- Phase separation dynamics of gluten protein mixtures. [Journal Article]
- SMSoft Matter 2019 Jul 18
- We investigate by time-resolved synchrotron ultra-small X-ray scattering the dynamics of liquid-liquid phase-separation (LLPS) of gluten protein suspensions following a temperature quench. Samples at…
We investigate by time-resolved synchrotron ultra-small X-ray scattering the dynamics of liquid-liquid phase-separation (LLPS) of gluten protein suspensions following a temperature quench. Samples at a fixed concentration (237 mg ml-1) but with different protein compositions are investigated. In our experimental conditions, we show that fluid viscoelastic samples depleted in polymeric glutenin phase-separate following a spinodal decomposition process. We quantitatively probe the late stage coarsening that results from a competition between thermodynamics that speeds up the coarsening rate as the quench depth increases and transport that slows down the rate. For even deeper quenches, the even higher viscoelasticity of the continuous phase leads to a "quasi" arrested phase separation. Anomalous phase-separation dynamics is by contrast measured for a gel sample rich in glutenin, due to elastic constraints. This work illustrates the role of viscoelasticity in the dynamics of LLPS in protein dispersions.
- Sheathless separation of microalgae from bacteria using a simple straight channel based on viscoelastic microfluidics. [Journal Article]
- LCLab Chip 2019 Jul 17
- Microalgae cells have been recognized as a promising sustainable resource to meet worldwide growing demands for renewable energy, food, livestock feed, water, cosmetics, pharmaceuticals, and material…
Microalgae cells have been recognized as a promising sustainable resource to meet worldwide growing demands for renewable energy, food, livestock feed, water, cosmetics, pharmaceuticals, and materials. In order to ensure high-efficiency and high-quality production of biomass, biofuel, or bio-based products, purification procedures prior to the storage and cultivation of the microalgae from contaminated bacteria are of great importance. The present work proposed and developed a simple, sheathless, and efficient method to separate microalgae Chlorella from bacteria Bacillus Subtilis in a straight channel using the viscoelasticity of the medium. Microalgae and bacteria migrate to different lateral positions closer to the channel centre and channel walls respectively. Fluorescent microparticles with 1 μm and 5 μm diameters were first used to mimic the behaviours of bacteria and microalgae to optimize the separating conditions. Subsequently, size-based separation in Newtonian fluid and in viscoelastic fluid in straight channels with different aspect ratios was compared and demonstrated. Under the optimal condition, the removal ratio for 1 μm microparticles and separation efficiency for 5 μm particles can reach up to 98.28% and 93.85% respectively. For bacteria and microalgae cells separation, the removal ratio for bacteria and separation efficiency for microalgae cells is 92.69% and 100% respectively. This work demonstrated the continuous and sheathless separation of microalgae from bacteria for the first time by viscoelastic microfluidics. This technique can also be applied as an efficient and user-friendly method to separate mammalian cells or other kinds of cells.
- Strong and thermally insulating polylactic acid/glass fiber composite foam fabricated by supercritical carbon dioxide foaming. [Journal Article]
- IJInt J Biol Macromol 2019 Jul 12
- Environmental friendly and non-toxic polylactic acid (PLA) foam exhibits a promising perspective in many areas. However, PLA shows very poor foaming ability. Herein, silane-modified glass fiber (GF) …
Environmental friendly and non-toxic polylactic acid (PLA) foam exhibits a promising perspective in many areas. However, PLA shows very poor foaming ability. Herein, silane-modified glass fiber (GF) was compounded with PLA to improve its foaming ability. Thanks to the increased melt viscoelasticity and melt strength, and the enhanced crystallization by adding GF, PLA/GF composites show dramatically improved foaming ability, characterized by widened processing window, increased expansion ratio, and improved cellular uniformity. Compared with pure PLA foam, PLA/GF composite foam shows dramatically enhanced mechanical properties in compressive strength and modulus. For foams with the same expansion ratio of 20-fold, the incorporation of 10 wt% GF led to increased compressive strength and modulus by 44.8% and 92.0%, respectively. The PLA/GF composite foam with an expansion ratio of 24.2-fold has a low thermal conductivity of 31.4 mW/m·K, which is comparable with the excellent thermal insulation performance of commercial polymer foams.
