Perceived rather than objective weight status is associated with suicidal behaviors among Chinese adolescents: a school-based study.

BACKGROUND: We aimed to explore the relationship between body mass index (BMI) and body weight perception (BWP) with suicidal behaviors among mainland Chinese adolescents. METHODS: A nationally representative sample (N = 10 110) of Chinese adolescents was assessed in this study. Suicidal behaviors (ideation, plan and attempt) were evaluated by four self-reported questions. Generalized linear mixed model was used to estimate the adjusted odds ratios (ORs) for the association between BWP/BMI with suicidal behaviors. RESULTS: The prevalence of suicidal ideation, suicidal plan and suicidal attempt was 12, 5 and 2.1%, respectively. After adjusting potential covariates, perceiving oneself as obese was significantly associated with increased risks of suicidal ideation (OR: 2.4, 95% confidence intervals, CI: 1.6-4.0, P = 0.001), suicidal plan (OR: 3.1, 95% CI: 1.5-6.3, P = 0.002) and suicidal attempt (OR: 3.7, 95% CI: 1.5-9.1, P = 0.001) compared with perceiving as normal weight among male adolescents; the effect attenuated to null among female adolescents. Perceiving oneself as underweight and overweight both exhibited significant adverse effect on suicidal behaviors (only suicidal ideation and suicidal plan) compared with perceiving oneself as normal weight among male adolescents, but not among female adolescents. The actual measured BMI was not significantly associated with suicidal behaviors among neither gender. CONCLUSIONS: Self-perception of their body image rather than actual measured weight may have a gender-specific adverse effect on suicidal behaviors among Chinese adolescents.

Characterization of CsTSI in the Biosynthesis of Theanine in Tea Plants (Camellia sinensis).

Theanine is a unique major amino acid in tea plants responsible for umami taste and mental health benefits of tea. However, theanine biosynthesis and physiological role in tea plants are not fully understood. Here, we demonstrate that tea plant theanine synthetase is encoded by a glutamine synthetase gene CsTSI. The expression pattern of CsTSI is closely correlated with theanine and glutamine levels in various tissues. CsTSI transcripts were accumulated in root tip epidermal cells, pericycle and procambial cells, where CsTSI presents as a cytosolic protein. Ectopic expression of the gene in Arabidopsis led to greater glutamine and theanine production than controls when fed with ethylamine (EA). RNAi knockdown or overexpression of CsTSI in tea plant hairy roots reduced or enhanced theanine and glutamine contents, respectively, compared with controls. The CsTSI recombinant enzymes used glutamate as an acceptor and ammonium or EA as a donor to synthesize glutamine and theanine, respectively. CsTSI expression in tea roots responded to nitrogen supply and deprivation and was correlated with theanine contents. This study provides fresh insights into the molecular basis for the biosynthesis of theanine, which may facilitate the breeding of high-theanine tea plants for improving the nutritional benefit of tea.

Synthesis of a Cyclophosphazene Derivative Containing Multiple Cyano Groups for Electron-Beam Irradiated Flame-Retardant Materials.

A cyclophosphazene derivative containing multiple cyano groups, denoted as hexa(4-cyanophenoxy)cyclotriphosphazene (CN-CP), was synthesized by a one-step nucleophilic substitution reaction for a phosphorus-nitrogen flame retardant. To meet the strict requirement of safe and environment-protective insulation materials, a series of composites based on low-density polyethylene-poly(ethylene-co-vinyl acetate) containing CN-CP/Mg(OH)2/Al(OH)3 organic-inorganic synergistic flame retardants was fabricated. High-energy electron beam irradiation was subsequently applied to obtain a halogen-free flame-retardant crosslinked system. The relationship between crosslinking degree and irradiation dose was studied, and crosslinking degrees ranging within 63-85% were obtained under 100-190 kGy. Furthermore, the effects of CN-CP filler and irradiation dose on the properties of the composites were carefully investigated. The maximum tensile stress and limiting oxygen index values of most composites irradiated by EB were more than 15 MPa and 28%. Results revealed that the obtained materials had excellent thermal and mechanical, flame-retardant, and insulation properties, thereby suggesting their promising prospects for wire and cable applications.

