Triggering of cellulase biosynthesis by cellulose in Trichoderma reesei. Involvement of a constitutive, sophorose-inducible, glucose-inhibited beta-diglucoside permease

We prepared [U-14C]cellobiose by cultivating Acetobacter pasteurianus in the presence of [U-14C]glucose and hydrolyzing the [U-14C]cellulose formed with beta-glucosidase-free cellulase from Trichoderma reesei. This 14C-labeled cellobiose was used to investigate the presence of an uptake system for cellobiose in T. reesei. Evidence was obtained for the presence of a high affinity (Km for cellobiose 0.3 microM) but low activity (2.5 milliunits/mg fungal dry weight) cellobiose permease. The permease is formed constitutively, but higher levels are formed after addition of sophorose (glucosyl-beta-1,2-diglucoside), a reputed cellulase inducer. The permease appears to be specific for beta-diglucosides, as the uptake of [U-14C]cellobiose is inhibited by sophorose, gentiobiose (glucosyl-beta-1,3-glucoside), and cellobiose. Under these conditions, cellooligodextrines (n, 4-7; final concentration, 1 mM) are not inhibitors. Glucose, but no other monosaccharides, inhibits the permease. The hypersecretory mutant T. reesei RUT C-30 exhibits elevated permease activities, whereas in T. reesei QM 9979, a mutant strain defective in the induction of cellulases by cellulose or sophorose, strongly reduced permease activities were demonstrated. The results stress a hitherto not recognized point of control in the induction of cellulases by T. reesei at the level of uptake of cellulose oligosaccharides.     

Practical accuracy analysis of some existing effective channellength and series resistance extraction methods for MOSFET's

A method to analyze the accuracy of the extracted values for the channel length (L_eff) and series resistance (R_s) of MOSFET devices is presented. The analysis is based on a statistical argument being the variance σ of the extracted results. This variance is found to be a good measure for the accuracy of the particular extraction method used. It is shown that, in the case of deep submicron technologies, errors as large as 200 nm for ΔL can be made for these extraction methods depending on the process design and the process control. The use of a single transistor method is suggested as a possible solution to the low accuracy of the L-array methods     

Quasilinearized Regression

Estimation in nonlinear regression usually requires a considerable amount of computational work. If it is possible to linearize the original formulas, the linear regression is sometimes applied to transformed linear relations. The method of quasilinearized regression (first order approximation of nonlinear regression), comparable to linear regression, with respect to computational effort, is described in this paper. This method gives substantially better results than linear regression of linearized formula.     

On the impact of TiN film thickness variations on the effective work function of poly-Si/TiN/SiO/sub 2/ and poly-Si/TiN/HfSiON gate stacks

The impact of TiN film thickness variations on the effective work function (WF) of poly-Si/TiN/SiO/sub 2/ and poly-Si/TiN/HfSiON interfaces has been investigated. The electrical signatures of these gate stacks indicate that the concentration of Hf-Ti and Ti-Si bonds at the (poly-Si/TiN)/HfSiON and (poly-Si/TiN)/SiO/sub 2/ interface plays a significant role on the control of the gate stacks' WF. The density of these interfacial bonds and the related work function changes are correlated to the degree of nucleation of the TiN film on the dielectric.     

Role of endoproteolytic dibasic proprotein processing in maturation of secretory proteins in Trichoderma reesei

Cell extracts of Trichoderma reesei exhibited dibasic endopeptidase activity toward the carboxylic side of KR, RR, and PR sequences. This activity was stimulated by the presence of Ca2+ ions and localized in vesicles of low bouyant density; it therefore exhibited some similarity to yeast Kex2. Analytical chromatofocusing revealed a single peak of activity. The dibasic endopeptidase activity was strongly and irreversibly inhibited in vitro as well as in vivo by 1 mM p-amidinophenylmethylsulfonyl fluoride (pAPMSF) but not by PMSF at concentrations up to 5 mM. We therefore used pAPMSF to study the role of the dibasic endopeptidase in the secretion of protein by T. reesei. Secretion of xylanase I (proprotein processing sequence -R-R- downward arrow-R- downward arrow-A-) and xylanase II (-K-R- downward arrow-Q-) was strongly inhibited by 1 mM pAPMSF, and a larger, unprocessed enzyme form was detected intracellularly under these conditions. Secretion of cellobiohydrolase II (CBH II; -E-R- downward arrow-Q-) was only slightly inhibited by pAPMSF, and no accumulation of unprocessed precursors was detected. In contrast, secretion of CBH I (-R-A- downward arrow-Q-) was stimulated by pAPMSF addition, and a simultaneous decrease in the concentration of intracellular CBH I was detected. Similar experiments were also carried out with a single heterologous protein, ShBLE, the phleomycin-binding protein from Streptoalloteichus hindustanus, fused to a series of model proprotein-processing sequences downstream of the expression signals of the Aspergillus nidulans gpdA promoter. Consistent with the results obtained with homologous proteins, pAPMSF inhibited the secretion of ShBLE with fusions containing dibasic (RK and KR) target sequences, but it even stimulated secretion in fusions to LR, NHA, and EHA target sequences. Addition of 5 mM PMSF, a nonspecific inhibitor of serine protease, nonspecifically inhibited the secretion of heterologous proteins from fusions bearing the NHA and LR targets. These data point to the existence of different endoproteolytic proprotein processing enzymes in T. reesei and demonstrate that dibasic processing is obligatory for the secretion of the proproteins containing this target.     

Effective Work-Function Modulation by Aluminum-Ion Implantation for Metal-Gate Technology (Poly-Si/TiN/SiO2)

The impact of aluminum (Al) implantation into TiN/SiO₂ on the effective work function (EWF) of poly-Si/ TiN/SiO₂ is investigated. Al implanted at 5 keV with a dose of 5 times 10¹⁵ cm^-2 reduces the flatband voltage (V_FB) and the EWF of poly-Si/TiN/SiO₂ stack by ~150 mV compared with the unimplanted poly-Si/TiN/SiO₂ stack. This reduction of V_FB is found to be dose-dependent, which is correlated to the Al concentration at the TiN-SiO₂ interface as evidenced by secondary-ion-mass-spectrometry profiles. The interface dipole created due to the Al presence at the metal-dielectric interface is believed to contribute to the observed V_FB (or EWF) reduction (or increase). This technique for EWF modulation is promising for further threshold-voltage (V_t) tuning without any process complexities and is quite significant for planar and multiple gate field-effect transistors on fully depleted silicon on insulator.     

Hydrodynamische Modelluntersuchungen zum bodenblasenden Konverter

Bisherige Erkenntnisse. Modellähnlichkeit und Dimensionierung des Konverters. Versuchsanlage. Versuchsdurchführung am System Wasser/Luft. Umlaufgeschwindigkeit und Wellenhöhe in Abhängigkeit von Füllhöhe, Gasstrom, Düsenzahl, Düsenanordnung, Düsenquerschnitt, Düsenorientierung. Empfehlungen für optimale Blasbedingungen.