High-concentration Gels Research Articles

High concentration in situ polymer gel electrolyte for high performance lithium metal batteries.

A high concentration gel polymer electrolyte (GPE) was prepared by simply using LiFSI-LiNO3 dissolved in 1,3-dioxolane. The Li‖Li cell achieves stable battery cycling for over 3200 h. Furthermore, the Li‖Cu cell demonstrates a high CE of 99.2%. Even at a high current density of 8 mA cm-2, a high CE of 98.5% was still achieved. Notably, in a Li‖LiFePO4 cell, this electrolyte enables high capacity retention of 94.5% and an average CE of 99.8% over 500 cycles, showing promising prospects for high-performance lithium metal batteries.

Deleterious Effects over Enamel Surface Bleached with Low and High Concentration Gels Containing Calcium In vitro Evaluation

Deleterious Effects over Enamel Surface Bleached with Low and High Concentration Gels Containing Calcium In vitro Evaluation

Investigation of Different Scenarios in Simulation of Controlling Water Production in Oil Wells Using Silica Gel Treatments

Excess water production is one of the limiting factors in oil recycling, which reduces production efficiency and leaves a lot of costs. In this paper, water control methods were investigated in order to find the best way to control excess water production. For this propos first, a real model was made using the history match of one of Iran's oil fields that produced excess water because of canalization and different simulation scenarios for gel treatment have been investigated. In the study of more scenarios, comparing the water production in the early times and later injecting the gel, the percentage of water production for injection in the early times has been further reduced. When the gel is injected for a fixed period of 6 months in the production and injection wells The best results for lowering the rate of production water are obtained when the gel is injected simultaneously into the injection and production well, which reduces the water production rate by 12,000 barrels, and the best oil production efficiency for when simultaneous injection is performed in the production and injection well. The best treatment method is injection of high concentration gel in the early stages of water production and it's better to inject gel in deeper wells.

Cyclohexamer [-(d-Phe-azaPhe-Ala)2-]: good candidate to formulate supramolecular organogels.

Molecular self-assembly is a fascinating process which has become an area of great interest in supramolecular chemistry, as it leads in certain cases to molecular gels. Organogels formulated from low molecular weight compounds (LMWOGs) have attracted much interest in the past decades due to their applications as new soft materials. Herein, we report on the ability of the cyclic pseudopeptide cyclo-[-(d-Phe-azaPhe-Ala)2-] (2) to self-assemble in some aromatic solvents and to form organogels driven by non-covalent forces, mainly hydrogen bonding and π-stacking interactions. Comprehensive FTIR and NMR studies emphasized that this cyclic aza-peptide adopts a β-turn conformation at low concentration in toluene, while an equilibrium between the monomeric states (intramolecular forces) and the supramolecular structures (intra- and intermolecular forces) is established at high concentration (gel state). Rheological investigations of the organogels highlight the dependence of their stiffness (up to ∼4 kPa) and sol/gel transition temperatures (up to 100 °C) as a function of the solvent and concentration of gelator used. The formulation of fibrous structures confirmed the phenomenon of self-assembly. Finally, we found that cyclo-[-(d-Phe-azaPhe-Ala)2-] is an effective organogelator for application in phase selective gelation (PSG) of organic solvents from aqueous/organic mixtures with recovery percents up to 96%.

Directly crosslinked dextran gels for SWCNT separation

The gel column chromatography method allows high-throughput and high-purity single-wall carbon nanotube (SWCNT) separation. However, the role of the gel in this system has not been fully understood. In this study, five gels with different dextran concentrations were synthesized by directly crosslinking dextran with epichlorohydrin. The low dextran concentration gels work for metal/semiconductor separation and diameter sorting of semiconducting SWCNTs. This is evidence that the chemical structure in the gel that is responsible for the selective adsorption of semiconducting SWCNTs is dextran. However, high dextran concentration gels did not adsorb SWCNTs, although the adsorption site was dextran. Micro-Raman measurements on gel slices revealed that the high dextran concentration gel has a pore size too small to allow deep diffusion of SWCNTs. Not only the chemical structure but also the physical structure is important for designing high-performance gels for SWCNT separation in the near future.

Formation and evolution of shish‐kebab structure during hot stretching in gel‐spun ultra‐high molecular weight polyethylene fibers with high concentration gel solution

Formation and evolution of shish‐kebab structure during hot stretching in gel‐spun ultra‐high molecular weight polyethylene fibers with high concentration gel solution

Pharmacokinetics of the Protein Microbicide 5P12-RANTES in Sheep following Single-Dose Vaginal Gel Administration.

