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https://www.readbyqxmd.com/read/28822539/polymers-and-surfactants-at-fluid-interfaces-studied-with-specular-neutron-reflectometry
#1
REVIEW
Larissa Braun, Martin Uhlig, Regine von Klitzing, Richard A Campbell
This review addresses the advances made with specular neutron reflectometry in studies of aqueous mixtures of polymers and surfactants at fluid interfaces during the last decade (or so). The increase in neutron flux due to improvements in instrumentation has led to routine measurements at the air/water interface that are faster and involve samples with lower isotopic contrast than in previous experiments. One can now resolve the surface excess of a single deuterated component on the second time scale and the composition of a mixture on the minute time scale, and information about adsorption processes and dynamic rheology can also be accessed...
July 12, 2017: Advances in Colloid and Interface Science
https://www.readbyqxmd.com/read/28822289/assessing-differences-between-ostwald-ripening-and-coalescence-by-rheology-laser-diffraction-and-multiple-light-scattering
#2
J Santos, N Calero, L A Trujillo-Cayado, M C Garcia, J Muñoz
This contribution deals with the study of the influence of surfactant ratio, namely triblock copolymer (Pluronic PE9400) to polyoxyethylene glycerol fatty acid ester (Levenol C201), on the stability of emulsions formulated with a mixture of two biosolvents (N,N Dimethyl Decanamide and D-limonene), which find applications as carriers of agrochemicals. Emulsions containing Pluronic, regardless of the concentration studied, underwent Ostwald ripening while coalescence controlled the destabilization process of emulsions containing Levenol C201 as the only emulsifier...
August 14, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28822121/investigating-the-origin-of-acoustic-attenuation-in-liquid-foams
#3
Juliette Pierre, Camille Gaulon, Caroline Derec, Florence Elias, Valentin Leroy
Liquid foams are known to be highly efficient to absorb acoustic waves but the origin of the sound dissipation remains unknown. In this paper, we present low frequency (0.5-4kHz) experimental results measured with an impedance tube and we confront the recorded attenuations with a simple model that considers the foam as a concentrate bubbly liquid. In order to identify the influence of the different parameters constituting the foams we probe samples with different gases, and various liquid fractions and bubble size distributions...
August 2017: European Physical Journal. E, Soft Matter
https://www.readbyqxmd.com/read/28821801/experimental-study-of-rheological-properties-and-oil-displacement-efficiency-in-oilfields-for-a-synthetic-hydrophobically-modified-polymer
#4
Pengcheng Liu, Zhenbao Mu, Chao Wang, Yanling Wang
In a previous study, we developed a synthetic hydrophobically modified hydroxyethyl cellulose (HEC) using bromododecane (BD), which we denote as BD-HMHEC. In this work, we continually investigate the rheological properties and its oil displacement efficiency in PuTao well area in Daqing oilfields, China. Results show that BD-HMHEC solution has good viscosification, thermal-resistance, salt-tolerance, shear resistance, and acid/alkali resistance. The storage modulus (G') and the loose modulus (G") of the BD-HMHEC solutions increase significantly with increasing BD-HMHEC concentration, and the solution becomes viscoelastic at a sufficiently high BD-HMHEC concentration...
August 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28821349/advances-and-challenges-in-the-rheology-of-concentrated-emulsions-and-nanoemulsions
#5
REVIEW
Ha Seong Kim, Thomas G Mason
We review advances that have been made in the rheology of concentrated emulsions and nanoemulsions, which can serve as model soft materials that have highly tunable viscoelastic properties at droplet volume fractions near and above the glass transition and jamming point. As revealed by experiments, simulations, and theoretical models, interfacial and positional structures of droplets can depend on the applied flow history and osmotic pressure that an emulsion has experienced, thereby influencing its key rheological properties such as viscoelastic moduli, yield stress and strain, and flow behavior...
