The present invention provides 8-substituted 1,3,7-trialkylxanthines useful as A.sub.2 -selective adenosine receptor antagonists and compositions comprising such compounds. Examples of the 8-substituted 1,3,7-trialkyl xanthines include: ##STR1## In compound (a), R.sub.1, R.sub.3, and R.sub.7 are methyl and X is one to three substituents, which may be the same or different and selected from the group consisting of amino, C.sub.1 -C.sub.4 alkylcarbonylamino, carboxy C.sub.2 -C.sub.4 alkylcarbonylamino, halo, C.sub.1 -C.sub.3 alkyloxy, amino C.sub.1 -C.sub.4 alkyloxy, C.sub.1 -C.sub.4 alkyloxy carbonylamino, amino C.sub.1 -C.sub.4 alkenyloxy, isothiocyanato, and diazonium tetrafluoroborate. In compound (b), R.sub.1, R.sub.3, and R.sub.7 are methyl, R.sub..beta. is hydrogen or methyl, and X is selected from the group consisting of R, C(.dbd.O)OR, and C(.dbd.O)NH--R, wherein R is a C.sub.1 -C.sub.6 alkyl.

Xanthine alkaloids, which include caffeine, theophylline, and theobromine, are ubiquitously distributed in plants, such as the seeds of Coffea arabica and related species, the leaves of Thea sinensis, the seeds of Theobroma cacao, the nuts of the tree Cola acuminata, and the like. Extracts of these naturally occurring substances have been used throughout history as beverages and the pharmacologically significant nervous system stimulant properties of such concoctions have long been recognized.
Xanthine, itself, is 3,7-dihydro-1H-purine-2,6-dione. Chemically, therefore, xanthine and its derivatives are structurally related to uric acid and purine. Caffeine (1,3,7-trimethylxanthine), theophylline (1,3-dimethylxanthine), and theobromine (3,7-dimethylxanthine) represent the alkaloids most frequently associated with the expression "xanthine." However, numerous other xanthine derivatives have been isolated or synthesized. See, for example, Bruns, Biochem. Pharmacol., 30, 325-333 (1981), which describes more than one hundred purine bases and structurally related heterocycles with regard to adenosine antagonism, and Daly, J. Med. Chem., 25(3), 197-207 (1982).
Pharmacologically, the xanthines represent an important class of therapeutic agents. Observed pharmacological actions include stimulation of the central nervous system, relaxation of smooth muscle constrictions of the smaller bronchi and other smooth muscles, dilation of the small pulmonary arteries, stimulation of cardiac muscle with increased cardiac output, and the promotion of mild diuresis. Available evidence indicates that the therapeutic actions of these drugs involve blockade or antagonism of adenosine receptors.
It now has been recognized that there are not one but at least two classes of extracellular receptors involved in the action of adenosine. One of these has a high affinity for adenosine and has been found to be coupled to a number of secondary messenger systems, including inhibition of adenylate cyclase, inhibition of calcium entry, stimulation of potassium flux, and phosphoinositide metabolism (Van Galen et al., Medicinal Res. Rev., 12, 423-471 (1992)). This class has been termed by some as the A.sub.1 receptors. The other class of receptors has a low affinity for adenosine and has been found to elicit a range of physiological responses, including the inhibition of platelet aggregation (Lohse et al., Naunyn Schmiedeberg's Arch. Pharmacol., 337, 64-68 (1988)), dilation of blood vessels (Ueeda et al., J. Med. Chem., 34, 1340-1344 (1991)), erythropoietin production (Ueno et al., Life Sciences, 43, 229-237 (1988)), and depression of locomotor activity (Nikodijevic et al., J. Pharm. Exp. Therap., 259, 286-294 (1991)). This class has been termed the A.sub.2 receptors.
Subtypes of A.sub.2 receptors also have been identified. For example, A.sub.2a receptors, which are linked via G.sub.S guanine nucleotide binding proteins to the stimulation of adenylate cyclase, are present in high density in the striatum of the CNS. They are also present on platelets, pheochromocytoma cells, and smooth muscle cells. A.sub.2b receptors (Bruns et al., Mol. Pharmacol., 29, 331-346 (1986)) are found in the brain, fibroblasts, and intestines (Stehle et al., Mol. Endocrinol., 6, 384-393 (1992)).
Characterization of the adenosine receptors is now possible with a variety of structural analogues. Adenosine analogues resistant to metabolism or uptake mechanisms have become available. These are particularly valuable, since their apparent potencies are less affected by metabolic removal from the effector system than other adenosine analogues. The adenosine analogues exhibit different rank order of potencies at A.sub.1 and A.sub.2 adenosine receptors, providing a simple method of categorizing a physiological response with respect to the nature of the adenosine receptor. The blockade of adenosine receptors, i.e., antagonism, provides another method of categorizing a response with respect to the involvement of adenosine receptors.
Adenosine, perhaps, represents a general regulatory substance, since no particular cell type or tissue appears uniquely responsible for its formation. In this regard, adenosine is unlike various endocrine hormones. Furthermore, there is no evidence for storage and release of adenosine from nerve or other cells. Thus, adenosine is unlike various neurotransmitter substances.
Although adenosine can affect a variety of physiological functions, particular attention has been directed over the years to those functions that might lead to clinical applications. Preeminent has been the cardiovascular effects of adenosine, which lead to vasodilation and hypotension but which also lead to cardiac depression. The antilipolytic, antithrombotic, and antispasmodic actions of adenosine have also received some attention. Adenosine stimulates steroidogenesis in adrenal cells, probably via activation of adenylate cyclase, and inhibits neurotransmission and spontaneous activity of central neurons. Finally, the bronchoconstrictor action of adenosine and its antagonism by xanthines represents an important area of research.
Although theophylline and other xanthines, such as caffeine, are relatively weak adenosine antagonists, having affinity constants in the range of 10-50 micromolar, they owe many of their pharmacological effects to blockage of adenosine-mediated functions at the A.sub.1 and A.sub.2 receptor sites. The A.sub.1 -adenosine receptor is inhibitory to adenylate cyclase and appears involved in antilipolytic, cardiac, and central depressant effects of adenosine. The A.sub.2 -adenosine receptor is stimulatory to adenylate cyclase and is involved in hypotensive, antithrombotic, and endocrine effects of adenosine. Some xanthines, such as 3-isobutyl-1-methylxanthine, not only block adenosine receptors but also have potent inhibitory effects on phosphodiesterases.
The brochodilator effects of the xanthines, particularly, theophylline, have received considerable commercial attention and various preparations of theophylline, such as the anhydrous base or salts thereof, including sodium acetate, sodium benzoate, sodium salicylate, calcium salicylate, etc., are available as tablets, capsules, and elixirs including sustained released forms. Other related xanthines, such as dyphyllin, have received widespread usage. Caffeine has been used alone and in combination with other drugs in the treatment of headaches.
Many of the xanthines, however, such as theophylline, have undesirable side effects. Some of these side effects may be due to actions at sites other than adenosine receptors. It is also likely that some side effects are associated with blockade of the adenosine receptors, themselves. It appears that at least some of the side-effects caused by the adenosine receptor antagonists could be avoided by the development of more potent blockers of such receptors which, because of their increased blocking action, could be employed in lower doses and, thus, would be less likely to produce side-effects not associated with the adenosine receptor blockade. Additionally, where the therapeutic effect is due to blockade of one subtype of adenosine receptor, while side-effects relate to blockade of a different subtype of adenosine receptor, drugs, which are extremely potent at one receptor and substantially less active at another adenosine receptor, also should have a reduced likelihood of side-effects.
Potent and A.sub.2 -selective adenosine antagonists, suitable as pharmacological tools, have long been lacking. A.sub.2 -selective antagonists also may have application as therapeutic agents, e.g., in the treatment of Parkinson's disease (Schiffman et al., Drug Dev. Res., 28, 381-385 (1993)). The slightly selective, non-xanthine antagonist CGS 15943 was under development as an antiasthmatic (Jacobson et al., J. Med. Chem., 35, 407-422 (1992)). A low affinity antagonist, 3,7-dimethyl-1-propargylxanthine (DMPX), was reported to be A.sub.2 -selective but by less than one order of magnitude (Ukena et al., Life Sci., 39, 743-750 (1986)). It was relatively weak in blocking the in vivo effects of N.sup.6 -cyclohexyladenosine (CHA) compared to those of 5'-N-ethylcarboxamidoadenosine (NECA), suggesting some A.sub.2 selectivity. Several non-xanthine antagonists of the triazoloquinazoline class, including CGS 15943, are A.sub.2 -selective but also by only one order of magnitude (Francis et al., J. Med. Chem., 31, 1014-1020 (1988)). The locomotor activity of several members of this class was described previously (Griebel et al., NeuroReport, 2, 139-140 (1991)). A triazoloquinozaline derivative, CP66,713, was found to be 12-fold selective in binding assays at rat brain A.sub.2a - vs. A.sub.1 -receptors (Sarges et al., J. Med. Chem., 33, 2240-2254 (1990)). Low selectivity, interspecies differences in affinity, and low water solubility precluded extensive use of this compound. In one study, partial antagonism of A.sub.2 depression of locomotor activity was achieved in vivo using CP66,713 (Nikodijevic et al., 1991, supra). At the same dose CP66,713 had no effect on A.sub.1 depression of locomotor activity.
It was only recently that 8-styrylxanthines were reported as the first potentially useful compounds by Shimada et al. (J. Med. Chem., 35, 2342-2345 (1992)). These authors found that 8-styryl derivatives of 1,3-dimethylxanthines were the most selective for A.sub.2 receptors (selectivities greater than 5000-fold were reported), but the affinities of the corresponding 1,3-propyl analogues at both subtypes were greater (the most potent compound having a K.sub.i value of 7.8 nM at A.sub.2 receptors).
The literature is replete with examples of 8-substituted xanthine derivatives, including 8-substituted 1,3,7-trialkyl-xanthines, such as 8-styryl-1,3,7-trialkyl-xanthines. For example, U.S. Pat. No. 3,641,010 (Schweiss et al.) discloses 1,3-dialkyl-7-methyl-8-styryl-xanthines and describes the compounds as cerebral stimulants of the caffeine type. WO 92/06976 discloses alkyl-substituted 8-styryl-xanthines as selective A.sub.2 -adenosine receptor antagonists useful in the treatment of asthma and osteoporosis. 1-methyl-3,7-disubstituted-8-benzyl-xanthine derivatives useful in the treatment of asthma and bronchitis are disclosed in European Patent Application 0 215 736. The administration of methylxanthines, which are described as adenosine antagonists, to alleviate asystole and cardiac arrhythmia associated with resuscitation is described in U.S. Pat. No. 4,904,472. Various substituted theophyllines/xanthines are disclosed in U.S. Pat. Nos. 2,840,559, 3,309,271, 3,624,215, 3,624,216, 4,120,947, 4,297,494, 4,299,832, 4,546,182, 4,548,820, 4,558,051, 4,567,183, and 4,883,801, although only the U.S. Pat. Nos. 4,593,095, 4,612,315, 4,696,932, 4,755,517, 4,769,377, 4,783,530, 4,879,296, 4,981,857, 5,015,647, and 5,047,534 describe the disclosed compounds as potent adenosine receptor antagonists. Although a number of these references disclose xanthine compounds and describe them as "potent" and/or "selective" A.sub.2 -adenosine receptor antagonists, the potency and/or selectivity actually realized is not that significant. Accordingly, there remains a need for highly selective and potent A.sub.2 -adenosine receptor antagonists. Such compounds would reduce, if not completely eliminate, the side effects associated with A.sub.2 -adenosine receptor antagonists of reduced potency or selectivity by increasing blocking activity at one receptor, significantly, if not completely, eliminating blocking activity at non-A.sub.2 -adenosine receptors and, consequently, enabling the employment of reduced dosages.
An object of the present invention is to provide A.sub.2 -adenosine receptor antagonists of high potency and/or selectivity. Another object of the present invention is to provide a pharmaceutical composition comprising one or more of the present inventive adenosine receptor antagonists. Yet another object of the present invention is to provide a method of selectively antagonizing A.sub.2 adenosine receptors in a mammal in need of selective antagonism of its A.sub.2 adenosine receptors. By means of these objects, the present invention offers advantages over currently available A.sub.2 -adenosine receptor antagonists by providing A.sub.2 -selective adenosine receptor antagonists of increased potency and/or specificity. Accordingly, the present invention also provides an improved pharmaceutical composition comprising A.sub.2 -selective adenosine receptor antagonists and an improved method for the selective antagonism of A.sub.2 adenosine receptors in a mammal in need of such selective antagonism. The method, since it involves the use of A.sub.2 -selective adenosine receptor antagonists having increased potency and/or selectivity over currently available antagonists, is expected to reduce, if not completely eliminate, the side effects associated with the A.sub.2 -adenosine receptor antagonists by enabling the employment of reduced dosages.

