One-phase controlled synthesis of Au25 nanospheres and nanorods from 1.3 nm Au : PPh3 nanoparticles: the ligand effects

We report the controlled synthesis of [Au25(PPh3)10(SR1)5X2](2+) nanorods (H-SR1: alkyl thiol, H-SC2H4Ph and H-S(n-C6H13)) and Au25(SR2)18 nanospheres (H-SR2: aromatic thiol, H-SPh and H-SNap) under the one-phase thiol etching reaction of the polydisperse Aun(PPh3)m parent-particles (core diameter: 1.3 ± 0.4 nm, 20 < n < 50). These as-obtained gold nanoclusters are identified by UV-vis spectroscopy and matrix-assisted laser desorption ionization mass spectrometry. Furthermore, the conversion process, from Aun(PPh3)m nanoparticles to Au25(SNap)18 nanospheres, is monitored by UV-vis spectroscopy. It is observed that the Au25(PPh3)10(SR1)5X2 nanorods cannot convert to Au25(SR)18 nanospheres in the presence of excess thiol (both the alkyl and aromatic thiol) even under thermal conditions (e.g., 55 and 80 °C), indicating that both the Au25 nanorods and nanospheres are in a stable state during the alkyl and aromatic thiol etching reactions, respectively. The two different conversion pathways (i.e., to Au25(PPh3)10(SR1)5X2 nanorods and Au25(SR2)18 nanospheres) mainly are attributed to the different electronic properties and the steric effects of the alkyl and aromatic thiol ligands. The significant ligand effect also is observed in catalytic CO oxidation. The Au25(SC2H4Ph)18/CeO2 catalyst shows catalytic activity at 80 °C and reaches up to 80.7% and 98.5% (based on CO conversion) at 100 and 150 °C, while Au25(SNap)18/CeO2 and Au25(PPh3)10(SC2H4Ph)5X2/CeO2 give rise to a low activity at 100 °C with only 3.3% and 10.2% CO conversion and 98.0% and 94.6% at 150 °C.

Antibacterial and photochemical properties of cellulose nanofiber-titania nanocomposites loaded with two different types of antibiotic medicines

Nanocomposite dermal drug delivery systems based on cellulose nanofibers with grafted titania nanoparticles loaded by two antibiotic medicines from different classes, i.e. tetracycline (TC) and phosphomycin (Phos), were successfully produced by a "green chemistry" approach in aqueous media. The influence of a different surface binding mechanism between the drug molecule and modified cellulose nanofibers on the release of the drug and, as a result, on antimicrobial properties against common pathogens Gram-positive, Staphylococcus aureus and Gram-negative Escherichia coli was investigated. The disk diffusion method and broth culture tests using varying concentrations of drugs loaded to nanocomposites were carried out to investigate the antibacterial effects. The influence of UV irradiation on the stability of the obtained nanocomposites and their antibacterial properties after irradiation were also investigated, showing enhanced stability especially for the TC loaded materials. These findings suggest that the obtained nanocomposites are promising materials for the development of potentially useful antimicrobial patches.

OsMYB511 encodes a MYB domain transcription activator early regulated by abiotic stress in rice

The MYB-domain proteins exist universally across diverse organisms and regulate numerous processes during the plant life cycle. In the present research, a full-length MYB gene OsMYB511 was identified from rice seedlings through microarray data. Induction of OsMYB511 by cold stress was dramatic in japonica cultivar Jiucaiqing as compared to indica IR26. In addition to cold, OsMYB511 was also markedly induced by osmotic stress, high temperature, and exogenous ABA, suggesting that OsMYB511 is a multiple-stress responsive gene in rice. Tissue-specific expression analysis indicated that OsMYB511 was highly expressed in rice panicles at earlier development stage. Interestingly, OsMYB511 expression is fully subjected to circadian rhythm regulation. The subcellular localization and yeast hybrid assay suggested that OsMYB511 is nucleus-localized transcription activator. Deletion analysis suggested that trans-activation activity of OsMYB511 relied on its C-terminus. Co-expression analysis revealed additional 2 MYB genes co-expressed with OsMYB511, implying that these MYB genes might coordinately regulate stress responses in rice.

