962 resultados para continuous process, fermentation


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A procedure for measuring the overheating temperature (ΔT ) of a p-n junction area in the structure of photovoltaic (PV) cells converting laser or solar radiations relative to the ambient temperature has been proposed for the conditions of connecting to an electric load. The basis of the procedure is the measurement of the open-circuit voltage (VO C ) during the initial time period after the fast disconnection of the external resistive load. The simultaneous temperature control on an external heated part of a PV module gives the means for determining the value of VO C at ambient temperature. Comparing it with that measured after switching OFF the load makes the calculation of ΔT possible. Calibration data on the VO C = f(T ) dependences for single-junction AlGaAs/GaAs and triple-junction InGaP/GaAs/Ge PV cells are presented. The temperature dynamics in the PV cells has been determined under flash illumination and during fast commutation of the load. Temperature measurements were taken in two cases: converting continuous laser power by single-junction cells and converting solar power by triple-junction cells operating in the concentrator modules.

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Acute promyelocytic leukemia (APL) is associated with chromosomal translocations always involving the RARα gene, which variably fuses to one of several distinct loci, including PML or PLZF (X genes) in t(15;17) or t(11;17), respectively. APL in patients harboring t(15;17) responds well to retinoic acid (RA) treatment and chemotherapy, whereas t(11;17) APL responds poorly to both treatments, thus defining a distinct syndrome. Here, we show that RA, As2O3, and RA + As2O3 prolonged survival in either leukemic PML-RARα transgenic mice or nude mice transplanted with PML-RARα leukemic cells. RA + As2O3 prolonged survival compared with treatment with either drug alone. In contrast, neither in PLZF-RARα transgenic mice nor in nude mice transplanted with PLZF-RARα cells did any of the three regimens induce complete disease remission. Unexpectedly, therapeutic doses of RA and RA + As2O3 can induce, both in vivo and in vitro, the degradation of either PML-RARα or PLZF-RARα proteins, suggesting that the maintenance of the leukemic phenotype depends on the continuous presence of the former, but not the latter. Our findings lead to three major conclusions with relevant therapeutic implications: (i) the X-RARα oncoprotein directly determines response to treatment and plays a distinct role in the maintenance of the malignant phenotype; (ii) As2O3 and/or As2O3 + RA combination may be beneficial for the treatment of t(15;17) APL but not for t(11;17) APL; and (iii) therapeutic strategies aimed solely at degrading the X-RARα oncoprotein may not be effective in t(11;17) APL.

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Onboarding is an important aspect of the employment process that has been often ignored. Overlooked onboarding results in high turnover costs, totaling up to 30 to 50 percent of an employee's first-year pay. To decrease this turnover and its associated high costs, this paper proposes the implementation of a highly strategic onboarding process. This process has a strategic focus, SMART goals, integrates multiple offices and people, and addresses all new employee needs with two considerations, generational and technological advances. An employee stays continuously and actively engaged, with vested interest in success, maximizing engagement and retention. The process focuses on constant and continuous feedback from all stakeholders. The project is a practical guide for implementing a new strategically focused onboarding process.

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The selective production of 2-methyltetrahydrofuran from levulinic acid has been effectively conducted using designed Cu based catalysts and compared with a commercial Pd/C system under microwave irradiation. Optimised conditions for the most active catalysts Cu-MINT (>90% conversion, 75% selectivity to MTHF) and Pd/C (78% conversion, 92% selectivity to MTHF) were further translated into a continuous flow process using the proposed catalysts to find out the deactivation of Cu-MINT under flow conditions (79 vs. 13% conversion with a switch in selectivity to products after 30 min in flow), the high stability of Pd/C (73 vs. 70% conversion at stable selectivity under analogous conditions to those of Cu-MINT) but, most importantly, different relevant pathways to valuable products from levulinic acid depending on the type of catalyst employed.

