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tensile stress

Yuhao Qiang, Jia Liu, E Du
Erythrocytes must undergo severe deformation to pass through narrow capillaries and submicronic splenic slits for several hundred thousand times in their normal lifespan. Studies of erythrocyte biomechanics have been mainly focused on cell deformability and rheology measured from a single application of stress and mostly under a static or quasi-static state using classical biomechanical techniques, such as optical tweezers and micropipette aspiration. Dynamic behavior of erythrocytes in response to cyclic stresses that contributes to the membrane failure in blood circulation is not fully understood...
May 16, 2017: Acta Biomaterialia
Hyo Jin Ji, Se-Hee Park, Kyung-Mo Cho, Suk Keun Lee, Jin Woo Kim
OBJECTIVES: Periapical lesions, including periapical cyst (PC), periapical granuloma (PG), and periapical abscess (PA), are frequently affected by chemical/physical damage during root canal treatment or severe bacterial infection, and thus, the differential diagnosis of periapical lesions may be difficult due to the presence of severe inflammatory reaction. The aim of this study was to make differential diagnosis among PC, PG, and PA under polarizing microscope. MATERIALS AND METHODS: The collagen birefringence patterns of 319 cases of PC (n = 122), PG (n = 158), and PA (n = 39) obtained using a polarizing microscope were compared...
May 2017: Restorative Dentistry & Endodontics
Jovana Radojevic, Antonios Zavaliangos
This study focuses on the evolution of mechanical behavior of starch and sodium chloride (NaCl) mixture tablets after compaction. This type of mixture has attracted attention in the past because such tablets exhibit lower tensile strengths than the ones of its individual components. Here we demonstrate that the strengths of NaCl-starch mixtures and NaCl tablets evolve after compaction in an opposite way. When stored at relative humidity (RH) of 60% NaCl tablets strengthen with time, while NaCl-starch mixtures weaken...
May 8, 2017: Journal of Pharmaceutical Sciences
Hemel N Modi, Harsimrat Singh, Felipe Orihuela-Espina, Thanos Athanasiou, Francesca Fiorentino, Guang-Zhong Yang, Ara Darzi, Daniel R Leff
OBJECTIVE: To investigate the impact of time pressure (TP) on prefrontal activation and technical performance in surgical residents during a laparoscopic suturing task. BACKGROUND: Neural mechanisms enabling surgeons to maintain performance and cope with operative stressors are unclear. The prefrontal cortex (PFC) is implicated due to its role in attention, concentration, and performance monitoring. METHODS: A total of 33 residents [Postgraduate Year (PGY)1-2 = 15, PGY3-4 = 8, and PGY5 = 10] performed a laparoscopic suturing task under "self-paced" (SP) and "TP" conditions (TP = maximum 2 minutes per knot)...
May 9, 2017: Annals of Surgery
Xavier Lepró, Paul Ehrmann, Joseph Menapace, Johann Lotscher, Swanee Shin, Richard Meissner, Salmaan Baxamusa
Although closely related to polystyrene, poly(divinylbenzene) (PDVB) has found limited utility due to the difficulties associated with its synthesis. As a highly cross-linked polymer, PDVB is infusible and insoluble and thus nearly impossible to shape into films by either melt or solvent-based processes. Here, we report the initiated chemical vapor deposition (iCVD) of nearly stress-free, highly transparent, free-standing films of PDVB up to 25 μm thick. Films initially grow under tensile intrinsic stress but become more compressive with thickness and eventually converge to zero-stress values once they reach ≥10 μm in thickness...
May 18, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Małgorzata Przybyłek, Mohamed Bakar, Mariola Mendrycka, Urszula Kosikowska, Anna Malm, Marta Worzakowska, Tomasz Szymborski, Karolina Kędra-Królik
In this paper we show an elastomeric nanocomposite that exhibits antibacterial and antifungal activity. It comprises a rubber blend matrix and a nanofiller, which is a modified bentonite clay (Nanobent® ZR2). We have developed innovative technology for the nanofiller incorporation into the rubber matrix. This new approach was successfully implemented in pilot production at the Polish chemical manufacturer Spoiwo (Spoldzielnia Pracy Chemiczno-Wytworczej 'Spoiwo', Radom, Poland). Here we reveal that addition of the functionalised bentonite affects the mechanical and thermal behaviour of elastomers...
