多型号丝锥的Pro/E参数化与族表联合建模方法

不同规格丝锥的三维模型形状相似,为了避免不同规格丝锥模型的重复建立,基于Pro/E三维软件,结合其参数化与族表功能,介绍了不同规格丝锥快速生成三维模型的方法。     

基于图像处理的针织物表面纹理参数分析

利用图像处理技术对针织物二维显微图像进行处理并进一步重构出三维纹理图像,在此基础上,通过对重构的三维图像截面曲线进行分析,提出3个针织物纹理信息特征参数:峰谷高度差、相邻两横列嵌入纱线平均距离、嵌入纱线曲率半径。同时对织物试样进行从0到75%的4个等梯度纵横向拉伸后,形成8种规则变化的织物纹理结构试样,比较分析其纹理特征参数的变化。结果表明,随着纵向拉伸,其峰谷高度差、相邻纱线平均距离呈线性增长,而在横向拉伸过程中,其峰谷高度差呈下降趋势,而相邻纱线平均距离基本不变,且嵌入纱线曲率半径在拉伸过程无显著性变化,这些参数的变化与拉伸过程表面纹理的变化过程一致。从一定程度上证实了所提出的特征参数可以实现对针织物纹理参数的定量表征,这一结果将有助于在织物外观检测过程对表面纹理特征的表达。     

High postnatal exposures to polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) via breast milk in California: does BDE-209 transfer to breast milk?

Breast milk samples collected during 2003-2005 from 82 first-time mothers in 24 communities located throughout California contained levels of polybrominated diphenyl ethers (∑(tri-hexa (8))PBDEs; median = 53.3 ng/g lw, range = 9.60-1291) and polychlorinated biphenyls (∑(12)PCBs; median = 73.4 ng/g lw, range = 22.2-433) that are among the highest in the world. PBDE levels varied 100-fold. BDE-47 was the dominant PBDE congener, with levels exceeding the U.S.EPA Reference Dose (RfD) for neurodevelopmental toxicity (100 ng/kg/day) in most (60%) breast milk samples. In some samples, BDE-209 (2/82) and/or BDE-153 (5/82) were the dominant congeners, suggesting that BDE-209 can transfer to breast milk and/or break down in the mother and transfer to the nursing infant as the lower-brominated PBDEs associated with adverse effects. PBDE levels in California breast milk are approaching those of PCBs, and the trend PBDEs > PCBs may continue as PBDEs migrate from products to the indoor and outdoor environments.     

Classifi cation of carbonate gas condensate reservoirs using well test and production data analyses

Carbonate reservoir patterns play an important role in the production performance of oil and gas wells,and it is usually classified through static data analysis which cannot reflect the actual well performance.This paper takes the Tazhong No.1 gas field in the Tarim Basin,China as an example to investigate the classification of carbonate reservoirs.The classification method mainly combines well test analysis with production analysis—especially the Blasingame type curve method.Based on the characteristics of type curves for well test analysis and the Blasingame method,the relationship between the type curves and reservoir pattern was established.More than 20 wells were analyzed and the reservoirs were classified into 3 major patterns with 7 sub-classes.Furthermore,the classification results were validated by dynamic performance analysis of wells in the Tazhong No.1 gas field.On the basis of the classification results,well stimulation(i.e.water flooding in a single well) was carried out in three volatile-oil wells,and the oil recovery increased by up to 20%.     

Bigger is Surprisingly Better: Agglomerates of Larger RuP Nanoparticles Outperform Benchmark Pt Nanocatalysts for the Hydrogen Evolution Reaction

Although metallic ruthenium (Ru) is a potential electrocatalyst for the hydrogen evolution reaction (HER) to replace platinum (Pt) at a cost of only ≈4% of Pt, the persistent dissolution of Ru under operation conditions remains a challenge. Here, it is reported that agglomerates of large ruthenium phosphide (RuP) particles (L‐RP, ≈32 nm) show outstanding HER performance in pH‐universal electrolytes, which particularly demonstrates a surprisingly higher intrinsic activity and durability than small nanoparticles of RuP (S‐RP, ≈3 nm) or metallic Ru on carbon supports. This is especially true in basic media, achieving electrocatalytic activity comparable to or even outperforming that of Pt/C, as reflected by lower overpotential at 10 mA cm^?2, smaller Tafel slope, larger exchange current density, and higher turnover frequency while maintaining 200 h stable operation. Calculations suggest that ΔG_H* of RuP is much closer to zero than that of metallic Ru, and phosphorous doping is proven to enhance the rate of proton transfer in HER, contributing in part to the improved activity of RuP. The better performance of L‐RP than that of S‐RP is ascribed largely to the stabilization of the P species due to the lowered surface energy of large particles. Furthermore, the relatively low‐cost materials and facile synthesis make L‐RP/C a highly attractive next‐generation HER electrocatalyst.     

