999 resultados para Impurity states


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In the last few years, hydrostatic pressure has been extensively used in the study of both protein folding and misfolding/aggregation. Compared to other chemical or physical denaturing agents, a unique feature of pressure is its ability to induce subtle changes in protein conformation, which allow the stabilization of partially folded intermediate states that are usually not significantly populated under more drastic conditions (e.g., in the presence of chemical denaturants or at high temperatures). Much of the recent research in the field of protein folding has focused on the characterization of folding intermediates since these species appear to be involved in a variety of disease-causing protein misfolding and aggregation events. The exact mechanisms of these biologicalphenomena, however, are still poorly understood. Here, we review recent examples of the use of hydrostatic pressure as a tool to obtain insight into the forces and energetics governing the productive folding or the misfolding and aggregation of proteins.

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The world’s population is growing at a rapid rate and one of the primary problems of a growing is food supply. To ensure food supply and security, the biggest companies in the agricultural sector of the United States and all over the world have collaborated to produce genetically modified organisms, including crops, that have a tendency to increase yields and are speculated to reduce pesticide use. It’s a technology that is declared to have a multitude of benefits. During the same time period another set of practices has risen to the horizon by the name of agroecology. It spreads across many different sectors such as politics, sociology, environment, health and so on. Moreover, it involves primitive organic techniques that can be applied at farm level to enhance the performance of an ecosystem to effectively decrease the negative effect on environment and health of individuals while producing good quality foods. Since both the processes proclaim sustainable development, a natural question may come in mind that which one seems more favorable? During the course of this study, genetically modified organisms (GMOs) and agroecology are compared within the sphere of social, environmental and health aspects. The results derived upon a comparative analysis of scientific literature tend to prove that GMOs pose a greater threat to the environment, health of individuals and the generalized social balance in the United States compared to agroecological practices. Economic indicators were not included in the study and more studies might be needed in the future to get a broader view on the subject.

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In this work emission, optical, electrical and magnetic properties of the d- and f- elements doped zinc selenide crystals were investigated within a wide temperature range. Doping was performed in various technological processes: during the growth by chemical vapor transport method; by thermal diffusion from the Bi or Zn melt. Concentration of the doping impurity in the crystals was controlled by amount of the dopant in the source material or by its concentration in the doping media. Special interest in the work was paid to the influence of the different concentrations of Cr and Yb impurities on ZnSe crystals’ properties, correlations between observed effects and similarities with the Ni, Mn and Gd dopants are analysed. Possibility of formation of the excitons bound to the doping d-ions was shown. In contrast to this, it was observed that f-elements do not bound excitons, but prevent formation of excitons bound to some uncontrolled impurities. A mechanism of Cr doping impurity interaction with background impurities and zinc selenide structural defects was proposed based on experimental data. An assumption about resonant energy transfer between double charged chromium ions and complexes based on crystals’ vacancy defects was made. A correlation between emission and magnetic properties of the d- ions doped samples was established. Based on this correlation a mechanism explaining the concentration quench of the emission was proposed. It was found that f-ions bind electrically active shallow and deep donor and acceptor states of background impurity to electrically neutral complexes. This may be observed as “purification” of ZnSe crystals by doping with the rare-earth elements, resulting i tendency of the properties of f-ion doped crystals to the properties of intrinsic crystals, but with smaller concentration of uncontrolled native and impurity defects. A possible interpretation of this effect was proposed. It was shown that selenium substituting impurities decrease efficiency of the Yb doping. Based on this experimental results an attempt to determine ytterbium ion surroundings in the crystal lattice was made. It was shown that co-doping of zinc selenide crystals with the d- and f- ions leads to the combination of the impurities influence on the material’s properties. On the basis of obtained data an interaction mechanism of the d- and f-elements co-dopants was proposed. Guided by the model of the ytterbium ion incorporation in the selenide sublattice of the ZnSe crystals, an assumption about stabilization of single charged chromium ions in the zinc sublattice crystal nodes, by means of formation of the local charge compensating clusters, was made.

