Enhanced superplasticity for (alpha plus beta)-hot rolled Ti-6Al-4V-0.1B alloy by means of dynamic globularization

Thermo-mechanically processed Ti-6Al-4V alloy, with (0.1 wt.%) and without boron addition, has been subjected to tensile test under superplastic deformation conditions (Temperature, T = 850 degrees C and initial strain rate, (epsilon) over dot = 3 x 10(-4) s(-1)). The boron added alloy exhibited higher elongation (similar to 430%) in comparison to the base alloy without boron (similar to 365%). Superior ductility of the boron added alloy has been attributed to an enhanced alpha/beta interfacial boundary sliding. This was caused by riotous dynamic globularization leading to the abundant presence of equiaxed primary alpha grains with refined sizes and narrow distribution in the deforming microstructure. Cavities do occur around TiB particles during deformation; the cavities are, however, extremely localized and do not cause macroscopic cracking. (C) 2014 Elsevier Ltd. All rights reserved.

Thermal conductivity of beta-FeSi2/Si endogenous composites formed by the eutectoid decomposition of alpha-Fe2Si5

Thermoelectric properties of semiconducting beta-FeSi2 containing a homogeneous distribution of Si secondary phase have been studied. The synthesis was carried out using arc melting followed by the densification by uniaxial hot pressing. Endogenous beta-FeSi2/Si composites were produced by the eutectoid decomposition of high-temperature alpha-Fe2Si5 phase. The aging heat treatments have been carried out at various temperatures below the equilibrium eutectoid temperature for various durations in order to tune the size of the eutectoid product. Thermal properties of the samples were studied in the temperature range of 100-350 A degrees C. The microstructural investigations support the fact that the finest microstructure generated through the eutectoid decomposition of the alpha-Fe2Si5 metastable phase is responsible of the phonon scattering. The results suggest an opportunity to produce bulk iron silicide alloys with reduced thermal conductivity in order to enhance its thermoelectric performance.

Mechanisms Responsible for the Trophic Effect of Beta-Adrenoceptors on the I-to Current Density in Type 1 Diabetic Rat Cardiomyocytes

Background/Aims: In diabetic ventricular myocytes, transient outward potassium current (I-to) amplitude is severely reduced because of the impaired catecholamine release that characterizes diabetic autonomic neuropathy. Sympathetic nervous system exhibits a trophic effect on I-to since incubation of myocytes with noradrenaline restores current amplitude via beta-adrenoceptor (beta AR) stimulation. Here, we investigate the intracellular signalling pathway though which incubation of diabetic cardiomyocytes with the beta AR agonist isoproterenol recovers I-to amplitude to normal values. Methods: Experiments were performed in ventricular myocytes isolated from streptozotocin-diabetic rats. I-to current was recorded by using the patch-clamp technique. Kv4 channel expression was determined by immunofluorescence. Protein-protein interaction was determined by coimmunoprecipitation. Results: Stimulation of beta AR activates first a G alpha s protein, adenylyl cyclase and Protein Kinase A. PKA-phosphorylated receptor then switches to the G alpha i protein. This leads to the activation of the beta AR-Kinase-1 and further receptor phosphorylation and arrestin dependent internalization. The internalized receptor-arrestin complex recruits and activates cSrc and the MAPK cascade, where Ras, c-Raf1 and finally ERK1/2 mediate the increase in Kv4.2 and Kv4.3 protein abundance in the plasma membrane. Conclusion: beta(2)AR stimulation activates a G alpha s and G alpha i protein dependent pathway where the ERK1/2 modulates the Ito current amplitude and the density of the Kv4.2 and Kv4.2 channels in the plasma membrane upon sympathetic stimulation in diabetic heart.