The United States of America as represented by the Department of Health and Human Services


An asset monitoring and security system includes at least one asset assigned a unique identifier and operable wirelessly transmit an identification signal embodying the identifier. A data store maintains a list of the assets and privileges associated with the assets for authorized users of the assets. A control unit is adapted to receive identification signals from the assets and monitor positions of the assets within a defined area. The control unit communicates with the data store and is further operable to initiate an alarm event when privileges associated with a given asset for authorized users of the asset are exceeded. Each of the assets includes a lock-out mechanism that impedes use of the asset when the lock-out mechanism is activated. The control unit activates the lock-out mechanism of a given asset when the privileges associated with the asset for authorized users of the asset are exceeded.

Construction sites and other industrial job site locations are typically unsecured areas. Loss and theft of tools and other construction equipment is a common occurrence at such sites. For example, a job site may remain exposed to the threat of theft and/or vandalism at night. The tools and/or equipment at an industrial job site typically include very expensive power tools and construction materials. Theft of such items amounts to considerable losses and expenses. While contractors may utilize security guards or guard dogs to ensure the security of tools and other equipment at night, this is very expensive. Additionally, theft and/or vandalism may still occur during the day.
Contractors commonly utilize portable containers to house large numbers of tools and other construction equipment. For example, a contractor may utilize one or more metallic gang boxes. While the tools and/or equipment are not being used, a contractor may attempt to prevent unauthorized access to the insides of the containers. For example, the contractor may utilize devices such as locks, chains, and/or straps to secure the containers. However, such containers may remain open for a long time while the tools and equipment are being used. Therefore, such devices do not guarantee the security of the tools and equipment at all times of the day. Additionally, it is difficult to keep track of and maintain an inventory of tools and equipment on a job site.
In one approach, a contractor employs a rigorous check-in/check-out process with all of the tools and equipment on a job site. However, this requires additional time, personnel, and expenses. Alternatively, a contractor may take an inventory of tools and equipment at the end of a day. Depending on the number of tools and equipment at the job site, this can be very time consuming and expensive. Additionally, a contractor may not notice that tools or equipment are damaged and/or missing until the end of the day.

Wireless asset monitoring and security system


The invention is directed to an antenna assembly which, when a rod antenna unit is retracted in the radio housing, permits transmission and reception with no influence thereon by the retracted rod antenna unit and which resonates with two frequencies when the rod antenna unit is in its extended position. Feeding metal pipe (9) connected to a secondary antenna (14) formed by a helical antenna element has contact springs (18) for elastic contact with a rod antenna unit (2). When the rod antenna unit (2) is retracted position, the contact springs (18) contact an insulating cover (11) wrapped around the rod antenna unit (2), electrically disconnecting a primary antenna (20) from the feeding metal pipe (9). Hence, only the secondary antenna (14) serves as an antenna without being affected by the primary antenna (20). When the rod antenna unit (2) is in its extended position, the contact springs (18) make electrical contact with a connector terminal (22) electrically connected to the primary antenna (20), thus connecting the primary antenna (20) and the secondary antenna (14) to the feeding hardware (9).

Portable radios, such as portable telephones, are usually designed to hold the antenna at its retracted position in their housing on the move to make them as compact in size as possible.
With the antenna retracted in the radio housing, however, portable radios of this kind cannot accomplish satisfactory transmission and reception, and the sensitivity for receiving call signals is particularly low. Hence, it is necessary in the prior art to hold the antenna in its extended position while awaiting a call.
As a solution to this problem, there has been developed an antenna unit which permits transmission and reception even with a rod antenna unit retracted in the radio housing, as described in Japanese Pat. Laid-Open Gazette No. 245603/91.
This conventional antenna assembly will be described below with reference to FIGS. 10 to 12.
As shown in FIG. 10, the antenna assembly has its feeding metal pipe mounted on the top of a housing 101 of a portable radio 110 and its rod antenna element 103 adapted to be pushed into and drawn out of the radio housing 101 through a through hole bored in the feeding metal pipe 102.
The rod antenna element 103 carries at its tip a helical antenna element 104. Since the rod antenna element 103 and the helical antenna 104 each have a length equal to the quarter wavelength of a radio signal of a frequency f, a half-wave antenna is formed when the rod antenna element 103 is drawn out of the radio housing 101 to its extended position.
In this state, the lower end portion of the rod antenna element 103 makes electrical contact with the feeding metal pipe 102, which is connected via a feeder 105 to a transmitter-receiver circuit (not shown) on a circuit board 106.
When the rod antenna element 103 is retracted in the radio housing 101, the junction between the rod antenna element 103 and the helical antenna 104 makes contact with the feeding metal pipe 102 and the helical antenna element 104 projecting out of the radio housing 101 functions as a quarter-wave antenna.
Accordingly, even with the rod antenna element 103 retracted in the radio housing 101, the portable radio 110 can transmit and receive radio signals of the frequency f.
As described above, the conventional antenna unit permits transmission and reception even when the rod antenna element 103 is retracted in the radio housing 101, but the rod antenna element 103 is still held in contact with the feeding metal pipe 102; hence, when the portable radio 110 transmits, high-frequency signals also emanate from the rod antenna element 103 and cause noise, adversely affecting respective circuits in the radio housing 101.
Also when receiving with the rod antenna element 103 retracted in the radio housing 101, the wavelength of the helical antenna element 104 deviates from the quarter wavelength under the influence of the rod antenna element 103, impairing the sensitivity to incoming signals.
To avoid this, in the above prior art example the lower end portion 103 a of the rod antenna element 103, when retracted, is held in contact with a grounding segment 107 as shown in FIG. 13, by which the impedance viewed from the feeding metal pipe 102 is made infinity, preventing the rod antenna element 103 from functioning as an antenna.
To ground the lower end portion 103 a of the rod antenna element 103, however, it is necessary to provide an extra grounded circuit as well as the grounding segment 107. This inevitably introduces complexity in the antenna structure.
Further, since the rod antenna element 103, when retracted in the radio housing 101, is supported at its upper end by the feeding metal pipe 102 alone, the lower end portion 103a is unstable in position and fail to contact the grounding segment 107.
Moreover, with an increase in the frequency f of the radio signal for transmission and reception by the portable radio 110, the influence of R and L components of the feeding metal pipe 102 and other parts becomes increasingly nonnegligible. It is not an easy task to make the resonance frequency of the helical antenna element 104 match the frequency f of the radio signal by adjusting the length of the helical antenna element 104.
Additionally, even when the rod antenna element 103 is in its extended position as shown in FIG. 11, only one resonance frequency is available; hence, when the receive frequency and the transmit frequency differ as in the case of the portable telephone, high sensitivity for reception and large radiated power for transmission cannot be obtained.
Incidentally, there is also known antenna unit of the type that permits transmission and reception only by the helical antenna element 104 projecting out of the radio housing 101 but as is the case with the above-mentioned prior art example, this antenna unit does not provide two resonance frequencies either, and hence it fails to obtain high sensitivity for reception and large radiated power for transmission.

