Physical properties of soft contact lens multipurpose solutions commercially available in Ghana.

Purpose: To investigate the physical properties of commercially available multipurpose soft contact lens solutions in Ghana. Methods: pH (Kelilong ICL-099 pH meter, China), osmolality (OSMOMAT 3000, GONOTEC, Germany), surface tension (Sigma 700 Tensiometer, Sweden), and viscosity (CFOC-200 Viscometer, Cannon Company, USA) of various soft contact lens multipurpose solutions (MPS) were measured in triplicates at room temperature. Viscosity measurements were also taken at 34 °C ocular surface temperature. The solutions examined were Opti-Free Replenish (OFR), Trufresh (TF), Avizor (AV), Freshlook (FL), and Refresh (RF). Results: Several solutions were largely hypo-osmotic in the range of 108-231 mOsm/kg, the exception being Avizor, which had osmolality values that were closer to human tears (301 ± 0.58 mOsm/kg). The range of pH values of the solutions (6.33-8.24, mean (SD) = 7.53 ± 0.18) fell within the reported tolerable range for the ocular surface (6.20-9.00). Surface tension values ranged from 35.86 to 42.27 mNm with a mean of 38.49 ± 2.32 mNm. The average viscosity of most solutions at room temperature (25 °C) was 1.44 ± 0.49 cP with a range of 1.04-2.15 cP. Significantly lower values ranging from 0.79 to 1.58 cP were obtained at ocular surface temperature (34 °C), p = 0.0001). Conclusions: The physical properties of many of the solutions used as MPS in Ghana are markedly variable. Nevertheless, pH, surface tension, and viscosity fall within the acceptable limits of ocular physiological tolerance; except for osmolality, which majority were outside the reported tolerable range for the ocular surface. This information may partly explain the reason some patients exhibit strong preferences for certain care systems and should aid clinical decision-making when prescribing eye care systems to patients.

Flow properties of single origin chocolates: Effect of product formulation and particle size.

The objective of this research was to evaluate changes in flow behavior of chocolate during chocolate grinding using a stone grinder as affected by chocolate formulation. Three different types of chocolates were evaluated. Two chocolates without milk added (70% chocolate) and two chocolates with milk added and with different amounts of cocoa nibs (30% chocolate and 14% chocolate) were tested. For the 70% chocolates, nibs of two different origins were used; therefore, a total of four samples were evaluated. Chocolates were processed in a stone grinder, and samples were taken as a function of grinding time. For each timepoint, the flow behavior of the samples was measured using a rotational rheometer and fitted to the Casson model. Particle size was measured using a laser scattering instrument. Results showed that yield stress increased linearly while the Casson plastic viscosity decreased exponentially with grinding time (smaller particles). Particle size distribution of the chocolates showed a prominent bimodal distribution for short grinding times (∼9 h) with small (∼15 µm) and large (∼100 µm) particles; with longer grinding time, the population of larger particles decreased. Yield stress values were higher for the 70% chocolate, but they were not very different between the two milk chocolates tested. The Casson plastic viscosity was greatest for the 70% chocolate, followed by the 30% chocolate. The 14% chocolate had the lowest Casson plastic viscosity. Changes of Casson plastic viscosity with particle size were more evident for the dark chocolates compared to the milk ones. These results are helpful to small chocolate producers who need better understanding of how the formulation and grinding of chocolate affect its flow behavior, which will ultimately affect chocolate handling during production.

A lysosomal-targeted and viscosity-ultrasensitive near-infrared fluorescent probe for sensing viscosity in cells and a diabetic mice model.

