Search

[μ- N, N′-Bis(pyridin-3-yl)benzene-1,4-dicarboxamide-1:2κ2 N: N′]bis{[ N, N′-bis(pyridin-3-yl)benzene-1,4-dicarboxamide-κ N]diiodidomercury(II)}, [Hg2I4(C18H14N4O2)3], is an S-shaped dinuclear molecule, composed of two HgI2 units and three N, N′-bis(pyridin-3-yl)benzene-1,4-dicarboxamide ( L) ligands. The central L ligand is centrosymmetric and coordinated to two HgII cations via two pyridine N atoms, in a syn- syn conformation. The two terminal L ligands are monodentate, with one uncoordinated pyridine N atom, and each adopts a syn- anti conformation. The HgI2 units show highly distorted tetrahedral (sawhorse) geometry, as the HgII centres lie only 0.34 (2) or 0.32 (2) Å from the planes defined by the I and pyridine N atoms. Supramolecular interactions, thermal stability and solid-state luminescence properties were also measured. [ABSTRACT FROM AUTHOR]

In this paper, an approach to reduce the common-mode voltage and to eliminate narrow pulse for implemented AC-DC matrix converters is presented. An improved space vector modulation (SVM) strategy is developed by replacing the zero space vectors with suitable pairs of active ones. Further, while considering the commutation time, the probability of narrow pulse in the conventional and proposed SVM methods are derived and compared. The advantages of the proposed scheme include: a 50% reduction in the peak value of the common-mode voltage; improved input and output performances; a reduction in the switching loss by a reduced number of switching commutations and a simplified implementation via software. Experimental results are presented to demonstrate the correctness of the theoretical analysis, as well as the feasibility of the proposed strategy. [ABSTRACT FROM AUTHOR]

A new approach for encoding DNA sequences as input for DNA sequence analysis is proposed using the error correction coding theory of communication engineering. The encoder was designed as a convolutional code model whose generator matrix is designed based on the degeneracy of codons, with a codon treated in the model as an informational unit. The utility of the proposed model was demonstrated through the analysis of twelve prokaryote and nine eukaryote DNA sequences having different GC contents. Distinct differences in code distances were observed near the initiation and termination sites in the open reading frame, which provided a well-regulated characterization of the DNA sequences. Clearly distinguished period-3 features appeared in the coding regions, and the characteristic average code distances of the analyzed sequences were approximately proportional to their GC contents, particularly in the selected prokaryotic organisms, presenting the potential utility as an added taxonomic characteristic for use in studying the relationships of living organisms. [ABSTRACT FROM AUTHOR]

The structural, energetic and electronic properties of carbon nanobuds (CNBs) with the smallest fullerene C20 covalently attached to the sidewall of singlewalled carbon nanotubes (SWNTs) are studied by first-principles calculations. Due to the high curvature of C20 and the resulting chemical activity, the binding between C20 and SWNTs is quite strong. Among different CNB configurations, bond cycloaddition is energetically most favorable. The activation barrier for C20-CNB formation is only one-fourth that of C60 and it would maintain good stability once formed. Our results also reveal that C20-CNB stability depends on the chirality of the SWNTs, and they exhibit tunable band gaps that can be modulated by the density of C20 attached to the SWNTs. [ABSTRACT FROM AUTHOR]

A path integral formulation of the Bianchi I models containing a massless scalar field in loop quantum cosmology is constructed. Following the strategy used in the homogenous and isotropic case, the calculation is extended to the simplest non-isotropic models according to the μ and μ ' schemes. It is proved from the path integral angle that the quantum dynamic lacks the full invariance with respect to fiducial cell scaling in the μ scheme, but it does not in the μ ' scheme. The investigation affirms the equivalence of the canonical approach and the path integral approach in loop quantum cosmology. [ABSTRACT FROM AUTHOR]

Recent functional magnetic resonance imaging studies have shown that the brain is remarkably active even in the absence of overt behavior, and this activity occurs in spatial patterns that are reproducible across subjects and follow the brain's established functional subdivision. Investigating the distribution of these spatial patterns is an active area of research with the goal of obtaining a better understanding of the neural networks underlying brain function. One intriguing aspect of spontaneous activity is an apparent nonstationarity, or variability of interaction between brain regions. It was recently proposed that spontaneous brain activity may be dominated by brief traces of activity, possibly originating from a neuronal avalanching phenomenon. Such traces may involve different subregions in a network at different times, potentially reflecting functionally relevant relationships that are not captured with conventional data analysis. To investigate this, we examined publicly available functional magnetic resonance imaging data with a dedicated analysis method and found indications that functional networks inferred from conventional correlation analysis may indeed be driven by activity at only a few critical time points. Subsequent analysis of the activity at these critical time points revealed multiple spatial patterns, each distinctly different from the established functional networks. The spatial distribution of these patterns suggests a potential functional relevance. [ABSTRACT FROM AUTHOR]

