Low-viscosity Solutions Research Articles

Exploring exudate viscosity: A rheological analysis of wound exudates.

Exudate and its viscosity are critical in wound healing. Changes in viscosity can interfere with dressings properties as well as affect the diffusion of immune cells, nutrients, oxygen and bacteria. Current international standards for laboratory testing of wound dressings use a single low-viscosity solution, named as 'Test Solution A', which fails to simulate the diverse range of exudates encountered clinically. This study employs rheological analysis to characterise exudates viscosity, comparing cattle-derived samples to the test solution A. Results reveal non-Newtonian, shear-thinning behaviour in exudates, contrasting with the Newtonian behaviour of the test solution A. Although clinically classified as 'seropurulent', three exudate samples analysed at 37°C present with different viscosity at various shear rates, ranging from 30.8 (±14.7) to 6.5 (±1.9) mPas. Findings show that the current tests on dressings employing Test Solution A are missing the complexity of real exudates.

Gas channeling control with CO2-responsive gel system in fractured low-permeability reservoirs: Enhancing oil recovery during CO2 flooding

During the CO2 flooding process in fractured low-permeability oil reservoirs, the injected CO2 is prone to channeling along fractures due to severe reservoir heterogeneity, resulting in poor development effect. The CO2-responsive gel system shows dual advantages in achieving CO2 capture and plugging gas channeling to enhance oil recovery. This paper constructed a system with good CO2 sensitivity based on long-chain alkyl amide propyl dimethyl tertiary amine first. Subsequently, the properties of the system before and after the response were evaluated through rheological test, and its microstructure was characterized by Cryo-TEM. The system exhibited good CO2 responsiveness, transitioning from low-viscosity solution system to high-viscosity CO2-responsive gel system upon contact with CO2, with its viscosity increasing by nearly five orders of magnitude. The CO2-responsive gel demonstrated excellent shear resistance, viscoelasticity and shear self-repairing ability. The change of microstructure further verified the mechanism of molecules self-assembly in the system under the action of CO2. Then, a series of core physical simulation experiments were carried out to comprehensively evaluate the effects of different factors on the injection capacity, plugging characteristics, dynamic filtration damage performance and EOR effect of CO2-responsive gel. The gel maintained injectability while achieving an exceptional deep plugging effect, and the plugging rate reached 98.77%. It showed good characteristics of low filtration and permeability damage in low permeability reservoirs, effectively ensuring the fracture plugging effect. After the fracture was plugged by gel, the sweep range of CO2 to the matrix significantly expanded, and the gas flooding recovery increased by 18.19–21.7%. Finally, the matrix-fracture dual-media chip model was used to conduct microfluidic experiment, the oil displacement characteristics in different displacement stages were visually clarified, and the synergistic plugging and oil displacement mechanism between the CO2-responsive gel and CO2 was summarized. The research results can provide important insights for the green and efficient application of CO2-responsive gel in fractured low-permeability reservoirs.

Near-infrared fluorescent probe for the imaging of viscosity in fatty liver mice and valuation of drug efficacy

Fatty liver disease affects at least 25 percent of the population worldwide and is a severe metabolic syndrome. Viscosity is closely related to fatty liver disease, so it is urgent to develop an effective tool for monitoring viscosity. Herein, a NIR fluorescent probe called MBC-V is developed for imaging viscosity, consisting of dimethylaniline and malonitrile-benzopyran. MBC-V is non-fluorescent in low viscosity solutions due to intramolecular rotation. In high viscosity solution, the intramolecular rotation of MBC-V is suppressed and the fluorescence is triggered. MBC-V has long emission wavelength at 720 nm and large Stokes shift about 160 nm. Moreover, MBC-V can detect changes in cell viscosity in fatty liver cells, and can image the therapeutic effects of drug in fatty liver cells. By taking advantage of NIR emission, MBC-V can be used as an imaging tool for fatty liver disease and a way to evaluate the therapeutic effect of drug for fatty liver disease.

