Effect of the B<Subscript>4</Subscript>C content on the structure and thermal expansion coefficient of the Al–5% Cu alloy-based metal-matrix composite material

The Al–5% Cu alloy-based metal-matrix composite materials reinforced with 5-μm B₄C particles have been produced using mechanical mixing-in method. A process of addition of the B₄C particles into the melt has been developed. A homogeneous distribution of the B₄C reinforcing particles in the metal-matrix composite matrix was obtained. Using X-ray diffraction analysis, the formation of Al₃BC and AlB₂ phases has been revealed at the interphase matrix/particle boundary, which indicates a good interaction in the phases. With increasing B₄C content in the matrix alloy, an insignificant increase in the porosity (from 1 to 3.1%) occurs. The average linear thermal-expansion coefficient is reduced from 24.5 to 22.6 × 10^–6 K^–1 in the temperature range of 20–100°C.     

Liquid crystal behavior of cellulose nanoparticles-ethyl cellulose composites: Preparation,characterization, and rheology

This work deals with assessing the approach for preparation of cellulose nanoparticles (CNPs) to be acted as synergistic component in liquid crystal (LC) ethyl cellulose composite (EC-CNPs). In this respect different structures of CNPs were prepared by acid and salt agents. These prepared CNPs were characterized by carboxyl content, IR, transmission electron microscope (TEM), and zeta potential, while their composites with EC were characterized by rheological measurements as a key factor for measuring the critical concentration of LC behavior. The results showed that, the crystallinity of CNPs obtained by ammonium persulfate exceeded that prepared by sulfuric acid hydrolysis. TEM images of stained CNPs showed both methods led to produce nanoparticles have rod like shape with aspect ratio (L/W) between 7.69 ± 3 and 31.3 ± 5. For the rheological measurements, it demonstrated the efficient of incorporating the CNPs to EC (EC-CNPs composites) to decrease the critical concentration of EC from 40 wt% to approximately 34 wt%.     

Enhancement of the electrical performance of poly(vinyl) alcohol by doping with chlorophyll and gamma irradiation

The electrical properties of poly(vinyl) alcohol (PVA) have been improved pronouncedly by doping with chlorophyll (Chl) and gamma irradiation. PVA/Chl films have been prepared and irradiated with γ-rays at dose levels of 10, 20, 30, 50, 70, 100, 150, 200 and 250 kGy. The crystalline and chemical structures of the samples have been studied using XRD and FTIR techniques. Also, the direct current electrical conductivity and the dielectric constant and loss have been determined for the proposed samples before and after gamma exposure. It is clearly shown that the electrical conductivity of PVA films was increased two orders of magnitude due to chlorophyll doping and about fifteen times due to gamma irradiation. Considering the dielectric constant and loss, their values were shown to increase significantly due to PVA doping with chlorophyll. The obtained results can be attributed to the existence of the conducting Mg atom, as well as, the conjugated double bonds in the chlorophyll. Moreover, the gamma irradiation of PVA/Chl, over 50 kGy, improves also this electrical performance. Therefore, the study suggests the possibility of the utilization of the gamma irradiated PVA/Chl films in different electronic applications.     

Thermal Ramp Type of Photo-Thermal Excitation in Hall Current and Variable Thermal Conductivity of Semiconductor Elastic Material

Silicon - In this article, the variable thermal conductivity which it depending on temperature gradient in context of the photothermal excitation process of a semiconductor elastic material is...     

Response of Thermo- Electro-Magneto Semiconductor Elastic Medium to Photothermal Excitation Process with Thomson Influence

Silicon - The effect of Thomson heating of semiconductor medium is studied. Analytical discussions are made in the presence of thermoelectricity theory and magnetic field in context of Photothermal...     

