According to one implementation, an optical observation system includes an optical fiber and at least one detection system. The optical fiber has at least one curved portion as a sensor for inputting light which has occurred in a test region. The optical fiber inputs the light from the at least one curved portion and transmits the light. The at least one detection system detects the light transmitted by the optical fiber. Further, according to one implementation, an optical observation method includes: inputting light, which has occurred in a test region, from at least one curved portion of an optical fiber and transmitting the light; and detecting the light transmitted by the optical fiber.

When electrical energy accumulates in a structure of an aircraft due to a lightning stroke, static electricity or the like, a spark occurs. The occurrence of a spark may cause fuel to ignite, which may interferes with the safety of a flight. Thus, conventionally in development of an aircraft, a huge number of tests have been done in order to confirm the existence of occurrence of a spark (for example, refer to Japanese Patent Application Publication JP 2014-153298 A). As a method of confirming the existence of occurrence of a spark, a photographic method and a gas ignition confirmation method are known.
The photographic method confirms the existence of a spark by photographing a test piece in which a current flows. Meanwhile, the gas ignition confirmation method confirms the existence of ignition by supplying a current to a test piece containing a flammable gas.
Furthermore, a technique to estimate energy of a spark has also been proposed as a related technique (for example, refer to Japanese Patent Application Publication JP 2014-137227 A).
In a spark confirmation test by the photographic method, even a spark having such a small energy that the spark does not ignite becomes a ground of rejection determination in the test as long as the spark is photographed. Therefore, an excessive countermeasure for preventing occurrence of a spark may be required. In addition, the photographic method has a problem that a spark may be photographed differently when cameras are different. Furthermore, a photographing direction by a camera is fixed in the photographic method. Therefore, there is a problem that in the case of photographing a test piece having a complicated structure, it may be unable to confirm the existence of a spark which has occurred at a position which becomes a shade of the test piece as seen from a position of the camera.
Meanwhile, in the case of the gas ignition confirmation method, there are problems that a test piece may ignite due to other than a spark, that a test piece may not ignite even when a spark occurs, and that the test takes long time and safety measures are necessary. Furthermore, in the case of testing a test piece having a complicated structure, a spark often occurs at a position which becomes a shade of the test piece as seen from a position of a camera. Therefore, a spark may not be seen even when the test piece ignites. When the test piece has ignited without the spark being seen, there is a problem that it cannot be confirmed whether the test piece has ignited due to the spark.
The above-mentioned conventional spark confirmation test has incurred an increase in a development period of an aircraft, and also has become a factor for increasing development costs of an aircraft. This is a common issue not only in development of an aircraft but also in development of a product for which it is necessary to prevent occurrence of a spark.
Thus, various techniques for detecting a spark even in the case of a test piece having a complicated structure have been proposed for a spark confirmation test of an aircraft or the like. For example, a system for specifying a position, at which a spark has occurred, by disposing many optical fibers on a test piece and performing photoelectric conversion of a light which has been input into an end portion of each of the optical fibers has been proposed (for example, refer to Japanese Patent Application Publication JP 2013-200213 A). That is, when many optical fibers are disposed on a test piece having a complicated structure, detection omission of a spark occurring at a position which becomes a shade of the test piece can be prevented.
However, when a spark confirmation test is performed using a plurality of optical fibers, placing a system takes time since many optical fibers, photoelectric converters and the like are necessary. Furthermore, since the system becomes a large scale, there are problems that manufacturing costs increase and that a large space is necessary for placing the system. These problems are common not only in a spark confirmation test but also in the case of detecting a light.
Thus, an object of the present invention is to allow confirming the existence of a light, such as a spark light, in satisfactory accuracy with a safer and simpler structure.

Optical observation system and optical observation method


A method is provided for treating solid tumors comprising administering a composition comprising a PDGF aptamer and a cytotoxic agent. In a preferred embodiment the PDGF aptamer is identified using the SELEX process for the Systematic Evolution of Ligands by Exponential enrichment. A method is also provided for reducing the interstitial fluid pressure (IFP) of a solid tumor comprising administering a PDGF aptamer. Finally, a method is provided for increasing the uptake of cytotoxic agents into a tumor comprising administering a composition comprising a PDGF aptamer and a cytotoxic agent.

The Systematic Evolution of Ligands by Exponential Enrichment (SELEX) process is a method for the in vitro evolution of nucleic acid molecules with highly specific binding to target molecules and is described in U.S. patent application Ser. No. 07/536,428, filed Jun. 11, 1990, entitled "Systematic Evolution of Ligands by EXponential Enrichment," now abandoned, U.S. Pat. No. 5,475,096, entitled "Nucleic Acid Ligands," and U.S. Pat. No. 5,270,163 (see also WO 91/19813), entitled "Methods for Identifying Nucleic Acid Ligands," each of which is specifically incorporated herein by reference in its entirety. Each of these applications, collectively referred to herein as the SELEX Patent Applications, describes a fundamentally novel method for making a nucleic acid ligand to any desired target molecule.
The SELEX process provides a class of products which are referred to as nucleic acid ligands or aptamers, each having a unique sequence, and which has the property of binding specifically to a desired target compound or molecule. Each SELEX-identified nucleic acid ligand is a specific ligand of a given target compound or molecule. The SELEX process is based on the unique insight that nucleic acids have sufficient capacity for forming a variety of two- and three-dimensional structures and sufficient chemical versatility available within their monomers to act as ligands (form specific binding pairs) with virtually any chemical compound, whether monomeric or polymeric. Molecules of any size or composition can serve as targets. The SELEX method applied to the application of high affinity binding involves selection from a mixture of candidate oligonucleotides and step-wise iterations of binding, partitioning and amplification, using the same general selection scheme, to achieve virtually any desired criterion of binding affinity and selectivity. Starting from a mixture of nucleic acids, preferably comprising a segment of randomized sequence, the SELEX method includes steps of contacting the mixture with the target under conditions favorable for binding, partitioning unbound nucleic acids from those nucleic acids which have bound specifically to target molecules, dissociating the nucleic acid-target complexes, amplifying the nucleic acids dissociated from the nucleic acid-target complexes to yield a ligand enriched mixture of nucleic acids, then reiterating the steps of binding, partitioning, dissociating and amplifying through as many cycles as desired to yield highly specific high affinity nucleic acid ligands to the target molecule.
It has been recognized by the present inventors that the SELEX method demonstrates that nucleic acids as chemical compounds can form a wide array of shapes, sizes and configurations, and are capable of a far broader repertoire of binding and other functions than those displayed by nucleic acids in biological systems.
The basic SELEX method has been modified to achieve a number of specific objectives. For example, U.S. patent application Ser. No. 07/960,093, filed Oct. 14, 1992, now abandoned, and U.S. Pat. No. 5,707,796, both entitled "Method for Selecting Nucleic Acids on the Basis of Structure," describe the use of the SELEX process in conjunction with gel electrophoresis to select nucleic acid molecules with specific structural characteristics, such as bent DNA. U.S. patent application Ser. No. 08/123,935, filed Sep. 17, 1993, entitled "Photoselection of Nucleic Acid Ligands," now abandoned, U.S. Pat. Nos. 5,763,177 and 6,011,577, both entitled "Systematic Evolution of Ligands by Exponential Enrichment: Photoselection of Nucleic Acid Ligands and Solution SELEX," describe a SELEX based method for selecting nucleic acid ligands containing photoreactive groups capable of binding and/or photocrosslinking to and/or photoinactivating a target molecule. U.S. Pat. No. 5,580,737, entitled "High-Affinity Nucleic Acid Ligands That Discriminate Between Theophylline and Caffeine," describes a method for identifying highly specific nucleic acid ligands able to discriminate between closely related molecules, which can be non-peptidic, termed Counter-SELEX. U.S. Pat. No. 5,567,588, entitled "Systematic Evolution of Ligands by EXponential Enrichment: Solution SELEX," describes a SELEX-based method which achieves highly efficient partitioning between oligonucleotides having high and low affinity for a target molecule.
The SELEX method encompasses the identification of high-affinity nucleic acid ligands containing modified nucleotides conferring improved characteristics on the ligand, such as improved in vivo stability or improved delivery characteristics. Examples of such modifications include chemical substitutions at the ribose and/or phosphate and/or base positions. SELEX process-identified nucleic acid ligands containing modified nucleotides are described in U.S. Pat. No. 5,660,985, entitled "High Affinity Nucleic Acid Ligands Containing Modified Nucleotides," that describes oligonucleotides containing nucleotide derivatives chemically modified at the 5- and 2′-positions of pyrimidines. U.S. Pat. No. 5,580,737, supra, describes highly specific nucleic acid ligands containing one or more nucleotides modified with 2′-amino (2′-NH2), 2′-fluoro (2′-F), and/or 2′-O-methyl (2′-OMe). U.S. patent application Ser. No. 08/264,029, filed Jun. 22, 1994, entitled "Novel Method of Preparation of Known and Novel 2′ Modified Nucleosides by Intramolecular Nucleophilic Displacement," describes oligonucleotides containing various 2′-modified pyrimidines.
The SELEX method encompasses combining selected oligonucleotides with other selected oligonucleotides and non-oligonucleotide functional units as described in U.S. Pat. No. 5,637,459, entitled "Systematic Evolution of Ligands by EXponential Enrichment: Chimeric SELEX," and U.S. Pat. No. 5,683,867, entitled "Systematic Evolution of Ligands by EXponential Enrichment: Blended SELEX," respectively. These applications allow the combination of the broad array of shapes and other properties, and the efficient amplification and replication properties, of oligonucleotides with the desirable properties of other molecules.
The SELEX method further encompasses combining selected nucleic acid ligands with lipophilic compounds or non-immunogenic, high molecular weight compounds in a diagnostic or therapeutic complex as described in U.S. Pat. No. 6,011,020, entitled "Nucleic Acid Ligand Complexes." Each of the above described patent applications which describe modifications of the basic SELEX procedure are specifically incorporated by reference herein in their entirety.
One approach to increasing the effectiveness of existing anti-cancer drugs for the treatment of solid malignancies is to augment the uptake of the drugs into tumors, and thereby obtain increased therapeutic concentration without elevating the adverse side-effects. Most solid tumors display an increased interstitial fluid pressure (IFP). The molecular mechanisms causing increased tumor IFP are poorly understood. However, tumor stroma involvement in IFP control has been demonstrated. (Gullino et al. (1964) Cancer Res. 24:780–797; Philips et al. (1990) J. Natl Cancer Inst. 82:1457–1469; Jain (1987) Cancer Res. 47:3039–3051). It has been suggested that high tumor IFP prevents drug transport from the circulation into the tumor interstitium. The reduction of tumor IFP therefore is a target for efforts to increase tumor drug uptake. (Jain (1996) Science 271:1079–1080). Several agents which induce a lowering of IFP, and thereby increase the transcapillary transport in experimental murine tumors have been identified, including nicotinamide (Lee et al. (1992) Cancer Res. 52:3237–3240), TNF-α (Kristensen et al. (1996) Br. J. Cancer 74:533–536) and dexamethasone (Kristjansen et al. (1993) Cancer Res. 53:4764–4766).
Platelet-derived growth factor (PDGF) and the cognate tyrosine kinase receptors are potent mitogens for mesenchymal cells. In addition to its growth promoting effects, PDGF-BB is involved also in the regulation of IFP. After dextran-induced anaphylaxis and lowering of IFP in rat skin, local administration of PDGF-BB results in normalized IFP. PDGF receptors are expressed in the tumor stroma of many common solid tumors, e.g. lung, colon and breast carcinomas. Based on these observations the effects of PDGF antagonists on tumor IFP, tumor transcapillary transport and therapeutic effects of cytotoxic drugs were investigated.