A learnable parallel processing architecture towards unity of memory and computing

Developing energy-efficient parallel information processing systems beyond von Neumann architecture is a long-standing goal of modern information technologies. The widely used von Neumann computer architecture separates memory and computing units, which leads to energy-hungry data movement when computers work. In order to meet the need of efficient information processing for the data-driven applications such as big data and Internet of Things, an energy-efficient processing architecture beyond von Neumann is critical for the information society. Here we show a non-von Neumann architecture built of resistive switching (RS) devices named "iMemComp", where memory and logic are unified with single-type devices. Leveraging nonvolatile nature and structural parallelism of crossbar RS arrays, we have equipped "iMemComp" with capabilities of computing in parallel and learning user-defined logic functions for large-scale information processing tasks. Such architecture eliminates the energy-hungry data movement in von Neumann computers. Compared with contemporary silicon technology, adder circuits based on "iMemComp" can improve the speed by 76.8% and the power dissipation by 60.3%, together with a 700 times aggressive reduction in the circuit area.

[Pharmacokinetics of loganin, ferulic acid and stilbene glucoside in Bushen Tongluo formula in vivo]

To study the pharmacokinetics characteristic of loganin, ferulic acid and stilbene glucoside in rat plasma after oral administration of Bushen Tongluo formula. The plasma samples were treated by using liquid-liquid extraction technique, the concentrations were determined by HPLC-UV. Johnson spherigel C18 column (4.6 mm x 250 mm, 5 μm) was adopted and eluted with the of mobile phase of methanol-water containing 0.01% glacial acetic acid in a gradient mode, with the flow rate at 1.0 mL x min(-1), column temperature at 30 degrees C and injection volume of 10 μL. According to the findings, loganin was determined at 235 nm, ferulic acid and stilbene glucoside were determined at 320 nm, with the sample size of 10 μL. The pharmacokinetic parameters of loganin, ferulic acid and stilbene glucoside were calculated by DAS 2. 0 software as follows: C(max) was (0.369 ± 0.042), (0.387 ± 0.071), (0.233 ± 0.044) mg x L(-1); t(max) was (0.226 ± 0.022), (0.282 ± 0.031), (0.233 ± 0.044) h; t(½β) was (6.89 ± 0.20), (10.73 ± 0.11), (6.93 ± 0.09) h; AUC(0-∞) was (1.91 ± 0.36), (3.22 ± 0.52), (1.52 ± 0.33) mg x h x L(-1); AUCO(0-t) was (1.62 ± 0.33), (2.58 ± 0.43), (1.30 ± 0.30) mg x h x L(-1); CL was (20.2 ± 4.0), (1.39 ± 0.23), (31.7 ± 6.9) L x h(-1) x kg(-1), respectively. The results showed that after the oral administration with Bushen Tongluo formula, loganin, ferulic acid and stilbene glucoside showed concentration-time curves in conformity with the two compartment model, with a rapid absorption, loganin and stilbene glucoside was excreted at a moderate speed, and ferulic acid was excreted slowly (but with the highest bioavailability). Bushen Tongluo formula can main maintain plasma concentration with three administrations everyday and so is suitable to be made into common oral preparation.

Galangin-induced down-regulation of BACE1 by epigenetic mechanisms in SH-SY5Y cells

Alzheimer's disease (AD), the most common cause of dementia in aging people, is found to have a critical link with the deposition of β-amyloid (Aβ) in the brain. The inhibition of β-site amyloid precursor protein-cleaving enzyme 1 (BACE1), a key enzyme for Aβ production, is a promising target for AD therapy. In pursuit to find a potent inhibitor of BACE1, we identified galangin, a natural flavonoid, had a significant lowering effect on Aβ levels. Furthermore, a dramatic reduction of BACE1 at mRNA and protein levels was observed after galangin treatment. We further investigated whether epigenetic mechanisms, such as histone acetylation and DNA methylation, were involved in galangin-induced transcriptional regulation of BACE1. Our data show that galangin induces a decrease of acetylated H3 in the BACE1 promoter regions through the up-regulation of endogenous HDAC1-mediated deacetylation, which is independent of DNA methylation status. The above findings suggest a novel mechanism for polyphenols' neuroprotective effect in neurodegeneration and galangin as a potential drug candidate for AD therapy.

Extension of the Peters-Belson method to estimate health disparities among multiple groups using logistic regression with survey data

Determining the extent of a disparity, if any, between groups of people, for example, race or gender, is of interest in many fields, including public health for medical treatment and prevention of disease. An observed difference in the mean outcome between an advantaged group (AG) and disadvantaged group (DG) can be due to differences in the distribution of relevant covariates. The Peters-Belson (PB) method fits a regression model with covariates to the AG to predict, for each DG member, their outcome measure as if they had been from the AG. The difference between the mean predicted and the mean observed outcomes of DG members is the (unexplained) disparity of interest. We focus on applying the PB method to estimate the disparity based on binary/multinomial/proportional odds logistic regression models using data collected from complex surveys with more than one DG. Estimators of the unexplained disparity, an analytic variance-covariance estimator that is based on the Taylor linearization variance-covariance estimation method, as well as a Wald test for testing a joint null hypothesis of zero for unexplained disparities between two or more minority groups and a majority group, are provided. Simulation studies with data selected from simple random sampling and cluster sampling, as well as the analyses of disparity in body mass index in the National Health and Nutrition Examination Survey 1999-2004, are conducted.  Empirical results indicate that the Taylor linearization variance-covariance estimation is accurate and that the proposed Wald test maintains the nominal level.