Diabetes, as a metabolic disorder, has been implicated in organ dysfunction, often correlated with aberrant changes in viscosity. Lysosomal viscosity serves as an indicator of the lysosome's condition and activity, as it always varies synchronously with the change of lysosome's positioning, structure, and internal constituents. Diabetes, a condition within the metabolic disease category, has the potential to disrupt organ function due to irregular changes in viscosity. Therefore, early and precise diagnosis of diabetes is crucial for the prevention and management of diabetic conditions. Understanding the correlation between viscosity variations and lysosomal changes in vivo is vitally important for researching associated diseases. In this study, we developed Lyso-V, a near-infrared (NIR) fluorescent probe targeting lysosomes, with ultrasensitivity to viscosity changes. This probe, designed with a donor-π-bridge-acceptor (D-π-A) structure, exhibits a significant increase in NIR fluorescence intensity (approximately 690 times) when responding to viscosity, due to a twisted intramolecular charge transfer (TICT) mechanism. Furthermore, the probe designed specifically for lysosomes, enables the detection of changes in lysosomal viscosity as well as autophagy processes. Notably, through the application of this probe, we have detected an increased viscosity within the pathological model of the diabetic mouse. Moreover, Lyso-V was employed to measure the viscosity in diabetic mice. Owing to the multifaceted nature of the Lyso-V probe, it is anticipated to act as a practical and potent resource for deepening our understanding of the pathophysiological aspects of diabetes and aiding in its early detection.

Glycerol-slaved 1H-1H NMR cross-relaxation in quasi-native lysozyme.

1H-1H nuclear cross-relaxation experiments have been carried out with lysozyme in variable glycerol viscosity to study intramolecular motion, self-diffusion, and isotropic rigid-body rotational tumbling at 298 K, pH 3.8. Dynamics of intramolecular 1H-1H cross-relaxation rates, the increase in internuclear spatial distances, and lateral and rotational diffusion coefficients all show fractional viscosity dependence with a power law exponent κ in the 0.17-0.83 range. The diffusion coefficient of glycerol Ds with the bulk viscosity itself is non-Stokesian, having a fractional viscosity dependence on the medium viscosity (Ds âˆ¼ Î·-κ, κ ≈ 0.71). The concurrence and close similarity of the fractional viscosity dependence of glycerol diffusion on the one hand, and diffusion and intramolecular cross-relaxation rates of the protein on the other lead to infer that relaxation of glycerol slaves protein relaxations. Glycerol-transformed native lysozyme to a quasi-native state does not affect the conclusion that both global and internal fluctuations are slaved to glycerol relaxation.

Machine learning prediction of methane, nitrogen, and natural gas mixture viscosities under normal and harsh conditions.

The accurate estimation of gas viscosity remains a pivotal concern for petroleum engineers, exerting substantial influence on the modeling efficacy of natural gas operations. Due to their time-consuming and costly nature, experimental measurements of gas viscosity are challenging. Data-based machine learning (ML) techniques afford a resourceful and less exhausting substitution, aiding research and industry at gas modeling that is incredible to reach in the laboratory. Statistical approaches were used to analyze the experimental data before applying machine learning. Seven machine learning techniques specifically Linear Regression, random forest (RF), decision trees, gradient boosting, K-nearest neighbors, Nu support vector regression (NuSVR), and artificial neural network (ANN) were applied for the prediction of methane (CH4), nitrogen (N2), and natural gas mixture viscosities. More than 4304 datasets from real experimental data utilizing pressure, temperature, and gas density were employed for developing ML models. Furthermore, three novel correlations have developed for the viscosity of CH4, N2, and composite gas using ANN. Results revealed that models and anticipated correlations predicted methane, nitrogen, and natural gas mixture viscosities with high precision. Results designated that the ANN, RF, and gradient Boosting models have performed better with a coefficient of determination (R2) of 0.99 for testing data sets of methane, nitrogen, and natural gas mixture viscosities. However, linear regression and NuSVR have performed poorly with a coefficient of determination (R2) of 0.07 and - 0.01 respectively for testing data sets of nitrogen viscosity. Such machine learning models offer the industry and research a cost-effective and fast tool for accurately approximating the viscosities of methane, nitrogen, and gas mixture under normal and harsh conditions.

Comparison of thermal, rheological properties of Finnish Pinus sp. and Brazilian Eucalyptus sp. black liquors and their impact on recovery units.

