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  • 1
    Electronic Resource
    Electronic Resource
    Monte Carlo analysis of the noise behavior in Si bipolar junction transistors and SiGe heterojunction bipolar transistors at radio frequencies (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 1582-1588 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a comparative analysis of the current spectral densities in a Si bipolar junction transistor (BJT) and a SiGe heterojunction bipolar transistor (HBT) of identical geometry performed by means of an ensemble Monte Carlo simulator self consistently coupled with a two-dimensional Poisson solver. We focus on the physical origin of the different noise sources in the transistors at rf when varying the injection level conditions. At low injection the spectral density of base current fluctuations, SJB(0), is governed by thermal noise related to the base resistance, while the collector spectral density, SJC(0), reaches a typical shot noise response. At high current density the onset of high injection in the base and the base push-out play an important role in the noise behavior of both transistors. Thus, SJC(0) deviates from the typical shot noise response. Hot carrier effects are also present. In the HBT, these effects are less important than in the BJT due to the SiGe/Si heterointerface, and SJB(0) can be neglected in the overall noise analysis because of the Ge content benefits when the structure enters the high-injection regime. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1384850
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  • 2
    Electronic Resource
    Electronic Resource
    Microscopic analysis of the influence of strain and band-gap offsets on noise characteristics in Si1−xGex/Si heterojunctions (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 5012-5020 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detailed study under forward-bias conditions of the physical origin of high frequency noise in p+(Si)-n (Si1−xGex) heterojunctions using ensemble Monte Carlo simulation is reported. Based on the internal magnitudes, we determine how the strained SiGe layer induces different features in the perpendicular transport of a heterojunction as compared with that of a silicon p+n homojunction. The main part of this study focuses on a comparative microscopic analysis of current fluctuations in homojunction and heterojunctions over a wide range of frequencies. A method based on considering a spatial analysis of noise to isolate the contributions of both types of carrier on the Si and Si1−xGex epilayers of the devices is described. The role of electrons and holes in the different regions of the devices and the combined effects of the band discontinuities and strain on noise characteristics in Si1−xGex/Si bipolar heterojunctions is discussed. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368748
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  • 3
    Electronic Resource
    Electronic Resource
    Coordinating properties of the Cephalexine antibiotic. A potentiometric study of the complexes formation between Cephalexine and Co(II), Ni(II) and Cu(II) metal ions
    Amsterdam : Elsevier
    Inorganica Chimica Acta 162 (1989), S. 113-119 
    Details
    ISSN: 0020-1693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0020-1693(00)83128-X
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  • 4
    Electronic Resource
    Electronic Resource
    ^1H NMR and UV-vis spectroscopic studies on Ni(II) carbonic anhydrase and its adducts with inorganic anions. Resonance assignments based on NOE effects
    Amsterdam : Elsevier
    Journal of Inorganic Biochemistry 43 (1991), S. 682 
    Details
    ISSN: 0162-0134
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0162-0134(91)84649-T
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  • 5
    Electronic Resource
    Electronic Resource
    Chitosanases in the autolysis of Mucor rouxii (1985)
    Springer
    Mycopathologia 89 (1985), S. 181-187 
    Details
    ISSN: 1573-0832
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The mycelium of Mucor rouxii reached a 50% degree of lysis after 50 days incubation, and was then stable with the incubation time. The pH of the medium was 4.3 when autolysis began, rising to pH 7.6 after 6 days of autolysis and remaining there for the duration of the experiment. Maximum degradation of mycelium occurs during the first days of autolysis. Glucosamine is present in the culture liquid during all the autolytic process. Enzymes implicated in the degradation of chitosan and chitin were studied in the culture fluid during autolysis. An exochitosanase activity was detected after a day of autolysis, and its activity increased during 20 days of autolysis and afterwards remained constant until the end of the process. An endochitosanase activity was detected in the culture fluid from the beginning of the autolysis, having its maximum activity after 34 days of incubation. Both activities show an optimum pH of 5.5, but the pH range of activity for endochitosanase was broader than for exochitosanase. Both activities were not inhibited by 0.5 mM glucosamine. Activities of the enzymes B-N-acetylglucosaminidase and chitinase were not found. The chitosan content in the cell walls decreased with the incubation time. In these cell walls the chitin content experienced an increase at the beginning of the autolysis, decreasing afterwards. The enzymatic complex obtained from autolyzed cultures of M. rouxii hydrolyzed 2-day-old cell walls of this fungus. The hydrolysis was 21% after 24 h of incubation, liberating glucose and glucosamine. As a consequence protoplasts from M. rouxii germinated spores were obtained with its own lytic enzymes in adequate osmotic conditions. The involvement of chitosanases in the autolysis of this fungus have been studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00447029
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of pectin on pectinases in autolysis of Botrytis cinerea (1988)
    Springer
    Mycopathologia 102 (1988), S. 37-43 
    Details
    ISSN: 1573-0832
