152 research outputs found

    Sliding wear resistance of biomorphic SiC ceramics

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    Biomorphic SiC ceramics were fabricated from four different wood precursors and their Knoop hardness and sliding wear resistance when sliding against a Si3N4 ball in air were studied. Tribological experiments were performed using a pin on disk apparatus, under normal loads of 2 and 5 N, at a sliding speed of 100 mm/s. The effects of specimen porosity and microstructure on measured wear were evaluated. A commercial sintered silicon carbide ceramic was also tested for comparison. Small differences in friction coefficient comparable to monolithic SiC ceramics were obtained. Several concurrent wear mechanisms are taking place: microfracture, plastic deformation in the Si phase and oxidation of the Si and/or SiC phase. The presence of an oxide tribolayer was assessed using fluorescence microscopy. Wear rates were found to scale with SiC content and depend on residual porosity in the composite.Peer reviewe

    Manganese Dioxide Supported on Porous Biomorphic Carbons as Hybrid Materials for Energy Storage Devices

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    A facile and low-cost method has been employed to fabricate MnO2/C hybrid materials for use as binder-free electrodes for supercapacitor applications. Biocarbon monoliths were obtained through pyrolysis of beech wood, replicating the microstructure of the cellulosic precursor, and serve as 3D porous and conductive scaffolds for the direct growth of MnO2 nanosheets by a solution method. Evaluation of the experimental results indicates that a homogeneous and uniform composite material made of a carbon matrix exhibiting ordered hierarchical porosity and MnO2 nanosheets with a layered nanocrystalline structure is obtained. The tuning of the MnO2 content and crystallite size via the concentration of KMnO4 used as impregnation solution allows to obtain composites that exhibit enhanced electrochemical behavior, achieving a capacitance of 592 F g−1 in electrodes containing 3 wt % MnO2 with an excellent cyclic stability. The electrode materials were characterized before and after electrochemical testing.Peer reviewe

    Modeling Macro-Sized, High Aspect Ratio Through-Hole Filling by Multi-Component Additive-Assisted Copper Electrodeposition

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    A multi-element, time-dependent model is used to examine additive-assisted copper electroplating in macro-channels. This model is an adaptation of the work of Akolkar and Landau [J. Electrochem. Soc., 156, D351 (2009)], used to describe plating in micro-vias for integrated circuits. Using their method for describing species movement in the channel, the model has been expanded to include transport and adsorption limitations of the inhibitor and accelerator, as well as the copper ions in solution. The model is used to investigate copper plating as an infiltration method across many size scales and aspect ratios. Biomorphic graphite scaffolds produced from wood are used as a representative system and the results of a two-additive bath are used to characterize the behavior of the additives and determine the effectiveness of the plating. The results indicate that at macro-scales, channel dimensions play an increasingly important role in dictating the behavior of additive-assisted plating. Because additive systems are designed to establish differential surface coverage within the channel, the success of which is determined by the additive's rates of diffusion and adsorption, certain size scale/aspect ratio combinations preclude such coverage. A guide for sample geometries that may be successfully infiltrated with a two-additive bath is provided

    Low-Voltage 0.81mW, 1-32 CMOS VGA with 5% Bandwidth variations and 38dB DC rejection

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    A CMOS low-voltage amplifier with approximately constant bandwidth and DC rejection is introduced. The design is based on the cascade of a wide linear input range OTA, an op-amp and a servo-loop with extremely large time constants. It operates with ±0.45V supplies and a power consumption of 0.81mW in 180nm technology. The bandwidth changes only from 9.08MHz to 9.54MHz over a gain range from 1 to 32, it has a 9.8Hz low cutoff frequency and a DC attenuation of 38dBs. DC floating voltage sources are used to keep the gates of all differential pairs at a constant value close to a supply rail in order to operate the amplifier circuit with minimum supply voltage. The proposed circuit has small and large signal figures of merit FOM SS = 5380 (MHz*pF/mW) and FOM LS = 0.0085((V/ns)*pF/mA) for a nominal gain A = 32

    Genotype-environment interaction in the production of dry matter of edgeless fodder barley (Hordeum vulgare L.)

