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Rheology

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https://www.readbyqxmd.com/read/28433884/synthetic-control-of-the-size-shape-and-polydispersity-of-anisotropic-silica-colloids
#1
Ryan P Murphy, Kunlun Hong, Norman J Wagner
The microstructure and rheological properties of colloidal suspensions depend on particle size and shape. This work aims to further control the size, shape, and polydispersity of anisotropic silica colloids, to reduce particle size, and to provide additional mechanistic insights on a prevalent, water-in-oil emulsion synthesis method. Key findings show that the dimensions of anisotropic silica particles can be systematically varied by approximately fivefold, with a limiting minimum particle size (D≈60nm, L≈300nm) obtained from emulsions with excess polyvinylpyrrolidone (PVP) and sodium citrate...
April 11, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28433176/novel-hydroxyethyl-chitosan-cellulose-scaffolds-with-bubble-like-porous-structure-for-bone-tissue-engineering
#2
Yaping Wang, Junmin Qian, Na Zhao, Ting Liu, Weijun Xu, Aili Suo
Hydrogels fabricated from natural polysaccharides may serve as ideal scaffolds for tissue engineering because of their similarity to the extracellular matrices. In this study, novel hydrogel scaffolds with bubble-like porous structure were prepared from hydroxyethyl chitosan (HECS) and cellulose (CEL) by a combination of chemical crosslinking, particle-leaching using silicon dioxide particles as porogen and freeze-drying method. The morphology, compression stress-strain curves, wettability, and swelling and rheological behaviors of the HECS/CEL scaffolds were characterized by SEM, mechanical test, contact angle measurement and rheometer...
July 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28433161/does-kappa-carrageenan-thermoreversible-gelation-affect-%C3%AE-carotene-oxidative-degradation-and-bioaccessibility-in-o-w-emulsions
#3
Christos Soukoulis, Maria Tsevdou, Lina Yonekura, Sébastien Cambier, Petros S Taoukis, Lucien Hoffmann
In the present work oil-in-gel (o/g) emulsions comprising 0.4-1% w/w κ-carrageenan in the absence and presence of Ca(2+) (20mM) were investigated for their ability to hamper the oxidative degradation under isothermal (5, 20 and 37°C) ambient air storage conditions and promote the in vitro bioaccessibility of β-carotene. The mechanical and structure conformational aspects of the o/g emulsions throughout in vitro digestion were measured by means of oscillatory rheology and optical microscopy. Although the addition of κ-carrageenan reduced by more than 50% (from 0...
July 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28433152/biodegradable-blends-of-urea-plasticized-thermoplastic-starch-utps-and-poly-%C3%AE%C2%B5-caprolactone-pcl-morphological-rheological-thermal-and-mechanical-properties
#4
Ana Carolina Correa, Vitor Brait Carmona, José Alexandre Simão, Luiz Henrique Capparelli Mattoso, José Manoel Marconcini
Biodegradable blends of urea plasticized thermoplastic starch (UTPS) and poly(ε-caprolactone) (PCL) were prepared in a co-rotating twin screw extruder. The UTPS and PCL content varied in a range of 25wt%. The materials were characterized by capillary rheometry, scanning electron microscopy (SEM), termogravimetry (TGA), differential scanning calorimetry (DSC) and tensile tests. Capillary rheometry showed better interaction between UTPS and PCL at 110°C than at 130°C. SEM showed immiscibility of all blends and good dispersion of UTPS in PCL matrix up to 50wt%...
July 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28433149/fabrication-and-evaluation-of-thermosensitive-chitosan-collagen-%C3%AE-%C3%AE-glycerophosphate-hydrogels-for-tissue-regeneration
#5
Qifeng Dang, Kai Liu, Zhenzhen Zhang, Chengsheng Liu, Xi Liu, Ying Xin, Xiaoyu Cheng, Tao Xu, Dongsu Cha, Bing Fan
Thermosensitive hydrogels whose physiological properties are similar to extracellular matrix have been extensively used for tissue regeneration. Polysaccharides and proteins, as biocompatible substrates similar to bio-macromolecules that could be recognized by human body, are two preferred polymers for fabrication of such hydrogels. A series of novel thermosensitive hydrogels (CS-ASC-HGs) containing chitosan (CS) and acid-soluble collagen (ASC) were thus prepared, in the presence of α, β-glycerophosphate, to mimic extracellular microenvironment for tissue regeneration...
