Factors affecting the electrical resistivity of soybean oil

The electrical resistivity of soybean oil that had been purified to remove polar constituents was determined, and the effect of measuring conditions and the addition of polar constituents (free fatty acids, phospholipids, monoglyceride, α-to-copherol, β-sitosterol, β-carotene, peroxides, and water) on resistivity was investigated. For reproducible resistivity measurements, voltages in excess of 50 volts and charging times greater than 120 s were necessary. As temperature was increased linearly, the resistivity of the oil decreased logarithmically. For making comparisons, a temperature of 24°C, a potential of 50 volts, and 120 s charging times were chosen. All polar constituents decreased the resistivity of the purified soybean oil, but water, phospholipids, and monoglycerides had the greatest effects. Water increased the resistivity-lowering effects of all other constituents except for free fatty acids, which were affected by water only slightly. The synergistic effect of water was much greater for phospholipids and monoglyceride than for other constituents.     

Cross‐Coupled Ratio Control Structure

Abstract

In this paper, a cross‐coupled ratio control structure with two blend stations has been proposed. The main feature of the proposed structure is to give a good ratio performance for both set‐point changes and load disturbances that might occur in any one of the two loops. A simple tuning procedure for the inner controllers of the two loops and an easy design methodology for the blend stations have been proposed in order to avoid any significant tuning and design effort for the implementer. The proposed structure is realized on a microcontroller based system. This cross‐coupled ratio control structure that has been embedded into the microcontroller is then used to maintain the prescribed ratio “a” of the two processes, namely heat transfer process trainer (PT 326‐Feedback) and process control simulator (PCS 327‐Feedback). The same two processes are run under another alternative ratio control structure and the results are compared with each other.     

Optical and physical behaviours of newly developed germanium-tellurium (GeTe) glasses: a comprehensive experimental and in-silico study with commercial glasses and ordinary shields

Journal of Materials Science: Materials in Electronics - In this study, synthesis and determination of physical, optical, and radiation shielding properties of glasses based on TeO2 and GeO2 were...     

Genetic divergence in cellular resistance to heat shock in cattle: differences between breeds developed in temperate versus hot climates in responses of preimplantation embryos,reproductive tract tissues and lymphocytes to increased culture temperatures

The detrimental effects of heat stress on fertility in cattle are less pronounced in heat-tolerant breeds. Although these genetic differences reflect differences in thermoregulation, cells from heat-tolerant breeds are less adversely compromised by increased temperature (that is, heat shock) than cells from heat-sensitive breeds. Experiments were performed to test the hypothesis that cells and tissues from two thermotolerant breeds (Brahman and Senepol) are better able to survive and function after exposure to increased temperature than cells and tissues from two thermosensitive breeds (Holstein and Angus). Exposure of embryos at>eight-cell stage at day 5 after insemination to heat shock of 41.0 degrees C for 6 h decreased development to the blastocyst stage and the number of cells per embryo. However, the deleterious effect of heat shock on blastocyst formation and the number of cells per embryo was less pronounced for Brahman than for Holstein and Angus breeds. Embryos from Senepol cows had very low development and it was not possible to determine heat shock effects in this breed. In contrast to the sensitivity of embryos to heat shock, there was no effect of a 41.0 degrees C heat shock on [(3)H]leucine incorporation into proteins secreted by oviductal or endometrial explants. Lymphocytes from Brahman and Senepol cows were more resistant to heat-induced apoptosis than lymphocytes from other breeds. Heat shock reduced lymphocyte glutathione content but the magnitude of the decrease was not affected by breed. In conclusion, embryos from Brahman cows are more resistant to heat shock than embryos from Holstein or Angus cows. Genetic differences are also present in thermotolerance for apoptosis response in lymphocytes, with Brahman and Senepol cattle being more resistant to heat shock than Angus and Holstein breeds. It is likely that the evolutionary forces that led to the Brahman and Senepol breeds being adapted to hot climates resulted in the selection of genes controlling resistance to cellular heat shock.     

Determination of physical properties of carbonate rocks from P-wave velocity

Velocity, density, porosity, void ratio, water absorption by weight and P-wave velocity tests were conducted on 14 different carbonate rocks. Strong correlations between P-wave velocity and all the physical properties of the rock were found. The relations follow a linear function. The equations developed were compared with others in the literature. Although it appears that the physical properties of the tested carbonate rocks can be estimated from P-wave velocity, the validity of the derived equations must be checked for other carbonate rocks as the equations given are likely to be specific to the test method and vary with rock type, degree of saturation and presence of bedding planes.      

