Electrical Transport Properties of Annealed Undoped InP

The electrical properties of annealed undoped n-type InP are studied by temperature dependent Hall effect (TDH) and current-voltage (I-V) measurements for semiconducting and semi-insulating samples, receptively. Defect band conduction in annealed semiconducting InP can be observed from TDH measurement, which is similar to those of as-grown unintentionally doped InP with low carrier concentration and moderate compensation. The I-V curves of annealed undoped SI InP exhibit ohmic property in the applied field region up to the onset of breakdown. Such a result is different from that of as-grown Fe-doped SI InP which has a nonlinear region in I-V curve explained by the theory of space charge limited current.

Alterations of immune functions induced by 12C6+ion irradiation in mice

Purpose: To estimate the biological risks to the immune system of the type of space radiation, 12C6+, encountered by cosmonauts during long-term travel in space. Materials and methods: The Kun-Ming strain mice were whole-body irradiated by 12C6+ ion with 0, 0.01, 0.05, 0.075, 0.2, 0.3, 0.5, 0.75, 1 or 2 Gy, at a dose rate of 1 Gy/min. At 35 days after irradiation, the thymus and spleen weights were measured, the natural killer (NK) cells activity of spleen was determined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT), and the interferon-gamma (IFN-gamma) levels in serum and thymus were detected with enzyme-linked immunosorbent assays (ELISA). Results: The results showed that the thymus weight, IFN-gamma levels in serum and the activity of splenic NK-cells had significantly increased at a dose of 0.05 Gy. With further dose increase, the weight of spleen continued to increase but the weight of thymus, IFN-gamma level and NK-cells activity declined. Conclusions: These results suggest that the dose of 0.05 Gy irradiation has a stimulatory effect on mouse immunity; this effect declined with increasing dose.

Effects of Ionizing Radiation on Three-Dimensional Human Vessel Models: Differential Effects According to Radiation Quality and Cellular Development

Little is known about the effects of space radiation on the human body. There are a number of potential chronic and acute effects, and one major target for noncarcinogenic effects is the human vasculature. Cellular stress, inflammatory response, and other radiation effects on endothelial cells may affect vascular function. This study was aimed at understanding the effects of space ionizing radiation on the formation and maintenance of capillary-like blood vessels. We used a 3D human vessel model created with human endothelial cells in a gel matrix to assess the effects of low-LET protons and high-LET iron ions. Iron ions were more damaging and caused significant reduction in the length of intact vessels in both developing and mature vessels at a dose of 80 cGy. Protons had no effect on mature vessels up to a dose of 3.2 Gy but did inhibit vessel formation at 80 cGy. Comparison with gamma radiation showed that photons had even less effect, although, as with protons, developing vessels were more sensitive. Apoptosis assays showed that inhibition of vessel development or deterioration of mature vessels was not due to cell death by apoptosis even in the case of iron ions. These are the first data to show the effects of radiation with varying linear energy transfer on a human vessel model. (C) 2011 In Radiation Research Society

The role of coke in the deactivation of Mo/MCM-22 catalyst for methane dehydroaromatization with CO2

The effect of space velocity on reaction performance and coke deposition over 6Mo/MCM-22 catalyst in methane dehydro-aromatization (MDA) with CO2 were studied. The characterization of catalysts reacted at different space velocity after the same amount of methane feed by TG, TPO and Benzene/NH3-TPD techniques suggested that the inert coke maybe responsible for the deactivation of catalyst because of its blockage effect for pore system.

Ten Years of the Relative Risk Model and Regional Scale Ecological Risk Assessment

It has been 10 years since the publication of the relative risk model (RRM) for regional scale ecological risk assessment. The approach has since been used successfully for a variety of freshwater, marine, and terrestrial environments in North America, South America, and Australia. During this period the types of stressors have been expanded to include more than contaminants. Invasive species, habitat loss, stream alteration and blockage, temperature, change in land use, and climate have been incorporated into the assessments. Major developments in the RRM have included the extensive use of geographical information systems, uncertainty analysis using Monte Carlo techniques, and its application to retrospective assessments to determine causation. The future uses of the RRM include assessments for forestry and conservation management, an increasing use in invasive species evaluation, and in sustainability. Developments in risk communication, the use of Bayesian approaches, and in uncertainty analyses are on the horizon.

Preparation and characterization of nanocrystalline CeO2 by precipitation method

CeO2 nanocrystalline particulates with different sizes were prepared by precipitation method using ethanol as dispersive and protective reagent. XRD spectra show that the synthesized CeO2 has cubic crystalline structure of space group O-H(5)-F-M3M, when calcination temperature is in the range of 250 similar to 800 degreesC. TEM images reveal that CeO2 particles are spherical in shape. The average size of the particles increases with the increase of calcination temperature. Thermogravimetric analysis indicates that the weight loss of precursor mainly depends on the calcination temperature, and little depends on the calcination time. Measurements of CeO2 relative density show that the relative density of CeO2 nanocrystalline powders increases with increasing CeO2 particle size.

