scholarly journals Kappa-Carrageenan-Based Dual Crosslinkable Bioink for Extrusion Type Bioprinting

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2377
Author(s):  
Wonseop Lim ◽  
Gyeong Jin Kim ◽  
Hyun Woo Kim ◽  
Jiyeon Lee ◽  
Xiaowei Zhang ◽  
...  
Keyword(s):  
Shear Stress ◽  
Physical Properties ◽  
New Technology ◽  
High Viscosity ◽  
3D Bioprinting ◽  
Cell Compatibility ◽  
Low Viscosity ◽  
Shape Retention ◽  
Kappa Carrageenan ◽  
Nih 3T3

Bioink based 3D bioprinting is a promising new technology that enables fabrication of complex tissue structures with living cells. The printability of the bioink depends on the physical properties such as viscosity. However, the high viscosity bioink puts shear stress on the cells and low viscosity bioink cannot maintain complex tissue structure firmly after the printing. In this work, we applied dual crosslinkable bioink using Kappa-carrageenan (κ-CA) to overcome existing shortcomings. κ-CA has properties such as biocompatibility, biodegradability, shear-thinning and ionic gelation but the difficulty of controlling gelation properties makes it unsuitable for application in 3D bioprinting. This problem was solved by synthesizing methacrylated Kappa-carrageenan (MA-κ-CA), which can be dual crosslinked through ionic and UV (Ultraviolet) crosslinking to form hydrogel using NIH-3T3 cells. Through MA substitutions, the rheological properties of the gel could be controlled to reduce the shear stress. Moreover, bioprinting using the cell-laden MA-κ-CA showed cell compatibility with enhanced shape retention capability. The potential to control the physical properties through dual crosslinking of MA-κ-CA hydrogel is expected to be widely applied in 3D bioprinting applications.

scholarly journals Research and Development of a 3D Jet Printer for High-Viscosity Molten Liquids

Micromachines ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 554
Author(s):  
Yang Yang ◽  
Shoudong Gu ◽  
Jianfang Liu ◽  
Hongyu Tian ◽  
Qingqing Lv
Keyword(s):  
Liquid Velocity ◽  
New Technology ◽  
Droplet Diameter ◽  
Average Diameter ◽  
High Viscosity ◽  
Taper Angle ◽  
Voltage Difference ◽  
Low Viscosity ◽  
Cooling Mechanism ◽  
Molten Liquid

Micro-droplet jetting manufacture is a new 3D printing technology developed in recent years. Presently, this new technology mainly aims at ejecting a low-viscosity medium. Therefore, a device for ejecting high-viscosity molten liquid is designed by analyzing the injection principle of high-viscosity molten liquid. Initially, the cooling mechanism is designed to overcome the defect that the piezoelectric stacks cannot operate in high-temperature conditions. Thereafter, the mathematical model of the liquid velocity in the nozzle is derived, and the factors influencing injection are verified by Fluent. Subsequently, a prototype of the jet printer is fabricated, and the needle velocity is tested by the laser micrometer; the relationship between voltage difference and the needle velocity is also obtained. The experimental results matched the theoretical model well, showing that the voltage difference, needle radius, nozzle diameter, and taper angle are closely related to the injection performance of the 3D jet printer. By using a needle with a radius of 0.4 mm, a nozzle with a diameter of 50 μm, a taper angle of 90°, a supply pressure of 0.05 Mpa, and a voltage difference of 98 V, a molten liquid with a viscosity of 8000 cps can be ejected with a minimum average diameter of 275 μm, and the variation of the droplet diameter is within ±3.8%.

