Mechanochemical Synthesis and Characterization of Nanocrystalline Copper-Cobalt Ferrites

Nanocrystalline copper-cobalt ferrites with composition Cu_(1-x)Co_xFe_2O_4,where x = 0.2 and 0.8,were synthesized by mechanochemical treatment of co-precipitated precursors.The ferrite powders were characterized by XRD and Mossbauer spectroscopy.Results proved obtaining of spinel ferrites with crystallite size smaller than 10 nm.Increasing of crystallite size of samples with increasing of mechanochemical treatment duration was established,too.Catalytic properties of obtained ferrites were tested in reactions of oxidation of CO,methanol and dimethyl ether.High catalytic activity of nanocrystalline copper-cobalt ferrites toward CO and CH_3OH(about 100% conversions of CO and CH_3OH at 160 ℃)and moderate activity toward(CH_3)_2O oxidation were established.The results obtained revealed that the Co/Cu atomic ratio is an important factor determinant the behavior of catalysts toward methanol and DME oxidation.     

Heavy metals (Pb,Cu, Zn and Cd) in the system soil – grapevine – grape

An Erratum has been published for this article in Journal of the Science of Food and Agriculture 79(15)1999, 2122. The investigation was carried out in the period 1991–1995 in a region with a major industrial pollutant, the Non‐Ferrous‐Metal Works, and a region with no industrial pollutants (as a control). The heavy metal content in soil, roots, annual shoots and perennial parts of grapevine, leaves, grapes and wine, was determined. Soil samples and roots of the rootstock Kober 5BB were taken at 10 cm intervals from depths of 0–100 cm. Roots were divided by thickness in fractions at 1 mm intervals. The shoots, bark, vascular tissue, wood, core and diaphragm were investigated. The leaf analyses included leaf blade and leaf petioles, and those of grapes, berry‐free raceme (washed in a lot of water and unwashed). Berries were analysed (the berry skin, the pulp and the seeds). The results obtained for the Pb, Cu, Zn and Cd contents in the grapevine roots show that they depend significantly both on their amounts in the soil and the age of the roots. The main parts of the heavy metal amounts taken by the roots of the grapevine from the soil are fixed and accumulated in the young feed rootlets (with diameters of 1 mm), and small amounts of them move through the conducting system to the older, larger diameter root system. The experimental data obtained for the presence of Pb, Cu, Zn and Cd in the separate tissues and organs of grapevines grown in an industrially polluted region showed that their amounts were mainly due to the heavy‐metal‐containing aerosols falling from the atmosphere. Part of them, however, got into the soil, and from there, even if in minimal amounts, penetrated via the root system into the grapevine plants and accumulated into their different overground parts. © 1999 Society of Chemical Industry     

On the geometrical dependence of low-frequency noise in SiGe HBTs

We present an investigation of the dependence of low-frequency noise on device geometry in advanced npn silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs). The devices examined in this work have fixed emitter width (W_E = 0.4 μm), but varying emitter length (0.5 μm  L_E  20.0 μm), and thus the ratio of the emitter perimeter (P_E) to the emitter area (A_E) varies widely, making it ideal for examining geometrical effects. The SPICE noise parameter A_F extracted from these devices decreases with increasing L_E. Furthermore, the low-frequency noise measured on SiGe HBTs with significantly different P_E/A_E ratios suggests a possibility that the fundamental noise source for the diffusion base current may be located at the emitter periphery. Transistors with different distances between the emitter edge and the shallow trench edge (XEC), and shallow trench edge to deep trench edge (XTC), are also investigated. The SiGe HBTs with a smaller value of XEC have higher low-frequency noise, but no significant difference is found in devices with varying XTC. Explanations of the observed noise behavior are suggested.     

Equation Discovery for Financial Forcasting in Context of Islamic Banking

This paper describes an equation discovery approach based on machine leamng using LAGdtAMGE as an equation discovery tool,with two sources of input,a dataset and model presented in context-free gammar.The approach is searching a large range of potential equations by a specific model.The parameters of the equation are fitted to find the best equations.The The experiments are illustratedwith commodity prices from the London Metal Exchange for the period of January-October 2009.The outputs of the experiments are a large number of equations;same of the equations display that the predicted rakes are following the market trends in perfect patterns.     