Angular distribution and conversion of multi-keV L-shell X-ray sources produced from nanosecond laser irradiated thick-foil targets

An experimental study on the angular distribution and conversion of multi-keV X-ray sources produced from 2 ns-duration 527nm laser irradiated thick-foil targets on Shenguang II laser facility (SG-II) is reported. The angular distributions measured in front of the targets can be fitted with the function of f(theta) = alpha+ (1- alpha)cos(beta) theta (theta is the viewing angle relative to the target normal), where alpha = 0.41 +/- 0.014, beta = 0.77 +/- 0.04 for Ti K-shell X-ray Sources (similar to 4.75 keV for Ti K-shell), and alpha = 0.085 +/- 0.06, beta = 0.59 +/- 0.07 for Ag/Pd/Mo L-shell X-ray Sources (2-2.8 keV for Mo L-shell, 2.8-3.5 keV for Pd L-shell, and 3-3.8 keV for Ag L-shell). The isotropy of the angular-distribution of L-shell emission is worse than that of the K-shell emission at larger viewing angle (>70 degrees), due to its larger optical depth (stronger self-absorption) in the cold plasma side lobe Surrounding the central emission region, and in the central hot plasma region (emission region). There is no observable difference in the angular distributions of the L-shell X-ray emission among Ag, Pd, and Mo. The conversion efficiency of Ag/Pd/Mo L-shell X-ray sources is higher than that of the Ti K-shell X-ray sources, but the gain relative to the K-shell emission is not as high as that by using short pulse lasers. The conversion efficiency of the L-shell X-ray sources decrease, with increasing atomic numbers (or X-ray photon energy), similar to the behavior of the K-shell X-ray Source.

Estudo do polimorfismo Ser49Gly do gene do receptor beta adrenérgico 1 (β-adr 1) na população do estado do Rio de Janeiro, Brasil estratificada por cor da pele e ancestralidade genômica

As doenças cardiovasculares possuem a maior taxa de óbitos no mundo, e notavelmente nos últimos anos as pesquisas genéticas sobre as mesmas estão baseadas em estudos de associação, no qual o gene suspeito que esteja em maior frequência entre os pacientes passa a ser considerado um possível fator causal. Os polimorfismos genéticos que ocorrem no receptor beta-adrenérgico podem resultar em mudanças significativas na função do receptor, podendo acarretar fisiopatologias. Neste trabalho, o objetivo foi estimar a diversidade e a frequência do polimorfismo Ser49Gly do gene do receptor beta-adrenérgico 1 a partir de uma amostra de 188 indivíduos da população do Estado do Rio de Janeiro. As frequências também foram analisadas a partir da estratificação da amostra por critério fenotípico em função do padrão de cor da pele em (negros e não negros) ou ancestralidade genética em (afrodescendente e não afrodescendente), definida através da informação dos marcadores de ancestralidade Indels e SNP de cromossomo Y, para avaliar se os padrões de ancestralidade ou cor da pele são fundamentais para a diferenciação e distanciamento genético. Fragmentos de interesse foram amplificados por PCR (reação de cadeia de polimerase) com primers específicos para o marcador Ser49Gly e as reações de genotipagem foram realizadas com enzimas de restrição Eco0109I. Os valores da heterozigosidade variaram entre 0,25-0,50 e 0,20-0,41 nos grupos estratificados por ancestralidade e cor da pele, respectivamente. No que diz respeito à análise do equilíbrio de Hardy-Weinberg, não houve um desvio significativo na distribuição do marcador nas amostras gerais do Estado do Rio de Janeiro, ou mesmo nas amostras estratificadas. A distribuição dos alelos na amostra dos 188 indivíduos da população geral do Rio de Janeiro (AC_RJ) mostrou uma frequência de 80,30% e 19,70% para o alelo selvagem e mutado Ser49Gly, respectivamente. A comparação das análises sobre a distribuição das frequências alélicas para este marcador mostrou a ocorrência de diferenças significativas na distribuição das frequências alélicas entre negros e não negros e afrodescendentes e não afrodescendentes. A diferença significativa observada entre os negros e afrodescendentes, foi em menor grau de distanciamento. A informação obtida em relação à ancestralidade foi crucial para a obtenção dos dados sobre o aumento da variável mutada do polimorfismo Ser49Gly nas populações negras e afrodescendentes do Estado Rio de Janeiro. Tal evidência, em combinação com estudos clínicos podem contribuir para uma análise pormenorizada do padrão de susceptibilidade à doença em questão, em falhas do mecanismo deste receptor.

