Release of particles containing metals from vegetation into the atmosphere

Studies with radioisotopes indicate that in the laboratory pea plants and pine tree seedlings release zinc and lead into the atmosphere. Field studies carried out on radiolabeled plots vegetated with a variety of grasses and small herbaceous plants also show that these elements are released into the atmosphere. The metals, associated with particles of various sizes, are released from the plant surfaces, and the loss mechanism is influenced by growth conditions, the concentrations of the elements in the leaves, and meteorological factors. For plants whose leaves have about equal concentrations of zinc and lead, the amount of zinc released is usually two orders of magnitude greater than the amount of lead. The significance of the process is discussed in terms of the overall trace metal composition of atmospheric particulates.     

Efficient incorporation of human CD4 protein into avian leukosis virus particles

Virus envelope (Env) proteins are thought to contain specific signals for selective uptake by virus particles. In the course of attempting to define these signals by testing virus incorporation of CD4-Env chimeric proteins, normal human CD4 was found to be efficiently and selectively assembled into avian leukosis virus particles in quail cells. Viruses bearing CD4 at their surface may be useful reagents in the design of retrovirus-mediated gene therapy for the acquired immune deficiency syndrome.     

Halite particles injected into the stratosphere by the 1982 el chichon eruption

Halite particles about 2 micrometers in size were collected by a quartz crystal microbalance cascade impactor from the El Chichón eruption cloud in the lower stratosphere during April and May 1982. These particles are probably derived from the erupted chloride-rich, alkalic magma. Enrichments of hydrogen chloride and increases in optical depolarization in the eruption cloud observed by lidar measurements may reflect the influence of the halite particles. There is evidence that the halite particles reacted with sulfuric acid after about 1 month, releasing gaseous hydrogen chloride, which can influence the catalytic destruction of ozone in the stratosphere.     

冬小麦对过量钼胁迫的代谢响应与耐钼机制

以正常钼与过量钼水平水培种植的冬小麦为试验材料,通过分析过量钼供给下小麦亚细胞组分钼含量及叶片代谢物的变化来探究冬小麦耐受过量钼的生理机制.结果显示,在过量钼水平下,根系亚细胞组分细胞壁、可溶性部分、细胞器、原生质体/叶绿体钼含量分别是地上部的219、38、25和62倍;根部和地上部的可溶性部分中钼的积累比例分别为71...     

Heat capacity of superconducting ternary molybdenum sulfides

The heat capacities of AgMo(4)S(5), PbMo(6)S(7), and SnMo(5)S(6) are reported. These ternary molybdenum sulfides have been found to be bulk superconductors with very large values of electronic heat capacity coefficients and very low values of Debye temperatures.     

钼肥在花生生产中的增产效果试验

为了探索化肥减量增效,使花生产量再创新高,验证微量元素钼肥在花生上的应用效果及适宜用量,通过小区田间试验在施用等量化肥的基础上对2、3、4、5处理施用不同量的钼肥,分别在花生初花期和盛花期各喷施50%,对照处理为1,测定各处理花生的主茎高、侧枝长、总分枝数、结果枝数、单株果数、百仁重、出仁率和产量。结果表明,喷施不同量的钼肥能增加主茎高、侧枝长、总分枝数、结果枝数、单株果数、百仁重、出仁率,改善了成产因素,从而提高了产量。最佳经济用量为1.50 kg/hm~2。     

钼对甘蔗氮代谢的影响

本试验选用巴西固氮甘蔗品种B 1和B 8为供试材料,在温室条件下桶栽砂培甘蔗施以含不同钼水平的营养液(0m g/L、0.01m g/L、0.02m g/L、0.04m g/L),在不同时期测定甘蔗叶片中硝酸还原酶、G S酶活性及硝态氮、氨态氮含量。试验结果表明,在大棚含氮条件下,三个钼处理都提高了两个甘蔗品种的硝酸还原酶活性而降低了硝态氮含量。0.01m g/L钼处理在拔节期后提高了B 1叶片的G S酶活性,而在幼苗期提高了B 8叶片的G S酶活性,降低了氨态氮含量,促进了氮代谢。在大棚无氮条件下,三个钼处理在拔节期后都提高了两个甘蔗品种的NR酶活性,降低硝态氮含量;提高了B 1的G S酶活性,降低氨态氮含量;在分蘖期也提高了B 8叶片的G S酶活性而降低了其氨态氮含量。因而在大棚里,无论是含氮或无氮条件下,在不同时期不同钼处理对甘蔗氮代谢和氨同化过程的作用也不同,但是相对以较低水平钼处理较能提高两个甘蔗品种的硝酸还原酶活性而降低硝态氮含量;提高了B 1与B 8的G S酶活性,降低氨态氮含量,促进了甘蔗的氮代谢和氨同化。     

钼对甘蔗光合生理特性的影响

选用巴西固氮甘蔗品种B1和B8为材料,在温室条件下对桶栽砂培甘蔗施以含不同钼水平的营养液,以了解钼对甘蔗光合生理特性的效应。结果表明,在含氮条件下,0.01mg/L钼处理能较明显提高B1叶片叶绿素a含量,而0.02mg/L钼处理则提高B8叶片叶绿素a含量;0.04mg/L钼处理对B1叶片净光合速率的促进效应较明显,而0.01、0.02mg/L钼处理对B8叶片净光合速率的促进效应较明显;0.01mg/L处理较明显地提高了B1叶片中的可溶性糖含量,但所有钼处理几乎都降低了B8叶片可溶性糖含量。因此,总体上,相对以较低水平的钼处理较能提高两个甘蔗品种叶片叶绿素含量、净光合速率、可溶性糖,促进了甘蔗的光合作用,有利于甘蔗固氮作用的进行。     