5P12-RANTES, a chemokine analogue that potently blocks the HIV CCR5 coreceptor, is being developed as both a vaginal and rectal microbicide for prevention of sexual transmission of HIV. Here, we report the first pharmacokinetic data for 5P12-RANTES following single-dose vaginal gel administration in sheep. Aqueous gel formulations containing low (1.24-mg/ml), intermediate (6.18-mg/ml), and high (32.0-mg/ml; suspension-type gel) concentrations of 5P12-RANTES were assessed via rheology, syringeability, and in vitro release testing. Following vaginal gel administration to sheep, 5P12-RANTES concentrations were measured in vaginal fluid, vaginal tissue, and serum over a 96-h period. All gels showed non-Newtonian pseudoplastic behavior, with the high-concentration gels exhibiting a greater viscosity and cohesive structure than the intermediate- and low-concentration gels. In in vitro release testing, >90% 5P12-RANTES was released from the low- and intermediate-concentration gels after 72 h. For the high-concentration gel, ∼50% 5P12-RANTES was detected, attributed to protein denaturation during lyophilization and/or subsequent solvation of the protein within the gel matrix. In sheep, 5P12-RANTES concentrations in vaginal fluid, vaginal tissue, and serum increased in a dose-dependent manner. The highest concentrations were measured in vaginal fluid (105 to 107 ng/ml), followed by vaginal tissue (104 to 106 ng/ml). Both of these concentration ranges are several orders of magnitude above the reported half-maximal inhibitory concentrations. The lowest concentration was measured in serum (<102 ng/ml). The 5P12-RANTES pharmacokinetic data are similar to those reported previously for other candidate microbicides. These data, coupled with 5P12-RANTES's potency at picomolar concentrations, its strong barrier to resistance, and the full protection that it was observed to provide in a rhesus macaque vaginal challenge model, support the continued development of 5P12-RANTES as a microbicide.

Versatile mechanically strong and highly conductive chemically converted graphene aerogels

Many efforts have been devoted to fabricating three-dimensional graphene-derived aerogels owing to their promising real-world applications. However, it is still a challenge to fabricate a pure graphene-based aerogels with both high mechanical strength and conductivity. In this study, we report a facile and scalable method to prepare pure chemically converted graphene aerogels (CCGA) from high-concentration gel precursors with the assistance of two-step freeze-drying. The CCGA demonstrates a high compressive strength of 106.1 kPa under a strain of 80%. Its resistance in the thickness direction is variable and reaches as low as 6.6 Ω at a compressive strain of 90%. The aerogels also show many interesting behaviors and properties, including promising Joule heating-assisted oil absorption, non-flammability, and the ability to sense a wide range of applied pressure.

Enhanced gelation of chitosan/β-sodium glycerophosphate thermosensitive hydrogel with sodium bicarbonate and biocompatibility evaluated

The application of chitosan/β-sodium glycerophosphate (β-GP) thermosensitive hydrogel has been limited by the relatively slow gelation, weak mechanical resistance and poor cytocompatibility. In this study, sodium hydrogen carbonate (NaHCO3) was applied with β-GP as gel agents to produce high-strength hydrogel. The hydrogels prepared with high NaHCO3 concentration or more gel agents showed shorter gelation time, better thermostability, drastically enhanced resistance in compression. Meanwhile, the hydrogels presented obvious porous structures and excellent biocompatibility to HUVEC and NIH 3T3 cultured in vitro with higher NaHCO3 concentration and moderate concentration of β-GP. Overall, appropriate concentration of β-GP combined with NaHCO3 can be a good gel regent to improve properties of chitosan thermosensitive hydrogels.

Menthol concentration in topical cold gel does not have significant effect on skin cooling.