This patent is subject to a terminal disclaimer.

Methods and compositions for treatment of tumors using nucleic acid ligands to platelet-derived growth factor


Embodiments of the present invention include a frequency generator comprising a feedback loop with a transmission line integrated on a single integrated circuit. In one embodiment, a frequency generator comprises a phase detector and a voltage controlled oscillator coupled in series, and a transmission line having an input coupled to an output of the voltage controlled oscillator, the transmission line providing a time delay between the transmission line input and output, wherein the phase detector includes an input coupled to the transmission line output and another input coupled to the transmission line input. The phase detector, voltage controlled oscillator and transmission line are advantageously integrated on a single integrated circuit.

The present invention relates to frequency generators, and in particular, to frequency generator circuits and methods that can be fully integrated on a single integrated circuit.
In almost every computer system or digital system, there is a requirement for at least one signal having a specified frequency. One example of such a signal is a reference frequency signal (i.e., a timing reference). For example, a reference frequency signal may be a system clock. Signals with specified frequencies are created using frequency generators. One example of a frequency generator is a crystal oscillator. A crystal oscillator is an electrical circuit that uses a quartz crystal as a reference device to generate a frequency. Quartz crystals are piezoelectric devices that are made from crystalline silicon dioxide. When quartz crystals are driven by an electrical signal, they will exhibit a mechanical resonance (vibration) at certain frequencies of the driving signal. By using the appropriate electrical circuit, an electrical signal can be generated that is equal in frequency to the quartz crystal's mechanical resonant frequency. Such circuits are advantageous because quartz crystal may be used to generate very precise reference frequency signals.
Even though crystal oscillators have an advantage of being very accurate, they do have some well-known disadvantages. For example, since the creation of the reference frequency involves physically vibrating a silicon dioxide crystal at the reference frequency, over-driving the crystal with too large of an electrical signal can damage it. This damage to the quartz crystal can result in a shift of the resonant frequency, or in extreme cases the crystal can fracture. If a fracture were to occur, the crystal would become non-functional and the crystal oscillator would stop operating at the reference frequency. Sudden large changes in temperature can also damage the quartz crystal. Again, this damage could result in a shift of the crystal's resonant frequency or the fracture of the crystal. Another disadvantage associated with these crystal oscillators are their susceptibility to mechanical vibration or shock. A mechanical shock to the crystal can cause a sudden momentary shift in the oscillator frequency. This occurs because the shock can disturb the mechanical vibration of the quartz crystal. In the same manner, a constant mechanical vibration of the circuit board to which the crystal is attached can interfere with the mechanical vibration of the quartz crystal. A mechanical vibration of the circuit board would cause periodic variations of the output frequency of the crystal oscillator.
A particularly significant drawback to crystal oscillator circuits is that a quartz crystal cannot be integrated into a monolithic integrated circuit together with the electrical drive circuitry. The silicon dioxide crystal is always placed external to the integrated circuit, which contains the electrical devices that drive the crystal. Because the crystal is external to the integrated circuit, the crystal oscillator is much more susceptible to electrical disturbances from external sources. Signals adjacent to the quartz crystal can couple electrical disturbances into the leads of the crystal. These disturbances may result in variations of the output frequency of the oscillator circuit. Having the quartz crystal external to the integrated circuit may also result in the crystal oscillator being more susceptible to humidity and dirt. Accumulated moisture or dirt across the leads of the crystal would create a conduction path between the leads. If the resistance of this parasitic conduction path becomes too low, the crystal oscillator circuit would stop oscillating. Still another drawback to the crystal oscillator is related to economics. Since the quartz crystal is external and separate from the integrated circuit that drives it, additional costs are incurred. One additional cost is due to the extra assembly costs required to attach the external crystal to the printed circuit board. Another additional cost is due to the extra printed circuit board space that is used.
Despite these many disadvantages, crystal oscillators are very popular because they are capable of generating extremely accurate reference frequency signals. The precision of the output frequencies from these crystal oscillator circuits is on the order of 0.01%. However, in many applications such a high level of precision is not required. For example, in many digital systems a precision on the order of 1.0% for the system clock is sufficient.
Thus, there is a need for improved frequency signal generators over existing crystal oscillator techniques. In particular, there is a need for a frequency generator that is fully integrated on a single integrated circuit. The present invention solves these and other problems by providing a frequency generator that can be fully integrated on a single integrated circuit. Features and advantages of the present invention include providing a frequency generator with improved reliability and lower cost.


A filter element includes a filter media pack, a frame, an annular seal, and a sealing means independent of the annular seal, attaching the filter media pack and the frame. The means of sealing an interface between the filter media pack and the frame include molding a filter media pack seal, plastic welding outer wraps of filter media pack to the frame, and securing the filter media pack and the frame using a bead of adhesive.

Filtration devices and systems are employed in a wide range of applications for filtering contaminants from various process fluids. For example, it is known to pass air or similar gases through filter assemblies that enclose filtration media such as filter paper to remove dust and other contaminants. The filtration media is typically enclosed within a housing that is a permanent part of a larger overall process system (e.g. an engine) that utilizes the filtered fluids. Desirably, to prevent clogging of the filter, the filter assembly is constructed to facilitate the removal and replacement of the filtration media from the permanent housing. For this reason, the filtration media is typically configured into removable filter elements, also referred to herein as filter cartridges.
One commonly used filter media in construction of filter elements is fluted filter media. Fluted filter media is typically formed by winding a convoluted sheet and a face sheet about an axis to form a plurality of contiguous adjacent flutes. In one common form of such fluted filter media, alternating ends of adjacent flutes are blocked to cause fluid entering one open end of "inlet" flutes to flow through the porous filter media into adjacent "outlet" flutes prior to exiting the filter media at an opposite end of the flutes.
To enable removal of a filter element from the filter housing (not shown), typically a clearance gap is provided between the two components. To cause process fluids to pass through the filtration media rather than short circuit around the filter element, the filter element is often provided with a seal that abuts against the filter housing. Prior such filter elements are disclosed in U.S. Pat. No. 6,610,117 (Gieseke), U.S. Patent Application Publication No. 2006/0091061 (Brown), and U.S. Patent Application Publication No. 2006/0090434 (Brown, et al.) herein incorporated by reference in their entireties.
The present invention pertains to improvements in frames, seal support structures and how they are attached to a filter, such as a fluted filter.

