Experimental Studies on the Self-Shielding Effect in Fissile Fuel Breeding Measurement in Thorium Oxide Pellets Irradiated with 14 MeV Neutrons

The 14 MeV neutrons produced in the D-T fusion reactions have the potential of breeding Uranium-233 fissile fuel from fertile material Thorium-232. In order to estimate the amount of U-233 produced, experiments are carried out by irradiating thorium dioxide pellets with neutrons produced from a 14 MeV neutron generator. The objective of the present work is to measure the reaction rates of 232 Th + 1 n → 233 Th → 233 Pa → 233 U in different pellet thicknesses to study the self-shielding effects and adopt a procedure for correction. An appropriate assembly consisting of high-density polyethylene is designed and fabricated to slow down the high-energy neutrons, in which Thorium pellets are irradiated. The amount of fissile fuel ( 233 U) produced is estimated by measuring the 312 keV gammas emitted by Protactinium-233 (half-life of 27 days). A calibrated High Purity Germanium (HPGe) detector is used to measure the gamma ray spectrum. The amount of 233 U produced by Th 232 (n, γ) is calculated using MCNP code. The self-shielding effect is evaluated by calculating the reaction rates for different foil thickness. MCNP calculation results are compared with the experimental values and appropriate correction factors are estimated for self-shielding of neutrons and absorption of gamma rays.     

采用粗空心微球低压粉末冶金法制备空心微球复合泡沫钛(英文)

在低压下采用粉末冶金法,使用粗尺寸空心微球制备出不同相对密度的钛空心微球复合泡沫材料。在压力为60~70 MPa,通过冷压制备得到不同相对密度的泡沫钛。研究冷压压力与空心微球破碎倾向和相对密度的函数关系。研究制备的泡沫钛材料的压缩变形行为,考虑到实际应用,建立了平台应力、弹性模量、致密化应变和能量吸收之间的经验关系。对比泡沫钛和致密钛的性能指标,发现在工程应用中泡沫钛是致密钛的优秀替代物。     

Studies on Acid Leaching Methods for Fine Metal Powder Production

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弯曲回弹的半解析建模及弯曲载荷的影响

对金属板材弧形弯曲的回弹建立解析模型可以为设计提供很好的支持。金属板材的几何形状和材料参数对回弹量的影响大;另外,弯曲载荷的影响也较大。许多数值模拟技术已经被用来预测回弹量,但只有少数的解析模型可以用来进行深入研究。为了预测弧形弯曲的回弹,基于应变以及变形能为基础的方法,提出了一个唯象模型;并对该解析模型的预测结果与已发表的实验结果以及采用有限元分析的结果进行比较。结果表明,他们的一致性很好,是令人满意的。     

SPICE compatible analytical electron mobility model for biaxial strained-Si-MOSFETs

This paper describes an analytical model for bulk electron mobility in strained-Si layers as a function of strain.Phonon scattering,columbic scattering and surface roughness scattering are included to analyze the full mobility model.Analytical explicit calculations of all of the parameters to accurately estimate the electron mobility have been made.The results predict an increase in the electron mobility with the application of biaxial strain as also predicted from the basic theory of strain physics of metal oxide semiconductor(MOS) devices.The results have also been compared with numerically reported results and show good agreement.     

Implications of psychological research on stress and technological accidents.

Psychological research on stress, disasters, and human-made technological accidents have important implications for policy, planning, and legal resolution of situations caused by environmental hazards. The incidence of technological accidents and catastrophes seems to have increased, and the biobehavioral sequelae of such accidents among victims have implications for mental and physical health as well as for intervention and prevention. In this article, research on the long-term effects of human-made disasters is discussed in the context of contributions that psychological research and theory can make in decisions regarding where potential hazards are located, how they are managed, and how accidents are handled. Unique psychophysiological processes associated with toxic accidents make these stressors more potent and likely to cause long-term uncertainty and chronic stress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Protein function microarrays based on self-immobilizing and self-labeling fusion proteins

