A resin-based VOC-free soldering flux consists of 40 to 50 wt % of a liquid epoxy resin, 25 to 30 wt % of a non-volatile liquid epoxy diluent, 20 to 33 wt % of a polyfunctional carboxylic acid, and 2.0 to 3.5 wt % of a thixotropic agent. There are no volatile organic solvents or compounds in the flux which can evaporate during the reflow process. The carboxylic acids are provided in powdered form and are suspended in the epoxy blend wherein they remain as solid particles until heated in the solder reflow process. A VOC-free solder paste formed from the flux consists of 40 to 95 wt % soldering particles, and 5 to 60 wt % of the VOC-free soldering flux. The thixotropic agent improves printability of the solder paste onto printed wiring boards. A VOC-free flux-core solder wire includes the VOC-free flux as the inner core of the wire with an outer shell of solder alloy. The VOC-free, epoxy resin based flux effectively activates the solder powder and the copper contact during the reflow process, while at the same time hardens to leave a solid, dry, yet flexible residue on a printed wiring board. No organic compounds are emitted during the reflow process.

The instant invention relates to soldering fluxes and solder pastes, and more particularly to an epoxy-based soldering flux which does not contain any volatile organic compounds or solvents (VOC's).
Soldering fluxes and solder pastes have heretofore been known in the art. In this regard, solder pastes are used to connect the leads of electronic elements to contact pads on a printed wiring board (PWB). In use, solder pastes are printed onto the copper contact pads of the PWB, the leads of the electronic element are placed in proper position on top of the PWB contact pads, and then the entire PWB assembly is heated to achieve reflow of the solder paste to form a connection between the leads of the electronic element and the contact pads of the PWB.
Solder paste, in general, comprises a homogenized mixture of solder powder and a soldering flux which, when mixed with the solder powder, gives the mixture the physical characteristics of a paste. The soldering flux is typically a solution of a resin, usually a rosin or rosin derivative, and an organic acid activator dissolved in a volatile organic solvent. The organic solvent typically comprises up to 80 wt % (percent by weight) of the flux composition. The organic acid activator in the soldering flux actively removes an oxide film from the metallic components when applied to the metal surfaces thereof, thus allowing the melted solder to flow freely over and bind to all fluxed surfaces. Thixotropic agents and other viscosity modifiers can also be present to achieve the desired rheological characteristics of the soldering flux and/or solder paste.
During the reflow, i.e. heating, process, most of the organic solvent evaporates into the air leaving a solid residue on the PWB. Furthermore, besides the evaporation of the organic solvents, a significant amount additional of organic material becomes airborne as fume through decomposition or sublimation of the solid residue. While the prior art solder pastes and fluxes have been highly effective for their intended purposes, the evaporation of the organic solvent and release of organic materials during solder reflow pose many problems which have recently become a significant concern in the industry. Firstly, volatile organic compounds (VOC's) and VOC emissions are now receiving stricter scrutiny from an environmental perspective. More stringent environmental regulations are requiring the reduction of organic emissions in all industrial applications. Secondly, VOC emissions are a burden to the reflow equipment in that the VOC's recondense onto the cold parts of the equipment, corroding metal, causing electrical failure, and clogging ventilation ducts. Another disadvantage to organic solvent based solder pastes is that in the case of rosin type pastes, the solid residue is brittle, and prone to cracking. Many manufacturers of printed wiring boards are now producing flexible circuit structures, i.e. flexi-circuits, and the brittleness and cracking of solvent based solder pastes is unacceptable in these types of applications. The use of plasticizers to remedy the brittleness of rosin-type organic solvent solder pastes makes the organic residue sticky, and unsuitable for pin-testing of the PWB after reflow.
The instant invention provides an epoxy-based, VOC-free soldering flux comprising 40 to 50 wt % (percent by weight) of epoxy resin, 25 to 30 wt % of non-volatile liquid epoxy diluent, 20 to 33 wt % of an activating agent which is insoluble, i.e. unreactive, in the epoxy system at room temperature, and 2.0 to 3.5 wt % of a thixotropic agent. In the instant soldering flux, the activating agent also serves as a curing agent for the epoxy resin system. There are no organic solvents in the soldering flux which can evaporate during the reflow process. The epoxy diluent can be either a reactive diluent containing one or more epoxy functional groups, such as polyglycol diepoxide, or a non-reactive diluent, such as a polyether diol. More specifically, the soldering flux preferably comprises 40 to 50 wt % of bisphenol A type epoxy resin, 25 to 35 wt % polyglycol diepoxide (epoxy diluent), 20 to 35 wt % of a polyfunctional carboxylic acid (activating agent and curing agent), such as malic acid, and 2.0 to 3.5 wt % of hydrogenated castor oil (thixotropic agent).
The instant invention further provides a VOC-free solder paste formed from the above-described flux consisting of 40 to 95 wt % soldering particles, and 5 to 60 wt % of the above-described VOC-free soldering flux. The soldering particles preferably comprise 63Sn/37Pb alloy solder particles having mesh size of about 325 to 500. The thixotropic agent added to the flux composition improves printability of the solder paste onto printed wiring boards. The activating agent of the flux effectively activates the solder powder and the copper contact during the reflow process, while at the same time cures the epoxy so that it hardens to leave a solid, dry, yet flexible residue on a printed wiring board. The activating/curing agent is selected so that its melts just prior to the reflow process so that activation, curing of the resin, and reflow of the solder particles occur almost simultaneously.
The instant invention still further provides a flux-core solder wire formed from the above-described VOC-free soldering flux. The flux-core solder wire is formed according to conventional solder wire forming techniques resulting in a wire structure having an inner core of the instant VOC-free soldering flux, and an outer shell of a solder alloy.
Accordingly, among the objects of the instant invention are the provision of an epoxy-based VOC-free soldering flux which hardens after the reflow process to form a solid, dry, flexible residue on the printed wiring board; the provision of a VOC-free solder paste; and the provision of a VOC-free flux-core solder wire.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds herein.


The invention relates to a novel Universal RT-coupled PCR strategy for the specific detection and accurate quantitation of mRNA. Claimed and disclosed are novel Universal reverse transcription (RT) primers, a specific primer mix containing the Universal RT-primers, a transcript specific forward primer and a reverse PCR primer identical to a unique tag sequence, and methods and kits thereof for avoiding the amplification of genomic DNA and/or pseudogenes.

