Potential of a cyclone prototype spacer to improve in vitro dry powder delivery.

PURPOSE: Low inspiratory force in patients with lung disease is associated with poor deagglomeration and high throat deposition when using dry powder inhalers (DPIs). The potential of two reverse flow cyclone prototypes as spacers for commercial carrier-based DPIs was investigated. METHODS: Cyclohaler®, Accuhaler® and Easyhaler® were tested with and without the spacers between 30 and 60 Lmin−1. Deposition of particles in the next generation impactor and within the devices was determined by high performance liquid chromatography. RESULTS: Reduced induction port deposition of the emitted particles from the cyclones was observed due to the high retention of the drug within the spacers (e.g. salbutamol sulphate (SS): 67.89 ± 6.51% at 30 Lmin−1 in Cheng 1). Fine particle fractions of aerosol as emitted from the cyclones were substantially higher than the DPIs alone. Moreover, the aerodynamic diameters of particles emitted from the cyclones were halved compared to the DPIs alone (e.g. SS from the Cyclohaler® at 4 kPa: 1.08 ± 0.05 μm vs. 3.00 ± 0.12 μm, with and without Cheng 2, respectively) and unaltered with increased flow rates. CONCLUSION: This work has shown the potential of employing a cyclone spacer for commercial carrier-based DPIs to improve inhaled drug delivery.

Moisture content in Dall's porpoise (Phocoenoides dalli) tissues: a reference base for conversion factors between dry and wet weight trace element concentrations in cetaceans

Concentration of trace elements measured by dry weight basis has become more commonly used in recent studies on cetaceans than wet weight basis, which was used more in earlier studies. Because few authors present moisture content data in their papers, it is difficult to compare the concentrations of trace elements between various studies. Therefore, we felt that it would be useful if a reference conversion factor (CF) for tissue types could be found to convert between wet weight and dry weight data on trace element concentrations. We determined the moisture contents of 14 tissues of Dall's porpoise (Phocoenoides dalli), and then, calculated the CF values for those tissues. Because the moisture content of each tissue differs from other tissues, it is necessary to use a specific CIF for each tissue rather than a general CF for several tissues. We have also found that CIF values for Dall's porpoise tissues are similar to the same tissues in other cetaceans. Therefore CF values from Dall's porpoise can be reliably used to convert between wet and dry weight concentrations for other cetacean tissues as reference data. (C) 2002 Elsevier Science Ltd. All rights reserved.

Ultra-dry oxygen atmosphere to protect tellurite glass fiber from surface crystallization

In this study we report on surface crystallization phenomena and propose a solution for the fabrication of long and robust tellurite glass fibers. The bulk tellurite glasses of interest were prepared by melting and quenching techniques. Tellurite glass preforms and fibers were fabricated by suction casting and rod-in-tube drawing methods, respectively. The surfaces of the tellurite bulk glass samples and of the drawn fibers prepared under different controlled atmospheres were examined by X-ray diffraction. When the tellurite glass fibers were drawn in ambient air containing water vapor, four primary kinds of small crystals were found to appear on the fiber surface, alpha-TeO(2), gamma-TeO(2), Zn(2)Te(3)O(8) and Na(2)Zn(3)(CO(3))(4)center dot 3H(2)O. A mechanism for this surface crystallization is proposed and a solution described, using an ultra-dry oxygen gas atmosphere to effectively prevent surface crystallization during fiber drawing. (C) 2010 Elsevier B.V. All rights reserved.

黄土高原六盘山生态经济圈功能区规划研究

六盘山区位于黄河中上游,是黄土高原西部天然生态屏障和水源涵养区,在中国生态环境建设中具有重要战略地位。本区土地资源丰富,生态环境洁净,旱作农业潜力大,草畜业兴旺。六盘山生态经济圈规划了4个功能区和7大特色农业基地产业,以六盘山国家自然保护区为中心,加大退耕造林种草与管护力度,到2015年基本修复六盘山区受损的森林生态系统和灌丛草原植被;以旱作农业技术体系为支撑,建立高效可持续发展的生态农业系统和绿色农牧产品基地,为经济社会发展和新农村建设提供良好的生态环境和农业基础。

旱地地膜和秸秆双元覆盖栽培下小麦产量与水分效应

通过覆盖措施提高水分利用率对旱地农业生产具有重要意义。该文采用田间对比试验,研究了旱地冬小麦几种覆盖栽培下产量、水分利用率、土壤水分剖面和硝态氮的分布的差异。结果表明,地膜和秸秆双元覆盖模式下小麦籽粒产量比对照增产12.11%～17.65%,水分利用效率(WUE)比常规栽培提高7.2%～30.8%,土壤0～20 cm土层的含水量提高到12%～16%,硝态氮含量提高到4.70～10.17 mg/kg。地膜和秸秆双元覆盖模式能够显著的提高作物产量和水分利用率,并显著增加耕层土壤中水分含量和硝态氮含量,减轻了土壤剖面硝态氮的淋溶累积。

Photoluminescence characteristics of GaAs/AlGaAs quantum dot arrays fabricated by dry and dry-wet etching

GaAs/AlGaAs quantum dot arrays with different dot sizes made by different fabrication processes were studied in this work. In comparison with the reference quantum well, photoluminescence (PL) spectra from the samples at low temperature have demonstrated that PL peak positions shift to higher energy side due to quantization confinement effects and the blue-shift increases with decreasing dot size, PL linewidths are broadened and intensities are much reduced. It is also found that wet chemical etching after reactive ion etching can improve optical properties of the quantum dot arrays.