[Relationship between smoking status and obesity risk in males aged 18-64 years in 9 provinces of China, 1991-2015]

Objective: To investigate longitudinal association between smoking behavior and obesity risk in male adults in China from 1991 to 2015. Methods: A total of 32 169 male adults aged 18-64 years who participated in two or more rounds of China Health and Nutrition Survey (CHNS, 1991-2015) and had complete information of demographic characteristics, smoking status and physical measurements were selected as the study subjects. According to whether the subjects smoked or not and the number of cigarettes smoked per day, the subjects were divided into four groups: nonsmoker, light smoker (1-14 cigarettes/d), moderate smoker (15-24 cigarettes/d) and heavy smoker (≥25 cigarettes/d). The distribution of body mass index (BMI), waist circumference (WC), general obesity and central obesity of subjects with different smoking status were observed. Two-level mixed effect linear regression model and logistic regression model were used to analyze the relationship between smoking status and obesity risk. Results: Compared with nonsmokers, the BMI decreased by 0.19 kg/m² in light smokers (95%CI:-0.27--0.10), 0.40 kg/m² in moderate smokers (95%CI:-0.49--0.31), and 0.36 kg/m² in heavy smokers (95%CI:-0.53--0.19), respectively, and the WC decreased by 0.49 cm in light smokers (95%CI:-0.76--0.21), 0.80 cm in moderate smokers (95%CI:-1.08--0.51) and 0.79 cm in heavy smokers (95%CI:-1.38--0.36) in, respectively. Compared with nonsmokers, the odds ratio of the risk for general and abdominal obesity were 0.70 (95%CI:0.62-0.79) and 0.78 (95%CI:0.73-0.84) in light smokers, 0.61 (95%CI:0.55-0.69) and 0.74 (95%CI:0.70-0.79) in moderate smokers and 0.78 (95%CI:0.65-0.96) and 0.84 (95%CI:0.76-0.95) in heavy smokers, respectively. Conclusions: From 1991 to 2015, the BMI, WC, prevalence of general and abdominal obesity in male adults showed a significant upward trends in both nonsmokers and smokers (light, moderate and heavy) in China, suggesting that smoking is negatively associated with the risk for obesity in male adults.

Strong interlayer coupling in two-dimensional PbSe with high thermoelectric performance

It was generally believed that weak van der Waals interactions exist between neighboring layers in the two-dimensional group-IV chalcogenides. Using PbSe as a prototypal example, we find additional strong coupling between the Pb-Pb layers, as evidenced by detailed analysis of the differential charge density plot. The coupling is covalent-like and can be fine-tuned to obviously reduce the phonon thermal conductivity but slightly change the electronic transport of PbSe layer. As a consequence, a maximumZTvalue of 2.5 can be realized at 900 K for thep-type system. Our work also offers an effective and feasible design strategy to enhance the thermoelectric performance of similar layered structures.

[Relationship between smoking status and sleeping duration in male adults in 15 provinces of China, 2015]

Objective: To assess the relationship between smoking status and sleep duration in male adults in urban-rural areas of 15 provinces (municipalities, autonomous regions) in China in 2015. Methods: Data were derived from the China Nutritional Transition Cohort Study 2015, a total of 4 419 participants aged 18-64 years, including 1 713 urban males (38.8%) and 2 706 rural males (61.2%), with complete information about smoking status and sleep duration were included in the final analysis. Based on the number of cigarettes consumed daily, the current smokers were classified to be heavy (25 cigarettes/d and above), moderate (15-24 cigarettes/d), and light (1-14 cigarettes/d). Sleep duration was classified to be insufficient (<7 h/d), sufficient (7-9 h/d), and excessive (9 h/d and above). Two-level mixed-effects linear and logistic regression models were used for association analysis. Results: The smoking rates in male adults in urban and rural areas were 45.7% and 53.8%, respectively. In male heavy smokers in urban and rural areas, the proportions of sufficient sleep were the lowest (66.7% and 68.1%). However, the proportions of sleep deprivation were highest (15.3% and 20.3%). After controlling for confounding factors, the net effect on male heavy smokers was a significant decrease of 0.21 h/d (β=-0.21, 95%CI: -0.44 - -0.01) in sleep duration. Moreover, the odds ratio for insufficient sleep were 1.83 (95%CI: 1.03-3.23) in male heavy smokers in rural area compared with nonsmokers. Conclusion: Heavy smoking is associated with decreased sleep duration and increased risk of sleep deprivation in male adults in rural China.

