451 research outputs found

    Solar and biomass hybridization through hydrothermal carbonization

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    Hydrothermal carbonization process can transform wet bio-wastes into value-added products. This work aims to hybridize a concentrating solar technology and a biomass reactor for the continuous and sustainable valorization of biomass. The novel technology proposed integrates a linear beam-down solar field with a twin-screw reactor for continuous HTC process. The solar field consists of two reflections that concentrate linearly the sun energy on the ground, where the twin-screw reactor is placed. A mathematical model is proposed to solve both the heat transfer and HTC kinetics for a co-rotating twin-screw reactor. The incoming heat flux from the solar field (8-20 kW/m(2)), the reactor length (L/D = 30-60 where D is the diameter) and the rotating velocity of the screw (25-100 rpm) are the main variables used to process the biomass up to the desired severity factor. The simulation results of different lignocellulosic biomasses (loblolly pine, sugarcane bagasse, corn stover and rice husk) are validated against literature data. The developed model shows good agreement with experimental results shown in the literature. The proposed technology foresees hydrochar yields of 64-78% for severity factors of 4.2 and 5.3, respectively, in agreement to the experimental results of 63-70% shown in literature. (C) 2021 Elsevier Ltd. All rights reserved

    Quasi-Exact Solvability and the direct approach to invariant subspaces

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    We propose a more direct approach to constructing differential operators that preserve polynomial subspaces than the one based on considering elements of the enveloping algebra of sl(2). This approach is used here to construct new exactly solvable and quasi-exactly solvable quantum Hamiltonians on the line which are not Lie-algebraic. It is also applied to generate potentials with multiple algebraic sectors. We discuss two illustrative examples of these two applications: an interesting generalization of the Lam\'e potential which posses four algebraic sectors, and a quasi-exactly solvable deformation of the Morse potential which is not Lie-algebraic.Comment: 17 pages, 3 figure

    An?lisis de los elementos cr?ticos para el desarrollo de proveedores en empresas de la gran miner?a en el Per?

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    En esta investigaci?n se describen las caracter?sticas de los elementos cr?ticos para el desarrollo de proveedores en empresas de la gran miner?a en el Per?. Como parte de la gesti?n de las relaciones con proveedores, las empresas realizan desarrollo de proveedores cuando participan activamente en esfuerzos para mejorar el desempe?o y capacidades de sus proveedores. Sobre la base del marco de referencia para el desarrollo de proveedores de Sucky y Durst (2013), se definen las variables que describen las condiciones influyentes, factores de ?xito, estrategias e impactos del desarrollo de proveedores en una muestra de seis empresas representativas de la gran miner?a peruana. Para ello se realizan entrevistas semiestructuradas a ejecutivos de log?stica, compras y contratos, as? como revisiones de reportes de sostenibilidad y otros documentos. El estudio concluye que la estrategia de las empresas es desarrollar las capacidades de sus proveedores locales, con el objetivo de mantener una buena relaci?n con las comunidades de sus ?reas de influencia directa. La baja capacidad del proveedor local representa la principal condici?n influyente, y la actitud estrat?gica hacia el proveedor es el principal factor de ?xito. Finalmente, el desarrollo de proveedores tiene impactos positivos en las empresas y en sus proveedores locales

    Suppression of Tc in the (Y0.9Ca0.1)Ba2Cu4-xFexO8 system

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    In this paper, the effects produced by the iron substitutions in the (Y0.9Ca0.1)Ba2Cu4-xFexO8 system on the superconducting and structural properties are studied. The Rietveld fit of the crystal structure and Mossbauer spectroscopy results of (Y0.9Ca0.1)Ba2Cu4-xFexO8 samples indicate that, the iron atoms occupy the Cu(1) sites of the (Cu-O)2 double chain in fivefold coordination at low iron concentrations. Besides at high iron concentrations the iron atoms occupy the Cu(1) sites of single Cu-O chainss and Cu(2) sites in the CuO2 planes of the (Y0.9Ca0.1)Ba2Cu4-xFexO8 phase with structural defects. Simultaneouly, as iron concentration increases, a faster decrease of Tc is observed in this material comapred with the YBa2Cu3-xFexO7-y system. According to the charge transfer model proposed for YBa2Cu4O8 under pressure, the decrease in the Cu(1)-O(4) bond length in parallel to the increase in the Cu(2)-O(4) bond length may affect the charge transfer mechanism leading to the suppression of Tc.Comment: submitted to Journal of Physics: Condensed Matter on 12 October 2001, 8 figures, 2 tables, 9 page

    Employment Expectations and Gross Flows by Type of Work Contract

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    There is growing interest in understanding firms’ temporary and permanent employment practices and how institutional changes shape them. Using data on Spanish establishments, we examine: (a) how employers adjust temporary and permanent job and worker flows to prior employment expectations, and (b) how the 1994 and 1997 labour reforms promoting permanent employment affected establishments’ employment practices. Generally, establishments’ prior employment expectations are realized through changes in all job and worker flows. However, establishments uniquely rely on temporary hires as a buffer to confront diminishing long-run employment expectations. None of the reforms significantly affected establishments’ net temporary or permanent employment flows.http://deepblue.lib.umich.edu/bitstream/2027.42/40032/3/wp646.pd

