bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymmetric source/drain offset structure for reduced leakage current in polycrystalline‐silicon thin‐film transistors
Authors: Lee Won‐Kyu , Park Hyun‐Sang , Jeong Byoung‐Seong , Choi Joonhoo , Kim Chi‐Woo , Hong Yongtaek , Han Min‐Koo
Published: May 2009

Abstract—An asymmetric source/drain offset structured (AOS) polycrystalline‐silicon (poly‐Si) thin‐film transistor (TFT) has ben developed by employing alternating magnetic‐field‐enhanced rapid thermal annealing (AMFERTA). The realized AOS poly‐Si TFT, with long drain‐side offset lengthLOff1and short source‐side offset lengthLOff2, considerably suppresses leakage current without sacrificing ON‐current. The offset regions of the AOS TFT are naturally lightly doped due to the diffusion ofn+ions by AMFERTA crystallization. The fabrication process of the AOS TFT does not require any additional offset mask step or doping process. Experimental results show that the leakage current is considerably suppressed when the drain‐side offset lengthLOff1is larger than 1.25 μm.
Anthropogenic modification of the nitrogen cycling within the Greater Hangzhou Area system, China
Authors: Gu Baojing , Chang Jie , Ge Ying , Ge Hanliang , Yuan Chi , Peng Changhui , Jiang Hong
Published: May 2009

Based on the mass balance approach, a detailed quantification of nitrogen (N) cycling was constructed for an urban–rural complex system, named the Greater Hangzhou Area (GHA) system, for this paper. The GHA is located in the humid climatic region on the southeastern coast of China, one of the earliest regions in the Yangtze Delta to experience economic development. Total N input into the GHA was calculated at 274.66 Gg/yr (1 Gg = 109 g), and total output was calculated at 227.33 Gg/yr, while N accumulation was assessed at 47.33 Gg/yr (17.2% of the total N input). Human activity resulted in 73% of N input by means of synthetic fertilizers, human food, animal feed, imported N containing chemicals, fossil fuel combustion, and other items. More than 69.3% of N was released into the atmosphere, and riverine N export accounted for 22.2% of total N output. N input and output to and from the GHA in 1980 were estimated at 119.53 Gg/yr and 98.30 Gg/yr, respectively, with an increase of 130% and 131%, respectively, during a 24‐year period (from 1980 to 2004). The N input increase was influenced by synthetic fertilizers (138%), animal feed (225%), N‐containing chemicals (371%), riverine input (311%), and N deposition (441%). Compared to the N balance seen in the arid Central Arizona–Phoenix (CAP) system in the United States, the proportion of N transferred to water bodies in the humid GHA system was found to be 36 times higher than the CAP system. Anthropogenic activity, as it typically does, enhanced the flux of N biogeochemistry in the GHA; however, a lack of an N remover (N pollutant treatment facilities) causes excess reactive N (Nr; such as NH3, N2O, NOx), polluting water bodies and the atmosphere within the GHA. Therefore many challenges remain ahead in order to achieve sustainable development in the rapidly developing GHA system.
Systemic Barriers to Health Care Access for U.S. Women with HIV: The Role of Cost and insurance
Authors: Stevens Patricia E. , Keigher Sharon M.
Published: May 2009

Lack of access to health care has particularly brutal consequences for low-income U.S. women with HIV who, without regular and consistent primary care, including treatment with highly active antiretroviral therapy (HAART), are less likely to live long and well with HIV. This article explores barriers to basic health care encountered by a sample of 55 HIV-infected women from urban and rural Wisconsin who participated in a longitudinal, qualitative study. In a series of 10 in-depth, story-eliciting interviews over a two-year period, each woman explained in detail what it was like for her to obtain health care since becoming infected. Conveying women's subjective experiences of trying to get the care they needed, their stories highlight serious institutional impediments to health care and provide a discomfiting glimpse of the systemic forces that limit access to health itself. Findings convey how the extraordinarily high cost of U.S. health care, the unpredictable and disjointed array of out-of-pocket costs, and the complex and obfuscated intricacies of health insurance impeded women's access. They lived a paradoxical reality: having an illness they feared, needing treatment for long-term survival, and being unable to meet its costs. Each woman's story reflects deep fissures in the U.S. health care system.
Patients' Awareness of and Attitudes toward Gifts from Pharmaceutical Companies to Physicians
Authors: Jastifer James , Roberts Sarah
Published: May 2009

The purpose of this study was to assess patients' awareness of and attitudes toward physicians' receiving gifts from the pharmaceutical industry. The Alger County Community Health Study was a self-report survey targeting rural Alger County, Michigan. The survey (completion rate 10.1%) addressed issues on health, demographics, and patients' awareness of and attitudes toward gifts to physicians. Rates of awareness of gifts were: drug samples, 94 percent; ballpoint pens, 76.2 percent; medical books, 38 percent; conference/travel expenses, 34 percent; dinner out, 36.6 percent; spouse meal at dinner out, 23 percent; golf tournament fees, 19.0 percent. Rates of “approval” of physicians' accepting gifts were: drug samples, 69 percent; ballpoint pens, 54.2 percent; medical books, 49 percent; conference/travel expenses, 14 percent; dinner out, 12.1 percent; spouse meal at dinner out, 7 percent; golf tournament fees, 3.7 percent. Patients' approval of gifts seems to be related to the perceived value of the gift to patients as well as its monetary value. The patient population in the current study seems to be less approving of gifts to physicians than patients surveyed in the 1990s. Patients' opinions should be considered when establishing ethical guidelines and policies regulating physician-industry interaction.
Expanding Housing Demand Efficiently and Equitably
Authors: Lerman Robert I
Published: May 2009

