Melt Rheological Behavior and Creep Response of EVA/TPU Blends: Exploring the Effect of Electron Beam Irradiation and Peroxide Cross-linking

The present study focuses on the variation of the melt rheological characteristics and the creep behavior of both electron beam-cross-linked and peroxide-cured ethylene vinyl acetate/thermoplastic polyurethane blends. The variation of complex viscosity, complex modulus, storage modulus, and loss modulus was evaluated over a wide range of frequency and strain amplitude using rubber process analyzer and the effect of radiation dose and peroxide concentration was investigated in detail. The creep study using dynamic mechanical analyzer shows that the creep behavior of the blends significantly improves after cross-linking and the creep compliance gradually decreases with the increasing radiation dose and peroxide content. An attempt was also made to pursue a comparative rheological and creep study among the peroxide-cured, electron beam-cross-linked and the coagent-treated dynamically vulcanized samples.     

Characterization of Morphological Changes in Agglomerates Subject to Condensation and Evaporation Using Multiple Fractal Dimensions

Multiple fractal dimensions are used to characterize morphological changes that occur when an aerosol composed of irregularly shaped agglomerates is subject to condensation followed by evaporation. The agglomerates change from a branched, chainlike structure to a more regular, near-spherical or clumplike structure reflected in a decrease in the structural fractal dimension. The textural fractal dimension remains constant because the primary particles, of which the agglomerates are composed, do not change in shape. The degree of supersaturation and the number of condensation-evaporation cycles that the aerosol undergoes are major factors that influence morphological change. Even at low supersaturations, increasing the number of condensation-evaporation cycles makes the agglomerates more regular and thus decreases the structural fractal dimension. The transition point in the Richardson plot is a good indicator of the size of the primary particles in the agglomerate.     

Local and Regional Secondary Organic Aerosol: Insights from a Year of Semi-Continuous Carbon Measurements at Pittsburgh

We present Scanning Mobility CCN Analysis (SMCA) as a novel method for obtaining rapid measurements of size-resolved cloud condensation nuclei (CCN) distributions and activation kinetics. SMCA involves sampling the monodisperse outlet stream of a Differential Mobility Analyzer (DMA) operated in scanning voltage mode concurrently with CCN and condensation particle counters. By applying the same inversion algorithm as used for obtaining size distributions with a scanning mobility particle sizer (SMPS), CCN concentration and activated droplet size are obtained as a function of mobility size over the timescale of an SMPS scan (typically 60–120 s). Methods to account for multiple charging, particle non-sphericity, and limited counting statistics are presented. SMCA is demonstrated using commercial SMPS and CFSTGC instruments with the manufacturer-provided control software. The method is evaluated for activation of both laboratory aerosol and ambient aerosol obtained during the 2004 NEAQS-ITCT2k4 field campaign. It is shown that SMCA reproduces the results obtained with a DMA operating in voltage “stepping” mode.     

Analysis of MTHFR and MTRR Gene Polymorphisms in Iranian Ventricular Septal Defect Subjects

Ventricular septal defect (VSD) is one of the most common types of congenital heart defects (CHD). There are vivid multifactorial causes for VSD in which both genetic and environmental risk factors are consequential in the development of CHD. Methionine synthase reductase (MTRR) and methylenetetrahydrofolate reductase (MTHFR) are two of the key regulatory enzymes involved in the metabolic pathway of homocysteine. Genes involved in homocysteine/folate metabolism may play an important role in CHDs. In this study; we determined the association of A66G and C524T polymorphisms of the MTRR gene and C677T polymorphism of the MTHFR gene in Iranian VSD subjects. A total of 123 children with VSDs and 125 healthy children were included in this study. Genomic DNA was extracted from the buccal cells of all the subjects. The restriction fragment length polymorphism polymerase chain reaction (PCR-RFLP) method was carried out to amplify the A66G and C524T polymorphism of MTRR and C677T polymorphism of MTHFR genes digested with Hinf1, Xho1 and Nde1 enzymes, respectively. The genotype frequencies of CC, CT and TT of MTRR gene among the studied cases were 43.1%, 40.7% and 16.3%, respectively, compared to 52.8%, 43.2% and 4.0%, respectively among the controls. For the MTRR A66G gene polymorphism, the genotypes frequencies of AA, AG and GG among the cases were 33.3%, 43.9% and 22.8%, respectively, while the frequencies were 49.6%, 42.4% and 8.0%, respectively, among control subjects. The frequencies for CC and CT genotypes of the MTHFR gene were 51.2% and 48.8%, respectively, in VSD patients compared to 56.8% and 43.2% respectively, in control subjects. Apart from MTHFR C677T polymorphism, significant differences were noticed (p < 0.05) in C524T and A66G polymorphisms of the MTRR gene between cases and control subjects.     

Effect of SiC on Mechanical and Microstructural Characteristics of Al Based Functionally Graded Material

Silicon - In this study, an attempt was made to enhance the mechanical and microstructural properties of aluminium (Al) based FGM with the influence of silicon carbide (SiC) elements. The five...     

Corrosion of carbon steel feeders during dilute chemical decontamination of primary heat transport system of PHWRs

Carbon steel feeders in the primary heat transport system of pressurized heavy water reactors (PHWRs) show significant wall thinning due to flow accelerated corrosion (FAC). This is of great concern, as the wear rate in certain locations exceeds the corrosion allowance by design. This necessitates periodic measurement of wall thickness and in some cases even mid course enmasse replacement of feeders. While analyzing the data on wall thicknesses and in arriving at the wall thinning rate during operation of the reactor, sufficient care has to be taken to account for the wall thinning occurring during full system chemical decontamination campaign which is carried out occasionally to reduce dose rates during reactor shut down. Chemical decontamination of primary heat transport system is carried out using a mixture of organic acids at a total concentration of about 0.1 g/L and at 85 °C. The results of experiments carried out under simulated conditions for estimating the wall thinning occurring in carbon steel feeder elbow during dilute chemical decontamination are described in this work. The corrosion rates are quantified.     

A novel adaptive sampling based methodology for feasible region identification of compute intensive models using artificial neural network

Identification of feasible region of operations in multivariate processes is a problem of interest in several fields. This is particularly challenging when the process model is black-box in nature and/or is computationally expensive, as analytical solutions are not available and the number of possible model evaluations is limited. An efficient methodology is required to identify samples where the model is evaluated for developing a computationally efficient surrogate model. In this work, an artificial neural network based surrogate model is proposed which is integrated with a statistical-based approach (Jack-knifing) to estimate the variance of the surrogate model prediction. This allows implementation of an adaptive sampling approach where new samples are identified close to the feasible region boundary or in regions of high prediction uncertainty. The proposed approach performs better than a previously published kriging based method for different dimensionality case studies.     

Modularization of a Large-Scale Business Application: A Case Study

Large software systems, developed over several years, are the backbone of industries such as banking, retail, transportation, and telecommunications. With multiple bug fixes and feature enhancements, these systems gradually deviate from the intended architecture and deteriorate into unmanageable monoliths. This article presents a case study of a banking application besot with such problems and the modularization approach that the company adopted as a solution. It also highlights benefits unearthed as a result of this reengineering exercise.     

Flexible Hardware Acceleration for Instruction-Grain Lifeguards

Instruction-grain lifeguards monitor executing programs at the granularity of individual instructions to quickly detect bugs and security attacks, but their fine-grain nature incurs high monitoring overheads. This article identifies three common sources of these overheads and proposes three techniques that together constitute a general-purpose hardware acceleration framework for lifeguards.