Extracellular adenine nucleotides ATP and ADP on vascular endothelial cells may play a role in the localization of atherogenesis by regulating the release of nitric oxide from endothelial cells and modulating intracellular calcium levels. To quantitatively investigate the concentration distribution of nucleotides on the luminal surface of the human thoracic aorta, we numerically simulated the transport of nucleotides using an aorta model constructed based on MRI images and analyzed the effects of different factors on nucleotide transport, such as ATP release rate (SATP), pulsatile flow and the absence of ATP in the main blood stream. The numerical results revealed that the combined concentration of ATP and ADP (cw-ATP+ADP) on the aortic surface varied from place to place, being relatively low in disturbed flow regions. In addition, cw-ATP+ADP was significantly affected by SATP. For relatively slow SATP, such as the moderate sigmoidal release model, cw-ATP+ADP was very low in certain flow regions with low wall shear stress. However, for very rapid SATP, such as the rapid linear release model, Cw-atp+adp was relatively high in these same regions. The results also demonstrated that for relatively slow Satp, pulsatile blood flow enhanced cw-atp+Adp. However, for very rapid SATP, pulsatile blood flow would reduce cw-ATP+ADP. Moreover, the absence of ATP within the main blood stream would not influence the distribution of cw-ATP+ADP. In conclusion, the concentration distribution of nucleotides along the aortic wall was quite uneven and determined by both the ATP release rate and the blood flow pattern in the aorta. [ABSTRACT FROM AUTHOR]

We have isolated an extraordinary pentapeptide, called 4862F, from the culture broth of Streptomyces albosporus I03A-04862 by Diaion HP-20 macroporous adsorbent resin column, ODS-A and Sephadex LH-20 chromatography, followed by preparative HPLC. This peptide shows inhibitory activity against HIV-1 protease. The structure was elucidated by spectroscopic approaches, including ESI-MS and various NMR methods. Absolute configuration of the amino acid residues in 4862F was defined using Marfey's method, and the structure was identified as N,N,N-(trimethylated)-Tyr-L-Leu-L-Val-L-Leu- (dehydrated)-His. The peptide 4862F displays inhibitory activity against HIV-1 protease, with IC50 values of 15.26 nM, using a fluorescence-based assay. [ABSTRACT FROM AUTHOR]

Objective. To explore the efficacy of Herb-partitioned moxibustion in treating IBS-D patients. Method. 210 IBS-D patients were randomly assigned on a 3 : 3 : 2 basis to group HM, group FM, or group PB for 4-week treatment. The change of GSRS total score at weeks 4 and 8, the changes of GSRS specific scores, and adverse events were evaluated. Results. Patients in group HM and group FM had lower GSRS total score at week 4 (1.98 ± 0.303, 2.93 ± 0.302 versus 3.73 ± 0.449) and at week 8 (2.75 ± 0.306, 3.56 ± 0.329 versus 4.39 ± 2.48) as compared with patients' score in group PB. However, there was no significant difference of GSRS total score between group HM and group FM. The effect of HM was significantly greater than that of oralloy taking PB in ameliorating the symptoms of rugitus (0.38 versus 0.59, P < 0.05), abdominal pain (0.28 versus 0.57, P < 0.01), abdominal distension (0.4 versus 0.7, P < 0.01), and increased passage of stools (0.06 versus 0.25, P < 0.01) at the end of treatment period. In the follow-up period, patients' therapeutic effect in group HM remained greater than that in group FM (in abdominal pain, abdominal distension, and increased passage of stools) and that in group PB (in loose stools). Conclusions. HM appears to be a promising, efficacious, and well-tolerated treatment for patients with IBS-D. [ABSTRACT FROM AUTHOR]

We study the properties and thermodynamic stability of the plane symmetry black hole from the viewpoint of geometry. We find that the Weinhold curvature gives the first-order phase transition at N= 1, where N is a parameter of the plane symmetry black hole while the Ruppeiner one shows first-order phase transition points for arbitrary N ≠ 1. Considering the Legendre invariant proposed by Quevedo et al., we obtain a unified geometry metric, which contains the information of the second-order phase transition. So, the first-order and second-order phase transitions can be both reproduced from the geometry curvatures. The geometry is also found to be curved, and the scalar curvature goes to negative infinity at the Davie phase transition points beyond semiclassical approximation. [ABSTRACT FROM AUTHOR]

This paper presents a numerical study of the nonpremixed stagnation point reverse flow (SPRF) combustor, especially focusing on the influence of air inlet conditions. Modified eddy dissipation concept (EDC) with a reduced mechanism was used to calculate the characteristic of MILD combustion. The results show that the modified EDC with DRM19 mechanism is suitable for the present simulations. Seven additional runs are conducted to find out that it is not necessary to include the influence of low oxygen despite its conduciveness to the establishment of MILD combustion in SPRF combustor. In addition, for the same mass rate of air inlet, it is difficult to reach MILD combustion mode by changing the velocity of the air inlet. The influence of air inlet momentum is also investigated by keeping the air inlet velocity constant and increasing the mass. Although the degree of recirculation (Reg) is small, it can still achieve MILD combustion mode. Compared with the influence of air inlet velocity, it could be concluded that, rather than Reg, the recirculation flow rate is the most important factor. [ABSTRACT FROM AUTHOR]

