Viscous Materials Research Articles

Noncontact 3D Bioprinting of Proteinaceous Microarrays for Highly Sensitive Immunofluorescence Detection within Clinical Samples.

Immunofluorescence assays are extensively used for the detection of disease-associated biomarkers within patient samples for direct diagnosis. Unfortunately, these 2D microarrays suffer from low repeatability and fail to attain the low limits of detection (LODs) required to accurately discern disease progression for clinical monitoring. While three-dimensional microarrays with increased biorecognition molecule density stand to circumvent these limitations, their viscous component materials are not compatible with current microarray fabrication protocols. Herein, we introduce a platform for 3D microarray bioprinting, wherein a two-step printing approach enables the high-throughput fabrication of immunosorbent hydrogels. The hydrogels are composed entirely of cross-linked proteins decorated with clinically relevant capture antibodies. Compared to two-dimensional microarrays, these proteinaceous microarrays offer 3-fold increases in signal intensity. When tested with clinically relevant biomarkers, ultrasensitive single-plex and multiplex detection of interleukin-6 (LOD 0.3 pg/mL) and tumor necrosis factor receptor 1 (LOD 1 pg/mL) is observed. When challenged with clinical samples, these hydrogel microarrays consistently discern elevated levels of interleukin-6 in blood plasma derived from patients with systemic blood infections. Given their easy-to-implement, high-throughput fabrication, and ultrasensitive detection, these three-dimensional microarrays will enable better clinical monitoring of disease progression, yielding improved patient outcomes.

Analysis of the Dispersive and Distributive Mixing Effect of Screw Elements on the Co-Rotating Twin-Screw Extruder with Particle Tracking.

Compounding is an important step in processing base polymers and is used to incorporate various additives into a polymer. For this purpose, different screw elements are used for dispersive and distributive mixing on a co-rotating twin-screw extruder. Optimising the screw configuration requires precise knowledge of the screw elements' mixing properties, which have not been thoroughly investigated. This study analyses the mixing behaviour of individual screw elements regarding dispersive and distributive mixing using 3D CFD flow simulations with subsequent particle tracking. For distributive mixing, the particle distribution behind the screw elements in the XY plane is analysed and the mixing index MQ, which relates the standard deviation and the mean value of the triangular areas between the particles, is calculated. For dispersive mixing, the maximum shear stress on the particle path and the integral of the shear stress over the residence time of each individual particle are determined. The results show that screw element geometry and rotation speed have a significant influence on dispersive and distributive mixing. In addition, better dispersive mixing is achievable with highly viscous materials. These findings enable the optimisation of the mixing zone of a co-rotating twin-screw extruder for the efficient mixing of mineral fillers.

Formation of Multiscale Porous Surfaces via Evaporation-Induced Aggregation of Imprinted Nanowires with Highly Viscous Photocurable Materials

AbstractNumerous structures at the nano and microscale manifest distinctive properties with far-reaching implications across diverse fields, including electronics, electricity, medicine, and surface engineering. Established methods such as nanoimprint lithography, photolithography, and self-assembly play crucial roles in the fabrication of nano- and microstructures; however, they exhibit limitations in generating high-aspect-ratio structures when utilizing high-viscosity photocurable resins. In response to this inherent challenge, we propose a highly cost-effective approach facilitating the direct replication of high-aspect-ratio structures, specifically nanowires, through the utilization of anodized aluminum substrates. This study elucidates the streamlined fabrication process for multiscale porous surfaces achieved through the evaporation-induced integration of solid nanowires printed with high-viscosity photocurable resin.

Ultrasonic vibration-assisted high-resolution electrohydrodynamic (EHD) printing

Electrohydrodynamic (EHD) printing has become a promising and cost-effective technique for producing high-resolution and large-scale features. One widely recognized obstacle in EHD printing is nozzle clogging due to solvent evaporation or ink polymerization. Moreover, printing highly viscous materials often requires pressure or other external force to assist the ink flow during the printing, which increases the complexity of process control and the required energy. In this work, we developed a novel ultrasonic vibration-assisted EHD printhead and associated process to effectively eliminate the nozzle clogging for the printing of high-viscosity and high-evaporation-rate inks. A series of experimental tests were conducted to characterize the printhead design and process parameters (i.e., vibration frequency, vibration amplitude, and printing voltage). The results demonstrated that superimposing ultrasonic vibration on the EHD printing nozzle can effectively enhance current EHD printing capabilities, such as reducing required pressure, eliminating nozzle clogging, and providing stable and continuous printing for high viscosity and high solvent evaporation rate material. With the optimal parameters, a filament with a diameter of around 1 µm can be continuously printed. In the paper, we successfully applied this developed ultrasonic-assisted EHD process to print high-resolution 2D patterns.

