Evolution of superconductivity in K2-xFe4+ySe5: Spectroscopic studies of X-ray absorption and emission.

This study investigates the evolution of superconductivity in K2-xFe4+ySe5 using temperature-dependent X-ray absorption and resonant inelastic X-ray scattering techniques. Magnetization measurements show that polycrystalline superconducting (SC) K1.9Fe4.2Se5 has a critical temperature (T c) of ∼31 K with a varying superconducting volume fraction, which strongly depends on its synthesis temperature. An increase in Fe-structural/vacancy disorder in SC samples with more Fe atoms occupying vacant 4d sites is found to be closely related to the decrease in the spin magnetic moment of Fe. Moreover, the nearest-neighbor Fe-Se bond length in SC samples exceeds that in the non-SC (NS) sample, K2Fe4Se5, which indicates a weaker hybridization between the Fe 3d and Se 4p states in SC samples. These results clearly demonstrate the correlations among the local electronic and atomic structures and the magnetic properties of K2-xFe4+ySe5 superconductors, providing deeper insight into the electron pairing mechanisms of superconductivity

Modeling of Ultrasonic Signals from Weak Inclusions

Recent research efforts aimed at improving the detection of hard-alpha inclusions have emphasized the need for accurately modeling the responses from such weakly-reflecting inclusions. The need arises because of the rare natural occurrence of hard-alpha inclusions, and consequently, the lacks of suitable experimental samples. These difficulties lend impetus to the application of signal modeling to augment and extend the experimental data in assessing detectability. Currently, a new approach is being developed for the purpose of predicting time-domain echoes from inclusions of specified morphology. This work is the continuation of our previous study of flat-bottomed holes [1–2] in constructing a methodology for estimating the probability of detection of flaws in titanium alloys based on a combination of physical and statistical models

DNA barcoding reveals the coral “laboratory-rat”, Stylophora pistillata encompasses multiple identities

Stylophora pistillata is a widely used coral “lab-rat” species with highly variable morphology and a broad biogeographic range (Red Sea to western central Pacific). Here we show, by analysing Cytochorme Oxidase I sequences, from 241 samples across this range, that this taxon in fact comprises four deeply divergent clades corresponding to the Pacific-Western Australia, Chagos-Madagascar-South Africa, Gulf of Aden-Zanzibar-Madagascar, and Red Sea-Persian/Arabian Gulf-Kenya. On the basis of the fossil record of Stylophora, these four clades diverged from one another 51.5-29.6 Mya, i.e., long before the closure of the Tethyan connection between the tropical Indo-West Pacific and Atlantic in the early Miocene (16–24 Mya) and should be recognised as four distinct species. These findings have implications for comparative ecological and/or physiological studies carried out using Stylophora pistillata as a model species, and highlight the fact that phenotypic plasticity, thought to be common in scleractinian corals, can mask significant genetic variation

N=8 Superspace Constraints for Three-dimensional Gauge Theories

We present a systematic analysis of the N=8 superspace constraints in three space-time dimensions. The general coupling between vector and scalar supermultiplets is encoded in an SO(8) tensor W_{AB} which is a function of the matter fields and subject to a set of algebraic and super-differential relations. We show how the conformal BLG model as well as three-dimensional super Yang-Mills theory provide solutions to these constraints and can both be formulated in this universal framework.Comment: 34 + 10 pages; added references, minor correction

High carriage rate of high-level penicillin-resistant Streptococcus pneumoniae in a Taiwan kindergarten associated with a case of pneumococcal meningitis

