Thesis--Wisconsin. / Includes bibliographical references (leaves 53-54).

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1912. / The entire thesis text is included in file. Typescript. Illustrated by authors. Title from title screen of thesis/dissertation PDF file (viewed March 2, 2009) Includes bibliographical references (p. 2).

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Preclinical assessment procedures for wound dressings have been established with the clinical situation in mind, taking into account the important parameters of tensile mechanical properties, conformability to body surfaces, water vapour transmission rate (WVTR) and gaseous transmission (GTR) to 0₂ and CO₂. The mechanical (tensile) properties, the WVTR and the GTR's are measured by modified international standards. These are ASTM D882-81, ASTM E96-81 and BS 2782 respectively. The mechanical test is basically a uniaxial test taken to failure, from which the stress-strain characteristics and the ultimate strength of the material are determined. The WVTR is determined by measuring the rate of water loss from a container, covered with the dressing being evaluated, under controlled humidity conditions. Gaseous transmission, to both oxygen and carbon dioxide, is determined by the British Standard Vacuum technique. This method was used only for the assessment of the hydrophobic dressings. A liquid to gas technique was employed to assess the hydrophilic (water containing) dressings in respect to their transmission characteristics. Conformability is measured by an inflation test. At a pressure of 40 mmHg, a radius of curvature is calculated from the incremental change in height of the central point of a disc of the material under test. Viscoelastic tests were carried out to determine if any of the materials showed viscoelastic behaviour. These properties are of importance in the application of pretensioned dressings. A series of commercial and experimental materials were evaluated using the techniques described above. Some of the materials were assessed as a bi-laminate form, with a Mefix (adhesive bandage) top layer. Such a layer generally proved beneficial with regard to their possible clinical performance. Clinical studies were carried out for both in situ water vapour transmission and conformability. Such studies were carried out to provide a correlation between the laboratory and clinical situations. By providing an indication of possible clinical problems, preclinical assessment is of importance to clinicians and manufacturers.

Lapping pad will be worn during lapping process. Therefore, the quality of the work piece and the material removal ability will be lower. First, in this paper, it propose a intermittently nickel-electroplating lap-ping pad in lapping process : At first, plate a layer of nickel on copper plate and used it to be lapping pad. Replate the lapping pad to restore the working ability when the working ability of lapping pad decreased be-cause of wear. Secondary, it propose another restore method : composite electroplating on grinder in process. When grinding by using Ni-SiC composite coating pad, it is used to restore the pad by Ni-SiC composite electroplating at the same time. At first, the influence of load and rotation speed on mate-rial removal are investigated in this study. It is found that the material removal increased as the rotation speed of lapping pad and load increased. It is also found that the roughness of sin-tering SiC decreased as the load increased at a constant rotational speed. And at constant load , the influence of rotation speed on roughness of sintering SiC is unapparent. The ability decay of material removal of lap-ping pad is as time as go by. It can complete restore the wore lap-ping pad to unwear state by replating 15 minutes with 2.5 cur-rent density. The restored pad¡¦s behavior of material removal and roughness is the same as a new one¡¦s. The material removal of sintering SiC of composite electro-plating on grinder in process by using Ni-SiC composite coating is bigger than the material removal of sintering SiC of lapping by nickel-electroplating lapping pad. The material removal increase to 1.7 ~ 3.8 times in 90 minutes at the same load and rotation speed. And the material removal and time are linearly depend. It is investigated that the working ability of grinding disk can be maintain constant. It is also found that the material removal increased as the rotation speed of lapping pad and load in-creased.

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