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991.
Antonio Perejón Pedro E. Sánchez-Jiménez Carlos Soria-Hoyo José Manuel Valverde José Manuel Criado Luis A. Pérez-Maqueda 《Journal of the American Ceramic Society》2019,102(3):1338-1346
The potential of controlled rate thermal analysis (CRTA) for studying high-pressure gas-solid processes has been evaluated. CRTA is a type of smart temperature program based on a feedback system that uses any experimental signal related to the process evolution for commanding the temperature evolution. In this work, an instrument that uses the gravimetric signal for CRTA control has been designed and used for the study of two high-pressure gas-solid reactions: the highly exothermic thermal oxidation of TiC under high pressure of oxygen and the reduction in Fe2O3 under high pressure of hydrogen. Advantages of CRTA for discriminating overlapping processes and appraising kinetic reaction mechanisms are shown. 相似文献
992.
993.
994.
Geise Camila de Araujo Ribeiro Pedro Fernandes 《Chemical Engineering Communications》2018,205(8):1060-1068
The present paper focuses on the production and characterization of inulinase produced by Pseudozyma sp. (CCMB 306) and on the subsequent immobilization of this enzyme on solid supports (eggshell, celite, Sepabeads®, silica). A primary aim of the present study was to investigate the effects of glucose and yeast extract concentrations (g/L) on the enzyme produced by Pseudozyma sp. according to response surface methodology (RSM). RSM was also used to study the optimum pH and temperature. The results for the optimization of inulinase production showed that the highest enzyme activity was observed for glucose and yeast extract concentrations of 10 and 1?g/L, respectively. The inulinase activity peaked at 50°C and pH 7.0. The results for enzyme immobilization on solid supports showed that celite, in an incubation medium containing acetone, was the best support for inulinases produced by Pseudozyma sp. 相似文献
995.
Professor Pedro Manuel Calas Lopes Pacheco Paula S. F. Oliveira Dr Ricardo A.A. Aguiar DSc. Professor Silvio De Barros 《The Journal of Adhesion》2015,91(10-11):883-908
Shape memory alloys (SMAs) present the capability to develop large forces and displacements with low power consumption. Due their special characteristics, SMAs have been used in many different applications. Pseudoelastic hysteresis loop observed in austenitic SMAs is associated with energy dissipation. Therefore, pseudoelastic SMA elements can be used as vibration attenuators. Joining methods present some technological challenges for the use of these elements. Welding can strongly affect the properties of the alloy. Mechanical joints using rivets and screws are commonly used but promote stress concentration effects. The use of adhesives offers some benefits, being an alternative to be investigated. This work presents a numerical model based on the finite-element method and experimental procedures to study the behaviour of bonded vibration attenuators with SMA elements. The proposed model considers the pseudoelastic behaviour of SMA elements, and a cohesive zone model was used to study the union between absorber and an aluminium plate. Finally, several loading conditions were analysed with the proposed models to assess the capability of bonded pseudoelastic SMA elements to dissipate energy. The proposed geometry allows the elements to actuate as an efficient vibration attenuator, in particular when submitted to axial loading. 相似文献
996.
Cristina Fernandez‐Barranco Africa Yebra‐Rodriguez M. Dolores La Rubia‐Garcia Francisco J. Navas‐Martos Pedro Alvarez‐Lloret 《Polymer Composites》2015,36(12):2326-2333
Polyamide66 (PA66) and polyamide66/sepiolite (PA66/sepiolite) nanocomposites at 1, 3, 5, 7, and 9 wt% clay loading were prepared and injected to simulate industrial processing. Tensile tests were performed in the samples, and scanning electron microscopy was used to characterize the fracture surface. The samples were also examined by X‐ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), and vibrational spectroscopy analysis (FT‐IR and FT‐Raman). Higher tensile strength and stiffness and reduction of the strain to failure are observed in the nanocomposites with higher sepiolite content. Two‐dimensional XRD analyses show that the sepiolite also enhances the orientation of PA66 crystals. XRD and spectroscopic analyses corroborate that the nanoclay fibers are placed between the lamellar superstructure of the PA66 without affecting the polymer chains. DSC confirms that the presence of sepiolite does not influence the crystallinity nor the nucleation of PA66 as the arrangement of the fibers between the PA66 lamellae hinders the nucleation of new crystals. We propose a model for the crystallographic organization of the organic and inorganic phases in the PA66/sepiolite nanocomposites. POLYM. COMPOS., 36:2326–2333, 2015. © 2014 Society of Plastics Engineers 相似文献
997.
