Molecular Weight: Measurements with Gravity Cells

A gravity cell can be used to determine the weights of particles greater than 10(8) molecular weight units. The solution is maintained at a temperature which is constant to +/- 0.001 degrees C until equilibrium between sedimentation produced by gravity is balanced by back diffusion. The weight-average molecular (particle) weight of tipula iridescent virus was (1.05 +/- 0.02) x 10(9).     

Reconstruction of Microraptor and the evolution of iridescent plumage

Iridescent feather colors involved in displays of many extant birds are produced by nanoscale arrays of melanin-containing organelles (melanosomes). Data relevant to the evolution of these colors and the properties of melanosomes involved in their generation have been limited. A data set sampling variables of extant avian melanosomes reveals that those forming most iridescent arrays are distinctly narrow. Quantitative comparison of these data with melanosome imprints densely sampled from a previously unknown specimen of the Early Cretaceous feathered Microraptor predicts that its plumage was predominantly iridescent. The capacity for simple iridescent arrays is thus minimally inferred in paravian dinosaurs. This finding and estimation of Microraptor feathering consistent with an ornamental function for the tail suggest a centrality for signaling in early evolution of plumage and feather color.     

Regional specialization of reptilian scale surfaces: relation of texture and biologic role

The iridescent body scales of the fossorial uropeltid snakes produce these interference colors by keratinous ridges spaced at 2500 A. The pattern inhibits wetting of the surface and adhesion of soil particles and thus reduces friction between the snake's trunk and walls of its tunnel. The epidermal scales of the blunt tail show a sharply defined pattern of spines and ridges with convergent flutings. Dirt caught here forms a plug that protects the snake's caudal end. The sharp transition of surface textures suggests (i) that selection for each of the two roles is great, and (ii) that the interference colors of many fossorial snakes indicate that friction as well as dirt adhesion are being reduced.     

棘胸蛙虹彩病毒免疫方法研究

[目的]研究棘胸蛙虹彩病毒疫苗体表喷雾和肌肉注射的免疫效果,为其免疫方法提供理论依据。[方法]用不同浓度棘胸蛙虹彩病毒灭活疫苗进行体表喷雾免疫和肌肉注射免疫,并进行血清抗体效价检测和相对免疫保护率测定。[结果]注射0.2 m L 1×108TCID50/m L疫苗组21 d血清中和抗体效价最高达到380.2,相对免疫保护率达到80%;体表喷雾1×107TCID50/m L疫苗组,28 d最高抗体效价为320.0,相对免疫保护率为60%。[结论]肌肉注射疫苗和体表喷雾疫苗对棘胸蛙都有较好的免疫效果,肌肉注射疫苗组的免疫效果最佳,但喷雾免疫可作为棘胸蛙快速无损伤免疫的一种有效途径。     

Self-assembly of ordered microporous materials from rod-coil block copolymers

Rod-coil diblock copolymers in a selective solvent for the coil-like polymer self-organize into hollow spherical micelles having diameters of a few micrometers. Long-range, close-packed self-ordering of the micelles produced highly iridescent periodic microporous materials. Solution-cast micellar films consisted of multilayers of hexagonally ordered arrays of spherical holes whose diameter, periodicity, and wall thickness depended on copolymer molecular weight and composition. Addition of fullerenes into the copolymer solutions also regulated the microstructure and optical properties of the microporous films. These results demonstrate the potential of hierarchical self-assembly of macromolecular components for engineering complex two- and three-dimensional periodic and functional mesostructures.     

罗氏沼虾野田村病毒和十足目虹彩病毒1二重荧光定量PCR检测方法的建立及应用

【目的】建立能同时检测罗氏沼虾野田村病毒（MrNV）和十足目虹彩病毒1（DIV1）的二重荧光定量PCR,为罗氏沼虾白尾病（WTD）及虹彩病毒病（DIV1D）的临床诊断和疫情监测提供更简便和高效的检测方法。【方法】分别根据MrNV-CP基因和DIV1-MCP基因的保守序列设计特异性引物和TaqMan-MGB探针,将目的基...     

