Probabilistic Simulation of Multi-Scale Composite Behavior

A methodology is developed to computationally assess the non-deterministic composite response at all composite scales (from micro to structural) due to the uncertainties in the constituent (fiber and matrix) properties, in the fabrication process and in structural variables (primitive variables). The methodology is computationally efficient for simulating the probability distributions of composite behavior, such as material properties, laminate and structural responses. Bi-products of the methodology are probabilistic sensitivities of the composite primitive variables. The methodology has been implemented into the computer codes PICAN (Probabilistic Integrated Composite ANalyzer) and IPACS (Integrated Probabilistic Assessment of Composite Structures). The accuracy and efficiency of this methodology are demonstrated by simulating the uncertainties in composite typical laminates and comparing the results with the Monte Carlo simulation method. Available experimental data of composite laminate behavior at all scales fall within the scatters predicted by PICAN. Multi-scaling is extended to simulate probabilistic thermo-mechanical fatigue and to simulate the probabilistic design of a composite redome in order to illustrate its versatility. Results show that probabilistic fatigue can be simulated for different temperature amplitudes and for different cyclic stress magnitudes. Results also show that laminate configurations can be selected to increase the redome reliability by several orders of magnitude without increasing the laminate thickness--a unique feature of structural composites. The old reference denotes that nothing fundamental has been done since that time

MATHEMATICAL MODELLING FOR MAGNETITE (CRUDE) REMOVAL FROM PRIMARY HEAT TRANSFER LOOP BY ION-EXCHANGE RESINS

The present research focuses to develop mathematical model for the removal of iron (magnetite) by ion-exchange resin from primary heat transfer loop of process industries. This mathematical model is based on operating capacities (that's provide more effective design as compared to loading capacity) from static laboratory tests. Results showed non-steady state distribution of external Fe2+ and limitations imposed on operating conditions, these conditions includes; loading and elution cycle time, flow rate, concentration of both loading and removal, volume of resin required. Number of generalized assumptions was made under shortcut modeling techniques to overcome the gap of theoretical and actual process design. KEY WORDS: Magnetite, Mathematical modeling, Ion-exchange resin, Operating capacity, Loading capacity Bull. Chem. Soc. Ethiop. 2009, 23(1), 129-133

Osteocyte isolation and culture methods.

The aim of this paper is to present several popular methods for in vitro culture of osteocytes and osteocyte cell lines. Osteocytes are located extremely suitably within the calcified bone matrix to sense mechanical signals, and are equipped with a multitude of molecular features that allow mechanosensing. However, osteocytes are more than specialized mechanosensing cells. Several signaling molecules are preferentially produced by osteocytes, and osteocytes hold a tight reign over osteoblast and osteoclast formation and activity, but also have a role as endocrine cell, communicating with muscles or organs as remote as the kidneys. In order to facilitate further research into this fascinating cell type, three protocols will be provided in this paper. The first protocol will be on the culture of mouse (early) osteocyte cell lines, the second on the isolation and culture of primary mouse bone cells, and the third on the culture of fully embedded human osteocytes within their own three-dimensional bone matrix

Salt stress induces genotype-specific DNA hypomethylation in ZmEXPB2 and ZmXET1 genes in maize

Maize, a moderately salt sensitive crop, first experiences osmotic stress that cause reduction in plant growth under salt stress. Fluctuation in cell wall elongation is one of the reasons of this reduction. Along with others, two important proteins expansins and xyloglucan endotransglucosylase are involved in regulation of cell wall elasticity, but the role of epigenetic mechanisms in regulating the cell wall related genes is still elusive. The present study was conducted with the aim of understanding the role of DNA methylation in regulating ZmEXPB2 and ZmXET1 genes. One salt sensitive and one salt tolerant maize cultivar was grown under hydroponic conditions at different levels of salt stress: T1 = 1 mM (control), T2 = 100 mM and T3 = 200 mM in three replicates. DNA and RNA were extracted from roots. After bisulfite treatment, Methyl Sensitive PCR was used for the DNA methylation analysis. It was revealed that fragment in promoter of ZmEXPB2 gene showed high level of DNA methylation under T1 in both varieties. Comparison of different stress treatments revealed decrease in DNA methylation with the increase in salt stress, significantly lower methylation appearing in T3. Similarly, the fragment in promoter of ZmXET1 gene also showed high levels of DNA methylation in T1. When different treatments were analysed, this gene significantly hypomethylated at T2 which continued to decrease in T3 in sensitive variety but remain stable in tolerant variety. Although, further in-depth analysis is required, our results demonstrate region-specific and genotype-specific methylation shift in the promoter of the ZmEXPB2 and ZmXET1 genes when subjected to the salt stress confirming the epigenetic regulation of these genes under stress conditions

Energy relaxation of an excited electron gas in quantum wires: many-body electron LO-phonon coupling

We theoretically study energy relaxation via LO-phonon emission in an excited one-dimensional electron gas confined in a GaAs quantum wire structure. We find that the inclusion of phonon renormalization effects in the theory extends the LO-phonon dominated loss regime down to substantially lower temperatures. We show that a simple plasmon-pole approximation works well for this problem, and discuss implications of our results for low temperature electron heating experiments in quantum wires.Comment: 10 pages, RevTex, 4 figures included. Also available at http://www-cmg.physics.umd.edu/~lzheng