Inkjet Printing of Long-Range Ordering Two-Dimensional Magnetic Ti0.8Co0.2O2 Film.

The value of two-dimensional (2D) materials in printed electronics has been gradually explored, and the rheological properties of 2D material dispersions are very different for various printing technologies. Understanding the rheological properties of 2D material dispersions plays a vital role in selecting the optimal manufacturing technology. Inkjet printing is suitable for small nanosheet sizes and low solution viscosity, and it has a significant advantage in developing nanosheet inks because of its masklessness, high efficiency, and high precision. In this work, we selected 2D Ti0.8Co0.2O2 nanosheets, which can be synthesized in large quantities by the liquid phase exfoliation technique; investigated the effects of nanosheet particle size, solution concentration on the rheological properties of the dispersion; and obtained the optimal printing processing method of the dispersion as inkjet printing. The ultrathin Ti0.8Co0.2O2 nanosheet films were prepared by inkjet printing, and their magnetic characteristics were compared with those of Ti0.8Co0.2O2 powder. The films prepared by inkjet printing exhibited long-range ordering, maintaining the nanosheet powders' paramagnetic characteristics. Our work underscored the potential of inkjet printing as a promising method for fabricating precisely controlled thin films using 2D materials, with applications spanning electronics, sensors, and catalysis.

Characterization of an Injectable Chitosan Hydrogel for the Tunable, Localized Delivery of Immunotherapeutics.

Localized delivery of immunotherapeutics within a tumor has the potential to reduce systemic toxicities and improve treatment outcomes in cancer patients. Unfortunately, local retention of therapeutics following intratumoral injection is problematic and is insufficiently considered. Dense tumor architectures and high interstitial pressures rapidly exclude injections of saline and other low-viscosity solutions. Hydrogel-based delivery systems, on the other hand, can resist shear forces that cause tumor leakage and thus stand to improve the local retention of coformulated therapeutics. The goal of the present work was to construct a novel, injectable hydrogel that could be tuned for localized immunotherapy delivery. A chitosan-based hydrogel, called XCSgel, was developed and subsequently characterized. Nuclear magnetic resonance studies were performed to describe the chemical properties of the new entity, while cryo-scanning electron microscopy allowed for visualization of the hydrogel's cross-linked network. Rheology experiments demonstrated that XCSgel was shear-thinning and self-healing. Biocompatibility studies, both in vitro and in vivo, showed that XCSgel was nontoxic and induced transient mild-to-moderate inflammation. Release studies revealed that coformulated immunotherapeutics were released over days to weeks in a charge-dependent manner. Overall, XCSgel displayed several clinically important features, including injectability, biocompatibility, and imageability. Furthermore, the properties of XCSgel could also be controlled to tune the release of coformulated immunotherapeutics.

Nanorobots simulation by using an amplified cell model with motor

Nanotechnology is the future research area that could benefit human beings in many different directions. In order to build that technology for the human beings, it is necessary to do some research on the simulators to find out some important mechanical properties of these robots in the environment they are in, in other word, low Reynolds environments. To check the availability of the cell model, it is necessary to construct it by using MATLAB and SOLIDWORKS. After construction, the testing process would show that behavior difference of the model in relative high Reynolds environments and low Reynolds environments. The cell simulator would provide a faster swirling speed but a slower velocity in high viscosity solutions than in low viscosity solutions. That would be contradictory to the theory of the Reynolds number which potentially indicate a failure in the experiment. Thus, the macroscopic simulation model might not provide an accurate result for future nanorobotics.