Pedro Rivero-Antúnez Rafael Cano-Crespo Florentino Sánchez-Bajo Arturo Domínguez-Rodríguez Víctor Morales-Flórez 《Journal of the European Ceramic Society》2021,41(11):5548-5557
This work presents a fast and direct controlled routine for the fabrication of fully dense alumina based on the reactive spark plasma sintering (reactive-SPS) of boehmite (γ-AlOOH) nano-powders obtained by the sol–gel technique. The evolution of the transition aluminas during sintering has been studied. Some boehmite powders were seeded with α-Al2O3 particles prior to the gelation. Boehmite seeded powders exhibited a direct transition to α-Al2O3 at 1070 °C, enhancing the transformation kinetics and lowering the required temperature by more than 100 °C. For comparison, other samples were prepared by previously annealing the seeded and unseeded boehmite powders. Thus, α-Al2O3 powders were obtained and were sintered by standard-SPS. A detailed structural and mechanical characterization is presented, comparing the hardness and indentation fracture resistance for different grain sizes and porosities. Both the reactive-SPSed samples and the standard-SPSed samples showed a high hardness (18–20 GPa), whereas the reactive-SPSed samples exhibited a lower indentation fracture resistance due to a large grain size (~10 μm). Improvements of this procedure for obtaining smaller grain size are discussed. In summary, the presented technique brings a revolutionary fast method for the fabrication of fully dense alumina, as this process reduces the time and temperature required for alumina densification. 相似文献
998.
Sara Becerril Roberto Corchado-Cobos Natalia García-Sancha Leonor Revelles David Revilla Tatiana Ugalde Concepcin Romn-Curto Jesús Prez-Losada Javier Caueto 《International journal of molecular sciences》2021,22(10)
Advances in virology and skin cancer over recent decades have produced achievements that have been recognized not only in the field of dermatology, but also in other areas of medicine. They have modified the therapeutic and preventive solutions that can be offered to some patients and represent a significant step forward in our knowledge of the biology of skin cancer. In this paper, we review the viral agents responsible for different types of skin cancer, especially for solid skin tumors. We focus on human papillomavirus and squamous cell cancers, Merkel cell polyomavirus and Merkel cell carcinoma, and human herpesvirus 8 and Kaposi’s sarcoma. 相似文献
999.
Paula Alonso-Ramos David lvarez-Melo Katerina Strouhalova Carolina Pascual-Silva George B. Garside Meret Arter Teresa Bermejo Rokas Grigaitis Rahel Wettstein Marta Fernndez-Díaz Joao Matos Marco Geymonat Pedro A. San-Segundo Jesús A. Carballo 《International journal of molecular sciences》2021,22(18)
Meiotic defects derived from incorrect DNA repair during gametogenesis can lead to mutations, aneuploidies and infertility. The coordinated resolution of meiotic recombination intermediates is required for crossover formation, ultimately necessary for the accurate completion of both rounds of chromosome segregation. Numerous master kinases orchestrate the correct assembly and activity of the repair machinery. Although much less is known, the reversal of phosphorylation events in meiosis must also be key to coordinate the timing and functionality of repair enzymes. Cdc14 is a crucial phosphatase required for the dephosphorylation of multiple CDK1 targets in many eukaryotes. Mutations that inactivate this phosphatase lead to meiotic failure, but until now it was unknown if Cdc14 plays a direct role in meiotic recombination. Here, we show that the elimination of Cdc14 leads to severe defects in the processing and resolution of recombination intermediates, causing a drastic depletion in crossovers when other repair pathways are compromised. We also show that Cdc14 is required for the correct activity and localization of the Holliday Junction resolvase Yen1/GEN1. We reveal that Cdc14 regulates Yen1 activity from meiosis I onwards, and this function is essential for crossover resolution in the absence of other repair pathways. We also demonstrate that Cdc14 and Yen1 are required to safeguard sister chromatid segregation during the second meiotic division, a late action that is independent of the earlier role in crossover formation. Thus, this work uncovers previously undescribed functions of the evolutionary conserved Cdc14 phosphatase in the regulation of meiotic recombination. 相似文献
1000.
Cristina Romo-Valera Pedro Guerrero Jon Arluzea Jaime Etxebarria Koro de la Caba Noelia Andollo 《International journal of molecular sciences》2021,22(7)
The vision impairments suffered by millions of people worldwide and the shortage of corneal donors show the need of substitutes that mimic native tissue to promote cell growth and subsequent tissue regeneration. The current study focused on the in vitro assessment of protein-based biomaterials that could be a potential source for corneal scaffolds. Collagen, soy protein isolate (SPI), and gelatin films cross-linked with lactose or citric acid were prepared and physicochemical, transmittance, and degradation measurements were carried out. In vitro cytotoxicity, cell adhesion, and migration studies were performed with human corneal epithelial (HCE) cells and 3T3 fibroblasts for the films’ cytocompatibility assessment. Transmittance values met the cornea’s needs, and the degradation profile revealed a progressive biomaterials’ decomposition in enzymatic and hydrolytic assays. Cell viability at 72 h was above 70% when exposed to SPI and gelatin films. Live/dead assays and scanning electron microscopy (SEM) analysis demonstrated the adhesion of both cell types to the films, with a similar arrangement to that observed in controls. Besides, both cell lines were able to proliferate and migrate over the films. Without ruling out any material, the appropriate optical and biological properties shown by lactose-crosslinked gelatin film highlight its potential for corneal bioengineering. 相似文献