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https://www.readbyqxmd.com/read/28930189/microstructural-investigation-of-heat-treated-ultra-high-performance-concrete-for-optimum-production
#1
Sung-Hoon Kang, Ji-Hyung Lee, Sung-Gul Hong, Juhyuk Moon
For optimum production of ultra-high performance concrete (UHPC), the material and microstructural properties of UHPC cured under various heat treatment (HT) conditions are studied. The effects of HT temperature and duration on the hydration reaction, microstructure, and mechanical properties of UHPC are investigated. Increasing HT temperature accelerates both cement hydration and pozzolanic reaction, but the latter is more significantly affected. This accelerated pozzolanic reaction in UHPC clearly enhances compressive strength...
September 20, 2017: Materials
https://www.readbyqxmd.com/read/28928507/characteristics-of-xanthosoma-sagittifolium-roots-during-cooking-using-physicochemical-analysis-uniaxial-compression-multispectral-imaging-and-low-field-nmr-spectroscopy
#2
Abena Achiaa Boakye, María Gudjónsdóttir, Jacob Lercke Skytte, Ioannis S Chronakis, Faustina Dufie Wireko-Manu, Ibok Oduro
To effectively promote the industrial utilization of cocoyam (Xanthosoma sagittifolium) roots for enhanced food sustainability and security, there is a need to study their molecular, mechanical and physicochemical properties in detail. The physicochemical and textural characteristics of the red and white varieties of cocoyam roots were thus analysed by low field nuclear magnetic resonance relaxometry, multispectral imaging, uniaxial compression testing, and relevant physicochemical analysis in the current study...
August 2017: Journal of Food Science and Technology
https://www.readbyqxmd.com/read/28927931/polyurethane-foam-scaffold-as-in-vitro-model-for-breast-cancer-bone-metastasis
#3
Valentina Angeloni, Nicola Contessi, Cinzia De Marco, Serena Bertoldi, Maria Cristina Tanzi, Maria Grazia Daidone, Silvia Farè
Breast cancer (BC) represents the most incident cancer case in women (29%), with high mortality rate. Bone metastasis occurs in 20-50% cases and, despite advances in BC research, the interactions between tumor cells and the metastatic microenvironment are still poorly understood. In vitro 3D models gained great interest in cancer research, thanks to the reproducibility, the 3D spatial cues and associated low costs, compared to in vivo and 2D in vitro models. In this study, we investigated the suitability of a poly-ether-urethane (PU) foam as 3D in vitro model to study the interactions between BC tumor-initiating cells and the bone microenvironment...
September 16, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28927930/biodegradable-and-adjustable-sol-gel-glass-based-hybrid-scaffolds-from-multi-armed-oligomeric-building-blocks
#4
Christian Kascholke, Stephan Hendrikx, Tobias Flath, Dzmitry Kuzmenka, Hans-Martin Dörfler, Dirk Schumann, Mathias Gressenbuch, F Peter Schulze, Michaela Schulz-Siegmund, Michael C Hacker
Biodegradability is a crucial characteristic to improve the clinical potential of sol-gel-derived glass materials. To this end, a set of degradable organic/inorganic class II hybrids from a tetraethoxysilane(TEOS)-derived silica sol and oligovalent cross-linker oligomers containing oligo(D,L-lactide) domains was developed and characterized. A series of 18 oligomers (Mn: 1100-3200 Da) with different degrees of ethoxylation and varying length of oligoester units was established and chemical composition was determined...
September 16, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28927929/mechanical-characterization-of-structurally-porous-biomaterials-built-via-additive-manufacturing-experiments-predictive-models-and-design-maps-for-load-bearing-bone-replacement-implants
#5
D Melancon, Z S Bagheri, R B Johnston, L Liu, M Tanzer, D Pasini
Porous biomaterials can be additively manufactured with micro-architecture tailored to satisfy the stringent mechano-biological requirements imposed by bone replacement implants. In a previous investigation, we introduced structurally porous biomaterials, featuring strength five times stronger than commercially available porous materials, and confirmed their bone ingrowth capability in an in-vivo canine model. While encouraging, the manufactured biomaterials showed geometric mismatches between their internal porous architecture and that of its as-designed counterpart, as well as discrepancies between predicted and tested mechanical properties, issues not fully elucidated...