On the plane waves of generalized thermo-microstretch elastic half-space under three theories

A general model of the equations of generalized thermo-microstretch for a homogeneous isotropic elastic half space is given. The formulation is applied to generalized thermoelasticity theories, the Lord-?hulman and Green-Lindsay theories, as well as the classical dynamical coupled theory. The normal mode analysis is used to obtain the exact expressions for the displacement components, force stresses, temperature, couple stresses and microstress distribution. The variations of the considered variables through the horizontal distance are illustrated graphically. Comparisons are made with the results in the presence and absence of microstretch constants and between the three theories for two different times.     

Immobilization of some biomolecules onto radiation‐grafted polyethylene beads for possible use in immunoassay applications

Functionalization of polyethylene (PE) beads was accomplished via radiation induced graft copolymerization of acrylic acid/acrylamide (AAc/AAm) binary comonomer of different compositions onto such beads. Factors affecting the grafting yield were optimized and the occurrence of the grafted chains was confirmed by following the FTIR spectra of the grafted beads. SEM analyses were used to follow the variation of the morphology of the grafting and immobilization onto PE beads. Some bio‐active molecules such as Follicle‐stimulating hormone (FSH), Luteinizing hormone (LH), Thyroid‐stimulating hormone (TSH), and Prolactin were immobilized to the radiation functionalized PE beads. The parameters may affect the immobilization process such as degree of grafting, temperature, and pH of the coupling buffer and the coupling period were investigated. The obtained results show that the grafting of AAc offers a better immobilization environment than those of AAm and their copolymer. It is found that the highest immobilization degree would be achieved at pH 7 and 37°C for 24 h. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

An optimal open-loop multimode fiber gyroscope for rate-grade performance applications

We report the realization of a new version of a fiber optic gyroscope (FOG), using low-cost multimode fiber components. This is achieved by an optimal choice of the components such as fiber, coupler, light source and photodetector. The aim behind this work is to demonstrate the versatility of the low-cost multimode FOG for rate-grade performance applications. Both analog signal processing and open-loop operation are used in the proposed FOG experiment. The obtained sensitivity is ∼7°/h and the angle random walk is about 0.087°/. The influence of the coupler technology on the performances is investigated.     

Response of Semiconductor Medium of Variable Thermal Conductivity Due to Laser Pulses with Two-Temperature through Photothermal Process

Silicon - A novel model of variable thermal conductivity of semiconductor medium in two-temperature theory is studied. The Photothermal excitation due to laser pulses is investigated. The governing...     

Origin of Bahariya oil in Salam oil field,Western Desert- Egypt

The origin of Bahariya oil is a debatable issue. Bahariya Formation produces oil from the Lower sandstone unit by normal pressure mechanism, while the Upper Bahariya shale produces oil by fracking mechanism. The main question is: is there any genetic relationship between the two oils.To answer this question, “50” ditch samples, “12” extract samples and “2” oil samples represent Khatatba and Bahariya formations and Abu Roash ‘G’ Member, collected from six wells drilled in Salam oil field, have been geochemicaly analyzed, using LECO SC632, Rock–Eval- 6 pyrolysis, GC and GC/MS techniques.The analysis shows that the Total Organic Carbon content (TOC) for the studied formations ranges from fair to v.good, with poor to good hydrocarbon potentiality. The maturity evaluation using Tmax, and calculated Vitrinite reflectance (R_o) showed that the studied samples have good thermal maturation reaching the stage of oil generation. Also the analysis revealed that the kerogen is a mixture of type II/III kerogen, reflecting the potential generation of oil and gas. The GC and GC/MS data showed that the organic matter is a mixed marine/terrestrial input deposited in transitional environment under prevailing reducing conditions. The oil samples fingerprint of the saturated hydrocarbons fraction from Baharyia reservoir (Lower and Upper) members suggest that the oil samples have a mixed organic source with significant terrestrial organic matter input deposited under saline to hypersaline environment with slightly oxidizing environment.Based on the obtained results, it is suggested that the Bahariya oil has been sourced mainly from deeper horizons (Khatatba Formation) with some contribution from upper and lower Bahariya source rocks.