A Comparison of Millimeter Wave and Eddy Current Detection of Surface Breaking Defects in Conducting Materials

The detection of surface breaking defects in conducting materials is an important aspect of nondestructive evaluation (NDE). Eddy current NDE methods have been used effectively for the detection of fatigue cracks and other surface breaking flaws in conducting materials [1], however, a detracting characteristic is that the eddy current transducer must be placed in close proximity to the test specimen. Since millimeter wave energy can propagate in air and does not require a couplant, millimeter wave NDE offers an alternative technique with the significant advantage of detection in a stand off mode of operation. Millimeter wave NDE has been shown to be effective at detecting small cracks [2–3], however, some methods under study require that the transducer be in close proximity with the specimen and thus suffer from the same disadvantages as eddy current techniques. This paper compares the detection capabilities of surface breaking flaws on conducting materials for millimeter wave NDE in the stand off mode and conventional eddy current NDE

A theoretical review of the operation of vibratory stress relief with particular reference to the stabilization of large-scale fabrications

Vibratory stress relief (VSR) is widely used on large welded fabrications to stabilize the structures so that they do not distort during further machining or during operational duty. The level of applied stress achieved during VSR on such structures is only 5–10 per cent of the yield stress. It is, therefore, not obvious how these applied loads come to modify the level of residual stress. It is suggested here that the reason for the success of VSR applied to large fabrications lies (a) in the origin of the residual stresses and (b) in the partial relief of these residual stresses by the initiation of the transformation of retained austenite particles (in the size range from 1 to 25 µm) by the movement of dislocations into positions that are favourable for the nucleation of martensite embryos. The shear deformation associated with the transformation of retained austenite into martensite will reduce the residual stress field to the point where the stability of the structure may be assured

Toxicity Evaluation of Silver Nanoparticle in the Kidneys of Wistar Rats

This study aimed to evaluate the nephrotoxic effects of silver nanoparticles (AgNPs) in Wistar rats using biochemical, oxidative stress and histopathological changes. Three groups of six rats were orally administered AgNPs once a day for 28 days with doses of 100, 500, 1000 mg/kg bodyweight. A control group was administered with deionized water. Blood and kidneys were collected 24 h after the last treatment following standard protocols. The activities of creatinine and blood urea nitrogen against AgNP-induced toxicity was determined in the serum by colorimetric microplate assay. Various activity levels of oxidative stress including, Catalase (CAT), Superoxide dismutase (SOD), Glutathione peroxidase (GPx) and Lipid hydroperoxides (LPO) were evaluated in the kidney tissue. Scanning (SEM) and transmission electron microscopy (TEM) was used to determine the histopathological evaluation of the kidneys. A significant increase in the levels of serum creatinine, blood urea nitrogen, CAT and LPO, were noted in AgNPs exposed rats compared to that in control rats. In contrast, decreased activities of SOD and GPx in a dose-dependent manner was observed in AgNPs exposed rats relative to control rats. SEM and TEM study showed significant morphological alterations in kidneys of AgNPs exposed rats in accordance with the biochemical markers. The results of the study demonstrate that AgNPs might be nephrotoxic, and its toxicity is mediated through oxidative stress mechanism

Studies Toward the Synthesis of Natural Product Scaffolds

Part 1: A Diels-Alder Approach to the Synthesis of Novel Analogues of the Natural Product Siamenol Due to the prevalence of biaryl motifs in natural product synthesis, the Carter research group has been exploring the utility of a Diels-Alder approach to biaryl synthesis. The Diels-Alder approach involves a [4+2] cycloaddition between an acetylene dienophile and a cyclohexadiene, followed by subsequent [4+2] cycloreversion. This method of biaryl synthesis introduces numerous advantages compared to the traditional metal-mediated biaryl synthesis procedures, including a lack of environmentally hazardous transition metals. The Diels-Alder approach has been used by the Carter group to synthesize the natural product siamenol. This carbazole alkaloid, isolated from the Murraya siamensis shrub, has been found to possess moderate activity in the inhibition of the human immunodeficiency virus (HIV). Previously, synthesis of siamenol had been based on the traditional metal-mediated cross-coupling approach. Based on this initial synthesis, a series of novel analogues of siamenol have been synthesized using the Diels-Alder approach to biaryl synthesis. This project focuses on the synthesis of four such analogues of siamenol. Part 2: Advances in Proline-Based Enantioselective Organocatalysis and its Application to a Novel Synthesis of the Natural Product Aconitine Organocatalysis, while not a novel concept, has made significant strides in the last decade with the advent of improved methods of enantioselective organocatalysis. Particular advances have been made in the use of proline-based organocatalysts in catalyzing such reactions as aldol, Mannich and Michael reactions in a highly enantioselective fashion. The Carter Group has utilized Hua Cat, a proline-based sulfonamide, to catalyze a series of [2.2.2] bicyclizations based on a Mannich reactionrelated mechanism. This approach has been utilized to form a precursor to the natural product aconitine, a known analgesic and antipyretic. The key [2.2.2] bicyclization step proceeded in a high-concentration (1.0 M), room temperature reaction that produced the target [2.2.2] octane with a 57% yield and 99% e.e. Further considerations toward the synthesis of aconitine are also discussed

Fabrics : Buying, Sewing, Laundering

This publication provides information on a variety of topics related to clothing and fabric. The main body of the publication is a table. The table is divided between natural and man-mad fibers. The natural fibers described are: cotton, linen, silk, and wool. The man-made fibers described are: rayon, nylon, orlon, dacron, acrilan, verel, acetate, dynel, vicara, fortisan, darlan, arnel and creslan. The various elements and characteristics of these fibers are divided between five rows titled, Characteristics, Fabric finishes possible, Uses, Sewing Tips, and Care