September 16, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28924624/nano-mechanics-of-ionic-liquids-at-dielectric-and-metallic-interfaces
#6
Léo Garcia, Léa Jacquot, Elisabeth Charlaix, Benjamin Cross
Using a dynamic surface force apparatus, we investigate the nano-mechanics and the nano-rheology of an ionic liquid at dielectric and metallic solid surfaces. On smooth dielectric Pyrex surfaces, we find an ordered interfacial phase extending over less than 3 nm away from the top of the layer, with a compression modulus of 15 MPa extracted from the profile of the oscillatory forces. We discuss the boundary flow of the Newtonian bulk phase on this ordered interfacial layer. On metallic platinum surfaces, our hydrodynamic measurements evidence an interfacial soft solid layer extending up to 20 nm away from the top of the layer...
September 19, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28923547/how-oral-environment-simulation-affects-ceramic-failure-behavior
#7
Ediléia Lodi, Kátia R Weber, Paula Benetti, Pedro H Corazza, Álvaro Della Bona, Márcia Borba
STATEMENT OF PROBLEM: Investigating the mechanical behavior of ceramics in a clinically simulated scenario contributes to the development of new and tougher materials, improving the clinical performance of restorations. The optimal in vitro environment for testing is unclear. PURPOSE: The purpose of this in vitro study was to investigate the failure behavior of a leucite-reinforced glass-ceramic under compression loading and fatigue in different simulated oral environment conditions...
September 16, 2017: Journal of Prosthetic Dentistry
https://www.readbyqxmd.com/read/28923319/mechanics-of-pharmaceutical-pellets-constitutive-properties-deformation-and-breakage-behavior-%C3%A2
#8
Alexander Russell, Rok Šibanc, Rok Dreu, Peter Müller
To ensure robust manufacturing of unit-based oral solid dosage forms with minimal structural imperfections and high mechanical reliability across subsequent processing unit operations (for e.g. withstanding mechanical stresses during coating, optional axial compression, handling, packaging, storage and transport conditions), process design should include consideration of precise limits of accurate micro, macro and bulk properties of the constituent pellets. This communication presents a comprehensive intricate database of micro-mechanical properties' and breakage probability distribution functions of pellets, illustrating the stiffening and strengthening effects of coatings and the softening and weakening effects of structural moisture...
September 15, 2017: Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28923094/high-magnitude-compression-accelerates-the-premature-senescence-of-nucleus-pulposus-cells-via-the-p38-mapk-ros-pathway
#9
Pei Li, Gang Hou, Ruijie Zhang, Yibo Gan, Yuan Xu, Lei Song, Qiang Zhou
BACKGROUND: Mechanical overloading can lead to disc degeneration. Nucleus pulposus (NP) cell senescence is aggravated within the degenerated disc. This study was designed to investigate the effects of high compression on NP cell senescence and the underlying molecular mechanism of this process. METHODS: Rat NP cells seeded in decalcified bone matrix were subjected to non-compression (control) or compression (2% or 20% deformation, 1.0 Hz, 6 hours/day). The reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) and the p38 MAPK inhibitor SB203580 were used to investigate the roles of the ROS and p38 MAPK pathway under high-magnitude compression...
September 18, 2017: Arthritis Research & Therapy
https://www.readbyqxmd.com/read/28922351/estimation-of-the-mechanical-properties-of-the-eye-through-the-study-of-its-vibrational-modes
#10
M Á Aloy, J E Adsuara, P Cerdá-Durán, M Obergaulinger, J J Esteve-Taboada, T Ferrer-Blasco, R Montés-Micó
Measuring the eye's mechanical properties in vivo and with minimally invasive techniques can be the key for individualized solutions to a number of eye pathologies. The development of such techniques largely relies on a computational modelling of the eyeball and, it optimally requires the synergic interplay between experimentation and numerical simulation. In Astrophysics and Geophysics the remote measurement of structural properties of the systems of their realm is performed on the basis of (helio-)seismic techniques...
