Abrasive water jet machining and mechanical behavior of banyan tree saw dust powder loaded polypropylene green composites

Banyan tree saw dust powder (BSD) filled Polypropylene (PP) green composites have been fabricated with varying amounts viz., 0%, 20%, and 40% of BSD particulate filler by using a co‐rotating twin screw extruder followed by injection molding. The mechanical properties such as surface hardness, tensile behavior, and impact strength of the fabricated PP/BSD green composites have been studied in order to standardize the composites. Abrasive water jet (AWJ) machining has been reported mainly for ceramics, concrete, and glass but not much literature is available on AWJ machining of polymer composites. This research is aimed at examining the AWJ machining of green polymer composites. The effect of BSD loading on the AWJ machining behavior of the PP/BSD green composites has been investigated. Furthermore, the effect of addition of 4% maleic anhydride grafted PP (coupling agent) and 4% talc (mineral filler) on the machining behavior of PP/BSD composites has also been evaluated. Surface roughness and optical micrographs of the AWJ cut composite specimens were examined to assess the effect of BSD content, AWJ traverse speed and pressure on the machining behavior of the composites. In order to probe the mechanism of AWJ machining behavior of PP/BSD composites, the kerf width and taper have been measured and results are correlated. POLYM. COMPOS., 37:1754–1764, 2016. © 2014 Society of Plastics Engineers     

Silver monoliths and their applications in catalytic reduction of 4-NP to 4-AP and sensing against As3+

Journal of Porous Materials - Silver monoliths using non-ionic surfactant Triton X-102 as reducing agent with and without additives such as Dextran and Ludox (SiNPs) were synthesized by modified...     

Efficient conversion of light paraffinic naphtha to aromatics over metal-modified Mo/MFI catalysts

Journal of Porous Materials - The transformation of light naphtha to value-added aromatic compounds is gaining momentum in the petrochemical industry. In this work, a series of metal modified...     

Synthesis and Properties of MoSi2–MoB–SiC Ceramics

MoB and SiC particulate reinforced MoSi₂ matrix composites were synthesized in situ from Mo, Si, and B₄C powder mixtures by self‐propagating high‐temperature synthesis (SHS). The SHS MoSi₂–MoB–SiC products were vacuum hot‐pressed (HPed) at 1400°C for 90 min to fabricate high‐density (> 97.5% relative density) bulk composites. Microstructure refinement and improvements in the Vickers hardness and fracture toughness of the HPed composites were observed with increasing B₄C content in the reaction mixture. The HPed composite of composition MoSi₂–0.4MoB–0.1SiC exhibited grain size of 1–5 μm, Vickers hardness of 12.5 GPa, bending strength of 537 MPa, and fracture toughness of 3.8 MPa.m^1/2. These excellent mechanical properties indicate that MoB and SiC particulate reinforced MoSi₂ composites could be promising candidates for structural applications.     

Treatment of olive mill washing water by ultrafiltration

Olive oil production requires important quantities of washing water containing low oil concentrations, but classical processes used to recover or to eliminate this oil are ineffective. This study presents a membrane technique to treat olive oil mill washing water using different commercial ultrafiltration membranes: one organic (PCI) and two ceramic (Ceraver) membranes. The influence of the hydrodynamic parameters (transmembrane pressure and flow rate) and the cut‐off membranes on the efficiency of the ultrafiltration process was evaluated, and it was shown the organic PCI membrane could reduce pollution due to organic matter by decreasing the value of the Chemical oxygen demand by about 90%. Moreover, the nature of the ultrafine pore membrane appeared to be an important parameter which may strongly increase or decrease the capacity of the membrane. The membrane cut‐off did not have a strong influence on the performance of the process but if the membrane pores were too large the stability of the dynamically formed membrane decreased at transmembrane pressures greater than 0.2 MPa.     

Influence of Elevated Temperature and Stress Ratio on the Fatigue Response of AM60B Magnesium Alloy

The fatigue response of a high pressure die-cast AM60B Mg alloy is studied at room and elevated temperatures. The fatigue tests are conducted with stress ratio of R?=?0.1 and frequency of 30?Hz. The main objective is to determine whether elevated temperature would affect the fatigue response of the alloy. In addition, fatigue crack growth characteristics of the alloy is investigated at room temperature. The purpose of this test is to ascertain the capability and accuracy of a finite element approach coupled with the Walker model in assessing the life cycle of the alloy, in consideration of the influence of stress ratio.     

