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https://www.readbyqxmd.com/read/28644633/role-of-preload-in-adhesion-of-rough-surfaces
#1
L Dorogin, A Tiwari, C Rotella, P Mangiagalli, B N J Persson
Adhesion between glass and bromobutyl and polydimethylsiloxane elastomers is investigated. We show that viscoelastic energy dissipation close to the opening (or closing) crack tip, and surface roughness, strongly affect the work of adhesion. We observe strong adhesion hysteresis and we show, in contrast to the Johnson-Kendall-Roberts theory prediction for elastic solids, that this results in a pull-off force, and effective work of adhesion to be dependent on the maximum loading force.
June 9, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28643855/support-surfaces-in-the-prevention-of-pressure-ulcers-in-surgical-patients-an-integrative-review
#2
Karoline Faria de Oliveira, Kleiton Gonçalves Nascimento, Adriana Cristina Nicolussi, Suzel Regina Ribeiro Chavaglia, Cleudmar Amaral de Araújo, Maria Helena Barbosa
AIM: To assess the scientific evidence about the types of support surfaces used in intraoperative surgical practice in the prevention of pressure ulcers due to surgical positioning. METHOD: This is an integrative literature review. The electronic databases Cochrane, PubMed, Web of Science, Scopus, Lilacs, and CINAHL were used. The descriptors surgical patients, support surfaces, perioperative care, patient positioning, and pressure ulcer were used in the search strategy...
June 23, 2017: International Journal of Nursing Practice
https://www.readbyqxmd.com/read/28642920/elastic-viscoelastic-and-viscoplastic-contributions-to-compliance-during-deformation-under-stress-in-prosthodontic-temporization-materials
#3
Tritala K Vaidyanathan, Jayalakshmi Vaidyanathan, David Arghavani
Purpose: The goal of this investigation was to characterize the compliance properties in selected polymers used for temporary (provisional crown and bridge) applications. Method: Polymethyl methacrylate (PMMA)- and polyethyl methacrylate (PEMA)-based JET and TRIM II were investigated along with two bisacryl composite resins (LUXATEMP and PROTEMP 3 GARANT). Rectangular samples of the resins were subjected to creep-recovery tests in a dynamic mechanical analyzer at and near the oral temperature (27 °C, 37 °C and 47 °C)...
December 2016: Acta Biomaterialia Odontologica Scandinavica
https://www.readbyqxmd.com/read/28639943/bioprintable-form-of-chitosan-hydrogel-for-bone-tissue-engineering
#4
T Tolga Demirtas, Gülseren Irmak, Menemse Gumusderelioglu
Bioprinting can be defined as the 3D patterning of living cells and other biologics by using a computer-aided layer-by-layer deposition approach. Presence of cells within the ink to usage of a "bio-ink" presents the potential to print of living tissues and organ analogs that can be implanted into damaged/diseased tissue to promote highly controlled cell-based regeneration. In this study, it was shown for the first time that chitosan solution and its composite with nanostructured bone-like hydroxyapatite (HA) can be mixed with cells and printed successfully...
June 22, 2017: Biofabrication
https://www.readbyqxmd.com/read/28638899/surface-cleaning-of-artworks-structure-and-dynamics-of-nanostructured-fluids-confined-in-polymeric-hydrogel-networks
#5
Rosangela Mastrangelo, Costanza Montis, Nicole Bonelli, Paolo Tempesti, Piero Baglioni
Nanosystems and confinement tools for the controlled release of a cleaning agent, e.g., hydrogels and microemulsions, have been used for several years for the treatment of delicate surfaces in art restoration interventions. However, notwithstanding the unprecedented achievements from an application point of view, a fundamental comprehension of their interaction mechanism is still lacking. In this study PVA hydrogels, obtained via freeze-thaw processes, are prepared as scaffolds for water-based nanostructured fluids for application in the cleaning of artworks: rheological, thermal, microscopic and scattering techniques showed that, depending on the number of freeze-thaw cycles, the hydrogels exhibit different physicochemical and viscoelastic properties, making them suitable for application in a broad range of cleaning issues...