Plasma viscosity regulates capillary perfusion during extreme hemodilution in hamster skinfold model

1998 ◽  
Vol 275 (6) ◽  
pp. H2170-H2180 ◽  
Author(s):  
Amy G. Tsai ◽  
Barbara Friesenecker ◽  
Michael McCarthy ◽  
Hiromi Sakai ◽  
Marcos Intaglietta
Keyword(s):  
Molecular Weight ◽  
Shear Stress ◽  
Capillary Density ◽  
High Viscosity ◽  
Plasma Viscosity ◽  
Capillary Perfusion ◽  
Low Viscosity ◽  
Arterial Blood ◽  
Wall Shear ◽  
Stress Dependent

Effect of increasing blood viscosity during extreme hemodilution on capillary perfusion and tissue oxygenation was investigated in the awake hamster skinfold model. Two isovolemic hemodilution steps were performed with 6% Dextran 70 [molecular weight (MW) = 70,000] until systemic hematocrit (Hct) was reduced by 65%. A third step reduced Hct by 75% and was performed with the same solution [low viscosity (LV)] or a high-molecular-weight 6% Dextran 500 solution [MW = 500,000, high viscosity (HV)]. Final plasma viscosities were 1.4 and 2.2 cP (baseline of 1.2 cP). Hct was reduced to 11.2 ± 1.1% from 46.2 ± 1.5% for LV and to 11.9 ± 0.7% from 47.3 ± 2.1% for HV. HV produced a greater mean arterial blood pressure than LV. Functional capillary density (FCD) was substantially higher after HV (85 ± 12%) vs. LV (38 ± 30%) vs. baseline (100%).[Formula: see text] levels measured with Pd-porphyrin phosphorescence microscopy were not statistically changed from baseline until after the third hemodilution step. Wall shear rate (WSR) decreased in arterioles and venules after LV and only in arterioles after HV. Wall shear stress (WSR × plasma viscosity) was substantially higher after HV vs. LV. Increased mean arterial pressure and shear stress-dependent release of endothelium-derived relaxing factor are possible mechanisms that improved arteriolar and venular blood flow and FCD after HV vs. LV exchange protocols.

A Film Thickness Analysis for Line Contacts Under Pure Rolling Conditions With a Non-Newtonian Rheological Model

1981 ◽  
Vol 103 (2) ◽  
pp. 305-313 ◽  
Author(s):  
B. Gecim ◽  
W. O. Winer
Keyword(s):  
Shear Stress ◽  
Film Thickness ◽  
High Viscosity ◽  
Low Viscosity ◽  
Limiting Shear Stress ◽  
Lubrication Regime ◽  
Pure Rolling ◽  
Reasonable Range ◽  
Line Contacts ◽  
Rolling Elements

The non-Newtonian constitutive equation proposed by Winer and Bair [1] is applied in a conventional isothermal film thickness analysis of line contact lubrication of rolling elements. The present analysis provides four different dimensionless film thickness equations for four different regimes of lubrication. Due to the formulation technique used in deriving the governing pressure-gradient equation, the present study is recommended for high viscosity, high rolling speed, and low limiting shear stress cases where Newtonian models fail to match the experimental data. Comparison of the present film thickness equations with the Newtonian correspondences in each lubrication regime shows a considerable difference, but the analysis suffers from the fact that the limiting shear stress parameters of these high viscosity lubricants need to be determined experimentally. The present analysis assumes a reasonable range of limiting shear stress which is smaller than the corresponding values for low viscosity lubricants which are predominantly Newtonian in behavior (unless severe rolling and/or sliding with high loads is applied).

scholarly journals A dual crosslinking strategy to tailor rheological properties of gelatin methacryloyl

2017 ◽  
Vol 3 (2) ◽  
Author(s):  
Miaomiao Zhou ◽  
Bae Hoon Lee ◽  
Lay Poh Tan
Keyword(s):  
Tissue Engineering ◽  
Three Dimensional ◽  
Emerging Technology ◽  
Solution Viscosity ◽  
3D Bioprinting ◽  
Cell Compatibility ◽  
Low Viscosity ◽  
The Poor ◽  
Isopeptide Bonds ◽  
Mechanical Tunability

