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The chemical engineering of natural extracts has emerged as an effective strategy for the production of diverse libraries of chemicals, making it integral to drug discovery. A chemical engineering strategy based on the epoxidation and ring-opening reactions was used to prepare diversity-enhanced extracts of Chaetomium madrasense 375. Eleven unnatural cytochalasan derivatives (1-11) with unique functional groups, such as amine and isoxazole, were isolated and characterized from these chemically engineered extracts of C. madrasense 375. The identification of these new structures was accomplished through comprehensive spectroscopic analysis, supplemented by synthetic considerations. Notably, compounds 5 and 13-16 displayed potent phytotoxic effects on Arabidopsis thaliana, while compounds 1, 2, 5, 10, and 12 demonstrated inhibitory activities on LPS-induced NO production in RAW264.7 cells. Among them, compound 1 was found to be able to inhibit the upregulated expression of the inducible nitric oxide synthase (iNOS) protein induced by LPS, while also decreasing the production of pro-inflammatory cytokines (IL-6) and influencing the phosphorylation of p38, ERK1/2, and JNK at 100 μM. Our findings demonstrate that the chemical engineering of natural product extracts can be an efficient technique for the generation of novel bioactive molecules. [ABSTRACT FROM AUTHOR]

The ethyl acetate extract of Amygdalus persica L. flowers (family Rosaceae) was fractionated by silica gel and Sephadex LH-20 column chromatography, and, after recrystallization, oleanolic acid (1), ursolic acid (2), quercetin (3), kaempferol (4), hesperetin (5), naringenin (6), and kaempferol-3-O-glucoside (7) were isolated. Their identities were elucidated by spectral techniques and from their physicochemical properties. Compounds 3-7 were identified from A. persica flowers for the first time. All the compounds were evaluated for their procoagulant activity by determining their activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), and fibrinogen (FIB) in vitro. The coagulation activity results showed that oleanolic acid and ursolic acid could significantly prolong APTT and TT; quercetin could significantly shorten PT and TT; kaempferol and hesperetin could significantly shorten APTT, PT, and TT; and naringenin could significantly shorten APTT, PT, and TT and decrease the content of FIB compared with the blank group. All of the above revealed that quercetin, kaempferol, hesperetin and naringenin possessed significant procoagulant activity, while ursolic acid had anticoagulant activity in vitro. [ABSTRACT FROM AUTHOR]

Background: Neonatal hepatitis B vaccination program at birth has been implemented nationwide since 1992 in China. However, current HBV prevalence status in blood donors has not been entirely examined, which may impact HBV safety in blood donations as the vaccinees over 18 years old progressively become the majority population of blood donors.Methods: In this study, 569,145 blood donors were screened for HBsAg by rapid tests and enzyme immunoassays, among them 475,538 blood samples with negative HBsAg were further screened for HBV DNA by nucleic acid testing between 2005 and 2014 at Shenzhen blood center.Results: An overall 2.3 % HBsAg prevalence was found in the blood donor population during the past 10 years (2.86 % in 2005, 1.76 % in 2010, and 2.79 % in 2014, respectively). HBsAg seroconversion occurred in 0.37 % of repeat-donors. When stratified by age, the prevalence of HBsAg was found significantly higher in younger donors age 18-25 years (2.73 %) than in those 26-35 years (2.13 %), 36-45 years (2.03 %) and 46-58 years (1.71 %) (P < 0.001), unexpectedly suggesting that younger donors remained at risk of chronic HBV infection. Assuming that donors aged 18-22 born before or after 1992 were non-vaccinated and vaccinated, respectively, HBsAg prevalence was higher in first-time donors born ≥1992 (3.9 %) than prior to 1992 (3.5 %, P = 0.005). The incidence of HBV infection in the 5-year period examined was significantly lower in repeat-donors born ≥1992 (0.27 %) than prior to 1992 (0.6 %, P = 0.008). The yield of HBV DNA+/HBsAg- donors was 1:3,302, including 1:4,486 occult infections and 1:43,231 window period infections.Conclusion: Young blood donors born after implementation of universal HBV vaccination in China presented higher prevalence of HBsAg but lower incidence of HBsAg seroconversion than older, presumed unvaccinated, donors. HBV vaccine boosting for adolescents at 15-17 years old prior to reaching blood donor age might help improve blood safety. [ABSTRACT FROM AUTHOR]

