Microstructural image analysis and structure–electrical conductivity relationship of single- and multiple-filler conductive composites

The electrical conductivity of polypropylene/graphite (PP/G) composites and polypropylene/graphite/carbon black (PP/G/CB) was investigated in this paper. The conductivity experimental data of PP/G composites was correlated to theoretical models, which exist in the literature, and the results showed higher values of the exponent t compared to the expected typical values. Moreover, these analytical models were unable to describe the electrical behaviour for multiple-filler conductive composites such as PP/G/CB composites. A 2D computer simulation to numerically compute the electrical conductivity based on digital image analysis was found to be somewhat useful to describe the mechanism of conduction in PP/G/CB composites and to determine the critical factors in developing high electrically conductive composites.     

A family of memristor‐based reactance‐less oscillators

In this paper, we present for the first time a family of memristor‐based reactance‐less oscillators (MRLOs). The proposed oscillators require no reactive components, that is, inductors or capacitors, rather, the ‘resistance storage’ property of memristor is exploited to generate the oscillation. Different types of MRLO family are presented, and for each type, closed form expressions are derived for the oscillation condition, oscillation frequency, and range of oscillation. Derived equations are further verified using transient circuit simulations. A comparison between different MRLO types is also discussed. In addition, detailed fabrication steps of a memristor device and experimental results for the first MRLO physical realization are presented. Copyright © 2013 John Wiley & Sons, Ltd.     

DRD2/ANKK1 TaqI polymorphism and smoking behavior of Egyptian male cigarette smokers.

Little is known about the genetic contribution to cigarette smoking and nicotine addiction in Egypt. The dopamine D2 receptor gene contains a TaqI repeat fragment length polymorphism creating two alleles with functional significance, DRD2*A1 and DRD2*A2. We investigated the relationship between these alleles and tobacco use in a study of 389 Egyptian male current smokers (mean age = 40 years; SD = 12). Participants were interviewed in 2004 on their smoking behaviors and quit attempts, and were given the Fagerstr?m Test for Nicotine Dependence (FTND). Blood samples were obtained and genotyped for DRD2 A1and A2 alleles. The frequencies of A1/A2, A1/A2, and A2/A2 genotypes were 6%, 29%, and 65%, respectively. We found no statistically significant association between genotype and age at onset of smoking, years of smoking, FTND score, or average number of cigarettes smoked per day. DRD2 genotype was associated with the number of cigarettes smoked in the past 48 hr (42.2 in A1 carriers vs. 37.6 in A2, p = .03), the previous quit duration (28% in A1 vs. 40% in A2 quit for more than 1 month, p = .05), and the depth of inhalation (82% in A1 vs. 72% in A2 inhaled the smoke deeply, p = .03). Logistic regression analysis including DRD2 genotype, FTND score, age at smoking initiation, marital status, and education as predictors showed that maximum duration of quit time was associated with FTND score (p = .003), DRD2 genotype (p = .01), marital status (p = .03), and age at smoking initiation (p = .04). These findings suggest a modest association between DRD2 genotype and quitting behavior in male cigarette smokers in Egypt.     

Assessment of the nutritional status of preschool-age children during the second Intifada in Palestine

