V-CE Sensing for IGBT Protection in NPC Three Level Converters-Causes For Spurious Trippings and Their Elimination

Neutral point clamped (NPC), three level converters with insulated gate bipolar transistor devices are very popular in medium voltage, high power applications. DC bus short circuit protection is usually done, using the sensed voltage across collector and emitter (i.e., V-CE sensing), of all the devices in a leg. This feature is accommodated with the conventional gate drive circuits used in the two level converters. The similar gate drive circuit, when adopted for NPC three level converter protection, leads to false V-CE fault signals for inner devices of the leg. The paper explains the detailed circuit behavior and reasons, which result in the occurrence of such false V-CE fault signals. This paper also illustrates that such a phenomenon shows dependence on the power factor of the supplied three-phase load. Finally, experimental results are presented to support the analysis. It is shown that the problem can be avoided by blocking out the V-CE sense fault signals of the inner devices of the leg.

Localization and release of ?-glucosidase in the thermophilic and cellulolytic fungus, Sporotrichum thermophile

In a medium containing cellulose as the carbon source, the rapid growth of Sporotrichum thermophile, the secretion of cellulases and the utilization of cellulose were well-correlated events. The production of beta-glucosidase in culture medium lagged behind cellulases, coinciding with the time of extensive autolysis of mycelia. By contrast, neither apparent autolysis nor secretion of beta-glucosidase occurred when S. thermophile was grown in medium containing cellobiose; the enzyme activity remained associated with mycelia. The release of beta-glucosidase in cellulose-grown cultures was correlated with the activity of the lytic enzyme in the cell wall. Immunocytochemical localization and biochemical characterization showed that a beta-glucosidase released in the cellulose medium was the same as that which remained associated with mycelia grown on cellobiose. The results indicated that the release of beta-glucosidase in the cellulose culture is incidental to the activity of the lytic enzymes which are strongly induced by cellulose. The observations minimize a functional role of the culture fluid beta-glucosidase in cellulolysis by the fungus. Rather, the available information suggests that the cellulases and beta-glucosidases associated with the hyphal cell wall may play a role in cellulolysis by the fungus. (C) 1994 Academic Press, Inc.

Localization and release of β-glucosidase in the thermophilic and cellulolytic fungus, Sporotrichum thermophile

n a medium containing cellulose as the carbon source, the rapid growth of Sporotrichum thermophile, the secretion of cellulases and the utilization of cellulose were well-correlated events. The production of beta-glucosidase in culture medium lagged behind cellulases, coinciding with the time of extensive autolysis of mycelia. By contrast, neither apparent autolysis nor secretion of beta-glucosidase occurred when S. thermophile was grown in medium containing cellobiose; the enzyme activity remained associated with mycelia. The release of beta-glucosidase in cellulose-grown cultures was correlated with the activity of the lytic enzyme in the cell wall. Immunocytochemical localization and biochemical characterization showed that a beta-glucosidase released in the cellulose medium was the same as that which remained associated with mycelia grown on cellobiose. The results indicated that the release of beta-glucosidase in the cellulose culture is incidental to the activity of the lytic enzymes which are strongly induced by cellulose. The observations minimize a functional role of the culture fluid beta-glucosidase in cellulolysis by the fungus. Rather, the available information suggests that the cellulases and beta-glucosidases associated with the hyphal cell wall may play a role in cellulolysis by the fungus. (C) 1994 Academic Press, Inc.

Influence of Tempered Microstructures on the Transformation Behaviour of Cold Deformed and Intercritically Annealed Medium Carbon Low Alloy Steel

This research is focused on understanding the role of microstructural variables and processing parameters in obtaining optimised dual phase structures in medium carbon low alloy steels. Tempered Martensite structures produced at 300, 500, and 650 degrees C, were cold rolled to varied degrees ranging from 20 to 80% deformation. Intercritical annealing was then performed at 740, 760, and 780 degrees C for various time duration ranging from 60 seconds to 60 minutes before quenching in water. The transformation behaviour was studied with the aid of optical microscopy and hardness curves. From the results, it is observed that microstructural condition, deformation, and intercritical temperatures influenced the chronological order of the competing stress relaxation and decomposition phase reactions which interfered with the rate of the expected alpha -> gamma transformation. The three unique transformation trends observed are systematically analyzed. It was also observed that the 300 and 500 degrees C tempered initial microstructures were unsuitable for the production of dual structures with optimized strength characteristics.