Battered housing prices are central to today's financial crisis, and Robert Lerman proposes a remedy that does not involve throwing money at Wall Street.
Kinetics and Process Selectivity Studies for the Preparation of 3, 7-Dinitro-1, 3, 5, 7-Tetraazabicyclo [3, 3, 1] Nonane
Authors: Jadhav P. M. , Sarangapani Radhakrishnan , Patil R. S. , Kunjir Ganesh M , Soman T.
Published: May 2009

The key intermediate for the manufacturing of a powerful explosive, HMX, is 3, 7-Dinitro-1, 3, 5, 7-tetraazabicyclo [3, 3, 1] nonane (DPT). It is being manufactured by the nitration of hexamine under mild acidic conditions and at low temperature yields of DPT in the initial stage, which upon further nitration gives HMX. The yield of DPT decides the productivity and economy of the HMX process. The present study's aim is to achieve the rate of formation of products and the stimulus of process parameters on the reaction for essentially enhancing the yield of DPT. The rate of formation of DPT has been studied in a continuous process under a wide envelope of residence times and temperatures. The rate expressions and activation energies of DPT and side products have been derived. The optimal temperature of reaction has been derived to obtain a higher yield of DPT at the lowest formation of side products. The selectivity of process has been enhanced by varying the concentration of limiting reagent.The qualitative and quantitative picture has been highlighted to realize the role of formation of DPT in HMX formation, and the study reveals that the yield of DPT and side products is sensitive toward the concentration of nitronium ion.
Research of possibilities for use domestic kaolin clays for production of metakaolin
Authors: Mitrovic Aleksandra , Komljenovic Miroslav , Ilic Biljana
Published: May 2009

Environmental concerns coming from the high energy consumption and CO2 emission associated with cement production have brought about pressures to reduce cement consumption through the use of new materials which can be applied for substitution of a part of clinker in Portland cement or a part of cement in concrete. One of the materials that satisfy requirements of sustainable development and, when added in appropriate shares, improves the properties of cement, mortars and concrete, is metakaolin (MK), a processed pozzolana. The main and widely used raw material for production of metakaolin is kaolin clay. MK is produced by calcination or 'thermal activation' of kaolin clay. The possibilities for metakaolin production are strongly related to the characteristics of the used kaolin clay. The samples of domestic kaolin clay used in this study were provided by factories Kaolin, Valjevo, and Keramika, Mladenovac. Chemical composition, mineralogical composition and thermal properties of these samples were determined. Thermal analysis (simultaneous recording of TG, DTG and DTA signals) was carried out at the temperature range from 20 to 1200 ?C. For both clays the results show that the loss of mass occurred in two stages. The dehydroxillation of kaolinite and formation of metakaolin occurred in the second stage. Minerals quartz and kaolinite are dominant in the clay Kaolin, Valjevo. Dehydroxillation of kaolinite and formation of metakaolin took place in the temperature range 350-800 ?C. This clay does not have clearly distinct exothermic and endothermic peaks. Clay from Keramika, Mladenovac, has a higher content of the kaolinite mineral, i.e. 81.51%. The dehydroxillation of kaolinite and formation of metakaolin occurred in the temperature range 400-700 ?C. This clay has two distinct endothermic peaks at 60 and 490 ?C. All these results show that both clays can be used for production of metakaolin.
Determination of the number of radicals in the initial chain reactions by mathematical methods
Authors: Pejovic Branko , Jotanovic Milovan , Micic Vladan , Tomic Milorad , Tadic Goran
Published: May 2009

Starting from the fact that the real mechanism in a chemical equation takes places through a certain number of radicals which participate in simultaneous reactions and initiate chain reactions according to a particular pattern, the aim of this study is to determine their number in the first couple of steps of the reaction. Based on this, the numbers of radicals were determined in the general case, in the form of linear difference equations, which, by certain mathematical transformations, were reduced to one equation that satisfies a particular numeric series, entirely defined if its first members are known. The equation obtained was solved by a common method developed in the theory of numeric series, in which its solutions represent the number of radicals in an arbitrary step of the reaction observed, in the analytical form. In the final part of the study, the method was tested and verified using two characteristic examples from general chemistry. The study also gives a suggestion of a more efficient procedure by reducing the difference equation to a lower order.
Improvement of CaO-based sorbent performance for CO2 looping cycles
Authors: Manovic Vasilije , Anthony Edward
Published: May 2009

This paper presents research on CO2 capture by lime-based looping cycles. This is a new and promising technology that may help in mitigation of global warming and climate change caused primarily by the use of fossil fuels. The intensity of the anticipated changes urgently requires solutions such as the developing technologies for CO2 capture, especially those based on CaO looping cycles. This technology is at the pilot plant demonstration stage and there are still significant challenges that require solutions. The technology is based on a dual fluidized bed reactor which contains a carbonator - a unit for CO2 capture, and a calciner - a unit for CaO regeneration. The major technology components are well known from other technologies and easily applicable. However, even though CaO is a very good candidate as a solid CO2 carrier, its performance in a practical system still has significant limitations. Thus, research on CaO performance is critical and this paper discusses some of the more important problems and potential solutions that are being examined at CETC-O.
Rapid pyrolysis of Serbian soft brown coals
Authors: Jankes Goran , Cvetkovic Olga , Milovanovic Nebojsa , Ercegovac Marko , Adzic Miroljub , Stamenic Mirjana
Published: May 2009