BACKGROUND: The Taiwan(19F)-14 Streptococcus pneumoniae clone and its variants are being found with increasing frequency in the Asia-Pacific region. A 5-year old child with S. pneumoniae meningitis caused by a high-level penicillin resistant strain (MIC = 4 μg/ml) was admitted to a hospital in southern Taiwan. We carried out a study to determine the potential source of this strain. METHODS: Nasopharyngeal cultures were obtained from all children attending the same kindergarten as the index case. To determine their relatedness all isolates were compared by serotype, antimicrobial susceptibility profile and pulsed field gel electrophoresis (PFGE). RESULTS: A high proportion of the children including the index case (32/78, 41.0%) carried S. pneumoniae in their nasopharynx (NP). The most common serotype was 19F (13/32, 40.6%). The PFGE types of the 19F serotype isolates obtained from the patient's blood, CSF and NP were identical and were related to 11 other serotype 19F NP isolates including 10 that were indistinguishable from the Taiwan(19F)-14 clone. All 14 isolates had similar high-level penicillin and multi-drug resistance. The serotypes of the other 19 NP isolates included 6A (2), 6B (10), 23F (5), 9V (1) and 3 (1). The overall rate of penicillin resistance in these S. pneumoniae from these children was 87.5% (28/32), with an MIC(50 )of 2 and MIC(90 )of 4 ug/ml. In addition, multi-drug resistant-isolates (isolates resistant to 3 different classes of antimicrobials) accounted for 87.5% (28/32) of all isolates. CONCLUSION: The high carriage rate of high-level penicillin- and multi-drug- resistant S. pneumoniae in a kindergarten associated with a case of pneumococcal meningitis emphasizes the need for restraint in antibiotic use and consideration of childhood immunization with conjugate pneumococcal vaccine to prevent the further spread of resistant S. pneumoniae in Taiwan

Chuanxiongzine relaxes isolated corpus cavernosum strips and raises intracavernous pressure in rabbits

It has been shown that there are many Chinese traditional herbals that can enhance sexual activity. Chuanxiongzine is a vasoactive ingredient that has been isolated and purified from Ligusticum chuanxiong Hort. In previous studies, it has been found that chuanxiongzine was effective in relaxing rabbit corpus cavernosum smooth muscle. We determined the effects of chuanxiongzine on relaxation of isolated corpus cavernosum strips in vitro and on increase of intracavernous pressure (ICP) in vivo in rabbits. Chuanxiongzine caused a concentration-dependent relaxation of phenylephrine precontracted isolated corpus cavernosum strips (EC50 1.58 × 10−4 mol l−1), which were endothelium independent and NO independent. However, the guanylyl cyclase inhibitor 1-H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one significantly shifted the chuanxiongzine concentration–response relationship to the right. Although there was no significant difference in the level of cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) in isolated corpus cavernosum strips treated with chuanxiongzine or vehicle, chuanxiongzine caused a significant rise in the level of cGMP and cAMP in isolated corpus cavernosum strips pretreated with the activator of adenylyl cyclase forskolin and the source of NO sodium nitroprusside. In an in vivo study, chuanxiongzine dose-dependently raised ICP after the intracavernous injection of its cumulative doses (0.5, 1, 2 and 5 mg kg−1). The ICP increased from baseline to 19.1±3.7, 24.8±2.1, 30.2±4.8 and 39.7±6.1 mm Hg, respectively, and the duration of tumescence ranged from 8.5±2.8 to 22.9±7.3 min. Our results show that chuanxiongzine can relax isolated corpus cavernosum strips of rabbits in vitro and increase ICP of rabbits in vivo, which is neither endothelium dependent nor NO dependent, but may be partly mediated by the inhibition of cAMP phosphodiesterase or cGMP phosphodiesterase

Physiologically based pharmacokinetic modeling of arterial – antecubital vein concentration difference