The specific amplification of mRNA for the quantitation of gene expression is central to the understanding of a wide range of biological processes, including gene regulation, development, differentiation, senescence, oncogenesis, pathogenesis of disease and many other medically important processes.
The sensitivity of RT-PCR has made it an essential tool of molecular biology for the detection of gene expression. Moreover, with the advent of real-time quantitative PCR technology, transcripts can now be quantitated with precision (Bustin et al., 2000). However, it has been shown that processed pseudogene sequences present in genomic DNA contamination of "RNA" extracts can confound even the most well-designed, standard PCR primers. These genomic DNA sequences are prevalent for highly-expressed "housekeeper" genes, such as β-actin, GAPDH and 36B4. Even small amounts of contaminating genomic DNA can cause false positives by the inadvertent amplification of genomic DNA or pseudogenes (Lion et al., Leukemia 15, 1033–1037, 2001).
Co-amplification of processed pseudogenes in RT-PCR is underreported in the scientific literature. Of the articles that acknowledge the problem, some focus on designing primers to take advantage of the limited sequence differences in the pseudogene sequence versus the mRNA sequence (Lion, Leukemia 15, 1033–1037, 2001; Raff et al. BioTechniques 23:456–460.1997; Kreuzer et al. Clinical Chemistry 45(2), 1999; Shibutani et al. Laboratory Investigation Vol. 80, No 2, p. 199, 2000 and Krauter et al. British Journal of Haematology 107,80–85, 1999). Others rely on DNase treatment to eliminate the genomic DNA signal (Lion, Leukemia 15, 1033–1037, 2001; Ambion Tech Notes Newsletter. Volume 8, Number 1, 2001; Huang et al. BioTechniques Vol. 20, No 6,1012–20, 1996; Bauer et al. BioTechniques 22:1128–32, 1997 and Ivarsson et al. BioTechniques 25:630–36, 1998), while others contend that the amplification of processed pseudogenes is insignificant to the overall signal (Overbergh et al. Cytokine, Vol. 11(4): 305–312, 1999 and Hartel et al. Scandinavian Journal of Immunology 49,649–654,1999).
Traditionally, there have been a number of strategies developed for the isolation of RNA in an attempt to reduce DNA contamination, such as the addition of a DNase digestion step (Raff et al. BioTechniques 23:456–460, 1997; Kreuzer et al. Clinical Chemistry 45(2), 1999; Getting Rid of Contaminating DNA. Ambion Tech Notes Newsletter. Volume 8, Number 1 2001; Huang et al. BioTechniques Vol. 20, No 6,1012–20, 1996; Bauer et al. BioTechniques 22:1128–32, 1997 and Ivarsson et al. BioTechniques 25:630–36, 1998), or passing the total RNA extracted from tissue samples through a PolyA column. Unfortunately, these strategies are unsuitable for optimal gene expression sensitivity, particularly for small samples or low-copy transcripts. Moreover, there are important considerations when using DNase to eliminate DNA contamination (Raff et al. BioTechniques 23:456–460, 1997; Ambion Tech Notes Newsletter, Volume 8, Number 1, 2001; and Lacave et al. British Journal of Cancer 77(5) 694–702, 1998). (1) Inactivation of the DNase must be complete because both reverse transcriptase and Taq polymerase can be degraded by active DNase; (2) failure to completely inactivate DNase can result in diminished or no product formation; and (3) DNase digestion protocols can result in significant RNA loss which is particularly important when attempting to amplify low levels of transcripts or isolating RNA from very small samples (Raff et al. BioTechniques 23:456–460.1997; Kreuzer et al. Clinical Chemistry 45(2). 1999; and Huang et al. BioTechniques Vol. 20, No 6,1012–20, 1996, see FIG. 1).
An alternative to adding further steps to the RNA purification is to design PCR primers that are so-called "mRNA specific". In native genes, individual exons are separated by an intron, and therefore the exon/exon primer-specific sequence does not exist in the coding gene with introns. Two typical strategies for primer design are: 1) To design the primers to span an intron such that the genomic DNA product is larger than the mRNA-derived product, and therefore easily size-distinguishable by visualization on a gel or 2) design an individual primer of a primer pair to span an exon/exon border in the mRNA. These approaches, however, are insufficient to ensure consistent mRNA-specific amplification. Raff et al. (Biotechniques 23:456–460, 1997) developed a quantitative β-actin RT-PCR that does not co-amplify processed β-actin pseudogenes, but maximum primer efficiency requires very specific annealing conditions. Two new sets of primers were designed around small pseudogene-RNA differences that allowed for specific amplification of human and rat β-actin reverse transcribed mRNA but not pseudogene sequences in small tissue samples from biopsies. The forward primer corresponds to the 18- and 20-nucleotide sequences in the 5′ untranslated region of exon 1 of human and rat β-actin gene respectively and the reverse primer corresponds to the 23-nt sequence from exon 4 of the human β-actin gene. Kreuzer et al. (Clinical Chemistry, 45:297–300, 1999) also developed a quantitative Taq Man™ PCR specific for human β-actin that relied on a few pseudogene mismatches with the 3′ end of the sense (reverse) primer to reportedly avoid amplification of contaminating genomic DNA-encoding pseudogene. However, data demonstrating RNA-specific RT-PCR was not shown in that article.
There have been further efforts to design a so-called RNA-specific RT-PCR (Joo et al. J. Virol. Meth. 100:71–81, 2002; Smith et al. Biotechniques 31:776–782, 2001; Sybesma et al. BioTechniques 31:466–472, 2001; Folz et al. Biotechniques 29:762–768, 2000; Shuldiner et al Gene 91: 139–142, 1990 and Shuldiner et al BioTechniques 11(6): 760–763, 1991). Joo et al. describe a tagged RT-PCR strategy for specifically amplifying viral CMV RNA, which takes advantage of temperature differences between RT and PCR. Limitations include 1) The RT approach is not universal, in that a new RT primer must be designed for each transcript to be amplified, and 2) the corollary is that there is inefficient use of precious total RNA sample required for each separate RT. 3) The RT primer sequence in this system is not specific for poly-A signal, and therefore RNA specificity depends entirely on access to a single strand viral RNA loop at standard RT temperatures. 4) The requirement for rigid reaction parameters, specific to each transcript, is highlighted by the demonstrated need for precise [Mg++] optimization for the system to be RNA- and transcript-specific, in the description and performance data. 5) RT efficiency and PCR efficiency will vary transcript to transcript, given the dual-role-of-primer strategy. 6) The system is not tested for non-viral eukaryotic or mammalian systems.
Smith et al. describe the employment of a tagged, anchored RT-RACE primer used from a commercial source (Clontech), combined with the use of that tag in PCR in a three-step step-in, step-out strategy. Limitations include: 1) The process is very complex. 2) The insertion of the larger generic reverse primer is a separate 35-cycle PCR step. 3) Two steps of a nested PCR strategy for GAPDH is required, which is time and labor expensive. 4) Potential for RT-RACE primer slippage is possible for transcripts, given that poly-T tail can anneal anywhere on the poly-A tail of mRNA with only one mismatch; this would yield multiple size bands for PCR product. 5) Multiple products in the GAPDH and HERV-K demonstration gene products preclude realtime quantitation. 6) Poly-A tails shorter than 30-mer on mRNA transcripts may not anneal the RACE primer, because of the length of the combined overhanging poly-T and 25-mer tag sequence. 7) Sensitivity has not been quantitated.
Folz et al. describe the design of a primer for one single gene that has both RT and PCR functions, depending on temperature parameters programmed into the respective RT and PCR protocols. Limitations include 1) The RT approach is not universal, in that a new RT primer must be designed for each transcript to be amplified, and 2) the corollary is that there is inefficient use of precious total RNA sample required for each separate RT. 3) The design parameters of the system are highly restrictive, preventing design of dual function RT-PCR antisense primers suitable for other transcripts; the poly-T tail demands a high GC transcript-specific design for nucleotide balance and the prevention of self-annealing. This would make the few possible primers inefficient, or completely unsuitable, for many transcripts and cDNAs. 4) The gene-specific 3′ end of the dual-function primer may readily anneal to gDNA pseudogene on PCR cycling, as could the poly-T tail, as many processed pseudogenes contain poly-A tails. 5) The system was reported for only one transcript; no data is available on others.
Sybesma et al. describe a RT-PCR employing tag-extended RT primers using temperature-gradient PCR, and Shuldiner et al. (1990 and 1991) describe an RNA template-specific PCR (RS-PCR) to reduce false positives. However the RT-PCR used by these groups have a number of limitations as follows: 1) The RT primers used are transcript-specific, not Universal for all transcripts; therefore new primers have to be designed for each transcript; 2) The PCR extension times need to be changed for each reaction according to the transcript being amplified; 3) The RNA template is consumed quickly as new RNA and reverse transcription is required for every new transcript; and, 4) The procedure requires multiple cumbersome steps.
Lastly, another approach to isolate RNA is to ignore the pseudogene contribution to the overall signal based on the assumption that the number of mRNA copies for an expressed gene greatly exceeds that of the pseudogene and therefore makes its contribution insignificant (Lacave et al. British Journal of Cancer 77(5) 694–702, 1998; Shibutani et al. Laboratory Investigation Vol. 80, No 2, pg. 199, 2000; Krauter et al. British Journal of Haematology 107, 80–85, 1999; Overbergh et al. Cytokine, Vol. 11(4): 305–312, 1999 and Hartel et al. Scandinavian Journal of Immunology 49,649–654, 1999). There are a number of potential problems with this approach. First, the mRNA: genomic DNA ratio may be low, simply as a result of low-copy transcription, characteristic of many native and nonetheless physiologically important transcripts. Second, RNA is more readily degraded than DNA, in part because RNase is ubiquitous. Even if the mRNA to genomic DNA pseudogene ratio is initially very high in the cell, the RNA can be degraded very rapidly from the point of tissue collection up to the end of cDNA synthesis. Consequently the cDNA:genomic DNA ratio after cDNA synthesis may be artificially low compared to original mRNA levels. Finally, the target gene of interest may not be expressed in all cell types. Tissue samples used for RNA isolation may contain many different cell types and the transcript of interest may only be expressed in a small number of these cells, for example epithelial cells. Genomic DNA (and therefore pseudogenes) is present in all cells of a sample, both mesenchymal and epithelial. Therefore, the contribution of PCR product derived from the contaminating genomic DNA pseudogene in the "RNA" sample may be very significant in tissue samples containing several cell types.
An approach that has been routinely used for the determination of mRNA levels is measuring all target transcripts against a constitutively expressed internal reference gene known as a "housekeeping gene", where mRNA expression of the transcript is constant. As previously noted, however, many of the highly expressed housekeeper genes including β-actin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) have additional related sequences nearby or remotely in the genome called "processed pseudogenes" (Raff et al. BioTechniques 23:456–460, 1997; Kreuzer et al. Clinical Chemistry 45(2), 1999; Mighell et al. FEBS Letters 468:109–114, 2000; NG et al. Molecular and Cellular Biology 5(10): 2720–32, 1985 and Taylor et al. Br J Haematolog 86: 444–5, 1994). Pseudogenes typically lack promoters or introns, making cDNA primer design that distinguishes cDNA from genomic-derived DNA sequences extraordinarily challenging, and somewhat impractical for high throughput applications (Raff et al. BioTechniques 23:456–460, 1997 and Kreuzer et al. Clinical Chemistry 45(2), 1999). This is particularly true for RNA samples derived from tissues where there is a substantial number of "non-target gene-expressing cells" (e.g. lung fibroblast/mesenchymal cells), mixed in with cells or tissue expressing the gene of interest (e.g. lung epithelial cells). Designing new PCR primers is possible but it remains very difficult to design reliable, cDNA-specific PCR primers or other cDNA-specific amplification strategies in the presence of a pseudogene (Raff et al. BioTechniques 23:456–460, 1997; Kreuzer et al. Clinical Chemistry 45(2), 1999 and Taylor et al. Br J Haematolog 86: 444–5, 1994). Finally, finding non-pseudogene-encoded housekeeper genes is another approach to the pseudogene-for-reference genes problem. Although housekeeping genes such as 28S ribosomal RNA can be good candidates, they are overwhelmingly plentiful, and therefore inadequate for providing a true reflection of RNA degradation, particularly as it affects low-copy number transcripts.
In conclusion, none of above strategies to-date have been successful as a true assay of gene expression without compromising the total RNA yield, specific, efficient and facile amplification of an RNA transcript, or accurate quantitation of the original mRNA transcript.
Therefore it is clear that there exists a need in the art for improved methods of selectively amplifying nucleic acids, especially mRNA, whereby the methods can achieve a high degree of amplification from a limited amount of mRNA and which simultaneously avoids genomic amplification often introduced by other amplification methods. The present invention is believed to satisfy this need and to provide other related advantages.
The present invention provides an improved strategy for the specific amplification of mRNA in total RNA extracts, regardless of sample contamination with genomic DNA. Moreover, the present strategy makes a quantitative evaluation of gene expression RNA-specific while preserving the sensitivity of standard RT-PCR techniques.
Citation of a reference herein shall not be construed as an admission that such reference is prior art to the present invention. In addition, each document or reference cited in this application, are hereby expressly incorporated herein by reference as well as each document or reference cited in each of the herein-cited documents or references, are hereby expressly incorporated herein by reference.