    Detection and dynamics of circulating tumor cells in patients with high-risk prostate cancer treated with radiotherapy and hormones: a prospective phase II study

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    BACKGROUND: Circulating tumor cells (CTCs) are an established prognostic marker in castration-resistant prostate cancer but have received little attention in localized high-risk disease. We studied the detection rate of CTCs in patients with high-risk prostate cancer before and after androgen deprivation therapy and radiotherapy to assess its value as a prognostic and monitoring marker. PATIENTS AND METHODS: We performed a prospective analysis of CTCs in the peripheral blood of 65 treatment-naive patients with high-risk prostate cancer. EpCAM-positive CTCs were enumerated using the CELLSEARCH system at 4 timepoints. A cut off of 0 vs >/= 1 CTC/7.5 ml blood was defined as a threshold for negative versus positive CTCs status. RESULTS: CTCs were detected in 5/65 patients (7.5%) at diagnosis, 8/62 (12.9%) following neoadjuvant androgen deprivation and 11/59 (18.6%) at the end of radiotherapy, with a median CTC count/7.5 ml of 1 (range, 1-136). Only 1 patient presented a positive CTC result 9 months after radiotherapy. Positive CTC status (at any timepoint) was not significantly associated with any clinical or pathologic factors. However, when we analyzed variations in CTC patterns following treatment, we observed a significant association between conversion of CTCs and stages T3 (P = 0.044) and N1 (P = 0.002). Detection of CTCs was not significantly associated with overall survival (P > 0.40). CONCLUSIONS: Our study showed a low detection rate for CTCs in patients with locally advanced high-risk prostate cancer. The finding of a de novo positive CTC count after androgen deprivation therapy is probably due to a passive mechanism associated with the destruction of the tumor. Further studies with larger samples and based on more accurate detection of CTCs are needed to determine the potential prognostic and therapeutic value of this approach in non-metastatic prostate cancer. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT01800058

    Naturally presented HLA class I-restricted epitopes from the neurotrophic factor S100-? are targets of the autoimmune response in type 1 diabetes

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    Type 1 diabetes (T1D) results from the destruction of pancreatic beta-cells by the immune system, and CD8(+) T lymphocytes are critical actors in this autoimmune response. Pancreatic islets are surrounded by a mesh of nervous cells, the peri-insular Schwann cells, which are also targeted by autoreactive T lymphocytes and express specific antigens, such as the neurotrophic factor S100-beta. Previous work has shown increased proliferative responses to whole S100-beta in both human T1D patients and the nonobese diabetic (NOD) mouse model. We describe for the first time naturally processed and presented epitopes (NPPEs) presented by class I human leukocyte antigen-A*02:01 (A2.1) molecules derived from S100-beta. These NPPEs triggered IFN-gamma responses more frequently in both newly diagnosed and long-term T1D patients compared with healthy donors. Furthermore, the same NPPEs are recognized during the autoimmune response leading to diabetes in A2.1-transgenic NOD mice as early as 4 wk of age. Interestingly, when these NPPEs are used to prevent diabetes in this animal model, an acceleration of the disease is observed together with an exacerbation in insulitis and an increase in S100-beta-specific cytotoxicity in vaccinated animals. Whether these can be used in diabetes prevention needs to be carefully evaluated in animal models before use in future clinical assays.-Calvino-Sampedro, C., Gomez-Tourino, I., Cordero, O. J., Reche, P. A., Gomez-Perosanz, M., Sanchez-Trincado, J. L., Rodriguez, M. A., Sueiro, A. M., Vinuela, J. E., Calvino, R. V. Naturally presented HLA class I-restricted epitopes from the neurotrophic factor S100-beta are targets of the autoimmune response in type 1 diabetes

    Mejoramiento de muros de contenci?n, veredas, escaleras y recuperaci?n de espacios p?blicos Asentamiento Humano Vi?a Alta, distrito de La Molina - Lima

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    La presente tesis tiene como objetivo general elaborar el Plan para el Comit? de Gesti?n, que se ha formado para la Direcci?n del Proyecto: ?Mejoramiento de Muros de Contenci?n, Veredas, Escaleras y Recuperaci?n de Espacios P?blicos en el AA.HH. Vi?a Alta, Distrito de La Molina ? Lima?. Asimismo, tiene como objetivos espec?ficos: - Desarrollar el acta de constituci?n del proyecto. - Identificar a los grupos de inter?s del proyecto. - Detallar el alcance del proyecto. - Desarrollar los planes de gesti?n subsidiarios del proyecto. - Realizar la integraci?n de todos los planes de gesti?n. - Cuantificar, evaluar y registrar las lecciones aprendidas en la gesti?n del proyecto
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