July 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
A Bracq, G Haugou, R Delille, F Lauro, S Roth, O Mauzac
The mechanical characterization of a polymer gel used as reference backing material for blunt ballistic impact interpretation is performed at room temperature from quasi-static (0.002s(-1)) up to high strain rates (1500s(-1)). As very high strain tensile tests (350%) are conducted, an appropriate gripping device and particular strain measurement techniques are used, as well as high strain compressive tests (80%) based on retro lighting imaging. One major challenge is to carry out reliable compressive tests at high strain rates with polymeric split Hopkinson pressure bars using high-speed imaging and specific signal processing software...
April 29, 2017: Journal of the Mechanical Behavior of Biomedical Materials
Takehiro Nakahara, Marc R Dweck, Navneet Narula, David Pisapia, Jagat Narula, H William Strauss
Vascular calcification is a hallmark of atherosclerosis. The location, density, and confluence of calcification may change portions of the arterial conduit to a noncompliant structure. Calcifications may also seed the cap of a thin cap fibroatheroma, altering tensile forces on the cap and rendering the lesion prone to rupture. Many local and systemic factors participate in this process, including hyperlipidemia, ongoing inflammation, large necrotic cores, and diabetes. Vascular cells can undergo chondrogenic or osteogenic differentiation, causing mineralization of membranous bone and formation of endochondral bone...
May 2017: JACC. Cardiovascular Imaging
Madhura P Nijsure, Meet Pastakia, Joseph Spano, Michael B Fenn, Vipuil Kishore
Bone tissue engineering mandates the development of a functional scaffold that mimics the physicochemical properties of native bone. Bioglass 45S5 (BG) is a highly bioactive material known to augment bone formation and restoration. Hybrid scaffolds fabricated using collagen type I and BG resemble the organic and inorganic composition of the bone extracellular matrix and hence have been extensively investigated for bone tissue engineering applications. However, collagen-BG scaffolds developed thus far do not recapitulate the aligned collagen structure found in native bone...
May 3, 2017: Journal of Biomedical Materials Research. Part A
Laura Patricia Kaplan, Ellen Marie Høye, Peter Balling, Ludvig Muren, Jørgen Petersen, Per Poulsen, Esben Yates, Peter Skyt
New treatment modalities in radiotherapy (RT) enable delivery of highly conformal dose distributions in patients. This creates a need for precise dose verification in three dimensions (3D). A radiochromic silicone-based 3D dosimetry system has recently been developed. Such a dosimeter can be used for dose verification in deformed geometries, which requires knowledge of the dosimeter's mechanical properties. In this study we have characterized the dosimeter's elastic behaviour under tensile and compressive stress...
May 3, 2017: Physics in Medicine and Biology
Kazushige Isobe, Taisuke Watanebe, Hideo Kawabata, Yutaka Kitamura, Toshimitsu Okudera, Hajime Okudera, Kohya Uematsu, Kazuhiro Okuda, Koh Nakata, Takaaki Tanaka, Tomoyuki Kawase
BACKGROUND: Fibrin clot membranes prepared from advanced platelet-rich fibrin (A-PRF) or concentrated growth factors (CGF), despite their relatively rapid biodegradability, have been used as bioactive barrier membranes for alveolar bone tissue regeneration. As the membranes degrade, it is thought that the growth factors are gradually released. However, the mechanical and degradable properties of these membranes have not well been characterized. The purpose of this study was to mechanically and chemically characterize these membranes...
December 2017: International Journal of Implant Dentistry
Jeremy T Robinson, Maxim K Zalalutdinov, Cory D Cress, James C Culbertson, Adam L Friedman, Andrew Merrill, Brian J Landi
Using graphene nanomechanical resonators we demonstrate the extent to which the mechanical properties of multilayer graphene films are controllable, in real time, through introduction and rearrangement of defects. We show both static and re-entrant (cyclical) changes in the tensile stress using a combination of ion implantation, chemical functionalization, and thermal treatment. While the dramatic increase in static tensile stress achievable through laser annealing can be of importance for various MEMS applications, we view the direct observation of a time-variable stress as even more significant...
May 8, 2017: ACS Nano
Konstantin Yumashev, Pavel Loiko
An analytical description of the thermal stress and end-bulging component of thermal lensing is presented for monoclinic laser crystals, taking into account the anisotropy of their optical, thermal, and elastic properties for the first time, to the best of our knowledge. The geometry of longitudinal diode-pumping (plane stress approximation) is considered. The developed approach is applied to the monoclinic double tungstates (MDTs), Yb:KGW, Yb:KYW, and Yb:KLuW, yielding values of normal and shear stresses, tensile stress, and the end-bulging term...
