Gels and gel-derived glasses in the system Na2O-B2O3-SiO2

NASA Technical Reports Server (NTRS)

Mukherjee, S. P.

1983-01-01

The containerless melting of high-purity multicomponent homogeneous gels and gel monoliths offers a unique approach to making ultrapure multicomponent optical glasses in the reduced gravity environment of space. Procedures for preparing and characterizing gels and gel-derived glasses in the system Na2O-B2O3-SiO2 are described. Preparation is based on the polymerization reactions of alkoxysilane with trimethyl borate or boric acid and a suitable sodium compound. The chemistry of the gelling process is discussed in terms of process parameters and the gel compositions. The physicochemical nature of gels prepared by three different procedures was found to be significantly different. Infrared absorption spectra indicate finite differences in the molecular structures of the different gels. The melting of the gel powders and the transformation of porous gel monoliths to transparent 'glass' without melting are described.

Cumulative irritation potential among metronidazole gel 1%, metronidazole gel 0.75%, and azelaic acid gel 15%.

PubMed

Colón, Luz E; Johnson, Lori A; Gottschalk, Ronald W

2007-04-01

Topical therapy for rosacea aims to reduce inflammatory lesions and decrease erythema but can carry side effects such as stinging, pruritus, and burning. Metronidazole and azelaic acid gel 15% are U.S. Food and Drug Administration-approved for the treatment of rosacea. The current study was conducted to assess the cumulative irritation potential of 2 formulations of metronidazole 0.75% gel and 1% gel--and azelaic acid gel 15% over 21 days (N=36). Results of this study demonstrated a significantly greater poten tial for irritation from azelaic acid compared with metronidazole gel 0.75% (P < .0001), which had significantly greater potential for irritation compared with metronidazole gel 1% (P = .0054). Metronidazole gel 1% had a similar profile to white petrolatum.

Nanoemulsion-based gel formulation of diclofenac diethylamine: design, optimization, rheological behavior and in vitro diffusion studies.

PubMed

Hamed, Rania; Basil, Marwa; AlBaraghthi, Tamadur; Sunoqrot, Suhair; Tarawneh, Ola

2016-12-01

Chronic oral administration of the non-steroidal anti-inflammatory drug, diclofenac diethylamine (DDEA), is often associated with gastrointestinal ulcers and bleeding. As an alternative to oral administration, a nanoemulsion-based gel (NE gel) formulation of DDEA was developed for topical administration. An optimized formulation for the o/w nanoemulsion of oil, surfactant and cosurfactant was selected based on nanoemulsion mean droplet size, clarity, stability, and flowability, and incorporated into the gelling agent Carbopol® 971P. Rheological studies of the DDEA NE gel were conducted and compared to those of conventional DDEA gel and emulgel. The three gels exhibited an elastic behavior, where G' dominated G″ at all frequencies, indicating the formation of strong gels. NE gel exhibited higher G' values than conventional gel and emulgel, which indicated the formation of a stronger gel network. Strat-M® membrane, a synthetic membrane with diffusion characteristics that are well correlated to human skin, was used for the in vitro diffusion studies. The release of DDEA from conventional gel, emulgel and NE gel showed a controlled release pattern over 12 h, which was consistent with the rheological properties of the gels. DDEA release kinetics from the three gels followed super case II transport as fitted by Korsmeyer-Peppas model.

Dapsone gel 5% in combination with adapalene gel 0.1%, benzoyl peroxide gel 4% or moisturizer for the treatment of acne vulgaris: a 12-week, randomized, double-blind study.

PubMed

Fleischer, Alan B; Shalita, Alan; Eichenfield, Lawrence F; Abramovits, William; Lucky, Anne; Garrett, Steven

2010-01-01

To evaluate the safety and efficacy of dapsone gel 5% in the treatment of acne when used in combination with adapalene gel 0.1%, benzoyl peroxide gel 4% or moisturizer. This was a twelve-week, randomized, double-blind study. Patients aged 12 years and older (n=301) applied dapsone gel twice daily and were randomly assigned (1:1:1) to one of three additional treatments, applied once daily. By week 12, dapsone gel combined with any of the three additional treatments reduced the mean number of inflammatory lesions. However, the authors did not detect a significant difference in the reduction of inflammatory lesions when dapsone was used in combination with adapalene gel or with benzoyl peroxide gel compared to the dapsone plus moisturizer combination group (P=0.052 for both versus moisturizer combination). Patients treated with dapsone gel combined with adapalene showed a significantly better response in reduction in non-inflammatory and total acne lesion count than those who received the moisturizer combination. Local adverse reactions in all three treatment groups were minimal and generally mild in severity. Dapsone gel in combination with adapalene gel or benzoyl peroxide gel is safe and well tolerated for the treatment of acne vulgaris.

3D gel printing for soft-matter systems innovation

NASA Astrophysics Data System (ADS)

Furukawa, Hidemitsu; Kawakami, Masaru; Gong, Jin; Makino, Masato; Kabir, M. Hasnat; Saito, Azusa

2015-04-01

In the past decade, several high-strength gels have been developed, especially from Japan. These gels are expected to use as a kind of new engineering materials in the fields of industry and medical as substitutes to polyester fibers, which are materials of artificial blood vessels. We consider if various gel materials including such high-strength gels are 3D-printable, many new soft and wet systems will be developed since the most intricate shape gels can be printed regardless of the quite softness and brittleness of gels. Recently we have tried to develop an optical 3D gel printer to realize the free-form formation of gel materials. We named this apparatus Easy Realizer of Soft and Wet Industrial Materials (SWIM-ER). The SWIM-ER will be applied to print bespoke artificial organs, including artificial blood vessels, which will be possibly used for both surgery trainings and actual surgery. The SWIM-ER can print one of the world strongest gels, called Double-Network (DN) gels, by using UV irradiation through an optical fiber. Now we also are developing another type of 3D gel printer for foods, named E-Chef. We believe these new 3D gel printers will broaden the applications of soft-matter gels.

A novel collagen hydrogel cross-linked by gamma-ray irradiation in acidic pH conditions.

PubMed

Inoue, Naoki; Bessho, Masahiko; Furuta, Masakazu; Kojima, Takao; Okuda, Shuichi; Hara, Masayuki

2006-01-01

We made a new type of collagen gel by gamma-ray irradiation of an acidic solution of type-I collagen, and performed comparative studies on a conventional gel and the new type of gel. The neutral gel, a conventional 0.3% (w/v) collagen gel, was formed at neutral pH and then irradiated by gamma-rays. The acidic gel, a 0.3% (w/v) collagen gel, was formed directly from the acidic solution of collagen by y-ray irradiation. Both types of gel were prepared, swollen in water and then dried for the measurement of specific water content. The neutral gel showed a relatively high specific water content and shrunk moderately, depending on the dose, while the acidic gel showed lower specific water content and shrunk clearly by y-ray irradiation. A three-dimensional tangled network of microfibrils was clearly observed in the neutral gels by scanning electron microscopy, but not in the acidic gels. From these results, we concluded that the acidic gel was quite different from a conventional collagen gel. Sodium dodecylsulfate-polyacrylamide gel electrophoresis showed that the alpha1 subunit and alpha2 subunit of the collagen molecule were cross-linked. The triple-helical structure of collagen was only partially perturbed, but not denatured completely, because the circular dichroism spectrum of the collagen solution irradiated at 1.3 kGy was similar to that of native collagen solution. Amino-acid analysis revealed that tyrosine, phenylalanine and histidine decreased by irradiation in the neutral gel. In the case of the acidic gel, these three amino acids and methionine decreased. We considered that these amino acids were cross-linking points between the collagen subunits during the gamma-ray irradiation.

Antimicrobial efficacy of alcohol-based hand gels.

PubMed

Guilhermetti, M; Marques Wiirzler, L A; Castanheira Facio, B; da Silva Furlan, M; Campo Meschial, W; Bronharo Tognim, M C; Botelho Garcia, L; Luiz Cardoso, C

2010-03-01

In recent years, several commercial alcohol-based hand gels have appeared on the market to improve the hand-cleansing compliance of healthcare workers. Although the antimicrobial efficacy of these products has been reported in different countries, few studies have investigated this subject in Brazil. In this study, we assessed the antimicrobial efficacy of 12 alcohol-based hand gels produced in Brazil, containing 70% w/w or v/v ethyl alcohol as the active ingredient, according to the European Standard EN 1500 (EN 1500). The following alcohol gels were tested: Hand Gel, Voga Gel, Solumax Solugel, Doctor Clean, Rio Gel, Clear Gel, Sevengel, Hand CHC, Gel Bac, WBL-50 Gel, Sanigel and Soft Care Gel. In addition, 70% w/w ethyl alcohol and three alcohol-based hand rubs (Sterillium, Sterillium Gel, and Spitaderm), commonly used in Europe and effective according to EN 1500, were also tested. All the products tested, except for two, were approved by the EN 1500 test protocol with a 60s application. The results confirmed the antimicrobial efficacy of the majority of the alcohol gels produced in Brazil for hand hygiene of healthcare workers. Copyright 2009 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.

Gel properties and interactions of Mesona blumes polysaccharide-soy protein isolates mixed gel: The effect of salt addition.

PubMed

Wang, Wenjie; Shen, Mingyue; Liu, Suchen; Jiang, Lian; Song, Qianqian; Xie, Jianhua

2018-07-15

Effect of different salt ions on the gel properties and microstructure of Mesona blumes polysaccharide (MBP)-soy protein isolates (SPI) mixed gels were investigated. Sodium and calcium ions were chosen to explore their effects on the rheological behavior and gel properties of MBP-SPI mixed gels were evaluated by using rheological, X-ray diffraction, protein solubility determination, and microstructure analysis. Results showed that the addition of salt ions change the crystalline state of gels system, the crystal of gel was enhanced at low ion concentrations (0.005-0.01 M). The two peaks of gel characteristic at 8.9° and 19.9° almost disappeared at high salt ions concentrations (0.015-0.02 M), and new crystallization peaks appeared at around 30° and 45°. The elasticity, viscosity, gel strength, water holding capacity, and thermal stability of gel were increased at low ion concentration. Results showed that the main interactions which promoted gel formation and maintain the three-dimensional structure of the gel were electrostatic interactions, hydrophobic interactions, and disulfide interactions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Kinetics of shear-induced gel deswelling/solvent release.

PubMed

Zeo, Undina; Tarabukina, Elena; Budtova, Tatiana

2005-11-02

The kinetics of shear-induced deswelling of gel particles based on synthetic (sodium polyacrylate) and natural (alginate) polymers was studied by rheo-optical technique. A swollen spherical gel particle of 100+/-50 microm diameter was placed in silicone oil and the evolution of the gel size as a function of time and shear rate was monitored. Different aqueous polymer solutions were used as synthetic gel solvent: polyvinylpyrrolidone, hydroxypropyl cellulose and glucose-based polymer. The interfacial tension (gel solvent)/(silicone oil), gel degree of swelling, solvent quality and viscosity are the main parameters influencing the kinetics of shear-induced gel deswelling. The kinetics of gel volume loss was approximated by a modified Weibull equation.

Disintegration kinetics of food gels during gastric digestion and its role on gastric emptying: an in vitro analysis.

PubMed

Guo, Qing; Ye, Aiqian; Lad, Mita; Ferrua, Maria; Dalgleish, Douglas; Singh, Harjinder

2015-03-01

The understanding of the disintegration and gastric emptying of foods in the stomach is important for designing functional foods. In this study, a dynamic stomach model (human gastric simulator, HGS) was employed to investigate the disintegration and subsequent emptying of two differently structured whey protein emulsion gels (soft and hard gels).The gels were mechanically ground into fragments to reproduce the particle size distribution of an in vivo gel bolus. The simulated gel bolus was prepared by mixing gel fragments and artificial saliva, and exposed to 5 hours of simulated gastric digestion in the presence and absence of pepsin. Results showed that regardless of pepsin, the soft gel always disintegrated faster than the hard gel. The presence of pepsin significantly accelerated the disintegration of both gels. In particular, it enhanced abrasion of the soft gel into fine particles (<0.425 mm) after 180 min of processing. The emptying of the gels was influenced by the combined effects of the original particle size of the gel boluses and their disintegration kinetics in the HGS. In the presence or absence of pepsin, the larger particles of the soft gel emptied slower than the hard one during the first 120 min of process. However, in the presence of pepsin, the soft gel emptied faster than the hard one after 120 min because of a higher level of disintegration. These findings highlight the role of food structure, bolus properties and biochemical effects on the disintegration and gastric emptying patterns of gels during gastric digestion.

Lipophilic Super-Absorbent Swelling Gels as Cleaners for Use on Weapons Systems and Platforms

DTIC Science & Technology

2011-08-18

polymer gel systems. Further research will address the post-cleaning gel removal method, the use of non- fluorinated compounds in gel synthesis, and...be proposed to address other issues including the method for removing the gels after swelling, the use of non- fluorinated compounds in gel...strength. Elimination of fluorinated compounds in the gel synthesis was the focus of this and subsequent phases of this research. TECHNICAL APPROACH

Cumulative irritation potential of metronidazole gel compared to azelaic acid gel after repeated applications to healthy skin.

PubMed

Ziel, Kristin; Yelverton, Christopher B; Balkrishnan, Rajesh; Feldman, Steven R

2005-01-01

Metronidazole 0.75% gel and azelaic acid 15% gel are commonly used to treat rosacea. Irritation is a common side effect. To assess the cumulative irritation potential of metronidazole 0.75% gel and azelaic acid 15% gel. Metronidazole 0.75% gel, azelaic acid 15% gel, and a white petrolatum negative control were applied under occlusive conditions to the upper back of a total of 33 healthy subjects. There were twelve 24-hour applications (4 times a week) and three 72-hour applications on weekends during a 3-week period. Skin reactions (erythema score +/- other local reaction) were assessed within 15 to 30 minutes of removal of the products. The mean cumulative irritancy index of metronidazole 0.75% gel was significantly lower than that of azelaic acid 15% gel and not significantly higher than the negative control product. There was increasing cumulative irritancy with azelaic acid; no cumulative irritancy was seen for either metronidazole or white petrolatum. Metronidazole 0.75% gel is less irritating in sustained use than azelaic acid 15% gel.

Gelling Properties of Fish/Pork Mince Mixtures.

PubMed

Liu, Ru; Zhao, Siming; Regenstein, Joe M; Liu, Qing; Yang, Hong; Xiong, Shanbai

2016-02-01

The gel properties of silver carp/pork mince mixtures were investigated as well as the protein structural changes and interactions during gelling using rheology, SEM, and FT-Raman spectroscopy. The breaking force values for gels containing 0% to 40% pork was significantly lower (P < 0.05) compared with gels containing 50% to 100% pork. Gels containing 70% to 100% pork had significantly higher (P < 0.05) breaking force values compared with gels containing 50% to 60% pork. Deformation values were more mixed. Dynamic rheological data suggested that mixing fish and pork at 3:7 could strengthen the gel network. The addition of 40% pork or above, significantly decreased (P < 0.05) the water retention of the gels compared with the 100% fish gels. The dimensional ordering of gels was also reduced by addition of pork. The reduced ordering was one of the reasons for the low water retention for fish/pork mixed gels. Raman spectral analysis confirmed that mixing fish and pork in 7:3 and 3:7 ratios could promote hydrophobic interactions such as bringing tyrosine residues into the intermolecular interface. The interactions in the 3:7 fish/pork mixed gels were favorable for forming a stronger gel. However, the interactions in the 7:3 fish/pork mixed gels were adverse. The water retention of gels was related to both molecular interactions and secondary structures of protein as well as the microstructure of the gels. © 2016 Institute of Food Technologists®

Influence of pre-cooking protein paste gelation conditions and post-cooking gel storage conditions on gel texture.

PubMed

Paker, Ilgin; Matak, Kristen E

2016-01-15

Gelation conditions affect the setting of myofibrillar fish protein gels. Therefore the impact of widely applied pre-cooking gelation time/temperature strategies and post-cooking period on the texture and color of final protein gels was determined. Four pre-cooking gelation strategies (no setting time, 30 min at 25 °C, 1 h at 40 °C or 24 h at 4 °C) were applied to protein pastes (fish protein concentrate and standard functional additives). After cooking, texture and color were analyzed either directly or after 24 h at 4 °C on gels adjusted to 25 °C. No-set gels were harder, gummier and chewier (P < 0.05) when analyzed immediately after cooling; however, gel chewiness, cohesiveness and firmness indicated by Kramer force benefited from 24 h at 4 °C gel setting when stored post-cooking. Gel-setting conditions had a greater (P < 0.05) effect on texture when directly analyzed and most changes occurred in no-set gels. There were significant (P < 0.05) changes between directly analyzed and post-cooking stored gels in texture and color, depending on the pre-cooking gelation strategy. Pre-cooking gelation conditions will affect final protein gel texture and color, with gel stability benefiting from a gel-setting period. However, post-cooking storage may have a greater impact on final gels, with textural attributes becoming more consistent between all samples. © 2015 Society of Chemical Industry.

Brief reports: regional anesthesia needles can introduce ultrasound gel into tissues.

PubMed

Belavy, David

2010-09-01

Anesthesiologists may insert needles through ultrasound gel when performing ultrasound-guided regional anesthesia. In this study, it was determined whether needles carry gel into tissues. Ultrasound gel dyed blue was applied to pork rashers. Tuohy and short-bevel needles were passed through the gel and pork. The needles were then assessed for the presence of ultrasound gel. All needles, including those with stylets, carried gel and tissue within the lumen. Ultrasound gel may be injected around (and perhaps in) nerves during regional anesthesia procedures. Studies are needed to determine the implications of this practice.

The Gel Electrophoresis Markup Language (GelML) from the Proteomics Standards Initiative

PubMed Central

Gibson, Frank; Hoogland, Christine; Martinez-Bartolomé, Salvador; Medina-Aunon, J. Alberto; Albar, Juan Pablo; Babnigg, Gyorgy; Wipat, Anil; Hermjakob, Henning; Almeida, Jonas S; Stanislaus, Romesh; Paton, Norman W; Jones, Andrew R

2011-01-01

The Human Proteome Organisation’s Proteomics Standards Initiative (HUPO-PSI) has developed the GelML data exchange format for representing gel electrophoresis experiments performed in proteomics investigations. The format closely follows the reporting guidelines for gel electrophoresis, which are part of the Minimum Information About a Proteomics Experiment (MIAPE) set of modules. GelML supports the capture of metadata (such as experimental protocols) and data (such as gel images) resulting from gel electrophoresis so that laboratories can be compliant with the MIAPE Gel Electrophoresis guidelines, while allowing such data sets to be exchanged or downloaded from public repositories. The format is sufficiently flexible to capture data from a broad range of experimental processes, and complements other PSI formats for mass spectrometry data and the results of protein and peptide identifications to capture entire gel-based proteome workflows. GelML has resulted from the open standardisation process of PSI consisting of both public consultation and anonymous review of the specifications. PMID:20677327

Epidemic models for phase transitions: application to a physical gel

NASA Astrophysics Data System (ADS)

Bilge, A. H.; Pekcan, O.; Kara, S.; Ogrenci, A. S.

2017-09-01

Carrageenan gels are characterized by reversible sol-gel and gel-sol transitions under cooling and heating processes and these transitions are approximated by generalized logistic growth curves. We express the transitions of carrageenan-water system, as a representative of reversible physical gels, in terms of a modified Susceptible-Infected-Susceptible epidemic model, as opposed to the Susceptible-Infected-Removed model used to represent the (irreversible) chemical gel formation in the previous work. We locate the gel point Tc of sol-gel and gel-sol transitions and we find that, for the sol-gel transition (cooling), Tc > Tsg (transition temperature), i.e. Tc is earlier in time for all carrageenan contents and moves forward in time and gets closer to Tsg as the carrageenan content increases. For the gel-sol transition (heating), Tc is relatively closer to Tgs; it is greater than Tgs, i.e. later in time for low carrageenan contents and moves backward as carrageenan content increases.

Large strain deformation behavior of polymeric gels in shear- and cavitation rheology

NASA Astrophysics Data System (ADS)

Hashemnejad, Seyed Meysam; Kundu, Santanu

Polymeric gels are used in many applications including in biomedical and in food industries. Investigation of mechanical responses of swollen polymer gels and linking that to the polymer chain dynamics are of significant interest. Here, large strain deformation behavior of two different gel systems and with different network architecture will be presented. We consider biologically relevant polysaccharide hydrogels, formed through ionic and covalent crosslinking, and physically associating triblock copolymer gels in a midblock selective solvent. Gels with similar low-strain shear modulus display distinctly different non-linear rheological behavior in large strain shear deformation. Both these gels display strain-stiffening behavior in shear-deformation prior to macroscopic fracture of the network, however, only the alginate gels display negative normal stress. The cavitation rheology data show that the critical pressure for cavitation is higher for alginate gels than that observed for triblock gels. These distinctly different large-strain deformation behavior has been related to the gel network structure, as alginate chains are much stiffer than the triblock polymer chains.

Sol-Gel Glasses

NASA Technical Reports Server (NTRS)

Mukherjee, S. P.

1985-01-01

Multicomponent homogeneous, ultrapure noncrystalline gels/gel derived glasses are promising batch materials for the containerless glass melting experiments in microgravity. Hence, ultrapure, homogeneous gel precursors could be used to: (1) investigate the effect of the container induced nucleation on the glass forming ability of marginally glass forming compositions; and (2) investigate the influence of gravity on the phase separation and coarsening behavior of gel derived glasses in the liquid-liquid immiscibility zone of the nonsilicate systems having a high density phase. The structure and crystallization behavior of gels in the SiO2-GeO2 as a function of gel chemistry and thermal treatment were investigated. As are the chemical principles involved in the distribution of a second network former in silica gel matrix being investigated. The procedures for synthesizing noncrystalline gels/gel-monoliths in the SiO2-GeO2, GeO2-PbO systems were developed. Preliminary investigations on the levitation and thermal treatment of germania silicate gel-monoliths in the Pressure Facility Acoustic Levitator were done.

Electrophoretic extraction of proteins from two-dimensional electrophoresis gel spots

DOEpatents

Zhang, Jian-Shi; Giometti, C.S.; Tollaksen, S.L.

1987-09-04

After two-dimensional electrophoresis of proteins or the like, resulting in a polyacrylamide gel slab having a pattern of protein gel spots thereon, an individual protein gel spot is cored out from the slab, to form a gel spot core which is placed in an extraction tube, with a dialysis membrane across the lower end of the tube. Replicate gel spots can be cored out from replicate gel slabs and placed in the extraction tube. Molten agarose gel is poured into the extraction tube where the agarose gel hardens to form an immobilizing gel, covering the gel spot cores. The upper end portion of the extraction tube is filled with a volume of buffer solution, and the upper end is closed by another dialysis membrane. Upper and lower bodies of a buffer solution are brought into contact with the upper and lower membranes and are provided with electrodes connected to the positive and negative terminals of a dc power supply, thereby producing an electrical current which flows through the upper membrane, the volume of buffer solution, the agarose, the gel spot cores and the lower membrane. The current causes the proteins to be extracted electrophoretically from the gel spot cores, so that the extracted proteins accumulate and are contained in the space between the agarose gel and the upper membrane. 8 figs.

Pharmacodynamic Activity of Dapivirine and Maraviroc Single Entity and Combination Topical Gels for HIV-1 Prevention.

PubMed

Dezzutti, Charlene S; Yandura, Sarah; Wang, Lin; Moncla, Bernard; Teeple, Elizabeth A; Devlin, Brid; Nuttall, Jeremy; Brown, Elizabeth R; Rohan, Lisa C

2015-11-01

Dapivirine (DPV), a non-nucleoside reverse transcriptase inhibitor, and maraviroc (MVC), a CCR5 antagonist, were formulated into aqueous gels designed to prevent mucosal HIV transmission. 0.05% DPV, 0.1% MVC, 0.05% DPV/0.1% MVC and placebo gels were evaluated for pH, viscosity, osmolality, and in vitro release. In vitro assays and mucosal tissues were used to evaluate anti-HIV activity. Viability (Lactobacilli only) and epithelial integrity in cell lines and mucosal tissues defined safety. The gels were acidic and viscous. DPV gel had an osmolality of 893 mOsm/kg while the other gels had an osmolality of <100 mOsm/kg. MVC release was similar from the single and combination gels (~5 μg/cm(2)/min(1/2)), while DPV release was 10-fold less from the single as compared to the combination gel (0.4331 μg/cm(2)/min(1/2)). Titrations of the gels showed 10-fold more drug was needed to protect ectocervical than colonic tissue. The combination gel showed ~10- and 100-fold improved activity as compared to DPV and MVC gel, respectively. All gels were safe. The DPV/MVC gel showed a benefit blocking HIV infection of mucosal tissue compared to the single entity gels. Combination products with drugs affecting unique steps in the viral replication cycle would be advantageous for HIV prevention.

Electrophoretic extraction of proteins from two-dimensional electrophoresis gel spots

DOEpatents

Zhang, Jian-Shi; Giometti, Carol S.; Tollaksen, Sandra L.

1989-01-01

After two-dimensional electrophoresis of proteins or the like, resulting in a polyacrylamide gel slab having a pattern of protein gel spots thereon, an individual protein gel spot is cored out from the slab, to form a gel spot core which is placed in an extraction tube, with a dialysis membrane across the lower end of the tube. Replicate gel spots can be cored out from replicate gel slabs and placed in the extraction tube. Molten agarose gel is poured into the extraction tube where the agarose gel hardens to form an immobilizing gel, covering the gel spot cores. The upper end portion of the extraction tube is filled with a volume of buffer solution, and the upper end is closed by another dialysis membrane. Upper and lower bodies of a buffer solution are brought into contact with the upper and lower membranes and are provided with electrodes connected to the positive and negative terminals of a DC power supply, thereby producing an electrical current which flows through the upper membrane, the volume of buffer solution, the agarose, the gel spot cores and the lower membrane. The current causes the proteins to be extracted electrophoretically from the gel spot cores, so that the extracted proteins accumulate and are contained in the space between the agarose gel and the upper membrane. A high percentage extraction of proteins is achieved. The extracted proteins can be removed and subjected to partial digestion by trypsin or the like, followed by two-dimensional electrophoresis, resulting in a gel slab having a pattern of peptide gel spots which can be cored out and subjected to electrophoretic extraction to extract individual peptides.

Combined transdermal testosterone gel and the progestin nestorone suppresses serum gonadotropins in men.

PubMed

Mahabadi, Vahid; Amory, John K; Swerdloff, Ronald S; Bremner, William J; Page, Stephanie T; Sitruk-Ware, Regine; Christensen, Peter D; Kumar, Narender; Tsong, Yun-Yen; Blithe, Diana; Wang, Christina

2009-07-01

Testosterone (T) plus progestin combinations are the most promising hormonal male contraceptives. Nestorone (NES), a progestin without estrogenic or androgenic activity, when combined with T may be an excellent candidate for male contraception. Our objective was to determine the effect of transdermal NES gel alone or with T gel on gonadotropin suppression. The randomized, unblinded clinical trial was conducted at two academic medical centers. A total of 140 healthy male volunteers participated. One hundred subjects were randomized initially (20 per group) to apply NES gel 2 or 4 mg, T gel 10 g, or T gel 10 g plus NES gel 2 or 4 mg daily for 20 d. Because only about half of the subjects in T plus NES 4 mg group suppressed serum gonadotropins to 0.5 IU/liter or less (suboptimal suppression), two additional groups of 20 men were randomized to apply daily T gel 10 g plus NES gel 6 or 8 mg. Suppression of serum LH and FSH concentrations to 0.5 IU/liter or less after treatment was the main outcome variable. A total of 119 subjects were compliant with gel applications with few study-related adverse events. NES alone reduced gonadotropins significantly but less than T gel alone. Combined T gel 10g plus NES gel 6 or 8 mg suppressed both serum gonadotropins to 0.5 IU/liter or less in significantly more men than either gel alone. Transdermal NES gel alone had gonadotropin suppression activity. Combined transdermal NES (6 or 8 mg) plus T gel demonstrated safe and effective suppression of gonadotropins, justifying a longer-term study of this combination for suppression of spermatogenesis.

Application of melanin-free ink as a new antioxidative gel enhancer in sardine surimi gel.

PubMed

Vate, Naveen Kumar; Benjakul, Soottawat; Agustini, Tri Winarni

2015-08-30

The squid ink that is discarded as waste during processing can be effectively utilised as a gel enhancer in surimi gels, especially those prepared from dark-fleshed fish which have poor gel properties. It also acts as an antioxidant, inhibiting lipid oxidation. This investigation aimed to study the effect of melanin-free ink (MFI) from splendid squid (Loligo formosana) on properties and oxidative stability of surimi gel from sardine (Sardinella albella). MFI (0-0.1 g kg(-1) surimi) increased the breaking force and deformation of sardine surimi gel in a dose-dependent manner (P < 0.05). The addition of MFI had no effect on whiteness of surimi gels (P > 0.05). The expressible moisture content of gels decreased as the levels of MFI increased (P < 0.05). Based on a microstructure study, gel added with MFI at a level of 0.08 g kg(-1) surimi was denser and finer than that of the control (without MFI). Surimi gels with MFI had lower peroxide values, thiobarbituric acid reactive substances, nonanal and 2-decenal. MFI could improve the properties of sardine surimi gel. Additionally, it was able to prevent lipid oxidation in surimi gels during refrigerated storage. © 2014 Society of Chemical Industry.

Thixotropic gel for vadose zone remediation

DOEpatents

Riha, Brian D.

2012-07-03

A thixotropic gel suitable for use in subsurface bioremediation is provided along with a process of using the gel. The thixotropic gel provides a non-migrating injectable substrate that can provide below ground barrier properties. In addition, the gel components provide for a favorable environment in which certain contaminants are preferentially sequestered in the gel and subsequently remediated by either indigenous or introduced microorganisms.

Thixotropic gel for vadose zone remediation

DOEpatents

Rhia, Brian D [Augusta, GA

2011-03-01

A thixotropic gel suitable for use in subsurface bioremediation is provided along with a process of using the gel. The thixotropic gel provides a non-migrating injectable substrate that can provide below ground barrier properties. In addition, the gel components provide for a favorable environment in which certain contaminants are preferentially sequestered in the gel and subsequently remediated by either indigenous or introduced microorganisms.

Thixotropic gel for vadose zone remediation

DOEpatents

Riha, Brian D.; Looney, Brian B.

2015-10-27

A thixotropic gel suitable for use in subsurface bioremediation is provided along with a process of using the gel. The thixotropic gel provides a non-migrating injectable substrate that can provide below ground barrier properties. In addition, the gel components provide for a favorable environment in which certain contaminants are preferentially sequestered in the gel and subsequently remediated by either indigenous or introduced microorganisms.

Development of a direct patterning method for functional oxide thin films using ultraviolet irradiation and hybrid-cluster gels and its application to thin-film transistor fabrication

NASA Astrophysics Data System (ADS)

Yoshimoto, Yuuki; Li, Jinwang; Shimoda, Tatsuya

2018-04-01

A gel state exists in the solution-solid conversion process. We found that solidification can be promoted by irradiating the gel with ultraviolet (UV) light. In this study, a patterning method without using a vacuum system or employing photoresist materials has been proposed wherein solidification was applied to a gel by UV irradiation. Indium oxide gel, indium gallium oxide gel, lanthanum zirconium oxide gel, and lanthanum ruthenium oxide gels were successfully patterned by using our technique. Moreover, an oxide thin-film transistor was fabricated by our novel patterning method and was successfully operated.

Comparative evaluation of the antimicrobial activity of natural extracts of Morinda citrifolia, papain and aloe vera (all in gel formulation), 2% chlorhexidine gel and calcium hydroxide, against Enterococcus faecalis: An in vitro study.

PubMed

Bhardwaj, Anuj; Ballal, Suma; Velmurugan, Natanasabapathy

2012-07-01

A comparative evaluation of the antimicrobial activity of natural extracts of Morinda citrifolia, papain, and aloe vera (all in gel formulations), 2% chlorhexidine gel and calcium hydroxide, against Enterococcus faecalis-an in vitro study. The antimicrobial efficacy was assessed in vitro using dentin shavings collected at 2 depths of 200 and 400 μm. The total colony forming units at the end of 1, 3, and 5 days were assessed. The overall percentage inhibition of bacterial growth (200 and 400 μm depth) was 100% with chlorhexidine gel. This was followed by M. citrifolia gel (86.02%), which showed better antimicrobial efficacy as compared with aloe vera gel (78.9%), papain gel (67.3%), and calcium hydroxide (64.3%). There was no statistical difference between data at 200 and 400 μm depth. Chlorhexidine gel showed the maximum antimicrobial activity against E. faecalis, whereas calcium hydroxide showed the least. Among the natural intracanal medicaments, M. citrifolia gel consistently exhibited good inhibition up to the 5(th) day followed by aloe vera gel and papain gel.

Self-assembling Structures and Sol-Gel Transition of Optically Active and Racemic 12-Hydroxystearic Acids in Organic Solvents

NASA Astrophysics Data System (ADS)

Takeno, Hiroyuki; Mochizuki, Tomomitsu; Yoshiba, Kazuto; Kondo, Shingo; Dobashi, Toshiaki

Self-assembling structures and sol-gel transition in solution of optically active and racemic 12-Hydroxystearic acids (HSA) have been investigated by means of small-angle X-ray scattering (SAXS), differential scanning calorimetry and rheological measurements. Apparently two kinds of gel, transparent gel and turbid gel were obtained in different solvents or by changing concentrations in the same solvent. The melting temperature of the turbid gel is higher than that of the transparent gel. The difference can be qualitatively explained by the dissolution of the crystals (melting point depression) in non-ideal solutions. The SAXS profiles of the transparent gel composed of fibrillar structures have a similar shape at different concentrations, although the intensity is larger for the gels with higher concentrations of 12-HSA. The SAXS analysis reveals that the cross-section of fibrils have square or circular shape (no anisotropic shape) with the radius of gyration 83 Å. On the other hand, for the turbid gel structural inhomnogeneity becomes significant with concentration. The gelation properties and the structures are found to be similar in the racemic HSA gel and the optically active (D-HSA) gel.

Gel performance in rheology and profile control under low-frequency vibration: coupling application of physical and chemical EOR techniques.

PubMed

Zheng, Li Ming; Pu, Chun Sheng; Liu, Jing; Ma, Bo; Khan, Nasir

2017-01-01

Flowing gel plugging and low-frequency vibration oil extraction technology have been widely applied in low-permeability formation. High probability of overlapping in action spheres of two technologies might lead to poor operating efficiency during gel injection. Study on flowing gel rheological properties under low-frequency vibration was essential, which was carried out indoor with viscosity measurement. Potential dynamic mechanisms were analyzed for the rheological variation. Under low-frequency vibration, gel rheological properties were found to be obviously influenced, with vibration delaying gel cross-linking in induction period, causing a two-stage gel viscosity change in acceleration period, and decreasing gel strength in stable period. Surface of gel system under vibration presented different fluctuating phenomenon from initial harmonic vibrating to heterogeneous fluctuating (droplet separation might appear) to final harmonic vibrating again. Dynamic displacement in unconsolidated sand pack revealed that low-frequency vibration during gel injection might be a measure to achieve deep profile control, with the gel injection depth increased by 65.8 % compared with the vibration-free sample. At last, suggestions for field test were given in the paper to achieve lower injection friction and better gel plugging efficiency.

A gel probe equilibrium sampler for measuring arsenic porewater profiles and sorption gradients in sediments: I. Laboratory development

USGS Publications Warehouse

Campbell, K.M.; Root, R.; O'Day, P. A.; Hering, J.G.

2008-01-01

A gel probe equilibrium sampler has been developed to study arsenic (As) geochemistry and sorption behavior in sediment porewater. The gels consist of a hydrated polyacrylamide polymer, which has a 92% water content. Two types of gels were used in this study. Undoped (clear) gels were used to measure concentrations of As and other elements in sediment porewater. The polyacrylamide gel was also doped with hydrous ferric oxide (HFO), an amorphous iron (Fe) oxyhydroxide. When deployed in the field, HFO-doped gels introduce a fresh sorbent into the subsurface thus allowing assessment of in situ sorption. In this study, clear and HFO-doped gels were tested under laboratory conditions to constrain the gel behavior prior to field deployment. Both types of gels were allowed to equilibrate with solutions of varying composition and re-equilibrated in acid for analysis. Clear gels accurately measured solution concentrations (??1%), and As was completely recovered from HFO-doped gels (??4%). Arsenic speciation was determined in clear gels through chromatographic separation of the re-equilibrated solution. For comparison to speciation in solution, mixtures of As(III) and As(V) adsorbed on HFO embedded in gel were measured in situ using X-ray absorption spectroscopy (XAS). Sorption densities for As(III) and As(V) on HFO embedded in gel were obtained from sorption isotherms at pH 7.1. When As and phosphate were simultaneously equilibrated (in up to 50-fold excess of As) with HFO-doped gels, phosphate inhibited As sorption by up to 85% and had a stronger inhibitory effect on As(V) than As(III). Natural organic matter (>200 ppm) decreased As adsorption by up to 50%, and had similar effects on As(V) and As(III). The laboratory results provide a basis for interpreting results obtained by deploying the gel probe in the field and elucidating the mechanisms controlling As partitioning between solid and dissolved phases in the environment. ?? 2008 American Chemical Society.

A comparison of 15% azelaic acid gel and 0.75% metronidazole gel in the topical treatment of papulopustular rosacea: results of a randomized trial.

PubMed

Elewski, Boni E; Fleischer, Alan B; Pariser, David M

2003-11-01

To compare the efficacy and safety of a novel formulation of 15% azelaic acid gel (Finacea; Berlex Laboratories, Inc, Montville, NJ) with 0.75% metronidazole gel (MetroGel; Galderma Laboratories LP, Fort Worth, Tex) as topical therapy for moderate, papulopustular facial rosacea. Multicenter, double-blind, randomized, parallel-group study. Thirteen US centers. A total of 251 patients with papulopustular rosacea with persistent erythema and telangiectasia. Patients were randomized to receive azelaic acid gel or metronidazole gel twice daily for 15 weeks. Nominal and percent change in inflammatory lesion count, change in erythema and telangiectasia severity ratings, investigator's global assessment of rosacea, and investigator's and patient's overall improvement ratings. Azelaic acid gel was superior to metronidazole gel in reduction of mean nominal lesion count (-12.9 vs -10.7, respectively) (P =.003) and mean percent decrease in inflammatory lesions (-72.7% vs -55.8%, respectively) (P<.001). With respect to erythema severity, 56% of azelaic acid gel-treated patients were rated improved vs 42% of metronidazole gel-treated patients (P =.02). The effectiveness of metronidazole gel on these variables seemed to plateau after week 8, whereas azelaic acid gel demonstrated progressive improvement through week 15. Neither treatment had a clinically appreciable effect on telangiectasia. Both the investigator's global assessment (P =.02) and overall assessment of improvement (P =.005) showed a significant therapeutic advantage for azelaic acid gel. Azelaic acid gel also scored higher on the patient's overall assessment of efficacy. Both treatments were rated as having high cosmetic acceptability. No serious or systemic treatment-related adverse events were reported in either group. Use of 15% azelaic acid gel twice daily for 15 weeks demonstrated significant superiority over using 0.75% metronidazole gel in improving principal signs of rosacea (inflammatory lesions and erythema).

Dog erythrocyte antigens 1.1, 1.2, 3, 4, 7, and Dal blood typing and cross-matching by gel column technique.

PubMed

Kessler, Rebecca J; Reese, Jessica; Chang, Denise; Seth, Mayank; Hale, Anne S; Giger, Urs

2010-09-01

Testing for canine blood types other than dog erythrocyte antigen 1.1 (DEA 1.1) is controversial and complicated by reagent availability and methodology. The objectives of this study were to use available gel column technology to develop an extended blood-typing method using polyclonal reagents for DEA 1.1, 1.2, 3, 4, 7, and Dal and to assess the use of gel columns for cross-matching. Dogs (43-75) were typed for DEA 1.1, 1.2, 3, 4, 7, and Dal. METHODS included tube agglutination (Tube) using polyclonal reagents, a commercially available DEA 1.1 gel column test kit (Standard-Gel) using monoclonal reagent, and multiple gel columns (Extended-Gel) using polyclonal reagents. Blood from 10 recipient and 15 donor dogs was typed as described above and cross-matched using the gel column technique. Of 43 dogs typed for DEA 1.1, 23, 25, and 20 dogs were positive using Standard-Gel, Extended-Gel, and Tube, respectively. Typing for DEA 1.2 was not achievable with Extended-Gel. For 75 dogs typed for DEA 3, 4, and 7, concordance of Extended-Gel with Tube was 94.7%, 100%, and 84%, respectively. Dal, determined only by Extended-Gel, was positive for all dogs. Post-transfusion major cross-matches were incompatible in 10 of 14 pairings, but none were associated with demonstrable blood type incompatibilities. Gel column methodology can be adapted for use with polyclonal reagents for detecting DEA 1.1, 3, 4, 7, and Dal. Agglutination reactions are similar between Extended-Gel and Tube, but are more easily interpreted with Extended-Gel. When using gel columns for cross-matching, incompatible blood cross-matches can be detected following sensitization by transfusion, although in this study incompatibilities associated with any tested DEA or Dal antigens were not found. ©2010 American Society for Veterinary Clinical Pathology.