Filter frame attachment and fluted filter having same


A frequency modulation signal demodulator includes: an optical signal that has a wavelength, a frequency modulation signal being superimposed onto the optical signal; an optical filter that inputs the optical signal and has a central wavelength of a pass band at a wavelength that is shifted from a central wavelength of a spectrum of the optical signal and that is set to allow the pass band to be located at one portion of the spectrum; and an asymmetry optical interferometer that demodulates the frequency modulation signal by splitting light which has passed through the optical filter, delaying different time between split lights, and interfering the split lights.

In recent years, with the spread of reconfigurable optical add/drop multiplexers (ROADM), availability of a network connection has increased. For this reason, there is an increasing demand for a function that may observe a network connection status in a simple manner. As one example of a technology that meets such a demand, a technology has been known that superimposes a control signal such as a supervisory signal onto an optical signal that carries data.
For example, in a WDM transmission system, the control signal for identifying an optical path is superimposed onto the optical signal (a main optical signal) of each wavelength (channel), which is included in a WDM signal. In this case, the optical transmission apparatus (hereinafter referred to as a "node") or a receiver may recognize a transmission source of the optical signal and a path of the optical signal by demodulating the control signal from the received optical signal.
In such a light transmitting system, data on each channel is modulated, for example, in a multi-level modulation manner such as QPSK, mQAM (m is 16, 64, and 256) and thus is transmitted along an optical transmission path. On the other hand, the control signal such as the supervisory signal, for example, is superimposed on main signal light in a frequency shift keying (FSK) manner.
Moreover, although an object of the disclosure is different, International Publication Pamphlet No. WO 2010/026757 discusses that a transmission apparatus phase-modulates or frequency-modulates an optical signal, which is phase-modulated based on a first signal, based on a second signal that is slower in speed than the first signal, and thus transmits the phase- or frequency-modulated optical signal. Furthermore, a receiving apparatus disclosed in International Publication Pamphlet No. WO 2010/026757 splits the optical signal received from a transmitting apparatus, performs delaying interference on one split optical signal and thus outputs interference light. Then, the receiving apparatus converts the interference light into an electric signal, and thus obtains the second signal based on the full-wave rectified signal and obtains the first signal based on the other split signal. Accordingly, in the technology disclosed in International Publication Pamphlet No. WO 2010/026757, multiple signals that are different in speed may be multiplexed, and information may be multiplexed in the shape of a single peak spectrum in a single wavelength slot.
Furthermore, Japanese Laid-open Patent Publication No. 02-096719 discusses an optical signal demodulation circuit including an optical filter that allows a specific optical frequency for the optical signal that is frequency-modulated to an n value (n is an integer that is 2 or greater) to pass through and a light receiving element that receives light that passes through the optical filter. The optical filter disclosed in Japanese Laid-open Patent Publication No. 02-096719 is a Mach-Zehnder type periodic optical filter that outputs optical frequencies corresponding to the n values to different output ports.
If the control signal is superimposed onto the optical signal in a frequency shift keying manner, the receiver, for example, demodulates the control signal by converting a frequency modulation component of the optical signal into an amplitude component. However, in this case, when the frequency modulation component for superimposing the control signal onto the optical signal is large (that is, when a range of frequency change is wide), there is a concern that quality of data (for example, an error rate) that is carried by that optical signal will deteriorate. For this reason, it is preferable that the frequency modulation component for superimposing the control signal onto the optical signal be small enough for the quality of the data not to deteriorate.
When the frequency modulation component of the optical signal is small, the amplitude component that is obtained from the frequency modulation component is also small in the receiver. In such a case, the amplitude component that is obtained from the frequency modulation component of the optical signal is easily influenced by an intensity modulation noise (an AM noise) that occurs in a transmission path between the transmitter and the receiver and the like. Therefore, detection sensitivity of the control signal is decreased in the receiver.
Moreover, the detection sensitivity of the frequency modulation signal that is superimposed onto the optical signal is not disclosed in International Publication Pamphlet No. WO 2010/026757 and Japanese Laid-open Patent Publication No. 02-096719.

Frequency modulation signal demodulator and light receiving apparatus


An integrated circuit system includes providing a semiconductor substrate having a semiconductor device provided thereon. A first dielectric layer is formed over the semiconductor substrate, and a first conductor core is formed in the first dielectric layer. A stop layer is formed over the first conductor core. A second dielectric layer is formed over the stop layer. A channel and a via are formed in the second dielectric layer. The channel and the via in the second dielectric layer are wet cleaned. A barrier metal layer is deposited to line the channel and the via in the second dielectric layer. The barrier metal layer is selectively etched from the bottom of the via in the dielectric layer, and a second conductor core is formed over the barrier metal layer to fill the second channel and the via to connect the second conductor core to the first conductor core.