Down-regulated CBS/H2S pathway is involved in high-salt-induced hypertension in Dahl rats

BACKGROUND

The study was designed to explore the significance of endogenous H2S in the development of high-salt-induced hypertension in rats.

METHODS

High-salt-induced hypertension rat model was made by feeding Dahl rat high-salt diet containing 8% NaCl for 8 weeks with SD rats as control. SBP and aorta structure in rats were observed. Endogenous H2S content and expression of cystathionine β-lyase (CBS), cystathionine γ-lyase and mercaptopyruvate sulfurtransferase in renal tissues were detected. Mechanisms for the impact of high-salt on CBS/H2S in renal tissues were studied, targeting HIF-1α pathway. The effect of H2S on RAS in serum and renal tissue of rats were tested.

RESULTS

High-salt reduced endogenous H2S content and inhibited the expression of CBS in renal tissue in salt-sensitive Dahl rats. H2S donor, however, inhibited salt-sensitive hypertension, reversed aortic structural remodeling and inhibited activation of the RAS system in renal tissues in Dahl rats. Expression of HIF-1α was decreased but expression of PHD2 was increased in renal tissue of Dahl rats with high-salt diet, whereas they did not alter in renal tissue of SD rats with high-salt diet. Ex vivo experiment showed that inhibitor of HIF-1α degradation could rescue down-regulated CBS/H2S pathway in renal tissue of Dahl rats with high-salt. In contrast, inhibitor of HIF-1α activity decreased the CBS/H2S pathway in the renal tissue of SD rats treated with high-salt.

CONCLUSIONS

Down-regulated CBS/H2S pathway in renal tissues under high-salt insult might be an important pathogenesis of salt-sensitive hypertension.

Expression of histone H3 lysine 4 methylation and its demethylases in the developing mouse testis

Histone H3 lysine 4 methylation (H3K4me) is an epigenetic modification associated with gene activation and is dynamically regulated by histone methylases and demethylases. To date, the expression patterns of H3K4me and its demethylases in the developing testis remain unclear. The present study was designed to detect the expression of H3K4me1/2/3 and its demethylases LSD1, RBP2 and SMCX in 21-, 40- and 60-day-old mouse testes by using immunohistochemistry, quantitative real-time polymerase chain reaction (PCR) and Western blot. The immunohistochemical results demonstrated that the expression patterns of the same protein were similar in testes at different ages and that the positive staining cell types were mainly Leydig cells, type A and B spermatogonia, leptotene spermatocytes and spermatids for H3K4me1/2/3, Leydig cells, type A spermatogonia, zygotene and pachytene spermatocytes, spermatids, and Sertoli cells for LSD1 and type A and B spermatogonia for RBP2. Immunostaining for SMCX was not detected in testes. Quantitative real-time PCR and Western blot showed that the amounts of LSD1, RPB2 and SMCX mRNA and protein were age-dependent, were significantly reduced with increasing age and exhibited a negative correlation with the protein levels of H3K4me1/2/3. Thus, H3K4me, which is modified by its demethylases, probably plays a role in male spermatogenesis and testis development.

KCNQ/Kv7 channel activator flupirtine protects against acute stress-induced impairments of spatial memory retrieval and hippocampal LTP in rats

Spatial memory retrieval and hippocampal long-term potentiation (LTP) are impaired by stress. KCNQ/Kv7 channels are closely associated with memory and the KCNQ/Kv7 channel activator flupirtine represents neuroprotective effects. This study aims to test whether KCNQ/Kv7 channel activation prevents acute stress-induced impairments of spatial memory retrieval and hippocampal LTP. Rats were placed on an elevated platform in the middle of a bright room for 30 min to evoke acute stress. The expression of KCNQ/Kv7 subunits was analyzed at 1, 3 and 12 h after stress by Western blotting. Spatial memory was examined by the Morris water maze (MWM) and the field excitatory postsynaptic potential (fEPSP) in the hippocampal CA1 area was recorded in vivo. Acute stress transiently decreased the expression of KCNQ2 and KCNQ3 in the hippocampus. Acute stress impaired the spatial memory retrieval and hippocampal LTP, the KCNQ/Kv7 channel activator flupirtine prevented the impairments, and the protective effects of flupirtine were blocked by XE-991 (10,10-bis(4-Pyridinylmethyl)-9(10H)-anthracenone), a selective KCNQ channel blocker. Furthermore, acute stress decreased the phosphorylation of glycogen synthase kinase-3β (GSK-3β) at Ser9 in the hippocampus, and flupirtine inhibited the reduction. These results suggest that the KCNQ/Kv7 channels may be a potential target for protecting both hippocampal synaptic plasticity and spatial memory retrieval from acute stress influences.