Consistency tests of Ampcalculator and chiral amplitudes in SU(3) Chiral Perturbation Theory: A tutorial-based approach

Ampcalculator (AMPC) is a Mathematica (c) based program that was made publicly available some time ago by Unterdorfer and Ecker. It enables the user to compute several processes at one loop (upto O(p(4))) in SU(3) chiral perturbation theory. They include computing matrix elements and form factors for strong and non-leptonic weak processes with at most six external states. It was used to compute some novel processes and was tested against well-known results by the original authors. Here we present the results of several thorough checks of the package. Exhaustive checks performed by the original authors are not publicly available, and hence the present effort. Some new results are obtained from the software especially in the kaon odd-intrinsic parity non-leptonic decay sector involving the coupling G(27). Another illustrative set of amplitudes at tree level we provide is in the context of tau-decays with several mesons including quark mass effects, of use to the BELLE experiment. All eight meson-meson scattering amplitudes have been checked. The Kaon-Compton amplitude has been checked and a minor error in the published results has been pointed out. This exercise is a tutorial-based one, wherein several input and output notebooks are also being made available as ancillary files on the arXiv. Some of the additional notebooks we provide contain explicit expressions that we have used for comparison with established results. The purpose is to encourage users to apply the software to suit their specific needs. An automatic amplitude generator of this type can provide error-free outputs that could be used as inputs for further simplification, and in varied scenarios such as applications of chiral perturbation theory at finite temperature, density and volume. This can also be used by students as a learning aid in low-energy hadron dynamics.

Remarkable role of positional isomers in the design of sensors for the ratiometric detection of copper and mercury ions in water

Cation sensing properties of the three positional isomers of rhodamine based sensors (1-3) are studied in water. The sensors differ only in the position of pyridine's nitrogen. The chemosensor 1, with pyridine nitrogen at ortho-position, showed a selective colorimetric detection of Cu(II) ions in water, at physiological pH 7.4 and also in medium containing BSA (bovine serum albumin) and blood serum. Notably the compound 2 and 3, with pyridine end located at meta-and para-positions did not show any color change with Cu(II) ions, although both the compounds showed turn-on change both in color and fluorescence with Hg(II) ions specifically. All the probes showed ratiometric changes with the specific metal ions. The changing position of nitrogen also changed the complexation pattern of the sensors with the metal ions. Probe 1 showed 2 : 1 complexation with Cu(II), whereas 2 and 3 showed 1 : 1 complexation with Hg(II) ions. The mechanism investigation showed that the change in color upon addition of metal ions is due to the ring-opening of the spirolactam ring of the probes. Cu(II) interacted with ligand 1 through a three-point interaction mode comprising carbonyl oxygen, amido nitrogen and pyridine nitrogen end. But in case of 2 and 3, Hg2+ only interacted through pyridine nitrogen ends. Quantitative estimation of Cu2+ and Hg2+ in complex biological media such as bovine albumin protein (BSA) and human blood serum were performed using these sensors. Rapid on-site detection as well as discrimination of these toxic ions was demonstrated using easily prepared portable test-strips.

The intensity distributions of collected signals in coherent anti-Stokes Raman scattering microscopy

Coherent anti-Stokes Raman scattering (CARS) microscopy with the combining of confocal and CARS techniques is a remarkable alternative for imaging chemical or biological specimens that neither fluoresce nor tolerate labeling. The CARS is a nonlinear optical process, the imaging properties of CARS microscopy will be very different from the conventional confocal microscopy. In this paper, we calculated the propagation of CARS signals by using the wave equation in medium and the slowly varying envelope approximation (SVEA), and find that the intensity angular distributions vary considerably with the different experimental configurations and the different specimen shapes. So the conventional description of microscopy (e.g.. the point spread function) will fail to descript the imaging properties of CARS microscopy. (c) 2004 Elsevier B.V. All rights reserved.