Topical menthol gels are used in the treatment of various pain conditions. However, the effect of the menthol concentration to skin cooling or cooling sensation is not clear. We hypothesized that increasing menthol concentration enhances skin cooling and causes elevated cooling sensation. Ten healthy male volunteers (age range 25-30 years) were recruited for this study. Application of three gels with different menthol concentrations (0.5%, 4.6% and 10.0%) was tested in random sequence on the left thigh of the subjects. Skin cooling was recorded with a digital infrared camera (FLIR Systems Inc., USA), and cooling sensation was measured with the visual analogue scale rating. All gels decreased skin temperature significantly (P < 0.05) at least for one hour. However, the variation in menthol concentration seemed not to have a significant effect on skin cooling. Subjects experienced that gel with 4.6% menthol concentration caused significantly stronger cooling effect than 0.5% and 10.0% gels. Gel application had no significant effect on skin temperature in surrounding skin areas. In contrast to our hypothesis, menthol concentration was not connected to skin cooling, while moderate menthol concentration of 4.6% may induce stronger cooling sensation compared to low (0.5%) or high (10.0%) concentration gels.

Influence of hydrogen peroxide-based bleaching agents on the bond strength of resin–enamel/dentin interfaces

This study evaluated the effect of different bleaching techniques on the bond strength of pre-existing adhesive restorations in enamel and dentin. Hydrogen peroxide-based bleaching gels with different concentrations (7.5% and 35%) were used on composite restorations of Adper Single Bond 2 (3M/ESPE, St. Paul, USA) and Filtek Z250 (3M/ESPE, St. Paul, USA). Twenty human third molars were randomly divided into 8 groups: GE—enamel control; GE7.5—bleaching using 7.5% hydrogen peroxide; GE35—bleaching using 35% hydrogen peroxide; GE 7.5+35—bleaching using 7.5% and 35% hydrogen peroxide; GD—dentin control; GD7.5—7.5% hydrogen peroxide; GD35—35% hydrogen peroxide; and GD 7.5+35—7.5% and 35% hydrogen peroxide. Bleaching was performed using long clinical application-time to low concentration gel, and short clinical application-time to high concentration gel. Unbleached specimens were stored in artificial saliva for 14 days. Specimens subject to micro-shear testing and data were analyzed by Analysis of Variance and Tukey's test (p=0.05). Enamel micro-shear bond strength was reduced after 7.5% hydrogen peroxide and after association of 7.5% and 35% hydrogen peroxide. Bleaching treatment altered dentin bond strength only when using 7.5% hydrogen peroxide. The results suggest that the bond strength of the restorations was influenced by the clinical extent of bleaching-gel application time and was not dependent on bleaching-gel concentration.

Quantitative Analysis of the Effect of Cancer Invasiveness and Collagen Concentration on 3D Matrix Remodeling

Extracellular matrix (ECM) remodeling is a key component of cell migration and tumor metastasis, and has been associated with cancer progression. Despite the importance of matrix remodeling, systematic and quantitative studies on the process have largely been lacking. Furthermore, it remains unclear if the disrupted tensional homeostasis characteristic of malignancy is due to initially altered ECM and tissue properties, or to the alteration of the tissue by tumor cells. To explore these questions, we studied matrix remodeling by two different prostate cancer cell lines in a three-dimensional collagen system. Over one week, we monitored structural changes in gels of varying collagen content using confocal reflection microscopy and quantitative image analysis, tracking metrics of fibril fraction, pore size, and fiber length and diameter. Gels that were seeded with no cells (control), LNCaP cells, and DU-145 cells were quantitatively compared. Gels with higher collagen content initially had smaller pore sizes and higher fibril fractions, as expected. However, over time, LNCaP- and DU-145-populated matrices showed different structural properties compared both to each other and to the control gels, with LNCaP cells appearing to favor microenvironments with lower collagen fiber fractions and larger pores than DU-145 cells. We posit that the DU-145 cells' preference for denser matrices is due to their higher invasiveness and proteolytic capabilities. Inhibition of matrix proteases resulted in reduced fibril fractions for high concentration gels seeded with either cell type, supporting our hypothesis. Our novel quantitative results probe the dynamics of gel remodeling in three dimensions and suggest that prostate cancer cells remodel their ECM in a synergistic manner that is dependent on both initial matrix properties as well as their invasiveness.

