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Analysis of the Influence of Parafunctional Loads on the Bone-Prosthesis System: A Non-Linear Finite Element Analysis

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Journal of Biomedical Science and Engineering 2021年第6期14卷 223-232页

作者： Henry Figueredo Losada Edison Gonçalves jose luis Valin luis Ide Faculty of Engineering University of the Republic Montevideo Uruguay Polytechnic School University of Sao Paulo Sao Paulo Brazil School of Mechanical Engineering Pontifical Catholic University of Valparaíso Valparaíso Chile Faculty of Dentistry University of Sao Paulo Sao Paulo Brazil

The present study evaluates the effects of occlusal loading on an implant-supported dental implant with external hexagon dental implant-abutment systems, using the finite element method analysis. Tensile analyses were performed to simulate different axial and obliquous masticatory loads. The influence of the variations in the contouring conditions of the interfaces was analyzed to weigh the osseointegration with linear and non-linear cases, by means of a parametric design. The geometry selected to place the prostheses was a jaw section, considering the properties of the set of cortical and trabecular bones. The results show that for non-linear contour conditions, the stress presents smaller value distributions and signals a different place in the screw-implant interface as the factor of the greater weight in this study. The location indicated that von Mises stress concentrations are not exclusive to the contact regions studied, moving to an area that is not in direct contact with the non-linear contact interfaces. In addition, the direction of load with an angle of 15 degrees presented the highest values of von Mises stress.

关键词： Biomechanics Analysis Non-Linear Dental Implant Finite Element Method

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Duodenal biopsy may be avoided when high transglutaminase antibody titers are present

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World Journal of Gastroenterology 2009年第38期15卷 4775-4780页

作者： Santiago Vivas jose G Ruiz de Morales Sabino Riestra Laura Arias Dolores Fuentes Noemi Alvarez Sara Calleja Mercedes Hernando Blanca Herrero Javier Casqueiro luis Rodrigo Department of Gastroenterology Hospital de León Institute of Biomedicine University of León Immunology Section Hospital de León Department of Gastroenterology Hospital Universitario Central de Asturias Department of Pathology Hospital de León Department of Pediatrics Hospital de León Faculty of Biology and Environmental Sciences University of León

AIM:To evaluate the predictive value of tissue transglutaminase (tTG) antibodies for villous atrophy in adult and pediatric populations to determine if duodenal biopsy can be ***: A total of 324 patients with celiac disease (CD; 97 children and 227 adults) were recruited prospectively at two tertiary centers. Human IgA class anti-tTG antibody measurement and upper gastrointestinal endoscopy were performed at diagnosis. A second biopsy was performed in 40 asymptomatic adults on a gluten-free diet (GFD) and with normal tTG ***: Adults showed less severe histopathology (26% vs 63%, P<0.0001) and lower tTG antibody titers than children. Levels of tTG antibody correlated with Marsh type in both populations (r=0.661, P<0.0001). Multiple logistic regression revealed that only tTG antibody was an independent predictor for Marsh type 3 lesions, but clinical presentation type and age were not. A cut-off point of 30 U tTG antibody yielded the highest area under the receiver operating characteristic curve (0.854). Based on the predictive value of this cut-off point, up to 95% of children and 53% of adults would be correctly diagnosed without biopsy. Despite GFDs and decreased tTG antibody levels, 25% of the adults did not recover from villous atrophy during the second year after ***: Strongly positive tTG antibody titers might be sufficient for CD diagnosis in children. However, duodenal biopsy cannot be avoided in adults because disease presentation and monitoring are different.

关键词： Biopsy Celiac disease Diagnosis Duodenum Transglutaminases

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Heterogeneous catalysts with programmable topologies generated by reticulation of organocatalysts into metal-organic frameworks:The case of squaramide

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Nano Research 2021年第2期14卷 458-465页

作者： Anna Broto-Ribas Claudia Vignatti Alicia Jimenez-Almarza Javier luis-Barrera Zahra Dolatkhah Felipe Gandara Inhar Imaz Ruben Mas-Balleste jose Aleman Daniel Maspoch Catalan Institute of Nanoscience and Nanotechnology(ICN2) CSIC and The Barcelona Institute of Science and Technology08193 BarcelonaSpain Inorganic Chemistry Department Modulo 7Universidad Autonoma de Madrid28049 MadridSpain Organic Chemistry Department Modulo 1Universidad Autonoma de Madrid28049 MadridSpain Materials Science Factory Instituto de Ciencia de Materiales de Madrid(ICMM)Consejo Superior de Investigaciones Cientificas(CSIC)Calle Sor Juana Ines de la Cruz328049 MadridSpain Institute for Advanced Research in Chemical Sciences(IAdChem) Campus Universidad Autonoma de Madrid28049 MadridSpain Institucio Catalana de Recerca i Estudis Avangats(ICREA) 08100 BarcelonaSpain

