Assimilation analysis of Rammasun typhoon structure over Northwest Pacific using satellite data

The kinetic and thermodynamic structure of typhoon Rammasun (No. 0205) over the Northwest Pacific has been analyzed, using NOAA-16 polar orbiting Advanced Microwave Sounding Unit (AMSU) data collected on 2 July, 2002. The three-dimensional variational (3DVAR) assimilation technology is used to assimilate the satellite observation. The results show that the characteristics of the 3D typhoon structure can be more reasonably described from the assimilated data. The warm-cored structure of the typhoon is enhanced in the analyzed field, which corresponds to strong typhoon. The typhoon cyclonic circulation in the middle and lower layers is apparently strengthened, and the strong anticyclonic circulation appears at the top of the typhoon. The water vapor and its supply in the typhoon are enhanced. The microwave assimilation data may be used to supply the lack of the conventional observation data over the tropical ocean.     

Study on reduction of MoS<Subscript>2</Subscript> powders with activated carbon to produce Mo<Subscript>2</Subscript>C under vacuum conditions

A method of preparing Mo₂C via vacuum carbothermic reduction of MoS₂ in the temperature range of 1350-1550℃ was proposed. The effects of MoS₂-to-C molar ratio (α, α=1:1, 1:1.5, and 1:2.5) and reaction temperature (1350 to 1550℃) on the reaction were studied in detail. The phase transition, morphological evolution, and residual sulfur content of the products were analyzed by X-ray diffraction, field-emission scanning electron microscopy, and carbon-sulfur analysis, respectively. The results showed that the complete decomposition of MoS₂ under vacuum is difficult, whereas activated carbon can react with MoS₂ under vacuum to generate Mo₂C. Meanwhile, higher temperatures and the addition of more carbon accelerated the rate of carbothermic reduction reaction and further decreased the residual sulfur content. From the experimental results, the optimum molar ratio α was concluded to be 1:1.5.     

玻璃的缺陷态分布及其低温下的超声特性

本文作者测定了玻璃在低温下不同频率的超声衰减,并讨论了玻璃中超声衰减的特性.用频率为90MHz的a—T曲线拟合了玻璃中缺陷态关于活化能的分布曲线,再用这一分布曲线反算了在30MHz频率下玻璃的a—T曲线与实测的数据对比吻合良好.本文采用声衰减相对于温度变化曲线来拟合玻璃中缺陷态的相对态密度分布的方法有足够的精度,实验简便,是一种测定双势阱缺陷态密度分布行之有效的方法.     

Measurement-induced entanglement for excitation stored in remote atomic ensembles

A critical requirement for diverse applications in quantum information science is the capability to disseminate quantum resources over complex quantum networks. For example, the coherent distribution of entangled quantum states together with quantum memory (for storing the states) can enable scalable architectures for quantum computation, communication and metrology. Here we report observations of entanglement between two atomic ensembles located in distinct, spatially separated set-ups. Quantum interference in the detection of a photon emitted by one of the samples projects the otherwise independent ensembles into an entangled state with one joint excitation stored remotely in 10(5) atoms at each site. After a programmable delay, we confirm entanglement by mapping the state of the atoms to optical fields and measuring mutual coherences and photon statistics for these fields. We thereby determine a quantitative lower bound for the entanglement of the joint state of the ensembles. Our observations represent significant progress in the ability to distribute and store entangled quantum states.     

Ultrafast and direct imprint of nanostructures in silicon

The fabrication of micrometre- and nanometre-scale devices in silicon typically involves lithography and etching. These processes are costly and tend to be either limited in their resolution or slow in their throughput. Recent work has demonstrated the possibility of patterning substrates on the nanometre scale by 'imprinting' or directed self-assembly, although an etching step is still required to generate the final structures. We have devised and here demonstrate a rapid technique for patterning nanostructures in silicon that does not require etching. In our technique which -- we call 'laser-assisted direct imprint' (LADI) -- a single excimer laser pulse melts a thin surface layer of silicon, and a mould is embossed into the resulting liquid layer. A variety of structures with resolution better than 10 nm have been imprinted into silicon using LADI, and the embossing time is less than 250 ns. The high resolution and speed of LADI, which we attribute to molten silicon's low viscosity (one-third that of water), could open up a variety of applications and be extended to other materials and processing techniques.     

A model for estimating the rate constant between CO2-CO gas and molten slag containing iron oxides using optical basicity

A simple model for estimating the rate constant between CO₂-CO gas and molten slag containing iron oxides was developed using optical basicity only. In this model, the temperature dependence of the rate constant can be described by the Arrhenius law, and the activation energy can be expressed with a linear function of the slag??s optical basicity. The model was applied to some molten slag systems, such as FeO, FeO-CaO, FeO-SiO₂, FeO-Na₂O, FeO-CaO-SiO₂, FeO-SiO₂-P₂O₅, FeO-SiO₂-Na₂O, and FeO-CaO-SiO₂-P₂O₅. A comparison between the predicted results and measured data showed that the model worked well.