SU-E-T-243: MonteCarlo Simulation Study of Polymer and Radiochromic Gel for Three-Dimensional Proton Dose Distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, M; Jung, H; Kim, G

2014-06-01

Purpose: To estimate the three dimensional dose distributions in a polymer gel and a radiochromic gel by comparing with the virtual water phantom exposed to proton beams by applying Monte Carlo simulation. Methods: The polymer gel dosimeter is the compositeness material of gelatin, methacrylic acid, hydroquinone, tetrakis, and distilled water. The radiochromic gel is PRESAGE product. The densities of polymer and radiochromic gel were 1.040 and 1.0005 g/cm3, respectively. The shape of water phantom was a hexahedron with the size of 13 × 13 × 15 cm3. The proton beam energies of 72 and 116 MeV were used in themore » simulation. Proton beam was directed to the top of the phantom with Z-axis and the shape of beam was quadrangle with 10 × 10 cm2 dimension. The Percent depth dose and the dose distribution were evaluated for estimating the dose distribution of proton particle in two gel dosimeters, and compared with the virtual water phantom. Results: The Bragg-peak for proton particles in two gel dosimeters was similar to the virtual water phantom. Bragg-peak regions of polymer gel, radiochromic gel, and virtual water phantom were represented in the identical region (4.3 cm) for 72 MeV proton beam. For 116 MeV proton beam, the Bragg-peak regions of polymer gel, radiochromic gel, and virtual water phantom were represented in 9.9, 9.9 and 9.7 cm, respectively. The dose distribution of proton particles in polymer gel, radiochromic gel, and virtual water phantom was approximately identical in the case of 72 and 116 MeV energies. The errors for the simulation were under 10%. Conclusion: This work indicates the evaluation of three dimensional dose distributions by exposing proton particles to polymer and radiochromic gel dosimeter by comparing with the water phantom. The polymer gel and the radiochromic gel dosimeter show similar dose distributions for the proton beams.« less

Efficacy and safety of once-daily metronidazole 1% gel compared with twice-daily azelaic acid 15% gel in the treatment of rosacea.

PubMed

Wolf, John E; Kerrouche, Nabil; Arsonnaud, Stephanie

2006-04-01

Rosacea is an inflammatory dermatologic disorder characterized by the presence of facial erythema, visible blood vessels, papules, and pustules. The National Rosacea Society has established a classification system that identifies 4 distinct rosacea subtypes based on clinical presentation: erythematotelangiectatic, papulopustular, phymatous, and ocular. The goal of topical therapy for rosacea is to reduce inflammatory lesion counts; decrease intensity of erythema; and reduce symptoms such as stinging, burning, and pruritus. Metronidazole and azelaic acid are thought to reduce the inflammation associated with rosacea by inhibiting the production of reactive oxygen species produced by neutrophils. Both metronidazole 1% gel and azelaic acid 15% gel recently have been approved for the treatment of rosacea. The current study was conducted to compare the once-daily application of metronidazole 1% gel with twice-daily applications of azelaic acid 15% gel for the treatment of patients with moderate rosacea (N=160). Both treatments showed similar reductions in inflammatory lesion counts (77% for metronidazole 1% gel and 80% for azelaic acid 15% gel) and high success rates in both global severity (53.7% vs 56.4% for metronidazole 1% gel and azelaic acid 15% gel, respectively) and erythema (42.7% vs 42.3% for metronidazole 1% gel and azelaic acid 15% gel, respectively). On average, the efficacy (including reduction in erythema) of the once-daily application of metronidazole 1% gel and twice-daily applications of azelaic acid 15% gel were similar.

Pharmacodynamic activity of Dapivirine and Maraviroc single entity and combination topical gels for HIV-1 prevention

PubMed Central

Dezzutti, Charlene S.; Yandura, Sarah; Wang, Lin; Moncla, Bernard; Teeple, Elizabeth A.; Devlin, Brid; Nuttall, Jeremy; Brown, Elizabeth R.; Rohan, Lisa C.

2015-01-01

Purpose Dapivirine (DPV), a non-nucleoside reverse transcriptase inhibitor, and maraviroc (MVC), a CCR5 antagonist, were formulated into aqueous gels designed to prevent mucosal HIV transmission. Methods 0.05% DPV, 0.1% MVC, 0.05% DPV/0.1% MVC and placebo gels were evaluated for pH, viscosity, osmolality, and in vitro release. In vitro assays and mucosal tissues were used to evaluate anti-HIV activity. Viability (Lactobacilli only) and epithelial integrity in cell lines and mucosal tissues defined safety. Results The gels were acidic and viscous. DPV gel had an osmolality of 893 mOsm/kg while the other gels had an osmolality of <100 mOsm/kg. MVC release was similar from the single and combination gels (~5 μg/cm2/min1/2), while DPV release was 10-fold less from the single as compared to the combination gel (0.4331 μg/cm2/min1/2). Titrations of the gels showed 10-fold more drug was needed to protect ectocervical than colonic tissue. The combination gel showed ~10- and 100-fold improved activity as compared to DPV and MVC gel, respectively. All gels were safe. Conclusions The DPV/MVC gel showed a benefit blocking HIV infection of mucosal tissue compared to the single entity gels. Combination products with drugs affecting unique steps in the viral replication cycle would be advantageous for HIV prevention. PMID:26078001

Thermosensitive In Situ Gel Based on Solid Dispersion for Rectal Delivery of Ibuprofen.

PubMed

Liu, Yangdan; Wang, Xin; Liu, Youping; Di, Xin

2018-01-01

The objective of this study was to develop a thermosensitive in situ gel based on solid dispersions (SDs) for rectal delivery of ibuprofen (IBU). Thermosensitive (poloxamer 407) and mucoadhesive (hydroxypropylmethyl cellulose E5 and sodium alginate) polymers were used to prepare the in situ gel and the sol-gel transition temperature (T sol-gel ) and gel strength were optimized. The in vitro release performance and in vivo pharmacokinetic properties of the in situ gel after their rectal administration to rabbits were investigated. Compared with the solid suppository, the cumulative release of the IBU SDs loaded in situ gel was significantly increased. The in vivo pharmacokinetics indicated that in situ gel had a higher peak plasma concentration (C max ) and area under the curve (AUC (0-∞) ) in plasma than the solid suppositories. Histopathology results showed that the IBU in situ gel given at a dose of 15 mg/kg did not produce any irritation. In conclusion, this study suggested that the in situ gel could be an effective rectal formulation for IBU.

Is instillation of anesthetic gel necessary in flexible cystoscopic examination? A prospective randomized study.

PubMed

Kobayashi, Takashi; Nishizawa, Koji; Ogura, Keiji

2003-01-01

To determine whether urethral injection of anesthetic and lubricating agent before outpatient flexible cystoscopic examination is worthwhile regarding patient tolerance of pain. A randomized prospective study was conducted. A total of 133 consecutive men scheduled to undergo flexible cystoscopy were randomized to receive 11 mL of 0.2% oxybuprocaine hydrochloride gel (group 1), 11 mL of plain lubricating gel (group 2), or no gel injection (group 3). In every group, 2% lidocaine gel was applied to the fiberscope. Patients recorded the level of pain during gel instillation, scope insertion, and intravesical observation separately on a 100-mm visual analog self-assessment scale. Pain scores for gel instillation were approximately two thirds those for scope insertion and intravesical observation in groups 1 and 2. No significant difference was noted in the pain score of each group during either scope insertion or intravesical observation. Pain during intraurethral gel instillation is significant. Anesthetic gel instillation has no advantage compared with no-gel injection in men when lubricating gel is applied to a flexible fiberscope.

[Mechanoelectric potentials in synthetic hydrogels: possible relation to cytoskeleton].

PubMed

Shkliar, T F; Safronov, A P; Toropova, O A; Pollack, G N; Bliakhman, F A

2010-01-01

Mechanical and electrical properties of a synthetic polyelectrolyte hydrogel considered as a model of the cytoskeletal gel were studied. Hydrogels were synthesized from polymethacrylic acid by radical polymerization in aqueous solution. The electrical charge was introduced into the gel network by partial neutralization of monomer acids with magnesium (hydro)oxides. Through the use of a motor, triangular longitudinal (axial) deformations were applied to gel samples. Simultaneously, the electrochemical (Donnan) potential of the gel was measured using conventional microelectrodes. We found that: (1) the Young modulus of the gel was 0.53 kPa; (2) at a given deformation velocity, the extent of gel deformation closely correlates with the gel potential; and (3) at the same level of gel deformation, the lower the deformation velocity, the higher the relative change of gel potential. These findings show a striking similarity to the data obtained in living cells, particularly in cardiac myocytes. A hypothesis involving the deformation-induced solvent migration from the gel to the surrounding solution is considered. It is concluded that the physicochemical features of the cytoskeletal gel may play a role in determining the mechanoelectric properties of excited cells.

SU-F-T-159: Monte Carlo Simulation Studies of Three-Dimensional Dose Distribution for Polymer Gel Dosimeter and Radiochromic Gel Dosimeter in a Proton Beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, M; Kim, G; Jung, H

Purpose: The purpose of this simulation study is to evaluate the proton detectability of gel dosimeters, and estimate the three-dimensional dose distribution of protons in the radiochromic gel and polymer gel dosimeter compared with the dose distribution in water. Methods: The commercial composition ratios of normoxic polymer gel and LCV micelle radiochromic gel were included in this simulation study. The densities of polymer and radiochromic gel were 1.024 and 1.005 g/cm3, respectively. The 50, 80 and 140 MeV proton beam energies were selected. The dose distributions of protons in the polymer and radiochromic gel were simulated using Monte Carlo radiationmore » transport code (MCNPX 2.7.0, Los Alamos Laboratory). The water equivalent depth profiles and the dose distributions of two gel dosimeters were compared for the water. Results: In case of irradiating 50, 80 and 140 MeV proton beam to water phantom, the reference Bragg-peak depths are represented at 2.22, 5.18 and 13.98 cm, respectively. The difference in the water equivalent depth is represented to about 0.17 and 0.37 cm in the radiochromic gel and polymer gel dosimeter, respectively. The proton absorbed doses in the radiochromic gel dosimeter are calculated to 2.41, 3.92 and 6.90 Gy with increment of incident proton energies. In the polymer gel dosimeter, the absorbed doses are calculated to 2.37, 3.85 and 6.78 Gy with increment of incident proton energies. The relative absorbed dose in radiochromic gel (about 0.47 %) is similar to that of water than the relative absorbed dose of polymer gel (about 2.26 %). In evaluating the proton dose distribution, we found that the dose distribution of both gel dosimeters matched that of water in most cases. Conclusion: As the dosimetry device, the radiochromic gel dosimeter has the potential particle detectability and is feasible to use for quality assurance of proton beam therapy beam.« less

Synthesis and Characterization of Types A and B Gelatin Methacryloyl for Bioink Applications

PubMed Central

Lee, Bae Hoon; Lum, Nathaniel; Seow, Li Yuan; Lim, Pei Qi; Tan, Lay Poh

2016-01-01

Gelatin methacryloyl (GelMA) has been increasingly considered as an important bioink material due to its tailorable mechanical properties, good biocompatibility, and ability to be photopolymerized in situ as well as printability. GelMA can be classified into two types: type A GelMA (a product from acid treatment) and type B GelMA (a product from alkali treatment). In current literature, there is little research on the comparison of type A GelMA and type B GelMA in terms of synthesis, rheological properties, and printability for bioink applications. Here, we report the synthesis, rheological properties, and printability of types A and B GelMA. Types A and B GelMA samples with different degrees of substitution (DS) were prepared in a controllable manner by a time-lapse loading method of methacrylic anhydride (MAA) and different feed ratios of MAA to gelatin. Type B GelMA tended to have a slightly higher DS compared to type A GelMA, especially in a lower feed ratio of MAA to gelatin. All the type A and type B GelMA solutions with different DS exhibited shear thinning behaviours at 37 °C. However, only GelMA with a high DS had an easy-to-extrude feature at room temperature. The cell-laden printed constructs of types A and B GelMA at 20% w/v showed around 75% cell viability. PMID:28773918

Internal structure analysis of particle-double network gels used in a gel organ replica

NASA Astrophysics Data System (ADS)

Abe, Mei; Arai, Masanori; Saito, Azusa; Sakai, Kazuyuki; Kawakami, Masaru; Furukawa, Hidemitsu

2016-04-01

In recent years, the fabrication of patient organ replicas using 3D printers has been attracting a great deal of attention in medical fields. However, the cost of these organ replicas is very high as it is necessary to employ very expensive 3D printers and printing materials. Here we present a new gel organ replica, of human kidney, fabricated with a conventional molding technique, using a particle-double network hydrogel (P-DN gel). The replica is transparent and has the feel of a real kidney. It is expected that gel organ replicas produced this way will be a useful tool for the education of trainee surgeons and clinical ultrasonography technologists. In addition to developing a gel organ replica, the internal structure of the P-DN gel used is also discussed. Because the P-DN gel has a complex structure comprised of two different types of network, it has not been possible to investigate them internally in detail. Gels have an inhomogeneous network structure. If it is able to get a more uniform structure, it is considered that this would lead to higher strength in the gel. In the present study we investigate the structure of P-DN gel, using the gel organ replica. We investigated the internal structure of P-DN gel using Scanning Microscopic Light Scattering (SMILS), a non-contacting and non-destructive.

Electrophoresis of DNA in agarose gels, polyacrylamide gels and in free solution

PubMed Central

Stellwagen, Nancy C.

2009-01-01

This review describes the electrophoresis of curved and normal DNA molecules in agarose gels, polyacrylamide gels and in free solution. These studies were undertaken to clarify why curved DNA molecules migrate anomalously slowly in polyacrylamide gels but not in agarose gels. Two milestone papers are cited, in which Ferguson plots were used to estimate the effective pore size of agarose and polyacrylamide gels. Subsequent studies on the effect of the electric field on agarose and polyacrylamide gel matrices, DNA interactions with the two gel matrices, and the effect of curvature on the free solution mobility of DNA are also described. The combined results suggest that the anomalously slow mobilities observed for curved DNA molecules in polyacrylamide gels are due primarily to preferential interactions of curved DNAs with the polyacrylamide gel matrix; the restrictive pore size of the matrix is of lesser importance. In free solution, DNA mobilities increase with increasing molecular mass until leveling off at a plateau value of (3.17 ± 0.01) × 10-4 cm2/Vs in 40 mM Tris-acetate-EDTA buffer at 20°C. Curved DNA molecules migrate anomalously slowly in free solution as well as in polyacrylamide gels, explaining why the Ferguson plots of curved and normal DNAs containing the same number of base pairs extrapolate to different mobilities at zero gel concentration. PMID:19517510

Autologous Platelet-Poor Plasma Gel for Injection Laryngoplasty

PubMed Central

Woo, Seung Hoon; Kim, Jin Pyeong; Park, Jung Je; Chung, Phil-Sang

2013-01-01

Purpose To overcome the potential disadvantages of the use of foreign materials and autologous fat or collagen, we introduce here an autologous plasma gel for injection laryngoplasty. The purpose of this study was to present a new injection material, a plasma gel, and to discuss its clinical effectiveness. Materials and Methods From 2 mL of blood, the platelet poor serum layer was collected and heated at 100℃ for 12 min to form a plasma gel. The plasma gel was then injected into a targeted site; the safety and efficacy thereof were evaluated in 30 rats. We also conducted a phase I/II clinical study of plasma gel injection laryngoplasty in 11 unilateral vocal fold paralysis patients. Results The plasma gel was semi-solid and an easily injectable material. Of note, plasma gel maintains the same consistency for up to 1 year in a sealed bottle. However, exposure to room air causes the plasma gel to disappear within 1 month. In our animal study, the autologous plasma gel remained in situ for 6 months in animals with minimal inflammation. Clinical study showed that vocal cord palsy was well compensated for with the plasma gel in all patients at two months after injection with no significant complications. Jitter, shimmer, maximum, maximum phonation time (MPT) and mean voice handicap index (VHI) also improved significantly after plasma gel injection. However, because the injected plasma gel was gradually absorbed, 6 patients needed another injection, while the gel remained in place in 2 patients. Conclusion Injection laryngoplasty with autologous plasma gel may be a useful and safe treatment option for temporary vocal cord palsy. PMID:24142660

Engineered Fibrin Gels for Parallel Stimulation of Mesenchymal Stem Cell Proangiogenic and Osteogenic Potential

PubMed Central

Murphy, Kaitlin C.; Hughbanks, Marissa L.; Binder, Bernard Y.K.; Vissers, Caroline B.; Leach, J. Kent

2014-01-01

Mesenchymal stem/stromal cells (MSCs) are under examination for use in cell therapies to repair bone defects resulting from trauma or disease. MSCs secrete proangiogenic cues and can be induced to differentiate into bone-forming osteoblasts, yet there is limited evidence that these events can be achieved in parallel. Manipulation of the cell delivery vehicle properties represents a candidate approach for directing MSC function in bone healing. We hypothesized that the biophysical properties of a fibrin gel could simultaneously regulate the proangiogenic and osteogenic potential of entrapped MSCs. Fibrin gels were formed by supplementation with NaCl (1.2, 2.3, and 3.9% w/v) to modulate gel biophysical properties without altering protein concentrations. MSCs entrapped in 1.2% w/v NaCl gels were the most proangiogenic in vitro, yet cells in 3.9% w/v gels exhibited the greatest osteogenic response. Compared to the other groups, MSCs entrapped in 2.3% w/v gels provided the best balance between proangiogenic potential, osteogenic potential, and gel contractility. The contribution of MSCs to bone repair was then examined when deployed in 2.3% w/v NaCl gels and implanted into an irradiated orthotopic bone defect. Compared to acellular gels after 3 weeks of implantation, defects treated with MSC-loaded fibrin gels exhibited significant increases in vessel density, early osteogenesis, superior morphology, and increased cellularity of repair tissue. Defects treated with MSC-loaded gels exhibited increased bone formation after 12 weeks compared to blank gels. These results confirm that fibrin gel properties can be modulated to simultaneously promote both the proangiogenic and osteogenic potential of MSCs, and fibrin gels modified by supplementation with NaCl are promising carriers for MSCs to stimulate bone repair in vivo. PMID:25527322

Dynamic and static fluctuations in polymer gels studied by neutron spin-echo

NASA Astrophysics Data System (ADS)

Kanaya, T.; Takahashi, N.; Nishida, K.; Seto, H.; Nagao, M.; Takeba, Y.

2006-11-01

We report neutron spin-echo measurements on three types of poly(vinyl alcohol) (PVA) gels. The first is PVA gel in a mixture of dimethyl sulfoxide (DMSO) and water with volume ratio 60/40, the second is PVA gel in an aqueous borax solution and the third is chemically cross-linked PVA gel. The observed normalized intermediate scattering functions I( Q, t)/ I( Q,0) were very different among them. The I( Q, t)/ I( Q,0) of the first and third gels showed a non-decaying component in addition to a decaying component, but the second one did not have the non-decaying one. This clearly indicates that the fluctuations in the first and third PVA gels consist of static and dynamic fluctuations whereas the second PVA gel does include only the dynamic fluctuations. The dynamic and static fluctuations of the PVA gels were analyzed in terms of a restricted motion in the gel network and the Zimm motion, respectively.

Comparative evaluation of the antimicrobial activity of natural extracts of Morinda citrifolia, papain and aloe vera (all in gel formulation), 2% chlorhexidine gel and calcium hydroxide, against Enterococcus faecalis: An in vitro study

PubMed Central

Bhardwaj, Anuj; Ballal, Suma; Velmurugan, Natanasabapathy

2012-01-01

Aim: A comparative evaluation of the antimicrobial activity of natural extracts of Morinda citrifolia, papain, and aloe vera (all in gel formulations), 2% chlorhexidine gel and calcium hydroxide, against Enterococcus faecalis—an in vitro study. Materials and Methods: The antimicrobial efficacy was assessed in vitro using dentin shavings collected at 2 depths of 200 and 400 μm. The total colony forming units at the end of 1, 3, and 5 days were assessed. Results: The overall percentage inhibition of bacterial growth (200 and 400 μm depth) was 100% with chlorhexidine gel. This was followed by M. citrifolia gel (86.02%), which showed better antimicrobial efficacy as compared with aloe vera gel (78.9%), papain gel (67.3%), and calcium hydroxide (64.3%). There was no statistical difference between data at 200 and 400 μm depth. Conclusion: Chlorhexidine gel showed the maximum antimicrobial activity against E. faecalis, whereas calcium hydroxide showed the least. Among the natural intracanal medicaments, M. citrifolia gel consistently exhibited good inhibition up to the 5th day followed by aloe vera gel and papain gel. PMID:22876022

Enzymatically Cross-linked Alginic-Hyaluronic acid Composite Hydrogels As Cell Delivery Vehicles

PubMed Central

Ganesh, Nitya; Hanna, Craig; Nair, Shantikumar V.; Nair, Lakshmi S.

2013-01-01

An injectable composite gel was developed from alginic and hyaluronic acid. The ezymatically cross-linked injectable gels were prepared via the oxidative coupling of tyramine modified sodium algiante and sodium hyaluronate in the presence of horse radish peroxidase (HRP) and hydrogen peroxide (H2O2). The composite gels were prepared by mixing equal parts of the two tryaminated polymer solutions in 10U HRP and treating with 1.0% H2O2. The properties of the alginate gels were significanly affected by the addition of hyaluronic acid. The percentage water absorption and storage modulus of the composite gels were found to be lower than the alginate gels. The alginate and composite gels showed lower protein release compared to hyaluronate gels in the absence of hyaluronidase. Even hyaluronate gels showed only approximately 10% protein release after 14 days incubation in phosphate buffer solution. ATDC-5 cells encapsulated in the injectable gels showed high cell viability. The composite gels showed the presence of enlarged spherical cells with significantly higher metabolic activity compared to cells in hyaluronic and alginic acid gels. The results suggest the potential of the composite approach to develop covalently cross-linked hydrogels with tuneable physical, mechanical, and biological properties. PMID:23357799

Coupled gel spreading and diffusive transport models describing microbicidal drug delivery

NASA Astrophysics Data System (ADS)

Funke, Claire; MacMillan, Kelsey; Ham, Anthony S.; Szeri, Andrew J.; Katz, David F.

2016-11-01

Gels are a drug delivery platform being evaluated for application of active pharmaceutical ingredients, termed microbicides, that act topically against infection by sexually transmitted HIV. Despite success in one Phase IIb trial of a vaginal gel delivering tenofovir, problems of user adherence to designed gel application regimen compromised results in two other trials. The microbicide field is responding to this issue by simultaneously analyzing behavioral determinants of adherence and pharmacological determinants of drug delivery. Central to both user adherence and mucosal drug delivery are gel properties (e.g. rheology) and applied volume. The specific problem to be solved here is to develop a model for how gel rheology and volume, interacting with loaded drug concentration, govern the transport of the microbicide drug tenofovir into the vaginal mucosa to its stromal layer. The analysis here builds upon our current understanding of vaginal gel deployment and drug delivery, incorporating key features of the gel's environment, fluid production and subsequent gel dilution, and vaginal wall elasticity. We consider the microbicide drug tenofovir as it is the most completely studied drug, in both in vitroand in vivostudies, for use in vaginal gel application. Our goal is to contribute to improved pharmacological understanding of gel functionality, providing a computational tool that can be used in future vaginal microbicide gel design.

Metal ion promoted hydrogels for bovine serum albumin adsorption: Cu(II) and Co(II) chelated poly[(N-vinylimidazole)-maleic acid].

PubMed

Pekel, Nursel; Salih, Bekir; Güven, Olgun

2005-05-10

Poly[(N-vinylimidazole)-maleic acid] (poly(VIm-MA)), copolymeric hydrogels were prepared by gamma-irradiating ternary mixtures of N-vinylimidazole-maleic acid-water in a (60)Co-gamma source. Cu(II) and Co(II) ions were chelated within the gels at pH=5.0. The maximum adsorption capacity of the gels were 3.71 mmol/g dry gel for Cu(II) and 1.25 mmol/g dry gel for Co(II) at pH=5.0. The swelling ratios of the gels were 1200% for poly(VIm-MA), 60 and 45% for Cu(II) and Co(II)-chelated poly(VIm-MA) gels at pH=5.0 in acetate buffer solution. These affinity gels with different swelling ratios for plain poly(VIm-MA), Cu(II)-, and Co(II)-chelated poly(VIm-MA), in acetate and phosphate buffers were used in the bovine serum albumin (BSA) adsorption/desorption studies in batch reactor. The maximum BSA adsorption capacities of the gels were 0.38 g/g dry gel for plain, 0.88 g/g dry gel for Cu(II)-chelated poly(VIm-MA) and 1.05 g/g dry gel for Co(II)-chelated poly(VIm-MA) gels. Adsorption capacity of BSA by the gels was reduced dramatically by increasing the ionic strength adjusted with NaCl. More than 95% of BSA were desorbed in 10 h in desorption medium containing 0.1M of EDTA for metal ion-chelated gels at pH=4.7.

3D printing of soft-matter to open a new era of soft-matter MEMS/robotics (Conference Presentation)

NASA Astrophysics Data System (ADS)

Furukawa, Hidemitsu

2017-04-01

3D printing technology is becoming useful and applicable by the progress of information and communication technology (ICT). It means 3D printer is a kind of useful robot for additive manufacturing and is controlled by computer with human-friendly software. Once user starts to use 3D printing of soft-matter, one can immediately understand computer-aided design (CAD) and engineering (CAE) technology will be more important and applicable for soft-matter systems. User can easily design soft-matter objects and 3D-print them. User can easily apply 3D-printed soft-matter objects to develop new research and application on MEMS and robotics. Here we introduce the recent progress of 3D printing (i.e. additive manufacturing), especially focusing on our 3D gel printing. We are trying to develop new advanced research and applications of 3D gel printer, including GEL-MECHANICS, GEL-PHOTONICS, and GEL-ROBOTICS. In the gel-mechanics, we are developing new gel materials for mechanical engineering. Some gels have high-mechanical strength and shape memory properties. In the gel-photonics. We are applying our original characterizing system, named `Scanning Microscopic Light Scattering (SMILS)', to analyze 3D printed gel materials. In the gel-robotics, we focus on 3D printing of soft parts for soft-robotics made form gel materials, like gel finger. Also we are challenging to apply 3D gel printing to start new company, to innovate new businesses in county side, and to create new 3D-printed foods.

Capillary pressure as related to water holding in polyacrylamide and chicken protein gels.

PubMed

Stevenson, Clinton D; Dykstra, Michael J; Lanier, Tyre C

2013-02-01

The ability of food gels to hold water affects product yield and organoleptic quality. Most researchers believe that water is held by capillarity such that gels having smaller mean pore diameter and a more hydrophilic surface hold water more tightly. To date, however, only qualitative evidence relating pore size to water holding (WH) properties has been provided. The present study sought to provide quantitative confirmation of this hypothesis. Scanning electron microscopy coupled with image analysis was used to measure pore size, and water contact angle with the gel surface was measured by the captive bubble method, in both model polyacrylamide gels and heat-induced protein (minced chicken breast) gels. These were related to water lost during cooking of meat pastes to form gels (cooking loss (CL)), as well as water lost upon centrifugation (expressible water (EW)) or by capillary suction (CSL) of all prepared gels, as inverse measures of WH. As predicted by the Young-Laplace equation for calculating capillary pressure, the presumed mechanism of WH, gels with lower water losses exhibited a more hydrophilic surface (smaller contact angle). Yet, both lower CL and CSL correlated with larger mean pore diameter of gels, not smaller as had been expected. Polyacrylamide gels varied more in WH than did prepared meat gels, yet only the capillary suction method was sensitive enough to detect these differences.  The ability of gels to hold water is important for economics of processing, food quality, and food safety. This study investigated the prevailing theory for how gels hold water, capillarity. Both the pore sizes of gel microstructures and the degree of hydrophilicity of the polymers comprising each gel were quantitatively assessed and related to water holding (WH) properties, and this was the first report using such methodologies. It appeared that the degree of hydrophilicity was much more important explaining WH properties than pore size, and that future research of this kind should be carried out. © 2013 Institute of Food Technologists®

Dosimetric characteristics of PASSAG as a new polymer gel dosimeter with negligible toxicity

NASA Astrophysics Data System (ADS)

Farhood, Bagher; Abtahi, Seyed Mohammad Mahdi; Geraily, Ghazale; Ghorbani, Mehdi; Mahdavi, Seied Rabi; Zahmatkesh, Mohammad Hasan

2018-06-01

Despite many advantages of polymer gel dosimeters, their clinical use is only not realized now. Toxicity of polymer gel dosimeters can be considered as one of their main limitations for use in routine clinical applications. In the current study, a new polymer gel dosimeter is introduced with negligible toxicity. For this purpose, 2-Acrylamido-2-Methy-1-PropaneSulfonic acid (AMPS) sodium salt monomer was replaced instead of acrylamide monomer used in PAGAT gel dosimeter by using %6 T and %50 C to the gel formula and the new formulation is called PASSAG (Poly AMPS Sodium Salt and Gelatin) polymer gel dosimeter. The irradiation of gel dosimeters was carried out using a Co-60 therapy machine. MRI technique was used to quantify the dose responses of the PASSAG gel dosimeter. Then, the MRI responses (R2) of the gel dosimeter was analyzed at different dose values, post-irradiation times, and scanning temperatures. The results showed that the new gel formulation has a negligible toxicity and it is also eco-friendly. In addition, carcinogenicity and genetic toxicity tests are negative for the monomer used in PASSAG. The radiological properties of PASSAG gel dosimeter showed that this substance can be considered as a soft tissue/water equivalent material. Furthermore, dosimetric evaluation of the new polymer gel dosimeter revealed an excellent linear R2-dose response in the evaluated dose range (0-15 Gy). The R2-dose sensitivity and dose resolution of PASSAG gel dosimeter were 0.081 s-1Gy-1 (in 0-15 Gy dose range) and 1 Gy (in 0-10 Gy dose range), respectively. Moreover, it was shown that the R2-dose sensitivity and dose resolution of the new gel dosimeter improves over time after irradiation. It was also found that the R2 response of the PASSAG gel dosimeter has less dependency to the 18, 20, and 24 °C scanning temperature in comparison to that of room temperature (22 °C).

Effect of Sol Concentration, Aging and Drying Process on Cerium Stabilization Zirconium Gel Produced by External Gelation

NASA Astrophysics Data System (ADS)

Sukarsono, R.; Rachmawati, M.; Susilowati, S. R.; Husnurrofiq, D.; Nurwidyaningrum, K.; Dewi, A. K.

2018-02-01

Cerium Stabilized Zirconium gel has been prepared using external gelation process. As the raw materials was used ZrO(NO3)2 and Ce(NO3)4 nitrate salt which was dissolved with water into Zr-Ce nitrate mixture. The concentration of the nitrate salt mixture in the sol solution was varied by varying the concentration of zirconium and cerium nitrate in the sol solution and the addition of PVA and THFA to produce a sol with a viscosity of 40-60 cP. The viscosity range of 40-60cP is the viscosity of the sol solution that was easy to produce a good gel in the gelation apparatus. Sol solution was casted in a gelation column equipped with following tools: a 1 mm diameter drip nozzle which was vibrated to adjust the best frequency and amplitude of vibration, a flow meter to measure the flow rate of sol, flowing of NH3 gas to presolidification process. Gelation column was contained NH4OH solution as gelation medium and gel container to collect gel product. Gel obtained from the gelation process than processed with ageing, washing, drying and calcinations to get round gel and not broken at calcinations up to 500°C. The parameters observed in this research are variation of Zr nitrate concentration, Ce nitrate concentration, ratio of Zr and Ce in the sol and ageing and drying process method which was appropriate to get a good gel. From the gelation processes that has been done, it can be seen that with the presolidification process can be obtained a round gel and without presolidification process, produce not round gel. In the process of ageing to get not broken gel, ageing was done on the rotary flask so that during the ageing, gels rotate in gelation media. Gels, then be washed by dilute ammonium nitrate, demireralized water and iso prophyl alcohol. The washed gel was then dried by vacuum drying to form pores on the gel which become the path for the gases resulting from decomposition of the gel to exit the gel. Vacuum drying can prevent cracking because the pores allow the gel to release the decomposition of the material during heating. Larger the concentration of nitric metal in sol solution, yields a gel with a larger diameter of gels. This research allows us to plan the diameter of the sintered particles to be made.

[Overdentures covering natural roots. The use of chlorhexidine gel].

PubMed

Hendrikx, M J; Kramer, J E; de Baat, C

2000-03-01

To prevent caries and periodontal disease in overdenture abutment teeth, daily application of chlorhexidine gel is recommended. In order to get insight into the use of the gel, 29 overdenture wearing patients were interviewed. In addition the patients were requested to show the use of the gel. It was concluded that at any time the patients were instructed about the use of the gel. Nevertheless, a majority of the patients did not use the gel daily and in accordance with the instructions given. Application of the gel in the abutment depressions of the overdenture appeared to be a heavy task.

Organization versus frustration: low temperature transitions in a gelatine-based gel

NASA Astrophysics Data System (ADS)

Philipp, M.; Müller, U.; Sanctuary, R.; Baller, J.; Krüger, J. K.

2008-09-01

A commercial physical gel composed of gelatine, water and glycerol shows a sol-gel transition which has been resolved by optical rotation measurements by step-wise heating the gel. This transition is not observable in the longitudinal acoustic mode measured at hypersonic frequencies with Brillouin spectroscopy. Depending on the thermal treatment of the investigated material during the sol-gel transition and within the gel state, Brillouin spectroscopy reflects tremendously different hypersonic dynamics. These distinct dynamics are responsible for the formation of different glassy states at low temperatures including that of a glass-ceramic. The large variety of super-cooled and glassy states is attributed to distinct distributions of the gel's constituents within the samples. Surprisingly, the same gel state can be produced either by annealing the gel over months or by the non-equilibrium effect of thermo-diffusion (Soret effect) in the course of some minutes.

Effects of oxidative modification on thermal aggregation and gel properties of soy protein by malondialdehyde.

PubMed

Wu, Wei; Hua, Yufei; Lin, Qinlu

2014-03-01

Malondialdehyde (MDA) was selected as a representative of lipid peroxidation products to investigate the effects of oxidative modification on thermal aggregation and gel properties of soy protein by lipid peroxidation products. Incubation of soy protein with increasing concentration of MDA resulted in gradual decrease of particle size and content of thermal aggregates during heat denaturation. Oxidative modification by MDA resulted in a decrease in water holding capacity, gel hardness, and gel strength of soy protein gel. An increase in coarseness and interstice of MDA modified protein gel network was accompanied by uneven distribution of interstice as MDA concentration increased. The results showed that degree of thermal aggregation of MDA-modified soy protein gradually decreased as MDA concentration increased, which contributed to a decrease in water holding capacity, gel hardness, and gel strength of MDA-modified soy protein gel.

Spongy Gels by a Top-Down Approach from Polymer Fibrous Sponges.

PubMed

Jiang, Shaohua; Duan, Gaigai; Kuhn, Ute; Mörl, Michaela; Altstädt, Volker; Yarin, Alexander L; Greiner, Andreas

2017-03-13

Ultralight cellular sponges offer a unique set of properties. We show here that solvent uptake by these sponges results in new gel-like materials, which we term spongy gels. The appearance of the spongy gels is very similar to classic organogels. Usually, organogels are formed by a bottom-up process. In contrast, the spongy gels are formed by a top-down approach that offers numerous advantages for the design of their properties, reproducibility, and stability. The sponges themselves represent the scaffold of a gel that could be filled with a solvent, and thereby form a mechanically stable gel-like material. The spongy gels are independent of a time-consuming or otherwise demanding in situ scaffold formation. As solvent evaporation from gels is a concern for various applications, we also studied solvent evaporation of wetting and non-wetting liquids dispersed in the sponge. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Metal-silica sol-gel materials

NASA Technical Reports Server (NTRS)

Stiegman, Albert E. (Inventor)

2002-01-01

The present invention relates to a single phase metal-silica sol-gel glass formed by the co-condensation of a transition metal with silicon atoms where the metal atoms are uniformly distributed within the sol-gel glass as individual metal centers. Any transition metal may be used in the sol-gel glasses. The present invention also relates to sensor materials where the sensor material is formed using the single phase metal-silica sol-gel glasses. The sensor materials may be in the form of a thin film or may be attached to an optical fiber. The present invention also relates to a method of sensing chemicals using the chemical sensors by monitoring the chromatic change of the metal-silica sol-gel glass when the chemical binds to the sensor. The present invention also relates to oxidation catalysts where a metal-silica sol-gel glass catalyzes the reaction. The present invention also relates to a method of performing oxidation reactions using the metal-silica sol-gel glasses. The present invention also relates to organopolymer metal-silica sol-gel composites where the pores of the metal-silica sol-gel glasses are filled with an organic polymer polymerized by the sol-gel glass.

Efficacy and safety of clindamycin-tretinoin gel versus clindamycin or tretinoin alone in acne vulgaris: a randomized, double-blind, vehicle-controlled study.

PubMed

Jarratt, Michael T; Brundage, Tom

2012-03-01

Topical combination therapy containing a retinoid and an antimicrobial is an effective treatment for acne vulgaris. To evaluate the efficacy and safety of a new topical formulation containing clindamycin phosphate 1.2% and tretinoin 0.025% solubilized in an aqueous-based gel (CT gel). 1,649 participants were randomized 2:2:2:1 to 12 weeks of double-blind treatment with CT gel, clindamycin, tretinoin, or vehicle gel administered once daily. Significantly more participants achieved 2-grade or greater improvement on the Investigator's Static Global Assessment score with CT gel versus clindamycin, tretinoin, or vehicle gel. CT gel produced a significantly greater reduction in absolute number of total lesions versus all other treatment groups, in total and noninflammatory lesions versus clindamycin, and in total and inflammatory lesions versus tretinoin. Local tolerability was similar to that of tretinoin alone; signs and symptoms of irritation were most notable at week 2. There were no more adverse events with CT gel than with tretinoin gel. CT gel is more effective than clindamycin or tretinoin monotherapy, with a safety and tolerability profile similar to that of tretinoin.

Study on the rheological properties and volatile release of cold-set emulsion-filled protein gels.

PubMed

Mao, Like; Roos, Yrjö H; Miao, Song

2014-11-26

Emulsion-filled protein gels (EFP gels) were prepared through a cold-set gelation process, and they were used to deliver volatile compounds. An increase in the whey protein isolate (WPI) content from 4 to 6% w/w did not show significant effect on the gelation time, whereas an increase in the oil content from 5 to 20% w/w resulted in an earlier onset of gelation. Gels with a higher WPI content had a higher storage modulus and water-holding capacity (WHC), and they presented a higher force and strain at breaking, indicating that a more compact gel network was formed. An increase in the oil content contributed to gels with a higher storage modulus and force at breaking; however, this increase did not affect the WHC of the gels, and gels with a higher oil content became more brittle, resulting in a decreased strain at breaking. GC headspace analysis showed that volatiles released at lower rates and had lower air-gel partition coefficients in EFP gels than those in ungelled counterparts. Gels with a higher WPI content had lower release rates and partition coefficients of the volatiles. A change in the oil content significantly modified the partition of volatiles at equilibrium, but it produced a minor effect on the release rate of the volatiles. The findings indicated that EFP gels could be potentially used to modulate volatile release by varying the rheological properties of the gel.

A novel smart supramolecular organic gelator exhibiting dual-channel responsive sensing behaviours towards fluoride ion via gel-gel states.

PubMed

Mehdi, Hassan; Pang, Hongchang; Gong, Weitao; Dhinakaran, Manivannan Kalavathi; Wajahat, Ali; Kuang, Xiaojun; Ning, Guiling

2016-07-07

A novel smart supramolecular organic gelator G-16 containing anion and metal-coordination ability has been designed and synthesized. It shows excellent and robust gelation capability as a strong blue fluorescent supramolecular organic gel OG in DMF. Addition of Zn(2+) produced Zn(2+)-coordinated supramolecular metallogel OG-Zn. Organic gel OG and organometallic gel OG-Zn exhibited efficient and different sensing behaviors towards fluoride ion due to the variation in self-assembling nature. Supramolecular metallogel OG-Zn displayed specific selectivity for fluoride ion and formed OG-Zn-F with dramatic color change from blue to blue green in solution and gel to gel states. Furthermore after directly addition of fluoride into OG produced fluoride containing organic gel OG-F with drastically modulation in color from blue to greenish yellow fluorescence via strong aggregation-induced emission (AIE) property. A number of experiments were conducted such as FTIR, (1)H NMR, and UV/Vis spectroscopies, XRD, SEM and rheology. These results revealed that the driving forces involved in self-assembly of OG, OG-Zn, OG-Zn-F and OG-F were hydrogen bonding, metal coordination, π-π interactions, and van der Waal forces. In contrast to the most anion responsive gels, particularly fluoride ion responsive gels showed gel-sol state transition on stimulation by anions, the gel state of OG and OG-Zn did not show any gel-to-sol transition during the whole F(-) response process.

Highly efficient treatment of aerobic vaginitis with simple acidic buffered gels: The importance of pH and buffers on the microenvironment of vaginas.

