Search

Na-ion intercalation significantly modifies the thermal conductivity of carbon honeycomb and preserves its high anisotropy.

This work aims to research the influence of boron and quenching temperature on the microstructures and performances of boron-bearing high-speed alloy steel. The results showed that the hardness and wear resistance of boron-bearing high-speed alloy steel were improved after increasing the boron content. The volume fraction of boron-rich carbide gradually decreased, and the hardness increased significantly with the rise in quenching temperature. The highest comprehensive mechanical properties were obtained for samples quenched at 1040 °C. The TEM results showed the boron-rich carbide was M7(C, B)3 with an HCP structure, and the precipitated particles were M23(C, B)6 with an FCC structure after tempering. This work may help improve the wear resistance of materials in the field of surface coatings.

Postpartum depression is a kind of mental disorder caused by the comprehensive effects of economics, psychosociology, biology, obstetrics and other characteristic factors in the process of female pregnancy. The pathogenesis of postpartum depression is complicated and has not been clarified. With the process pregnancy, the influence of psychosocial and biology factors are also in dynamic change. The postpartum depression predictor among psychosocial factors are antenatal depression, life events and social supports. Among biological factors, the predictors are hypothalamic-pituitary-thyroid axis and serum lipids. Timely and effective prediction can identify the high-risk population and risk factors for postpartum depression.产后抑郁是女性孕育过程中由人口经济学、心理社会学、生物学、产科及其他因素等综合作用所致的一种精神障碍性疾病。产后抑郁发病机制较复杂且尚未明确。随着妊娠的进展，心理社会学和生物学因素处于不断变化的过程，其对产后抑郁的影响也随之动态变化。在心理社会学因素中，对产后抑郁具有预测作用的为产前抑郁、负性生活事件、人格特征、社会支持；在生物学因素中，对产后抑郁有影响的因素为下丘脑-垂体-甲状腺轴、血清脂质。及时、有效的预测能及早发现产后抑郁高危人群和高危因素。.

Virus 3D atomic structures provide insight into our understanding of viral life cycles and the development of antiviral drugs. X-ray crystallography and cryo-EM have been used to determine the atomic structure of viruses. However, limited availability of biological samples, biosafety issues due to virus infection, and sometimes inherent characteristics of viruses, pose difficulties on combining both methods in determining viral structures. These have made solving the high resolution structure of some medically important viruses very challenging. Here, we describe our recently employed protocols for determining the high-resolution structure of the virus-like particle of hepatitis E virus (HEV), a pathogen of viral hepatitis in human. These protocols include utilizing recombinant baculovirus system to generate sufficient amount of virus particles, single-particle cryo-EM to get an intermediate resolution structure as a phasing model, and X-ray crystallography for final atomic structure determination. Our protocols have solved the hepatitis E virus structure to the resolution of 3.5 Å. The combined methodology is generally applicable to other human infectious viruses.

Spherical virions can be structurally divided into two compositions: the outer protein shell, and its content including the viral genome and enzymes. Three-dimensional virus structures are the key to understanding the virus life cycles and their mechanisms for infecting hosts, which can contribute to anti-viral drug design. These structures can be solved either by X-ray crystallization (Harrison et al. 1978) or by cryo-electron microscopy (cryo-EM) (Dubochet et al. 1988), or by combining both methods (Guu et al. 2009). In retrospect, the X-ray method had begun to solve viral structures at high resolution with atomic information since the late 1970s (Harrison et al. 1978; Abad-Zapatero et al. 1980), while cryo-EM, considered as a blobology method, only provided low- or medium-resolution information from the 1980s (Dubochet et al. 1988). In recent years, cryo-EM has emerged to rival with X-ray on the high-resolution structure determination of spherical viruses (Grant and Grigorieff 2015; Liu et al. 2016). In spite of a wealth of virus structures determined by these methods, the solved parts were limited to the viral capsid, while the remaining moieties, like the viral genomes and virus-self-functional enzymes within, were rarely visualized. Strikingly, in a recent paper published in Science (Liu and Cheng 2015), Drs. Liu and Cheng managed to discern the full genome and polymerase of cytoplasmic polyhedrosis virus (CPV), using their new approach adapted from traditional single-particle analysis of icosahedral viruses.

