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https://www.readbyqxmd.com/read/28441022/a-low-valent-lead-hydride-and-its-extreme-low-field-1h-nmr-chemical-shift
#1
Julia Schneider, Christian Patrick Sindlinger, Klaus Eichele, Hartmut Schubert, Lars Wesemann
Although hydrides of the group 14 elements are well known as versatile starting materials in many chemical transformations, a hydride of lead in oxidation state II is so far unknown. In this work we finally complete the jigsaw puzzle by reporting the isolation of the first low valent organolead hydride. The thermolabile dimeric organolead hydride was synthesized at low temperature and fea-tures a hydride 1H NMR signal (in solution 35.61 ppm; in the solid state 31.1 ppm) at the lowest field observed so far for a diamagnetic compound in agreement with quantum chemical predictions...
April 25, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28427837/in-vitro-fatigue-tests-and-in-silico-finite-element-analysis-of-dental-implants-with-different-fixture-abutment-joint-types-using-computer-aided-design-models
#2
Satoshi Yamaguchi, Yasufumi Yamanishi, Lucas S Machado, Shuji Matsumoto, Nick Tovar, Paulo G Coelho, Van P Thompson, Satoshi Imazato
PURPOSE: The aim of this study was to evaluate fatigue resistance of dental fixtures with two different fixture-abutment connections by in vitro fatigue testing and in silico three-dimensional finite element analysis (3D FEA) using original computer-aided design (CAD) models. METHODS: Dental implant fixtures with external connection (EX) or internal connection (IN) abutments were fabricated from original CAD models using grade IV titanium and step-stress accelerated life testing was performed...
April 17, 2017: Journal of Prosthodontic Research
https://www.readbyqxmd.com/read/28413061/mechanical-behavior-of-bulk-direct-composite-versus-block-composite-and-lithium-disilicate-indirect-class-ii-restorations-by-cad-fem-modeling
#3
Pietro Ausiello, Stefano Ciaramella, Andrea Fabianelli, Antonio Gloria, Massimo Martorelli, Antonio Lanzotti, David C Watts
OBJECTIVES: To study the influence of resin based and lithium disilicate materials on the stress and strain distributions in adhesive class II mesio-occlusal-distal (MOD) restorations using numerical finite element analysis (FEA). To investigate the materials combinations in the restored teeth during mastication and their ability to relieve stresses. METHODS: One 3D model of a sound lower molar and three 3D class II MOD cavity models with 95° cavity-margin-angle shapes were modelled...
April 13, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
https://www.readbyqxmd.com/read/28397164/comparison-of-effects-of-different-screw-materials-in-the-triangle-fixation-of-femoral-neck-fractures
#4
Kadir Gok, Sermet Inal, Arif Gok, Eyyup Gulbandilar
In this study, biomechanical behaviors of three different screw materials (stainless steel, titanium and cobalt-chromium) have analyzed to fix with triangle fixation under axial loading in femoral neck fracture and which material is best has been investigated. Point cloud obtained after scanning the human femoral model with the three dimensional (3D) scanner and this point cloud has been converted to 3D femoral model by Geomagic Studio software. Femoral neck fracture was modeled by SolidWorks software for only triangle configuration and computer-aided numerical analyses of three different materials have been carried out by AnsysWorkbench finite element analysis (FEA) software...
May 2017: Journal of Materials Science. Materials in Medicine
https://www.readbyqxmd.com/read/28386685/a-machine-learning-approach-to-investigate-the-relationship-between-shape-features-and-numerically-predicted-risk-of-ascending-aortic-aneurysm
#5
Liang Liang, Minliang Liu, Caitlin Martin, John A Elefteriades, Wei Sun
Geometric features of the aorta are linked to patient risk of rupture in the clinical decision to electively repair an ascending aortic aneurysm (AsAA). Previous approaches have focused on relationship between intuitive geometric features (e.g., diameter and curvature) and wall stress. This work investigates the feasibility of a machine learning approach to establish the linkages between shape features and FEA-predicted AsAA rupture risk, and it may serve as a faster surrogate for FEA associated with long simulation time and numerical convergence issues...
