Miscibility in poly-p-phenylene terephthalamide/nylon 6 and nylon 66 molecular composites

Miscibility and crystallization of poly-p-phenylene terephthalamide (PPTA)/nylon 6 and nylon 66 composites prepared by coagulation of isotropic ternary sulfuric acid solutions were studied. The apparent crystallinity of nylon 6 and nylon 66 in molecular composites was investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy. The solvation of nylon 6 crystals in PPTA matrix was observed when the PPTA content exceeds 70 wt%. Cross-hydrogen bonding seems to be responsible for the virtual disappearance of nylon 6 crystals. Specific interaction between PPTA and nylon 6 macromolecules and phase separation during thermal treatment has been discussed.     

Mechanical properties of nanostructured Mg–5 wt%Al–x wt%AlN composite synthesized from Mg chips

In the present investigation, Mg chips are recycled to produce nanostructured Mg–5wt%Al reinforced with 1, 2 and 5 wt% nanosized AlN particulates by mechanical milling (MM). Each batch of composite mixture was milled for different milling durations to produce different degrees of grain refinement. The mechanical properties such as tensile strength, ductility and hardness with respect to the effect of grain refinement, in other words, milling duration were studied. It was found that grain size played an important role in controlling ductility of the composites.     

Automation of the use of fluorescent microspheres for the determination of blood flow

Fluorescent-labeled microspheres (FM) are a new tool for the determination of organ blood flow. However, the FM-method is labor intensive, because of the necessity to recover the microspheres from the tissue samples. The aim of this study was to automate the FM-method. A Zymate-Robotic System (Zymark, Idstein, Germany) was modified to handle a novel filtration device. The robot is surrounded by 12 different stations which are necessary to process the samples. It performs the sequential steps which are needed to recover the microspheres from the samples. The dyes are finally released from the FM with a solvent and their fluorescent intensity is measured online using a spectrophotometer (Perkin Elmer, Uberlingen, Germany). The robotic system is able to recover the FM through digestion and filtration of the tissue samples using the new filter, to dissolve the FM and to release the dyes so that their fluorescent intensities can be measured for the calculation of organ blood flow.     

Multi-cyber framework for availability enhancement of cyber physical systems

With the rapid growth of wireless communication, the deployment of cyber-physical system (CPS) is increasing day by day. As a cyber physical system involves a tight coupling between the physical and computational components, it is critical to ensure that the system, apart from being secure, is available for both the cyber and physical processes. Traditional methods have generally been employed to defend an infrastructure system against physical threats. However, this does not guarantee that the availability of the system will always be high. In this paper, we propose a multi-cyber (computational unit) framework to improve the availability of CPS based on Markov model. We evaluate the effectiveness of our proposed framework in terms of availability, downtime, downtime cost and reliability of the CPS framework.     

Test bed for power amplifier behavioral characterization and modeling

Traditional test bed of power amplifier (PA) behavioral characterization and modeling based on vector signal analyzer (VSA) and often equipped with specialized software is both expensive and inflexible to modify to suit different scenarios. In this paper, a new test bed based on an oscilloscope or other general purpose data acquisition systems, which works as analog to digital converter (ADC) with a proper (radio frequency) RF bandwidth and maximum sampling rate, is proposed. The common impairments, e.g. transmitter IQ imbalances, channel delay, frequency offset, and carrier phase offset, are all well compensated. The accurately recovered envelopes of the PA’s input and output signals are used for a PA behavioral characterization and modeling. Furthermore, Relative envelope error (REE) parameter is proposed to evaluate the accuracy of envelope recovery. The experiment shows a very accurate RF signal envelope recovery, and a good performance of PA behavioral modeling.     

Large amplitude flexural vibration of rectangular plates

By using an approximate formulation due to Berger it is shown that the vibration of rectangular plates with large amplitudes may be treated in a simple and unified manner. Numerical results are given for various boundary conditions.     

Haplotype mapping of a major quantitative-trait locus for fetal hemoglobin production, on chromosome 6q23

Fetal hemoglobin (Hb F) and fetal cell (FC) levels in adults show considerable variation and are influenced by several genetic variants; the major determinants appear to be unlinked to the beta-globin gene cluster. Recently, a trans-acting locus controlling Hb F and FC production has been mapped to chromosome 6q23 in an Asian Indian kindred that includes individuals with heterocellular hereditary persistence of Hb F (HPFH) associated with beta thalassemia. We have extended the kindred by 57 members, bringing the total studied to 210, and have saturated the region with 26 additional markers. Linkage analysis showed tight linkage of the quantitative-trait locus (QTL) to the anonymous markers D6S976 (LOD score 11.3; recombination fraction .00) and D6S270 (LOD score 7.4; recombination fraction .00). Key recombination events now place this QTL within a 1-2-cM interval spanning approximately 1.5 Mb between D6S270 and D6S1626. Furthermore, haplotype analysis has led to a reevaluation of the genealogy and to the identification of additional relationships in the kindred.     

Molecular weight and concentration effects on gel/sol transitions in a segmented rigid-rod polyimide solution

Gel/sol and order/disorder transitions can be observed in a segmented rigid-rod polyimide solution at different concentrations and molecular weights. This polyimide was synthesized from 3,3′,4,4′-biphenyltetracarboxylic dianhydride and 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl in refluxing 3-cresol in a one-step process. Above about 140°C, the polymers are completely soluble in 3-cresol in a concentration range up to 12(w/w)%. During cooling, the hot solutions undergo a mechanical sol/gel transition to form thermally reversible gels. In the gel state, an ordered structure develops. Both the gel/sol and order/disorder transitions are dependent upon concentration, temperature, and molecular weight, but the two transitions exhibit different kinetics. Possible mechanisms of these transitions are discussed.