2017: PloS One
https://www.readbyqxmd.com/read/28921994/anisotropic-cracking-of-nanocrystal-superlattices
#11
Benjamin T Diroll, Xuedan Ma, Yaoting Wu, Christopher B Murray
The synthesis colloidal nanocrystals in non-polar organic solvents has led to exceptional size- and shape-control, enabling the formation of nanocrystal superlattices isostructural to atomic lattices built with nanocrystals rather than atoms. The long aliphatic ligands (e.g. oleic acid) used to achieve this control separate nanocrystals too far in the solid-state for most charge-transporting devices. Solid-state ligand exchange, which brings particles closer together and enhances conductivity, necessitates large changes in the total volume of the solid (compressive stress), which leads to film cracking...
September 18, 2017: Nano Letters
https://www.readbyqxmd.com/read/28919827/is-a-mechanical-assist-device-better-than-manual-chest-compression-a-randomized-controlled-trial
#12
Chaiyaporn Yuksen, Thidathit Prachanukool, Kasamon Aramvanitch, Nuttamon Thongwichit, Kittisak Sawanyawisuth, Yuwares Sittichanbuncha
BACKGROUND: Chest compression quality is a determinant of survival from sudden cardiac arrest. The CPR RsQ Assist Device (CPR RAD) is a new cardiopulmonary resuscitation device for chest compression. It is operated manually but it does not pull up on the chest on the up stroke. The aim of this study was to compare the CPR RAD with standard manual compression in terms of chest compression quality in a manikin model. METHODS: Participants were randomly assigned to either the device or manual chest compression group...
2017: Open Access Emergency Medicine: OAEM
https://www.readbyqxmd.com/read/28919399/a-numerical-model-suggests-the-interplay-between-nuclear-plasticity-and-stiffness-during-a-perfusion-assay
#13
Solenne Deveraux, Rachele Allena, Denis Aubry
Cell deformability is a necessary condition for a cell to be able to migrate, an ability that is vital both for healthy and diseased organisms. The nucleus being the largest and stiffest organelle, it often is a barrier to cell migration. It is thus essential to characterize its mechanical behaviour. First, we numerically investigate the visco-elasto-plastic properties of the isolated nucleus during a compression test. This simulation highlights the impact of the mechanical behaviour of the nuclear lamina and the nucleoplasm on the overall plasticity...
September 14, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28917989/shear-strength-of-pharmaceutical-tablets-theoretical-considerations-evaluation-and-relation-with-the-capping-tendency-of-biconvex-tablets
#14
V Mazel, H Diarra, V Busignies, P Tchoreloff
Capping is a major industrial issue during pharmaceutical powder compression, especially in the case of biconvex tablets. Several articles proposed that capping was in fact a failure in shear. Shear strength should thus be interesting to study the capping tendency of a formulation. In this work, the ratio between the shear strength and the tensile strength obtained by diametral compression was first studied from a theoretical point of view considering different failure criteria. Then, a shear test usually performed on bilayer tablets was adapted to monolayer tablets...
September 13, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28917918/chitosan-composite-hydrogels-reinforced-with-natural-clay-nanotubes
#15
Biao Huang, Mingxian Liu, Changren Zhou
Here, chitosan composites hydrogels were prepared by addition of halloysite nanotubes (HNTs) in the chitosan KOH/LiOH/urea solution. The raw chitosan and chitosan/HNTs composite hydrogels were obtained by heat treatment at 60°C for 8h and then regeneration in ethanol solution. The viscosity of the composite solution is increased with HNTs content. The Fourier transform infrared spectroscopy (FT-IR) shows that the hydrogen bonds interactions exist between the HNTs and the chitosan. X-ray diffraction (XRD) results show that the crystal structure of HNT is not changed in the composite hydrogels...