April 6, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28386547/biomechanical-evaluation-of-a-tooth-restored-with-high-performance-polymer-pekk-post-core-system-a-3d-finite-element-analysis
#6
Ki-Sun Lee, Joo-Hee Shin, Jong-Eun Kim, Jee-Hwan Kim, Won-Chang Lee, Sang-Wan Shin, Jeong-Yol Lee
The aim of this study was to evaluate the biomechanical behavior and long-term safety of high performance polymer PEKK as an intraradicular dental post-core material through comparative finite element analysis (FEA) with other conventional post-core materials. A 3D FEA model of a maxillary central incisor was constructed. A cyclic loading force of 50 N was applied at an angle of 45° to the longitudinal axis of the tooth at the palatal surface of the crown. For comparison with traditionally used post-core materials, three materials (gold, fiberglass, and PEKK) were simulated to determine their post-core properties...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28384464/biomechanical-evaluation-of-different-plating-methods-used-in-mandibular-angle-fractures-with-3-dimensional-finite-element-analysis-favorable-fractures
#7
Aysa Ayali, Erkan Erkmen
PURPOSE: The aim of the present study was to evaluate the performances of 5 different plating techniques for fixation of favorable mandibular angle fractures using the 3-dimensional finite element analysis (FEA) method. MATERIALS AND METHODS: Five different miniplate placement configurations were considered for the fixation of favorable mandibular angle fractures. The following models were created: a double parallel miniplate (M1) placed at the halfway point of the mandibular angle height; a one-third superior-positioned miniplate (M2); a single miniplate (M3) placed at the halfway point of the mandibular angle height (one-half middle-positioned); a one-third inferior-positioned miniplate (M4); and an X-shape miniplate (M5)...
March 14, 2017: Journal of Oral and Maxillofacial Surgery
https://www.readbyqxmd.com/read/28379839/a-density-functional-theory-study-of-the-influence-of-exchange-correlation-functionals-on-the-properties-of-feas
#8
Sinéad M Griffin, Nicola A Spaldin
We use density functional theory within the local density approximation (LDA), LDA  +  U, generalised gradient approximation (GGA), GGA  +  U, and hybrid-functional methods to calculate the properties of iron monoarsenide. FeAs, which forms in the MnP structure, is of current interest for potential spintronic applications as well as being the parent compound for the pnictide superconductors. We compare the calculated structural, magnetic and electronic properties obtained using the different functionals to each other and to experiment, and investigate the origin of a recently reported magnetic spiral...
April 5, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28377978/long-term-treatment-with-odanacatib-maintains-normal-trabecular-biomechanical-properties-in-ovariectomized-adult-monkeys-as-demonstrated-by-micro-ct-based-finite-element-analysis
#9
Antonio Cabal, Donald S Williams, Richa Y Jayakar, Jingru Zhang, Swanand Sardesai, Le T Duong
The cathepsin K inhibitor odanacatib (ODN) is a potent and reversible inhibitor of osteoclastic resorption activity. This drug is currently under development for the treatment of postmenopausal osteoporosis. Previously, we described data on the treatment efficacy of ODN in a preclinical estrogen-deficient model of an ovariectomized (OVX) rhesus monkey using HR-pQCT based finite element analysis (FEA) in vivo estimates of bone strength on the distal radius. To support the bone safety profile of ODN, we report ex vivo data on the apparent and hard tissue biomechanical properties of the trabecular bone of vertebrae of animals after 20 months of dosing in three treatment groups: Vehicle (VEH), ODN (2 mg/kg/day), and ALN (30 μg/kg/week)...
June 2017: Bone Reports
https://www.readbyqxmd.com/read/28376828/all-polyethylene-tibial-components-in-distal-femur-limb-salvage-surgery-a-finite-element-analysis-based-on-promising-clinical-outcomes
#10
Fan Tang, Yong Zhou, Wenli Zhang, Li Min, Rui Shi, Yi Luo, Hong Duan, Chongqi Tu
BACKGROUND: Whether all-polyethylene tibial (APT) components are beneficial to patients who received distal femur limb-salvage surgery lacks high-quality clinical follow-up and mechanical evidence. This study aimed to investigate the biomechanics of the distal femur reconstructed with APT tumor knee prostheses using finite element (FE) analysis based on our previous, promising clinical outcome. METHODS: Three-dimensional FE models that use APT and metal-backed tibial (MBT) prostheses to reconstruct distal femoral bone defects were developed and input into the Abaqus FEA software version 6...
April 4, 2017: Journal of Orthopaedic Surgery and Research
https://www.readbyqxmd.com/read/28372368/a-novel-diamond-anvil-cell-for-x-ray-diffraction-at-cryogenic-temperatures-manufactured-by-3d-printing
#11
H Jin, C H Woodall, X Wang, S Parsons, K V Kamenev
A new miniature high-pressure diamond anvil cell was designed and constructed using 3D micro laser sintering technology. This is the first application of the use of rapid prototyping technology to construct high-pressure apparatus. The cell is specifically designed for use as an X-ray diffraction cell that can be used with commercially available diffractometers and open-flow cryogenic equipment to collect data at low temperature and high pressure. The cell is constructed from stainless steel 316L and is about 9 mm in diameter and 7 mm in height, giving it both small dimensions and low thermal mass, and it will fit into the cooling envelope of a standard Cryostream(TM) cooling system...