In the manufacture of integrated circuits, after the individual devices such as the transistors have been fabricated in and on a semiconductor substrate or wafer, they must be connected, or "wired", together to perform the desired circuit functions. This interconnection process is generally called "metallization" and is performed using a number of different photolithographic, deposition, and removal processes to create contacts to the transistors, wire/channels to the contacts, and vias interconnecting the channels where there are more than one level of channels.
There are a number of different metalization techniques, but generally, a device dielectric layer is deposited over the transistors, openings are formed through the device dielectric layer down to transistor junctions and gates, and the openings are filled with a conductive metal to form contacts.
In one technique called the "single damascene" or "single inlaid" process, the formation of the first channels starts with the deposition of a thin first channel stop layer over the device dielectric layer. The first channel stop layer is an etch stop layer which is subject to a photolithographic processing step which involves deposition, patterning, exposure, and development of a photoresist, and an anisotropic etching step through the patterned photoresist to provide openings to the contacts. The photoresist is then stripped.
A first channel dielectric layer is formed over the first channel stop layer. Where the first channel dielectric layer is of an oxide material, such as silicon oxide (SiO2), the first channel stop layer is a nitride, such as silicon nitride (SiN), so the two layers can be selectively etched. The first channel dielectric layer is then subject to further photolithographic process and etching steps to form first channel openings in the pattern of the first channels. The photoresist is then stripped.
An optional thin adhesion layer is deposited on the first channel dielectric layer over the entire semiconductor wafer and lines the first channel openings to ensure good adhesion of subsequently deposited material to the first channel dielectric layer. The adhesion layer is a metal such as tungsten (W), titanium (Ti), or tantalum (Ta).
High conductivity metals, such as copper (Cu), diffuse easily through dielectric materials such as silicon oxide. This diffusion can result in a conductive buildup and cause short circuits in the integrated circuits. To prevent diffusion, a diffusion barrier is deposited on the adhesion layer. For copper conductor materials, the diffusion barrier layer is composed of materials such as tantalum nitride (TaN), titanium nitride (TiN), or tungsten nitride (WN).
However, these nitride compounds have relatively poor adhesion to copper and relatively high electrical resistance so they are problematic. For simplicity, the adhesion and barrier layers are sometimes collectively referred to as a "barrier" layer herein.
For conductor materials, such as copper and copper alloys, which are deposited by electroplating, a seed layer is deposited on the barrier layer and lines the barrier layer in the first channel openings to act as an electrode for the electroplating process. Processes such as electroless, physical vapor, and chemical vapor deposition are used to deposit the seed layer.
A first conductor material is electroplated on the seed layer and fills the first channel opening. The first conductor material and the seed layer generally become integral, and are often collectively referred to as the conductor core when discussing the main current-carrying portion of the channels.
A chemical-mechanical polishing/planarization (CMP) process is then used to remove the first conductor material, the seed layer, and the barrier layer above the first channel dielectric layer so the materials and layers are coplanar with the dielectric layer. The CMP process leaves the first conductor "inlaid" in the first channel dielectric layer to form the first channels. When a thin dielectric layer is placed over the first channels as a final layer, it is called a "capping" layer and the single damascene process is completed. When the layer is processed further for placement of additional channels over it, the layer is a via stop layer.
In another technique called the "dual damascene" or "dual inlaid" process, vias and channels are formed at the same time, generally over a completed single damascene process series of first channels. Effectively, two levels of channels of conductor materials in vertically separated planes are separated by an interlayer dielectric (ILD) layer and interconnected by the vias.
The initial step of the dual damascene process starts with the deposition of a thin via stop layer over the first channels and the first channel dielectric layer if it has not already been deposited as a capping layer. The via stop layer is an etch stop layer which is subject to photolithographic processing using a photoresist and anisotropic etching steps to provide openings to the first channels. The photoresist is then stripped.
A via dielectric layer is formed over the via stop layer. Again, where the via dielectric layer is of an oxide material, such as silicon oxide, the via stop layer is a nitride, such as silicon nitride, so the two layers can be selectively etched. The via dielectric layer is then subject to further photolithographic process using a photoresist and etching steps to form the pattern of the vias. The photoresist is then stripped. An etch stop layer between the via and the second channel opening may be optional depending upon the manufacturing process being used.
A second channel dielectric layer is formed over the via dielectric layer. Again, where the second channel dielectric layer is of an oxide material, such as silicon oxide, the via stop layer is a nitride, such as silicon nitride, so the two layers can be selectively etched. The second channel dielectric layer is then subject to further photolithographic process and etching steps to simultaneously form second channel and via openings in the pattern of the second channels and the vias. The photoresist is then stripped.
An optional thin adhesion layer is deposited on the second channel dielectric layer and lines the second channel and the via openings.
A barrier layer is then deposited on the adhesion layer and lines the adhesion layer in the second channel openings and the vias.
Again, for conductor materials such as copper and copper alloys, a seed layer is deposited on the barrier layer and lines the barrier layer in the second channel openings and the vias.
A second conductor material is electroplated on the seed layer and fills the second channel openings and the vias.
A CMP process is then used to remove the second conductor material, the seed layer, and the barrier layer above the second channel dielectric layer to form the second channels. When a layer is placed over the second channels as a final layer, it is called a "capping" layer and the dual damascene process is completed.
The layer may be processed further for placement of additional levels of channels and vias over it. Individual and multiple levels of single and dual damascene structures can be formed for single and multiple levels of channels and vias, which are collectively referred to as "interconnects".
The use of the single and dual damascene techniques eliminates metal etch and dielectric gap fill steps typically used in the metallization process for conductor metals such as aluminum. The elimination of metal etch steps is important as the semiconductor industry moves from aluminum (Al) to other metallization materials, such as copper, which are very difficult to etch.
From a reliability perspective, one of the most critical areas in a Cu dual-damascene (DD) structure is the bottom of the vias where two metal levels meet. In the typical manufacturing sequence, after the via is opened to the underlying metal conductor, it will undergo a wet clean process to remove polymers and other impurities generated during etch. Thereafter, it will undergo a degas process, such as an argon (Ar) sputter and hydrogen (H2) reactive pre-clean prior to formation of the barrier metal, Cu seed deposition and Cu plating. These pre-clean processes are designed to remove Cu oxide and etch residues (if any) from the via bottom. Insufficient pre-clean will result in increased via resistance, reduced yield and degraded interconnect reliability.
On the other hand, an aggressive sputter pre-clean process leads to loss of the critical dimension (CD) of the metal conductor, and contaminates the via sidewalls leading to poor adhesion between the barrier metal layer and the inter-metal dielectric (IMD) layer, and forms voids at the bottom corners of the via. Also, reactive pre-clean processes have limitations such as their reactivity with a wide range of contaminants such as carbon, fluorine, Cu oxide and etch residues which all have very different etch chemistries. It also reacts with constituents of a low-k IMD layer leading to loss of CD and increased k value. Thus, the extendibility of existing sputter and reactive pre-clean processes for future interconnect applications is questionable.
One proposed solution, referred to as a barrier first approach, skips the pre-clean processes by selectively removing the deposited barrier metal and contaminants only from the via bottom. However, these selectively removed contaminants are re-deposited on the barrier metal at the via sidewalls prior to deposition of the seed layer and electroplating of the metal, which poses some of the same reliability concerns.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.

Integrated circuit system using dual damascene process

Chartered Semiconductor Manufacturing, Ltd.


A bit holding system includes a transmission block coupled to the transmission shaft of a power hand tool, a plurality of clamping rods obliquely radially mounted in respective oblong holes on the transmission block to hold a bit at a front end of the transmission block, the clamping rods each having a threaded rear end extended out of the transmission block, a first impact member having a tapered, threaded inside wall threaded onto the threaded rear ends of the clamping rods and a plurality of equiangularly spaced and backwardly extended bottom teeth, a spring supported second impact member mounted around the transmission block between the first impact member and the reversible motor drive, the second impact member having teeth acting with the teeth of the first impact member, and a shell for holding down by hand to stop the second impact member from rotary motion, causing it to impact a resisting force to the first impact member upon each rotation cycle of the first impact member when the first impact member is turned with the clamping rods and the transmission block.

The present invention relates to a power hand tool, and more particularly to a bit holding system for a power hand tool which can be controlled to provide a high torsional force intermittently.
FIG. 1 shows a power hand drill according to the prior art. According to this structure of power hand drill, a transmission block is coupled to the motor shaft of a reversible motor drive, a plurality of clamping rods are obliquely mounted around the transmission block, each clamping rod having a threaded inner end threaded into a respective screw hole on the transmission block, and a control ring for adjusting the position of the clamping rods. The control ring has a serrated front edge. When turning the control ring to adjust the position of the clamping rods, a special T-shaped driving tool is used and inserted into a positioning hole on the casing of the power hand drill to force a bevel gear of the T-shaped driving tool into engagement with the serrated front edge of the control ring, and therefor the control ring is turned when rotating the T-shaped driving tool. Because the T-shaped driving tool must be used to adjust the position of the clamping rods when mounting or dismounting the bit, the T-shaped driving tool must be well kept with the power hand drill.

Bit holding system for a power hand tool


A paper tissue such as a facial tissue or a disposable handkerchief and a method of making the tissue. The method includes passing the tissue paper web through an embossing nip formed between a first and a second embossing roll, wherein at least one of the embossing rolls comprises at least 30 embossing elements per square centimeter and applying a transferable lotion to at least portions of the tissue paper web.

Paper webs or sheets, sometimes called tissue or paper tissue webs or sheets, and products made therefrom, such as paper handkerchiefs, sometimes also called facial tissues, find extensive use in modern society. Such items as facial and toilet tissues and kitchen towels are staple items of commerce, all of which are herein referred to as paper tissue products. It has long been recognized that important physical attributes of these products are their strength and thickness/caliper, their softness and smoothness, their absorbency, and their lint resistance. Research and development efforts have been directed to the improvement of each of these attributes without seriously affecting the others as well as to the improvement of two or three attributes simultaneously.
Softness and smoothness relate to the tactile sensation perceived by the consumer when holding a particular product, rubbing it across the skin, or crumpling it within the hands. The tactile sensation is a combination of several physical properties. The tactile sensation can be well captured by the objective parameter of the physiological surface smoothness (PSS) parameter as known e.g. from U.S. Pat. No. 5,855,738. As important for the tactile sensation of consumers is the thickness/caliper of a tissue product.
Strength is the ability of the product to maintain physical integrity and to resist tearing, bursting, and shredding under use conditions.
Absorbency is the measure of the ability of a product to absorb quantities of liquid, particularly aqueous solutions or dispersions. Overall absorbency as perceived by the consumer is generally considered to be a combination of the total quantity of a liquid a given mass of paper tissue will absorb at saturation as well as the rate at which the mass absorbs the liquid.
Lint resistance is the ability of the fibrous product, and its constituent webs, to bind together under use conditions, including when wet. In other words, the higher the lint resistance is, the lower the propensity of the web to lint will be.
Through-air-drying can provide high wet burst strength as well as relatively high caliper. Though-air-drying facilities, however, are not generally available on conventional paper making machines and the provision of such equipment means a considerable financial investment. Further, though-air-drying facilities typically have an increased energy consumption as compared to more conventional drying facilities. Therefore it is still of interest to provide superior paper qualities employing conventional paper machines.
It is known in the art to provide facial tissue and paper handkerchiefs with additives to achieve skin care or pharmaceutical benefits, e.g. in the from of lotions. However, the present invention attempts to alleviate the detrimental effects of highly transferable lotions by providing a paper quality and structure particularly suitable for lotioned tissue paper, which still can be produced in a very economic fashion. In particular, the present invention can provide any or all of the following:                improved strength, especially wet burst strength, absorbency and lint resistance.        improved tactile sensation of softness, smoothness and thickness.        a cost effective way to manufacture improved tissue on conventional paper machines and/or through-air-dried paper machines.        a process that allows for the economic application of a lotion.        a product that avoids unwanted premature lotion transfer while ensuring good lotion transfer to a user when needed.


Primary amines, ammonia, or mixtures thereof can be detected using a reagent comprising from about 650 ppm to about 25 percent by weight of phthalic dicarboxyaldehyde; from about 74 to about 99.88 percent by weight of an alkali metal borate; and, from about 550 ppm to about 22 percent by weight of a nucleophile.

