A low noise charge sensitive preamplifier with switch control feedback resistance

In this paper, the design and analysis of a new low noise charge sensitive preamplifier for silicon strip, Si(Li), CdZnTe and CsI detectors etc. with switch control feedback resistance were described, the entire system to be built using the CMOS transistors. The circuit configuration of the CSP proposed in this paper can be adopted to develop CMOS-based Application Specific Integrated Circuit further for Front End Electronics of read-out system of nuclear physics, particle physics and astrophysics research, etc. This work is an implemented design that we succeed after a simulation to obtain a rise time less than 3ns, the output resistance less than 94 Omega and the linearity almost good.

a requirement traceability refinement method based on relevance feedback

Knowledge Systems Institute Graduate School

Temperature sensitivity of soil respiration is affected by prevailing climatic conditions and soil organic carbon content: A trans-China based case study

National Natural Science Foundation of China [30590381]; Knowledge Innovation Program of the Chinese Academy of Sciences [KZCX2YW-432]; International Partnership Project

Reducing H2S production by O-2 feedback control during large-scale sewage sludge composting

Hydrogen sulfide (H2S) production patterns and the influence of oxygen (O-2) concentration were studied based on a well operated composting plant. A real-time, online multi-gas detection system was applied to monitor the concentrations of H2S and O-2 in the pile during composting. The results indicate that H2S was mainly produced during the early stage of composting, especially during the first 40 h. Lack of available O-2 was the main reason for H2S production. Maintaining the O-2 concentration higher than 14% in the pile could reduce H2S production. This study suggests that shortening the interval between aeration or aerating continuously to maintain a high O-2 concentration in the pile was an effective strategy for restraining H2S production in sewage sludge composting. (C) 2010 Elsevier Ltd. All rights reserved.

Effect of the nucleating agent 1,3 : 2,4-di(3,4-dimethylbenzylidene) sorbitol on the gamma phase content of propylene/ethylene copolymer

The influence of the concentration of a nucleating agent (NA), namely 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol (DMDBS), on the gamma phase content in a propylene/ethylene copolymer was investigated by means of Differential Scanning Calorimetry (DSC), Wide-Angle X-ray Diffraction (WAXD), Small- Angle X-ray Scatter (SAXS) and Polarized Optical Microscopy (POM).

White light emission on amplified spontaneous emission with dye content controlled polymer system

White light emission from amplified spontaneous emission (ASE) was realized by optically pumping fluorescent dye 4-(dicy-anomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped semiconducting poly(9,9-dioctylfluorene) (PFO) polymer thin films. Two individual ASE peaks originating from DCJTB and PFO were observed by carefully controlling the DCJTB concentration in PFO. The studies of the ASE characteristics of DCJTB:PFO thin films lead to the conclusion that the DCJTB:PFO system with 0.3% w/w DCJTB dopant concentration in PFO showed the best ASE performance.

Low-threshold conjugated polymer distributed feedback lasers on InP substrate

We demonstrate a low threshold polymer solid state thin-film distributed feedback (DFB) laser on an InP substrate with the DFB structure. The used gain medium is conjugated polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV) doped polystyrene (PS) and formed by drop-coating method. The second order Bragg scattering region on the InP substrate gave rise to strong feedback, thus a lasing emission at 638.9nm with a line width of 1.2nm is realized when pumped by a 532nm frequency-doubled Nd: YAG pulsed laser. The devices show a laser threshold as low as 7 nJ/pulse.

Synthesis of Liquid Polybutadiene Having Desired 1,2-Vinyl Content with Co(naph)(2)-Al-2(C2H5)(3)Cl-3-P(OPh)(3) Catalyst System

Liquid polybutadiene with desirable 1,2-units content was synthesized by Co(naph)(2)-Al-2(C2H5)(3)Cl-3-P(OPh)(3) catalyst system. It was shown that liquid polybutadiene having adequate 1,2-unit content (vinvl =35%-40%) molecular weight(M-n = 700-3500), and acceptabele conversion(>= 55%) can synthesized after optimizing polymerization conditions.

A quantitative HPLC method for determining lactide content using hydrolytic kinetics

A new method for quantitative analysis of lactide has been developed by applying chemical kinetics to a HPLC system. The most important advance is its practical approach to the quantification of analytes that are unstable in the HPLC mobile phase. In HPLC analysis, anhydrous mobile phases cannot separate lactide from impurities, and only mixtures of water and organic solvent can achieve effective separation. By selecting conditions for testing and studying the kinetics of lactide hydrolysis, extensive experiments revealed that lactide degradation can be treated as a pseudo-first-order reaction under the given HPLC conditions, and lactide content or purity can be quantitatively determined. This method is practical for measuring the purity of the intermediate lactide in polylactic acid (PLA) production and the lactide content in PLA.

Influence of Zn content on the microstructure and mechanical properties of extruded Mg-5Y-4Gd-0.4Zr alloy

Microstructures and mechanical properties of the Mg-5Y-4Gd-xZn-0.4Zr alloys have been investigated. These results show that the Mg-5Y-4Gd-0.5Zn-0.4Zr alloy in the peak-aged condition exhibits the highest tensile strength, and the values of the ultimate tensile strength and yield tensile strength are 370 and 300 MPa, respectively. It is suggested that addition of 0.5% Zn has a great effect on age hardening response. The long periodic stacking structure has been found in these Zn-containing alloys, and the volume fraction of this phase increases with increasing Zn addition. This phase plays an important role in improvement of the mechanical properties, especially for the elongations. The beta' phase precipitates during the ageing process are responsible for the improvement of the mechanical properties of the alloys in the peak-aged condition.

Studies on the content variation of chemical constituents during the combination of ginseng with veratrum nigrum by ESI-MS and HPLC-ESI-MS

To study the content variation of ginsenosides and alkaloids during combination of ginseng with veratrum nigrum, the ginsenosides and alkaloids in the decoction of ginseng with veratrum nigrum were analyzed and compared by high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) and electrospray ionization-mass spectrometry (ESI-MS). In the compatible decoction, eight ginsenosides and eight alkaloids. were detected, and the contents of six ginsenosides were found to be reduced, on the contrary, the contents of six alkaloids were increased. During combination of ginseng with veratrum nigrum, the contents of ginsenosides were reduced and those of the toxic alkaloids were increased. From the chemical point of view, the traditional theory is right that ginseng and veratrum nigrum are incompatible with each other.

Spectrophotometric determination of water content in alcohol organic solvents

In this work, the absorption spectral characteristics and color-change reaction mechanism of cobalt(II) chloride(COCl2) in alcohol organic solvents has been investigated in the presence of water, and then the optimum conditions for determining the water content in the solvents were selected. Results indicated that the absorption spectra Of COCl2 in alcohols decreased with the increment of water content. At the maximum absorption wavelength of 656 nm, there were good linear relationships between the logarithm of the absorbance and the water content in organic solvents such as ethanol, n-propanol, iso-propanol and n-butanol with related coefficients in the range of 0.9996 similar to 0.9998. For determining water content in organic solvents, this method is simple, rapid, sensitive, reproducible and environmentally friendly. Furthermore, the linear range cannot restrict determination of the water content in organic solvents. This method had been applied to determine the water content in ethanol and n-butanol with satisfactory recovery of water in n-butanol between 98.41%-101.29%.