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https://www.readbyqxmd.com/read/28098315/a-ph-responsive-wormlike-micellar-system-of-a-noncovalent-interaction-based-surfactant-with-a-tunable-molecular-structure
#1
Wanli Kang, Pengxiang Wang, Haiming Fan, Hongbin Yang, Caili Dai, Xia Yin, Yilu Zhao, Shujun Guo
Responsive wormlike micelles are very useful in a number of applications, whereas it is still challenging to create dramatic viscosity changes in wormlike micellar systems. Here we developed a pH-responsive wormlike micellar system based on a noncovalent constructed surfactant, which is formed by the complexation of N-erucamidopropyl-N,N-dimethylamine (UC22AMPM) and citric acid at the molar ratio of 3 : 1 (EACA). The phase behavior, aggregate microstructure and viscoelasticity of EACA solutions were investigated by macroscopic appearance observation, rheological and cryo-TEM measurements...
January 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28098305/phase-behaviour-and-temperature-responsive-properties-of-a-gemini-surfactant-brij-30-water-system
#2
Chuanhong Han, Yan Guo, Xiaoxiao Chen, Meihuan Yao, Yingtian Zhang, Qirui Zhang, Xilian Wei
The phase behaviour of a ternary system composed of cationic gemini surfactant 2-hydroxypropyl-1,3-bis(myristyldimethylammonium chloride) (14-3(OH)-14(2Cl)), nonionic surfactant polyoxyethylene laurel ether (C12H25(OCH2CH2)10OH, Brij-30) and H2O was studied and its phase diagram was determined. In several different phase regions identified in the phase diagram, the viscoelastic worm-like micellar solution region was investigated. The focus of the investigation was the increase in the viscosity of the micellar solution with the temperature and the Brij-30 content, as suggested by a partial region of the triangular phase diagram...
January 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28094528/noncontact-viscoelastic-measurement-of-polymer-thin-films-in-a-liquid-medium-using-a-long-needle-afm
#3
Dongshi Guan, Chloé Barraud, Elisabeth Charlaix, Penger Tong
We report noncontact measurement of the viscoelastic property of polymer thin films in a liquid medium using frequency-modulation atomic force microscopy (FM-AFM) with a newly developed long-needle probe. The probe contains a long vertical glass fiber with one end adhered to a cantilever beam and the other end with a sharp tip placed near the liquid-film interface. The nanoscale flow generated by the resonant oscillation of the needle tip provides a precise hydrodynamic force acting on the soft surface of the thin film...
January 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28094486/understanding-developmental-hemostasis-through-the-use-of-viscoelastic-tests-of-whole-blood-coagulation
#4
David Faraoni, James D O'Leary
No abstract text is available yet for this article.
January 17, 2017: Minerva Anestesiologica
https://www.readbyqxmd.com/read/28092386/closer-insight-into-the-structure-of-moderate-to-densely-branched-comb-polymers-by-combining-modelling-and-linear-rheological-measurements
#5
Mostafa Ahmadi, Sandie Pioge, Charles-Andre Fustin, Jean-Francois Gohy, Evelyne van Ruymbeke
Synthesis of combs with well-entangled backbones and long branches with high densities has always been a challenge. Steric hindrance frequently leads to coupling of chains and structural imperfections that cannot be easily distinguished by traditional characterization methods. Research studies have therefore tried to use a combination of different methods to obtain more information on the actual microstructures. In this work, a grafting-from approach is used to synthesize poly(n-butyl acrylate) combs using atom transfer radical polymerization (ATRP) in three steps including the synthesis of a backbone, cleavage of protecting groups and growth of side branches...
January 16, 2017: Soft Matter
https://www.readbyqxmd.com/read/28090125/a-multi-physics-model-for-ultrasonically-activated-soft-tissue
#6
Rahul Suvranu De
A multi-physics model has been developed to investigate the effects of cellular level mechanisms on the thermomechanical response of ultrasonically activated soft tissue. Cellular level cavitation effects have been incorporated in the tissue level continuum model to accurately determine the thermodynamic states such as temperature and pressure. A viscoelastic material model is assumed for the macromechanical response of the tissue. The cavitation model based equation-of-state provides the additional pressure arising from evaporation of intracellular and cellular water by absorbing heat due to structural and viscoelastic heating in the tissue, and temperature to the continuum level thermomechanical model...
February 1, 2017: Computer Methods in Applied Mechanics and Engineering
https://www.readbyqxmd.com/read/28088300/cytoplasmic-rna-protein-particles-exhibit-non-gaussian-subdiffusive-behavior
#7
Thomas J Lampo, Stella Stylianidou, Mikael P Backlund, Paul A Wiggins, Andrew J Spakowitz
The cellular cytoplasm is a complex, heterogeneous environment (both spatially and temporally) that exhibits viscoelastic behavior. To further develop our quantitative insight into cellular transport, we analyze data sets of mRNA molecules fluorescently labeled with MS2-GFP tracked in real time in live Escherichia coli and Saccharomyces cerevisiae cells. As shown previously, these RNA-protein particles exhibit subdiffusive behavior that is viscoelastic in its origin. Examining the ensemble of particle displacements reveals a Laplace distribution at all observed timescales rather than the Gaussian distribution predicted by the central limit theorem...