N-3 Polyunsaturated Fatty Acids Modulate In-Vitro T Cell Function in Type I Diabetic Patients

In this work, we assessed the in-vitro effects of eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3) (final concentration, 15 microM) on T cell blastogenesis, interleukin-2 and -4 (IL-2, IL-4) secretion, fatty acid composition and intracellular oxidative status in type I diabetic patients with or without complications. Con A stimulated lymphocyte proliferation, glucose uptake, intracellular reduced glutathione levels and catalase activity were lower in diabetics as compared to controls, regardless to the presence of complications. EPA and DHA diminished T-lymphocyte proliferation and IL-2 production but enhanced IL-4 secretion in both diabetic and control groups. No changes in the levels of reduced glutathione and in the activities of catalase and SOD were observed in control T cells cultured in the presence of EPA and DHA. However, in diabetic patients, addition of n-3 PUFA to culture induced an increase in T cell levels of reduced glutathione and hydroperoxide, and in activities of catalase and SOD. Low levels of arachidonic acid (C20:4n-6) were found in plasma membrane phospholipids of lymphocytes from diabetic patients compared to controls. Incubation of lymphocytes with EPA and DHA was associated with an incorporation of these fatty acids in membrane phospholipids. In conclusion, the beneficial effects of n-3 PUFA on T cell functions in type I diabetes could be attributed to their suppressive action and modulation of cytokine secretion, and to the improvement of intracellular oxidative status.     

Natural rubber filled SiC and B4C ceramic composites as a new NTC thermistors and piezoresistive sensor materials

A novel electrically conductive composite for NTC thermistor and piezoresistive sensor was successfully fabricated by homogeneously dispersing conductive SiC and B₄C in an insulating natural rubber (NR) matrix. The morphology of the composites was investigated by means of scanning electron microscopy, cross linking density (n), volume fraction of rubber (V_r), and interparticle distance among conductive phases (r_p). The influence of the filler concentrations on the mechanical properties such as modulus of elasticity (E); hardness shore A (H), and elongation at break (EB) were studied in details. The dependences of volume resistivity of NR based composites filled with B₄C and SiC as a function of fillers concentration was investigated. Temperature dependencies of volume resistivity were also measured to examine the possible application of the composites to polymer linear negative temperature (NTC) thermistors. Furthermore, the temperature dependencies of dielectric constant of the composites were studied. For practical application, the thermal stability of the composites was examined by means of resistivity temperature and pressure hysteresis cycle. In parallel, the conduction mechanism of conductivity of the composites was interpreted in terms of the computed the activation and hopping energy. The applicability of the composites to piezoresistive sensor was examined too. The good mechanical properties and thermal stability of NR composites behavior can be utilized for fabricating various electronic devices as NTC thermistors and piezoresistive sensor (i.e. transducers in pressure sensors). POLYM. COMPOS., 29:109–118, 2008. © 2007 Society of Plastics Engineers     

Microstructure and hardness studies of the electron beam welded zone of Hastelloy C-276

Electron beam welding (EBW) technique is becoming popular in nuclear, chemical and aerospace industries due to its high penetration depth and fast cooling rate. Samples of Hastelloy C-276 have been welded by electron beam (EB). A scanning electron microscope (SEM) having the attachment of an energy dispersive system (EDS) has been employed to study the resulting microstructure and micro-eutectic phases. The microstructure of the molten zone (MZ) is found to be of fine lamellar type. The hardness of the MZ is found to be 35% higher compared to as-received alloy. The micro-eutectoids are rich in Mo and W. The X-ray diffraction patterns of the MZ show shifting of peaks towards higher angle compared to the diffraction pattern of the as-received alloy. Broadening of the peaks is also observed in the diffraction pattern of the MZ. Formation of the μ-phase was observed in the MZ after a tempering treatment at 950 °C.     

Temperature and processing effects on lithium ion conductivity of solution-deposited lithium zirconium phosphate (LiZr2P3O12) thin films

Lithium zirconium phosphate (LiZr₂P₃O₁₂) thin films have been prepared on platinized silicon substrates via a chemical solution deposition approach with processing temperatures between 700°C and 775°C. Films that were subject to a single high-temperature anneal were found to crystallize at temperatures above 725°C. Crystallization was observed in films annealed after each deposited layer at 700°C and above. In both cases, grain size was found to increase with annealing temperature. Ion conductivity was found to increase with annealing temperature in singly annealed films. In per-layer annealed films ion conductivity was found to initially increase then decrease with increasing annealing temperature. A maximum ion conductivity of 1.6 × 10⁻⁶ S/cm was observed for the singly annealed 775°C condition, while a maximum ion conductivity of 5.8 × 10⁻⁷ S/cm was observed for the 725°C per-layer annealed condition. These results are consistent with an increasing influence of cross-plane, internal interface resistance and vapor phase carrier loss in the per-layer annealed samples. This work demonstrates that post-deposition processing methods can strongly affect the ion conducting properties of LiZr₂P₃O₁₂ thin films.