Research on screening effect and time-frequency characteristics of screen surface with additional striking beam

ABSTRACT In this study, a new flexible screen surface structure with an additional striking beam was proposed for improved efficiency and addressing the clogging issue while processing moist coal material. Vibration tests were used to analyze the time-frequency characteristics of the screen surface and the striking beam under no-load and load conditions. The effects of different process parameters on the elastic screening effect of viscous and wet materials were explored. Further, the industrial application of the equipment was preliminarily carried out. The results showed that the load did not affect the main vibration frequency of the elastic screen surface and the striking beam. When the axis distance was adjusted to 7.5 cm, the displacement from the feeding end to the discharge end gradually decreased, promoting the rapid loosening and stratification of the material group. Semi-industrial tests showed that the optimal screening effects had a screening efficiency of 92.16% and a total misplaced content of 5.95% when exciting force was 18 kN, the exciting frequency was 10.8 Hz, the feeding rate was 9.36 t/h, the distance was 7.5 cm, and the moisture content was 8.21%. The GQPSS1848 vibrating screen applied in the industry achieved a screening efficiency of 86.66% at a processing capacity of 85 t/h with a broad commercial prospect. The study aims to provide theoretical and technical support for the research and development of flexible screening equipment and the efficient classification of −3 mm sticky and wet materials.

Quantitatively measuring the cytotoxicity of viscous hydrogels with direct cell sampling in a micro scale format “MicroDrop” and its comparison to CCK8

Tissue engineering holds promise for developing therapeutic applications using viscous materials e.g. hydrogels. However, assessing the cytotoxicity of such materials with conventional assays can be challenging due to non-specific interactions. To address this, we optimized a live/dead staining method for quantitative evaluation and compared it with the conventional CCK8 assay. Our MicroDrop method involved seeding droplets containing 5000 cells in 10 µl medium on 12-well plates. After allowing them to adhere for 4 h, various viscous samples were applied to the cells and measurements were conducted using a fluorescence microscope immediately and at daily intervals up to 72 h. A sodium dodecyl sulfate (SDS) dilution series compared the MicroDrop with the CCK8 assay. The findings revealed a cell-type specific pattern for 10 mg/ml hyaluronic acid (HA), wherein MC3T3-E1 cells maintained 95% viability until 72 h, while L929 cells experienced a gradual decline to 17%. 2 mg/ml HA exhibited consistent viability above 90% across all time points and cell lines. Similarly, fibrin demonstrated 90% viability across dilutions and time points, except for undiluted samples showing a decrease from 85% to 20%. Gelatin-methacrylol sustained viability above 70% across all time points at both 5% and 10% concentrations. The comparison of the SDS dilution series between viability (MicroDrop) and metabolic activity (CCK8) assay showed a correlation coefficient of 0.95. The study validates the feasibility of the established assay, providing researchers with an efficient tool for assessing cytotoxicity in viscous materials. Additionally, it holds the potential to yield more precise data on well-known hydrogels.Graphical

Calculations of phase composition of austenitic high-nitrogen welding wire and study of a welded joint made from it

