Characterization of zirconium oxynitride films obtained by radio frequency magnetron reactive sputtering

Thin ZrN_xO_y films are deposited on Si (100) substrates by radio frequency (RF) reactive magnetron sputtering of a zirconium target in an argon-oxygen-nitrogen mixture. The Φ_N2/Φ_{(Ar + N2 + O2)} ratio was varied in the range 2.5%-100% while the oxygen flux was kept constant. The films were characterized by combining several techniques: X-ray photoelectron spectroscopy, X-ray diffraction and Secondary Ion Mass Spectroscopy. The relationship between structural and compositional properties and the sputtering parameters was investigated. Increasing nitrogen partial pressure in the gas mixture, a chemical and structural evolution happens. At lowest nitrogen flux, ZrN cubic phase is formed with a very small amount of amorphous zirconium oxynitride. At highest nitrogen flux, only crystalline ZrON phases were found. For the films obtained between these two extremes, a co-presence of ZrN and ZrON can be detected. In particular, chemical analysis revealed the co-presence of ZrO₂, ZrN, ZrON and N-rich zirconium nitride which is correlated with the Φ_N2/Φ_{(Ar + N2 + O2)} values. A zirconium nitride crystal structure with metal vacancies model has been considered in order to explain the different chemical environment detected by X-ray photoelectron spectroscopy measurements. The metal vacancies are a consequence of the deposition rate decreasing due to the target poisoning. It's evident that the growth process is strongly influenced by the zirconium atoms flux. This parameter can explain the structural evolution.     

低压配电智能监控终端的设计与实现

阐述了低压配电系统无功补偿的现状和特点,分析了无功补偿方式和低压终端无功补偿的特殊性.介绍了面向该应用对象的基于PIC单片机的配电智能监控终端设计.该配电智能监控终端具有高性能、低价位、高可靠性和配置灵活等特点.     

Hypomagnesemia as a predictor of mortality in hemodialysis patients and the role of proton pump inhibitors: A cross‐sectional, 1‐year,retrospective cohort study

Introduction This study aimed to evaluate the association between proton pump inhibitor (PPI) use and serum magnesium levels, and the role of hypomagnesemia and PPI use as a risk factor for mortality in hemodialysis patients. Methods An observational study, including a cross‐sectional and 1‐year retrospective cohort study. The study comprised 399 hemodialysis patients at a single center, and was conducted from January to September 2014. Multiple linear regression analysis was used to investigate the independent relationship between serum magnesium levels and baseline demographic and clinical variables, including PPI and histamine‐2 receptor antagonist use. Cox regression model was used to identify lower serum magnesium level and PPI as a predictor of 1‐year mortality. Findings Serum magnesium levels were lower with PPI use than non‐PPI use (2.39 ± 0.36 vs. 2.56 ± 0.39 mg/dL, P < 0.001). Multiple linear regression analysis showed that PPI use, low serum albumin levels, and low serum potassium and high‐sensitivity C‐reactive protein (hs‐CRP) levels were significantly associated with low serum magnesium levels. A total of 29 deaths occurred during the follow‐up period. According to Cox regression analysis stratified by hs‐CRP, only high serum hs‐CRP levels (>4.04 mg/L) in association with low serum magnesium levels was an independent risk factor for 1‐year mortality (hazard ratio: 2.92; 95% CI: 1.53–6.40, P < 0.001). Discussion Serum magnesium levels are lower in PPI use. In the inflammatory state, a low serum magnesium level is a significant predictor of mortality in hemodialysis patients.     

熔融制样-X射线荧光光谱法测定锰铁中锰硅磷

锰铁试样以水和硝酸于铂黄坩埚中溶解并蒸干,加入Co元素为Mn元素内标,以四硼酸锂为熔剂、溴化钾为脱模剂,熔融制作玻璃熔片,在X射线荧光光谱仪上测定锰、硅和磷的含量。本法采用少量水浸润试样并滴加硝酸溶解的试样前处理方法,可保证溶解反应温和且不致试样扑溅损失,有效避免了锰铁熔融过程中坩埚腐蚀问题。同时采用大稀释比、内标法减少了基体干扰。对不同生产单位的标准样品进行测定,测定值与认定值相吻合,各元素测定结果的相对标准偏差（n＝11）为0.25%～1.9%。     

Effectiveness of single and coastal superposphates applied either in autumn or spring