June 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28636261/characteristics-of-corneal-biomechanical-responses-detected-by-a-non-contact-scheimpflug-based-tonometer-in-eyes-with-glaucoma
#6
Younhea Jung, Hae-Young L Park, Hee Jung Yang, Chan Kee Park
PURPOSE: To determine the corneal biomechanical properties in eyes with glaucoma using a non-contact Scheimpflug-based tonometer. METHODS: Corneal biomechanical responses were examined using a non-contact Scheimpflug-based tonometer. The tonometer parameters of the normal control group (n = 75) were compared with those of the glaucoma group (n = 136), including an analysis of glaucoma subgroups categorized by visual field loss. RESULTS: After adjusting for potential confounding factors, including the intraocular pressure (IOP), central corneal thickness (CCT), age and axial length, the deformation amplitude was smaller in the glaucoma group (1...
June 21, 2017: Acta Ophthalmologica
https://www.readbyqxmd.com/read/28635276/dynamic-viscoelastic-functions-of-liquid-crystalline-chitin-nanofibril-dispersions
#7
Morihiko Yokoi, Reina Tanaka, Tsuguyuki Saito, Akira Isogai
The dynamic viscoelastic functions of aqueous chitin nanofibril (ChNF) dispersions are defined by their liquid-crystalline fibril arrangement. Four ChNF dispersions with different structures were prepared from squid-pen β-chitin, by sonication in aqueous acetic acid at pH 3 for 4‒40 min. Squid-pen β-chitin was disintegrated into randomly-oriented bundles of ChNFs during the initial stage of sonication, and then became more finely dispersed with further sonication up to 8 min. The additional sonication resulted in the individualization of the approximately 3-nm-wide ChNFs...
June 21, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28633849/effects-of-bovine-serum-albumin-on-a-single-cavitation-bubble
#8
Shuibao Qi, Badreddine Assouar, Weizhong Chen
The dynamics and sonoluminescence (SL) of a single cavitation bubble in bovine serum albumin (BSA) aqueous solutions have been experimentally and theoretically investigated. A phase-locked integral imaging has been used to record the bubble pulsation evolutions. The results show that, under the optimum driving condition, the endurable driving pressure, maximum radius, radius compression ratio and SL intensity of the cavitation bubble increase correspondingly with the increase of BSA concentrations within the critical micelle concentration, which indicates that the addition of BSA increases the power capability of the cavitation bubble...
September 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28633824/ultrasound-assisted-extraction-of-polysaccharides-from-rhododendron-aganniphum-antioxidant-activity-and-rheological-properties
#9
Xiao Guo, Xiaofei Shang, Xuzheng Zhou, Baotang Zhao, Jiyu Zhang
In this study, we aimed to optimize the extraction of polysaccharides from the leaves of Rhododendron aganniphum and investigate its rheological properties and antioxidant activity. After optimizing the operating parameters using a Box-Behnken design (BBD), the results showed that the optimal ultrasound-assisted extraction conditions were as follows: extraction temperature, 55°C; liquid-solid ratio, 25:1; extraction time, 2.2h; and ultrasound treatment power, 200W. The optimized experimental yield of polysaccharides by ultrasound-assisted extraction (PUAE) was 9...
September 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28633066/an-emg-assisted-modeling-approach-to-assess-passive-lumbar-tissue-loading-in-vivo-during-trunk-bending
#10
Xiaopeng Ning
Lower back pain (LBP) is a condition with high prevalence and high cost both in the United States and around the world. The magnitude of mechanical loading on spine is strongly associated with the occurrence of LBP. Previously, to assess spinal loading, biologically assisted biomechanical models were developed to estimate trunk muscle contraction forces. Loadings on lumbar passive tissues are estimated using anatomical models. However, despite the substantial individual variability in lumbar ligament geometry and viscoelastic properties, the existing anatomical models do not account for these differences...