July 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28430517/small-particle-driven-chain-disentanglements-in-polymer-nanocomposites
#6
Erkan Senses, Siyam M Ansar, Christopher L Kitchens, Yimin Mao, Suresh Narayanan, Bharath Natarajan, Antonio Faraone
Using neutron spin-echo spectroscopy, x-ray photon correlation spectroscopy, and bulk rheology, we studied the effect of particle size on the single-chain dynamics, particle mobility, and bulk viscosity in athermal polyethylene oxide-gold nanoparticle composites. The results reveal a ≈25% increase in the reptation tube diameter with the addition of nanoparticles smaller than the entanglement mesh size (≈5  nm), at a volume fraction of 20%. The tube diameter remains unchanged in the composite with larger (20 nm) nanoparticles at the same loading...
April 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28430456/the-microstructure-of-%C3%AE-sitosterol-%C3%AE-oryzanol-edible-organogels
#7
Andrew Barclay Matheson, Vasileios Koutsos, Georgios A Dalkas, Stephen Robert Euston, Paul S Clegg
Rheology and atomic force microscopy (AFM) were employed to examine the microstructure of β-sitosterol : γ-oryzanol organogels in sunflower oil. Using time resolved rheology we followed gel formation, paying specific attention to the fibril aggregation process, which had not been studied in detail previously for this system. Using AFM we observed gel structures directly, and obtained detailed information of the gel structure, far exceeding previous studies. Our analysis suggests that though gels are formed by the self-assembly and aggregation of one-dimensional fibrils, the manner in which these fibrils aggregate into ribbons results in complex structures of higher dimensionality...
April 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28430448/structural-and-rheological-properties-of-temperature-responsive-amphiphilic-triblock-copolymers-in-aqueous-media
#8
Josefine Eilsø Nielsen, Kaizheng Zhu, Sverre Arne Sande, Lubomír Kováčik, Dušan Cmarko, Kenneth Dahl Knudsen, Bo Nyström
Thermoresponsive amphiphilic biodegradable block copolymers of the type poly(-caprolactone-co-lactide)-poly(ethylene glycol)-poly(-caprolactone-co-lactide) (PCLA-PEGm-PCLA) have great potential for various biomedical applications. In the present study, we have surveyed the effects of PEG-spacer length (m=1000 and 1500), temperature, and polymer concentration on the self-assembling process to form supramolecular structures in aqueous solutions of the PCLA-PEGm-PCLA copolymer. This copolymer has a lower critical solution temperature, and the cloud point depends on both concentration and PEG-length...
April 21, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28430345/healing-response-of-rat-pulp-treated-with-an-injectable-keratin-hydrogel
#9
Lavanya Ajay Sharma, Robert M Love, Mohammad A Ali, Ajay Sharma, Soraia Macari, Avadhoot Avadhani, George J Dias
BACKGROUND: Keratin has shown promising outcomes as a biomaterial due to its inherent bioactivity, biocompatibility and regenerative effects. The effect of keratin on repair and regeneration of dental tissues has never been studied before. Current therapies to treat pulp tissues involve its replacement with inert, synthetic materials that do not have a proper biological function, leading to failure and tooth loss. This study aimed to develop a biocompatible keratin hydrogel (KH) suitable for pulp therapies...
April 20, 2017: Journal of Applied Biomaterials & Functional Materials
https://www.readbyqxmd.com/read/28430010/prolonged-injectable-formulation-of-nafarelin-using-in-situ-gel-combination-delivery-system
#10
Behnoush Alizadeh, Nika Bahari Javan, Hamid Akbari Javar, Mohammad Reza Khoshayand, Farid Abedin Dorkoosh
The principal purpose of the present study was to prepare and characterize a complex drug delivery system consisting of Nafarelin- poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles (NPs) in combination with sodium alginate/poloxamer 407 in situ gel. Nafarelin loaded PHBV NPs were prepared via double emulsion solvent evaporation technique. Box-Behnken Response Surface Methodology was utilized to optimize NPs. Mean particle size, polydispersity index (PDI), entrapment efficiency (EE) and drug loading (DL) of the optimized NPs were measured...