Soft brown coals of the open coal fields of Kolubara and Kostolac are the main domestic energy sources of Serbia. This paper presents the results of investigations on rapid devolatilization of these two coals which have covered kinetics of devolatilization (based on total volatile yield), forms of sulphur and petrographic analysis of coal and char. Experiments of devolatilization were performed in inert gas (N2) at atmospheric pressure and in batch-type hot-wire screen reactor. The mass-loss values of both coals at selected final reaction temperatures (300-900?C) and retention times (3-28 s) were obtained. Anthony and Howard's kinetic model was applied over two temperature ranges (300-500 and 700-900?C). The types of sulphur as monosulphide, sulphate, pyritic, and organic sulphur were determined for chars and original coals. Strong transformation of pyrite was evident even at low temperatures (300?C). Devolatilization of all types of sulphur has started over 600 and at 900?C the content of sulphur in char remained only 66% of total sulphur in original coal. Microscopic investigations were carried out on samples prepared for reflected light measurements. The petrographic analysis included: the ratio of unchanged and changed coal, maceral types, the share of cenosferes, isotropic mixed carbonized grains, mixed grains, small fragments, clay, and pyrite. The change of the structure of devolatilized coal was also observed.
Influence of running conditions on resonant oscillations in fresh-air ventilator blades used in thermal power plants
Authors: Tasic Milan , Mitrovic Radivoje , Popovic Predrag , Tasic Marko
Published: May 2009

High frequency cyclic load of fresh air supply to ventilator blades in thermo energetic facilities can cause the occurrence of fretting in the pressed overlap of ventilator shaft and socket. These loads can be generated by the resonant oscillations of ventilator blades and thermal residual stress due to welding. To prevent running in resonant conditions, the manufacturer of the ventilator defined a procedure of adjusting blades natural frequency in the process of production, as well as period control during exploitation period. The numerical simulations and the accelerations measured and presented in this paper, enabling analysis of mass changes and rotation rate effects on resonant oscillations occurrence in fresh air ventilator.
Analysis of the energetic/environmental performances of gas turbine plant: Effect of thermal barrier coatings and mass of cooling air
Authors: Ion Ion , Portinha Anibal , Martins Jorge , Teixeira Vasco , Carneiro Joaquim
Published: May 2009

Zirconia stabilized with 8 wt.% Y2O3 is the most common material to be applied in thermal barrier coatings owing to its excellent properties: low thermal conductivity, high toughness and thermal expansion coefficient as ceramic material. Calculation has been made to evaluate the gains of thermal barrier coatings applied on gas turbine blades. The study considers a top ceramic coating Zirconia stabilized with 8 wt.% Y2O3 on a NiCoCrAlY bond coat and Inconel 738LC as substrate. For different thickness and different cooling air flow rates, a thermodynamic analysis has been performed and pollutants emissions (CO, NOx) have been estimated to analyze the effect of rising the gas inlet temperature. The effect of thickness and thermal conductivity of top coating and the mass flow rate of cooling air have been analyzed. The model for heat transfer analysis gives the temperature reduction through the wall blade for the considered conditions and the results presented in this contribution are restricted to a two considered limits: (1) maximum allowable temperature for top layer (1200?C) and (2) for blade material (1000?C). The model can be used to analyze other materials that support higher temperatures helping in the development of new materials for thermal barrier coatings.
Exergy analysis of scroll compressors working with R22, R407C, and R417A as refrigerant for HVAC system
Authors: Kalaiselvam Sivakumar , Saravanan Ragupathy
Published: May 2009

The rise in crisis of power enthralls the world economically and the options for conventional and non-conventional energy resources have been searched out. No system exists in this world with 100% efficiency due to several irreversibility's. If the output obtained from the system is maximum for a given input, maximum amount of energy can be saved globally. To understand the thermodynamic losses occurring in the system and to predict the available energy that can be tapped from the system, exergy plays a major role. Experimental study on exergy in a system can pave the way to understand the complete behavior of the system exergually. Conceptually exergy studies are based on simulation, to provide a new dimension to the concept of exergy experimental validation have been promoted. The analogy of exergy analysis of three refrigerants working in scroll compressors and their exergual features are explained in this paper. The refrigerants R22, R417A, and R407C and their thermo dynamical behavior, irreversibility were experimented in an air conditioning system with three scroll compressors, interaction between the system and the refrigerant in terms of pressure drop and heat transfer, friction has been implemented for the calculation of exergy. The entire system performance on the basis of refrigerant is validated in each part of the air conditioning system. The resultant coefficient of performance of R407C is 2.41% less than R22 in a R22 designed scroll compressor with minimal exergy losses. The second law efficiency of 50 to 55% obtained in R22 has fewer rules over R407C and R417A which has 48 to 52%. The diminutive deviation of results encourages R417A refrigerant to be used as a substitute for R22. Thus the exergual prediction of performance of refrigerant and second law efficiency can identify the use of eco-friendly refrigerant in scroll compressor.
Numerical study of a modified Trombe wall solar collector system
Authors: Dragicevic Snezana , Lambic Miroslav
Published: May 2009