Extendable rod antenna and helical antenna with frequency adjusting conductor


A substrate for an integrated circuit package. Located on a bottom surface of the substrate are a plurality of contact pads. Solder balls are attached to the contact pads and then reflowed to mount the package to a printed circuit board. The bottom surface of the substrate has a first layer of solder mask. The first layer has a plurality of first openings which expose at least a portion of each contact pad. Adjacent to the first layer of solder mask is a second layer of solder mask which has a plurality of second openings that also expose the contact pads. The diameter of each second opening is larger than the diameter of each first opening. The openings may be created by etching the layers of solder mask. The etching process typically creates in annular lips in the solder mask openings. The larger second openings reduce the stress risers of the solder balls created by the inner lips of the solder mask.

1. FIELD OF THE INVENTION
The present invention relates to an integrated circuit package.
2. BACKGROUND INFORMATION
Integrated circuits are typically assembled into packages that are soldered to printed circuit boards. There are many types of integrated circuit packages including ball grid array (BGA) packages.
FIG. 1 shows a BGA package of the prior art. The package includes a substrate 1 that supports an integrated circuit 2. The integrated circuit 2 is typically wire bonded to bond fingers (not shown) on the top surface of the substrate. The bottom surface of the substrate 1 has a plurality of contact pads 3 that are electrically connected to the integrated circuit 2 by the bond fingers and vias that extend through the substrate 1. Solder balls 4 are attached to the contact pads 3 and then subsequently reflowed to mount the package to a printed circuit board (not shown).
As shown in FIG. 2, layers of solder mask 5 are applied to the bottom surface of the substrate 1 and then etched in certain locations to expose the contact pads 3. The solder mask 5 prevents shorting between the solder balls 4 when the solder is reflowed onto a printed circuit board. It has been found that the etching processes creates an annular lip 6 in the solder mask 5. The lip 6 creates a stress riser in the solder joint which may induce a crack 7 in the solder. The crack 7 may lead to a failure in the solder joint and render the integrated circuit package inoperable. It would be desirable to provide a BGA integrated circuit package and a process for forming the package that reduces the stress risers in the solder joints.

Integrated circuit package substrate with stepped solder mask openings


An electronic ballast (100) for powering at least one gas discharge lamp (10) comprises an inverter (300), an output circuit (400), and a switching circuit (500). Output circuit (400) includes a resonant inductor (440) and a resonant capacitor (460). Switching circuit (500) is coupled between the resonant capacitor (460) and an AC ground node such as circuit ground node (60), and is operable to effectively disconnect the resonant capacitor (460) after the lamp (10) ignites, thereby eliminating circulating current and significantly enhancing ballast energy efficiency. Switching circuit preferably comprises an electronic switch (600) and a pulse circuit (700), and optionally includes a diode matrix for use in ballasts for powering two or more lamps. In one embodiment, pulse circuit (800) monitors for lamp replacement and provides automatic ignition of a replaced lamp.

A number of existing electronic ballasts for gas discharge lamps include an inverter and a series resonant output circuit that provide a high voltage for igniting the lamps and a high frequency current for efficiently powering the lamps.
A series resonant output circuit draws a certain amount of input current from the inverter. Apart from that portion of the input current that is needed for powering the lamps, a considerable portion of the input current is reactive in nature and is commonly referred to as "circulating current." In "driven" type inverters that do not utilize resonant current feedback for commutating the inverter switches, the circulating current serves no useful purpose after the lamps are ignited and has the undesirable effect of increasing the power dissipation in the resonant circuit and in certain inverter components such as the inverter switches.
The power losses due to circulating current degrade ballast energy efficiency and reliability, and are a significant impediment to efforts to reduce the physical size, weight, and cost of the ballast itself. These problems are particularly acute for higher power ballast circuits, such as those for driving three or four lamps, for which miniaturization efforts are highly contingent upon reduced power losses in the inverter and output circuit.
In addition to the problem of circulating current, many existing electronic ballasts that employ a driven type inverter have the disadvantage of requiring special protection circuitry to prevent self-destruction of the inverter and resonant output circuit in the event of lamp failure or lamp fault conditions. Such protection circuitry is often very extensive and quite complex, and adds considerably to the resulting physical size and cost of the ballast.
It is therefore apparent that a need exists for an electronic ballast that substantially reduces or eliminates circulating current and that lessens or obviates the need for extensive protection circuitry. Such a ballast would be significantly more energy efficient than existing ballasts, would be amenable to reductions in size, weight, and cost, and would therefore represent a considerable advance over the prior art.


A charge pump circuit is provided which outputs a high voltage by using a boosting circuit with a smaller number of stages. A diode is used to give a back-gate voltage for a MOS transistor composing the charge pump circuit, thereby minimizing a reduction in a boosted voltage due to an increase in the threshold voltage of the MOS transistor. In addition, a second MOS transistor is provided between the back gate of the MOS transistor and the ground (GND) such that in-phase clock signals are inputted to the gate of the second MOS transistor and the capacitor thereof.

1. Field of the Invention
The present invention relates to a charge pump circuit for voltage boosting.
2. Description of the Related Art
As a conventional charge pump circuit, there has been known a circuit as shown in FIG. 14 (see, e.g., JP 2718375 B (FIG. 11)).
Specifically, n-channel MOS transistors MN1 to MN5 each having the gate and drain thereof connected to each other are connected in series and capacitor elements C1 to C4 are connected individually to the respective connection points between the gates and drains of the MOS transistors MN2 to MN5. To the CLK and CLKB terminals provided at the other end of the capacitor elements, voltages VCLK and VCLKB having phases opposite to each other are inputted, as shown in FIG. 15.
Each of the gate and drain of the n-channel MOS transistor MN1 is connected to a power source VDD and an output OUT of the boosting circuit is extracted from the source of the MOS transistor MN5. A voltage at a connection point among the source of then-channel MOS transistor MN1 and the gate and drain of the n-channel MOS transistor MN2 is assumed to be V12. When the voltage VCLK is initially in the "L", i.e., GND state, the voltage V12 is given by the expression (1):V12=VDD−Vtn1   (1).
Next, when the voltage VCLK comes into the "H", i.e., VDD state, the voltage V12 is given by the expression (2):V12=2*VDD−Vtn1   (2)wherein Vtn1 represents the threshold voltage of the n-channel MOS transistor MN1. A voltage at a connection point among the source of the n-channel MOS transistor MN2 and the gate and drain of the n-channel MOS transistor MN3 is assumed to be V23. When the voltage VCLK is in the "H", i.e., VDD state, the voltage V23 is given by the expression (3) (the voltage VCLKB at that time is in the "L" state):V23=2*VDD−Vtn1Vtn2   (3)wherein Vtn2 represents the threshold voltage of the n-channel MOS transistor MN2. Next, the voltage VCLK comes into the "L" state, i.e., the voltage VCLKB comes into the VDD state. A voltage at the connection point among the source of the n-channel MOS transistor MN2 and the gate and drain of the n-channel MOS transistor MN3 is assumed to be V23. The voltage V23 is given by the expression (4):V23=3*VDD−Vtn1Vtn2   (4).
Finally, a voltage at the output terminal of the conventional charge pump circuit having a four-stage configuration shown in FIG. 13, i.e., the source voltage V5 of the n-channel MOS transistor MN5 is given by the expression (5):V5=5*VDD−Vtn1Vtn2−Vtn3−Vtn4−Vtn5   (5)wherein Vtn3, Vtn4, and Vtn5 each represent the threshold voltages of the n-channel MOS transistors MN3, MN4, and MN5, respectively.
In FIG. 14, the substrate (well) of each of the n-channel MOS transistors MN1 to MN5 is connected to the ground (GND). In that case, due to the back-gate effect, the values of the respective threshold voltages Vtn1 to Vtn5 of the n-channel MOS transistors MN1 to MN5 increases to be higher than the values of the threshold voltages in the absence of the back-gate effect. Accordingly, the voltage V5 at the output terminal, which is given by the expression (5), decreases.


The present invention relates to an ionic multi-block copolymer composition comprising tri-block copolymers having a polypropyleneoxide or polybutyleneoxide block positioned between two polyethyleneoxide blocks and the tri-block copolymers are connected through dicarboxylic acid linkages forming a multi-block copolymer having a weight average molecular weight of more than 40,000 Dalton. The higher weight average molecular weight enables the hydrolgel formed from the multi-block copolymer of the present invention to maintain its gel status for more than several days.

