Sufficient oxygen for animal respiration 1,400 million years ago.

The Mesoproterozoic Eon [1,600-1,000 million years ago (Ma)] is emerging as a key interval in Earth history, with a unique geochemical history that might have influenced the course of biological evolution on Earth. Indeed, although this time interval is rather poorly understood, recent chromium isotope results suggest that atmospheric oxygen levels were <0.1% of present levels, sufficiently low to have inhibited the evolution of animal life. In contrast, using a different approach, we explore the distribution and enrichments of redox-sensitive trace metals in the 1,400 Ma sediments of Unit 3 of the Xiamaling Formation, North China Block. Patterns of trace metal enrichments reveal oxygenated bottom waters during deposition of the sediments, and biomarker results demonstrate the presence of green sulfur bacteria in the water column. Thus, we document an ancient oxygen minimum zone. We develop a simple, yet comprehensive, model of marine carbon-oxygen cycle dynamics to show that our geochemical results are consistent with atmospheric oxygen levels >4% of present-day levels. Therefore, in contrast to previous suggestions, we show that there was sufficient oxygen to fuel animal respiration long before the evolution of animals themselves.

Orbital forcing of climate 1.4 billion years ago.

Fluctuating climate is a hallmark of Earth. As one transcends deep into Earth time, however, both the evidence for and the causes of climate change become difficult to establish. We report geochemical and sedimentological evidence for repeated, short-term climate fluctuations from the exceptionally well-preserved ∼1.4-billion-year-old Xiamaling Formation of the North China Craton. We observe two patterns of climate fluctuations: On long time scales, over what amounts to tens of millions of years, sediments of the Xiamaling Formation record changes in geochemistry consistent with long-term changes in the location of the Xiamaling relative to the position of the Intertropical Convergence Zone. On shorter time scales, and within a precisely calibrated stratigraphic framework, cyclicity in sediment geochemical dynamics is consistent with orbital control. In particular, sediment geochemical fluctuations reflect what appear to be orbitally forced changes in wind patterns and ocean circulation as they influenced rates of organic carbon flux, trace metal accumulation, and the source of detrital particles to the sediment.

Efficacy, safety, and immunogenicity of an enterovirus 71 vaccine in China.

BACKGROUND: Enterovirus 71 (EV71) is one of the major causative agents of outbreaks of hand, foot, and mouth disease or herpangina worldwide. This phase 3 trial was designed to evaluate the efficacy, safety, and immunogenicity of an EV71 vaccine. METHODS: We conducted a randomized, double-blind, placebo-controlled, multicenter trial in which 10,007 healthy infants and young children (6 to 35 months of age) were randomly assigned in a 1:1 ratio to receive two intramuscular doses of either EV71 vaccine or placebo, 28 days apart. The surveillance period was 12 months. The primary end point was the occurrence of EV71-associated hand, foot, and mouth disease or herpangina. RESULTS: During the 12-month surveillance period, EV71-associated disease was identified in 0.3% of vaccine recipients (13 of 5041 children) and 2.1% of placebo recipients (106 of 5028 children) in the intention-to-treat cohort. The vaccine efficacy against EV71-associated hand, foot, and mouth disease or herpangina was 94.8% (95% confidence interval [CI], 87.2 to 97.9; P<0.001) in this cohort. Vaccine efficacies against EV71-associated hospitalization (0 cases vs. 24 cases) and hand, foot, and mouth disease with neurologic complications (0 cases vs. 8 cases) were both 100% (95% CI, 83.7 to 100 and 42.6 to 100, respectively). Serious adverse events occurred in 111 of 5044 children in the vaccine group (2.2%) and 131 of 5033 children in the placebo group (2.6%). In the immunogenicity subgroup (1291 children), an anti-EV71 immune response was elicited by the two-dose vaccine series in 98.8% of participants at day 56. An anti-EV71 neutralizing antibody titer of 1:16 was associated with protection against EV71-associated hand, foot, and mouth disease or herpangina. CONCLUSIONS: The EV71 vaccine provided protection against EV71-associated hand, foot, and mouth disease or herpangina in infants and young children. (Funded by Sinovac Biotech; ClinicalTrials.gov number, NCT01507857.).