The paper presents numerical analysis of efficiency of the modified Trombe wall with forced convection. The analyzed system comprises a double glass glazing, and a massive wall with opening and central channel in it. In order to increase the efficiency, a fan is provided at the bottom vent of the wall. It is more advanced as compared with simple Trombe solar wall with a relatively low thermal resistance, which is taken as a reference in experimental analysis. The mathematical model, composed for the massive solar wall efficiency, is usually very complicated and assessment of the thermal behavior requires the use of thermal simulation techniques. This paper presents steady-state and one-dimensional mathematical model for simplified analysis of thermal efficiency of modified Trombe solar wall. The results from presented model were analyzed to predict the effects of variations in the operational parameters on the solar wall efficiency: solar radiation intensity, air velocity in the entrance duct, and room air temperature. The results have been compared with the available experimental study, and the comparison has shown satisfactory agreement. The obtained results have be used for simple and fast running design tools that designers can use in the early phases of the design process for approximate calculations of efficiency of the passive solar heating systems.
An energy and exergy study of a solar thermal air collector
Authors: Mohseni-Languri Ehsan , Taherian Hessam , Masoodi Reza , Reisel John
Published: May 2009

A solar flat plate air collector was manufactured in the north of Iran, and connected to a room as the model to study the possibility of using such solar heating systems in the northern parts of Iran. This collector was tested as a solar air heater to see how good it could be for warming up the test room during the winter. The experimental data obtained through accurate measurements were analyzed using second law approach to find the optimum mass flow rate, which leads to the maximum exergy efficiency. It was found that for the test setup at the test location, a mass flow rate of 0.0011 kg/s is the optimum mass flow rate for tested conditions which leads to the highest second law efficiency.
Evaluation of the efficacy of different feed additives to adsorbe T-2 toxin in vitro
Authors: Nesic Vladimir , Ostojin Mirjana , Nesic Ksenija , Resanovic Radmila
Published: May 2009

In the trial, in vitro HPTLC - High Performance Thin Layer Chomatography was used to determine the amount of 'free', i.e. unbound or non-decomposed T-2 toxin. Mean adsorption or degradation levels of T-2 toxin in examined feed aditives, in in vitro conditions, ranged from 26.06 to 34.84% and did not significantly differ among used adsorbents: inorganic (Minazel plus - Mz), organic (Mycosorb - Ms) and mixed (Micofyx - Mf). All these additives showed better adsorption ability in the acidic environment (pH3).
Mycotoxic porcine nephropathy and spontaneous occurrence of ochratoxin A residues in kidneys of slaughtered swine
Authors: Milicevic Dragan , Juric Verica , Dakovic Aleksandra , Jovanovic Miljan , Stefanovic Srdjan , Petrovic Zoran
Published: May 2009

In order to find information on the occurrence of mycotoxic porcine nephropathy in Serbia, during a six month period (2006/2007) samples of kidney from individual healthy slaughtered pigs were collected (n=90) and analyzed by HPLC for ochratoxin A. In addition, histological examinations were carried out. The incidence of OTA in kidney was 33,3% and varied between 0.17-52.5 ng/g. Histopathological examination of kidneys confirmed tubulopathies with oedema and cell vacuolization. In addition, hemorrhages and necrosis of proximal kidney tubules cells were found. These findings indicate that it is likely that most of the kidney injury is related to ochratoxin A and other nephrotoxic compounds which enhance the toxicity of OTA.
Influence of pelleting on microbiological and mycotoxical correctness of feed mixtures with bentonite supplement
Authors: Adamovic Milan , Bocarov-Stancic Aleksandra , Pantic Vladimir , Radivojevic Mihailo , Adamovic Ivana , Stojanovic Bojan
Published: May 2009

Influence of pelleting calf feed mixtures supplemented with bentoni on microbiological and mycotoxicological properties was investigated. Microbiological and mycotoxicological quality was investigated at the production day (day 0) and after 45 days of storage. Total count of microorganisms in the pelleted mixture, at the day 0 (280.000/g), was several times lower than in the powdered mixture (2.000.000/g). Similar results were obtained at day 45 when the total number of microorganisms in the pelleted mixture was 270.000/g and 1.800.000/g in the powdered mixture. Number of yeasts and molds at the production day in the pelleted mixture was 650/g, and in the powdered mixture it was 27.000/g. Similar results were obtained 45 days later when the number of yeasts and molds in the pelleted mixture was 540/g, and 16.000/g in the powdered mixture. There were 6 species identified in the pelleted mixture, and 9 species in the powdered mixture at the day of production. Similar mold species ratio in the pelleted (11) and powdered mixture (13) was found at day 45. In the examined samples representatives of Fusarium genus - F. subglutinans i F. verticillioides dominated. Number of sultite-redzcing clostridia in the mixtures, in both observed periods, was similar (below 1000/g of sample). By mycotoxicological analysis of mixtures at the production day, only trichotecene (T-2 toxin) presence was found in amount of 0,337 mg/kg. The applied technological procedure of pelleting with bentonite supplement, had positive influence on the improvement of microbiological and toxicological properties of mixture.
Effect of mint (Mentha piperita L.) and caraway (Carum carvi L.) on the growth of some toxigenic aspergillus species and aflatoxin B1 production
Authors: Skrinjar Marija , Mandic Anamarija , Misan Aleksandra , Sakac Marijana , Saric Ljubisa , Zec Marija
Published: May 2009