Applications of nuclear magnetic resonance spectroscopy to the study of medium-sized rings. I. Conformational properties of cycloheptane. II. Conformational properties of cycloöctane

Conformational equilibrium in medium-sized rings has been investigated by the temperature variation of the fluorine-19 n.m.r. spectra of 1, 1-difluorocycloalkanes and various substituted derivatives of them. Inversion has been found to be fast on the n.m.r. time scale at -180˚ for 1, 1-difluorocycloheptane, but slow for 1, 1-difluoro-4, 4-dimethylcycloheptane at -150˚. At low temperature, the latter compound affords a single AB pattern with a chemical-shift difference of 841 cps. which has been interpreted in terms of the twist-chair conformation with the methyl groups on the axis position and the fluorine atoms in the 4-position. At room temperature, the n.m.r. spectrum of 1, 1-difluoro-4-t-butylcycloheptane affords an AB pattern with a chemical-shift difference of 185 cps. The presence of distinct trans and gauche couplings from the adjacent hydrogens has been interpreted to suggest the existence of a single predominant form, the twist chair with the fluorine atoms on the axis position.

Investigation of 1, 1-difluorocycloöctane and 1, 1, 4, 4-tetrafluorocycloöctane has led to the detection of two kinetic processes both having activation energies of 8-10 kcal./mole but quite different A values. In light of these results eleven different conformations of cycloöctane along with a detailed description of the ways in which they may be interconverted are discussed. An interpretation involving the twist-boat conformation rapidly equilibrating through the saddle and the parallel-boat forms at room temperature is compatible with the results.

Estabelecimento de culturas de raízes in vitro e avaliação da produção de metabólitos secundários de Cleome spinosa Jacq. (Cleomaceae)

Cleome spinosa é uma espécie herbácea de uso na medicina popular, especialmente no Nordeste do Brasil. A cultura in vitro de raízes adventícias da espécie foi iniciada com segmentos radiculares (0,5 e 1,0 cm) obtidos a partir de duas fontes de explantes: plantas propagadas in vitro e plantas oriundas do processo de germinação in vitro. Os explantes foram inoculados em meio MS líquido suplementado ou não com as auxinas ANA, AIA e AIB em diferentes concentrações (0,5; 1,0; 1,5; 3,0; 5,0 mg.L-1). As culturas foram mantidas em sala de crescimento, sob agitação (100 rpm) e sob fotoperíodo de 16h ou no escuro, com subculturas a cada 45 dias. Explantes oriundos de plantas propagadas in vitro também foram cultivados em meio contendo a citocinina BAP em associação com auxinas, na presença de sorbitol (isoladamente ou em associação com sacarose), em meio MS contendo redução na concentração total de sais minerais (MS1/2 e MS1/4) e em meio sólido. Os resultados mostraram que a adição de auxinas ao meio de cultura foi essencial à multiplicação das raízes, uma vez que em meio MS0 ocorreu significativo desenvolvimento de brotos. A suplementação com ANA não foi eficiente para a produção de raízes e acarretou no calejamento dos explantes, enquanto que a presença de AIA e AIB resultaram na multiplicação das raízes. Ainda assim, independentemente das manipulações realizadas no meio de cultivo, a capacidade de multiplicação mostrou-se reduzida. Uma expressiva multiplicação de raízes foi observada em culturas iniciadas a partir de explantes oriundos de plantas obtidas por germinação in vitro. A maior produção de biomassa foi alcançada em culturas iniciadas com segmentos radiculares de plantas obtidas por germinação in vitro cultivadas em meio contendo com 3,0 mg.L-1 de AIB e mantidas no escuro. Culturas estabelecidas nas melhores condições para acúmulo de biomassa foram acompanhadas por três subculturas, sendo avaliados períodos de cultura de 45 dias e de 60 dias. Culturas mantidas a intervalos de 45 dias apresentaram maior produção de raízes durante a segunda subcultura, enquanto que para o intervalo de 60 dias, embora tenha sido observada a capacidade de multiplicação das raízes, a maior produção de biomassa ocorreu nos primeiros 60 dias de cultivo. A partir de materiais in vivo e in vitro foram realizadas extrações com solventes de polaridade crescente (hexano, diclorometano, acetato de etila e metanol) e os extratos foram submetidos a avaliações cromatográficas. As análises por cromatografia em camada delgada mostraram a presença de terpenos nos extratos obtidos com hexano e diclorometano, tanto em material obtido a campo como naqueles produzidos in vitro e de compostos fenólicos nos extratos em acetato de etila obtidos a partir de material de campo. Pelas análises por cromatografia líquida associada à espectrometria de massas foi possível observar a presença de flavonoides nas culturas in vitro, não detectados no material de campo. As análises por cromatografia de fase gasosa associada à espectrometria de massas apontaram a presença de esteroides nos extratos em hexano de raízes coletadas a campo e nas culturas in vitro de raízes. Os resultados obtidos mostraram a viabilidade da produção de culturas de raízes in vitro para a espécie C. spinosa e o potencial deste material para a produção de substâncias bioativas, algumas não encontradas em material coletado a campo