Bay scallop (Argopecten irradians) is one of the most economically important aquaculture species in China. In this study, we constructed a consensus microsatellite-based genetic linkage map with a mapping panel containing two hybrid backcrosslike families involving two subspecies of bay scallop, A. I. irradians and A. I. concentricus. One hundred sixty-one microsatellite and one phenotypic (shell color) markers were mapped to 16 linkage groups (LGs), which corresponds to the haploid chromosome number of bay scallop. The sex-specific map was 779.2 cM and 781.6 cM long in female and male, respectively, whereas the sex-averaged map spanned 849.3 cM. The average resolution of integrated map was 5.9 cM/locus and the estimated coverage was 81.3%. The proportion of distorted markers occurred more in the hybrid parents, suggesting that the segregation distortion was possibly resulted from heterospecific interaction between genomes of two subspecies of bay scallop. The overall female-to-male recombination rate was 1.13:1 across all linked markers in common to both parents, and considerable differences in recombination also existed among different parents in both families. Four size-related traits, including shell length (SL), shell height (SH), shell width (SW) and total weight (TW) were measured for quantitative trait loci (QTL) analysis. Three significant and six suggestive QTL were detected on five LGs. Among the three significant QTL, two (qSW-10 and qTW-10, controlling SW and TW, respectively) were mapped on the same region near marker AiAD121 on LG10 and explained 20.5% and 27.7% of the phenotypic variance, while the third (qSH-7, controlling SH) was located on LG7 and accounted for 15.8% of the phenotypic variance. Six suggestive QTL were detected on four different LGs. The linkage map and size-related QTL obtained in this study may facilitate marker-assisted selection (MAS) in bay scallop. [ABSTRACT FROM AUTHOR]

A coarse-grained lattice Metropolis Monte Carlo (CG-MMC) method is presented for simulating fluid systems described by standard molecular force fields. First, a thermodynamically consistent coarse-grained interaction potential is obtained numerically and automatically from a continuous force field such as Lennard-Jones. The coarse-grained potential then is used to drive CG-MMC simulations of vapor-liquid equilibrium in Lennard-Jones, square-well, and simple point charge water systems. The CG-MMC predicts vapor-liquid phase envelopes, as well as the particle density distributions in both the liquid and vapor phases, in excellent agreement with full-resolution Monte Carlo simulations, at a fraction of the computational cost. [ABSTRACT FROM AUTHOR]

The usage of mobile phone increases globally. However, there is still a paucity of data about the impact of electromagnetic fields (EMF) on human health. This study investigated whether EMF radiation would alter the biology of glial cells and act as a tumor-promoting agent. We exposed rat astrocytes and C6 glioma cells to 1950-MHz TD-SCDMA for 12, 24 and 48 h respectively, and found that EMF exposure had differential effects on rat astroctyes and C6 glioma cells. A 48 h of exposure damaged the mitochondria and induced significant apoptosis of astrocytes. Moreover, caspase-3, a hallmark of apoptosis, was highlighted in astrocytes after 48 h of EMF exposure, accompanied by a significantly increased expression of bax and reduced level of bcl-2. The tumorigenicity assays demonstrated that astrocytes did not form tumors in both control and exposure groups. In contrast, the unexposed and exposed C6 glioma cells show no significant differences in both biological feature and tumor formation ability. Therefore, our results implied that exposure to the EMF of 1950-MHz TD-SCDMA may not promote the tumor formation, but continuous exposure damaged the mitochondria of astrocytes and induce apoptosis through a caspase-3- dependent pathway with the involvement of bax and bcl-2. [ABSTRACT FROM AUTHOR]

Sensing technology has been widely investigated and utilized for gas detection. Due to the different applicability and inherent limitations of different gas sensing technologies, researchers have been working on different scenarios with enhanced gas sensor calibration. This paper reviews the descriptions, evaluation, comparison and recent developments in existing gas sensing technologies. A classification of sensing technologies is given, based on the variation of electrical and other properties. Detailed introduction to sensing methods based on electrical variation is discussed through further classification according to sensing materials, including metal oxide semiconductors, polymers, carbon nanotubes, and moisture absorbing materials. Methods based on other kinds of variations such as optical, calorimetric, acoustic and gas-chromatographic, are presented in a general way. Several suggestions related to future development are also discussed. Furthermore, this paper focuses on sensitivity and selectivity for performance indicators to compare different sensing technologies, analyzes the factors that influence these two indicators, and lists several corresponding improved approaches. [ABSTRACT FROM AUTHOR]

A group of dynamic-colour white fluorescences with various colour temperatures that can be applied to circadian lighting are achieved in Eu/Tb-codoped lithium-yttrium-aluminium-silicate (LYAS) glasses, which can be attributed to the simultaneous generation of three primary colours emitting from Eu3+ (red), Eu2+ (blue) and Tb3+ (green) by varying the ultraviolet (UV) radiation wavelength. Fluorescence colour coordinates pass through the whole white region of the CIE x, y chromaticity diagram when the UV excitation wavelength is increased from 300 to 370 nm. A favourable white light with colour coordinates (0.338, 0.298) close to the equal energy white is obtained under 360 nm excitation. These results indicate that the Eu/Tb-codoped LYAS glasses are a promising candidate to develop white lighting devices under the excitation of commercial UV light-emitting diodes, and a smart lighting system based on rare-earth doped glasses will be a potential illumination source offering controllability of the colour temperature that can adjust to specific environments and requirements, and benefit human health, well-being and productivity. [ABSTRACT FROM AUTHOR]

Abstract: A type of acoustic carpet cloak has been theoretically designed and numerically implemented in air using steel/air composites. By using the effective medium theory, the effective density and bulk modulus of the composite material are designed to agree with the spatially variant parameters calculated from the coordinate transformation approach. Great cloaking performance is achieved as an object is well hidden under a sound reflective surface in a wide frequency range. It has also been shown that sound can be effectively manipulated using the proposed composite materials because of its low complexity. [Copyright &y& Elsevier]