PubMed

Sun, Xiaodong; Qiu, Haiying; Jin, Yiguang

2017-06-15

Aerobic vaginitis (AV) leads to uterus deep infection or preterm birth. Antibacterial agents are not optimal therapeutics of AV. Here, we report a series of temperature-sensitive in situ forming acidic buffered gels for topical treatment of AV, involving lactate, acetate, and citrate gels at pH 3.5, 5.0, and 6.5. AV rat models were prepared following vaginal infection with Staphylococcus aureus and Escherichia coli. In vitro/in vivo studies of the buffered gels were performed compared with ofloxacin gels and blank gels. All the buffered gels showed the lower in vitro antibacterial activities than ofloxacin gels but the better in vivo anti-S. aureus effects and similar anti-E. coli effects. The buffered gels improved Lactobacillus growth in the vaginas. Both the healthy rat vaginal pH and the pH of rat vaginas treated with the buffered gels were about 6.5 though the AV rat models or ones treated with ofloxacin gels still remained at the high pH more than 7.0. After treatments with the buffered gels, the vaginal smears changed to a clean state nearly without aerobic bacteria, the vaginal tissues were refreshed, and the immunoreactions were downregulated. The acidic buffered gels bring rapid decrease of local vaginal pH, high antibacterial activities, improvement of probiotics, and alleviation of inflammation. They are simple, highly efficient, and safe anti-AV formulations. Copyright © 2017 Elsevier B.V. All rights reserved.

Combining high-throughput MALDI-TOF mass spectrometry and isoelectric focusing gel electrophoresis for virtual 2D gel-based proteomics.

PubMed

Lohnes, Karen; Quebbemann, Neil R; Liu, Kate; Kobzeff, Fred; Loo, Joseph A; Ogorzalek Loo, Rachel R

2016-07-15

The virtual two-dimensional gel electrophoresis/mass spectrometry (virtual 2D gel/MS) technology combines the premier, high-resolution capabilities of 2D gel electrophoresis with the sensitivity and high mass accuracy of mass spectrometry (MS). Intact proteins separated by isoelectric focusing (IEF) gel electrophoresis are imaged from immobilized pH gradient (IPG) polyacrylamide gels (the first dimension of classic 2D-PAGE) by matrix-assisted laser desorption/ionization (MALDI) MS. Obtaining accurate intact masses from sub-picomole-level proteins embedded in 2D-PAGE gels or in IPG strips is desirable to elucidate how the protein of one spot identified as protein 'A' on a 2D gel differs from the protein of another spot identified as the same protein, whenever tryptic peptide maps fail to resolve the issue. This task, however, has been extremely challenging. Virtual 2D gel/MS provides access to these intact masses. Modifications to our matrix deposition procedure improve the reliability with which IPG gels can be prepared; the new procedure is described. Development of this MALDI MS imaging (MSI) method for high-throughput MS with integrated 'top-down' MS to elucidate protein isoforms from complex biological samples is described and it is demonstrated that a 4-cm IPG gel segment can now be imaged in approximately 5min. Gel-wide chemical and enzymatic methods with further interrogation by MALDI MS/MS provide identifications, sequence-related information, and post-translational/transcriptional modification information. The MSI-based virtual 2D gel/MS platform may potentially link the benefits of 'top-down' and 'bottom-up' proteomics. Copyright © 2016 Elsevier Inc. All rights reserved.

Comparison of micronized tretinoin gel 0.05% and tretinoin gel microsphere 0.1% in young adolescents with acne: a post hoc analysis of efficacy and tolerability data.

PubMed

Lucky, Anne W; Sugarman, Jeffrey

2011-06-01

Acne vulgaris is common in young adolescents. Retinoids are widely used but may be associated with poor tolerability. This post hoc analysis of 483 participants aged 10 to 14 years with mild to moderate acne compared efficacy and tolerability of once-daily treatment with micronized tretinoin gel 0.05%, tretinoin gel microsphere 0.1%, and vehicle over 12 weeks. In study 1, inflammatory and noninflammatory lesion reduction and treatment success was comparable between tretinoin gel 0.05% and tretinoin gel microsphere 0.1%. Inflammatory (46.3%) and noninflammatory (45.7%) lesion reductions with tretinoin gel 0.05% were significantly greater than vehicle (37.1% and 27.9%, respectively) (both P<.001). In study 2, inflammatory and noninflammatory lesion reductions and treatment success with tretinoin gel 0.05% (30.6%, 39.1%, and 19%, respectively) were significantly greater than vehicle (10.9%, 16.9% [both P<.001], and 4% [P=.008], respectively). Tretinoin gel 0.05% was significantly better tolerated than tretinoin gel microsphere 0.1% (P<.001); the majority of adverse events (AEs) were mild, occurring in the first 2 weeks. Fourteen percent of participants reported dry skin, 8% skin burning sensation, 5% erythema, and 5% dermatitis exfoliative with tretinoin gel 0.05% compared with 32%, 11%, 23%, and 23%, respectively, with tretinoin gel microsphere 0.1% (all P<.001, except skin burning sensation). In this secondary analysis of acne in young adolescents aged 10 to 14 years, micronized tretinoin gel 0.05% provided a comparable lesion reduction and treatment success versus tretinoin gel microsphere 0.1%, with a better cutaneous tolerability profile.

Comparison of the transdermal absorption of nimesulide from three commercially available gel formulations.

PubMed

Dayal, Pankaj; Kanikkannan, Narayanasamy; Singh, Amarjit; Sing, Mandip

2002-03-01

Nimesulide is a non-steroidal anti-inflammatory drug (NSAID) applied topically for a variety of conditions characterized by pain and inflammation. One of the aims of this study was to compare the permeation profile of nimesulide from the commercially available transdermal gel formulations across dermatomed porcine and human skin. The in vitro transdermal absorption of nimesulide formulations across porcine skin and human skin was studiedfor 24 hr using a continuous flow-through diffusion cell. The three commercial gels used in this study were Nimulid, Nise Gel, and Orthobid. All gels contained 1% (w/w) nimesulide. An infinite dose of nimesulide gel (about 300mg) was applied on the skin over 0.636 cm2 surface area. The rank order for the drug permeation from these formulations using porcine skin was: Nimulid > Orthobid > Nise Gel. The rank order of the permeation across human skin was: Nimulid> Nise Gel> Orthobid. The permeation profiles followed zero-order kinetics without any significant lag time. The steady-state flux of nimesulide from Nimulid was significantly higher than that of Nise Gel and Orthobid in both porcine and human skin (p <.05). However, there were no significant differences in the delivery of nimesulide (24 hr) from Nise Gel and Orthobid across both human and porcine skins. The results suggest that the Nimulid gel may have a greater bioavailability of nimesulide compared to the other gels. In addition, permeation profiles of the various gels across porcine skin did show a positive profile behavior to human skin. However, the in vitro drug release of nimesulide gels across a synthetic membrane did not correlate with skin permeation profiles.

Probing Biomolecular Structures and Dynamics of Single Molecules Using In-Gel Alternating-Laser Excitation

PubMed Central

Santoso, Yusdi; Kapanidis, Achillefs N.

2009-01-01

Gel electrophoresis is a standard biochemical technique used for separating biomolecules on the basis of size and charge. Despite the use of gels in early single-molecule experiments, gel electrophoresis has not been widely adopted for single-molecule fluorescence spectroscopy. We present a novel method that combines gel electrophoresis and single-molecule fluorescence spectroscopy to simultaneously purify and analyze biomolecules in a gel matrix. Our method, in-gel ALEX, uses non-denaturing gels to purify biomolecular complexes of interest from free components, aggregates, and non-specific complexes. The gel matrix also slows down translational diffusion of molecules, giving rise to long, high-resolution time traces without surface immobilization, which allow extended observations of conformational dynamics in a biologically friendly environment. We demonstrated the compatibility of this method with different types of single molecule spectroscopy techniques, including confocal detection and fluorescence-correlation spectroscopy. We demonstrated that in-gel ALEX can be used to study conformational dynamics at the millisecond timescale; by studying a DNA hairpin in gels, we directly observed fluorescence fluctuations due to conformational interconversion between folded and unfolded states. Our method is amenable to the addition of small molecules that can alter the equilibrium and dynamic properties of the system. In-gel ALEX will be a versatile tool for studying structures and dynamics of complex biomolecules and their assemblies. PMID:19863108

Synthesis and adsorption of silica gel modified 3-aminopropyltriethoxysilane (APTS) from corn cobs against Cu(II) in water

NASA Astrophysics Data System (ADS)

Purwanto, Agung; Yusmaniar, Ferdiani, Fatmawati; Damayanti, Rachma

2017-03-01

Silica gel modified APTS was synthesized from silica gel which was obtained from corn cobs via sol-gel process. Silica gel was synthesized from corn cobs and then chemically modified with silane coupling agent which has an amine group (NH2). This process resulting modified silica gel 3-aminopropyltriethoxysilane (APTS). Characterization of silica gel modified APTS by SEM-EDX showed that the size of the particles of silica gel modified APTS was 20µm with mass percentage of individual elements were nitrogen (N) 15.56%, silicon (Si) 50.69% and oxygen (O) 33.75%. In addition, silica gel modified APTS also showed absorption bands of functional groups silanol (Si-OH), siloxane (Si-O-Si), and an aliphatic chain (-CH2-), as well as amine (NH2) from FTIR spectra. Based on the characterization of XRD, silica gel 2θ of 21.094° and 21.32° respectively. It indicated that both material were amorphous. Determination of optimum pH and contact time on adsorption of silica gel 3-aminopropyltriethoxysilane (APTS) against Cu(II). The optimum pH and contact time was measured by using AAS. Optimum pH of adsorption silica gel modified APTS against metal Cu(II) could be obtained at pH 6 while optimum contact time was at 30 minutes, with the process of adsorption metal Cu(II) occured based on the model Freundlich isotherm.

Topical adapalene gel 0.1% vs. isotretinoin gel 0.05% in the treatment of acne vulgaris: a randomized open-label clinical trial.

PubMed

Ioannides, D; Rigopoulos, D; Katsambas, A

2002-09-01

Topical application of isotretinoin and adapalene has proved effective in treating acne vulgaris. Both drugs demonstrate therapeutic advantages and less irritancy over tretinoin, the most widely used treatment for acne. They both act as retinoid agonists, but differ in their affinity profile for nuclear and cytosolic retinoic acid receptors. To compare the efficacy and tolerability of adapalene gel 0.1% and isotretinoin gel 0.05% in the treatment of acne vulgaris of the face, in a randomized open-label clinical trial. Eighty patients were enrolled and were instructed to apply adapalene gel 0.1% or isotretinoin gel 0.05% once daily over a 12-week treatment period. Efficacy determination included noninflammatory and inflammatory lesion counts by the investigator and global evaluation of improvement. Cutaneous tolerance was assessed by determining erythema, scaling and burning with pruritus. Adapalene and isotretinoin gels were highly effective in treating facial acne. Adapalene gel produced greater reductions in noninflammatory and inflammatory lesion counts than did isotretinoin gel, but differences between treatments were not statistically significant. Adapalene gel was significantly better tolerated than isotretinoin gel during the whole treatment period. The two gels studied demonstrated comparable efficacy. When adapalene and isotretinoin were compared, significantly lower skin irritation was noted with adapalene, indicating that adapalene may begin a new era of treatment with low-irritant retinoids.

Effects of copper ions on the characteristics of egg white gel induced by strong alkali.

PubMed

Shao, Yaoyao; Zhao, Yan; Xu, Mingsheng; Chen, Zhangyi; Wang, Shuzhen; Tu, Yonggang

2017-09-01

This study investigated the effects of copper ions on egg white (EW) gel induced by strong alkali. Changes in gel characteristics were examined through texture profile analysis, scanning electron microscopy (SEM), and chemical methods. The value of gel strength reached its maximum when 0.1% copper ions was added. However, the lowest cohesiveness values were observed at 0.1%. The springiness of gel without copper ions was significantly greater than the gel with copper ions added. SEM results illustrated that the low concentration of copper ions contributes to a dense and uniform gel network, and an open matrix was formed at 0.4%. The free and total sulphhydryl group content in the egg white protein gel significantly decreased with the increased copper. The increase of copper ions left the contents of ionic and hydrogen bonds basically unchanged, hydrophobic interaction presented an increasing trend, and the disulfide bond exhibited a completely opposite change. The change of surface hydrophobicity proved that the main binding force of copper induced gel was hydrophobic interaction. However, copper ions had no effect on the protein component of the gels. Generally, a low level of copper ions facilitates protein-protein association, which is involved in the characteristics of gels. Instead, high ionic strength had a negative effect on gels induced by strong alkali. © 2017 Poultry Science Association Inc.

Sulfur-Containing Organic-Inorganic Hybrid Gel Compositions and Aerogels

NASA Technical Reports Server (NTRS)

Evans, Owen R (Inventor); Deshpande, Kiranmayi (Inventor); Dong, Wenting (Inventor)

2017-01-01

Methods and materials are described for preparing organic-inorganic hybrid gel compositions where a sulfur-containing cross-linking agent covalently links the organic and inorganic components. The gel compositions are further dried to provide porous gel compositions and aerogels. The mechanical and thermal properties of the dried gel compositions are also disclosed.

Sulfur-Containing Organic-Inorganic Hybrid Gel Compositions and Aerogels

NASA Technical Reports Server (NTRS)

Deshpande, Kiranmayi (Inventor); Evans, Owen R. (Inventor); Dong, Wenting (Inventor)

2015-01-01

Methods and materials are described for preparing organic-inorganic hybrid gel compositions where a sulfur-containing cross-linking agent covalently links the organic and inorganic components. The gel compositions are further dried to provide porous gel compositions and aerogels. The mechanical and thermal properties of the dried gel compositions are also disclosed.

The effects of brushing on human enamel surface roughness after NaF gel and theobromine gel exposure

NASA Astrophysics Data System (ADS)

Mahardhika, A.; Noerdin, A.; Eriwati, Y. K.

2017-08-01

This study aimed to determine the effects of brushing on human enamel surface roughness after different exposure times of 200 mg/L theobromine gel (8, 16, and 32 minutes) and 2% NaF gel (16 minutes). Twenty-four human upper premolars were used and divided into four groups. Group 1 was exposed to 2% NaF gel for 16 minutes. In contrast, groups 2, 3, and 4 were exposed to 200 mg/L theobromine gel for 8 minutes, 16 minutes, and 32 minutes, and each group was then brushed for 9 minutes and 20 seconds. After the treatment, samples were tested using a surface roughness tester (Mitutoyo SJ 301, Japan). The Wilcoxon test showed significant changes (p < 0.05) in roughness values after exposure to the theobromine gel or NaF gel and after brushing for 9 minutes and 20 seconds. It can be concluded that exposure to 200 mg/L theobromine gel or 2% NaF gel can soften the enamel surface and then increase roughness after brushing.

Optimal processing for gel electrophoresis images: Applying Monte Carlo Tree Search in GelApp.

PubMed

Nguyen, Phi-Vu; Ghezal, Ali; Hsueh, Ya-Chih; Boudier, Thomas; Gan, Samuel Ken-En; Lee, Hwee Kuan

2016-08-01

In biomedical research, gel band size estimation in electrophoresis analysis is a routine process. To facilitate and automate this process, numerous software have been released, notably the GelApp mobile app. However, the band detection accuracy is limited due to a band detection algorithm that cannot adapt to the variations in input images. To address this, we used the Monte Carlo Tree Search with Upper Confidence Bound (MCTS-UCB) method to efficiently search for optimal image processing pipelines for the band detection task, thereby improving the segmentation algorithm. Incorporating this into GelApp, we report a significant enhancement of gel band detection accuracy by 55.9 ± 2.0% for protein polyacrylamide gels, and 35.9 ± 2.5% for DNA SYBR green agarose gels. This implementation is a proof-of-concept in demonstrating MCTS-UCB as a strategy to optimize general image segmentation. The improved version of GelApp-GelApp 2.0-is freely available on both Google Play Store (for Android platform), and Apple App Store (for iOS platform). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of residual water on antacid properties of sucralfate gel dried by microwaves.

PubMed

Gainotti, Alessandro; Losi, Elena; Colombo, Paolo; Santi, Patrizia; Sonvico, Fabio; Baroni, Daniela; Massimo, Gina; Colombo, Gaia; Del Gaudio, Pasquale

2006-01-20

The aim of this work was to study the acid neutralization characteristics of microwave-dried sucralfate gel in relation to the water content and physical structure of the substance. Several dried sucralfate gels were compared with humid sucralfate gel and sucralfate nongel powder in terms of neutralization rate and buffering capacity. Humid sucralfate gel and microwave-dried gel exhibited antacid effectiveness. In particular, the neutralization rate of dried gel powders was inversely related to the water content: as the water content of dried powders decreased, the acid reaction rate linearly increased. The relationship was due to the different morphology of dried sucralfate gels. In fact, the porosity of the dried samples increased with the water reduction. However, the acid neutralization equivalent revealed that the dried sucralfate gel became more resistant to acid attack in the case of water content below 42%. Then, the microwave drying procedure had the opposite effect on the reactivity of the aluminum hydroxide component of dried sucralfate gel powders, since the rate of the reaction increased whereas the buffering capacity decreased as the amount of water was reduced.

The effect of residual water on antacid properties of sucralfate gel dried by microwaves.

PubMed

Gainotti, Alessandro; Losi, Elena; Colombo, Paolo; Santi, Patrizia; Sonvico, Fabio; Baroni, Daniela; Massimo, Gina; Colombo, Gaia; Del Gaudio, Pasquale

2006-03-01

The aim of this work was to study the acid neutralization characteristics of microwave-dried sucralfate gel in relation to the water content and physical structure of the substance. Several dried sucralfate gels were compared with humid sucralfate gel and sucralfate nongel powder in terms of neutralization rate and buffering capacity. Humid sucralfate gel and microwave-dried gel exhibited antacid effectiveness. In particular, the neutralization rate of dried gel powders was inversely related to the water content: as the water content of dried powders decreased, the acid reaction rate linearly increased. The relationship was due to the different morphology of dried sucralfate gels. In fact, the porosity of the dried samples increased with the water reduction. However, the acid neutralization equivalent revealed that the dried sucralfate gel became more resistant to acid attack in the case of water content below 42%. Then, the microwave drying procedure had the opposite effect on the reactivity of the aluminum hydroxide component of dried sucralfate gel powders, since the rate of the reaction increased whereas the buffering capacity decreased as the amount of water was reduced.

Spatiotemporal control of synergistic gel disintegration consisting of boroxole- and glyco-based polymers via photoinduced proton transfer.

PubMed

Kotsuchibashi, Yohei; Ebara, Mitsuhiro; Sato, Takeshi; Wang, Yinan; Rajender, Rajender; Hall, Dennis G; Narain, Ravin; Aoyagi, Takao

2015-02-12

We demonstrate here a local- and remote-control of gel disintegration by using photoinduced proton transfer chemistry of photoacid generator (PAG). The gels were prepared by simply mixing two polymers, poly(N-isopropylacrylamide-co-5-methacrylamido-1,2-benzoxaborole) (P(NIPAAm-co-MAAmBO)) and poly(3-gluconamidopropyl methacrylamide) (PGAPMA) via the synergistic interaction of benzoxaborole and diol groups. The o-nitrobenzaldehyde (o-NBA) was then loaded into the gel as a PAG. The benzoxaborole-diol interaction was successfully disintegrated upon UV irradiation due to the local pH decrease inside the gel. When the gel was irradiated to a specific gel region, the synergistic interactions were disintegrated only at the exposed region. Of special interest is that the whole material eventually transitioned from gel to sol state, as the generated protons diffused gradually toward the nonilluminated region. The ability of the proposed gel-sol transition system via photoinduced proton diffusion may be beneficial for not only prompt pH changes within the gel but also the design of predictive and programmable devices for drug delivery.

Improvement on the freeze-thaw stability of corn starch gel by the polysaccharide from leaves of Corchorus olitorius L.

PubMed

Yamazaki, Eiji; Sago, Toru; Kasubuchi, Yoshiaki; Imamura, Kazuhito; Matsuoka, Toshio; Kurita, Osamu; Nambu, Hironobu; Matsumura, Yasuki

2013-04-15

Effect of the polysaccharide from leaves of Corchorus olitorius L. (PLC) on the freeze-thaw (FT) stability of corn starch gel was studied. PLC was incorporated into the starch gel at 0.7% and total solid was adjusted to 6.0%. The syneresis was measured by the centrifugal-filtration method and, as a result, addition of PLC reduced effectively the syneresis of the starch gel even after 5 FT cycles, which was less than one third that of the normal starch gel. The rheological changes of the starch/PLC gel during the FT treatments were evaluated while the gel remained on the rheometer plate. The starch/PLC gel had less significant changes in the rheological parameters during the FT cycles than starch/guar gum or xanthan gum gel systems. SEM images showed that PLC stabilized the gel matrix surrounding pores, which would contribute to both a lower syneresis production and a higher stability in the rheological behavior at FT. Copyright © 2013 Elsevier Ltd. All rights reserved.

“Tell Juliana”: Acceptability of the Candidate Microbicide VivaGel® and Two Placebo Gels Among Ethnically Diverse, Sexually Active Young Women Participating in a Phase 1 Microbicide Study

PubMed Central

Giguere, Rebecca; Dolezal, Curtis; Chen, Beatrice A.; Kahn, Jessica; Zimet, Greg; Mabragaña, Marina; Leu, Cheng-Shiun; McGowan, Ian

2011-01-01

This study assessed acceptability of the candidate microbicide VivaGel® and two placebo gels among 61 sexually active young US and Puerto Rican women at three sites. Participants were randomly assigned to use one of the gels twice per day for 14 days. At trial completion, 59% of the women in the VivaGel® group reported being likely to use the gel in the future, whereas 23% were unlikely to use it and 18% were undecided. Participants reported problems with all three gels, including the “universal” placebo containing hydroxyethyl cellulose (HEC). The most frequent complaints were leakage, interference with sexual behavior, and decreased sexual satisfaction. Some of the complaints are not new but remain unresolved. Women’s perceived risk of HIV infection may determine whether the gels are used. Users also may want a choice of viscosity. Poor acceptability of vaginal microbicide formulations may result in poor adherence to gel use during efficacy trials and compromise validity of results. PMID:21863338

CONFORMANCE IMPROVEMENT USING GELS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Randall S. Seright

2003-09-01

This report describes work performed during the second year of the project, ''Conformance Improvement Using Gels.'' The project has two objectives. The first objective is to identify gel compositions and conditions that substantially reduce flow through fractures that allow direct channeling between wells, while leaving secondary fractures open so that high fluid injection and production rates can be maintained. The second objective is to optimize treatments in fractured production wells, where the gel must reduce permeability to water much more than that to oil. Pore-level images from X-ray computed microtomography were re-examined for Berea sandstone and porous polyethylene. This analysismore » suggests that oil penetration through gel-filled pores occurs by a gel-dehydration mechanism, rather than a gel-ripping mechanism. This finding helps to explain why aqueous gels can reduce permeability to water more than to oil. We analyzed a Cr(III)-acetate-HPAM gel treatment in a production well in the Arbuckle formation. The availability of accurate pressure data before, during, and after the treatment was critical for the analysis. After the gel treatment, water productivity was fairly constant at about 20% of the pre-treatment value. However, oil productivity was stimulated by a factor of 18 immediately after the treatment. During the six months after the treatment, oil productivity gradually decreased to approach the pre-treatment value. To explain this behavior, we proposed that the fracture area open to oil flow was increased substantially by the gel treatment, followed by a gradual closing of the fractures during subsequent production. For a conventional Cr(III)-acetate-HPAM gel, the delay between gelant preparation and injection into a fracture impacts the placement, leakoff, and permeability reduction behavior. Formulations placed as partially formed gels showed relatively low pressure gradients during placement, and yet substantially reduced the flow capacity of fractures (with widths from 1 to 4 mm) during brine and oil flow after placement. Regardless of gel age before placement, very little gel washed out from the fractures during brine or oil flow. However, increased brine or oil flow rate and cyclic injection of oil and water significantly decreased the level of permeability reduction. A particular need exists for gels that can plug large apertures (e.g., wide fractures and vugs). Improved mechanical strength and stability were demonstrated (in 1- to 4-mm-wide fractures) for a gel that contained a combination of high- and low-molecular weight polymers. This gel reduced the flow capacity of 2- and 4-mm-wide fractures by 260,000. In a 1-mm-wide fracture, it withstood 26 psi/ft without allowing any brine flow through the fracture. Cr(III)-acetate-HPAM gels exhibited disproportionate permeability reduction in fractures. The effect was most pronounced when the gel was placed as gelant or partially formed gels. The effect occurred to a modest extent with concentrated gels and with gels that were ''fully formed'' when placed. The effect was not evident in tubes. We explored swelling polymers for plugging fractures. Polymer suspensions were quickly prepared and injected. In concept, the partially dissolved polymer would lodge and swell to plug the fracture. For three types of swelling polymers, behavior was promising. However, additional development is needed before their performance will be superior to that of conventional gels.« less

Evaluation of radiochromic gel dosimetry and polymer gel dosimetry in a clinical dose verification

NASA Astrophysics Data System (ADS)

Vandecasteele, Jan; De Deene, Yves

2013-09-01

A quantitative comparison of two full three-dimensional (3D) gel dosimetry techniques was assessed in a clinical setting: radiochromic gel dosimetry with an in-house developed optical laser CT scanner and polymer gel dosimetry with magnetic resonance imaging (MRI). To benchmark both gel dosimeters, they were exposed to a 6 MV photon beam and the depth dose was compared against a diamond detector measurement that served as golden standard. Both gel dosimeters were found accurate within 4% accuracy. In the 3D dose matrix of the radiochromic gel, hotspot dose deviations up to 8% were observed which are attributed to the fabrication procedure. The polymer gel readout was shown to be sensitive to B0 field and B1 field non-uniformities as well as temperature variations during scanning. The performance of the two gel dosimeters was also evaluated for a brain tumour IMRT treatment. Both gel measured dose distributions were compared against treatment planning system predicted dose maps which were validated independently with ion chamber measurements and portal dosimetry. In the radiochromic gel measurement, two sources of deviations could be identified. Firstly, the dose in a cluster of voxels near the edge of the phantom deviated from the planned dose. Secondly, the presence of dose hotspots in the order of 10% related to inhomogeneities in the gel limit the clinical acceptance of this dosimetry technique. Based on the results of the micelle gel dosimeter prototype presented here, chemical optimization will be subject of future work. Polymer gel dosimetry is capable of measuring the absolute dose in the whole 3D volume within 5% accuracy. A temperature stabilization technique is incorporated to increase the accuracy during short measurements, however keeping the temperature stable during long measurement times in both calibration phantoms and the volumetric phantom is more challenging. The sensitivity of MRI readout to minimal temperature fluctuations is demonstrated which proves the need for adequate compensation strategies.

Soft and wet actuator developed with responsible high-strength gels

NASA Astrophysics Data System (ADS)

Harada, S.; Hidema, R.; Furukawa, H.

2012-04-01

Novel high-strength gels, named double network gels (DN gels), show a smart response to altering external electric field. It was reported that a plate shape of the DN gel bends toward a positive electrode direction when a static (DC) electric field is applied. Based on this previous result, it has been tried to develop a novel soft and wet actuator, which will be used as an automatically bulging button for cellar phones, or similar small devices. First, a bending experiment of a hung plate-shape DN gel was done, and its electric field response was confirmed. Second, the response of a lying plate-shape DN gels was confirmed in order to check the bulging phenomena. The edge of three plate-shape gels that was arranged radially on a plane surface was lifted 2mm by applying DC 8V. This system is a first step to make a gels button. However the critical problem is that electrolysis occurs simultaneously under electric field. Then, the water sweep out from gels, and gels is shrinking; They cause the separation between aluminum foil working as electrode and gels. That is why, a flexible electrode should be made by gels completely attached to the gels. As a third step, a push button is tried to make by a shape memory gels (SMG). The Young's modulus of the SMG is dramatically changed by temperature. This change in the modulus is applied to control the input-acceptable state and input-not-acceptable states of the button. A novel push button is proposed as a trial, and its user-friendliness is checked by changing the size of the button. The button is deformed by pushing and is back to original shape due to the property of shape memory. We believe the mechanism of this button will be applied to develop new devices especially for visually impaired persons.

Biochemical characterization of the beta-1,4-glucuronosyltransferase GelK in the gellan gum-producing strain Sphingomonas paucimobilis A.T.C.C. 31461.

PubMed Central

Videira, P; Fialho, A; Geremia, R A; Breton, C; Sá-Correia, I

2001-01-01

Biosynthesis of bacterial polysaccharide-repeat units proceeds by sequential transfer of sugars, from the appropriate sugar donor to an activated lipid carrier, by committed glycosyltransferases (GTs). Few studies on the mechanism of action for this type of GT are available. Sphingomonas paucimobilis A.T.C.C. 31461 produces the industrially important polysaccharide gellan gum. We have cloned the gelK gene from S. paucimobilis A.T.C.C. 31461. GelK belongs to family 1 of the GT classification [Campbell, Davies, Bulone, Henrissat (1997) Biochem. J. 326, 929-939]. Sequence similarity studies suggest that GelK consists of two protein modules corresponding to the -NH(2) and -CO(2)H halves, the latter possibly harbouring the GT activity. The gelK gene and the open reading frames coding for the -NH(2) (GelK(NH2)) and -CO(2)H (GelK(COOH)) halves were overexpressed in Escherichia coli. GelK and GelK(NH2) were present in both the soluble and membrane fractions of E. coli, whereas GelK(COOH) was only present in the soluble fraction. GelK catalysed the transfer of [(14)C]glucuronic acid from UDP-[(14)C]glucuronic acid into a glycolipid extracted from S. paucimobilis or E. coli, even in the presence of EDTA, and the radioactive sugar was released from the glycolipid by beta-1,4-glucuronidase. GelK was not able to use synthetic glucosyl derivatives as acceptors, indicating that the PP(i)-lipid moiety is needed for enzymic activity. Recombinant GelK(NH2) and GelK(COOH) did not show detectable activity. Based on the biochemical characteristics of GelK and on sequence similarities with N-acetylglucosaminyltransferase, we propose that GT families 1 and 28 form a superfamily. PMID:11513745

Homogeneity of gels and gel-derived glasses

NASA Technical Reports Server (NTRS)

Mukherjee, S. P.

1984-01-01

The significance and implications of gel preparation procedures in controlling the homogeneity of multicomponent oxide gels are discussed. The role of physicochemical factors such as the structure and chemical reactivities of alkoxides, the formation of double-metal alkoxides, and the nature of solvent(s) are critically analyzed in the context of homogeneity of gels during gelation. Three procedures for preparing gels in the SiO2-B2O3-Na2O system are examined in the context of cation distribution. Light scattering results for glasses in the SiO2-B2O3-Na2O system prepared by both the gel technique and the conventional technique are examined.

The preparation and characterization of a lithium borate glass prepared by the gel technique

NASA Technical Reports Server (NTRS)

Weinberg, M. C.; Neilson, G. F.; Smith, G. L.; Dunn, B.; Moore, G. S.; Mackenzie, J. D.

1985-01-01

The preparation of an amorphous lithium borate gel by the metal organic procedure is described. In addition, a preliminary evaluation of the behavior of the gel upon heating is given. In particular the crystallization tendency of the gel is studied with the aid of DTA and X-ray diffraction, and the structural changes in the gel are monitored with the aid of IR spectroscopy. The glass produced from the lithium borate gel is compared to both the gel precursor material and a glass of similar composition prepared by conventional techniques. Specifically, the relevant water contents, crystallization behavior, and structural features are contrasted.

Silicone gel breast implants: science and testing.

PubMed

Kinney, Brian M; Jeffers, Lynn L C; Ratliff, Gregory E; Carlisle, Dan A

2014-07-01

Since the first generation of breast implants, major design innovations, including consistency of the gel, palpability and thickness of the shell, and barrier materials in the shell, have been introduced. Surgeons have not had metrics to assess and compare available implants. Research at independent laboratories included 4 tests: gel elasticity (the gel's ability to retain its shape), gel compression fracture (the resistance to permanent gel deformation), gel-shell peel (the integration of the gel with shell as a cohesive unit), and morphological analysis. Sientra's round High-Strength Cohesive (HSC) experienced the least gel elasticity (5.805 mm), whereas Allergan's round implants experienced the most (7.465 mm). Among shaped implants, Allergan 410 experienced the least gel elasticity (3.242 mm), whereas the Sientra HSC+ implant experienced the most (4.270 mm). Sientra's round (36.32 lbf) and shaped (44.16 lbf) implants demonstrated the highest resistance to gel fracture, with Allergan's implants demonstrating the least among round (23.06 lbf) implants and Mentor Contour Profile Gel (CPG) among shaped (30.45 lbf) implants. For the gel-shell peel test, Sientra's implant required over 26% greater force than Allergan's implant and over 35% greater force than Mentor's implant. Sientra's shaped implants required more than double the peel force than Allergan 410 (119% greater) and Mentor CPG (130% greater). Morphological results showed Sientra's implants preserved structural integrity (-1.10% change). The initial findings show that these implant characteristics are individual factors to be considered separately and are not necessarily correlative. Further study of implants using these and other testing techniques will help clinicians choose between implants.

The effects of inhomogeneous boundary dilution on the coating flow of an anti-HIV microbicide vehicle

NASA Astrophysics Data System (ADS)

Tasoglu, Savas; Peters, Jennifer J.; Park, Su Chan; Verguet, Stéphane; Katz, David F.; Szeri, Andrew J.

2011-09-01

A recent study in South Africa has confirmed, for the first time, that a vaginal gel formulation of the antiretroviral drug Tenofovir, when topically applied, significantly inhibits sexual HIV transmission to women [Karim et al., Science 329, 1168 (2010)]. However, the gel for this drug and anti-HIV microbicide gels in general have not been designed using an understanding of how gel spreading and retention in the vagina govern successful drug delivery. Elastohydrodynamic lubrication theory can be applied to model spreading of microbicide gels [Szeri et al., Phys. Fluids 20, 083101 (2008)]. This should incorporate the full rheological behavior of a gel, including how rheological properties change due to contact with, and dilution by, ambient vaginal fluids. Here, we extend our initial analysis, incorporating the effects of gel dilution due to contact with vaginal fluid produced at the gel-tissue interface. Our original model is supplemented with a convective-diffusive transport equation to characterize water transport into the gel and, thus, local gel dilution. The problem is solved using a multi-step scheme in a moving domain. The association between local dilution of gel and rheological properties is obtained experimentally, delineating the way constitutive parameters of a shear-thinning gel are modified by dilution. Results show that dilution accelerates the coating flow by creating a slippery region near the vaginal wall akin to a dilution boundary layer, especially if the boundary flux exceeds a certain value. On the other hand, if the diffusion coefficient of boundary fluid is increased, the slippery region diminishes in extent and the overall rate of gel spreading decreases.

Structural studies of gels and gel-glasses in the SiO2-GeO2 system using vibrational spectroscopy

NASA Technical Reports Server (NTRS)

Mukherjee, Shyama P.; Sharma, Shiv K.

1986-01-01

GeO2 gel and gels in the SiO2-GeO2 system synthesized by the hydrolytic polycondensation of metal alkoxides have been studied by infrared and Raman spectroscopic techniques. The molecular structures, hydroxyl contents, and crystallinity of gels and gel-glasses in relation to the thermal history and GeO2 concentration were investigated. The binary compositions having up to 70 mol percent GeO2 were examined.

[Sniffing Position and i-gel Rotation Approach for i-gel Insertion under General Anesthesia].

PubMed

Takahashi, Yoshihiro; Murashima, Koji; Kayashima, Kenji

2016-04-01

Insertion assistance techniques, such as the sniffing position (SP) and i-gel? rotation approach (RA), are recommended in the i-gel supraglottic airway device insertion manual. The usefulness of these techniques was evaluated, in this study, under general anesthesia. In 50 adult patients, the i-gel was inserted with the patient in the mild-SP with 5 degrees head extention at first attempt. When resistance was encountered during insertion or airway patency was not obtained after insertion, the i-gel was re-inserted with the patient in the full-SP with maximum head extention during second attempt. When re-insertion failed, the i-gel was inserted with the patient in the full-SP and by using the i-gel RA during third attempt. Airway patency was established in the mild-SP in 36 of 50 patients, in the full-SP in 11 of the remaining 14, and in the full-SP with the i-gel RA in the remaining 3. The average insertion time was 24.0 s during the first attempt, 22.2 s during the second, and 18.2 s during the third. No major complications were observed. Both the full-SP and the i-gel RA can be used for i-gel insertion.

Solution-mediated growth of NBA-ZSM-5 crystals retarded by gel entrapment

NASA Astrophysics Data System (ADS)

Aguilar-Mamani, Wilson; Akhtar, Farid; Hedlund, Jonas; Mouzon, Johanne

2018-04-01

The synthesis of flat tablet-shaped ZSM-5 crystals from a gel using metakaolin as aluminosilicate source and n-butyl amine as structure directing agent was investigated. The evolution inside the solid phase was characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetry and mass spectrometry. A kinetic study indicated that the nucleation of the majority crystals occurred concurrently with the formation of the gel upon heating the starting liquid suspension. Microstructural evidences undeniably showed that the gel precipitated on ZSM-5 crystals and mineral impurities originating from kaolin. As a result, crystal growth was retarded by gel entrapment, as indicated by the configuration and morphology of the embedded crystals. The results presented herein are harmonized with a solution-mediated nucleation and growth mechanism. Our observations differ from the autocatalytic model that suggests that the nuclei rest inside the gel until released when the gel is consumed. Our results show instead that it is crystals that formed in an early stage before entrapment inside the gel that rest inside the gel until exposed at the gel surface. These results illustrate the limitation of the classical method used in the field to determine nucleation profiles when the crystals become trapped inside the gel.

Pharmacokinetic Studies of Gel System Containing Ibuprofen Solid Nanoparticles.

PubMed

Nagai, Noriaki; Tanino, Tadatoshi; Ito, Yoshimasa

2016-12-01

In the therapy of rheumatoid arthritis, ibuprofen (IBU) is widely used; however, it has been limited the clinical use by its systemic side effect, such as gastrointestinal lesions. Therefore, we prepared topical gel ointment used IBU solid nanoparticles (IBU nano -gel formulation). In addition, we demonstrated their anti-inflammatory effect by using arthritis model rat (adjuvant-induced arthritis rat, AA rat). The gel formulations were prepared using additives (Carbopol 934, 2-hydroxypropyl-β-cyclodextrin and methylcellulose) and bead mill-method. The IBU particle size in the IBU nano -gel formulation was 208 nm. The increase in inflammation of the hind feet of AA rats was attenuated by the treatment with the IBU nano -gel formulation, and preventive effect was higher than that of a gel formulation containing IBUmicroparticles (IBU micro -gel formulation, mean particle size 85.4 μm); the accumulation and permeability through the skin of IBU from the IBU nano -gel formulation were significantly larger in comparison with the IBU micro -gel formulation. Further, no gastrointestinal lesions were observed in AA rats following the repetitive administration of the 5% IBU nano -gel formulation (0.30 g) for 42 days (once a day). These results suggest that the dermal application of IBU-nanoparticles provide effective and efficient therapy that spares patients from unwanted side effects.

40 CFR 63.5731 - What standards must I meet for resin and gel coat mixing operations?

Code of Federal Regulations, 2010 CFR

2010-07-01

... and gel coat mixing operations? 63.5731 Section 63.5731 Protection of Environment ENVIRONMENTAL... Manufacturing Standards for Resin and Gel Coat Mixing Operations § 63.5731 What standards must I meet for resin and gel coat mixing operations? (a) All resin and gel coat mixing containers with a capacity equal to...

40 CFR 63.5731 - What standards must I meet for resin and gel coat mixing operations?

Code of Federal Regulations, 2011 CFR

2011-07-01

... and gel coat mixing operations? 63.5731 Section 63.5731 Protection of Environment ENVIRONMENTAL... Manufacturing Standards for Resin and Gel Coat Mixing Operations § 63.5731 What standards must I meet for resin and gel coat mixing operations? (a) All resin and gel coat mixing containers with a capacity equal to...

40 CFR 63.5731 - What standards must I meet for resin and gel coat mixing operations?

Code of Federal Regulations, 2012 CFR

2012-07-01

... and gel coat mixing operations? 63.5731 Section 63.5731 Protection of Environment ENVIRONMENTAL... Boat Manufacturing Standards for Resin and Gel Coat Mixing Operations § 63.5731 What standards must I meet for resin and gel coat mixing operations? (a) All resin and gel coat mixing containers with a...

40 CFR 63.5731 - What standards must I meet for resin and gel coat mixing operations?

Code of Federal Regulations, 2014 CFR

2014-07-01

... and gel coat mixing operations? 63.5731 Section 63.5731 Protection of Environment ENVIRONMENTAL... Boat Manufacturing Standards for Resin and Gel Coat Mixing Operations § 63.5731 What standards must I meet for resin and gel coat mixing operations? (a) All resin and gel coat mixing containers with a...

40 CFR 63.5731 - What standards must I meet for resin and gel coat mixing operations?

Code of Federal Regulations, 2013 CFR

2013-07-01

... and gel coat mixing operations? 63.5731 Section 63.5731 Protection of Environment ENVIRONMENTAL... Boat Manufacturing Standards for Resin and Gel Coat Mixing Operations § 63.5731 What standards must I meet for resin and gel coat mixing operations? (a) All resin and gel coat mixing containers with a...

Method of making ionic liquid mediated sol-gel sorbents

DOEpatents

Malik, Abdul; Shearrow, Anne M.

2017-01-31

Ionic liquid (IL)-mediated sol-gel hybrid organic-inorganic materials present enormous potential for effective use in analytical microextraction. One obstacle to materializing this prospect arises from high viscosity of ILs significantly slowing down sol-gel reactions. A method was developed which provides phosphonium-based, pyridinium-based, and imidazolium-based IL-mediated advanced sol-gel organic-inorganic hybrid materials for capillary microextraction. Scanning electron microscopy results demonstrate that ILs can serve as porogenic agents in sol-gel reactions. IL-mediated sol-gel coatings prepared with silanol-terminated polymers provided up to 28 times higher extractions compared to analogous sol-gel coatings prepared without any IL in the sol solution. This study shows that IL-generated porous morphology alone is not enough to provide effective extraction media: careful choice of the organic polymer and the precursor with close sol-gel reactivity must be made to ensure effective chemical bonding of the organic polymer to the created sol-gel material to be able to provide the desired sorbent characteristics.

