Heterogeneous mutations in the gene encoding the alpha-subunit of the stimulatory G protein of adenylyl cyclase in Albright hereditary osteodystrophy

Albright hereditary osteodystrophy (AHO) is an inherited disorder associated with deficient activity of the alpha-subunit of the guanine nucleotide-binding regulatory protein (Gs alpha) that couples receptors to adenylyl cyclase. To identify mutations that lead to Gs alpha deficiency, we isolated genomic DNA from patients with AHO and used the polymerase chain reaction to amplify exons of the Gs alpha genes. DNA was amplified using intron-specific oligonucleotide primers flanking exons of the Gs alpha gene. To optimize our ability to detect mutations, one oligonucleotide from each primer pair was synthesized with a 5' GC-clamp. Amplified Gs alpha gene fragments were analyzed by denaturing gradient gel electrophoresis in order to detect mutations that alter the melting point of the double-stranded DNA fragment. Using this technique, we have identified and characterized three mutations and one neutral polymorphism. The polymorphism, located in exon 5, consisted of a T-->C substitution that conserves the isoleucine residue at codon 131 (ATT-->ATC). Two mutations were missense mutations, which in one family consisted of a nucleotide substitution (T-->C) in exon 4 that results in replacement of Leu by Pro at codon 99 of the Gs alpha molecule. Affected subjects in a second family had a single base (C-->T) mutation in exon 6 that resulted in replacement of Arg by Cys at codon 165. A 4-base pair deletion (GTGG) in exon 8 at position +214 was identified in one Gs alpha allele from each affected subject in the third family. This mutation causes a frameshift after the codon for Gln213 that results in a premature stop codon 81 base pair after the deletion. Immunoblot analysis of plasma membranes prepared from cultured fibroblasts or erythrocytes indicated that levels of immunoactive Gs alpha protein were decreased in all affected subjects. We conclude that heterogeneous mutations in the gene encoding Gs alpha, including deletions and single amino acid substitutions, are responsible for Gs alpha deficiency in AHO.     

A generalized theory of simple thermomechanical materials

We develop here a constitutive theory for the generalized simple thermomechanical materials by resorting to generalized thermodynamics in which the empirical temperature is replaced by the thermodynamic temperature which is itself a constitutive function. The restrictions imposed by the generalized Clausius-Duhem inequality on the constitutive relations are fully explored and the theory is applied to a special thermoviscoelastic material.     

Factors influencing the activity and thermostability of immobilized porcine pancreatic lipase

Lipase from porcine pancreas was immobilized on cellulose beads having various degrees of hydrophobicity, by covalent linking and by hydrophobic adsorption. Lipolytic activity was measured in heterogeneous organicaqueous systems of various hydrophobicities using olive oil as a substrate. The main factors influencing lipase activity were hydrophobicity of the reaction mixture and of the carrier. Carriers with increased hydrophobicity enhanced lipase activity more than less hydrophobic ones. Lipase immobilized covalently on cellulose beads was less active than that adsorbed onto tritylcellulose but was considerably more thermostable.     

The wear of aluminium-based journal bearing materials under lubrication

The aluminium-based alloys, nowadays, are developed to be used in high performance engine bearings. In this study, new Al-based bearing alloys, which are produced by metal mould casting, were developed; and tribologic properties of these alloys under lubrication were analyzed experimentally. Four different aluminium alloys were carried out on pin on disc wear tester for that purpose. SAE 1040 steel was used as the disc material in the wear tester. Friction tests were carried out at 0.231–1.036 N/mm² pressures and at 0.6–2.4 m/s sliding speeds. Wear tests were carried out at 1.8 m/s sliding speed and at 70 N normal load. Friction coefficients and weight losses of the samples were determined under various working conditions as a result of the experiments. The morphographies of the worn surfaces were analyzed. Hardness, surface roughness, and surface temperature of the samples were measured. The results showed that the friction and wear behaviors of the alloys have changed according to the sliding conditions. The effects of the elements except aluminium composing alloys on the tribologic properties were analyzed. Al8.5Si3.5Cu alloy has a lower friction coefficient value than other alloys. Al8.5Si3.5Cu and Al15Sn5Cu3Si alloys, on the other hand, have the highest wear resistance. Al15Pb3.7Cu1.5Si1.1Fe alloy is the most worn material; and Al15Pb3.7Cu1.5Si1.1Fe alloy has the highest wear rate. As a result of the evaluations conducted, Al–Sn and Al–Si alloys, which include Si and Sn, can be preferred, among the aluminium alloys that will work under lubrication, as the bearing material.     