May 1, 2017: Applied Optics
Fei Fang, Spencer P Lake
Proteoglycans (PGs) have been reported to be broadly distributed within many soft tissues and, among other roles, often contribute to mechanical properties. Although PGs were once assumed to help support load in tendon, numerous studies have found no changes to tensile mechanics after PG depletion. Since PGs are known to help sustain non-tensile loading in other tissues (e.g., compressive forces in cartilage), we hypothesized that PGs might help support non-tensile loading in the human supraspinatus tendon (SST), a commonly injured tendon which functions in a complex multiaxial loading environment...
May 2, 2017: Journal of Biomechanical Engineering
J P Torres, L-J Vandi, M Veidt, M T Heiztmann
This article features a large statistical database on the tensile properties of natural fibre reinforced composite laminates. The data presented here corresponds to a comprehensive experimental testing program of several composite systems including: different material constituents (epoxy and vinyl ester resins; flax, jute and carbon fibres), different fibre configurations (short-fibre mats, unidirectional, and plain, twill and satin woven fabrics) and different fibre orientations (0°, 90°, and [0,90] angle plies)...
June 2017: Data in Brief
Valerio Oddone, Benji Boerner, Stephanie Reich
High thermal conductivity, low thermal expansion and low density are three important features in novel materials for high performance electronics, mobile applications and aerospace. Spark plasma sintering was used to produce light metal-graphite composites with an excellent combination of these three properties. By adding up to 50 vol.% of macroscopic graphite flakes, the thermal expansion coefficient of magnesium and aluminum alloys was tuned down to zero or negative values, while the specific thermal conductivity was over four times higher than in copper...
2017: Science and Technology of Advanced Materials
Waqas Muhammad
BACKGROUND: Hard water is thought to play a key role in weakening of hair (not Hair Loss) and breakage especially when travelling is involved. In our community, commonly men do the travelling and complain more about hair problem which is why only young male individuals were included in this study. MATERIALS AND METHODS: Water samples from different districts of KPK, Pakistan, were collected and their hardness values were estimated to find the water sample of maximum and minimum water hardness in order to know the maximum hardness hair would encounter in KPK, Pakistan...
September 30, 2016: JPMA. the Journal of the Pakistan Medical Association
A C Antony, S A Akhade, Z Lu, T Liang, M J Janik, S R Phillpot, S B Sinnott
Interatomic potentials for Pt and Au are developed within the third generation charge optimized many-body (COMB3) formalism. The potentials are capable of reproducing phase order, lattice constants, and elastic constants of Pt and Au systems as experimentally measured or calculated by density functional theory. We also fit defect formation energies, surface energies and stacking fault energies for Pt and Au metals. The resulting potentials are used to map a 2D contour of the gamma surface and simulate the tensile test of 16-grain polycrystalline Pt and Au structures at 300 K...
June 7, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Seda Güneş, Funda Tıhmınlıoğlu
Recent studies in wound dressing applications offer new therapies and promote wound healing process. The aim of this study was to develop Hypericum perforatum (St John's Wort) oil incorporated chitosan films for wound dressing applications. H. perforatum oil as a potential therapeutic agent was encapsulated in chitosan film to achieve a better wound dressing material. Oil incorporated chitosan films were successfully prepared by solvent casting method in different oil concentrations (0.25-1.5%v/v). Water vapor permeability (WVP), mechanical test, swelling behavior and surface hydrophobicity were performed in order to characterize the prepared films...
April 24, 2017: International Journal of Biological Macromolecules
Guilei Wang, Jun Luo, Jinbiao Liu, Tao Yang, Yefeng Xu, Junfeng Li, Huaxiang Yin, Jiang Yan, Huilong Zhu, Chao Zhao, Tianchun Ye, Henry H Radamson
In this paper, pMOSFETs featuring atomic layer deposition (ALD) tungsten (W) using SiH4 and B2H6 precursors in 22 nm node CMOS technology were investigated. It is found that, in terms of threshold voltage, driving capability, carrier mobility, and the control of short-channel effects, the performance of devices featuring ALD W using SiH4 is superior to that of devices featuring ALD W using B2H6. This disparity in device performance results from different metal gate-induced strain from ALD W using SiH4 and B2H6 precursors, i...
December 2017: Nanoscale Research Letters
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