Physico-Chemical Properties of the Egyptian Tamarind Seed Oil

The physico-chemical properties of the Egyptian Tamarind seed oil were investigated. The seeds were found to contain a fair amount of oil (16.25%). It was found that the oil has a high acid and iodine values in comparison with cotton seed oil. Arachidic, linoleic, oleic, stearic, palmitic, myristic, and lauric were fractionated by gas liquid chromatography from the tamarind seed oil. More than 50% of the total acids are unsaturated. The infrared spectroscopy showed the presence of 7 absorption bands at wave-number cm^?1 (730, 1150, 1380, 1480, 1750, 2900 and 2950) in the investigated oil. On the other hand chemical analysis of the cake showed a lower protein content and higher sugar content.     

A Comparative Study Between Electro and Magneto Excess Conductivities in FeTeSe Superconductors

We report here structural and fluctuation-induced excess conductivity in a FeTeSe superconductor by using the resistivity versus temperature measurements at different values of independent currents and applied fields (I = 1, 10, 50, and 100 mA, H = 0; H = 1, 3, 6, and 9 T, I = 10 mA). The prepared sample is investigated by using X-ray diffraction and standard four-probe technique using the resistivity option of PPMS-14 T. It was found that all peaks of the X-ray pattern are indexed as a tetragonal P4/nmm phase, and only a very small peak at about 2 ?? = 32.04^° is obtained. The lattice parameters are a = b = 3.802(5) Å and c = 6.070(2) Å, and the medium size of crystallites is about 32 nm. Regardless of magnetic field for simplicity and by using Aslamazov and Larkin expression, the logarithmic plots of Δσ and reduced temperature (ε), for both cases of different currents and fields, reveal three different conductivity exponents in the slope of each plot corresponding to two crossover temperatures. This is due to shifting of the order parameter dimensionality from short wave (SW) to two-dimensional/one-dimensional (2D/1D) and from 2D/1D to three-dimensional (3D), respectively. Furthermore, we estimated several physical parameters such as coherence lengths, Ginsburg number, anisotropy, G-L parameter, critical magnetic fields, and critical current density. Moreover, we follow Ullah and Dorsey field-dependent approximation for 3D and 2D analyses to obtain the fluctuation induced magneto-conductivity in the presence of magnetic field. Interestingly, the values of the slopes, deduced from logarithmic plots of 3D and 2D field dependence, are consistent with the values of SW conductivity exponents in the normal field region. In the mean field region, the values of the slopes for 3D are consistent with 2D conductivity exponents at H = 1, 3, and 6 T and with 1D at H = 9 T, while the values of the slopes for 2D are consistent with 3D conductivity exponents at H = 3, 6, and 9 T and with 1D at H = 1 T. As the field increases and keeping the temperature close to T _c, the 3D curves seem to be slightly open like a fan, while the 2D curves are collapse together.     

Effect of Ar heat treatment on oxygenated R1−x Ca x Ba2Cu3O7−δ (R = Y, Sm) superconductors

The influence of heat treatment, at 450°C in Ar environment, on oxygenated (6.72 < 7 – < 6.93) samples of R_1–x Ca _x Ba₂Cu₃O_7– (i.e. R(Ca)-123, with R = Y, Sm) with 0 < x < 0.3 has been investigated. Measurements of oxygen loss, normal state resistivity behaviour (T), superconducting critical temperature T _c and transition widths reveal that Ar treatment effects both the series differently. The Sm(Ca)-123 samples, for all values of x, show a considerable loss of oxygen ((x) = 0.4 to 0.6) and decrease in T _c (T _c(x) = 35 to 55 K). Whereas, surprisingly, the Y(Ca)-123 samples show a much smaller loss of oxygen ((x) = 0 to 0.3), along with a decrease in T _c for x < 0.2 and an increase in it for x > 0.2. In particular, the x = 0.3 sample shows a negligible change in oxygen content accompanied by an increase of 20 K in T _c. These and host of other observations suggest that the presence of Ca may influence the oxygen loss mechanism in these series.     

Detecting oxidized contaminants in water using sulfur-oxidizing bacteria

For the rapid and reliable detection of oxidized contaminants (i.e., nitrite, nitrate, perchlorate, dichromate) in water, a novel toxicity detection methodology based on sulfur-oxidizing bacteria (SOB) has been developed. The methodology exploits the ability of SOB to oxidize elemental sulfur to sulfuric acid in the presence of oxygen. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH. When oxidized contaminants were added to the system, the effluent EC decreased and the pH increased due to the inhibition of the SOB. We found that the system can detect these contaminants in the 5-50 ppb range (in the case of NO(3)(-), 10 ppm was detected), which is lower than many whole-cell biosensors to date. At low pH, the oxidized contaminants are mostly in their acid or nonpolar, protonated form which act as uncouplers and make the SOB biosensor more sensitive than other whole-cell biosensors which operate at higher pH values where the contaminants exist as dissociated anions. The SOB biosensor can detect toxicity on the order of minutes to hours which can serve as an early warning so as to not pollute the environment and affect public health.     

