Variation of photon density distribution with system component within Intralipid emulsion

In order to recover distributions of optical parameters of underlining tissues utilizing backreflection optic tomography or diffuse reflectance spectroscopy for diagnostic proposes, trajectories of photons should be correctly estimated within tissue. Therefore, we have simulated the soft tissues with 1% Intralipid emulsion and have determined photon density distribution as a function of depth inside the Intralipid emulsions using laser light of wavelength 808 nm and two different detectors for different source-to-detector (S-D) separations. In this study we have shown difference in path distribution of the detected photons with two different detectors with different sensitivity for the same S-D separations in the Intralipid emulsions. This study has also shown that, the maximum penetration depth (MPD) of the detected photons is not an increasing function of the S-D separations. After reaching a maximum depth, the penetration depth decreases as S-D separation increases.     

Evaluation and correction of isotope ratio inaccuracy on inductively coupled plasma time-of-flight mass spectrometry

Isotope ratio measurements are found to have systematic bias when using the analog detection mode on an inductively coupled plasma time-of-flight (TOF) mass spectrometer. This bias is dependent upon the value of the ratio, the intensity of the signal, and the gain of the electron multiplier tube. The error should not appear if ion counting is employed instead of analog detection, although analog detection with time-of-flight has other distinct advantages. The cause of this isotope ratio inaccuracy is rooted in disproportionate recording of the analog signal because of the need to filter out noise by blocking analog signals below a threshold voltage. This attenuates smaller signals to a greater degree than larger signals. This variable “detection efficiency” causes a larger systematic error in the isotopic ratio as the isotopic abundances become more disparate. Ratios close to unity are generally accurate within the precision of the measurement. The use of an increased gain on the detector leads to improved ratio accuracy, but at the cost of decreased detector lifetime. This research presents a method of analyzing solutions using natural, known isotopic ratios to produce an efficiency correction curve. The average error of several isotope ratios for a 500 ng/mL solution of various elements with ratios between 3.4 and 10 was found to be 6.5% without correction, 3.0% with increased detector gain, 1.1% with efficiency correction and 0.6% with both increased gain and efficiency correction.     

Response of CZT drift-strip detector to X- and gamma rays

The drift-strip method for improving the energy response of a CdZnTe (CZT) detector to hard X- and gamma rays is discussed. Results for a 10×10×3 mm³ detector crystal demonstrate a remarkable improvement of the energy resolution. The full width at half maximum (FWHM) is 2.18 keV (3.6%), 2.45 keV (3.0%), 2.86 keV (0.8%) and 3.89 keV (0.6%) at 60, 80, 356 and 661 keV, respectively. The resolution is limited by electronic noise below 100 keV.     

某型探测器冷却组件的研制

介绍了一种探测器冷却组件的研制背景及设计方案,采用仿真的设计手段对组件的制冷系统进行了优化设计,实践证明其设计是成功的。同时说明了该型组件所具有的特点及应用场合。     

Fluorimetric detector and sensor for flow analysis made of light emitting diodes

Two compact optoelectronic fluorimetric devices operating according to the paired-emitter-detector-diode concept have been developed. The fluorimetric detector, fabricated of three light emitting diodes only, has been applied for the development of fluorimetric optosensor by further integration with sensing solid phase. In these investigations as a model analyte and as a model sensing layer useful for solid phase spectrometry, riboflavin and C18-silica have been chosen, respectively. Both developed analytical devices have been applied for non-stationary fluorimetric measurements performed under conditions of flow injection analysis. The presented flow-through detector and sensor operating under given flow conditions offer riboflavin determination in mg L⁻¹ and μg L⁻¹ ranges of concentration, respectively.     

CID型ICP光谱仪分析钢中稳定夹杂物的8种组分含量

本文探讨了以CID作检测器的全谱直读ICP光谱仪测定钢中稳定夹杂物化学组分的方法，并从试液制备、谱线选定、介质影响、方法检出限和精密度等方面进行了讨论，样品测定结果较好，满足了工作的需要。     

Exploratory growth in the Li2MoO4-MoO3 system for the next crystal generation of heat-scintillation cryogenic bolometers

In this work, we report on the Czochralski growth of Li₂MoO₄ crystals up to 230 g for heat-scintillation cryogenic bolometers likely to be used in astroparticle physics and neutron spectroscopy. Their transmission properties, radiopurity levels and detector behavior characterizations were carried out in order to validate the crystal growth process. The melting characteristics, the partition coefficients of a broad range of impurities, the thermal expansion (lattice parameters and dilatometry) and specific heat properties of the crystals were measured, over a broad temperature range for the last two, providing new data likely to be used in crystal growth process numerical simulations. We also investigated the crystal growth of Li₄Mo₅O₁₇ and determined its melting behavior and specific heat. The physical properties directly relevant to heat-scintillation cryogenic bolometers of Li₂MoO₄ and Li₄Mo₅O₁₇ are discussed in the context of the current materials developed for such applications.     

Indirect Fluorescent Visualization Of Aliphatic Amines

Abstract

2-Amino-5-methylbenzenesulfonic acid has been investigated as an indirect fluorescent visualization reagent in reversed phase ion pair chromatography. Aliphatic amines coelute as a negative peak which can be quantitated. Using a solvent of 1 mM 2-amino-5-methyl-benzenesulfonic acid, 0.05 M acetic acid, pH = 5.0 buffer and a C₁₈ column, butylamine was quantitated. The calibration curve was linear from 1.0 M to 2.5 × 10^?3M with a minimum detectable concentration of 1.01 × 10^?3M with a 20 μl injection loop.     

Combination of chromatographic and chemometric methods to study the interactions between DNA strands

This work describes the combination of size-exclusion chromatography and chemometric resolution methods to study the formation of complex DNA structures from individual strands. This combined procedure has been applied to two different experimental data. Firstly, the formation of an intermolecular Watson–Crick duplex structure formed by the individual unstructured strands. Secondly, the competition between the intermolecular Watson–Crick duplex and intramolecular quadruplex structures formed by two sequences found in the hTERT gene has been studied.     

HPLC测定西宁市鱼产品中的孔雀石绿与结晶紫

探索了西宁市鱼类产品中孔雀石绿与结晶紫的高效液相色谱荧光检测方法,方法在0.1ng/g-700ng/g范围内具有很好的线性关系,相关系数r为0.9998,定量限为0.5μg/kg.采用不同的鱼类产品进行验证,孔雀石绿的回收率在88％-94％之间,相对标准偏差(RSD)为3.15％-4.87％.结晶紫的回收率在94％-108％,相对标准偏差(RSD)为2.54％-4.05％.本法提取快捷、简便,适用于大批量的抽样检测,可检测出鱼类样品中痕量的孔雀石绿,为水产养殖提供可行的监测手段,为鱼类中孔雀石绿的检测标准的制定提供依据.