Black liquor (BL) is the major bioproduct and biomass fuel in pulp mill processes. However, the high viscosity of BL makes it a challenging material to work with, resulting in issues with evaporators and heat exchangers during its transport and processing. The thermal and rheological properties of BLs from Pinus sp. (PBL) and Eucalyptus sp. (EBL) were studied. FTIR spectra revealed the presence of the characteristic functional groups and the chemical composition in liquors. TGA/DTG curves showed three characteristic degradation stages related to evaporation of water, pyrolysis of organic groups, and condensation of char. Rheologically, liquors are classified as non-Newtonian and with comportment pseudoplastic. Their rheological dynamic shear properties included a linear viscoelastic region up to 1% shear strain, while frequency sweeps showed that storage modulus (G') > loss modulus (G''), thus confirming the solid-like behavior of both BLs. The rheological study demonstrated that increasing the temperature and oscillatory deformations of PBL and EBL decreased their degree of viscoelasticity, which could favor their pumping and handling within the pulp mill, as well as the droplet formation and swelling characteristics in the recovery furnace.

Impact of saliva incorporation on the rheological properties of in vitro gastric contents formulated from sour cream.

Rheological properties of gastric contents depend on the food ingested, and on the volume and composition of secretions from the host, which may vary. This study investigates the impact of saliva regular incorporation in the stomach after a meal on the rheological properties of gastric contents, considering two levels of salivary flow (low = 0.5 and high = 1.5 mL/min). In vitro chymes were obtained by mixing sour cream, simulated gastric fluid, two different volumes of oral fluid (at-rest human saliva, SSF for Simulated Salivary Fluid or water) and adjusting pH at 3. Chymes samples were characterized at 37°C for their particle size and rheological properties. Overall, particle size distribution was not different between samples: incorporating a larger volume of saliva resulted in more heterogeneity, but the surface area moment D[3,2] and volume moment D[4,3] did not differ significantly with the oral fluid type. Shear viscosity of chyme samples was higher when saliva was incorporated, in comparison with water or SSF. In addition, as shown from data extracted at γ ̇ $$ \dot{\gamma} $$ = 20 s-1 the higher the fluid volume the lower the shear viscosity, which is attributed to a dilution effect. However, this dilution effect was attenuated in the case of saliva, most likely due to its composition in organic compounds (e.g., mucins) contributing to the rheological properties of this biological fluid. In these in vitro conditions, both saliva and the salivation rate had a significant but slight impact on the rheological properties of gastric contents (of the order of 1-5 mPa s at γ ̇ $$ \dot{\gamma} $$ = 20 s-1).

Incorporation of germinated lupin into corn-based extrudates: Focus on starch digestibility, matrix structure and physicochemical properties.

The research aimed to assess the effects of incorporating germinated Lupinus angustifolius flour into corn extrudates for different periods (3, 5, and 7 days), focusing on starch digestibility, morphological structure, thermal, and pasting properties. Extrudate with germinated lupinus flour for 7 days (EG7) significantly increased the content of slowly digestible starch up to 10.56% (p < 0.05). Crystallinity increased up to 20% in extrudates with germinated flour compared to extrudates with ungerminated flour (EUG), observing changes at the molecular level by FTIR that impact the thermal and pasting properties. X-ray diffraction revealed angles of 2θ = 11.31, 16.60, 19.91, and 33.04 as a result of the germination and extrusion processes. Microstructural analysis indicated starch-protein interactions influencing changes in calorimetry, viscosity, X-ray diffraction, and digestibility. PCA allowed establishing that the addition of germinated flours significantly affected the properties and microstructural characteristics of extruded products, potentially affecting digestibility and nutritional quality.

Sequence-Based Viscosity Prediction for Rapid Antibody Engineering.