Thermal decomposition of ammonium perchlorate-based molecular perovskite from TG-DSC-FTIR-MS and ab initio molecular dynamics.

(H2dabco)[NH4(ClO4)3] (DAP, dabco = 1,4-diazabicyclo[2.2.2]octane) is a recently synthesized ammonium perchlorate-based molecular perovskite energetic material. The high-symmetry perovskite configuration assembles the oxidant ClO4 - and fuel H2dabco2+ into a compact cubic crystal, realizing a high energy-releasing efficiency. In this study, the thermal decomposition of DAP has been investigated by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) coupled with Fourier transform infrared (FTIR) spectroscopy and mass spectroscopy (MS). The TG-DSC profiles show that DAP has an intense one-stage heat release process with a weight loss of 94.7%. The evolved gas products are identified as H2O, CO2, CO, HCl, HCN, NH3, HNCO by FTIR spectrum, in which the infrared characteristic peak at 2283 and 2250 cm-1 is clarified not from N2O and assigned to HNCO. The principal products are H2O and CO2 together with significant amounts of HCl, HCN, NH3 in MS, while few nitrogen oxides and O2 are detected. The experimental results show that organic components have been the prominent media for the degradation of ClO4 -. To refine the mechanism observed in experiment, ab initio molecular dynamics simulations are carried out to reveal the atomistic reaction mechanisms. The decomposition of DAP starts with proton transfer from NH4 + and H2dabco2+ to ClO4 -. The deprotonated carbon skeleton is preferable to NH3 in capturing O atoms, realizing a faster consumption of O atoms. Amounts of H atoms enter the environment being active free radicals, realizing an efficient autocatalytic chain propagation of degradation of ClO4 -. The atomistic thermal decomposition reaction mechanism of DAP uncovers the role of organic components in promoting the degradation of ClO4 -, which will help improve the synthesis strategy of molecular perovskite energetic materials with improved performance.

Poly(arylene ether sulfone) crosslinked networks with pillar[5]arene units grafted by multiple long-chain quaternary ammonium salts for anion exchange membranes.

Several high-molecular-weight pillar[5]arene-containing poly(arylene ether sulfone) polymers were synthesized for the first time. Through grafting and crosslinking approaches, networks consisting of the molecular chains bearing multiple long-chain quaternary amine salts were fabricated. For the crosslinked membranes, high conductivity and low swelling were achieved even at low ion exchange capacity.

Endophytic Bacteria as Contributors to Theanine Production in Camellia sinensis.

Theanine is the most abundant non-protein amino acid in Camellia sinensis, but it is not known how a tea plant accumulates such high levels of theanine. The endophyte isolated from in vitro grown plantlets of C. sinensis cultivars was identified as Luteibacter spp., showing strong biocatalytic activity for converting both glutamine and ethylamine to theanine. Theanine was secreted outside of the bacteria. The endophyte isolated from in vitro plantlets of Camellia oleifera cultivar was identified as Bacillus safensis and did not convert glutamine and ethylamine to theanine. Enzymatic assays in vitro indicated that γ-glutamyltranspeptidases rCsEGGTs from the endophyte Luteibacter strains converted glutamine and ethylamine to theanine at higher rates than rCsGGTs from C. sinensis. This is the first report on theanine biosynthesis by an endophyte from C. sinensis, which provides a new pathway to explore the mechanism of theanine biosynthesis in C. sinensis and the interactions between an endophyte and tea plants.

The tea plant reference genome and improved gene annotation using long-read and paired-end sequencing data.