Universal RT-coupled PCR method for the specific amplification of mRNA


A computer system includes a computing device such as a microcontroller and a memory device. The memory device is illustratively a serial device connected to the serial port of the microcontroller. The memory device includes a page latch load circuit which provides serial I/O to the microcontroller and transfers I/O bits in a predetermined order to/from the page latches. Page latches are connected over many bit lines to a memory cell array. The page latches not only supports programming and reading of sectors in the memory cell array, but also provides one or more of the following functions: directly accessible to the microcontroller as an SRAM scratch pad, directly loadable from the memory cell array to facilitate single byte "read-modify-write" operations, and loadable during programming operations to support real time applications.

1. Field of the Invention
The present invention related to non-volatile programmable memory, and more particularly to non-volatile programmable memory having a buffering capability.
2. Description of Related Art
Byte programming for EEPROM (Electrically Erasable-Programmable Read-Only Memory) devices is longer than byte programming for EPROM (Erasable-Programmable Read-Only Memory) or Flash EPROM. In particular, byte programming requires about 5 ms for EEPROM as opposed to about 10 .mu.s for EPROM or Flash EPROM. The reason is that EEPROM devices typically use Fowler-Nordheim Tunneling mechanism to inject electrons or retrieve electrons to or from the floating gate, while EPROM or Flash EPROM devices typically use the CHE (channel hot electron) mechanism to inject electrons in the floating gate. The CHE mechanism is quite inefficient and typically requires anywhere from 100 .mu.A to 1 mA of programming current for each cell. This is why only one byte at a time is usually programmed in EPROM's or FLASH EPROM's devices. On the other hand, the FN (Fowler-Nordheim) tunneling mechanism barely consumes any current, being typically in the nanoamphere range. Because of this, many cells, illustratively a few thousand, can be programmed at the same time in parallel.
Because large number of cells can be programmed in parallel, page latches have been widely used in EEPROM devices to speed up their programming time. An early EEPROM device containing page latches is the type 28C64, which is a 64K EEPROM available from various manufacturers including Catalyst and Xicor. Each page latch is connected to a bitline; typically for a given EEPROM device, there are as many page latches as there are bitlines. For example, a 64K EEPROM (type 28C64) has 32 bytes of page latches, a 256K EEPROM (type 28C256) has 64 bytes of page latches, and a 1Mb EEPROM (type 28C010) has 128 bytes of page latches. A serial 8 Mbit Flash EEPROM type 26F080 available from Nexcom Technology, Inc. of Sunnyvale, Calif. has 536 bytes of page latches.
Page latches typically operate in the following way. The user provides to the memory the column address as well as the data byte followed by WE and CE to load the page latches. After all the page latches are loaded, the memory device goes into a self-timed programming cycle at the end of which the data in the page latches is transferred to the selected row decoded by the X-Address decoder. The device programming is sped up by a considerable factor. For example, if all 32 bytes are loaded in the page latches, the programming time per byte is cut from an average of 5 ms to 5 ms/32 or 156 .mu.s. For an 8 Mbit device having 2048 sectors of 536 bytes each, the average programming time is 5 ms/536 bytes or about 9 .mu.s.
A page latch has some features in common with an SRAM cell. For example, both page latches and SRAM cells typically includes two inverters connected back-to-back. However, page latches and SRAM cells have many differences as well. For example, SRAM cells are differential devices, while page latches are single ended. As a differential device, an SRAM cell is able to interact with high capacitance differential bit lines without affecting the value stored therein. However, as a single ended device, a page latch is not able to interact with a high capacitance line without potentially changing the value stored therein. While a page latch can be used as temporary storage before transferring data to a selected row of memory, a page latch is not usable as a data buffer.
One-transistor Flash EEPROM devices containing page latches have a further weakness, relative to regular EEPROM devices. Regular EEPROM devices, which contain two transistor memory cells, use a byte-select transistor for every byte, so that every byte is uniquely accessible. Eight page latches are associated with every byte, and an additional page latch is associated with the byte select. If only one byte needs to be modified, the modification can be easily achieved because only that byte will go through the Erase & Write cycle. However, Flash EEPROM devices using one-transistor memory cells have no byte-select transistors. If only one byte needs to be modified, the entire sector is erased (high threshold voltage V) and is subsequently entirely written. Typically, if a "Read-Modify-Write" operation is desired, the entire sector is read and stored in external RAM, the selected byte is modified, and the entire sector is loaded back into the page latches before the self timed Erase-Write Operation is initiated. Unfortunately, this process is time-consuming.
Memory devices containing page latches have a further weakness, which is problematical in some real time applications requiring continuous writes to memory. During programming of a sector in which data is transferred from the page latches to the selected sector, the page latches cannot be accessed until the sector programming is complete. Typically, a self-timed programming cycle takes about 5 ms. In a real time application generating sectors of data more frequently than once ever 5 ms, an external memory device must be used to temporarily store the stream of real time data until programming of the present sector is complete.

Non-volatile programmable memory having a buffering capability and method of operation thereof


A radio-frequency receiver circuitry includes a down-converter circuitry, an analog-to-digital converter circuitry, and a DC offset reduction circuitry. The down-converter circuitry accepts a received radio-frequency signal and processes the radio-frequency signal to provide an in-phase down-converted signal and a quadrature down-converted signal to the analog-to-digital converter circuitry. The analog-to-digital converter circuitry converts the in-phase and quadrature down-converted signals to an in-phase digital output signal and a quadrature digital output signal, respectively. The DC offset reduction circuitry couples to the analog-to-digital converter circuitry, and tends to reduce a DC offset transmitted to the in-phase and quadrature digital output signals.

The proliferation and popularity of mobile radio and telephony applications has led to market demand for communication systems with low cost, low power, and small form-factor radio-frequency (RF) transceivers. As a result, recent research has focused on providing monolithic transceivers using low-cost complementary metal-oxide semiconductor (CMOS) technology. One aspect of research efforts has focused on providing an RF transceiver within a single integrated circuit (IC). The integration of transceiver circuits is not a trivial problem, as it must take into account the requirements of the transceiver's circuitry and the communication standards governing the transceiver's operation. From the perspective of the transceiver's circuitry, RF transceivers typically include sensitive components susceptible to noise and interference with one another and with external sources. Integrating the transceiver's circuitry into one integrated circuit may exacerbate interference among the various blocks of the transceiver's circuitry. Moreover, communication standards governing RF transceiver operation outline a set of requirements for noise, inter-modulation, blocking performance, output power, and spectral emission of the transceiver.
Unfortunately, no technique for addressing all of the above issues in high-performance RF receivers or transceivers, for example, RF transceivers used in cellular and telephony applications, has been developed. A need therefore exists for techniques of partitioning and integrating RF receivers or transceivers that would provide low-cost, low form-factor RF transceivers for high-performance applications, for example, in cellular handsets.
A further aspect of RF receivers and transceivers relates to providing high-performance signal processing functions in an integrated form. RF receivers and transceivers typically employ analog front-end circuitry. Analog circuitry, by its nature, is more susceptible to non-ideal circuit behavior, such as component mismatches, parasitic effects, second-order effects, and the like. As a result, front-end analog circuitry produces DC offsets that impact the processing of the desired signal. A further need therefore exists for RF receivers and transceivers that reduce the DC offset or compensate for it.

DC offset reduction in radio-frequency apparatus and associated methods


A method for reducing memory latency in a multi-node architecture. In one embodiment, a speculative read request is issued to a home node before results of a cache coherence protocol are determined. The home node initiates a read to memory to complete the speculative read request. Results of a cache coherence protocol may be determined by a coherence agent to resolve cache coherency after the speculative read request is issued.

Computer systems may contain multiple processors that may work together to perform a task. For example, a computer system may contain four processors that may share system resources (e.g., input devices or memory devices) and may perform parallel processing. The processors may send messages to each other, may send messages to system resources, and may send and receive messages from the system resources. For example, such messages may include requests for information that is stored at a location in a memory device or a request to store information in a location of a memory device.
In a cache coherent shared memory multiprocessor, the set of data currently being used by a microprocessor may be copied from a system memory device such as a dynamic random access memory (DRAM) into a relatively smaller but faster cache memory device such as a static random access memory (SRAM). In such systems, a cache is said to be "coherent" if the information resident in the cache accurately reflects the information in DRAM memory. Lack of cache coherency can occur when a requester for a memory location does not receive the latest copy of the data. For example, if the cache is updated while main memory is not and a new requester for this location receives the data from main memory into the requester's cache, the cache is said to be non-coherent.
Cache "snooping" is a technique used to detect an access to memory that might cause a cache coherency problem. For example, in the case where the cache is updated while the memory is not, the memory request from the new requesting agent is snooped in the cache containing updated data, which then supplies the data to the requester instead of memory. In a multi-processor system, the messages sent between processors may include cache snooping messages generated in accordance with a coherence protocol. A coherence protocol (e.g., MESI protocol) is implemented to prevent cache coherency problems.
Typically, in order for the requester to receive updated data, the result of the cache coherence protocol is first determined before the memory access is started. In a large scale multi-node distributed memory multi-processor, the resolution of the cache coherence protocol may take a long time, resulting in increased memory latency for accessing data from memory.