Through machine learning, identifying correlations between amino acid sequences of antibodies and their observed characteristics, we developed an internal viscosity prediction model to empower the rapid engineering of therapeutic antibody candidates. For a highly viscous anti-IL-13 monoclonal antibody, we used a structure-based rational design strategy to generate a list of variants that were hypothesized to mitigate viscosity. Our viscosity prediction tool was then used as a screen to cull virtually engineered variants with a probability of high viscosity while advancing those with a probability of low viscosity to production and testing. By combining the rational design engineering strategy with the in silico viscosity prediction screening step, we were able to efficiently improve the highly viscous anti-IL-13 candidate, successfully decreasing the viscosity at 150 mg/mL from 34 cP to 13 cP in a panel of 16 variants.

Multifactor Analyses of Frontal Cortex Lipids in the APP/PS1 Model of Familial Alzheimer's Disease Reveal Anomalies in Responses to Dietary n-3 PUFA and Estrogenic Treatments.

Brain lipid homeostasis is an absolute requirement for proper functionality of nerve cells and neurological performance. Current evidence demonstrates that lipid alterations are linked to neurodegenerative diseases, especially Alzheimer's disease (AD). The complexity of the brain lipidome and its metabolic regulation has hampered the identification of critical processes associated with the onset and progression of AD. While most experimental studies have focused on the effects of known factors on the development of pathological hallmarks in AD, e.g., amyloid deposition, tau protein and neurofibrillary tangles, neuroinflammation, etc., studies addressing the causative effects of lipid alterations remain largely unexplored. In the present study, we have used a multifactor approach combining diets containing different amounts of polyunsaturated fatty acids (PUFAs), estrogen availabilities, and genetic backgrounds, i.e., wild type (WT) and APP/PS1 (FAD), to analyze the lipid phenotype of the frontal cortex in middle-aged female mice. First, we observed that severe n-3 PUFA deficiency impacts the brain n-3 long-chain PUFA (LCPUFA) composition, yet it was notably mitigated by hepatic de novo synthesis. n-6 LCPUFAs, ether-linked fatty acids, and saturates were also changed by the dietary condition, but the extent of changes was dependent on the genetic background and hormonal condition. Likewise, brain cortex phospholipids were mostly modified by the genotype (FAD>WT) with nuanced effects from dietary treatment. Cholesterol (but not sterol esters) was modified by the genotype (WT>FAD) and dietary condition (higher in DHA-free conditions, especially in WT mice). However, the effects of estrogen treatment were mostly observed in relation to phospholipid remodeling in a genotype-dependent manner. Analyses of lipid-derived variables indicate that nerve cell membrane biophysics were significantly affected by the three factors, with lower membrane microviscosity (higher fluidity) values obtained for FAD animals. In conclusion, our multifactor analyses revealed that the genotype, diet, and estrogen status modulate the lipid phenotype of the frontal cortex, both as independent factors and through their interactions. Altogether, the outcomes point to potential strategies based on dietary and hormonal interventions aimed at stabilizing the brain cortex lipid composition in Alzheimer's disease neuropathology.

Mechanical Characterization of Vial Strain During Freezing and Thawing Operations Using Amorphous Excipients.

The purpose of this study was to investigate the mechanical stresses and strains acting on pharmaceutical glass tubing vials during freezing and thawing of model pharmaceutical formulations. Strain measurements were conducted inside of a laboratory-scale freeze-dryer using a custom wireless sensor. In both sucrose and trehalose formulations at concentrations between 5 % and 20 % w/v, the strain measurements initially increased before peaking in magnitude at temperatures close to the respective glass transition temperatures of the maximally freeze concentrated solutes, Tg'. We attribute this behavior to a shift in the mechanical properties of the frozen system from a purely elastic glass below Tg' to a viscoelastic rubber-like material above Tg'. That is, when the interstitial region becomes mechanically compliant at temperature above Tg'. The outputs were less predictable below 5 % w/v and tended to exhibit two separate peaks in strain output, one near the equilibrium melting temperature of pure ice and the other near Tg'. The peaks merged at concentrations between 4 and 5 % w/v where the largest strain magnitude was observed. The strain on primary packaging has traditionally been applied to evaluate the risk of damage or breakage due to, for example, crystallization of excipients. However, data collected during this study suggest there may be utility in formulation design or as a process analytical technology to minimize potentially destabilizing stresses and strains in the frozen formulation.

