Deposition and dispersion of 1-micrometer aerosol boluses in the human lung: effect of micro- and hypergravity

We performed bolus inhalations of 1-micrometer particles in four subjects on the ground (1 G) and during parabolic flights both in microgravity (microG) and in approximately 1.6 G. Boluses of approximately 70 ml were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 200 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The deposition, dispersion, and position of the bolus in the expired gas were calculated from these data. For Vp >/=400 ml, both deposition and dispersion increased with Vp and were strongly gravity dependent, with the greatest deposition and dispersion occurring for the largest G level. At Vp = 800 ml, deposition and dispersion increased from 33.9% and 319 ml in microG to 56.9% and 573 ml at approximately 1.6 G, respectively (P < 0.05). At each G level, the bolus was expired at a smaller volume than Vp, and this volume became smaller with increasing Vp. Although dispersion was lower in microG than in 1 G and approximately 1.6 G, it still increased steadily with increasing Vp, showing that nongravitational ventilatory inhomogeneity is partly responsible for dispersion in the human lung.     

Effect of lung function and mode of inhalation on penetration of aerosol into the human lung

The method using radioactive tracer particles has been applied to study the effect of the mode of inhalation of aerosols on the depth of deposition in the lungs of 50 patients with airways obstruction. The findings show that the penetration of particles is directly related to: (1) volume inspired per breath (VI); (2) forced expiratory volume in one second (FEV1); and inversely related to (3) flow rate during inhalation (V). In mathematical terms, alveolar deposition (%) = 40-3 (VI)+10-98 (FEV1)--0-75 (V)+40-4; for this regression F = 4-41 and P less than 0-01.     

Substituting Effect of Y in La0.5Ba0.5 CoO3

La0.5-xYxBa0.5CoO3 polycrystals were prepared by solid state reaction. The substituting effects of Y for La on the magnetic and transport properties of the materials were studied systematically. The results indicate that substitution of Y induces two effects. Firstly, the charge transfer from Y to 3d orbital of Co happens. This causes the molecular magnetic moment to decrease. Secondly, the antiferromagnetic exchange interaction of Co ions appears. When the content of Y is less than or equal to 30%, the non-colinear structure of spins in materials is observed. When the content of Y is greater than 30%, the materials transit from predominant ferromagnetic state to predominant antiferromagnetic one. The conductive mechanism for the materials with different content of Y belongs to the variable range hopping conduction of polarons.The resistivity of materials increases sharply with increasing Y content.     

Effects of long-term hypergravity on muscle, heart and lung structure of mice

Quantitative changes in lung, heart and muscle structure were assessed in mice exposed for 14 weeks to a gravitational field of 3 G since the age of 4 weeks; matched controls were kept at normal gravity (1 G). The body mass of 3-G-exposed mice was significantly reduced by 9%, while total skeletal muscle mass remained the same fraction of body mass. The mass of the soleus muscle was found to be significantly larger in 3-G-exposed mice both in absolute (+27%) and body mass specific terms (+42%). Capillary density was significantly reduced by 22% because of a relatively larger increase of fiber cross-sectional area (+47%) than of capillary to fiber ratio (+16%). Other morphometric variables remained unchanged with hypergravity. Heart mass and mitochondrial volume were both larger in 3-G-exposed mice (+15% and +27%, respectively). This difference reached statistical significance when normalized to body mass. The only significant difference in lung structure detectable by morphometric methods were a smaller volume (-9%), that paralleled lower body mass, and thinner alveolar septa (-12%). From these results it is concluded that the lung's support structures in mice are sufficiently strong to withstand the stress of long-term hypergravity; however, 3-G exposure leads to a selective hypertrophy of soleus muscle fibers while absolute capillary length in this muscle remains unaltered.     

热处理工艺对ZQAl10-4-0.5合金组织与性能的影响

研究了不同热处理工艺对ZQAl10-4-0.5合金的组织和性能的影响,结果表明,该合金通过800℃正火后,370°～400℃回火可以得到细小的α、γ_2相呈细小颗粒状分布的(α+γ_2)共析体和δ_(Fe)相组成的组织,使合金既具有较高的强度(特别是压缩强度)、硬度,同时又具有足够的塑性、韧性和导电率,且具有较佳的机械性能和导电率的配合。     

Effect of simulated microgravity on vascular contractility

Microgravity was simulated in Sprague-Dawley (SD) and Wistar (W) rats by using a tail harness to elevate the hindquarters, producing hindlimb unweighting (HU). After 20 days of HU treatment, blood vessels from both HU and control rats were cut into 3-mm rings and mounted in tissue baths for the measurement of isometric contraction. HU treatment decreased the contractile response to 68 mM K+ in abdominal aorta from W rats. HU treatment also decreased the contraction to 68 mM K+ in carotid arteries from both rat strains and in femoral arteries from W but not SD rats. HU treatment reduced the maximal response to norepinephrine in all arteries except the femoral from SD rats. HU treatment reduced the maximal response of jugular vein from W rats to 68 mM K+ but had no effect on that response in femoral vein from either rat strain. HU treatment also had no significant effect on the maximal response to norepinephrine in veins. These results demonstrate that HU treatment caused a nearly universal reduction of contractility in arteries, but generally had no effect in veins.     

