On cavitation and macroscopic behaviour of amorphous polymer-rubber blends

The macroscopic behaviour of rubber-modified polymethyl methacrylate (PMMA) was investigated by taking into account the microdeformation mechanisms of rubber cavitation. The dependence of the macroscopic stress–strain behaviour of matrix deformation on the cavitation of rubber particles was discussed. A phenomenological elastic-viscoplastic model was used to model the behaviour of the matrix material, while the rubber particles were modelled with the hyperelasticity theory. A two-phase composite material with a periodic arrangement of reinforcing particles of a circular unit cell section was considered. Finite-element analysis was used to determine the local stresses and strains in the two-phase composite. In order to describe the cavitation of the rubber particles, a criterion of void nucleation is implemented in the finite-element (FE) code. A comparison of the numerically predicted response with experimental result indicates that the numerical homogenisation analysis gives satisfactory prediction results.     

Olive stones based carbon foam: synthesis,characterization and application on post-combustion CO2 adsorption

Journal of Porous Materials - In the present paper, the performance of carbon foams to adsorb CO2 in post-combustion conditions using a thermo-gravimetric analyzer was investigated. Two types of...     

A projected fast ISTA algorithm for joint beam forming and antenna selection in massive MIMO

Wireless Networks - The joint beam-forming and antenna selection problem encountered in modern multi-user massive multiple input multiple output (MIMO) communication systems is solved using the...     

Application of genetic algorithm to color recipe formulation using reactive and direct dyestuffs mixtures

Color reproduction is a science in constant development. In this article, a new model to solve the color recipe prediction problem using a genetic algorithm is proposed. The objective is to optimize the color recipe prediction stage by determining the dyes to use in a mixture and their respective proportions to reproduce the target color. Two ranges of dyes were used for dyeing 100% cotton woven fabrics: three reactive dyes (CI Reactive Red 238, CI Reactive Yellow 145, and CI Reactive Blue 235) and four direct dyes (CI Direct Orange 34, CI Direct Red 227, CI Direct Blue 85, and CI Direct Black 22). The criterion of optimization, in reproducing the desired shades, is to minimize the CMC color difference between the desired reference color and the color resulting of the predicted recipe. The proposed algorithm revealed good results with small CMC color differences between target and reproduced colors. The effectiveness of the algorithm was also evaluated and proven by calculating errors between the predicted concentrations in the proposed recipes and the actual concentrations.     

Elemental chlorine-free bleaching halfa pulp

Halfa, also known as Stipa tenacissima, is grown in North Africa and south Spain. Due to its short fiber length, paper of halfa remains bulk and takes the block letters well. In this study halfa was evaluated for bleached pulp production. Two cellulose pulps with different chemical compositions were pulped by conventional Kraft process: one from the original halfa material and the other from halfa pretreated by diluted acid. The pulp produced from halfa pretreated by diluted acid was bleached by elemental chlorine-free sequences, DEPD and DEDP. Yield, Kappa number, brightness and α-cellulose contents of bleached and unbleached pulps were evaluated. The results show that during the chemical pulping process, treated halfa was easily cooked than that original halfa. Treated halfa pulp also showed very good bleaching, showing brightness level of 94.8% ISO, yield 93.6% and α-cellulose content 96.8% with DEDP bleaching sequence compared to 83.2% ISO brightness level, 92.8% yield and 95.1% α-cellulose content for bleached pulp with DEPD bleaching sequence. On the other hand, the physicomechanical properties of pulp were not notably reduced by the bleaching process. Breaking length, tear and burst index of paper sheets were acceptable. Therefore, this halfa material could be a worthwhile choice for cellulosic fiber supply.     

Preparation and Evaluation of Some Polymeric Basalt Composites

Unsaturated polyester based on poly(ethylene, 1,2, propylene ma-leate-phthalate-adipate) was synthesized and used with the styrene monomer as a binder to produce polymeric basalt composites (PBC). The physical properties of the styrenated polyester resin (SP) were determined. Because the aggregate type and composition do affect the durability properties of the composites, the minerological, textural, and chemical composition of the basalt Filler were studied. The mix design for the PBC systems was optimized for workability, strength, and economy. The optimum composition was 10wt% resin and 90wt% oven-dried basalt.

