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Mechanical compression

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https://www.readbyqxmd.com/read/28110324/setting-kinetics-and-mechanical-properties-of-flax-fibre-reinforced-glass-ionomer-restorative-materials
#1
Abou Neel Ensanya Ali, Young Anne M
Regardless of the excellent properties of glass ionomer cements, their poor mechanical properties limit their applications to non-load bearing areas. This study aimed to investigate the effect of incorporated short, chopped and randomly distributed flax fibers (0, 0.5, 1, 2.5, 5 and 25 wt%) on setting reaction kinetics, and mechanical and morphological properties of glass ionomer cements. Addition of flax fibers did not significantly affect the setting reaction extent. According to their content, flax fibers increased the compressive (from 148 to 250 MPa) and flexure strength (from 20 to 42 MPa)...
October 17, 2016: Journal of Biomedical Research
https://www.readbyqxmd.com/read/28110072/structuring-of-composite-hydrogel-bioadhesives-and-its-effect-on-properties-and-bonding-mechanism
#2
Oded Pinkas, Daniella Goder, Roni Noyvirt, Sivan Peleg, Maayan Kahlon, Meital Zilberman
: Bioadhesives are polymeric hydrogels that can adhere to a tissue after crosslinking and are an essential element in nearly all surgeries worldwide. Several bioadhesives are commercially available. However, none of them are ideal. The main limitation of current tissue adhesives is the tradeoff between biocompatibility and mechanical strength, especially in wet hemorrhagic environments. Our novel bioadhesives are based on the natural polymers gelatin (coldwater fish) and alginate, crosslinked by carbodiimide (EDC)...
January 18, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28110067/poly-glycerol-sebacate-elastomer-supports-bone-regeneration-by-its-mechanical-properties-being-closer-to-osteoid-tissue-rather-than-to-mature-bone
#3
S H Zaky, K W Lee, J Gao, A Jensen, K Verdelis, Y Wang, A J Almarza, C Sfeir
: Mechanical load influences bone structure and mass. Arguing the importance of load-transduction, we investigated the mechanisms inducing bone formation using an elastomeric substrate. We characterized Poly (glycerol sebacate) (PGS) in-vitro for its mechanical properties, compatibility with osteoprogenitor cells regarding adhesion, proliferation, differentiation under compression versus static cultures and in-vivo for the regeneration of a rabbit ulna critical size defect. The load-transducing properties of PGS were compared in-vitro to a stiffer poly lactic-co- glycolic-acid (PLA/PGA) scaffold of similar porosity and interconnectivity...
January 18, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28109814/carboxymethyl-sesbania-gum-synthesis-characterization-and-evaluation-for-drug-delivery
#4
Shakuntla Verma, Munish Ahuja
In the present study, carboxymethyl Sesbania gum was synthesized and evaluated for drug delivery. Carboxymethylation was carried out by reacting with monochloroacetic acid under alkaline conditions. Modification of the gum was confirmed by Fourier-transform infrared spectroscopy. The degree of carboxymethyl substitution was determined to be 1.3. Carboxymethylation improved the flow properties, increased the degree of crystallinity and changed the compression behaviour from elastic to plastic. Further, the interaction between the modified gum and Ca(2+)-ions was optimized employing a 3-factor, 3-level central composite experimental design to prepare mucoadhesive sustained release beads using metformin hydrochloride as the model drug...
January 18, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28108405/defects-of-the-vertebral-endplate-implications-for-disc-degeneration-depend-on-size
#5
Uruj Zehra, Luke Flower, Katharine Robson-Brown, Michael A Adams, Patricia Dolan
BACKGROUND CONTEXT: Bony vertebral endplates must be porous to allow metabolite transport into the disc, and yet strong to resist high intradiscal pressure. Endplate defects may therefore have nutritional and mechanical consequences for the disc, depending on their size and type. We hypothesise that broad, diffuse defects are more closely associated with disc decompression and degeneration than are focal Schmorl's node-type defects. PURPOSE: To determine how the size and type of endplate defects are related to decompression and degeneration in the adjacent intervertebral disc...