Metal-Insulator Transition Induced by Spin Reorientation in Fe7Se8 Grain Boundaries.

Fe7Se8 exists as a hexagonal NiAs-like crystal structure with a large number of ordered intrinsic vacancies. It is an ideal candidate for studying the effect of defects on properties such as magnetism and electrical transport. In this work, highly crystalline Fe7Se8 with the 3c crystal structure was synthesized by a solid-state reaction. Sharp changes in the magnetization at 100 K confirm a rotation of the spins from the ab plane to the c axis with decreasing temperature. We observe an interesting metal-insulator transition at the same temperature as the spin-direction changes. We propose that locked spins in the grain boundaries induce electron localization and result in the metal-insulator transition. Electron localization is confirmed by X-ray photoelectron spectroscopy of the Fe 2p peaks, which exhibit two characteristic satellite peaks. This mechanism is also verified by comparing it with the properties of the 4c-Fe7Se8 crystal structure.

Molecular epidemiology of coxsackievirus A6 associated with outbreaks of hand, foot, and mouth disease in Tianjin, China, in 2013.

Since 2008, Mainland China has undergone widespread outbreaks of hand, foot, and mouth disease (HFMD). In order to determine the characteristics of epidemics and enteroviruses (EV) associated with HFMD in Tianjin, in northern China, epidemiological and virological data from routine surveillance were collected and analyzed. In Tianjin, a persistent epidemic of HFMD was demonstrated during 2008-2013, involving 102,705 mild, 179 severe, and 16 fatal cases. Overall, 8234 specimens were collected from 7829 HFMD patients for EV detection during 2008-2013. Enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) were the dominant serotypes during 2008-2012, and they were replaced by CV-A6 as the major causative agent in 2013. Phylogenetic analysis based on complete VP1 nucleotide sequences revealed that multiple CV-A6 lineages co-circulated in Tianjin, which grouped together with strains from China and other countries and split into two distinct clusters (clusters 1 and 2). Most Tianjin strains grouped in cluster 1 and were closely related to strains from several eastern and southern provinces of China during 2012 and 2013. Estimates from Bayesian MCMC analysis suggested that multiple lineages had been transmitted silently before the outbreaks at an estimated evolutionary rate of 4.10 × 10(-3) substitutions per site per year without a specific distribution of rate variances among lineages. The sudden outbreak of CV-A6 in Tianjin during 2013 is attributed to indigenous CV-A6 lineages, which were linked to the wide spread of endemic strains around eastern and southern China.

Anionogenic mixed valency in KxBa1-xO2-δ.

We have synthesized members of an isostructural solid solution series KxBa1-xO2-δ (x < 0.41, δ < 0.11) containing mixed-valent dioxygen anions. Synthesis in liquid ammonia solution allows a continuous range of compounds to be prepared. X-ray and neutron diffraction show that KxBa1-xO2-δ adopts the tetragonal rocksalt-derived structure of the end members KO2 and BaO2, without any structural phase transition down to 5 K, the lowest temperature studied here. We identify four oxygen-oxygen stretching modes above 750 cm(-1) in the measured Raman spectra, unlike the spectra of KO2 and BaO2 which both contain just a single mode. We use density functional theory calculations to show that the stretching modes in KxBa1-xO2-δ arise from in-phase and anti-phase coupling of the stretching of nearest-neighbor oxygen dimers when the valence state of the dimers lies between -1 and -2 because of mixed cation coordination. This coupling is a direct signature of a novel type of anionogenic mixed valency.

An outbreak of echovirus 33 in schools in China in 2013.

