Influence of cerium oxide additive and aloe vera biodiesel on a CI engine

Diesel is the main source of world transportation due to higher combustion efficiency, compliance, consistency and cost-economy. It is also a major contributor to the world prosperity since it is used extensively. Diesel engine’s emissions are the serious hazard to the world environment and it is measured to be the major causes of air pollution. The demand in biofuels for years created a scope for aloe vera into biodiesels. Aloe vera, having higher calorific value vnthan other plant sources used as biodiesels, enhanced us in making another alternative biodiesel, which has lesser emissions and better performance. In this research work, four biodiesel blends from aloe vera oil with cerium oxide additive are explored for their performance and emission characteristics. The results proved B30 (30% biodiesel, 68% diesel and 1% cerium oxide) gives good performance when compared to other blends.     

Numerical and Experimental Studies of Parasitic Heat Losses in Coldfinger of a Pulse Tube Cryocooler in Off-State Condition

A pulse tube cryocooler (PTC) for future metrological satellites has been developed at one of the lead centers of the Indian Space Research Organisation in Bangalore, India for cooling on-board Infrared (IR) detectors to 80 K.A study has been conducted on the coldfinger of PTC to understand the off-state heat loads on the cooler by varying the value of gravity numerically in ANSYS FLUENT and experimentally by orienting the setup with respect to gravity. The off-state parasitic losses represent a major heat load in on-board applications that include redundant, viz. nonoperating coolers. To find out the amount of off-state parasitic heat losses in a nonoperating coldfinger of the PTC experimentally, transient warm-up technique was used. Various heat loads were applied experimentally on the cryo-tip at temperatures ranging from 80 to 100 K for determining the parasitic losses. The effect of orientation of PTC on the off-state parasitic heat load with respect to gravity is studied and presented in this paper. Enhancement due to free convection heat flow normalized by gas molecular conduction in pulse tube is analyzed using computational fluid dynamics to verify and compare with experimental results. The best orientation angle where the parasitic is low is when the cold end of the coldfinger of pulse tube cryocooler faces down (0^°) and high when the cold end of the coldfinger is oriented to 135^°.     

Melt Rheological Behavior and Creep Response of EVA/TPU Blends: Exploring the Effect of Electron Beam Irradiation and Peroxide Cross-linking

The present study focuses on the variation of the melt rheological characteristics and the creep behavior of both electron beam-cross-linked and peroxide-cured ethylene vinyl acetate/thermoplastic polyurethane blends. The variation of complex viscosity, complex modulus, storage modulus, and loss modulus was evaluated over a wide range of frequency and strain amplitude using rubber process analyzer and the effect of radiation dose and peroxide concentration was investigated in detail. The creep study using dynamic mechanical analyzer shows that the creep behavior of the blends significantly improves after cross-linking and the creep compliance gradually decreases with the increasing radiation dose and peroxide content. An attempt was also made to pursue a comparative rheological and creep study among the peroxide-cured, electron beam-cross-linked and the coagent-treated dynamically vulcanized samples.     

Room temperature synthesis of high temperature stable lanthanum phosphate–yttria nano composite

A facile aqueous sol–gel route involving precipitation–peptization mechanism followed by electrostatic stabilization is used for synthesizing nanocrystalline composite containing lanthanum phosphate and yttria. Lanthanum phosphate (80 wt%)–yttria (20 wt%) nano composite (LaPO₄–20%Y₂O₃), has an average particle size of ～70 nm after heat treatment of precursor at 600 °C. TG–DTA analysis reveals that stable phase of the composite is formed on heating the precursor at 600 °C. The TEM images of the composite show rod shape morphology of LaPO₄ in which yttria is acquiring near spherical shape. Phase identification of the composite as well as the phase stability up to 1300 °C was carried out using X-ray diffraction technique. With the phases being stable at higher temperatures, the composite synthesized should be a potential material for high temperature applications like thermal barrier coatings and metal melting applications.     

Hybrid polymer-grafted multiwalled carbon nanotubes for in vitro gene delivery

Carbon nanotubes (CNTs) consist of carbon atoms arranged in sheets of graphene rolled up into cylindrical shapes. This class of nanomaterials has attracted attention because of their extraordinary properties, such as high electrical and thermal conductivity. In addition, development in CNT functionalization chemistry has led to an enhanced dispersibility in aqueous physiological media which indeed broadens the spectrum for their potential biological applications including gene delivery. The aim of this study is to determine the capability of different cationic polymer-grafted multiwalled carbon nanotubes (MWNTs) (polymer-g-MWNTs) to efficiently complex and transfer plasmid DNA (pCMV-βGal) in vitro without promoting cytotoxicity. Carboxylated MWNT is chemically conjugated to the cationic polymers polyethylenimine (PEI), polyallylamine (PAA), or a mixture of the two polymers. In order to explore the potential of these polymer-g-MWNTs as gene delivery systems, we first study their capacity to complex plasmid DNA (pDNA) using agarose gel electrophoresis. Gel migration studies confirm pDNA binding to polymer-g-MWNT with different affinities, highest for PEI-g-MWNT and PEI/PAA-g-CNT constructs. β-galactosidase expression is assessed in human lung epithelial (A549) cells, and the cytotoxicity is determined by modified LDH assay after 24 h incubation period. Additionally, PEI-g-MWNT and/or PEI/PAA-g-MWNT reveal an improvement in gene expression when compared to the naked pDNA or to the equivalent amounts of PEI polymer alone. Mechanistically, pDNA was delivered by the polymer-g-MWNT constructs via a different pathway compared to those used by polyplexes. In conclusion, polymer-g-MWNTs may be considered in the future as a versatile tool for efficient gene transfer in cancer cells in vitro, provided their toxicological profile is established.     