GH4169 is a nickel-based superalloy that has been widely used in aerospace, nuclear energy, petroleum industry and extrusion molds due to its excellent strength, weldability and long-term stability. To improve its self-cleaning and anti-icing properties in consideration of its broad applications in aerospace and aviation, we developed an electrochemical method using neutral electrolyte, followed by low surface energy treatment to fabricate superhydrophobic GH4169 surfaces. The superhydrophobic surfaces prepared in sodium nitrate and sodium chloride solutions had contact angles of 159.6° and 160.7°, and sliding angles of 7.65° and 7.8°, respectively. Their surface wettability is highly dependent on current density and process time in electrochemical etching whereas the concentration and temperature of the electrolyte are not so important. The prepared superhydrophobic GH4169 surfaces demonstrate anti-adhesion, self-cleaning and anti-icing properties.

Hepatitis B virus (HBV) contains 3 types of particles, i.e., 22-nm-diameter spherical and tubular subviral particles (SVPs) and 44-nm-diameter Dane particles. The SVPs are non-infectious and present strong immunogenicity, while Dane particles are infectious. In this study, we isolated spherical SVPs from HBV carriers’ sera and determined their 3D structure at the resolution of ∼30 A by cryo-electron microscopy (cryo-EM) single-particle reconstruction. Our cryo-EM structure suggests that the native HBV spherical SVP is irregularly organized, where spike-like features are arranged in a crystalline-like pattern on the surface. Strikingly, the hepatitis B surface antigen (HBsAg) in the native spherical SVPs folds as protrusions on the surface, as those on the native tubular SVPs and Dane particles, but is largely different from that in the recombinant octahedral SVPs. These results suggest a universal folding shape of HBsAg on the native HBV viral and subviral particles.

Using an isothermal evaporation method, the metastable phase equilibrium of the quaternary system Li+, Na+//Cl–, B4O72––H2O was investigated at 273 K. The useful data for solubilities, densities, and pH values were measured, based on which the metastable phase diagram, water content diagram, density vs composition diagram, and pH value vs composition diagram of this system were constructed. The metastable phase diagram of this quaternary system contains two invariant points, five univariant curves, and four crystallization fields. This quaternary system is of a simple cosaturation type, without double salt or solid solution formed. The four crystallization fields are corresponding to salts NaCl, LiCl·H2O, LiBO2·8H2O, and Na2B4O7·10H2O, respectively. The sequence of the crystallization field sizes of slats is salt Na2B4O7·10H2O > salt LiBO2·8H2O > salt NaCl > salt LiCl·H2O, which demonstrates that the borates, including salt Na2B4O7·10H2O and salt LiBO2·8H2O, can be more easily separated from the solution ...

Proteomic changes induced by Cd have been described in plants in different scenarios. However, there has been no proteomic study on Cd toxicity, including any low Cd-accumulating species. Here, we investigate the response of a low Cd-accumulating species, Solanum torvum, to Cd toxicity at the root proteomic level using two-dimensional gel electrophoresis (2-DGE). The root 2-DGE map consisted of at least 927 reproducible protein spots, of which 45 were classified as differentially expressed proteins based on three replicated separations. MALDI-TOF MS analysis identified 19 of these spots, and MALDI-TOF/TOF MS analysis identified 8 of the spots. The eight proteins identified were two S-adenosylmethionine (SAM) synthetases, actin, an ATP synthase subunit, two tubulin proteins, alcohol dehydrogenase (ADH), and 14-3-3 protein 4. These proteins are involved in phytohormone synthesis, defense responses, energy metabolism, and cytoskeleton construction. Thus, our proteomic analysis revealed that Cd stress promotes an increase in the abundance of proteins involved in antioxidant defenses and anti-stress protection.

The three-dimensional structure of recombinant hepatitis B core antigen (HBcAg) particles truncated at residue 154 (HBcAg-154) was determined to 7.8 Å resolution by cryo-electron microscopy (cryoEM) and computer reconstruction. The capsid of HBcAg-154 is mainly constituted by α-helical folds, highly similar to that of HBcAg-149. The C-terminal region between residues 155 and 183 of the core protein is more crucial to the encapsidation of RNA, and the short C-terminal tail of HBcAg-154 results in a nearly empty capsid.

