Investigation of paramagnetic response of metallic epoxies

The paramagnetic properties of epoxies which were impregnated with metal ions were examined as the primary task in this research. A major conclusion was that the quality control of the epoxies was insufficient to permit reliable evaluation. Subsequently, a new set of specimens is being prepared. As an additional task, a new method is investigated for estimating heats of combustion for saturated hydrocarbons. The results of that investigation have shown that the empirical approach is a promising method for on-line measurements

Lack of direct evidence for a functional role of voltage-operated calcium channels in juxtaglomerular cells

In this study we have examined the role of voltage-gated calcium channels in the regulation of calcium in juxtaglomerular cells. Using a combination of patch-clamp and single-cell calcium measurement we obtained evidence neither for voltage-operated calcium currents nor for changes of the intracellular calcium concentration upon acute depolarizations of the cell membrane. Increases of the extracellular concentration of potassium to 80 mmol/l depolarized the juxtaglomerular cells close to the potassium equilibrium potential, but did not alter the intracellular calcium concentration neither in patch-clamped nor in intact Furaester-loaded cells. Moreover, basal renin secretion from a preparation enriched in mouse juxtaglomerular cells and from rat glomeruli with attached juxtaglomerular cells was not inhibited when extracellular potassium was isoosmotically increased to 56 mmol/l. In mouse kidney slices, however, depolarizing potassium concentrations caused a delayed inhibition at 56 mmol/l and a delayed stimulation of renin secretion at 110 mmol/l. Taken together, our study does not provide direct evidence for a role of voltage-activated calcium channels in the regulation of calcium and renin secretion in renal juxtaglomerular cells

The correlation of microstructure and mechanical properties of in-situ Al-Mg2Si cast composite processed by equal channel angular pressing

In this paper, the effect of equal channel angular pressing (ECAP) on microstructure and mechanical properties of hypereutectic Al-20%Mg2Si and Al-15%Mg2Si, as well as hypoeutectic Al-10%Mg2Si composites has been investigated. After fabricating the composites by in-situ casting, the composites were processed using the ECAP process up to two passes at room temperature. Microstructural studies have been carried out using a field emission scanning electron microscopy equipped with an energy dispersive X-ray spectrometer. Mechanical properties were also documented using Vickers microhardness and shear punch tests. In the hypereutectic composites, a decrease in the average size of pro-eutectic Mg2Si (Mg2Sip) particles, breakages in eutectic networks, and lengthening of the Al (α) phase in direction of shear bands were observed after the ECAP process. For instance, the average size of Mg2Sip Particles in Al-20%Mg2Si composite reduced from 40 to 17 μm after 2 passes of ECAP. Furthermore, a uniform distribution of Mg2Sip particles was developed in the matrix. In hypoeutectic composite, the ECAP process caused a uniform distribution of eutectic Mg2Si (Mg2SiE) in the matrix that considered a favorable microstructure. Microhardness measurements and shear punch results showed an ascending trend after each pass of ECAP for all specimens. For example, microhardness and shear strength of Al-20%Mg2Si increased from 88 HV and 109 MPa to 119 HV and 249 MPa after two passes indicating 35% and 34% increments, respectively. Density and porosity calculations by Archimedes principle revealed that the density of the composites increased after two passes of ECAP due to the reduction of porosity

Analysis and comparison of wheat losses in two harvesting methods

Wheat losses in John Deere 955 combine was compared between stripper header and conventional header.  Tests were conducted in a wheat field.  At first for comparison, the optimum working condition was obtained for both type of headers and then other parameters are compared. Results showed that the optimum working condition of combine with a second gear and mediate engine speed for stripper header was obtained with 75 cm for hood distance, 60 cm for header distance and 760 rmin-1 for rotor speeds.  In stripper header, the total loss of different parts of combine was under 3.5%, although these losses in conventional header reached up to 6.5% which was the highest loss for headers.  Number and weight of lost cluster in harvesting with stripper header was much less than conventional header. Keywords: wheat, stripper header, conventional header, rotor speed, los

Feasibility of a nuclear gauge for fuel quantity measurement aboard aircraft

Capacitance fuel gauges have served as the basis for fuel quantity indicating systems in aircraft for several decades. However, there have been persistent reports by the airlines that these gauges often give faulty indications due to microbial growth and other contaminants in the fuel tanks. This report describes the results of a feasibility study of using gamma ray attenuation as the basis for measuring fuel quantity in the tanks. Studies with a weak Am-241 59.5-keV radiation source indicate that it is possible to continuously monitor the fuel quantity in the tanks to an accuracy of better than 1 percent. These measurements also indicate that there are easily measurable differences in the physical properties and resultant attenuation characteristics of JP-4, JP-5, and Jet A fuels. The experimental results, along with a suggested source-detector geometrical configuration are described

Solving two-dimensional coupled Burgers equations via a stable hybridized discontinuous Galerkin method

The purpose of this paper is to design a fully discrete hybridized discon-tinuous Galerkin (HDG) method for solving a system of two-dimensional (2D) coupled Burgers equations over a specified spatial domain. The semi-discrete HDG method is designed for a nonlinear variational formulation on the spatial domain. By exploiting broken Sobolev approximation spaces in the HDG scheme, numerical fluxes are defined properly. It is shown that the proposed method is stable under specific mild conditions on the stabi-lization parameters to solve a well-posed (in the sense of energy method) 2D coupled Burgers equations, which is imposed by Dirichlet boundary conditions. The fully discrete HDG scheme is designed by exploiting the Crank–Nicolson method for time discretization. Also, the Newton–Raphson method that has the order of at least two is nominated for solving the obtained nonlinear system of coupled Burgers equations over the rect-angular domain. To reduce the complexity of the proposed method and the size of the linear system, we exploit the Schur complement idea. Numerical results declare that the best possible rates of convergence are achieved for approximate solutions of the 2D coupled Burgers equations and their first-order derivatives. Moreover, the proposed HDG method is examined for two other types of systems, that is, a system with high Reynolds numbers and a system with an unavailable exact solution. The acceptable results of examples show the flexibility of the proposed method in solving various problems

Highly Efficient Formylation of Alcohols, Thiols and Aniline Derivatives by a Heterogeneous (HCOOH/SiO2) System under Microwave Irradiation and Solvent-free Conditions

A simple, rapid and efficient microwave-assisted procedure for the formylation of aniline derivatives and alcohols, using a heterogeneous (HCOOH/SiO2) system under solvent-free conditions is reported. The method is applied to a set of amines, alcohols and thiols and short reaction times (<10 min) with high yields are reported. This protocol introduces a practical and viable green technology of solvent-free and catalyst-free reactions.Keywords: Alcohols, anilines, SiO2, HCOOH, microwave irradiation, solvent-free condition

Cloning, expression, purification and CD analysis of recombinant human betatrophin

Betatrophin is a member of the angiopoietin-like (ANGPTL) family that has been implicated in both triglyceride and glucose metabolism. The physiological functions and molecular targets of this protein remain largely unknown; hence, a purified available protein would aid study of the exact role of betatrophin in lipid or glucose metabolism. In this study, we cloned the full-length cDNA of betatrophin from a human liver cDNA library. Betatrophin was expressed in the pET-21b-E. coli Bl21 (DE3) system and purified by immobilized metal-affinity chromatography and ion-exchange chromatography. Circular dichroism spectroscopy revealed α-helix as the major regular secondary structure in recombinant betatrophin. The production method is based on commonly available resources; therefore, it can be readily implemented