January 11, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28088071/discrete-quasi-linear-viscoelastic-damping-analysis-of-connective-tissues-and-the-biomechanics-of-stretching
#8
Behzad Babaei, Aaron J Velasquez-Mao, Stavros Thomopoulos, Elliot L Elson, Steven D Abramowitch, Guy M Genin
The time- and frequency-dependent properties of connective tissue define their physiological function, but are notoriously difficult to characterize. Well-established tools such as linear viscoelasticity and the Fung quasi-linear viscoelastic (QLV) model impose forms on responses that can mask true tissue behavior. Here, we applied a more general discrete quasi-linear viscoelastic (DQLV) model to identify the static and dynamic time- and frequency-dependent behavior of rabbit medial collateral ligaments. Unlike the Fung QLV approach, the DQLV approach revealed that energy dissipation is elevated at a loading period of ∼10s...
December 22, 2016: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28074943/the-influence-of-flaxseed-gum-on-the-microrheological-properties-and-physicochemical-stability-of-whey-protein-stabilized-%C3%AE-carotene-emulsions
#9
Duoxia Xu, Yameng Qi, Xu Wang, Xin Li, Shaojia Wang, Yanping Cao, Chengtao Wang, Baoguo Sun, Eric Decker, Atikorn Panya
The impact of flaxseed gum (FG) on the microrheological properties and physicochemical stability of whey protein isolate (WPI) stabilized β-carotene emulsions at pH 3.0 was studied. A layer-by-layer electrostatic deposition method was used to prepare multilayered β-carotene emulsions with interfacial membranes consisting of WPI and FG. The microrheological behavior of the multilayered β-carotene emulsions was measured through the diffusive wave spectroscopy technique. WPI alone and WPI-FG (concentration of FG = 0...
January 11, 2017: Food & Function
https://www.readbyqxmd.com/read/28074815/effect-of-heparin-and-bivalirudin-on-the-kinetics-of-clot-formation-viscoelastic-coagulation-testing
#10
Suruchi Hasija, Poonam Malhotra Kapoor
No abstract text is available yet for this article.
January 2017: Annals of Cardiac Anaesthesia
https://www.readbyqxmd.com/read/28069450/micromechanical-modeling-of-rate-dependent-behavior-of-connective-tissues
#11
A Fallah, M T Ahmadian, K Firozbakhsh, M M Aghdam
In this paper, a constitutive and micromechanical model for prediction of rate-dependent behavior of connective tissues (CTs) is presented. Connective tissues are considered as nonlinear viscoelastic material. The rate-dependent behavior of CTs is incorporated into model using the well-known quasi-linear viscoelasticity (QLV) theory. A planar wavy representative volume element (RVE) is considered based on the tissue microstructure histological evidences. The presented model parameters are identified based on the available experiments in the literature...
January 7, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28068950/corneal-hysteresis-in-patients-with-glaucoma-like-optic-discs-ocular-hypertension-and-glaucoma
#12
Melissa L Murphy, Olya Pokrovskaya, Marie Galligan, Colm O'Brien
BACKGROUND: To compare corneal hysteresis (CH) measurements between patients with glaucoma, ocular hypertension (OHT) and glaucoma-like optic discs (GLD)- defined as a cup to disc ratio greater than or equal to 0.6 with normal intraocular pressure (IOP) and visual fields. The secondary aim was to investigate whether corneal resistance factor (CRF) and central corneal thickness (CCT) differ between patient groups. METHODS: In this cross sectional study a total of 123 patients (one eye each) were recruited from a glaucoma outpatient department to undergo ocular response analyser (ORA) testing and ultrasound pachymetry as well as clinical examination...
January 10, 2017: BMC Ophthalmology
https://www.readbyqxmd.com/read/28068607/micro-electromechanical-film-bulk-acoustic-sensor-for-plasma-and-whole-blood-coagulation-monitoring
#13
Da Chen, Shuren Song, Jilong Ma, Zhen Zhang, Peng Wang, Weihui Liu, Qiuquan Guo
Monitoring blood coagulation is an important issue in the surgeries and the treatment of cardiovascular diseases. In this work, we reported a novel strategy for the blood coagulation monitoring based on a micro-electromechanical film bulk acoustic resonator. The resonator was excited by a lateral electric field and operated under the shear mode with a frequency of 1.9GHz. According to the apparent step-ladder curves of the frequency response to the change of blood viscoelasticity, the coagulation time (prothrombin time) and the coagulation kinetics were measured with the sample consumption of only 1μl...
December 30, 2016: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28068542/cost-effective-surface-modification-for-galinstan%C3%A2-lyophobicity
#14
Shantanu Shrikant Kadlaskar, Jun Hyeon Yoo, Abhijeet, Jeong Bong Lee, Wonjae Choi
In this paper we investigate the feasibility of using a cost-effective fabrication method based on sandblasting, chemical etching and spray coating processes, to render common surfaces to be non-wettable by Galinstan®. Although Galinstan® is a non-toxic liquid metal alternative to mercury, the viscoelastic and extremely wetting characteristics of Galinstan® have been the major bottleneck limiting the wide applicability of the gallium-based liquid metal. This paper tries to accomplish non-wettability to Galinstan® by combining surface texture and chemistry with the unique property of Galinstan®, that is, its high surface tension and yield strength that prevent the penetration of the liquid metal into surface asperities...