BACKGROUND: The Palestinian economy has dramatically deteriorated at all levels since the Al-Aqsa Intifada (uprising) began in 2000, resulting in an unprecedented catastrophe to the livelihoods of the Palestinians residing in the West Bank and Gaza. It was also marked by lack of household physical and financial access to food and health care, which placed children at increased risk of malnutrition and poor health. This prompted a significant increase in food aid from 2002 until the summer of 2003. OBJECTIVES: To assess the nutritional status of children 6 to 59 months of age after 1 year of food assistance. METHODS: In the West Bank and Gaza, a nationally representative sample of children 6 to 59 months of age was randomly selected with a validated multistage clustered design, with the Health Survey 1999 sample used as the sampling frame. The sample was stratified according to governorate, place of residence (urban, nonurban, or refugee camp), locality, and size of locality (number of households). A cross-sectional survey of nutritional status was carried out. Data were collected by interviews with the primary caregivers of the children. Measurements were made of children's weight and height or length. Food-intake data were collected by the 24-hour food-recall method with the use of a booklet of photographs of foods commonly eaten in Palestine. RESULTS: A total of 3,089 children were assessed, of whom 3.1% in the West Bank and 3.9% in the Gaza Strip were suffering from acute malnutrition; the prevalence of chronic malnutrition was 9.2% in the West Bank and 12.7% in the Gaza Strip (p = .02). Sex, refugee status, locality, and maternal education were not significantly associated with acute malnutrition by logistic regression analysis, whereas infants 6 to 23 months of age were significantly at risk. Calorie and protein intakes were generally lower than recommended dietary allowances. CONCLUSIONS: The prevalence rates of both acute and chronic malnutrition among children in the West Bank and Gaza are significantly higher than the national Palestinian averages. There is a need to establish nutritional surveillance systems to monitor the nutritional status of children in conflict areas.     

Zur Polymerisation des Ethylens mit Vanadium(III)amid

Polymerization of Ethylene with Vanadium(III)amide By addition of AlEt₃, AlEt₂Cl or AlEtCl₂ to V(NPh₂)₃ · THF · 0,5 Dx. the polymerization of ethylene under normal conditions is started with increasing rate. The influence of the concentration of the catalyst components, the monomer concentration and the ageing time of the catalytic system on the rate is studied.     

Ion bombardment induced changes in the optical and electrical properties of polycarbonate

The changes in the optical and electrical properties of polycarbonate (PC) films, bombarded with He and Ar ion beams, have been studied. The PC films were divided into two groups where the first group was bombarded with 130 keV He ions of fluences ranged from 1 × 10¹⁴ cm⁻² to 2 × 10¹⁶ cm⁻², while the second one was bombarded with 320 keV Ar of fluences (1 × 10¹³ cm⁻² and 1 × 10¹⁵ cm⁻²). The surface morphology of the unirradiated and irradiated PC films was studied using scanning electron microscopy (SEM) technique. The optical properties of the two groups have been carried out using UV-Vis spectrophotometer and the direct current (DC) electrical conductivity was also performed. The obtained results showed a decrease in the optical energy gap, the optical activation energy and the electrical activation energy with increasing the fluence of both He and Ar ions. Meanwhile, an increase in the DC conductivity was obtained with increasing the fluence of the ions. The bombardment of the PC films with He and Ar ion beams induced formation of carbon clusters near the polymer surface and, also, resulted in scission in the polymer chains.     

Physico-Chemical Aspects on Uranium and Molybdenum Extraction from Aqueous Solution by Synthesized Phosphinimine Derivative Chelating Agent

Journal of Inorganic and Organometallic Polymers and Materials - To retain uranium and molybdenum ions from G.Gattar leach liquor (GI), North Eastern Desert, Egypt, a new fabricated chelating...     

The role of trust in government in crisis management: Fear of COVID-19 and compliance with social distancing

This study examines the mediating role of trust in government on the relationship between fear of coronavirus disease 2019 (COVID-19) and compliance with social distancing. A cross-sectional survey was conducted among 740 Jordanian citizens, and path analysis (SmartPLS 2.0) was conducted to analyze the data. Results show that fear of COVID-19 has a positive effect on both compliance with social distancing (t = 6.777, p = .000) and trust in government (t = 7.968, p = .000); trust in government has a positive effect on compliance with social distancing (t = 8.502, p = .000); and trust in government partially mediates the relationship between fear of COVID-19 and compliance with social distancing (Sobel test = 6.17, p = .000). The effect of fear of COVID-19 on compliance with social distancing, with trust in the government as a mediating variable, is greater than the direct effect without the mediating variable. Therefore, it is suggested that for social distancing measures imposed by the government on citizens to be effective, policymakers must work to enhance citizens' trust in the government and its measures aimed at curbing the outbreak of COVID-19. Limitations, implications, and suggestions for future research are discussed.