July 5, 2017: Advances in Colloid and Interface Science
https://www.readbyqxmd.com/read/28821154/design-and-characterization-of-a-biocompatible-physical-hydrogel-based-on-scleroglucan-for-topical-drug-delivery
#6
Patrizia Paolicelli, Gabriele Varani, Settimio Pacelli, Elisa Ogliani, Martina Nardoni, Stefania Petralito, Alessandra Adrover, Maria Antonietta Casadei
Physical hydrogels of a high-carboxymethylated derivative of scleroglucan (Scl-CM300) were investigated as potential systems for topical drug delivery using three different therapeutic molecules (fluconazole, diclofenac and betamethasone). Rheological tests were carried out on drug-loaded hydrogels along with in-vitro release studies in a vertical Franz cell, in order to investigate if and how different drugs may influence the rheological and release properties of Scl-CM300 hydrogels. Experimental results and theoretical modeling highlighted that, in the absence of drug/polymer interactions (as for fluconazole and betamethasone) Scl-CM300 matrices offer negligible resistance to drug diffusion and a Fickian transport model can be adopted to estimate the effective diffusion coefficient in the swollen hydrogel...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821146/evaluation-of-carboxymethyl-moringa-gum-as-nanometric-carrier
#7
Rimpy, Abhishek, Munish Ahuja
In the present study, carboxymethylation of Moringa oleifera gum was carried out by reacting with monochloroacetic acid. Modified gum was characterised employing Fourier-transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and Rheology study. The carboxymethyl modification of moringa gum was found to increase its degree of crystallinity, reduce viscosity and swelling, increase the surface roughness and render its more anionic. The interaction between carboxymethyl moringa gum and chitosan was optimised by 2-factor, 3-level central composite experimental design to prepare polyelectrolyte nanoparticle using ofloxacin, as a model drug...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821145/utilization-of-cotton-waste-for-regenerated-cellulose-fibres-influence-of-degree-of-polymerization-on-mechanical-properties
#8
Rasike De Silva, Nolene Byrne
Cotton accounts for 30% of total fibre production worldwide with over 50% of cotton being used for apparel. In the process from cotton bud to finished textile product many steps are required, and significant cotton waste is generated. Typically only 30% of pre consumer cotton is recycled. Here we use cotton waste lint to produce regenerated cellulose fibres (RCF). We find the RCF from waste cotton lint had increased mechanical properties compared to RCF produced from wood pulp. We show that this is likely linked to the higher degree of polymerization (DP) of waste cotton lint...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821142/manufacture-of-requeij%C3%A3-o-cremoso-processed-cheese-with-galactooligosaccharide
#9
P C Belsito, M V S Ferreira, L P Cappato, R N Cavalcanti, V A S Vidal, T C Pimentel, E A Esmerino, C F Balthazar, R P C Neto, M I B Tavares, P B Zacarchenco, M Q Freitas, M C Silva, R S L Raices, G M Pastore, M A R Pollonio, A G Cruz
The addition of galactooligosaccharide, (GOS, 0, 1.5, 3 or 4g/100g) on the quality parameters of requeijão cremoso was investigated. Chemical characteristics (pH, moisture, fat and protein), color (L*, a*, b*), water mobility by TD- nuclear magnetic resonance, rheology (flow curve and oscillatory tests), microstructure and sensory acceptance (consumer test) were evaluated. The addition of GOS provided a denser and compact structure and reduced number and size of fat globules. Increased GOS level (3 and 4g/100g) improved the softness and spreadability (decrease of G', G″ and apparent viscosity and an increase of tan δ and melting index) and impacted positively on the aroma and taste of the requeijão cremoso...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821115/rheology-and-bioactivity-of-high-molecular-weight-dextrans-synthesised-by-lactic-acid-bacteria
#10
Kenza Zarour, Mª Goretti Llamas, Alicia Prieto, Patricia Rúas-Madiedo, María Teresa Dueñas, Pilar Fernández de Palencia, Rosa Aznar, Mebrouk Kihal, Paloma López