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    Objective: To analyze the genotype environment interaction (GEI) in the dry forage production of 24 lines of awnless barley and commercial checks of the same and other species, through five environments.  Design/methodology/approach: A randomly complete block design with three replications was used in the five environments evaluated, forage harvest was done at 105 days after sowing. The data were analyzed as combined randomly blocks over environmentss and the (GEI) was analyzed using the AMMI model. Results: Significative differences (p? 0.01) were detected in the main effects and the GEI. According to AMMI analysis, genotypes G26 (Cerro prieto), G27 (Gabyan95), G10, G3, G19 and even genotype G24, showed near-zero interactions, so they were considered stable, while awnless barley lines: G6, G1 and G2 were rated as desirable for dry forage production base don their superiority over the overall mean and its low IGA. Limitations on study/implications: Results may to vary if different environments and genotypes are considered. Findings/conclusions: Threre are stable and desirable awnless barley genotypes that represents an excellent option for forage production in the studied región. The oat check was considered the least productive and Zaragoza, Coahuila, location is considered a potential environment for the production of dry forage using awnless forage barley as those evaluated in this study, in addition this environment exhibited adequate discriminatory power. Key words: Awnless barley, dry forage, genotype environment interaction, AMMI model.Objective: To analyze the genotype-environment interaction (GEI) within the dry fodder production of 24 edgeless barley fodder lines (Hordeum vulgare L.) or commercial controls of the same and other species across five environments. Design/Methodology/Approach: A randomized complete block design with three repetitions was used in the five trial environments, with fodder harvested at 105 d after sowing. Data were analyzed as combined random blocks over environments and the GEI was analyzed using the AMMI model. Results: Significance (p≤ 0.01) was detected in the main effects and the GEI. Genotypes G26 (Cerro Prieto), G27 (Gabyan95), G10, G3, G19 and even genotype G24, showed interactions close to zero, so they were considered stable, while the edgeless barley lines: G6, G1 and G2 were qualified as desirable for dry fodder production, according to their superiority over the general mean and their low GEI. Study Limitations/Implications: Results may vary when evaluating other environments and genotypes. Findings/Conclusions: There are stable and desirable edgeless fodder barley genotypes that represent an option for fodder production in the study region. The oat control was considered the least productive and the locality of Zaragoza, Coahuila, is considered a potential environment for dry fodder production using edgeless fodder barleys such as those evaluated in this study, in addition to showing adequate discriminatory power

    Hongos liquenizados y liquenícolas de la Sierra de Albarracín (Teruel, España)

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    Se presenta un catálogo de 462 hongos liquenizados y liquenícolas de la Sierra de Albarracín (Teruel, Aragón, España), como resultado de la IV Campaña de Recolección organizada por la Sociedad Española de Liquenología (SEL). Diplotomma hedinii es novedad para la Península Ibé- rica y Lepraria leuckertiana constituye una segunda cita peninsular, 69 taxones son novedad para Aragón y 86 lo son para la provincia de Teruel

    “Tourism, water, and gender”—An international review of an unexplored nexus

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    This international literature review of the tourism–water nexus identifies a gender gap. Tourism development can affect water supply both quantitatively and qualitatively. Many regions will face considerable problems of water availability and quality, affecting their tourism sector and increasing competition with local residents, and other industries especially agriculture. This international review of literature explores the tourism–water nexus, comparing and contrasting literature published in English, Chinese, and Spanish. Securing access to safe water for continued tourism development is a common theme and the vast majority of work has focused on hotels including water pricing, water-saving practices and innovative management methods. In all continents, struggles are apparent, and the unsustainability of tourism is having impacts on water quantity and quality. This article identifies significant gaps in the literature including climate change, the energy-water nexus, and the links with the Sustainable Development Goals. Furthermore, studies from a gendered perspective are minimal and the potential for areas of further gendered studies within the tourism–water nexus are highlighted including intersectionality, water insecurity and sanitation, tourism and gender based violence, and additional unpaid care work

    Liver injury in non-alcoholic fatty liver disease is associated with urea cycle enzyme dysregulation

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    The main aim was to evaluate changes in urea cycle enzymes in NAFLD patients and in two preclinical animal models mimicking this entity. Seventeen liver specimens from NAFLD patients were included for immunohistochemistry and gene expression analyses. Three-hundred-and-eighty-two biopsy-proven NAFLD patients were genotyped for rs1047891, a functional variant located in carbamoyl phosphate synthetase-1 (CPS1) gene. Two preclinical models were employed to analyse CPS1 by immunohistochemistry, a choline deficient high-fat diet model (CDA-HFD) and a high fat diet LDLr knockout model (LDLr −/−). A significant downregulation in mRNA was observed in CPS1 and ornithine transcarbamylase (OTC1) in simple steatosis and NASH-fibrosis patients versus controls. Further, age, obesity (BMI > 30 kg/m), diabetes mellitus and ALT werefound to be risk factors whereas A-allele from CPS1 was a protective factor from liver fibrosis. CPS1 hepatic expression was diminished in parallel with the increase of fibrosis, and its levels reverted up to normality after changing diet in CDA-HFD mice. In conclusion, liver fibrosis and steatosis were associated with a reduction in both gene and protein expression patterns of mitochondrial urea cycle enzymes. A-allele from a variant on CPS1 may protect from fibrosis development. CPS1 expression is restored in a preclinical model when the main trigger of the liver damage disappears.The research leading to these results has received funding from the Consejería de Salud de la Junta de Andalucía under grant agreement PC-0148-2016-0148 and PE-0451-2018 and Instituto de Salud Carlos III under grant agreements CD21/00095, PI16/01842, PI19/01404, PI19/00589, IFI18/00041, FI20/00201, CD18/00126 and EHD18PI04/2021. Rocío Gallego-Durán has received the Andrew K Burroughs Fellowship from European Association for the Study of the Liver (EASL), Aprendizaje de Nuevas Tecnologías fellowship from Asociación Española para el Estudio del Hígado (AEEH) and CIBERehd Grant to support researcher’s mobility