Large deformation of self-oscillating polymer gel

NASA Astrophysics Data System (ADS)

Maeda, Shingo; Kato, Terukazu; Otsuka, Yuji; Hosoya, Naoki; Cianchetti, Matteo; Laschi, Cecilia

2016-01-01

A self-oscillating gel is a system that generates an autonomous volume oscillation. This oscillation is powered by the chemical energy of the Belousov-Zhabotinsky (BZ) reaction, which demonstrates metal ion redox oscillation. A self-oscillating gel is composed of Poly-N -isopropylacrylamide (PNIPAAm) with a metal ion. In this study, we found that the displacement of the volume oscillation in a self-oscillating gel could be controlled by its being subjected to a prestraining process. We also revealed the driving mechanism of the self-oscillating gel from the point of view of thermodynamics. We observed that the polymer-solvent interaction parameter χ is altered by the redox changes to the metal ion incorporated in the self-oscillating gel. The prestraining process leads to changes in χ and changes in enthalpy and entropy when the self-oscillating gel is in a reduced and oxidized state. We found that nonprestrained gel samples oscillate in a poor solution (χ >0.5 ) and prestrained gel samples oscillate in a good solution (χ <0.5 ).

Gadolinium-loaded gel scintillators for neutron and antineutrino detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riddle, Catherine Lynn; Akers, Douglas William; Demmer, Ricky Lynn

A gadolinium (Gd) loaded scintillation gel (Gd-ScintGel) compound allows for neutron and gamma-ray detection. The unique gel scintillator encompasses some of the best features of both liquid and solid scintillators, yet without many of the disadvantages associated therewith. Preferably, the gel scintillator is a water soluble Gd-DTPA compound and water soluble fluorophores such as: CdSe/ZnS (or ZnS) quantum dot (Q-dot) nanoparticles, coumarin derivatives 7-hydroxy-4-methylcoumarin, 7-hydroxy-4-methylcoumarin-3-acetic acid, 7-hydroxycoumarin-3-carboxylic acid, and Alexa Fluor 350 as well as a carbostyril compound, carbostyril 124 in a stable water-based gel, such as methylcellulose or polyacrylamide polymers. The Gd-loaded ScintGel allows for a homogenious distribution ofmore » the Gd-DTPA and the fluorophores, and yields clean fluorescent emission peaks. A moderator, such as deuterium or a water-based clear polymer, can be incorporated in the Gd-ScintGel. The gel scintillators can be used in compact detectors, including neutron and antineutrino detectors.« less

The Tolerability Profile of Clindamycin 1%/Benzoyl Peroxide 5% Gel vs. Adapalene 0.1%/Benzoyl Peroxide 2.5% Gel for Facial Acne

PubMed Central

Cirigliano, Marcela; Gwazdauskas, Jennifer A; Gonzalez, Pablo

2012-01-01

Objective: To compare the first two weeks of tolerability of clindamycin/benzoyl peroxide gel versus adapalene/benzoyl peroxide gel followed by six weeks of open-label clindamycin/benzoyl peroxide gel therapy in subjects with mild-to-moderate acne who participated in two eight-week, identically designed, clinical studies. Methods: Using a split-face method, patients received both clindamycin/benzoyl peroxide gel and adapalene/benzoyl peroxide gel once daily for two weeks (allocation to the right or left side of the face was randomized) in an investigator-blinded fashion. Patients then went on to receive a further six weeks of open-label, full-face clindamycin/benzoyl peroxide gel. The primary outcome was to compare signs and symptoms of tolerability during the first two weeks of treatment using an investigator-assessed 4-point rating scale. Secondary endpoints included assessment of acne severity (Investigator Static Global Assessment and lesion counts), quality of life, product acceptability/preference, and patient assessments of tolerability and safety. Results: Of the 76 subjects enrolled in the two studies, 72 completed them. Overall both products were well tolerated, but mean scores for erythema, dryness, and peeling were significantly higher with adapalene/benzoyl peroxide gel than with clindamycin/benzoyl peroxide gel at both Weeks 1 and 2 (p<0.03). Patients also rated clindamycin/benzoyl peroxide gel significantly more tolerable than adapalene/benzoyl peroxide gel for redness, dryness, burning, itching, and scaling at Weeks 1 and 2 (p 0.0073). Mean Investigator Static Global Assessment score improved with both products during the first two weeks of treatment and continued to show significant improvement versus baseline when treatment with clindamycin/benzoyl peroxide gel was continued for a further six weeks (p<0.001 at Week 8). Lesion counts improved throughout the study with significant reductions from baseline occurring at Weeks 5 and 8 (p<0.0001 for both time points for total lesion counts). Clindamycin/benzoyl peroxide gel and adapalene/benzoyl peroxide gel were well tolerated, with most adverse events of mild-to-moderate severity. Conclusion: Clindamycin/benzoyl peroxide gel had better tolerability with regard to erythema, dryness, and peeling than adapalene/benzoyl peroxide gel during the first two weeks of treatment. PMID:22808305

Numerical modelling and experimental study of liquid evaporation during gel formation

NASA Astrophysics Data System (ADS)

Pokusaev, B. G.; Khramtsov, D. P.

2017-11-01

Gels are promising materials in biotechnology and medicine as a medium for storing cells for bioprinting applications. Gel is a two-phase system consisting of solid medium and liquid phase. Understanding of a gel structure evolution and gel aging during liquid evaporation is a crucial step in developing new additive bioprinting technologies. A numerical and experimental study of liquid evaporation was performed. In experimental study an evaporation process of an agarose gel layer located on Petri dish was observed and mass difference was detected using electronic scales. Numerical model was based on a smoothed particle hydrodynamics method. Gel in a model was represented as a solid-liquid system and liquid evaporation was modelled due to capillary forces and heat transfer. Comparison of experimental data and numerical results demonstrated that model can adequately represent evaporation process in agarose gel.

Coupling the Alkaline-Surfactant-Polymer Technology and the Gelation Technology to Maximize Oil Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malcolm Pitts; Jie Qi; Dan Wilson

2005-12-01

Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or reservoirs with different sand lenses with high permeability contrast. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more crude oil than waterflooding froin swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or reservoirs with high permeability contrast zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. Fluid-fluid interaction withmore » different gel chemical compositions and alkaline-surfactant-polymer solution with pH values ranging from 9.2 to 12.9 have been tested. Aluminum-polyacrylamide gels are not stable to alkaline-surfactant-polymer solutions at any pH. Chromium-polyacrylamide gels with polymer to chromium ion ratios of 25 or greater were stable to alkaline-surfactant-polymer solutions if solution pH was 10.6 or less. When the polymer to chromium ion was 15 or less, chromium-polyacrylamide gels were stable to alkaline-surfactant-polymer solutions with pH values up to 12.9. Chromium-xanthan gum gels were stable to alkaline-surfactant-polymer solutions with pH values of 12.9 at the polymer to chromium ion ratios tested. Silicate-polyacrylamide, resorcinol-formaldehyde, and sulfomethylated resorcinol-formaldehyde gels were also stable to alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Iron-polyacrylamide gels were immediately destroyed when contacted with any of the alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in the fluid-fluid analyses with the exception of the xanthan gum-chromium acetate gels. Aluminum-polyacrylamide flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9, either in linear corefloods or in dual separate radial core, common manifold corefloods. Chromium acetate-polyacrylamide flowing and rigid tonguing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid tonguing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Chromium acetate gels were stable to injection of alkaline-surfactant-polymer solutions at 72 F, 125 F and 175 F in linear corefloods. Chromium acetate-polyacrylamide gels maintained diversion capability after injection of an alkaline-surfactant-polymer solution in stacked; radial coreflood with a common well bore. Chromium acetate-polyacrylamide gel used to seal fractured core maintain fracture closure if followed by an alkaline-surfactant-polymer solution. Chromium acetate-xanthan gum rigid gels are not stable to subsequent alkaline-surfactant-polymer solution injection at 72, 125, and 175 F. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Resorcinol-formaldehyde gels were stable to subsequent alkaline-surfactant-polymer solution injection. When evaluated in a dual core configuration, injected fluid flows into the core with the greatest effective permeability to the injected fluid. The same gel stability trends to subsequent alkaline-surfactant-polymer injected solution were observed. Aluminum citrate-polyacrylamide, resorcinol-formaldehyde, and the silicate-polyacrylamide gel systems did not produce significant incremental oil in linear corefloods. Both flowing and rigid tonguing chromium acetate-polyacrylamide gels and the xanthan gum-chromium acetate gel system produced incremental oil with the rigid tonguing gel producing the greatest amount. Higher oil recovery could have been due to higher differential pressures across cores. Aluminum citrate-polyacrylamide gels, chromium acetate-polyacrylamide gels, silicate-polymer, and chromium-xanthan guin gels did not alter an alkaline-surfactant-polymer solution's ability to produce incremental oil. Incremental oil was reduced with the resorcinol-formaldehyde gel system. Total waterflood plus chemical flood oil recovery sequence recoveries were generally similar.« less

Water equivalence of NIPAM based polymer gel dosimeters with enhanced sensitivity for x-ray CT

NASA Astrophysics Data System (ADS)

Gorjiara, Tina; Hill, Robin; Bosi, Stephen; Kuncic, Zdenka; Baldock, Clive

2013-10-01

Two new formulations of N-isopropylacrylamide (NIPAM) based three dimensional (3D) gel dosimeters have recently been developed with improved sensitivity to x-ray CT readout, one without any co-solvent and the other one with isopropanol co-solvent. The water equivalence of the NIPAM gel dosimeters was investigated using different methods to calculate their radiological properties including: density, electron density, number of electrons per grams, effective atomic number, photon interaction probabilities, mass attenuation and energy absorption coefficients, electron collisional, radiative and total mass stopping powers and electron mass scattering power. Monte Carlo modelling was also used to compare the dose response of these gel dosimeters with water for kilovoltage and megavoltage x-ray beams and for megavoltage electron beams. We found that the density and electron density of the co-solvent free gel dosimeter are more water equivalent with less than a 2.6% difference compared to a 5.7% difference for the isopropanol gel dosimeter. Both the co-solvent free and isopropanol solvent gel dosimeters have lower effective atomic numbers than water, differing by 2.2% and 6.5%, respectively. As a result, their photoelectric absorption interaction probabilities are up to 6% and 19% different from water, respectively. Compton scattering and pair production interaction probabilities of NIPAM gel with isopropanol differ by up to 10% from water while for the co-solvent free gel, the differences are 3%. Mass attenuation and energy absorption coefficients of the co-solvent free gel dosimeter and the isopropanol gel dosimeter are up to 7% and 19% lower than water, respectively. Collisional and total mass stopping powers of both gel dosimeters differ by less than 2% from those of water. The dose response of the co-solvent free gel dosimeter is water equivalent (with <1% discrepancy) for dosimetry of x-rays with energies <100 keV while the discrepancy increases (up to 5%) for the isopropanol gel dosimeter over the same energy range. For x-ray beams over the energy range 180 keV-18 MV, both gel dosimeters have less than 2% discrepancy with water. For megavoltage electron beams, the dose differences with water reach 7% and 14% for the co-solvent free gel dosimeter and the isopropanol gel dosimeter, respectively. Our results demonstrate that for x-ray beam dosimetry with photon energies higher than 100 keV and megavoltage electron beams, correction factors are needed for both NIPAM gels to be used as water equivalent dosimeters.

A novel low-molecular-mass gelator with a redox active ferrocenyl group: tuning gel formation by oxidation.

PubMed

Liu, Jing; Yan, Junlin; Yuan, Xuanwei; Liu, Kaiqiang; Peng, Junxia; Fang, Yu

2008-02-15

A novel low-molecular-mass gelator containing a redox-active ferrocenyl group, cholesteryl glycinate ferrocenoylamide (CGF), was intentionally designed and prepared. It was demonstrated that the gelator gels 13 out of the 45 solvents tested. Scanning electron microscopy (SEM) measurements revealed that the gelator self-assembled into different supramolecular network structures in different gels. Chemical oxidation of the ferrocenyl residue resulted in phase transition of the gel from gel state to solution state. FTIR and (1)H NMR spectroscopy studies revealed that hydrogen bonding between the gelator molecules in the gel was one of the main driving forces for the formation of the gels.

Analyzing genetic diversity in conifers...isozyme resolution by starch gel electrophoresis

Treesearch

M. Thompson Conkle

1972-01-01

Enzymes in forest tree materials can be resolved by starch gel electrophoresis. A gel slab is prepared in a mold assembled from glass and plastic. Wicks containing an aqueous extract of macerated plant material are inserted in the gel and processed. The gel is sliced, stained, examined, and photographed. Isozyme bands produced by differential migration of enzymes...

Quantitative and qualitative measure of intralaboratory two-dimensional protein gel reproducibility and the effects of sample preparation, sample load, and image analysis.

PubMed

Choe, Leila H; Lee, Kelvin H

2003-10-01

We investigate one approach to assess the quantitative variability in two-dimensional gel electrophoresis (2-DE) separations based on gel-to-gel variability, sample preparation variability, sample load differences, and the effect of automation on image analysis. We observe that 95% of spots present in three out of four replicate gels exhibit less than a 0.52 coefficient of variation (CV) in fluorescent stain intensity (% volume) for a single sample run on multiple gels. When four parallel sample preparations are performed, this value increases to 0.57. We do not observe any significant change in quantitative value for an increase or decrease in sample load of 30% when using appropriate image analysis variables. Increasing use of automation, while necessary in modern 2-DE experiments, does change the observed level of quantitative and qualitative variability among replicate gels. The number of spots that change qualitatively for a single sample run in parallel varies from a CV = 0.03 for fully manual analysis to CV = 0.20 for a fully automated analysis. We present a systematic method by which a single laboratory can measure gel-to-gel variability using only three gel runs.

Tissue simulating gel for medical research

NASA Technical Reports Server (NTRS)

Companion, John A. (Inventor)

1991-01-01

A tissue simulating gel and a method for preparing the tissue simulating gel are disclosed. The tissue simulating gel is prepared by a process using water, gelatin, ethylene glycol, and a cross-linking agent. In order to closely approximate the characteristics of the type of tissue being simulated, other material has been added to change the electrical, sound conducting, and wave scattering properties of the tissue simulating gel. The result of the entire process is a formulation that will not melt at the elevated temperatures involved in hyperthermia medical research. Furthermore, the tissue simulating gel will not support mold or bacterial growth, is of a sufficient mechanical strength to maintain a desired shape without a supporting shell, and is non-hardening and non-drying. Substances have been injected into the tissue simulating gel prior to the setting-up thereof just as they could be injected into actual tissue, and the tissue simulating gel is translucent so as to permit visual inspection of its interior. A polyurethane spray often used for coating circuit boards can be applied to the surface of the tissue simulating gel to give a texture similar to human skin, making the tissue simulating gel easier to handle and contributing to its longevity.

Development of gel materials with high transparency and mechanical strength for use with a 3D gel printer SWIM-ER

NASA Astrophysics Data System (ADS)

Tase, Taishi; Okada, Koji; Takamatsu, Kyuichiro; Saito, Azusa; Kawakami, Masaru; Furukawa, Hidemitsu

2016-04-01

Medical doctors use artificial blood vessels and organ models, which are usually made of plastic, to explain operations to students, or patients awaiting treatment. However, there are some problems such as the high cost of making the model and there is not a realistic feel because the model is hard. These problems can be solved using soft and wet material for instance gel. Gels are materials with unique properties such as transparency, biocompatibility, and low friction. In recent years, high strength gel has been developed and is expected to be applied in medical fields in the future. Artificial models of gel can be produced by 3D gel printers. Our group has been developing a 3D gel printer with 1mm precision in printing, but the shape, size and mechanical strength are not sufficient for medical models. In this study, we overcome these problems and make a gel model which is transparent, mechanically strong with a fine shape. The strength and molding accuracy is improved by changing and preparing the cross linker and ultraviolet absorber. We conducted mechanical and molding tests to confirm that the gel material properties improved.

Can a commercial gel dosimetry system be used to verify stereotactic spinal radiotherapy treatment dose distributions?

NASA Astrophysics Data System (ADS)

Kairn, T.; Asena, A.; Crowe, S. B.; Livingstone, A.; Papworth, D.; Smith, S.; Sutherland, B.; Sylvander, S.; Franich, R. D.; Trapp, J. V.

2017-05-01

This study investigated the use of the TruView xylenol-orange-based gel and VISTA optical CT scanner (both by Modus Medical Inc, London, Canada), for use in verifying the accuracy of planned dose distributions for hypo-fractionated (stereotactic) vertebral treatments. Gel measurements were carried out using three stereotactic vertebral treatments and compared with planned doses calculated using the Eclipse treatment planning system (Varian Medical Systems, Palo Alto, USA) as well as with film measurements made using Gafchromic EBT3 film (Ashland Inc, Covington, USA), to investigate the accuracy of the gel system. The gel was calibrated with reference to a moderate-dose gradient region in one of the gel samples. Generally, the gel measurements were able to approximate the close agreement between the doses calculated by the treatment planning system and the doses measured using film (which agreed with each other within 2%), despite lower resolution and bit depth. Poorer agreement was observed when the dose delivered to the gel exceeded the range of doses delivered in the calibration region. This commercial gel dosimetry system may be used to verify hypo-fractionated treatments of vertebral targets, although separate gel calibration measurements are recommended.

Tissue simulating gel for medical research

NASA Technical Reports Server (NTRS)

Companion, John A. (Inventor)

1989-01-01

A tissue simulating gel and a method for preparing the tissue simulating gel are disclosed. The tissue simulating gel is prepared by a process using water, gelatin, ethylene gylcol, and a cross-linking agent. In order to closely approximate the characteristics of the type of tissue being simulated, other material has been added to change the electrical, sound conducting, and wave scattering properties of the tissue simulating gel. The result of the entire process is a formulation that will not melt at the elevated temperatures involved in hyperthermia medical research. Furthermore, the tissue simulating gel will not support mold or bacterial growth, is of a sufficient mechanical strength to maintain a desired shape without a supporting shell, and is non-hardening and non-drying. Substances were injected into the tissue simulating gel prior to the setting-up thereof just as they could be injected into actual tissue, and the tissue simulating gel is translucent so as to permit visual inspection of its interior. A polyurethane spray often used for coating circuit boards can be applied to the surface of the tissue simulating gel to give a texture similar to human skin, making the tissue simulating gel easier to handle and contributing to its longevity.

Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by sol-gel process

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1990-01-01

Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water:TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, x ray diffraction, surface area and pore size distribution measurements.

Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by the sol-gel process

NASA Technical Reports Server (NTRS)

Bansal, N. P.

1992-01-01

Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water: TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, X-ray diffraction, surface area and pore size distribution measurements.

Charge-regularized swelling kinetics of polyelectrolyte gels: Elasticity and diffusion

NASA Astrophysics Data System (ADS)

Sen, Swati; Kundagrami, Arindam

2017-11-01

We apply a recently developed method [S. Sen and A. Kundagrami, J. Chem. Phys. 143, 224904 (2015)], using a phenomenological expression of osmotic stress, as a function of polymer and charge densities, hydrophobicity, and network elasticity for the swelling of spherical polyelectrolyte (PE) gels with fixed and variable charges in a salt-free solvent. This expression of stress is used in the equation of motion of swelling kinetics of spherical PE gels to numerically calculate the spatial profiles for the polymer and free ion densities at different time steps and the time evolution of the size of the gel. We compare the profiles of the same variables obtained from the classical linear theory of elasticity and quantitatively estimate the bulk modulus of the PE gel. Further, we obtain an analytical expression of the elastic modulus from the linearized expression of stress (in the small deformation limit). We find that the estimated bulk modulus of the PE gel decreases with the increase of its effective charge for a fixed degree of deformation during swelling. Finally, we match the gel-front locations with the experimental data, taken from the measurements of charged reversible addition-fragmentation chain transfer gels to show an increase in gel-size with charge and also match the same for PNIPAM (uncharged) and imidazolium-based (charged) minigels, which specifically confirms the decrease of the gel modulus value with the increase of the charge. The agreement between experimental and theoretical results confirms general diffusive behaviour for swelling of PE gels with a decreasing bulk modulus with increasing degree of ionization (charge). The new formalism captures large deformations as well with a significant variation of charge content of the gel. It is found that PE gels with large deformation but same initial size swell faster with a higher charge.

Acceptability of a combination testosterone gel and depomedroxyprogesterone acetate male contraceptive regimen.

PubMed

Amory, John K; Page, Stephanie T; Anawalt, Bradley D; Matsumoto, Alvin M; Bremner, William J

2007-03-01

Testosterone (T) gel, administered transdermally in combination with injections of depomedroxyprogesterone acetate (DMPA) every 3 months, results in effective suppression of spermatogenesis in 90% of men. Men's attitudes regarding the daily self-administration of T-gel and the impact of such a regimen on sexual function, however, are unknown. Therefore, we questioned subjects enrolled in a combination T-gel plus DMPA male contraceptive trial regarding the acceptability of T-gel for male contraception and the impact of the T-gel/DMPA regimen on sexual function and satisfaction during treatment. Thirty-eight healthy men, ages 18-55, were treated with T-gel (100 mg daily) + DMPA (300 mg every 3 months) for 24 weeks. Sexual function was assessed using a validated questionnaire at baseline, after 12 and 24 weeks of treatment and 12 weeks into recovery. The overall acceptability of the method and attitudes regarding the daily self-administration of T-gel were assessed by a questionnaire 12 weeks into recovery. Fifty percent of subjects were either satisfied or very satisfied with the T-gel-based contraceptive regimen, and 45% indicated they would use the regimen if it were commercially available. The T-gel was found to be easy to use by 76% of men, but a third of subjects felt that T-gel administration interfered with their daily routine. Sexual function was largely preserved during treatment; however, slight decreases in sexual function were noted during recovery. The experimental male hormonal contraceptive regimen of T-gel + DMPA is acceptable to approximately one half of study volunteers, most of whom would use the method if it were commercially available. Given its appeal to a significant proportion of men, additional studies using T-gel and DMPA for male contraception are warranted.

Hybrid organic-inorganic sol-gel materials and components for integrated optoelectronics

NASA Astrophysics Data System (ADS)

Lu, Dong

On the technical platform of hybrid organic-inorganic sol-gel, the integrated optoelectronics in the forms of heterogeneous integration between the hybrid sol-gel waveguide and the high refractive index semiconductors and the nonlinear functional doping of disperse red chromophore into hybrid sol-gel is developed. The structure of hybrid sol-gel waveguide on high index semiconductor substrate is designed with BPM-CAD software. A hybrid sol-gel based on MAPTMS and TEOS suitable for lower cladding for the waveguide is developed. The multi-layer hybrid sol-gel waveguide with good mode confinement and low polarization dependence is fabricated on Si and InP. As proof of concept, a 1 x 12 beam splitter based on multimode interference is fabricated on silicon substrate. The device shows excess loss below 0.65 dB and imbalance below 0.28 dB for both TE and TM polarization. A nonlinear active hybrid sol-gel doped with disperse red 13 has been developed by simple co-solvent method. It permits high loading concentration and has low optical loss at 1550 nm. The second-order nonlinear property of the active sol-gel is induced with corona poling and studied with second harmonic generation. A 3-fold of enhancement in the poling efficiency is achieved by blue light assisted corona poling. The chromophore alignment stability is improved by reducing the free volume of the formed inorganic network from the sol-gel condensation reaction. An active sol-gel channel waveguide has been fabricated using active and passive hybrid sol-gel materials by only photopatterning and spin-coating. An amplitude modulator based on the active sol-gel containing 30 wt.% of DR13 shows an electro-optic coefficient of 14 pm/V at 1550 nm and stable operation within the observation time of 24 days.

Studies on a new class of organogelator containing 2-anthracenecarboxylic acid: influence of gelator and solvent on stereochemistry of the photodimers.

PubMed

Dawn, Arnab; Fujita, Norifumi; Haraguchi, Shuichi; Sada, Kazuki; Tamaru, Shun-ichi; Shinkai, Seiji

2009-11-07

A new class of binary organogelator (G1, G2 and G3) based on 2-anthracenecarboxylic acid (2Ac), attached noncovalently with the gelator counterpart containing a 3,4,5-tris(n-dodecyloxy)benzoylamide backbone has been developed. Among the three gelators, two (G2 and G3) are chiral containing D-alanine or L-2-phenylglycine moieties, respectively. They can act as efficient gelators of organic solvents with varying polarity depending upon the gelator systems. Gelator G1 even gelates chiral solvents. The photoirradiation of the gel samples produces photocyclodimers having different degrees of stereoselectivity for different systems. Gels with G1 and G2 produce head-to-head (h-h) photodimers as major products, whereas the stereoselectivity is reversed for the gels with G3 producing head-to-tail (h-t) photodimers as major products. Among those, G2/cyclohexane gel shows the highest degree of stereoselectivity, producing only h-h photodimers with some significant amount of chiral induction. Other chiral systems exhibit low to moderate chiral inductions. The gelator G1 can differentiate between the racemic and enantiomerically pure varieties of a solvent by exhibiting different gel melting temperatures (T(gel)). For different gel systems, T(gel) increases in all the cases as a consequence of photoreaction, except for the G2/cyclohexane gel, where a prominent gel-to-sol phase transition can be observed during the photoreaction. Hydrogen-bonding and pi-pi stacking interactions play the principal roles in constructing the gel structure. The morphologies of the gel systems vary between one-dimensional fibrils and a fibrillar network structure. In addition, the influences of the gelator and solvent polarity on the rate of photoreactions, photoproduct distributions as well as gel structures are investigated.

Electromyography analysis of natural mastication behavior using varying mouthful quantities of two types of gels.

PubMed

Kohyama, Kaoru; Gao, Zhihong; Ishihara, Sayaka; Funami, Takahiro; Nishinari, Katsuyoshi

2016-07-01

The objectives of this study were to examine the effects of mouthful quantities and mechanical properties of gels on natural mastication behaviors using electromyography (EMG). Two types of hydrocolloid gels (A and K) with similar fracture loads but different moduli and fracture strains were served to eleven normal women in 3-, 6-, 12-, and 24-g masses in a randomized order. EMG activities from both masseter muscles were recorded during natural mastication. Because of the similar fracture loads, the numbers of chews, total muscle activities, and entire oral processing times were similar for similar masses of both gel types. Prior to the first swallow, the more elastic K gel with a higher fracture strain required higher muscle activities than the brittle A gel, which had higher modulus. Majority of subjects had preferred sides of chewing, but all subjects with or without preferred sides used both masseters during the consumption of gels. Similar effects of masses and types of gels were observed in EMG activities of both sides of masseters. Contributions of the dominant side of chewing were diminished with increasing masses of gels, and the mass dependency on ratio of the dominant side was more pronounced with K gel. More repetitions of smaller masses required greater muscle activities and longer periods for the consumption of 24-g gel portions. Reduction in the masses with an increased number of repetitions necessitated slower eating and more mastication to consume the gel portions. These observations suggest that chewing using both sides is more effective and unconsciously reduces mastication times during the consumption of gels. Copyright © 2016 Elsevier Inc. All rights reserved.

Applications and Properties of Ionic Liquid- Based Gels and Soft Solid Composites

NASA Astrophysics Data System (ADS)

Voss, Bret Alan McGinness

2011-12-01

Solid-liquid composites (gels) have a combination of properties that afford new material applications in which high solute diffusion is desirable. These composites have a soft-solid mechanical integrity and will not flow under gravity, but entrain a liquid matrix (i.e. 60-98 mass %) which allows for high diffusion and high reactivity. Room temperature ionic liquid (RTILs) are molten organic salts with a melting point below room temperature and negligible vapor pressure. If the RTILs are used as the liquid component of a gel, then the gel matrix will not evaporate (unlike other organic solvents) and may be used for long term applications. This thesis research applies RTIL gels for two new applications; carbon dioxide/nitrogen separation and chemical warfare agent (CWA) barrier and decontamination. Separating CO2 from the flue gas of coal and gas fired power-plants is an increasingly economically and environmentally important gas separation. In this first study, RTIL gels are cast in a supported membrane and gas permeability and ideal selectivity are measured. The RTIL matrix has an inherent affinity for CO2 and provides a high diffusion, hence high permeability (i.e. 500-700 barrer). The solidifying component is a low molecular-weight organic gelator (LMOG) which through physical bonding interactions (i.e. hydrogen bonding, pi-pi stacking and van der Walls forces) forms an entangled network which provides mechanical stability (i.e. increase trans-membrane pressure required to expel selective material from the support). In these studies two LMOGs and five RTILs are used to make supported gel membranes and determine gas permeability and temperature dependent trends. The second application for RTIL gels is a decontaminating barrier for CWAs and toxic industrial compounds (TICs). In these studies a layer of RTIL gel is applied on top of a substrate contaminated with a CWA simulant (i.e. chloroethylethylsulfide, CEES). The gel performs well as a barrier, preventing CEES vapor from penetrating the gel. Simultaneously, the RTIL gel actively decontaminated the substrate by reacting CEES with a sacrificial amine. The RTIL gel barrier was able to decontaminate up to 98% of the CEES applied to a painted steel substrate. Two gel barriers are tested: (1) RTIL gel with a LMOG solidifying agent, and (2) RTIL gel with a polymeric cross-linked network solidifying agent. The polymer gel provided a more mechanically robust barrier, however, the LMOG gel decontaminated at a faster rate. These new applications are but two of many possible applications for RTIL gels. Their negligible vapor pressure affords long term application in ambient conditions and their unique chemistry allows them to be tailored for specific applications.

Coupling the Alkaline-Surfactant-Polymer Technology and The Gelation Technology to Maximize Oil Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malcolm Pitts; Jie Qi; Dan Wilson

2005-10-01

Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or more efficient areal sweep efficiency for those with high permeability contrast ''thief zones''. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more oil than waterflooding from swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or those with thief zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. A priormore » fluid-fluid report discussed interaction of different gel chemical compositions and alkaline-surfactant-polymer solutions. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in the fluid-fluid analyses. Aluminum-polyacrylamide, flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9. Chromium acetate-polyacrylamide flowing and rigid flowing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid flowing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Chromium acetate-xanthan gum rigid gels are not stable to subsequent alkaline-surfactant-polymer solution injection. Resorcinol-formaldehyde gels were stable to subsequent alkaline-surfactant-polymer solution injection. When evaluated in a dual core configuration, injected fluid flows into the core with the greatest effective permeability to the injected fluid. The same gel stability trends to subsequent alkaline-surfactant-polymer injected solution were observed. Aluminum citrate-polyacrylamide, resorcinol-formaldehyde, and the silicate-polyacrylamide gel systems did not produce significant incremental oil in linear corefloods. Both flowing and rigid flowing chromium acetate-polyacrylamide gels and the xanthan gum-chromium acetate gel system produced incremental oil with the rigid flowing gel producing the greatest amount. Higher oil recovery could have been due to higher differential pressures across cores. None of the gels tested appeared to alter alkaline-surfactant-polymer solution oil recovery. Total waterflood plus chemical flood oil recovery sequence recoveries were all similar. Chromium acetate-polyacrylamide gel used to seal fractured core maintain fracture closure if followed by an alkaline-surfactant-polymer solution. Chromium acetate gels that were stable to injection of alkaline-surfactant-polymer solutions at 72 F were stable to injection of alkaline-surfactant-polymer solutions at 125 F and 175 F in linear corefloods. Chromium acetate-polyacrylamide gels maintained diversion capability after injection of an alkaline-surfactant-polymer solution in stacked; radial coreflood with a common well bore. Xanthan gum-chromium acetate gels maintained gel integrity in linear corefloods after injection of an alkaline-surfactant-polymer solution at 125 F. At 175 F, Xanthan gum-chromium acetate gels were not stable either with or without subsequent alkaline-surfactant-polymer solution injection. Numerical simulation demonstrated that reducing the permeability of a high permeability zone of a reservoir with gel improved both waterflood and alkaline-surfactant-polymer flood oil recovery. A Minnelusa reservoir with both A and B sand production was simulated. A and B sands are separated by a shale layer. A sand and B sand waterflood oil recovery was improved by 196,000 bbls when a gel was placed in the B sand. A sand and B sand alkaline-surfactant-polymer flood oil recovery was improved by 596,000 bbls when a gel was placed in the B sand. Alkaline-surfactant-polymer flood oil recovery improvement over a waterflood was 392,000 bbls. Placing a gel into the B sand prior to an alkaline-surfactant-polymer flood resulted in 989,000 bbl more oil than only water injection.« less

Structure Analysis of Jungle-Gym-Type Gels by Brownian Dynamics Simulation

NASA Astrophysics Data System (ADS)

Ohta, Noriyoshi; Ono, Kohki; Takasu, Masako; Furukawa, Hidemitsu

2008-02-01

We investigated the structure and the formation process of two kinds of gels by Brownian dynamics simulation. The effect of flexibility of main chain oligomer was studied. From our results, hard gel with rigid main chain forms more homogeneous network structure than soft gel with flexible main chain. In soft gel, many small loops are formed, and clusters tend to shrink. This heterogeneous network structure may be caused by microgels. In the low density case, soft gel shows more heterogeneity than the high density case.

Chiral bis(amino acid)- and bis(amino alcohol)-oxalamide gelators. Gelation properties, self-assembly motifs and chirality effects.

PubMed

Frkanec, Leo; Zinić, Mladen

2010-01-28

Bis(amino acid)- and bis(amino alcohol)oxalamide gelators represent the class of versatile gelators whose gelation ability is a consequence of strong and directional intermolecular hydrogen bonding provided by oxalamide units and lack of molecular symmetry due to the presence of two chiral centres. Bis(amino acid)oxalamides exhibit ambidextrous gelation properties, being capable to form gels with apolar and also highly polar solvent systems and tend to organise into bilayers or inverse bilayers in hydrogel or organic solvent gel assemblies, respectively. (1)H NMR and FTIR studies of gels revealed the importance of the equilibrium between the assembled network and smaller dissolved gelator assemblies. The organisation in gel assemblies deduced from spectroscopic structural studies are in certain cases closely related to organisations found in the crystal structures of selected gelators, confirming similar organisations in gel assemblies and in the solid state. The pure enantiomer/racemate gelation controversy is addressed and the evidence provided that rac-16 forms a stable toluene gel due to resolution into enantiomeric bilayers, which then interact giving gel fibres and a network of different morphology compared to its (S,S)-enantiomer gel. The TEM investigation of both gels confirmed distinctly different gel morphologies, which allowed the relationship between the stereochemical form of the gelator, the fibre and the network morphology and the network solvent immobilisation capacity to be proposed. Mixing of the constitutionally different bis(amino acid) and bis(amino alcohol)oxalamide gelators resulted in some cases in highly improved gelation efficiency denoted as synergic gelation effect (SGE), being highly dependent also on the stereochemistry of the component gelators. Examples of photo-induced gelation based on closely related bis(amino acid)-maleic acid amide and -fumaramide and stilbene derived oxalamides where gels form by irradiation of the solution of a non-gelling isomer and its photo-isomerisation into gelling isomer are provided, as well as examples of luminescent gels, gel-based fluoride sensors, LC-gels and nanoparticle-hydrogel composites.

THE MECHANISM OF THE INFLAMMATORY PROCESS : III. ELECTROPHORETIC MIGRATION OF INERT PARTICLES AND BLOOD CELLS IN GELATIN SOLS AND GELS WITH REFERENCE TO LEUCOCYTE EMIGRATION THROUGH THE CAPILLARY WALL.

PubMed

Abramson, H A

1928-07-20

1. Quartz particles and certain other particles move cataphoretically in certain soft gelatin gels, with the same velocity as in the sol. The speed is a function of the true viscosity of the sol or gel, and it is See PDF for Structure apparently not altered in these soft gels by the presence of gel structure. It is proportional to the applied difference of potential. 2. This finding is compatible with the fact that certain sols undergo gelation with no increase of the true viscosity although a marked change in the apparent viscosity takes place. 3. Red cells in soft gelatin-serum gels show a distinct difference in behavior. They migrate through the sol or gel with a speed that is about twice as great as the leucocytes and quartz particles, which latter particles migrate with the same velocity. This ratio has been found to hold for serum and plasma. The absolute velocities are comparatively slightly decreased by the presence of the gel. 4. In more concentrated or stiffer gels, leucocytes, red cells and quartz particles all move at first with the same velocity. By producing mechanical softening of these gels (shearing from cataphoretic movement of the micells within the cell) the red cells presently resume their previous property of independent migration through the gel. 5. The movements of particles in gelatin gels produced by a magnetic force or the force of gravity are of a different nature than those movements produced by cataphoresis. 6. The mechanical nature of obstruction to the cataphoretic migration of leucocytes and red cells in fibrin gels is briefly described. 7. The correlation of cataphoresis of microscopic particles in gels with the order of magnitude and nature of the potential differences in the capillary wall, lends additional evidence to the theory that polymorphonuclear leucocyte emigration and migration are dependent upon these potential differences.

Uptake of divalent ions (Mn+2 and Ca+2) by heat-set whey protein gels.

PubMed

Oztop, Mecit H; McCarthy, Kathryn L; McCarthy, Michael J; Rosenberg, Moshe

2012-02-01

Divalent salts are used commonly for gelation of polymer molecules. Calcium, Ca(+2), is one of the most common divalent ions that is used in whey protein gels. Manganese, Mn(+2), is also divalent, but paramagnetic, enhancing relaxation decay rates in magnetic resonance imaging (MRI) and can be used as a probe to understand the behavior of Ca(+2) in whey protein gels. The objective of this study was to investigate the diffusion of Ca(+2) and Mn(+2) ions in heat-set whey protein gels by using MRI and nuclear magnetic resonance (NMR) relaxometry. Whey protein gels were immersed in solutions containing MnCl(2) and CaCl(2) at neutral pH. Images obtained with gels immersed in MnCl(2) solution revealed a relaxation sink region in the gel's surface and the thickness of the region increased with time. These "no signal" regions in the MR images were attributed to uptake of Mn(+2) by the gel. Results obtained with CaCl(2) solution indicated that since Ca(+2) did not have the paramagnetic effect, the regions where Ca(+2) diffused into the gel exhibited a slight decrease in signal intensity. The relaxation spectrums exhibited 3 populations of protons, for gels immersed in MnCl(2) solution, and 2 populations for gels in CaCl(2) solution. No significant change in T(2) distributions was observed for the gels immersed in CaCl(2) solution. The results demonstrated that MRI and NMR relaxometry can be used to understand the diffusion of ions into the whey protein gel, which is useful for designing gels of different physical properties for controlled release applications. Design of food systems for delivery of bioactive compounds requires knowledge of diffusion rates and structure. Utilizing magnetic resonance imaging the diffusion rates of ions can be measured. Relaxation spectra could yield information concerning molecular interactions. © 2012 Institute of Food Technologists®

Local Controlled Release of Polyphenol Conjugated with Gelatin Facilitates Bone Formation

PubMed Central

Honda, Yoshitomo; Tanaka, Tomonari; Tokuda, Tomoko; Kashiwagi, Takahiro; Kaida, Koji; Hieda, Ayato; Umezaki, Yasuyuki; Hashimoto, Yoshiya; Imai, Koichi; Matsumoto, Naoyuki; Baba, Shunsuke; Shimizutani, Kimishige

2015-01-01

Catechins are extensively used in health care treatments. Nevertheless, there is scarce information about the feasibility of local administration with polyphenols for bone regeneration therapy, possibly due to lack of effective delivery systems. Here we demonstrated that the epigallocatechin-3-gallate-conjugated gelatin (EGCG/Gel) prepared by an aqueous chemical synthesis using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-morpholinium chloride (DMT-MM) gradually disintegrated with time and facilitated bone formation in a critical size defect of a mouse calvaria. Conjugation of EGCG with the Gel generated cross-linking between the two molecules, thereby leading to a retardation of the degradation of the EGCG/Gel and to a delayed release of EGCG. The prepared EGCG/Gels represented significant osteogenic capability compared with that of the uncross-linked Gel and the cross-linked Gel with uncombined-EGCG. In vitro experiments disclosed that the EGCG/Gel induced osteoblastogenesis of a mouse mesenchymal stem cell line (D1 cells) within 14 days. Using fluorescently-labeled EGCG/Gel, we found that the fraction of EGCG/Gel adsorbed onto the cell membrane of the D1 cells possibly via a Gel-cell interaction. The interaction might confer the long-term effects of EGCG on the cells, resulting in a potent osteogenic capability of the EGCG/Gel in vivo. These results should provide insight into local controlled release of polyphenols for bone therapy. PMID:26110386

Pilot randomized trial for treatment of bacterial vaginosis using in situ forming metronidazole vaginal gel.

PubMed

Shaaban, Omar M; Fetih, Gihan N; Abdellah, Noura H; Ismail, Saeyd; Ibrahim, Maggie A; Ibrahim, El-sayed A

2011-07-01

To compare the efficacy of a novel vaginal delivery system for metronidazole (0.8% MTZ in situ gel) versus a conventional MTZ vaginal gel product in the treatment of bacterial vaginosis (BV). All consecutive patients who presented to a tertiary care hospital with symptoms suggestive of BV were approached to participate in the study. Forty-two eligible participants were randomly assigned to either MTZ in situ gel or a conventional vaginal gel product twice daily for 5 days. All participants were re-examined after one and 4 weeks of the beginning of treatment to ensure cure of infection and any side-effects. Demographic criteria of the participants were comparable in the two treatment groups. The cure rate after one week from the treatment was 85% in the in situ gel group and 71.4% in the conventional vaginal gel group (P = 0.294), while after 4 weeks, the cure rate showed significant difference in the in situ gel group as compared to the conventional vaginal gel group (16/20 [80%]) and (9/19 [47.4%]), respectively (P = 0.034). Pilot testing showed that in situ MTZ vaginal gel is more effective than the conventional vaginal gel for long-term cure of BV. These findings suggest a novel and efficient long-term treatment of BV. © 2011 The Authors. Journal of Obstetrics and Gynaecology Research © 2011 Japan Society of Obstetrics and Gynecology.