Method and apparatus for reducing memory latency in a cache coherent multi-node architecture


The trap apparatus of the present invention includes a case provided for a gas exhaust system used for a film forming equipment which carries out a film forming process on an object, a gas supply port, made in the case and connected to an exhaust pipe of the gas exhaust system, for introducing an exhaust gas flowing through the exhaust pipe, into the case, a gas exhaust port, made in the case and connected to an exhaust pipe of the gas exhaust system, for exhausting the exhaust gas flowing through an inner space of the case, to the exhaust pipe, a plurality of partition plates arranged in the case so as to partition the inner space of the case into a plurality of rooms between the gas supply port and the gas exhaust port, a gas distribution port provided in some of the partition plates such that the exhaust gas introduced into the case through the gas supply port, is allowed to flow through the rooms partitioned by the partition plates, in the order, and then exhausted from the gas exhaust port, and a trap mechanism housed in each of the rooms, for trapping reaction byproducts contained in the exhaust gas introduced into the case through the gas supply port.

The present invention relates to a trap apparatus for trapping reaction byproducts contained in an exhaust gas from a film forming equipment for carrying out a predetermined film forming process on an object, so as to eliminate them.
Generally, in the productions of integrated circuits such as ICs or logic elements, the film forming process for forming a predetermined thin film on an object such as a semiconductor wafer, a glass substrate or LCD substrate, and the etching process for etching a formed thin film into a desired pattern, are repeatedly carried out.
For example, in the film forming process, as a predetermined process gas is introduced into a reaction container, and the process gas reacts, a thin film of silicon, a thin film of a silicon oxide or a silicon nitride, a thin film of a metal, or a thin film of a metal oxide or a metal nitride, or the like is formed on a surface of an object. At the same time with the reaction of forming such a film, undesired reaction byproducts are created, which are discarded together with an exhaust gas.
The reaction byproducts, if directly released to the atmosphere, cause an environmental pollution or the like. Therefore, as a general case, a trap apparatus is provided for the gas exhaust system extending from the processing container, so as to eliminate the reaction byproducts contained in the exhaust gas by trapping them with the trap apparatus.
There are various types of trap apparatuses having different structures, proposed depending upon the characteristics of reaction byproducts to be trapped and eliminated. For example, the trap apparatus used for eliminating reaction products which are liquefied or solidified as a condensate at room temperature, is formed to have a structure consisting of a case having a supply port and an exhaust port, for exhaust gas, and a number of fins provided in the case. It should be noted that these fins are arranged in order each at a different angle with respect to the direction of flow of the exhaust gas, so as to create an exhaust conductance. With this structure, when the exhaust gas passes through the fins, the reaction byproducts contained in the exhaust gas are trapped as they are adhered to the surfaces of the fins.
Trap apparatuses of the conventional type as described above, usually have a single space structure. Due to such a structure, the time period in which the exhaust gas is brought into contact with the fins, is very short. Particularly, when a great amount of process gas is allowed to flow in order to increase the rate of the film formation, reaction byproducts which cannot be trapped by the trap apparatus, in some cases, escape to the down-stream side of the trap apparatus.
Further, in the conventional trap apparatuses, since the fins of a great number, are arranged at the same pitch, the fins are often blinded by the reaction byproducts adhered thereto. Therefore, reaction byproducts which cannot be trapped by the trap apparatus are made to flow to the down-stream of the flow.
As one solution to the above-described problem, it can be proposed to increase the capacity of the trap apparatus. However, if the capacity is simply increased, it is not possible to enhance the trapping efficiency for the increased capacity, but the space occupied by the apparatus is enlarged for nothing.


A membrane electrode assembly for a fuel cell having a polymer electrolyte membrane, having a layer sequence comprising an ion-conducting membrane (2), a catalyst layer (3) and a gas diffusion layer (5). A substantially catalyst-free, porous condensation layer (5) is arranged between the catalyst layer (3) and the membrane (2).

The present invention relates to a membrane electrode assembly for a fuel cell.
It is known that the water budget is a critical factor in fuel cells with a polymer electrolyte membrane. A proton-conducting membrane and a catalyst layer on both sides are provided in the interior of the fuel cell. The catalyst layer, which is required for the electrochemical reaction, has a porous structure comprising agglomerates with characteristic pore radii of a few nanometres to a few hundred nanometres. A porous gas diffusion layer, generally comprising a plurality of individual layers with pores of significantly larger radii, through which starting materials, usually hydrogen and oxygen, are transported from an anode duct and a cathode duct and products (water) are discharged to the duct, is usually arranged on the catalyst layers on both sides of the membrane. Gas mixtures comprising a certain level of water vapor are usually present in the cathode duct. Further water vapor is fed to the duct from the catalyst layer through diffusion. Consequently, it can be assumed that the level of water vapor in the catalyst layer is significantly higher than in the porous gas diffusion layer and in the duct.
If the level of water vapor in the duct is very low, despite the increase in the level of water vapor towards the catalyst, there will be insufficient water vapor there to protect the adjoining membrane and the catalyst layer itself from drying out. If the level of water vapor in the duct is low, water is extracted initially from the catalyst layer and ultimately from the membrane through diffusion across the porous gas diffusion layer, which can cause damage to the membrane.
On the other hand, if the level of water vapor in the duct is very high, it will increase towards the catalyst layer to such an extent that the condensation point is reached and liquid water will be formed in the pores in the catalyst layer. The flooding with liquid water which then results is a crucial factor in preventing the supply of starting materials to the catalyst layer and also significantly inhibits the fuel cell reaction on account of the difficulties involved in discharging liquid water. Although there is then no risk of the membrane drying out, the efficiency and operational reliability of the fuel cell are greatly reduced.
German Patent Application No. DE 100 52 189 A1 discloses providing a buffer layer in a gas diffusion electrode for the purpose of controlling the gas and water management. In this case, a hydrophobic buffer layer is arranged between a carbon paper and a catalyst layer, the intention being to improve distribution of gas and water.

Membrane electrode assembly for a fuel cell


A method for providing parallel processing capabilities including: performing scalar and array privatization analysis via a compiler; checking whether an assignment statement is reducible; recognizing reduction patterns through a pattern matching algorithm; classifying a reduction type of each of the reduction patterns; and performing transformations and code generation for each reduction the reduction type of each of the reduction patterns.

1. Field of the Invention
This invention relates to reductions of array variables, and particularly to a method for solving a general reduction problem, which is generalized as a divide-and-conquer problem for solving a problem on an instance of size n, by dividing the instance into two or more smaller instances.
2. Description of Background
Most compilers are capable of recognizing simple reductions such as the accumulation into the variable "SUM" 10 in FIG. 1. Reductions of array variables are also common in scientific codes and are a potential source of significant improvements in parallelization results. In general, a reduction can be expressed in the form of R={r,f,d}, where r can be a scalar variable, an array, or a compound expression. The symbol,  represents an associative reduction operator, ƒ is a function of reduction execution, and d is a domain for reduction operation. Taking the code segment 10 in FIG. 1 as an example, r is a scalar variable, i.e., SUM. is +, ƒ is an identity function, and d is the data area pointed by A ranging from A[1,1] to A[N,M].
Handling such kind of scalar reduction in FIG. 1 is straightforward. There are a number of solutions implemented or proposed. For example, a conventional method is to use a critical section to enable parallel execution of the loop. Another approach is to compute a partial reduction result of each processor and then merge the results to get the overall result. However, for a reduction that involves complicated structures, such as a conditional branch, the identification and implementation is difficult.
For instance, an example code segment 12 in FIG. 2 is considered, which is used to calculate a global maximum and indexes associated with the maximum value. The loop in FIG. 2 cannot be parallelized due to the loop carried dependences on Max_value, Max_index_i and Max_index_j. Another example of a code segment 14 is shown in FIG. 3, which is used to detect the number of array elements whose value is equal to that of variable val. Code segment 12 in FIG. 2 and code segment 14 in FIG. 3 illustrate the difficulty in identifying and implementing a general reduction.
Considering the limitations of the aforementioned methods, it is clear that there is a need for an efficient method for solving a general reduction problem, which is generalized as a divide-and-conquer problem for solving a problem on an instance of size n, by dividing the instance into two or more smaller instances.

Framework for parallelizing general reduction

International Business Machines Corporation


An actuator (144) for initiating a trip of a circuit breaker. Load current passes through a conductor (66) that is electrically coupled to a contact arm (56) by a braid (62). A thermally responsive bi-metal (64) has a first end portion which is disposed against a portion of the conductor (66) and through which at least a portion of load current carried by the contact arm, the braid, and the conductor passes. The bi-metal further has a second end portion that is disposed in spaced relation to the conductor and is cantilever-mounted on the portion of the conductor via the bi-metal's first end portion. The bi-metal is nominally flat and straight, but increasingly warps as thermal energy in the bi-metal increases. Upon attaining a certain degree of warping, the bi-metal initiates a trip of the circuit breaker by causing the contact arm to swing from a circuit-making to a circuit-breaking condition.