Molecular characterization of Chinese sturgeon gonadotropins and cellular distribution in pituitaries of mature and immature individuals

Chinese sturgeon (Acipenser sinensis) is a rare and endangered species, and also an important resource for the sturgeon aquaculture industry. To understand molecular characterization of Chinese sturgeon gonadotropins (GTHs), we cloned the full-length cDNAs of gonadotropin subunits common alpha (GTH-alpha), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from a pituitary cDNA library of mature female. Two subtypes of GTH-alpha were identified. The nucleotide sequences of A. sinensis common alpha I (AsGTH-alpha I), common alpha II (AsGTH-alpha II), FSH beta (AsFSH beta) and LH beta (AsLH beta) subunit cDNAs are 345, 363, 387 and 414 bp in length, and encode mature peptides of 115, 121, 129 and 138 aa, respectively. Then, three polyclonal antibodies were prepared from the in vitro expressed AsGTH-alpha I, AsFSH beta and AsLH beta mature proteins, respectively. Significant expression differences were revealed between immature and mature sturgeon pituitaries. Western blot detection and immunofluoresence localization revealed the existence of three-gonadotropin subunits (AsGTH-alpha, AsFSH beta and AsLH beta) in mature sturgeon pituitaries, but only AsFSH beta was detected in immature individual pituitaries during early stages in the sturgeon life, and obvious difference was observed between males and females. In males, AsFSH beta was expressed in 4-year-old individuals, whereas in females, AsFSH beta was just expressed in 5-year-old individuals. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Properties of the beta-Delayed Proton Decay of Er-147

The beta-delayed proton decay of Er-147 is studied experimentally using the Ni-58+Mo-92 reaction at a beam energy of 383 MeV. Based on a He-jet apparatus coupled with a tape transport system, the beta-delayed proton radioactivities both from the nu s(1/2) ground state and the nu h(11/2) isomer in Er-147 are identified by proton-gamma coincidence measurements. By analyzing the time distribution of the 4(+) -> 2(+) gamma transition in the grand-daughter nucleus Dy-146, a half-life of 1.6 +/- 0.2 s is determined for the nu h(11/2) isomer in Er-147. The half-life for the ground state of Er-147 is estimated to be 3.2 +/- 1.2 s.

Living Copolymerization of Ethylene with Norbornene Mediated by Heteroligated (Salicylaldiminato) (beta-enaminoketonato)Titanium Catalysts

Three heteroligated (salicylaldiminato)(beta-enaminoketonato)titanium complexes [3-Bu-t-2-OC6H3CH=N(C6F5)][(p-XC6H4)N=C(Bu-t)CHC(CF3)O]TiCl2 (3a: X = F, 3b: X = Cl, 3c: X = Br) were synthesized and investigated as the catalysts for ethylene polymerization and ethylene/norbornene copolymerization. In the presence of modified methylaluminoxane as a cocatalyst, these unsymmetric catalysts exhibited high activities toward ethylene polymerization, similar to their parallel parent catalysts. Furthermore, they also displayed favorable ability to efficiently incorporate norbornene into the polymer chains and produce high molecular weight copolymers under the mild conditions, though the copolymerization of ethylene with norbornene leads to relatively lower activities. The sterically open structure of the beta-enaminoketonato ligand is responsible for the high norbornene incorporation. The norbornene concentration in the polymerization medium had a profound influence on the molecular weight distribution of the resulting copolymer.