Tea is a globally consumed non-alcohol beverage with great economic importance. However, lack of the reference genome has largely hampered the utilization of precious tea plant genetic resources towards breeding. To address this issue, we previously generated a high-quality reference genome of tea plant using Illumina and PacBio sequencing technology, which produced a total of 2,124 Gb short and 125 Gb long read data, respectively. A hybrid strategy was employed to assemble the tea genome that has been publicly released. We here described the data framework used to generate, annotate and validate the genome assembly. Besides, we re-predicted the protein-coding genes and annotated their putative functions using more comprehensive omics datasets with improved training models. We reassessed the assembly and annotation quality using the latest version of BUSCO. These data can be utilized to develop new methodologies/tools for better assembly of complex genomes, aid in finding of novel genes, variations and evolutionary clues associated with tea quality, thus help to breed new varieties with high yield and better quality in the future.

Molecular dynamics simulations of a cyclotetramethylene tetra-nitramine/hydrazine 5,5'-bitetrazole-1,1'-diolate cocrystal.

An energetic ionic salt (EIS)-based cocrystal formation, cyclotetramethylene tetra-nitramine (HMX)/hydrazine 5,5'-bitetrazole-1,1'-diolate (HA·BTO), is predicted based on molecular dynamics simulations. HA·BTO is a newly-synthesized environmentally friendly energetic ionic salt with good detonation performance and low sensitivity. Calculated powder X-ray diffraction patterns and intermolecular interactions deduce the formation of the new cocrystal structure. Radial distribution function analysis suggests that hydrogen bonds and van der Waals (vdW) forces exist between the H⋯O pairs of HMX and HA·BTO, while the hydrogen bonds between the H of HA·BTO and the O of HMX play a prominent role. The cohesive energy density and mechanical properties are also analyzed. The cohesive energy density of the HMX/HA·BTO cocrystal is larger than that of the composite of HMX and HA·BTO, indicating an improvement in crystal stability by cocrystalization. Compared to both HMX and HA·BTO, HMX/HA·BTO has smaller Young modulus, bulk modulus and shear modulus values, but larger K/G values and a positive Cauchy pressure, suggesting decreased stiffness and improved ductibility. Moreover, the calculated formation energy is -405.79 kJ mol-1 at 298 K, which implies that the proposed cocrystal structure is likely to be synthesized at ambient temperature. In summary, we have predicted an EIS-based cocrystal formation in which the safety and mechanical properties of HMX have been improved via cocrystalization with HA·BTO, and this provides deep insight into the formation mechanism of the EIS-based cocrystal.

Draft genome sequence of Camellia sinensis var. sinensis provides insights into the evolution of the tea genome and tea quality.

Tea, one of the world's most important beverage crops, provides numerous secondary metabolites that account for its rich taste and health benefits. Here we present a high-quality sequence of the genome of tea, Camellia sinensis var. sinensis (CSS), using both Illumina and PacBio sequencing technologies. At least 64% of the 3.1-Gb genome assembly consists of repetitive sequences, and the rest yields 33,932 high-confidence predictions of encoded proteins. Divergence between two major lineages, CSS and Camellia sinensis var. assamica (CSA), is calculated to ∼0.38 to 1.54 million years ago (Mya). Analysis of genic collinearity reveals that the tea genome is the product of two rounds of whole-genome duplications (WGDs) that occurred ∼30 to 40 and ∼90 to 100 Mya. We provide evidence that these WGD events, and subsequent paralogous duplications, had major impacts on the copy numbers of secondary metabolite genes, particularly genes critical to producing three key quality compounds: catechins, theanine, and caffeine. Analyses of transcriptome and phytochemistry data show that amplification and transcriptional divergence of genes encoding a large acyltransferase family and leucoanthocyanidin reductases are associated with the characteristic young leaf accumulation of monomeric galloylated catechins in tea, while functional divergence of a single member of the glutamine synthetase gene family yielded theanine synthetase. This genome sequence will facilitate understanding of tea genome evolution and tea metabolite pathways, and will promote germplasm utilization for breeding improved tea varieties.

