Reinforcement of magnesium with boron and tantalum filaments

Composites of magnesium reinforced with continuous boron filaments (0.004 in. diam and 450 ksi tensile strength), and tantalum (0.010 in. diam and 78 ksi tensile strength) were fabricated by the infiltration technique. The tensile strength of the boron filament dropped to nearly half its original strength (230 ksi) as a result of exposure to molten magnesium. The tantalum filaments, however, maintained their original strength after infiltration. The stress-strain curves of B-Mg composites were of a typical brittle material. The elongation in each case approached that of the filament,i.e., about 0.35 pct. Ta-Mg composites failed essentially in ductile manner. The elongation of the composites with 0.4Vf was as high as 15.7 pct. The elastic modulus, tensile and yield strength, and fracture behavior of the two composite systems are discussed.     

Paired helical filaments (PHFs) are a family of single filament structures with a common helical turn period: negatively stained PHF imaged by TEM and measured before and after sonication, deglycosylation, and dephosphorylation

Isolated paired helical filaments (PHFs) were visualized on glutaraldehyde vapor-treated thin approximately 10-nm thick indirect carbon films using high-resolution transmission electron microscopy (TEM) and the negative stain, phosphotungstate acid (PTA) at near neutral pH of 6.8. PHF preparations were prepared with and without 1 minute of sonication. These same PHF were also deglycosylated with endoglycosidase F/N-glycosidase F for 1 hour or the PHF were dephosphorylated with PP-2A for 1 hour. The negatively stained PHF filaments were quantitatively studied by measuring their wide regions (W) their thin regions (T) and their helical turn period (L) and these separate parameters were averaged for each filament. In the unsonicated PHF preparation there were PHF, cylindrical filaments with periodic thin regions (CF-PT), cylindrical filaments (CF), as well as 2.0-nm tau polymer-like filaments. The CF-PT were characterized by W, T, and L measurements and the CF were characterized by diameter measurements. The paired helical filament model proposed by Kidd (1963, Nature 197:192-193) of two approximately 10 nm filaments twisting around each other every approximately 80 nm with a thin region of 10 nm and a wide region of 25 nm does not correspond to the PHF structures found. None of the PHF we observed were composed of a pair of filaments and all of the PHF appear to be a single filament. The wide regions ranged from 12.5-27 nm and the thin regions ranged from 4.5-12.3 nm. The helical turn periods ranged from 76-85 nm and were generally about 80 nm. Only the helical turn period of approximately 80 nm was a common property of the whole family of PHF structures. The CF-PT appear to be a PHF precursor filament. Deglycosylation of the PHF and CF-PT reduced their sizes by 0.5-0.6 nm and 0.7-1.0 nm, respectively, and the right-hand helicity of the PHF was lost after deglycosylation. Dephosphorylation with PP-2A reduced the PHF wide regions by 6.0 nm and the thin regions by 2.6 nm.     

Synthesis ofGEM-dibromocyclopropanoid fatty esters using phenyl (tribromomethyl) mercury

Thegem-dibromocyclopropanation of naturally occurring unsaturated hydroxy fatty esters, methyl ricinoleate (I) and methyl isoricinoleate (II), has been undertaken to provide compounds which might have potential utility. Phenyl(tribromomethyl)mercury reacts only with the carbon-carbon double bond of each substrate, leaving the OH group intact. The product, methyl 9,10-dibromomethylene-12-hydroxyoctadecanoate (III) and methyl 12,13-dibromomethylene-9-hydroxyoctadecanoate (IV), obtained from I and II, respectively, were characterized by elemental, infrared (IR) and nuclear magnetic resonance (NMR) analyses.     

The trap depth in evaporated polypropylene from measurements of thermally stimulated currents

The occurrence of thermally stimulated currents in thin evaporated films of polypropylene was demonstrated and an analysis of the curves gave an electron trap depth of 0.33 eV in this material.     

Feeding rolled barley grain steeped in lactic acid modulated energy status and innate immunity in dairy cows

Feeding dairy cows large proportions of cereal grain is commonly associated with rumen acidosis, activation of innate immunity, and perturbation of intermediary metabolism. We previously showed that steeping barley grain in 0.5% lactic acid (LA) decreased the rate of starch degradation, lowered the risk of subacute rumen acidosis, modulated rumen fermentation profile, and increased milk fat content in dairy cows. This study sought to investigate whether feeding of LA-treated barley grain would affect carbohydrate and lipid metabolism as well as innate immunity. Eight rumen-fistulated late-lactation (approximately 217 d in milk, DIM) Holstein cows were randomly assigned, in a 2 × 2 crossover design, to 1 of the 2 dietary treatments consisting of 27% (dry matter basis) rolled barley grain steeped for 48 h in an equal volume (wt/vol) of tap water (CTR) or 0.5% LA (TRT). Each experimental period lasted 21 d, with the first 11 d for diet adaptation. Blood and rumen samples were collected on d 12, 15, 17, and 21 of the experimental period before the morning feeding to evaluate the effects of dietary treatment on preprandial day-to-day variation of plasma and rumen variables. To establish the effect of treatment on diurnal variation of plasma variables, blood samples were collected on the last day of each period at 0, 2, 4, 6, 8, 10, and 12 h after the morning feeding (i.e., 0800 h). Results of the day-to-day study showed that cows fed the TRT diet had greater overall preprandial concentrations of glucose, cholesterol, and insulin, and a lower concentration of haptoglobin in plasma. Diurnal data indicated lower concentrations of haptoglobin and serum amyloid A and a tendency for greater plasma lactate in cows fed the TRT diet. A treatment by time interaction was observed for glucose, lactate, insulin, haptoglobin, and lipopolysaccharide-binding protein, suggesting a role for both the processing of grain and the time of sampling on those variables. No effect of diet on plasma concentrations of cortisol, β-hydroxybutyrate, and nonesterified fatty acids or rumen endotoxin was evidenced. Taken together, our results demonstrated that feeding barley grain steeped in 0.5% LA modulated both energy status and innate immunity of dairy cows fed relatively high levels (45% of dry matter) of dietary concentrate.     