1. Field of the Invention
The present invention relates to a biodegradable multi-block copolymer having an improved release profile and control of the release rate for various drugs. Particularly, the present invention provides a multi-block copolymer comprising ABA-type tri-block copolymers wherein the A block is polyethyleneoxide and the B-block is a polypropyleneoxide or polybutyleneoxide block, and wherein the resulting PEO-PPO (or PBO)-PEO blocks are connected through dicarboxylic linkages which can be hydrolyzed in the living body.
2. Description of the Related Art
Hydrogels have biocompatible properties and thus have been widely used as drug carriers. A therapeutic agent is entrapped within the crosslinked hydrogel matrix and upon release passes through interstices in the matrix.
Early drug delivery systems used gels having thermoplastic properties. The thermoplastic system involved the formation of a polymeric solution in solvents. Before injection into the body, a drug was added to the polymeric solution. After injection the polymeric solution quickly formed a gel by exposure to body fluids. However, the early drug delivery systems had problems in that they could be toxic and irritating to the body due to the presence of the organic solvent.
Recently, a gel drug delivery system using aqueous solutions has been developed. The system uses a block copolymer which is composed of polyethylene oxide and polypropylene oxide. The polyethylene oxide and polypropylene oxide copolymers, when at sufficient concentration and temperature, absorb water to form a gel (U.S. Pat. Nos. 4,188,373, 4,478,822 and 4,474,751). An example of the polymeric solution is known as a poloxamer and is commercially available. The poloxamer is a tri-block copolymer of PEO-PPO-PEO wherein PEO is a polyethylene oxide block and PPO is a polypropylene oxide block (PPO). The poloxamer has a molecular weight ranging from 9,840 to 14,600 Daltons. However, the poloxamer-based gel is non-biodegradable. In order to undergo phase transition under physiological conditions, a poloxamer polymer solution having a concentration of more than 18 to 20% is necessary. However, such a concentrated solution has a very high viscosity in the liquid phase and thereby may induce unfavorable reactions in the living body. Although when injected into a living body, it is quickly transformed into a gel, the gel status can only be maintained for several hours and therefore it has limited application as a drug delivery system.
In order to solve these problems, Sosnik et al. synthesized the compound of formula 1, wherein poloxamer 407 blocks are connected by a urethane linkage by reacting poloxamer 407 and hexamethylene diisocyanate (Winter Symposium & 11th International Symposium on Recent Advances in Drug Delivery Systems, 2003 Controlled Release Society, #117)).[PEO—PPO—PEO—CO—NH—(CH2)6—NCO]p, wherein p is 4.  Chemical formula 1
It is disclosed in Sosnik that the compound with the chemical formula 1 has a viscosity several times higher than poloxamer 407 in the case of a 17% aqueous solution and a significantly longer time in maintaining its gel status at high temperatures. However, there are problems with the polymer in that it is non-biodegradable and has a molecular weight of more than 50,000 Daltons and thus excretion from the body is difficult.
X. Zhao et al. discloses a biodegradable polymeric composition including the poloxamer 407 of chemical formula 2 (30th annual meeting and exhibition of the controlled release society, Glasgow, Scotland, Jul. 19-23, 2003). In preparation of the polymer, a poloxamer 407 is reacted with disuccincimidyl carbonate (DSC), so that poloxamer 407 blocks are connected through carbonate linkages as shown in Chemical Formula 2.HO—[PEO—PPO—PEO—C(═O)—O]n—H, wherein the average number of n is 3.   Chemical formula 2
U.S. Patent Application No. 20030187148 discloses a polymeric composition wherein poly(hydroxyl carboxylic acid) blocks are introduced into both terminal ends of poloxamer 407 and the resulting penta-blocks are chain-extended through a HDI (hexamethylene diisocyanate) linker. However, the polymer is non-biodegradable because urethane linkages are non-biodegradable.
U.S. Pat. No. 6,348,558 discloses a biodegradable polymer wherein at least two polyalkylene oxide oligomers are connected through hydrolytic carbonate linkers.
However, the above disclosed polymers only have hydroxyl groups at the terminal ends and the release rate of a drug from the gel depends only on the diffusion rate which is determined by the viscosity of the gel. Thus it is impossible to control the release rate of the drug.
Therefore, there is a need for a biodegradable polymeric composition which has low toxicity and an improved release profile, and can control of the release rate of various drugs.

Biodegradable multi-block polymeric composition capable of sol-gel transition and pharmaceutical composition comprising the same


An example of a system for delivering neurostimulation energy to a patient using a plurality of electrodes may include a stimulation circuit and a sensing circuit. The stimulation circuit may be configured to deliver the neurostimulation energy using stimulation electrodes selected from the plurality of electrodes and to control the delivery of the neurostimulation energy. The sensing circuit may be configured to receive one or more neural signals from sensing electrodes selected from the plurality of electrodes and may include a signal processing circuit. The signal processing circuit may include a detection circuit and an analysis circuit. The detection circuit may be configured to detect one or more attributes of neural responses from the received one or more neural signals. The analysis circuit may be configured to analyze the detected one or more attributes of the neural responses for one or more indications of a neurodegenerative disease.

Neurostimulation, also referred to as neuromodulation, has been proposed as a therapy for a number of conditions. Examples of neurostimulation include Spinal Cord Stimulation (SCS), Deep Brain Stimulation (DBS), Peripheral Nerve Stimulation (PNS), and Functional Electrical Stimulation (FES). Implantable neurostimulation systems have been applied to deliver such a therapy. An implantable neurostimulation system may include an implantable neurostimulator, also referred to as an implantable pulse generator (IPG), and one or more implantable leads each including one or more electrodes. The implantable neurostimulator delivers neurostimulation energy through one or more electrodes placed on or near a target site in the nervous system. An external programming device is used to program the implantable neurostimulator with stimulation parameters controlling the delivery of the neurostimulation energy.
Patients treated with implantable neurostimulation system may have nerve diseases that may or may not be targeted by the treatment delivered from the system. For example, many patients receiving SCS or DBS have neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, peripheral neuropathies, diabetic neuropathy, chronic pain, and glaucoma. A patient diagnosed with such a neurodegenerative disease may need to be treated by neurostimulation deliverable using the implantable neurostimulation system and/or one or more other therapies.

Neurostimulation system with neurodegenerative disease detection

Boston Scientific Neuromodulation Corporation


Personnel and vehicle collision avoidance devices configured to be used in collision avoidance systems are disclosed. The collision avoidance devices are configured to be aware of the context (e.g. position, location, state, status, etc.) in which the person or vehicle is. This awareness allows the devices to avoid transmitting non-hazardous proximity warnings when the context does not warrant the transmission of proximity warnings, and to transmit special critical proximity warnings when the context warrants the transmission of such proximity warnings. To detect the context, the devices comprise one or more context-awareness mechanisms (e.g. user input interfaces, sensors, infra-red receivers, etc.), each of which being capable of detecting one or more particular contexts. A collision avoidance system comprising these personnel and vehicle collision avoidance devices is also presented.

Numerous underground mines are developed and are in operation throughout the world. Though safety measures are typically deployed to prevent accidents involving collisions between vehicles, machines, personnel and/or obstacles in these mines, accidents unfortunately happen on a regular basis.
To minimize the risks of collisions, collision avoidance systems are increasingly deployed. These systems come in various configurations and use various technologies, all with their inherent advantages and drawbacks.
One type of collision avoidance systems that is becoming popular in underground mine environments involves the use of typically three types of collision avoidance devices configured to be respectively mounted to vehicles, personnel, and obstacles. These devices are configured to form ad hoc peer-to-peer wireless networks when they are within communication range of each other and can therefore transmit proximity warnings to each other if proximity is detected from various sensors based on received signal strength, time-of-flight, radar, lasers or magnetic fields.
However, even if these types of collision avoidance systems can provide valuable warnings to enhance safety at mine sites, it remains that these systems do not take into account the context in which the person or the vehicle carrying the device is before transmitting proximity warnings. Hence, these systems often cause the transmission of proximity warnings even though the context does not warrant it.
Non-limitative examples of non-hazardous proximity warnings include the notification to a vehicle operator of personnel in the area when personnel are passengers in the same or another vehicle, the notification to a vehicle operator of personnel in the area when personnel are in a refuge or other sheltered area, the notification to a vehicle operator of vehicles in the area when the vehicles are parked in a garage, and the notification to personnel of a vehicle in the area when the vehicle is stopped or non-operating.
Unfortunately, current collision avoidance systems have a very limited ability to distinguish between non-hazardous situations, hazardous situations, and very hazardous or critical situations, and therefore often issue proximity warnings in all these situations.
Understandably, the transmission of proximity warnings for non-hazardous situations causes problems. For example, vehicle operators bombarded by undistinguished proximity warnings will be unable to distinguish between very hazardous, hazardous and non-hazardous situations and will tend to ignore most warnings, thereby causing preventable accidents.
Hence, in view of the foregoing, there is a need for an improved collision avoidance system, and related devices and methods, purpose-built for underground mines which will at least mitigate some of the shortcomings of systems using collision avoidance devices.

Context-aware collision devices and collision avoidance system comprising the same


This invention relates to a fluid sealing mechanism for the inside diameter and or the outside diameter of a piston-cylinder arrangement. This device results in zero seal leakage path with low differential seal pressure required using only one piston ring, one ring groove, and very loose dimensional tolerances required on both the ring and related groove. This yields an inexpensive more positive seal for fluid piston-cylinder configuration used in industrial, commercial, and personal use.