Echovirus 33 (E33) has been infrequently detected and is less frequently associated with clinical diseases when compared with other types of enteroviruses (EVs) in China. An outbreak of E33 was identified in four schools in Hunan Province, China, in June 2013. For laboratory diagnosis, throat swabs and/or serum specimens were collected from 27 patients. E33 was isolated in cell culture and typed by molecular methods. Complete VP1 gene sequences were determined and analyzed. Specific E33 antibody was measured by virus neutralization testing. From June 3-20, 108 suspected cases were reported, and 19 were confirmed to be associated with E33 by laboratory testing, with seven virologically confirmed and 12 serologically confirmed cases. The suspected cases were in children aged 3-16 years (mean, 11 years), most of whom (94%, 102/108) were ≥6 years old. The majority of cases (98%, 106/108) presented as influenza-like illness (ILI), and two were clinically diagnosed as viral meningitis. Older children aged ≥12 years had a higher hospitalization rate (21%) than younger children (4%). A BLAST query of GenBank with the Hunan E33 strain VP1 gene sequence gave a close match to an E33 isolate from Pakistan, based on a partial VP1 gene sequence. Phylogenetic analyses of the complete E33 VP1 gene sequences from our study revealed an independent cluster with nucleotide sequences that diverge from E33 from other countries by >12%. Due to limited E33 VP1 gene sequence data in GenBank and passive EV surveillance in China and most other parts of the world (excepting hand, foot, and mouth disease surveillance in Asia), the approximate origin of Hunan E33 could not be determined.

The Impact of Transcriptional Profiling Cadherin Family and Therapeutic Approaches of Gastric Cancer: A Translational Outlook on Multi-omics Data Analysis.

The classical cadherin gene has been linked to a variety of human malignancies, including gastric cancer. However, the link between cadherin genes and gastric cancer outcome is still unclear. This study used multi-omics data to examine the cadherin genes that were differentially regulated in gastric cancer. Differential expression of genes, epigenetic, molecular alterations, and protein expression analyses was conducted. Male SD rats were given N-methyl-N-nitrosourea (MNU) to induce stomach carcinoma in order to verify the activation of cadherin genes. CDH5, CDH6, CDH11, and CDH24 levels were found to be considerably higher in gastric cancer and may serve as useful indicators of stomach adenocarcinoma (STAD). Cadherin genes with variable expression had considerably more promoter methylation in cancers than in normal tissues. In individuals with gastric cancer, high expression of these cadherin genes was related to lower total mortality and disease-free survival rates. Furthermore, compared to normal rats, gastric cancer-induced rats had significantly higher expression and distribution of CDH5, CDH6, CDH11, and CDH24. This study sheds new light on the diagnosis and prognosis of gastric cancer by identifying potential prognostic markers such as CDH5, CDH6, CDH11, and CDH24. The multi-omics approach provided a potential tool for target-based therapy by accurately predicting the outcome of stomach cancer. Researchers may gain more knowledge about the role of cadherin genes in the development and dissemination of tumors to the activated rat model of gastric cancer.

Antiferromagnetic S=1/2 spin chain driven by p-orbital ordering in CsO2.

We demonstrate, using a combination of experiment and density functional theory, that orbital ordering drives the formation of a one-dimensional (1D) S=1/2 antiferromagnetic spin chain in the 3D rocksalt structure of cesium superoxide (CsO2). The magnetic superoxide anion (O2(-)) exhibits degeneracy of its 2p-derived molecular orbitals, which is lifted by a structural distortion on cooling. A spin chain is then formed by zigzag ordering of the half-filled superoxide orbitals, promoting a superexchange pathway mediated by the p(z) orbitals of Cs(+) along only one crystal direction. This scenario is analogous to the 3d-orbital-driven spin chain found in the perovskite KCuF3 and is the first example of an inorganic quantum spin system with unpaired p electrons.

[Raman spectra of pyroxene].

By testing the Raman spectra of megacryst pyroxene, enstatite and diopside in terms of location, shape and intensity, the symmetries of the main spectral band of pyroxene and the vibration modes of Raman shift were identified. The spectral bands of corresponding ionic groups such as non-bridge oxygen Si-O- and bridge oxygen Si-O0, O-Si-O and M-O were assigned for vibrational mode. Through the change in the intensity of the spectral band in different section direction and the deficiency of some spectral bands, the orientation problem in mineral crystallography was preliminarily studied.