Revisiting the mechanism of the triosephosphate isomerase reaction: the role of the fully conserved glutamic acid 97 residue

An analysis of 503 available triosephosphate isomerase sequences revealed nine fully conserved residues. Of these, four residues—K12, H95, E97 and E165—are capable of proton transfer and are all arrayed around the dihydroxyacetone phosphate substrate in the three‐dimensional structure. Specific roles have been assigned to the residues K12, H95 and E165, but the nature of the involvement of E97 has not been established. Kinetic and structural characterization is reported for the E97Q and E97D mutants of Plasmodium falciparum triosephosphate isomerase (Pf TIM). A 4000‐fold reduction in k_cat is observed for E97Q, whereas the E97D mutant shows a 100‐fold reduction. The control mutant, E165A, which lacks the key catalytic base, shows an approximately 9000‐fold drop in activity. The integrity of the overall fold and stability of the dimeric structure have been demonstrated by biophysical studies. Crystal structures of E97Q and E97D mutants have been determined at 2.0 Å resolution. In the case of the isosteric replacement of glutamic acid by glutamine in the E97Q mutant a large conformational change for the critical K12 side chain is observed, corresponding to a trans‐to‐gauche transition about the Cγ? Cδ (χ³) bond. In the E97D mutant, the K12 side chain maintains the wild‐type orientation, but the hydrogen bond between K12 and D97 is lost. The results are interpreted as a direct role for E97 in the catalytic proton transfer cycle. The proposed mechanism eliminates the need to invoke the formation of the energetically unfavourable imidazolate anion at H95, a key feature of the classical mechanism.     

Wollastonite/hydroxyapatite scaffolds with improved mechanical,bioactive and biodegradable properties for bone tissue engineering

Wollastonite/hydroxyapatite composite scaffolds are proposed as bone graft. An investigation on scaffold with varying reinforcing wollastonite content fabricated by polymeric sponge replica is reported. The composition, sintering behavior, morphology, porosity and mechanical strength were characterized. All the scaffolds had a highly porous well-interconnected structure. A significant increase in mechanical strength is achieved by adding a 50% wollastonite phase. The most mechanically resistant (50/50) wollastonite/hydroxyapatite scaffolds were soaked in both simulated body fluid (SBF) and Tris–HCl solution in order to assess bioactivity and biodegradability. A carbo-hydroxyapatite layer formed on their surfaces when immersed in SBF. The biodegradability tests reveals that the composite scaffold shows a higher degradation rate compared to pure hydroxyapatite used as comparison. These results demonstrate that the incorporation of a 50% of wollastonite phase in hydroxyapatite matrix is effective in improving the strength and the bioactive and biodegradable properties of the porous scaffolds.     

Beryllium-doped single-walled carbon nanotubes with Stone-Wales defects: A promising material to store hydrogen at room temperature

Hydrogen storage in single-walled carbon nanotubes containing the Stone-Wales defects and doped with metal atoms (titanium and beryllium) has been studied using molecular dynamics simulations and density functional theory calculations. Although, Be is known to be toxic at high temperatures, Be-doped SWCNT shows a promising potential to exceed the DOE target at moderate temperatures and pressures. One of the major advantages of doping Be is its lower atomic weight, which increases the gravimetric storage capacity compared to SWCNTs doped with heavy-wight Ti atoms. In addition, the binding energy of Be is higher than that of Ti, which enhances the capture of hydrogen molecules. The gravimetric and volumetric storage capacities depend not only on the dopant atom but also on the location of doping. SWCNTs in which Be is doped on the octagonal ring of the Stone-Wales defects exhibits higher storage capacity than Be doped on defect-free SWCNTs. At room temperature (298 K), the storage capacity of Be-doped SWCNT containing the Stone-Wales defect exceeds the DOE target of 5.5 wt% (gravimetric) and 40 g H₂/L (volumetric) at a pressure of 267 atm, which is significantly lower than that used in high pressure vessels.     

Effect of Temperature on Grain Size in AA6063 Aluminum Alloy Subjected to Repetitive Corrugation and Straightening

The influence of processing temperature on grain size reduction in AA 6063 aluminum alloy subjected to repetitive corrugation and straightening(RCS)is investigated in this work.The aluminum alloy was processed by RCS at different temperatures(room temperature,100 ℃,200 ℃ and 300 ℃)till the maximum number of passes possible before failure and the mechanical properties such as tensile strength and hardness were measured.The grain size and their misorientation of grains of the processed samples were analyzed using the electron backscattered diffraction.The results indicated that the transformation of low-angle grain boundaries to high-angle grain boundaries and dislocation tangles were highly dependent on the strain imparted,which could be controlled by selecting the proper processing temperature.As a result,the mechanical properties are affected.In particular,the room temperature tensile strength and hardness values of the processed material decrease with increasing processing temperature.     

Flexural studies on asymmetric hybrid Kevlar fabric/epoxy composites

For composites reinforced with Kevlar fabrics, the method of asymmetric hybridization is employed for the improvement of flexural properties such as maximum fibre yield stress and modulus of elasticity in bending. Calculations based on the elastic-plastic analysis are used to assess the shift in the neutral axis during bending, and the bimaterial beam model is invoked to estimate the arrangement and replacement of Kevlar fibres by carbon fibres in the compression face, for two relative fibre orientations. Flexural properties of the bimaterial are compared with those of unmodified Kevlar/epoxy composite for three different loading rates. Scanning electron microscopic examination of the fracture features is discussed.