This invention refers to an inexpensive, zero leakage path, low differential pressure seal for a piston-cylinder arrangement. More specifically it refers to a low speed or high speed reciprocating piston-cylinder zero leakage path seal for fluid compressors, fluid motors, fluid pumps and internal combustion engines.
It is known from prior art to obtain zero leakage path in a piston-cylinder arrangement use of an "O" ring seal, lip seal, or the like is used. However, present technology limits their use to slow speed reciprocating piston-cylinder configurations.
Present technology for high speed reciprocating piston-cylinder configurations is based on controlled and or minimal leakage seal of the fluid past a split ring set into a groove of a piston reciprocating in a cylinder.
I have invented an art with a zero leakage path which becomes more positive with the more pressure it is subjected to. Prior art has leakage increasing with fluid pressure acting on the seal, whereas, this invention becomes a more positive seal the more fluid pressue it is subject to, and since there is no leakage path, any leakage encountered is from the cylinder well and the ring face imperfections of the various sealing surfaces.
Prior art has two basic losses associated with it. The first being the friction loss of the ring scraping against the cylinder wall. This friction is caused by the designed radial tension in the ring to seal said pressurized fluid and additional radial tension put on the ring by the pressurized fluid itself. This friction loss increases as the face width of the ring increases. The ring face width is dependent upon the pressure and more specifically the temperature variations of the pressurized fluid and the configurations of the face proper which causes for width. As pressurized fluid temperatures increase the ring face width increases to avoid burn-thru (i.e. the Challenger effect). As ring face width increases friction increases between the ring and cylinder. Yet, functionability of the art requires the friction loss to properly seal.
Prior art minimized pressurized fluid leakage by increasing the number of rings used, special design considerations to the outside diameter face of the rings, ring juncture design enhancements, etc. Increasing the number of rings to stop pressurized fluid leakage and/or scrape oil increases the frictional loss. However, all prior art reduces but does not eliminate total leakage paths. Leakage occurs past the face of the ring against the cylinder wall as detailed above, thru the juncture of the gap of the ring ends, and behind the ring and its groove. Additionally, in four cycle internal combustion engines the compression rings axial movement, though ever so minute, acts as a pump of the crankcase under the ring and oil into the combustion chamber.
The second loss associated with prior art is the actual leakage associated with the piston-ring-cylinder seal. Assuming there is no leakage by the face of the ring and the cylinder due to prior art considerations as mentioned then leakage loss occurs thru the gap associated with the ends of the ring. Likewise, said gap leakage is very dependent upon the temperature and pressure of the fluid. Additionally, another leakage loss occurs in a path behind the ring and its respective groove.
This invention stops the leakage behind the ring and its groove and thru the ring gap. When said leakage is inhibited then at higher temperature applications of the pressurized fluid the "hot spot burn thru" (Challenger effect) is also eliminated thus reducing the ring face thicknesss to mechanical considerations only.
The result being a sizable reduction in frictional loss of ring-cylinder friction since only one new art ring is required and a sizable gain in efficiency from increased compression of same due to essentially zero blow-by.
Using this new art on a pressurized liquid fluid application a sustained vacuum draw of 27 inches of mercury is demonstrated repeatedly over a sustained period with high usage of the new art seal. Said seal dimensional characteristics of the ring, ring groove, and the cylinder are considered extremely loose compared to prior art requirements and manufacturing capabilities.
Likewise, applying the new art to internal combustion engines has resulted in the use of only one new art ring versus two or more compression rings in typical two cycle internal combustion engines. Tests show a considerable horse power and compression increase in said engine due to reduced ring friction (via reduction in ring face width and number of rings) and near zero blow-by, thereby increasing horse power availability for the same amount of gas consumed. These results were observed in two cycle engines of size varying from single piston air cooled to a large industrial six cylinder water cooled diesel engine.
The same results as observed in the two cycle internal combustion engine were observed in four cycle engines plus additional considerations. As in the two cycle engine, the four cycle application of the new art required only one compression ring versus two rings required in prior art. Additionally, prior art necessitated an oil wipe ring for four cycle engines. The new art does not need such a ring.
Tests show that the new art single ring facilitates and improves the function that in prior art, two compression rings are required to accomplish on four cycle engines. Also, the new art eliminates pumping of crankcase oil by axial movement of prior art rings either thru the gap and or behind the prior art rings. Additionally, because of even and floating radial loading of the new art ring, it wipes crankcase oil off the cylinder wall with no leakage thru a gap or behind the ring for there is no passage. Hence, the new art eliminates the need for an oil wipe ring on four cycle engines.
With the elimination of the need for a second (or more) compression ring in two cycle internal combustion engine and the elimination of the need for a second compression ring and oil wipe ring used in standard practice in a four cycle internal combustion engine, the opportunity exists to move the wrist pin closer to the crown of a piston with many associated advantages such as, horse power, compression, efficiency, weight, mass, volume, etc.
Prior art, be it for internal combustion engines, pumps, motor, compressors, etc. for high speed reciprocating piston-piston ring-cylinder configurations have the piston centered in the cylinder by the piston skirt. This prior art configuration necessitated a specific length of skirt in addition to skirt lengths required for compression ring(s), oil wipe ring and wrist pin. The quantity of specific rings needed being dictated by the application.
Prior art rings could be floating to an axis of the cylinder which is different than the axis of the piston skirt. Thus, causing for increased friction and blow-by all causing an efficiency loss.
The new art has the single ring centering the piston head within the cylinder. Hence, the piston and piston ring are on the same cylinder axis regardless how much said axis varies in its length.
The new art allows for oval, square, rectangular piston-piston ring-cylinder configurations.
Additionally, it has been observed that in internal combusion engines that with zero blow-by choking is no longer required or vastly reduced because the charge is being maintained in the cylinder it gives the engine immediate starting capabilities.
Prior art for high speed reciprocating piston cylinder arrangements have a paradox of:
If thermal expansion is not detrimental, then a gapless ring is possible. However, friction wear and no gap are causes for ring face blow-by.
If thermal expansion requires a gap in the ring, then blow-by is present initially. The new technology is self-adjusting in either of the aforementioned paradoxes.
Prior art requires the piston rings to be made of material with radial elasticity for sealing considerations. This necessity eliminated materials with optimun temperature, weight, durability, etc. characteristics from consideration as ring material. The new art technology accepts sealing band materials with no radial elasticity, but doesn't require same for Radial elasticity is provided by the new art seal expander. The drawings show the ring groove perpendicular to the piston and/or cylinder centerline. It is realized it may be desirable for manufacturing, or oil scraping from cylinder walls in four-cycle internal combustion engines, and/or ring sliding over cylinder ports in two-cycle internal combustion engines to angle the ring groove of the piston relative to the cylinder wall or passage centerline to meet specific requirements.
In accordance with certain of its objects, my invention relates to a sealing assembly for internal combustion engines, compressors, fluid motors, fluid pumps and other devices which require sealing which comprises: an assembly of members to be sealed, one member axially centered over another member with a clearance passage between the assembled members, capable of allowing the assembly of members to move in relation to one and the other; said clearance passage being capable of transmitting a fluid under pressure; one of the members having one or more grooved openings to the clearance passage between the assembly of members, said groove openings having side walls and a bottom; positioned within and at the bottom of said groove openings is a continuous, resilient, elasteromeric, expander seal; positioned with said groove openings and biased to said expander seal is one or more gapped sealing bands. The one or more sealing bands have an inclined surface that engages the expander seal and said incline surface is in the direction of a fluid source under pressure; a means for actuating the fluid under pressure whereby the fluid under pressure engages the one or more sealing bands and engages and activates the expander seal causing said expander seal to pressurize and expand against the inclined surface of the one or more sealing bands thereby forcing said one or more sealing bands against the ungrooved member and against wall of said groove opening thereby causing a seal.
Further, in accordance with certain of its objects, my invention relates to a sealing assembly for internal combustion engines, compressors, fluid motors, fluid pumps and other devices which require sealing which comprises: an assembly of members to be sealed, one member axially centered over another member with a clearance passage between the assembled members, capable of allowing the assembly of members to move in relation to one and the other; said clearance passage being capable of transmitting a fluid under pressure; one of the members having one or more grooved openings to the clearance passage between the assembly of members, said groove openings having side walls and a bottom; positioned within and at the bottom of said groove openings is a continuous, resilient, elasteromeric, expander seal; positioned within said groove openings and biased to said expander seal is one or more gapped sealing bands; the one or more sealing bands have a flat surface that engages the expander seal and an axial porous force which engages the one or more sealing bands and engages the side wall of the groove opening, said groove wall in the direction of a fluid source thus pushing the one or more sealing bands against the other groove wall; a means for actuating the fluid under pressure whereby the fluid under pressure engages the one or more sealing bands and engages and activates the expander seal causing said expander seal to pressurize and expand against the flat surface of the one or more sealing bands thereby forcing said one or more sealing bands against the ungrooved member and against the wall of said groove opening thereby causing a seal.
Still further, in accordance with certain of its objects, my invention further relates to a sealing assembly for fluid cylinders, internal combustion engines, compressors, fluid motors, fluid pumps and other devices which require sealing which comprises: an assembly of members to be sealed, one member axially centered over another member with a clearance passage between the assembled members, capable of allowing the assembly of members to move in relation to one and the other; said clearance passage being capable of transmitting a fluid under pressure; one of the members having one or more grooved openings to the clearance passage between the assembly of members, said groove openings having side walls and a bottom; positioned within and at the bottom of said groove openings is a continuous, resilient, elasteromeric, expander seal; positioned within said groove openings and biased to said expander seal is one or more gapped sealing bands; the one of more sealing bands have a flat surface that engages the expander seal and an axial porous force which engages the one or more sealing bands and engages one side wall of the groove opening, thus pushing the one or more sealing bands against the other groove wall, both groove walls having serrations and/or protrusions allowing fluid passage; a means for actuating the fluid under pressure bi-directionally whereby the fluid under pressure engages the one or more bands and engages and activates the expander seal causing said expander seal to pressurize and expand against the flat surface of the one or more sealing bands thereby forcing said one or more sealing bands against the ungrooved member and either against one wall of said groove opening thereby causing a seal, or against the force which is against said groove opening thereby causing a seal.


An apparatus for inspecting a sample using a scanning electron microscope includes a sample stage, a first electron-optical system to scan an electron beam of a first beam current on the sample, a second electron-optical system to scan an electron beam of a second beam current smaller than the first beam current on the sample, a mechanism to move the sample stage, a detector provided in each of the first and second electron-optical systems to detect a secondary electron. The first electron-optical system is operable in a first mode and the second electron-optical system is operable in a second mode with higher resolution than that of the first mode. In the first mode, the sample is observed while the sample stage is moved continuously, and in the second mode, the sample is observed by detecting a secondary electron using the detector while the sample stage is held stationary.

The present invention relates to a circuit pattern inspecting instrument and a circuit pattern inspecting method, and in particular to an instrument and a method for inspecting circuit patterns on a wafer or the like in a semiconductor device manufacturing process.
For a comparison testing method of detecting defects in circuit patterns formed on a wafer in a semiconductor device manufacturing process, there has been put to practical use an instrument for inspecting the wafers by comparing images of two or more LSI circuits of the same pattern formed on a single wafer with each other.
Particularly, instruments for pattern comparison and pattern inspection using an electron beam are described in Japanese Patent Application Laid Open No. Sho 59-192943, J. Vac. Sci. Tech. B, Vol. 9, No. 6, pp. 3005-3009 (1991), J. Vac. Sci. Tech. B, Vol. 10, No. 6, pp. 2511-2515 (1992), SPIE (The International Society for Optical Engineering) Vol. 2439, and Japanese Patent Application Laid Open No. Sho 5-258703. In those instruments, for obtaining a practical throughput it is necessary to acquire images at a very high speed, and at least 100 times (at least 10 nA) the electron beam current with an ordinary scanning electron microscope is used to ensure the sufficient S/N ratio of the images acquired at high speed as well as a practical inspection speed. The electron beam diameter is spread fairly wider than that in an ordinary scanning electron microscope and is about 0.05 to 0.2 μm. This is because of an increase in chromatic aberration caused by widening of the electron energy width which is attributable to a large beam current, a limitation to brightness of an electron gun and a limitation by the Coulomb effect.
The images formed by such an electron optic system are fed to an image processing unit, in which images of the adjacent circuits of the same pattern are compared with each other for inspection. If a portion having different brightness occurs between the compared images, the portion is regarded as a defect and coordinates of the portion are stored.
With the above configuration, it is possible to detect even a defect as small as 0.1 μm or so.
Further, instruments for inspecting defects in semiconductor by reducing the energy of the electron beam with a voltage applied to a sample and an electrode disposed close to the sample are disclosed in Japanese Patent Application Laid Open Nos. Hei 7-78855, 9-181139/, 10-19538, 10-27834, 10-27835, and 11-25901. But they do not refer to an instrument having a review function to be described later, or an instrument having a combination of the review function and an energy analyzing function to be described subsequently.