November 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28917879/laccase-tempo-oxidation-in-the-production-of-mechanically-strong-arabinoxylan-and-glucomannan-aerogels
#16
Kirsti Parikka, Ida Nikkilä, Leena Pitkänen, Abdul Ghafar, Tuula Sontag-Strohm, Maija Tenkanen
New wheat arabinoxylan and konjac glucomannan hydrogels and aerogels were prepared by hemiacetal crosslinking induced by laccase/TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) -catalysed oxidation, which selectively converts the primary hydroxyl groups to aldehydes. The degree of oxidation of the product aldehydes was ca. 10% of the total carbohydrates of the polysaccharides, and the determination of storage and viscous moduli of the oxidised samples showed that they had formed true hydrogels. Two freezing methods for the hydrogels, conventional freezing and ice crystal templating, were investigated for aerogel production, the ice crystal templated products especially were mechanically strong in compression test against the ice crystals' growth direction...
November 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28917256/postoperative-stereotactic-body-radiotherapy-for-spinal-metastases
#17
Majed Alghamdi, Chia-Lin Tseng, Sten Myrehaug, Pejman Maralani, Chris Heyn, Hany Soliman, Young Lee, Mark Ruschin, Leodante Da Costa, Victor Yang, Mikki Campbell, Arjun Sahgal
Spine is a common site of metastases in cancer patients. Spine surgery is indicated for select patients, typically those with mechanical instability and/or malignant epidural spinal cord (or cauda equina) compression. Although post-operative conventional palliative external beam radiation therapy has been the standard of care, technical improvements in radiation planning and image-guided radiotherapy have allowed for the application of stereotactic body radiotherapy (SBRT) to the spine. Spine SBRT is intended to ablate residual tumor and optimize local control by delivering several fold greater biologically effective doses...
September 2017: Chinese Clinical Oncology
https://www.readbyqxmd.com/read/28916883/different-post-processing-conditions-for-3d-bioprinted-%C3%AE-tricalcium-phosphate-scaffolds
#18
Liciane Sabadin Bertol, Rodrigo Schabbach, Luis Alberto Loureiro Dos Santos
The development of 3D printing hardware, software and materials has enabled the production of bone substitute scaffolds for tissue engineering. Calcium phosphates cements, such as those based on α-tricalcium phosphate (α-TCP), have recognized properties of osteoinductivity, osteoconductivity and resorbability and can be used to 3D print scaffolds to support and induce tissue formation and be replaced by natural bone. At present, however, the mechanical properties found for 3D printed bone scaffolds are only satisfactory for non-load bearing applications...
September 15, 2017: Journal of Materials Science. Materials in Medicine
https://www.readbyqxmd.com/read/28916741/enhancement-of-water-diffusion-and-compression-performance-of-crosslinked-alginate-films-with-a-minuscule-amount-of-graphene-oxide
#19
Ángel Serrano-Aroca, Juan-Francisco Ruiz-Pividal, Mar Llorens-Gámez
A series of calcium alginate composite hydrogels with several calcium chloride contents ranging from 3 to 18 wt.% with and without 0.1 wt.% of graphene oxide (GO) was prepared in order to study the effect of crosslinking and nanofilling on water diffusion and compression performance. Thus, for high crosslinker contents, these composite hydrogels exhibited ultrafast diffusion of liquid water and excellent compression properties as compared with control (0 wt.% GO and the same crosslinking). These remarkable results are produced due to calcium cations are able to crosslink alginate and also graphene oxide nanosheets to form large crosslinked GO networks inside the calcium alginate hydrogels...
September 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28916305/unusual-causes-of-venous-thrombosis-bladder-distension-and-uterine-mass
#20
Michael L Caparelli, Sepehr Lalezari, Steven Perlman
Thrombosis of the inferior vena cava (IVC) continues to be a rare event and there is a scarcity of evidence with regard to its etiology. One source for IVC thrombosis is external compression from adjacent structures. In this case series we present one case of IVC thrombosis caused by a severely distended bladder and a case of external iliac thrombosis caused by external compression from an abnormally enlarged uterus. The treatment of each case is varied and included novel oral anticoagulation (NOAC), catheter-directed thrombolysis in conjunction with mechanical thrombectomy, or a combination of these...
September 12, 2017: Annals of Vascular Surgery
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