Binary Supramolecular Gel of Achiral Azobenzene with a Chaperone Gelator: Chirality Transfer, Tuned Morphology, and Chiroptical Property.

PubMed

Ji, Lukang; Ouyang, Guanghui; Liu, Minghua

2017-10-31

Binary supramolecular gels based on achiral azobenzene derivatives and a chiral chaperone gelator, long-alkyl-chain-substituted L-Histidine (abbreviated as LHC18) that could assist many nongelling acids in forming gels, were investigated in order to fabricate the chiroptical gel materials in a simple way. It was found that although the carboxylic acid-terminated achiral azobenzene derivatives could not form gels in any solvents, when mixed with LHC18 they formed the co-gels and self-assembled into various morphologies ranging from nanotubes and loose nanotubes to nanosheets, depending on the substituent groups on the azobenzene moiety. The ether linkage and the number of carboxylic acid groups attached to the azobenzene moiety played important roles. Upon gel formation, the localized molecular chirality in LHC18 could be transferred to the azobenzene moiety. Combined with the trans-cis isomerization of the azobenzene, optically and chiroptically reversible gels were generated. It was found that the gel based on azobenzene with two carboxylic acid groups and ether linkages showed clear optical reversibility but less chiroptical reversibility, whereas the gel based on azobenzene with one carboxylic acid and an ether linkage showed both optical and chiroptical reversibility. Thus, new insights into the relationship among the molecular structures of the azobenzene, self-assembled nanostructures in the gel and the optical and chiroptical reversibility were disclosed.

Influence of remineralizing gels on bleached enamel microhardness in different time intervals.

PubMed

Borges, Alessandra Bühler; Yui, Karen Cristina Kazue; D'Avila, Thaís Corrêa; Takahashi, Camila Lurie; Torres, Carlos Rocha Gomes; Borges, Alexandre Luis Souto

2010-01-01

This study evaluated the influence of bleaching gel pH, the effect of applying remineralizing gels after bleaching and the effect of artificial saliva on enamel microhardness. Seventy bovine incisors were divided into three groups: Group 1 (n=10) received no bleaching procedure (control); Group 2 was bleached with a 35% hydrogen peroxide neutral gel (n=30) and Group 3 was bleached with a 35% hydrogen peroxide acid gel (n=30). Each experimental group was subdivided into three groups (n=10) according to the post-bleaching treatment: storage in artificial saliva, application of a fluoride gel and application of a combination of calcium and fluoride gel. The specimens were stored in artificial saliva for 7, 15 and 30 days and enamel microhardness was evaluated. The Vickers microhardness data were analyzed by three-way RM ANOVA, which revealed a significant difference only for treatment factor. The Tukey's test showed that the groups bleached followed by no additional treatment exhibited microhardness means significantly lower than the bleached groups treated with remineralizing gels. The Dunnet's test showed a significant difference only for the group bleached with acid gel without remineralizing treatment compared to the control group measured immediately after bleaching. It was concluded that acid bleaching gel significantly reduced enamel microhardness and that use of remineralizing gels after bleaching can significantly enhance the microhardness of bleached enamel.

Characterization of partially hydrolyzed OCP crystals deposited in a gelatin matrix as a scaffold for bone tissue engineering

NASA Astrophysics Data System (ADS)

Ezoe, Yushi; Anada, Takahisa; Yamazaki, Hajime; Handa, Takuto; Kobayashi, Kazuhito; Takahashi, Tetsu; Suzuki, Osamu

2015-03-01

The present study was designed to investigate how hydrolysis of octacalcium phosphate (OCP) into hydroxyapatite is affected by the presence of gelatin (Gel) molecules and how osteoblastic cells respond to the resultant OCP hydrolyzate/Gel composites as the hydrolysis advances. OCP was prepared from a solution containing calcium and phosphate ions and Gel molecules, having a composition to produce a 40 wt% OCP as a final co-precipitate as the OCP/Gel. The precipitate was further incubated up to 40 h to advance the hydrolysis of OCP. These precipitates were processed to mold OCP/Gel sponges through lyophilization and dehydrothermal treatment. Chemical analysis, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and selected area electron diffraction revealed that the hydrolysis of OCP/Gel composite in hot water advanced in a time-dependent manner and faster than hydrolysis of OCP alone. The effect of Gel on the OCP hydrolysis was further examined in the presence of distinct concentrations of Gel molecules in hot water, showing that the Gel enhanced the hydrolysis as the concentration increased. Proliferation and differentiation of mouse bone marrow stromal ST-2 cells on the hydrolyzed OCP/Gel composites were compatible with Gel sponge alone after 21 days of culture, suggesting that these composites could be a candidate as a scaffold in bone tissue engineering.

Photo-induced locomotion of chemo-responsive polymer gels

NASA Astrophysics Data System (ADS)

Dayal, Pratyush; Kuksenok, Olga; Balazs, Anna C.

2009-03-01

The need to translate chemical energy into a mechanical response, a characteristic of many biological processes, has motivated the study of stimuli-responsive polymer gels. Recently, it has been shown experimentally that by coupling the mechanical properties of the gel with the Belousov-Zhabotinsky (BZ) reaction it is possible to induce self-sustained oscillations in the gel. One of the means for controlling these chemical oscillations is using light as an external stimulus. To study the effect of light on the mechanical behavior of the gel, we use our recently developed a 3D gel lattice spring model (gLSM) which couples the BZ reaction kinetics to the gel dynamics. In this model, the polymer-solvent interactions were taken into account by adding a coupling term to the Flory-Huggins free energy. By virtue of this coupling term, the swelling---de-swelling behavior of the gel was captured in 3D. In order to include the effect of the polymer on the reaction kinetics, the Oregonator model for the photo-sensitive BZ reaction was also modified. Using gLSM model, we probed the effect of non-uniform light irradiation on the gel dynamics. We were able to manipulate the direction and velocity of locomotion of the gel using light as a control parameter. This ability to control the movement of the gel can be utilized in a variety of applications, ranging from bio-actuators to controlled drug release systems.

Physicochemical characterization of diclofenac sodium-loaded poloxamer gel as a rectal delivery system with fast absorption.

PubMed

Yong, Chul Soon; Sah, Hongkee; Jahng, Yurngdong; Chang, Hyeun Wook; Son, Jong-Keun; Lee, Seung Ho; Jeong, Tae Cheon; Rhee, Jong-Dal; Baek, Suk Hwan; Kim, Chong-Kook; Choi, Han-Gon

2003-05-01

Rectal poloxamer gel systems composed of poloxamers and bioadhesive polymers were easy to administer to the anus and were mucoadhesive to the rectal tissues without leakage after the dose. However, a poloxamer gel containing diclofenac sodium could not be developed using bioadhesive polymers, since the drug was precipitated in this preparation. To develop a poloxamer gel using sodium chloride instead of bioadhesive polymers, the physicochemical properties such as gelation temperature, gel strength, and bioadhesive force of various formulations composed of diclofenac sodium, poloxamers, and sodium chloride were investigated. Furthermore, the pharmacokinetic study of diclofenac sodium delivered by the poloxamer gel was performed. Diclofenac sodium significantly increased the gelation temperature and weakened the gel strength and bioadhesive force, while sodium chloride did the opposite. The poloxamer gels with less than 1.0% sodium chloride, in which the drug was not precipitated, were inserted into the rectum without difficulty and leakage, and were retained in the rectum of rats for at least 6 hr. Furthermore, poloxamer gel gave significantly higher initial plasma concentrations and faster Tmax of diclofenac sodium than did solid suppository, indicating that drug from poloxamer gel could be absorbed faster than that from the solid one in rats. Our results suggested that a rectal poloxamer gel system with sodium chloride and poloxamers was a more physically stable, convenient, and effective rectal dosage form for diclofenac sodium.

Effects of a wax organogel and alginate gel complex on holy basil (Ocimum sanctum) in vitro ruminal dry matter disappearance and gas production.

PubMed

Templeman, James R; Rogers, Michael A; Cant, John P; McBride, Brian W; Osborne, Vern R

2018-02-20

The objectives of this study were to: (a) select an ideal organogel for the oil phase of a novel gel encapsulation technology, (b) optimize the formulation of an organogel and sodium alginate-based gel complex, and (c) examine the rumen protective ability of the gel by measuring 48-h in vitro ruminal dry matter disappearance and gas production from encapsulated dried and ground holy basil leaves. A rice-bran wax and canola oil organogel was selected for the oil phase of the gel complex as this combination had a 48-h dry matter disappearance of 6%, the lowest of all organogels analyzed. The gel complex was formulated by homogenizing the organogel with a sodium alginate solution to create a low-viscosity oil-in-water emulsion. Average dry matter disappearance of gel-encapsulated holy basil was 19%, compared to 42% for the free, unprotected holy basil. However, gel encapsulation of holy basil stimulated gas production. Specifically, gas production of encapsulated holy basil was four times higher than the treatment with holy basil added on top of the gel prior to incubation rather than encapsulated within the gel. Although the gel itself was highly degradable, it is speculated encapsulation thwarted holy basil's antimicrobial activity. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Adipose Extracellular Matrix/Stromal Vascular Fraction Gel Secretes Angiogenic Factors and Enhances Skin Wound Healing in a Murine Model.

PubMed

Sun, Mingliang; He, Yunfan; Zhou, Tao; Zhang, Pan; Gao, Jianhua; Lu, Feng

2017-01-01

Mesenchymal stem cells are an attractive cell type for cytotherapy in wound healing. The authors recently developed a novel, adipose-tissue-derived, injectable extracellular matrix/stromal vascular fraction gel (ECM/SVF-gel) for stem cell therapy. This study was designed to assess the therapeutic effects of ECM/SVF-gel on wound healing and potential mechanisms. ECM/SVF-gel was prepared for use in nude mouse excisional wound healing model. An SVF cell suspension and phosphate-buffered saline injection served as the control. The expression levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and monocyte chemotactic protein-1 (MCP-1) in ECM/SVF-gel were analyzed at different time points. Angiogenesis (tube formation) assays of ECM/SVF-gel extracts were evaluated, and vessels density in skin was determined. The ECM/SVF-gel extract promoted tube formation in vitro and increased the expression of the angiogenic factors VEGF and bFGF compared with those in the control. The expression of the inflammatory chemoattractant MCP-1 was high in ECM/SVF-gel at the early stage and decreased sharply during the late stage of wound healing. The potent angiogenic effects exerted by ECM/SVF-gel may contribute to the improvement of wound healing, and these effects could be related to the enhanced inflammatory response in ECM/SVF-gel during the early stage of wound healing.

Neural stem cell proliferation and differentiation in the conductive PEDOT-HA/Cs/Gel scaffold for neural tissue engineering.

PubMed

Wang, Shuping; Guan, Shui; Xu, Jianqiang; Li, Wenfang; Ge, Dan; Sun, Changkai; Liu, Tianqing; Ma, Xuehu

2017-09-26

Engineering scaffolds with excellent electro-activity is increasingly important in tissue engineering and regenerative medicine. Herein, conductive poly(3,4-ethylenedioxythiophene) doped with hyaluronic acid (PEDOT-HA) nanoparticles were firstly synthesized via chemical oxidant polymerization. A three-dimensional (3D) PEDOT-HA/Cs/Gel scaffold was then developed by introducing PEDOT-HA nanoparticles into a chitosan/gelatin (Cs/Gel) matrix. HA, as a bridge, not only was used as a dopant, but also combined PEDOT into the Cs/Gel via chemical crosslinking. The PEDOT-HA/Cs/Gel scaffold was used as a conductive substrate for neural stem cell (NSC) culture in vitro. The results demonstrated that the PEDOT-HA/Cs/Gel scaffold had excellent biocompatibility for NSC proliferation and differentiation. 3D confocal fluorescence images showed cells attached on the channel surface of Cs/Gel and PEDOT-HA/Cs/Gel scaffolds with a normal neuronal morphology. Compared to the Cs/Gel scaffold, the PEDOT-HA/Cs/Gel scaffold not only promoted NSC proliferation with up-regulated expression of Ki67, but also enhanced NSC differentiation into neurons and astrocytes with up-regulated expression of β tubulin-III and GFAP, respectively. It is expected that this electro-active and bio-active PEDOT-HA/Cs/Gel scaffold will be used as a conductive platform to regulate NSC behavior for neural tissue engineering.

Antioxidant effect of green tea on polymer gel dosimeter

NASA Astrophysics Data System (ADS)

Samuel, E. J. J.; Sathiyaraj, P.; Deena, T.; Kumar, D. S.

2015-01-01

Extract from Green Tea (GTE) acts as an antioxidant in acrylamide based polymer gel dosimeter. In this work, PAGAT gel was used for investigation of antioxidant effect of GTE.PAGAT was called PAGTEG (Polyacrylamide green tea extract gel dosimeter) after adding GTE. Free radicals in water cause pre polymerization of polymer gel before irradiation. Polyphenols from GTE are highly effective to absorb the free radicals in water. THPC is used as an antioxidant in polymer gel dosimeter but here we were replaced it by GTE and investigated its effect by spectrophotometer. GTE added PAGAT samples response was lower compared to THPC added sample. To increase the sensitivity of the PAGTEG, sugar was added. This study confirmed that THPC was a good antioxidant for polymer gel dosimeter. However, GTE also can be used as an antioxidant in polymer gel if use less quantity (GTE) and add sugar as sensitivity enhancer.

Anisotropic Mechanical Properties of Magnetically Aligned Fibrin Gels Measured by Magnetic Resonance Elastography

PubMed Central

Namani, Ravi; Wood, Matthew D.; Sakiyama-Elbert, Shelly E.; Bayly, Philip V.

2009-01-01

The anisotropic mechanical properties of magnetically aligned fibrin gels were measured by magnetic resonance elastography (MRE) and by a standard mechanical test: unconfined compression. Soft anisotropic biomaterials are notoriously difficult to characterize, especially in vivo. MRE is well-suited for efficient, non-invasive, and nondestructive assessment of shear modulus. Direction-dependent differences in shear modulus were found to be statistically significant for gels polymerized at magnetic fields of 11.7T and 4.7T compared to control gels. Mechanical anisotropy was greater in the gels polymerized at the higher magnetic field. These observations were consistent with results from unconfined compression tests. Analysis of confocal microscopy images of gels showed measurable alignment of fibrils in gels polymerized at 11.7T. This study provides direct, quantitative measurements of the anisotropy in mechanical properties that accompanies fibril alignment in fibrin gels. PMID:19656516

Hyper alginate gel microbead formation by molecular diffusion at the hydrogel/droplet interface.

PubMed

Hirama, Hirotada; Kambe, Taisuke; Aketagawa, Kyouhei; Ota, Taku; Moriguchi, Hiroyuki; Torii, Toru

2013-01-15

We report a simple method for forming monodispersed, uniformly shaped gel microbeads with precisely controlled sizes. The basis of our method is the placement of monodispersed sodium alginate droplets, formed by a microfluidic device, on an agarose slab gel containing a high-osmotic-pressure gelation agent (CaCl(2) aq.): (1) the droplets are cross-linked (gelated) due to the diffusion of the gelation agent from the agarose slab gel to the sodium alginate droplets and (2) the droplets simultaneously shrink to a fraction of their original size (<100 μm in diameter) due to the diffusion of water molecules from the sodium alginate droplets to the agarose slab gel. We verified the mass transfer mechanism between the droplet and the agarose slab gel. This method circumvents the limitations of gel microbead formation, such as the need to prepare microchannels of various sizes, microchannel clogging, and the deformation of the produced gel microbeads.

Gels with exceptional thermal stability formed by bis(amino acid) oxalamide gelators and solvents of low polarity.

PubMed

Makarević, Janja; Jokić, Milan; Frkanec, Leo; Katalenić, Darinka; Zinić, Mladen

2002-10-07

Some bis (amino acid) oxalamide gelators form common thermo-reversible gels with various organic solvents but also gels of exceptional thermal stability with some solvents of medium and low polarity; the latter gels can be heated up to 50 degrees C higher temperatures than the bp of the solvent without apparent gel-to-sol transition.

A clinical evaluation comparing two H2O2 concentrations used with a light-assisted chairside tooth whitening system.

PubMed

Ward, Marilyn; Felix, Heather

2012-04-01

The purpose of this study was to assess the efficacy of two different BriteSmile hydrogen peroxide (H2O2) gels in a split-arch protocol for whitening teeth in a clinical setting when used in conjunction with a BriteSmile BS4000 lamp. Fifteen subjects were enrolled into a single-center clinical trial. The efficacy of the BriteSmile BS4000 lamp using both 15% H2O2 and 25% H2O2 gel formulations was tested. Study subjects were concurrently exposed to the whitening lamp with the 15% H2O2 gel placed on half of their anterior teeth and the 25% H2O2 gel on the other half for a total light and gel exposure of 60 minutes. The clinical data collected were shade score, gingival health, and dentinal hypersensitivity self-assessment. Changes in tooth shade were better for subjects exposed to the 25% gel and the dental whitening lamp (average 8.0 shade changes) compared to subjects exposed to the 15% gel and dental whitening lamp (average 7.6 shade changes) immediately after treatment. The same held true at the 7-day follow-up (25% gel average 7.4 shade changes versus 15% gel average 7.3 shade changes). However, these differences were not statistically significant. No reports of irritation of gingival soft tissues were documented. The relative changes in mean sensitivity scores were similar for both groups with no significant differences in mean sensitivity scores between the groups. Both concentrations of H2O2 gel and the whitening lamp combined gave study subjects an average of 8.0 (25% gel) and 7.6 (15% gel) shade changes immediately after treatment. The 7-day follow-up examination resulted in a regression of lightest to an average of 7.4 (25% gel) and 7.3 (15% gel). It was concluded that the use of the chairside whitening light and either 15% or 25% hydrogen peroxide gel is safe and effective for whitening teeth in 1 hour.

Coupling the Alkaline-Surfactant-Polymer Technology and The Gelation Technology to Maximize Oil Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malcolm Pitts; Jie Qi; Dan Wilson

2005-12-01

Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or reservoirs with different sand lenses with high permeability contrast. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more crude oil than waterflooding from swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or reservoirs with high permeability contrast zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. Fluid-fluid interaction withmore » different gel chemical compositions and alkaline-surfactant-polymer solution with pH values ranging from 9.2 to 12.9 have been tested. Aluminum-polyacrylamide gels are not stable to alkaline-surfactant-polymer solutions at any pH. Chromium-polyacrylamide gels with polymer to chromium ion ratios of 25 or greater were stable to alkaline-surfactant-polymer solutions if solution pH was 10.6 or less. When the polymer to chromium ion was 15 or less, chromium-polyacrylamide gels were stable to alkaline-surfactant-polymer solutions with pH values up to 12.9. Chromium-xanthan gum gels were stable to alkaline-surfactant-polymer solutions with pH values of 12.9 at the polymer to chromium ion ratios tested. Silicate-polyacrylamide, resorcinol-formaldehyde, and sulfomethylated resorcinol-formaldehyde gels were also stable to alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Iron-polyacrylamide gels were immediately destroyed when contacted with any of the alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in the fluid-fluid analyses with the exception of the xanthan gum-chromium acetate gels. Aluminum-polyacrylamide flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9, either in linear corefloods or in dual separate radial core, common manifold corefloods. Chromium acetate-polyacrylamide flowing and rigid tonguing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid tonguing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Chromium acetate gels were stable to injection of alkaline-surfactant-polymer solutions at 72 F, 125 F and 175 F in linear corefloods. Chromium acetate-polyacrylamide gels maintained diversion capability after injection of an alkaline-surfactant-polymer solution in stacked; radial coreflood with a common well bore. Chromium acetate-polyacrylamide gel used to seal fractured core maintain fracture closure if followed by an alkaline-surfactant-polymer solution. Chromium acetatexanthan gum rigid gels are not stable to subsequent alkaline-surfactant-polymer solution injection at 72, 125, and 175 F. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Resorcinol-formaldehyde gels were stable to subsequent alkaline-surfactant-polymer solution injection. When evaluated in a dual core configuration, injected fluid flows into the core with the greatest effective permeability to the injected fluid. The same gel stability trends to subsequent alkaline-surfactant-polymer injected solution were observed. Aluminum citrate-polyacrylamide, resorcinol-formaldehyde, and the silicate-polyacrylamide gel systems did not produce significant incremental oil in linear corefloods. Both flowing and rigid tonguing chromium acetate-polyacrylamide gels and the xanthan gum-chromium acetate gel system produced incremental oil with the rigid tonguing gel producing the greatest amount. Higher oil recovery could have been due to higher differential pressures across cores. Aluminum citrate-polyacrylamide gels, chromium acetate-polyacrylamide gels, silicate-polymer, and chromium-xanthan gum gels did not alter an alkaline-surfactant-polymer solution's ability to produce incremental oil. Incremental oil was reduced with the resorcinol-formaldehyde gel system. Total waterflood plus chemical flood oil recovery sequence recoveries were generally similar. Performance and produced polymer evaluation of four alkaline-surfactant-polymer projects concluded that only one of the projects could have benefited from combining the alkaline-surfactant-polymer and gelation technologies. Cambridge, the 1993 Daqing, Mellott Ranch, and the Wardlaw alkaline-surfacant-polymer floods were studied. An initial gel treatment followed by an alkaline-surfactant-polymer flood in the Wardlaw field would have been a benefit due to reduction of fracture flow.« less

Topical Application of a Silicone Gel Sheet with Verapamil Microparticles in a Rabbit Model of Hypertrophic Scar.

PubMed

Rha, Eun Young; Kim, Yun Ho; Kim, Tae-Jung; Yoo, Gyeol; Rhie, Jong Won; Kim, Hyun-Jung; Park, Il-Kyu

2016-01-01

The authors developed a novel treatment based on the topical application of a silicone gel sheet containing verapamil microparticles. The ability of these silicone gel sheets to inhibit hypertrophic scar in a rabbit ear wound model was examined. Ten New Zealand White rabbits with a total of 80 wounds in both ears were used in this study. The rabbits were divided into five groups (control; silicone gel sheet; and silicone gel sheet plus 0.25, 2.5, and 25 mg of verapamil per gram). Histopathologic findings were quantified. The mean scar elevation index, fibroblast counts, and capillary counts differed significantly among the five groups (p < 0.05). The median scar elevation index was significantly lower in the silicone gel sheet plus 2.5 mg of verapamil per gram group than in the silicone gel sheet group (1.2 versus 2.2). The median number of fibroblasts was significantly lower in the silicone gel sheet plus 0.25 mg of verapamil per gram group than in the silicone gel sheet group (172.5 versus 243). In the median number of capillary lumina, there was no significant difference between the silicone gel sheet group and the silicone gel sheet plus 0.25, 2.5, and 25 mg of verapamil per gram groups (28.5, 18, 20, and 18, respectively). Topical application of a silicone gel sheet with verapamil microparticles may be a novel, effective treatment method for hypertrophic scar, but its safety and efficacy in humans must be tested in clinical trials.

Effect of 5% benzocaine gel on relieving pain caused by fixed orthodontic appliance activation. A double-blind randomized controlled trial.

PubMed

Eslamian, L; Gholami, H; Mortazavi, S A R; Soheilifar, S

2016-11-01

To compare the effectiveness of 5% benzocaine gel and placebo gel on reducing pain caused by fixed orthodontic appliance activation. Thirty subjects (15-25 years) undergoing fixed orthodontics. A randomized, double-blind, placebo-controlled and cross-over clinical trial study was conducted. Subjects were asked to apply a placebo gel and 5% benzocaine gel, exchangeable in two consecutive appointments, twice a day for 3 days and mark their level of pain on a VAS scale. The pain severity was evaluated by means of Mann-Whitney U-test for comparing two gel groups, Kruskal-Wallis nonparametric test for overall differences and post hoc test of Dunnett for paired multiple comparisons. p-value was assigned <0.05. The overall mean value of pain intensity for benzocaine and placebo gels was 0.89 and 1.15, respectively. The Mann-Whitney U-test indicated that there was no significant difference between overall pain in both groups (mean difference = 0.258 p ˂ 0.21). For both groups, pain intensity was significantly lower at 2, 6 and 24 h compared with pain experienced at days 2, 3 and 7. Benzocaine gel caused a decrease in pain perception at 2 h compared with placebo gel. Peak pain intensity was at 2 h for placebo gel and at 6 h for benzocaine gel, followed by a decline in pain perception from that point to day 7 for both gels. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Gluten gel and film properties in the presence of cysteine and sodium alginate.

PubMed

Yuno-Ohta, Naoko; Yamada, Mariko; Inomata, Masako; Konagai, Hiromi; Kataoka, Tomomi

2009-08-01

Wheat flour has an ability of forming dough by mixing with water, which exhibits a rheological property required for making bread. The major protein is gluten, which is a valuable protein material for food industry. In this study, gluten protein gels and films were formed with cysteine and sodium alginate. Adding cysteine improved gel and film properties (stress relaxation behavior, bending strength). The gel containing 0.01 M cysteine had a longer relaxation time and was more rigid than the gel without cysteine. Although adding sodium alginate to the gluten suspension containing cysteine improved the water-holding ability and homogeneity of the gel network, the film from this gel was more brittle than the gluten film with cysteine alone. Microstructural observations of the gels and films with scanning electron microscopy suggested that water evaporation was more heterogeneous from the gel containing sodium alginate than from the gel with cysteine alone. Fourier transform-infrared (FT-IR) analysis during film formation suggested that the presence of cysteine encourages interaction between gluten molecules and results in intermolecular beta-sheet formation in earlier stages than in the no additive condition. FT-IR results also suggested that the combined effect of sodium alginate and cysteine on the protein secondary structure was remarkably different from that of cysteine alone. Our results suggest that addition of a suitable amount of cysteine (0.01 M) and heat treatment to 80 degrees C during gluten gel and film formation induces a homogenous network in the gel and film by regulating disulfide-sulfide interactions.

Effect of Concentration of Collagen Gel on Functional Activity of Bone Marrow Mesenchymal Stromal Cells.

PubMed

Nashchekina, Yu A; Yudintceva, N M; Nikonov, P O; Ivanova, E A; Smagina, L V; Voronkina, I V

2017-05-01

Collagen I gels with protein concentrations of 1, 2, and 3.5 mg/ml were prepared and embedded in a porous polylactide scaffold to reduce their contraction. Concentration of the gel did not affect its degradation. Collagen gels promoted the formation of cell networks. The cells in the collagen gel with a concentration of 1 mg/ml embedded in polylactide scaffold had elongated spindle-like shape, in contrast to flattened cells in collagen gel of the same concentration not embedded in the scaffold. Stabilization of the collagen gel in the polylactide scaffold promoted active synthesis of laminin and fibronectin by cells as soon as on day 5 of culturing in comparison with that in free collagen substrate.

Gel sealants for the mitigation of spontaneous heatings in coal mines. Report of investigations/1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miron, Y.

1995-12-31

The U.S. Bureau of Mines evaluated three sealant systems for this purpose, bentonite-water mixtures, silicate gel, and guar gum gels. The guar gum-based gel was the only sealant that possessed the desired properties of elasticity, ease of preparation, adaptability to the mine, and a long life. In addition, since the gel consists mostly of water, it could quench or cool nearby heatings. Optimal formulations were determined in laboratory tests, and then tested in the U.S. Bureau of Mines` Safety Research Coal Mine. Two formulations resulted in stable gels that lasted for at least 12 months in the mine. Semi-continuous preparationmore » of gel using an eductor was evaluated and appears feasible.« less

Ultrapure glass optical waveguide development in microgravity by the sol-gel process

NASA Technical Reports Server (NTRS)

Mukherjee, S. P.; Holman, R. A.

1981-01-01

Multicomponent, homogeneous, noncrystalline oxide gels can be prepared by the sol-gel process and these gels are promising starting materials for melting glasses in the space environment. The sol-gel process referred to here is based on the polymerization reaction of alkoxysilane with other metal alkoxy compounds or suitable metal salts. Many of the alkoxysilanes or other metal alkoxides are liquids and thus can be purified by distillation. The use of gels offers several advantages such as high purity and lower melting times and temperatures. The sol-gel process is studied for utilization in the preparation of multicomponent ultrapure glass batches for subsequent containerless melting of the batches in space to prepare glass blanks for optical waveguides.

Development of bufferless gel electrophoresis chip for easy preparation and rapid DNA separation.

PubMed

Oleksandrov, Sergiy; Aman, Abdurazak; Lim, Wanyoung; Kim, Younghee; Bae, Nam Ho; Lee, Kyoung G; Lee, Seok Jae; Park, Sungsu

2018-02-01

This work presents a handy, fast, and compact bufferless gel electrophoresis chip (BGEC), which consists of precast agarose gel confined in a disposable plastic body with electrodes. It does not require large volumes of buffer to fill reservoirs, or the process of immersing the gel in the buffer. It withstands voltages up to 28.4 V/cm, thereby allowing DNA separation within 10 min with a similar separation capability to the standard gel electrophoresis. The results suggest that our BGEC is highly suitable for in situ gel electrophoresis in forensic, epidemiological settings and crime scenes where standard gel electrophoresis equipment cannot be brought in while quick results are needed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Verification on the Dose Profile Variation of a 3-D—NIPAM Polymer Gel Dosimeter

NASA Astrophysics Data System (ADS)

Hsieh, Bor-Tsung; Wu, Jay; Chang, Yuan-Jen

2013-04-01

A gel dosimeter is a three-dimensional (3-D) device that is used in radiotherapy. It is more efficient than traditional one-dimensional and two-dimensional dosimeters because it can be used in complicated radiation therapy applications. However, the achievement of temporal and spatial stabilities for gel dosimeters remains challenging in clinical applications because the fabrication process affects the polymerization reaction during irradiation. This study investigated the dose profile variation of an N-isopropyl acrylamide (NIPAM) polymer gel dosimeter by using the 3-D optical computed tomography scanner OCTOPUSTM 10X (MGS Research Inc.). Two acrylic containers (diameter=10, height=10, and diameter=15, height=15cm ) filled with polymer gel (gelatin: 5%, NIPAM: 5%, Bis: 3%, THPC: 5 mM) were irradiated by using intensity-modulated radiotherapy (SIEMENS Oncor Impression, 6 MV Photo beam). The treatment field was a 3 cm 3 cm square field, and the prescribed dose was 5 Gy. The results of the reconstruction line profile showed that the uncertainty of non-irradiated gel is less than 1.3% when a container with 10 cm diameters cooled in a refrigerator with a water bath. The maximum uncertainties of the irradiated gel at 24 h, 48 h, and 72 h post-irradiation were 2.9%, 2.9%, and 3.1%, respectively. However, the maximum uncertainty of the non-irradiated gel dosimeter increased to 3% when a container with 15 cm diameter was cooled in the same refrigerator. After irradiation, the maximum uncertainties of the irradiated gel at 24 h, 48 h, and 72 h post-irradiation were 13.1%, 13.7%, and 12.95%, respectively. The uncertainty differences for gels at different container sizes were attributed to the different cooling rates that were applied to the gels. The time required for large gel containers to cool in the refrigerator was more than 10 h, whereas the cooling process only took 4.2 h for gels in a small container. The time difference produced different temperature histories for gels and may result in changes in gel sensitivity. Given the thermally induced pre-radiation polymerization, the time difference resulted in a deviation in dose profiles. This study reports that thermal control during gel preparation should be carefully performed for clinical applications to achieve a more accurate dose distribution in 3-D image reconstruction.

The characteristics of bacterial nanocellulose gel releasing silk sericin for facial treatment.

PubMed

Aramwit, Pornanong; Bang, Nipaporn

2014-12-09

Recently, naturally derived facial masks with beneficial biological properties have received increasing interest. In this study, silk sericin-releasing bacterial nanocellulose gel was developed to be applied as a bioactive mask for facial treatment. The silk sericin-releasing bacterial nanocellulose gel produced at a pH of 4.5 had an ultrafine and extremely pure fiber network structure. The mechanical properties and moisture absorption ability of the gel were improved, compared to those of the commercially available paper mask. Silk sericin could be control-released from the gel. A peel test with porcine skin showed that the gel was less adhesive than the commercially available paper mask, which would be removed from the face more easily without pain. The in vitro cytotoxicity test showed that the gel was not toxic to L929 mouse fibroblast and HaCaT human keratinocyte cells. Furthermore, when implanted subcutaneously and evaluated according to ISO10993-6 standard, the gel was not irritant to tissue. The silk sericin-releasing bacterial nanocellulose gel had appropriate physical and biological properties and safety for the facial treatment application.

Efficacy of topical azelaic acid gel in the treatment of mild-moderate acne vulgaris.

PubMed

Iraji, Fariba; Sadeghinia, Ali; Shahmoradi, Zabiholahi; Siadat, Amir Hossein; Jooya, Abolfazl

2007-01-01

Twenty percent azelaic acid gel is recommended as a topical treatment for acne due to its favorable profile. Our objective in this study was to evaluate the efficacy of 20% azelaic acid gel in the treatment of mild to moderate acne vulgaris. This was a double blind, randomized clinical trial. Sixty patients with mild to moderate acne vulgaris were selected randomly to receive either azelaic acid gel or the vehicle gel alone. Patients were followed up every 15 days for a period of 45 days. The number of lesions and the acne severity index (ASI) were recorded and compared using Student's t-test. Total lesion count was reduced by 60.6% and 19.9% by azelaic acid gel and the placebo respectively (P = 0.002). ASI was reduced by 65.2% and 21.3% by azelaic acid gel and the placebo respectively (P = 0.001), i.e, azelaic acid gel was 3.06 times more effective than the placebo in reducing ASI. Azelaic acid gel can be used as an effective treatment in mild to moderate acne vulgaris.

Infrared and Raman spectra of triacetoxyvinylsilane, aqueous sol-gel and xerogel

NASA Astrophysics Data System (ADS)

Li, Ying-Sing; Ba, Abdul; Mahmood, Maleeha S.

2009-04-01

Triacetoxyvinylsilane (TAVS) has been used as a precursor to prepare sol-gel under aqueous conditions. The sol-gel product has been applied for the surface treatment of aluminum. Infrared and Raman spectra have been collected for TAVS and for TAVS sol-gel, xerogel and sol-gel-coated aluminum. Vibrational analyses have been suggested for the recorded spectra based essentially on the group frequencies and the spectral variation with the change of the sol-gel product states and the vibrational assignments of similar molecules. From the recorded infrared and Raman spectra of the sol-gel and xerogel, it is found that the sol-gel produced in the process with TAVS is essentially the same as that prepared from vinyltriethoxysilane. Thermo-gravimetric analysis (TGA) of TAVS xerogel has been conducted, and an explanation has been given in coordination with the results obtained from IR spectroscopic study of the xerogels cured at different temperatures. The study has demonstrated the thermal effect on the condensation of the sol-gel process and on the vinyl decomposition of TAVS xerogel.

Biocompatibility of a Sonicated Silk Gel for Cervical Injection During Pregnancy

PubMed Central

Critchfield, Agatha S.; Mccabe, Reid; Klebanov, Nikolai; Richey, Lauren; Socrate, Simona; Norwitz, Errol R.; Kaplan, David L.; House, Michael

2014-01-01

Objective: To evaluate the biocompatibility of silk gel for cervical injection. Study Design: Silk gel was injected into the cervix of pregnant rats on day 13 (n = 11) and harvested at day 17. Histology of silk gel was compared with suture controls. Also, human cervical fibroblasts were cultured on silk gel and tissue culture plastic (TCP) in vitro. Cell viability, proliferation, metabolic activity, gene expression (COL1A1, COL3A1, and COX2), and release of proinflammatory mediators (interleukin [IL] 6 and IL-8) were evaluated. Results: In vivo, a mild foreign body response was seen surrounding the silk gel and suture controls. In vitro, cervical fibroblasts were viable, metabolically active, and proliferating at 72 hours. Release of IL-6 and IL-8 was similar on silk gel and TCP. Collagen and COX2 gene expression was similar or slightly decreased compared with TCP. Conclusions: Silk gel was well tolerated in vivo and in vitro, which supports continuing efforts to develop silk gels as an alternative to cervical cerclage. PMID:24520079

Induction and Tunability of Self-Healing Property of Dendron Based Hydrogel Using Clay Nanocomposite.

PubMed

Vivek, Balachandran; Kumar, Prashant; Prasad, Edamana

2016-06-16

Low molecular weight gels have relatively poor self-healing capacity compared to that of polymeric gels. Induction and tuning of the healing capacity of low molecular weight gels to achieve desired applications are thus challenging tasks. The present work describes the achievement of remarkable tunability of self-healing property for a low molecular weight hybrid gel, based on poly(aryl ether) dendron derivative (PAD). The hybrid gel has been synthesized using PAD and poly(amido amine) {PAMAM} dendrimer derivative (QPD), which are intercalated in the montmorillonite clay (MMT) layers. The self-healing of the hybrid gel (QPD-MMT-PAD) was demonstrated through experiments where the distorted gel regained the initial value of storage modulus (G') within a few minutes. Further, the propensity of self-healing of the gel has been tuned as a function of QPD concentration. The mechanically stable QPD-MMT-PAD hybrid gel has been utilized for the adsorption of ppm level concentration of polycyclic aromatic hydrocarbons (PAHs) such as β-naphthol, pyrene, and phenenathrene from water with excellent efficiency (80-98%).

Silica- and germania-based dual-ligand sol-gel organic-inorganic hybrid sorbents combining superhydrophobicity and π-π interaction. The role of inorganic substrate in sol-gel capillary microextraction.

PubMed

Seyyal, Emre; Malik, Abdul

2017-04-29

Principles of sol-gel chemistry were utilized to create silica- and germania-based dual-ligand surface-bonded sol-gel coatings providing enhanced performance in capillary microextraction (CME) through a combination of ligand superhydrophobicity and π-π interaction. These organic-inorganic hybrid coatings were prepared using sol-gel precursors with bonded perfluorododecyl (PF-C 12 ) and phenethyl (PhE) ligands. Here, the ability of the PF-C 12 ligand to provide enhanced hydrophobic interaction was advantageously combined with π-π interaction capability of the PhE moiety to attain the desired sorbent performance in CME. The effect of the inorganic sorbent component on microextraction performance of was explored by comparing microextraction characteristics of silica- and germania-based sol-gel sorbents. The germania-based dual-ligand sol-gel sorbent demonstrated superior CME performance compared to its silica-based counterpart. Thermogravimetric analysis (TGA) of the created silica- and germania-based dual-ligand sol-gel sorbents suggested higher carbon loading on the germania-based sorbent. This might be indicative of more effective condensation of the organic ligand-bearing sol-gel-active chemical species to the germania-based sol-gel network (than to its silica-based counterpart) evolving in the sol solution. The type and concentration of the organic ligands were varied in the sol-gel sorbents to fine-tune extraction selectivity toward different classes of analytes. Specific extraction (SE) values were used for an objective comparison of the prepared sol-gel CME sorbents. The sorbents with higher content of PF-C 12 showed remarkable affinity for aliphatic hydrocarbons. Compared to their single-ligand sol-gel counterparts, the dual-ligand sol-gel coatings demonstrated significantly superior CME performance in the extraction of alkylbenzenes, providing up to ∼65.0% higher SE values. The prepared sol-gel CME coatings provided low ng L -1 limit of detections (LOD) (4.2-26.3 ng L -1 ) for environmentally important analytes including polycyclic aromatic hydrocarbons, ketones and aliphatic hydrocarbons. In CME-GC experiments (n = 5), the capillary-to-capillary RSD value was ∼2.1%; such a low RSD value is indicative of excellent reproducibility of the sol-gel method used for the preparation of these CME coatings. The dual-ligand sol-gel coating provided stable performance in capillary microextraction of analytes from saline samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Metal-doped organic gels and method thereof

DOEpatents

Satcher, Jr., Joe H.; Baumann, Theodore F.

2003-09-02

Disclosed herein is a sol-gel polymerization process for synthesizing metal-doped organic gels. The process polymerizes metal salts of hydroxylated benzenes or hydroxylated benzene derivatives with alkyl or aryl aldehydes to form metal-doped, wet, organic gels. The gels can then be dried by supercritical solvent extraction to form metal-doped aerogels or by evaporation to form metal-doped xerogels. The aerogels and xerogels can then be pyrolyzed.

Sol-gel processing to form doped sol-gel monoliths inside hollow core optical fiber and sol-gel core fiber devices made thereby

NASA Technical Reports Server (NTRS)

Shaw, Harry C. (Inventor); Ott, Melanie N. (Inventor); Manuel, Michele V. (Inventor)

2002-01-01

A process of fabricating a fiber device includes providing a hollow core fiber, and forming a sol-gel material inside the hollow core fiber. The hollow core fiber is preferably an optical fiber, and the sol-gel material is doped with a dopant. Devices made in this manner includes a wide variety of sensors.

Metal-doped organic gels and method thereof

DOEpatents

Satcher, Jr., Joe H.; Baumann, Theodore F.