Method of inspecting a circuit pattern and inspecting instrument


This invention discloses a method for migration between a permanent connection and a switched connection in a transmission network. The method comprises the steps of: the ingress node of the current connection receiving a message of connection migrating request; forwarding the message of connection migrating request node by node starting from the ingress node in the direction of the traffic signal transmission of the current connection till the egress node of the current connection; making migration between the two connection modes until the ingress node after the message of migrating request has been received. By making migration between modes of connection node by node at each node of a transmission network, this invention ensures a smooth transition between a permanent connection and a switched connection, effectively avoiding service disruption while making the implementation of network services more flexible.

Optical networks include Synchronous Digital Hierarchy (SDH)/Synchronous optical networks (Sonet), wave-length switched networks, and etc. A traditional optical network is a system based on centralized management and connection services between nodes of the network are implemented by way of permanent connection. The path of connection is pre-calculated by the management plane based on the connection requirement and the availability of network resources, then cross-connection commands are sent to nodes on the connection path via Network Management Interface-Transport (NMI-T) to carry out unified designation and assignment, and eventually, accomplish the establishment of a communication channel. The approach of permanent connection had good effects in the early development of optical network because the design is simple and cost is low. However, the setup, maintenance, and release of optical connection by the approach of permanent connection require the involvement of human work or network management system. With the continuing growth of traffic data, this approach of connection is no longer able to meet the dynamic and flexible requirement of an optical network system.
The key to solve this problem is the implementation of dynamic optical switching. That is why ITU-T has put forward the architecture of Automatic Switching Optical Network (ASON), which adds a control plane to a traditional optical network and puts forward the concept of switched connection. According to this idea, a node in an optical network will first obtain the link connection relations of this node with other nodes by the link discovery technique, then issue the states of node and links through the control plane, and receive the state issuance of other nodes in the network. Eventually, every optical node will have a "network map" giving a description of the accurate topology of the network and including various information about nodes, links, and resources. When a node is requested by a client or management system to establish a connection, the node will first calculate a path using the information of the "network map" combined with a certain algorithm of routing, and then drive the nodes on the path by signaling protocols to establish the cross-connection. When a network connection is dynamically created or released, or a failure brings about changes in the resources of links, related nodes will issue in time updated states of node and links to achieve re-synchronization of the "network map". In ASON, if the connection request received by a node comes from a client device or proxy, the connection created is referred to as switched connection; if the request comes from network management system, the connection created is referred to as soft permanent connection. In this specification, switched connection and soft permanent connection are both referred to as switched connection except otherwise specified. If a switched connection or a soft permanent connection is cut off when a failure occurs in the network, e.g. a link disconnects or a node fails, the control plane will be able to re-create the routing of connection dynamically and restore the traffic. An optical network with this approach of switched connection is of dynamic and flexible characteristics and is capable of meeting the requirement of growing data traffic.
Though the approach of switched connection has many advantages, it is a long process of evolution to upgrade a traditional supply-based optical network into an ASON, for it is an enormous project of system engineering involving the upgrading of network equipment, network management system, operating and supporting systems as well as other aspects of the network. In the present process of transition, the control plane is implemented only on some nodes. Even on these "intelligent" nodes where the control plane has been implemented, manually provided connections will not disappear immediately and permanent connections and switched connections will co-exist in the network. When permanent connections and switched connections co-exist in a network, network resources are usually allocated by the management plane to the connections, respectively and it is not easy to change the allocation thereafter. However, it is often not possible for the static allocation of resources to satisfy the changing traffic of an optical network. It is often necessary for an operator to make migration between a permanent connection and a switched connection to re-allocate the resources occupied respectively by the two modes of connection and make use of the different characteristics thereof.
In the prior art, however, no method of migration between a permanent connection and a switched connection is provided. When it is needed to make such a migration, the migrated connection has to be released at first, and then a connection of the required mode can be created using the resources from the released connection. This approach of migration may cause a disruption of the traffic, damages to the data in network transmission, problems to the operation of service, as well as inconvenience for the operator, and may further affect the network evolution to ASON.

Method for migration between a permanent connection and a switched connection in a transmission network


The present invention provides a three-level ac generating circuit and the control method thereof. The three-level ac generating circuit includes a three-level boosting circuit connected to an input source and including a positive boosting portion and a negative boosting portion; and a three-level inverting circuit connected to the three-level boosting circuit and including a positive inverting portion and a negative inverting portion, wherein while the input source is a relative low voltage, the relatively low voltage is boosted via the three-level boosting circuit, inverted and output via the three-level inverting circuit; while the input source is a relatively high voltage, the relatively high voltage is inverted and output via the three-level inverting circuit and                wherein the output of the three-level ac generating circuit is power grid.

It is the trend of the energy development to balance the energy, the environment and the economics. Furthermore, there are many drawbacks of the traditional centralized power generation technology. In comparison with the centralized power generation technology, the advantages of the distributed power generation technology are the flexible power generation, the environment protection, etc. The distributed power generation technology not only meets the requirements of the power system and the user, but also provides the flexibility, the reliability and the economical value.
Currently, the solar power generation system, the fuel battery and the wind power generation system are the main distributed power generation systems. The distributed power generation technology can be independently operated or be operated with the power generation system. The distributed power generation technology is operated in the place without the power grid. The distributed power generation technology is operated with the power generation system in the area with the increased loading. The ac generating circuit is the important part of the distributed power generation system.
Please refer to FIG. 1(a) showing the three-level ac generating circuit according to the prior art. Since the three-level ac generating circuit 10 is a single-stage circuit, the three-level ac generating circuit 10 has higher efficiency but needs higher battery voltage.
Please refer to FIG. 1(b) showing another three-level ac generating circuit according to the prior art. The three-level ac generating circuit 11 is a two-stage circuit. The battery voltage is converted into a predetermined value via the pre-converter 111, and then output via the post-inverter 112. Typically, the typical pre-converter 111 is a boost circuit or a buck-boost circuit.
The circuit shown in FIG. 1(b) has the expanded variation of the input voltage, but the drawbacks thereof are those the efficiency is low and many interferences are formed from the capacitor. In addition, the traditional half-bridge structure is used in the post-inverter 112, and the efficiency is low while the high voltage is applied to the post-inverter 112. The traditional half-bridge switch component has the anti-parallel diode as the continuous loop, so that while the switch component is conducted, the reverse recovery is performed by the anti-parallel diode. The MOSFET is not used as the switch component for minimizing the loss from the reverse recovery since the parasitic diode property of the MOSFET is not good enough even though the MOSFET has the conduction property of the resistance and good switch property. The switch loss of the system cannot be minimized by using the MOSFET as the switch component.
Generally, the three-level inverting circuit is used for the device with the high direct current input voltage but not the device with the low voltage. The voltage endurance capability of the switch component is decreased by the three-level inverting circuit, so that the efficiency of the device with the high voltage having the three-level inverting circuit is increased; therefore, the three-level inverting circuit is generally used in the fields of the uninterrupted power system and the motor driving. In the fields of the uninterrupted power system and the motor driving, the output terminal of the three-level inverting circuit is connected to the power-consuming device, and the load characteristic of the power-consuming device is changed along with the operation status of the power-consuming device. It means that the output voltage and the current phase of the three-level inverting circuit are changeable, i.e. there may be dual directions of the energy transportation.
Please refer to FIG. 2(a), which is the oscillogram showing the driving signals for driving the four switches by the single phase three-level inverting circuit with the inductance load. The switch components Sx1 and Sx2 are main control components, and the switch components Sx2 and Sx3 have the driving signals complementary to the diving signals of the switch components Sx4 and Sx1, respectively. FIGS. 2(b)-2(e) are circuits showing the three-level inverting circuit operating at different statuses.
FIG. 2(b) and FIG. 2(d) are circuits showing the three-level inverting circuit in the modes of the energy transportation. In FIG. 2(b), the switch component Sx1 is switched at high frequency and has the driving signal complementary to the driving signal of the switch component Sx3, the switch component Sx2 is normal on, and the switch component Sx4 is normal off. While the switch component Sx1 is conducted, the energy is transported from the input terminal via the switch components Sx1 and Sx2 and the inductor Lx to the output terminal. While the switch component is off, the inductor current iLx passes through the diode Dx12 and the switch component Sx2.
The operation procedure shown on FIG. 2(d) is similar to that shown on FIG. 2(b).
FIG. 2(c) and FIG. 2(e) are circuits showing the three-level inverting circuit in the mode of the energy feedback. In FIG. 2(c), the switch component Sx1 is switched at high frequency and has the driving signal complementary to the driving signal of the switch component Sx3, the switch component Sx2 is normal on, and the switch component Sx4 is normal off. While the switch component Sx1 is conducted, the inductor current iLx is negative, so that the current passes through the diode anti-parallel to the switch components Sx1 and Sx2, and the energy is feedback from the output terminal to the input terminal. While the switch component Sx1 is off and the switch component Sx3 is conducted, the inductor current iLx passes through the switch component Sx3 and the diode Dx34.
The operation procedure shown on FIG. 2(e) is similar to that shown on FIG. 2(c).
According to the above analyses, while the three-level inverting circuit is in the mode of the energy transportation (for example, as shown in FIG. 2(b)), the switch component Sx3 is not the component for passing through the current, so that the switch component Sx3 is switched at low frequency, i.e. the switch frequency is equal to the frequency of output voltage. While the three-level inverting circuit is in the mode of energy feedback, the switch component Sx3 is as the component for passing through the current, so that the switch component Sx3 has to be switched at high frequency. In addition, there are the energy transportation mode and the energy feedback mode in the fields of the uninterrupted power system and the motor driving, i.e. there are dual directions of the energy transportation, so that the switch component Sx3 has to be switched at high frequency. Similarly, the switch component Sx2 also has to be switched at high frequency.
In addition, while the three-level inverting circuit is in the mode of the energy feedback (for example, as shown FIG. 2(c)), the current passes through the diode anti-parallel to the switch components Sx1 and Sx2, so that while the switch component Sx1 is off and the switch component Sx3 is conducted, the diode anti-parallel to the switch components Sx1 and Sx2 is reversely recovered. There is the parasitic diode in the MOSFET, and the reverse recovery characteristic of the parasitic diode is very bad, so that while the three-level inverting circuit is used in the fields of the uninterrupted power system and the motor driving, the MOSFET is generally not used as the switch component. The MOSFET is not used as the switch component for minimizing the loss from the reverse recovery since the parasitic diode property of the MOSFET is not good enough even though the MOSFET has the conduction property of the resistance and good switch property.
In addition, since the power systems, such as the solar battery and the fuel battery, have the wide range of the voltage variation of the direct current power source, wherein the highest input voltage may be several times (for example, more than 3 times)of the lowest input voltage, the three-level inverting circuit cannot be directly used in the power system.
In order to overcome the disadvantages of the prior art described above, the present invention provides a three-level AC generating circuit and the control method thereof.