One design criterion for a circuit breaker holds that upon occurrence of a load fault which creates an unacceptably large current draw (e.g., a short circuit current) through closed contacts of a circuit breaker, the circuit breaker mechanism must open the contacts in a manner that promptly terminates the current. Certain known circuit breakers that employ one or more pivotally mounted contact arms utilize electromagnetic blow-apart, or blow-open, force to blow open the contact arm(s) upon the occurrence of such a sudden load fault. Although the blow-open force quickly initiates contact arm motion to begin tripping the circuit breaker, current may continue to arc across the contacts as the contact arm(s) swing open. consequently, further circuit breaker design principles include minimizing (and ideally eliminating) such arcing as the tripping continues. Furthermore, once current flow has terminated, any opportunity for its re-establishment must be foreclosed as the tripping concludes.
In accomplishing prompt arrest of current arcing across blowing-open contacts, it may be desirable for the circuit breaker mechanism to augment the impetus of the blow-open force as the tripping continues toward conclusion. But in doing so, the mechanism's augmentation of the force acting on the swinging contact arm(s) must not induce rebound of the contact arm(s) off of a stop to an extent that could potentially re-establish current flow.
Consider for example a circuit breaker that employs a spring-loaded, over-center toggle mechanism which goes over-center during the trip. As the mechanism goes over-center, an operating spring which had been effectively applying to the contact arm(s), a force resisting, but not preventing, the trip, now suddenly applies its force to aid the trip, driving the swinging contact arm(s) against the stop. That added force must not cause excessive contact arm rebound from the stop.
Circuit breaker design must therefore take into consideration various factors that may conflict. A better circuit breaker design will account for such factors to provide a circuit breaker that will terminate a specified fault current within a specified response time, with better assurance that current will not be re-established once the circuit breaker has been tripped. Moreover, a successful circuit breaker design should be cost and space efficient.
It is toward these and other objectives that the present invention is directed.
A known actuator for tripping a circuit breaker comprises a bi-metal strip that increasingly warps as it is increasingly heated. When heated above a certain point where a circuit breaker should be tripped, the strip will have warped sufficiently to cause the associated trip mechanism to enable the trip. A known trip mechanism conducts electric current through the length the strip inducing ohmic heating of the bi-metal.
The present invention relates to a novel construction for associating a bi-metal actuator with other associated parts that avoids conducting electric current through the entire length of the strip. The present invention is believed to cause less stress in the bi-metal and reduce the potential for damage to it, especially when a circuit breaker is tripped due to a short circuit fault.
In the illustrated embodiment, the invention is carried out by mounting a nominally flat bi-metal strip in cantilever fashion on a load terminal. More specifically, one end portion of the bi-metal is disposed flat against, and joined to, a portion of a load terminal. The other end portion of the bi-metal is spaced from the load terminal so as to be capable of warping as the thermal energy in the strip increases. When the thermal energy in the strip reaches a level where the circuit breaker should be tripped, the cantilevered portion of the strip will have warped sufficiently to enable tripping via the associated trip mechanism.
Because only the cantilevered portion of the strip warps, it may be considered as an active portion while the portion joined to the load terminal may be considered as an inactive portion because it is constrained by its joinder to the load terminal. It is believed that current passing through the load terminal passes substantially only through the inactive portion of the bi-metal so that substantially no current passes through the active portion. Because of this, it is further believed that the bi-metal should be subject to less stress and reduced potential for damage than might otherwise be the case without denigrating the effectiveness of strip warping to enable a trip. Thermal energy input to the bi-metal that is needed to operate the trip mechanism is caused by ohmic heating occurring in the inactive portion of the strip. That heat will flow from the inactive portion to the active portion because the bi-metal is a thermal conductor. Therefore the active portion of the strip will warp, but without conducting significant current, if indeed any current at all.
By further arranging the active portion of the bi-metal to face relatively closely and directly a portion of the load terminal, heat generated in that portion of the load terminal due to current flowing through it can radiate and/or convect to the confronting bi-metal, thereby augmenting the thermal energy input to the bi-metal. It is believed that this may accelerate a trip and further reduce the potential for damaging the bi-metal upon occurrence of a fault, especially one due to a short circuit.
Accordingly, one aspect of the present invention relates to an actuator for enabling a trip comprising a conductor through which current passes, a thermally responsive bi-metal having a first end portion which is disposed against a portion of the conductor and through which at least a portion of current carried by the conductor passes, the bi-metal further comprising a second end portion that is disposed in spaced relation to the conductor and is cantilever-mounted on the portion of the conductor via the bi-metal's first end portion, and that increasingly warps as thermal energy in the bi-metal increases for enabling a trip upon attaining a certain degree of warping.
Another aspect of the present invention relates to a circuit breaker comprising a first conductor member through which current passes from a line terminal to a load terminal, a mounting movably mounting the first conductor member for selective operation to a circuit-making condition enabling current to flow between the line and load terminals and to a circuit-breaking condition preventing current flow between the line and load terminals, an operating mechanism for moving the first conductor member, a trip mechanism that operates via the operating mechanism to enable the first conductor member to move from circuit-making condition to circuit-breaking condition and thereby trip the circuit breaker, and an actuator for causing the trip mechanism to enable a trip comprising a second conductor member through which current carried by the first conductor member passes, a thermally responsive bi-metal having a first end portion which is disposed against a portion of the second conductor member and through which at least a portion of current carried by the two conductor members passes, the bi-metal further comprising a second end portion that is disposed in spaced relation to the second conductor member and is cantilever-mounted on the portion of the second conductor member via the bi-metal's first end portion, that increasingly warps as thermal energy in the bi-metal increases, and that, upon attaining a certain degree of warping, causes the trip mechanism to enable a trip by enabling the first conductor member to move from circuit-making condition to circuit-breaking condition.
The foregoing, along with further features, advantages, and benefits of the invention, will be seen in the ensuing description and claims, which are accompanied by drawings. The description and drawings disclose a presently preferred embodiment of the invention according to the best mode contemplated at this time for carrying out the invention.

Thermal sensing bi-metal trip actuator for a circuit breaker


This invention relates to homogeneous liquid laundry detergent compositions containing polyhydroxy fatty acid amide, silicone antifoam composition, and anionic, nonionic or amphoteric surfactant. The silicone antifoam composition includes polyethylene glycol or a copolymer of polyethylene-polypropylene glycol having a solubility in water at room temperature of more than about 2 weight %.

Silicone antifoam compositions, and methods for producing them, have been described in, for example, U.S. Pat. Nos. 4,639,489 and 4,749,740, Aizawa et al, issued Jan. 27, 1987 and Jun. 7, 1988, respectively; and U.S. Pat. Nos. 4,978,471 and 4,983,316, Starch, issued Dec. 18, 1990 and Jan. 8, 1991, respectively.
Liquid laundry detergent compositions containing polyhydroxy fatty acid amide have been described in, for example, WO-92-06154, published Apr. 16, 1992. Anionic, nonionic and amphoteric surfactants are known ingredients of liquid laundry detergent compositions.
It has been found that it is difficult to formulate available silicone antifoam compositions into liquid laundry detergent compositions containing polyhydroxy fatty acid amide. These formulations tend to separate out after a few days in product. Even if they can be formulated into a storage stable product, they must also be effective at controlling suds in liquid laundry detergents. High suds are not desirable in the washing machine.
It has now been found that when polyethylene glycol (PEG), and/or copolymers of polyethylene-polypropylene glycol (PEG/PPG), having a solubility in water at room temperature of more than about 2 weight %, are substituted for the polypropylene glycol (PPG) heretofore present in a silicone antifoam composition, a stable, low sudsing liquid laundry detergent can be formulated. The liquid laundry detergent compositions, which contain polyhydroxy fatty acid amide, remain homogeneous upon storage. The silicone antifoam compositions with PEG and/or PEG/PPG copolymer are surprisingly better at suds reduction in this formulation in the washing machine than are the silicone antifoam compositions with PPG.

Liquid laundry detergent compositions with silicone antifoam agent


A measuring device including a control device, at least two ports, at least two measurement channels and at least two display devices. The control device assigns ports to the measurement channels and connects the measurement channels to these ports internally, at least logically. In this context, one display device is assigned to every port. The display devices allocated to the ports display information, which relates to the present assignment and/or utilization of the respective ports.

1. Field of the Invention
The invention relates to a measuring device, of which the measurement channels are dynamically assigned to its ports, and a corresponding measuring method.
2. Discussion of the Background
A vectorial network analyzer is conventionally used to determine the scattering parameters of a device under test. The ports for the test signals are generally allocated to the measurement channels on such a measuring device in a fixed manner. The allocation is identified by labelling the ports on the housing of the measuring device.
However, with this fixed allocation, it is disadvantageous that the user of the measuring device must match a measuring task to be implemented with the allocation. This means that, under some circumstances, the user must take into account a more complex wiring, in order to perform the measuring task. Alternatively, the user is forced to convert the determined scattering parameters into a required form.
Regarding the technical background, DE 10 2006 023 914 A1 discloses an oscilloscope with a fixed allocation of the ports to measurement channels with a preview display.

Measuring instrument and measuring method featuring dynamic channel allocation


The present invention relates to amino acid sequences for novel tachykinin polypeptides and base sequences encoding them, agonists and antagonists of such polypeptides, pharmaceutical compositions comprising them, and the like.

