History of the “Detector Materials Engineering” Crystal Growth Process for Bulk Hg1−x Cd x Te

This paper reviews the history and technology of a bulk Hg_1?x Cd _x Te crystal growth process that was developed in the early 1980s at Honeywell Electro-Optics Division (presently BAE Systems, Electronic Solutions). The crystal growth process name, DME, was an acronym for the department name: Detector Materials Engineering. This was an accelerated crucible rotation technique (ACRT) vertical traveling heater method growth process. Crystal growth occurred in the pseudobinary Hg_1?x Cd _x Te system. ACRT mixing allowed the lower-density, higher-x-value Hg_1?x Cd _x Te growth nutrient in the upper region of the ampoule to replenish the depleted melt and allowed the growth of constant-x-value, higher-density Hg_1?x Cd _x Te. The material grown by this research and production growth process yielded single crystals that had improved purity, compositional uniformity, precipitate density, and reproducibility in comparison with solid-state recrystallization and other bulk Hg_1?x Cd _x Te growth techniques. Radial and longitudinal nonuniformities in x-value for Hg_1?x Cd _x Te were reduced to <0.0008/cm. The net electrically active background impurities did not exceed 1 × 10¹⁴ cm^?3. Electron mobilities in excess of 1.5 × 10⁶ cm²/V-s were observed at 77 K. Structural defects of less than 10⁴ cm^?2 were measured. Te precipitates were not observed. As a result of these material improvements, long-wavelength infrared (LWIR) photoconductive devices fabricated from DME material had highly desired performance characteristics.     

The transversal imager: a photonic neurochip with programmablesynaptic weights

A photonic neural processor implemented in NMOS/CCD integrated circuit technology is described. The processor performs outer-product processing utilizing optical input of the synaptic weights and electrical input of the state vector, or, visa versa. The performance of the 32-neuron, 1024-synapse processor is presented.     

Impurity study of CdZnTe substrates used for LPE HgCdTe

Impurites were tracked from raw material purification through to CdZnTe processing in an effort to identify the sources of elements which impact on IR photodetector performance. Chemical analyses by GDMS and ZCGFAA effectively showed the levels of impurities introduced into CdZnTe substrate material from the manufacturing processes. A new purification process (ISDZR) for raw materials was developed, resulting in improved CdZnTe substrate purity. Substrate CU contamination was found to have detrimental effects on LPE layer and device electrical properties for lightly doped HgCdTe.     

四边形钢塔结构动力反应研究

本文采用了不同的力学模型及计算方法对四边形钢塔结构的动力特性进行了分析:(1)杆系-层间模型,振型分解法计算;(2)空间杆系模型,振型分解法计算;(3)杆系-层间模型,直接动力法计算。为了验证计算结果的可靠性,又用两种方法进行了检验;(1)激振法,(2)脉动法,其中又分为光线记录,人工分析数据和磁带记录,数据处理机分析数据。文中并对三种计算方法和二种试验方法进行了比较,供对类似结构进行计算或试验时参考。     

A comparison of techniques for nondestructive composition measurements in CdZnTe substrates

We report an overview and a comparison of nondestructive optical techniques for determining alloy composition x in Cd_1-xZn_xTe substrates for HgCdTe epitaxy. The methods for single-point measurements include a new x-ray diffraction technique for precision lattice parameter measurements using a standard highresolution diffractometer, room-temperature photoreflectance, and low-temperature photoluminescence. We compare measurements on the same set of samples by all three techniques. Comparisons of precision and accuracy, with a discussion of the strengths and weaknesses of different techniques, are presented. In addition, a new photoluminescence excitation technique for full-wafer imaging of composition variations is described.     

输电铁塔T型缝超声波探伤

本文介绍了输电线路钢管塔T字型焊缝的主要缺陷及其超声波回波特征,提出了T字型焊缝三种超声波探伤方法,说明了探伤工艺对保证产品质量的重要性。     

Relationships between perceptual responses and accident patterns in children: a pilot study

Many studies have been done to define factors related to accident tendencies in children, but few related these tendencies to developmental lags in visual perception. This pilot study explored the possibility that such a relationship exists. Twelve Caucasian females from similar socioeconomic backgrounds and age ranges were administered the Frostig Developmental Test of Visual Perception. Performance on the perceptual test was compared to accident frequency levels for each child to determine whether or not a correlation between visual perceptual performance and accident frequency existed. Although statistically significant results were not obtained, the need for more definite research related to spatial relations, position in space, and figure ground perception was demonstrated.     

Acid-Sphingomyelinase Triggered Fluorescently Labeled Sphingomyelin Containing Liposomes in Tumor Diagnosis after Radiation-Induced Stress

In liposomal delivery, a big question is how to release the loaded material into the correct place. Here, we will test the targeting and release abilities of our sphingomyelin-consisting liposome. A change in release parameters can be observed when sphingomyelin-containing liposome is treated with sphingomyelinase enzyme. Sphingomyelinase is known to be endogenously released from the different cells in stress situations. We assume the effective enzyme treatment will weaken the liposome making it also leakier. To test the release abilities of the SM-liposome, we developed several fluorescence-based experiments. In in vitro studies, we used molecular quenching to study the sphingomyelinase enzyme-based release from the liposomes. We could show that the enzyme treatment releases loaded fluorescent markers from sphingomyelin-containing liposomes. Moreover, the release correlated with used enzymatic activities. We studied whether the stress-related enzyme expression is increased if the cells are treated with radiation as a stress inducer. It appeared that the radiation caused increased enzymatic activity. We studied our liposomes’ biodistribution in the animal tumor model when the tumor was under radiation stress. Increased targeting of the fluorescent marker loaded to our liposomes could be found on the site of cancer. The liposomal targeting in vivo could be improved by radiation. Based on our studies, we propose sphingomyelin-containing liposomes can be used as a controlled release system sensitive to cell stress.     

Thrombophilia and Pregnancy Complications

There is a paucity of strong evidence associated with adverse pregnancy outcomes and thrombophilia in pregnancy. These problems include both early (recurrent miscarriage) and late placental vascular-mediated problems (fetal loss, pre-eclampsia, placental abruption and intra-uterine growth restriction). Due to poor quality case-control and cohort study designs, there is often an increase in the relative risk of these complications associated with thrombophilia, particularly recurrent early pregnancy loss, late fetal loss and pre-eclampsia, but the absolute risk remains very small. It appears that low-molecular weight heparin has other benefits on the placental vascular system besides its anticoagulant properties. Its use is in the context of antiphospholipid syndrome and recurrent pregnancy loss and also in women with implantation failure to improve live birth rates. There is currently no role for low-molecular weight heparin to prevent late placental-mediated complications in patients with inherited thrombophilia and this may be due to small patient numbers in the studies involved in summarising the evidence. There is potential for low-molecular weight heparin to improve pregnancy outcomes in women with prior severe vascular complications of pregnancy such as early-onset intra-uterine growth restriction and pre-eclampsia but further high quality randomised controlled trials are required to answer this question.