April 21, 2017: Pharmaceutical Development and Technology
https://www.readbyqxmd.com/read/28429928/a-dual-enzyme-hydrogen-peroxide-generation-machinery-in-hydrogels-supports-antimicrobial-wound-treatment
#11
Daniela Huber, Gregor Tegl, Anna Mensah, Bianca Beer, Martina Baumann, Nicole Borth, Christoph Sygmund, Roland Ludwig, Georg M Guebitz
The aging population and accompanying diseases like diabetes resulted in an increased occurrence of chronic wounds. Topical wound treatment with antimicrobial agents to inhibit bacterial invasion and promote wound healing is often associated with difficulties. Here, we investigated the potential of succinyl chitosan (SC) - carboxymethyl cellulose (CMC) hydrogels which constantly release clinically relevant levels of hydrogen peroxide (H2O2). CMC hydrogel matrix was in-situ converted by limited hydrolysis by a cellulase into substrates accepted by cellobiose dehydrogenase (CDH) for continuous production of H2O2 (30 µM over 24 h)...
April 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28429810/cisplatin-directed-coordination-crosslinking-nanogels-with-thermo-ph-sensitive-triblock-polymers-improvement-on-chemotherapic-efficacy-via-sustained-release-and-drug-retention
#12
Hao Zhao, Jiabao Xu, Jiangshan Wan, Shinan Geng, Han Li, Xiaole Peng, Qianwen Fu, Ming He, Yanbing Zhao, Xiangliang Yang
To realize the sustained release and long-term intratumoural retention of water-soluble cisplatin, thermo/pH-sensitive cisplatin-directed coordination-crosslinking nanogels (Pt-PNA) were developed via the coordination bonds of Pt-carboxyl groups. As the coordination ratio (CR) of the Pt-carboxyl bonds increased from 5% to 35%, the sizes of the Pt-PNA nanogels decreased from 999 nm to 167 nm, and their zeta potentials increased from -35 mV to -13 mV. Only through a simple mixing of cisplatin and PNAs, the entrapment efficiencies (EEs) of the Pt-PNA nanogels reached near 100% (>90%), and the drug-loading amounts (DLs) of cisplatin could achieve up to 25...
April 21, 2017: Nanoscale
https://www.readbyqxmd.com/read/28429808/slow-creep-in-soft-granular-packings
#13
Ishan Srivastava, Timothy S Fisher
Transient creep mechanisms in soft granular packings are studied numerically using a constant pressure and constant stress simulation method. Rapid compression followed by slow dilation is predicted on the basis of a logarithmic creep phenomenon. Characteristic scales of creep strain and time exhibit a power-law dependence on jamming pressure, and they diverge at the jamming point. Microscopic analysis indicates the existence of a correlation between rheology and nonaffine fluctuations. Localized regions of large strain appear during creep and grow in magnitude and size at short times...
April 21, 2017: Soft Matter
https://www.readbyqxmd.com/read/28429474/the-influence-of-glu-1-and-glu-3-loci-on-dough-rheology-and-bread-making-properties-in-wheat-t-aestivum-l-doubled-haploid-lines
#14
Monika Langner, Karolina Krystkowiak, Bolesław P Salmanowicz, Tadeusz Adamski, Paweł Krajewski, Zygmunt Kaczmarek, Maria Surma
BACKGROUND: The major determinants of wheat quality are Glu-1 and Glu-3 glutenin loci and environmental factors. Additive effects of alleles at Glu-1 and Glu-3 loci, and their interactions were evaluated for dough rheology and baking properties in four groups of wheat doubled haploid lines differing in HMW-GS and LMW-GS composition. RESULTS: Flour quality, Reomixer, dough extension, Farinograph and baking parameters were determined. Groups of lines with the alleles Glu-A3b and Glu-B3d were characterized by higher values of dough and baking parameters than those with the Glu-A3e and Glu-B3a alleles...
April 21, 2017: Journal of the Science of Food and Agriculture
https://www.readbyqxmd.com/read/28419829/characterization-of-polyhydroxyalkanoates-produced-by-synechocystis-salina-from-digestate-supernatant
#15
Adriana Kovalcik, Katharina Meixner, Matthias Mihalic, Wolfgang Zeilinger, Ines Fritz, Werner Fuchs, Pavel Kucharczyk, Franz Stelzer, Bernhard Drosg
The current commercial production of polyhydroxyalkanoates (PHA) is based on heterotrophic bacteria, using organic carbon sources from crops. To avoid the competition with food and feed production, cyanobacteria, metabolising PHA from carbon dioxide can be used. This research focuses on the investigation of the thermal and rheological properties of PHA polymers accumulated by Synechocystis salina, which had been cultivated in digestate supernatant and a mineral medium. The dried bacterial cells had a polymer content of 5...