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The structure and optical properties of thin films based on C60 materials are studied. Reproducible vacuum method of thin fullerene films production with Cd impurity on Si, glass and mica surfaces is developed. Surface morphology of the films are investigated by AFM and SEM methods. The ab initio quantum - chemical calculations of the geometry, total energy and excited energy states of complex fullerene- cadmium telluride supramolecules are performed. Photoluminescence spectra of composite thin films based on C60 before and after X-ray irradiation were measured. The intensity of additional peaks is defined as the charge composition due to the type of substrate. These results are interpreted as an appearance of the dipole-allowed transitions in the fullerene excited singlet states spectrum cause of an interference with cadmium telluride. X-ray irradiated films were investigated, and additional peaks in photoluminescence spectra were detected. These peaks appear as a result of molecular complexes formation from C60CdTe mixture and dimerization of the films. Density functional B3LYP quantum-chemical calculations for C60CdTe, molecular complexes, (C60)2 and C120O dimers were performed to elucidate some experimental results.

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Rough turning is an important form of manufacturing cylinder-symmetric parts. Thus far, increasing the level of automation in rough turning has included process monitoring methods or adaptive turning control methods that aim to keep the process conditions constant. However, in order to improve process safety, quality and efficiency, an adaptive turning control should be transformed into an intelligent machining system optimizing cutting values to match process conditions or to actively seek to improve process conditions. In this study, primary and secondary chatter and chip formation are studied to understand how to measure the effect of these phenomena to the process conditions and how to avoid undesired cutting conditions. The concept of cutting state is used to address the combination of these phenomena and the current use of the power capacity of the lathe. The measures to the phenomena are not developed based on physical measures, but instead, the severity of the measures is modelled against expert opinion. Based on the concept of cutting state, an expert system style fuzzy control system capable of optimizing the cutting process was created. Important aspects of the system include the capability to adapt to several cutting phenomena appearing at once, even if the said phenomena would potentially require conflicting control action.

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Bipolar disorder (BD) is a common psychiatric mood disorder affecting more than 1-2% of the general population of different European countries. Unfortunately, there is no objective laboratory-based test to aid BD diagnosis or monitor its progression, and little is known about the molecular basis of BD. Here, we performed a comparative proteomic study to identify differentially expressed plasma proteins in various BD mood states (depressed BD, manic BD, and euthymic BD) relative to healthy controls. A total of 10 euthymic BD, 20 depressed BD, 15 manic BD, and 20 demographically matched healthy control subjects were recruited. Seven high-abundance proteins were immunodepleted in plasma samples from the 4 experimental groups, which were then subjected to proteome-wide expression profiling by two-dimensional electrophoresis and matrix-assisted laser desorption/ionization-time-of-flight/time-of-flight tandem mass spectrometry. Proteomic results were validated by immunoblotting and bioinformatically analyzed using MetaCore. From a total of 32 proteins identified with 1.5-fold changes in expression compared with healthy controls, 16 proteins were perturbed in BD independent of mood state, while 16 proteins were specifically associated with particular BD mood states. Two mood-independent differential proteins, apolipoprotein (Apo) A1 and Apo L1, suggest that BD pathophysiology may be associated with early perturbations in lipid metabolism. Moreover, down-regulation of one mood-dependent protein, carbonic anhydrase 1 (CA-1), suggests it may be involved in the pathophysiology of depressive episodes in BD. Thus, BD pathophysiology may be associated with early perturbations in lipid metabolism that are independent of mood state, while CA-1 may be involved in the pathophysiology of depressive episodes.