电感耦合等离子体光谱法测定豆科作物中钼含量

豆科作物样品经干灰化法处理,用ICP-AES法测定试液中痕量钼。试验中着重研究了共存元素对钼的干扰及消除。钼的样品检测限为0.82　μg.g-1,相对标准偏差RSD 2.1%(n=8),加标回收率为93.0%～98.6%。该方法已应用于百余个豆科作物的叶、茎、根、种子、植株样品的分析。     

The codon-optimized capsid gene of duck circovirus can be highly expressed in yeast and self-assemble into virus-like particles

The capsid(Cap) protein, which is the only structural protein of duck circovirus(DuCV), is the most important antigen for the development of vaccines against DuCV and the virus' s serological diagnostic methods. In order to use yeast expression system to produce a large quantities of DuCV Cap protein which is close to its natural form to display the antigen peptides perfectly, the Cap gene was optimized into the codon-optimized capsid(Opt-Cap) gene towards the preference of yeast firstly. Then, the genes of Cap and Opt-Cap were separately cloned into pPIC9K plasmid and transformed into Picha pastoris GS115. The strains that displayed the phenotype of Mut~+ and contained multiple inserts of expression cassette were selected from those colonies. After the induction expression, the secretory type of Cap protein, which was about 43 kDa, was best expressed under 0.5%(v/v) methanol and sorbitol induction. Compared with the Cap gene, the expression level of Opt-Cap gene was much higher. What's more, the purified Cap protein had a good reactivity to its specific polyclone antibody and DuCV-positive serum, and it was able to self-assemble into virus-like particles(VLPs). These VLPs, with a diameter of 15–20 nm and without a nucleic acid structure, showed a high level of similarity to DuCV particles in size and shape. All of the results demonstrated that, based on the codon-optimization, it is suitable to use the P. pastoris expression system to produce DuCV VLPs on a large scale. It is the first time that a large amounts of DuCV VLPs were produced successfully in P. pastoris, which might be particularly useful for the further studies of serological diagnosis and vaccines of DuCV.     

Edge surfaces in lithographically textured molybdenum disulfide

Lithographic techniques were used to expose edge surfaces in layered molybdenum disulfide single crystals. This microstructuring produced ideal samples for the study of the surface morphology and electronic structure of this catalytically important material. The optical absorption that was measured at mid-gap increased by two orders of magnitude after texturing. This increase resulted from reduced molybdenum at surface defects that are located on edge planes, as shown by photoemission spectroscopy. This information cannot easily be obtained on conventional crystals with predominantly basal plane surfaces.     

不同钼水平对七子花生理特性的影响

以七子花为研究材料,设置了7个不同的钼(Mo)水(0,0.000 5,0.005,0.05,0.5,5,50mg/kg),研究钼对七子花光合速率、呼吸速率、质膜透性、过氧化物酶、过氧化氢酶、抗坏血酸过氧化物酶等生理特性的影响.结果表明:七子花在Mo浓度为0.5mg/kg时,叶片的光合速率最大,呼吸速率最强,叶片的质膜透性最低,过氧化物酶、过氧化氢和抗坏血酸过氧化物酶的活性最高,表明该浓度较适宜七子花生长.低钼水平或高钼水平都不利于七子花的生长.     

钼提高植物抗逆性研究进展

钼（Mo）作为植物必需的微量元素,在促进植物生长发育和增强植物抗逆性方面发挥着关键作用。植物对钼的吸收转运主要受到钼酸盐转运蛋白基因MOT1和MOT2调控,钼进入植物体内以含钼酶形式参与植物生长代谢,其中对植物抗逆性方面的调控主要表现为：钼通过含钼酶硝酸还原酶、醛氧化酶、黄嘌呤脱氢酶影响植物体内的光合碳氮代谢、激素合成和活性氧代谢进而调控植物抗寒性;钼通过硝酸还原酶和醛氧化酶介导的信号转导过程调控根系发育、养分水分利用及抗旱基因表达,进一步影响脂质合成与代谢调控植物抗旱性;最新研究还发现钼在植物适应盐胁迫、缓解重金属胁迫方面也具有重要作用。这些研究结果为通过钼营养调控提升植物的抗逆性提供了新思路。     

Detection of relativistic particles

It appears possible to extend the application of most of the existing detection techniques to the identification and separation of charged particles in the relativistic energy region.One can probably extend these applications, in certain limited cases, up to an energy region of several hundred billion electron volts. However, for general applications in the identification of particles in the ultrarelativistic region, the existing detectors are rather limited, and new methods and approaches are desirable. At present, detectors making use of the relativistic rise effect seem to show considerable promise.     

Two-dimensional magnetic particles

Single two-dimensional (2D) atomically thick magnetic particles of cobalt and iron with variable size and shape were fabricated by combining a mask technique with standard molecular beam epitaxy. Reduction of the lateral size of in-plane magnetized 2D cobalt films down to about 100 nanometers did not essentially modify their magnetic properties; although the separation of boundaries decreased greatly, neither domain penetrated the particle, nor was any sizable shape anisotropy observed. The mutual interaction of 2D cobalt particles was negligible, and the magnetic state of a single particle could be switched without modifying the state of the neighbors. Perpendicularly magnetized iron particles did not exhibit such responses. These results suggest that only a few atoms forming a 2D in-plane magnetized dot may provide a stable elementary bit for nanorecording.