Deep sequencing of the Camellia sinensis transcriptome revealed candidate genes for major metabolic pathways of tea-specific compounds.

BACKGROUND: Tea is one of the most popular non-alcoholic beverages worldwide. However, the tea plant, Camellia sinensis, is difficult to culture in vitro, to transform, and has a large genome, rendering little genomic information available. Recent advances in large-scale RNA sequencing (RNA-seq) provide a fast, cost-effective, and reliable approach to generate large expression datasets for functional genomic analysis, which is especially suitable for non-model species with un-sequenced genomes. RESULTS: Using high-throughput Illumina RNA-seq, the transcriptome from poly (A)+ RNA of C. sinensis was analyzed at an unprecedented depth (2.59 gigabase pairs). Approximate 34.5 million reads were obtained, trimmed, and assembled into 127,094 unigenes, with an average length of 355 bp and an N50 of 506 bp, which consisted of 788 contig clusters and 126,306 singletons. This number of unigenes was 10-fold higher than existing C. sinensis sequences deposited in GenBank (as of August 2010). Sequence similarity analyses against six public databases (Uniprot, NR and COGs at NCBI, Pfam, InterPro and KEGG) found 55,088 unigenes that could be annotated with gene descriptions, conserved protein domains, or gene ontology terms. Some of the unigenes were assigned to putative metabolic pathways. Targeted searches using these annotations identified the majority of genes associated with several primary metabolic pathways and natural product pathways that are important to tea quality, such as flavonoid, theanine and caffeine biosynthesis pathways. Novel candidate genes of these secondary pathways were discovered. Comparisons with four previously prepared cDNA libraries revealed that this transcriptome dataset has both a high degree of consistency with previous EST data and an approximate 20 times increase in coverage. Thirteen unigenes related to theanine and flavonoid synthesis were validated. Their expression patterns in different organs of the tea plant were analyzed by RT-PCR and quantitative real time PCR (qRT-PCR). CONCLUSIONS: An extensive transcriptome dataset has been obtained from the deep sequencing of tea plant. The coverage of the transcriptome is comprehensive enough to discover all known genes of several major metabolic pathways. This transcriptome dataset can serve as an important public information platform for gene expression, genomics, and functional genomic studies in C. sinensis.

Robust stereo image matching using a two-dimensional monogenic wavelet transform.

A robust approach based on the 2D monogenic wavelet transform (MWT), which pairs the polyharmonic B-spline wavelet basis with its complex Riesz counterparts to specify a multiresolution monogenic signal analysis, is proposed to solve the general stereo image matching problem. The disparity is directly estimated by establishing correspondences between the monogenic signal components according to the suitable local properties, i.e., the monogenic wavelet annihilates antimonogenic signals, the MWT is phase-shift covariant and the transform magnitude is phase-shift invariant. This approach is different from the current matching techniques and is promising for image registration, flow estimation, and 3D reconstruction.

Preparation and electrical properties of ultrafine Ga2O3 nanowires.

Uniform and well-crystallized beta-Ga2O3 nanowires are prepared by reacting metal Ga with water vapor based on the vapor-liquid-solid (VLS) mechanism. Electron microscopy studies show that the nanowires have diameters ranging from 10 to 40 nm and lengths up to tens of micrometers. The contact properties of individual Ga2O3 nanowires with Pt or Au/Ti electrodes are studied, respectively, finding that Pt can form Schottky-barrier junctions and Au/Ti is advantageous to fabricate ohmic contacts with individual Ga2O3 nanowires. In ambient air, the conductivity of the Ga2O3 nanowires is about 1 (Omega.m)-1, while with adsorption of NH3 (or NO2) molecules, the conductivity can increase (or decrease) dramatically at room temperature. The as-grown Ga2O3 nanowires have the properties of an n-type semiconductor.