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Video games industry has recently bonded California and Finland in a new way and where the employers are recruiting they also need to be aware of the provisions and procedures related to terminations. In general, collective dismissals are on a relatively high level both in Finland and in California. In California, collective redundancies are regulated under the WARN law. The WARN obligates employers with 75 or more employees to give a 60-day notice prior to a mass lay off and some other similar events. Employers with less than 75 employees are free to administer the terminations without the WARN notice period. Generally, the California at-will presumption allows employment relationship to be terminated any day with or without reason and without notice period if conditions of collective agreements or employment contract do not limit this right. Termination cannot anyhow be in violation of the anti-discrimination law. In Finland the termination related provisions are part of the Employment Contracts Act and the Act on Co-operation within Undertakings. Collective redundancies are allowed under financial and production related grounds. Small employers with less than 20 employees follow the termination provisions of the Employment Contracts Act and are obligated to inform the employee to be terminated on the details of the termination itself and also the services of the Employment and Economic Development Office. Employers with 20 or more employees are to initiate co-operation procedure under the Act on Co-operation within Undertakings when reducing personnel. The co- operation negotiations are to inform employees on the employer’s plans and financial situation as well as to involve them in the decision making regarding the terminations. The employer’s duty to inform the employees of the services of Employment and Economic Development Office needs to be fulfilled also in terminations under the co-operation procedure. Discrimination is prohibited in Finland in terminations of employment. As an alternative for terminations, employees can for example be transferred to another position or be temporarily laid off. Employer’s duties related to search of alternatives for layoff are broader in Finland than in California. The recent development of the labor laws in Finland and in California suggests that the labor law is not static in either one of these environments but changes can be expected as the needs of the business life so require.

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Finnish companies cross listing in the United States is an exceptional phenomenon. This study examines the cross listing decision, cross listing choice and cross listing process with associated challenges and critical factors. The aim is to create an in-depth understanding of the cross listing process and the required financial information. Based on that, the aim is to establish the process phases with the challenges and the critical factors that ought to be considered be- fore establishing the process plus re-evaluated and further considered at points in time during the process. The empirical part of this study is conducted as a qualitative study. The research data was collected through the adoption of two approaches, which are the interview approach and the textual data approach. The interviews were conducted with Finnish practitioners in the field of accounting and finance. The textual data was from publicly available publications of this phenomenon by the two BIG5 accounting companies worldwide. The results of this study demonstrate the benefits of cross listing in the U.S. are the better growth opportunities, the reduction of cost of capital and the production of higher quality financial information. In the decision making process companies should assess whether the benefits exceed the increased costs, the pressure for performance, the uncertainty of market recognition and the requirements of management. The exchange listing is seen as the most favourable cross listing choice for Finnish companies. The establishment of the processes for producing reliable, transparent and timely financial information was seen as both highly critical and very challenging. The critical success factors relating to the cross listing phases are the assessment and planning as well as the right mix of experiences and expertise. The timing plays important role in the process. The results mainly corroborate the literature concerning cross listing decision and choice. This study contributes to the literature on the cross listing process offering a useful model for the phases of the cross listing process.

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Today the Washington Consensus on development lies in tatters. The recent history of the developing world has been unkind to the core claim that a nation that opens its economy and keeps government's role to a minimum invariably experiences rapid economic growth. The evidence against this claim is strong: the developing world as a whole grew faster during the era of state intervention and import substitution (1950-1980) than in the more recent era of structural adjustment (1990-2005); and the recent economic performance of both Latin America and Sub-Saharan Africaregions that truly embraced neoliberalismhas lagged well behind that of many Asian economies, which have instead pursued judicial and unorthodox combinations of state intervention and economic openness. As scholars and policy makers reconstruct alternatives to the Washington Consensus on development, it is important to underline that prudent and effective state intervention and selective integration with the global economy have been responsible for development success in the past; they are also likely to remain the recipes for upward mobility in the global economy in the future."

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The aim of this paper is to analyze the relation between economic growth and labor market dynamics in Brazil between 1981 and 2009, making a comparison with the United States. Among the findings, one can mention that economic growth in Brazil has been related to a massive incorporation of labor force in labor intensive activities, whereas, in the United States, to a substantial improvement of labor productivity in high-technology activities. Despite the favorable economic context in the 2000s, huge inequalities between these countries have widened since the structure of the Brazilian labor market remained with few or no changes.