Abstract: Fuel swelling by fission products is now considered the greatest factor that influences fuel performance. To gain a better understanding of the swelling behavior on UMo/Al fuel, we have investigated gas generation and have characterized fission-product swelling. The matrix-material creep and the interaction between the UMo fuel particles and the Al matrix have also been studied in the modeling of this process. The modeled phenomena also allow the prediction of UMo/Al fuel swelling. The results show that the motion of fission gaseous atoms, bubble growth and evolution and the creep of matrix materials are the basic behaviors of UMo/Al-dispersion fuel swelling. The swelling rate of the fuel exhibits a distinct knee. Before the grain subdivision, the degrees of fuel swelling at different fission rates are not evidently different. After the grain subdivision, the fuel swelling at lower fission rates is faster than that at higher fission rates. The matrix material experiences accelerated creep at high temperatures. If the fuel volume fraction is higher than 52%, the fuel swelling sharply increases after grain subdivision. The results are compared with the data from the literature, and these show reasonable agreement. The analysis provides a plausible interpretation of the behavior of UMo/Al-dispersion fuel swelling. [Copyright &y& Elsevier]

Novel helical macrocyclic imines derived from planar chiral [2.2]paracyclophane were synthesized. The chiroptical properties of the enantiopure compounds were investigated and their absolute configurations were assigned. [ABSTRACT FROM AUTHOR]

Abstract: Two locking-free nonconforming finite elements are presented for three-dimensional elasticity problem with pure displacement boundary condition. Convergence rate of the elements are uniformly optimal with respect to λ. The energy norm and L 2 norm errors are O(h 2) and O(h 3), respectively. Lastly, a numerical experiment is carried out, which coincides with the theoretical analysis. [Copyright &y& Elsevier]

This paper proposes a Bayesian design approach to planning a pre-production accelerated design test (ADT) with physically based statistical models. To motivate the study, we consider the hot-carrier-induced degradation of modern MOS field effect transistors. A single-path power-law statistical degradation model with nonlinear stress-life relationships is first developed. Based on this model, we formulate a Bayesian optimal design problem that minimizes the expected pre-posterior variance of the quantity of interest at use environment. To solve the problem, a simulation-based stochastic optimization method, which yields a consistent estimate of the optimal design, is utilized. As demonstrated by the numerical example, such an algorithm is of great practical importance in planning an ADT because it is considerably faster than the commonly used Monte Carlo simulation for evaluating the expected pre-posterior variance. Finally, we perform a comparison study between the proposed Bayesian plan and the locally optimal plan, which is based on the maximum likelihood theory. Results strongly suggest that the robustness of the proposed plan against the uncertainty associated with planning inputs can be significantly enhanced. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Two new locking-free nonconforming finite elements for the pure displacement planar elasticity problem are presented. Convergence rates of the elements are uniformly optimal with respect to λ. The energy norm and L norm errors are proved to be O( h) and O( h), respectively. Numerical tests confirm the theoretical analysis. [ABSTRACT FROM AUTHOR]

VEGF is an important growth factor in embryonic development and functional maintenance of adult organs. Single allele inactivation of VEGF leads to embryonic lethality and many conditional disruptions show dramatic phenotypes or reduced viabilities. To overcome this burden, a reversible system, which was used in the regulation of VEGF expression and functional studies of many tissues and organs in adult, was developed. VEGF is known for expression in many tissues and high expression in platelets. Repression of VEGF expression showed significant defect in bleeding time and clotting time. In mouse model of LPS-induced blood hypercoagulation, significant reduction of plasma thrombin-antithrombin formation was observed in VEGF repressed mice, and tissues expressed different modes of damages. These results indicate that VEGF regulates coagulation cascade and may affect sepsis. This is the first genetic evidence of direct link between VEGF transcription and coagulation cascade. Studies using this system may help us to find out how VEGF regulates coagulation cascade and provide new strategies in treating coagulation related diseases. © 2010 IUBMB IUBMB Life, 2010. [ABSTRACT FROM AUTHOR]

Background: It is well established that hippocampal activity is positively related to effective associative memory formation. However, in biological systems often optimal levels of activity are contrasted by both sub- and supra-optimal levels. Suboptimal levels of hippocampal activity are commonly attributed to unsuccessful memory formation, whereas the supraoptimal levels of hippocampal activity related to unsuccessful memory formation have been rarely studied. It is still unclear under what circumstances such supra-optimal levels of hippocampal activity occur. To clarify this issue, we aimed at creating a condition, in which supra-optimal hippocampal activity is associated with encoding failure. We assumed that such supra-optimal activity occurs when task-relevant information is embedded in task-irrelevant, distracting information, which can be considered as noise. Methodology/Principal Findings: In the present fMRI study, we probed neural correlates of associative memory formation in a full-factorial design with associative memory (subsequently remembered versus forgotten) and noise (induced by high versus low distraction) as factors. Results showed that encoding failure was associated with supra-optimal activity in the high-distraction condition and with sub-optimal activity in the low distraction condition. Thus, we revealed evidence for a bell-shape function relating hippocampal activity with associative encoding success. Conclusions/Significance: Our findings indicate that intermediate levels of hippocampal activity are optimal while both too low and too high levels appear detrimental for associative memory formation. Supra-optimal levels of hippocampal activity seem to occur when task-irrelevant information is added to task-relevant signal. If such task-irrelevant noise is reduced adequately, hippocampal activity is lower and thus optimal for associative memory formation. [ABSTRACT FROM AUTHOR]