- Viscoelastic properties of the central region of porcine temporomandibular joint disc in shear stress-relaxation. [Journal Article]
- JBJ Biomech 2019 Jul 02
- In this study, shear relaxation properties of the porcine temporomandibular joint (TMJ) disc are investigated. Previous studies have shown that, in fatigue failure and damage of cartilage and fibroca…
In this study, shear relaxation properties of the porcine temporomandibular joint (TMJ) disc are investigated. Previous studies have shown that, in fatigue failure and damage of cartilage and fibrocartilage, shear loads could be one of the biggest contributors to the failure. The aim of the present study is to develop an evaluation method to study shear properties of the disc and to do a mathematical characterization of it. For the experiments, twelve porcine discs were used. Each disc was dissected from the TMJ and, then, static strain control tests were carried out to obtain the shear relaxation modulus for the central region of the discs. From the results, it was found that the disc presents a viscoelastic behavior under shear loads. Relaxation modulus decreased with time. Shear relaxation was 10% of the instantaneous stress, which implies that the viscous properties of the disc cannot be neglected. The present results lead to a better understanding of the discs mechanical behavior under realistic TMJ working conditions.
- Understanding rates of genital-anal injury: Role of skin color and skin biomechanics. [Journal Article]
- JFJ Forensic Leg Med 2019 Jul 02; 66:120-128
- CONCLUSIONS: Our findings provide qualified support for the importance of skin color during the forensic examination. Women with lighter skin tones may have skin that is more easily injured than women with darker tones. In contrast, external genital injuries may be more easily identified in women with light as compared to dark skin, a situation that is important in both the health care and criminal justice systems. Additionally, women with decreased viscoelasticity and increased hydration may be more easily injured. These findings support the need to develop forensic procedures that are effective in people across the range of skin colors and to interpret forensic findings considering the innate properties of the skin.
- Transient measurement and structure analysis of protein-polysaccharide multilayers at fluid interfaces. [Journal Article]
- SMSoft Matter 2019 Jul 12
- The formation of electrostatic protein-polysaccharide multilayers has attracted attention for the design of fluid interfaces with enhanced stability and functionality. However, current techniques are…
The formation of electrostatic protein-polysaccharide multilayers has attracted attention for the design of fluid interfaces with enhanced stability and functionality. However, current techniques are often limited to measuring final multilayer properties. We present an interfacial shear rheology setup with simultaneous subphase exchange, allowing the transient measurement of biopolymer multilayers by their viscoelasticity. The successive and simultaneous adsorption of β-lactoglobulin (β-lg) and low-methoxyl pectin were investigated at the n-dodecane/water interface at pH 4. The successive injection of pectin increased the viscoelasticity of an adsorbed β-lg layer by electrostatic complexation. On the other hand, simultaneous adsorption impeded adsorption kinetics and interfacial layer strength due to complexation in the bulk phase prior to adsorption. Neutron reflectometry at the air-water interface confirmed the formation of an initial β-lg layer and electrostatic complexation of a secondary pectin layer, which desorbed upon pH-induced charge inversion. The layer formed by simultaneous adsorption mainly consisted of β-lg. We conclude that protein-polysaccharide complexes show limited surface activity and result in a lower effective protein concentration available for adsorption.
