化肥厂周边地区植物叶片中氟的积累

采集了吉林市某化肥厂周边的植物叶片样品,对叶片中的氟化物进行测定,以评价其周围空气环境中氟化物的污染状况.实验结果表明,在距化肥厂500 m内,随着距离的增加,植物叶片样品中氟含量明显减小,并呈良好的线性关系.而在1 000 m左右时,氟含量与500 m处相近,周边环境影响因素比较复杂.     

一类支持向量机在烟叶选择中的应用

为解决卷烟叶组配方中的烟叶替换问题,提出了基于一类支持向量机的烟叶选择方法。介绍了烟叶选择支持向量机建模的原理,分析了影响模型准确性的主要因素,提出了特征选择与支持向量机参数的联合优化策略。应用实例表明,该方法能够根据烟叶中的化学成分的测量值来确定烟叶的相似性,为实现烟叶的智能化选择打下了基础。     

竹原纤维纺织工艺探讨

文章介绍了竹原纤维的特性,阐述了竹原纤维在纺纱织造生产中应注意的一些问题。     

竹材密实化及其物理力学性能研究

采用平压-热压法对毛竹材进行压缩密实试验,探讨竹材的压缩率与密度、密度与静曲强度及弹性模量、热压温度与静曲强度及弹性模量相互之间的关系。     

An investigation on the impact fatigue characteristics of valve leaves for small hermetic reciprocating compressors in a new automated test system

This paper presents an investigation on the impact fatigue characteristics of valve leaves that are prevalently used in hermetic reciprocating compressors especially for the household type refrigerators. A unique automated impact fatigue test system has been designed and produced, which enables to carry out impact fatigue tests of the compressor valve leaves under the desired impact velocities. The test system incorporates a noncontact actuation, a data acquisition system and an acoustic‐based damage detection technique, which continuously monitors the health of the structure. The damage detection system allows parametrical investigation on the impact fatigue life by detecting any possible damage and automatically terminating the test. The investigation relates the impact fatigue lifetime of the valve leaves with the impact velocity, asymmetrical impact, operation temperature, material type (carbon strip steel, stainless strip steel and new stainless strip steel grade) and tumbling operation duration. The observations show that the cracks have initiated from the edges of the valve leaf where is in contact with the valve plate. Subsequently, the cracks initially have propagated in the radial direction inwards the center of the impact area. Various failure cases have been resulted in by either a single crack or inter‐related multiple cracks. Microscopic and metallographic observations have been performed on the specimens to enhance the understanding of the damage mechanisms. The investigation and introduced test system guide the design optimization of the valve leaves in terms of compressor performance due to the energy consumption and lifetime of the valve leaf.     

Assessment of Intestinal Absorption of Vitexin-2″-O-Rhamnoside in Hawthorn Leaves Flavonoids in Rat Using In Situ and In Vitro Absorption Models

The purpose of this study was to investigate the absorption mechanism of vitexin-2″-O-rhamnoside, the index component in hawthorn leaves flavonoids (HLF) in the rat intestine, using two different absorption models, the in situ single-pass intestinal perfusion and the in vitro everted gut sac model. The effective permeability coefficients (P_eff) in the in situ single-pass intestinal perfusion experiments and the apparent permeability coefficients (P_app) in the in vitro everted gut sac experiments were calculated. Furthermore, the influences of the P-glycoprotein inhibitors, verapamil and digoxin, on the intestinal absorption of vitexin-2″-O- rhamnoside in HLF were studied using the above-mentioned two models. Results showed that there were no significant differences in the absorption of vitexin-2″-O-rhamnoside in HLF in four segments of the rat intestine, duodenum, jejunum, ileum, and colon, and at different concentrations of HLF ranging from 0.05 mg/ml to 0.5 mg/ml (P > 0.05). The P_eff values for vitexin-2″-O-rhamnoside in the rat jejunal perfusion at the concentration of 0.05, 0.1, 0.25, and 0.5 mg/ml were (2.48 ± 0.33) × 10^?5; (2.23 ± 0.67) × 10^?5; (2.18 ± 0.48) × 10^?5; and (2.25 ± 0.17) × 10^?5 cm/s, respectively. But there was significant difference between absence and presence of verapamil or digoxin (P < 0.05). P_eff and P_app values of vitexin-2″-O-rhamnoside in HLF were increased in the presence of verapamil or digoxin. In conclusion, vitexin-2″-O-rhamnoside can be classified into high permeability class drug according to the biopharmaceutical classification system. Passive diffusion dominates the absorptive transport behavior of vitexin-2″-O-rhamnoside in HLF. The absorption and secretion are mediated by the efflux transport system, P-gp. The absorption of vitexin-2″-O-rhamnoside in HLF can be enhanced administered together with P-gp inhibitors.     

