Microstructure and Crystallographic Texture of Aluminium Composite

The objective of the present work is to study the hot deformation behaviour of Al alloy-SiC Composites and to analyze the microstructure and crystallographic texture. Dispersing finer size hard particles in Al alloys restricted the flow of grains and tends to alter the texture. Al composites were homogenized and subjected to compression test using universal testing machine at various strain rates and temperatures. The deformed microstructure was studied under microscope paying particular emphasis to understand the mechanism of material flow. The crystallographic texture of the deformed samples was found out using x-ray diffactometer. The results depict that Al composites can safely be deformed at 400 oC and at 0.01 /s strain rate and the microstructure shows dynamic recrystallization as the predominant mechanism of material flow.  It was also observed that at higher strain rate (10/s) of deformation, the interface decohesion between the metallic matrix and ceramic phase was observed.  Adiabatic shear bands (localized flow) were observed when the materials deformed at room temperature (30 oC) and at strain rate of 0.01/s.  The texture measurement of Al composites, at the safe region, shows the components of (011) [100], (001) [1-10], (010) [101].  This study indicated that Goss and cube texture are favorable for the easy deformation of Al composite

Relaxation of thermo-remanent magnetization in Fe-Cr GMR multilayers

The time decay of the thermo-remanent magnetization (TRM) in Fe-Cr giant magnetoresistive (GMR) multilayers has been investigated. The magnetization in these multilayers relaxes as a function of time after being cooled in a small magnetic field of 100 Oe to a low temperature and then the magnetic field is switched off. Low-field ($<$ 500 Oe) magnetization studies of these samples have shown hysteresis. This spin-glass-like behavior may originate from structural imperfections at the interfaces and in the bulk. We find that the magnetization relaxation is logarithmic. Here the magnetic viscosity is found to increase first with increasing temperature, then it reaches a maximum around T$_g$, and then it decreases with increasing temperature. This behavior is different from that of conventional spin glasses where the logarithmic creep rate is observed to increase with temperature. Power law also gives good fits and it is better than the logarithmic fit at higher temperatures. The dynamical effects of these multilayers are related to the relaxation of thermally blocked superparamagnetic grains and magnetic domains in the film layers.Comment: 19 page

Modeling the effects of insecticides and external efforts on crop production

In this paper a nonlinear mathematical model is proposed and analyzed to understand the effects of insects, insecticides and external efforts on the agricultural crop productions. In the modeling process, we have assumed that crops grow logistically and decrease due to insects, which are wholly dependent on crops. Insecticides and external efforts are applied to control the insect population and enhance the crop production, respectively. The external efforts affect the intrinsic growth rate and carrying capacity of crop production. The feasibility of equilibria and their stability properties are discussed. We have identified the key parameters for the formulation of effective control strategies necessary to combat the insect population and increase the crop production using the approach of global sensitivity analysis. Numerical simulation is performed, which supports the analytical findings. It is shown that periodic oscillations arise through Hopf bifurcation as spraying rate of insecticides decreases. Our findings suggest that to gain the desired crop production, the rate of spraying and the quality of insecticides with proper use of external efforts are much important