Protein microarrays are an attractive approach for the high-throughput analysis of protein function, but their impact on proteomics has been limited by the technical difficulties associated with their generation. Here we demonstrate that fusion proteins of O6-alkylguanine-DNA alkyltransferase (AGT) can be used for the simple and reliable generation of protein microarrays for the analysis of protein function. Important features of the approach are the selectivity of the covalent immobilization; this allows for direct immobilization of proteins out of cell extracts, and the option both to label and to immobilize AGT fusion proteins, which allows for direct screening for protein-protein interactions between different AGT fusion proteins. In addition to the identification of protein-protein interactions, AGT-based protein microarrays can be used for the characterization of small molecule-protein interactions or post-translational modifications. The potential of the approach was demonstrated by investigating the post-translational modification of acyl carrier protein (ACP) from E. coli by different phosphopantetheine transferases (PPTases), yielding insights into the role of selected ACP amino acids in the ACP-PPTase interaction.     

Structural,Wettability and Optical Investigation of Titanium Oxynitride Coatings:Effect of Various Sputtering Parameters

The objective of the present work is to investigate the effect of various sputtering parameters such as nitrogen flow rate,deposition time and sputtering pressure on structural,wettability and optical properties of titanium oxynitride films deposited on glass substrate by reactive magnetron sputtering.The X-ray diffraction graphs of titanium oxynitride films show evolution of various textures of TiO_xN_y and TiN phases with increasing nitrogen flow rate and deposition time,but an increase in sputtering pressure from 4.0 to 8.0 Pa results in decline of various textures observed for TiO_xN_y and TiN phases.The stress and strain calculated by sin~2Ψ method are compressive,which decrease with increasing nitrogen flow rate from 55 to 100 sccm(standard cubic centimeter per minute) and increase with increasing deposition time from 80 to 140 min due to atomic penning effect and increasing thickness of the deposited films.The titanium oxynitride films have contact angle values above 90 deg.,indicating that films are hydrophobic.The maximum contact angle of 109.1 deg.is observed at deposition time of 140 min.This water repellent property can add value to potential protective,wear and corrosion resistant application of titanium oxynitride films.The band gap decreases from 1.98 to 1.83 eV as nitrogen flow rate is increased from 55 to 100 sccm;it decreases from 1.93 to 1.79 eV as deposition time is increased from 80 to 140 min as more nitrogen incorporation results in higher negative potential of valence band N2p orbital.But it increases from 2.26 to 2.34 eV for titanium oxynitride films as sputtering pressure increases from 4.0 to 8.0 Pa.     

FINITE ELEMENT ANALYSIS OF A VERTICAL RECTANGULAR PLATE COUPLED WITH AN UNBOUNDED FLUID DOMAIN ON ONE SIDE USING A TRUNCATED FAR BOUNDARY

The dynamic pressure distribution on a rectangular plate attached to a rigid wall and supporting an infinitely large extent of fluid subjected to a harmonic ground excitation is evaluated in the time domain. Governing equations for the fluid domain are set considering the compressibility of the fluid with negligibly small change in density and a linearized free surface. A far boundary condition for the three-dimensional fluid domain is developed so that the far boundary is truncated at a closer proximity to the structure. The coupled problem is solved independently for the structure and the fluid domain by transferring the acceleration of the plate to the fluid and pressure of the fluid to the plate in sequence. Helmholtz equation for the three-dimensional fluid domain and Mindlin's theory for the two-dimensional plate are used for the solution of the interacting domains. Finite element technique is adopted for the solution of this problem with pressure as nodal variable for the fluid domain and displacement for the plate. The time dependent equations are solved in each of the interacting domain using Newmark-b method. The effectiveness of the technique is demonstrated and the influences of surface wave, exciting frequency and flexibility of the plate on dynamic pressure are investigated.     

Estimation of Separation of Electrolytes and Organic Compounds by Nanofiltration Membranes Using an Irreversible Thermodynamic Modei

Nanofiltration separation has become a popular technique for removing large organic molecules and inorganic substances from water. It is achieved by a combination of three mechanisms: electrostatic repulsion, sieving and diffusion. In the present work, a modei based on irreversible thermodynamics is extended and used to estimate rejection of inorganic salts and organic substances. Binary systems are modeled, where the feed contains an ion that is much less permeable to the membrane as compared with the other ion. The two modei parameters are estimated by fitting the modei to the experimental data. Variation of these parameters with the composition of the feed is described by an empirical correlation. This work attempts to describe transport through the nanofiltration membranes by a simple model.