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991.
Laura Fasce Josefina Cura Gerardo García Bermúdez Patricia Frontini 《Surface & coatings technology》2010,204(23):3887-3894
Generation of wear debris is the principal obstacle limiting the durability of ultra-high molecular weight polyethylene (UHMWPE) in biomedical applications. Aiming to enhance UHMWPE wear resistance, surface modification with swift heavy ion irradiation (SHI) appears as a potential and attractive methodology. Contrary to ion implantation techniques, the swift heavy ions range can reach tens to hundreds microns and its extremely high linear energy is able to induce effective chemical modifications using low fluence values. Nano-wear performance and surface mechanical properties of samples of pristine and SHI irradiated (using N2+ ions at 33 MeV and a fluence of 1 × 1012 ions/cm2) were characterized by depth sensing indentation (DSI) and scanning probe microscopy (SPM). It turned out that modifications induced by irradiation at the surface layers were successful to reduce nano-wear volume and creep deformation. These improvements were related to beneficial changes in hardness, elastic modulus, hardness to elastic modulus ratio and friction coefficient. 相似文献
992.
Carbon nanotube (CNT)/diamond composite has been fabricated by hot filament chemical vapor deposition on a silicon substrate using iron as catalyst. The material characteristics of this monolithic structure were examined by electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and electron energy loss spectroscopy. The composite material shows the presence of carbon nanotubes of several microns in length together with conspicuous diamond microcrystals of sizes ranging from 0.5 to 2.0 μm. The CNTs protrude from the diamond microcrystals and become entangled around them as they grow. This monolithic CNT/diamond composite provides an intrinsic heat dissipation mechanism for CNTs during field emission and exhibits low turn on field, large field enhancement factor, and an excellent current stability over a period of 44 h. 相似文献
993.
J.A. Fernández-Madrigal L. Llopis A. Cruz-Martín C. Galindo J. González-Jiménez 《Computer Standards & Interfaces》2013,35(1):30-49
This paper presents H, a minimalistic specification language for designing heterogeneous software applications, particularly in the realms of robotics and industria, which takes advantage of a Component-Based Software Engineering (CBSE) approach. H copes with some of the most outstanding characteristics of these systems, like diversity at different levels (hardware platforms, programming languages, programmer skills), network distribution, real time and fault-tolerance. The H specification covers the life-cycle of any heterogeneous application. Its development system offers to the designer and/or builder a set of tools for specifying modules, generating code semiautomatically, debugging, maintenance, and a real time analysis of the system. 相似文献
994.
Daniel de Santos Víctor Lorente Félix de la Paz José Manuel Cuadra José R. Álvarez-Sánchez Eduardo Fernández José M. Ferrández 《Robotics and Autonomous Systems》2010,58(12):1223-1230
This paper introduces an open-source real-time system that remotely controls a robot using human neuroblastoma cultures and a client–server architecture. Multielectrode array set-ups have been designed for direct culturing of neural cells over silicon or glass substrates, providing the capability simultaneously to stimulate and record populations of neural cells. However, it is very difficult to attach these neural cells to the robot structure due to the special conditions of the biological material. The main objective of this research is to build a client–server system for remotely connecting a robot to a neural culture in a closed-loop experimentation. The robot sensors will feed the biological neuroprocessor, while the neural activity will be used for guiding the robot, controlling in this way the robotic behaviour. 相似文献
995.
Rodríguez-Manzo G.; Pellicer F.; Larsson K.; Fernández-Guasti A. 《Canadian Metallurgical Quarterly》2000,114(3):553
The aim of the present study was to establish whether electrical and/or drug stimulation of the medial preoptic area/anterior hypothalamus (mPOA/AH) surmounts the sexual behavior inhibition that results from copulation to exhaustion. Thus, intermittent electrical stimulation of the mPOA/AH (alone or combined with the systemic injection of yohimbine or apomorphine, at doses that were subthreshold for reversing sexual exhaustion) or intrapreoptic treatments to block GABAergic transmission were applied to sexually satiated rats. The results suggest that the mPOA/AH is not responsible for male sexual behavior inhibition or for the pharmacologically induced sexual behavior expression in satiated rats. Data are discussed in terms of the roles ascribed to the mPOA/AH, both in the control of sexual behavior expression and in the regulation of the postejaculatory interval. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
996.