Dielectric properties of LaSrCoAlO ( x=0, 0.1, 0.3, and 0.5) ceramics were investigated in a broad frequency and temperature range. The AC conductivity decreased with the increasing Al concentration. Dielectric constant increased at lower frequency and decreased at higher frequency when the Al concentration increased from 0.1 to 0.3, then it decreased at all frequencies as the x value was 0.5. While the dielectric loss decreased first and then increased with the increasing Al concentration. There was one dielectric relaxation in the curve of temperature dependence of dielectric properties of LaSrCoAlO ceramics. The nonadiabatic small polaronic hopping process should contribute to the dielectric relaxation in the present ceramics. The AC conductivity increased in about one order of magnitude after annealing the sample in the oxygen atmosphere, and this should be attributed to the appearance of interstitial oxygen in the annealed sample. [ABSTRACT FROM AUTHOR]

Selenium, an essential micronutrient for humans, is insufficient in dietary intake for millions of people worldwide. Rice as the most popular staple food in the world is one of the dominant selenium (Se) sources for people. The distribution and translocation of Se from soil to grain were investigated in a Se-rich environment in this study. The Se levels in soils ranged widely from 0.5 to 47.7 mg kg-1. Selenium concentration in rice bran was 1.94 times higher than that in corresponding polished rice. The total Se concentrations in the rice fractions were in the following order: straw > bran > whole grain > polished rice > husk. Significant linear relationships between different rice fractions were observed with each other, and Se in the soil has a linear relationship with different rice fractions as well. Se concentration in rice can easily be predicted by soil Se concentrations or any rice fractions and vice versa according to their linear relationships. In all rice samples for Se speciation, SeMet was the major Se species, followed by MeSeCys and SeCys. The average percentage for SeMet (82.9%) and MeSeCys (6.2%) was similar in the range of total Se from 2.2 to 8.4 mg kg-1 tested. The percentage of SeCys decreased from 6.3 to 2.8%, although its concentration elevated with the increase in total Se in rice. This could be due to the fact that SeCys is the precursor for the formation of other organic Se compounds. The information obtained may have considerable significance for assessing translocation and accumulation of Se in plant. [ABSTRACT FROM AUTHOR]

This paper proposes a Bayesian approach to planning an accelerated life test (ALT) for repairable systems with multiple s-independent failure modes. A power law process (PLP), that combines both proportional intensity (PI) and acceleration time (AT) approaches, is used for modeling the failure process of repairable systems under ALT. Based on the Bayesian D-optimality, and Ds-optimality, we develop optimal plans for ALT by invoking the general equivalence theorem. We also discuss the elicitation of prior distributions, and derive the expression of the Fisher information matrix. Finally, a case study on testing diesel automotive engines is presented to illustrate how to use the proposed planning principle to obtain the 2-stress-level optimal plan, and a compromise plan for 3-stress-level ALT. [ABSTRACT FROM AUTHOR]

In this work, we investigate strain effects induced by the deposition of gate dielectrics on the valence band structures in Si (110) nanowire via the simulation of strain distribution and the calculation of a generalized 6x6k*p strained valence band. The nanowire is surrounded by the gate dielectric. Our simulation indicates that the strain of the amorphous SiO2 insulator is negligible without considering temperature factors. On the other hand, the thermal residual strain in a nanowire with amorphous SiO2 insulator which has negligible lattice misfit strain pushes the valence subbands upwards by chemical vapour deposition and downwards by thermal oxidation treatment. In contrast with the strain of the amorphous SiO2 insulator, the strain of the HfO2 gate insulator in Si (110) nanowire pushes the valence subbands upwards remarkably. The thermal residual strain by HfO2 insulator contributes to the up-shifting tendency. Our simulation results for valence band shifting and warping in Si nanowires can provide useful guidance for further nanowire device design. [ABSTRACT FROM AUTHOR]

Background: We recently developed a new method to induce human stem cells (hESCs) differentiation into hematopoietic progenitors by cell extract treatment. Here, we report an efficient strategy to generate erythroid progenitors from hESCs using cell extract from human fetal liver tissue (hFLT) with cytokines. Human embryoid bodies (hEBs) obtained of human H1 hESCs were treated with cell extract from hFLT and co-cultured with human fetal liver stromal cells (hFLSCs) feeder to induce hematopoietic cells. After the 11 days of treatment, hEBs were isolated and transplanted into liquid medium with hematopoietic cytokines for erythroid differentiation. Characteristics of the erythroid cells were analyzed by flow cytometry, Wright-Giemsa staining, real-time RT-PCR and related functional assays. Results: The erythroid cells produced from hEBs could differentiate into enucleated cells and expressed globins in a time-dependent manner. They expressed not only embryonic globins but also the adult-globin with the maturation of the erythroid cells. In addition, our data showed that the hEBs-derived erythroid cells were able to act as oxygen carriers, indicating that hESCs could generate functional mature erythroid cells. Conclusion: Cell extract exposure with the addition of cytokines resulted in robust erythroid -like differentiation of hEBs and these hEBs-derived erythroid cells possessed functions similar to mature red blood cells. [ABSTRACT FROM AUTHOR]