3D bioprinting is an emerging technology that enables fabrication of three-dimensional organised cellular constructs. One of the major challenges in 3D bioprinting is to develop a material to meet the harsh requirements (cell-compatibility, printability, structural stability post-printing and bio-functionality to regulate cell behaviours) suitable for printing. Gelatin methacryloyl (GelMA) has recently emerged as an attractive biomaterial in tissue engineering, because it satisfies the requirements of bio-functionality and mechanical tunability. However, the poor rheological property such as low viscosity at body temperature inhibits its application in 3D bioprinting. In this work, an enzymatic crosslinking method triggered by Ca2+-independent microbial transglutaminase (MTGase) was introduced to catalyse isopeptide bonds formation between chains of GelMA, which could improve its rheological behaviours, specifically viscosity. By combining enzymatic crosslinking and photo crosslinking, it is possible to tune the solution viscosity and quickly stabilize the gelatin macromolecules at the same time. The results showed that the enzymatic crosslinking can increase the solution viscosity. Subsequent photo crosslinking could aid in fast stabilization of the structure and make handling easy.

Physical properties of the oleoresin system of the four major southern pines

1977 ◽  
Vol 7 (3) ◽  
pp. 520-525 ◽  
Author(s):  
John D. Hodges ◽  
William W. Elam ◽  
William F. Watson
Keyword(s):  
Physical Properties ◽  
Function Analysis ◽  
Total Yield ◽  
Morphological Characteristics ◽  
High Viscosity ◽  
High Rate ◽  
High Yield ◽  
Breast Height ◽  
Low Viscosity ◽  
Very High

Oleoresin viscosity, flow (rate, duration, and total amount), and rate of crystallization were determined for Pinuselliottii Engelm., Pinuspalustris Mill., Pinustaeda L., and Pinusechinata Mill, in central Louisiana, U.S.A. Physical properties of the oleoresin and tree morphological characteristics (diameter at breast height, growth rate, height, crown ratio, and age) were not strongly related in either of the four species. Pinuselliottii oleoresin was extremenly viscous, crystallized very slowly, and flowed at a slow rate over a long period, and total yield was moderate. Pinuspalustris oleoresin was of moderately high viscosity and very high yield and had a high rate of flow. Pinustaeda and Pinusechinata oleoresin had, on the average, low viscosity, a moderate to low total yield, a short duration of flow, and rapid rate of crystallization. A discriminant function analysis revealed that 19% of the Pinustaeda and 6% of the Pinusechinata trees had oleoresin properties more similar to Pinuspalustris and Pinuselliottii than to the means for their own species. This information is being used to assess tree susceptibility to attack by Dendroctonusfrontalis Zimm.

Elevated plasma viscosity in extreme hemodilution increases perivascular nitric oxide concentration and microvascular perfusion

2005 ◽  
Vol 288 (4) ◽  
pp. H1730-H1739 ◽  
Author(s):  
Amy G. Tsai ◽  
Cesar Acero ◽  
Patricia R. Nance ◽  
Pedro Cabrales ◽  
John A. Frangos ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Shear Stress ◽  
Capillary Density ◽  
Blood Stream ◽  
High Viscosity ◽  
Plasma Viscosity ◽  
Low Viscosity ◽  
Enhanced Production ◽  
Dextran 70 ◽  
Nitric Oxide Concentration

We tested the hypothesis that high-viscosity (HV) plasma in extreme hemodilution causes wall shear stress to be greater than low-viscosity (LV) plasma, leading to enhanced production of nitric oxide (NO). The perivascular concentration of NO was measured in arterioles and venules and the tissue of the hamster chamber window model, subjected to acute extreme hemodilution, with a hematocrit (Hct) of 11% using Dextran 500 ( n = 6) or Dextran 70 ( n = 5) with final plasma viscosities of 1.99 ± 0.11 and 1.33 ± 0.04 cp, respectively. HV plasma significantly increased the periarteriolar, perivenular, and tissue NO concentration by 2.0, 1.9, and 1.4 times the control ( n = 7). The NO concentration with LV plasma was not statistically different from control. Arteriolar shear stress was significantly increased in HV plasma relative to LV plasma in arterioles but not in venules. Aortic endothelial NO synthase (eNOS) protein expression was increased with HV plasma but not with LV plasma. There was a weak correlation between perivascular NO concentration and the locally calculated shear stress induced by the procedures, when blood viscosity was corrected according to Hct values previously determined in studies of microvascular Hct distribution. The finding that the periarteriolar and venular NO concentration in HV plasma was the same although arteriolar shear stress was significantly greater than venular shear stress maybe be due to differences in vessel wall metabolism between arterioles and venules and the presence of NO transport through the blood stream in the microcirculation. Results support the concept that in extreme hemodilution HV plasma maintains functional capillary density through a NO-mediated vasodilatation.