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Pectic activity in autolyzed cultures of Botrytis cinerea in a medium with and without pectin was similar, but in the medium with pectin maximal activities occurred in younger cultures. The pectic activities found were polygalacturonase, polymethylgalacturonase, endo activity (pectin as substrate) and pectin lyase. The molecular weights of polygalacturonase, polymethylgalacturonase and endo activity (pectin as substrate) were 36000, 33000 and 30200 daltons respectively, and the molecular weight of pectin lyase was 18200 daltons. By gel electrophoresis four different pectic activities were detected, three in the top of the gel and one in the bottom. Two enzymes were characterized, the polygalacturonase activity (first band in the top) inhibited by Ca++ and the pectin lyase activity (in the bottom) which was not inhibited by Ca++. These enzymes are not induced by the presence of pectin in the medium during degradation of Botrytis cinerea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00436250
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  • 7
    Electronic Resource
    Electronic Resource
    Cell wall degradation in the autolysis of filamentous fungi (1982)
    Springer
    Mycopathologia 80 (1982), S. 147-155 
    Details
    ISSN: 1573-0832
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A systematic study on autolysis of the cell walls of fungi has been made on Neurospora crassa, Botrytis cinerea, Polystictus versicolor, Aspergillus nidulans, Schizophyllum commune, Aspergillus niger, and Mucor mucedo. During autolysis each fungus produces the necessary lytic enzymes for its autodegradation. From autolyzed cultures of each fungus enzymatic precipitates were obtained. The degree of lysis of the cell walls, obtained from non-autolyzed mycelia, was studied by incubating these cell walls with and without a supply of their own lytic enzymes. The degree of lysis increased with the incubation time and generally was higher with a supply of lytic enzymes. Cell walls from mycelia of different ages were obtained. A higher degree of lysis was always found, in young cell walls than in older cell walls, when exogenous lytic enzymes were present. In all the fungi studied, there is lysis of the cell walls during autolysis. This is confirmed by the change of the cell wall structure as well as by the degree of lysis reached by the cell wall and the release of substances, principally glucose and N-acetylglucosamine in the medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00437577
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  • 8
    Electronic Resource
    Electronic Resource
    Hydrogen-peroxide-producing system ofPleurotus eryngii involving the extracellular enzyme aryl-alcohol oxidase (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 465-470 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The effect of benzyl alcohol, benzaldehyde and benzoic acid on the production of extracellular hydrogen peroxide (H2O2) by the ligninolytic fungusPleurotus eryngii was investigated. It was found that an equilibrium between oxidative and reductive reactions of these compounds is established, leading to the continuous production of H2O2. A multienzymatic cyclic system is proposed in which H2O2 is produced extracellularly by the action of aryl-alcohol oxidase on benzyl alcohol, the most abundant compound after redox reactions, and to a lower extent on benzaldehyde. The oxidation products of these reactions, benzaldehyde and benzoic acid, are reduced by intracellular dehydrogenases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00939037
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  • 9
    Electronic Resource
    Electronic Resource
    Studies on homoveratric acid transformation by the ligninolytic fungus Pleurotus eryngii (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 500-504 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Homoveratric acid (HVA) degradation was observed in cultures of Pleurotus eryngii lacking lignin peroxidase (LiP) activity. Extracellular enzymes seemed responsible for this transformation, and the lack of activity after ultrafiltration of the culture liquid suggests that the presence of some low-molecular-size compounds is required. This hypothesis is supported by rapid HVA transformation after addition of the synthetic laccase substrate 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) to the ultrafiltered liquid. HVA transformation by the extracellular enzymes from P. eryngii takes place via Cα-Cβ breakdown and formation of veratryl alcohol, which is further transformed into veratraldehyde. The same major compounds were found during HVA transformation by LiP from Phanerochaete chrysosporium, but this reaction was not stimulated by ABTS. Although the involvement of other enzymes cannot be ruled out, purified laccase from Pleurotus eryngii caused the same HVA transformation pattern in presence of ABTS. Moreover, veratryl alcohol oxidation by P. eryngii laccase was demonstrated in the presence of ABTS. These results suggest that enzymatic systems lacking LiP could be responsible for natural degradation of lignin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00178479
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  • 10
    Electronic Resource
    Electronic Resource
    Hydrogen-peroxide-producing system ofPleurotus eryngii involving the extracellular enzyme aryl-alcohol oxidase (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 465-470 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The effect of benzyl alcohol, benzaldehyde and benzoic acid on the production of extracellular hydrogen peroxide (H2O2) by the ligninolytic fungusPleurotus eryngii was investigated. It was found that an equilibrium between oxidative and reductive reactions of these compounds is established, leading to the continuous production of H2O2. A multienzymatic cyclic system is proposed in which H2O2 is produced extracellularly by the action of aryl-alcohol oxidase on benzyl alcohol, the most abundant compound after redox reactions, and to a lower extent on benzaldehyde. The oxidation products of these reactions, benzaldehyde and benzoic acid, are reduced by intracellular dehydrogenases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01982537
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