Mechanochemically robust hydrophobic fabric using an aqueous emulsion of amine-terminated polydimethylsiloxane

Polydimethylsiloxane (PDMS) is a highly reliable thermosetting polymer with exceptional chemical and mechanical resistance, as well as remarkable water repellency and adhesive performance. Its unique features make it the preferred choice for fluorine-free hydrophobic coatings. However, the use of PDMS requires organic solvents that are toxic and environmentally hazardous. In this study, an emulsion composed of amine-terminated polydimethylsiloxane (PDMS-NH2) in an environmentally friendly solvent, water, was prepared. Subsequently, glutaraldehyde (GA) was added and crosslinked to generate a hydrophobic PDMS–GA emulsion. The PDMS–GA emulsion is a low-viscosity solution that can infiltrate different types of fabrics (cotton, nylon, and polyester) or paper with numerous intertwined fibers. After dipping the fabrics and paper into the prepared PDMS–GA emulsion, they were washed in an aqueous solution containing dispersed kaolin particles and dried to yield a rough structure. As a result, a hydrophobic surface with a water contact angle of 151.2° was achieved. Furthermore, after exposure to strongly acidic or alkaline solutions (pH 1–13) and washing six times with water, the hydrophobic fabric remained chemically stable. Additionally, it withstood ten tape peeling tests, proving its mechanical durability. Crucially, the hydrophobic treatment method does not involve fluorine and uses eco-friendly water as the solvent. Therefore, this is a convenient way to apply waterproof coatings to functional textiles that require water resistance and are expected to have great industrial applications.

Deposition of Uniform Nanoscale Patterns on Silicon Dioxide Based on Coaxial Jet Direct Writing.

To increase the printing stability of low-viscosity solutions, an auxiliary method was proposed using a coaxial electrohydrodynamic jet. A high-viscosity solution was employed as the outer layer in the printing process, and it could be removed (dissolved away) after printing the structures. A combination of mechanical and electrical forces was proposed to enhance the consistency, durability, and alignment of the printed versatile structures. The instability of the jet trajectory (which arose from the repulsion between the jet and the base with a residual charge, in addition to the winding effect of the solution) was also reduced using the drag force along the direction of movement. Moreover, the jet velocity, the surface charge, and the influence of various working voltages on the jet speed were simulated. An array of IDT-BT nanostructures measuring about 100 nm was prepared on silicon dioxide (using an inner needle with a diameter of 130 µm) by equating the moving speed (350 mm/s) of the substrate to the speed of the jet. Moreover, the moving speed (350 mm/s) of the substrate was compared exclusively to the speed of the jet. The method proposed throughout this study can provide a reference for enhancing the stability of low-viscosity solutions on substrates for high-efficiency fabrication devices (NEMS/MEMS).

The influence of repair technique on the distribution of biogenic CaCO3 in a mimic vertical crack

Microbially induced carbonate precipitation (MICP) is a promising solution for the remediation of concrete cracks. It has great advantages of environmental compatibility and exceptional penetration of cracks owing to its low-viscosity solution. Despite of these, practical application of MICP has been hindered by challenges including limited efficiency of in situ microbial deposition of CaCO3, extended repair cycles, and suboptimal strength recovery. Addressing these issues, this study undertook a comprehensive exploration of key repair process parameters for repairing cracks within the simulated crack space through inducing CaCO3 precipitation by a urease producing bacteria, specifically, the flow rate of the repair agents (7.958, 15.91, and 39.79 μL/min), the pre-sealing length of the crack (one-third of the crack length, half of the crack length, and full sealing), and the injection port position (upper, middle, and bottom of the crack). Their impacts on the distribution of bio-CaCO3 and overall repair effectiveness were examined in detail. Optimal repair performance was achieved at a flow rate of 15.91 μL/min, with full crack sealing, and the injection port situated at the bottom. This configuration resulted in a remarkable coverage rate of crack side wall, crack surface repair rate, and crack volume filling rates of 94.38%, 79.48%, and 100% respectively, and the first two were calculated using Image J software. The crack repair depth was significantly improved. Relative contribution rates to repair effectiveness was found to be ranked as follows: injection port position > flow rate > pre-sealing length. This study provides critical insights into the optimization of MICP repair process parameters, presenting a significant advancement in the understanding and development of effective techniques for concrete crack repair.

