Publications (25) View all
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Conference Proceeding: Effects of process variations on the current in Schottky Barrier Source-Gated Transistors
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ABSTRACT: The sensitivity of the drain current in Schottky barrier source-gated transistors to process variation is studied using computer simulations. It is shown that provided the device is designed correctly, the current is independent of source-drain separation and is insensitive to source length variations. However, uniform insulator thickness and precise control of the source barrier is needed if good current uniformity is to be obtained.Semiconductor Conference, 2009. CAS 2009. International; 11/2009 -
Article: [Identification of a fibrinolytic enzyme producing Bacillus pseudomycoides and purification and characterization of the enzyme].
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ABSTRACT: To purify a single fibrinolytic enzyme from Bacillus pseudomycoides B-60 and to determine its N-terminal sequence and to characterize the fibrinolytic enzyme. We examined the fibrinolytic enzyme activity by fibrin plate and purified fibrinolytic enzyme by ammonium sulfate fractional precipitation and DEAE anion exchange chromatography. Obtained a single protein fraction with fibrinolytic activity (BpFE) from B. pseudomycoides B-60. It appeared as a single band in the SDS-PAGE with a relative molecular weight of 34 kDa. The fibrinolytic activity of the protein was stable at 4-50 degrees C and at pH 5-10. The activity sharply decreased above 50 degrees C, and the total loss of activity at pH 3.0. The enzymatic activity was slightly enhanced by the ions of Ca2+, Mg2+, Mn2+, whereas strongly inhibited by Cu2+ ion. Phenylmethyl sulfonyl fluoride (PMSF) could completely inhibit its activity. In addition, the activity improved when the protein was enzymatically hydrolyzed using trypsin and pepsin. The first 15 amino acids of the N-terminal sequence of the enzyme were determined to be VTGTNAVGTGKGVLG. The partial amino acids sequence alignment study of the enzyme from B-60 strain with bacillolysin, neutral protease and hydrolase which were from B. cereus, B. thuringiensis, B. anthracis and Lactobacillus sp. was carried out, and there is a 100% homogeneity between them. We obtained a single fibrinolytic enzyme. Through its N-terminal sequence alignment study, a plasmin with high homogeneity to this protein was not found yet. This provided a basis for further study of new thrombolytic drugs.ACTA MICROBIOLOGICA SINICA 05/2009; 49(4):492-7. -
Article: [Purification and characterization of fibrinolytic enzyme from Bacillus subtilis BS-26].
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ABSTRACT: Thrombolytic therapy is a safe and effective treatment for thrombotic diseases. Microorganisms are possible sources of thrombolytic drugs. We purified and characterized fibrinolytic enzyme produced by Bacillus subtilis strain BS-26. We examined the fibrinolytic enzyme activity by fibrin plate and purified fibrinolytic enzyme by ammonium sulfate fractional precipitation, anion-exchange chromatography on DEAE-Sepharose Fast Flow and preparative PAGE. The fibrinolytic enzyme of the strain BS-26 was stable blow 50 degrees C and pH5.0-11.0, the optimal temperature was 42 degrees C and optimal pH was 9.0. Ca2+ and Mg2+ ions enhanced the fibrinolytic activity, whereas Cu2+ completely inhibited the enzyme. Phenylmethylsulfonyl fluoride (174.2 microg/mL), chicken ovomucoid (1000 microg/mL) and soybean trypsin inhibitor (1000 microg/mL) could inhibit enzyme activity, which indicated that the enzyme belonged to serine protease group. On plasminogen-free fibrin plates and plasminogen fibrin plates, the fibrinolytic activity had no obvious difference, indicating that the enzyme was a fibrinolytic enzyme which degraded fibrin directly, but not a plasminogen activator which degraded fibrin by activating plasminogen. A fibrinolytic enzyme was purified from the fermentation broth with recovery yield of 3.2%, purification factor of 41.0 fold and the specific activity 8750.0 U/mg. SDS-PAGE analysis of the purified protein showed only one band with molecular mass of 32 kDa. A single fibrinolytic enzyme was purified, which provided the basis for large-scale production of fibrinolytic enzyme.ACTA MICROBIOLOGICA SINICA 11/2008; 48(10):1387-92. -
Article: Engineering. High-performance transistors by design.
Science 06/2008; 320(5876):618-9. · 31.20 Impact Factor -
Conference Proceeding: High Performance Transistors in Low Mobility Organic Semiconductors for Analog and High-Frequency Applications
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ABSTRACT: In conventional organic field-effect transistors (OFETs), the low mobility of carriers in the organic semiconductor layers leads to low device speed , which seriously limits the applicability of the devices for analog and high frequency circuits in high performance applications. In this paper, the source- gated transistor (SGT) concept is introduced for high performance transistors in low mobility organic semiconductors, in which the source comprises a potential barrier to current flow and a gate is used to modulate the electric field at the reverse-biased source barrier and change the current. Compared to the OFET, the OSGT has a much smaller susceptibility to short-channel effects, and can be operated with much higher internal electrical fields giving high drive current and high speed. The numerical simulation results show that the OSGT can be an excellent candidate for designing high performance transistors in low-mobility organic materials for analog and high frequency applications.Flexible Electronics and Displays Conference and Exhibition, 2008; 02/2008
