Mechanical evaluation and FE modeling of composite sandwich panels

Most sandwich structures are defined using a three-layer type of construction, two thin layers and a thick core layer. Typically, the thickness ratio of core to face sheet is in the range of 10 to 15. For this study, end grain balsa was used as a core material (thickness ∼3 in.) and Fiber Reinforced Polymer Composite (FRP thickness ∼0.25 in.) was used as face sheet material.;The objective of this research was to develop a modeling approach to predict response of composite sandwich panels under static bending conditions. Different model including 2D and 3D solid with isotropic and orthotropic material properties were attempted in advanced Finite Element (FE) software MSC.NASTRAN. Comparison of FE model predictions with experimental data on sandwich panel mechanical properties helped in establishing appropriate modeling approach. FEA has been carried out both the bench and full scale panel levels. The effects of different material properties and panel profiles (with caps and w/o caps) were investigated. Finally, the FEA was further extended to predict response of jointed FRP sandwich panels. Proposed modeling has been proved to give reasonably accurate prediction for composite sandwich panels under the mentioned scenarios.;Another objective of this study was to evaluate mechanical and physical properties of Carbon FRP composites including both laminates and sandwich panels. CFRP sandwich panels of 0.25&inches; thick face sheets sandwiching balsa core were produced by BRP Inc., while additional laminates were manufactured either by compression molding (CFC-WVU lab) or Resin Infusion process (Fiber-Tech.) with varying resin system, fabric architecture and 3D stitched fabric. Mechanical property evaluation of composite material was carried out on both the coupon and panel levels under bending, tension etc. Effect of different process parameters, material structure and resin on composite properties was discussed. Microstructure study of composite specimens was carried out in order to analyze fiber-matrix adhesion and void content which in turn affect the strength of FRP composites

Study of the Effect of Surface Modification and Sulfur Impurities in Syngas on the Fischer-Tropsch Performance of Cobalt Catalysts

The effect of surface modification of the silica support on the Fischer-Tropsch (FT) activity and the selectivity of cobalt catalyst were studied. The catalysts were characterized by N2- physisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction (TPR) and hydrogen chemisorption. FT was carried out in a fixed-bed reactor at 230 °C, 20 bar and 9000 sccm/h/gcat, using syngas with H2 /CO = 2.0. Surface modification with chelating agents (CAs), i.e., nitrilotriacetic acid (NTA) and ethylenediaminetetracetic acid (EDTA), results in a smaller crystallite size of cobalt oxides after the calcination. In addition, the CA-modified catalysts contain well-dispersed cobalt oxides and higher number of catalytic sites on the surface. The CO conversions and the hydrocarbon yields, i.e., gC/Kgcat/h, are notably higher for the CA-modified catalysts at different operating temperatures. The structure-activity relationships based on the findings confirm the advantage of CA modification of the support during catalyst synthesis. In the next step, catalysts were subjected to poisoning by 10 and 50 ppm sulfur in the syngas. At both the concentrations, the sulfur is noted to adsorb irreversibly on the surface and to cause permanent loss in the activity. In the presence of sulfur, the performance of both CA-modified catalysts is better compared to that of the base catalyst. The sulfur poison affects the hydrogenation and the chain-propagation ability of the catalysts, and shifts the product selectivity towards short-chain hydrocarbons with a higher percentages of olefins. Highly dispersed CA-modified catalysts have a longer life in the presence of sulfur poison

Fischer-Tropsch Synthesis on Multicomponent Catalysts: What Can We Learn from Computer Simulations?

In this concise review paper, we will address recent studies based on the generalized-gradient approximation (GGA) of the density functional theory (DFT) and on the periodic slab approach devoted to the understanding of the Fischer-Tropsch synthesis process on transition metal catalysts. As it will be seen, this computational combination arises as a very adequate strategy for the study of the reaction mechanisms on transition metal surfaces under well-controlled conditions and allows separating the influence of different parameters, e.g., catalyst surface morphology and coverage, influence of co-adsorbates, among others, in the global catalytic processes. In fact, the computational studies can now compete with research employing modern experimental techniques since very efficient parallel computer codes and powerful computers enable the investigation of more realistic molecular systems in terms of size and composition and to explore the complexity of the potential energy surfaces connecting reactants, to intermediates, to products of reaction. In the case of the Fischer-Tropsch process, the calculations were used to complement experimental work and to clarify the reaction mechanisms on different catalyst models, as well as the influence of additional components and co-adsorbate species in catalyst activity and selectivity

Phytochemical investigation and anti-Inflammatory activity of Coccinia indica wight and arn. (Cucurbitaceae) fruits

The present work was to study the anti-inflammatory activity of Coccinia indica Wight and Arn fruits belonging to family Cucurbitaceae. The fruit powder of C. indica was subjected to successive extraction with petroleum ether, chloroform, ethanol and water in a Soxhlet extractor. The ethanol extract after preliminary phytochemical investigation shown the presence of glycosides, triterpenoids, flavonoids, tannins and phenolic compounds. The anti-inflammatory activity was studied using carrageenan-induced rat paw oedema and cotton pellet granuloma at three different doses (100, 200 and 400 mg/kg b.w. p.o.) of each extract. The ethanol extract of C. indica fruits exhibited significant anti-inflammatory activity at the dose of 200 mg/kg and 400 mg/kg in both models when compared with control group. Indomethacin (10 mg/kg b.w. p.o) also showed significant anti-inflammatory activity in both models.Colegio de Farmacéuticos de la Provincia de Buenos Aire

The reactive metabolite target protein database (TPDB) – a web-accessible resource

BACKGROUND: The toxic effects of many simple organic compounds stem from their biotransformation to chemically reactive metabolites which bind covalently to cellular proteins. To understand the mechanisms of cytotoxic responses it may be important to know which proteins become adducted and whether some may be common targets of multiple toxins. The literature of this field is widely scattered but expanding rapidly, suggesting the need for a comprehensive, searchable database of reactive metabolite target proteins. DESCRIPTION: The Reactive Metabolite Target Protein Database (TPDB) is a comprehensive, curated, searchable, documented compilation of publicly available information on the protein targets of reactive metabolites of 18 well-studied chemicals and drugs of known toxicity. TPDB software enables i) string searches for author names and proteins names/synonyms, ii) more complex searches by selecting chemical compound, animal species, target tissue and protein names/synonyms from pull-down menus, and iii) commonality searches over multiple chemicals. Tabulated search results provide information, references and links to other databases. CONCLUSION: The TPDB is a unique on-line compilation of information on the covalent modification of cellular proteins by reactive metabolites of chemicals and drugs. Its comprehensiveness and searchability should facilitate the elucidation of mechanisms of reactive metabolite toxicity. The database is freely available a