March 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28369819/feeding-biomechanics-of-late-triassic-metoposaurids-amphibia-temnospondyli-a-3d-finite-element-analysis-approach
#12
Josep Fortuny, Jordi Marcé-Nogué, Dorota Konietzko-Meier
The Late Triassic freshwater ecosystems were occupied by different tetrapod groups including large-sized anamniotes, such as metoposaurids. Most members of this group of temnospondyls acquired gigantic sizes (up to 5 m long) with a nearly worldwide distribution. The paleoecology of metoposaurids is controversial; they have been historically considered passive, bottom-dwelling animals, waiting for prey on the bottom of rivers and lakes, or they have been suggested to be active mid-water feeders. The present study aims to expand upon the paleoecological interpretations of these animals using 3D finite element analyses (FEA)...
March 29, 2017: Journal of Anatomy
https://www.readbyqxmd.com/read/28367492/analgesic-anti-inflammatory-and-antioxidant-activities-of-byrsonima-duckeana-w-r-anderson-malpighiaceae
#13
Maria Christina Dos Santos Verdam, Fernanda Guilhon-Simplicio, Kleyton Cardoso de Andrade, Karina Lorena Meira Fernandes, Tallita Marques Machado, Felipe Moura Araújo da Silva, Mayane Pereira de Souza, Hector Henrique Ferreira Koolen, Cristiane da Silva Paula, Beatriz Cristina Konopatzki Hirota, Vinícius Bednarczuk de Oliveira, Cristina Mayumi Sasaki Miyazaki, Milena Kalegari, Marilis Dallarmi Miguel, Patricia Maria Stuelp-Campelo, Obdulio Gomes Miguel
Background. Byrsonima is a promising neotropical genus, rich in flavonoids and triterpenes, with several proven pharmacological properties. Nevertheless, Byrsonima duckeana W. R. Anderson is an Amazonian species almost not studied. Objective. To assess the antioxidant, anti-inflammatory, and analgesic activities of Byrsonima duckeana leaves. Materials and Methods. We analyzed an ethanol extract and its fractions for polyphenol content and UHPLC-MS/MS, phosphomolybdenum, DPPH, TBARS antioxidant tests, formalin-induced pain, carrageenan-induced peritonitis, acetic acid-induced abdominal writhings, and hot plate assays...
2017: TheScientificWorldJournal
https://www.readbyqxmd.com/read/28365982/hygroscopic-swelling-determination-of-cellulose-nanocrystal-cnc-films-by-polarized-light-microscopy-digital-image-correlation
#14
Shikha Shrestha, Jairo A Diaz, Siavash Ghanbari, Jeffrey Paul Youngblood
The coefficient of hygroscopic swelling (CHS) of self-organized and shear-oriented cellulose nanocrystal (CNC) films was determined by capturing hygroscopic strains produced as result of isothermal water vapor intake in equilibrium. Contrast enhanced microscopy digital image correlation enabled the characterization of dimensional changes induced by the hygroscopic swelling of the films. The distinct microstructure and birefringence of CNC films served in exploring the in-plane hygroscopic swelling at relative humidity values ranging from 0% to 97%...
April 3, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28365541/fracture-strength-and-probability-of-survival-of-narrow-and-extra-narrow-dental-implants-after-fatigue-testing-in-vitro-and-in-silico-analysis
#15
Dimorvan Bordin, Edmara T P Bergamo, Vinicius P Fardin, Paulo G Coelho, Estevam A Bonfante
PURPOSE: To assess the probability of survival (reliability) and failure modes of narrow implants with different diameters. MATERIALS AND METHODS: For fatigue testing, 42 implants with the same macrogeometry and internal conical connection were divided, according to diameter, as follows: narrow (Ø3.3×10mm) and extra-narrow (Ø2.9×10mm) (21 per group). Identical abutments were torqued to the implants and standardized maxillary incisor crowns were cemented and subjected to step-stress accelerated life testing (SSALT) in water...