In all organisms, the coordinated regulation of events such as genesis, differentiation, growth, and homeostatic maintenance is dependent on intercellular and intertissue communication. In most cases, these processes are mediated by protein factors. Many secretory factors (humoral factors) which have been discovered are involved in the immune system and hematopoietic system, for example, and are referred to as cytokines, which include lymphokines, monokines, interferons, colony-stimulating factors, tumor necrosis factors, and the like. Their relation to disease and their potential use as drugs continue to be the subject of considerable research.
Humoral factors such as growth factors or peptide hormones produced by endocrine tissue also play an extremely important role in growth and homeostatic maintenance, and their application as drugs is the subject of considerable research.
For example, "tachykinins" is the generic term for a group of physiologically active peptides included in this category, which consist of about 10 amino acids and share in common the following carboxyl terminal sequence motif:
Phe-Xaa-Gly-Leu-Met-NH2
(the above sequence is an example in which the carboxyl group of the C terminal methionine is amidated, where Xaa can be any amino acid). Substance P, neurokinin A, and neurokinin B are known mammalian tachykinins, and are widely distributed in the central nervous and peripheral nervous systems. These peptides are generally released by the nerves, and in most cases are known to bind to various receptors (NK-1, NK-2, and NK-3) present in the body, thereby producing various forms of physiological activity depending on their activation. Particularly in terms of their pharmacological activity, it is clear from the literature, including Pernow et al., Pharmacol. Rev., Vol. 35, pp. 85-141 (1983), that proteins with the aforementioned carboxyl terminal structure are shared. Examples of such activity are widely ranging, such as smooth muscle contraction, decreased blood pressure, enhanced exocrine function, and stimulated vasopermeability. The release of such peptides is known to induce respiratory diseases such as respiratory inflammation or bronchial contraction, and the release of histamines from mast cells. Substance P, in particular, is believed to be involved in the neurotransmission of pain, including pain associated with migraines and arthritis. These peptides may also be involved in gastrointestinal disorders and diseases such as inflammatory bowel disease, as well as other diseases. In view of the great number of clinical diseases characterized by tachykinin over-involvement, the development of tachykinin receptor antagonists may be useful in controlling such clinical pathologies, and a number of peptide and non-peptide tachykinin receptor antagonists have been developed thus far (Nippon Rinsho, Vol. 48, No. 5, p. 98-104 (1990), The FASEB Journal, Vol. 4, pp. 1606-1615 (1990), and Current Medical Chemistry, Vol. 6, pp. 1375-1388 (1999)).
These protein and peptide factors, which are essential to organisms, have conventionally been found on the basis of their inherent biological activity. Genes with high homology have then been discovered by means of cloning techniques based on homology for known physiologically active proteins. However, it is highly likely that, in addition to these known gene groups, humoral functional molecules, which have not been identified by conventional techniques and whose existence therefore remains unknown, also play a major physiological role in maintaining the health of higher organisms, especially mammals.
More recent research based on bioinformatics has attempted to make biological, medical, and veterinary use of novel gene products, which have been discovered on the basis of DNA sequence data, through the aid of data processing techniques using computers (Trends in Biotechnology), Vol. 14, pp. 294-298 (1996). With recent achievements in the large-scale screening of cDNA libraries, an enormous number of novel genes or candidates have continued to be discovered through the compilation of EST (expressed sequence tag) data. However, much of this sequence data is fragmentary and incomplete. A currently remaining, major issue is that various existing cDNA-related public databases do not always contain the complete expressed genes for various organisms. It can thus be a daunting matter to search for completely novel and useful gene products in such databases. Meanwhile, structural analysis of all the DNA of a given organism, that is, the genome, has currently been completed for several bacteria and fungi (such as yeasts). Although such research for the human genomes is expected to take several years, the number of human genes is estimated to be around a hundred thousand. The genes coding for many secretory proteins or secretory peptides have actually been isolated already. However, that number cannot be understood to include all the genes of the genome. Despite the intense desire to find novel useful products, the aforementioned data processing techniques alone cannot be considered adequate for the elucidation of such genes; proof must be based on more detailed biological or chemical analysis and experimentation.

Tachykinin-like polypeptides and use thereof


An image acquisition apparatus 1A includes a sample stage 10 for placing a sample S thereon, an image pickup device 20 capable of acquiring a two-dimensional image and TDI driving, an image pickup optical system 30 including an objective lens 32, a scanning unit for acquiring an observation image while scanning the sample S by the image pickup device 20 and the image pickup optical system 30, and a focus oscillation control device 40 for controlling oscillation of a focus in the sample S so that an image pickup focus in the sample S oscillates at an oscillation frequency fs in an optical axis direction. The focus oscillation control device 40 sets the oscillation frequency fs so that the oscillation frequency fs substantially coincides with Ns times (Ns is an integer not less than 1) the basic frequency, which is a reciprocal 1/Ti of an image pickup period Ti of TDI driving in the image pickup device 20. Thus, an image acquisition apparatus capable of efficiently acquiring an observation image with focus extended can be realized.

Recently, in the field of pathology, etc., there are known virtual microscopes which can be operated as if an operator observes a sample through a real microscope in a virtual space of a personal computer or the like. Sample data to be handled in such a virtual microscope is based on image data of a sample acquired in advance by using a real microscope at high resolution.
For realizing image operation in the virtual microscope, it is demanded that an image acquisition apparatus which acquires image data (virtual slides) of a sample to be thus used in a virtual microscope acquires an image of a sample at sufficiently high resolution. For such image acquisition with high resolution, for example, a method for acquiring an observation image for a whole sample by imaging while scanning the sample two-dimensionally by an image pickup device has been used (for example, refer to Patent Documents 1 and 2). Thus, acquiring an image while scanning a sample two-dimensionally makes it easy to acquire a high-resolution image of the whole sample in a short time.


An IGBT is disclosed which has a set of inside trenches and an outside trench formed in its semiconductor substrate. The substrate has emitter regions adjacent the trenches, a p-type base region adjacent the emitter regions and trenches, and an n-type base region comprising a first and a second subregion contiguous to each other. The first subregion of the n-type base region is contiguous to the inside trenches whereas the second subregion, less in impurity concentration than the first, is disposed adjacent the outside trench. Breakdown is easier to occur than heretofore adjacent the inside trenches, saving the device from destruction through mitigation of a concentrated current flow adjacent the outside trench.

This invention relates to semiconductor devices, particularly to those having trenches formed in their substrate, and more particularly to trenched semiconductor devices of improved immunity to destruction. The trenched semiconductor devices according to the invention include, but are not limited to, an insulated-gate bipolar transistor (IGBT) and insulated-gate field-effect transistor (IGFET).
Japanese Unexamined Patent Publication No. 2005-57028 is hereby cited as teaching an IGBT that is trenched for a higher breakdown voltage. As illustrated in FIG. 1 for a better understanding of the features of the instant invention, the prior art trenched IGBT has a plurality of trenches 2 in its semiconductor substrate 1′. The substrate 1′ is variously doped to include n-type emitter regions 3, p-type base region 4, n-type base region 5, n+-type buffer region 6, p+-type collector region 7, p−-type reduced surface field (RESURF) region 8, and n+-type channel stop region 9. The trenches 2 receive gate conductors 11 as gate electrodes via gate insulators 10. An emitter electrode 12 is received in part in recesses 33 and 34 in one major surface 21 of the substrate 1′, in part overlies the trenches 2 via insulators 36, and is electrically coupled directly to both n-type emitter regions 3 and p-type base region 4. A collector electrode 13 underlies the other major surface 22 of the substrate 1′ and adjoins the p+-type collector region 7.
In order to turn this prior art IGBT on, a gate voltage may be applied to make the gate conductors 11 higher in potential than the emitter electrode 12, with the collector electrode 13 held higher in potential than the emitter electrode. The result is the creation of a channel in the p+-type base region 4 adjacent the trenches 2, permitting a current flow from collector electrode 13 to emitter electrode 12. The prior art IGBT is turned off by making the gate conductors 11 less in potential than the threshold. Thereupon the channel will disappear from the p-type base region 4. During the ensuing off period, the voltage between collector electrode 13 and emitter electrode 12 will be higher than that during the on period. A relatively high reverse bias voltage will be impressed between p-type base regions 4 and n-type base region 5, and a depletion layer or depletion region 14′ will spread as indicated by the broken line in FIG. 1.
The contour of the depletion region 14′ depends upon the relative positions of the trenches 2, which may be thought of as comprising a series of relatively inside trenches 2a and an outside trench 2b. The depletion region 14′ will be contoured mostly as desired in the neighborhoods of the inside trenches 2a, successfully mitigating field concentrations. Adjacent the outside trench 2b, however, the depletion region will not spread so much as desired because it has a neighboring trench on one side only, rather than on both sides like each of the inside trenches 2a. The field intensity will therefore become higher there than in the vicinities of the inside trenches. Breakdown has therefore been easy to occur near this outmost trench, with the consequent flow of a concentrated large current eventually leading to the destruction of the IGBT in the worst case.
An obvious expedient for alleviation of field intensity adjacent the outmost trench might seem to make the p-type base region 4 deeper on the outside of that trench. Such deeper part of the base region 4 would serve to spread the depletion region deeper for mitigation of field concentration adjacent the outmost trench. This measure is objectionable because the diffusion of a p-type dopant is the only possible way of deepening the required part of the base region 4. The deeper diffusion of the p-type dopant would inevitably invite its lateral (horizontal) diffusion in addition to that in the depth (vertical) direction. The base region 4 would therefore become larger in its surface area, necessitating use of a correspondingly larger substrate.
The above discussed problems arising from trenches are not limited to IGBTs. Similar difficulties have been encountered with other types of trenched semiconductor devices notably including IGFETs.