Characterization of bolometers based on polycrystalline silicongermanium alloys

In this paper, we report on the first realization and characterization of uncooled Infra Red (IR) bolometers, based on polycrystalline alloys of silicon and germanium (poly SiGe). Responsivity, thermal conductance, thermal time constant and noise will be analyzed. It will be shown that poly SiGe provides high thermal insulation. An average detectivity of 10⁸ cm√(Hz)/W has been measured. We expect that modifications in the device structure could allow to achieve detectivities of 10⁹ cm √(Hz)/W     

Mechanical behavior and microhardness of swollen natural rubber loaded with carbon black

The mechanical behavior and microhardness characteristics of a natural rubber vulcanizate loaded with 40 phr high abrasion furnace carbon black swollen in kerosene were studied. The measured parameters (i.e., the Young's modulus, tensile strength, and elongation at break) varied with the swelling time in kerosene. The hardness degree decreased as the swelling time in kerosene increased. Different models were applied to describe this mechanical behavior. The Mooney–Rivilin relation agreed with the experimental data at low extension ratios, whereas the Blatz relation agreed at high extension ratios only. The strain rate sensitivity was taken into account to describe this mechanical behavior. The strain energy density as a function of the swelling time in kerosene was calculated with three different equations. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of localized KrF excimer laser treatment on fracture behaviors of freestanding <110> and <100> single crystal silicon beams

Microscale silicon structures oriented along <100> and <110> orientations were laser treated with different conditions with the cross section shape and tensile strength investigated after the treatment. Finite element simulation was performed to examine the temperature distribution at different conditions during laser treatment. Using a low energy (1.2 J/cm²) and high tilt angle (65°) led to a more preserved cross section with a slight strength improvement. The strength improvement was limited due to other surfaces that were not affected by laser treatment. An improvement of 30 % in tensile strength was achieved with a higher energy (4 J/cm²) lower tilt angle (45°) treatment that was consistent for different sample orientations. The cross section of the samples treated at such condition was significantly changed however. The effect of sample orientation on fracture behaviour was studied and unstable crack propagation was observed for <100> oriented samples that was more significant after laser treatment.     

Pulsed-laser annealing, a low-thermal-budget technique for eliminating stress gradient in poly-SiGe MEMS structures

In this paper, we demonstrate eliminating the stress gradient in polycrystalline silicon germanium films at temperatures compatible with standard CMOS (Al interconnects) backend processing. First, we study the effect of varying the germanium concentration from 40% to 90%, layer thickness, deposition pressure from 650 to 800 mtorr and deposition temperature from 400 to 450/spl deg/C, on the mechanical properties of SiGe films. Then the effect of excimer laser annealing (248 nm, 38 ns, 780 mJ/cm/sup 2/) on stress gradient is analyzed. It is demonstrated that stress gradient can be eliminated completely by depositing Si/sub x/Ge/sub 1-x/(10%相似文献   

New low-stress PECVD poly-SiGe Layers for MEMS

Thick poly-SiGe layers, deposited by plasma-enhanced chemical vapor deposition (PECVD), are very promising structural layers for use in microaccelerometers, microgyroscopes or for thin-film encapsulation, especially for applications where the thermal budget is limited. In this work it is shown for the first time that these layers are an attractive alternative to low-pressure CVD (LPCVD) poly-Si or poly-SiGe because of their high growth rate (100-200 nm/min) and low deposition temperature (520/spl deg/C-590/spl deg/C). The combination of both of these features is impossible to achieve with either LPCVD SiGe (2-30 nm/min growth rate) or LPCVD poly-Si (annealing temperature higher than 900/spl deg/C to achieve structural layer having low tensile stress). Additional advantages are that no nucleation layer is needed (deposition directly on SiO/sub 2/ is possible) and that the as-deposited layers are polycrystalline. No stress or dopant activation anneal of the structural layer is needed since in situ phosphorus doping gives an as-deposited tensile stress down to 20 MPa, and a resistivity of 10 m/spl Omega/-cm to 30 m/spl Omega/-cm. With in situ boron doping, resistivities down to 0.6 m/spl Omega/-cm are possible. The use of these films as an encapsulation layer above an accelerometer is shown.