17 beta-Estradiol and progesterone improve in-vitro cytoplasmic maturation of oocytes from unstimulated prepubertal and adult rhesus monkeys

BACKGROUND: Effects of 17beta-estradiol and progesterone on rhesus monkey oocyte maturation in vitro were evaluated by embryo development subsequent to IVF. METHODS AND RESULTS: In experiment 1, immature cumulus-oocyte complexes collected from unstimulated adult females during the non-breeding season were matured in modified medium CMRL-1066 containing various combinations of gonadotrophins (FSH + LH), estradiol and/or progesterone. Formation of morulae and blastocysts was greatest in oocytes matured in medium containing estradiol and/or progesterone, with or without gonadotrophins (morula 38-46%, blastocyst 14-20%) than in control oocytes matured without estradiol or progesterone (morula 14%, blastocyst 0%). In experiment 2, cumulus-oocyte complexes from unstimulated prepubertal female monkeys were matured in medium with gonadotrophins, estradiol or progesterone. The best development to the morula stage was obtained with oocytes matured with gonadotrophins and estradiol or gonadotrophins and progesterone (43 and 25 morulae, respectively), while control oocytes matured with gonadotrophins but without steroid hormones gave the poorest morula developmental response (12%). However, there was no difference in blastocyst development across all groups (0-3%). CONCLUSIONS: These results demonstrate that during rhesus monkey oocyte maturation in vitro: (i) estradiol or progesterone can improve oocyte developmental competence; (ii) immature oocytes from prepubertal versus adult females have differential responses to challenge with estradiol or progesterone.

Culture of green algae Chlorella ellipsoidea in inexpensive media

The culture of the of green alga Chlorella ellipsoidea was conducted under natural conditions at the same place simultaneously in five different media, viz., medium-I (inorganic medium), medium-II (powdered whole-pulse medium), medium-III (medium of pulse bran), medium-IV (mixed medium = 50% inorganic medium + 50% whole-pulse powder medium), medium-V (mixed medium = 50% inorganic medium + 50% pulse bran medium). The culture was done in 500 ml conical flask. Growth rates of C. ellipsoidea in five different media were different and reached maximum cell densities of 0.63 x 10^6 cells per ml in 8 days in medium-I, 4.02 x 10^6 cells per ml in 10 days in medium-II, 3.62 x 10^6 cells per ml in 9 days in medium-III, 4.38 x 10^6 cells per ml in 11 days in medium-IV and 4.36 x 10^6 cells per ml in 11 days in medium-V. The range of air temperature was 20 to 33°C and that of culture media was 24 to 32°C and light intensity was 2000 to 7000 lux during the culture period. The inexpensive culture media were found to be significantly useful for algal culture.