Microcrystalline cellulose (MCC) was pretreated with phosphoric acid at 323K for 10h. X-ray diffraction (XRD) and Atomic Force Microscope (AFM) analyses revealed that the fiber surface morphology of pretreated MCC (P-MCC) were uneven and rough with the crystalline diffraction peaks of P-MCC decreased to a distinct range. The X-ray Photoelectron Spectroscopy (XPS) analysis showed that the uneven and rough surface of P-MCC could enhance the adsorption of cellulose to the molecular surface of cellulose, which is one of the key factors affecting enzymatic hydrolysis of cellulose. A reversible first order kinetics was employed to describe the adsorption kinetics of cellulase to MCC and P-MCC, and the adsorption rate constants of MCC and P-MCC were found to be 0.016, 0.024, 0.041, and 0.095, 0.149, 0.218min(-1), respectively at 278K, 293K and 308K. The activation energies of MCC and P-MCC hydrolysis reactions were found to be 22.257 and 19.721kJ mol(-1). The major hydrolysis products of MCC and P-MCC were cellobiose and glucose. Hydrolysis of MCC for 120h resulted in yields of glucose (7.21%), cellobiose (13.16%) and total sugars (20.37%). However, after the pretreatment with phosphoric acid, the corresponding sugar yields resulted from enzymatic hydrolysis of P-MCC were increased to 24.10%, 41.42%, and 65.52%; respectively, which were 3.34, 3.15, and 3.22 times of the sugars yields from enzymatic hydrolysis of MCC.

Core protein of hepatitis B virus (HBV) with various C-terminal lengths (residue 154, 164, 167 and 183) can self-assemble into recombinant hepatitis B core antigen (HBcAg) particles. To understand the RNA encapsidation mechanism of HBV, the three-dimensional structures of these particles were reconstructed by cryo-electron microscopy (cryoEM). Detailed structural comparisons showed that their capsid structures are highly similar, while the RNA content is increased upon the retention of more amino acid residues at the C-terminus of core protein, suggesting the crucial role of the basic C-terminal tail on determining the genome size.

In this study, we aimed to dissolve microcrystalline cellulose (MCC) with phosphoric acid to obtain high-quality fermentable saccharides. MCC was directly dissolved in phosphoric acid (the concentration was 83%) for 10 hours at temperatures of 30, 50, and 70 degrees C. The structural changes of MCC were determined in detail with X-ray powder diffraction, solid-state cross-polarization magic angle spinning (13)C-NMR, and X-ray photoelectron spectroscopy. The kinetics of MCC decrystallization during treatment with phosphoric acid was also compared at 30, 50, and 70 degrees C. With the assumption of first order kinetics, the Arrhenius parameters of K, A(0) and E(a) were calculated. The rate constants of decrystallization reaction (K) were 0.06, 0.17, and 0.12 h(-1) respectively. The pre-exponential factor (A(0)) was 1.2 x 10(6) h(-1), and the activation energy (E(a)) was 42.4 kJ/mol.

Hepatitis E virus (HEV), a small, non-enveloped RNA virus in the family Hepeviridae , is associated with endemic and epidemic acute viral hepatitis in developing countries. Our 3.5-Å structure of a HEV-like particle (VLP) shows that each capsid protein contains 3 linear domains that form distinct structural elements: S, the continuous capsid; P1, 3-fold protrusions; and P2, 2-fold spikes. The S domain adopts a jelly-roll fold commonly observed in small RNA viruses. The P1 and P2 domains both adopt β-barrel folds. Each domain possesses a potential polysaccharide-binding site that may function in cell-receptor binding. Sugar binding to P1 at the capsid protein interface may lead to capsid disassembly and cell entry. Structural modeling indicates that native T = 3 capsid contains flat dimers, with less curvature than those of T = 1 VLP. Our findings significantly advance the understanding of HEV molecular biology and have application to the development of vaccines and antiviral medications.