PREPARATION AND MOLECULAR-STRUCTURE OF METHYLBIS(TERT-BUTYLCYCLOPENTADIENYL)NEODYMIUM AND METHYLBIS(TERT-BUTYLCYCLOPENTADIENYL)GADOLINIUM

Bis(t-butylcyclopentadienyl)lanthanide chloride (Ln = Nd or Gd) reacts with one equivalent of methyllithium in ether/tetrahydrofuran to give the complex [(C5H4tBu)2LnCH3]2 (Ln = Nd or Gd). The structure of [(C5H4tBu)2NdCH3]2 has been determined by X-ray analysis. The crystals are monoclinic of space group Cm with a = 9.538(2), b = 23.298(4), c = 9.505(3) angstrom, beta = 119.53(2)-degrees, V = 1828.0(7) angstrom 3, D(calc.) = 1.458 g/cm3 and Z = 2 for the dimer. The two (C5H4tBu)2Nd units in the dimer are connected by asymmetrical methyl bridges with independent Nd-C bond lengths of 2.70(2) and 2.53(2) angstrom and Nd-C-Nd angles of 94.7(9) and 87.3(6)-degrees.

砂砾岩储层流动单元四维模型研究

This article is an important part of "95" technological subject of SINOPEC. It has a large number of difficulties and workloads, and has significant theoretical meanings and practical value. The study area is composed of sandstone & conglomerate reservoir of alluvial fan & fan delta, which belong to Sha3 lower member and Sha4 upper member of lower tertiary of Yong'an Town Oilfield in Dongying Depression. The target stataum develops in the hanging wall of the synsedimentary fault in the scarp zone of Dongying Depression. The frequently intense movements result in the variation of sandstone and conglomerate reservoir and the evolution of the time and space of Sha3 lower member and Sha4 upper member in Yong'an Town Oilfield. As a result, it is difficult for the individual reservoir correlation at the root of fan, which bring about a tackle problem for the exploitation of oilfield. In this background, the research of fluid units will be more difficult. In this article, the new concepts, the new methods, and the new techniques of sedimentology, petroleum geology, reservoir geology, physics of crystal surface, dynamic & static state reservoir description and well logging geology are synthetically applied, and the computer technology are made full uses of, and the identifying, dividing and appraising of the two-formation-type sandstone & conglomerate reservoir fluid units of Sha3 lower member and Sha4 upper member systemically analyzed in Yong'an Town Oilfield, Dongying Depression. For the first time, the single-well model, the section model, the plane model, the nuclear magnetism log model, the microcosmic network model, the 4-D geology model and the simulation model of the two-formation-type reservoir fluid units of the of sandstone & conglomerate reservoir of Sha3 lower member and Sha4 upper member are established, and the formative mechanism and distributing & enrichment laws of oil-gas of the two type of sandstone and conglomerate reservoir fluid units are revealed. This article established the optimizing, identifying, classifying and appraising standard of the two-formation-type reservoir fluid units of the of sandstone and conglomerate reservoir of Sha3 lower member and Sha4 upper member, which settles the substantial foundations for static state model of the fluid units, reveals the macroscopic & microcosmic various laws of geometrical static state of the fluid units, and instructs the oil exploitation. This article established static state model of the two-formation-type sandstone and conglomerate reservoir fluid units by using the multi-subject theories, information and techniques, and reveals the geometrical configuration, special distribution and the oil-gas enrichment laws of the sandstone and conglomerate reservoir fluid units. For the first time, we established the nuclear magnetism log model of the two-formation-type sandstone and conglomerate reservoir of Sha3 lower member and Sha4 upper member, which reveals not only the character and distributing laws of the porosity and permeability, bat also the formation and distribution of the movable fluid. It established six type of microcosmic net model of the two-formation-type sandstone and conglomerate reservoir of Sha3 lower member and Sha4 upper member in the working area by using the advanced theories, such as rock thin section, SEM, image analysis, intrusive mercury, mold, rock C.T. measure & test image etc., which reveals the microcosmic characteristic of porosity & throat, filterate mode and microcosmic oil-gas enrichment laws of the sandstone and conglomerate reservoir. For the first time, it sets up the 4-D model and mathematic model of the sandstone and conglomerate reservoir, which reveals the distributing and evolving laws of macroscopic & microcosmic parameters of the two-formation-type sandstone and conglomerate reservoir and oil-gas in 4-D space. At the same time, it also forecasts the oil-gas distribution and instructs the oilfield exploitation. It established reservoir simulation model, which reveals the filterate character and distributing laws of oil-gas in different porosity & throat net models. This article established the assistant theories and techniques for researching, describing, indicating and forecasting the sandstone and conglomerate reservoir fluid units, and develops the theories and techniques of the land faces faulted basin exploitation geology. In instructing oilfield exploitation, it had won the notable economic & social benefits.

Catalytic reduction of NO over in situ synthesized Ir/ZSM-5 monoliths

The catalytic performance of Ir-based catalysts was investigated for the reduction of NO under lean-burn conditions over binderless Ir/ZSM-5 monoliths, which were prepared by a vapor phase transport (VPT) technique. The catalytic activity was found to be dependent not only on the Ir content, but also on the ZSM-5 loading of the monolith. With the decreasing of the Ir content or the increasing of the ZSM-5 loading of the monolith, NO conversion increased. When the ZSM-5 loading on the cordierite monolith was raised up to ca. 11% and the metal Ir content was about 5 g/l, the NO conversion reached its maximum value of 73% at 533 K and SV of 20 000 h(-1). Furthermore, both the presence of 10% water vapor in the feed gas and the variation of space velocity of the reaction gases have little effect on the NO conversion. A comparative test between Ir/ZSM-5 and Cu/ZSM-5, as well as the variation of the feed gas compositions, revealed that Ir/ZSM-5 is very active for the reduction of NO by CO under lean conditions, although it is a poor catalyst for the C3H8-SCR process. This unique property of Ir/ZSM-5 makes it superior to the traditional three-way catalyst (TWC) for NO reduction under lean conditions. (C) 2001 Elsevier Science B.V. All rights reserved.