Simultaneous Protein Adsorption and Viscosity Measurement using Micropillar-Enhanced Acoustic Wave (µPAW) Device for Pharmaceutical Applications.

At the early stages of drug development, the amount of drug materials is rather limited. In this case, viscosity measurement is often postponed to the later stages, where grams of proteins can be produced. Therefore, it is necessary to develop a viscometer capable of measuring the viscosity with high accuracy while requiring low sample volume. This study presents a novel viscosity measurement technique based on measuring the resonance frequency and motional resistance of a micropillar-enhanced acoustic wave (µPAW) device. The µPAW was developed by fabricating micropillars on the quartz crystal microbalance substrate in order to achieve ultra-high sensitivity, thanks to a unique coupling between the micropillar and the resonator. The experimental measurements demonstrated a nonlinear relationship between the density and viscosity of the fluid and the response of µPAW. A calibration correlation was developed using the response of µPAW in aqueous glycerol and sucrose solutions. The measurements were then extended using high-concentration BSA solutions as the model of protein solution. The main advantage of the µPAW device in this work over other viscometers is the ability to simultaneously measure solution viscosity and protein adsorption on the surface. This is a huge step forward in the development of sensing systems for the pharmaceutical industry, where real-time sensing of target biological proteins and measuring the viscosity of a solution is required.

3D vector MR elastography applications in small organs.

BACKGROUND: Magnetic resonance elastography (MRE) is a rapidly developing medical imaging technique that allows for quantitative assessment of the biomechanical properties of the tissue. MRE is now regarded as the most accurate noninvasive test for detecting and staging liver fibrosis. A two-dimensional (2D MRE) acquisition version is currently deployed at >2000 locations worldwide. 2D MRE allows for the evaluation of the magnitude of the complex shear modulus, also referred to as stiffness. The development of 3D vector MRE has enabled researchers to assess the biomechanical properties of small organs where wave propagation cannot be adequately analyzed with the 2D MRE imaging approach used in the liver. In 3D vector MRE, the shear waves are imaged and processed throughout a 3D volume and processed with an algorithm that accounts for wave propagation in any direction. Additionally, the motion is also imaged in x, y, and z directions at each voxel, allowing for more advanced processing to be applied. PURPOSE: This review describes the technical principles of 3D vector MRE, surveys its clinical applications in small organs, and discusses potential clinical significance of 3D vector MRE. CONCLUSION: 3D vector MRE is a promising tool for characterizing the biomechanical properties of small organs such as the uterus, pancreas, thyroid, prostate, and salivary glands. However, its potential has not yet been fully explored.

Enhancing rheology and reducing lipid digestion of oil-in-water emulsions using controlled aggregation and heteroaggregation of soybean protein isolate-peach gum microspheres.

There is a growing interest in developing highly viscous lipid foods using plant protein and polysaccharide gum-based emulsion technology. However, gaps remain in understanding the rheological, microstructural, and digestive properties of plant proteins like soybean protein isolate (SPI) in combination with various gums. This study investigates how combining SPI and peach gum (PG) affects rheology and lipolysis of oil-in-water (O/W) emulsions containing 20 wt% soybean oil. Emulsions with varying SPI and PG compositions including SPI-PG single and SPI/PG mixed droplet systems were prepared. Heating induced alterations in viscosity (e.g., SPI-PG from 14.88 to 90.27 Pa·s and SPI/PG from 9.66 to 85.32 Pa·s) and microstructure revealing aggregate formation at oil-water interface. The viscosity decreased significantly from the oral to intestinal phase (SPI-PG: 28.10 to 0.19 Pa·s, SPI/PG: 21.27 to 0.10 Pa·s). These changes affected lipid digestion, notably in SPI-PG and SPI/PG emulsions where a compact interface hindered lipolysis during digestion. Interestingly, free fatty acid (FFA) release during small intestinal phase followed a different order: SPI (82.51 %) > SPI-PG (70.77 %) > SPI/PG (63.60 %) > PG (56.09 %). This study provides insights into creating highly viscous O/W spreads with improved rheology, stability, and delayed lipid digestion, offering potential benefits in food product formulation.