High figure-of-merit in the heavy-fermion UN2 system for radioisotope thermoelectric applications

The design of uranium-based thermoelectric (TE) materials presents a novel and intriguing strategy for directly converting nuclear heat into electrical power. Using high-level first-principles approach combined with accurate solution of Boltzmann transport equation, we demonstrate that a giant n-type power factor of 13.8 mW m^-1 K^-2 and a peak ZT value of 2.2 can be realized in the heavy-fermion UN₂ compound at 700 K. Such promising TE performance arises from the large degeneracy (N _v = 14) of heavy conduction band coupled with weak electron-phonon interactions, which is in principle governed by the strong Coulomb correlation among the partially filled U-5f electrons in the face-centered cubic structure. Collectively, our theoretical work suggests that the energetic UN₂ could serve as both excellent heat source and efficient power convertor, which also uncovers an underexplored area for TE research.

A comparative study of the thermoelectric performance of graphene-like BX (X = P, As, Sb) monolayers

The electronic and phonon transport properties of graphene-like boron phosphide (BP), boron arsenide (BAs), and boron antimonide (BSb) monolayers are investigated using first-principles calculations combined with the Boltzmann theory. By considering both the phonon-phonon and electron-phonon scatterings, we demonstrate that the strong bond anharmonicity in the BAs and BSb monolayers can dramatically suppress the phonon relaxation time but hardly affect that of electron. As a consequence, both systems exhibit comparable power factors with that of the BP monolayer but much lower lattice thermal conductivities. Accordingly, a maximum ZT value above 3.0 can be realized in both BAs and BSb monolayers at optimized carrier concentration. Interestingly, very similar p - and n-type thermoelectric performance is observed in the BSb monolayer along the zigzag direction, which is of vital importance in the fabrication of thermoelectric modules with comparable efficiencies.

Thermal conductivities of phosphorene allotropes from first-principles calculations: a comparative study

Phosphorene has attracted tremendous interest recently due to its intriguing electronic properties. However, the thermal transport properties of phosphorene, especially for its allotropes, are still not well-understood. In this work, we calculate the thermal conductivities of five phosphorene allotropes (α-, β-, γ-, δ- and ζ-phase) by using phonon Boltzmann transport theory combined with first-principles calculations. It is found that the α-phosphorene exhibits considerable anisotropic thermal transport, while it is less obvious in the other four phosphorene allotropes. The highest thermal conductivity is found in the β-phosphorene, followed by the δ-, γ- and ζ-phase. The much lower thermal conductivity of the ζ-phase can be attributed to its relatively complex atomic configuration. It is expected that the rich thermal transport properties of phosphorene allotropes can have potential applications in the thermoelectrics and thermal management.

Understanding the electronic and phonon transport properties of a thermoelectric material BiCuSeO: a first-principles study

Using the first-principles pseudopotential method and Boltzmann transport theory, we give a comprehensive understanding of the electronic and phonon transport properties of a thermoelectric material BiCuSeO.

LaPtSb: a half-Heusler compound with high thermoelectric performance

The electronic and transport properties of the half-Heusler compound LaPtSb are investigated by performing first-principles calculations combined with semi-classical Boltzmann theory and deformation potential theory.

High thermoelectric performance of the distorted bismuth(110) layer

The thermoelectric properties of the distorted bismuth(110) layer are investigated using first-principles calculations combined with the Boltzmann transport equation for both electrons and phonons.

Co-expression of recombinant human prolyl with human collagen α1 (III) chains in two yeast systems

In this study, we co-expressed the human prolyl 4-hydroxylases (P4H) with human collagen α1 (III) (COL3A1) in an inducible system: Pichia pastoris (pPICZB), and one constitutive system: P. pastoris (pGAPZαB). The P4H catalyses the post-translational hydroxylation of proline residues in collagen strands. Conventional protein expression system such as bacteria and yeasts, which lack endogenous P4H, are not efficient for the production of recombinant collagen. In this study, the P4H gene was constructed in pGAPZαB plasmid and pPICZB plasmid respectively. These two plasmids were transformed in P. pastoris #1 that carrying COL3A1. Colony PCR analysis and sequencing after electroporation P. pastoris GS115 showed that the target gene had inserted successfully. The results of reverse transcript-qPCR, SDS-PAGE, Western blotting and LC-MS/MS analysis of the rhCOL3A1 demonstrated that the P4H was expressed successfully. Besides, it is noted that low copy number, constitutive system was suitable for hydroxylated rhCOL3A1.