[Crystallography orientation by molecular spectrum of structural hydroxide in pyroxene megacryst].

Crystal can be crystallographically oriented by molecular spectrum with the change in band shift, band intensity, and band shape. The three groups of band shift of augite are different between vertical to c-axis and parallel to c-axis: the first peak value 3 629-3 633 red shifts to 3 601-3 616; the same as the second peak value 3 514-3 543; on the contrary, the third peak value 3 460-3 465 is blue shift. The intensity of the first band is equivalent in two directions, while the second and the third parallel to c-axis are much stronger than the vertical. The wave shape is not quite different. The intensity of the Raman spectra vertical to c-axis is stronger than that parallel to c-axis in general, while the band shift and the shape show little difference. It was indicated that the geological tectonic environment can be reflected by the spectra of structural hydroxide with different crystal directions.

Na2C monolayer: a novel 2p Dirac half-metal with multiple symmetry-protected Dirac cones.

A Dirac half-metal material, which has a gapped band structure in one spin channel but Dirac cones in the other, combines two intriguing properties of 100% spin polarization and massless Dirac fermions and has recently started to attract increasing attention. In this work, using first-principles calculations we predict that the disodium carbide (Na2C) monolayer is an intrinsic 2p Dirac half-metal material with 12 fully spin-polarized and symmetry-protected Dirac cones, and a slightly gapped (53 meV) spin-polarized nodal line coexisting in one spin channel, leaving the other spin channel insulated with a gap of 1.9 eV. There are two kinds of Dirac cones in Na2C, protected by different crystalline symmetries, both of which are robust against biaxial strains (±5%) and spin-orbit coupling effects, with Fermi velocities of up to 5.2 × 105 m s-1. Ferromagnetism is mainly contributed to by the unpaired 2p electrons in the carbon, with a Curie temperature estimated to be 382 K, and the origin of the 2p magnetism could be explained by the superexchange mechanism between C2- anions with the Na+ cation as a bridge. Our results not only indicate a promising candidate for high-speed spintronic devices, but also reveal the hidden mechanism of the origin of symmetric protection and ferromagnetic exchange interactions in a Dirac semi-metal, which would provide a feasible strategy for the design of Dirac materials.

Robust Room-Temperature Quantum Spin Hall Effect in Methyl-functionalized InBi honeycomb film.

Two-dimensional (2D) group-III-V honeycomb films have attracted significant interest for their potential application in fields of quantum computing and nanoelectronics. Searching for 2D III-V films with high structural stability and large-gap are crucial for the realizations of dissipationless transport edge states using quantum spin Hall (QSH) effect. Based on first-principles calculations, we predict that the methyl-functionalized InBi monolayer (InBiCH3) has no dynamic instability, and hosts QSH state with a band gap as large as 0.29 eV, exhibiting an interesting electronic behavior viable for room-temperature applications. The topological characteristic is confirmed by s-pxy band inversion, topological invariant Z2 number, and the time-reversal symmetry protected helical edge states. Noticeably, the QSH states are tunable and robust against the mechanical strain, electric field and different levels of methyl coverages. We also find that InBiCH3 supported on h-BN substrate maintains a nontrivial QSH state, which harbors the edge states lying within the band gap of substrate. These findings demonstrate that the methyl-functionalized III-V films may be a good QSH platform for device design and fabrication in spintronics.

Unexpected Giant-Gap Quantum Spin Hall Insulator in Chemically Decorated Plumbene Monolayer.

Quantum spin Hall (QSH) effect of two-dimensional (2D) materials features edge states that are topologically protected from backscattering by time-reversal symmetry. However, the major obstacles to the application for QSH effect are the lack of suitable QSH insulators with a large bulk gap. Here, we predict a novel class of 2D QSH insulators in X-decorated plumbene monolayers (PbX; X = H, F, Cl, Br, I) with extraordinarily giant bulk gaps from 1.03 eV to a record value of 1.34 eV. The topological characteristic of PbX mainly originates from s-p(x,y) band inversion related to the lattice symmetry, while the effect of spin-orbital coupling (SOC) is only to open up a giant gap. Their QSH states are identified by nontrivial topological invariant Z2 = 1, as well as a single pair of topologically protected helical edge states locating inside the bulk gap. Noticeably, the QSH gaps of PbX are tunable and robust via external strain. We also propose high-dielectric-constant BN as an ideal substrate for the experimental realization of PbX, maintaining its nontrivial topology. These novel QSH insulators with giant gaps are a promising platform to enrich topological phenomena and expand potential applications at high temperature.