2007-10-23

Disclosed herein is a sol-gel polymerization process for synthesizing metal-doped organic gels. The process polymerizes metal salts of hydroxylated benzenes or hydroxylated benzene derivatives with alkyl or aryl aldehydes to form metal-doped, wet, organic gels. The gels can then be dried by supercritical solvent extraction to form metal-doped aerogels or by evaporation to form metal-doped xerogels. The aerogels and xerogels can then be pyrolyzed.

A brief review of other notable protein detection methods on acrylamide gels.

PubMed

Kurien, Biji T; Scofield, R Hal

2012-01-01

Several methods have been described to stain proteins analyzed on acrylamide gels. These include ultrasensitive protein detection in one-dimensional and two-dimensional gel electrophoresis using a fluorescent product from the fungus Epicoccum nigrum; a fluorescence-based Coomassie Blue protein staining; visualization of proteins in acrylamide gels using ultraviolet illumination; fluorescence visualization of proteins in sodium dodecyl sulfate-polyacrylamide gels using environmentally benign, nonfixative, saline solution; and increasing the sensitivity four- to sixfold for detecting trace proteins in dye or silver stained polyacrylamide gels using polyethylene glycol 6000. All these methods are reviewed briefly in this chapter.

Sol-gel layers for ceramic microsystems application

NASA Astrophysics Data System (ADS)

Czok, Mateusz; Golonka, Leszek

2016-11-01

This paper describes research on sol-gel solutions preparation process. Utilize of a sol-gel layers in the LTCC technology for reduction of surface roughness and influence on the ceramics properties is examined and described. The influence of sol-gel layer on possible sedimentation of dyes or biological substances in channels, mixers or chambers of ceramic microfluidic structures was investigated. Moreover, properties of sol-gel coated surfaces have been precisely examined and described. Finally, positive results of conducted experiments made it possible to design and manufacture a simple microfluidic ceramic structure, with embedded protective layer of sol-gel, for fluorescence measurements.

New composite thixotropic hydrogel composed of a polymer hydrogelator and a nanosheet

NASA Astrophysics Data System (ADS)

Ohsedo, Yutaka; Oono, Masashi; Saruhashi, Kowichiro; Watanabe, Hisayuki; Miyamoto, Nobuyoshi

2017-12-01

A composite gel composed of a water-soluble aromatic polyamide hydrogelator and the nanosheet Laponite®, a synthetic layered silicate, was produced and found to exhibit thixotropic behaviour. Whereas the composite gel contains the gelator at the same concentration as the molecular gel made by the gelator only, the composite gel becomes a softer thixotropic gel compared to the molecular gel made by the gelator only. The reason for this could be that bundles of polymer gelator may be loosened and the density of the polymer network increased in the presence of Laponite.

New composite thixotropic hydrogel composed of a polymer hydrogelator and a nanosheet

PubMed Central

Oono, Masashi; Saruhashi, Kowichiro; Watanabe, Hisayuki; Miyamoto, Nobuyoshi

2017-01-01

A composite gel composed of a water-soluble aromatic polyamide hydrogelator and the nanosheet Laponite®, a synthetic layered silicate, was produced and found to exhibit thixotropic behaviour. Whereas the composite gel contains the gelator at the same concentration as the molecular gel made by the gelator only, the composite gel becomes a softer thixotropic gel compared to the molecular gel made by the gelator only. The reason for this could be that bundles of polymer gelator may be loosened and the density of the polymer network increased in the presence of Laponite. PMID:29308249

Method of controlling a resin curing process. [for fiber reinforced composites

NASA Technical Reports Server (NTRS)

Webster, Charles Neal (Inventor); Scott, Robert O. (Inventor)

1989-01-01

The invention relates to an analytical technique for controlling the curing process of fiber-reinforced composite materials that are formed using thermosetting resins. The technique is the percent gel method and involves development of a time-to-gel equation as a function of temperature. From this equation a rate-of-gel equation is then determined, and a percent gel is calculated which is the product of rate-of-gel times time. Percent gel accounting is used to control the proper pressure application point in an autoclave cure process to achieve desired properties in a production composite part.

Sol-gel process for the manufacture of high power switches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landingham, Richard L.; Satcher, Jr, Joe; Reibold, Robert

According to one embodiment, a photoconductive semiconductor switch includes a structure of nanopowder of a high band gap material, where the nanopowder is optically transparent, and where the nanopowder has a physical characteristic of formation from a sol-gel process. According to another embodiment, a method includes mixing a sol-gel precursor compound, a hydroxy benzene and an aldehyde in a solvent thereby creating a mixture, causing the mixture to gel thereby forming a wet gel, drying the wet gel to form a nanopowder, and applying a thermal treatment to form a SiC nanopowder.

Mineral loss and morphological changes in dental enamel induced by a 16% carbamide peroxide bleaching gel.

PubMed

Soares, Diana Gabriela; Ribeiro, Ana Paula Dias; Sacono, Nancy Tomoko; Loguércio, Alessandro Dourado; Hebling, Josimeri; Costa, Carlos Alberto de Souza

2013-01-01

The aim of this study was to compare the effect of a 16% carbamide peroxide (CP) gel and a 10% CP gel on mineralized enamel content and morphology. Enamel blocks from bovine incisors were subjected to a 14-day treatment (8 h/day) with 10% or 16% CP gels. Knoop microhardness was evaluated before bleaching and at 1, 7 or 14 days after this treatment (50 g/15 s). Mineral content (energy-dispersive x-ray spectroscopy), surface roughness and topography (atomic force microscopy) were evaluated at the 14-day period. Data were analyzed statistically by two-way ANOVA and Tukey's test (α=0.05). Significant microhardness reduction was observed at the 7 th and 14 th days for 10% CP gel, and for all bleaching times for 16% CP gel (p<0.05). At the 14-day period, a significant decrease in Ca and P content, increase on surface roughness (p<0.05) as well as on picks and valleys distance were observed when both bleaching gels were used. These enamel alterations were more intense for 16% CP gel. It was concluded that both CP-based gels promoted loss of mineral structure from enamel, resulting in a rough and porous surface. However, 16% CP gel caused the most intense adverse effects on enamel.

Effects of Ca, Cu, Al and La on pectin gel strength: implications for plant cell walls.

PubMed

McKenna, Brigid A; Nicholson, Timothy M; Wehr, J Bernhard; Menzies, Neal W

2010-06-16

Rheology of Ca-pectate gels is widely studied, but the behaviour of pectate gels formed by Cu, Al and La is largely unknown. It is well known that gel strength increases with increasing Ca concentration, and it is hypothesised that this would also be the case for other cations. Pectins are a critical component of plant cell walls, imparting various physicochemical properties. Furthermore, the mechanism of metal toxicity in plants is hypothesised to be, in the short term, related to metal interactions with cell wall pectin. This study investigated the influence of Ca, Cu, Al and La ion concentrations at pH 4 on the storage modulus as a function of frequency for metal-pectin gels prepared from pectin (1%) with a degree of esterification of 30%. Gels were formed in situ over 6d in metal chloride solution adjusted daily to pH 4. Cation concentration was varied to develop a relationship between gel strength and cation concentration. At similar levels of cation saturation, gel strength increased in the order of La

Mucoadhesive in situ gel formulation for vaginal delivery of clotrimazole: formulation, preparation, and in vitro/in vivo evaluation.

PubMed

Rençber, Seda; Karavana, Sinem Yaprak; Şenyiğit, Zeynep Ay; Eraç, Bayri; Limoncu, Mine Hoşgör; Baloğlu, Esra

2017-06-01

The purpose of this study was to develop a suitable mucoadhesive in situ gel formulation of clotrimazole (CLO) for the treatment of vaginal candidiasis. For this aim, the mixture of poloxamer (PLX) 407 and 188 were used to prepare in situ gels. Hydroxypropyl methylcellulose (HPMC) K100M or E50 was added to in situ gels in 0.5% ratio to improve the mucoadhesive and mechanical properties of formulations and to prolong the residence time in vaginal cavity. After the preparation of mucoadhesive in situ gels; gelation temperature/time, viscosity, mechanical, mucoadhesive, syringeability, spreadibility and rheological properties, in vitro release behavior, and anticandidal activities were determined. Moreover vaginal retention of mucoadhesive in situ gels was investigated with in vivo distribution studies in rats. Based on the obtained results, it was found that gels prepared with 20% PLX 407, 10% PLX 188 and 0.5% HPMC K100M/E50 might be suitable for vaginal administration of CLO. In addition, the results of in vivo distribution studies showed that gel formulations remained on the vaginal mucosa even 24 h after application. In conclusion, the mucoadhesive in situ gels of CLO would be alternative candidate for treatment of vaginal candidiasis since it has suitable gel properties with good vaginal retention.

Effectiveness of intra-alveolar chlorhexidine gel in reducing dry socket following surgical extraction of lower third molars. A pilot study.

PubMed

Requena-Calla, Silvana; Funes-Rumiche, Italo

2016-04-01

Dry socket is one of the most studied complications in dentistry and several studies have sought an effective and safe method for its prevention and treatment. The aim of this study was to evaluate the effectiveness of intra-alveolar gel chlorhexidine in preventing dry socket after the surgical removal of third molars. The sample involved the treatment of 40 patients who required extraction of third molars impacted, which were randomly assigned to research groups: experimental group (chlorhexidine gel 0.12%) and control group (placebo gel). Performed the extraction was administered 1 mL of chlorhexidine gel or 1 mL of placebo gel within the socket. The removal of suture was on the fifth postoperative day in which the presence or absence of dry socket was evaluated. No relationship between the appearance of dry socket after application of chlorhexidine gel or placebo gel (X2 test, p = 0.311) was found. However, significant differences (U Mann-Whitney test, p = 0.036) in the pain presented on the fifth postoperative day were evident (VAS). The administration of intra-alveolar chlorhexidine gel 0.12% could generate a better response to postoperative pain after the removal of third molars. Third molar surgery, dry socket, chorhexidine gel.

Self-Assembling Nanoclay Diffusion Gels for Bioactive Osteogenic Microenvironments.

PubMed

Shi, Pujiang; Kim, Yang-Hee; Mousa, Mohamed; Sanchez, Roxanna Ramnarine; Oreffo, Richard O C; Dawson, Jonathan I

2018-06-17

Laponite nanoparticles have attracted attention in the tissue engineering field for their protein interactions, gel-forming properties, and, more recently, osteogenic bioactivity. Despite growing interest in the osteogenic properties of Laponite, the application of Laponite colloidal gels to host the osteogenic differentiation of responsive stem cell populations remains unexplored. Here, the potential to harness the gel-forming properties of Laponite to generate injectable bioactive microenvironments for osteogenesis is demonstrated. A diffusion/dialysis gelation method allows the rapid formation of stable transparent gels from injectable, thixotropic Laponite suspensions in physiological fluids. Upon contact with buffered saline or blood serum, nanoporous gel networks exhibiting, respectively, fivefold and tenfold increases in gel stiffness are formed due to the reorganization of nanoparticle interactions. Laponite diffusion gels are explored as osteogenic microenvironments for skeletal stem cell containing populations. Laponite films support cell adhesion, proliferation, and differentiation of human bone marrow stromal cells in 2D. Laponite gel encapsulation significantly enhances osteogenic protein expression compared with 3D pellet culture controls. In both 2D and 3D conditions, cell associated mineralization is strongly enhanced. This study demonstrates that Laponite diffusion gels offer considerable potential as biologically active and clinically relevant bone tissue engineering scaffolds. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Type I collagen gel protects murine fibrosarcoma L929 cells from TNFα-induced cell death

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hong-Ju; He, Wen-Qi; Chen, Ling

Murine fibrosarcoma L929 cells have been used to test efficacy of proinflammatory cytokine TNFα. In the present study, we reported on protective effect of type I collagen gel used as L929 cell culture. L929 cell grew and proliferated well on collagen gel. However, the L929 cells exhibited cobblestone-like morphology which was much different from the spread fusiform shape when cultured on conventional cell dishes as well as the cells tended to aggregate. On conventional cell culture dishes, the cells treated with TNFα became round in shape and eventually died in a necroptotic manner. The cells cultured on collagen gel, however,more » were completely unaffected. TNFα treatment was reported to induce autophagy in L929 cells on the plastic dish, and therefore we investigated the effect of collagen gel on induction of autophagy. The results indicated that autophagy induced by TNFα treatment was much reduced when the cells were cultured on collagen gel. In conclusion, type I collagen gel protected L929 cell from TNFα-induced cell death. - Highlights: • Collagen gel culture changed the morphology of L929 cells. • L929 cell cultured on collagen gel were resistant to TNFα-induced cell death. • Collagen gel culture inhibited TNFα-induced autophagy in L929 cells.« less

Evaluation of a New and Rapid Serologic Test for Detecting Brucellosis: Brucella Coombs Gel Test.

PubMed

Hanci, Hayrunisa; Igan, Hakan; Uyanik, Muhammet Hamidullah

2017-01-01

Many serological tests have been used for the diagnosis of human brucellosis. A new serological method is identified as Brucella Coombs gel test based on the principle of centrifugation gel system similar to the gel system used in blood group determination. In this system, if Brucella antibodies were present in the serum, antigen and antibody would remain as a pink complex on the gel. Otherwise, the pink Brucella antigens would precipitate at the bottom of the gel card system. In this study, we aimed to compare the Brucella Coombs gel test, a new, rapid screen and titration method for detection of non-agglutinating IgG with the Brucella Coombs test. For this study, a total of 88 serum samples were obtained from 45 healthy persons and 43 individuals who had clinical signs and symptoms of brucellosis. For each specimen, Rose Bengal test, standard agglutination test, Coombs test and Brucella Coombs gel test were carried out. Sensitivity and specificity of Brucella Coombs gel test were found as 100.0 and 82.2%, respectively. Brucella Coombs gel test can be used as a screening test with high sensitivity. By the help of pink Brucella antigen precipitation, the tests' evaluation is simple and objective. In addition, determination of Brucella antibody by rapid titration offers another important advantage.

Coating flow of an anti-HIV microbicide gel: boundary dilution and yield stress

NASA Astrophysics Data System (ADS)

Szeri, Andrew J.; Tasoglu, Savas; Park, Su Chan; Katz, David F.

2010-11-01

A recent study has confirmed, for the first time, that a vaginal gel formulation of the antiretroviral drug Tenofovir, when topically applied, significantly inhibits sexual HIV transmission to women [1]. However, the gel for this drug, and anti-HIV microbicide gels in general, have not been designed using an understanding of how gel spreading govern successful drug delivery. Elastohydrodynamic lubrication theory can be applied to model spreading of microbicide gels [2]. Here, we extend our initial analysis: we incorporate a yield stress, and we model the effects of gel dilution due to contact with vaginal fluid produced at the gel-tissue interface. Our model developed in [2] is supplemented with a convective-diffusive transport equation to characterize dilution, and solved using a multi-step scheme in a moving domain. The association between local dilution of gel and rheological properties is obtained experimentally. To model the common yield stress property of gels, we proceed by scaling analysis first. This establishes the conditions for validity of lubrication theory of a shear thinning yield stress fluid. This involves further development of the model in [2], incorporating a biviscosity model.[4pt] [1] Karim, et al., Science, 2010.[0pt] [2] Szeri, et al., Phy. of Fluids, 2008.

Impact of saccharides on the drying kinetics of agarose gels measured by in-situ interferometry

NASA Astrophysics Data System (ADS)

Mao, Bosi; Divoux, Thibaut; Snabre, Patrick

2017-01-01

Agarose gels are viscoelastic soft solids that display a porous microstructure filled with water at 90% w/w or more. Despite an extensive use in food industry and microbiology, little is known about the drying kinetics of such squishy solids, which suffers from a lack of time-resolved local measurements. Moreover, only scattered empirical observations are available on the role of the gel composition on the drying kinetics. Here we study by in-situ interferometry the drying of agarose gels of various compositions cast in Petri dishes. The gel thinning is associated with the displacement of interference fringes that are analyzed using an efficient spatiotemporal filtering method, which allows us to assess local thinning rates as low as 10 nm/s with high accuracy. The gel thinning rate measured at the center of the dish appears as a robust observable to quantify the role of additives on the gel drying kinetics and compare the drying speed of agarose gels loaded with various non-gelling saccharides of increasing molecular weights. Our work shows that saccharides systematically decrease the agarose gel thinning rate up to a factor two, and exemplifies interferometry as a powerful tool to quantify the impact of additives on the drying kinetics of polymer gels.

Biomimetic chimeric peptide-tethered hydrogels for human mesenchymal stem cell delivery.

PubMed

Shim, Gayong; Kim, Gunwoo; Choi, Junhyeok; Yi, TacGhee; Cho, Yun Kyoung; Song, Sun Uk; Byun, Youngro; Oh, Yu-Kyoung

2015-12-01

Here, we report a chimeric peptide-tethered fibrin hydrogel scaffold for delivery of human mesenchymal stem cells (hMSC). Osteopontin-derived peptide (OP) was used as an hMSC-tethering moiety. OP showed hMSC adhesion properties and enhanced hMSC proliferation. A natural fibrin-binding protein-derived peptide (FBP) was tested for its ability to tether hMSC to the fibrin gel matrix. FBP loading on fibrin gels was 8.2-fold higher than that of a scrambled peptide (scFBP). FBP-loaded fibrin gels were retained at injection sites longer than scFBP-loaded fibrin gels, showing a 15.9-fold higher photon intensity of fluorescent FBP-grafted fibrin gels than fluorescent scFBP-loaded fibrin gels 48 h after injection. On the basis of the fibrin gel-binding properties of FBP and the hMSC-binding and proliferation-supporting properties of OP, we constructed chimeric peptides containing FBP and OP linked with a spacer (FBPsOP). Four days after transplantation, the survival of hMSC in FBPsOP-grafted fibrin gels was 3.9-fold higher than hMSC in fibrin gels alone. Our results suggest the potential of FBPsOP-grafted fibrin gels as a bioactive delivery system for enhanced survival of stem cells. Copyright © 2015 Elsevier B.V. All rights reserved.

Structural characteristics of gels prepared from sonohydrolysis and conventional hydrolysis of TEOS: an emphasis on the mass fractal as determined from the pore size distribution

NASA Astrophysics Data System (ADS)

Vollet, D. R.; Torres, R. R.; Donatti, D. A.; Ibañez Ruiz, A.

2005-11-01

Silica gels were preparated from fixed proportion mixtures of tetraethoxysilane, water and hydrocloric acid, using either ultrasound stimulation (US) or conventional method (CO) in the hydrolysis step of the process. Wet gels were obtained with the same silica volume concentration and density. According to small-angle X-ray scattering, the structure of the wet gels can be described as mass fractal structures with mass fractal dimension D = 2.20 in a length scale = 7.9 nm, in the case of wet gels US, and D = 2.26 in a length scale = 6.9 nm, in the case of wet gels CO. The mass fractal characteristics of the wet gels US and CO account for the different structures evolved in the drying of the gels US and CO in the obtaining of xerogels and aerogels. The pore structure of the dried gels was studied by nitrogen adsorption as a function of the temperature. Aerogels (US and CO) present high porosity with pore size distribution (PSD) curves in the mesopore region while xerogels (US and CO) present minor porosity with PSD curves mainly in the micropore region. The dried gels US (aerogels and xerogels) generally present pore volume and specific surface area greater than the dried gels CO. The mass fractal structure of the aerogels has been studied from an approach based on the PSD curves exclusively.

Effect of natural gel product on bovine dentin erosion in vitro

PubMed Central

SALES-PERES, André de Carvalho; MARSICANO, Juliane Avansini; GARCIA, Rudan Paraíso; FORIM, Moacir Rossi; da SILVA, Maria Fatima das Graças Fernandes; SALES-PERES, Sílvia Helena de Carvalho

2013-01-01

Objective To evaluate the efficacy of Neem (Azadirachta indica) experimental gel for the prevention of erosive wear on bovine dentin, in vitro. Material and Methods One hundred dentin blocks were allocated into 5 experimental groups (20 samples each): C (control group, without gel); CG (control group, only base gel); F (fluoride gel, 1.23% NaF; pH 4.1, Dentsply; Brazil); N (Neem gel, 10% neem extract; pH 4.1, manipulation); NF (Neem+fluoride gel, 10% Neem extract and 1.23% NaF; pH 4.1, manipulation). The blocks were stored in artificial saliva for 24 hours. After this, they were submitted to six alternating re- and demineralization cycles. The blocks were analyzed for wear (profilometry). The results were submitted to statistical analysis by ANOVA and Tukey tests (P<0.05). Results The mean wear (±SD, µm) was shown as follows in groups: C (13.09±0.99), CG (10.60±1.99), F (10.90±1.44), N (12.68±1.13) and NF (10.84±1.65). All gels showed some preventive action when compared with control group. However, significant differences were found only between Neem+fluoride gel and fluoride gel. Conclusion A single application of a neem-containing fluoride gel reduced dentin erosion, thus it is a possible alternative in reducing dental wear. Further research should investigate the action mechanism and the synergism between them. PMID:24473728

Study on Influence Factors and Governance Countermeasures of Movable Gel Prepared with Backfilling Waste Water

NASA Astrophysics Data System (ADS)

Gao, Shanshan; Zhang, Jianzhong; Zhang, Tiantian; Cui, Yanjie; Wang, Zhiqiang; Sun, Xinrui; Li, Jing; Zhang, Lianchao

2018-05-01

Movable gel as profile control and flooding is one of the main measures in tertiary oil recovery in Huabei Oilfield. Many blocks have tight fresh water supplies, but produced waste water can not be discharged. Therefore, preparing movable gel with backfilling waste water has become an inevitable development trend of profile control and flooding. Three different quality of sewage water named SW, YW and ZW were used to prepare gel and then compared with gel prepared clean water. The results showed that the gel viscosity prepared with clean water was 1.5-5.6 times of sewage water at the same formula concentration. For this reason, the effect of Na+, Ca2+, Fe2+ on the gel performance were analyzed. The above ions lead to a decrease in the gel viscosity and poor stability, which can not even be crosslinked. According to the sewage water characteristics, corresponding treatment measures were developed respectively. The best treatment of SW and ZW was increasing polymer concentration followed by the addition of thiourea. The best treatment of YW was also increasing polymer concentration followed by stirring and aeration. The gel viscosity reached to 1800-2500mPaṡs and maintained at 800-1200mPaṡs after 90 days at formation temperature. It showed that the treatment can effectively improve the gel viscosity and stability prepared with sewage water. The results provide valuable experiences for the preparation of movable gel with different quality waste water.

A combined analysis of 2 randomized clinical studies of tretinoin gel 0.05% for the treatment of acne.

PubMed

Webster, Guy; Cargill, D Innes; Quiring, John; Vogelson, Cullen T; Slade, Herbert B

2009-03-01

Acne vulgaris is a widely prevalent skin disorder primarily treated with retinoids, which have been shown to cause skin irritation. This report describes the combined analysis of 2 similar phase 3 studies designed to evaluate the efficacy and safety of an aqueous gel formulation of tretinoin relative to its vehicle (both studies) and a marketed microsphere formulation of tretinoin (one study) for once-daily topical treatment of acne. Randomized participants 10 years and older with mild to moderate acne (N=1537) received tretinoin gel 0.05% (n=674), tretinoin gel microsphere 0.1% (n=376), or vehicle (n=487) once daily for 12 weeks. Tretinoin gel was more effective than vehicle in reducing inflammatory (P<.001) and noninflammatory (P<.001) lesion counts over 12 weeks. Treatment success rate (global severity score, 0 or 1) was significantly greater in the tretinoin gel 0.05% group compared with the vehicle group (P<.001). The efficacy rate of tretinoin gel 0.05% was approximately 12% less than tretinoin gel microsphere 0.1%. Adverse events (AEs) were generally mild to moderate and rarely resulted in participant discontinuation. Incidence of skin-related AEs in the tretinoin gel 0.05% group (31%) was significantly lower compared with the tretinoin gel microsphere 0.1% group (52%)(P<.001). Thus, tretinoin gel 0.05% applied once daily is a well-tolerated and effective therapy for acne vulgaris and is associated with a low incidence of skin-related AEs.

Evaluation of tilapia skin gelatin as a mammalian gelatin replacer in acid milk gels and low-fat stirred yogurt.

PubMed

Pang, Zhihua; Deeth, Hilton; Yang, Hongshun; Prakash, Sangeeta; Bansal, Nidhi

2017-05-01

Tilapia skin gelatin (TSG) was studied in a 3-stage process (cooling, annealing, and heating) for pure gelatin gels and in a 4-stage process (acidification, cooling, annealing, and heating) for acid milk gels and cultured yogurt. The aim was to evaluate the use of TSG as a replacement for mammalian gelatin in yogurt. In pure TSG gels, stronger gels with higher melting temperatures were formed with increasing TSG concentrations. Compared with bovine gelatin (BG), which gelled at a concentration of 2.5%, TSG gels had lower gelling (14.1°C) and melting (24°C) temperatures but comparable storage moduli during annealing. In acid milk gels, addition of TSG increased the firmness of the gels with increasing concentration. Gelling and melting points of TSG in milk gels were observed at sufficient concentrations during cooling and heating. Strands and sheets were observed in the electron micrographs of milk gels with 1% TSG and a very dense structure was observed with 2.5% TSG. Yogurt with 0.4% TSG had similar viscosity, consistency, pseudoplasticity, and thixotropy as yogurt containing 0.4% BG; no difference was perceived by sensory panelists according to a triangle test. Addition of 0.4% TSG completely prevented whey separation from the acid milk gel and yogurt. The results suggest that TSG could be a suitable replacement for mammalian gelatin in low-fat stirred yogurt. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The effect of short- and long-term treatment with manuka honey on second intention healing of contaminated and noncontaminated wounds on the distal aspect of the forelimbs in horses.

PubMed

Bischofberger, Andrea S; Dart, Christina M; Perkins, Nigel R; Kelly, Ashley; Jeffcott, Leo; Dart, Andrew J

2013-02-01

To compare the effects of manuka honey and manuka honey gel on second intention healing of noncontaminated distal limb wounds and those contaminated with feces. Experimental study. Standardbred horses (n = 10). Five full-thickness wounds (2 × 2 cm) were created on both metacarpi. Wounds on 1 forelimb were covered with horse feces for 24 hours. Wounds on the contralateral limb were left uncontaminated. Wounds were assigned to the following 5 different treatments: manuka honey, manuka honey gel or gel applied for 12 days, manuka honey gel applied throughout healing and untreated control. Wound area was measured on day 1 then weekly until day 42 and time to complete healing was recorded. Wounds treated with manuka honey gel throughout healing healed faster than all other wounds (P < .05). Wounds treated with manuka honey and manuka honey gel for 12 days healed faster than gel control and untreated control wounds (P < .05). Wounds treated with manuka honey and manuka honey gel for 12 days and throughout healing were smaller than gel control and untreated control wounds until day 35 (P < .05). Wounds contaminated with feces had greater retraction for 7 days, but healed faster than noncontaminated wounds (P < .05). Treatment of wounds with manuka honey and manuka honey gel reduced wound retraction and overall healing time compared with gel and untreated control wounds. © Copyright 2012 by The American College of Veterinary Surgeons.

Effect of dextran and dextran sulfate on the structural and rheological properties of model acid milk gels.

PubMed

Pachekrepapol, U; Horne, D S; Lucey, J A

2015-05-01

Various types of polysaccharides are widely used in cultured dairy products. However, the interaction mechanisms, between milk proteins and these polysaccharides, are not entirely clear. To explore the interactions between uncharged and charged polysaccharides and the caseins, we used a model acid-milk-gel system, which allowed acidification to occur separately from gelation. The effect of adding uncharged dextran (DX; molecular weight ~2.0×10(6) Da) and negatively charged dextran sulfate (DS; molecular weight ~1.4×10(6) Da) to model acid milk gels was studied. Two concentrations (0.075 and 0.5%, wt/wt) of DX or DS were added to cold milk (~0°C) that had been acidified to pH values 4.4, 4.6, 4.8, or 4.9. Acidified milks containing DX or DS were then quiescently heated at the rate of 0.5°C/min to 30°C, which induced gelation, and gels were then held at 30°C for 17 h to facilitate gel development. Dynamic small-amplitude-oscillation rheology and large-deformation (shear) tests were performed. Microstructure of gels was examined by fluorescence microscopy. Gels made with a high concentration of DX gelled at a lower temperature, but after 17 h at 30°C, these gels exhibited lower storage moduli and lower yield-stress values. At pH 4.8 or 4.9 (pH values greater than the isoelectric point of caseins), addition of 0.5% DS to acidified milk resulted in lower gelation temperature. At pH 4.4 (pH values less than the isoelectric point of caseins), addition of 0.5% DS to acidified milk resulted in gels with very high stiffness values. Gels made at pH 4.8 or 4.9 with both concentrations of DS had much lower stiffness and yield-stress values than control gels. Microstructural analysis indicated that gels made at pH 4.4 with the addition of 0.5% DX exhibited large protein strands and pores, whereas gels made with 0.075% DX or the control gels had a finer protein matrix. At higher pH values (>4.4), gels made with 0.5% DX had a finer structure. At all pH values, gels made with 0.5% DS exhibited larger pores than the control gels. This study demonstrated that low concentrations of uncharged DX did not significantly affect the rheological properties of model acid milk gels; high concentrations of DX resulted in earlier gelation, possibly caused by depletion-induced attractions between casein particles, which altered the microstructure and created weaker gels. At pH values <4.6, negatively charged DS produced stiff casein gels, which might be due to attractive crosslinking by electrostatic interactions between DS and caseins at pH values below the isoelectric pH of casein (i.e., positively charged casein regions interacted with negatively charged DS molecules). Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Structurally stable gel bead containing entrapped enzyme and method for manufacture thereof

DOEpatents

Woodward, J.

1998-12-08

This research provides a structurally stable gel bead containing an entrapped enzyme and a method for its manufacture. The enzyme is covalently cross-linked to gelatin in the presence of glutaraldehyde prior to the formation of the gel bead, to prevent leakage of the enzyme. Propylene glycol alginate is then added to the mixture. Once the gel beads are formed, they are then soaked in glutaraldehyde, which imparts structural stability to the gel beads. This method can be used with many types of enzymes, such as proteases, carbohydrases, proteases, ligases, isomerases, oxidoreductases, and specialty enzymes. These and other enzymes can be immobilized in the gel beads and utilized in a number of enzymatic processes. Exogenously added ions are not required to maintain the structural stability of these gel beads. 7 figs.

Structurally stable gel bead containing entrapped enzyme and method for manufacture thereof

DOEpatents

Woodward, Jonathan

1998-01-01

A structurally stable gel bead containing an entrapped enzyme and a method for its manufacture. The enzyme is covalently cross-linked to gelatin in the presence of glutaraldehyde prior to the formation of the gel bead, to prevent leakage of the enzyme. Propylene glycol alginate is then added to the mixture. Once the gel beads are formed, they are then soaked in glutaraldehyde, which imparts structural stability to the gel beads. This method can be used with many types of enzymes, such as proteases, carbohydrases, proteases, ligases, isomerases, oxidoreductases, and specialty enzymes. These and other enzymes can be immobilized in the gel beads and utilized in a number of enzymatic processes. Exogenously added ions are not required to maintain the structural stability of these gel beads.

Technical considerations for implementation of x-ray CT polymer gel dosimetry.

PubMed

Hilts, M; Jirasek, A; Duzenli, C

2005-04-21

Gel dosimetry is the most promising 3D dosimetry technique in current radiation therapy practice. X-ray CT has been shown to be a feasible method of reading out polymer gel dosimeters and, with the high accessibility of CT scanners to cancer hospitals, presents an exciting possibility for clinical implementation of gel dosimetry. In this study we report on technical considerations for implementation of x-ray CT polymer gel dosimetry. Specifically phantom design, CT imaging methods, imaging time requirements and gel dose response are investigated. Where possible, recommendations are made for optimizing parameters to enhance system performance. The dose resolution achievable with an optimized system is calculated given voxel size and imaging time constraints. Results are compared with MRI and optical CT polymer gel dosimetry results available in the literature.

pH-responsive self-assembly by molecular recognition on a macroscopic scale.

PubMed

Zheng, Yongtai; Hashidzume, Akihito; Harada, Akira

2013-07-12

Macroscopic pH-responsive self-assembly is successfully constructed by polyacrylamide(pAAm)-based gels carrying dansyl (Dns) and β-cyclodextrin (βCD) residues, which are represented as Dns-gel and βCD-gel, respectively. Dns-gel and βCD-gel assemble together at pH ≥ 4.0, but disassemble at pH ≤ 3.0. The adhesion strengths for pairs of Dns-gel/βCD-gel increase with increasing pH. The fluorescence study on the model system of pAAm modified with 1 mol% Dns moieties (pAAm/Dns) reveals that Dns residues are protonated at a lower pH, which results in the reduction in binding constant (K) for Dns residues and βCD. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Starbursts and Wispy Drops : Surfactants Spreading on Gel Substrates

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Shomeek; Daniels, Karen; Behringer, Robert

2005-11-01

We report a phase diagram for a novel instability seen in drops of nonionic surfactant solution (Triton X-305) spreading on viscoelastic agar gel substrate . This system allows us to examine the effect of varying the effective fluidity/stiffness of aqueous substrates. The morphology is strongly affected by the substrate fluidity, ranging from spreading starbursts of arms on weak gels, to wispy drops on intermediate strength gels, to circular drops on stiff gels. We analyze the dynamics of spreading in the starburst phase, where the arm length grows as t ^3/4 at early times, independent of the gel strength and surfactant concentration. The number of arms is proportional to the surfactant concentration and inversely proportional to the gel strength. Ongoing work is exploring the effects of changing the drop volume.

High transparent shape memory gel

NASA Astrophysics Data System (ADS)

Gong, Jin; Arai, Masanori; Kabir, M. H.; Makino, Masato; Furukawa, Hidemitsu

2014-03-01

Gels are a new material having three-dimensional network structures of macromolecules. They possess excellent properties as swellability, high permeability and biocompatibility, and have been applied in various fields of daily life, food, medicine, architecture, and chemistry. In this study, we tried to prepare new multi-functional and high-strength gels by using Meso-Decoration (Meso-Deco), one new method of structure design at intermediate mesoscale. High-performance rigid-rod aromatic polymorphic crystals, and the functional groups of thermoreversible Diels-Alder reaction were introduced into soft gels as crosslinkable pendent chains. The functionalization and strengthening of gels can be realized by meso-decorating the gels' structure using high-performance polymorphic crystals and thermoreversible pendent chains. New gels with good mechanical properties, novel optical properties and thermal properties are expected to be developed.

Meso-decorated self-healing gels: network structure and properties

NASA Astrophysics Data System (ADS)

Gong, Jin; Sawamura, Kensuke; Igarashi, Susumu; Furukawa, Hidemitsu

2013-04-01

Gels are a new material having three-dimensional network structures of macromolecules. They possess excellent properties as swellability, high permeability and biocompatibility, and have been applied in various fields of daily life, food, medicine, architecture, and chemistry. In this study, we tried to prepare new multi-functional and high-strength gels by using Meso-Decoration (Meso-Deco), one new method of structure design at intermediate mesoscale. High-performance rigid-rod aromatic polymorphic crystals, and the functional groups of thermoreversible Diels-Alder reaction were introduced into soft gels as crosslinkable pendent chains. The functionalization and strengthening of gels can be realized by meso-decorating the gels' structure using high-performance polymorphic crystals and thermoreversible pendent chains. New gels with good mechanical properties, novel optical properties and thermal properties are expected to be developed.

Apparatus for the production of gel beads containing a biocatalyst

DOEpatents

Scott, C.D.; Scott, T.C.; Davison, B.H.

1998-03-19

An apparatus is described for the large-scale and continuous production of gel beads containing a biocatalyst. The apparatus is a columnar system based on the chemical cross-linking of hydrocolloidal gels that contain and immobilize a biocatalyst, the biocatalyst being a microorganism or an enzyme. Hydrocolloidal gels, such as alginate, carrageenan, and a mixture of bone gelatin and modified alginate, provide immobilization matrices that can be used to entrap and retain the biocatalyst while allowing effective contact with substrates and release of products. Such immobilized biocatalysts are generally formulated into small spheres or beads that have high concentrations of the biocatalyst within the gel matrix. The columnar system includes a gel dispersion nozzle submerged in a heated non-interacting liquid, typically an organic liquid, that is immiscible with water to allow efficient formation of spherical gel droplets, the non-interacting liquid having a specific gravity that is less than water so that the gel droplets will fall through the liquid by the force of gravity. The heated non-interacting liquid is in direct contact with a chilled upflowing non-interacting liquid that will provide sufficient residence time for the gel droplets as they fall through the liquid so that they will be cooled below the gelling temperature and form solid spheres. The upflowing non-interacting liquid is in direct contact with an upflowing temperature-controlled aqueous solution containing the necessary chemicals for cross-linking or fixing of the gel beads to add the necessary stability. The flow rates of the two liquid streams can be varied to control the proper residence time in each liquid section to accommodate the production of gel beads of differing settling velocities. A valve is provided for continuous removal of the stabilized gel beads from the bottom of the column. 1 fig.

Apparatus and method for the production of gel beads containing a biocatalyst

DOEpatents

Scott, Charles D.; Scott, Timothy C.; Davison, Brian H.

1998-01-01

An apparatus and method for the large-scale and continuous production of gel beads containing a biocatalyst. The apparatus is a columnar system based on the chemical cross-linking of hydrocolloidal gels that contain and immobilize a biocatalyst, the biocatalyst being a microorganism or an enzyme. Hydrocolloidal gels, such as alginate, carrageenan, and a mixture of bone gelatin and modified alginate, provide immobilization matrices that can be used to entrap and retain the biocatalyst while allowing effective contact with substrates and release of products. Such immobilized biocatalysts are generally formulated into small spheres or beads that have high concentrations of the biocatalyst within the gel matrix. The columnar system includes a gel dispersion nozzle submerged in a heated non-interacting liquid, typically an organic liquid, that is immiscible with water to allow efficient formation of spherical gel droplets, the non-interacting liquid having a specific gravity that is less than water so that the gel droplets will fall through the liquid by the force of gravity. The heated non-interacting liquid is in direct contact with a chilled upflowing non-interacting liquid that will provide sufficient residence time for the gel droplets as they fall through the liquid so that they will be cooled below the gelling temperature and form solid spheres. The upflowing non-interacting liquid is in direct contact with an upflowing temperature-controlled aqueous solution containing the necessary chemicals for cross-linking or fixing of the gel beads to add the necessary stability. The flow rates of the two liquid streams can be varied to control the proper residence time in each liquid section to accommodate the production of gel beads of differing settling velocities. A valve is provided for continuous removal of the stabilized gel beads from the bottom of the column.

Apparatus for the production of gel beads containing a biocatalyst

DOEpatents

Scott, Charles D.; Scott, Timothy C.; Davison, Brian H.

1998-01-01

An apparatus for the large-scale and continuous production of gel beads containing a biocatalyst. The apparatus is a columnar system based on the chemical cross-linking of hydrocolloidal gels that contain and immobilize a biocatalyst, the biocatalyst being a microorganism or an enzyme. Hydrocolloidal gels, such as alginate, carrageenan, and a mixture of bone gelatin and modified alginate, provide immobilization matrices that can be used to entrap and retain the biocatalyst while allowing effective contact with substrates and release of products. Such immobilized biocatalysts are generally formulated into small spheres or beads that have high concentrations of the biocatalyst within the gel matrix. The columnar system includes a gel dispersion nozzle submerged in a heated non-interacting liquid, typically an organic liquid, that is immiscible with water to allow efficient formation of spherical gel droplets, the non-interacting liquid having a specific gravity that is less than water so that the gel droplets will fall through the liquid by the force of gravity. The heated non-interacting liquid is in direct contact with a chilled upflowing non-interacting liquid that will provide sufficient residence time for the gel droplets as they fall through the liquid so that they will be cooled below the gelling temperature and form solid spheres. The upflowing non-interacting liquid is in direct contact with an upflowing temperature-controlled aqueous solution containing the necessary chemicals for cross-linking or fixing of the gel beads to add the necessary stability. The flow rates of the two liquid streams can be varied to control the proper residence time in each liquid section to accommodate the production of gel beads of differing settling velocities. A valve is provided for continuous removal of the stabilized gel beads from the bottom of the column.

Solvent-resistant sol-gel polydimethyldiphenylsiloxane coating for on-line hyphenation of capillary microextraction with high-performance liquid chromatography.

PubMed

Segro, Scott S; Malik, Abdul

2008-09-26

A sol-gel polydimethyldiphenylsiloxane (PDMDPS) coating was developed for capillary microextraction on-line hyphenated with high-performance liquid chromatography (HPLC). This coating was created using methyltrimethoxysilane (MTMS) as the sol-gel precursor and di-hydroxy-terminated PDMDPS as the sol-gel active polymer. The methyl and phenyl groups on the sol-gel active polymer and the methyl groups on the sol-gel precursor ultimately turned into pendant groups providing the ability to extract non-polar analytes. A 40-cm segment of 0.25 mm I.D. fused silica capillary containing the sol-gel PDMDPS coating was installed as an external sampling loop in an HPLC injection port. Aqueous samples containing polycyclic aromatic hydrocarbons (PAHs), aromatic compounds, ketones, and aldehydes were passed through this capillary wherein the analytes were extracted by the sol-gel coating. The extracted analytes were then transferred to the HPLC column using isocratic or gradient elution with an acetonitrile/water mobile phase. This capillary demonstrated excellent extraction capability for non-polar (e.g., polycyclic aromatic hydrocarbons and aromatic compounds) as well as moderately polar compounds, such as aromatic amines, ketones, and aldehydes. The test results indicate that PDMDPS can be successfully immobilized into a sol-gel network and that the resulting solvent-resistant sol-gel organic-inorganic hybrid coating can be effectively used for on-line hyphenation of capillary microextraction with high-performance liquid chromatography. The test results also indicate that the sol-gel PDMDPS coated capillary is resistant to high-temperature solvents, making it suitable for applications in high-temperature HPLC. To the best of our knowledge, this is the first report on the creation of a silica-based sol-gel PDMDPS coating used in capillary microextraction on-line hyphenated to HPLC.

