佛山市敬老院304例老年人口腔保健知识及行为调查分析

目的调查分析佛山市敬老院老年人口腔保健知识和健康行为,为社区老年人的口腔疾病防治工作提供必要的信息。方法采用问卷调查法,于2013年对佛山市5间敬老院共304名老年人进行口腔自我保健知识及健康行为进行问卷调查。结果 1)口腔卫生习惯:每天早晚刷两次牙的占32.6%,更换牙刷的频率为3个月内定期更换一次仅占11.6%,日常使用过牙线清洁口腔仅占4.6%。2)就医行为:调查的老年人中60.5%对自己的口腔健康不满意,但仅有4.7%的人会定期接受口腔健康检查。3)接受口腔健康信息宣教的途径:不知道或认为所在社区没有进行过关于口腔健康信息宣传的占83.7%。4)对口腔保健知识及常见口腔疾病的防治知识的测试结果普遍较差。结论佛山市敬老院老年人的口腔保健知识贫乏,应加强对老年人口腔健康教育信息的宣传,建立良好的口腔健康行为。     

HBF4溶液中全铅液流电池

报道了一种HBF₄水溶液中的全铅液流电池,正、负电极电解液均采用Pb（BF₄）₂的HBF₄水溶液.在酸性的四氟硼酸铅电解液中考察了石墨电极和玻碳电极作为工作电极的循环伏安性能,石墨电极较适于用作全铅液流电池的正、负电极.采用石墨电极作为电池的正、负电极并在四氟硼酸铅酸性电解液中进行充放电实验,其中Pb（BF₄）₂浓度分别为0.5、1.0和1.5 mol·L^-1,且保持游离的HBF₄浓度为1.0 mol·L^-1.该电池为单液流电池,不需要隔膜分隔正、负极的电解液,电流密度为10、20和40 mA.cm^-2,当限定充电容量为7.0 mAh.cm^-2,放电电压截止到1.0 V时,平均库仑效率大于87%,平均能量效率大于68%;当电解液采用1.0或1.5 mol·L^-1 Pb（BF₄）₂+1.0 mol·L^-1HBF₄水溶液时,在10及20 mA.cm^-2电流下的能量效率最高可超过74%.     

浅析广东省中间产品贸易的优劣势

随着经济全球化和国际生产体系的不断演进，基于产品内国际分工的中间产品贸易迅速发展起来并成为国际贸易的主要方式。本文客观地分析了中间产品贸易产生的现实条件和近年来广东省中间产品贸易的发展，并提出政策建议。     

Effect of oxygen on regulation of properties of moderately boron-doped diamond films

Regulation of oxygen on properties of moderately boron-doped diamond films is fully investigated. Results show that, with adding a small amount of oxygen (oxygen-to-carbon ratio < 5.0%), the crystal quality of diamond is improved, and a suppression effect of residual nitrogen is observed. With increasing ratio of O/C from 2.5% to 20.0%, the hole concentration is firstly increased then reduced. This change of hole concentration is also explained. Moreover, the results of Hall effect measurement with temperatures from 300 K to 825 K show that, with adding a small amount of oxygen, boron and oxygen complex structures (especially B₃O and B₄O) are formed and exhibit as shallow donor in diamond, which results in increase of donor concentration. With further increase of ratio of O/C, the inhibitory behaviors of oxygen on boron leads to decrease of acceptor concentration (the optical emission spectroscopy has shown that it is decreased with ratio of O/C more than 10.0%). This work demonstrates that oxygen-doping induced increasement of the crystalline and surface quality could be restored by the co-doping with oxygen. The technique could achieve boron-doped diamond films with both high quality and acceptable hole concentration, which is applicable to electronic level of usage.     

压力容器焊接中常见缺陷产生成因及防止措施

压力容器焊接是保证压力容器安全运行的关键。本文介绍了压力容器焊接中几种常见缺陷原因并提出防止措施。     

筑路机械铆焊生产过程检验基础

筑路机械铆焊质量是保证整套设备运行可靠性的关键，本文介绍发筑路机械铆焊生产过程检验重点。     

太阳光激发UVC紫外上转换发光材料Y_2SiO_5∶Pr~(3+)的灭菌效果研究

制备了Y_2SiO_5∶Pr~(3+)上转换发光材料,首次实现了太阳光激发下的UVC(220~280 nm)紫外上转换发射。为检测紫外(UVC)上转换发光材料的灭菌效果,从土壤中筛选出铜绿假单胞菌并进行培养。为了便于观察,使用Syto9/PI染色剂对细菌着色。实验结果显示:经过太阳光照射后,附着上转换材料的细菌的死亡率比没有上转换材料的细菌有明显的上升。这说明在太阳光的照射下,上转换材料能够将太阳光转化为紫外线并有效灭菌。     

垃圾填埋场封场与生态恢复设计

以温州市杨府山垃圾填埋场封场与生态恢复设计为例,从封场覆盖、渗沥液收集导排处理、生态恢复和园林造景等方面进行了分析和探讨,以期为同类项目的建设提供借鉴和参考。     

聚氯乙烯下游消费市场现状及前景分析

经过十余年的发展,聚氯乙烯市场已经发展到成熟阶段,达到供需平衡。但是,对比国外成熟的聚氯乙烯生产及消费市场看,中国的聚氯乙烯行业距离真正的平衡、稳定结论为时尚早,聚氯乙烯下游市场仍然存在巨大的潜力和机遇。     

Origin,characteristics, and suppression of residual nitrogen in MPCVD diamond growth reactor

Unintentional nitrogen incorporation has been observed in a set of microwave plasma chemical vapor deposition (MPCVD)-grown samples. No abnormality has been detected on the apparatus especially the base pressure and feeding gas purity. By a comprehensive investigation including the analysis of the plasma composition, we found that a minor leakage of the system could be significantly magnified by the thermal effect, resulting in a considerable residual nitrogen in the diamond material. Moreover, the doping mechanism of leaked air is different to pure nitrogen doping. The dosage of several ppm of pure nitrogen can lead to efficient nitrogen incorporation in diamond, while at least thousands ppm of leaked air is required for detecting obvious residual nitrogen. The difference of the dosage has been ascribed to the suppression effect of oxygen that consumes nitrogen. As the unintentional impurity is basically detrimental to the controllable fabrication of diamond for electronic application, we have provided an effective way to suppress the residual nitrogen in a slightly leaked system by modifying the susceptor geometry. This study indicates that even if a normal base pressure can be reached, the nitrogen residing in the chamber can be "activated" by the thermal effect and thus be incorporated in diamond material grown by a MPCVD reactor.