An optically active azo compound is represented by the following general formula (I), ##STR1## where R is an alkyl group having from 1 to 20 carbon atoms, and R* is an optically active radical of an alkyl group or a halogen substituted alkyl group having from 1 to 10 carbon atoms. A liquid crystal composition contains this compound. A method for producing an optically active azo compound represented by the following general formula (I) has the step of reacting a phenol compound represented by the following general formula (II) with an optically active carboxylic acid represented by the following general formula (III) using a condensing agent at a room temperature. ##STR2##

1. Field of the Invention
The present invention relates to a novel optically active azo compound, a producing method thereof, and a liquid crystal composition containing said compound.
2. Description of the Related Art
Each of liquid crystal materials is widely used as an element for a display at the present time. These liquid crystal display elements are almost constructed by a display system of a twisted nematic type (TN-type) using a nematic liquid crystal. This display system has many merits and advantages. However, responsibility of the display system is very low in comparison with that of a display system of a light emitting type such as a CRT. No responsibility can be easily improved although many liquid crystal display systems except for the display system of the TN-type are also considered.
However, a liquid crystal device using a ferroelectric smectic liquid crystal has a high response speed 100 to 1000 times that of the general liquid crystal display element of the TN-type. Further, this liquid crystal device has preferable bistability. Accordingly, displayed contents are memorized even when a power source of the liquid crystal device is turned off. Such a memory effect has been recently found. Therefore, there is a high possibility that such a liquid crystal device can be used for an optical shutter, a printer head, a thin type television, etc. The liquid crystal device is searched and developed at the present time to practically use this device in various kinds of industrial fields.
A phase of the ferroelectric liquid crystal belongs to a chiral smectic phase of a tilting system. A practically desirable liquid crystal phase of the ferroelectric liquid crystal is a so-called chiral smectic C-phase having low viscosity.
For example, the following properties are required with respect to such a ferroelectric liquid crystal material.
(1) The ferroelectric liquid crystal material is chemically stable and has excellent durability.
(2) The ferroelectric liquid crystal material has a wide liquid crystal phase in a temperature range from a low temperature to a high temperature and shows ferroelectricity in a wide temperature range including a room temperature.
(3) The rotational viscosity of a liquid crystal molecule in the ferroelectric liquid crystal material is small and the ferroelectric liquid crystal material has large spontaneous polarization and high speed responsibility.
For example, various kinds of liquid crystal compounds are already synthesized on the basis of such material designs in Japanese Patent Application Laying Open (KOKAI) Nos. Hei 2-225441 and Hei 2-229131, etc. However, at the present stage, it is difficult to obtain a practical material constituting a ferroelectric liquid crystal constructed by a single composition and satisfying the above-mentioned various properties. Similar to the case of a nematic liquid crystal already used practically, there is a trial for obtaining desirable characteristics for the ferroelectric liquid crystal by mixing several kinds of compounds with each other.

Optically active azo compound, producing method thereof, and liquid crystal composition containing said compound


A pulse compression signal processor (10) for a laser radar system which utilizes substantially identical negative slope SAW matched filters (30,44) for compressing both the up and down chirps of a bi-directional echo signal (14). The signal processor (10) receives the echo (14) and splits it into two signals (16, 18) for processing by separate negative slope SAW matched filters (30, 44).

1. Field of Invention
This invention relates generally to FM "chirped" laser radar systems and, more particularly, to a pulse compression signal processor which utilizes identical sound acoustic wave (SAW) matched filters for processing both the up and down chirps of a bi-directional linear FM echo signal.
2. Discussion
Laser radar systems which employ an intensely focused beam of light to detect the presence, position and motion of objects have been used in numerous applications, especially in the radar communications and measurement fields. Militarily, these systems have been implemented in conjunction with cruise missile and tactical fighter technology wherein laser radar has provided functions such as obstacle avoidance and terrain following. These laser radar systems enable sophisticated target homing capabilities for accurately guiding a missile or plane toward a target by utilizing a distinguishing feature of that target.
Linear frequency modulated (LFM) "chirped" laser radar has proven to be particularly useful in these applications. A "chirped" laser radar system typically includes a continuous wave (CW) transmitter which emits laser light at a preselected center frequency f.sub.c. This emitted light is frequency modulated into linear "chirps" by passing it through an electro-optical device disposed within the cavity of the transmitter. The shape of modulated waveform can be varied somewhat in order to optimize trade-offs in efficiency, complexity and performance.
A bi-directional type of waveform, as shown in FIG. 1, is often used to minimize range/doppler ambiguity in the system as well as to maximize the system's ambiguous range. To create this waveform, the frequency of each transmitted pulse is first increased and then decreased at a constant rate. The frequency variation created is preferably linear and the frequency versus time characteristic of the signal is typically of a trapezoid pattern as shown by the solid line in FIG. 1. Each chirp in the signal includes an "up chirp" component wherein frequency is increasing and a "down chirp" component wherein the frequency is decreasing.
The transmitted chirped signal is directed toward a target and then reflected back therefrom, creating a return signal or "echo" associated with the target. The time taken by the transmitted signal to reach the target and return causes the return signal to be displaced in time with respect to the transmitted signal. The echo signal naturally retains the same increases and decreases in frequency it had as a transmitted signal. This is shown graphically in FIG. 1 wherein the solid line represents a transmitted signal Tx and the dashed line is used to indicate a corresponding return signal Rx. As illustrated in FIG. 1, both the transmitted and return signals have an up chirp where frequency is steadily increasing and a corresponding down chirp where frequency decreases.
The instantaneous frequency difference between the transmitted and return signals is indicated in FIG. 1 as f.sub.o. To obtain this frequency difference, the return signal may be compared to a reference signal which is typically a sample of the transmitted signal created by using a beamsplitter to retain a small portion of the transmitted beam. Properly scaled, this instantaneous frequency difference f.sub.o can be used to "demodulate" the return signal in order to ascertain certain information about the target and its location.
To obtain both long range detection capabilities and fine range resolution, extremely narrow pulses of exceptionally high peak power need to be transmitted. But, because there exist practical limitations on the level of peak power used, the laser radar system typically utilizes a relatively long coded pulse as the transmitted signal and then takes advantage of pulse compression of the return signal to obtain a narrower pulse. This enables achievement of the increased detection ability of a long pulse radar system while also retaining the range resolution capability of a narrow pulse system. Transmission of long pulses also permits a more efficient use of the average power capability of the radar without generating high peak power signals.
Pulse compression allows the transmission of modulated pulses of sufficient width to provide the average power necessary to illuminate targets, at a reasonable level of peak power. The received echoes are then compressed by decoding their modulation to obtain the range accuracy and resolution equivalent to that of a short pulse. This is accomplished by increasing the transmitted signal bandwidth by modulating the frequency of the carrier within the transmitted pulse. With a matched filter, the received long pulse can be compressed to a short pulse of duration equal to the inverse of the transmitted signal bandwidth.
The various methods of pulse compression are essentially matched filtering schemes in which the transmitted pulses are coded and the received pulses are passed through a filter whose time-frequency characteristic is the conjugate (opposite) of the coding. This function is usually performed within the signal processor used to process the received echo.
The matched filter introduces into the signal a time lag that is inversely proportional to frequency. As illustrated in FIG. 2, a filter for compressing an up chirp has a signal transit time which decreases linearly with increasing frequency, at exactly the same rate as the frequency of the echo increases. The trailing portions of an up chirp echo, being of a progressively higher frequency, take less time to pass through than the lower frequency leading portions, thereby causing successive portions to bunch together or compress. When a pulse has been compressed by the filter, its amplitude is much greater and its width is much less than when it entered. While the output echo may be only a fraction of the width of the received echo, it can have many times the peak power.
In laser radar systems this pulse compression is typically performed with a surface acoustic wave (SAW) device used as a matched filter. The signal transit time may either decrease with frequency as shown in FIG. 2, to compress an up chirp, or else increase with frequency for compressing a down chirp. A filter of the type shown in FIG. 2 is often referred to as a negative slope device and a filter having an opposite configuration in which frequency increases with transit time is referred to as a positive slope device.
In previous laser radar systems, individual SAW matched filters were uniquely developed for processing each of the up and down pulses of a bi-directional echo signal. A positive slope SAW matched filter was used to compress the down chirp and a negative slope SAW matched filter was used to compress the up chirp.
However, SAW devices have a bulk mode problem with long delays which is aggravated with high frequencies. In a positive slope device, the higher frequencies take the longer delay through the filter. The bulk mode problems generate spurious signals difficult to eliminate by filtering. The output is also often preceded and followed by sidelobes, an undesirable series of lesser pulses.
There is, therefore, a need for a LFM chirp laser radar signal processor which substantially reduces these problems and is able to compress both the up and down chirps with improved performance.

Pulse compression signal processor utilizing identical saw matched filters for both up and down chirps


A process for purification which permits satisfactory removal of impurities from a block copolymer consisting essentially of polyethylene glycols and poly(acidic amino acid) and is suitable for the production of a polymeric carrier having a pharmaceutically acceptable purity; a process for producing such a polymeric carrier; a block copolymer reduced in impurity content; a polymeric carrier as described above; pharmaceutical preparations in polymeric form, produced by the use of the carrier; and a method of subjecting polyethylene glycols and poly(acidic amino acids)—which are impurities contained in the block copolymer—to treatment with either an ion-exchange resin or a partition/absorption resin and then determining the quantities of them with a gel filtration column.