Parvoviridae is a family of the smallest viruses known with a wide variety of hosts. The capsid structure of the Aedes albopictus C6/36 cell densovirus (C6/36 DNV) at 1.2-nm resolution was obtained by electron cryomicroscopy (cryoEM) and three-dimensional (3D) image reconstruction. Structure comparisons between the C6/36 DNV and other parvoviruses reveal that the degree of structural similarity between C6/36 DNV and the human parvovirus B19 is higher than that between C6/36 DNV and other insect parvoviruses. The amino acid sequence comparisons of structural and non-structural proteins also reveal higher levels of similarity between C6/36 DNV and parvovirus B19 than those between C6/36 DNV and other parvoviruses. These findings indicate that C6/36 DNV is closely related to the human virus B19, and the former might evolve from the human species other than from other insect viruses.

A nanostructural polyaniline-poly(propylene oxide) (PANI-PPO) composite coating was electrochemically synthesized on a stainless steel wire, by using acidic ionic liquid 1-sulfobutyl-3-methylimidazolium hydrosulfate as supporting electrolyte. The coating showed strong hydrophobicity and allowed for the direct immersion solid-phase microextraction of carbamate pesticides (i.e. 2-(1-methylethoxy) phenyl methylcarbamate, m-tolyl-n-methylcarbamate, 2-(1-methylethyl) phenyl methylcarbamate, 2-(1-methylpropyl) phenol methylcarbamate and 2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) in complex matrices. Moreover, this coating could be used for at least 120 times of extraction. When it was coupled with gas chromatography for the determination of these carbamate pesticides the linear ranges were about 0.1–100 μg L−1 and the detection limits were 0.012–0.048 μg L−1. It also displayed acceptable repeatability and reproducibility. When a fiber was used for five successive measurements the relative standard deviations (RSDs) were smaller than 8.7%, and the RSDs for fiber-to-fiber were 5.7–12.9% (n = 5). The practical feasibility of the proposed method was evaluated by determining carbamate pesticides in vegetable samples and the recoveries for standards added were 79.8–108.8%.

When Aedes albopictus larvae were infected with C6/36 densovirus (C6/36DNV), the mortality reached 97.46% within 21 days for those larvae infected at the first day after hatching, and 14.17% for control. A real-time quantitative polymerase chain reaction (qPCR) was used to trace the dynamic change of the quantity of C6/36DNV genomes in the larvae and the adults, and to study the interaction of C6/36DNV with dengue virus type II(DEN-II) in mosquitoes. It showed that C6/36DNV could persist in the adults that could transmit C6/36DNV vertically to the next generation. The quantity of C6/36DNV after DEN-II infection increased by 10(2)~10(3) times in the C6/36DNV-positive mosquitoes, and the quantity of DEN-II in the C6/36DNV-positive mosquitoes was about 100 times lower than that in the C6/36DNV-negative mosquitoes, which suggested that DEN-II could remarkably stimulate the reproduction of C6/36DNV, while C6/36DNV persisted in mosquitoes could inhibit the reproduction of DEN-II. The study throws light on C6/36DNV as a possible biologic control agent against dengue virus and Ae. albopictus.

The causative agent of severe acute respiratory syndrome (SARS) is the SARS-associated coronavirus, SARS-CoV. The nucleocapsid (N) protein plays an essential role in SARS-CoV genome packaging and virion assembly. We have previously shown that SARS-CoV N protein forms a dimer in solution through its C-terminal domain. In this study, the crystal structure of the dimerization domain, consisting of residues 270–370, is determined to 1.75Å resolution. The structure shows a dimer with extensive interactions between the two subunits, suggesting that the dimeric form of the N protein is the functional unit in vivo. Although lacking significant sequence similarity, the dimerization domain of SARS-CoV N protein has a fold similar to that of the nucleocapsid protein of the porcine reproductive and respiratory syndrome virus. This finding provides structural evidence of the evolutionary link between Coronaviridae and Arteriviridae, suggesting that the N proteins of both viruses have a common origin.

The causative agent of severe acute respiratory syndrome (SARS) is the SARS-associated coronavirus, SARS-CoV. The viral nucleocapsid (N) protein plays an essential role in viral RNA packaging. In this study, recombinant SARS-CoV N protein was shown to be dimeric by analytical ultracentrifugation, size exclusion chromatography coupled with light scattering, and chemical cross-linking. Dimeric N proteins self-associate into tetramers and higher molecular weight oligomers at high concentrations. The dimerization domain of N was mapped through studies of the oligomeric states of several truncated mutants. Although mutants consisting of residues 1-210 and 1-284 fold as monomers, constructs consisting of residues 211-422 and 285-422 efficiently form dimers. When in excess, the truncated construct 285-422 inhibits the homodimerization of full-length N protein by forming a heterodimer with the full-length N protein. These results suggest that the N protein oligomerization involves the C-terminal residues 285-422, and this region is a good target for mutagenic studies to disrupt N protein self-association and virion assembly.