January 17, 2017: Spine Journal: Official Journal of the North American Spine Society
https://www.readbyqxmd.com/read/28107739/on-the-synthesis-of-nanostructured-akermanite-scaffolds-via-space-holder-method-the-effect-of-the-spacer-size-on-the-porosity-and-mechanical-properties
#6
Aliakbar Najafinezhad, Majid Abdellahi, Sepideh Nasiri-Harchegani, Ali Soheily, Mohammadsaleh Khezri, Hamid Ghayour
In the present study, for the first time, the space holder method was used to prepare akermanite scaffolds with high porous structures, high interconnectivity, and high compressive strength, while the role of different spacer sizes on the akermanite scaffold properties was also evaluated. The results showed that the increase in the NaCl particle size which was used as spacer leads to an increase of the pore size and interconnectivity and a decrease of compressive strength. When the size of the spacer was 420-600µm and more than 600µm, a total porosity of 82 and 83% and a compressive strength of 0...
January 3, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28107240/an-in-vitro-evaluation-of-fracture-reduction-achieved-by-inflatable-bone-tamps-under-simulated-physiological-load
#7
Michael Gordon, Walter C Peppelman, William Beutler, Damien OʼHalloran, Suresh R Chinthakunta, Brandon Bucklen
STUDY DESIGN: An in vitro biomechanical study. OBJECTIVE: To determine the fracture reduction achieved by a novel inflatable bone tamp under simulated physiological load. SUMMARY OF BACKGROUND DATA: Previous biomechanical studies have showed that kyphoplasty allows near-total restoration of lost vertebral height in unloaded conditions and partial height restoration under simulated physiological loads. Clinically, loss of reduction has been observed after bone tamp deflation, before cement injection...
February 2017: Clinical Spine Surgery
https://www.readbyqxmd.com/read/28106535/viscoelastic-behaviour-of-hydrogel-based-composites-for-tissue-engineering-under-mechanical-load
#8
Rok Kocen, M Gasik, Ana Gantar, Sasa Novak
Along with biocompatibility, bioinductivity and appropriate biodegradation, mechanical properties are also of crucial importance for tissue engineering scaffolds. Hydrogels, such as gellan gum, are usually soft materials, which may benefit from the incorporation of inorganic particles, e.g. bioactive glass, not only due to the acquired bioactivity, but also due to improved mechanical properties. They exhibit complex viscoelastic properties, which can be evaluated in various ways. In this work, to reliably evaluate the effect of the bioactive glass addition on viscoelastic properties of the composite hydrogel, we employed and compared three most commonly used techniques, analyzing their advantages and limitations: monotonic uniaxial unconfined compression, small amplitude oscillatory shear (SAOS) rheology and dynamic mechanical analysis (DMA)...
January 20, 2017: Biomedical Materials
https://www.readbyqxmd.com/read/28106318/reduced-laser-evoked-potential-habituation-detects-abnormal-central-pain-processing-in-painful-radiculopathy-patients
#9
P Hüllemann, C von der Brelie, G Manthey, J Düsterhöft, A K Helmers, M Synowitz, R Baron
BACKGROUND: Repetitive painful laser stimuli lead to physiological laser-evoked potential (LEP) habituation, measurable by a decrement of the N2/P2 amplitude. The time course of LEP-habituation is reduced in the capsaicin model for peripheral and central sensitization and in patients with migraine and fibromyalgia. In the present investigation, we aimed to assess the time course of LEP-habituation in a neuropathic pain syndrome, i.e. painful radiculopathy. METHODS: At the side of radiating pain, four blocks of 25 painful laser stimuli each were applied to the ventral thigh at the L3 dermatome in 27 patients with painful radiculopathy...