1. Field of the Invention
The field of technology of the invention is the treatment of fluid systems wherein corrosive conditions may exist, and more specifically, the detection of primary amines or ammonia in such fluid systems.
2. Description of the Prior Art
The uses of steam include comfort heating, hot water heating, food services, humidification, sterilization, and laundry services. Direct steam injection can be used to humidify room air or to heat liquids or objects. More commonly, the steam flows through a heat exchanger and transfers energy to another fluid without making direct contact with that fluid. The term condensate refers to steam that has condensed to the liquid state (water) during the heat exchange process. Condensate is commonly collected through a system of tanks, traps, and receivers so that it can be returned to the boiler and used as feed water.
Boiler feed water typically consists of both make-up water and returned condensate. The make-up water is generally purified water from a primary source such as a city water system, a well, or a river. Make-up water replaces hydraulic losses in the boiler system such as steam that was not returned as condensate. Another major hydraulic loss is boiler blowdown or water that is released from the boiler itself. Blowdown is necessary to limit the concentration of dissolved solids in the boiler water. A primary objective in the successful operation of any steam generating system is to maximize its overall efficiency and reliability while minimizing problems related to water and steam quality. One of the greatest factors in achieving this objective is the amount and purity of condensate returned to the boiler as feed water. Returned condensate, being condensed steam, is extremely pure and has a relatively high heat content, making it ideal for boiler feed water.
As more condensate is returned, less make-up water is required, thereby saving on both water and pretreatment costs. Since condensate is already hot (typically between 180.degree. and 200.degree. F.), less fuel is required to convert it into steam. The high purity of condensate reduces the need for boiler blowdown, thereby reducing water, energy, and chemical loss. The overall scale-forming tendency of the boiler water is also reduced by condensate return and results in cleaner heat transfer surfaces.
While the use of high purity hot condensate contributes to the efficiency of steam generating equipment, the presence of very small amounts of contaminants in the liquid condensate can cause damaging corrosion of most ferrous and nonferrous metals in the condensate system, including piping and equipment. When metal oxide corrosion products formed in the condensate system are returned to the boiler they have a strong propensity to deposit on the heat transfer surfaces. This deposition limits heat transfer efficiency in the boiler and can initiate under-deposit corrosion mechanisms. Therefore, there is a strong desire to limit corrosion in boiler condensate systems.
The major causes of corrosion are dissolved gases such as carbon dioxide (CO.sub.2) and oxygen (O.sub.2). Oxygen is present due to air leakage into the condensate system components and can be excluded by good design and maintenance practices. The major source of CO.sub.2 in the steam is the thermal breakdown of bicarbonate and carbonate alkalinity present in the feed water. At boiler operational temperatures and pressures, the following alkalinity reactions occur: EQU 2 NaHCO.sub.3 .fwdarw.Na.sub.2 CO.sub.3 +CO.sub.2 +H.sub.2 O (Equation 1) EQU Na.sub.2 CO.sub.3 +H.sub.2 O.revreaction.2 NaOH+CO.sub.2 (Equation 2)
The breakdown of the bicarbonates (see Equation 1) proceeds to 100% completion. Carbonate breakdown (see Equation 2) proceeds from about 70 to about 100% completion, depending on the boiler pressure. The CO.sub.2 liberated in both reactions is carried with the steam and dissolves in the condensate. As it dissolves, it forms carbonic acid: EQU CO.sub.2 +H.sub.2 O.revreaction.H.sub.2 CO.sub.3 .revreaction.H.sup.+ +HCO.sub.3.sup.- (Equation 3)
Since condensate is extremely pure, even small quantities of carbonic acid can significantly lower condensate pH and correspondingly increase its corrosivity. As little as 1 ppm of CO.sub.2 in the steam can depress the pH of the condensate to 5.5. High alkalinity feed water will produce very corrosive condensate.
The corrosion reaction of carbonic acid with iron produces ferrous bicarbonate, Fe(HCO.sub.3).sub.2, and hydrogen gas: EQU Fe+2H.sup.+ +2 HCO.sub.3.sup.-2 .fwdarw.Fe(HCO.sub.3).sub.2 +H.sub.2 (Equation 4)
The soluble ferrous bicarbonate is carried away with the condensate, leaving behind an area of obvious metal loss. The corrosion usually appears as a uniform attack leaving a rather smooth surface where the iron has dissolved away.
Corrosion of a condensate system can be inhibited by either mechanical or chemical means, although neither is completely effective when used alone. Nearly all modern boiler systems are protected by a combination of the two. Mechanical elimination of all avenues of air and process fluid in-leakage is an essential part of system protection. Feed water oxygen can be completely eliminated by mechanical deaeration plus the use of a chemical oxygen scavenger. In addition, various pretreatment processes such as hot lime softening, dealkylization, or demineralization can be used to reduce or eliminate make-up water bicarbonates and carbonates. However, even with pretreatment to reduce potential CO.sub.2, chemical inhibitors are usually necessary for complete protection.
Three basic types of chemical corrosion inhibitors are used for condensate corrosion control: neutralizing amines, filming amines, and oxygen scavengers/metal passivators.
Neutralizing amines are typically volatile, alkaline compounds that are added to either the boiler feed water or the steam supply systems. They function by volatilizing into the steam and re-dissolving in the condensate with the CO.sub.2. The amines chemically neutralize any acid present in the system. They raise pH to a level at which the condensate is much less aggressive towards the metallic components of the system.
Most commercially available neutralizing amine condensate treatments are blends of various amines. The blends offer combinations of certain characteristics that are unique to each amine. The characteristics of greatest importance when selecting amines are volatility, acid neutralizing ability, and basicity. Every volatile substance in a boiler system, or similar type system, has a specific volatility or vapor to liquid distribution ratio. The distribution ratio is defined by: EQU V/L=Concentration in the Vapor or Steam Phase/Concentration in the Liquid or Condensate Phase
The distribution ratio indicates the portion of a given amine that will condense with the condensate or stay with the steam in a given piece of equipment. To neutralize CO.sub.2, the amine must be in the condensate as the CO.sub.2 dissolves.
Another very important criterion for amine choice is acid neutralizing ability. This is the amount of amine required on a weight basis to neutralize the carbonic acid present. The amine reacts with the carbonic acid in solution to form an amine bicarbonate: EQU RNH.sub.2 +H.sup.+ +HCO.sub.3.sup.- .fwdarw.RNH.sub.3.sup.+ +HCO.sub.3.sup.-(Equation 5)
Although Equation 5 is for a primary amine, secondary and tertiary amines are also used for condensate treatment.
Once all of the acid in the condensate system has been neutralized (at a pH of about 8.3), amine basicity becomes important. Any additional amine added to the condensate system will hydrolyze, raising the condensate pH: EQU RNH.sub.2 +H.sub.2 O.fwdarw.RNH.sub.3.sup.+ +OH.sup.- (Equation 6)
Basicities of neutralizing amines also vary. Above a certain pH, additional quantities of the weaker neutralizing amines do little to further increase the pH.
Neutralizing amine programs are most effective when fed to maintain a condensate pH of from about 8.5 to about 9.5, a range of maximum corrosion protection for both ferrous and copper alloys. Because the amines are added to the system in direct proportion to the amount of CO.sub.2 in the steam, high alkalinity feed water requires considerable amounts of amine to obtain the desired pi range. The cost of such a program may be prohibitive and alternative means of corrosion protection may be desired.
Filming amines are high molecular weight amines with long-chain hydrocarbon alkyl groups. The amine-containing end of the molecule chemisorbs to the metal surfaces of the condensate system while the hydrophobic tail of the molecule extends away from the metal surface. A monomolecular, non-wettable film is thereby created on all metal surfaces that come into contact with condensate containing the filming amine. This film acts as a physical barrier between metal surfaces and corrosive condensate, offering protection against CO.sub.2. Unlike neutralizing programs, filming amines protect the condensate system from O.sub.2 attack. Since filming amines react with the metal surface instead of with a dissolved corrosive species, their feed rates are not directly proportional to the amount of contaminate (such as O.sub.2 and CO.sub.2) in the steam. Instead, the amount of filming amine required is related to the system's surface area.
The protective amine film is generally quite stable, but extreme pH conditions (high or low) may cause it to strip off the metal surfaces. Filming amines must be fed continuously to ensure that no gaps in protection occur in any parts of the system. However, excessive feed may cause the filming amine to accumulate as sticky masses in receivers, traps, valves, or any collection point. Therefore, periodic field testing is required to maintain a specified amount of filming amine in the condensate to avoid such deposits.
An alternative to filming amines for dissolved oxygen corrosion inhibition in condensate systems is the use of volatile oxygen scavengers in combination with neutralizing amines. The scavenger reacts directly with any oxygen present while the neutralizer provides protection from CO.sub.2 corrosion. Such programs are controlled by the same parameters as neutralizing amine programs.
Examples of amines that are commonly added to boiler water systems include: diethylaminoethanol; morpholine; methoxypropyl amine; cyclohexyl amine; monoethanol amine; methyl amine; ethyl amine; propyl amine; butyl amine; t-butyl amine; octadecyl amine; and, mixtures of these amines.