Ethylene-propylene copolymerization with bis(beta-enaminoketonato) titanium complexes activated with modified methylaluminoxane

Ethylene-propylene copolymerization, using [(Ph)NC(R-2)CHC(R-1)O](2)TiCl2 (R-1 = CF3, Ph, or t-Bu; R-2 = CH3 or CF3) titanium complexes activated with modified methylaluminoxane as a cocatalyst, was investigated. High-molecular-weight ethylene-propylene copolymers with relatively narrow molecular weight distributions and a broad range of chemical compositions were obtained. Substituents R-1 and R-2 influenced the copolymerization behavior, including the copolymerization activity, methylene sequence distribution, molecular weight, and polydispersity. With small steric hindrance at R-1 and R-2, one complex (R-1 = CF3; R-2 = CH3) displayed high catalytic activity and produced copolymers with high propylene incorporation but low molecular weight. The microstructures of the copolymers were analyzed with C-13 NMR to determine the methylene sequence distribution and number-average sequence lengths of uninterrupted methylene carbons.

Synthesis and characterization of poly(beta-hydroxybutyrate) and poly(epsilon-caprolactone) copolyester by transesterification

To synthesize the copolyester of poly(beta-hydroxybutyrate) (PHB) and poly(epsilon-caprolactone) (PCL), the transesterification of PHB and PCL was carried out in the liquid phase with stannous octoate as the catalyzer. The effects of reaction conditions on the transesterification, including catalyzer concentration, reaction temperature, and reaction time, were investigated. The results showed that both rising reaction temperature and increasing reaction time were advantageous to the transesterification. The sequence distribution, thermal behavior, and thermal stability of the copolyesters were investigated by C-13 NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry, wide-angle X-ray diffraction, optical microscopy, and thermogravimetric analysis. The transesterification of PHB and PCL was confirmed to produce the block copolymers. With an increasing PCL content in the copolyesters, the thermal behavior of the copolyesters changed evidently. However, the introduction of PCL segments into PHB chains did not affect its crystalline structure. Moreover, thermal stability of the copolyesters was little improved in air as compared with that of pure PHB.

Study on the transesterification of poly(beta-hydroxybutyrate) and poly(epsilon-caprolactone)

The transesterification of poly(beta-hydroxybutyrate) (PHB) and poly(epsilon-caprolactone) (PCL) was carried out by using stannous octoate as catalyzer in liquid phase. The effects of reaction conditions on the transesterification, including reaction temperature, reaction time and catalyzer content, were investigated. The sequence distribution, crystallization behavior and thermal stability of PHB-co-PCL copolyesters were studied by C-13-NMR, FTIR, DSC, WAXD and TGA. The results showed that the transesterification of PHB with PCL was confirmed to produce a block copolymer, and enhancing reaction temperature and increasing reaction time were advantageous to the transesterification. With the increase in PCL content in the block copolymer, the crystallization behavior of PHB-co-PCL copolyesters changed evidently. On the other hand, the introduction of PCL segment into PHB chains did not change its crystalline structure; moreover, thermal stability of PHB-co-PCL copolyesters was a little improved in air, comparing with that of pure PHB.

beta-catenin in early development of the lancelet embryo indicates specific determination of embryonic polarity

The lancelet (amphioxus) embryo develops from a miolecithal egg and starts gastrulation when it is approximately 400 cells in size, in a fashion similar to that of some non-chordate deuterostomes. Throughout this type of gastrulation, the embryo develops characteristics such as the notochord and hollow nerve cord that commonly appear in chordates. beta-Catenin is an important factor in initiating body patterning. The behavior and developmental pattern of this protein in early lancelet development was examined in this study. Cytoplasmic beta-catenin was localized to the animal pole after fertilization and then was incorporated asymmetrically into the blastomeres during the first cleavage. Asymmetric distribution was observed at least until the 32-cell stage. The first nuclear localization was at the 64-cell stage, and involved all of the cells. At the initial gastrula stage, however, concentrated beta-catenin was found on the dorsal side. LiCl treatment affected the asymmetric pattern of beta-catenin during the first cleavage. LiCl also changed distribution of nuclear beta-catenin at the initial gastrula stage: distribution extended to cells on the animal side. Apparently associated with this change, expression domains of goosecoid, lhx3 and otx also changed to a radially symmetric pattern centered at the animal pole. However, LiCl-treated embryos were able to establish embryonic polarity. The present study suggests that in the lancelet embryo, polarity determination is independent of dorsal morphogenesis.