Background: Oysters are morphologically plastic and hence difficult subjects for taxonomic and evolutionary studies. It is long been suspected, based on the extraordinary species diversity observed, that Asia Pacific is the epicenter of oyster speciation. To understand the species diversity and its evolutionary history, we collected five Crassostrea species from Asia and sequenced their complete mitochondrial (mt) genomes in addition to two newly released Asian oysters (C. iredalei and Saccostrea mordax) for a comprehensive analysis. Results: The six Asian Crassostrea mt genomes ranged from 18,226 to 22,446 bp in size, and all coded for 39 genes (12 proteins, 2 rRNAs and 25 tRNAs) on the same strand. Their genomes contained a split of the rrnL gene and duplication of trnM, trnK and trnQ genes. They shared the same gene order that differed from an Atlantic sister species by as many as nine tRNA changes (6 transpositions and 3 duplications) and even differed significantly from S. mordax in protein-coding genes. Phylogenetic analysis indicates that the six Asian Crassostrea species emerged between 3 and 43 Myr ago, while the Atlantic species evolved 83 Myr ago. Conclusions: The complete conservation of gene order in the six Asian Crassostrea species over 43 Myr is highly unusual given the remarkable rate of rearrangements in their sister species and other bivalves. It provides strong evidence for the recent speciation of the six Crassostrea species in Asia. It further indicates that changes in mt gene order may not be strictly a function of time but subject to other constraints that are presently not well understood. [ABSTRACT FROM AUTHOR]

Stat6 signaling is active in cancer cells and IL-4-induced Stat6 activities or Stat6 activational phenotypes vary among cancer cells. This study aimed at investigating possible mechanism(s) involved in the formation of varying Stat6 activities/phenotypes. Stat6 regulatory genes, SOCS-1 and SHP-1, were examined for mRNA expression using RT-PCR, and their promoter DNA methylation was assayed by methylation-specific PCR in Stat6-phenotyped colon cancer cell lines. DNA methylation was then verified by sequencing. RT-PCR assay and Western blotting were used to detect the expression of SOCS-1 and SHP-1 after demethylation using 5-aza-2′-deoxycytidine. Compared with Stat6null Caco-2 cells, Stat6high HT-29 cells showed decreased constitutive expression of SOCS-1 and SHP-1, which correlated with DNA hypermethylation in these genes’ promoters. Interestingly, demethylation in HT-29 cells recovered the constitutive expression of SOCS-1 and SHP-1. These findings suggest that DNA methylation controls the constitutive expression of negative Stat6 regulatory genes, which may affect Stat6 activities. [ABSTRACT FROM AUTHOR]

Human embryonic stem (hES) cells are typically maintained on mouse embryonic fibroblast (MEF) feeders or with MEF-conditioned medium. However, these xenosupport systems greatly limit the therapeutic applications of hES cells because of the risk of cross-transfer of animal pathogens. The stem cell niche is a unique tissue microenvironment that regulates the self-renewal and differentiation of stem cells. Recent evidence suggests that stem cells are localized in the microenvironment of low oxygen. We hypothesized that hypoxia could maintain the undifferentiated phenotype of embryonic stem cells. We have co-cultured a human embryonic cell line with human fetal liver stromal cells (hFLSCs) feeder cells stably expressing hypoxia-inducible factor-1 alpha (HIF-1α), which is known as the key transcription factor in hypoxia. The results suggested HIF-1α was critical for preventing differentiation of hES cells in culture. Consistent with this observation, hypoxia upregulated the expression of Nanog and Oct-4, the key factors expressed in undifferentiated stem cells. We further demonstrated that HIF-1α could upregulate the expression of some soluble factors including bFGF and SDF-1α, which are released into the microenvironment to maintain the undifferentiated status of hES cells. This suggests that the targets of HIF-1α are secreted soluble factors rather than a cell–cell contact mechanism, and defines an important mechanism for the inhibition of hESCs differentiation by hypoxia. Our findings developed a transgene feeder co-culture system and will provide a more reliable alternative for future therapeutic applications of hES cells. J. Cell. Physiol. 221: 54–66, 2009. © 2009 Wiley-Liss, Inc [ABSTRACT FROM AUTHOR]

Although single nucleotide polymorphisms (SNPs) are important resources for population genetics, pedigree analysis and genomic mapping, such loci have not been reported in Pacific abalone so far. In this study, a bioinformatics strategy was adopted to discover SNPs within the expressed sequences (ESTs) of Pacific abalone, Haliotis discus hannai, and furthermore, polymerase chain reaction direct sequencing (PCR-DS) and allele-specific PCR (AS-PCR) were used for SNPs detection and genotype scoring respectively. A total of 5893 ESTs were assembled and 302 putative SNPs were identified. The average density of SNPs in ESTs was 1%. Fifty-two sets of sequencing primers were designed from SNPs flanking ESTs to amplify the genomic DNA, and 13 could generate products of expected size. Polymerase chain reaction direct sequencing of the amplification products from pooled DNA samples revealed 40 polymorphic SNP loci. Using a modified tetra-primer AS-PCR, seven mitochondrial and six nuclear SNPs were typed and characterized among 37 wild abalones. In conclusion, it is feasible to discover SNPs from number limited ESTs and the AS-PCR as a simple, robust and reliable assay could be a primary method for small- and medium-scale SNPs detection in abalones as well as other non-model organisms. [ABSTRACT FROM AUTHOR]

