Superconductivity in hydrogen dominant materials: silane

The metallization of hydrogen directly would require pressure in excess of 400 gigapascals (GPa), out of the reach of present experimental techniques. The dense group IVa hydrides attract considerable attention because hydrogen in these compounds is chemically precompressed and a metallic state is expected to be achievable at experimentally accessible pressures. We report the transformation of insulating molecular silane to a metal at 50 GPa, becoming superconducting at a transition temperature of Tc = 17 kelvin at 96 and 120 GPa. The metallic phase has a hexagonal close-packed structure with a high density of atomic hydrogen, creating a three-dimensional conducting network. These experimental findings support the idea of modeling metallic hydrogen with hydrogen-rich alloy.     

有机物料高温快速连续发酵除臭技术研究

采用2种除臭方法对畜禽粪便处理进行了研究：方法1采用物理-化学除臭方法，有机物料经JH1000型鸡粪烘干机处理后，再依次降温、降尘、沸石吸附、水吸收，然后加入亚硫酸氢钠和甘油水溶液除臭；方法2采用生物-物理-化学除臭方法，在工厂化高温快速连续发酵有机物料中预先混入10％～15％的风化煤，再加入1％马粪和5％5406菌剂，充分搅拌后用抽风机将臭气抽出，在臭气进入烟囱前喷洒亚硫酸氢纳-甘油混合液，同时在发酵过程中，调节和控制发酵温度、水分、化学、生物等指标变化。经气相色谱检测分析表明，2种方法综合除臭效率分别为64％，89％，均达到国家恶臭污染排放标准要求。生物-物理-化学方法除臭效果优于物理-化学方法，适合在我国大、中型集约化畜禽养殖场推广应用。     

Pattern of marine mass extinction near the Permian-Triassic boundary in South China

The Meishan section across the Permian-Triassic boundary in South China is the most thoroughly investigated in the world. A statistical analysis of the occurrences of 162 genera and 333 species confirms a sudden extinction event at 251.4 million years ago, coincident with a dramatic depletion of delta13C(carbonate) and an increase in microspherules.     

Duplication, deletion, and polymorphism in the sex-determining region of the mouse Y chromosome

The ZFY gene in the sex-determining region of the human Y chromosome encodes a "zinc-finger" protein that may be the testis-determining factor, TDF. Although the Y chromosomes of most placental mammals carry a single homolog of ZFY, the mouse Y chromosome has two homologs, both in the sex-determining (Sxr) region. Zfy-1 alone may suffice to determine maleness; Zfy-2 is dispensable, as it was deleted in an Sxr variant that retains sex-determining function but has lost other genes. Both loci mapped near the centromere of the mouse Y chromosome. The Y chromosomes of the subspecies Mus musculus musculus and M. m. domesticus were distinguishable by a Zfy-1 restriction fragment polymorphism, which can be used to study their differing interactions with autosomal sex-determining genes.     

Countercurrent chromatography with flow-through coil planet centrifuge

We have developed a new method of countercurrent chromatography which employs a vertical helical tube in the centrifugal field. The helical tube is arranged so that it does not rotate as it revolves, thus eliminating the need for rotating seals. When the gyrating tube is filled with either phase and the other phase is introduced into the tube in the proper direction, an equilibrium state results in which the two phases are split into multiple alternating segments within the coil. Each phase oscillates to and fro with the rotation as the moving phase is steadily eluted out through the other end of the tube. Consequently, solutes introduced into the tube are subjected to a rapid partition process, resulting in an efficient chromatographic separation without the complications arising from solid supports. The method is illustrated by the microanalytical separation of dinitrophenyl amino acids and can be used on a preparative scale.     

Oceanic Residence Times of Dissolved Beryllium and Aluminum Deduced from Cosmogenic Tracers 10Be and 26Al

The residence times of the soluble fractions of beryllium and aluminum in seawater are estimated to be 1500 years or more. These residence times are estimated from a comparison of the annual deposition rates of cosmogenic beryllium-10 and aluminum-26 with the concentrations of beryllium-10 and aluminum-26 in seawater estimated from the specific activities of these radionuclides in an authigenic mineral assembly such as a manganese nodule. These residence times are greater by an order of magnitude than the mean residence times of beryllium and aluminum estimated from the geochemical balance.     

The imaging photopolarimeter experiment on pioneer 11

For 2 weeks continuous imaging, photometry, and polarimetry observations were made of Jupiter and the Galilean satellites in red and blue light from Pioneer 11. Measurements of Jupiter's north and south polar regions were possible because the spacecraft trajectory was highly inclined to the planet's equatorial plane. One of the highest resolution images obtained is presented here along with a comparison of a sample of our photometric and polarimetric data with a simple model. The data seem consistent with increased molecular scattering at high latitudes.     

Orbital ordering transition in La4Ru2O10

We report experimental evidence for a full orbital ordering transition in the two-dimensional lanthanum ruthenate La4Ru2O10. The observable consequences of this orbital ordering include the loss of the Ru local moment, a structural distortion which partitions Ru-O bonds into axially oriented short and long sets, a sharp jump in electrical resistivity, and the opening of a spin gap that is visible in neutron scattering experiments. This is a rare example of a discrete orbital ordering transition in a 4d transition metal oxide and demonstrates that orbital effects can have an influence on the properties of layered ruthenates, a family of compounds that notably includes the p-wave superconductor Sr2RuO4 and the field-tuned quantum critical metamagnet Sr3Ru2O7.     

Role of importin-beta in coupling Ran to downstream targets in microtubule assembly

The guanosine triphosphatase Ran stimulates assembly of microtubule asters and spindles in mitotic Xenopus egg extracts. A carboxyl-terminal region of the nuclear-mitotic apparatus protein (NuMA), a nuclear protein required for organizing mitotic spindle poles, mimics Ran's ability to induce asters. This NuMA fragment also specifically interacted with the nuclear transport factor, importin-beta. We show that importin-beta is an inhibitor of microtubule aster assembly in Xenopus egg extracts and that Ran regulates the interaction between importin-beta and NuMA. Importin-beta therefore links NuMA to regulation by Ran. This suggests that similar mechanisms regulate nuclear import during interphase and spindle assembly during mitosis.