An FPGA based test bench for non-volatile memory testing
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non-volatile memory memory tester endurance testin↗
Engineering topics
Rao, V.
Publications and source records attributed to Rao, V..
Effects of gene deletion of the tissue inhibitor of the matrix metalloproteinase-type 1 (TIMP-1) on left ventricular geometry and function in mice
Alterations in the expression and activity of the matrix metalloproteinases (MMPs) and the tissue inhibitors of the MMPs (TIMPs) have been implicated in tissue remodeling in a number of disease states. One of the better characterized TIMPs, TIMP-1, has been shown to bind to active MMPs and to regulate the MMP activational process. The goal of this study was to determine whether deletion of the TIMP-1 gene in mice, which in turn would remove TIMP-1 expression in LV myocardium, would produce time-dependent effects on LV geometry and function. Age-matched sibling mice (129Sv) deficient in the TIMP-1 gene (TIMP-1 knock-out (TIMP-1 KO), n=10) and wild-type mice (n=10) underwent comparative echocardiographic studies at 1 and 4 months of age. LV catheterization studies were performed at 4 months and the LV harvested for histomorphometric studies. LV end-diastolic volume and mass increased (18+/-4 and 38+/-3%, respectively, P<0.05) at 4 months in the TIMP-1 KO group; a significant increase compared to wild-type controls (P<0.05). At 4 months, LV and end-diastolic wall stress was increased by over two-fold in the TIMP-1 KO compared to wild type (P<0.05). However, LV systolic pressure and ejection performance were unchanged in the two groups of mice. LV myocyte cross-sectional area was unchanged in the TIMP-1 KO mice compared to controls, but myocardial fibrillar collagen content was reduced. Changes in LV geometry occurred in TIMP-1 deficient mice and these results suggest that constitutive TIMP-1 expression participates in the maintenance of normal LV myocardial structure. Copyright 2000 Academic Press.
Non-NASA Center↗
Control of interface reactions in SIC/TI composites
The reaction between a 0.5 to 1.0 Al film and a thick Ti substrate to form TiAl3 occurs very rapidly on heating to 635 C and causes the Al to be confined to the surface region. After heating to 900 C Ti3Al is formed with little release of Al into alpha Ti. Further annealing at 900 C eventually causes the Ti3Al phase to decompose and a substantial amount of Al is released into alpha Ti. The interdiffusion coefficient for Al in alpha Ti at 900 C increases by less than one order of magnitude as Al is varied from 0 to 20 at %. These data were obtained from the (101) X-ray diffraction intensity band using polycrystalline samples. Improvements in the analysis of X-ray diffraction data for the determination of composition profiles are discussed.
Houska, C. R.↗
Determination of volume fraction in multiphase systems using incomplete pole figures
The determination of the volume fraction of a second phase in a multiphase sample by X-ray diffraction becomes more difficult if the diffracting planes have a preferred orientation. Lopata and Kula have described a method of treating this problem using complete pole figures for each of the phases. With some samples, it is not always possible or convenient to obtain data over the full hemisphere. Equations and an example are given which require X-ray data over a limited range of approximately 0 to 75 deg. This can be obtained by reflection without a specially cut sample or transmission data. A series of Legendre polynomials are fitted to data collected while spinning the sample about its normal. An extrapolation is made possible by introducing two conditions on the end points which must be satisfied if the extrapolation functions are to be valid.
Houska, C. R.↗