Modelling of composite crystallization

Metal matrix composites(MMCs)have received much attention due to their promising advanced mechanical properties.The aim of this work is to create a micro-macro model of composite crystallization.The developed model is coupled with the process of heat flow in the macroscopic scale,resulting from the heat emission during the nucleation and the growth of grains.Taking into account both of these phenomena,the proposed model is distinguished by a good reflection of reality.Moreover,the presented model assumes that the function of grain density depends on the maximal supercooling and the mass volume of the reinforcement phase particles.The knowledge of the equations,describing the function of grain density depending on the degree of supercooling,is necessary in the,more and more often used,numerical modelling of the casting structure.     

Effect of pig sex on consumer ratings for pork chops and bacon

The study was conducted to determine whether consumer acceptability of fresh and cured pork differed among gilt, intersex, cryptorchid, and intact male market pigs. Samples of chops and bacon from 12 animals of each sex were tested using 9-point hedonic scales for sensory characteristics. Androst-16-ene steroid levels, blood levels of testosterone and estrogen were determined, as was ‘taint’ by a fry test of fat. A significant sex effect for tenderness (P < 0·0092) and juiciness (P < 0·0095) resulted from chops of intact males being liked least. Low consumer ratings were usually texture related. Cryptorchid pigs varied most in eating characteristics being the only sex to exhibit significant differences for liking of aroma and flavour of chops. The few significant differences obtained for bacon were not related to those obtained for chops. Fry test and steroid levels were not related to liking with the exception of testosterone which reduced mean liking.     

Resulted word counts optimization—A new approach for better automatic image annotation

One of major problems in image auto-annotation is the difference between the expected word counts vector and the resulted word counts vector. This paper presents a new approach to automatic image annotation—an algorithm called resulted word counts optimizer which is an extension to existing methods. An ideal annotator is defined in terms of recall quality measure. On the basis of the ideal annotator an optimization criterion is defined. It allows to reduce the difference between resulted and expected word counts vectors. The proposed algorithm can be used with various image auto-annotation algorithms because its generic nature. Additionally, it does not increase the computational complexity of the original annotation method processing phase. It changes output word probabilities according to a pre-calculated vector of correction coefficients.     

Prüfkörperabdichtung und der Wasserabsorptionskoeffizient von mit Polypropylenfasern modifizierten Zementmörteln

Insulation of samples and water sorption coefficient of cement mortars modified with polypropylene fibres. In the following paper are shown results of water capillary suction in cement mortars prepared in accordance with 18 different recipes. All the mortars were prepared using natural quartz sand 0 to 2 mm. The mortars were varied with the use of two different cements and two different water‐cement ratios w/c, namely clean cement CEM I 42.5 R at w/c = 0.55 and ash cement CEM II/B‐V 32.5 R at w/c = 0.55 and w/c = 0.45. These mortars were modified by adding three types of polypropylene fibres with five lengths ranging from 3 to 38 mm. All samples were insulated against humidity on the side surfaces to ensure the one‐way water flow during the execution of this experiment. In relation to each type of mortar two different types of insulation were used: a silicone coat and polyethylene foil. The comparative analysis received served to evaluate the scale of reaction to the sorption coefficient A of such factors as: the type of cement, the w/c ratio, the type and length of fibres and the type of humidity insulation. It appeared that this last factor exerted a major effect on the course of the process, and equally on the A parameter when described in terms of quantity.     

Time-resolved photoluminescence spectroscopy of ligand-capped PbS nanocrystals

PbS nanocrystals are synthesized using colloidal techniques and have their surfaces capped with oleic acid. The absorption band edge of the PbS nanocrystals is tuned between 900 and 580?nm. The PbS nanocrystals exhibit tuneable photoluminescence with large non-resonant Stokes shifts of up to 500?meV. The magnitude of the Stokes shift is found to be dependent upon the size of PbS nanocrystals. Time-resolved photoluminescence spectroscopy of the PbS nanocrystals reveals that the photoluminescence has an extraordinarily long lifetime of 1?μs. This long fluorescence lifetime is attributed to the effect of dielectric screening similar to that observed in other IV-VI semiconductor nanocrystals.     

OH concentration and temperature measurements by use of near-resonant holographic interferometry

Near-resonant holographic interferometry is demonstrated to measure temperature and species concentration in a two-dimensional steady premixed air-acetylene flame. A peak temperature of (2600 +/- 100) K and a peak OH number density of (9.6 +/- 0.3) x 10(22) m(-3) are obtained, consistent with the expected values for such a flame. These values are determined by recording interferograms with a laser assumed sufficiently detuned from line center so that pressure and temperature broadening can be ignored. The results are thus obtained without making prior assumptions on the temperature or pressure of the flame beyond the existence of thermal equilibrium.     

Enhanced flow visualization with near-resonant holographic interferometry

Holographic interferometry measurements have been performed on high-speed, high-temperature gas flows with a laser output tuned near a resonant sodium transition. The technique allows the detection and quantification of the sodium concentration in the flow. By controlling the laser detuning and seeded sodium concentration, we performed flow visualization in low-density flows that are not normally detectable with standard interferometry. The technique was also successfully used to estimate the temperature in the boundary layer of the flow over a flat plate.     

Kinetic properties of the periplasmic hydrogenase from Desulfovibrio desulfuricans NCIMB 8372 and use in photosensitized H2-production

The periplasmic hydrogenase (hydrogen: ferricytochrome-c₃ oxido-reductase EC 1.12.2.1) from Desulfovibrio desulfuricans (NCIMB 8372) was isolated and the catalytic properties of the enzyme determined with different electron mediators. In the direction of H₂-oxidation with the physiological electron mediator cytochrome c₃, the value of the apparent second order rate constant (k_cat/K_m) is close to that expected for a diffusion-controlled reaction. In H₂-production however, the value of k_cat/K_m with cytochrome c₃ is almost 200 times lower. When methyl viologen is used as mediator, the value of k_cat/K_m is the same in both directions and is intermediate to the values obtained with cytochrome c₃. The close to optimum value of k_cat/K_m in H₂-oxidation with cytochrome c₃ as electron acceptor is discussed with respect to the biological role of this and related hydrogenases. H₂-production occurred with the hydrogenase in a system where the mediator was reduced with either of three photosensitizers (proflavin, 5-deazariboflavin, Zn-tetraphenyl porphyrin sulphonate) upon illumination. The efficiency of different mediators is discussed.     

Dialdehyde Starch Nanocrystals as a Novel Cross-Linker for Biomaterials Able to Interact with Human Serum Proteins

In recent years, new cross-linkers from renewable resources have been sought to replace toxic synthetic compounds of this type. One of the most popular synthetic cross-linking agents used for biomedical applications is glutaraldehyde. However, the unreacted cross-linker can be released from the materials and cause cytotoxic effects. In the present work, dialdehyde starch nanocrystals (NDASs) were obtained from this polysaccharide nanocrystal form as an alternative to commonly used cross-linking agents. Then, 5–15% NDASs were used for chemical cross-linking of native chitosan (CS), gelatin (Gel), and a mixture of these two biopolymers (CS-Gel) via Schiff base reaction. The obtained materials, forming thin films, were characterized by ATR-FTIR, SEM, and XRD analysis. Thermal and mechanical properties were determined by TGA analysis and tensile testing. Moreover, all cross-linked biopolymers were also characterized by hydrophilic character, swelling ability, and protein absorption. The toxicity of obtained materials was tested using the Microtox test. Dialdehyde starch nanocrystals appear as a beneficial plant-derived cross-linking agent that allows obtaining cross-linked biopolymer materials with properties desirable for biomedical applications.