SIGNIFICANCE AND IMPACT OF THE STUDY

Successful co-expression of recombinant human collagen α1 (III) (rhCOL3A1) and human prolyl 4-hydroxylases (P4H) in Picha pastoris GS115, simultaneously results in the acquisition of rhCOL3A1 with hydroxylation of proline (Hyp). Further, this experiment also discusses that the high or low copy numbers and different promoters affect the Hyp degree of rhCOL3A1. Selecting more appropriate strains can express high degree Hyp of rhCOL3A1. This work will be helpful to the collagen structure study.

Enhanced thermoelectric performance of carbon nanotubes at elevated temperature

High thermoelectric performance can be realized in single-walled carbon nanotubes by isotopic substitution and chemisorptions of hydrogen.

Inoculation of phosphate solubilizing bacteria for the improvement of lead accumulation by Brassica juncea

Two phosphate-solubilizing bacterial strains were isolated and identified as Acinetobacter calcoaceticus YC-5a and Enterobacter agglomerans KMC-7 based on the 16S rRNA gene sequence analysis. A. calcoaceticus YC-5a is less well known as a phosphate-solubilizing plant-associated bacterium. The plant growth-promoting properties of the phosphate-solubilizing bacteria (PSB) were characterized in vitro, including their phosphate-solubilizing activities and their capabilities for producing indole-3-acetic acid and siderophores. A pot experiment was conducted to elucidate the effects of inoculating both strains on the growth and Pb uptake of Brassica juncea grown in different concentrations of Pb-contaminated soils. Inoculation with both PSB not only stimulated the growth of B. juncea, but it also influenced the accumulation of Pb in the shoots and roots of the host plant. The present study demonstrates that PSB are a valuable microbial resource that can be exploited to improve the efficiency of phytoextraction.

Bone regeneration by using scaffold based on mineralized recombinant collagen

Bone regeneration was achieved in the 15-mm segmental defect model in the radius of rabbit by using the scaffold based on mineralized recombinant collagen for the first time. The recombinant collagen was recombinant human-like type I collagen, which was produced by cloning a partial cDNA that was reversed by mRNA from human collagen alpha1(I) and transferred to E. coli. The scaffold material nano-hydroxyapatite/recombinant human-like collagen/poly(lactic acid) (nHA/RHLC/PLA) was developed by biomimetic synthesis. Thermo gravimetric analysis, X-ray diffraction and scanning electron microscopy were applied to exhibit that the scaffold showed some features of natural bone both in main component and hierarchical microstructure. The percentages of organic phase and inorganic phase of nHA/RHLC were similar to that of natural bone. The three-dimensional porous scaffold materials mimic the microstructure of cancellous bone. In the implantation experiment, the segmental defect was healed 24 weeks after surgery, and the implanted composite was completely substituted by new bone tissue. The results of the implantation experiment were very comparable with that of the scaffold based on mineralized animal-sourced collagen. It is concluded that the scaffold based on mineralized recombinant collagen maintains the advantages of mineralized animal-sourced collagen, while avoids potential virus-dangers. The scaffold is a promising material for bone tissue engineering.

Modification of bone graft by blending with lecithin to improve hydrophilicity and biocompatibility

Lecithin was blended to improve the hydrophilicity and biocompatibility of bone graft containing poly(l-lactic acid) (PLLA). Solution blending and freeze drying were used to fabricate symmetrical scaffolds containing different percentages of lecithin (lecithin: PLLA = 0, 5, 10 wt%). Scanning electron microscopy showed that the scaffolds maintained the three-dimensional porous structure. A water uptake experiment proved the significant improvement of hydrophilicity of the blend scaffold. With the addition of lecithin, the compressive strength and compressive modulus decreased. When the weight ratio of lecithin to PLLA was up to 10%, the compressive strength was still more than the lower limit of natural cancellous bone. To test the biocompatibility of the scaffolds, cell culture in vitro and subcutaneous implantation in vivo were performed. MC3T3-E1 preosteoblastic cells were cultured on the scaffolds for 7 days. Methylthiazol tetrazolium assay and laser scanning confocal microscopy were used to exhibit proliferation and morphology of the cells. The subcutaneous implantation in rats tested inflammatory response to the scaffolds. The results proved the better biocompatibility and milder inflammatory reactions of the blend scaffold (lecithin: PLLA = 5%) compared with the scaffold without lecithin. The modified scaffold containing lecithin is promising for bone tissue engineering.