scholarly journals PHYSICAL PROPERTIES OF GAMETES IN THREE SEA URCHIN SPECIES

1994 ◽  
Vol 194 (1) ◽  
pp. 263-284 ◽  
Author(s):  
F Thomas
Keyword(s):  
Physical Properties ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Shear Thinning ◽  
High Viscosity ◽  
Wave Action ◽  
Shear Rates ◽  
Low Viscosity ◽  
Male Gametes ◽  
High Shear Rates

Physical properties (density in kg m-3, viscosity, sinking rates and dispersion rate) of the gametes and associated spawned materials were measured for three species of sea urchin, Tripneustes gratilla, Echinometra mathaei and Colobocentrotus atratus, from habitats that differ in wave exposure. The gametes of all three species are negatively buoyant, highly viscous and exhibit shear-thinning (a decrease in viscosity with increasing shear rate). Female gametes are more viscous than male gametes, and the viscosity of female gametes differs among the three species. The viscosity of female gametes is highest for C. atratus, the species from habitats most exposed to wave action. Within the species T. gratilla, viscosity of female gametes is higher in habitats exposed to wave action than in more protected habitats. Evidence reported in this paper suggests that the shear-thinning of gametes may provide a performance advantage for these sea urchins. High viscosity of gametes at low shear rates may decrease gamete dispersal upon release and, under certain flow conditions, allow gametes to form strings and clumps on the surface of the urchin. Depending upon the morphology of the surface, these clumps or strings may be retained and fertilization may occur within these clumps or strings. Conversely, low viscosity of gametes at high shear rates decreases the power required to extrude gametes through the gonoduct during spawning.

scholarly journals A Low-Viscosity BisGMA Derivative for Resin Composites: Synthesis, Characterization, and Evaluation of Its Rheological Properties

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 338
Author(s):  
Ali Alrahlah ◽  
Abdel-Basit Al-Odayni ◽  
Haifa Fahad Al-Mutairi ◽  
Bashaer Mousa Almousa ◽  
Faisal S. Alsubaie ◽  
...  
Keyword(s):  
Substantial Reduction ◽  
Triethylene Glycol ◽  
High Viscosity ◽  
Resin Matrix ◽  
Resonance Spectroscopy ◽  
Dental Resin ◽  
Triethylene Glycol Dimethacrylate ◽  
Oh Groups ◽  
Low Viscosity ◽  
13C Nuclear Magnetic Resonance

This study aimed to synthesize new bisphenol A-glycidyl methacrylate (BisGMA) derivatives, targeting a reduction in its viscosity by substituting one of its OH groups, the leading cause of its high viscosity, with a chlorine atom. Hence, this monochloro-BisGMA (mCl-BisGMA) monomer was synthesized by Appel reaction procedure, and its structure was confirmed using Fourier transform infrared spectroscopy, 1H and 13C-nuclear magnetic resonance spectroscopy, and mass spectroscopy. The viscosity of mCl-BisGMA (8.3 Pa·s) was measured under rheometry conditions, and it was found to be more than 65-fold lower than that of BisGMA (566.1 Pa·s) at 25 °C. For the assessment of the viscosity changes of model resins in the presence of mCl-BisGMA, a series of resin matrices, in which, besides BisGMA, 50 wt % was triethylene glycol dimethacrylate, were prepared and evaluated at 20, 25, and 35 °C. Thus, BisGMA was incrementally replaced by 25% mCl-BisGMA to obtain TBC0, TBC25, TBC50, TBC75, and TBC100 blends. The viscosity decreased with temperature, and the mCl-BisGMA content in the resin mixture increased. The substantial reduction in the viscosity value of mCl-BisGMA compared with that of BisGMA may imply its potential use as a dental resin matrix, either alone or in combination with traditional monomers. However, the various properties of mCl-BisGMA-containing matrices should be evaluated.