The processability of a material is directly related to the possibility of its production, operation and maintainability. One of the most important indicators of the processability of any metal is weldability. Austenitic steels with a high nitrogen content proved themselves as high-strength, corrosion- and cold-resistant materials, but the issue of their weldability is still not fully understood. The lack of welding filler materials on the market specifically designed for welding high-nitrogen steels is the primary obstacle to solving this problem. Thus, the goal of the work was to develop and obtain a laboratory sample of high-nitrogen welding wire. Based on calculations of nitrogen solubility and the phase composition of the weld metal, the chemical composition of Cr – Mn – Ni – Mo – V, N steel was selected for this wire. A defect-free ingot with 0.57 % N was obtained, and wire with a nitrogen content of 0.57 wt. % was produced using hot plastic deformation and drawing methods. Testing of this wire to obtain a welded joint of austenitic cast steel, close to it in chemical composition, with the welding process carried out according to the developed technological recommendations, made it possible to obtain a defect-free welded joint without loss of nitrogen in the weld metal. With a microhardness of the base metal of 252 HV50 , due to the alloying of the welding wire steel with nitrogen and vanadium, the metal of the weld and fusion line had a high microhardness (278 and 273 HV50 , respectively), significantly exceeding the microhardness of Cr – Ni cast austenite. The metal of the welded joint has high strength (0.9 of the base metal strength) and high impact toughness. The fracture of impact samples is characterized by a dimple structure characteristic of viscous materials. According to the obtained results, the new welding wire showed itself to be a promising material for welding austenitic high-nitrogen steels.

Load characteristics of screen panels in vibrating flip-flow screens

A vibrating flip-flow screen (VFFS) is an effective solution for screening viscous and fine-grained materials. As one of the critical components, the load characteristics of the polyurethane screen panel primarily affect the fatigue life. However, more research is needed to understand the load characteristics of the screen panel. In this article, the discrete screen panel dynamic model is proposed to research the load characteristics of the screen panel based on the catenary model. The dynamic response parameters of the screen panel are obtained by the catenary model, and the finite element model of the screen panel is established to extract the dynamic characteristic parameters of the screen panel. The accuracy of the catenary model and the finite element model is verified by the experiment, and then the rationality of the dynamic theory is verified by the simulation. Moreover, the effects of hardness, amplitude, frequency, and angle on the tension and vibration strength of the screen panel are investigated. The results show that hardness, amplitude, frequency, and angle significantly affect the tension and vibration strength of the screen panel. The sensitivity of each factor on tension from high to low: amplitude > hardness > frequency > angle. Adjusting the value of each factor within a certain range is beneficial to increasing the vibration strength; meanwhile, it can reduce the tension of the screen panel. This research helps improve the service life and provides a theoretical basis for designing and optimizing the screen panel.

Phenomena-based optimization of load function during nanoindentation experiments for estimating elastic aspect of viscous materials

We propose an optimized load function designed to acquire the elastic aspect during nanoindentation for two viscous polymers, i.e., polycarbonate (PC) and poly (methyl methacrylate) (PMMA). To do so, various load functions are followed where constant strain rate (P˙/P) varies from 0.05 /s to 50.0 /s, maximum load (Pm) from 1000 μN to 9000 μN and unloading rate (P˙UL) from 9.0 × 102 μN/s to 107 μN/s. Depending upon the P˙/P, extent of viscous deformation varies during loading, e.g., slow P˙/P shows more viscous deformation due to sufficient loading time and vice-versa. However, for fast P˙/P, a large amount of viscous deformation is observed only when the tip decelerates at the end of loading since the deceleration zone is the favor of viscous deformation. During holding, it is seen that a large amount of viscous deformation takes place for fast P˙/P at any Pm. Because viscous deformation could not take place during loading due to insufficient time that is why it takes place during holding. In addition, at high Pm large amount of viscous deformation takes place than low Pm. Since it is observed that different time is required for various P˙/P and Pm to saturate the viscous deformation during holding; hence, a novel method is suggested to estimate the required time for any P˙/P and Pm indentation. During unloading, it is noticed that for fast P˙UL less amount of viscoelastic recovery takes place towards Pm, hence, it is recommended that 95%–40% and 95%–60% unloading range should be considered to evaluate the elastic aspect for PC and PMMA, respectively.

Utilizing multiscale engineered biomaterials to examine TGF-β-mediated myofibroblastic differentiation.