The three-dimensional structure of capsid of Aedes albopictus C6/36 densovirus was determined to 14-A resolution by electron cryomicroscopy and computer reconstruction. The triangulation number of the capsid is 1. There are 12 holes in each triangular face and a spike on each 5-fold vertex. The validity of the capsid and nucleic acid densities in the reconstructions was discussed.

In vivo entry of Bombyx mori cypovirus 1 into the silkworm midgut was studied by electron microscopy of ultrathin sections of midguts from silkworm larvae that had been administered virus-contaminated leaves. In 3 h, virions were observed outside and inside midgut cells, including columnar cells, goblet cells and muscle cells. Virions were seen adhering to the plasma membrane of microvilli, embedding in the membrane and settling themselves intact inside the microvilli of the columnar cells. These results suggested that intact virions entered columnar cells by means of direct penetration through the cell membrane. In 12, 24 and 48 h, virogenic stromata and progeny virions were observed in columnar cells, but not in other midgut cells.

Viruses in the family Reoviridae are capable of transcription within the intact capsids. As the only single-shelled and thus the simplest member of the Reoviridae, cytoplasmic polyhedrosis virus (CPV) provides an attractive system for studying endogenous transcription. We report the structures of the full and empty CPV determined at 13-A resolution by electron cryomicroscopy. The structure of the empty CPV reveals a density attributed to the transcription enzyme complex, which is attached to the internal surface of the capsid shell below each of the 12 turrets. The full capsid has an identical capsid shell but contains additional internal densities contributed by the genomic double-stranded (ds) RNA. The RNA densities proximal to the capsid shell are organized into layers with a dodecahedral appearance, suggesting a genome organization of dsRNA segments each having a cone shape spooling around a transcription enzyme complex. Our structures also suggest that the capsid shell serves as a scaffold for appropriate positioning of the RNA genome, whereas nascent mRNA release takes place through the constricted central channel of the turret. Based on these observations, a detailed moving template transcription mechanism is proposed that may provide insight into the well coordinated and highly efficient endogenous RNA transcription of dsRNA viruses.

To examine the psychometric features of the body image after breast cancer questionnaire-Chinese version (BIBCQ-C) in Chinese women with breast cancer.A total of 545 women with breast cancer received a demographics investigation: BIBCQ-C and hospital anxiety and depression scale (HAD). Four weeks later, 31 patients were selected randomly to finish BIBCQ-C again.The Cronbach's alpha coefficient for the total scale was 0.90, and that for the 6 factors ranged from 0.62 to 0.87. The mean inter-item correlation coefficient of the total scale was 0.16, and the mean inter-item correlation coefficient of the subscales ranged from 0.21 to 0.57, and the test-retest reliability of the total scale and 6 factors was over 0.60. The confirmatory factor analyses supported the 6-factor model, and BIBCQ-C were significantly correlated with the symptom scales of anxiety and depression (r=0.20, 0.21, P0.01).BIBCQ-C is reliable and valid, which can effectively assess body image of Chinese women with breast cancer.

This paper presents a new method of collaborative technical service orient product lifecycle to improve quality and efficiency in technical service. Firstly, the collaborative technical service orient product lifecycle is defined and characteristics of collaborative technical service are analyzed. Then, based on analyses structure of technical service data-base the collaborative technical service system architecture is founded. Finally, on the base of theoretical research, a prototype system of collaborative technical service orient product lifecycle is developed.

The brevidensovirus is one of the smallest viruses in the world and the capsid of Aedes albopictus C6/36 cell densovirus (C6/36DNV) is the simplest and most compact capsid in brevidensovirus. To understand the assembly mechanism of icosahedral-virus capsid from this simplest model, we tried to express various lengths of virus proteins (VPs) of C6/36DNV in Bac-to-Bac system and evaluate their self-assembly capacities in insect Spodoptera frugiperda 9 (Sf9) cells. The result showed that the N-terminal GGSG sequence (residue 23-26), highly conserved glycine-rich region in Parvoviridae, and C-terminal GTGGVVTCMP (residue 344-353) were essential for capsid assembly, while the N-terminal nuclear localization signal, GTKRKR sequence (residue 15-20), was nonessential for the virus-like particles (VLPs) assembly, but did effect the formation of crystalline arrays in infected Sf9 cells. These information provided clues for how icosahedral-virus capsids formed and showed the potential of C6/36DNV-VLPs becoming a powerful nanoparticle vector.