Experimental Investigation on the Separation of Bentonite using Ceramic Membranes: Effect of Turbulence Promoters

The static turbulence promoters presented in this work are designed to enhance filtration within tubular ceramic membranes of 0.5 micron pore size. Permeate flux enhancement still remains a topical problem during tangential crossflow filtration. The decline in flux with time is due to the usual phenomena of concentration polarization and membrane fouling, operating parameters including the system pressures, feed composition, membrane type and configuration, and the hydrodynamics within the membrane module. Solute accumulates on the membrane surface and forms a high concentration gel layer, thus increasing the effective membrane thickness and reduces its hydraulic permeability. Turbulence promoters of varying pitch lengths have been incorporated into the work to ultimately reduce the deposition of bentonite particles on the membrane surface during microfiltration. Yeast suspensions have previously been used as feed suspensions in order to compare the effectiveness of the turbulence promoters with an organic foulant. The objective of this work was to investigate the influence of static promoter geometry on flux sustainability enhancement during bentonite suspension filtration. All experiments have been conducted on a tubular ceramic membrane and the experimental membrane rig as shown in this paper. The effects of feed concentration, feed temperature, system pressures, and crossflow rates on the membrane flux sustainability were investigated. It was found that the promoters greatly improved flux sustainability and membrane efficiency over time and in some cases, a loss of 3% in membrane efficiency was realized with turbulence promoters at higher feed temperatures. The use of the turbulence promoter caused a large scouring of the membrane surface and membrane cleaning was significantly improved compared to the experiments without the promoters.

Thermal Behavior of Syndiotactic Polystyrene/1,2‐Dichloroethane Gels and Stoichiometry of Polymer‐Solvent Compounds

The phase behavior of syndiotactic polystyrene (sPS)/1,2‐dichloroethane (DCE) gels has been investigated by differential scanning calorimetry (DSC) and wide angle x‐ray diffraction (WAXD) for different gel formation conditions. DSC data show that the gel melting temperatures are independent of the cooling conditions leading to gel formation, whereas the melting enthalpies of the gels depend on the cooling history. WAXD measurements show that for low concentration gels the sPS/DCE clathrate structure is obtained, whereas for high concentration gels both the clathrate structure and the solvent‐free β phase can be obtained. Furthermore, the onset of formation of the β phase is dependent on the cooling rate. In light of combined DSC and WAXD data, the reliability of the DSC in evaluating the absolute stoichiometry of polymer‐solvent compounds formed in sPS/DCE gels is discussed.

Flux enhancement by using helical baffles in ultrafiltration of suspended solids

The main reason for the flux decline during the initial period of all filtration processes is the usual phenomena of concentration polarization and fouling. After this stage follows the cake filtration process that allows the obtaining of the steady state flux. The solute accumulated on the membrane surface forms a high concentration gel layer, which increases the effective membrane thickness and so reduces its hydraulic permeability. Different techniques are used to reduce this formation and use of helical baffles inside the membrane element is one of such techniques. The selection of appropriate helical baffle is vital to get improved permeation flux with minimum pressure drop for cross-flow feed. The number of helices/unit length has a considerable influence on the selected helical baffle. All experiments have been conducted with an inorganic tubular ultrafiltration membrane for filtering a supernatant from activated sludge plant consisting of suspended and biological solids. The influence of the operational parameters is studied in this paper. Nevertheless, the feed temperature and the concentration were kept constant at the industrial values. We found 1 bar as an optimal pressure, above this pressure the permeation flux decreases, contrarily to several works, which observe a plateau after certain value of pressure. Progressive fouling can be limited by use of helical baffles in the filtration element operated at low pressures and the flocculation of particles is reduced. On the other hand, we have found that the influence of Reynolds number inside the membrane tube and the feed flow-rate are similar to other studies that used different helical baffles.

Comprehensive analysis of p53 gene mutation characteristics in lung carcinoma with special reference to histological subtypes.

To date, the characteristics of p53 gene mutations in lung cancer have been extensively investigated. However, current estimates of p53 alterations are inaccurate, since most investigators have limited their analyses to exons 5 to 8 of the p53 gene. We examined 52 lung carcinoma cell lines and 106 primary non-small cell lung carcinomas (NSCLC) for mutations in the entire coding region of the p53 gene, from exons 2 to 11. High resolution single strand conformation polymorphism analysis was performed using a modified electrophoretic apparatus with a high concentration gel (14%) and accurate temperature control. The prevalence of mutations was high (more than 80%) in both small cell lung carcinoma (SCLC) (15 of 18) and NSCLC cell lines (28 of 34), and 9 of 45 mutations (20%) were detected outside the region of exons 5 to 8. The frequency of the mutations in primary NSCLC was 48% (51 of 106) and was significantly different (p=0.01) between adenocarcinoma (39%) and squamous cell carcinoma (67%). A-->G transitions (14%, 6 of 43 cases) as well as G-->T transversions (26%, 11 of 43 cases) were frequently detected with significant strand bias in smoking patients, suggesting that carcinogens causing these mutations are involved in smoking associated lung carcinogenesis.