Cells integrate many mechanical and chemical cues to drive cell signalling responses. Because of the complex nature and interdependency of alterations in extracellular matrix (ECM) composition, ligand density, mechanics, and cellular responses it is difficult to tease out individual and combinatorial contributions of these various factors in driving cell behavior in homeostasis and disease. Tuning of material viscous and elastic properties, and ligand densities, in combinatorial fashions would enhance our understanding of how cells process complex signals. For example, it is known that increased ECM mechanics and transforming growth factor beta (TGF-β) receptor (TGF-β-R) spacing/clustering independently drive TGF-β signalling and associated myofibroblastic differentiation. However, it remains unknown how these inputs orthogonally contribute to cellular outcomes. Here, we describe the development of a novel material platform that combines microgel thin films with controllable viscoelastic properties and DNA origami to probe how viscoelastic properties and nanoscale spacing of TGF-β-Rs contribute to TGF-β signalling and myofibroblastic differentiation. We found that highly viscous materials with non-fixed TGF-β-R spacing promoted increased TGF-β signalling and myofibroblastic differentiation. This is likely due to the ability of cells to better cluster receptors on these surfaces. These results provide insight into the contribution of substrate properties and receptor localisation on downstream signalling. Future studies allow for exploration into other receptor-mediated processes.

A Unified MPM Framework Supporting Phase-field Models and Elastic-viscoplastic Phase Transition

Recent years have witnessed the rapid deployment of numerous physics-based modeling and simulation algorithms and techniques for fluids, solids, and their delicate coupling in computer animation. However, it still remains a challenging problem to model the complex elastic-viscoplastic behaviors during fluid–solid phase transitions and facilitate their seamless interactions inside the same framework. In this article, we propose a practical method capable of simulating granular flows, viscoplastic liquids, elastic-plastic solids, rigid bodies, and interacting with each other, to support novel phenomena all heavily involving realistic phase transitions, including dissolution, melting, cooling, expansion, shrinking, and so on. At the physics level, we propose to combine and morph von Mises with Drucker–Prager and Cam–Clay yield models to establish a unified phase-field-driven EVP model, capable of describing the behaviors of granular, elastic, plastic, viscous materials, liquid, non-Newtonian fluids, and their smooth evolution. At the numerical level, we derive the discretization form of Cahn–Hilliard and Allen–Cahn equations with the material point method to effectively track the phase-field evolution, so as to avoid explicit handling of the boundary conditions at the interface. At the application level, we design a novel heuristic strategy to control specialized behaviors via user-defined schemes, including chemical potential, density curve, and so on. We exhibit a set of numerous experimental results consisting of challenging scenarios to validate the effectiveness and versatility of the new unified approach. This flexible and highly stable framework, founded upon the unified treatment and seamless coupling among various phases, and effective numerical discretization, has its unique advantage in animation creation toward novel phenomena heavily involving phase transitions with artistic creativity and guidance.

Research on the influence of fluid viscosity on the inlet flow parameters of wiped film molecular distillation

Wiped film molecular distillation is a kind of evaporation device with rotating scraping film structure, which is used to separate and purify viscous materials at molecular level. The feed pump of a wiped film molecular distillation is a centrifugal pump driven by a brushless DC motor. The fluid flow at the outlet has an important effect on the evaporation process. Based on the geometric model of the test pump generated by Gambit, the unsteady flow and head in the pump under optimal, low flow and shut off conditions were calculated, and the influence of liquid viscosity on the flow parameter pulsation behind the impeller, that is, inside the volute was investigated. The head calculated by unsteady flow model and steady flow model is compared with the experimental values. In addition, the calculated liquid velocity distribution during water transport is compared with the measured results of LDV in detail. The results show that the increase of fluid viscosity weakens the flow parameter pulsation behind the impeller of the feed pump and the flow separation tendency near the blade face.

Development of “Ink” for Extrusion Methods of 3D Printing with Viscous Materials

Development of “Ink” for Extrusion Methods of 3D Printing with Viscous Materials

The influence of material properties and process parameters on energy consumption during extrusion of flexible PVC

The aim of this work is to investigate the correlation between the process settings, the material properties, and the extrusion energy consumption. Experiments were conducted on a laboratory extruder, testing different flexible PVCs. During continuous single-screw extrusion for various process conditions, power signals were recorded for the extruder's motor and the entire machine. According to the results of the previous works, the absorbed current, the power factor, and the total active power increased with the screw speed for all the tested materials. However, due to the high content of additives, the considered materials exhibited wall-slip during extrusion, and the influence of the slip behavior on the specific energy consumption was evaluated too. It was found that the specific energy consumption did not decrease monotonically with the screw speed, and thus the maximum energy efficiency can not always be achieved at the highest screw speed. Significant correlations were found between the material's hardness, viscosity, and process energy usage, with the hardest and most viscous materials requiring more energy to be extruded.