The mechanical and durability properties of the prepared PBC have been investigated. The physical, mechanical, and thermal properties of the composites appear to be satisfactorily good. Excellent chemical resistance to most chemical environments was also noted. The dielectric constant (?′) values indicated that the use of basalt as a filler enhances the electrical characteristics of the PBC as insulators as compared to the SP resin. Obviously, the obtained PBC would be excellent candidates for several potential applications.     

Widespread infection of lake whitefish Coregonus clupeaformis with the swimbladder nematode Cystidicola farionis in northern lakes Michigan and Huron

We estimated the prevalence, intensity, and abundance of swimbladder nematode infection in 1281 lake whitefish (Coregonus clupeaformis) collected from four sites in northern lakes Huron (Cheboygan and DeTour Village) and Michigan (Big Bay de Noc and Naubinway) from fall 2003 through summer 2006. Morphological examination of nematode egg, larval, and mature stages through light and scanning electron microscopy revealed characteristics consistent with that of Cystidicola farionis Fischer 1798. Total C. farionis prevalence was 26.94%, while the mean intensity and abundance of infection was 26.72 and 7.21 nematodes/fish, respectively. Although we detected C. farionis in all four stocks that were examined, Lake Huron stocks generally had higher prevalence, intensity, and abundance of infection than Lake Michigan stocks. A distinct seasonal fluctuation in prevalence, abundance, and intensity of C. farionis was observed, which does not coincide with reported C. farionis development in other fish species. Lake whitefish that were heavily infected with C. farionis were found to have thickened swimbladder walls with deteriorated mucosa lining, which could affect swimbladder function. Whether C. farionis infection may be negatively impacting lake whitefish stocks in the Great Lakes is unclear; continued monitoring of C. farionis infection should be conducted to measure responses of lake whitefish stocks to infection levels.     

Charged particle equilibrium effects on the electron absorbed fraction in the extrathoracic airways

Estimates of the dose to the extrathoracic airway (nasal vestibule) from inhaled beta-emitting radionuclides, obtained using the respiratory tract model presented in Publication 66 of the International Commission on Radiological Protection, frequently predict that the basal cells in this region are the most highly irradiated tissues of the body. The dose to the basal cells is averaged over a layer of tissue 10 microm thick located at a depth of 40 microm into the airway assuming that charged particle equilibrium exists. Since the target (basal cell layer) is very small and thin (10 cm(2) area and 10 microm thickness), charged particle equilibrium does not exist. In this work the effect on the absorbed fraction of the lack of charged particle equilibrium is investigated.     

Growth performance and shedding of some pathogenic bacteria in feedlot cattle treated with different growth-promoting agents

Eighty steers with a mean body weight of 319 kg were used in a study to evaluate the effect of a growth-promoting implant (trenbolone acetate plus estradiol benzoate), monensin, and oxytetracycline on the steer performance and shedding of some foodborne pathogens. The steers were allotted to one of eight treatment combinations according to a randomized complete block design with 16 pens of five animals. Rectal fecal samples were collected before treatment commenced and over a period of more than 24 weeks to study the influence of treatments on the intestinal microbiology of the animals. Results supported the beneficial effect of the hormonal implant on the performance of feedlot steers (average daily gain, feed efficiency, and fat thickness), on carcass characteristics (hot carcass weight, lean yield), and economic value of the carcasses (P < 0.01). The levels of Escherichia coli in feces were not affected by treatments but remained high throughout the study period. Antibiotic-resistant isolates of E. coli were more frequently found as the study progressed but were not associated with any specific treatment. Also independently of treatment, we observed a reduction over time in the shedding of Campylobacter and Yersinia during the feeding period, whereas the shedding of Enterococcus was increased. The results of this study confirmed the beneficial economic effect of growth-promoting agents in beef production and showed that the agents tested did not specifically affect the overall microbial evolution of the animal gut. However, the study also showed, independently of the growth promoter used, the shedding of Campylobacter, Yersinia, and antibiotic-resistant E. coli in the feedlot environment. These bacteria also may be found in the colonic tissue of steers at slaughter and might be a source of carcasses contamination.