Efficient Large Area All‐Small‐Molecule Organic Solar Cells Fabricated by Slot‐Die Coating with Nonhalogen Solvent

AbstractThe commercialization of organic solar cells (OSCs) requires the use of roll‐to‐roll coating technology. However, it is generally believed that all‐small‐molecule (ASM) systems cannot form high‐quality films in most film‐fabrication technologies except for spin coating, mainly due to their strong crystallinity and low solution viscosity. Herein, it is found that the small molecule donor and acceptor system with strong intermolecular interaction can weaken the molecular self‐aggregation during film formation. As a result, all‐small‐molecule organic solar cells (ASM‐OSCs) are successfully fabricated using the green solvent tetrahydrofuran via spin coating as well as slot‐die coating technology. Under the optimal conditions, the devices achieve power conversion efficiency (PCE) of 14.05% and 13.41% prepared by spin coating and slot‐die coating, respectively. Moreover, a large‐area device with an area of 1 cm2 achieve a PCE of 10.65% by slot‐die coating. The study of the device performance and the active layer morphology reveal a unique film optimization mechanism in ASM‐OSCs. In the slot‐die coating process, a high‐quality film is formed due to the significantly suppressed crystallinity of the small molecule donor; with further thermal annealing, the crystallization‐induced phase separation enables an optimized morphology. This study proves that high‐performance ASM‐OSCs can be fabricated by the industrial‐compatible method.

Aqueous Two-Phase Enabled Low Viscosity 3D (LoV3D) Bioprinting of Living Matter.

Embedded 3D bioprinting has great value for the freeform fabrication of living matter. However, embedded 3D bioprinting is currently limited to highly viscous liquid baths or liquid-like solid baths. In contrast, prior to crosslinking, most hydrogels are formulated as low-viscosity solutions and are therefore not directly compatible with bioprinting due to low shape fidelity and poor print stability. The authors here present a method to enable low-viscosity ink 3D (LoV3D) bioprinting, based on aqueous two-phase stabilization of the ink-bath interface. LoV3D allows for the printing of living constructs at high extrusion speeds (up to 1.8 m s-1 ) with high viability due to its exceedingly low-viscosity. Moreover, LoV3D liquid/liquid interfaces offer unique advantages for fusing printed structures, creating intricate vasculature, and modifying surfaces at higher efficiencies than traditional systems. Furthermore, the low interfacial tension of LoV3D bioprinting offers unprecedented nozzle-independent control over filament diameter via large-dimension strand-thinning, which allows for the printing of an exceptionally wide range of diameters down to the width of a single cell. Overall, LoV3D bioprinting is a unique all-aqueous approach with broad material compatibility without the need for rheological ink adaption, which opens new avenues of application in cell patterning, drug screening, engineered meat, and organ fabrication.

Interfacial Reinitiation of Free Radicals Enables the Regeneration of Broken Polymeric Hydrogel Actuators

Interfacial Reinitiation of Free Radicals Enables the Regeneration of Broken Polymeric Hydrogel Actuators

Molecular structure and chiral recognition ability of highly branched cyclic dextrin carbamate derivative

A hyperbranched polymer, highly branched cyclic dextrin tris(3,5-dimethylphenylcarbamate) (HDMPC), consisting of rigid rodlike subchains was synthesized to investigate dimensional and hydrodynamic properties of HDMPC in methyl acetate and 4-methyl-2-pentanone at 25 °C. Both gyration radii and intrinsic viscosities of the HDMPC sample in the two solvents were much smaller than those for the linear amylose tris(3,5-dimethylphenylcarbamate) (ADMPC) chain with the corresponding molar mass. The chiral column made of the HDMPC sample has chiral separation ability for 8 racemates with a mobile phase of hexane/2-propanol while 6 of them were also separated by our previously investigated linear ADMPC column. These results indicate that HDMPC retains the functionality of the rigid linear ADMPC chain with much smaller chain dimensions and lower solution viscosity than those for the linear chain with the same molar mass.