During winter months, a novel overwintering mode of transferring juvenile abalones to open seawaters in southern China rather than keeping them in closed land-based nursery systems in northern China is a popular practice. The initial size, stocking density and sorting are among the first considerations when establishing an abalone culture system. This study aimed to investigate the effects of these factors on the growth of juvenile Pacific abalone, Haliotis discus hannai Ino, during overwintering. Juvenile abalones were reared in multi-tier basket form for overwintering in open seawaters in southern China for 106 days. The daily growth rates (DGRs) in the shell length of all experimental groups ranged from 67.08 to 135.75 μm day−1, while the specific growth rates (SGRs) were 0.2447–0.3259% day−1. Variance analysis indicated that both DGRs and SGRs in shell length were significantly affected by the initial body size and stocking density. Furthermore, the effects of stocking density on DGRs and SGRs varied with the initial size. However, sorting abalones according to their initial sizes may not be necessary in practice as sorting did not alter growth significantly at all densities in this study. Factors potentially affecting abalone growth such as genetic control and intraspecific competition were discussed. [ABSTRACT FROM AUTHOR]

From the viewpoint of quantum information, this paper proposes a concept and a definition of the atomic optimal entropy squeezing sudden generation (AOESSG) for the system of an effective two-level moving atom which entangles with the two-mode coherent fields. It also researches the relationship between the AOESSG and entanglement sudden death of the atom-fields, and discusses the influences of atomic initial state on the AOESSG and obtains the system parameter which controls the AOESSG. [ABSTRACT FROM AUTHOR]

In this paper, we mainly investigate the W ⊗ W system, in which the matter and the Liouville subsystems generate the W and W algebras, respectively. We first give a brief discussion of the physical states for the corresponding W strings. The lower states are given by freezing the spin-2 and spin- s currents. Then, introducing two pairs of ghost-like fields, we give the realizations of the W1,2, s algebras. Based on these linear realizations, the BRST operators for the W2, s algebras are obtained. Finally, we construct new BRST charges of the Liouville system for the W strings at the specific values of the central charges c: $c=-\frac{22}{5}$ for the W algebra, c=−24 for the W algebra and $c=-2,-\frac{286}{3}$ for the W algebra, at which the corresponding W algebras are singular. [ABSTRACT FROM AUTHOR]

Here, we have now developed a new inducing system to promote the differentiation of human stem cells (hESCs) toward hematopoietic lineages by the treatment with cells extract of human fetal liver tissue (hFLT). The embryoid bodies (EBs) obtained from human H1 embryonic stem cells were exposed to buffer, hFLT cells extract, heated hFLT cell extract, and cell extract of human liver cells lines-LO2. Then, the feature of EBs in different groups was characterized by real-time RT-PCR and colony-forming assays. The results showed the treatment by hFLT cells extract could activate the hematopoietic genes expression and improve the capacity for hematopoietic progenitor development of hEBs. After that, we cocultured hFLT extract treated hEBs on the hFLSCs (human fetal liver stromal cells) feeder to differentiate them into hematopoietic cells. As a control, untreated hEBs were cocultured on hFLSCs feeder with cytokines. The feature of induced cells from hEBs was characterized by flow cytometry, Wright-Giemsa staining, and colony-forming assays. The results demonstrated that hFLT cells extract was capable of inducing hEBs into hematopoietic cells and combing it with hFLSCs feeder could largely promote hematopoietic differentiation of hESCs. This method may supply a new way to substitute the cytokines required in hematopoietic induction of hESCs. [ABSTRACT FROM AUTHOR]

In the analysis of accelerated life testing (ALT) data, some stress-life model is typically used to relate results obtained at stressed conditions to those at use condition. For example, the Arrhenius model has been widely used for accelerated testing involving high temperature. Motivated by the fact that some prior knowledge of particular model parameters is usually available, this paper proposes a sequential constant-stress ALT scheme and its Bayesian inference. Under this scheme, test at the highest stress is firstly conducted to quickly generate failures. Then, using the proposed Bayesian inference method, information obtained at the highest stress is used to construct prior distributions for data analysis at lower stress levels. In this paper, two frameworks of the Bayesian inference method are presented, namely, the all-at-one prior distribution construction and the full sequential prior distribution construction. Assuming Weibull failure times, we (1) derive the closed-form expression for estimating the smallest extreme value location parameter at each stress level, (2) compare the performance of the proposed Bayesian inference with that of MLE by simulations, and (3) assess the risk of including empirical engineering knowledge into ALT data analysis under the proposed framework. Step-by-step illustrations of both frameworks are presented using a real-life ALT data set. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We discuss the following viscosity approximations with the weak contraction A for a non-expansive mapping sequence {Tn}, yn = αnAyn + (1 - αn)Tnyn, xn+1 = αnAxn + (1 - αn)Tnxn. We prove that Browder's and Halpern's type convergence theorems imply Moudafi's viscosity approximations with the weak contraction, and give the estimate of convergence rate between Halpern's type iteration and Mouda's viscosity approximations with the weak contraction. [ABSTRACT FROM AUTHOR]

Duplications and rearrangements of coding genes are major themes in the evolution of mitochondrial genomes, bearing important consequences in the function of mitochondria and the fitness of organisms. Yu et al. (BMC Genomics 2008, 9:477) reported the complete mt genome sequence of the oyster Crassostrea hongkongensis (16,475 bp) and found that a DNA segment containing four tRNA genes (trnK1, trnC, trnQ1 and trnN), a duplicated (rrnS) and a split rRNA gene (rrnL5') was absent compared with that of two other Crassostrea species. It was suggested that the absence was a novel case of "tandem duplication-random loss" with evolutionary significance. We independently sequenced the complete mt genome of three C. hongkongensis individuals, all of which were 18,622 bp and contained the segment that was missing in Yu et al.'s sequence. Further, we designed primers, verified sequences and demonstrated that the sequence loss in Yu et al.'s study was an artifact caused by placing primers in a duplicated region. The duplication and split of ribosomal RNA genes are unique for Crassostrea oysters and not lost in C. hongkongensis. Our study highlights the need for caution when amplifying and sequencing through duplicated regions of the genome. [ABSTRACT FROM AUTHOR]

