The efficacy of a test and ESS program

Statistical results of all the 1621 failure analyses, which cover a four‐year effort, are presented. The failure analyses were part of an elaborate test and ESS process of a high‐reliability system. Of the failure analyses, 97.5% identified the root cause. The classification of the failures by 11 root cause classes, including the test and ESS process itself is provided. The distribution of failure root causes detected during the various phases of the process is shown. Each test phase was analyzed according to the share of failures found and the fraction of failures that occurred during that phase. Applying a linear formula that summarizes the relative efficacy of each test phase compares the performances of the various phases. The term efficacy is used to describe the ability of a test phase to reveal failures without generating new problems. Copyright © 2002 John Wiley & Sons, Ltd.     

Free convection in porous media filled right-angle triangular enclosures

Steady-state free convection heat transfer in a right-angle triangular enclosure, whose vertical wall insulated and inclined and bottom walls are differentially heated, is performed in this study. The governing equations are obtained using Darcy model. In this study, the governing equations were solved by finite difference method and solution of algebraic equations was made via Successive Under Relaxation method. The effect of aspect ratios ranging from 0.25 to 1.0 and Rayleigh numbers 50 ≤ Ra ≤ 1000 is investigated as governing parameters on heat transfer and flow field. It is observed that heat transfer is increased with the decreasing of aspect ratio and multiple cells are formed at high Rayleigh numbers.     

Reversible Switch Memory Effect in Hydrogen‐Terminated Ultrananocrystalline Diamond

Innovative memory switch devices require reliable bistable conductance properties. It would be desirable if such bistable characteristics were available in robust solid state materials, such as diamond, which benefit from outstanding physical properties. A bistable current with reversible switching effect from surface transfer doped ultrananocrystalline diamond thin films measured by electron field emission is reported. This switching is manifested by the appearance of huge jumps in the current emission, up to four orders of magnitude, that occur at specific extracting electric field values. Persistent hysteresis is exhibited whenever the field is ramped down. It is proposed that these phenomena are the result of resonant‐tunneling through a double barrier junction composed of tetrahedral amorphous carbon (ta‐C)/nanodiamond/adsorbent/vacuum. This finding may pave the way for the realization of novel types of memory switch devices with unprecedented performance.     

Core Histones Are Constituents of the Perinuclear Theca of Murid Spermatozoa: An Assessment of Their Synthesis and Assembly during Spermiogenesis and Function after Gametic Fusion

The perinuclear theca (PT) of the eutherian sperm head is a cytoskeletal-like structure that houses proteins involved in important cellular processes during spermiogenesis and fertilization. Building upon our novel discovery of non-nuclear histones in the bovine PT, we sought to investigate whether this PT localization was a conserved feature of eutherian sperm. Employing cell fractionation, immunodetection, mass spectrometry, qPCR, and intracytoplasmic sperm injections (ICSI), we examined the localization, developmental origin, and functional potential of histones from the murid PT. Immunodetection localized histones to the post-acrosomal sheath (PAS) and the perforatorium (PERF) of the PT but showed an absence in the sperm nucleus. MS/MS analysis of selectively extracted PT histones indicated that predominately core histones (i.e., H3, H3.3, H2B, H2A, H2AX, and H4) populate the murid PT. These core histones appear to be de novo-synthesized in round spermatids and assembled via the manchette during spermatid elongation. Mouse ICSI results suggest that early embryonic development is delayed in the absence of PT-derived core histones. Here, we provide evidence that core histones are de novo-synthesized prior to PT assembly and deposited in PT sub-compartments for subsequent involvement in chromatin remodeling of the male pronucleus post-fertilization.     

Optical synthetic aperture radar

A method is proposed for increasing the resolution of an object and overcoming the diffraction limit of an optical system installed on top of a moving imaging system, such as an airborne platform or satellite. The resolution improvement is obtained via a two-step process. First, three low resolution differently defocused images are captured and the optical phase is retrieved using an improved iterative Gershberg–Saxton based algorithm. The phase retrieval allows numerical back propagation of the field to the aperture plane. Second, the imaging system is shifted and the first step is repeated. The obtained optical fields at the aperture plane are combined and a synthetically increased lens aperture is generated along the direction of movement, yielding higher imaging resolution. The method resembles a well-known approach from the microwave regime called the synthetic aperture radar in which the antenna size is synthetically increased along the platform propagation direction. The proposed method is demonstrated via Matlab simulation as well as through laboratory experiment.     

X-ray investigation of the solid solution Zn1−XCuXCr2S4 with spinel structure

The phase diagram of the quasibinary system of the semiconducting ZnCr₂S₄ and the metallic CuCr₂S₄ has been studied with the help of X-ray powder photographs of quenched samples and high temperature X-ray diffraction patterns. At ambient temperature the mutual solid solubility of both sulfide spinels is only small with x < 0.1 and > 0.9. But the interchangeability of ZnCr₂S₄ and CuCr₂S₄ increases with increasing temperature, and at temperatures above 630°C a complete series of mixed crystals is formed, which, however, cannot be quenched to room temperature without decomposition. The limited solid solubility of chalcide spinels containing copper is discussed in terms of size factor and valence state of the ions under investigation.     

Inhibition of cholesterol and fatty acid biosynthesis in liver enzymes and chicken hepatocytes by polar fractions of garlic

Different concentrations of polar fractions, methanol-soluble (MESF), or water-soluble (WASF), of 1–8% equivalent to fresh garlic paste were added to yellow corn-soybean based diets and fed to 5-week-old male broiler chickens for 3 weeks to measure the inhibition of hepatic β-hydroxy-β-methylglutaryl coenzyme A (HMG-CoA) reductase, cholesterol 7α-hydroxylase (7α-hydroxy) and fatty acid synthetase (FAS). Dose-related decreases in the activities of these enzymes were obtained. Decreases in serum total cholesterol and in low density lipoprotein (LDL) levels were also observed. There was no effect on the level of cholesterol in high density lipoprotein (HDL). The most effective dose for these decreases was found 0.54% (MESF) and 1.2% (WASF) equivalent to 6% of the fresh garlic. The inhibition of HMG-CoA reductase and FAS by 25–300 μm of MESF or WASF for 15 min was tested in vitro, in male and female chicken hepatocytes. Inhibitions of activity were dose-dependent and the degree of inhibition increased with duration of incubation (150 μg of MESF or WASF 5 to 60 min). Dietary supplementation of odorless WASF of garlic was found to be very effective in lowering the total and LDL cholesterol levels compared to control chickens. Cooperative investigation between the Agricultural Research Service, US Department of Agriculture, and College of Agriculture and Life Sciences, University of Wisconsin, Madison. A preliminary report of this work was presented at the 66th Annual Meeting of Federation of American Societies for Experimental Biology, New Orleans, LA, April 1982, Abs. 41∶554 (1982). Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the US Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.