scholarly journals A Conceptional Approach of Resin-Transfer-Molding to Rosin-Sourced Epoxy Matrix Green Composites

Aerospace ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 5
Author(s):  
Sicong Yu ◽  
Xufeng Zhang ◽  
Xiaoling Liu ◽  
Chris Rudd ◽  
Xiaosu Yi
Keyword(s):  
Composite Laminates ◽  
Resin Transfer Molding ◽  
High Viscosity ◽  
Ramie Fiber ◽  
Liquid Composite Molding ◽  
Curing Agent ◽  
Molding Process ◽  
Transfer Molding ◽  
Low Viscosity ◽  
Composite Molding

In this concept-proof study, a preform-based RTM (Resin Transfer Molding) process is presented that is characterized by first pre-loading the solid curing agent onto the preform, and then injecting the liquid nonreactive resin with an intrinsically low viscosity into the mold to infiltrate and wet the pre-loaded preform. The separation of resin and hardener helped to process inherently high viscosity resins in a convenient way. Rosin-sourced, anhydrite-cured epoxies that would normally be regarded as unsuited to liquid composite molding, were thus processed. Rheological tests revealed that by separating the anhydrite curing agent from a formulated RTM resin system, the remaining epoxy liquid had its flowtime extended. C-scan and glass transition temperature tests showed that the preform pre-loaded with anhydrite was fully infiltrated and wetted by the liquid epoxy, and the two components were diffused and dissolved with each other, and finally, well reacted and cured. Composite laminates made via this approach exhibited roughly comparable quality and mechanical properties with prepreg controls via autoclave or compression molding, respectively. These findings were verified for both carbon and ramie fiber composites.

Electrochemical Evaluation for Rust Preventive Properties of Rust Preventive Oils Coated on Fe-Cu-C Sintered Steel

2014 ◽  
Vol 783-786 ◽  
pp. 2537-2540 ◽  
Author(s):  
Satoshi Sunada ◽  
Norio Nunomura ◽  
Sayaka Hirata ◽  
Naoki Nagase
Keyword(s):  
Open Circuit Potential ◽  
High Viscosity ◽  
Open Circuit ◽  
Second Step ◽  
Sintered Steel ◽  
Corrosive Solution ◽  
The Third ◽  
Low Viscosity ◽  
Sintered Steels ◽  
Electrochemical Evaluation

Since Fe-Cu-C sintered steels are easily rusted, they are coated with rust preventive oils. High viscosity of those rust preventive oils decrease workability, and low viscosity deteriorates rust preventive performance. Therefore, it is necessary to develop new rust preventive oils with contradictory properties of low viscosity and superior rust prevention. However, precise methodology to evaluate rust prevention ability has not been established. In this study, we developed new technique to quantitatively evaluate rust prevention ability by measuring the open circuit potential through thin corrosive solution on Fe-Cu-C sintered steels coated with a rust preventive oils. As a result, the ability for rust prevention can be measured quantitatively, and it decreases slowly over time, with repeating destruction and restoration. Furthermore, it was found that the deteriorating processes of rust prevention ability for rust prevention oils are composed of three characteristics steps respectively. That is, in the first step the great open circuit potential changes from 0V to-0.3V with repetition were observed where the excellent rust prevention ability was kept, in the second step it decreases slowly from-0.1V to-0.4V with oscillation of the small potential changes where the gradual decrease of rust prevention ability was recognized and in the third step it decreases monotonously in the lower potential than-0.4V where the rust was observed because of the remarkable deteriorating of the rust prevention ability.

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