Method and apparatus for detecting amines and ammonia by fluorescence


A light-guide plate (1) arranged at a display face (2a) of a liquid crystal (2) and illuminates radiating light from a light source (3) to the display face (2a) is constructed by a light permeability base portion (10) having a first face (8), a second face (9) of the rear face side of the first face (8), and a third face (5) guiding light from the light source (3) from side face, an adhesive layer (11), and light permeability sheet (12) forming plural prism grooves on a light emission face (6) with the predetermined interval and providing on the adhesive layer (11).

The present invention relates to a light-guide plate and a method for manufacturing the same, for example, to so-called front light which is set at display front side of various kinds of reflective type display units and the like including a reflective type liquid crystal to illuminate.
A back light and a front light are proposed for illuminating a liquid crystal display board and the like. In these units, light is guided to a light-guide member by providing a light source at a side face of the light-guide member comprising a transparent board, and plane light emission is realized by diffusing the light by using a light emission pattern such as prism grooves and the like provided at the surface of the light-guide member. Such the light-guide member is called a light-guide plate because it is generally a flat shape.
A method for forming a light emission pattern on the light-guide member by injection molding method for example is known as a technique forming such the light emission pattern. However, there are problems in the technique that shape fault of the light emission caused by lack of filling up resin material generates and it has a limit to make the light-guide member thin.
The technique forming the light emission pattern by performing press working to material of the light-guide member is proposed in JP-11-147255 for example. The technique using the press working has effects reducing the shape fault and design thin light-guide member.
However, making the light-guide member thin by the light emission pattern using press working has problems that thickness of an incident part of light source becomes thin and usage efficiency decreases.
Recently, a front light is becoming the main current, which illuminates display plane of liquid crystal directly by arranging at display front side of a reflective type liquid crystal instead of the back light illuminating the transparent type liquid crystal from back side. A display unit constructed by the reflective type liquid crystal and the front light has advantages that angle of visibility is made large and power consumption is made little.
Constructions are known as the front light, which are disclosed in Japanese Patent No. 2,925,530, JP-A-2001-110223, and JP-A-2001-23424.
In the construction of each of the above official gazettes, a face facing a liquid crystal of light-guide plate is made flat, half-circular concave portions or convex portions of a sawlike prism shape or a triangle prism shape in section are formed at face of the opposite side, and incident light from the end face of the light-guide plate is totally reflected at these prism-shaped face. By these constructions, illumination is performed by letting the liquid crystal direct, and uniform illumination over whole plane is performed by radiating from light emission face. Further, the construction bonding with liquid crystal through a refraction layer having smaller refractive index than the light-guide plate is disclosed in JP-A-2000-221501.
On the other hand, it is known that a light-guide plate for a front light is molded integratedly by injection molding method using light permeability resin material such as polycarbonate, methyl polymethacrylate resin, and so on. The process thereof will be described simply referring the flowchart of FIG. 11A, first, size of an external form of a light-guide plate determined based on the product specification and known values of quantity of light source and directivity are inputted to a simulation program of a personal computer so as to design for trial computing ideal arrangement of prism grooves and numbers of arrangement in Step S10. Continuously, the light-guide plate is actually produced by hand-made based on the design for trial in Step S11. Then, it is judged whether density of quantity of light from light emission face is uniform or not by setting a light source on the trial piece in Step S12, and when it is uniform, an exclusive injection-molding die is produced advancing the next step S13.
On the other hand, when density of quantity of light from light emission face of the light-guide plate is not uniform in Step S12, the light-guide plate as produced for trial again returning to Step S11 and repeats Steps S11 and S12 till density of quantity of light becomes uniform.
Next to the above Step S13, molding using the produced injection-molding die is performed so as to finish molding of the light-guide plate advancing to Step S14. Continuously, setting the light source in Step S15, whether density of quantity of light from light emission face of the light-guide plate is uniform or not, when it is uniform, it is shipped as a product advancing to the next Step S17.
On the other hand, when it is decided that density of quantity of light from light emission face of the light-guide plate is not uniform in Step S15, correction of the injection-molding die is performed advancing to Step S16, and the light-guide plate is molded again returning to Step S14 and repeats Steps S15, S16 and S14 till density of quantity of light becomes uniform.
It is indispensable condition that the prism grooves 7 are molded exactly in valley shape having planes to perform reflection of light as shown in FIG. 11B for the light-guide plate 1 molded integratedly with the prism grooves 7 by going through the above processes.
However, according to resin injection molding method using the above injection molding die, the prism grooves 7 are possibly molded in valley shape having dull planes as shown in FIG. 11C depending on the shape of the prism grooves 7, a part of molding, and condition of injection molding. When the prism grooves 7 are molded integratedly in such the valley shape having dull planes, it can not be used as a light-guide plate 1.
Further, it is possibly difficult to mold the light-guide plate integratedly since deformation such as bending and the like caused by heat contraction after injection molding generates. Further more, there are defects that an injection-molding die requiring accuracy of micron order such a light-guide plate requires is considerably expensive and life of the die is short. Additionally, since the correction of die for the above injection molding needs considerable skill, there is a problem needing man-hour for the correction.

Light-guide plate and method for manufacturing the same


A method of generating a plant tolerant of environmental stress conditions, the method comprising the step of expressing within the plant exogenous polynucleotides encoding enzymes capable of catalyzing proline production, wherein the exogenous polynucleotides are expressed in a manner so as to allow accumulation of the enzymes within a subcellular organelle of the plant. The invention further describes novel polynucleotides and nucleic acid constructs useful in implementing the methods and a transgenic plant resultant therefrom.