On-line laser-photometric monitoring of aerosol deposition in ventilated rabbit lungs

A photometric technique was developed for on-line measurement of aerosol deposition in isolated, ventilated, and perfused rabbit lungs. A jet nebulizer was used for aerosolization of saline (hygroscopic particles) and di(2-ethylhexyl) sebacate (nonhygroscopic particles). Aerosol concentration (laser photometer, constructed for measurements in rabbit lungs) and flow rate (commercial pneumotachograph) were continuously monitored at the inlet of the tracheal cannula. Computer-assisted data processing allowed the breath-by-breath calculation of inhaled and exhaled aerosol mass, thus providing the deposition fraction. With the use of hygroscopic particles, however, this approach was hampered by the humidity-induced particle growth in the airways, leading to an overestimation of the aerosol concentration in exhaled air. This effect was corrected by an algorithm using a "particle growth factor" derived breath by breath from the photometer signal. To test the reliability of this approach, saline particles carrying technetium-99m label were aerosolized into rabbit lungs with the use of various ventilator settings, and the aerosol deposition was assessed in parallel by photometry and by radioactivity detection over the lung and over a trap in the exhaled-air circuit. Superimposable curves of cumulative aerosol deposition, with changes in kinetics dependent on the ventilator mode, were obtained. For a given ventilator setting, absolute values of the deposition fraction were 0.32 +/- 0.04 (radiotracer quantification) and 0.36 +/- 0.04 (photometry; means +/- SD; n = 4). We conclude that the presented laser-photometric technique allows reliable on-line monitoring of the deposition of both nonhygroscopic and hygroscopic aerosol particles in ventilated lungs.     

0.5Li3VO4-0.5Li4TiO4的溶胶-凝胶法合成及其离子导电性

用非醇盐溶胶凝胶法合成了组成和粒度均匀的锂离子导体０．５Ｌｉ３ＶＯ４０．５Ｌｉ４ＴｉＯ４超细粒子。用Ｘ射线衍射、ＴＥＭ及交流阻抗等方法对产物进行了表征。产物中两相的相纯度各为５０％,粒径在０３μｍ以下,室温下的离子电导率为７１０×１０－６ｓ·ｃｍ－１。     

La0.5Sr0.5CoO3晶体微结构振动形态的模拟计算

采用离子束溅射法制备了钙钛矿型复合氧化物La0.5Sr0.5CoO3(LSCO) 薄膜,测试了La0.5Sr0.5CoO3(LSCO) 薄膜的拉曼光谱,采用Gaussian 03W量子化学软件从头计算了这种晶体的拉曼光谱.实验和计算均表明,钙钛矿晶体LSCO的基本结构单元为钴氧八面体,钴氧八面体的振动频率与其振动模式密切相关;并给出了拉曼谱峰的振动频率与振动方式之间的对应关系;通过改变Co-O键长值,对CoO6八面体振动方式和频率进行计算拟合,研究了热处理温度和衬底对晶胞化学键长度变化的影响.     

离子束溅射法制备La0.5Sr0.5CoO3薄膜的拉曼光谱分析

采用离子束溅射在氧化钇稳定的氧化锆(YSZ)和铝酸镧(LaAlO3)上制备了La0.5Sr0.5CoO3的钙钛矿薄膜.利用拉曼光谱,研究了不同热处理温度和不同衬底对LSCO薄膜材料的晶体结构、分子振动模式和化学键的影响.研究发现La0.5Sr0.5CoO3钙钛矿薄膜的晶体结构随着热处理温度的升高发生明显的相变,由排列无规则态朝着正交晶系结构转变,Co-O键构成的八面体间的相对运动强度逐渐减弱.另外,还发现La0.5Sr0.5CoO3钙钛矿薄膜在衬底氧化锫(YSZ)上的Co-O键振动频率要小于在衬底铝酸镧(LaAlO3)上的振动频率,这与两者的品格失配程度有关.     