Determination of total arsenic using a novel Zn-ferrite binding gel for DGT techniques: Application to the redox speciation of arsenic in river sediments.

PubMed

Gorny, Josselin; Lesven, Ludovic; Billon, Gabriel; Dumoulin, David; Noiriel, Catherine; Pirovano, Caroline; Madé, Benoît

2015-11-01

A new laboratory-made Zn-ferrite (ZnFe2O4) binding gel is fully tested using Diffusive Gradient in Thin films (DGT) probes to measure total As [including inorganic As(III) and As(V), as well as MonoMethyl Arsenic Acid (MMAA(V)) and DiMethyl Arsenic Acid (DMAA(V))] in river waters and sediment pore waters. The synthesis of the binding gel is easy, cheap and its insertion into the acrylamide gel is not problematic. An important series of triplicate tests have been carried out to validate the use of the Zn-ferrite binding gel in routine for several environmental matrixes studies, in order to test: (i) the effect of pH on the accumulation efficiency of inorganic As species; (ii) the reproducibility of the results; (iii) the accumulation efficiency of As species; (iv) the effects of the ionic strength and possible competitive anions; and (v) the uptake and the elution efficiency of As species after accumulation in the binding gel. All experimental conditions have been reproduced using two other existing binding gels for comparison: ferrihydrite and Metsorb® HMRP 50. We clearly demonstrate that the Zn-ferrite binding gel is at least as good as the two other binding gels, especially for pH values higher than 8. In addition, by taking into consideration the diffusion rates of As(III) and As(V) in the gel, combining the 3-mercaptopropyl [accumulating only As(III)] with the Zn-ferrite binding gels allows for performing speciation studies. An environmental study along the Marque River finally illustrates the ability of the new binding gel to be used for field studies. Copyright © 2015. Published by Elsevier B.V.

Thickness sensing of hMSCs on collagen gel directs stem cell fate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leong, Wen Shing; Tay, Chor Yong; Yu, Haiyang

Research highlights: {yields} hMSCs appeared to sense thin collagen gel (130 {mu}m) with higher effective modulus as compared to thick gel (1440 {mu}m). {yields} Control of collagen gel thickness can modulate cellular behavior, even stem cell fate (neuronal vs. Quiescent). {yields} Distinct cellular behavior of hMSCs on thin and thick collagen gel suggests long range interaction of hMSCs with collagen gel. -- Abstract: Mechanically compliant substrate provides crucial biomechanical cues for multipotent stem cells to regulate cellular fates such as differentiation, proliferation and maintenance of their phenotype. Effective modulus of which cells sense is not only determined by intrinsic mechanicalmore » properties of the substrate, but also the thickness of substrate. From our study, it was found that interference from underlying rigid support at hundreds of microns away could induce significant cellular response. Human mesenchymal stem cells (hMSCs) were cultured on compliant biological gel, collagen type I, of different thickness but identical ECM composition and local stiffness. The cells sensed the thin gel (130 {mu}m) as having a higher effective modulus than the thick gel (1440 {mu}m) and this was reflected in their changes in morphology, actin fibers structure, proliferation and tissue specific gene expression. Commitment into neuronal lineage was observed on the thin gel only. Conversely, the thick gel (1440 {mu}m) was found to act like a substrate with lower effective modulus that inhibited actin fiber polymerization. Stem cells on the thick substrate did not express tissue specific genes and remained at their quiescent state. This study highlighted the need to consider not only the local modulus but also the thickness of biopolymer gel coating during modulation of cellular responses.« less

A New Combination of Testosterone and Nestorone Transdermal Gels for Male Hormonal Contraception

PubMed Central

Ilani, Niloufar; Roth, Mara Y.; Amory, John K.; Swerdloff, Ronald S.; Dart, Clint; Page, Stephanie T.; Bremner, William J.; Sitruk-Ware, Regine; Kumar, Narender; Blithe, Diana L.

2012-01-01

Context: Combinations of testosterone (T) and nestorone (NES; a nonandrogenic progestin) transdermal gels may suppress spermatogenesis and prove appealing to men for contraception. Objective: The objective of the study was to determine the effectiveness of T gel alone or combined with NES gel in suppressing spermatogenesis. Design and Setting: This was a randomized, double-blind, comparator clinical trial conducted at two academic medical centers. Participants: Ninety-nine healthy male volunteers participated in the study. Interventions: Volunteers were randomized to one of three treatment groups applying daily transdermal gels (group 1: T gel 10 g + NES 0 mg/placebo gel; group 2: T gel 10 g + NES gel 8 mg; group 3: T gel 10 g + NES gel 12 mg). Main Outcome Variable: The main outcome variable of the study was the percentage of men whose sperm concentration was suppressed to 1 million/ml or less by 20–24 wk of treatment. Results: Efficacy data analyses were performed on 56 subjects who adhered to the protocol and completed at least 20 wk of treatment. The percentage of men whose sperm concentration was 1 million/ml or less was significantly higher for T + NES 8 mg (89%, P < 0.0001) and T + NES 12 mg (88%, P = 0.0002) compared with T + NES 0 mg group (23%). The median serum total and free T concentrations in all groups were maintained within the adult male range throughout the treatment period. Adverse effects were minimal in all groups. Conclusion: A combination of daily NES + T gels suppressed sperm concentration to 1 million/ml or less in 88.5% of men, with minimal adverse effects, and may be further studied as a male transdermal hormonal contraceptive. PMID:22791756

Heated Ultrasound Gel and Patient Satisfaction with Bedside Ultrasound Studies: The HUGS Trial

PubMed Central

Krainin, Benjamin M.; Thaut, Lane C.; April, Michael D.; Curtis, Ryan A.; Kaelin, Andrea L.; Hardy, Garrett B.; Weymouth, Wells L.; Srichandra, Jonathan; Chin, Eric J.; Summers, Shane M.

2017-01-01

Introduction Our goal was to determine if heated gel for emergency department (ED) bedside ultrasonography improves patient satisfaction compared to room-temperature gel. Methods We randomized a convenience sample of ED patients determined by their treating physician to require a bedside ultrasound (US) study to either heated gel (102.0° F) or room-temperature gel (82.3° F). Investigators performed all US examinations. We informed all subjects that the study entailed investigation into various measures to improve patient satisfaction with ED US examinations but did not inform them of our specific focus on gel temperature. Investigators wore heat-resistant gloves while performing the examinations to blind themselves to the gel temperature. After completion of the US, subjects completed a survey including the primary outcome measure of patient satisfaction as measured on a 100-mm visual analogue scale (VAS). A secondary outcome was patient perceptions of sonographer professionalism measured by an ordinal scale (1–5). Results We enrolled 124 subjects; 120 completed all outcome measures. Of these, 59 underwent randomization to US studies with room-temperature gel and 61 underwent randomization to heated US gel. Patient 100-mm VAS satisfaction scores were 83.9 among patients undergoing studies with room-temperature gel versus 87.6 among subjects undergoing studies with heated gel (effect size 3.7, 95% confidence interval −1.3–8.6). There were similarly no differences between the two arms with regard to patient perceptions of sonographer professionalism. Conclusion The use of heated ultrasound gel appears to have no material impact on the satisfaction of ED patients undergoing bedside ultrasound studies. PMID:29085538

Kinetics of swelling of polyelectrolyte gels: Fixed degree of ionization

NASA Astrophysics Data System (ADS)

Sen, Swati; Kundagrami, Arindam

2015-12-01

The swelling kinetics of uncharged and charged polymer (polyelectrolyte) gels in salt-free conditions is studied in one dimension by solving the constitutive equation of motion (Newton's law for the elementary gel volume) of the displacement variable by two theoretical methods: one in which the classical definition of stress is used with the bulk modulus taken as a parameter, and the other in which a phenomenological expression of the osmotic stress as a function of polymer density and degree of ionization is taken as an input to the dynamics. The time-evolution profiles for spatially varying polymer density and stress, along with the location of the gel-solvent interface, are obtained from the two methods. We show that both the polymer density (volume fraction) and stress inside the gel follow expected behaviours of being maximum for the uniformly shrunken gel, and relaxing slowly to the lowest values as the gel approaches equilibrium. We further show that, by comparing the temporal profiles of the gel-solvent interface and other variables between the two methods, one may attempt to assign an effective bulk modulus to the polyelectrolyte gel as a function of the degree of ionization and other parameters of the gel such as hydrophobicity, cross-link density, and the temperature. The major result we get is that the effective bulk modulus of a polyelectrolyte gel increases monotonically with its degree of ionization. In the process of identifying the parameters for a monotonic swelling, we calculated using a well-known expression of the free energy the equilibrium results of two-phase co-existence and the critical point of a polyelectrolyte gel with a fixed degree of ionization.

Elastic Behavior and Platelet Retraction in Low- and High-Density Fibrin Gels

PubMed Central

Wufsus, Adam R.; Rana, Kuldeepsinh; Brown, Andrea; Dorgan, John R.; Liberatore, Matthew W.; Neeves, Keith B.

2015-01-01

Fibrin is a biopolymer that gives thrombi the mechanical strength to withstand the forces imparted on them by blood flow. Importantly, fibrin is highly extensible, but strain hardens at low deformation rates. The density of fibrin in clots, especially arterial clots, is higher than that in gels made at plasma concentrations of fibrinogen (3–10 mg/mL), where most rheology studies have been conducted. Our objective in this study was to measure and characterize the elastic regimes of low (3–10 mg/mL) and high (30–100 mg/mL) density fibrin gels using shear and extensional rheology. Confocal microscopy of the gels shows that fiber density increases with fibrinogen concentration. At low strains, fibrin gels act as thermal networks independent of fibrinogen concentration. Within the low-strain regime, one can predict the mesh size of fibrin gels by the elastic modulus using semiflexible polymer theory. Significantly, this provides a link between gel mechanics and interstitial fluid flow. At moderate strains, we find that low-density fibrin gels act as nonaffine mechanical networks and transition to affine mechanical networks with increasing strains within the moderate regime, whereas high-density fibrin gels only act as affine mechanical networks. At high strains, the backbone of individual fibrin fibers stretches for all fibrin gels. Platelets can retract low-density gels by >80% of their initial volumes, but retraction is attenuated in high-density fibrin gels and with decreasing platelet density. Taken together, these results show that the nature of fibrin deformation is a strong function of fibrin fiber density, which has ramifications for the growth, embolization, and lysis of thrombi. PMID:25564864

Local application of osteoprotegerin-chitosan gel in critical-sized defects in a rabbit model

PubMed Central

2017-01-01

Background Osteoprotegerin (OPG) is used for the systemic treatment of bone diseases, although it has many side effects. The aim of this study was to investigate a newly formulated OPG-chitosan gel for local application to repair bone defects. Recent studies have reported that immunodetection of osteopontin (OPN) and osteocalcin (OC) can be used to characterise osteogenesis and new bone formation. Methods The osteogenic potential of the OPG-chitosan gel was evaluated in rabbits. Critical-sized defects were created in the calvarial bone, which were either left unfilled (control; group I), or filled with chitosan gel (group II) or OPG-chitosan gel (group III), with rabbits sacrificed at 6 and 12 weeks. Bone samples from the surgical area were decalcified and treated with routine histological and immunohistochemical protocols using OC, OPN, and cathepsin K (osteoclast marker) antibodies. The toxicity of the OPG-chitosan gel was evaluated by biochemical assays (liver and kidney function tests). Results The mean bone growth in defects filled with the OPG-chitosan gel was significantly higher than those filled with the chitosan gel or the unfilled group (p < 0.05). At 6 and 12 weeks, the highest levels of OC and OPN markers were found in the OPG-chitosan gel group, followed by the chitosan gel group. The number of osteoclasts in the OPG-chitosan gel group was lower than the other groups. The results of the liver and kidney functional tests indicated no signs of harmful systemic effects of treatment. In conclusion, the OPG-chitosan gel has many characteristics that make it suitable for bone repair and regeneration, highlighting its potential benefits for tissue engineering applications. PMID:28674665

Kinetics of swelling of polyelectrolyte gels: Fixed degree of ionization.

PubMed

Sen, Swati; Kundagrami, Arindam

2015-12-14

The swelling kinetics of uncharged and charged polymer (polyelectrolyte) gels in salt-free conditions is studied in one dimension by solving the constitutive equation of motion (Newton's law for the elementary gel volume) of the displacement variable by two theoretical methods: one in which the classical definition of stress is used with the bulk modulus taken as a parameter, and the other in which a phenomenological expression of the osmotic stress as a function of polymer density and degree of ionization is taken as an input to the dynamics. The time-evolution profiles for spatially varying polymer density and stress, along with the location of the gel-solvent interface, are obtained from the two methods. We show that both the polymer density (volume fraction) and stress inside the gel follow expected behaviours of being maximum for the uniformly shrunken gel, and relaxing slowly to the lowest values as the gel approaches equilibrium. We further show that, by comparing the temporal profiles of the gel-solvent interface and other variables between the two methods, one may attempt to assign an effective bulk modulus to the polyelectrolyte gel as a function of the degree of ionization and other parameters of the gel such as hydrophobicity, cross-link density, and the temperature. The major result we get is that the effective bulk modulus of a polyelectrolyte gel increases monotonically with its degree of ionization. In the process of identifying the parameters for a monotonic swelling, we calculated using a well-known expression of the free energy the equilibrium results of two-phase co-existence and the critical point of a polyelectrolyte gel with a fixed degree of ionization.

[Preparation and transdermal permeation of triptolide and ferulic acid ethosomes gel in vitro].

PubMed

Tao, Ling; He, Liang-Fei; Guan, Yong-Mei; Chen, Li-Hua; Zhu, Wei-Feng; Jin, Chen; Wu, Lu

2018-03-01

The aim of this study was to prepare triptolide and ferulic acid ethosomes gel, investigate its transdermal permeation, and compare the results with ordinary gel and cream. Improved Franz diffusion cell method was used in the transdermal delivery experiment with rat abdominal skin as in vitro model. The receptor fluid at different time points was collected; ferulic acid concentration was determined by high performance liquid chromatography (HPLC) and triptolide concentration was determined by liquid chromatography-electrospray ionization mass spectrometry (LC-MS/MS). Then the penetration rate, transdermal volume and skin reserve of three dosage forms (hydroplasy gel, ordinary gel, and cream) to investigate the transdermal properties of ferulic acid and triptolide in vitro of triptolide and ferulic acid ethosomes gel. The results showed that the steady penetration rate of ferulic acid was 5.268 5, 8.990 9, 12.042 0 μg·cm⁻² ·h⁻¹ respectively in triptolide and ferulic acid ethosomes gel, ordinary gel and cream; the skin retention was (30.234 8±1.525 4), (20.402 6±0.402 6), (7.635 3±1.094 2) μg·cm⁻² . The steady-state permeation rate of triptolide was 67.238 0, 67.238 0 ng·cm⁻² ·h⁻¹ in triptolide and ferulic acid ethosomes gel, about 1.24 times of cream and 3.28 times of ordinary gel; the skin retention was (371.351 4±35.317 1) ng·cm⁻², about 3.35 times of cream and 5.25 times of ordinary gel. Therefore, the ethosomes gel showed good transdermal absorption property and it may be good for clinical safety administration. Copyright© by the Chinese Pharmaceutical Association.

Safety, tolerability, and systemic absorption of dapivirine vaginal microbicide gel in healthy, HIV-negative women.

PubMed

Nel, Annalene M; Coplan, Paul; van de Wijgert, Janneke H; Kapiga, Saidi H; von Mollendorf, Claire; Geubbels, Eveline; Vyankandondera, Joseph; Rees, Helen V; Masenga, Gileard; Kiwelu, Ireen; Moyes, Jocelyn; Smythe, Shanique C

2009-07-31

To assess the local and systemic safety of dapivirine vaginal gel vs. placebo gel as well as the systemic absorption of dapivirine in healthy, HIV-negative women. Two prospective, randomized, double-blind, placebo-controlled phase I/II studies were conducted at five research centers, four in Africa and one in Belgium. A total of 119 women used dapivirine gel (concentrations of 0.001, 0.002, 0.005, or 0.02%), and 28 used placebo gel twice daily for 42 days. The primary endpoints were colposcopic findings, adverse events, Division of AIDS grade 3 or grade 4 laboratory values, and plasma levels of dapivirine. Safety data were similar for the dapivirine and placebo gels. None of the adverse events with incidence more than 5% occurred with greater frequency in the dapivirine than placebo groups. Similar percentages of placebo and dapivirine gel users had adverse events that were considered by the investigator to be related to study gel. A total of five serious adverse events occurred in the two studies, and none was assessed as related to study gel. Mean plasma concentrations of dapivirine were approximately dose proportional, and, within each dose group, mean concentrations were similar on days 7, 28, and 42. The maximum observed mean concentration was 474 pg/ml in the 0.02% gel group on day 28. Two weeks after the final application of study gel, mean concentrations decreased to 5 pg/ml or less. Twice daily administration of dapivirine vaginal gel for 42 days was safe and well tolerated with low systemic absorption in healthy, HIV-negative women suggesting that continued development is warranted.

Ophthalmic gels: Past, present and future.

PubMed

Al-Kinani, Ali A; Zidan, Ghada; Elsaid, Naba; Seyfoddin, Ali; Alani, Adam W G; Alany, Raid G

2018-02-15

Aqueous gels formulated using hydrophilic polymers (hydrogels) along with those based on stimuli responsive polymers (in situ gelling or gel forming systems) continue to attract increasing interest for various eye health-related applications. They allow the incorporation of a variety of ophthalmic pharmaceuticals to achieve therapeutic levels of drugs and bioactives at target ocular sites. The integration of sophisticated drug delivery technologies such as nanotechnology-based ones with intelligent and environment responsive systems can extend current treatment duration to provide more clinically relevant time courses (weeks and months instead of hours and days) which will inevitably reduce dose frequency, increase patient compliance and improve clinical outcomes. Novel applications and design of contact lenses and intracanalicular delivery devices along with the move towards integrating gels into various drug delivery devices like intraocular pumps, injections and implants has the potential to reduce comorbidities caused by glaucoma, corneal keratopathy, cataract, diabetic retinopathies and age-related macular degeneration. This review describes ophthalmic gelling systems with emphasis on mechanism of gel formation and application in ophthalmology. It provides a critical appraisal of the techniques and methods used in the characterization of ophthalmic preformed gels and in situ gelling systems along with a thorough insight into the safety and biocompatibility of these systems. Newly developed ophthalmic gels, hydrogels, preformed gels and in situ gelling systems including the latest in the area of stimuli responsive gels, molecularly imprinted gels, nanogels, 3D printed hydrogels; 3D printed devices comprising ophthalmic gels are covered. Finally, new applications of gels in the production of artificial corneas, corneal wound healing and hydrogel contact lenses are described. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis of the response of PVA-GTA Fricke-gel dosimeters with clinical magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Collura, Giorgio; Gallo, Salvatore; Tranchina, Luigi; Abbate, Boris Federico; Bartolotta, Antonio; d'Errico, Francesco; Marrale, Maurizio

2018-01-01

Fricke gel dosimeters produced with a matrix of Poly-vinyl alcohol (PVA) cross-linked with glutaraldehyde (GTA) were analyzed with magnetic resonance imaging (MRI). Previous studies based on spectrophotometry showed valuable dosimetric features of these gels in terms of X-ray sensitivity and diffusion of the ferric ions produced after irradiation. In this study, MRI was performed on the gels at 1.5 T with a clinical scanner in order to optimize the acquisition parameters and obtain high contrast between irradiated and non-irradiated samples. The PVA gels were found to offer good linearity in the range of 0-10 Gy and a stable signal for several hours after irradiation. The sensitivity was about 40% higher compared to gels produced with agarose as gelling agent. The effect of xylenol orange (XO) on the MRI signal was also investigated: gel dosimeters made without XO show higher sensitivity to x-rays than those made with XO. The dosimetric accuracy of the 3D gels was investigated by comparing their MRI response to percentage depth dose and transversal dose profile measurements made with an ionization chamber in a water phantom. The comparison of PVA-GTA gels with and without XO showed that the chelating agent reduces the MRI sensitivity of the gels. Depth-dose and transversal dose profiles acquired by PVA-GTA gels without XO are more accurate and consistent with the ionization chamber data. However, diffusion effects hinder accurate measurements in the steep dose gradient regions and they should be further reduced by modifying the gel matrix and/or by minimizing the delay between irradiation and imaging.

Methods of Manufacturing Bioactive Gels from Extracellular Matrix Material

NASA Technical Reports Server (NTRS)

Janis, Abram D. (Inventor); Kentner, Kimberly A. (Inventor); Stuart, Katherine A. (Inventor)

2014-01-01

The present invention is directed to methods of manufacturing bioactive gels from ECM material, i.e., gels which retain bioactivity, and can serve as scaffolds for preclinical and clinical tissue engineering and regenerative medicine approaches to tissue reconstruction. The manufacturing methods take advantage of a new recognition that bioactive gels from ECM material can be created by digesting particularized ECM material in an alkaline environment and neutralizing to provide bioactive gels.

Methods of Manufacturing Bioactive Gels from Extracellular Matrix Material

NASA Technical Reports Server (NTRS)

Kentner, Kimberly A. (Inventor); Stuart, Katherine A. (Inventor); Janis, Abram D. (Inventor)

2015-01-01

The present invention is directed to methods of manufacturing bioactive gels from ECM material, i.e., gels which retain bioactivity, and can serve as scaffolds for preclinical and clinical tissue engineering and regenerative medicine approaches to tissue reconstruction. The manufacturing methods take advantage of a new recognition that bioactive gels from ECM material can be created by digesting particularized ECM material in an alkaline environment and neutralizing to provide bioactive gels.

Methods of Manufacturing Bioactive Gels from Extracellular Matrix Material

NASA Technical Reports Server (NTRS)

Kentner, Kimberly A. (Inventor); Stuart, Katherine A. (Inventor); Janis, Abram D. (Inventor)

2016-01-01

The present invention is directed to methods of manufacturing bioactive gels from ECM material, i.e., gels which retain bioactivity, and can serve as scaffolds for preclinical and clinical tissue engineering and regenerative medicine approaches to tissue reconstruction. The manufacturing methods take advantage of a new recognition that bioactive gels from ECM material can be created by digesting particularized ECM material in an alkaline environment and neutralizing to provide bioactive gels.

Methods of Manufacturing Bioactive Gels from Extracellular Matrix Material

NASA Technical Reports Server (NTRS)

Kentner, Kimberly (Inventor); Janis, Abram D. (Inventor); Stuart, Katherine A. (Inventor)

2017-01-01

The present invention is directed to methods of manufacturing bioactive gels from ECM material, i.e., gels which retain bioactivity, and can serve as scaffolds for preclinical and clinical tissue engineering and regenerative medicine approaches to tissue reconstruction. The manufacturing methods take advantage of a new recognition that bioactive gels from ECM material can be created by digesting particularized ECM material in an alkaline environment and neutralizing to provide bioactive gels.

Gel-forming reagents and uses thereof for preparing microarrays

DOEpatents

Golova, Julia; Chernov, Boris; Perov, Alexander

2010-11-09

New gel-forming reagents including monomers and cross-linkers, which can be applied to gel-drop microarray manufacturing by using co-polymerization approaches are disclosed. Compositions for the preparation of co-polymerization mixtures with new gel-forming monomers and cross-linker reagents are described herein. New co-polymerization compositions and cross-linkers with variable length linker groups between unsaturated C.dbd.C bonds that participate in the formation of gel networks are disclosed.

An in vivo and in vitro investigation of the effect of Aloe vera gel ethanolic extract using animal model with diabetic foot ulcer

PubMed Central

Daburkar, Mohan; Lohar, Vikram; Rathore, Arvind Singh; Bhutada, Pravin; Tangadpaliwar, Shrikant

2014-01-01

Aim: To examine the preventive effect of Aloe vera gel ethanolic extract using diabetic foot ulcer (DFUs) protocol in Wistar rats. Materials and Methods: Male Wistar rats were divided into untreated control (Group I), untreated DFUs (Group II), DFUs treated with A. vera gel ethanolic extract (Group III), DFUs treated with topical A. vera gel (Group IV), DFUs treated with A. vera gel ethanolic extract and topical A. vera gel (Group V). The rats in the treatment groups were daily administered the A. vera gel and ethanolic extract for 9 days. Fasting blood glucose levels and percentage of wound ulcer contraction were measured on day 3, 6, and 9. Statistical Analysis used: The results are expressed as a mean ± Standard Error Mean (SEM). Data were analyzed using one-way analysis of variance (ANOVA) after Newman–Keuls test. P < 0.05 were considered statistically significant in all cases. Results: Oral administration of A. vera gel ethanolic extract at a dose of 300 mg/kg body weight per day to diabetic rats for a period of 9 days resulted in a significant reduction in fasting blood glucose and a significant improvement in plasma insulin. Topical application of A. vera gel at a dose 30 mg/kg body weight per day to streptozotocin (STZ)-induced diabetic rats for a period of 9 days resulted in no change in blood glucose and plasma insulin. Oral administration as well as topical application of A. vera gel ethanolic extract and gel significantly reduced the blood glucose, improved the plasma insulin, and significantly increased DNA and glycosaminoglycans (GAGs) to improve the wound ulcer healing as well as the breaking strength on day 9. Conclusions: Present findings provide a scientific rationale for the use of A. vera gel ethanolic extract, and showed that the gel attenuated the diabetic foot wound in rats. PMID:25035641

Effects of obstetric gel on the process and duration of labour in pregnant women: Randomised controlled trial.

PubMed

Seval, Mehmet Murat; Yüce, Tuncay; Yakıştıran, Betül; Şükür, Yavuz Emre; Özmen, Batuhan; Atabekoğlu, Cem; Koç, Acar; Söylemez, Feride

2017-08-01

The present study investigated maternal and neonatal outcomes in pregnant women who used obstetric lubricant gels during active labour. This prospective randomised controlled study included 180 pregnant women. Women were randomly assigned to two groups during the first-stage of labour. Pregnant women in the obstetric gel group received standard antepartum care plus vaginal application of obstetric gel. Women in the control group received standard antepartum care without obstetric gel. Mean duration of the second stage of labour was significantly shorter in the obstetric gel group than control group (45 ± 34 min vs. 58 ± 31 min, respectively; p = .005). Mean APGAR values at 5 min were significantly higher in the obstetric gel group (9.5 ± 0.6 vs. 9.2 ± 0.7; p = .0014). Among nulliparous women, mean duration of the second stage of labour was significantly shorter in the gel group than control group (53 ± 52 min vs. 83 ± 45 min, respectively; p = .003). Using obstetric gel at the beginning of the first stage decreases the length of the second stage of labour, particularly in nulliparous women, and may be associated with an improved APGAR score at 5 min. Impact statement A limited number of studies in the literature have demonstrated that obstetric gels shorten the second stage of labour and are protective for the pelvic floor. The results of this study show that using obstetric gel shortens the second stage of labour in only nulliparous, but not multiparous women. In addition, a significant improvement in the 5 min APGAR score was seen in the neonates of women who used obstetric gel. The application of obstetric gels during the labour of nulliparous women may be a useful clinical practice and may have a widespread use in the future.

Evaluation of affinity and pseudo-affinity adsorption processes for penicillin acylase purification.

PubMed

Fonseca, L P; Cabral, J M

1996-01-01

Affinity ligand (6-Aminopenicillanic acid, Amoxycillin, Ampicillin, Benzylpenicillin and 4-Phenylbutylanzine) of penicillin acylase (EC 3.5.1.11) were attached to hydrophilic gels like Sepharose 4B-CNBr and Minileak 'medium'. Ampicillin and 4-Phenylbutylamine were the affinity ligands that presented the higher concentrations attached to both gels. Penicillin acylase adsorption on these affinity gels was mainly dependent on the activated group of the gel, the affinity ligand attached and the experimental conditions of enzyme adsorption. Under affinity conditions only the ligands Amoxycillin, Ampicillin and 4-Phenylbutylamine, immobilized on Minileak, adsorbed the enzyme from osmotic shock extracts at different pH values. These affinity ligand systems were characterized by low adsorption capacities of penicillin acylase activity (1.2-2.1 IU mL-1 gel) and specific activity (1.5-2.9 IU mg-1 prot). Under pseudo-affinity conditions all the ligands attached both activated to gels (Sepharose 4B-CNBr and Minileak) adsorbed the enzyme. The affinity gels were characterized by higher values of adsorption capacity (3.7 and 55.6 IU mL-1 gel) and adsorbed specific activity (2.0 and 6.1 IU mg-1 prot) than those observed under affinity conditions. The space arm of Minileak gel, shown to be fundamental to enzyme adsorption under affinity conditions, preferentially adsorbed proteins in relation to the enzyme under pseudo-affinity conditions. However, this effect was partially minimized when the gel was derivatized by the affinity ligands at concentrations higher than 6 mumol mL-1 gel. Ampicillin was the affinity ligand that presented the best results for specific adsorption of penicillin acylase under affinity and pseudo-affinity adsorption processes. The Sepharose 4B-CNBr derivatized gel also presented a good adsorption capacity of enzyme activity (26.8 IU mL-1 gel) under pseudo-affinity adsorption processes.

Bioactive Molecules Release and Cellular Responses of Alginate-Tricalcium Phosphate Particles Hybrid Gel

PubMed Central

Bang, Sumi; Zhang, Shengmin

2017-01-01

In this article, a hybrid gel has been developed using sodium alginate (Alg) and α-tricalcium phosphate (α-TCP) particles through ionic crosslinking process for the application in bone tissue engineering. The effects of pH and composition of the gel on osteoblast cells (MC3T3) response and bioactive molecules release have been evaluated. At first, a slurry of Alg and α-TCP has been prepared using an ultrasonicator for the homogeneous distribution of α-TCP particles in the Alg network and to achieve adequate interfacial interaction between them. After that, CaCl2 solution has been added to the slurry so that ionic crosslinked gel (Alg-α-TCP) is formed. The developed hybrid gel has been physico-chemically characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and a swelling study. The SEM analysis depicted the presence of α-TCP micro-particles on the surface of the hybrid gel, while cross-section images signified that the α-TCP particles are fully embedded in the porous gel network. Different % swelling ratio at pH 4, 7 and 7.4 confirmed the pH responsiveness of the Alg-α-TCP gel. The hybrid gel having lower % α-TCP particles showed higher % swelling at pH 7.4. The hybrid gel demonstrated a faster release rate of bovine serum albumin (BSA), tetracycline (TCN) and dimethyloxalylglycine (DMOG) at pH 7.4 and for the grade having lower % α-TCP particles. The MC3T3 cells are viable inside the hybrid gel, while the rate of cell proliferation is higher at pH 7.4 compared to pH 7. The in vitro cytotoxicity analysis using thiazolyl blue tetrazolium bromide (MTT), bromodeoxyuridine (BrdU) and neutral red assays ascertained that the hybrid gel is non-toxic for MC3T3 cells. The experimental results implied that the non-toxic and biocompatible Alg-α-TCP hybrid gel could be used as scaffold in bone tissue engineering. PMID:29135939

Agar/gelatin bilayer gel matrix fabricated by simple thermo-responsive sol-gel transition method.

PubMed

Wang, Yifeng; Dong, Meng; Guo, Mengmeng; Wang, Xia; Zhou, Jing; Lei, Jian; Guo, Chuanhang; Qin, Chaoran

2017-08-01

We present a simple and environmentally-friendly method to generate an agar/gelatin bilayer gel matrix for further biomedical applications. In this method, the thermally responsive sol-gel transitions of agar and gelatin combined with the different transition temperatures are exquisitely employed to fabricate the agar/gelatin bilayer gel matrix and achieve separate loading for various materials (e.g., drugs, fluorescent materials, and nanoparticles). Importantly, the resulting bilayer gel matrix provides two different biopolymer environments (a polysaccharide environment vs a protein environment) with a well-defined border, which allows the loaded materials in different layers to retain their original properties (e.g., magnetism and fluorescence) and reduce mutual interference. In addition, the loaded materials in the bilayer gel matrix exhibit an interesting release behavior under the control of thermal stimuli. Consequently, the resulting agar/gelatin bilayer gel matrix is a promising candidate for biomedical applications in drug delivery, controlled release, fluorescence labeling, and bio-imaging. Copyright © 2017 Elsevier B.V. All rights reserved.

Anomalous piezoelectric properties of poly(vinylidene fluoride-trifluoroethylene)/ionic liquid gels

NASA Astrophysics Data System (ADS)

Fukagawa, Miki; Koshiba, Yasuko; Fukushima, Tatsuya; Morimoto, Masahiro; Ishida, Kenji

2018-04-01

Piezoelectric gels were prepared from low-volatile ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][TFSI]) gels, and their structural, ferroelectric, and piezoelectric properties were investigated. Poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE)/IL gels were formed using thermally reversible physical gels. The structural characterization indicated that the P(VDF-TrFE) molecules in the gels predominantly formed a ferroelectric phase (Form I) of P(VDF-TrFE). Polarization switching peaks were clearly observed using a three-layer stacked device structure. The coercive field of the P(VDF-TrFE)/IL gels substantially decreased to 4-9 MV/m, and their remnant polarizations were maintained at 63-71 mC/m2, which is similar to that for typical solid-state P(VDF-TrFE). Finally, the P(VDF-TrFE)/IL gel films exhibited a piezoelectric response, and the highest piezoelectric coefficient was ˜300 pm/V at an applied voltage frequency of 4 kHz.

A pneumatic device for rapid loading of DNA sequencing gels.

PubMed

Panussis, D A; Cook, M W; Rifkin, L L; Snider, J E; Strong, J T; McGrane, R M; Wilson, R K; Mardis, E R

1998-05-01

This work describes the design and construction of a device that facilitates the loading of DNA samples onto polyacrylamide gels for detection in the Perkin Elmer/Applied Biosystems (PE/ABI) 373 and 377 DNA sequencing instruments. The device is mounted onto the existing gel cassettes and makes the process of loading high-density gels less cumbersome while the associated time and errors are reduced. The principle of operation includes the simultaneous transfer of the entire batch of samples, in which a spring-loaded air cylinder generates positive pressure and flexible silica capillaries transfer the samples. A retractable capillary array carrier allows the delivery ends of the capillaries to be held up clear of the gel during loader attachment on the gel plates, while enabling their insertion in the gel wells once the device is securely mounted. Gel-loading devices capable of simultaneously transferring 72 samples onto the PE/ABI 373 and 377 are currently being used in our production sequencing groups while a 96-sample transfer prototype undergoes testing.

Effect of pullulan on the water distribution, microstructure and textural properties of rice starch gels during cold storage.

PubMed

Chen, Long; Tian, Yaoqi; Tong, Qunyi; Zhang, Zipei; Jin, Zhengyu

2017-01-01

The effects of pullulan on the water distribution, microstructure and textural properties of rice starch gels during cold storage were investigated by low field-nuclear magnetic resonance (LF-NMR), scanning electron microscope (SEM), and texture profile analysis (TPA). The addition of pullulan reduced the transversal relaxation time of rice starch gels during cold storage. The microstructure of rice starch gel with 0.5% pullulan was denser and more uniform compared with that of rice starch without pullulan in each period of storage time. With regard to textural properties, 0.01% pullulan addition did not significantly change the texture of rice starch gels, while 0.5% pullulan addition appeared to reduce the hardness and retain the springiness of rice starch gels (P⩽0.05). The restriction effects of pullulan on water mobility and starch retrogradation were hypothesized to be mainly responsible for the water retention, gel structure maintenance, and modification of the textural attributes of rice starch gels. Copyright © 2016 Elsevier Ltd. All rights reserved.

Gels composed of sodium-aluminum silicate, Lake Magadi, Kenya

USGS Publications Warehouse

Eugster, H.P.; Jones, B.F.

1968-01-01

Sodium-aluminum silicate gels are found in surftcial deposits as thick as 5 centimeters in the Magadi area of Kenya. Chemical data indicate they are formed by the interaction of hot alkaline springwaters (67?? to 82??C; pH, about 9) with alkali trachyte flows and their detritus, rather than by direct precipitation. In the process, Na2O is added from and silica is released to the saline waters of the springs. Algal mats protect the gels from erosion and act as thermal insulators. The gels are probably yearly accumulates that are washed into the lakes during floods. Crystallization of these gels in the laboratory yields analcite; this fact suggests that some analcite beds in lacustrine deposits may have formed from gels. Textural evidence indicates that cherts of rocks of the Pleistocene chert series in the Magadi area may have formed from soft sodium silicate gels. Similar gels may have acted as substrates for the accumulation and preservation of prebiological organic matter during the Precambrian.

Active, motor-driven mechanics in a DNA gel.

PubMed

Bertrand, Olivier J N; Fygenson, Deborah Kuchnir; Saleh, Omar A

2012-10-23

Cells are capable of a variety of dramatic stimuli-responsive mechanical behaviors. These capabilities are enabled by the pervading cytoskeletal network, an active gel composed of structural filaments (e.g., actin) that are acted upon by motor proteins (e.g., myosin). Here, we describe the synthesis and characterization of an active gel using noncytoskeletal components. We use methods of base-pair-templated DNA self assembly to create a hybrid DNA gel containing stiff tubes and flexible linkers. We then activate the gel by adding the motor FtsK50C, a construct derived from the bacterial protein FtsK that, in vitro, has a strong and processive DNA contraction activity. The motors stiffen the gel and create stochastic contractile events that affect the positions of attached beads. We quantify the fluctuations of the beads and show that they are comparable both to measurements of cytoskeletal systems and to theoretical predictions for active gels. Thus, we present a DNA-based active gel whose behavior highlights the universal aspects of nonequilibrium, motor-driven networks.

Development of low-cost open source 3D gel printer "RepRap SWIM-ER"

NASA Astrophysics Data System (ADS)

Sato, Kei; Basher, Samiul; Ota, Takafumi; Tase, Taishi; Takamatsu, Kyuichiro; Saito, Azusa; Khosla, Ajit; Kawakami, Masaru; Furuawa, Hidemitsu

2017-04-01

Gels are soft and wet materials having low friction, good biocompatibility, and material permeability. It is expected that gel materials will be used as new kinds of industrial materials in the engineering and medical applications. But it cannot build a complicated shape. Soft & Wet Matter Engineering Laboratory developed a 3D gel Printer "SWIM-ER", has enabled modeling of complex shapes of the gel. However, this is expensive. Therefore not all of the gel researchers and the companies have such a device. To solve this problem, we manufacture a low-cost open-source 3D gel printer "RepRap SWIM-ER" from the RepRap. We made the components required to manufacture the "RepRap SWIM-ER" from the 3D printer and chose a light source. In addition, we produced the P-DN gel for RepRap SWIM-ER and conducted the molding test to confirm whether RepRap SWIM-ER can used it.

Orientation of chain molecules in ionotropic gels: a Brownian dynamics model

NASA Astrophysics Data System (ADS)

Woelki, Stefan; Kohler, Hans-Helmut

2003-09-01

As is known from birefringence measurements, polysaccharide molecules of ionotropic gels are preferentially orientated normal to the direction of gel growth. In this paper the orientation effect is investigated by means of an off-lattice Brownian dynamics model simulating the gel formation process. The model describes the integration of a single coarse grained phantom chain into the growing gel. The equations of motion of the chain are derived. The computer simulations show that, during the process of integration, the chain is contracting normal to the direction of gel growth. A scaling relation is obtained for the degree of contraction as a function of the length parameters of the chain, the velocity of the gel formation front and the rate constant of the crosslinking reaction. It is shown that the scaling relation, if applied to the example of ionotropic copper alginate gel, leads to reasonable predictions of the time course of the degree of contraction of the alginate chains.

A sensitive gel-based global O-glycomics approach reveals high levels of mannosyl glycans in the high mass region of the mouse brain proteome.

PubMed

Breloy, Isabelle; Pacharra, Sandra; Aust, Christina; Hanisch, Franz-Georg

2012-08-01

We developed a gel-based global O-glycomics method applicable for highly complex protein mixtures entrapped in discontinuous gradient gel layers. The protocol is based on in-gel proteolysis with pronase followed by (glyco)peptide elution and off-gel reductive β-elimination. The protocol offers robust performance with sensitivity in the low picomolar range, is compatible with gel-based proteomics, and shows superior performance in global applications in comparison with workflows eliminating glycans in-gel or from electroblotted glycoproteins. By applying this method, we analyzed the O-glycome of human myoblasts and of the mouse brain O-glycoproteome. After semipreparative separation of mouse brain proteins by one-dimensional SDS gel electrophoresis, the O-glycans from proteins in different mass ranges were characterized with a focus on O-mannose-based glycans. The relative proportion of the latter, which generally represent a rare modification, increases to comparatively high levels in the mouse brain proteome in dependence of increasing protein masses.

Sol-Gel Manufactured Energetic Materials

DOEpatents

Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

2005-05-17

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

Sol-gel manufactured energetic materials

DOEpatents

Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

2003-12-23

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

Cold therapy for the management of pain associated with deep breathing and coughing post-cardiac surgery.