January 20, 2017: European Journal of Pain: EJP
https://www.readbyqxmd.com/read/28106209/sub-100-nm-wrinkling-of-polydimethylsiloxane-by-double-frontal-oxidation
#10
Manuela Nania, Fabrizia Foglia, Omar K Matar, João T Cabral
We demonstrate nanoscale wrinkling on polydimethylsiloxane (PDMS) at sub-100 nm length scales via a (double) frontal surface oxidation coupled with a mechanical compression. The kinetics of the glassy skin propagation is resolved by neutron and X-ray reflectivity, and atomic force microscopy, combined with mechanical wrinkling experiments to evaluate the resulting pattern formation. In conventional PDMS surface oxidation, the smallest wrinkling patterns attainable have an intrinsic lower wavelength limit due to the coupling of skin formation and front propagation at fixed strain εprestrain, whose maximum is, in turn, set by material failure...
January 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28106012/high-pressure-structural-elastic-and-thermodynamic-properties-of-zircon-type-hopo4-and-tmpo4
#11
O Gomis, B Lavina, P Rodríguez-Hernández, A Muñoz, R Errandonea, D Errandonea, M Bettinelli
Zircon-type holmium phosphate (HoPO4) and thulium phosphate (TmPO4) have been studied by single-crystal x-ray diffraction and ab initio calculations. We report on the influence of pressure on the crystal structure, and on the elastic and thermodynamic properties. The equation of state for both compounds is accurately determined. We have also obtained information on the polyhedral compressibility which is used to explain the anisotropic axial compressibility and the bulk compressibility. Both compounds are ductile and more resistive to volume compression than to shear deformation at all pressures...
January 20, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28105891/friction-of-sodium-alginate-hydrogel-scaffold-fabricated-by-3-d-printing
#12
Qian Yang, Jian Li, Heng Xu, Shijun Long, Xuefeng Li
A rapid prototyping technology, formed by three-dimensional (3-D) printing and then crosslinked by spraying Ca(2+) solution, is developed to fabricate a sodium alginate (SA) hydrogel scaffold. The porosity, swelling ratio, and compression modulus of the scaffold are investigated. A friction mechanism is developed by studying the reproducible friction behavior. Our results show that the scaffold can have 3-D structure with a porosity of 52%. The degree of swelling of the SA hydrogel scaffold is 8.5, which is nearly the same as bulk SA hydrogel...
January 20, 2017: Journal of Biomaterials Science. Polymer Edition
https://www.readbyqxmd.com/read/28105748/silicone-based-organic-inorganic-hybrid-aerogels-and-xerogels
#13
REVIEW
Taiyo Shimizu, Kazuyoshi Kanamori, Kazuki Nakanishi
Aerogels are attracting increasing attention due to their high thermal insulation ability as well as unique properties such as high porosity, surface area, and transparency. However, low mechanical strengths, originating from their unique porous structure, impede handling, formability, mass production, and extended applications. This minireview focuses on the strengthening of aerogels by several organic-inorganic hybridization strategies. In particular, successful strengthening methodologies, which employ organo-substituted alkoxysilanes as the single precursor for the sol-gel preparations, developed by the authors are highlighted...
January 20, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28104573/anomalous-subcortical-morphology-in-boys-but-not-girls-with-adhd-compared-to-typically-developing-controls-and-correlates-with-emotion-dysregulation
#14
Karen E Seymour, Xiaoying Tang, Deana Crocetti, Stewart H Mostofsky, Michael I Miller, Keri S Rosch
There has been limited investigation of volume and shape difference in subcortical structures in children with ADHD and a paucity of examination of the influence of sex on these findings. The objective of this study was to examine morphology (volume and shape) of subcortical structures and their association with emotion dysregulation (ED) in girls and boys with ADHD as compared to their typically-developing (TD) counterparts. Participants included 218 children ages 8-12 years old with and without DSM-IV ADHD...
January 6, 2017: Psychiatry Research
https://www.readbyqxmd.com/read/28103756/compression-induced-chondrogenic-differentiation-of-embryonic-stem-cells-in-3-d-pdms-scaffolds
#15
Christina McKee, Yifeng Hong, Donggang Yao, G Rasul Chaudhry
Embryonic stem cells (ESCs) are an ideal source for chondrogenic progenitors for the repair of damaged cartilage tissue. It is currently difficult to induce uniform and scalable ESC differentiation in vitro, a process required for stem cell therapy. This is partly because stem cell fate is determined by complex interactions with the native microenvironment and mechanical properties of the extracellular matrix. Mechanical signaling is considered to be one of the major factors regulating the proliferation and differentiation of chondrogenic cells both in vitro and in vivo...
