Reproductive outcomes of maternal contamination with cyclodiene insecticides, hexachlorobenzene and beta-benzene hexachloride

The effects of organochlorines on human reproduction have been recently under scrutiny. Some negative effects on animal reproduction have been reported. In this study we aimed to evaluate the effect of maternal contamination with a certain group of organochlorines, which are cyclodienes, HCB (hexachlorobenzene) and beta-BHC (beta-hexachlorocyclohexane) on human reproduction. Breast milk samples from 815 eligible Victorian mothers were used for measuring maternal contamination and the reproductive outcomes such as birth weight, head circumference and prematurity were taken from health files. Our study did not show any significant negative effect on outcomes such as birth weight, small for gestation age, previous miscarriage or still birth, head circumference or sex ratio. An inconsistent increase across oxychlordane exposure levels for prematurity was found. We also found an inverse association between the highest levels of HCB and oxychlordane with previous miscarriage or still birth; but this was based on small numbers and may be explained by loss of contaminants through the aborted fetus. These results suggest that the declining contamination levels of these chemicals do not impose a threat to human reproduction.     

Low-temperature synthesis of mesoporous nanocrystalline magnesium aluminate (MgAl2O4) spinel with high surface area using a novel modified sol-gel method

A simple, template-free and scalable modified sol-gel route was developed for the synthesis of mesoporous flake-like magnesium aluminate spinel (MgAl₂O₄) at low temperature (700 °C) with high surface area (281 m² g^?1). The obtained spinel materials were characterized by means of physicochemical techniques including X-ray diffraction, thermogravimetric analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and N₂ adsorption-desorption analysis. The propylene oxide was used as gelation and pore forming agent in the sol-gel process. Different morphologies and sizes of flake were generated by the varied synthesis conditions. The result materials reveal that the textural properties of the MgAl₂O₄ product are strongly associated with the nature and amount of addictive solvent and calcination temperatures. It shows that the BET surface area decrease as the increase of calcination temperature and the optimal temperature of 700 °C result in the pure phase of MgAl₂O₄ spinel. This synthesis strategy offers a feasible approach for scalable fabrication of mixed metal oxides for various catalytic reactions or catalyst supports due to the large surface area.     

Size dependent buckling analysis of nano sandwich beams by two schemes

Abstract

Within the framework of Timoshenko beam theory, the buckling of nano sandwich beams is developed. The material properties are assumed to vary arbitrarily in both axial and thickness directions. These types of beams are referred to as bi-directional functionally graded (BDFG) beams. Two types of nano sandwich beams with different material distribution patterns and immovable supports are considered. Since the size effects play a significant role in mechanical behavior of nanostructures, the small-scale effects are captured by Eringen’s nonlocal theory of elasticity. The governing equations are derived using the variational formulation. Symmetric smoothed particle hydrodynamics (SSPH) and the Galerkin method are adopted as numerical solution approaches. As a truly meshless method, the convergence of the SSPH technique mainly depends on the smoothing length value and distribution of particles in the compact support domain of the kernel function. The Revised Super Gauss Function is used as the kernel function and an optimum value for the smoothing length that bears the fastest convergence rate is obtained. The solution methods are verified through benchmark problems found in the literature. Numerical and illustrative results show that various parameters, including the aspect ratio, nonlocal parameter, gradient indexes, and cross-sectional types have significant effects on the buckling responses of BDFG nano sandwich beams.     

Mutations of the RET-GDNF signaling pathway in Ondine''s curse

Sarcoidosis is a multi-systemic granulomatous disease of unknown cause. It commonly involves lymph nodes, lungs, eyes, and skin. Cardiac sarcoid may be isolated, or associated with systemic involvement. Cardiac involvement is found in 20-50% of autopsied patients with sarcoidosis. However, it only gives rise to clinical manifestations in about 5% of patients. Cardiac involvement by sarcoid has been reported to manifest as complete heart block, papillary muscle dysfunction, congestive heart failure, pericarditis and/or effusion, conduction abnormality or arrhythmia, chest pain, and sudden death. The most common site of involvement is the interventricular septum base, which when involved may lead to heart block or arrhythmia. We report a case of sudden death in a 33-year-old male with a history of surgically repaired congenital heart disease. Although his congenital heart disease was originally postulated to be important in his death, autopsy examination revealed cardiac sarcoid with prominent involvement of the conduction system.     

A signal Processing system for extraction of harmonics and reactive current of single-phase systems

A signal processing system for extraction of harmonic and reactive current components is introduced and its performance is evaluated. The extraction system is adopted as part of the control system of a single-phase active power filter (APF) to provide the required signals for harmonic filtering and reactive power compensation. Performance of the overall system is evaluated based on digital time-domain simulation studies. The APF control system including the signal processing algorithms are implemented in Matlab/Simulink Fixed-Point Blockset to accommodate bit-length limitation which is a crucial factor in digital implementation. The power system including the APF, load and the supply system are simulated with the PSCAD/EMTDC software to which the Matlab-based control model is interfaced. The simulation results indicate that the signal processing unit can provide the required signals for APF to perform filtering/compensation within the transient period of 2 to 3 cycles.     

An efficient chaotic based PSO for earliness/tardiness optimization in a batch processing flow shop scheduling problem

The flow shop is a well-known class of manufacturing system for production process planning. The need for scheduling approaches arises from the requirement of most systems to implement more than one process at a moment. Batch processing is usually carried out to load balance and share system resources effectively and gain a desired quality of service level. A flow shop manufacturing problem with batch processors (BP) is discussed in current paper so as to minimize total penalty of earliness and tardiness. To address the problem, two improved discrete particle swarm optimization (PSO) algorithms are designed where most important properties of basic PSO on velocity of particles are enhanced. We also employ the attractive properties of logistic chaotic map within PSO so as to investigate the influence of chaos on search performance of BP flow shop problem. In order to investigate the suggested algorithms, a comprehensive computational study is carried out and performance of algorithms is compared with (1) a commercial optimization solver, (2) a well-known algorithm from PSO’s literature and (3) three algorithms from BP’s literature. The experimental results demonstrate the superiority of our algorithm against others.