Percolative Anodization: Tailoring TiO2 Nanotube Arrays Inside Ultrafine Ti Microchannels

Porous metals have generated increasing interest for biomedical, catalysis, energy and environmental applications, because of the high specific strength and large surface area. To make full use of the porous feature, it is of essential importance to tailor the surface morphology and wettability of the microchannels inside the metals. However, it remains a great challenge to uniformly and conformally coat the microchannels of <30 μm in view of the spatial limitation. In this work, a percolative anodization is developed to decorate the ultrafine microchannels of porous titanium with TiO2 nanotube arrays. Uniform and conformal nanotube coatings are produced throughout the channels of 0.5–10 μm with superwetting characters by optimizing the solvent viscosity. The mechanism of percolative anodization is established by investigating the nanotube growth in both torturous and straight channels. A key parameter of K value is thus introduced to elucidate the percolative anodization controlled either by electric field or concentration field. The anodization requires an electrolyte solution of low viscosity with K < 0.4, and may employ that of high viscosity with K > 0.4 to sufficiently coat the microchannels. The major findings reported herein can be extended to other porous metals for surface modification and functionalization.

Adaptation of the alginate production process for the brown alga Sargassum horridum (Fucales: Sargassaceae)

The genus Sargassum is a brown alga which is abundant in México, in the Gulf of California and the Caribbean Sea. The large biomass could be used to production of alginate, a polysaccharide with properties which allow it to form a thick solution or gels for different industries, such as for pharmaceutical and food products. The alginate production process may have some modifications, depending on the type of alga that is used as raw material, reducing water consumption and increasing the alginate yield and quality. In this research, the amount of water and reagents was optimized, reducing the volumes in the production process, based on the volumes used to process the giant kelp Macrocystis pyrifera. Hydration was reduced from 1 : 10 to 1 : 4 (part of alga : volume of chemical), acid pre-extraction from 1 : 10 to 1 : 5, extraction from 1 : 16 to 1 : 10, and dilution from 1 : 55 to 1 : 15; bleaching was improved from very dark brown to pale brown. The main reason that reduction is possible is that Sargassum has a more rigid cell wall than Macrocystis, absorbing less water and producing less viscosity. Although the alginate viscosity is relatively low, some applications require low viscosity solutions. However, the gel strength reached up to 1906 g cm−2, which may compete with other alginates to produce gelling products. To avoid the use of hydrochloric acid and decrease the contamination of wastewater in the process, the acid pre-extraction stage was changed for a neutral pre-cooking stage, resulting in an increase of the alginate yield from 8.3 % to 13.5 %; the viscosity was normally kept low, but the gel strength increased up to 2400 g cm−2.

Injectable bottlebrush hydrogels with tissue-mimetic mechanical properties.

Injectable hydrogels are desired in many biomedical applications due to their minimally invasive deployment to the body and their ability to introduce drugs. However, current injectables suffer from mechanical mismatch with tissue, fragility, water expulsion, and high viscosity. To address these issues, we design brush-like macromolecules that concurrently provide softness, firmness, strength, fluidity, and swellability. The synthesized linear-bottlebrush-linear (LBL) copolymers facilitate improved injectability as the compact conformation of bottlebrush blocks results in low solution viscosity, while the thermoresponsive linear blocks permit prompt gelation at 37°C. The resulting hydrogels mimic the deformation response of supersoft tissues such as adipose and brain while withstanding deformations of 700% and precluding water expulsion upon gelation. Given their low cytotoxicity and mild inflammation in vivo, the developed materials will have vital implications for reconstructive surgery, tissue engineering, and drug delivery applications.

Intrinsically Viscoelastic Supramolecular Conjugated Polymer toward Suppressing Coffee-Ring Effect

Intrinsically Viscoelastic Supramolecular Conjugated Polymer toward Suppressing Coffee-Ring Effect

Optimization of Spray-Drying Process Parameters to Study Anti-Sticking Effect of Hydroxypropyl Methyl Cellulose-VLV on Corni fructus Extracts.