Design of "Off-On-Off" fluorescence sensors for Heparin detection by precise modulation of molecular structure.

In this strategy, the fluorescence sensor Nap-Co-T1 employing the fluorescence resonance energy transfer (FRET) mechanism was designed and synthesized to have an efficient response to Heparin, and the FRET mechanism was explored for different excitation-emission wavelengths with different distances between the energy acceptor and the energy donor (comparing with fluorescence sensor Nap-TPA-T2). Upon the addition of Heparin, the fluorescence emission of Nap-Co-T1 was turned on at 565 nm, and the fluorescence color changed of the solution from colorless to bright yellow. The limit of detection (LOD) was as low as 0.04 µg/mL. With the addition of antagonistic protamine (PRTM) to the sensor complex with Heparin, the fluorescence emission was turned off to a certain extent, and the reversibility of the "off-on-off" system was maintained for five cycles or more. In addition, Nap-Co-T1 provides rapid and sensitive detection of Heparin in human serum albumin solution and artificial urine and is highly sensitive to environmental viscosity.

Relationship between rheological properties, sensory perception, and overall acceptability of thickened liquids for dysphagia in young and old healthy individuals.

This study investigated the relationship between rheological properties, sensory perception, and overall acceptability in healthy young and old groups for dysphagia thickened liquids. Unflavored (UTL) and flavored (FTLP) thickened liquids were prepared using tap water or pomegranate juice at 10 different viscosity levels. The rheological properties were then evaluated via syringe flow test and line spread test (LST). When the apparent viscosity levels of UTL and FTLP were similar, the syringe test and LST results were also similar, indicating consistent flow behavior. Sensory perception evaluations showed that the young group better distinguished viscosity differences between stages compared to the old group. Regarding overall acceptability, the old group preferred samples with higher apparent viscosity than the young group. Principal component analysis and k-means cluster analysis were used to explore correlations between variables and classify thickened liquids into four groups. This can serve the foundation for standardized texture grades of dysphagia thickened liquids, considering rheological characteristics and sensory profiles.

Development of BODIPY-based fluorescent probes for imaging Aß aggregates and lipid droplet viscosity.

Alzheimer's disease (AD), gradually recognized as an untreatable neurodegenerative disorder, has been considered to be closely associated with Aß plaques, which consist of ß-amyloid protein (Aß) and is one of the crucial pathological features of AD. There are no obvious symptoms in the initial phase of AD, and thus the therapeutic interventions are important for early diagnosis of AD. Moreover, recent researches have indicated that lipid droplets might serve as a potential ancillary biomarker, and its viscosity changes are closely associated to the pathological process of AD. Herein, two newly fluorescent probes 5QSZ and BQSZ have been developed and synthesized for identifying Aß aggregates and detecting the viscosity of lipid droplet. After selectively binding to Aß aggregates, 5QSZ and BQSZ exhibited linear and obvious fluorescence enhancements (32.58 and 36.70 folds), moderate affinity (Kd = 268.0 and 148.6 nM) and low detection limits (30.11 and 65.37 nM) in aqueous solutions. Further fluorescence staining of 5QSZ on brain tissue sections of APP/PS1 transgenic mouse exhibited the higher selectivity of 5QSZ towards Aß aggregates locating at the core of the plaques. Furthermore, 5QSZ and BQSZ displayed strong linear fluorescence emission enhancements towards viscosity changes and would be utilized to monitor variation in cellular viscosity induced by LPS or monensin. These two probes were non-cytotoxic and showed good localization in lipid droplets. Therefore, 5QSZ and BQSZ could serve as potential bi-functional fluorescent probes to image Aß aggregates and monitor the viscosity of lipid droplets, which have significant implications for the early diagnosis and progression of AD.