March 27, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28362373/proximal-cadaveric-femur-preparation-for-fracture-strength-testing-and-quantitative-ct-based-finite-element-analysis
#16
Dan Dragomir-Daescu, Asghar Rezaei, Susheil Uthamaraj, Timothy Rossman, James T Bronk, Mark Bolander, Vincent Lambert, Sean McEligot, Rachel Entwistle, Hugo Giambini, Iwona Jasiuk, Michael J Yaszemski, Lichun Lu
Cadaveric fracture testing is routinely used to understand factors that affect proximal femur strength. Because ex vivo biological tissues are prone to lose their mechanical properties over time, specimen preparation for experimental testing must be performed carefully to obtain reliable results that represent in vivo conditions. For that reason, we designed a protocol and a set of fixtures to prepare the femoral specimens such that their mechanical properties experienced minimal changes. The femora were kept in a frozen state except during preparation steps and mechanical testing...
March 11, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28353052/the-effect-of-screw-tunnels-on-the-biomechanical-stability-of-vertebral-body-after-pedicle-screws-removal-a-finite-element-analysis
#17
Jia-Ming Liu, Yu Zhang, Yang Zhou, Xuan-Yin Chen, Shan-Hu Huang, Zi-Kai Hua, Zhi-Li Liu
PURPOSE: Posterior reduction and pedicle screw fixation is a widely used procedure for thoracic and lumbar vertebrae fractures. Usually, the pedicle screws would be removed after the fracture healing and screw tunnels would be left. The aim of this study is to evaluate the effect of screw tunnels on the biomechanical stability of the lumbar vertebral body after pedicle screws removal by finite element analysis (FEA). METHODS: First, the CT values of the screw tunnels wall in the fractured vertebral bodies were measured in patients whose pedicle screws were removed, and they were then compared with the values of vertebral cortical bone...
March 28, 2017: International Orthopaedics
https://www.readbyqxmd.com/read/28349900/structural-monitoring-and-modeling-of-the-mechanical-deformation-of-three-dimensional-printed-poly-%C3%AE%C2%B5-caprolactone-scaffolds
#18
João Ribeiro, Sara Oliveira, José Alves, Adriano Pedro, Rui Reis, Emanuel M Fernandes, Joao Mano
Three-dimensional (3D) printed poly(ε-caprolactone) (PCL) based scaffolds have being proposed for different tissue engineering applications. This study addresses the design and fabrication of 3D PCL constructs with different struts alignments at 90º, 45º and 90º with offset. The morphology and the mechanical behavior under uniaxial compressive load were assessed at different strain percentages. The combination of a new XtremeCT compression device and micro computed tomography (micro-CT) allowed understanding the influence of pore geometry under controlled compressive strain in the mechanical and structural behavior of PCL constructs...
March 28, 2017: Biofabrication
https://www.readbyqxmd.com/read/28347170/stress-distribution-in-cylindrical-and-conical-implants-under-rotational-micromovement-with-different-boundary-conditions-and-bone-properties-3-d-fea
#19
Mateus Bertolini Fernandes Dos Santos, Gabriel de Oliveira Meloto, Ataís Bacchi, Lourenço Correr-Sobrinho
Factors related to micromovements at bone-implant interface have been studied because they are considered adverse to osseointegration. Simplifications are commonly observed in these FEA evaluations. The aim of this study was to clarify the influence of FEA parameters (boundary conditions and bone properties) on the stress distribution in peri-implant bone tissue when micromovements are simulated in implants with different geometries. Three-dimensional models of an anterior section of the jaw with cylindrical or conical titanium implants (4...
March 28, 2017: Computer Methods in Biomechanics and Biomedical Engineering
https://www.readbyqxmd.com/read/28342508/gender-smoking-body-size-and-aneurysm-geometry-influence-the-biomechanical-rupture-risk-of-abdominal-aortic-aneurysms-as-estimated-by-finite-element-analysis
#20
Moritz Lindquist Liljeqvist, Rebecka Hultgren, Antti Siika, T Christian Gasser, Joy Roy
OBJECTIVE: Finite element analysis (FEA) has been suggested to be superior to maximal diameter measurements in predicting rupture of abdominal aortic aneurysms (AAAs). Our objective was to investigate to what extent previously described rupture risk factors were associated with FEA-estimated rupture risk. METHODS: One hundred forty-six patients with an asymptomatic AAA of a 40- to 60-mm diameter were retrospectively identified and consecutively included. The patients' computed tomography angiograms were analyzed by FEA without (neutral) and with (specific) input of patient-specific mean arterial pressure (MAP), gender, family history, and age...
April 2017: Journal of Vascular Surgery
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