Understanding the effect of defects on mechanical responses and failure behaviors of a graphene membrane is important for its applications. As examples, in this paper, a family of graphene with various 5-8-5 defects are designed and their mechanical responses are investigated by employing molecular dynamics simulations. The dependence of fracture strength and strain as well as Young's moduli on the nearest neighbor distance and defect types is examined. By introducing the 5-8-5 defects into graphene, the fracture strength and strain become smaller. However, the Young's moduli of DL (Linear arrangement of repeat unit 5-8-5 defect along zigzag-direction of graphene), DS (a Slope angle between repeat unit 5-8-5 defect and zigzag direction of graphene) and DZ (Zigzag-like 5-8-5 defects) defects in the zigzag direction become larger than those in the pristine graphene in the same direction. A maximum increase of 11.8% of Young's modulus is obtained. Furthermore, the brittle cracking mechanism is proposed for the graphene with 5-8-5 defects. The present work may provide insights in controlling the mechanical properties by preparing defects in the graphene, and give a full picture for the applications of graphene with defects in flexible electronics and nanodevices. [ABSTRACT FROM AUTHOR]

Insulin resistance is common in critically ill patients and seriously affects their prognosis. The anesthetic propofol (2,6-diisopropylphenol) has been shown to cause insulin resistance in rats; however, the specific mechanism underlying this phenomenon remains unknown. Thus, the aim of the present study was to determine the molecular mechanism through which propofol influences insulin resistance in the liver. The current study assessed the effects of propofol on the phosphorylation level of key enzymes involved in the insulin signaling pathway, as well as the glycogen content in primary mouse hepatocytes. Propofol administration was demonstrated to considerably reduce the phosphorylation levels of Akt (Ser473) and glycogen synthase kinase (GSK)-3β (Ser9) in the primary mouse hepatocytes. In addition, propofol was shown to downregulate the phosphoinositide 3-kinase (PI3K)/Akt/GSK-3β signaling pathway and inhibit glycogen synthesis in hepatocytes. Thus, the present results indicated that propofol induced insulin resistance in primary mouse hepatocytes. Notably, pretreatment with propofol in tumor necrosis factor (TNF)-α-induced primary mouse hepatocytes with insulin resistance was demonstrated to alleviate the inhibitory effects of TNF-α on the PI3K/Akt/GSK-3β signaling pathway and glycogen synthesis. These results indicated that propofol exerts a protective effect against insulin resistance in primary mouse hepatocytes induced by TNF-α, indicating that propofol therapy may be clinically feasible to alleviate insulin resistance in critically ill patients. [ABSTRACT FROM AUTHOR]

The neutral and anionic ConCN (n = 1-5) clusters were investigated using density functional calculations. The most stable structures of neutral and anionic ConCN (n = 1-5) clusters have been identified. In these structures, the CN radical retains its integrity as a structural unit. For anionic ConCN- (n = 1-5) and neutral ConCN (n = 1-2) clusters, the CN prefers to be adsorbed on the top sites of Con clusters via the C terminal, forming a linear or quasi-linear N-C-Co structure. For neutral ConCN (n = 3-5) clusters, the CN is adsorbed on the bridge sites of Con (n = 3-5) by both C and N atoms. Compared to the free CN radical calculated at the same level, the C-N stretching frequencies of neutral ConCN (n = 3-5) are red-shifted while they are blue-shifted for neutral ConCN (n = 1-2). The adiabatic and vertical detachment energies of anionic ConCN- (n = 1-5) clusters are calculated based on density functional calculations. In addition, the most favored dissociation channels of neutral and anionic ConCN (n = 1-5) clusters are determined by calculating the dissociation energies of various possible dissociation pathways. [ABSTRACT FROM AUTHOR]