Current scenario and potential of biodiesel production from waste cooking oil in Pakistan: An overview

Biodiesel utilization has been rapidly growing worldwide as the prime alternative to petrodiesel due to a global rise in diesel fuel demand along with hazardous emissions during its thermochemical conversion. Although, several debatable issues including feedstock availability and price, fuel and food competition, changes in land use and greenhouse gas emission have been raised by using edible as well as inedible feedstocks for the production of biodiesel. However, non-crop feedstocks could be a promising alternative. In this article, waste cooking oils have been recommended as a suitable option for biodiesel production bearing in mind the current national situation. The important factors such as the quantity of waste cooking oil produced, crude oil and vegetable oil import expenses, high-speed diesel imports, waste management issues and environmental hazards are considered. Moreover, process simulation and operating cost evaluation of an acid catalyzed biodiesel production unit are also conducted. The simulation results show that the production cost of waste cooking oil-based biodiesel is about 0.66USD·L^-1. We believe that the present overview would open new pathways and ideas for the development of biofuels from waste to energy approach in Pakistan.     

Phase change materials,their synthesis and application in textiles—a review

Phase change materials (PCMs) are widely being used in thermal energy storage systems for solar engineering, building materials, heat pumps, spacecraft, and in textile field especially smart and technical textiles. There are large numbers of organic and inorganic PCMs that possess a wide range of melting and solidifying temperature which attracts researcher’s attention for their applications in different fields. This review paper summarizes the investigation and analysis of the available organic and inorganic PCMs, different encapsulating techniques, characterization techniques, incorporation into fiber and pad application on textiles with practical applications in the field of smart textiles.     

Thermal depolarization and electromechanical hardening in Zn2+-doped Na1/2Bi1/2TiO3-BaTiO3

Na_1/2Bi_1/2TiO₃-based materials have been earmarked for one of the first large-volume applications of lead-free piezoceramics in high-power ultrasonics. Zn²⁺-doping is demonstrated as a viable route to enhance the thermal depolarization temperature and electromechanically harden (1-y)Na_1/2Bi_1/2TiO₃-yBaTiO₃ (NBT100yBT) with a maximum achievable operating temperature of 150 °C and mechanical quality factor of 627 for 1 mole % Zn²⁺-doped NBT6BT. Although quenching from sintering temperatures has been recently touted to enhance T_F-R, with quenching the doped compositions featuring an additional increase in T_F-R by 17 °C, it exhibits negligible effect on the electromechanical properties. The effect is rationalized considering the missing influence on conductivity and therefore, negligible changes in the defect chemistry upon quenching. High-resolution diffraction indicates that Zn²⁺-doped samples favor the tetragonal phase with enhanced lattice distortion, further corroborated by ²³Na Nuclear Magnetic Resonance investigations.     

Fabrication and characterization of MnO2 based composite sheets for development of flexible energy storage electrodes

Development of cost efficient, flexible and light weight paper electrodes for high-tech applications is high in demand in era of modern disposable technology. In this study α-MnO₂ nanorods were fabricated through hydrothermal method by varying growth time and further combined with lignocelluloses fibers extracted from self growing plant, Monochoria Vaginalis. Crystal structure, morphology and thermal properties of MnO₂ nanorods were characterized by X. Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Thermogravimetric Analysis (TGA), respectively. FESEM image analysis revealed the highest aspect ratio of 48.016 for 4?h treated MnO₂ sample and high purity level was confirmed by XRD. MnO₂ sample with high aspect ratio, relatively pure and larger yield was selected for incorporation of lignocelluloses fibers to fabricate flexible, light-weight and environmentally safe LC/MnO₂ composite paper sheet. Furthermore, LC/MnO₂ composite sheet was employed as working electrode in 2?M sodium sulfate electrolyte for cyclic voltammetry measurements. Presented LC/MnO₂ composite sheet revealed specific capacitances 117, 59, 39, 25 and 23?F/g at scan rates of 5, 10, 20, 50 and 100?mV/s, respectively. Incorporation of LC fibers within MnO₂ nanorods as binders will open the possibilities to fabricate the flexible paper electrode for application in supercapacitors and batteries due to facile synthesis, light-weight and environmentally friendly aspects.