A well-established strategy to synthesize heterogeneous,metal-organic framework(MOF)catalysts that exhibit nanoconfinement effects,and specific pores with highly-localized catalytic sites,is to use organic linkers containing organocatalytic ***,we report that by combining this linker approach with reticular chemistry,and exploiting three-dimensioanl(3D)MOF-structural data from the Cambridge Structural Database,we have designed four heterogeneous MOF-based catalysts for standard organic *** programmable MOFs are isoreticular versions of pcu IRMOF-16,feu UiO-68 and pillared-pcu SNU-8X,the three most common topologies of MOFs built from the organic linker p.p'-terphenyldicarboxylic acid(tpdc).To synthesize the four squaramide-based MOFs,we designed and synthesized a linker,4,4’-((3,4-dioxocyclobut-1-ene-1,2-diyl)bis(azanedyil))dibenzoic acid(Sq_tpdc),which is identical in directionality and length to tpdc but which contains organocatalytic squaramide *** were chosen because their immobilization into a framework enhances its reactivity and stability while avoiding any self-quenching ***,the four MOFs share the same organocatalytic squaramide moiety,but confine it within distinct pore *** then evaluated these MOFs as heterogeneous H-bonding catalysts in organic transformations:a Friedel-Crafts alkylation and an epoxide *** of them exhibited good performance in both reactions but all showed distinct catalytic profiles that reflect their structural differences.

关键词： reticular chemistry metal-organic frameworks H-bond catalysis squaramide Friedel-Cratts epoxide ring-opening

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Direct-fed microbes: A tool for improving the utilization of low quality roughages in ruminants

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Journal of Integrative Agriculture 2015年第3期14卷 526-533页

作者： Mona M Y Elghandour Abdelfattah Z M Salem jose S Martínez Castaeda luis M Camacho Ahmed E Kholif Juan C Vázquez Chagoyán Faculty of Veterinary Medicine and Animal Science Autonomous University of the State of Mexico Faculty of Veterinary Medicine and Animal Science Autonomous University of Guerrero Dairy Science Department National Research Centre

For many years, ruminant nutritionists and microbiologists have been interested in manipulating the microbial ecosystem of the rumen to improve production efficiency of different ruminant species. Removal and restriction of antibiotics subtherapeutic uses from ruminant diets has amplified interest in improving nutrient utilization and animal performance and search for more safe alternatives. Some bacterial and fungal microorganisms as a direct-fed microbial（DFM） can be the most suitable solutions. Microorganisms that are commonly used in DFM for ruminants may be classified mainly as lactic acid producing bacteria（LAB）, lactic acid utilizing bacteria（LUB）, or other microorganism＇s species like Lactobacillus, Bifidobacterium, Enterococcus, Streptococcus, Bacillus, Propionibacterium, Megasphaera elsdenii and Prevotellabryantii, in addition to some fungal species of yeast such as Saccharomyces and Aspergillus. A definitive mode of action for bacterial or fungal DFM has not been established; although a variety of mechanisms have been suggested. Bacterial DFM potentially moderate rumen conditions, and improve weight gain and feed efficiency. Fungal DFM may reduce harmful oxygen from the rumen, prevent excess lactate production, increase feed digestibility, and alter rumen fermentation patterns. DFM may also compete with and inhibit the growth of pathogens, immune system modulation, and modulate microbial balance in the gastrointestinal tract. Improved dry matter intake, milk yield, fat corrected milk yield and milk fat content were obtained with DFM administration. However, the response to DFM is not constant; depending on dosages, feeding times and frequencies, and strains of DFM. Nonetheless, recent studies have supported the positive effects of DFM on ruminant performance.

关键词： direct-fed microbial(DFM) mode of action ruminants

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Effect of homogenization process on the hardness of Zn-Al-Cu alloys

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International Journal of Minerals,Metallurgy and Materials 2015年第10期22卷 1076-1081页

作者： jose D.Villegas-Cardenas Maribel L.Saucedo-Munoz Victor M.Lopez-Hirata Antonio De Ita-De la Torre Erika O.Avila-Davila Jorge luis Gonzalez-Velazquez Department of Metallurgy and Materials Instituto Politecnico Nacional(IPN-ESIQIE)Mexico City 07300Mexico Department of Industrial Engineering Universidad Politecnica del Valle de MexicoMexico CityMexico Department of Materials Universidad Autonoma Metropolitana(UAM)Unidad AzcapotzalcoMexico

The effect of a homogenizing treatment on the hardness of as-cast Zn–Al–Cu alloys was investigated. Eight alloy compositions were prepared and homogenized at 350 °C for 180 h, and their Rockwell 'B' hardness was subsequently measured. All the specimens were analyzed by X-ray diffraction and metallographically prepared for observation by optical microscopy and scanning electron microscopy. The results of the present work indicated that the hardness of both alloys(as-cast and homogenized) increased with increasing Al and Cu contents; this increased hardness is likely related to the presence of the θ and τ′ phases. A regression equation was obtained to determine the hardness of the homogenized alloys as a function of their chemical composition and processing parameters, such as homogenization time and temperature, used in their preparation.

关键词： zinc–aluminum–copper alloys casting hardness homogenization phases microstructure

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