A dual-band 1:3 series power divider that provides equal power splits to all three output ports is presented. To achieve dual-band working, the divider employs, instead of conventional transmission lines of one wavelength, the composite right/left-handed transmission lines (CRLH TLs) yielding electrical length of 0 and -2π at 1.14 and 2.47 GHz, respectively. Dual-frequency transformers in two sections are added at the output ports to provide dual-band impedance matching. Two pairs of isolation resistors are used to isolate the three output ports from each other, and their values are determined by solving the equivalent network model of the divider. The isolation between any of the two output ports is measured to be larger than 20 dB at both frequencies, which is of great use in power combination, and the dual-band divider maintains a relatively compact size. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3236–3239, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23927 [ABSTRACT FROM AUTHOR]

Abstract  It has been reported that alfacalcidol had an anticatabolic and anabolic effect on bone in ovariectomized and aged male rat models, but this has not been tested on intact female rats. The current study was to determine the effects of alfacalcidol on cancellous and cortical bone in intact female rats with or without exercise. Seventy-four, 8.5-month-old, intact female rats were orally treated with 0, 0.005, 0.025, 0.05, or 0.1 μg/kg alfacalcidol alone or in combination with raised cage (RC) exercise for 3 months. In vivo peripheral quantitative computerized tomography (pQCT) of the proximal tibial metaphyses (PTM) and ex vivo histomorphometric analyses of the PTM and tibial shaft (TX) were performed. Only the 0.1 μg alfacalcidol/kg dose proved to be anabolic. pQCT analysis showed that this dose increased total and cortical bone mineral content and density and trabecular bone mineral density. Histomorphometrically, it induced an anabolic response by increased trabecular mass and microarchitecture from stimulated cancellous bone and bone bouton formations, and suppressed bone resorption more than bone formation on the trabecular and endocortical surfaces, to produce a positive bone balance. A positive correlation between trabecular connectivity and bone bouton numbers occurred. These findings suggest alfacalcidol treatment augments bone mass by increased cancellous bone mass and improved trabecular architecture through its anticatabolic and anabolic properties in the intact adult female rat. Last, raised cage exercise alone or the combination of raised cage and alfacalcidol was no more effective than alfacalcidol alone. [ABSTRACT FROM AUTHOR]

Considering that gravitational force might deviate from Newton's inverse-square law and become much stronger in small scale, we present a method to detect the possible existence of extra dimensions in the ADD model. By making use of an effective variational wave function, we obtain the nonrelativistic ground energy of a helium atom and its isoelectronic sequence. Based on these results, we calculate gravity correction of the ADD model. Our calculation may provide a rough estimation about the magnitude of the corresponding frequencies which could be measured in later experiments. [ABSTRACT FROM AUTHOR]

We have evaluated the effects of recombination processes in a charge storage layer, either between trapped electrons and trapped holes or between trapped carriers and free carriers, on charge trapping memory cell's performances by numerical simulation. Recombination is an indispensable mechanism in charge trapping memory. It helps charge convert process between negative and positive charges in the charge storage layer during charge trapping memory programming/erasing operation. It can affect the speed of programming and erasing operations. [ABSTRACT FROM AUTHOR]

A base population of the bay scallop, Argopecten irradians irradians Lamarck, was produced by crossing two cultured bay scallop populations. After 1 year of rearing, the top 10% truncation selection of the top 10% ( i=1.755) was carried out in the base population of about 1300 adults. A control parental group with a an identical number to the select parental group was randomly selected from the entire population before isolation of the select parental group. The result showed that, at the larval stage, the growth rate of larvae in the selected line was significantly higher than that of the control ( P<0.05), and that the genetic gain was 6.78%. Owing to the lower density of control at the spat stage, the mean shell length of the control line was larger than that of the select line at day 100. When the same density was adjusted between two lines in the grow-out stage (from day 100 to 160), the daily growth rate of the selected line was significantly higher than that of the control line ( P<0.05). Survival of the select line was significantly larger than that of the control line in the grow-out stage. In conclusion, the results obtained from this experiment indicate that selective breeding from a base population with a high genetic diversity established by mass spawning between different populations appears to be a promising method of genetic improvement in bay scallop, A. irradians irradians Lamarck. [ABSTRACT FROM AUTHOR]

This paper presents a semi-analytical approach for electrical performance modeling of complex electronic packages with multiple power/ground planes and large number of vias. The method is based on the modal expansion technique and the method of moments. For the inner package domain with multiple power! ground planes and many vias, the modal expansion method is employed to compute the electromagnetic fields from which the multiport network parameters, e.g., the admittance matrix can be easily obtained. For the top/bottom domain of signal layers, the moment method is used to extract the equivalent resistance, inductance, capacitance, and conductance (RLCG) parameters. The equivalent circuit for the entire package is then generated by combining the results for both package domains. The equivalent circuit can be used in a SPICE-like simulator to study the signal and power integrity of an electronic package. Numerical examples demonstrate that the new approach is able to provide fast yet accurate signal and power integrity analysis of multilayered electronic packages. [ABSTRACT FROM AUTHOR]