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111.
Crosslinked natural rubber (NR) nanocomposites were prepared using cellulose nanowhiskers (CNWs) that were extracted from bamboo pulp residue of newspaper production, as the reinforcing phase. The coagulated NR latex containing bamboo nanowhiskers (master batch) was compounded with solid NR and vulcanizing agents using a two-roll mill and subsequently cured to introduce crosslinks in the NR phase. No evidence of micro-scaled aggregates of cellulose nanowhiskers in NR matrix was observed in Scanning Electron Microscopy (SEM) images. The addition of CNWs had a positive impact on the tensile strength, E-modulus, storage modulus, tan delta peak position and thermal stability of the crosslinked NR. Theoretical modeling of the mechanical properties showed a lower performance than predicated and therefore further process optimization and/or compatibilization are required to reach the maximum potential of these nanocomposites. 相似文献
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Aarthy K Chindhanaiselvam Anitha Priya John Abraham Nambirajan Subramanian 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(19):2823-2829
Dwarf Poinciana (Caesalpinia pulcherrima) seeds are studied for first time for the extraction of bio-oil. The dried and crushed seeds are optimized for maximum yield of bio-oil with a series of polar and nonpolar solvents and recovered by a simple distillation process. Methanol is found to yield the maximum bio-oil. The fatty acid analysis of bio-oil reveals the prevalence of linoleic acid (54.67%), followed by palmitic acid (16.9%), stearic acid (12.5%), and oleic acid (10.32%). Basic fuel properties like specific gravity, viscosity, refractive index, iodine value, saponification value, fire point, flash point, pour point, and calorific value are studied. 相似文献
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Serafino Teseo Emmanuel Lecoutey Daniel J. C. Kronauer Abraham Hefetz Alain Lenoir Pierre Jaisson Nicolas Châline 《Journal of chemical ecology》2014,40(5):429-438
Although cuticular hydrocarbons (CHCs) have received much attention from biologists because of their important role in insect communication, few studies have addressed the chemical ecology of clonal species of eusocial insects. In this study we investigated whether and how differences in CHCs relate to the genetics and reproductive dynamics of the parthenogenetic ant Cerapachys biroi. We collected individuals of different ages and subcastes from several colonies belonging to four clonal lineages, and analyzed their cuticular chemical signature. CHCs varied according to colonies and clonal lineages in two independent data sets, and correlations were found between genetic and chemical distances between colonies. This supports the results of previous research showing that C. biroi workers discriminate between nestmates and non-nestmates, especially when they belong to different clonal lineages. In C. biroi, the production of individuals of a morphological subcaste specialized in reproduction is inversely proportional to colony-level fertility. As chemical signatures usually correlate with fertility and reproductive activity in social Hymenoptera, we asked whether CHCs could function as fertility-signaling primer pheromones determining larval subcaste fate in C. biroi. Interestingly, and contrary to findings for several other ant species, fertility and reproductive activity showed no correlation with chemical signatures, suggesting the absence of fertility related CHCs. This implies that other cues are responsible for subcaste differentiation in this species. 相似文献
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Oleogels from Glycerol‐Based Lyotropic Liquid Crystals: Phase Diagrams and Structural Characterization
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Yael Cegla‐Nemirovsky Abraham Aserin Nissim Garti 《Journal of the American Oil Chemists' Society》2015,92(3):439-447
In the course of our studies on structured reverse lyotropic liquid crystals (LLC) as oleogels, a system was designed with the desired physical and rheology properties for cosmetic and pharmaceutical applications. The aqueous phase was partially replaced by glycerol to minimize bacteriological problems and obtain specific rheology characteristics. The constructed phase diagrams are based on ternary mixtures of glycerol monooleate (GMO), decane, water, and glycerol. The main lyotropic mesophase obtained in this study was reverse hexagonal derived from dilution line 8:2 (72 wt% GMO and 18 wt% decane) and 10 wt% water; or water:glycerol (wt ratios 3:1 and 1:1) mixture. It was found that heat‐cool fluctuation caused formation of new pseudo‐equilibrium structures with mesomorphic transformations to more fluid and less ordered mesostructures. Replacing up to 50 wt% of the water by glycerol significantly increases the gel phase region in the phase diagram, meaning more structural compositional options. The structural parameters were determined using cross‐polarized light microscopy (CPLM), differential scanning calorimeter (DSC), powder X‐ray diffraction (PXRD), and small angle X‐ray scattering (SAXS). Rheological measurements revealed viscoelastic properties of lyotropic liquid crystals with a decrease in the elasticity (G′), plasticity (G″), and complex viscosity (η*), as a function of increasing the glycerol content. 相似文献
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Multiuser multiple‐input multiple‐output orthogonal frequency division multiple access (MIMO‐OFDMA) is considered as the practical method to attain the capacity promised by multiple antennas in the downlink direction. However, the joint calculation of precoding/beamforming and resource allocation required by the optimal algorithms is computationally prohibitive. This paper proposes computationally efficient resource allocation algorithms that can be invoked after the precoding and beamforming operations. To support stringent and diverse quality of service requirements, previous works have shown that the resource allocation algorithm must be able to guarantee a specific data rate to each user. The constraint matrix defined by the resource allocation problem with these data rate constraints provides a special structure that lends to efficient solution of the problem. On the basis of the standard graph theory and the Lagrangian relaxation, we develop an optimal resource allocation algorithm that exploits this structure to reduce the required execution time. Moreover, a lower‐complexity suboptimal algorithm is introduced. Extensive simulations are conducted to evaluate the computational and system‐level performance. It is shown that the proposed resource allocation algorithms attain the optimal solution at a much lower computational overhead compared with general‐purpose optimization algorithms used by previous MIMO‐OFDMA resource allocation approaches. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献