A new electrochemical voltammetric sensor, Langmuir-Blodgett (LB) film of 25,27-dimethoxy-26-( N-trichloroacetyl)carbamoyloxy- p-tert-butylcalix[4]arene (DCA) modified GCE (LB-GCE), was designed and successfully used for recognition and determination of trace amounts of Ag in water. Under the optimum experimental conditions, the lowest detectable concentration of Ag reached 1 × 10 mol L. Moreover, LB-GCE exhibited a well-defined response relating to the Ag with good sensitivity, selectivity, reproducibility, and long stability. The recognizing mechanism of LB-GCE for silver ion in aqueous solution was also discussed. The results show that the size of calixarene cavity may be the predominate factor affecting recognition of calixarene for silver ions. A new electrochemical voltammetric sensor, based on a DCA LB film modified electrode, was fabricated and used for Ag determination. The result indicated that such materials with corresponding size of cavity may have an interaction effect with metal ions and could be used for the determination of metal ions. [ABSTRACT FROM AUTHOR]

Developing advanced electrochemical electrode materials with excellent performance is critical to their future energy storage devices. Herein, we design and synthesize two-dimensional (2D) porous structure nickel oxide (NiO) nanosheets via a facile and scalable hydrothermal approach, and further heating. The effects of heating time on the electrochemical performances are investigated. The results indicate that the maximum specific capacitance is achieved for NiO nanosheets when heating temperature and time are 300 °C and 3 h, respectively (namely NiO-3). The as-prepared NiO-3 nanosheet are grown uniform on the skeleton of reduced graphene oxide (rGO). The optimum NiO/rGO displays a reversible discharge capacity of 781.7 F g−1 at 1 A g−1, and shows an ultra-long life-span with over 94% capacitance retention after 4000 cycles. The enhanced electrochemical properties for NiO/rGO can be ascribed to a collaborative effect between NiO and rGO, which possess high capacitance storage ability and excellent conductivity, respectively. [ABSTRACT FROM AUTHOR]

We have demonstrated a novel three-dimensional (3D) architecture of a graphene/carbon nanotube (G-CNT) hybrid synthesized at large scale within just 5 s via a simple microwave-heating method without the usage of any other conducting or expanding agent for the first time. The carbon composites obtained consist of evenly grown CNTs with an average diameter of about 15 nm on the surface of graphene nanosheets. The G-CNT hybrid exhibits enhanced electrochemical performance for both aqueous and organic supercapacitor devices. Particularly, the G-CNT electrodes demonstrate an enhanced specific capacitance of 361 F g−1 at a current density of 1.1 A g−1 in an aqueous electrolyte and a volumetric capacitance of 254 F cm−3 in an organic electrolyte. They also display excellent cycle stability with nearly 91.2% of the initial capacitance retained after 10 000 charging-discharging cycles at a current density of 15 A g−1. This demonstrates that the developed composites have potential applications in supercapacitors and other energy storage devices. [ABSTRACT FROM AUTHOR]

Freestanding polyaniline (PANI) nanorods grown in situ on microwave-expanded graphene oxide (MEGO) sheets were prepared through a facile solution method. The morphological characterization indicates that large quantity of free-standing PANI nanorods with average diameter of 50 nm were uniformly deposited onto the double sides of the MEGO nanosheets to form a sandwich structure. The hybrid of PANI/MEGO (GPANI) exhibit high specific surface area and high electrical conductivity, compared with pristine PANI nanorods. When evaluated as electrodes for supercapacitors, the GPANI demonstrate high specific capacitance of 628 F g−1 at a current density of 1.1 A g−1, high-rate performance, and excellent cycle stability compared to individual component. Such excellent electrochemical performance should be attributed to the combined double-layer capacitance and pseudo -capacitance mechanisms from the MEGO sheets and PANI nanorods. [ABSTRACT FROM AUTHOR]