The present invention relates to methods of generating plants tolerant of extreme environmental stress conditions and to plants generated thereby. More particularly, the methods of the present invention are effected by over expression of enzymes involved in the biosynthesis of proline and/or downregulation of endogenous proline degrading enzymes. The present invention also relates to polynucleotides including a novel stress sensitive promoter and encoding a novel proline dehydrogenase (oxidase) enzyme which catalyses the first step in plant proline degradation and as such, can be specifically targeted for downregulation in order to increase proline level in plants.
Environmental conditions such as high salinity, drought and extreme temperatures severely limit plant growth and/or yield and as such, geographical locations which are characterized by such environmental conditions are typically devoid of crop plants.
Extreme environmental conditions typically lead to a lack of available water molecules which in turn leads to osmotic stress in the plant. Water loss from a plant grown under such conditions can be counteracted for a short period of time via various stress tolerance mechanisms, which are sometimes species-specific.
Stress tolerance is a multi-gene trait, encompassing various biochemical metabolic pathways which are found in bacteria, fungi, algae and plants.
The best characterized biochemical response of plant cells to osmotic stress is the synthesis of special organic solutes (osmolytes) which accumulate at high cytoplasmic concentrations and as such elevate the internal osmotic pressure to eliminate water loss from the cell and restore cell volume and turgor (Serrano and Gaxiola, 1994).
Under low water conditions, when the water potential of the soil in the rooting zone declines and shoot transpiration is limited, plants generate a gradient of negative water potential throughout the root and shoot tissues up to the leaves such that water from the soil can be driven to the upper parts of the shoots.
To generate such a gradient, plants have developed osmotic adjustment ability in which gradual accumulation of solutes is effected by the cells in order to decrease their water potential without any accompanying decrease in turgor. The accumulation of ions during osmotic adjustment appears to occur mainly within the vacuoles, where the ions are kept out of contact with enzymes in the cytosol or sub-cellular organelles. Because of this compartmentation of ions, other solutes must accumulate in the cytoplasm to maintain water potential equilibrium within the cell. These solutes, which are termed compatible solutes or osmolytes, are organic compounds that do not interfere with intracellular enzyme functions (Taiz and Zeiger, 1991).
Plant osmolytes are typically uncharged at neutral pH, and highly soluble in water (Ballantyne and Chamberlin, 1994). In addition, at high concentrations osmolytes have little or no perturbing effect on macromolecule-solvent interactions (Yancey, 1994). Furthermore, unlike perturbing solutes (such as inorganic ions) which readily enter the hydration sphere of proteins, thus favoring unfolding, compatible osmolytes tend to be excluded from the hydration sphere of proteins and as such stabilize folded protein structures (Low, 1985).
Proline is the most common osmolyte and is accumulated by a variety of organisms including bacteria, fungi, algae, invertebrates and plants (for review see Delauney and Verma, 1993, Hare and Cress, 1997). Other well-studied osmolytes include sugar alcohols like sorbitol and quaternary amines, such as glycine-betaine.
Solutes accumulation under stress (osmotic adjustment) is probably the most distinctive feature of an adaptive response to stresses linked to water deficit, such as drought, freezing and salinity.
Osmotic adjustment takes time, while fast reduction in plant water status during imposition of osmotic shock does not leave enough time for adjustment. This implies that osmotic adjustment may not be a very effective mechanism for conferring drought resistance when plants are grown in very light tropical or sandy soils, which are characterized by a very low water holding capacity (Blum, 1996). Therefore, acquiring high levels of cellular osmolytes in genetically modified plants could improve their osmotic tolerance when grown in such rapidly changing environments.
Proline and Stresses:
In higher plants, proline accumulation is a common metabolic response to water deficit and salinity stress, and as such, proline accumulation has been the subject of numerous reviews over the last 20 years (see for example, Stewart and Larher, 1980; Thompson, 1980; Stewart, 1981; Hanson and Hitz, 1982; Rhodes, 1987; Delauney and Verma, 1993; Samaras et al., 1995; Taylor, 1996).
Proline also appears to be the preferred organic osmolyte in many other organisms. Genetic studies in prokaryotes demonstrated that proline is an essential compatible solute capable of conferring osmo-protection (Csonka, 1989). Increased osmo-tolerance of bacteria has been achieved by proline over-production caused by altered feedback inhibition of the proline biosynthesis pathway (Csonka, 1981; Smith, 1985).
Numerous studies have linked proline accumulation in plants to high salinity conditions, water deprivation, high and low temperature, toxicity of heavy metals, pathogen infections, anaerobiosis, nutrient deficiencies, atmospheric pollution and UV irradiation.
For example, soluble proline accumulates in leaves of many halophytic higher plant species grown in saline environments (Stewart and Lee, 1974; Treichel, 1975; Briens and Larher, 1982), in leaf tissues and shoot apical meristems of plants grown under water stress (Barnett and Naylor, 1966; Boggess et al., 1976; Jones et al., 1980), in desiccating pollen (Hong-qi et al., 1982; Lansac et al., 1996), in root apical regions grown under a low water potential (Voetberg and Sharp, 1991), and in suspension cultures of plant cells adapted to water stress (Tal and Katz, 1980; Handa et al., 1986; Rhodes et al., 1986), or NaCl stress (Katz and Tal, 1980; Tal and Katz, 1980; Treichel, 1986; Binzel et al., 1987; Rhodes and Handa, 1989; Thomas et al., 1992).
Studies reviewed by Hare and Cress (1997) pointed out that during the imposition of a stress, an increase in proline level in planta is linked to the amelioration of negative physiological effects. Analysis of experimental evidence collected from many studies suggests that proline accumulation may also serve to protect membranes and proteins against the adverse effects of high concentrations of inorganic ions and temperature extremes (Pollard and Wyn Jones, 1979; Paleg et al., 1981; Nash et al., 1982; Paleg et al., 1984; Brady et al., 1984; Gibson et al., 1984; Smirnoff and Stewart, 1985; Rudolph et al., 1986; Santarius, 1992; Santoro et al., 1992), as a protein-compatible hydrotope (Srinivas and Balasubramanian, 1995), and as a hydroxyl radical scavenger (Smimoff and Cumbes, 1989).
Under conditions of water or salinity stress in plants, proline accumulates primarily in the cell cytosol (Leigh et al., 1981; Ketchum et al., 1991). For example, in cell cultures of tobacco which were adapted for growth under 428 mM NaCl proline represents over 80% of the free amino acid pool (Rhodes and Handa, 1989). Thus, assuming a uniform distribution of proline in the cytosol, this amino acid is present in the cell cytosol at a concentration of 129 mM (Binzel et al, 1987). However, if confined to the cytoplasm, the concentration of proline could exceed 200 mM in these cells and therefore contribute substantially to cytoplasmic osmotic adjustment (Binzel et al., 1987). Similarly, the cytosolic proline concentration of salt stressed Distichlis spicata cells (treated with 200 mM NaCl) is estimated at around 230 mM (Ketchum et al. 1991).
Proline represents a major solute in the apical millimeter of maize roots, reaching concentrations of 120 mM in roots growing at water potential of −1.6 MPa (Voetberg and Sharp, 1991). The accumulated proline accounts for a significant fraction (about 50%) of the osmotic adjustment in this region (Voetberg and Sharp, 1991). In response to a water deficit, proline accumulates in maize root apical meristems with a marked increase of proline deposition in the growing region; this accumulation appears to be abscisic acid (ABA) dependent (Ober and Sharp, 1994; Sharp et al., 1994). Although maize roots are known to synthesize proline (Oaks et al., 1970), at present it is unclear whether increased deposition of proline in the apical region is a consequence of increased transport to the apex via the phloem, or local de novo synthesis of proline in the apex (Voetberg and Sharp, 1991).
Studies conducted on hydroxyproline-resistant mutants of barley and winter wheat have identified plant lines that accumulate greater quantities of proline than wild-type (Kueh and Bright, 1981; Dorffling et al., 1993). In winter wheat the hydroxyproline-resistant lines are significantly more frost tolerant than wild-type (Dorffling et al., 1993). However, it appears that the concentrations of proline accumulated in these mutants may be an order of magnitude lower than that required to produce a significant physiological effect on osmotic stress tolerance (Lone et al., 1987).
Under stress conditions, proline synthesis is also participates in alleviating cytoplasmic acidosis, and may maintain NADP+/NADPH ratios at values compatible with metabolism (Hare and Cress, 1997). Rapid catabolism of proline upon relief of stress may provide reducing equivalents that support mitochondrial oxidative phosphorylation and the generation of ATP useful for recovery from stress and repair of stress-induced cellular damage (Hare and Cress, 1997).
Proline Biosynthiesis:
In E. coli, the first two steps in the proline synthesis pathway (FIG. 1) are catalyzed by an enzymatic complex formed from gamma-glutamyl kinase (GK), which is encoded by the proB gene, and gamma-glutamylphosphate reductase (GPR or GSD), which is encoded by proA. The delta-pyrroline-5-carboxylate (P5C) product generated by the complex, or from the arginine biosynthesis pathway (FIG. 1), is immediately reduced to proline in a reaction catalyzed by delta-pyrroline-5-carboxylate reductase (P5CR), which is encoded by proC.
The first enzyme, GK, is feedback regulated by proline and, therefore, proline accumulation does not occur in wild-type E. coli cells. The E. coli proB74 mutated gene encodes a modified GK enzyme, which is insensitive to high proline concentrations of up to 100 mM, and which, therefore, can drive proline synthesis in the presence of high proline concentration in the cells. The proB74 gene differs at position 107 of the ProB (GK) amino acid sequence (aspartic acid to asparagin). Increased proline production and osmo-tolerance in bacteria has been observed in mutants carrying the proB74 gene (Csonka et al., 1988).
In young plants, proline is produced from either glutamate or ornithine (FIG. 1), while in mature plants or during the exposure to stress the glutamate pathway usually dominates (Roosens et al., 1998). A bifunctional enzyme, delta-pyrroline-5-carboxylate synthase (P5CS, FIG. 1) catalyzes the first two steps of P5C formation and shows a certain homology to the deduced amino acid sequence of the bacterial proB and proA Fujita et al., 1998; Ginzberg et al., 1998; Hu et al., 1992; Strizhov et al., 1997). It is assumed that P5CS activity is confined to the cytosol, since full length P5CS cDNAs isolated thus far lack a defined plastid-targeting transit-peptide sequence.
The activity of P5CS is feedback regulated by concentrations of proline as low as 10 mM (Hu et al., 1992). Expression of a cDNA encoding a wild-type P5CS of Vigna in tobacco rendered the recipient plants relatively tolerant to salt stress (Kishor et al., 1995), despite the enzyme's sensitivity to low proline concentrations. However, the measurements relating to osmotic adjustment which were performed in these transgenic plants, were not accepted by some plant physiologists (Blum et al., 1996).
U.S. Pat. No. 5,639,950 to Verma et al., describes the production of plants containing a cDNA clone encoding P5CS, with both gamma-glutamyl kinase and glutamic-gamma-semialdehyde dehydrogenase activities that catalyzes the first two steps in plant proline biosynthesis. This invention also provides methods for increasing the salt tolerance and drought resistance of plants, and for increasing the proline production activity in plants.
A mutated P5CS, showing relative insensitivity to proline inhibition was generated via site directed mutagenesis (Zhang et al., 1995). Such a mutant may further increase proline accumulation when expressed in transgenic plants. However, the presence of P5CS inhibitor that inactivates its enzymatic activity in roots (Zhang et al., 1995) may negatively affect activity of both endogenous as well as exogenous P5CSs at the primary site exposed to salinity stress.
Studies in which overexpression of P5CR (FIG. 1) was effected in transgenic plants, did not alter the proline level therein, and as such this enzyme is not considered a likely candidate for overexpression in plants (Szoke et al., 1992).
Proline Degradation in Plants:
Proline oxidation to glutamate is carried out in the mitochondria by the sequential action of proline dehydrogenase (PDh) and P5C-dehydrogenase (P5C-Dh) (FIG. 1). Both enzymes are bound to the matrix side of the inner mitochondrial membrane. A cDNA encoding PDh has been isolated from Arabidopsis (Kiyosue et al., 1996). Two forms of the second enzyme P5C-Dh have also been identified in plants but their corresponding genes have not been isolated (Forlani et al., 1997).
Transcription and Activity of Proline Biosynthesis and Begradation Enzymes During Stress Imposition and Relief:
Analysis of transcription during stress and recovery periods showed that the levels of P5CS transcripts were elevated during stress and gradually diminished during the post-stress period (Ginzberg et al., 1998; Peng et al., 1996; Strizhov et al., 1997; Yoshiba et al., 1997).
Conversely, transcript levels of PDh gradually reduced within several hours of stress, and rapidly increased upon relief from stress (Peng et al., 1996; Yoshiba et al., 1997). PDh transcript levels also increased by exogenously applied proline (Peng et al., 1996). The enzymatic activities in vitro of PDh and P5C-Dh have been reported to be strongly reduced by high concentrations of Cl− anions, while in intact cells no conspicuous Cl− inhibition of P5C-Dh form I has been recorded (Forlani et al., 1997; Peng et al., 1996).
Although the prior art documents mentioned hereinabove describe methods for increasing the proline level in plants, the increase in proline level demonstrated by these methods falls short of that observed in wild type plants grown under extreme environmental stress conditions which is approximately 40-300 times higher than that of non-stressed plants. As such, it is believed that these prior art methods cannot effectively produce a desired osmotic protective effect under conditions of extreme stress.
Thus, the present invention relates to a method for generating a plant tolerant of environmental stress conditions, which plant is capable of accumulating high levels of proline. Generating plants tolerant of environmental stress conditions according to the present invention is effected by increasing proline biosynthesis in the plant via overexpression of exogenous prokaryotic or eukaryotic proline biosynthetic enzymes, preferably in the chloroplast, and in addition or alternatively blocking or downregulating the activity of endogenous enzymes, such as proline dehydrogenase (PDh) and P5C-Dh, which are responsible for proline degradation. The present invention further relates to an alfalfa (Medicago sativa) gene including a novel stress sensitive promoter and further encoding a novel proline dehydrogenase (oxidase) enzyme which catalyses the first step in plant proline degradation and as such can be specifically targeted for downregulation.