Dextrans synthesised by three Leuconostoc mesenteroides strains, isolated from mammalian milks, were studied and compared with dextrans produced by Lc. mesenteroides and Lactobacillus sakei strains isolated from meat products. Size exclusion chromatography coupled with multiangle laser light scattering detection analysis demonstrated that the dextrans have molecular masses between 1.74×10(8)Da and 4.41×10(8)Da. Rheological analysis of aqueous solutions of the polymer revealed that all had a pseudoplastic behaviour under shear conditions and a random, and flexible, coil structure...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821099/xyloglucan-gelation-induced-by-enzymatic-degalactosylation-kinetics-and-the-effect-of-the-molar-mass
#11
Caroline Novak Sakakibara, Maria Rita Sierakowski, Christophe Chassenieux, Taco Nicolai, Rilton Alves de Freitas
Gelation kinetics of aqueous solutions of xyloglucan (XG) extracted from H. courbaril seeds were investigated, in-situ, during enzymatic removal of galactose units by oscillatory shear rheological measurements, at different XG and enzyme (β-galactosidase) concentrations. Increasing the enzyme concentration (Cenz) led to an increase of the gelation rate. Master curves of the evolution of the storage shear modulus at different Cenz could be formed by time-Cenz superposition showing that Cenz influenced the kinetics, but not the gelation process and the final gel stiffness...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821071/on-the-use-of-ion-crosslinked-nanocellulose-hydrogels-for-wound-healing-solutions-physicochemical-properties-and-application-oriented-biocompatibility-studies
#12
Alex Basu, Jonas Lindh, Eva Ålander, Maria Strømme, Natalia Ferraz
Calcium ion-crosslinked nanofibrillated cellulose (NFC) hydrogels were investigated as potential materials for wound healing dressings. The physicochemical properties of the hydrogels were examined by rheology and water retention tests. Skin cells and monocytes were selected for application-oriented biocompatibility studies. The NFC hydrogels presented entangled fibrous networks and solid-like behavior. Water retention tests showed the material´s potential to maintain a suitable moist environment for different type of wounds...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821056/fabrication-of-salecan-poly-amps-co-hmaa-semi-ipn-hydrogels-for-cell-adhesion
#13
Xinyu Hu, Yongmei Wang, Liangliang Zhang, Man Xu, Wei Dong, Jianfa Zhang
Salecan is a novel water-soluble extracellular β-glucan and has excellent physicochemical and biological properties. A series of hydrogels were fabricated from Salecan and poly(2-acrylamido-2-methylpropanesulfonic acid-co-N-hydroxymethyl acrylamide) (poly(AMPS-co-HMAA), PAH) by semi-IPN technique. The introduction of Salecan into the PAH network endows the system with enhanced cell adhesion properties. These semi-IPN hydrogels with open interconnected pores had pH and salt-sensitive swelling behavior. The increase in the content of hydrophilic Salecan could enhance the water uptake of the hydrogels...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821041/regulation-of-structure-rheological-and-surface-properties-of-chitin-nanocrystal-dispersions
#14
M A Torlopov, I S Martakov, V I Mikhaylov, N V Tsvetkov, P V Krivoshapkin
The hydrosols of chitin nanocrystals (ChN) are promising as modifiers of properties, drug delivery systems, and media. The purpose of this work is to clarify the mechanisms for regulating processes of stability and structure formation occurring in the ChN hydrosols under the influence of varying ionic strength. ChN were isolated from the crab shell; ChN hydrosols are obtained with different concentrations of the dispersed phase. The structure and morphology of the particles was studied by atomic force microscopy and X-ray diffraction...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28820922/a-self-assembling-peptide-gel-as-a-vitreous-substitute-a-rabbit-study
#15
Koji Uesugi, Hirokazu Sakaguchi, Yasutaka Hayashida, Ryuhei Hayashi, Koichi Baba, Yuya Suganuma, Hidenori Yokoi, Motokazu Tsujikawa, Kohji Nishida
Purpose: To evaluate a self-assembling peptide gel as a potential vitreous substitute. Methods: PanaceaGel SPG-178, a self-assembling peptide gel, was diluted with distilled water and a balanced salt solution to achieve a final peptide concentration of 0.1%. The gel's refractive index, visible light transmission rate, and rheologic properties were investigated. The gel's biocompatibility was evaluated by examining the cellular viability (live and dead staining) and proliferation rate (alamarBlue assay)...