An inhibitory effect of various concentrations (0.0, 0.5, 1.0, 1.5 and 2,0%) of mint (Mentha piperita L.) and caraway (Carvum carvi L.) on the growth of A. fumigatus, A. flavus and A. ochraceus was examined during 10 days of cultivation in YES medium at temperature of 25?C. Mint showed stronger inhibitory effect than caraway. Total dry weight (g/l) after 10 days of the growth of A. fumigatus in YES medium with 0.5% of mint decreased by about 95%, A. flavus by 97% and A. ochraceus by about 82%. Addition of higher concentrations of mint (1.0, 1.5 and 2.0%) reduced the growth of all tested species. It was poor and hardly visible. pH values of the media increased with the increase of mint concentrations. A. fumigatus showed the highest sensitivity towards caraway and A. flavus the lowest. Total dry weight (g/l) after 10 days of growth of A. fumigatus in medium with 0.5% of caraway decreased by about 72% in comparison to the control. In media with higher concentrations of caraway, its growth was found to be very poor. Concentration of 1.0% of caraway reduced A. flavus growth by 15% and of 1.5% by 92%, in regard to the control. In medium with 2.0% of caraway the growth of A. flavus was observed as poor and hardly visible. The growth of A. ochraceus in medium with 0.5% of caraway decreased by about 85% comparing with control and further decrease was noticed by the increase of concentrations. In medium with 1.5% of caraway a reduction of about 95% of growth was found and under 2.0% of caraway it was poor. pH of the media also increased with the increase of caraway concentrations. Applied concentrations of mint and caraway inhibited completely the production of AB1 by A. flavus.
Bipolaris sorokiniana (teleomorph Cochliobolus Sativus): Causer of barley leaf lesions and root rot in Macedonia
Authors: Karov Ilija , Mitrev Sasa , Kostadinovska Emilija
Published: May 2009

Diseased barley plants (Hordeum vulgare), were noticed in the area of Kumanovo, Bitola, Probistip, Skopje and Kocani, at the beginning of March, 2006. Our investigations were carried out in the period from 2006 to 2009. The plants were highly diseased, probably in the stage of germination, dwarfed with necrotic leaves and with poorly developed root. A rotten root collar was noticed notice in some plants, which could be easily pulled out from the soil. Plants infected in a later developing stage became yellow from the top of the leaf, and many brown-olive, oval shape lesions were noticed. Conidia of Bipolaris sorokiniana (Sacc.) Shoen., were isolated from symptomatic lesions. Pseudothecia with asci and ascospores from teleomorph Cochliobolus sativus, were found on the barley straw in the same field the previous year.
Mineral fertilizers as a governing factor of the regulation of the number of fungi in soil
Authors: Pesakovic Marijana , Djukic Dragutin , Mandic Leka , Rakicevic Milan , Miletic Rade
Published: May 2009

Over 2003-2005 period, a study was performed on the effect of different rates of NPK fertilizer of formulation 8:16:24 + 3% MgO (N1 - 400 kg ha-1; N2 - 600 kg ha-1; N3 - 800 kg ha-1; N4 - 1000 kg ha-1) on development of the soil fungi. The trial was set up in the experimental plum orchard established by Fruit Research Institute Cacak, and the laboratory of Department of Microbiology, Faculty of Agronomy Cacak. Unfertilized soil was used as the control soil. Each of the stated variants was carried out in three replications. The size of the basic plot was 68 m2. The effect of the studied mineral fertilizer rates was determined three times over the growing season, the number of fungi being checked by the indirect rarefaction method on Chapek nutritive medium. The results of the study inferred that the application of mineral fertilizers brought about the decrease in the number of fungi. Of all studied variants, the one with the highest nitrogen rate (variant N4) exhibited the strongest effect. The influence of the fertilizer was highest at the third sampling. Furthermore, the effect was highest in season 2003.
Growth and fruit body formation of Pleurotus ostreatus on media supplemented with inorganic selenium
Authors: Savic Milena , Petrovic Jelena , Klaus Anita , Niksic Miomir , Rajkovic Milos , Filipovic Nenad , Antic-Mladenovic Svetlana
Published: May 2009

Selenium is a trace mineral chemically related to sulfur and tellurium. In the body selenium combines with protein molecules to form selenoproteins and it is distributed in low concentrations and unequally in air, soil and water all over the world. Edible mushrooms are known to be selenium accumulators. Since mushrooms contain relatively high protein levels, and they can accumulate large amounts of selenium, it is reasonable to expect that selenium could be incorporated into proteins. The growth of mycelia and fruit body formation of different medicinal mushroom strains of Pleurotus ostreatus (Hk-35 and P70) over the wide range of concentrations of inorganic form of selenium were examined. Mushrooms were cultivated on agar base media and on substrates based on sawdust. Vegetative growths of mycelium were measured as colony diameter in pure cultures supplemented with inorganic form of Se supplements, prepared as Na2SeO4 and Na2SeO3 in concentrations of: 1, 10, 25, 50, 75, 100 and 150 mg/l. Inorganic form of Se supplements, showed stimulation effects (in concentration of 1-50 mg/l) and toxic effects in higher concentration. On the standard industrial sawdust based substrate, supplemented with 100 mg/kg Na2SeO4 and Na2SeO3, accumulation of Se in fruit bodies was determined by the method of flameless atomic absorption spectrophotometer. The readings were performed on Varian SpectrAA-10 spectrophotometer equipped with VGA-76. Se as Na2SeO4 and Na2SeO3 was effectively taken up from substrates and accumulated in fruit bodies. Mushrooms accumulated selenium between 120 and 250 mg/kg dry weight. In mushrooms cultivated without Se supplement, Se contents were only about 1 mg/kg and in substrate about 0.1 mg/kg.
Influence of bioactive compounds extracted from mushroom Ganoderma lucidum on B and T cells
Authors: Klaus Anita , Kozarski Maja , Niksic Miomir
Published: May 2009