January 19, 2017: Tissue Engineering. Part A
https://www.readbyqxmd.com/read/28103752/mynxgrip-for-closure-of-antegrade-puncture-after-peripheral-interventions-with-same-day-discharge
#16
Maciej J Pruski, Aleksandra M Blachut, Magda Konkolewska, Adam Janas, Eugeniusz Hrycek, Piotr P Buszman, Radoslaw S Kiesz
BACKGROUND: This was the first prospective study to assess the safety and efficiency of MynxGrip vascular closure device (VCD) in peripheral interventions with antegrade access. METHODS AND RESULTS: We enrolled 66 consecutive patients from 1 center. All patients were discharged home on the day of procedure and were observed for adverse events at 1 and 30 days of follow-up. No major complications were observed. The rate of minor complications (conversion to manual or mechanical compression) was 7...
January 1, 2017: Vascular and Endovascular Surgery
https://www.readbyqxmd.com/read/28103515/strong-synergistic-effects-in-pla-pcl-blends-impact-of-pla-matrix-viscosity
#17
Aleksandra Ostafinska, Ivan Fortelný, Jiří Hodan, Sabina Krejčíková, Martina Nevoralová, Jana Kredatusová, Zdeněk Kruliš, Jiří Kotek, Miroslav Šlouf
Blends of two biodegradable polymers, poly(lactic acid) (PLA) and poly(ϵ-caprolactone) (PCL), with strong synergistic improvement in mechanical performance were prepared by melt-mixing using the optimized composition (80/20) and the optimized preparation procedure (a melt-mixing followed by a compression molding) according to our previous study. Three different PLA polymers were employed, whose viscosity decreased in the following order: PLC ≈ PLA1 > PLA2 > PLA3. The blends with the highest viscosity matrix (PLA1/PCL) exhibited the smallest PCL particles (d∼0...
January 10, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28102380/novel-high-temperature-ferroelectric-domain-morphology-in-pbtio3-ultrathin-films
#18
Jacob B J Chapman, Anna V Kimmel, Dorothy M Duffy
Exotic domain morphologies in ferroic materials are an exciting avenue for the development of novel nanoelectronics. In this work we have used large scale molecular dynamics to construct a strain-temperature phase diagram of the domain morphology of PbTiO3 ultrathin films. Sampling a wide interval of strain values over a temperature range up to the Curie temperature Tc, we found that epitaxial strain induces the formation of a variety of closure- and in-plane domain morphologies. The local strain and ferroelectric-antiferrodistortive coupling at the film surface vary for the strain mediated transition sequence and this could offer a route for experimental observation of the morphologies...
January 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28102351/origins-of-ripples-in-cvd-grown-few-layered-mos2-structures-under-applied-strain-at-atomic-scales
#19
Jin Wang, Raju R Namburu, Madan Dubey, Avinash M Dongare
The potential of the applicability of two-dimensional molybdenum disulfide (MoS2) structures, in various electronics, optoelectronics, and flexible devices requires a fundamental understanding of the effects of strain on the electronic, magnetic and optical properties. Particularly important is the recent capability to grow large flakes of few-layered structures using chemical vapor deposition (CVD) wherein the top layers are relatively smaller in size than the bottom layers, resulting in the presence of edges/steps across adjacent layers...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28101732/the-analysis-of-knee-joint-loading-during-drop-landing-from-different-heights-and-under-different-instruction-sets-in-healthy-males
#20
Dmitry Verniba, Jason D Vescovi, David A Hood, William H Gage
BACKGROUND: Mechanical loading during exercise has been shown to promote tissue remodeling. Safe and accessible exercise may be beneficial to populations at risk of diminished bone and joint health. We examined the effect of drop height and instruction on knee loading during a drop-landing task and proposed a task that makes use of drop heights that may be appropriate for rehabilitation purposes and functional in daily life to examine transient knee joint loads. METHODS: Twenty males (22...
December 2017: Sports Medicine—Open
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