Phosphorus (P) is known to leach laterally in water flowing during winter over pasture growing on flat soils that are shallow sands over slowly permeable lateritic ironstone gravel or clay soils in the high rainfall (> 800 mm annual average) areas of south-western Australia. The climate is Mediterranean, with hot dry December to March and cool wet April to November growing season, with excess water flowing over the surface from June to early-August. Fertilizer P is presently applied at about mid-March, near the start of the growing season. Single superphosphate has been applied for many years, which has a good residual value, and so the soils are no longer acutely P deficient. Consequently, a better method may be to apply the fertilizer at mid-August, after waterlogging and P leaching have usually receded, and radiation and temperature are rising, so pasture growth is increasing. The field experiment reported here was on a shallow sand over lateritic ironstone gravel where lateral leaching of P occurs. The experiment compared from 1990 to 1994 the effectiveness of single superphosphate (SSP), the fertilizer used at present, and coastal superphosphate (CSP), a partially acidulated rock phosphate containing about half the total P and one third the water-soluble P initially present in SSP. The fertilizers were applied annually either at mid-March or at mid-August. SSP applied at mid-March was the most effective treatment studied in the years when pasture plants had emerged before fertilizer was applied at mid-March. This is attributed to pasture plants being able to take up P from SSP applied at mid-March before leaching of P occurred, so that relative to SSP applied at mid-March, the other P fertilizer treatments (CSP applied at mid-march and mid-August, SSP applied at mid-August) were about equally or less effective. However, in years when the growing season had yet to start before fertilizer was applied at mid-March, then relative to SSP applied at mid-March, the other fertilizer treatments were equally or more effective. This is attributed to extensive leaching of P from SSP applied at mid-March, so that due to P losses from SSP applied at mid-March, the other treatments were equally or more effective. It is therefore concluded that profitable pasture production with reduced leaching is achieved by applying SSP at mid-March if soils are moist and pasture plants are growing at that time. However, if the soils are dry and no pasture plants are growing at mid-March, then CSP should be applied at mid-August.     

Sn-9Zn-xP无铅焊料合金性能研究

以Sn-9Zn合金为研究对象,考察了P的添加对其性能的影响,并对其机制作了初步探讨。通过二次离子质谱(SIMS)分析发现,P的添加显著降低Sn-9Zn合金中的含氧量,从而提高了合金在Cu上的润湿性。P的改善润湿性的效果不仅有利于其工艺性能,也提高了Sn-9Zn/Cu焊点界面的结合强度,只使其塑性略有下降。同时,微量P的添加不改变Sn-9Zn合金与Cu形成的焊点的界面结构。另外,蠕变强度测试结果表明,P的添加能显著提高合金的抗蠕变性能。     

新型异步电机无速度传感器低速控制算法

基于数学模型的速度估算是异步电机无速度传感器控制的核心。目前,围绕速度估算这个问题,在电机控制领域已出现模型参考自适应、自适应观测器以及扩展卡尔曼滤波等多种方法。无论采用哪种速度估算技术,速度估算系统的动静态性能、低速性能、对参数的敏感性、算法的复杂程度及实现难度都是工程师必须考虑的几个重要性能指标。文中针对低速条件下的异步电机速度估算及控制提出了一种基于无功功率闭环的异步电机无速度传感器矢量控制算法,并探讨了该方法的一些性能指标问题。     

SPS快速烧结制备纳米结构Ti5Si3-TiC复合材料

采用金属钛和碳化硅为初始原料,采用放电等离子体快速烧结(SPS)技术制备了致密纳米结构的Ti5Si3-TiC复合材料.借助XRD、SEM和TEM考察了复合材料的相组成和显微结构,利用压痕法测定了其室温显微硬度和断裂韧性.结果表明利用SPS技术可在1260℃,保温8 min条件下使金属钛和碳化硅同步完成反应、烧结、致密化,生成Ti5Si3-TiC复合材料,并且晶粒细小,其中TiC晶粒尺寸＜200nm.     

Electrochemical Monitoring of Paclitaxel‐Induced ROS Release from Mitochondria inside Single Cells

Mitochondria are believed to be the major source of intracellular reactive oxygen species (ROS). However, in situ, real‐time and quantitative monitoring of ROS release from mitochondria that are present in their cytosolic environment remains a great challenge. In this work, a platinized SiC@C nanowire electrode is placed into a single cell for in situ detection of ROS signals from intracellular mitochondria, and antineoplastic agent (paclitaxel) induced ROS production is successfully recorded. Further investigations indicate that complex IV (cytochrome c oxidase, COX) is the principal site for ROS generation, and significantly more ROS are generated from mitochondria in cancer cells than that from normal cells. This work provides an effective approach to directly monitor intracellular mitochondria by nanowire electrodes, and consequently obtains important physiological evidence on antineoplastic agent‐induced ROS generation, which will be of great benefit for better understanding of chemotherapy at subcellular levels.     

火焰原子吸收光谱法测定高效红磷阻燃剂中痕量铁

用火焰原子吸收光谱法测定高效红磷阻燃剂中痕量铁 ,样品经溴化硝酸溶解 ,干滤后 ,用空气 -乙炔火焰测定 ,结果准确可靠。RSD为 6.2 % ,回收率在 96%～ 10 2 %范围。