Ganoderma lucidum (Leyss.: Fr.) Karst is one of the most often used mushrooms in traditional medicine of Far Eastern people. Because of its bitter taste and wooden build it is not suitable for nutrition, but the bioactive substances extracted from this mushroom possess very important medicinal characteristics. The aim of this experiment was to investigate the effects of different concentrations of isolated Ganoderma lucidum GL-I extract on the growth of JY (B) and Jurkat (T) cells. Obtained extracts were added to the cells in concentrations 1 mg/ml, 100 ng/ml, 10 ng/ml, 1 ng/ml and 100 pg/ml. JY and Jurkat cells were exposed to the action of bioactive compounds, b-glucans, during the incubation period of 72 h, at 37?C, in the atmosphere with 5% CO2 and their number was counted. Among all tested concentrations of extract the most important influence showed concentration of 1 mg/ml, which reduced the number of B cells by 61.46%, while in the case of T cells their number was reduced by 57.14%.
Dermatomycosis: A potential source of zoonotic infection in cities
Authors: Stojanov Igor , Prodanov Jasna , Pusic Ivan , Ratajac Radomir
Published: May 2009

Skin infections in animals and humans represent a complex syndrome that is, from etiological point of view, often hard to solve. Skin is one of the largest organs and plays an important role in the organism of mammals. Depending on the age, it presents 5-8% of total body mass in humans, 12% of adult animals, and even up to 24% in newly born animals. The population of pets and stray dogs in cities provides a possibility for contacts between animals and/or humans, which is a mode of transmission for some diseases. Fungal diseases in dogs caused by dermatophyte are zoonosis, contagious infections that affect dogs and cats, but also other animals, as well as humans. There has been an overall increase in the number of the cases caused by anthropophilic fungi from the strain of Microsporum spp. and Trichophyton spp. Our research was related to animals with different changes on skin manifested by hairless surfaces, dandruff, red skin and extensive pruritus. The objective of our examination was the analyses of scarified samples and swob from canine skin with the aim to determine whether the changes were caused by dermatophytosis. Our aim was to point out the possibility of transmission of mycotic infections from animals to humans in households. For this mycological examination swobs and skin scarifications from dogs, were used. The samples were streaked on Sabo and dextrose agar and incubated at 25?C for at least 21 days. In one year period 81 samples were collected out of which 11 (13.58%) were positive for dermatophyte. In all samples Microsporum canis was isolated. The findings of Microsporum canis in 13.58% of the examined samples indicate the importance of mycological skin disorder in pets. Having in mind that this is a zoonosis, the findings point to a possibility of exposing the humans to fungal infection, affecting almost all pet owners, especially in urban environment.
Effect of yeast storage temperature and flour composition on fermentative activities of baker's yeast
Authors: Pejin Dusanka , Grujic Olgica , Pejin Jelena , Kocic-Tanackov Suncica
Published: May 2009

Baker's yeast is a set of living cells of Saccharomyces cerevisiae. It contains around 70-72% of water, 42-45% of proteins, around 40% of carbohydrates, around 7.5% of lipids (based on dry matter), and vitamin B-complex. On the basis of yeast cell analysis it can be concluded that yeast is a complex biological system which changes in time. The intensity of the changes depends on temperature. Yeast sample was stored at 4?C i 24?C for 12 days. During storage at 4?C, the content of total carbohydrates decreased from 48.81% to 37.50% (dry matter), whereas carbohydrate loss ranged from 40.81% to 29.28% at 24?C. The content of trehalose was 12.33% in the yeast sample stored at 4?C and 0.24% at 24?C. Loss of fermentative activity was 81.76% in the sample stored at 24?C for 12 days. The composition of five samples of 1st category flour was investigated. It was found that flours containing more reducing sugars and maltose enable higher fermentation activities. The flours with higher ash content (in the range 0.5-0.94%) had higher contents of phytic acid. Higher ash and phytic contents in flour increased the yeast fermentative efficiency. In bakery industry, a range of ingredients has been applied to improve the product's quality such as surface active substances (emulsifiers), enzymes, sugars and fats. In the paper, the effect of some ingredients added to dough (margarine, saccharose, sodium chloride and malted barley) on the yeast fermentative activity was studied. The mentioned ingredients were added to dough at different doses: 0.5, 1.0, 1.5 and 2.0%, flour basis. It was found that the investigated ingredients affected the fermentative activity of yeast and improved the bread quality.
Ethanol production using Saccharomyces cerevisiae cells immobilised on corn stem ground tissue
Authors: Vucurovic Vesna , Razmovski Radojka , Popov Stevan
Published: May 2009