August 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28820072/structural-design-and-physicochemical-foundations-of-hydrogels-for-biomedical-and-pharmaceutical-applications
#16
Qingyong Li, Wen Li, Jie Xu, Zhengxiang Ning, Jiaoyan Ren, Wenzhen Liao
Biomedical research, known as medical research, is conducive to support and promote the development of knowledge in the field of medicine. Hydrogels have been extensively used in many biomedical fields due to theirs highly absorbent and flexible properties. The smart hydrogels, especially, can respond to a broad range of external stimuli such as temperature, pH value, light, electric and magnetic fields. With excellent biocompatibility, tunable rheology, mechanical properties, porosity, and hydrated molecular structure, hydrogels are considered as promising candidate for simulating local tissue microenvironment...
August 17, 2017: Current Medicinal Chemistry
https://www.readbyqxmd.com/read/28819663/rheological-characterization-of-yield-stress-gels-formed-via-electrostatic-heteroaggregation-of-metal-oxide-nanoparticles
#17
Javen S Weston, Jeffrey H Harwell, Brian P Grady
Mixtures of fumed fractal metal oxide nanoparticles (np's) dispersed in water, at a solution pH where one species is positively charged and the other is negatively charged, form yield stress gels at volume fractions as low as 1.5%, due to electrostatic heteroaggregation into networks as confirmed by small-angle neutron scattering. These gels exhibit a measurable yield stress and an apparent viscosity that follows a power law relationship with shear rate. Rotational and oscillatory shear rheology is presented for binary mixtures of fumed silica, fumed alumina, and fumed titania in aqueous dispersions...
August 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28819659/solvent-hydrophobicity-induced-complex-coacervation-of-dsdna-and-in-situ-formed-zein-nanoparticles
#18
Pankaj Kumar Pandey, Priyanka Kaushik, Kamla Rawat, V K Aswal, H B Bohidar
Zein, a predominantly hydrophobic protein, was sustained as a stable dispersion in ethanol-water (80 : 20, % (v/v)) binary solvent at room temperature (25 °C). Addition of aqueous dsDNA solution (1% (w/v)) to the above dispersion prepared with the protein concentration of Czein = 0.01-0.5% (w/v) caused a concomitant change in ethanol content from 14-35% (v/v), which in turn generated zein nanoparticles in situ of size 80-120 nm increasing with water content. The subsequent associative interaction between DNA (polyanion; 2000 bps) and the positively charged zein nanoparticles, (at pH = 4) was driven by Coulombic forces, and by the solvent hydrophobicity due to the ethanol content of the binary solvent...
August 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28819658/weld-formation-during-material-extrusion-additive-manufacturing
#19
Jonathan E Seppala, Seung Hoon Han, Kaitlyn E Hillgartner, Chelsea S Davis, Kalman B Migler
Material extrusion (ME) is a layer-by-layer additive manufacturing process that is now used in personal and commercial production where prototyping and customization are required. However, parts produced from ME frequently exhibit poor mechanical performance relative to those from traditional means; moreover, fundamental knowledge of the factors leading to development of inter-layer strength in this highly non-isothermal process is limited. In this work, we seek to understand the development of inter-layer weld strength from the perspective of polymer interdiffusion under conditions of rapidly changing mobility...
August 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28819137/precise-stacking-of-decellularized-extracellular-matrix-based-3d-cell-laden-constructs-by-a-3d-cell-printing-system-equipped-with-heating-modules
#20
Geunseon Ahn, Kyung-Hyun Min, Changhwan Kim, Jeong-Seok Lee, Donggu Kang, Joo-Yun Won, Dong-Woo Cho, Jun-Young Kim, Songwan Jin, Won-Soo Yun, Jin-Hyung Shim
Three-dimensional (3D) cell printing systems allow the controlled and precise deposition of multiple cells in 3D constructs. Hydrogel materials have been used extensively as printable bioinks owing to their ability to safely encapsulate living cells. However, hydrogel-based bioinks have drawbacks for cell printing, e.g. inappropriate crosslinking and liquid-like rheological properties, which hinder precise 3D shaping. Therefore, in this study, we investigated the influence of various factors (e.g. bioink concentration, viscosity, and extent of crosslinking) on cell printing and established a new 3D cell printing system equipped with heating modules for the precise stacking of decellularized extracellular matrix (dECM)-based 3D cell-laden constructs...
August 17, 2017: Scientific Reports
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