June 10, 2017: Journal of Electromyography and Kinesiology
https://www.readbyqxmd.com/read/28631757/resolving-mixed-mechanisms-of-protein-subdiffusion-at-the-t-cell-plasma-membrane
#11
Yonatan Golan, Eilon Sherman
The plasma membrane is a complex medium where transmembrane proteins diffuse and interact to facilitate cell function. Membrane protein mobility is affected by multiple mechanisms, including crowding, trapping, medium elasticity and structure, thus limiting our ability to distinguish them in intact cells. Here we characterize the mobility and organization of a short transmembrane protein at the plasma membrane of live T cells, using single particle tracking and photoactivated-localization microscopy. Protein mobility is highly heterogeneous, subdiffusive and ergodic-like...
June 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28629872/sevoflurane-relieves-lung-function-deterioration-after-cardiopulmonary-bypass
#12
Adam L Balogh, Ferenc Peták, Gergely H Fodor, Roberta Sudy, Barna Babik
OBJECTIVE: To investigate sevoflurane's potential to alleviate the detrimental pulmonary changes after cardiopulmonary bypass (CPB). DESIGN: Prospective, randomized clinical investigation. SETTING: University hospital. PARTICIPANTS: One hundred ninety patients undergoing elective cardiac surgery. INTERVENTIONS: Ninety-nine patients under intravenous anesthesia were administered 1 minimal alveolar concentration of sevoflurane for 5 minutes after being weaned from CPB (group SEV); intravenous anesthesia was maintained in the other 91 patients (group CTRL)...
February 24, 2017: Journal of Cardiothoracic and Vascular Anesthesia
https://www.readbyqxmd.com/read/28628873/complexation-thermodynamics-of-%C3%AE-cyclodextrin-with-ionic-surfactants-in-water
#13
Daniel Ondo, Miguel Costas
The interaction of α-cyclodextrin (α-CD) with ten ionic surfactants (S) in water was systematically examined using isothermal titration calorimetry. The S comprised cationic and anionic head groups while the hydrocarbon alkyl chain length varied from eight to fourteen carbon atoms. The heat data were measured at five temperatures ranging from 283.15K to 318.15K and were treated simultaneously allowing the estimation of a thermodynamically consistent temperature dependence of the equilibrium constant, as well as the enthalpy and heat capacity for the sequential formation of the [α-CD·S] and the [α-CD2·S] inclusion complexes...
June 8, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28624047/viscoelastic-monitoring-in-pediatric-trauma-a-survey-of-pediatric-trauma-society-members
#14
Robert T Russell, Ilan I Maizlin, Adam M Vogel
BACKGROUND: Viscoelastic monitoring (VEM), including thromboelastography (TEG) and rotational thromboelastometry (ROTEM) in the setting of goal-directed hemostatic resuscitation has been shown to improve outcomes in adult trauma. The American College of Surgeons (ACS) Committee on Trauma recommends that "thromboelastography should be available at level I and level II trauma centers". The purpose of this study is to determine the current availability and utilization of VEM in pediatric trauma...
June 15, 2017: Journal of Surgical Research
https://www.readbyqxmd.com/read/28623360/endothelial-cell-derived-extracellular-vesicles-size-dependently-exert-procoagulant-activity-detected-by-thromboelastometry
#15
Wolfgang Holnthoner, Cornelia Bonstingl, Carina Hromada, Severin Muehleder, Johannes Zipperle, Stefan Stojkovic, Heinz Redl, Johann Wojta, Herbert Schöchl, Johannes Grillari, Sylvia Weilner, Christoph J Schlimp
Endothelial cells (ECs) are major modulators of hemostasis by expressing and releasing pro- and anticoagulant mediators into the circulation. Previous studies showed that cultured ECs release procoagulant mediators into cell culture supernatants as evidenced by the reduction of viscoelastic clotting time. This effect was reversed with an anti-tissue factor antibody. Here, we aimed to investigate whether tissue factor (TF) was released by endothelial-derived extracellular vesicles (EVs) and which portion of the released vesicles displays the most prominent procoagulant properties...
