Influences of sex and seasons on levels of heavy metals in tissues of green tiger shrimp (Penaeus semisulcatus de Hann, 1844)

Seasonal changes in heavy metal (Ag, Cr, Ni, Pb, Cu, Fe, Zn) concentrations in muscle, gill, hepatopancreas and gonad tissues of both male and female green tiger shrimp (Penaeus semisulcatus) from Iskenderun Bay (Northern East Mediterranean Sea, Turkey) were measured for a year period by using ICP-AES. The relationships in various heavy metal concentrations in organs were compared according to sex and seasons. Heavy metal content varied with type of metals, seasons and sex. Accumulations also differed significantly in certain organs. Metal concentrations (as μg g⁻¹ w.w.) were highest in male gonads whereas lowest in the muscle of all shrimp species. From the human consumption point of view, heavy metal concentrations except for copper in male and female green tiger shrimp’s muscle were below the admissible limits. Thus, precautions should be taken on account of higher content of heavy metals as well as in other organs that could be affected by industrial pollution.     

Synthesis and characterization of thiophene functionalized polystyrene copolymers and their electrochemical properties

Thiophene functionalized polystyrene samples (TFPS) were synthesized by atom transfer radical polymerization (ATRP) of styrene, followed by Suzuki coupling with 3‐thiophene (Th) boronic acid. Conducting graft polymer of TFPS with thiophene was achieved at 1.5 V in tetrabutylammonium tetrafluoroborate/dichloromethane (TBAFB/DM) by electrochemical methods. Spectroelectrochemical analysis of the resulting copolymers [P(TFPS‐co‐Th)] reflected electronic transitions at 449, 721 and 880 nm, revealing π ? π* transition, polaron and bipolaron band formation, respectively. We also successfully established the utilization of dual type complementary colored polymer electrochromic devices using P(TFPS‐co‐Th)/poly(3,4‐ethylenedioxythiophene (PEDOT) in sandwich configuration. The switching ability, stability and optical memory of the electrochromic device were investigated by UV–visible spectrophotometry and cyclic voltammetry. Device switches between brown and blue color with a switching time of 1.3 s were prepared with optical contrast (%ΔT) of 25 %. Copyright © 2005 Society of Chemical Industry     

3D Modeling of Ripping Process

Due to environmental constraints and limitations on blasting, ripping as a ground loosening and breaking method has become more popular than drilling and blasting method in both mining and civil engineering applications. The best way of estimating the rippability of rocks is to conduct direct ripping runs in the field. However, it is not possible to conduct direct ripping runs in all sites using different dozer types. Therefore, the utilization of numerical modeling of ripping systems becomes unavoidable. A complex ripping system can better be understood with three-dimensional (3D) models rather than two-dimensional models. In this study, 3D distinct element program called 3DEC was used to investigate the ripping process. First, the ripping mechanisms were investigated and then the individual factors that affect the rippability performance of dozers were reviewed. The rippabilities of rocks depend not only on the rock properties, but also machine or dozer properties. Thus, ripper production and rock rippability with D8 type of dozers were also determined by direct ripping runs on different open pit lignite mines within the scope of this research. Production values obtained from numerical modeling were compared with field production values obtained from the case studies. This comparison shows that the model gives consistent and adequate results. Hence, a link has been established between the field results and the 3D models.     

Microstructure evolution of Al–Si alloys under shear loading

In this paper, an attempt is made to predict the microstructure evolution in Al–Si alloy two-dimensional (2D) system under shear loading conditions. The importance of damage accumulation events in delamination wear is studied. The conducted molecular dynamics (MD) simulations are based on the Modified Embedded Atom Method (MEAM). As a result a cohesive zone type of model relating the shear stress and the shear displacement has been suggested.     

Database audit and control strategies

Database management systems are the primary tools of automated record keeping, reporting, auditing, and control. Although they have significantly improved the efficiency and speed of record keeping, the ability to detect errors and maintain quality has not kept pace. There are three major strategies of error detection, auditing, and control to maintain integrity. The three strategies are introduced, and compared in terms of efficiency and effectiveness in eliminating errors. The optimum timing of audits under each strategy is computed. One strategy is shown to be completely dominated by the others. Hybrid strategies involving various combinations of the three pure strategies are introduced, and their performance computed. Hybrid strategies are shown to outperform the pure strategies under most realistic conditions. Finally, optimum audit strategies are devised, and their parameters computed.     