Hybrid simulation of ion cyclotron resonance in the solar wind: evolution of velocity distribution functions

Li, Xing; Habbal, S.R., (2005) 'Hybrid simulation of ion cyclotron resonance in the solar wind: evolution of velocity distribution functions', Journal of Geophysical Research 110(A10) pp.A10109 RAE2008

The G-protein-coupled receptor kinases beta ARK1 and beta ARK2 are widely distributed at synapses in rat brain.

The beta-adrenergic receptor kinase (beta ARK) phosphorylates the agonist-occupied beta-adrenergic receptor to promote rapid receptor uncoupling from Gs, thereby attenuating adenylyl cyclase activity. Beta ARK-mediated receptor desensitization may reflect a general molecular mechanism operative on many G-protein-coupled receptor systems and, particularly, synaptic neurotransmitter receptors. Two distinct cDNAs encoding beta ARK isozymes were isolated from rat brain and sequenced. The regional and cellular distributions of these two gene products, termed beta ARK1 and beta ARK2, were determined in brain by in situ hybridization and by immunohistochemistry at the light and electron microscopic levels. The beta ARK isozymes were found to be expressed primarily in neurons distributed throughout the CNS. Ultrastructurally, beta ARK1 and beta ARK2 immunoreactivities were present both in association with postsynaptic densities and, presynaptically, with axon terminals. The beta ARK isozymes have a regional and subcellular distribution consistent with a general role in the desensitization of synaptic receptors.

Activation and targeting of extracellular signal-regulated kinases by beta-arrestin scaffolds.

Using both confocal immunofluorescence microscopy and biochemical approaches, we have examined the role of beta-arrestins in the activation and targeting of extracellular signal-regulated kinase 2 (ERK2) following stimulation of angiotensin II type 1a receptors (AT1aR). In HEK-293 cells expressing hemagglutinin-tagged AT1aR, angiotensin stimulation triggered beta-arrestin-2 binding to the receptor and internalization of AT1aR-beta-arrestin complexes. Using red fluorescent protein-tagged ERK2 to track the subcellular distribution of ERK2, we found that angiotensin treatment caused the redistribution of activated ERK2 into endosomal vesicles that also contained AT1aR-beta-arrestin complexes. This targeting of ERK2 reflects the formation of multiprotein complexes containing AT1aR, beta-arrestin-2, and the component kinases of the ERK cascade, cRaf-1, MEK1, and ERK2. Myc-tagged cRaf-1, MEK1, and green fluorescent protein-tagged ERK2 coprecipitated with Flag-tagged beta-arrestin-2 from transfected COS-7 cells. Coprecipitation of cRaf-1 with beta-arrestin-2 was independent of MEK1 and ERK2, whereas the coprecipitation of MEK1 and ERK2 with beta-arrestin-2 was significantly enhanced in the presence of overexpressed cRaf-1, suggesting that binding of cRaf-1 to beta-arrestin facilitates the assembly of a cRaf-1, MEK1, ERK2 complex. The phosphorylation of ERK2 in beta-arrestin complexes was markedly enhanced by coexpression of cRaf-1, and this effect is blocked by expression of a catalytically inactive dominant inhibitory mutant of MEK1. Stimulation with angiotensin increased the binding of both cRaf-1 and ERK2 to beta-arrestin-2, and the association of beta-arrestin-2, cRaf-1, and ERK2 with AT1aR. These data suggest that beta-arrestins function both as scaffolds to enhance cRaf-1 and MEK-dependent activation of ERK2, and as targeting proteins that direct activated ERK to specific subcellular locations.