CO2-Driven Nebulization of pH-Sensitive Supramolecular Polymers for Intraperitoneal Hydrogel Formation and the Treatment of Peritoneal Metastasis.

Because peritoneal metastasis (PM) from ovarian cancer is characterized by non-specific symptoms, it is often diagnosed at advanced stages. Pressurized intraperitoneal aerosol chemotherapy (PIPAC) can be considered a promising drug delivery method for unresectable PM. Currently, the efficacy of intraperitoneal (IP) drug delivery is limited by the off-label use of IV chemotherapeutic solutions, which are rapidly cleared from the IP cavity. Hence, this research aimed to improve PM treatment by evaluating a nanoparticle-loaded, pH-switchable supramolecular polymer hydrogel as a controlled release drug delivery system that can be IP nebulized. Moreover, a multidirectional nozzle was developed to allow nebulization of viscous materials such as hydrogels and to reach an even IP gel deposition. We demonstrated that acidification of the nebulized hydrogelator solution by carbon dioxide, used to inflate the IP cavity during laparoscopic surgery, stimulated the in situ gelation, which prolonged the IP hydrogel retention. In vitro experiments indicated that paclitaxel nanocrystals were gradually released from the hydrogel depot formed, which sustained the cytotoxicity of the formulation for 10 days. Finally, after aerosolization of this material in a xenograft model of PM, tumor progression could successfully be delayed, while the overall survival time was significantly increased compared to non-treated animals.

Sorghum oleoresins: Effect of extraction on compositional and structural characteristics

AbstractOleoresins are resin‐like viscous materials obtained from plants, oilseeds, or spices with functional properties. The objectives of this study were to obtain oleoresins from waxy burgundy sorghum grain, and to characterize the effects of extraction process and solvents on their composition and functional properties. Oleoresins were obtained by using the following solvents with and without ball milling: two types of novel ionic liquids (IL1: 1‐n‐Hexyl‐3‐methylimidazoliumchloride, IL2: 1‐Ethyl‐3‐methylimidazoliumchloride), ethanol and dichloromethane. The effects of processing were evaluated for the extraction yield, protein, fat and total phenolic content, fatty acid composition, particle size and zeta potential, and FTIR spectra. The use of ILs and ball mill process significantly (p < 0.05) affected the extraction yield and physicochemical properties. The highest extraction yields increased (31.35% ± 0.58) when ball milling used with IL2 in comparison to the lowest (18.37% ± 0.77) obtained by traditional ethanol extraction. In a similar way, protein concentration and phenolic content were the highest (1.37% ± 0.05 and 0.57% ± 0.01, respectively) with ball milling extraction and IL1. The FTIR spectra indicated higher phospholipids (at 1200 cm−1) and protein‐phospholipid bonding (at 1700 cm−1) by ILs, and ball milling as compared to traditional extraction. Overall, wet milling‐assisted extraction by using a ball mill and ILs provided control over the composition of the oleoresins important for value‐added food applications and higher extraction efficiencies as compared to traditional techniques.

Seismic Velocity Structure of Upper Mantle Beneath the Oldest Pacific Seafloor: Insights From Finite‐Frequency Tomography