Background. Previous studies have shown that common human coronavirus might be neurotropic, although it was first isolated as a pathogen of the respiratory tract. We noticed that a few patients with severe acute respiratory syndrome (SARS) experienced central nervous symptoms during the course of illness. In the present study, we isolated a SARS coronavirus strain from a brain tissue specimen obtained from a patient with SARS with significant central nervous symptoms. Methods. Using transmission electronic microscopy and nested reverse transcription–polymerase chain reaction, the causative pathogen was identified in cultures of a brain tissue specimen obtained from the patient with SARS. Histopathologic examination of the brain tissue was performed using the methods of immunohistochemistry analysis and double immunofluorescence staining. Fifteen cytokines and chemokines were detected in the blood of the patient with SARS by means of a bead-based multiassay system. Results. A fragment specific for SARS human coronavirus was amplified from cultures of the brain suspension, and transmission electronic microscopy revealed the presence of an enveloped virus morphologically compatible with a coronavirus isolated in the cultures. Pathologic examination of the brain tissue revealed necrosis of neuron cells and broad hyperplasia of gliocytes. Immunostaining demonstrated that monokine induced by interferon-Γ (Mig) was expressed in gliocytes with the infiltration of CD68+ monocytes/macrophages and CD3+ T lymphocytes in the brain mesenchyme. Cytokine/chemokine assay revealed that levels of interferon-Γ–inducible protein 10 and Mig in the blood were highly elevated, although the levels of other cytokines and chemokines were close to normal. Conclusions. This study provides direct evidence that SARS human coronavirus is capable of infecting the central nervous system, and that Mig might be involved in the brain immunopathology of SARS.

The RNA of Chinese Sacbrood Bee Virus (CSBV) was purified and used as template to obtain a 1096 bp cDNA fragment by RT-PCR amplification. This DNA fragment was cloned into pGEM-T Easy Vector for sequencing. Analyses of the sequenced CSBV RNA fragment revealed a nucleotide sequence homology of 87.6% and a deduced amino-acid sequence homology of 94.6% with that of the Sacbrood Virus (SBV), indicating that CSBV is a different but highly homologous virus of SBV. The three-dimensional (3D) structure of CSBV was determined at 2.5 nm resolution by using electron cryo-microscopy (cryoEM) and computer reconstruction methods. The 3-D structure showed that the capsid has aT = 1 (or P = 3) icosahedral capsid shell with a smooth surface. There were 12 pentons at its icosahedral vertices (5-fold axes) and 132 holes penetrating the shell. The 3-D structure also revealed densities corresponding to the CSBV genome, suggesting icosahedrally-ordered RNA organization, a novel feature not previously reported for any picornaviruses.

The structure determination of unstained biological molecules by electron microscopy would be straightforward but for two factors: One is their high sensitivity to electron damage and the other is the loss of three-dimensional order that generally takes place when the specimen's natural aqueous environment is replaced by the high vacuum of the electron microscope. In order to surmounting these difficulties, following methods would be used: (i) Phase contrast; (ii) For vacuum preservation the aqueous medium is replaced by glucose; (iii) Low dose (le/Å2.S) electron microscopy is used to prevent specimen from electron damage. However, a low dose image will not display the projected structure of a molecule or unit cell directly, because contrast and S/N are very low. Nenertheless, provided that the object is comprised of a large enough number of unit cells and that the periodicities are precisely maintained, all the information need to reconstruct the “average” molecule or unit cell will be available by computer. In order to recontrast the object, one needs to determine the Fourier amplitude and phase for each reflection. Fourier analysis of the micrograph data provide the phase and the measurement of the electron diffraction pattern provide the amplitudes. In this paper an experimental method of determining molecular structure of B. subtilis alpha-amylase crystal is discussed.