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The optimization of chemical processes where the flowsheet topology is not kept fixed is a challenging discrete-continuous optimization problem. Usually, this task has been performed through equation based models. This approach presents several problems, as tedious and complicated component properties estimation or the handling of huge problems (with thousands of equations and variables). We propose a GDP approach as an alternative to the MINLP models coupled with a flowsheet program. The novelty of this approach relies on using a commercial modular process simulator where the superstructure is drawn directly on the graphical use interface of the simulator. This methodology takes advantage of modular process simulators (specially tailored numerical methods, reliability, and robustness) and the flexibility of the GDP formulation for the modeling and solution. The optimization tool proposed is successfully applied to the synthesis of a methanol plant where different alternatives are available for the streams, equipment and process conditions.

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We present a derivative-free optimization algorithm coupled with a chemical process simulator for the optimal design of individual and complex distillation processes using a rigorous tray-by-tray model. The proposed approach serves as an alternative tool to the various models based on nonlinear programming (NLP) or mixed-integer nonlinear programming (MINLP) . This is accomplished by combining the advantages of using a commercial process simulator (Aspen Hysys), including especially suited numerical methods developed for the convergence of distillation columns, with the benefits of the particle swarm optimization (PSO) metaheuristic algorithm, which does not require gradient information and has the ability to escape from local optima. Our method inherits the superstructure developed in Yeomans, H.; Grossmann, I. E.Optimal design of complex distillation columns using rigorous tray-by-tray disjunctive programming models. Ind. Eng. Chem. Res.2000, 39 (11), 4326–4335, in which the nonexisting trays are considered as simple bypasses of liquid and vapor flows. The implemented tool provides the optimal configuration of distillation column systems, which includes continuous and discrete variables, through the minimization of the total annual cost (TAC). The robustness and flexibility of the method is proven through the successful design and synthesis of three distillation systems of increasing complexity.

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Comunicación presentada en CIDUI 2010, Congreso Internacional Docencia Universitaria e Innovación, Barcelona, 30 junio-2 julio 2010.

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We present an extension of the logic outer-approximation algorithm for dealing with disjunctive discrete-continuous optimal control problems whose dynamic behavior is modeled in terms of differential-algebraic equations. Although the proposed algorithm can be applied to a wide variety of discrete-continuous optimal control problems, we are mainly interested in problems where disjunctions are also present. Disjunctions are included to take into account only certain parts of the underlying model which become relevant under some processing conditions. By doing so the numerical robustness of the optimization algorithm improves since those parts of the model that are not active are discarded leading to a reduced size problem and avoiding potential model singularities. We test the proposed algorithm using three examples of different complex dynamic behavior. In all the case studies the number of iterations and the computational effort required to obtain the optimal solutions is modest and the solutions are relatively easy to find.

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Among the factors that affect the convergence towards the European Higher Education Area, university teaching staff's motivation is fundamental, and consequently, it is crucial to empirically know what this motivation depends on. In this context, one of the most relevant changes in the teacher-student relationship is assessment. In fact, the transition from a static assessment -focused on only one temporal point (final exam)- to a dynamic assessment, will require changes in thought and action, both on the part of teachers and students. In this line, the objective of this paper is to analyze the determinants of teaching staff's predisposition to the continuous assessment method. Specifically, we consider the following explanatory dimensions: teaching method used (which measures their degree of involvement with the ongoing adaptation process), type of subject (core, compulsory and optional), and teacher's personal characteristics (professional status and gender). The empirical application carried out at the University of Alicante uses Logit Models with Random Coefficients to capture heterogeneity, and shows that "cooperative learning" is a clear-cut determinant of "continuous assessment" as well as "continuous assessment plus final examination". Also, a conspicuous result, which in turn becomes a thought-provoking finding, is that professional status is highly relevant as a teacher's engagement is closely related to prospects of stability. Consequently, the most relevant implications from the results revolve around the way academic institutions can propose and implement inducement for their teaching staff.