Electric-field-induced Skyrmion distortion and giant lattice rotation in the magnetoelectric insulator Cu2OSeO3

Uniquely in Cu2OSeO3, the Skyrmions, which are topologically protected magnetic spin vortexlike objects, display a magnetoelectric coupling and can be manipulated by externally applied electric (E) fields. Here, we explore the E-field coupling to the magnetoelectric Skyrmion lattice phase, and study the response using neutron scattering. Giant E-field induced rotations of the Skyrmion lattice are achieved that span a range of ∼25°. Supporting calculations show that an E-field-induced Skyrmion distortion lies behind the lattice rotation. Overall, we present a new approach to Skyrmion control that makes no use of spin-transfer torques due to currents of either electrons or magnons.

Expression analysis of differentially expressed miRNAs in male and female chicken embryos

MicroRNAs (miRNAs) are small non-coding RNA molecules that play key roles in the regulation of development processes of many tissues and organs at the post-transcriptional level. However, little is known about how they affect chicken gonadal development. We examined the expression of four miRNAs (miR-218, -200b, -196, and -206) in chicken embryonic gonads at embryonic days 3.5-6.5. Their target genes were predicted by miRDB, TargetScan and PicTar algorithms. The expression levels of these four miRNAs differed with sex to varying degrees; miR-200b was expressed at a significantly higher level in female gonads during the entire interval. The whole mount in situ hybridization result showed considerably higher expression of miR-200b in females than in males in E5.5 embryos. The miRNA target scanning results indicated several genes with functions in gonad development and gonad function. We conclude that miR-200b is involved in the regulation of gonad development and sexual differentiation of chicken embryos.

Dynamic patterns of histone H3 lysine 4 methyltransferases and demethylases during mouse preimplantation development

Extensive and dynamic chromatin remodeling occurs after fertilization, including DNA methylation and histone modifications. These changes underlie the transition from gametic to embryonic chromatin and are thought to facilitate early embryonic development. Histone H3 lysine 4 methylation (H3K4me) is an important epigenetic mechanism that associates with gene-specific activation and functions in development. However, dynamic regulation of H3K4me during early embryonic development remains unclear. Herein, the authors examined the dynamic changes of H3K4me and its key regulators (Ash1l, Ash2l, Kmt2a, Kmt2b, Kmt2c, Setd1a, Setd7, Kdm1a, Kdm1b, Kdm5a, Kdm5b, Kdm5c, and Kdm5d) in mouse oocytes and preimplantation embryos. An increase in levels of H3K4me2 and me3 was observed at the one- to two-cell stages (P < 0.05), corresponding to the period of embryonic genome activation (EGA). Subsequently, the H3K4me2 level dramatically decreased at the four-cell stage and remained at low level until the blastocyst stage (P < 0.05), whereas the H3K4me3 level transiently decreased in the four-cell embryos but steadily increased to the peak in the blastocysts (P < 0.05). The high level of H3K4me2 during the EGA was coinciding with a peak expression of its methyltransferase, ASH2L, which may stabilize this methylation level during this period. Correspondingly, a concomitant decrease in levels of its demethylases, KDM5B and KDM1A, was observed. H3K4me3 was correlated to the expression of its methyltransferase (KMT2B) and demethylase (KDM5A). Thus, these enzymes may function for the EGA and the first lineage segregation in preimplantation mouse embryos.

Poly(3-hexylthiophene) nanostructured materials for organic electronics applications

Semiconducting polymers have been developed during the last few decades and are currently used in various organic electronics applications. Regioregular poly(3-hexylthiophene) (P3HT) is the most employed semiconducting polymer for organic electronics applications. The development of living Grignard metathesis polymerization (GRIM) allowed the synthesis of P3HT with well-defined molecular weights and functional end groups. A large number of block copolymers containing P3HT have been reported, and their opto-electronic properties have been investigated. The performance of P3HT homopolymer and block copolymers in field-effect transistors and bulk heterojunction solar cells are discussed in this review. The morphology of the P3HT materials is also discussed.