我国竹工机械区域布局及未来走势分析

介绍了我国竹工机械的内涵及分类方法,回顾了我国竹工机械的发展历史,从产业规模、产业布局方面阐述了我国竹工机械的现状;从国内需求、产品结构和技术发展方向三方面对我国竹工机械的发展趋势进行了预测,同时还指出了我国竹工机械存在的问题,并提出政策建议。     

Improving thermo‐oxidative degradation resistance of bamboo fiber reinforced polymer composites with antioxidants. Part II: Effect on other select properties

The first of this two‐article study showed that the addition of antioxidants can significantly improve the thermo‐oxidative resistance of bamboo fiber reinforced polypropylene composites (BFPCs). In this article, the effect of antioxidants on water absorption, thermal stability, crystallinity, and the dynamic mechanical properties of the composites were investigated. The results showed that the addition of antioxidants resulted in a slight increase in water absorption, but this increase can be reduced by controlling the ratio of the primary and secondary antioxidants. The glass transition temperature (T_g) of composites also slightly increased. However, the effects of antioxidants on the crystallinity as well as other thermal properties of BFPCs were small or even insignificant. The different combinations, ratios, and the adding amounts of antioxidants show tiny differences for all these properties. As a whole, the addition of minor antioxidants in the bamboo fiber (BF) polymer composites will not produce obvious negative effects on their overall performances. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44199.     

Improving thermo‐oxidative degradation resistance of bamboo fiber reinforced polypropylene composite with antioxidants. Part I: Screening of antioxidants

In this study, the effect of antioxidant application (applied in different combinations, ratios and contents) on the thermo‐oxidative degradation resistance of bamboo fiber polypropylene composites (BFPCs) were investigated, with oxidative induction time (OIT), weight loss, surface color, and flexural mechanical properties as the main indicators for evaluation. The results showed the addition of antioxidants could greatly increase the OIT and reduce the weight loss and color change of the composites after 900 h of thermal weathering. Meanwhile, the flexural mechanical properties were little affected or even slightly improved. The combination of 1076 and DLTP antioxidants at a ratio of 2:1 and 0.2 wt % content was found to exhibit the best thermal oxidation resistance with respect to the OIT, mechanical properties and cost. Our study indicate that the OIT can serve as a simple and quick indicator for the evaluation of thermo‐oxidative resistance of BFPC. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44198.     

重组竹在长期荷载作用下的蠕变行为

通过长期荷载作用下的拉伸与压缩蠕变试验,研究了重组竹在不同应力水平下的蠕变行为特点及变化规律.分别釆用Burgers模型和Findley幂律模型对重组竹在长期荷载作用下的蠕变曲线进行拟合,确定了重组竹蠕变模型,分析了Burgers模型和Findley幂律模型的相关系数及变化规律.结果表明:在不同应力水平下,重组竹蠕变应变-时间曲线均呈现出相似的变化趋势,均包含瞬态蠕变和稳态蠕变阶段;采用Burgers模型和Findley幂律模型都能很好地模拟重组竹的蠕变性能;瞬间弹性形变、延迟弹性形变和黏性流动形变均随应力水平的增加而增大.高应力水平下的蠕变可导致重组竹构件破坏,在设计时应合理地控制应力水平.