Application of corporate social responsibility approach in Bulgaria to support sustainable tourism development

The rapidly developing tourism industry in Bulgaria in the last 15?years, especially at the Black sea coast, contributed to an entire change in the accommodation sector. The growth was due to unseen construction of new accommodation facilities and entire renovation of the existing ones. At the same time the tourism industry suffers from many social problems: lack of staff, shortage of qualified staff especially in the high-star hotels, very high rate of turnover, flow of Bulgarian staff abroad. The bigger mobility of the employees is facilitated by the seasonal character of the industry, knowledge of foreign languages, difference in payments, as well as in the nature of work. Overall, this leads to lost training investments, reduces the incentives for employers to provide training, causes lower quality services in hotels, and finally impacts negatively the competitiveness of the hotel sector in Bulgaria and its sustainable development. The paper presents the practical experience and conclusions from a corporate social responsibility (CSR) assessment in 25 Bulgarian hotels regarding the social issues of the CSR: human resource management, occupational safety and health, human and labour rights, stakeholder and community involvement, customer satisfaction. The most important social problems identified are: deficiency in management skills, deficiency in organised (external) stakeholder dialogue, lack of qualified staff in certain professions, lack of investment in training, high turnover, low motivation, conflicts related to wage levels, overtime, etc. A set of key performance indicators related to social responsibility is suggested and analysed. The benchmarking process is discussed and exemplary benchmarks are quoted. The most frequently proposed measures by the hotel CSR teams to improve the social responsibility in the hotels are reviewed.     

Xylose fermentation to biofuels (hydrogen and ethanol) by extreme thermophilic (70 °C) mixed culture

Combined biohydrogen and bioethanol (CHE) production from xylose was achieved by an extreme thermophilic (70 °C) mixed culture. Effect of initial pH, xylose, peptone, FeSO₄, NaHCO₃, yeast extract, trace mineral salts, vitamins, and phosphate buffer concentrations on bioethanol and biohydrogen yield was investigated in batch experiments. Results obtained showed that initial pH, concentration of xylose, peptone, and FeSO₄ significantly affected biohydrogen and bioethanol production, while the concentration of NaHCO₃ was only significant for bioethanol production. By changing cultivation conditions the culture could be directed to mainly produce ethanol with maximum ethanol yield of 1.60 mol ethanol/mol-xylose corresponding to 95.8% of the theoretical ethanol yield based on degradation of xylose through ethanologenic pathway, or mainly hydrogen with maximum hydrogen yield of 1.84 mol H₂/mol-xylose corresponding to 55% of the theoretical hydrogen yield based on acetate metabolic pathway. An empirical model was established to reveal the quantitative effect of factors significant for biohydrogen (quadratic model) production and for bioethanol (linear model) production. Changes in hydrogen/ethanol yields observed were due to the shift of the metabolic pathway between ethanol or hydrogen production, rather than changes in bacterial community composition at genus level. Thermoanaerobacter related bacteria were found to be the dominant hydrogen/ethanol producers.     

Thick lead-free ferroelectric films with high Curie temperatures through nanocomposite-induced strain

Ferroelectric materials are used in applications ranging from energy harvesting to high-power electronic transducers. However, industry-standard ferroelectric materials contain lead, which is toxic and environmentally unfriendly. The preferred alternative, BaTiO(3), is non-toxic and has excellent ferroelectric properties, but its Curie temperature of ～130 °C is too low to be practical. Strain has been used to enhance the Curie temperature of BaTiO(3) (ref. 4) and SrTiO(3) (ref. 5) films, but only for thicknesses of tens of nanometres, which is not thick enough for many device applications. Here, we increase the Curie temperature of micrometre-thick films of BaTiO(3) to at least 330 °C, and the tetragonal-to-cubic structural transition temperature to beyond 800 °C, by interspersing stiff, self-assembled vertical columns of Sm(2)O(3) throughout the film thickness. The columns, which are 10 nm in diameter, strain the BaTiO(3) matrix by 2.35%, forcing it to maintain its tetragonal structure and resulting in the highest BaTiO(3) transition temperatures so far.     

On the concept of immediate probabilities

The problem of decision making under doubt is described. the concept of immediate probabilities is introduced. It is seen as a modification of typical probabilistic knowledge with information about the payoffs, mediated through dispositional information (optimism/pessimism), resulting in a modified formulation of an agents perception of the probabilities in effect in the current decision. We use the Dempster rule of combination to help obtain an expression for these probabilities. We show how immediate probabilities allows us to explain the Allais paradox. A number of properties of these probabilities are described. the strategic use of these probabilities are explored as a means for effecting other people's decisions. © 1995 John Wiley & Sons, Inc.     

An exploratory study of the relationship between meaning-making and quality in games

Multimedia Tools and Applications - This study aimed at identifying and interpreting relevant relationships between players’ perceptions of meaning-making affordances and: 1) players’...