Cell immobilisation in alcoholic fermentation has been extensively studied during the past few decades because of its technical and economical advantages over those of free cell systems. A biocatalyst was prepared by immobilising a commercial Saccharomyces cerevisiae strain (baker yeast) on corn stem ground tissue for use in alcoholic fermentation. For this purpose, the yeast cells were submitted to the batch tests 'in situ' adsorption onto pieces of the corn stem ground tissue. Cells immobilisation was analysed by optical microscopy. It was determined that the addition of the corn stem ground tissue led to an increase of the pH value, total dissolved salts content, and sugar content in fermentation medium. The addition of 5 and 10g of the corn stem ground tissue per liter of medium, increased ethanol yield, decreased amount of residual sugar and the cells immobilisation was effective. Corn stem is one of the abundant, available, inexpensive, stable, reusable, nontoxic celulosic biomaterial with high porosity, which facilitates the transmission of substrates and products between carrier and medium. The prepared immobilised biocatalyst showed higher fermentation activity than free cells. The results indicate that corn stem might be an interesting support for yeast cell immobilisation, and also a cheap alternative recourse of mineral components with possibility of application for improving ethanol productivities.
A Comparison of ICT Knowledge and Usage among Female Distance Learners in Endowed and Deprived Communities of a Developing Country
Authors: Kwapong Olivia Adwoa Tiwaah Frimpong
Published: May 2009

Working with the premise that information and communications technology (ICT) has the capacity to make or unmake so far as women's empowerment is concerned, this article looks at the ICT situation among female distance learners in both endowed and under-served parts of Ghana, to check the user differentials among the two contrasting groups through a survey that covered 174 respondents. From the results one could not strongly say that there were vast ICT knowledge and usage gaps among the two groups considering the extent of the developmental gap that the regional differences presents. Factors like time or convenience, space, and income have to be considered in using ICT for education and development among women. Exposing the women to multiple usages of ICT is also critical. Another core observation from this study is that women who are generally categorized as not being technology friendly are overcoming at least that. This applies not only to women in relatively well-endowed areas but also to those in under-served areas. This is a good starting point for undertaking gender-specific projects that will promote e-learning, e-government, e-medicine, e-commerce and all other applications among women in both urban and rural communities.
Providing Operational Definitions to Quality Constructs for E-Learning in Higher Education
Authors: Usoro Abel , Abiagam Bridget
Published: May 2009

New developments in information and communication technologies (ICT) to support learning have brought about increasing interest by both academic and non-academic institutions in e-learning. These developments in ICT are principally multimedia and the Internet with its World Wide Web. Interest in ICT supported learning is also fuelled by the associated (expected) cost reduction and easy expansion of education to the increasing and flexible market that is difficult to reach by traditional delivery. Expansion of e-learning, especially in higher education, raises the issue of quality, resulting in both anecdotal and empirical evidence of how to achieve high quality while at the same time benefiting from e-learning. After examining key current research, the authors developed a conceptual framework of nine factors of quality in e-learning in higher education. These factors include content, delivery, technical provision (referred to as tangibles) and globalisation. This article takes the research further by attempting to operationalise the nine factors and develop a questionnaire such that future work can undertake a primary study to validate the framework.
Cyber-Relations in the Field of Home Computer Use for Leisure: Bourdieu and Teenage Technological Experts
Authors: Johnson Nicola F.
Published: May 2009

This article highlights the practice of a group of New Zealand teenagers who are considered by their family and themselves to be technological experts. Drawing on Pierre Bourdieu's key concepts of habitus, field and capital, this text identifies and discusses the cyber-relations that constitute the practice in the field of home computer use for leisure. The purpose of this article is to claim that though this field is predominantly a field of leisure, these are valid sites of informal learning. As almost all of the experts in the study gained their expertise through independent means, with minimal input from their schooling, discussion focuses on what these informal trajectories to technological expertise might mean for pedagogy and formal learning within schools.
Cost Optimization in E-Learning-Based Education Systems: Implementation and Learning Sequence
Authors: Fazlollahtabar Hamed , Yousefpoor Narges
Published: May 2009

Increasing the effectiveness of e-learning has become one of the most practically and theoretically important issues within both educational engineering and information system fields. The development of information technologies has contributed to growth in online training as an important education method. The online training environment enables learners to undertake ‘any time, any place’ customized training. Moreover, information technology allows both trainers and learners to be decoupled in terms of time, place, and space. There is a competence set consisting of ideas, knowledge, information, and skills for making a decision. In order to effectively acquire the needed skills in the competence set to solve the problem, finding appropriate learning sequences for decision makers should be taken into account. However, the means for determining the learning cost of learning one skill in relation to another skill plays a critical role for generating learning sequences. This article addresses the identification of varied cost elements as well as cost optimization in e-learning educational systems using mathematical programming. An effective method for estimating the learning cost between any two skills by using grey relational analysis and a radial basis function network is then proposed. An integer programming method is employed to demonstrate that it is possible to facilitate the acquisition of single skills by considering a set of useful compound skills.
Clinical Utility of the 2-Minute Walk Test for Older Adults Living in Long-Term Care
Authors: Connelly D.M. , Thomas B.K. , Cliffe S.J. , Perry W.M. , Smith R.E.
Published: May 2009

Purpose: This study's purposes were to examine the measurement properties of the 2-minute walk test (2MWT), to illustrate the use of reliability coefficients in clinical practice, and to estimate sample size for a subsequent validity study.

