Experimental and numerical investigation on micro deep drawing process of stainless steel 304 foil using flexible tools

Flexible forming technology provides significant application potential in various areas of manufacturing, particularly at a miniaturized level. Simplicity, versatility of process and feasibility of prototyping makes forming techniques by using flexible tools suitable for micro sheet metal forming. This paper reports the results of FE simulation and experimental research on micro deep drawing processes of stainless steel 304 sheets utilising a flexible die. The study presents a novel technique in which an initial gap (positive or negative) is adopted between an adjustment ring and a blank holder employed in the developed forming system. The blank holder is moveable part and supported by a particular spring that provides the required holding force. The forming parameters (anisotropy of SS 304 material, initial gap, friction conditions at various contact interfaces and initial sheet thickness) related with the forming process are in details investigated. The FE models are built using the commercial code Abaqus/Standard. The numerical predictions reveal the capability of the proposed technique on producing micro metallic cups with high quality and large aspect ratio. To verify these results, number of micro deep drawing experiments is conducted using a special set up developed for this purpose. As providing a fundamental understanding is required for the commercial development of this novel forming technique, hence the optimization of the initial gap in accordance with each sheet thickness, thickness distribution and punch force/stroke relationship are detected

CORRELATION BETWEEN NEURAL RESPONSE TELEMETRY (NRT) MESUREMENT LEVEL AND BEHAVIORL (T-LEVEL AND C-LEVEL) IN PRELINGUAL COCHLEAR IMPLANT PATIENTS

 Objectives: To study the correlation between Neural Response Telemetry (NRT) measurement level and behavioral (Threshold level and Comfort level) in pre lingual cochlear implant patients age between 2 -10 years old at one and three months post implant. Methods: A cross sectional study conducted at University Kebangsaan Malaysia Medical Center from September 2010 to January 2012. Total numbers of hundred patients were involved in this study.All recipients implanted with Nucleus 24 cochlear implant and had full insertion and normal activation of the electrode array. Comparison between intra-operative NRT measurement level and behavioral (T-level and C-level) in cochlear implant patients at one month and three months post implantation were obtained respectively. Results: This study showed the intra-operative NRT levels were seen to fall between the T and C levels in one and three months respectively. There was also a positive correlation between NRT value measurements and both T and C value measurements in both one and three months (p value 0.01). There is a fair strength of the linear relationship between NRT and behavioral level in both one and three month post implant as shown by the r value (0.4 at one month, 0.2 at three months) Conclusion: It is useful to use the NRT values to predict the behavioral T and C values in prelingual children and an additional tool for the mapping. Key words: Neural Response Telemetry (NRT); Threshold level; Comfort level; Nucleus 24 cochlear implant.

A unit organization on the topic: history of the Arabs.

Thesis (M.A.)--Boston Universit

IN VITRO ANTIPLATELET ACTIVITY OF AN ISOFLAVANONE ISOLATED FROM METHANOLIC EXTRACT OF EMBLICA OFFICINALIS FRUITS

Objective: In this study, we aimed to isolate a polyphenolic compound from a polyphenolic-rich fraction from Emblica officinalis fruits and also study its effect on adenosine diphosphate (ADP) and collagen-induced in vitro platelet aggregation. Methods: The polyphenolic-rich fraction was prepared by 80% methanolic extraction. The residue was extracted successively with hexane, benzene, ethyl acetate and n-butanol. Ethyl acetate residue was selected for column chromatography because of its high polyphenolic content. It was subjected to repeated column chromatography of series with different eluents of increasing polarity. A brown amorphous powder was obtained from ethyl acetate: methanol (7:3) fraction. This sample was subjected to UV-visible spectrum, IR spectrum, 1H NMR, 13C NMR and electrospray mass spectrum (ES-MS) studies for its structural elucidation. Results: A compound, 5, 7, 4'-trihydroxy 3'-methoxy isoflavanone was identified from polyphenolic rich ethyl acetate: methanol (7:3) fraction separated from the 80% methanolic extract of Embica officinalis fruits by repeated column chromatography. Yield of the compound was 421.05 mg/kg. This compound exhibited antiplatelet activity well comparable with that of quercetin. Conclusion: The present study proved that the isolated compound 5, 7, 4'-trihydroxy 3'-methoxy isoflavanone exerts a significant inhibitory activity on ADP and collagen-induced in vitro platelet aggregation, which can be considered as an effective remedy for alleviating complications of cardiovascular diseases

Resistivity network and structural model of the oxide cathode for CRT application

In this paper, the electrical properties of oxide cathode and oxide cathode plus, supplied by LG Philips Displays, have been investigated in relation to different cathode activation regimes and methods. Oxide cathode activation treatment for different durations has been investigated. The formations of the compounds associated to the diffusion of reducing elements (Mg, Al, and W) to the Ni cap surface of oxide cathode were studied by a new suggestion method. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) was used as analytical techniques. Al, W, and Mg doping elements take place during heating to 1080 K (Ni-Brightness) under a rich controlled Ba–SrO atmosphere through an acceleration life test. The chemical transport of these elements was occurred mainly by the Ni cap grain boundary mechanism with significant pile-up of Mg compounds. Al and W show a superficial concentrations and distribution. A new structural and resistivity network model of oxide cathode plus are suggested. The new structural model shows a number of metallic and metallic oxide pathways are exist at the interface or extended through the oxide coating. The effective values of the resistances and the type of the equivalent circuit in the resistivity network model are temperature and activation time dependent.</p