There has been known an approach in which, by using a polymeric carrier that forms a micelle, a medicine, genes and the like are transported to a target place in a living organism; however, with respect to the block copolymer used for this purpose, impurities have not been sufficiently removed therefrom.
Conventionally, refining processes of the synthetic high molecular compound such as a block copolymer have been carried out by using a method such as a dialysis operation, an ultrafiltration operation and a precipitating operation.
In the refining methods of the dialysis operation and ultrafiltration operation, separating and refining processes are carried out based upon a difference in molecular weights. In general, dialysis membranes and ultrafiltration films are classified into groups depending on the maximum molecular weight that is allowed to permeate; however, there are great variations in precision of molecular weights of fraction. Consequently, in the methods for refining the synthetic high molecular compound such as a block copolymer through the dialysis operation and the ultrafiltration operation, it is not possible to carry out sufficient refining processes in the case when there is not a great difference between the molecular weight of a target synthetic high molecular compound and the molecular weight of impurities. Moreover, these methods are not suitable for industrial use, and are used as refining methods in laboratories in most cases.
In contrast, the refining method using a precipitating process has been widely used as a method that is also applicable to industrial use. In this method, by using a difference in solubility to a solvent, impurities are removed so as to carry out refining processes, and this method is superior in removing low-molecular-weight components from a synthetic high molecular compound such as a block copolymer. However, in the case of impurities having greater molecular weights such as polyethylene glycols and poly(acidic amino acids), there is only a small difference in solubility to a solvent between the synthetic high molecular compound such as a block copolymer and the impurities, with the result that the high molecular compound such as a block copolymer is not sufficiently refined through the precipitating process.
As described above, impurities having great molecular weights, contained in a block copolymer, have not been sufficiently removed, and a refining method, which is suitably used for obtaining a block copolymer that is also applicable to pharmaceutical preparations and the like, has not been known.
Moreover, with respect to a micelle-forming block copolymer having amphipathic property, the conventional method for quantitatively determining impurities in the block copolymer has failed to provide sufficient analysis results.
In the conventional method, the synthetic high molecular compound such as a block copolymer is dissolved in a solvent, and analyzed by using a high speed liquid chromatography to which a gel permeation column is connected (gel permeation chromatography: GPC).
However, in the case when there is only a small difference in molecular weights among the block copolymer and impurities contained therein, it is difficult to separate them with clear peaks, failing to provide sufficient performance as quantitative determination method for impurities.
Moreover, even in the case when there is a sufficient difference in molecular weights among them, if the quantity of impurities is small, it is not possible to obtain clear peaks. This is because since the gel permeation separation mechanism utilizes molecular diffusion, a peak tends to spread on the chromatogram to cause insufficient peak heights with respect to a component that is small in quantity. Consequently, the conventional method has failed to provide a quantitative determination method with sufficient performance.
Furthermore, since the conventional method separates and quantitatively determines a main component and impurities depending upon only the difference in molecular weights, no qualitative information, such as structures and provenance of impurities, is obtained.

Block copolymer reduced in impurity content, polymeric carrier, pharmaceutical preparations in polymeric form and process for the preparation of the same


An apparatus, system and method are provided for a switchable fiber termination (SFT) incorporated into an optical network device that responds to a test signal received via an optical network carrying data. The test signal may be a part of a multiplexed signal carrying data and is separated from the data by a wavelength division multiplexer. The SFT may be used to determine the characteristics of an optical network, including the operational status of optical network devices.

Technological advancements such as the Internet, video on demand, high-definition television (HDTV), video conferencing, multiple telephone lines, etc. and the need or desire for better quality video and audio have created the demand for more and more bandwidth at businesses and homes. In response to this demand, telecommunications providers and others began installing fiber optic telecommunications cables with extremely large bandwidths to replace or supplement traditional copper and coaxial systems. Fiber-optic cable is known in the art to one of ordinary skill and is generally comprised of a plurality of fiber-optic strands and buffering material encased in one or more layers of shielding material. Initially, because of the cost of fiber optic cable, head-end equipment and terminating equipment, the fiber optic cable was extended only to large businesses and local exchange panels where service to small business, homes and other residential dwellings was still occurring through copper wires. However, bandwidth demand has continued to grow and costs of fiber-optic cable and equipments has decreased and consequentially, telecommunications providers and others have begun to install fiber optic cable all the way to small businesses, homes and other residential dwellings. This is generally referred to as fiber to the premises (FTTP).
In many instances, passive optical networks (PONs) are used to provide FTTP as well as fiber to the curb (FTTC) and fiber to the neighborhood (FTTN). PON is a fiber to the premises configuration in which unpowered optical splitters are used to enable a single optical fiber to serve multiple premises. The advantages to PON include that it is a fiber-based transmission network that contains no active electronics and that a single fiber may provide service to multiple premises. It is a point-to-multipoint configuration, which reduces the amount of fiber required compared with point-to-point configurations. However, the very design that makes PONs attractive from a design and cost standpoint creates challenges when testing a PON, especially when the PON is on-line or active. Prior technologies have used a moveable mirror to selectively reflect light back into a fiber for test purposes. However, these devices reflect the light at all wavelengths back onto the fiber. This allows the fiber to be tested by an instrument at the other end of the fiber, but this test cannot be made without disrupting traffic on the fiber. Also, these devices have not been designed to work in PONs. Instead they have been used in point-to-point fiber networks or Fiber Distributed Data Interface (FDDI) networks (e.g., token ring).


A crop gathering attachment for an agricultural harvester having a rotatable auger-like conveyor for transporting crop material, a stationary crank shaft mechanism enclosed in the conveyor and having a shaft portion disposed eccentrically and parallel to the rotational axis of the conveyor, and a retractable finger arrangement comprising a plurality of finger members pivotally connected at their inner ends to the shaft portion and projecting outwardly through guiding members provided in the peripheral wall of the conveyor. The finger arrangement is timed such that due to the eccentric disposition of the shaft portion, the finger members are reciprocated relative to the conveyor wall upon rotation of the conveyor, thereby protruding from the wall at one side of the conveyor for projecting into the crop material and being retracted relative to the wall at the generally diametrically opposed side of the conveyor for releasing the transported crop. A unique actuator is operatively connected to the crank shaft mechanism for remotely controlling the position of the shaft portion relative to the conveyor and thereby varying the timing of the finger members.

A crop consolidating auger for a pick-up attachment usually extends the full width of the attachment and is provided with oppositely wound auger flights for gathering and consolidating the crop material in the central region of the auger from where the crop is conveyed towards processing means including, e.g., a comminuting rotor when the attachment is mounted on a forage harvester. Retractable fingers embodied in the auger, at least in the central region thereof, are a well known expedient for assisting the transfer of crop material from the pick-up device to the crop processing machine to which the device is attached.
Normally, such retractable fingers are carried on bearings which rotate on the eccentric part of a crank shaft mechanism which is coaxial with the rotational axis of the auger conveyor. The timing of the arrangement is such that, during operation, the fingers are protruding from the auger body to their maximum possible extent when oriented to the crop collecting side, i.e., the front side of the pick-up device, whereas the fingers are fully retracted when directed to the crop releasing side. In so doing, crop material lifted from the ground and presented to the consolidating auger, at least in the central portion thereof, is aggressively engaged by the protruding fingers and positively urged rearwardly where other crop transporting means are operable, such as forage harvester feed rolls or an elevating conveyor in a combine harvester feeder house.
Retractable finger arrangements of the type described is conventional in the art. For example, see U.S. Pat. No. 2,701,634, the content of which is incorporated herein by reference.
It has been experienced however that the above described finger timing position relative to the auger body is not always the best suited for all types of crops and crop conditions. Depending on, e.g., crop length, moisture content or degree of ripeness, different timing positions of the retractable fingers may be desirable in order to optimize transfer of crop material. In the arrangement shown in U.S. Pat. No. 2,701,634, mentioned above, means are provided to move the eccentric shaft relative to the pivot axis of the auger whereby a different timing position of the retractable fingers can be preset. However, among other things, this prior art arrangement suffers from the critical disadvantage that any adjustment of the finger orientation has to be performed while the harvester and attachment are inactive, meaning that the result of an adjusted finger setting is not immediately ascertainable. This leads to continuous periods of inoperation until the optimum timing is set for the existing crop conditions. Also, as crop conditions in a same field may vary widely, repeated trial and error adjustments of the finger orientation may be required leading to undesirable periods of downtime.
In addition to the above problems, crop gathering attachments occasionally become plugged due to a lump of crop material wedging between crop handling elements to the extent that it prevents normal operation. To obviate the need of manual unplugging, harvesters are commonly provided with a drive reversing mechanism which allows for reversing rotation of the crop conveying and processing means in order to evacuate the obstruction towards the front of the harvester, i.e., in a direction opposite to crop flow during normal operation. However, in the transitional area between the harvester base unit and its attachment, the auger fingers are completely retracted in the auger body, which is the normal position for the fingers during operation of the auger for releasing the transported crop appropriately. As a result, even with reverse mode available, plugging occurs necessitating shutdown to enable the operator to clear out the plug located in the transitional area.


A pixel structure having a first region and a second region adjacent to each other is provided. The pixel structure includes a first pixel electrode and a second pixel electrode. The first pixel electrode forms a plurality of first V-shaped electrode patterns. A tip of the first V-shaped electrode patterns is located at a boundary of the first region and the second region. The second pixel electrode includes a plurality of second V-shaped electrode patterns and a first protrusion electrode pattern. The first protrusion electrode pattern is connected to one of the second V-shaped electrode patterns and protrudes towards an adjacent first V-shaped electrode pattern from the tip of the second V-shaped electrode pattern.

1. Field of the Invention
The invention relates to a pixel structure, and more particularly to a pixel structure having two pixel electrodes.
2. Description of Related Art
Nowadays, multimedia technology has been well developed, which mostly benefits from the development of semiconductor devices and display apparatuses. As for the display, the liquid crystal display having superior features such as high picture quality, good space utilization efficiency, low power consumption and no radiation becomes the mainstream in the market. To have a better display quality, various types of liquid crystal display with wide viewing angle are developed, and the common ones are, for example, in-plane switching (IPS) liquid crystal displays, multi-domain vertically alignment (MVA) liquid crystal displays, fringe field switching (FFS) liquid crystal displays, and so on.
As for the IPS LCD and the FFS LCD, a driving electric field is substantially paralleled with a substrate, and liquid crystal molecules are rotated in a direction parallel with the substrate to achieve the light valve function for displaying a gray level. The pixel structures of the two types of LCD adopt two pixel electrodes configured with an interval, and the two pixel electrodes form an electric field passing through the interval therebetween by being applied with different voltages.
However, if a plurality of alignment domains are to be defined in the IPS and the FFS LCDs, two pixel electrodes are required to have a plurality of strip-shaped electrode patterns, respectively. In that meantime, it is likely to require an additional connecting electrode to be configured so that the stripe-shaped electrode patterns of the same pixel electrode can be connected to the same potential, such connecting electrode staggering another pixel electrode will cause poor distribution of the electric field.