Matias Estaras Manuel R. Gonzalez-Portillo Miguel Fernandez-Bermejo Jose M. Mateos Daniel Vara Gerardo Blanco-Fernandez Diego Lopez-Guerra Vicente Roncero Gines M. Salido Antonio Gonzlez 《International journal of molecular sciences》2021,22(11)
In certain diseases of the pancreas, pancreatic stellate cells form an important part of fibrosis and are critical for the development of cancer cells. A hypoxic condition develops within the tumor, to which pancreatic stellate cells adapt and are able to proliferate. The consequence is the growth of the tumor. Melatonin, the product of the pineal gland, is gaining attention as an agent with therapeutic potential against pancreatic cancers. Its actions on tumor cells lead, in general, to a reduction in cell viability and proliferation. However, its effects on pancreatic stellate cells subjected to hypoxia are less known. In this study, we evaluated the actions of pharmacological concentrations of melatonin (1 mM–1 µM) on pancreatic stellate cells subjected to hypoxia. The results show that melatonin induced a decrease in cell viability at the highest concentrations tested. Similarly, the incorporation of BrdU into DNA was diminished by melatonin. The expression of cyclins A and D also was decreased in the presence of melatonin. Upon treatment of cells with melatonin, increases in the expression of major markers of ER stress, namely BIP, phospho-eIF2α and ATF-4, were detected. Modulation of apoptosis was noticed as an increase in caspase-3 activation. In addition, changes in the phosphorylated state of p44/42, p38 and JNK MAPKs were detected in cells treated with melatonin. A slight decrease in the content of α-smooth muscle actin was detected in cells treated with melatonin. Finally, treatment of cells with melatonin decreased the expression of matrix metalloproteinases 2, 3, 9 and 13. Our observations suggest that melatonin, at pharmacological concentrations, diminishes the proliferation of pancreatic stellate cells subjected to hypoxia through modulation of cell cycle, apoptosis and the activation of crucial MAPKs. Cellular responses might involve certain ER stress regulator proteins. In view of the results, melatonin could be taken into consideration as a potential therapeutic agent for pancreatic fibrosis. 相似文献
997.
Elena Sánchez-Zapata Juana Fernández-López José A. Pérez-Alvarez José Soares Sergio Sousa Ana M.P. Gomes Manuela M.E. Pintado 《Food and Bioproducts Processing》2013,91(3):279-286
Tiger nut milk (“horchata”) liquid co-products (TNLC) were evaluated as carbon source for probiotic bacteria (Lactobacillus acidophilus and Bifidobacterium animalis) growth by screening via microplate assay and determination of viable cells and metabolic activity. Based on MRS five different basal media were prepared ((i) without carbon source, (ii) with 2% (w/v) glucose, (iii) with 2% (w/v) FOS, (iv) with 2% (v/v) TNLC and (v) 3% (v/v) TNLC). Additionally, reconstituted TNLC was also used as basal medium. For determination of viable cells and metabolic activity skim milk powder was used. Glucose was found to be the best substrate to L. acidophilus grows, followed by FOS and TNLC (2% and 3%, respectively). TNLC (3%) was found to be the best substrate followed by TNLC (2%), glucose and FOS, in the promotion of growth of B. animalis. The growth of L. acidophilus and B. animalis in skim milk reconstituted TNLC + water was higher than samples inoculated in skim milk reconstituted only with water (p < 0.05). This is supported by the pH effect and by the faster organic acid production (mainly lactic acid, acetic acid, and butyric acid), confirming the property of TNLC as a carbon source for probiotic bacteria growth. 相似文献
998.
Films plasticized with glycerine were prepared using chitosan with two different molecular weights (Mw), 780 and 430 kDa. Films were obtained by drying at 80 and 40°C at 20 and 40% relative humidity (RH) in a climatic chamber. Drying kinetics were established by the measurement of the evolution of the actual temperatures of the film forming solutions. Chitosan Mw did not show any significant influence on drying kinetics. Drying temperature affected drying kinetics in a more intense way than drying RH. Maximum tensile strength (86 MPa) and elongation at break (56.5%) were obtained with slow drying cycles (lower drying T) and when higher Mw chitosan was employed. Minimum water vapor permeability (0.59 g · mm/kPa · h · m) was achieved for films dried at faster drying cycles (higher drying T). Chitosan Mw was not a significant factor affecting water vapor permeability. 相似文献
999.
The dynamical behaviour for a generic two-dimensional model of a continuous bioreactor is studied in this article. The state variables for the bio-reacting system are restricted to concentrations of substrate and biomass, where the specific growth rate is a smooth function of the substrate concentration, which can be a kinetic function, monotone or non-monotone (as Monod, Haldane, Teissier, etc.). The effect of input (dilution rate) on multiplicity and bifurcation of equilibrium is shown in open-loop configuration. The absence of limit cycles on open-loop configuration and through state-feedback on the dilution rate are demonstrated. The aim of analysing oscillations under state feedback control is related to the possible improvement of reactor yields under this operation regime. An example for a cell-producing bioreactor illustrates the analytical results. 相似文献
1000.
Heriberto Rodríguez‐Tobías Graciela Morales Oliverio Rodríguez‐Fernández Pablo Acuña 《应用聚合物科学杂志》2013,127(6):4708-4718
A series of poly(acrylonitrile‐butadiene‐styrene)/ZnO nanocomposites with different ZnO nanoparticles content were synthesized by a mass‐suspension polymerization process. Nanocomposites obtained through this technique presented high impact resistance despite the presence of agglomerates for high ZnO nanoparticles content so that, these samples were subjected to twin‐screw extrusion. The extrusion led to a dramatic morphological change and increased in impact resistance, higher than 100% in most of the cases. On the other hand, the higher the ZnO content, the higher the UV blocking (>95% for 1 and 3% of ZnO) for both materials, before and after extrusion. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献