To prevent the sticking of Corni fructus extract (CFE) during spray drying, the anti-sticking effects of different excipients were compared. Hydroxypropyl methylcellulose (HPMC)-VLV showed a higher powder yield at a lower dosage (8% of total solids), and a lower solution viscosity, compared with HPMC-E5. Therefore, HPMC-VLV is a more effective excipient for reducing CFE sticking during spray drying. The spray-drying process parameters were optimized by central composite rotatable design/response surface methodology, and spray drying was conducted under the following conditions: Inlet air temperature, 126 °C; atomization pressure, 1.05 bar; pump speed, 7.7 mL/min. Scanning electron microscopy showed that the powder comprised shrunken spherical particles with particle sizes in the range of 2-30 μm. Analysis of dynamic surface tension and chemical elements on the powder surface showed that HPMC-VLV rapidly moved to the droplet surface owing to its surface activity. HPMC covered the droplet surface and reduced surface tension, achieving an anti-sticking effect. In conclusion, HPMC-VLV at a solid content of 8% significantly improved the spray drying and reduced sticking of CFE. The spray-drying process parameters were nonlinearly related to the dry product yield. Graphical Abstract.

Facile polyamide microstructure adjustment of the composite reverse osmosis membrane assisted by PF127/SDS mixed micelles for improving seawater desalination performance

The integrity and uniformity of polyamide (PA) layer have a great influence on the separation performance of thin-film composite (TFC) polyamide reverse osmosis (RO) membrane. In this work, three kinds of micelles including the neutral macromolecule Pluronic F127 (PF127), anionic surfactant sodium dodecyl sulfate (SDS) and the PF127/SDS mixed micelles (PSMM), were proposed to be introduced in the aqueous phase to regulate the interfacial polymerization (IP) process with the purpose of constructing a more integrated and uniform PA separation layer of the RO membrane for seawater desalination. Compared to the single PF127 and SDS, the PSMM-1 (0.05 wt% PF127/0.05 wt% SDS) in the aqueous solution exhibited special advantages including unique three-dimensional (3D) spherical structure, lower solution viscosity and water-Isopar G interface tension (IFT), which sped up m-phenylenediamine (MPD) to homogeneously diffuse to the water-Isopar G interface and further regulated the interfacial polymerization reaction between MPD and trimesoyl chloride (TMC). Ultimately, the regulated RO membrane via PSMM-1 had more uniform PA layer and thus exhibited better comprehensive separation performances including higher salt rejection (more than 99.5%) and ideal water flux (about 35 L·m−2·h−1). This study provides a facile method of PA microstructure adjustment via micelles to fabricate higher-performance TFC RO membrane for seawater desalination.

Near-field electrospinning polycaprolactone microfibers to mimic arteriole-capillary-venule structure.

The ability to create three-dimensional (3D) cell-incorporated constructs for tissue engineering has progressed tremendously. One of the major challenges that limit the clinical applications of tissue engineering is the inability to form sufficient vascularization of capillary vessels in the 3D constructs. The lack of a functional capillary network for supplying nutrients and oxygen leads to poor cell viability. This paper presents the near-field electrospinning (ES) technique to fabricate a branched microfiber structure that mimics the morphology of capillaries. Polycaprolactone solution was electrospun onto a sloped collector that resulted in morphological and geometric variation of the fibers. With proper control over the solution viscosity and the electrospinning voltage, a single fiber was scattered into a branched fiber network and then converged back to a single fiber on the collector. The obtained fibers have a diameter of less than 100microns at the two ends with coiled and branched fibers of less than 10 microns that mimics the arteriole-capillary-venule structure. The formation of such a structure in the near-field ES strongly depends on the solution viscosity. Low viscosity solutions form beads and discontinuous lines thus cannot be used to achieve the desired structure. The branching of PCL fiber occurs due to an electrohydrodynamic instability. The transition from the straight large fiber to smaller coiled/branched fibers is not instantaneous and stretches over a horizontal region of 1.5cm. The current work shows the feasibility of electrospinning the stem-branch-stem fibrous structure by adopting a valley-shaped collector with potentials for tissue engineering applications.