What controls dynamics of droplet shape evolution upon impingement on a solid surface?

A shape coefficient is introduced to quantify droplet shape by measuring its similarity to a desired shape to enable the study of droplet shape evolution upon impingement on a solid surface. Parametric simulations are performed with an experimentally validated numerical model to determine the impact conditions to maximize the shape coefficient. Results show that the Weber number is the controlling factor that determines the maximum achievable shape coefficient and the time instant when it is achieved for small Ohnesorge numbers, whereas the Reynolds number becomes the key parameter defining the optimal shape when the Ohnesorge number is large. A regime map is also developed to define the regions where a desired droplet shape can be achieved without splash. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3071–3082, 2013     

Analysis of real oil prices via trend-cycle decomposition

The recent fluctuations in the oil prices have intensified the discussion on the dynamics and causes of real oil price changes. While the long-run component of real oil prices seems to have a stochastic trend, global real economic activity has been thought to generate important changes in real oil prices. Based on this argument, in this paper, we analyze the real oil prices within a trend-cycle decomposition framework, where we impose a stochastic trend and assume the cyclical term to be affected by global economic conditions. We also let the parameters vary over time to see whether shocks to trend and the cycle have changing effects on the real oil prices. As a result, we find that shocks to trend are more persistent recently. In that sense, this paper contributes to the literature by offering an explanation for the increased volatility in oil prices. In addition, we show that global economic activity contributed also to the previous oil price shocks, which were regarded mainly as supply-side driven.     

The effect of land-cover change on vegetation greenness-based satellite agricultural drought indicators: a case study in the southwest climate division of Indiana,USA

During the last decade, the use of the normalized difference vegetation index (NDVI) for drought monitoring applications has drawn many criticisms, mainly because a number of drivers such as land-cover/land-use change, pest infestation, and flooding may depress the NDVI, further causing false drought identification. In this study, the impacts of land-cover change on the NDVI-derived satellite drought indicator, the vegetation condition index (VCI), are presented. It was found that the VCI is sensitive to changes in land cover, especially deforestation, the land cover changes from evergreen and deciduous forests to other land-cover classes. However, because the scale of land-cover changes was very small across the study area, only trivial drought alerts were observed in the VCI-based drought maps during non-drought years. Because drought is a large-scale climate event, it is reasonable to neglect these alerts. Besides, when the VCI was averaged to climate division scale, the results obtained through the VCI method were in good agreement with those acquired by the meteorological data-based drought indices such as the Palmer drought severity index and standardized precipitation index.     

Electrospinning of single and multilayered scaffolds for tissue engineering applications

Optimized electrospinning conditions were applied to produce single and multilayered (ML) scaffolds composed of polycaprolactone, collagen and elastin. The ML scaffold was cross-linked with glutaraldehyde to increase the stability. Morphological and structural characteristics of the scaffolds were measured by SEM and FTIR analyses. Results revealed that polymers combined to each other well and uniform fibers were obtained with the diameters ranging from 156 ± 53 to 1536 ± 293 nm. Contact angle measurements were performed to investigate the hydrophilic character of each structure. It was observed that incorporation of the natural polymers into the blends increased the hydrophilicity. Mechanical tests proved that collagen contributed to fabricate stiffer structures while elastin provided more elasticity. Biocompatibility of the scaffolds was examined by SEM analysis and WST-1 test with mouse fibroblast cells (L929) in vitro. Results exhibited that the addition of natural polymers increased the cell growth, and none of the single and ML scaffolds presented cytotoxic effect.     

The effect of long-term ambient aging on the mechanical properties of conducting polysiloxane-polypyrrole graft copolymers

The mechanical behavior of conducting polysiloxane-polypyrrole graft copolymers has been investigated as a function of ambient oxidative aging period. Graft copolymers of N-pyrrolyl-terminated polydimethylsiloxane (SPPy) with pyrrole were synthesized electrochemically at constant potential by using p -toluene sulfonic acid as the supporting electrolyte. Mechanical tests were performed on both unwashed and dichloromethane -washed copolymers after aging. An initial decrease followed by an increase in the tensile strength and strain values was observed with aging. The conductivities and mechanical properties of the films were determined to remain almost unchanged after 6 months of aging at about 46 S/cm.