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Among the factors that affect the convergence towards the European Higher Education Area, university teaching staff's motivation is fundamental, and consequently, it is crucial to empirically know what this motivation depends on. In this context, one of the most relevant changes in the teacher-student relationship is assessment. In fact, the transition from a static assessment -focused on only one temporal point (final exam)- to a dynamic assessment, will require changes in thought and action, both on the part of teachers and students. In this line, the objective of this paper is to analyze the determinants of teaching staff's predisposition to the continuous assessment method. Specifically, we consider the following explanatory dimensions: teaching method used (which measures their degree of involvement with the ongoing adaptation process), type of subject (core, compulsory and optional), and teacher's personal characteristics (professional status and gender). The empirical application carried out at the University of Alicante uses Logit Models with Random Coefficients to capture heterogeneity, and shows that "cooperative learning" is a clear-cut determinant of "continuous assessment" as well as "continuous assessment plus final examination". Also, a conspicuous result, which in turn becomes a thought-provoking finding, is that professional status is highly relevant as a teacher's engagement is closely related to prospects of stability. Consequently, the most relevant implications from the results revolve around the way academic institutions can propose and implement inducement for their teaching staff.

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Retraining the labor force to match the demands of a modem economy is seen as an important task during the transition process from a centrally-planned to a market economy. This need was particularly pressing in East Germany, because the transition process has proceeded much faster than in the rest of Eastern Europe. Therefore, substantial resources have been devoted to this purpose. This paper analyzes the impact of continuous off-the-job training in East Germany from the point of view of individuals who were part of the labor force before German unification in 1990. It tries to answer questions about the average gains from participating in a specific type of training. Typical outcomes considered to measure those gains are income, employment status, job security, and expected future changes in job position. The methodology used for the evaluation is the potential outcome approach to causality. This approach has received considerable attention in the statistical literature over the last fifteen years and it has recently been rediscovered by the econometric literature as well. It is adapted to allow for important permanent and transitory shocks, such as unemployment, which influence the decision to participate in the training as well as future labor market outcomes. The empirical part is based on the first four waves of the Socio-Economic Panel (GSOEP)-East (1990-1993). This panel data set has the advantage that the fourth wave contains a special survey on continuous training and that it allows keeping track of individual behavior on a monthly, respectively yearly, basis. The econometric analysis focuses on off-the-job training courses that began after unification and were completed not later than in early 1993. Although it is obviously too early to evaluate the long-term implications, the results suggest that there are no positive effects in the short run.

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Since the beginning of its existence in the form of communities, the European Union’s decision-making process underwent constant evolution. There were continuous adjustments that transformed a pure intergovernmental process into one having rather federal features. Based on the hypothesis that changes have occurred at the decision level in regards to the actors, procedures, influence and ways of taking decisions in order for the new realities, needs and will at the European level to be properly addressed, this paper aims to present the reforms performed through the adoption of new treaties and the modification of the existing ones. The reality is that in order for the European dream and integration to go on and also for further development of the European Union, finally becoming an entity far beyond the founders expectations, decision makers had to constantly and carefully adapt the decision-making process. The purpose of this paper will be achieved by conducting a research based on the qualitative method, analyzing the related researches on this topic and the consolidated versions of the treaties. Thus, we will finally validate our research hypothesis that there was an evolution in what the EU’s decision-making process and decision procedures are concerned.

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"The Corey H. Continuous Improvement Process is the ongoing collection and analysis of information for all entities serving children with disabilities to determine compliance with applicable state and federal requirements."--P. [1].

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Rhizopus arrhizus, strain DAR 36017, produced L(+)-lactic acid in a simultaneous saccharification and fermentation process using starch waste effluents. Lactic acid at 19.5 - 44.3 g l(-1) with a yield of 0.85 - 0.96 g g(-1) was produced in 40 h using 20 - 60 g starch l(-1). Supplementation of nitrogen source may be unnecessary if potato or corn starch waste effluent was used as a production medium.

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The fungal species of Rhizopus oryzae 2062 has the capacity to carry out a single stage fermentation process for lactic acid production from potato starch wastewater. Starch hydrolysis, reducing sugar accumulation, biomass formation, and lactic acid production were affected with variations in pH, temperature, and starch source and concentration. A growth condition with starch concentration approximately 20 g/L at pH 6.0 and 30degreesC was favourable for starch fermentation, resulting in a lactic acid yield of 78.3%similar to85.5% associated with 1.5similar to2.0 g/L fungal biomass produced in 36 h of fermentation.