[Quantitative determination of glass content in monazite glass-ceramics by IR technique].

Monazite glass-ceramics consist of both monazite and metaphoshate glass phases. The absorption bands of both phases do not overlap each other, and the absorption intensities of bands 1,275 and 616 cm-1 vary with the glass contents. The correlation coefficient between logarithmic absorbance ratio of the two bands and glass contents was r = 0.9975 and its regression equation was y = 48.356 + 25.93x. The absorbance ratio of bands 952 and 616 cm-1 also varied with different ratios of Ce2O3/La2O3 in synthetic monazites, with r = 0.9917 and a regression equation y = 0.2211 exp (0.0221x). High correlation coefficients show that the IR technique could find new application in the quantitative analysis of glass content in phosphate glass-ceramics.

Molecular epidemiology of coxsackievirus A16: intratype and prevalent intertype recombination identified.

Coxsackievirus A16 (CVA16) is responsible for nearly 50% of all the confirmed hand, foot, and mouth disease (HFMD) cases in mainland China, sometimes it could also cause severe complications, and even death. To clarify the genetic characteristics and the epidemic patterns of CVA16 in mainland China, comprehensive bioinfomatics analyses were performed by using 35 CVA16 whole genome sequences from 1998 to 2011, 593 complete CVA16 VP1 sequences from 1981 to 2011, and prototype strains of human enterovirus species A (EV-A). Analysis on complete VP1 sequences revealed that subgenotypes B1a and B1b were prevalent strains and have been co-circulating in many Asian countries since 2000, especially in mainland China for at least 13 years. While the prevalence of subgenotype B1c (totally 20 strains) was much limited, only found in Malaysia from 2005 to 2007 and in France in 2010. Genotype B2 only caused epidemic in Japan and Malaysia from 1981 to 2000. Both subgenotypes B1a and B1b were potential recombinant viruses containing sequences from other EV-A donors in the 5'-untranslated region and P2, P3 non-structural protein encoding regions.

[Rash and fever illness caused by herpes simplex virus type 1 needs to be distinguished from hand, foot and mouth disease].

An epidemic of rash and fever illnesses suspected of hand, foot and mouth disease (HFMD) occurred in Gansu Province of China in 2008, laboratory tests were performed in order to identify the pathogen that caused this epidemic. Eight clinical specimens collected from the 4 patients (each patient has throat swab and herpes fluid specimens) with rash and febrile illness, were inoculated onto RD and HEp-2 cells for virus isolation, and the viral nucleic acid was then extracted with the positive virus isolates, the dual-channel real-time reverse transcript-polymerase chain reaction (RT-PCR) was performed to detect the nucleic acid of human enterovirus (HEV) in the viral isolates at the same time. For the viral isolates with the negative results of HEV, a sequence independent single primer amplification technique (SISPA) was used for "unknown pathogen" identification. Totally, 6 viral isolates were identified as herpes simplex virus type 1 (HSV-1). Comprehensive analyses results of the clinical manifestations of the patients, epidemiological findings and laboratory test indicated that this epidemic of rash and febrile illness was caused by HSV-1. The differences among the gG region of 6 HSV-1 isolates at nucleotide level and amino acid level were all small, and the identities were up to 98. 8% and 97.9%, respectively, showing that this outbreak was caused by only one viral transmission chain of HSV-1. HSV-1 and other viruses that cause rash and febrile illnesses need differential diagnosis with HFMD. The etiology of rash and febrile illness is sometimes difficult to distinguish from the clinical symptoms and epidemiological data, the laboratory diagnosis is therefore critical.