Various Scale Levels of the Gel-to-Glass Transformation

The gel-to-glass transition in SiO₂ xerogels prepared by inorganic sol-gel synthesis was studied. The evolution of the molecular structure is traced using the infrared and lowfrequency Raman spectroscopy methods. The elastic moduli of the samples as well as the pore wall moduli at various stages of heat treatment are determined from the data on Brillouin scattering. The formation of monolithic glass on the macroscopic level manifests itself within a narrow temperature range by the dramatic increase of Young's modulus to the accepted value for fused silica. This phenomenon coincides with structural transformations on the molecular scale: (i) the definite correlation radius (the long-range order sphere) appears; (ii) local distortions of the silica network relax. The presence of structural defects influences the kinetics of vitreous SiO₂ formation during xerogel heat treatment.     

Reactions of fuel-nitrogen compounds under conditions of inert pyrolysis

As part of a study of the chemical mechanisms involved in the conversion of fuel-nitrogen compounds to nitric oxide during combustion, fossil fuels and model nitrogen compounds were pyrolysed in helium in a small quartz flow reactor. Hydrogen cyanide was the major nitrogen-containing product obtained in all cases indicating that hydrogen cyanide is formed during the initial pre-flame stages of combustion and is the principal intermediate in the formation of fuel nitric oxide. At a nominal residence time of one second, 50% decomposition of pyrrole, quinoline, benzonitrile and pyridine occurs at 905, 910, 922 and 954 °C, respectively. The fraction of the nitrogen in pyridine that is converted to hydrogen cyanide increases from 40% at 960 °C to 100% at 1100 °C. Benzonitrile produces similar amounts of hydrogen cyanide (49 and 82%). The hydrogen cyanide yields from coals and residual fuel oils increase from the range of 15–25% at 950 °C to 23–42% at 1100 °C. It is not possible to determine from these single-stage experiments if most of the hydrogen cyanide forms in the primary pyrolysis process or in secondary reactions.     

Gypsy moth mating disruption: Dosage effects

Small (1-hectare) plots in a dense gypsy moth (Lymantria dispar) infestation were treated with 5, 50, or 500 g racemic disparlure, and effects on male trap catch and mating behavior were studied. Capture of males in traps baited with 1, 10, 100, or 1000 g (+)-disparlure declined as disruptant dosages increased. Traps with high levels of attractant caught moths when capture in those with lower baitings was dramatically reduced. While all disruptant dosages reduced trap catch, it was reducd at least 95% at all attractant levels at the 500-g disruptant application rate. Visual estimates indicated that male moth density was similar in treated and control plots; female mating success was reduced 6.5, 34.5, and 84% in plots with 5, 50, and 500 g/ hectare disruptant, respectively. The duration of precopulatory and copulatory periods was similar for all females that were observed mating, regardless of disruptant treatment. It is proposed that reduced trap catch and female mating success are due to effects of atmospheric synthetic disparlure (disruptant) camouflaging natural attractant point sources.Lepidoptera: Lymantriidae.     

Determination of the Composition of Commercial Tannin Extracts by Liquid Secondary Ion Mass Spectrometry (LSIMS)

The composition of various commercial tannin extracts were determined by liquid secondary ion mass spectrometry (LSIMS). Spectra were obtained directly from tannin extracts without any pre-separation. Eight different tannin powders were analysed: three gallotannins (Chinese, Turkish, tara), three ellagitannins (sweet chestnut, pendunculata oak, sessile oak), one mixed hydrolysable tannin (myrabolans) and one proanthocyanidin (grape seeds). This method enabled the main molecules in these powders to be identified.     

Editorial: Security and Privacy Protection for Mobile Applications and Platforms

Mobile Networks and Applications -     

Computation offloading balance in small cell networks with mobile edge computing

Wireless Networks - As a promising way to offset the low computation capacity of user equipments (UEs), mobile edge computing (MEC) has attracted great attention of academy and industrial recently....     

Programmable CMOS CNN Cell Based on Floating-gate Inverter Unit

At present, the Cellular Neural Network (CNN) is a potential parallel structure able to perform image processing tasks in real-time when is effectively implemented in CMOS technology. The CNN silicon integration success is due mainly to the local connectivity of processing cells. In this work, an alternative design based on floating-gate MOS inverters is presented, which uses unipolar signals for solving binary tasks. The approach brings a fast response in a reduced silicon area, as shown through electrical simulations. A prototype cell in CMOS technology (AMI, 1.2 micron) was fabricated and tested for eight image processing tasks.

Caring for a family member with a traumatic brain injury

The responses to a questionnaire on subjective burden are reported for 52 primary caregivers of a group of persons with traumatic brain injuries sustained an average of 6 years previously. The aim of the study was to examine satisfaction with social support, perception of coping skills, and appraisal of symptoms as predictors of strain in the carers. A range of responses, both positive and negative, to the work of caring for a relative with a head injury was reported. A high prevalence rate of emotional and behavioural changes in the persons with head injuries was found and the amount of distress caused by these symptoms was found to be predictive of burden. The other factor important in predicting burden was the carers' ratings of their satisfaction with their ability to cope with the work of caregiving. Social support, injury severity, and the demographic characteristics of the persons with head injury and their carers were not significant predictors. Depression in the carers was also investigated and the variable most predictive of elevated depression scores was coping satisfaction. These findings reinforce the importance of strengthening carers coping resources in rehabilitation work with head injured persons and their families.