Total cross section of solid mesitylene, toluene and a mixture of them at thermal neutron energies

The total neutron cross sections of mesitylene, toluene and a solution 3:2 by volume of mesitylene and toluene were measured at the electron LINAC based pulsed neutron source of Centro Atómico Bariloche. Measurements were performed at 180 K, 120 K and 31.6 K for mesitylene and at 120 K and 31.6 K for toluene and a solution 3:2 by volume of mesitylene and toluene. The systems are potential moderator materials to be considered in the design of a cold neutron source due to their high resistance to radiation and the richness in low-energy excitations of their frequency spectra, that lead to produce an enhanced cold neutron flux.     

Radiation protection of mox-fuel by doping with Pa and U

The paper addresses the problem of MOX-fuel self-protection at the “Spent Fuel Standard” level and more during full cycle of MOX-fuel management. Under conditions of the closed LWR cycle the proliferation-resistance levels were evaluated for fresh and spent MOX-fuel doped with ²³¹Pa and ²³²U. According to the evaluations, it was derived that cyclic regime with Pa-U feeding at the level of 5% HM makes it possible to achieve the proliferation resistance of fresh MOX-fuel at the level high enough to protect it against short-term unauthorized actions (receiving the lethal dose for about 10 minutes in the vicinity of MOX-fuel assembly) and also against the acts of terrorism (receiving the shock lethal dose for a few minutes).     

Growth and characterization of pure and potassium chloride-doped Zinc Tris-thiourea Sulphate (ZTS) single crystals

Single crystals of pure and potassium chloride-doped Zinc Tris-thiourea Sulphate (ZTS) were grown from aqueous solution by slow evaporation technique. The grown crystals were subjected to various studies such as XRD, FTIR, atomic absorption, SHG and TGA-DTA studies. The melting point and density of the grown crystals were also measured. The various studies revealed the incorporation of the impurity (potassium chloride) into ZTS crystals and the investigations indicated that the impurity played an important role in the changes of the spectral and structured properties of ZTS crystals.     

The Making of Early Republican Ankara

Zeynep Kezer outlines the ascendancy and development of Ankara from an obscure, central Anatolian town into a capital city that was to become the focus of the new nation state. Informed by German architectural and technological expertise, it was executed to rigorous Modernist planning principles and aesthetics, and came to represent in urban form the polarisation of pre-republican and republican Turkey. Copyright © 2010 John Wiley & Sons, Ltd.     

The Story of Istanbul's Modernisation

Since reform started under Ottoman rule in the early 19th century, Istanbul has undergone a substantial period of modernisation that has spanned more than 150 years. İlhan Tekeli outlines the metropolis' enduring development, characterising Istanbul's transformation into a modern city into four distinct periods. It is a story that bridges the collapse of the Ottoman Empire and the reconstruction of the Turkish Republic as a nation-state, with the initial demise of the city in favour of Ankara; and continues with Istanbul regaining its status as a world city; as it evolves from a monstrous industrial city to an urban region and global centre. Copyright © 2010 John Wiley & Sons, Ltd.     

主题模型中的参数估计方法综述

主题模型利用快速的机器学习算法从高维稀疏的单词数据中提取出低维的主题表示,实现了对文档单词的聚类。对主题模型中的参数进行估计是该领域的一项重要研究工作。详细描述了概率潜在语义分析模型和潜在狄利克雷模型以及主题模型中基本的参数估计方法,并对模型的困惑度进行了实验比较。     

Distribution Behavior of Nb,Ta, and Pa as Homologues of Db in Cation Exchange and Solid-Liquid and Liquid-Liquid Extractions by Aliquat 336 from Hydrochloric Acid

Detailed chemical studies on transactinide elements will clarify their characteristic properties caused by strong relativistic effect. In this work, to realize chemical study on transactinide element ₁₀₅Db, cation exchange, and solid-liquid and liquid-liquid extractions of micro amounts of Nb, Ta (homologues of Db), and Pa (pseudo homologue) by Aliquat 336 were performed employing hydrochloric acid. Clearly different chloride complex formations and distribution reaction kinetics were observed among these elements, and the present results are useful for studying the chemical properties of Db. Based on these results, we propose suitable experimental conditions for Db.     

Interface kinetics and morphology on the nanoscale

Diffusion on the nanoscale in multilayer, thin films has many challenging features even if the role of structural defects can be neglected and ‘only’ the effects related to the nanoscale arise. Recently, we have discovered different examples for diffusional nanoscale effects, which are summarized in this contribution. Interface shift kinetics may be different from the ones predicted by continuum approximations (anomalous kinetics). Moreover we show that in solid state reactions, reaction layers form and start to grow highly non-stoichiometrically and an initially existing stoichiometric compound layer may dissolve then re-form non-stoichiometrically. Our findings are of primary importance for nanotechnologies where early stages of solid state reaction (SSR) are utilized. We also show that an initially diffused interface may sharpen even in completely miscible systems. This phenomenon could provide a useful tool for the improvement of interfaces and offer a way to fabricate, for example, better X-ray or neutron mirrors, microelectronic devices, or, multilayers with giant magnetic resistance.A variety of different UHV-based techniques (AES/XPS and synchrotron facilities) have been used to prove the above theoretical findings in different systems (e.g. Ni/Cu, Ni/Au, Si/Ge, Co/Si).     

Investigation of thermal stability of hydrogenated amorphous Si/Ge multilayers

Thermal stability of hydrogenated amorphous Si/Ge multilayers has been investigated by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Small-Angle X-Ray Diffraction (SAXRD) techniques. Amorphous H-Si/Ge multilayers were prepared by RF sputtering with 1.5 and 6 ml/min H₂ flow-rate. It is shown by Elastic Recoil Detection Analysis (ERDA) that the hydrogen concentration increased by increasing the H₂ flow-rate. Annealing of the samples was carried out at 400 and 450 °C for several hours. It has been observed that samples prepared with 6 ml/min flow-rate at both annealing temperatures underwent significant structural changes: the surface of the samples was visibly roughened, gas bubbles were formed and craters were created. The decay of the periodic structure of Si and Ge layers in these types of multilayers was faster than in non-hydrogenated samples. Samples prepared with 1.5 ml/min flow-rate have similar behaviour at 450 °C, but at 400 °C the decay of the first order SAXRD peaks was slower than in case of the non-hydrogenated multilayers. Qualitatively the observed behaviour can be explained by the fast desorption of the saturated hydrogen, leading to the formation of bubbles and craters at 450 °C, as well as, at 400 °C in the sample with lower H-content, by the possible passivation of the dangling bonds resulting in a slowing down of the diffusion intermixing.     

预防和治理大型发电机组脱硫设备的GGH（空气换热器）结垢堵塞有效方法

某发电公司发电机组FGD脱硫设备的GGH换热器原件在使用过程中经常性地发生结垢堵塞,GGH的差压增大,影响了脱硫的效果。在线高压水冲洗与压缩空气吹扫能够减少GGH的差压。但因设备老化和使用时间长,效果不是很好。而化学清洗则能够有效解决GGH的换热原件结垢堵塞的疏通问题。