Extraparticulate chain interaction between different electron transport particles

Interaction or cross-linking between the respiratory chains of the electron transport particles of bacterial origin occurs with a mixture of active and inactive particles. Interaction between bacterial particles and liver sub-mitochondrial particles also occurs. Irradiation of the bacterial particles at 360 nanometers resulted in the destruction of quinone and consequent loss of ability of reduced nicotinamide adenine, dinucleotides to reduce cytochromes b, c(1), c, and a plus a(3). A mixture of both irradiated and untreated particles in the presence of the reduced dinucleotide resulted in the reduction of cytochromes c and a plus a(3), in an amount equivalent to the total concentration of these cytochromes in both types of particles. In contrast, the amount of cytochrome b reduced was equivalent to half the particle concentration or to that observed with the active particles alone. The rate of reduction of cytochromes c and a plus a(3) with the mixture of particles was similar to that with the active particles alone. The interaction or cross-linking between the particulate respiratory chains of bacteria or of bacterial and mammalian systems occurs after cytochrome b and before or at cytochrome c.     

影响刨花对流干燥的因素分析

该文通过对刨花干燥过程中影响因素的研究,以期为刨花干燥工艺的优化设计和过程控制提供理论依据.研究表明,随着气流温度的升高,刨花平均干燥速率增大,单位能耗也相应增加;随着气流速度的提高,刨花平均干燥速率增大,单位能耗逐渐降低;随着刨花初含水率的升高,刨花平均干燥速率加大,单位能耗增加;随着装载量的增大,刨花平均干燥速率大幅减小,单位能耗基本不变,总能耗急剧增加;转筒的运动影响了刨花的干燥,其自转可提高平均干燥速率.实际生产中应根据产量和生产成本,选择合适的干燥条件进行生产.     

颗粒特性对矩形养殖舱中颗粒物去除效果的影响

养殖工船是拓展深远海养殖空间的新途径之一,在船载舱养过程中,如果未消化的饲料残渣和排泄物等颗粒物不能及时排出,则会对鱼类健康及其生长环境产生严重的负面影响。该文章采用FLOW-3D软件进行数值仿真计算,研究了静止状态下30万t级养殖工船养殖舱出水口数目对舱内流场特征的影响,并在此基础上探究不同粒径与密度的颗粒物在舱内的去除效果。结果表明：当总进出水流量与出水口总面积恒定时,出水口数目从1增加到4,V99%从0.244 m/s降低至0.232 m/s,V95%从0.215 m/s降低至0.203 m/s,随着出水口数目的增加,养殖舱内流速减小;以占总量95%的颗粒物排出养殖舱所需时间为评价标准,当颗粒物密度为1050 kg/m3时,粒径为1 mm的颗粒物排出需要约24 min,粒径为0.5 mm的颗粒物排出需要约45 min,粒径为0.1 mm的颗粒物排出需要约78 min,当颗粒物密度相同时,随着粒径增大,其在养殖舱内的停留时间减少;颗粒物粒径为1 mm时,密度为1100 kg/m3的颗粒物排出需要约15 min,密度为1150 kg/m3的颗粒物排出需要约11.6 min,当颗粒物粒径相同时,颗粒物密度越大,其在养殖舱流场内的停留时间越短。该研究形成了CFD数值仿真计算与数理统计有机结合的综合分析方法,为之后具有不同横摇周期和较大横摇幅值的复杂工况提供研究手段及理论依据。     

Particle capture by a pacific brittle star: experimental test of the aerosol suspension feeding model

Ophiopholis aculeata, a suspension feeding brittle star, is capable of removing artificial particles from seawater by some mechanism or mechanisms other than sieving; the animal can capture a finite proportion of particles in all size classes available from at least 30 to 360 micrometers in diameter. A marked shift in the size distribution of particles caught by the animal toward larger particle sizes agrees with predictions derived from aerosol filtration theory. Adhesion of particles to the tube feet is strongly dependent on the presence of fixed charged groups on the surface of the particles.     