Three-level AC generating circuit and control method thereof


A method is provided for use in constructing an MR image associated with the flow of blood or other fluid through an imaging volume, wherein material flowing through a selected voxel of the imaging volume is distinguished from static material. The method includes the step of applying a first MR pulse sequence to the imaging volume to produce a first MR data signal, having a magnitude which encodes first and second flow parameters for respective voxels comprising the volume, and having a phase which encodes a third flow parameter. The method further includes the step of applying a second MR pulse sequence to the volume, to produce a second MR data signal which indicates the content of respective voxels without flow encoding. The first and second MR data signals are compared to one another, such as by computing the difference therebetween, to determine the presence or absence of flowing material in respective voxels of the imaging volume. Information generated by such comparison is employed to construct an MR image which shows the flowing material.

The invention disclosed and claimed herein is generally directed to a technique for acquiring magnetic resonance (MR) signal data relating to the flow of blood or other fluid within an imaging subject, wherein flow velocity or other parameter is encoded in the MR signals. More particularly, the invention pertains to a technique of the above type, wherein flow velocity information is encoded in the magnitude as well as the phase of respective MR signals. As is well known, acquired MR imaging data can be represented in quadrature. That is, the MR signal at each voxel location of an imaging slice can be represented by two complex components which are ninety degrees out of phase, referred to herein as C.sub.1 and C.sub.2, respectively. Thus, the MR signal at the jth voxel has a magnitude I.sub.j equal to ##EQU1## and a phase component .phi..sub.j equal to the arctangent of (C.sub.2 /C.sub.1), or tan.sup.-1 (C.sub.2 /C.sub.1). Accordingly S.sub.j can be expressed as S.sub.j =I.sub.j e.sup.-i.PHI..sbsp.j.
MR signal phase component is now used in the field of phase contrast (PC) angiography. Such field pertains to generation of an image which represents the flow of blood or other fluid through a vessel, and more specifically represents fluid velocity, rate of flow, or other flow parameter. As is further well known, if blood is flowing through the jth voxel, an associated signal S.sub.j can be acquired wherein the phase .phi..sub.j is a function of flow velocity at the jth voxel v.sub.j. Thus, velocity is encoded in the phase, i.e., .phi..sub.j =.PHI.(v.sub.j).
In accordance with conventional PC angiography, two consecutive MR experiments or sequences are applied to an imaging volume to produce two successive signals S.sub.1j and S.sub.2j, associated with the jth voxel. The first experiment employs a positive flow encoding gradient pulse, and the second experiment employs an identical gradient pulse, but of negative sign. Thus, signals are provided wherein S.sub.1j =I.sub.js +I.sub.1jm e.sup.-i.PHI.(vj) and S.sub.2j =I.sub.2js +I.sub.2jm e.sup.+i.PHI.(v.sub.j). The terms I.sub.1js and I.sub.2j represent the signal components resulting from static or non-moving spins and are the same for both experiments, i.e., I.sub.1js =I.sub.2js. Also, in conventional PC angiography, signal magnitude is not affected by flow velocity, so that I.sub.1jm =I.sub.2jm =I.sub.j. Accordingly, the difference between S.sub.1j and S.sub.2j, i.e. {I.sub.1js +I.sub.j e.sup.-.PHI.(v.sbsp.j) }-{I.sub.2js +I.sub.j e.sup.+.PHI.(v.sbsp.j) }=I.sub.j {e.sup.-.PHI.(v.sbsp.j) -e.sup.+l.PHI.(v.sbsp.j) },provides an expression from which static effects are eliminated, and from which the flow velocity may be computed.
Flow velocity v.sub.j generally comprises components v.sub.x, v.sub.y, and v.sub.Z, relative to the X-, Y-, Z- gradient axes, respectively. Practical implementation of the above technique requires computation of each velocity component, so that it is necessary to apply X-, Y-, and Z-gradients sequentially. As a result, the imaging time required to construct an angiogram is comparatively long. Under conventional practice, it is necessary to acquire at least four images, in order to obtain the velocity component information required to compute the velocity v.sub.j value for each of the voxels of a single angiogram. Imaging time thus constitutes one of the major limitations of PC angiography.

Encoding flow information using MR signal magnitude


In accordance with the present invention, neuropsychiatric symptoms of apathy-amotivation syndrome and particularly those symptoms in: Alzheimer's disease, multiple sclerosis, Huntington's chorea, frontal lobe lesions, and AIDS dementia can be ameliorated by treating a patient with a histamine H.sub.2 -antagonist that passes the blood-brain barrier. Suitable H.sub.2 -antagonists include famotidine and ranitidine. The H.sub.2 -antagonists may be co-administered with other compounds which are known to be useful in the treatment of the above neuropsychiatric conditions, and in one aspect of the invention can be formulated with such other compounds into a therapeutic composition.

This application relates to a method and composition for use in the treatment of apathy-amotivation syndrome (also known as abulia or anergia syndrome) in neuropsychiatric disorders.
The syndrome of apathy is defined as absence of or decrease in motivation (Marin, Differential Diagnosis and Classification of Apathy, American Journal of Psychiatry 147: 22-30,, January 1990). Slowness of thinking and diminished ability to shift from one set of thinking to the other. This can occur in a variety of apparently unrelated neuropsychiatric disorders. Some of the most common conditions that result in apathy-amotivation syndrome are: schizophrenia, Parkinson's disease, Alzheimer's disease, multiple sclerosis, Huntington's chorea and frontal lobe lesions. (Marin, Apathy: A Neuropsychiatric Syndrome, Journal of Neuropsychiatry and Clinical Neurosciences, 3: 243-254, 1991). In each case apathy-amotivation is just one of a plurality of symptoms associated with the disease. In the past, treatments of other aspects of these conditions such as motor and sensory deficits, dementia, and depression have little or no benefit with respect to apathy-amotivation syndrome.
There is large body of evidence that describe apathy-amotivation syndrome and its manifestation in neuropsychiatric disorders. (Starkstein, et al., Reliability, Validity, and Clinical Correlates of Apathy in Parkinson's Disease, Journal of Neuropsychiatry, Volume 4, Number 2, Spring 1992; Bozzola, et al., Personality Changes in Alzheimer's Disease, Arch Neurol, Volume 49, March 1992; Burns, et al., Clinical Assessment of Irritability, Aggression, and Apathy in Huntington and Alzheimer Disease, The Journal of Nervous and Mental Disease Vol. 178, No. 1; Mendez, et al., Neurobehavioral changes associated with caudate lesions, Neurology 39, March 1989; Robinson, et al., Mood Disorders in Stroke Patients, Brain (1984); House, et al., Mood Disorders in the Year after First Stroke, British Journal of Psychiatry (1991); Benson, et al., Psychiatric Aspects of Neurological Disease, Personality Changes With Frontal and Temporal Lobe Lesions, Grune & Stratton, Inc., 1975; Cummings, Clinical Neuropsychiatry, Grune & Stratton, Inc., 1985; McHugh, et al., Psychiatric Aspects of Neurological Disease, Psychiatric Syndromes of Huntington's Chorea: A Clinical and Phenomenologic Study, Grune & Stratton, 1975; Caine, et al., Psychiatric Syndromes in Huntington's Disease, Am J Psychiatry 140:6, June 1983; Ho, et al., The Acquired Immunodeficiency Syndrome (AIDS) Dementia Complex, Annals of Internal Medicine, Volume III, Number 5, Sep. 1, 1989; Cohen, et al., Amantadine Treatment of Fatigue Associated With Multiple Sclerosis, Arch Neurol Vol. 46, June 1989). The common scientific view is to ascribe apathy-amotivation to deficits in the function of the frontal lobes. (Hecaen, et al., Psychiatric Aspects of Neurological Disease, Disorders of Mental Functioning Related to Frontal Lobe Pathology, Grune & Stratton, 1975; Trimble, Psychopathology of Frontal Lobe Syndromes, Seminars in Neurology, Volume 10, No. 3, September 1990; Strub, Frontal Lobe Syndrome in a Patient With Bilateral Globus Pallidus Lesions, Arch Neurol, Vol. 46, September 1989). In recent years, studies have implicated other brain structures that may be involved in the production of the apathy-amotivation syndrome (e.g., striatum and hippocampal formation) (Wang, Neurobehavioral Chanaes Following Caudate Infarct: A Case Report with Literature Review, Chin Med J (Taipei), 1991; Hedreen, et al., Neuronol loss in layers V and VI of cerebral cortex in Huntington's disease, Neuroscience Letters, 133 (1991); Alvarez, et al., The role of histamine in the anterior hypothalamus and its functional interaction with the hippocampal on exploratory behavior in adult male rats, Behavioural Brain Research, 48: 127-33, 1992) but their specific contribution is yet to be elucidated.
Recently, I have established that apathy-amotivation associated with schizophrenia and Parkinson's disease can be treated using histamine H.sub.2 -antagonists. It is the object of the present invention to extend this same treatment regimen to patients having apathy-amotivation syndrome associated with other neuropsychiatric disorders.