- Strain Rate Dependent Viscoelasticity and Fracture Mechanics of Cellulose Nanofibrils Composite Hydrogels. [Journal Article]
- LLangmuir 2019 Jul 12
- In this work, the composite hydrogels toughening behaviors as manifested by strain rate dependent viscoelastic properties and enhanced fracture mechanics, i.e. suppressed catastrophic crack propagati…
In this work, the composite hydrogels toughening behaviors as manifested by strain rate dependent viscoelastic properties and enhanced fracture mechanics, i.e. suppressed catastrophic crack propagation with increased resistance, are systematically examined by using cellulose nanofibrils (CNFs) as fillers in polyacrylamide (PAAm) matrix. The uniaxial mechanical tests show that the tearing energy increases with crack velocity and becomes dominated by the viscoelastic energy dissipation in front of the crack tip. The creep dynamics of the composite hydrogels under a constant stress is examined and the results indicate that the incorporation of CNF pronouncedly suppresses the creep deformation. In addition, the microdeformation and failure mechanisms are analyzed through the observation of morphology of arrested crack tips and the damage zone by TEM and SEM. By aligning the CNF along the crack direction, it is possible to focus on the study of interfacial slip mechanics and identify the role of interfacial slip during energy dissipation process. The results indicate that the CNFs are largely orientated parallel to the loading direction to maximize the energy dissipation, where the initiation of crack propagation is the primary fracture mechanism in composite hydrogels. The coarse feature on the composite fracture surface implies that the CNF initiates deflection of crack propagation fronts and thus increases the strain energy for continuation of fracture. It is envisioned that with incorporation of interdisciplinary strategies, one can rationally combine multiple approaches toward the creation of nanocomposite hydrogels with enhanced mechanical properties.
- Sheathless High-Throughput Circulating Tumor Cell Separation Using Viscoelastic non-Newtonian Fluid. [Journal Article]
- MMicromachines (Basel) 2019 Jul 10; 10(7)
- Circulating tumor cells (CTCs) have attracted increasing attention as important biomarkers for clinical and biological applications. Several microfluidic approaches have been demonstrated to separate…
Circulating tumor cells (CTCs) have attracted increasing attention as important biomarkers for clinical and biological applications. Several microfluidic approaches have been demonstrated to separate CTCs using immunoaffinity or size difference from other blood cells. This study demonstrates a sheathless, high-throughput separation of CTCs from white blood cells (WBCs) using a viscoelastic fluid. To determine the fluid viscoelasticity and the flow rate for CTC separation, and to validate the device performance, flow characteristics of 6, 13, and 27 μm particles in viscoelastic fluids with various concentrations were estimated at different flow rates. Using 0.2% hyaluronic acid (HA) solution, MCF-7 (Michigan Cancer Foundation-7) cells mimicking CTCs in this study were successfully separated from WBCs at 500 μL/min with a separation efficiency of 94.8%. Small amounts of MCF-7 cells (~5.2%) were found at the center outlet due to the size overlap with WBCs.
- Fully automated thromboelastograph TEG 6s to measure anticoagulant effects of direct oral anticoagulants in healthy male volunteers. [Journal Article]
- RPRes Pract Thromb Haemost 2019; 3(3):391-396
- CONCLUSIONS: We have demonstrated that TEG _6s R has significant correlation with DOAC blood concentrations and has potential for monitoring the DOAC's effect on hemostasis with reasonable sensitivity in the small sample analyzed. This novel technology is easy to use on a small volume of whole blood without requiring a specialized laboratory. Further study is warranted to correlate R with clinical outcomes.
New Search Next
- Hyaluronic Acid: Molecular Mechanisms and Therapeutic Trajectory. [Review]
- FVFront Vet Sci 2019; 6:192
- Hyaluronic acid (also known as hyaluronan or hyaluronate) is naturally found in many tissues and fluids, but more abundantly in articular cartilage and synovial fluid (SF). Hyaluronic acid (HA) conte…
Hyaluronic acid (also known as hyaluronan or hyaluronate) is naturally found in many tissues and fluids, but more abundantly in articular cartilage and synovial fluid (SF). Hyaluronic acid (HA) content varies widely in different joints and species. HA is a non-sulfated, naturally occurring non-protein glycosaminoglycan (GAG), with distinct physico-chemical properties, produced by synoviocytes, fibroblasts, and chondrocytes. HA has an important role in the biomechanics of normal SF, where it is partially responsible for lubrication and viscoelasticity of the SF. The concentration of HA and its molecular weight (MW) decline as osteoarthritis (OA) progresses with aging. For that reason, HA has been used for more than four decades in the treatment of OA in dogs, horses and humans. HA produces anti-arthritic effects via multiple mechanisms involving receptors, enzymes and other metabolic pathways. HA is also used in the treatment of ophthalmic, dermal, burns, wound repair, and other health conditions. The MW of HA appears to play a critical role in the formulation of the products used in the treatment of diseases. This review provides a mechanism-based rationale for the use of HA in some disease conditions with special reference to OA.