June 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28622632/applying-rheological-analysis-to-better-understand-the-mechanism-of-acid-conditioning-on-activated-sludge-dewatering
#16
Hou-Feng Wang, Yun-Jie Ma, Hua-Jie Wang, Hao Hu, Hai-Yang Yang, Raymond J Zeng
The pH value is a key parameter and affects sludge dewatering. Comprehensive understanding of the effects and mechanism of pH is important for sludge treatment process and sludge dewatering. The goal of this study was to evaluate the proposed mechanism of acid conditioning on sludge dewatering based on rheological analysis. At lower sludge pH, changes in floc structure, surface properties, and flocculation improved the performance of dewatering. Additionally, lower sludge pH caused the hydrolysis of EPS and intracellular materials, which released greater amounts of bound water...
May 13, 2017: Water Research
https://www.readbyqxmd.com/read/28619454/carvacrol-clay-hybrids-loaded-into-in-situ-gelling-films
#17
M Tenci, S Rossi, C Aguzzi, E Carazo, G Sandri, M C Bonferoni, P Grisoli, C Viseras, C M Caramella, F Ferrari
The aim of the present work was the development of polymer films loaded with a carvacrol (CVR)/clay hybrid (HYBD) for the delivery of CRV in infected skin ulcer treatment. Different clays were considered: montmorrilonite, halloysite and palygorskite (PHC). CRV incorporation in PHC reduced its volatility. HYBD showed 20% w/w CRV loading capacity and was able to preserve CRV antioxidant properties. HYBD was characterized by improved antimicrobial properties against S. aureus and E. coli and cytocompatibility towards human fibroblasts with respect to pure CRV...
June 12, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28618545/mean-lagrangian-formalism-and-covariance-of-fluid-turbulence
#18
Taketo Ariki
Mean-field-based Lagrangian framework is developed for the fluid turbulence theory, which enables physically objective discussions, especially, of the history effect. Mean flow serves as a purely geometrical object of Lie group theory, providing useful operations to measure the objective rate and history integration of the general tensor field. The proposed framework is applied, on the one hand, to one-point closure model, yielding an objective expression of the turbulence viscoelastic effect. Application to two-point closure, on the other hand, is also discussed, where natural extension of known Lagrangian correlation is discovered on the basis of an extended covariance group...
May 2017: Physical Review. E
https://www.readbyqxmd.com/read/28618301/noninvasive-measurement-of-wave-speed-of-porcine-cornea-in-ex-vivo-porcine-eyes-for-various-intraocular-pressures
#19
Boran Zhou, Arthur J Sit, Xiaoming Zhang
The objective of this study was to extend an ultrasound surface wave elastography (USWE) technique for noninvasive measurement of ocular tissue elastic properties. In particular, we aim to establish the relationship between the wave speed of cornea and the intraocular pressure (IOP). Normal ranges of IOP are between 12 and 22mmHg. Ex vivo porcine eye balls were used in this research. The porcine eye ball was supported by the gelatin phantom in a testing container. Some water was pour into the container for the ultrasound measurement...
June 7, 2017: Ultrasonics
https://www.readbyqxmd.com/read/28617909/development-of-a-flow-evolution-network-model-for-the-stress-strain-behavior-of-poly-l-lactide
#20
Maureen L Dreher, Srinidhi Nagaraja, Jorgen Bergstrom, Danika Hayman
Computational modeling is critical to medical device development and has grown in its utility for predicting device performance. Additionally, there is an increasing trend to use absorbable polymers for the manufacturing of medical devices. However, computational modeling of absorbable devices is hampered by a lack of appropriate constitutive models that capture their viscoelasticity and post-yield behavior. The objective of this study was to develop a constitutive model that incorporated viscoplasticity for a common medical absorbable polymer...
June 15, 2017: Journal of Biomechanical Engineering
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