Spectroscopic and thermal analysis of lead-free multipurpose radiation shielding glasses

The genetic algorithm was used to identify glasses, of the composition 50Bi₂O₃-(50-x) B₂O₃-xBaO with $25\ge x\ge 5$ wt%, that have a similar half-value layer (HVL) and neutron removal cross-section. The structure of these glasses was further explored using a combination of spectroscopic and thermal analysis in order to ascertain whether they possess advantageous physical properties comparable to traditional materials used in nuclear reactor design. Differential scanning calorimetry (DSC) analysis was used to examine the thermal profile of the glass system and to identify glass transition temperature T_g and softening temperature T_s. Glass of the composition 50Bi₂O₃–30B₂O₃–20BaO had exhibited the highest thermal stability. Analysis of the Raman spectra of the samples confirmed the presence of BiO₆ octahedrons and B-O-B bonds in poly borate chains. A deconvolution of the IR spectra was carried out to determine the relative proportions of BO₃ triangles to BO₄ tetrahedral units in the glass network that would affect the density and bulk modulus. Optical absorption spectrum of the samples exhibited absorption peaks in the blue region along with a broad band of absorption at longer red wavelengths associated with excitation of bismuth ions. When compared to traditional heavy concretes used in radiation shielding, the bismuth-barium borate glasses exhibited superior performance over conventional barite concrete as a gamma-radiation shield and was comparable to limonite concrete as a neutron radiation shield. The bulk modulus of the glass series was also found to be comparable to that of regular concrete at approximately to 30?GPa.     

Measurement of mass attenuation coefficients,effective atomic numbers,and electron densities for different parts of medicinal aromatic plants in low-energy region

The mass attenuation coefficients(l/q) for different parts(root, flower, stem, and leaf) of three medicinal aromatic plants(Teucrium chamaedrys L. subsp. sinuatum,Rheum ribes, and Chrysophthalmum montanum) were measured using an ~(241)Am photon source in a stable geometry and calculated using the Monte Carlo N-Particle Transport Code System-extended(MCNPX) code and the WinXCOM program. The experimental and theoretical MCNPX and WinXCOM values exhibited good agreement.The measured mass attenuation coefficient values were then used to compute the effective atomic number(Z_(eff))and electron density(N_E) of the samples. The results reveal that S1-S(stem of Teucrium chamaedrys L. subsp. sinuatum) has the highest values of l/q and Zeff.     

Simulations of mass attenuation coefficients for shielding materials using the MCNP-X code

In this paper,mass attenuation coefficients of concrete,bricks and cement plaster,as shielding materials,are calculated at 59.5,356,662,1173,1274 and 1333 keV by using the MCNP-X (version 2.4.0) code.The numerical simulation results are compared with previous Monte Carlo studies,experimental results and XCOM data.The effects of barite on mass attenuation coefficients are investigated.The mass attenuation coefficients increase with the barite content.Thus,our results agree well with experimental studies on gamma ray shielding of barite.It is flexible for the MN method to change the barite rates in material by small increments,which is experimentally difficult.Also,modeled geometry can be used for future approaches such as new designs and new structures especially in investigating new barite-containing materials to build nuclear reactors or high-energy radiation therapy facilities.     

A comparison of the transmission through butt and overlap gaps

This paper compares the transmission through electrically thin butt and overlap gaps. It is shown that in the limit as the gap widths approaches zero, the transmissions are identical and the transmitted power can be minimized by choosing the gap depths as a quarter wavelength plus an integer number of half wavelengths     

A review of thermoplastic composites for bipolar plate applications

Bipolar plates are responsible for functions of vital importance to the long‐term performance of fuel cells. They play crucial roles in water and gas management, mechanical strength and electrical conductivity. It also significantly contributes to the volume, weight and cost of fuel cell stacks. The properties of bipolar plates are affected by the materials and processes used in the manufacturing of the plates. The objective of this article is to review the use of thermoplastic materials as polymer matrices in bipolar plate applications. Conductive composites consisting of different types and blends of thermoplastic polymers are detailed discussed. The effects of filler types and processing conditions are given. Several thermoplastic blends consisting of carbon black, carbon nanotube and graphite are evaluated. The dispersion of conductive fillers, in particular, polymer composites and polymer blend composites is also given. Copyright © 2013 John Wiley & Sons, Ltd.