Method: Sixteen residents of long-term care (LTC; mean age = 87 years) completed two 2MWTs with Rater A and two 2MWTs with Rater B on test days 1 and 2, approximately 1 week apart. On a third test day, subjects completed one trial of the Berg Balance Scale (BBS), timed up-and-go (TUG) test, and 6-minute walk test (6MWT) with Rater A. On 2 other test days, approximately 1 week apart, Rater A administered the 2MWT to five older adults living in a retirement facility. Absolute and relative reliability and concurrent and known-groups validity coefficients were calculated.

Results: No main effect for rater, trial, or occasion was found. Test–retest reliability estimates of 0.94 and 0.95 were obtained. The 2MWT demonstrated concurrent validity (r ≥ 0.84) with the BBS, TUG, and 6MWT. Comparison of distance walked by LTC and retirement residents showed a difference of 72.9 m (95% CI: 44.2, 101.6). The results suggest that 90% of truly stable older adults will display random fluctuations in 2MWT performance within a boundary of 15 m.

Conclusion: The 2MWT had sound measurement properties in this sample of LTC residents. Based on our results, 24 subjects would be required for a subsequent hypothesis-testing validity study.
El Chile de las regiones: una historia inconclusa
Authors: Arenas Federico
Published: May 2009

Las regiones chilenas tienen una historia que se remonta a varias décadas, desde los primeros intentos de establecer una regionalización en Chile en los años cincuenta, hasta la instalación de los denominados Gobiernos Regionales el año 1993. Sin embargo, la lectura crítica del proceso de regionalización y sobre todo de la descentralización, muestra que más allá de los innumerables avances, todavía estamos lejos de representar como país, un modelo de estado unitario desconcentrado. En este trabajo se revisan los hitos más importantes del desarrollo institucional chileno a la escala regional, con el fin de establecer el nivel de avance y los desafíos pendientes del país en esta materia.
Eliminación de arsénico mediante flotación por adsorción coloidal utilizando flóculos de Fe(OH)3 en un sistema de flotación por aire disuelto
Authors: Pavez O. , Palacios J. M. , Aguilar C.
Published: May 2009

En el presente trabajo se estudió el efecto de la relación Fe/As sobre la eliminación de arsénico aplicando flotación por adsorción coloidal en aguas con distintos contenidos de arsénico. Como coagulante se utilizó cloruro férrico y dodecil sulfato de sodio como colector, y las soluciones fueron preparadas con trióxido de arsénico. Los resultados obtenidos muestran que el rango de pH 4-5,5 es el más adecuado para la eliminación de arsénico, aumentando el porcentaje de eliminación con el incremento de la concentración inicial de Fe(III) en la solución. Por otra parte, a medida que disminuye la concentración inicial de arsénico en la solución se requiere una mayor proporción de Fe/As para su eliminación. Además, se mostró que para soluciones conteniendo 13,73 mg/l, 1,71 mg/l y 0,105 mg/l de As, se necesitan relaciones Fe/As de 6:1, 18:1 y 800:1 para lograr una eliminación de arsénico desde la solución del orden de 95 %.
Procesos de fabricación de metales celulares. Parte II: Vía sólida, deposición de metales, otros procesos
Authors: Fernández P. , Cruz L. J. , Coleto J.
Published: May 2009

En la primera parte de esta revisión se realizó la descripción de los procesos empleados por vía líquida para la fabricación de metales celulares. En esta segunda parte, se describen los procesos correspondientes a la vía sólida y la deposición de metales. De igual manera, se revisan los diferentes métodos, en cada caso, haciendo una breve descripción de los principales parámetros involucrados y las ventajas y desventajas en cada uno de ellos.
Glycohistochemical study of the toadfish Halobatrachus didactylus (Scheider, 1801) stomach
Authors: Desantis Salvatore , Acone Franca , Zizza Sara , Deflorio Michele , Palazón Fernández Josè Luis , Sarasquete Carmen , De Metrio Gregorio
Published: May 2009

Toadfish Halobatrachus didactylus gastric mucosa was studied using conventional and lectin histochemistry. Conventional histochemistry revealed neutral glycoconjugates predominating over acidic ones in the apical zone of both surface epithelial cells and pit cells. The neck cells contained a few neutral glycoconjugates, whereas gastric glands were negative to PAS and AB staining. Lectin histochemistry showed different oligosaccharide expression along the columnar cells. The sub-nuclear cytoplasm was stained with RCA120, SBA, HPA, GSA I-B4, GSA II, UEA I, LTA, Con A, KOH-sialidase-WGA. The Golgi zone reacted with RCA120, DBA, SBA, HPA, KOH-sialidase-WGA, GSA I-B4, GSA II, UEA I, LTA, MAL II, SNA, and showed an increase in DBA staining after KOH-sialidase treatment. The granules of the apical zone stained with PNA, UEA I, LTA and showed increased PNA reactivity after KOH-sialidase treatment. The luminal cell coat reacted with PNA, HPA, Con A, KOH-sialidase-WGA, UEA I, LTA, MAL II, SNA and KOH-sialidase-PNA. Pit cells showed a minor expression of lectin-binding sites with respect to columnar cells. Neck cells linked UEA I and LTA and gastric glands reacted with PNA, DBA, SBA, HPA, Con A, GSA I-B4, KOH-sialidase-WGA and KOH-sialidase-DBA. The results suggest that the stomach of the toadfish H. didactylus is characterised by a species-specific glycoconjugate pattern.