海涂围垦区不同土地利用类型土壤颗粒分形特征

土壤颗粒分形特征是表征植被与土壤环境相互作用的重要因子。本研究以江苏沿海条子泥垦区长期撂荒地和水稻田两种土地利用类型为研究样地,探讨了土壤颗粒分形维数及其与土壤粒径分布、土壤理化性质之间的关系。结果表明：海涂围垦区土壤颗粒分形维数在2.16～2.21之间,不同土地利用类型间分形维数存在显著差异,表现为荒地土壤大于稻田土壤,农业垦殖降低了海涂垦区土壤颗粒分形维数。土壤颗粒分形维数与土壤黏粒、细粉砂粒和粗粉砂粒的颗粒含量呈极显著正相关,与极细砂粒、细砂粒和中砂粒的颗粒含量呈极显著负相关。粒径0.05 mm是影响海涂围垦区土壤颗粒分形维数变化的临界粒径。荒地土壤电导率和可溶盐阳离子含量均高于水稻田土壤,水稻种植有利于降低围垦区土壤盐分含量。土壤颗粒分形维数与土壤有机质含量和粒径>0.25 mm水稳性团聚体含量均呈显著正相关关系。土壤颗粒分形维数可以较好地反映土壤理化性质特征及变化过程,可以作为评价海涂围垦区盐渍土发育和演变规律的定量指标之一。     

Colloidal jamming at interfaces: a route to fluid-bicontinuous gels

Colloidal particles or nanoparticles, with equal affinity for two fluids, are known to adsorb irreversibly to the fluid-fluid interface. We present large-scale computer simulations of the demixing of a binary solvent containing such particles. The newly formed interface sequesters the colloidal particles; as the interface coarsens, the particles are forced into close contact by interfacial tension. Coarsening is markedly curtailed, and the jammed colloidal layer seemingly enters a glassy state, creating a multiply connected, solidlike film in three dimensions. The resulting gel contains percolating domains of both fluids, with possible uses as, for example, a microreaction medium.     

Shape and nature of small sedimentary quartz particles

Quartz particles in sediments become flatter with decreasing size; a cleavage mechanism may operate below the critical size of about 100 microns. Flat particles would tend to form a more open packing than spherical particles, and this may contribute to the collapse of loess and similar soils and the sudden loss of strength observed in "sensitive" clay soils.     

VIRUS-LIKE PARTICLES IN BLOOD OF TWO ACUTE LEUKEMIA PATIENTS

A modified negative staining technique suited to demonstrating fragile virus particles in the electron microscope revealed particles having a surrounding membranous sac and an internal filamentous component of a consistent diameter of 75 A in the blood of two patients with acute leukemia. No particles of this type were seen in the blood of four other patients with acute leukemia or in the blood of six normal individuals.     

Oxygen isotopes in refractory stratospheric dust particles: proof of extraterrestrial origin

The oxygen and magnesium isotopic compositions of five individual particles that were collected from the stratosphere and that bear refractory minerals were measured by secondary ion mass spectrometry. Four of the particles exhibit excesses of oxygen-16 similar to those observed in anhydrous mineral phases of carbonaceous chondrites and thus are extraterrestrial. The oxygen and magnesium isotopic abundances of one corundum-rich particle are consistent with a terrestrial origin. Magnesium in the four extraterrestrial particles is isotopically normal. It is unlikely that these particles are derived from carbonaceous chondrites and thus such particles probably represent a new type of collected extraterrestrial material.     