Rheological properties of acidic soybean protein gels: Salt addition effect

The objective of this work was to study rheological properties of acidic soybean protein gels in the presence of sodium and calcium chloride. The viscoelastic properties of acidic gels were affected by the amount and type of the assay salt. The pH 2.75 dispersions prepared with 0.1–0.25 M NaCl behaved as diluted macromolecular or entanglement solutions and were more viscous than elastic. At high ionic strength (2.0 M NaCl), samples were more elastic with a gel-like behavior. A semidiluted macromolecular solutions was observed for dispersions at pH 3.50 with 0.1 M NaCl, while at high salt concentration (0.25–2.0 M) gels were obtained. At pH 2.75 gelation kinetics was different at several NaCl concentrations, while at pH 3.50, first order kinetics was observed. At pH 2.75 and 0.1 M CaCl 2, the dispersions behaved as semidiluted macromolecular solutions, while at 0.2 M CaCl 2 diluted macromolecular solutions were obtained. A semidiluted solution dynamic spectra for pH 3.50 samples (0.1–0.2 M CaCl 2) was observed. Both pH 2.75 and 3.50 gels prepared with several NaCl concentrations were more fragile, hardest and resistant rupture than those obtained with CaCl 2. The textural properties of acidic gels were less modified by CaCl 2.

Raman spectroscopic study on water in aqueous gelatin gels and sols

AbstractA Raman spectroscopic study on property changes of water in aqueous gelatin media was carried out. The state of water in gelatin gels and sols at various temperatures and concentrations was studied in connection with the conformation of polymer chains. When gelatin with a low molecular weight was used, there was no gel‐sol transition, and the structure of water observed by Raman spectroscopy was not significantly affected by the presence of gelatin. When gelatin with a high molecular weight was used, on the other hand, the structure of water strongly depended on the concentration of gelatin both in the gel and the sol state. A contribution of small spaces surrounded by entangled gelatin chains (which exist both in high concentration gels and sols) to the perturbation of the structure of incorporated water was suggested. It was also found that, at 60°C, gelatin chains in the low concentration region induced an enhancement of structured water. This is the first finding that water soluble polymers at high temperature induce the network structure of water.

Rapid separation of DNA sequencing reaction product using capillary electrophoresis.

The effect of the gel composition, electric field strength, and capillary length on the separation of DNA sequencing reaction product was investigated in order to achieve highspeed DNA sequencing on a large-scale for the Human Genome Project. In this study, we prepared gel-filled capillaries differing in gel concentration (3%T6%T), degree of crosslinking (0%C5%C), and capillary length (15.3 cm36.3 cm). Fluorescencelabeled A-termination sequencing reaction product (M13mp 18 template) was first separated by capillary electrophoresis using the gel-filled capillaries prepared here in electric fields from 200 V/cm to 414 V/cm and then detected at 560 nm by using an on-line argon ion laser (488 nm)-induced fluorescence detector. In conclusion, the use of the short capillary, high concentration gel, and high electric field realizes high-speed separation of DNA sequencing reaction product with high resolution. Under optimum separation conditions, only 10 min is required for sequencing of 250-base DNA.

High resolution of honey bee ( Apis mellifera) venom peptides by propionic acid/urea polyacrylamide gel electrophoresis after ethanol precipitation

S. Chettibi and A. Lawrence. High resolution of honey bee ( Apis mellifera) venom peptides by propionic acid/urea polyacrylamide gel electrophoresis after ethanol precipitation. Toxicon 27, 781–787, 1989.—A new and simple gel electrophoretic method is described which enables the protein and polypeptide components of bee venom to be resolved on a single gel. The electrophoretic method allows octapeptides to be resolved and species as small as decapeptides can be detected at high sensitivity using the Coomassie blue staining method without prior fixation. This has been achieved by replacing acetic acid by propionic acid in acid/urea polyacrylamide gels and by controlling the amount of TEMED catalyst for the polymerisation of high concentration gels in order to obtain a low effective pore size. We demonstrated the value of ethanol precipitation as a rapid and efficient desalting the fractionation technique and propose that it could be used in combination with gel filtration to purify many of the peptides to homogeneity.