稀土对HAl62-3-3-0.7合金组织和性能的影响

通过对合金成分的调整分别配制了添加不同量稀土元素的试验用HAl62-3-3-0．7合金。借助金相与扫描电镜观察和分析了各合金的显微组织结构,运用模拟设备测试了各合金的力学性能。文章阐述了稀土元素对该类高强度耐磨黄铜的组织和性能的影响,试验表明适量加入稀土会显著细化晶粒,过量的稀土会导致在合金显微组织中形成线形富稀土相。随着合金中稀土含量的增加,合金的硬度升高,但当稀土含量超过0．1％时,由于线形富稀土相的形成,反而会使合金的力学性能下降。     

BaTiO3-Bi0．5Na0.5TiO3系铁电陶瓷的晶相特征及性能研究

采用X射线粉晶衍射分析及透射电镜选区电子衍射分析技术等手段,研究了(1-x)BaTiO3-x Bi0.5 Na0.5 TiO3(x≤0.4)固溶体陶瓷的晶相组成及晶体结构特征,并对陶瓷性能特征进行了讨论.研究表明,固溶体的晶体结构受BNT含量的显著影响.X射线衍射分析表明,经1250 ℃烧结2 h的陶瓷形成了钙钛矿结构固溶体.选区电子衍射分析表明,该固溶体并非单一晶相,其晶相类型包括四方相和立方相,并存在局部结构畸变现象.陶瓷的相变温度随BNT含量的增高而变化,居里温度增高,次级相变向低温移动,并最终消失.当BNT含量为20%～40%(摩尔分数)时,陶瓷具有较好的铁电性,其居里温度为146～182 ℃,介电损耗为0.030～0.042,并在-60～110 ℃以上较宽的范围内具有良好的介电稳定性.     

Effect of metal doping into Ce0.5Zr0.5O2 on catalytic activity of MnOx/Ce0.5-xZr0.5-xM0.2xOy/Al2O3 for benzene combustion

The research investigated the effect of doping two metals separately or together into Ce0.5Zr0.5O2 on the catalytic activity of MnOx/Ce0.5–xZr0.5–xM0.2xOy/Al2O3 (M=Y, Mn, Y and Mn) for catalytic combustion of benzene. The prepared catalysts were characterized by X-ray diffraction (XRD), surface area analysis, oxygen storage capacity (OSC), and H2-temperature programmed reduction (H2-TPR). Cata-lytic test was performed on a conventional fixed bed flow reactor. The characterization results revealed that Y and Mn ions entered into the ceria-zirconia mixed oxides framework, which improved the textural properties and greatly promoted the MnOx dispersion on the support surface. The complete conversion temperature of benzene on MnOx/Ce0.4Zr0.4Y0.1Mn0.1Oy /Al2O3 was 563 K, and the selectivity of carbon dioxides was 99%. This catalyst could be applied in a wide range of GHSV and wide concentration condition, showing great potential for application.     

微量Nd和Sc对A1-6．5Mg-0．5Mn合金组织及力学性能的影响

采用拉伸力学性能测试、扫描电镜及透射电镜观察等手段研究了微量Nd和Sc对Al-6．5Mg-0．5Mn合金的显微组织及力学性能的影响。结果表明：分别单独添加Nd,Sc使合金的抗拉强度均有所提高;同时添加Nd和Sc可使合金的抗拉强度、屈服强度分别提高65MPa、55MPa,但合金的伸长率有所降低;合金中晶界上形成含Nd或Sc的化合物,这些化合物钉扎亚晶界、从而抑制合金的再结晶晶粒的形成。     

Morphology of the Tin Whiskers on the Surface of a Sn-3Ag-0.5Cu-0.5Nd Alloy

Rapid growth of tin whiskers has been observed on the surface of rosette-shaped NdSn₃ intermetallic phase in a Sn-3Ag-0.5Cu-0.5Nd alloy after air storage. It is shown that various cross sections of NdSn₃ rosettes in the solder matrix reveal different morphologies of tin whiskers, which can be classified as four types: long fibers, short fibers, tiny sprouts, and hillocks. The fibrous whiskers and tiny sprouts are found on the surfaces of specimens exposed to air at room temperature and 423 K (150 °C), while hillocks appear only after storage at 423 K (150 °C). In addition, it is observed that, in most cases, each oxidized NdSn₃ intermetallic phase contains only a single whisker at its center. Through metallographic observations and chemical analyses on the cross sections of the oxidized NdSn₃ intermetallics, a “successive compressive stress model” has been proposed to interpret the tin whisker growth on the surface of a rare earth (RE)–containing solder.