April 15, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28419504/sensory-and-rheological-characteristics-of-thickened-liquids-differing-concentrations-of-a-xanthan-gum-based-thickener
#16
Hyeri Kim, Han-Im Hwang, Ki-Won Song, Jeehyun Lee
The objectives of this study were to develop and compare sensory characteristics of beverages and soups thickened with different concentrations of a xanthan gum-based thickener, and to examine, using rheological measurement, whether the viscosity of the thickened liquids conformed to the recommendations of the National Dysphagia Diet Task Force. Beverages tested included water, plum juice, apple juice, orange juice, milk, soymilk, and Yakult. The thickening agent was added to samples at concentrations of 1%, 2%, or 3%...
April 17, 2017: Journal of Texture Studies
https://www.readbyqxmd.com/read/28419471/spectral-analysis-of-the-stick-slip-phenomenon-in-oral-tribological-texture-evaluation
#17
Solange Sanahuja, Rutuja Upadhyay, Heiko Briesen, Jianshe Chen
"Oral" tribology has become a new paradigm in food texture studies to understand complex texture attributes, such as creaminess, oiliness, and astringency, which could not be successfully characterized by traditional texture analysis nor by rheology. Stick-slip effects resulting from intermittent sliding motion during kinetic friction of oral mucosa could constitute an additional determining factor of sensory perception where traditional friction coefficient values and their Stribeck regimes fail in predicting different lubricant (food bolus and saliva) behaviors...
March 28, 2017: Journal of Texture Studies
https://www.readbyqxmd.com/read/28418657/oil-in-water-emulsions-stabilized-by-saponified-epoxidized-soybean-oil-grafted-hydroxyethyl-cellulose
#18
Xujuan Huang, Qiaoguang Li, He Liu, Shibin Shang, Minggui Shen, Jie Song
An oil-in-water emulsion stabilized by saponified epoxidized soybean oil-grafted hydroxyethyl cellulose (H-ESO-HEC) was investigated. By using an ultrasonic method, oil-in-water emulsions were prepared by blending 50 wt% soybean oil and 50 wt% H-ESO-HEC aqueous suspensions. The influence of H-ESO-HEC concentrations on the properties of oil-in-water emulsions was examined. The H-ESO-HEC concentrations in the aqueous phase varied from 0.02 to 0.40 wt%. When the H-ESO-HEC concentration was 0.4 wt%, the emulsion remained stable for more than 80 days...
April 18, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28416876/comparison-of-rheological-behaviors-and-nanostructure-of-bighead-carp-scales-gelatin-modified-by-different-modification-methods
#19
Tao Huang, Zong-Cai Tu, Hui Wang, Wei Liu, Lu Zhang, Yan Zhang, Xin-Chen ShangGuan
In this study, microbial transglutaminase (MTGase) and pectin were compared to modify bighead carp (Hypophthalmichthys nobilis) scale gelatin. The functional properties of modified fish scales gelatin (FSG) were largely improved, including melting temperature and rheological behavior. While, modification methods decreased the triple-helix content and destroyed the single left-hand helix chain of modified FSG as investigated by X-ray diffraction. MTGase could induce the denser and finer gels network, but had none significant effect on nanostructural properties of fish gelatin...
April 2017: Journal of Food Science and Technology
https://www.readbyqxmd.com/read/28416866/rheology-and-microstructure-of-kefiran-and-whey-protein-mixed-gels
#20
Hosayn Kazazi, Faramarz Khodaiyan, Karamatollah Rezaei, Malihe Pishvaei, Mohammad Amin Mohammadifar, Sohrab Moieni
The effect of kefiran on cold-set gelation of whey protein isolate (WPI) at 25 °C was studied using rheological measurements and environmental scanning electron microscopy (ESEM). The gelation of samples was induced by the addition of glucono-δ-lactone to the dispersions. WPI concentration was maintained at 8% (w/v) and the concentration of kefiran varied from 0 to 0.08% (w/v). According to rheological measurements, the addition of kefiran into WPI dispersions resulted in a significant increase in the gel strength, the yield stress, and the shear stress values at the flowing point...
April 2017: Journal of Food Science and Technology
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