BACKGROUND: Modeling of pharmacokinetic parameters and pharmacodynamic actions requires knowledge of the arterial blood concentration. In most cases, experimental measurements are only available for a peripheral vein (usually antecubital) whose concentration may differ significantly from both arterial and central vein concentration. METHODS: A physiologically based pharmacokinetic (PBPK) model for the tissues drained by the antecubital vein (referred to as "arm") is developed. It is assumed that the "arm" is composed of tissues with identical properties (partition coefficient, blood flow/gm) as the whole body tissues plus a new "tissue" representing skin arteriovenous shunts. The antecubital vein concentration depends on the following parameters: the fraction of "arm" blood flow contributed by muscle, skin, adipose, connective tissue and arteriovenous shunts, and the flow per gram of the arteriovenous shunt. The value of these parameters was investigated using simultaneous experimental measurements of arterial and antecubital concentrations for eight solutes: ethanol, thiopental, (99)Tc(m)-diethylene triamine pentaacetate (DTPA), ketamine, D(2)O, acetone, methylene chloride and toluene. A new procedure is described that can be used to determine the arterial concentration for an arbitrary solute by deconvolution of the antecubital concentration. These procedures are implemented in PKQuest, a general PBPK program that is freely distributed . RESULTS: One set of "standard arm" parameters provides an adequate description of the arterial/antecubital vein concentration for ethanol, DTPA, thiopental and ketamine. A significantly different set of "arm" parameters was required to describe the data for D(2)O, acetone, methylene chloride and toluene – probably because the "arm" is in a different physiological state. CONCLUSIONS: Using the set of "standard arm" parameters, the antecubital vein concentration can be used to determine the whole body PBPK model parameters for an arbitrary solute without any additional adjustable parameters. Also, the antecubital vein concentration can be used to estimate the arterial concentration for an arbitrary input for solutes for which no arterial concentration data is available

N-acetyltransferase 2 (NAT2) gene polymorphisms in colon and lung cancer patients

BACKGROUND: N-acetyltransferase 2 (NAT2) metabolizes arylamines and hydrazines moeities found in many therapeutic drugs, chemicals and carcinogens. The gene encoding NAT2 is polymorphic, thus resulting in rapid or slow acetylator phenotypes. The acetylator status may, therefore, predispose drug-induced toxicities and cancer risks, such as bladder, colon and lung cancer. Indeed, some studies demonstrate a positive association between NAT2 rapid acetylator phenotype and colon cancer, but results are inconsistent. The role of NAT2 acetylation status in lung cancer is likewise unclear, in which both the rapid and slow acetylator genotypes have been associated with disease. METHODS: We investigated three genetic variations, c.481C>T, c.590G>A (p.R197Q) and c.857G>A (p.G286E), of the NAT2 gene, which are known to result in a slow acetylator phenotype. Using validated PCR-RFLP assays, we genotyped 243 healthy unrelated Caucasian control subjects, 92 colon and 67 lung cancer patients for these genetic variations. As there is a recent meta-analysis of NAT2 studies on colon cancer (unlike in lung cancer), we have also undertaken a systematic review of NAT2 studies on lung cancer, and we incorporated our results in a meta-analysis consisting of 16 studies, 3,865 lung cancer patients and 6,077 control subjects. RESULTS: We did not obtain statistically significant differences in NAT2 allele and genotype frequencies in colon cancer patients and control group. Certain genotypes, however, such as [c.590AA+c.857GA] and [c.590GA+c.857GA] were absent among the colon cancer patients. Similarly, allele frequencies in lung cancer patients and controls did not differ significantly. Nevertheless, there was a significant increase of genotypes [c.590GA] and [c.481CT+c.590GA], but absence of homozygous c.590AA and [c.590AA+c.857GA] in the lung cancer group. Meta-analysis of 16 NAT2 studies on lung cancer did not evidence an overall association of the rapid or slow acetylator status to lung cancer. Similarly, the summary odds ratios obtained with stratified meta-analysis based on ethnicity, and smoking status were not significant. CONCLUSION: Our study failed to show an overall association of NAT2 genotypes to either colon or lung cancer risk

Nanoparticle Network Formation in Nanostructured and Disordered Block Copolymer Matrices

Incorporation of nanoparticles composed of surface-functionalized fumed silica (FS) or native colloidal silica (CS) into a nanostructured block copolymer yields hybrid nanocomposites whose mechanical properties can be tuned by nanoparticle concentration and surface chemistry. In this work, dynamic rheology is used to probe the frequency and thermal responses of nanocomposites composed of a symmetric poly(styrene-b-methyl methacrylate) (SM) diblock copolymer and varying in nanoparticle concentration and surface functionality. At sufficiently high loading levels, FS nanoparticle aggregates establish a load-bearing colloidal network within the copolymer matrix. Transmission electron microscopy images reveal the morphological characteristics of the nanocomposites under these conditions