    Liver injury in non-alcoholic fatty liver disease is associated with urea cycle enzyme dysregulation

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    The main aim was to evaluate changes in urea cycle enzymes in NAFLD patients and in two preclinical animal models mimicking this entity. Seventeen liver specimens from NAFLD patients were included for immunohistochemistry and gene expression analyses. Three-hundred-and-eighty-two biopsy-proven NAFLD patients were genotyped for rs1047891, a functional variant located in carbamoyl phosphate synthetase-1 (CPS1) gene. Two preclinical models were employed to analyse CPS1 by immunohistochemistry, a choline deficient high-fat diet model (CDA-HFD) and a high fat diet LDLr knockout model (LDLr −/−). A significant downregulation in mRNA was observed in CPS1 and ornithine transcarbamylase (OTC1) in simple steatosis and NASH-fibrosis patients versus controls. Further, age, obesity (BMI > 30 kg/m2), diabetes mellitus and ALT werefound to be risk factors whereas A-allele from CPS1 was a protective factor from liver fibrosis. CPS1 hepatic expression was diminished in parallel with the increase of fibrosis, and its levels reverted up to normality after changing diet in CDA-HFD mice. In conclusion, liver fibrosis and steatosis were associated with a reduction in both gene and protein expression patterns of mitochondrial urea cycle enzymes. A-allele from a variant on CPS1 may protect from fibrosis development. CPS1 expression is restored in a preclinical model when the main trigger of the liver damage disappears

    Thin film nanostructuring at oblique angles by substrate patterning

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    It is demonstrated that, besides classical nanocolumnar arrays, the oblique angle geometry induces the growth of singular structures in the nanoscale when using wisely designed patterned substrates. Well-ordered array of crosses, cylindrical nanorods or hole structures arranged in square or hexagonal regular geometries are reported as examples, among others. The fundamental framework connecting substrate topography and film growth at oblique angles is presented, allowing the use of substrate patterning as a feasible thin film nanostructuring technique. A systematic analysis of the growth of TiO2 thin films on 4 different lithographic patterned substrates in 4 different scale lengths is also presented. A first conclusion is the existence of a height-based selective growth in the initial stages of the deposition, by which the film preferentially develops on top of the tallest substrate features. This behavior is maintained until the film reaches a critical thickness, the so-called Oblivion Thickness, above which the film topography becomes gradually independent of the substrate features. A general formula relating the spatial features of the pattern, the coarsening exponent and the Oblivion Thickness has been deduced.The authors thank the financial support from MCIN/AEI/10.13039/ 501100011033 projects PID2019-110430GB-C21, PID2020-112620GBI00, PID2020-114270RA-I00 and RTI2018-098117-B-C21 (also financed by FEDER Una manera de hacer europa), the Junta de Andalucía (PAIDI- 2020 through projects P18-RT-3480 and P18-RT-6079, and through its 2019 PhD Researcher Hiring Program), the CSIC (2019AEP161 and 201860E050), the Regional Government of Madrid (project IND2017/ IND-7668 and YEI contract PEJ-2019-AI/IND-14451 with support from FSE), the H2020-EU.1.2.1-FET OPEN program (grant 899352, project SOUNDofICE, and the EFRE Infra-Pro project ChAMP), and the University of Seville (VI PPIT-US). The work is supported by the Deutsche Forschungsgemeinschaft (DFG, grant Scha 632/24, “Tailored Disorder” and Scha 632/27, “DFGGer ¨atezentrum”). This work is also supported by the free state of Thuringia under grants 2015 FGI 0025 305 (FastμXRD) and B715-10009 (BioMacroNano2020), all co-financed by the European Union within the framework of the European Regional Development Fund (ERDF). The service from the MiNa Laboratory at IMN-CNM (CSIC), funded from CM (project S2018/NMT-4291 TEC2SPACE), MINECO (project CSIC13-4E- 1794) and EU (FEDER, FSE), is also acknowledged.Peer reviewe
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