AbstractThe oldest oceanic basin (160–180 Ma) in the western Pacific is the birthplace of the Pacific Plate and is thus essential for understanding the formation and evolution of the oceanic plate. However, the upper mantle structure beneath the region has not been thoroughly investigated because of the remoteness and difficulties of long‐term in situ seismic measurements at the ocean bottom. From 2018 to 2019, the Oldest‐1 experiment on the oldest seafloor was conducted as part of the international Pacific Array initiative. We present the first three‐dimensional P‐wave velocity structure down to a depth of 350 km based on the relative travel time residuals of teleseismic earthquakes recorded by 11 broadband ocean‐bottom seismometers operated during the Oldest‐1 experiment. Our result shows a fast P‐wave velocity anomaly (VP perturbation of 2%–4% faster than average) at a depth of 95–185 km beneath the northeast of the study area. This structure is interpreted as evidence of dry, viscous, and rigid materials at depths below the lithosphere. Two slow anomalies (VP perturbation of 2%–4% slower than average) are seen beneath the southwestern and eastern (the oldest seafloor >170 Ma) parts of the array site. The low‐velocity zones are found at depths of 95–305 km. The observed velocity structures can be indicative of plume activities that affected the upper mantle as the Pacific Plate migrated over hotspots from the southeast. Alternatively, the observed velocity features may provide seismic evidence for small‐scale sublithospheric convection.

Numerical modelling of high velocity impact problem involving non-linear viscosity

The paper is aimed at developing numerical models for simulation of hypervelocity collisions of small fragments with honeycomb shields relevant to Space structures protection from impact of debris fragments. Numerical modelling of hypervelocity collision within hydrodynamic approach reveals effects that are inconsistent with physical sense. In order to overcome these inconsistencies and to achieve justified description of the process of penetration and fracturing numerical model was developed assuming the impactor and projectile being viscous materials. Despite constant viscosity we investigate two phenomenological relationships for viscosity: depending on temperature and depending on deformation rate. The exponential dependence of viscosity on material state (temperature and second invariant of strain rate deviator) makes the material manifest both properties of fluid and solid state of matter. Taking into account viscosity allows to suppress jets at symmetry axis and small-scaled ejecta. The usage of non-constant viscosity results in a more physically based scenarios for fracturing of the shell obtained in numerical simulations.

Viscoelasticity of Liposomal Dispersions.

Janus-faced viscoelastic gelling agents-possessing both elastic and viscous characteristics-provide materials with unique features including strengthening ability under stress and a liquid-like character with lower viscosities under relaxed conditions. The mentioned multifunctional character is manifested in several body fluids such as human tears, synovial liquids, skin tissues and mucins, endowing the fluids with a special physical resistance property that can be analyzed by dynamic oscillatory rheology. Therefore, during the development of pharmaceutical or cosmetical formulations-with the intention of mimicking the physiological conditions-rheological studies on viscoelasticity are strongly recommended and the selection of viscoelastic preparations is highlighted. In our study, we aimed to determine the viscoelasticity of various liposomal dispersions. We intended to evaluate the impact of lipid concentration, the presence of cholesterol or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and the gelling agents polyvinyl alcohol (PVA) and hydroxyethylcellulose (HEC) on the viscoelasticity of vesicular systems. Furthermore, the effect of two model drugs (phenyl salicylate and caffeine) on the viscoelastic behavior of liposomal systems was studied. Based on our measurements, the oscillation rheological properties of the liposomal formulations were influenced both by the composition and the lamellarity/size of the lipid vesicles.

Mixing Characteristics and Parameter Effects on the Mixing Efficiency of High-Viscosity Solid–Liquid Mixtures under High-Intensity Acoustic Vibration

High-intensity acoustic vibration is a new technology for solving the problem of uniform dispersion of highly viscous materials. In this study, we investigate the mixing characteristics of high-viscosity solid–liquid phases under high-intensity acoustic vibration and explore the effect of vibration parameters on the mixing efficiency. A numerical simulation model of solid–liquid–gas multiphase flow, employing the volume of fluid (VOF) and discrete phase model (DPM), was developed and subsequently validated through experimental verification. The results show that the movement and deformation of the gas–liquid surface over the entire field are critical for achieving rapid and uniform mixing of the solid–liquid phases under acoustic vibration. Increasing the amplitude or frequency of vibration can intensify the movement and deformation of the free surface of gas and liquid, improve the mixing efficiency, and shorten the mixing time. Under the condition of constant acceleration, the mixing efficiency of materials is higher at low frequency and high amplitude. Further, we define a relationship that predicts desirable mixing conditions as a function of amplitude and frequency. This serves as a valuable reference guide for evaluating the minimum requirements when selecting operating parameters.