Method and composition for the treatment of apathy-amotivation syndrome


Photoelectric and inductive sensors are placed along a picking and eviscerating chicken lines. The sensors detect the location of a chicken bird in a shackle and its associated feet, also in a shackle. The sensors communicate this information to a programmable logic card. An inspection button also communicates information to the programmable logic card. Medal flags are attached to a shackle to allow for an easier way for the sensors to determine the locations of the chicken bird and its associated feet.

1) Field of the Invention
The field of invention relates to a process to electronically sort chicken feet into the category of either edible or inedible. More particularly, the invention utilizes electronic tracking sensors to maintain identity between all processed chickens and their respective feet.
2) Description of Prior Art
While the prior art includes methods and apparatus for performing various poultry processing operations, insofar as the applicants are aware there is no known method that utilizes an electronic tracking system to maintain identity between all processed chickens and their respective feet.
The demand for poultry, and especially chicken feet as a specialty food item, particularly in the Orient, is relatively great. Approximately three hundred tons per month are currently being exported from the United States. However, the supply of poultry feet is limited and the cost is kept relatively high because of the lack of a fully automatic method and apparatus for processing such poultry parts into edible and inedible parts. Conventional practice calls for the poultry feet be sorted into edible and inedible when an inspector, from the USDA or plant quality facility, determines that the chicken is edible or inedible. However, the labor required to manually remove the feet from the conveyor lines subsequent to the inspector's review of the chicken makes the cost of poultry process of the manual method unattractive.
Therefore, it has long been known that it would be desirable to have a method to electronically sort the feet into the category of edible and inedible when the chicken is inspected and determined to be either edible or inedible. The invention thus provides for the processing of poultry in an automatic, dependable and economical fashion so as to permit the sale of such chicken parts at a commercially acceptable price and which has particular utility in the processing of poultry feet.

Process to electronically automate the sorting of chicken feet in the category of edible or inedible


A method and apparatus used for designing printed circuit boards to meet current leakage requirement by determining an approximate model of electric fields based on a structure between two conductors on an outer surface of a printed circuit board; deriving an effective permittivity of the model of the electric fields; calculating a plurality of electric fields using the derived effective permittivity by varying a distance between the two conductors, a thickness of the printed circuit board, and an applied voltage between the two conductors; plotting a graph of the calculated plurality of electric fields; and selecting by using the graph a configuration of the two conductors so as to meet the current leakage requirement. A printed circuit board has a set of conductors on the outer surfaces of the printed circuit board; another set of conductors interior to the printed circuit board; and a solder mask that covers only the set of conductors on the outer surfaces of the printed circuit board.

Printed circuit boards utilized in certain applications such as those printed circuit boards utilized in telecommunication public facilities must demonstrate the ability of conductors exposed on the surface of the printed circuit board to withstand a high-voltage surge without causing safety compromises to the end user. Regulatory compliance tests have been set up to test for such conditions. One such regulatory test is defined by the TIA968A Leakage Current Limitations test as outlined in section 4.3 of the standard. The latter test specifically requires that exposed printed circuit board conductors must not cause their dielectric insulation to break down under the response to a 1500 Vrms low-frequency sine wave of a 60 seconds duration. If the dielectric breakdown occurs between the exposed printed circuit conductors and the leakage current exceeds 10 ma, the printed circuit board fails this particular test and must be redesigned so that the exposed conductors can be in compliance with this test.
Within the prior art, the redesign of the printed circuit board has been accomplished either by simply increasing the distance between the edges of the two exposed conductors such that the dielectric breakdown is avoided between the conductors. A second approach has been to use conformal coatings between the two conductors. Although both of these prior art approaches are effective, it is very costly to have to either redesign for a larger distance between the conductors or to use conformal coatings.

Method and apparatus for designing printed circuit boards to meet leakage current requirements


This disclosure relates to a process of manufacturing para-xylene, comprising (a) contacting a pygas feedstock and methylating agent with a catalyst under reaction conditions to produce a product having para-xylene, wherein the product has higher para-xylene content than the para-xylene content of the pygas feedstock; and (b) separating the para-xylene from the product of the step (a), wherein the catalyst comprises a molecular sieve having a Diffusion Parameter for 2,2-dimethylbutane of about 0.1-15 sec−1 when measured at a temperature of 120° C. and a 2,2-dimethylbutane pressure of 8 kPa-a and the pygas comprises from about 1 to about 65 wt % benzene and from about 5 to 35 wt % toluene.

Of the xylene isomers, para-xylene (PX) is of particular value since it is useful in the manufacture of terephthalic acid which is an intermediate in the manufacture of synthetic fibers. Para-Xylene is presently produced almost exclusively from naphtha by catalytic reforming process. The aromatics produced are used as feedstock to aromatics plants. Aromatics plants purify toluene and mixed xylenes. Purified toluene may be selectively or non-selectively disproportionated to produce para-xylene and benzene. Para-xylene may also be produced from mixed xylenes by isomerization/separations loop.
One known method for producing xylenes involves the alkylation of toluene with methanol over a solid acid catalyst. Thus the alkylation of toluene with methanol over cation-exchanged zeolite Y has been described by Yashima et al. in the Journal of Catalysis 16, 273-280 (1970). These workers reported selective production of para-xylene over the approximate temperature range of 200 to 275° C., with the maximum yield of para-xylene in the mixture of xylenes, i.e. about 50 wt % of the xylene product mixture, being observed at 225° C. Higher temperatures were reported to result in an increase in the yield of meta-xylene and a decrease in production of para and ortho-xylenes.
U.S. Pat. Nos. 7,119,239 and 7,176,339 disclose a process for the production of xylenes from reformate. The process is carried out by methylating under conditions effective for the methylation, the benzene/toluene present in the reformate outside the reforming loop, to produce a resulting product having a higher xylenes content than the reformate. Greater than equilibrium amounts of para-xylene can be produced by the process. U.S. Pat. No. 7,186,873 discloses process for the production of xylenes from reformate by reactive distillation. The process is carried out by methylating the benzene/toluene present in the reformate in a reactive distillation zone and under reactive distillation conditions to produce a resulting product having a higher xylenes content than the reformate. Greater than equilibrium amounts of para-xylene can be produced by the process.
As far as the present inventor is aware, it has previously not been suggested to methylate a pyrolysis gasoline (pygas), to manufacturing para-xylene nor has been suggested to integrate a catalytic system comprising a steam cracker and a methylation unit to produce para-xylene, and optionally co-produce light olefins. There is no prior art disclosing the production of para-xylene from resid and methylating agent feedstocks by any means. There is no prior art teaching the use of methylation technology to convert ethylbenzene to para-xylene and ethylene.
U.S. Pat. No. 6,046,372 discloses a process for converting methanol and/or dimethyl ether to a product containing C2 to C4 olefins which comprises the step of contacting a feed which contains methanol and/or dimethyl ether with a catalyst comprising a porous crystalline material, said contacting step being conducted in the presence of an aromatic compound under conversion conditions including a temperature of 350° C. to 480° C. and a methanol partial pressure in excess of 10 psia (70 kPa), said porous crystalline material having a pore size greater than the critical diameter of the aromatic compound and the aromatic compound being capable of alkylation by the methanol and/or dimethyl ether under said conversion conditions.
U.S. Pat. No. 6,680,418 discloses a process for converting methanol and/or dimethyl ether to a product containing C2 to C4 olefins, which comprises the step of contacting a reaction mixture containing methanol and/or dimethyl ether and at least 10 wt % of a polymethylbenzene component selected from trimethylbenzenes, tetramethylbenzenes and mixtures thereof with a catalyst comprising a porous crystalline material. The contacting step is conducted under conversion conditions including a temperature of about 250° C. to about 500° C. and a methanol and/or dimethyl ether partial pressure of about 5 to about 250 psia (35 to 1725 kPa). The porous crystalline material used in the catalyst has a pore size greater than the critical diameter of the aromatic compound and a Diffusion Parameter for 2,2-dimethylbutane of at least 500 sec−1 when measured at a temperature of 120° C. and a 2,2-dimethylbutane pressure of 60 torr (8 kPa).
All methylation processes use relatively pure toluene, mixtures of toluene and benzene, or reformate as feedstock for manufacturing xylene, preferably para-xylene. The sources of toluene/benzene feedstock for the methylation process may be reformate or pygas. However, to the best knowledge of the inventor, there is no disclosure of using pygas as the aromatic feedstock for the methylation process. It is well known to a person of ordinary skill that pygas contains large amount of non-aromatics, some olefinic hydrocarbons, and a high ethylbenzene content in the C8 aromatics. Both non-aromatics and olefinic hydrocarbons are known for catalyst deactivation and aging. Ethylbenzene is known as a bad feedstock for para-xylene production. Furthermore, there is no disclosure using pygas without extraction as the aromatic feedstock for the methylation process. Even more, there is no disclosure using pygas obtained from steam cracking a hydrocarbon feedstock made with hydroprocessed resid with/without extraction as the aromatic feedstock for the methylation process.
There is, therefore, a need to develop a technology to produce para-xylene in high yield from pygas feedstock. Another technical challenge related to use of pygas feedstock for para-xylene production is rapid catalyst deactivation because the pygas feedstock contains certain amount of non-aromatics which may deactivate the catalyst. Therefore the pygas feedstock normally is subjected to an extraction process to remove most of the non-aromatics before further processing. However, the extraction process is expensive and capital intensive. There is also a need to produce aromatic products from pygas without extraction.
We surprisingly discovered a process of manufacturing PX, optionally co-manufacturing light olefins, from a pygas feedstock by methylating the pygas with a methylating agent using a molecular sieve catalyst. Furthermore, the para-xylene is produced with higher than thermodynamic equilibrium amount when a selectivated molecular sieve is used as catalyst for the methylation step.