Effect of fertigation on available soil micro-nutrient under Kinnow Mandarin

A field experiment was conducted at Division of Fruit and Horticultural Technology, Indian Agricultural Research Institute (IARI), on 5-year-old plants at Todapur Orchard, IARI, New Delhi, during 2010-2011, to study the effect of fertigation on nutrient distribution pattern under Kinnow mandarin. Standard dose of fertilizers were 600g of N, 300g of P, and 400g of K per tree per year, scheduled in three splits during the period of February (300g N, 75g P and 100g K), April (150g N, 112.5g P and 150g K) and August (150g N, 112.5g P and 150g K) respectively. The soil nutrient was measured at the start and end of the experiment in February 2010 and January 2011 at three depths, viz. 0-15, 15- 30 and 30- 60 cm corresponding to two radial distances (50 and 100 cm) for different experimental treatments. The highest amount of soil iron at the end of experiment was observed in T6 having 3.98 ppm, followed by 3.78 ppm and 3.72 ppm at three different depths viz: 0-15, 15-30 and 30- 60 cm respectively at 50 cm distance whereas 3.56 ppm followed by 3.49 ppm and 3.32 were found at 100 cm distance away from the tree. T6recorded the highest amount of available copper in soil having 2.76 ppm followed by 2.73 ppm and 2.67 ppm from 0-15, 15-30 and 30- 60 cm depths respectively at the distance of 50 cm while, 2.68 ppm, 2.65 ppm and 2.61 ppm from 0-15, 15-30 and 30- 60 cm depths respectively at 100 cm away from the tree. T8 recorded the highest amount of soil zinc at the end of experiment, 2.59 ppm, 2.50 ppm and 2.20 ppm from 0-15, 15-30 and 30- 60 cm depths respectively from the distance of 50 cm and 2.31 ppm, 2.20 ppm and 1.74 ppm from 0-15, 15-30 and 30- 60 cm depths respectively away from the tree. The highest amount of soil manganese was recorded in T8 at the end of experiment. From 0-15, 15-30 and 30- 60 cm depths respectively 28.38 ppm followed by 24.84 ppm and 21.09 ppm at a distance of 50 cm while 29.88 ppm, 22.40 ppm and 17.43 ppm were observed at 0-15, 15-30 and 30- 60 cm depths respectively away from the tree. Fertigation resulted in increase in concentrationsof micro- nutrients near the zone of active roots (0-15 and 15-30 cm depths), exhibiting a radial decrease with increasing horizontal distance from the point of application, i.e. higher at 50 cmand lower at 100 cm distance from the trunk. It was recommended that fertigation with 75 per cent N and 100 per cent P &amp; K (450 g N, 300g P and 400 g K) can be recommended for application in three splits during February (225N:75P:100K), Apri1(112.5N: 112.5P: 150 K) and August (112.5N: 112.5P: 150 K) for young Kinnow orchards.Keywords: Kinnow, fertigation, micronutrient, depth, distanc

Interleukin-7 deficiency in rheumatoid arthritis: consequences for therapy-induced lymphopenia

We previously demonstrated prolonged, profound CD4+ T-lymphopenia in rheumatoid arthritis (RA) patients following lymphocyte-depleting therapy. Poor reconstitution could result either from reduced de novo T-cell production through the thymus or from poor peripheral expansion of residual T-cells. Interleukin-7 (IL-7) is known to stimulate the thymus to produce new T-cells and to allow circulating mature T-cells to expand, thereby playing a critical role in T-cell homeostasis. In the present study we demonstrated reduced levels of circulating IL-7 in a cross-section of RA patients. IL-7 production by bone marrow stromal cell cultures was also compromised in RA. To investigate whether such an IL-7 deficiency could account for the prolonged lymphopenia observed in RA following therapeutic lymphodepletion, we compared RA patients and patients with solid cancers treated with high-dose chemotherapy and autologous progenitor cell rescue. Chemotherapy rendered all patients similarly lymphopenic, but this was sustained in RA patients at 12 months, as compared with the reconstitution that occurred in cancer patients by 3–4 months. Both cohorts produced naïve T-cells containing T-cell receptor excision circles. The main distinguishing feature between the groups was a failure to expand peripheral T-cells in RA, particularly memory cells during the first 3 months after treatment. Most importantly, there was no increase in serum IL-7 levels in RA, as compared with a fourfold rise in non-RA control individuals at the time of lymphopenia. Our data therefore suggest that RA patients are relatively IL-7 deficient and that this deficiency is likely to be an important contributing factor to poor early T-cell reconstitution in RA following therapeutic lymphodepletion. Furthermore, in RA patients with stable, well controlled disease, IL-7 levels were positively correlated with the T-cell receptor excision circle content of CD4+ T-cells, demonstrating a direct effect of IL-7 on thymic activity in this cohort

A Conceptual Framework for Analyzing the Use of Context in Groupware

Abstract. This article presents a conceptual framework for the identification and classification of contextual elements included in groupware applications. Contextual elements store information that helps group members to characterize and to understand the interaction and its associate information. The conceptual framework can be used not only to guide the development of new groupware applications but also to analyze existing groupware. We illustrate the use of the framework in the analysis of three groupware tools.

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