December 28, 2016: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28066548/nanomechanical-properties-of-protein-dna-layers-with-different-oligonucleotide-tethers
#15
Cristina Gutiérrez Sánchez, Qiang Su, Sabine Wenderhold-Reeb, Gilbert Nöll
The multi-ligand binding flavoprotein dodecin is reconstituted on top of flavin-terminated oligonucleotide monolayers. A detailed quartz crystal microbalance with a dissipation monitoring (QCM-D) study showing how the length and flexibility of the oligonucleotide tethers influence the stability and the viscoelastic properties of the resulting DNA-protein layers is presented. Relatively dense protein layers can be obtained, if the length of the tethers is in the same range as the diameter of dodecin. When significantly longer tethers are used, less dense layers are formed...
June 24, 2016: RSC Advances
https://www.readbyqxmd.com/read/28065929/standardized-static-and-dynamic-evaluation-of-myocardial-tissue-properties
#16
Sherif Ramadan, Narinder Paul, Hani E Naguib
INTRODUCTION: Quantifying the mechanical behaviours of soft biological tissues is of considerable research interest. However, validity and reproducibility between different researchers and apparatus is questionable. This study aims to quantify the mechanical properties of myocardium while investigating methodologies that can standardize biological tissue testing. MATERIALS AND METHODS: Tensile testing was performed to obtain Young���s modulus and a dynamic mechanical analysis (DMA) determined the viscoelastic properties...
January 9, 2017: Biomedical Materials
https://www.readbyqxmd.com/read/28064504/development-of-l-tyrosine-based-enzyme-responsive-amphiphilic-poly-ester-urethane-nanocarriers-for-multiple-drug-delivery-to-cancer-cells
#17
Rajendra Aluri, Manickam Jayakannan
New classes of enzymatic-biodegradable amphiphilic poly(ester-urethane)s were designed and developed from l-tyrosine amino acid resources and their self-assembled nanoparticles were employed as multiple drug delivery vehicles in cancer therapy. The amine and carboxylic acid functional groups in l-tyrosine were converted into dual functional ester-urethane monomers and they were subjected to solvent free melt polycondensation with hydrophilic polyethylene glycols to produce comb-type poly(ester-urethane)s. The phenolic unit in the l-tyrosine was anchored with hydrophobic alkyl side chain to bring appropriate amphiphilicity in the polymer geometry to self-assemble them as stable nanoscaffolds in aqueous medium...
January 9, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28063896/clinical-correlation-of-abnormal-findings-on-magnetic-resonance-elastography-in-idiopathic-normal-pressure-hydrocephalus
#18
Avital Perry, Christopher S Graffeo, Nikoo Fattahi, Mona M ElSheikh, Nealey Cray, Arvin Arani, Richard L Ehman, Kevin J Glaser, Armando Manduca, Fredric B Meyer, John Huston
BACKGROUND: Idiopathic normal pressure hydrocephalus (iNPH) is ventriculomegaly syndrome characterized by dementia, urinary incontinence, and gait disturbance, which is potentially reversible following ventriculoperitoneal shunting (VPS). Magnetic resonance elastography (MRE) is an evolving imaging technology that noninvasively measures tissue viscoelasticity. OBJECTIVE: We studied iNPH patients using MRE prior to shunting, compared them to normal controls, and analyzed associations between MRE findings and clinical features, as a pilot assessment of MRE in iNPH...
January 4, 2017: World Neurosurgery
https://www.readbyqxmd.com/read/28060331/biomechanical-characterization-of-human-soft-tissues-using-indentation-and-tensile-testing
#19
Michelle Griffin, Yaami Premakumar, Alexander Seifalian, Peter Edward Butler, Matthew Szarko
Regenerative medicine aims to engineer materials to replace or restore damaged or diseased organs. The mechanical properties of such materials should mimic the human tissues they are aiming to replace; to provide the required anatomical shape, the materials must be able to sustain the mechanical forces they will experience when implanted at the defect site. Although the mechanical properties of tissue-engineered scaffolds are of great importance, many human tissues that undergo restoration with engineered materials have not been fully biomechanically characterized...
December 13, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28059426/the-effect-of-colloidal-aggregates-on-fat-crystal-networks
#20
Raamanand R Chauhan, Roel P A Dullens, Krassimir P Velikov, Dirk G A L Aarts
We investigate the role of a colloidal model system in the crystallization and network formation of lipids. This system consists of fractal fumed silica aggregates. We look at the influence of different solid fat concentrations and fumed silica concentrations on the resulting gel network. Oscillatory rheology shows that the addition of silica to fat-in-oil gels does not significantly affect the magnitude of the storage modulus within the linear viscoelastic region. Interestingly, the range of this region is increased...
January 6, 2017: Food & Function
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