Age-specific and compartment-dependent changes in mitochondrial homeostasis and cytoplasmic viscosity in mouse peripheral neurons.

Mitochondria are dynamic bioenergetic hubs that become compromised with age. In neurons, declining mitochondrial axonal transport has been associated with reduced cellular health. However, it is still unclear to what extent the decline of mitochondrial transport and function observed during ageing are coupled, and if somal and axonal mitochondria display compartment-specific features that make them more susceptible to the ageing process. It is also not known whether the biophysical state of the cytoplasm, thought to affect many cellular functions, changes with age to impact mitochondrial trafficking and homeostasis. Focusing on the mouse peripheral nervous system, we show that age-dependent decline in mitochondrial trafficking is accompanied by reduction of mitochondrial membrane potential and intramitochondrial viscosity, but not calcium buffering, in both somal and axonal mitochondria. Intriguingly, we observe a specific increase in cytoplasmic viscosity in the neuronal cell body, where mitochondria are most polarised, which correlates with decreased cytoplasmic diffusiveness. Increasing cytoplasmic crowding in the somatic compartment of DRG neurons grown in microfluidic chambers reduces mitochondrial axonal trafficking, suggesting a mechanistic link between the regulation of cytoplasmic viscosity and mitochondrial dynamics. Our work provides a reference for studying the relationship between neuronal mitochondrial homeostasis and the viscoelasticity of the cytoplasm in a compartment-dependent manner during ageing.

Molecular Dynamics Simulation on Thickening and Solubility Properties of Novel Thickener in Supercritical Carbon Dioxide.

Supercritical CO2 has wide application in enhancing oil recovery, but the low viscosity of liquid CO2 can lead to issues such as poor proppant-carrying ability and high filtration loss. Therefore, the addition of thickening agents to CO2 is vital. Hydrocarbon polymers, as a class of green and sustainable materials, hold tremendous potential for acting as thickeners in supercritical CO2 systems, and PVAc is one of the best-performing hydrocarbon thickeners. To further improve the viscosity enhancement and solubility of PVAc, here we designed a novel polymer structure, PVAO, by introducing CO2-affine functional groups to PVAc. Molecular dynamics simulations were adopted to analyze viscosity and relevant solubility parameters systematically. We found that PVAO exhibits superior performance, with a viscosity enhancement of 1.5 times that of PVAc in supercritical CO2. While in the meantime, PVAO maintains better solubility characteristics than PVAc. Our findings offer insights for the future design of other high-performance polymers.

Synthesis and Performance of Polycarboxylate Superplasticizer with Viscosity-Reducing and Low-Shrinkage Properties for Fair-Faced Concrete.

A low-shrinkage and viscosity-reducing polycarboxylate superplasticizer was synthesized with maleic anhydride (MAH), diethylene glycol monobutyl ether, and methoxypoly (ethylene glycol) methacrylate (MPEGnMA). The surface tension, early shrinkage, cement paste performance, and application performance of concrete made with the synthesized water-reducing admixture were tested. A series of experiments were conducted to determine the optimal range of plastic viscosity coefficients for producing high-quality, fair-faced concrete with minimal surface defects. These experiments utilized both the synthesized water-reducing admixture alone and in combination with other water-reducing agents. The results showed that the synthesized water-reducing admixture had an ideal molecular structure, as confirmed by the GPC spectrum. When added to an aqueous solution, it reduced the surface tension from 72.47 mN/m to 30.56 mN/m. The 72 h shrinkage value of concrete was reduced by 20.6% compared with that of the conventional control group, effectively reducing shrinkage and adjusting the viscosity of the concrete mixture. Additionally, the influence of the plastic viscosity coefficient on the apparent voids in fair-faced concrete was investigated. This study revealed that when the plastic viscosity coefficient was between 5 and 10 Pa·s, the apparent void grade of the fair-faced concrete was simultaneously excellent and good. This water-reducing admixture helped prevent surface cracking and voids in fair-faced concrete, making it a suitable choice for producing high-quality fair-faced concrete surfaces.