The efficiency of compensation grouting in sands

Physical model experiments on compensation grouting in sands were performed in two different setups (Cambridge and Delft). The effect of water-cement (w/c) ratio, bentonite content (b.c.) and injection rate on compensation efficiency was investigated. Results show a considerable drop in compensation efficiency resulted from reducing the soil density. Injection in dense sand (R.D. = 93%) resulted in efficiencies between 40-90%, whereas injection in medium-dense sand (R.D. = 60-75%) yielded in reduced efficiencies between 10-40%. When the w/c ratio increased from 0.5 to 1.5 for a given density (R.D. = 93%) and the b.c. of 4%, the compensation efficiency value decreased. Typical efficiencies were between 60% and 40-50% for w/c ratios of 0.5 and 1.5, respectively. The values of compensation and grout efficiencies were almost equal, suggesting that pressure filtration happens mainly during injection. Increasing the b.c. improved the compensation efficiency. When a higher b.c. of 12% to 14% was used, typical compensation efficiencies in dense sand were 78 and 90% for w/c ratios of 1.5 and 1.8 respectively. © 2012 Taylor & Francis Group.

Depletion of Vipp1 in Synechocystis sp PCC 6803 affects photosynthetic activity before the loss of thylakoid membranes

A vipp1 mutant of Synechocystis sp. PCC 6803 could not be completely segregated under either mixotrophic or heterotrophic conditions. A vipp1 gene with a copper-regulated promoter (P-petE-vipp1) was integrated into a neutral platform in the genome of the merodiploid mutant. The copper-induced expression of P-petE-vipp1 allowed a complete segregation of the vipp1 mutant and observation of the phenotype of Synechocystis 6803 with different levels of vesicle-inducing protein in plastids 1 (Vipp1). When P-petE-vipp1 was turned off by copper deprivation, Synechocystis lost Vipp1 and photosynthetic activity almost simultaneously, and at a later stage, thylakoid membranes and cell viability. The photosystem II (PSII)-mediated electron transfer was much more rapidly reduced than the PSI-mediated electron transfer. By testing a series of concentrations, we found that P-petE-vipp1 cells grown in medium with 0.025 mu M Cu2+ showed no reduction of thylakoid membranes, but greatly reduced photosynthetic activity and viability. These results suggested that in contrast to a previous report, the loss of photosynthetic activity may not have been due to the loss of thylakoid membranes, but may have been caused more directly by the loss of Vipp1 in Synechocystis 6803.

Pion Production in Heavy-ion Collisions in the 1 A GeV region

Within the framework of the improved isospin dependent quantum molecular dynamics (ImIQMD) model, the pion emission in heavy-ion collisions in the region 1AGeV is investigated systematically, in which the pion is considered to be mainly produced by the decay of resonances ∆(1232) and N∗(1440). The in-medium dependence and Coulomb effects of the pion production are included in the calculation. Total pion multiplicity and π−/π+ yields are calculated for the reaction 197Au+197Au in central collisions for selected Skyrme parameters SkP, SLy6,Ska, SIII and compared them with the measured data by the FOPI collaboration.

Pion Production in Heavy-Ion Collisions in the 1 A GeV Region

Within the framework of the improved isospin dependent quantum molecular dynamics (ImIQMD) model, pion emission in heavy-ion collisions in the region 1 A GeV is investigated systematically, in which the pion is considered to be mainly produced by the decay of resonances Delta(1232) and N*(1440). The in-medium dependence and Coulomb effects of pion production are included in the calculation. Total pion multiplicity and pi(-)/pi(+) yields are calculated for the reaction Au-197+(197) Au in central collisions for selected Skyrme parameters SkP, SLy6, Ska, SIII and compared with the measured data of the FOPI collaboration.