Processing of aluminum-graphite particulate metal matrix composites by advanced shear technology

Copyright @ 2009 ASM International. This paper was published in Journal of Materials Engineering and Performance 18(9) and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this paper for a fee or for commercial purposes, or modification of the content of this paper are prohibited.To extend the possibilities of using aluminum/graphite composites as structural materials, a novel process is developed. The conventional methods often produce agglomerated structures exhibiting lower strength and ductility. To overcome the cohesive force of the agglomerates, a melt conditioned high-pressure die casting (MC-HPDC) process innovatively adapts the well-established, high-shear dispersive mixing action of a twin screw mechanism. The distribution of particles and properties of composites are quantitatively evaluated. The adopted rheo process significantly improved the distribution of the reinforcement in the matrix with a strong interfacial bond between the two. A good combination of improved ultimate tensile strength (UTS) and tensile elongation (e) is obtained compared with composites produced by conventional processes.EPSR

Experimental determination of the permeability of engineering textiles: Benchmark II

In this second international permeability benchmark, the in-plane permeability values of a carbon fabric were studied by twelve research groups worldwide. One participant also investigated the deformation of the tested carbon fabric. The aim of this work was to obtain comparable results in order to make a step toward standardization of permeability measurements. Unidirectional injections were thus conducted to determine the unsaturated in-plane permeability tensor of the fabric. Procedures used by participants were specified in the guidelines defined for this benchmark. Participants were asked to use the same values for parameters such as fiber volume fraction, injection pressure and fluid viscosity to minimize sources of scatter. The comparison of the results from each participant was encouraging. The scatter between data obtained while respecting the guidelines was below 25%. However, a higher dispersion was observed when some parameters differed from the recommendations of this exercise.The authors are grateful to J.M. Beraud from Hexcel Fabrics for his support that made possible this exercise. The contributions of J.B. Alms, N.C. Correia, S. Advani, E. Ruiz and P.C.T. Goncalves to the preparation of the guidelines document and templates are acknowledged by the participants of this benchmark.Vernet, N.; Ruiz, E.; Advani, S.; Alms, JB.; Aubert, M.; Barburski, M.; Barari, B.... (2014). Experimental determination of the permeability of engineering textiles: Benchmark II. Composites Part A: Applied Science and Manufacturing. 61:172-184. doi:10.1016/j.compositesa.2014.02.010S1721846

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Cerebral blood flow velocity changes under nitrous oxide halothane anesthesia in patients with frontotemporal gliomas: A comparison of the normal and abnormal cerebral hemispheres

Background: Regional differences in vascular response to anesthetic agents in brain areas with and without tumors have not been investigated till now. The existence of such differences may influence the regional distribution of cerebral blood flow under anesthesia. Material and Methods: In 8 patients with frontotemporal gliomas, middle cerebral artery blood flow velocity (Vmca), pulsatality index (PI) and resistance index (RI) were determined in the normal and pathological cerebral hemispheres before and after stable nitrous oxide-halothane anesthesia. Results: During halothane anesthesia, there was an increase in Vmca both in the normal cerebral hemisphere (69 ± 11 to 100 ± 38 cm/s; P = 0.05) and the hemisphere with tumor (65 ± 17 to 83 ± 28 cm/s; P = 0.04). A significant decrease in the pulsatality index and the resistance index was also observed in both the hemispheres (P < 0.05). The percentage changes of Vmca,, PI and RI in both the hemispheres after anesthesia were not significantly different. Conclusions: In patients with cerebral tumors, nitrous oxide-halothane anesthesia causes comparable changes of cerebral blood flow velocities in the hemisphere with tumor and the normal hemisphere

Feasibility, safety and efficacy of percutaneus endoscopic gastrostomy on ventilated patients in ICU

An audit of 27 ventilated patients who underwent percutaneous endoscopic gastrostomy (PEG) in ICU revealed that this procedure could be safely performed in the ICU under local anesthesia. None of the patients had any hemodynamic or respiratory complications. All of them could be started on enteral feeds on the following day. PEG done in the ICU avoids the complications of transportation to the operation theater and general anesthesia

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Not AvailableParasitic infestations are frequently reported in brackishwater fish. Hence, prevention and control strategy is paramount for successful brackishwater aquaculture. Emamectin benzoate (EMB) is found to be an effective in-feed treatment for controlling several ecto-parasites in fish. The objective of this study was to understand the biosafety, withdrawal and efficacy of EMB for use in brackishwater reared Asian Seabass (Lates calcarifer) under tropical climate. Biosafety was evaluated at doses of 0, 50, 250 and 500 μg kg−1 of fish body weight (BW) day−1 for 21 days. EMB was administered per os through coated pellet feed. Gross, haematological and histopathological observations were made and found that there were no biologically significant adverse changes between control and treated groups. Withdrawal period was estimated with similar experiment with same doses but for seven consecutive days. Samples were collected on 0th, 7th, 14th, 21st and 28th day of post-medication for QTRAP 4000 LC-MS/MS analysis. The data showed that the level of EMB in whole fish treated with 50, 250 and 500 μg kg−1 of fish BW day−1 were 21.0 ± 0.0, 142.4 ± 0.1 and 209.7 ± 0.1 parts per billion (ppb) on 0th day of withdrawal, respectively. These values were found drastically decreased on 7th day of withdrawal and reached undetectable level by 28th day. For assessing the environmental safety, acute immobilization test was conducted using 24 h old daphnid. The EC50 and LC50 values in daphnids were 107 and 160 times higher than the the treatment dose, respectively. Efficacy was tested with the therapeutic dose on Asian Seabass fingerlings infested with naturally sea louse (Caligus minimus). Medicated pellet feed was fed at 4% BW day−1 divided equally between three feedings. Efficacy trial showed that there was significant improvement in survival (92.0 ± 2.3%; P < .01), reduction in parasitic load (P < .05), percent efficacy (76.2%) and haematological parameters (P < .01; P < .05) on and after fifth day of treatment. Based on the results, it was concluded that there was an adequate margin of safety and 100% efficacy associated with administering EMB-medicated feed to Asian Seabass fingerlings at the proposed therapeutic treatment regimen of 50 μg of EMB kg−1 fish BW day−1 for seven consecutive days.Not Availabl