Optimization of the Dissolution of Tincal Ore in Phosphoric Acid Solutions at High Temperatures

The aim of the study was to investigate the optimization of the dissolution of tincal ore in phosphoric acid solutions at high temperatures in a batch reactor. The effect of the following parameters on the dissolution process was investigated: the reaction temperature, the phosphoric acid concentration, the particle size, and the solid-to-liquid ratio. The best conditions for the dissolution were determined using the 2⁴ factorial experimental design method. The optimum values of the parameters were experimentally determined. The effective parameters were the reaction temperature, the phosphoric acid concentration, the particle size, and the solid-to-liquid ratio. The optimum conditions resulted in the maximum boron dissolution at an acid concentration of 1 M, reaction temperature of 85°C, particle size of 4.75 mesh, and solid-to-liquid ratio of 1/6 g · mL^?1. Under these optimum conditions, the best dissolution yield was 98.26%.     

Measurements of the Efficiency of A Si(Li) Detector in the 5.5-60 keV Energy Region

Abstract

The photopeak, intrinsic, and radial efficiency of a Si(Li) detector has been determined as a function of energy over the range 5.5 to 60 keV energy region using four standard sources. Furthermore, emission probabilities for the standard sources have been determined and compared with literature values.     

Functional copolymer/organo‐montmorillonite nanoarchitectures. IX. Synthesis and nanostructure–morphology–thermal behaviour relationships of poly[(maleic anhydride)‐alt‐(acrylic acid)]/organo‐ montmorillonite nanocomposites

Functional copolymer/clay hybrids were synthesized by radical‐initiated interlamellar copolymerization of maleic anhydride/maleic acid and acrylic acid with 2,2′‐azobis(2‐methylpropionamidine) dihydrochloride as a water‐soluble ionizable radical initiator in the presence of reactive (octadecylamine‐montmorillonite (ODA‐MMT)) and non‐reactive (dimethyldodecylammonium‐montmorillonite) organoclays at 60 °C in aqueous medium under nitrogen atmosphere. The monomers were dissolved in aqueous medium, and the two types of clay particles used were easily dissolved and dispersed partially swollen, respectively, in deionized water. Structure, thermal behaviour and morphology of the synthesized nanocomposites were investigated using Fourier transform infrared spectroscopy, X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and scanning and transmission electron microscopy. It is demonstrated that intercalative copolymerization proceeds via ion exchange between organoclays and carboxylic groups of monomers/polymers, which essentially improves interfacial interactions of polymer matrix and clay layers through strong hydrogen bonding. In the case of intercalative copolymerization in the presence of ODA‐MMT clay, a similar improvement is provided by in situ hydrogen bonding and amidolysis of carboxylic/anhydride groups from copolymer chains with primary amine groups of ODA‐MMT. The nanocomposites exhibit higher degree of intercalation/exfoliation of copolymer chains, improved thermal properties and fine dispersed morphology. Copyright © 2011 Society of Chemical Industry     

The synthesis of (N1E,N4E)-N1,N4-bis(pyridine-2-YL) ethylene benzene-1,4-diamine and investigation of its efficiency as new binuclear catalyst complex in copper-based ATRP

(N¹E,N⁴E)-N¹,N⁴-bis(pyridin-2-yl) ethylene benzene-1,4-diamine (BPEBD) was synthesized by condensation of 2-acetyl pyridine and 1,4-diaminobenzene and its efficiency as a catalyst in Cu-based atom transfer radical polymerizations (ATRP) of methyl methacrylate (MMA) and styrene (S) was investigated. Linear first-order kinetic plots were obtained. However, there were induction periods. The apparent rate constant values of ATRP of MMA with CuCl/BPEBD catalyst system in toluene were found to be between 2.10 × 10^?5 and 9.83 × 10^?5 s^?1, while they were between 6.67 × 10^?6 and 3.30 × 10^?5 s^?1 in the case of acetonitrile, indicating the presence of a low radical concentration throughout the polymerizations. Low apparent rate constant values denote a good control over ATRP in general. Apparent rate constant vs [ligand]/[catalyst] ratio plots showed a maximum at the [ligand]/[catalyst] ratio of 1. In the ATRP of MMA in toluene, M _n,GPC values increased linearly with conversion and these molecular weight values were close to M _n,th in comparison to that of in acetonitrile. In the polymerization of S, the control of molecular weights was not good, although the reactions were first-order kinetics. Cyclic voltammetry measurements confirmed that CuCl/BPEBD complex in acetonitrile gives quasi-reversible redox couples, and copper (I) centers in CuCl/BPEBD binuclear catalyst complexes are readily oxidized and it potentially suits to facile ATRP.