Activating Both Basal Plane and Edge Sites of Layered Cobalt Oxides for Boosted Water Oxidation

Layered A_xCoO₂ materials built by stacking layers of CoO₂ slabs and inserting alkali ions in between them have shown a promising activity of oxygen evolution reaction (OER) due to their active edge sites. However, the large basal plane areas of the CoO₂ slabs show too strong adsorption energy to the reaction intermediates, which is unfavorable for the release of O₂. Here, a simple cation-exchange strategy based on Fe³⁺ and alkali ions is proposed to simultaneously activate both the basal plane and edge sites of A_xCoO₂ for the OER. X-ray absorption spectroscopy has revealed that the Fe³⁺ ions deposit both on the surface and edge sites of the CoO₂ slabs and enter the interlayer. The cation-exchanged A_xCoO₂ electrodes show a boosted activity compared to their pristine and conventional Fe-doped A_xCoO₂ counterparts. This phenomenon is mainly ascribed to the abundant edge-sharing Co–Fe motifs at the edge sites and the charge redistribution in the basal plane sites induced by the insertion of Fe³⁺ ions. This work provides a novel method to fully exploit layer-structured materials for efficient energy conversion.     

Molecular Analysis of 14-3-3 Genes in Citrus sinensis and Their Responses to Different Stresses

14-3-3 proteins (14-3-3s) are among the most important phosphorylated molecules playing crucial roles in regulating plant development and defense responses to environmental constraints. No report thus far has documented the gene family of 14-3-3s in Citrus sinensis and their roles in response to stresses. In this study, nine 14-3-3 genes, designated as CitGF14s (CitGF14a through CitGF14i) were identified from the latest C. sinensis genome. Phylogenetic analysis classified them into ε-like and non-ε groups, which were supported by gene structure analysis. The nine CitGF14s were located on five chromosomes, and none had duplication. Publicly available RNA-Seq raw data and microarray databases were mined for 14-3-3 expression profiles in different organs of citrus and in response to biotic and abiotic stresses. RT-qPCR was used for further examining spatial expression patterns of CitGF14s in citrus and their temporal expressions in one-year-old C. sinensis “Xuegan” plants after being exposed to different biotic and abiotic stresses. The nine CitGF14s were expressed in eight different organs with some isoforms displayed tissue-specific expression patterns. Six of the CitGF14s positively responded to citrus canker infection (Xanthomonas axonopodis pv. citri). The CitGF14s showed expressional divergence after phytohormone application and abiotic stress treatments, suggesting that 14-3-3 proteins are ubiquitous regulators in C. sinensis. Using the yeast two-hybrid assay, CitGF14a, b, c, d, g, and h were found to interact with CitGF14i proteins to form a heterodimer, while CitGF14i interacted with itself to form a homodimer. Further analysis of CitGF14s co-expression and potential interactors established a 14-3-3s protein interaction network. The established network identified 14-3-3 genes and several candidate clients which may play an important role in developmental regulation and stress responses in this important fruit crop. This is the first study of 14-3-3s in citrus, and the established network may help further investigation of the roles of 14-3-3s in response to abiotic and biotic constraints.     

Tough hybrid hydrogels based on simultaneous dual in situ sol–gel technique and radical polymerization

A tough hybrid hydrogel has been developed by dual in situ sol–gel reaction of γ-ethacryloxypropyltrimethoxysilane (MPTMS) and tetrabutyl titanate, as well as in situ radical polymerization of acrylamide (AM) and MPTMS. In this hydrogel, covalently bonded SiO₂ and TiO₂ nanoparticles were used as inorganic filler and multifunctional crosslinker. Nano-TiO₂ was bonded onto the surface of SiO₂ by forming Ti O Si bonds and SiO₂ bonded with polymer chains by the formation of C O Si bonds, which were confirmed by Fourier transform infrared and X-ray photoelectron spectroscopy technology. Transmission electron microscopy images revealed that SiO₂ and TiO₂ tended to construct a distinct rod-like structure in poly(AM) matrix. This specific microstructure enhanced the mechanical properties of hydrogel. The compressive stress of the gel reached up to 9.49 MPa, and the compressive fracture energy was as high as 5307.73 J m⁻². This strategy provided a probable method for the preparation of tough soft materials with potential applications in chemical machinery and actuators. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47742.     

低温液相法制备硫化铋纳米材料的研究进展

文章综述了低温液相法制备纳米硫化铋的最新工艺研究进展。从原料选用、制备工艺、设备等多方面对各液相法包括水热(溶剂热)法、回流法、超声法、微波法、模板法等进行了比较和总结,并深入分析了其制备工艺的发展趋势。     

Porous SiC nanowire arrays as stable photocatalyst for water splitting under UV irradiation

In this study, we report the fabrication and photocatalytic properties of the oriented arrays of SiC nanowires on the Si substrate. The SiC nanowire arrays were prepared by carbonizing the Si nanowire arrays with the graphite powder at 1250 °C. The as-prepared SiC nanowires are highly porous, which endows them with a high surface-to-volume ratio. Considering the large surface areas and the high stability, the porous SiC nanowire arrays were used as photocatalyst for water splitting under UV irradiation. It was found that such porous SiC structure exhibited an enhanced and extremely stable photocatalytic performance.