Productivity and economic evaluation of Willow (Salix alba L.) based silvopastoral agroforestry system in Kashmir valley

Performance of two fodder crops namely, sorghum (Sorghum vulgare L.) and maize (Zea mays L.) was investigated with Willow (Salix alba L.) to evaluate productivity and economics of the silvopastoral agroforestry system in Kashmir valley. The experiment was laid out by planting two year old willows at 2.0m × 2.0m spacing and dividing the main plot into sub-plots of size 8m × 2m each with 5 replications in randomized block design (RDB). The intercrops of sorghum and maize were maintained at 20cm × 10 cm spacing and supplied with recommended doses of fertilizers. The economics of the willow plantation intercropped with fodder crops was compared with sole willow farming by the benefit-cost ratio and net present worth. The study revealed the differential behaviour of Salix alba regarding growth parameters (height, diameter and girth) by different intercrops and various fodder intercrops with respect to yield, above ground biomass, dry matter production and soil nutrient status (pH, organic carbon, available nitrogen, phosphorus and potassium). The willow based silvopastoral system was estimated to have benefit-cost ratio of 2.71 with maize and 2.68 with sorghum, while as sole crop the willows accrued a benefit-cost ratio of 2.66. The study is useful in discovering growth of willows, productivity of fodder crops and soil nutrient status under various silvopastoral agroforestry systems for maximizing economic gains. The findings envisaged evidences in favour of adopting willow based silvopastoral agroforestry instead of sole tree farming and the knowledge of interactions will be helpful in proper management of the system for sustained multiple productions

INVESTIGATION OF SINGLE-PASS/DOUBLE-PASS TECHNIQUES ON FRICTION STIR WELDING OF ALUMINIUM

The aim of this research is to study the effects of single-pass/ double-pass techniques on friction stir welding of aluminium. Two pieces of AA1100 with a thickness of 6.0 mm were friction stir welded using a CNC milling machine at rotational speeds of 1400 rpm, 1600 rpm and 1800 rpm respectively for single-pass and double-pass. Microstructure observations of the welded area were studied using an optical microscope. The specimens were tested by using a tensile test and Vickers hardness test to evaluate their mechanical properties. The results indicated that, at low rotational speed, defects such as ‘surface lack of fill’ and tunnels in the welded area contributed to a decrease in mechanical properties. Welded specimens using double-pass techniques show increasing values of tensile strength and hardness. From this investigation it is found that the best parameters of FSW welded aluminium AA1100 plate were those using double-pass techniques that produce mechanically sound joints with a hardness of 56.38 HV and 108 MPa strength at 1800 rpm compared to the single-pass technique. Friction stir welding, single-pass/ double-pass techniques, AA1100, microstructure, mechanical properties

Local Anaesthetic Flush Reduces Postoperative Pain and Haematoma Formation After Great Saphenous Vein Stripping—A Randomised Controlled Trial

AbstractObjectivesTo observe the effect of local anaesthetic flush through the great saphenous vein (GSV) tunnel on postoperative pain and haematoma formation following saphenous vein stripping operations.DesignProspective, double-blind, randomised, control trial.MethodsOne hundred patients were randomized to receive 20ml of local anaesthetic (bupivacaine 0.25%+adrenaline) or saline control flush through the GSV tunnel after stripping in a double-blind study. Visual analogue pain scores were used to measure postoperative pain daily for the 1st week, then at 3 weeks and 6 weeks. Patients were examined during the 1st, 3rd and 6th week for haematoma formation.ResultsIn the control group the median postoperative pain score was 4 (range 0–7) in the immediate postoperative period compared to a median of 1 (range 0–4) in the LA group (p<0.001). The median pain score on day-4 was 4 (range 1–6) (control) vs. 1 (range 0–3) (LA group) (p<0.001, Mann–Whitney Utest) and on day-6 it was 1 (range 0–5) (control) vs. 0 (range 0–5) (LA group) (p<0.001, Mann–Whitney). Twelve patients (24%) developed a haematoma in the GSV tunnel in the control group compared to three patients (6%) in the LA group (p=0.007).ConclusionFlushing of the GSV tunnel with bupivacaine plus adrenaline significantly reduces postoperative pain and haematoma formation in patients undergoing GSV stripping for varicose veins

Preparation and shelf life study of probiotic chocolate manufactured using Lactobacillus helveticus MTCC 5463

Current study was taken up to develop probiotic chocolate using indigenous probiotic culture L. helveticus MTCC 5463. Preliminary trials included optimization of culture inoculums and physical form (freeze-dried or frozen concentrated) of addition and finally optimized product was tested for probiotic viability, texture, and organoleptic parameters at regular intervals during storage at 10±2 °C for 30 days. Probiotic chocolates prepared via incorporation of freeze dried culture (3% w/w) had acceptable organoleptic quality and had a similar behaviour as the control chocolate during storage. However, the viability of probiotic bacteria (2.42×108 CFU g–1) was achieved only up to 15 days of storage at 10±2 °C