Plants tolerant of environmental stress conditions, methods of generating same and novel polynucleotide sequence utilized thereby


Resins having a softening point from 10.degree. C. to 120.degree. C. especially 10.degree. C. to 80.degree. C. being a copolymer of a feed which is predominantly C.sub.5 olefines and diolefines and 10 to 60 wt. % of one or more monovinyl aromatic compounds are used as a tackifier for acrylic polymers or copolymers particularly in aqueous based pressure sensitive adhesives.

The present invention relates to pressure sensitive adhesives comprising a synthetic latex and a tackifier resin.
Pressure sensitive adhesives are, among other applications, used in the tape and label field. A pressure sensitive adhesive may be used in a number of applications such as masking tape, electrical tape and medicinal tapes for holding dressings and the like in place. The term label covers an broad range of products and includes items such as price tags in the supermarket and labels on glass or plastic containers. In the case of "labels " two types of bonding are required namely permanent and removable. Permanent bonding is required for items such as labels on glass or plastic containers when the life of the label will be relatively long. Removable bonding is desirable for items such as price tags and peelable tape.
Pressure sensitive adhesives should have a high initial tack so that the adhesive surface merely needs to be contacted and pressed to a substrate to achieve bonding. There should be little or no requirement to hold the adhesive and substrate in position for any significant time while a bond develops. Depending upon the strength of adhesion required the bonding force of the adhesive may increase with time to provide a relatively permanent bond.
It is known to prepare at least three different types of adhesives using natural or synthetic tackifier, natural or synthetic resins, or blends thereof, namely, hot melt adhesives, solution adhesives and aqueous based adhesives. Hot melt adhesives are made from a blend of resins and are normally solid at room temperature. Hot melt adhesives require an elevated temperature for application to a substrate necessitating some type of hot melt gun.
Solution adhesives such as those described in U.S. Pat. Nos. 4,037,016, 4,048,124 and 4,248,748 do not suffer from the same drawback since the adhesives comprise a solution of a tackifier resin or a blend of tackifier resins in a low boiling hydrocarbon solvent. When the adhesive is applied to a substrate the solvent evaporates. Due to environmental concerns and the rising cost of hydrocarbon solvent there has been an increasing need to reduce or eliminate the hydrocarbon solvent in such adhesives. Accordingly, the adhesives industry is seeking improved aqueous based adhesive compositions. Existing aqueous based adhesive compositions usually comprise a natural or a synthetic latex in admixture with cellulose materials such as starch or natural or synthetic tackifier resins.
U.S. Pat. No. 4,189,419 to Avery International disclosed a pressure sensitive adhesive comprising from about 50 to 60% by weight on a dry basis of a tackifier and from about 50 to 40% by weight on a dry basis of a carboxylated styrene butadiene polymer (SBR).
A paper entitled "Styrene Butadiene Latexes for Adhesive Applications" by Robert G. Kahn of Dow Chemical, published in Adhesives Age, December of 1977 discloses a similar pressure sensitive adhesive composition which also contains butyl benzyl phthalate, as a "plasticizer". While the amount of plasticizer is relatively small the plasticizer comprises a hydrocarbon phase in the adhesive and the composition is not entirely aqueous based.
U.S. Pat. No. 4,179,415 issued Dec. 18, 1979, to Johnson and Johnson discloses a substantially aqueous based adhesive composition containing a latex having a high proportion of isoprene.
United Kingdom patent application 2097410A discloses novel pressure sensitive adhesives comprising a latex of a polymer and a tackifier resin the polymer being obtained from particular amounts of vinyl or vinylidene aromatic monomers and C.sub.4 -C.sub.8 conjugated diene monomers and an unsaturated carboxylic acid. Similarly European patent application publication number 0062343 A2 discloses a latex of a copolymer obtained from a hard monomer such as styrene, a soft monomer such as butadiene and an unsaturated acid which may be blended with a tackifying resin to produce a formulation useful as a pressure sensitive adhesive.
Various resinous materials have been suggested as tackifier for these latices. Examples of materials suggested include emulsified rosin, partially decarboxylated rosin, glyceryl esters of polymerised rosin, partially dimerised rosin, natural resins, hydrogenated wood rosin, plasticised hydrogenated rosin, aliphatic hydrocarbon resins from petroleum, aromatic petroleum resins, EVA, terpene/phenol resins, cumarone/indene resins, rosin esters, pentaerythritol esters and polydicylopentadiene resins.
In developing adhesive formulations one seeks the optimum combination of several adhesive properties and since it is not generally possible to achieve the optimum for every property it is necessary to obtain the best balance of properties for the particular use in mind. For pressure sensitive adhesives for use in the label industry one tries to optimise the loop tack and ball tack and at the same time provide an adhesive whose component will not migrate during storage leading to unsightly coloring and lowering of adhesive properties. Although the improved loop tack and ball tack can be provided by the tackifier resins of the type described above we have found that those tackifier which provide such tack for example hydrogenated rosins such as Staybelite ester 10 and modified rosins such as Snowtack 52CF tend to migrate.
It has been generally suggested in United Kingdom patent application 2097410A and European Patent application 0062343 that petroleum hydrocarbon resins such as those manufactured from a C.sub.9 cut of an aromatic hydrocarbon stream or a C.sub.5 cut of an aliphatic or cycloaliphatic hydrocarbon stream are useful as tackifiers. There is however no suggestion of the particular type of resin that should be used and indeed many of the resins falling within such broad descriptions are unsuitable for tackification of lattices.
Our European Patent Application 85302057.6 describes lattices of resins having a softening point from 10.degree. C. to 80.degree. C. which are copolymers of a feed which is predominantly C.sub.5 olefines and diolefines and one or more monovinyl aromatic compounds which contain from 10 to 30 wt. % of the monovinyl aromatic compound and their use as tackifiers for carboxylated styrene butadiene copolymer rubbers. We have now found that this type of copolymer is useful to tackify the polyacrylate emulsions frequently used in aqueous based adhesives.

Tackifiers and their use in pressure sensitive adhesives