Reactions at interfaces as a source of sulfate formation in sea-salt particles

Understanding the formation of sulfate particles in the troposphere is critical because of their health effects and their direct and indirect effects on radiative forcing, and hence on climate. Laboratory studies of the chemical and physical changes in sodium chloride, the major component of sea-salt particles, show that sodium hydroxide is generated upon reaction of deliquesced sodium chloride particles with gas-phase hydroxide. The increase in alkalinity will lead to an increase in the uptake and oxidation of sulfur dioxide to sulfate in sea-salt particles. This chemistry is missing from current models but is consistent with a number of previously unexplained field study observations.     

磁场中电解质内胶态粒子的电荷分布

为了探求磁处理技术防垢的机理，应用电学与统计力学的理论和数学分析的方法。对电解质内胶态粒子周围的电荷分布进行了研究，计算了磁场对这种电荷分布的影响，给出了在温度较高及稀溶液情况下磁场对胶态粒子周围电荷分布影响的公式。认为电解质内的胶态粒子周围带有一层离子电荷，其厚度取决于温度与离子的浓度。当离子浓度离子大时，离子层变薄，促使胶粒之间发生凝聚；当温度增高时，离子层变厚，阻碍胶粒之间发生凝聚。当电解质     

春小麦病毒病的鉴定——Ⅰ.电镜观察及病细胞超微结构分析

小麦病叶中观察到大小为50～55nm×330～450nm的病毒粒体,粒体大多为弹状,少数为两端削平的杆状;粒体横切面有3层同心环结构;本病毒粒体主要存在于感病细胞的细胞质中及细胞核的周围;在个别细胞的核质中发现无被膜粒体。细胞质中的病毒粒体常聚集成团粒体结构,此结构的外缘有膜状物包围。未成熟的筛管分子中和胞间连丝附近的病毒粒体呈散乱无规则分布。观察到病毒粒体通过胞间连丝运转的状态及粒体运转对胞间连丝的影响,还发现高尔基体囊胞增生现象和粒体在细胞质中的出芽现象。将电镜观察结果同已报道的有关文献进行比较,认为该病毒为北方禾谷花叶病毒(国内称小麦丛矮病毒)(NCMV)。     

土壤环境中粘粒的分散-凝聚行为及其影响因素

本文研究了一般无机离子,重金属离子,表面活性剂和高分子化合物对土壤粘粒分散凝聚行为的影响,以期为土壤环境的保护与管理提供理论依据。结果表明i:)一般无机离子可通过对粘粒表面扩散双电层的压缩作用导致粘粒凝聚,且离子价数越高压缩作用越强i;i)重金属离子在粘粒上的专性吸附,导致其对扩散双电层的压缩作用更强i;ii)阳离子表面活性剂在较低浓度时可形成粒间疏水性表面胶束使粘粒凝聚,而在较高浓度时可形成粒内亲水性表面胶束使粘粒分散i;v)阳离子型高分子化合物在较低浓度时对粘粒的架桥作用可使粘粒凝聚,而在较高浓度时的静电斥力可使粘粒分散;v)随着pH的升高,粘粒由于表面负电荷的增加而趋于分散。以上说明:双电层的压缩、专性吸附、粒间疏水性表面胶束和架桥作用等均可使土壤粘粒凝聚,降低其稳定性。     

Rapid formation of sulfuric acid particles at near-atmospheric conditions

We investigated the formation of new particles in a laboratory study, starting from H2SO4 produced in situ through the reaction of OH radicals with SO2. Newly formed particles were observed for H2SO4 concentrations above 7 x 10(6) per cubic centimeter. At 293 kelvin, a rough estimate yielded a nucleation rate of 0.3 to 0.4 particles per cubic centimeter per second for approximately 10(7) particles per cubic centimeter of H2SO4 (particle size >/= 3 nanometers). These findings are in agreement with observations from the atmosphere. The results demonstrate that under laboratory conditions similar to the atmosphere, particle formation occurs at atmospheric H2SO4 concentration levels.