A Simple Circuit to Reduce the Input Capacitance of Microelectrode Amplifiers

There are several specialized applications which require amplifiers with very low input capacitance. Two field effect transistors (FET's) can be cascaded in a source follower configuration to drive the drain of the input FET. The cascaded source follower provides at least an order of magnitude decrease in input capacitance. The cascaded source follower can be added to existing amplifiers or incorporated into new amplifier design with relatively little difficulty.     

On the systematic evaluation of the fracture safety,particularly for pressure vessels

A systematic evaluation of the fracture safety particularly for pressure vessels is presented. It is a stepwise approach based on the conventional brittle fracture test methods (qualitative assessment using temperature criteria) as well as on the current fracture mechanics test methods (quantitative assessment using LEFM-EPFM). The important aspects in connection with the application of the quantitative assessment, e.g. material and fracture mechanics properties, specimen types, test and fracture mechanics analysis methods are discussed. Also results of a fracture mechanics test program for a reactor pressure vessel are shown and the importance and the difficulties to acquire component specific fracture mechanics properties are described.     

Endogenous vasopressin increases acute endotoxin shock-provoked gastrointestinal mucosal injury in the rat

Administration of a low dose of endotoxin (from Escherichia coli, 3 mg kg(-1), i.v.), which does not affect vascular permeability or blood pressure over 1 h, leads to the release of endogenous vasopressin and damage to the mucosal microvasculature. Thus, endogenous vasopressin could be involved in septic shock. In the present study, we investigated the role of endogenous vasopressin in gastrointestinal mucosal injury induced by acute endotoxin shock, which was generated in rats by administering a high dose of E. coli endotoxin (50 mg kg(-1), i.v.). Tissues were removed 15 min after endotoxin. The vasopressin V1 receptor antagonist, d[CH2]5Tyr[Me]arginine-vasopressin (0.2-1 microg kg(-1), i.v.), was injected 10 min before endotoxin. Monastral blue (30 mg kg(-1), i.v.), which stains damaged vasculature, was injected 10 min before autopsy. Endotoxin reduced systemic arterial blood pressure (from 115+/-5 to 42+/-4 mmHg), generated macroscopic and microvascular injury, and elevated plasma vasopressin levels (from 3.4+/-0.2 to 178+/-16 pg ml(-1)). The vasopressin V1 receptor antagonist reduced this macroscopic injury, and in the vasopressin-deficient Brattleboro rat a similar reduction of gastrointestinal mucosal damage was found. Substantial decreases in endotoxin-induced microvascular damage were observed in each tissue, e.g., the gastric Monastral blue staining was reduced by 47+/-3% and 96+/-3% (P < 0.01) after vasopressin V1 receptor antagonist treatment and in Brattleboro rats, respectively. Vasopressin, acting through its V1 receptors, thus appears to be involved in acute endotoxin shock-provoked gastrointestinal injury.     

Kinetic investigation of the reaction: CO+Cl2COCl2 over ZSM-5 zeolites with transition metal ions

The CO+Cl₂COCl₂ reaction was studied over a ZSM-5 zeolite (SiO₂/Al₂O₃ = = 80.0) containing transition metal ions. An Eley-Rideal type rate equation describes the observed rates with acceptable accuracy. The proposed mechanism takes into account the interaction of CO arriving from the gas phase with chemisorbed chlorine. I.r. spectra convincingly show the presence of a charged COCl⁺ species under reaction conditions.     

Determination of phosphorus-, copper-, and zinc-containing human brain proteins by LA-ICPMS and MALDI-FTICR-MS

Human brain proteins containing phosphorus, copper, and zinc were detected directly in protein spots in gels of a human brain sample after separation by two-dimensional gel electrophoresis using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). A powerful laser ablation system with cooled laser ablation chamber was coupled to a double-focusing sector field ICPMS. The separated protein spots in 2D gels were fast screened using the optimized microanalytical LA-ICPMS technique measured at medium mass resolution with a focused laser beam (wavelength, 213 nm; diameter of laser crater, 50 mum; and laser power density, 3 x 10(9) W cm(-2)) with respect to selected three essential elements. Of 176 protein spots in 2D gel from a human brain sample, phosphorus, copper, and zinc were detected in 31, 43, and 49 protein spots, respectively. For the first time, uranium as a naturally occurring radioactive element was found in 20 selected protein spots. The detection limits for P, S, Cu, Zn and U were determined in singular protein spots with 0.0013, 1.29, 0.029, 0.063, and 0.000 01 mg g(-1), respectively. A combination of LA-ICPMS with matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR-MS) was applied for the identification of selected protein spots from human brain protein separated by 2D gel electrophoresis. Combining MALDI-FTICR-MS for the structure analysis of metal- and phosphorus-containing human brain proteins with LA-ICPMS, the direct analysis of heteroelements on separated proteins in 2D gels can be performed. For quantification of analytical LA-ICPMS data, the number of sulfur atoms per protein (and following the sulfur concentration) determined by MALDI-FTICR-MS was used for internal standardization. From the known sulfur concentration in protein, the concentration of other heteroelements was calculated. In addition, the number of phosphorylation and the phosphorylation sites of phosphorylated proteins in the human brain sample detected by LA-ICPMS were determined by MALDI-FTICR-MS. This technique allows the study of posttranslational modifications in human brain proteins.     

Absorption and fluorescence spectroscopic study on complexation of Oxazine 1 Dye by calix[8]arenesulfonate

It has been established by combined absorption and fluorescence measurements that the cationic dye Oxazine 1 (OX) and the polyvalent anionic host calix[8]arenesulfonate (SCA8) form two complexes in simultaneous reactions: OX + SCA8 <--> OX.SCA8 (1), and OX.SCA8 + OX <--> OX(2).SCA8 (2). The equilibrium constants for the two reactions, as functions of the ionic strength (I), and the absorption and fluorescence spectra of the two complex species have been determined by a least-squares fitting method from the experimental data. The variations of the binding constants with the ionic strength could be described on the basis of Debye-Huckel theory. The equilibrium constants are large; their values extrapolated to I = 0 are K(1) = 5.5 x 10(6) M(-1) and K(2) = 4.4 x 10(5) M(-1). The fluorescence of OX undergoes a strong static quenching upon complexation. These results indicate that the complexes are held together by strong electrostatic forces. The addition of non-fluorescent tetramethylammonium chloride to OX-SCA8 mixtures results in a dramatic fluorescent enhancement, which demonstrates the potential applicability of this supramolecular system in fluorescence assays.