PubMed

Chailler, Myrianne; Ellis, Jacqueline; Stolarik, Anne; Woodend, Kirsten

2010-01-01

Coughing has been identified as the most painful experience post cardiac surgery. Participants (n = 32), in a randomized crossover trial, applied a frozen gel pack to their sternal incision dressing before performing deep breathing and coughing (DB & C) exercises. Pain scores from 0 to 10 at rest were compared with pain scores post DB & C with and without the gel pack. Participants were also asked to describe their sensations with the frozen gel pack, as well as their preferences for gel pack application. The repeated measures analysis of variance revealed a significant reduction in pain scores between pre- and post-application of the gel pack (F = 28.69, p < .001). There were 22 (69%) participants who preferred the application of the gel pack compared with no gel pack. All 32 (100%) participants would reapply the gel pack in the future. This study demonstrates that cold therapy can be used to manage sternal incisional pain when DB & C.

Thermodynamic analysis of sol-gel transition of gelatin in terms of water activity in various solutions.

PubMed

Miyawaki, Osato; Omote, Chiaki; Matsuhira, Keiko

2015-12-01

Sol-gel transition of gelatin was analyzed as a multisite stoichiometric reaction of a gelatin molecule with water and solute molecules. The equilibrium sol-gel transition temperature, Tt , was estimated from the average of gelation and melting temperature measured by differential scanning calorimetry. From Tt and the melting enthalpy, ΔHsol , the equilibrium sol-to-gel ratio was estimated by the van't Hoff equation. The reciprocal form of the Wyman-Tanford equation, which describes the sol-to-gel ratio as a function of water activity, was successfully applied to obtain a good linear relationship. From this analysis, the role of water activity on the sol-gel transition of gelatin was clearly explained and the contributions of hydration and solute binding to gelatin molecules were separately discussed in sol-gel transition. The general solution for the free energy for gel-stabilization in various solutions was obtained as a simple function of solute concentration. © 2015 Wiley Periodicals, Inc.

Halogen-bonding-triggered supramolecular gel formation

NASA Astrophysics Data System (ADS)

Meazza, Lorenzo; Foster, Jonathan A.; Fucke, Katharina; Metrangolo, Pierangelo; Resnati, Giuseppe; Steed, Jonathan W.

2013-01-01

Supramolecular gels are topical soft materials involving the reversible formation of fibrous aggregates using non-covalent interactions. There is significant interest in controlling the properties of such materials by the formation of multicomponent systems, which exhibit non-additive properties emerging from interaction of the components. The use of hydrogen bonding to assemble supramolecular gels in organic solvents is well established. In contrast, the use of halogen bonding to trigger supramolecular gel formation in a two-component gel (‘co-gel’) is essentially unexplored, and forms the basis for this study. Here, we show that halogen bonding between a pyridyl substituent in a bis(pyridyl urea) and 1,4-diiodotetrafluorobenzene brings about gelation, even in polar media such as aqueous methanol and aqueous dimethylsulfoxide. This demonstrates that halogen bonding is sufficiently strong to interfere with competing gel-inhibitory interactions and create a ‘tipping point’ in gel assembly. Using this concept, we have prepared a halogen bond donor bis(urea) gelator that forms co-gels with halogen bond acceptors.

Explaining the texture properties of whey protein isolate/starch co-gels from fracture structures.

PubMed

Fu, Wei; Nakamura, Takashi

2017-04-01

The effects of tapioca starch (TS) and potato starch (PS) on texture properties of whey protein isolate (WPI)/starch co-gels were investigated for fracture structures. We focused on two types of WPI network structures. In a fine-stranded structure at pH 6.8, the WPI/TS co-gel fractured similarly to the WPI single gel. The WPI/PS co-gel was broken at a lower strain and lower stress. In a random aggregation at pH 5.8, the WPI/TS co-gel reached a yielding point at a lower strain, whereas the WPI/PS co-gel fractured at a higher strain and higher stress. In the fracture structures, it was revealed that breaks occurred in different places in these cases, which could explain the different texture properties of samples. This study tries to explain the texture properties of WPI/starch co-gels from fracture structures and provides a reference to predict texture properties of the WPI/starch food system.

Measuring Dilution of Microbicide Gels with Optical Imaging

PubMed Central

Drake, Tyler K.; Shah, Tejen; Peters, Jennifer J.; Wax, Adam; Katz, David F.

2013-01-01

We present a novel approach for measuring topical microbicide gel dilution using optical imaging. The approach compares gel thickness measurements from fluorimetry and multiplexed low coherence interferometry in order to calculate dilution of a gel. As a microbicide gel becomes diluted at fixed thickness, its mLCI thickness measurement remains constant, while the fluorimetry signal decreases in intensity. The difference between the two measurements is related to the extent of gel dilution. These two optical modalities are implemented in a single endoscopic instrument that enables simultaneous data collection. A preliminary validation study was performed with in vitro placebo gel measurements taken in a controlled test socket. It was found that change in slope of the regression line between fluorimetry and mLCI based measurements indicates dilution. A dilution calibration curve was then generated by repeating the test socket measurements with serial dilutions of placebo gel with vaginal fluid simulant. This methodology can provide valuable dilution information on candidate microbicide products, which could substantially enhance our understanding of their in vivo functioning. PMID:24340006

Chemotaxis of active, self-oscillating polymer gels in solution

NASA Astrophysics Data System (ADS)

Dayal, Pratyush; Bhattacharya, Amitabh; Kuksenok, Olga; Balazs, Anna C.

2012-02-01

Fighting, fleeing and feeding are hallmarks of all living things; all these activities require some degree of mobility. Herein, we undertake the first computational study of self-oscillating polymer gels and show that this system can ``communicate'' to undergo a biomimetic, collective response to small-scale chemical changes. In this study we harness unique properties of polymer gels that undergo oscillatory Belousov-Zhabotinsky (BZ) reaction. The activator for the reaction is generated within these BZ cilia and diffuses between the neighboring gels. In order to simulate the dynamics of the BZ gels in surrounding fluid we have developed a nonlinear hybrid 3D model which captures the elasto-dynamics of polymer gel and diffusive exchange of BZ reagents between the gel and the fluid. We illustrate that multiple BZ gels in solution exhibit a distinct form of chemotaxis, moving towards the highest activator concentration in the solution. Similar ability to sense and move in response to chemical gradients constitutes a vital function in simple organisms, enabling them to find food and flee from poisons.

Fouling mechanisms of gel layer in a submerged membrane bioreactor.

PubMed

Hong, Huachang; Zhang, Meijia; He, Yiming; Chen, Jianrong; Lin, Hongjun

2014-08-01

The fouling mechanisms underlying gel layer formation and its filtration resistance in a submerged membrane bioreactor (MBR) were investigated. It was found that gel layer rather than cake layer was more easily formed when soluble microbial products content in sludge suspension was relatively high. Thermodynamic analyses showed that gel layer formation process should overcome a higher energy barrier as compared with cake layer formation process. However, when separation distance <2.3 nm, attractive interaction energy of gelling foulant-membrane combination was remarkably higher than that of sludge floc-membrane combination. The combined effects were responsible for gel layer formation. Filtration tests showed that specific filtration resistance (SFR) of gel layer was almost 100 times higher than that of cake layer. The unusually high SFR of gel layer could be ascribed to the gelling propensity and osmotic pressure mechanism. These findings shed significant light on fouling mechanisms of gel layer in MBRs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Preparation and evaluation of chitosan-based nanogels/gels for oral delivery of myricetin.

PubMed

Yao, Yashu; Xia, Mengxin; Wang, Huizhen; Li, Guowen; Shen, Hongyi; Ji, Guang; Meng, Qianchao; Xie, Yan

2016-08-25

A novel nanogel/gel based on chitosan (CS) for the oral delivery of myricetin (Myr) was developed and evaluated comprehensively. The particle size of the obtained Myr-loaded CS/β-glycerol phosphate (β-GP) nanogels was in the range of 100-300nm. The rheological tests showed that the sol-gel transition happened when the nanogels were exposed to physiological temperatures, and 3D network structures of the gelatinized nanogels (gels) were confirmed by Scanning Electron Microscopy. Myr was released from CS/β-GP nanogel/gel in acidic buffers via a Fickian mechanism, and this release was simultaneously accompanied by swelling and erosion. Moreover, the nanogel/gel exhibited no cytotoxicity by MTT assay, and the oral bioavailability of Myr in rats was improved with an accelerated absorption rate after Myr was loaded into CS/β-GP nanogel/gel. In summary, all of the above showed that CS/β-GP nanogel/gel was an excellent system for orally delivering Myr. Copyright © 2016 Elsevier B.V. All rights reserved.

One plunge or two?--hand disinfection with alcohol gel.

PubMed

Macdonald, Duncan J M; Mckillop, Elisabeth C A; Trotter, Sylvia; Gray, Alastair J R

2006-04-01

To compare health care workers' hand surface coverage using two different volumes of alcohol gel for hand disinfection. and methods. A total of 84 members of staff in our hospital were studied. Subjects were asked to disinfect their hands with alcohol gel containing a clear fluorescent substance. Performance was assessed by using UV light to identify areas which had been missed, and the total surface area missed was calculated. A total of 42 subjects received 3.5 ml of alcohol gel, and 42 age-, sex-, and job-matched subjects received 1.75 ml of alcohol gel. Significantly less area was missed when hand disinfecting with double the volume of alcohol gel; 1.23 versus 6.35% surface area was missed (P < 0.001). Doubling the volume of alcohol gel used for hand disinfection significantly improves the efficiency of coverage of the hands with alcohol gel. This may result in lower bacterial count on the hands and may reduce the spread of nosocomial infections including that of methicillin-resistant Staphylococcus aureus.

Hydroxyapatite-coated double network hydrogel directly bondable to the bone: Biological and biomechanical evaluations of the bonding property in an osteochondral defect.

PubMed

Wada, Susumu; Kitamura, Nobuto; Nonoyama, Takayuki; Kiyama, Ryuji; Kurokawa, Takayuki; Gong, Jian Ping; Yasuda, Kazunori

2016-10-15

We have developed a novel hydroxyapatite (HAp)-coated double-network (DN) hydrogel (HAp/DN gel). The purpose of this study was to determine details of the cell and tissue responses around the implanted HAp/DN gel and to determine how quickly and strongly the HAp/DN gel bonds to the bone in a rabbit osteochondral defect model. Immature osteoid tissue was formed in the space between the HAp/DN gel and the bone at 2weeks, and the osteoid tissue was mineralized at 4weeks. The push-out load of the HAp/DN gel averaged 37.54N and 42.15N at 4 and 12weeks, respectively, while the push-out load of the DN gel averaged less than 5N. The bonding area of the HAp/DN gel to the bone was above 80% by 4weeks, and above 90% at 12weeks. This study demonstrated that the HAp/DN gel enhanced osseointegration at an early stage after implantation. The presence of nanoscale structures in addition to osseointegration of HAp promoted osteoblast adhesion onto the surface of the HAp/DN gel. The HAp/DN gel has the potential to improve the implant-tissue interface in next-generation orthopaedic implants such as artificial cartilage. Recent studies have reported the development of various hydrogels that are sufficiently tough for application as soft supporting tissues. However, fixation of hydrogels on bone surfaces with appropriate strength is a great challenge. We have developed a novel, tough hydrogel hybridizing hydroxyapatite (HAp/DN gel), which is directly bondable to the bone. The present study demonstrated that the HAp/DN gel enhanced osseointegration in the early stage after implantation. The presence of nanoscale structures in addition to the osseointegration ability of hydroxyapatite promoted osteoblast adhesion onto the surface of the HAp/DN gel. The HAp/DN gel has the potential to improve the implant-tissue interface in next-generation orthopaedic implants such as artificial cartilage. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Locally targeted delivery of a micron-size radiation therapy source using temperature-sensitive hydrogel.

PubMed

Kim, Yusung; Seol, Dong Rim; Mohapatra, Sucheta; Sunderland, John J; Schultz, Michael K; Domann, Frederick E; Lim, Tae-Hong

2014-04-01

To propose a novel radiation therapy (RT) delivery modality: locally targeted delivery of micron-size RT sources by using temperature-sensitive hydrogel (RT-GEL) as an injectable vehicle. Hydrogel is a water-like liquid at room temperature but gels at body temperature. Two US Food and Drug Administration-approved polymers were synthesized. Indium-111 (In-111) was used as the radioactive RT-GEL source. The release characteristics of In-111 from polymerized RT-GEL were evaluated. The injectability and efficacy of RT-GEL delivery to human breast tumor were tested using animal models with control datasets of RT-saline injection. As proof-of-concept studies, a total of 6 nude mice were tested by injecting 4 million tumor cells into their upper backs after a week of acclimatization. Three mice were injected with RT-GEL and 3 with RT-saline. Single-photon emission computed tomography (SPECT) and CT scans were performed on each mouse at 0, 24, and 48 h after injection. The efficacy of RT-GEL was determined by comparison with that of the control datasets by measuring kidney In-111 accumulation (mean nCi/cc), representing the distant diffusion of In-111. RT-GEL was successfully injected into the tumor by using a 30-gauge needle. No difficulties due to polymerization of hydrogel during injection and intratumoral pressure were observed during RT-GEL injection. No back flow occurred for either RT-GEL or RT-saline. The residual tumor activities of In-111 were 49% at 24 h (44% at 48 h, respectively) for RT-GEL and 29% (22%, respectively) for RT-saline. Fused SPECT-CT images of RT-saline showed considerable kidney accumulation of In-111 (2886%, 261%, and 262% of RT-GEL at 0, 24, and 48 h, respectively). RT-GEL was successfully injected and showed much higher residual tumor activity: 170% (200%, respectively), than that of RT-saline at 24 h (48 h, respectively) after injection with a minimal accumulation of In-111 to the kidneys. Preliminary data of RT-GEL as a delivery modality of a radiation source to a local tumor are promising. Published by Elsevier Inc.

The phototoxic and photoallergy potential of clindamycin phosphate 1.2%/ tretinoin 0.025% gel for facial acne: results of two single-center, evaluator-blinded, randomized, vehicle-controlled phase 1 studies in healthy volunteers.

PubMed

Murray, John; Potts, Aaron

2014-01-01

A fixed-dose combination of clindamycin phosphate 1.2% and tretinoin 0.025% gel (VELTIN® (clindamycin phosphate and tretinoin) 1.2%/0.025% Gel [VELTIN]) (clindamycin/tretinoin gel) is currently available for the once-daily topical treatment of acne. Two-phase I studies were conducted to evaluate the phototoxic and photoallergic potential of clindamycin/tretinoin gel. Study 1 (phototoxic) (n=37) and Study 2 (photoallergic) (n=58) were single-center, evaluator-blinded, randomized, vehicle-controlled, phase 1 studies conducted in healthy volunteers. In Study 1, clindamycin/tretinoin gel patches, vehicle gel patches and blank patches (no gel) were applied concurrently for 24 hours to naïve sites. After patch removal, sites were irradiated with 16 joules/cm2 of ultraviolet A light (UVA) then 0.75 minimal erythema dose (MED) of UVA/ultraviolet B light (UVB), the same irradiation protocol followed by 15 joules/cm2 of visible light (VIS), or served as non-irradiated controls. Study 2 examined the effect of repeated drug exposure and involved an induction period (6 repeat phases at the same body sites during which clindamycin/tretinoin gel and vehicle gel patches were applied for 24 hours, removed and sites irradiated with UVB +/- VIS), followed by a rest period (10 to 17 days), then a challenge period that used the protocol described for Study 1. In both studies, inflammatory responses and other cutaneous effects were evaluated at 1, 24, 48, and 72 hours after patch removal. No subject experienced any adverse events in Study 1 (phototoxic). One subject in Study 2 (photoallergic) experienced AEs (diffuse erythema; mild application site irritation at one each of UV/VIS-irradiated clindamycin/tretinoin gel and vehicle gel patch sites) considered definitely related to study product that resulted in discontinuation from the study. Data from Study 1 and the challenge phase from Study 2 showed most subjects had no visible inflammatory reaction to clindamycin/tretinoin gel after irradiation. Clindamycin/tretinoin gel has a favorable safety profile following UV/visible irradiation and a low potential for phototoxicity and photoallergenicity.

SU-E-T-105: Development of 3D Dose Verification System for Volumetric Modulated Arc Therapy Using Improved Polyacrylamide-Based Gel Dosimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ono, K; Fujimoto, S; Akagi, Y

2014-06-01

Purpose: The aim of this dosimetric study was to develop 3D dose verification system for volumetric modulated arc therapy (VMAT) using polyacrylamide-based gel (PAGAT) dosimeter improved the sensitivity by magnesium chloride (MgCl{sub 2}). Methods: PAGAT gel containing MgCl{sub 2} as a sensitizer was prepared in this study. Methacrylic-acid-based gel (MAGAT) was also prepared to compare the dosimetric characteristics with PAGAT gel. The cylindrical glass vials (4 cm diameter, 12 cm length) filled with each polymer gel were irradiated with 6 MV photon beam using Novalis Tx linear accelerator (Varian/BrainLAB). The irradiated polymer gel dosimeters were scanned with Signa 1.5 Tmore » MRI system (GE), and dose calibration curves were obtained using T{sub 2} relaxation rate (R{sub 2} = 1/T{sub 2}). Dose rate (100-600 MU min{sup −1}) and fractionation (1-8 fractions) were varied. In addition, a cubic acrylic phantom (10 × 10 × 10 cm{sup 3}) filled with improved PAGAT gel inserted into the IMRT phantom (IBA) was irradiated with VMAT (RapidArc). C-shape structure was used for the VMAT planning by the Varian Eclipse treatment planning system (TPS). The dose comparison of TPS and measurements with the polymer gel dosimeter was accomplished by the gamma index analysis, overlaying the dose profiles for a set of data on selected planes using in-house developed software. Results: Dose rate and fractionation dependence of improved PAGAT gel were smaller than MAGAT gel. A high similarity was found by overlaying the dose profiles measured with improved PAGAT gel dosimeter and the TPS dose, and the mean pass rate of the gamma index analysis using 3%/3 mm criteria was achieved 90% on orthogonal planes for VMAT using improved PAGAT gel dosimeter. Conclusion: In-house developed 3D dose verification system using improved polyacrylamide-based gel dosimeter had a potential as an effective tool for VMAT QA.« less

SU-E-T-753: Three-Dimensional Dose Distributions of Incident Proton Particle in the Polymer Gel Dosimeter and the Radiochromic Gel Dosimeter: A Simulation Study with MCNP Code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, M; Kim, G; Ji, Y

Purpose: The purpose of this study is to estimate the three-dimensional dose distributions in the polymer and the radiochromic gel dosimeter, and to identify the detectability of both gel dosimeters by comparing with the water phantom in case of irradiating the proton particles. Methods: The normoxic polymer gel and the LCV micelle radiochromic gel were used in this study. The densities of polymer and the radiochromic gel dosimeter were 1.024 and 1.005 g/cm{sup 3}, respectively. The dose distributions of protons in the polymer and radiochromic gel were simulated using Monte Carlo radiation transport code (MCNPX, Los Alamos National Laboratory). Themore » shape of phantom irradiated by proton particles was a hexahedron with the dimension of 12.4 × 12.4 × 15.0 cm{sup 3}. The energies of proton beam were 50, 80, and 140 MeV energies were directed to top of the surface of phantom. The cross-sectional view of proton dose distribution in both gel dosimeters was estimated with the water phantom and evaluated by the gamma evaluation method. In addition, the absorbed dose(Gy) was also calculated for evaluating the proton detectability. Results: The evaluation results show that dose distributions in both gel dosimeters at intermediated section and Bragg-peak region are similar with that of the water phantom. At entrance section, however, inconsistencies of dose distribution are represented, compared with water. The relative absorbed doses in radiochromic and polymer gel dosimeter were represented to be 0.47 % and 2.26 % difference, respectively. These results show that the radiochromic gel dosimeter was better matched than the water phantom in the absorbed dose evaluation. Conclusion: The polymer and the radiochromic gel dosimeter show similar characteristics in dose distributions for the proton beams at intermediate section and Bragg-peak region. Moreover the calculated absorbed dose in both gel dosimeters represents similar tendency by comparing with that in water phantom.« less

Meso-Decorated Switching-Knot Gels

NASA Astrophysics Data System (ADS)

Gong, Jin; Sawamura, Kensuke; Makino, Masato; Kabir, M. H.; Furukawa, Hidemitsu

Gels are a new material having three-dimensional network structures of macromolecules. They possess excellent properties as swellability, high permeability and biocompatibility, and have been applied in various fields of daily life, food, medicine, architecture, and chemistry .In this study, we tried to prepare new multi-functional and high-strength gels by using Meso-Decoration (Meso-Deco), one new method of structure design at intermediate mesoscale. High-performance rigid-rod aromatic polymorphic crystals. The strengthening of gels can be realized by meso-decorating the gels' structure using high-performance polymorphic crystals. New gels with good mechanical properties, novel optical properties and thermal properties are expected to be developed.

The Effect of Various Acids to the Gelation Process to the Silica Gel Characteristic Using Organic Silica

NASA Astrophysics Data System (ADS)

Rahman, NA; Widiyastuti, W.; Sigit, D.; Ajiza, M.; Sujana, W.

2018-01-01

Bagasse ash is solid waste of cane sugar industry which contain of silica more than 51%. Some previous study of silica gel from bagasse ash have been conducted often and been applied. This study concerns about the effect of various acid used in the process of gelation to the characteristic of silica gel produced. Then, this silica gel will be used as adsorbent. As that, the silica gel must fulfill the requirements of adsorbent, as have good pores characteristics, fit in mesoporous size so that adsorbent diffusion process is not disturbed. A fitted pores size of silica gel can be prepared by managing acid concentration used. The effect of acid, organic acid (tartaric acid) and inorganic acid (hydrochloric acid), is investigated in detail. The acid is added into sodium silicate solution in that the gel is formed, the pores structures can be investigated with BET, the crystal form is analyzed with XRD and the pore structure is analyzed visually with SEM. By managing the acid concentration added, it gets the effect of acid to the pore structure of silica gel. The bigger concentration is, the bigger the pore’s size of silica gel produced.

Prevention of postsurgical scars: comparsion of efficacy and convenience between silicone gel sheet and topical silicone gel.

PubMed

Kim, Sue-Min; Choi, Jung-Sik; Lee, Jung-Ho; Kim, Young-Jin; Jun, Young-Joon

2014-11-01

To date, few studies have compared the effectiveness of topical silicone gels versus that of silicone gel sheets in preventing scars. In this prospective study, we compared the efficacy and the convenience of use of the 2 products. We enrolled 30 patients who had undergone a surgical procedure 2 weeks to 3 months before joining the study. These participants were randomly assigned to 2 treatment arms: one for treatment with a silicone gel sheet, and the other for treatment with a topical silicone gel. Vancouver Scar Scale (VSS) scores were obtained for all patients; in addition, participants completed scoring patient questionnaires 1 and 3 months after treatment onset. Our results reveal not only that no significant difference in efficacy exists between the 2 products but also that topical silicone gels are more convenient to use. While previous studies have advocated for silicone gel sheets as first-line therapies in postoperative scar management, we maintain that similar effects can be expected with topical silicone gel. The authors recommend that, when clinicians have a choice of silicone-based products for scar prevention, they should focus on each patient's scar location, lifestyle, and willingness to undergo scar prevention treatment.

A study on the reproducibility and spatial uniformity of N-isopropylacrylamide polymer gel dosimetry using a commercial 10X fast optical-computed tomography scanner

NASA Astrophysics Data System (ADS)

Chang, Y. J.; Lin, J. Q.; Hsieh, B. T.; Chen, C. H.

2013-06-01

This study investigated the reproducibility and spatial uniformity of N-isopropylacrylamide (NIPAM) polymer gel as well as the reproducibility of a NIPAM polymer gel dosimeter. A commercial 10X fast optical computed tomography scanner (OCTOPUS-10X, MGS Research, Inc., Madison, CT, USA) was used as the readout tool of the NIPAM polymer gel dosimeter. A cylindrical NIPAM gel phantom measuring 10 cm (diameter) by 10 cm (height) by 3 mm (thickness) was irradiated by the four-field box treatment with a field size of 3 cm × 3 cm. The dose profiles were found to be consistent at the depths of 2.0 cm to 5.0 cm for two independent gel phantom batches, and the average uncertainty was less than 2%. The gamma pass rates were calculated to be between 94% and 95% at depths of 40 mm for two independent gel phantom batches using 4% dose difference and 4 mm distance-to-agreement criterion. The NIPAM polymer gel dosimeter was highly reproducible and spatially uniform. The results highlighted the potential of the NIPAM polymer gel dosimeter in radiotherapy.

Water Holding as Determinant for the Elastically Stored Energy in Protein-Based Gels.

PubMed

Pouvreau, Laurice; van Wijlen, Emke; Klok, Jan; Urbonaite, Vaida; Munialo, Claire D; de Jongh, Harmen H J

2016-04-01

To evaluate the importance of the water holding capacity for the elastically stored energy of protein gels, a range of gels were created from proteins from different origin (plant: pea and soy proteins, and animal: whey, blood plasma, egg white proteins, and ovalbumin) varying in network morphology set by the protein concentration, pH, ionic strength, or the presence of specific ions. The results showed that the observed positive and linear relation between water holding (WH) and elastically stored energy (RE) is generic for globular protein gels studied. The slopes of this relation are comparable for all globular protein gels (except for soy protein gels) whereas the intercept is close to 0 for most of the systems except for ovalbumin and egg white gels. The slope and intercept obtained allows one to predict the impact of tuning WH, by gel morphology or network stiffness, on the mechanical deformation of the protein-based gel. Addition of charged polysaccharides to a protein system leads to a deviation from the linear relation between WH and RE and this deviation coincides with a change in phase behavior. © 2016 Institute of Food Technologists®

Formation and functional properties of protein-polysaccharide electrostatic hydrogels in comparison to protein or polysaccharide hydrogels.

PubMed

Le, Xuan T; Rioux, Laurie-Eve; Turgeon, Sylvie L

2017-01-01

Protein and polysaccharide mixed systems have been actively studied for at least 50years as they can be assembled into functional particles or gels. This article reviews the properties of electrostatic gels, a recently discovered particular case of associative protein-polysaccharide mixtures formed through associative electrostatic interaction under appropriate solution conditions (coupled gel). This review highlights the factors influencing gel formation such as protein-polysaccharide ratio, biopolymer structural characteristics, final pH, ionic strength and total solid concentration. For the first time, the functional properties of protein-polysaccharide coupled gels are presented and discussed in relationship to individual protein and polysaccharide hydrogels. One of their outstanding characteristics is their gel water retention. Up to 600g of water per g of biopolymer may be retained in the electrostatic gel network compared to a protein gel (3-9g of water per g of protein). Potential applications of the gels are proposed to enable the food and non-food industries to develop new functional products with desirable attributes or new interesting materials to incorporate bioactive molecules. Copyright © 2016 Elsevier B.V. All rights reserved.

Creating Reconfigurable Materials Using ``Colonies'' of Oscillating Polymer Gels

NASA Astrophysics Data System (ADS)

Deb, Debabrata; Dayal, Pratyush; Kuksenok, Olga; Balazs, Anna

2013-03-01

Species ranging from single-cell organisms to social insects can undergo auto-chemotaxis, where the entities move towards a chemo-attractant that they themselves emit. This mode of signaling allows the organisms to form large-scale structures. Using computational modeling, we show that millimeter-sized polymer gels can display similar auto-chemotaxis. In particular, we demonstrate that gels undergoing the self-oscillating Belousov-Zhabotinsky (BZ) reaction not only respond to a chemical signal from the surrounding solution, but also emit this signal and thus, multiple gel pieces can spontaneously self-aggregate. We focus on the collective behavior of ``colonies'' of BZ gels and show that communication between the individual pieces critically depends on all the neighboring gels. We isolate the conditions at which the BZ gels can undergo a type of self-recombining: if a larger gel is cut into distinct pieces that are moved relatively far apart, then their auto-chemotactic behavior drives them to move and autonomously recombine into a structure resembling the original, uncut sample. These findings reveal that the BZ gels can be used as autonomously moving building blocks to construct multiple structures and thus, provide a new route for creating dynamically reconfigurable materials.

Transfer printing of thermoreversible ion gels for flexible electronics.

PubMed

Lee, Keun Hyung; Zhang, Sipei; Gu, Yuanyan; Lodge, Timothy P; Frisbie, C Daniel

2013-10-09

Thermally assisted transfer printing was employed to pattern thin films of high capacitance ion gels on polyimide, poly(ethylene terephthalate), and SiO2 substrates. The ion gels consisted of 20 wt % block copolymer poly(styrene-b-ethylene oxide-b-styrene and 80 wt % ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)amide. Patterning resolution was on the order of 10 μm. Importantly, ion gels containing the block polymer with short PS end blocks (3.4 kg/mol) could be transfer-printed because of thermoreversible gelation that enabled intimate gel-substrate contact at 100 °C, while gels with long PS blocks (11 kg/mol) were not printable at the same temperature due to poor wetting contact between the gel and substrates. By using printed ion gels as high-capacitance gate insulators, electrolyte-gated thin-film transistors were fabricated that operated at low voltages (<1 V) with high on/off current ratios (∼10(5)). Statistical analysis of carrier mobility, turn-on voltage, and on/off ratio for an array of printed transistors demonstrated the excellent reproducibility of the printing technique. The results show that transfer printing is an attractive route to pattern high-capacitance ion gels for flexible thin-film devices.

Ionic liquids gels: Soft materials for environmental remediation.

PubMed

Marullo, Salvatore; Rizzo, Carla; Dintcheva, Nadka T; Giannici, Francesco; D'Anna, Francesca

2018-05-01

Nanostructured sorbents and, in particular, supramolecular gels are emerging as efficient materials for the removal of toxic contaminants from water, like industrial dyes. It is also known that ionic liquids can dissolve significant amounts of dyes. Consequently, supramolecular ionic liquids gels could be highly efficient sorbents for dyes removal. This would also contribute to overcome the drawbacks associated with dye removal by liquid-liquid extraction with neat ionic liquids which would require large volumes of extractant and a more difficult separation of the phases. Herein we employed novel supramolecular ionic liquid gels based on diimidazolium salts bearing naturally occurring or biomass derived anions, to adsorb cationic and anionic dyes from wastewaters. We also carried out a detailed investigation of thermal, structural, morphological and rheological features of our gels to identify which of them are key in designing better sorbents for environmental remediation. The most effective gels showed fast and thorough removal of cationic dyes like Rhodamine B. These gels could also be reused up to 20 times without any loss in removal efficiency. Overall, our ionic gels outperform most of gel-based sorbents systems so far reported in literature. Copyright © 2018 Elsevier Inc. All rights reserved.

Preparation of a collagen/polymer hybrid gel designed for tissue membranes. Part I: controlling the polymer-collagen cross-linking process using an ethanol/water co-solvent.

PubMed

Nam, Kwangwoo; Kimura, Tsuyoshi; Funamoto, Seiichi; Kishida, Akio

2010-02-01

The drawback with collagen/2-methacryloyloxyethyl phosphorylcholine (MPC) polymer hybrid gels (collagen/phospholipid polymer hybrid gels) prepared in alkaline morpholinoethane sulfonic acid (MES) aqueous solution is that the cross-linking rate between the polymer and the collagen is low. To solve this problem, ethanol has been adopted as the reaction solvent, to prevent 1-ethyl-3-(3-dimethylaminopropyl)-1-carbodiimide hydrochloride (EDC) hydrolysis. Alterations in the ethanol mole concentration changed the cross-linking rate between the MPC polymer and the collagen gel. Prevention of EDC hydrolysis is clearly observed; protonation of carboxyl groups implies that the ratio of ethanol to water should be controlled. The polymer shows signs of penetration into the collagen gel layer, thus forming a totally homogeneous phase gel. This affects the mechanical strength of the collagen gel, making the gel much stiffer and brittle with an increase in the swelling ratio, as compared with that prepared in MES buffer. However, it is possible to obtain a collagen/phospholipid polymer hybrid gel with a high polymer portion and the cross-linking rate can be successfully controlled.

Thermostability of glucose oxidase in silica gel obtained by sol-gel method and in solution studied by fluorimetric method.

PubMed

Przybyt, Małgorzata; Miller, Ewa; Szreder, Tomasz

2011-04-04

The thermostability of glucose oxidase entrapped in silica gel obtained by sol-gel method was studied by thermostimulated fluorescence of FAD at pH 5 and 7 and compared with that of the native enzyme in the solution and at the presence of ethanol. The unfolding temperatures were found to be lower for the enzyme immobilised in gel as compared with the native enzyme but higher as for the enzyme at the presence of ethanol. In gel, the thermal denaturation of glucose oxidase is independent on pH while in solution the enzyme is more stable at pH 5. The investigation the enzyme in different environment by steady-state fluorescence of FAD and tryptophan, synchronous fluorescence and time-resolved fluorescence of tryptophan indicates that the state of the molecule (tertiary structure and molecular dynamics) is different in gel and in solution. The ethanol produced during gel precursor hydrolysis is not the main factor influencing the thermostability of the enzyme but more important are interactions of the protein with the gel lattice. Copyright © 2011 Elsevier B.V. All rights reserved.

Growth of Normal Mouse Vaginal Epithelial Cells in and on Collagen Gels

NASA Astrophysics Data System (ADS)

Iguchi, Taisen; Uchima, Francis-Dean A.; Ostrander, Patricia L.; Bern, Howard A.

1983-06-01

Sustained growth in primary culture of vaginal epithelial cells from ovariectomized adult BALB/cCrg1 mice embedded within or seeded on collagen gel matrix was achieved in a serum-free medium composed of Ham's F-12 medium/Dulbecco's modified Eagle's medium, 1:1 (vol/vol), supplemented with insulin, bovine serum albumin fraction V, epidermal growth factor, cholera toxin, and transferrin. Three-dimensional growth of vaginal epithelial cells occurred inside the collagen gel matrix. Cell numbers increased 4- to 8-fold in collagen gel and about 4-fold on collagen gel after 9-10 days in culture. The effect of 17β -estradiol (0.00018-180 nM in gel or 0.018-180 nM on gel) and diethylstilbestrol (DES; 0.0186-186 nM in gel) on the growth of vaginal epithelial cells was examined. The addition of estrogen did not enhance the growth of vaginal epithelial cells during this time period either in the complete medium or in a suboptimal medium. Cultures on floating collagen gels in the serum-free medium are composed of 1-3 cell layers with superficial cornification. Estrogen does not appear to be a direct mitogen for vaginal epithelial cells, at least in this system.

Radiation hardening in sol-gel derived Er{sup 3+}-doped silica glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hari Babu, B., E-mail: hariphy2012@gmail.com, E-mail: matthieu.lancry@u-psud.fr; León Pichel, Mónica; Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR CNRS-UPSud 8182, Université Paris Sud, 91405 Orsay

2015-09-28

The aim of the present paper is to report the effect of radiation on the Er{sup 3+}-doped sol-gel silica glasses. A possible application of these sol-gel glasses could be their use in harsh radiation environments. The sol-gel glasses are fabricated by densification of erbium salt-soaked nanoporous silica xerogels through polymeric sol-gel technique. The radiation-induced attenuation of Er{sup 3+}-doped sol-gel silica is found to increase with erbium content. Electron paramagnetic resonance studies reveal the presence of E′{sub δ} point defects. This happens in the sol-gel aluminum-silica glass after an exposure to γ-rays (kGy) and in sol-gel silica glass after an exposuremore » to electrons (MGy). The concentration levels of these point defects are much lower in γ-ray irradiated sol-gel silica glasses. When the samples are co-doped with Al, the exposure to γ-ray radiation causes a possible reduction of the erbium valence from Er{sup 3+} to Er{sup 2+} ions. This process occurs in association with the formation of aluminum oxygen hole centers and different intrinsic point defects.« less

Studies of matrix vesicle-induced mineralization in a gelatin gel

NASA Technical Reports Server (NTRS)

Boskey, A. L.; Boyan, B. D.; Doty, S. B.; Feliciano, A.; Greer, K.; Weiland, D.; Swain, L. D.; Schwartz, Z.

1992-01-01

Matrix vesicles isolated from fourth-passage cultures of chondrocytes were tested for their ability to induce hydroxyapatite formation in a gelatin gel in order to gain insight into the function of matrix vesicles in in situ mineralization. These matrix vesicles did not appear to be hydroxyapatite nucleators per se since the extent of mineral accumulation in the gel diffusion system was not altered by the presence of matrix vesicles alone, and in the vesicle containing gels, mineral crystals were formed whether associated with vesicles or not. In gels with these matrix vesicles and beta-glycerophosphate, despite the presence of alkaline phosphatase activity, there was no increase in mineral deposition. This suggested that in the gel system these culture-derived vesicles did not increase local phosphate concentrations. However, when known inhibitors of mineral crystal formation and growth (proteoglycan aggregates [4 mg/ml], or ATP [1 mM], or both proteoglycan and ATP) were included in the gel, more mineral was deposited in gels with the vesicles than in comparable gels without vesicles, indicating that enzymes within these vesicles were functioning to remove the inhibition. These data support the suggestion that one function of the extracellular matrix vesicles is to transport enzymes for matrix modification.

COUPLING THE ALKALINE-SURFACTANT-POLYMER TECHNOLOGY AND THE GELATION TECHNOLOGY TO MAXIMIZE OIL PRODUCTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malcolm Pitts; Jie Qi; Dan Wilson

2005-04-01

Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or more efficient areal sweep efficiency for those with high permeability contrast ''thief zones''. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more oil than waterflooding from swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or those with thief zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. A priormore » fluid-fluid report discussed interaction of different gel chemical compositions and alkaline-surfactant-polymer solutions. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in the fluid-fluid analyses. Aluminum-polyacrylamide, flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9. Chromium acetate-polyacrylamide flowing and rigid flowing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid flowing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Chromium acetate-xanthan gum rigid gels are not stable to subsequent alkaline-surfactant-polymer solution injection. Resorcinol-formaldehyde gels were stable to subsequent alkaline-surfactant-polymer solution injection. When evaluated in a dual core configuration, injected fluid flows into the core with the greatest effective permeability to the injected fluid. The same gel stability trends to subsequent alkaline-surfactant-polymer injected solution were observed. Aluminum citrate-polyacrylamide, resorcinol-formaldehyde, and the silicate-polyacrylamide gel systems did not produce significant incremental oil in linear corefloods. Both flowing and rigid flowing chromium acetate-polyacrylamide gels and the xanthan gum-chromium acetate gel system produced incremental oil with the rigid flowing gel producing the greatest amount. Higher oil recovery could have been due to higher differential pressures across cores. None of the gels tested appeared to alter alkaline-surfactant-polymer solution oil recovery. Total waterflood plus chemical flood oil recovery sequence recoveries were all similar.« less

In vitro wound healing and cytotoxic activity of the gel and whole-leaf materials from selected aloe species.

PubMed

Fox, Lizelle T; Mazumder, Anisha; Dwivedi, Anupma; Gerber, Minja; du Plessis, Jeanetta; Hamman, Josias H

2017-03-22

Aloe vera is one of the most important medicinal plants in the world with applications in the cosmetic industry and also in the tonic or health drink product market. Different parts of Aloe ferox and Aloe marlothii are used as traditional medicines for different applications. Although wound healing has been shown for certain aloe gel materials (e.g. A. vera ) previously, there are conflicting reports on this medicinal application of aloe leaf gel materials. The present study aimed at determining the wound healing properties of the gel and whole-leaf materials of Aloe vera, Aloe ferox and Aloe marlothii, as well as their cytotoxic effects on normal human keratinocyte cells (HaCaT). Nuclear magnetic resonance spectroscopy was used to chemically fingerprint the aloe gel and whole-leaf materials by identifying characteristic marker molecules of aloe gel and whole-leaf materials. An MTT assay was performed to determine the cytotoxicity of the various aloe whole-leaf and gel materials on HaCaT cells. Wound healing and in vitro cell migration were investigated with HaCaT cells by means of the CytoSelect™ assay kit. The in vitro wound healing assay suggested that all the aloe gel and whole-leaf materials examined, exhibited faster wound healing activity than the untreated control group. After 48h, all the aloe gel and whole-leaf materials almost completely caused full wound closure, displaying 98.07% (A. marlothii whole-leaf), 98.00% (A. vera gel), 97.20% (A. marlothii gel), 96.00% (A. vera whole-leaf), 94.00% (A. ferox gel) and 81.30% (A. ferox whole-leaf) wound closure, respectively. It was noteworthy that the gel materials of all the three aloe species exhibited significantly faster (p<0.05) wound healing actions when compared to their respective whole-leaf materials at 32h. The gel and whole-leaf materials of A. vera, A. ferox and A. marlothii have shown the ability to heal wounds at a faster rate and to a larger extent than untreated keratinocytes. The MTT assay results suggested that the gel and whole-leaf materials of all the selected Aloe species showed negligible toxicity towards the HaCaT cells. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

A thermodynamically-consistent large deformation theory coupling photochemical reaction and electrochemistry for light-responsive gels

NASA Astrophysics Data System (ADS)

Dehghany, Mohammad; Zhang, Haohui; Naghdabadi, Reza; Hu, Yuhang

2018-07-01

Gels are composed of crosslinked polymer network and solvent molecules. When the main chain network is incorporated with functional groups that can undergo photo-chemical reaction upon light irradiation, the gel becomes light-responsive. Under irradiation, the photosensitive groups may undergo photo-ionization process and generate charges that are attached to the main chain or diffuse into the solvent. The newly generated ions disturb the osmotic balance of the gel medium. As a result, water molecules and mobile ions are driven into or out of the network to compensate the osmotic imbalance, which eventually leads to macroscopic swelling or shrinking of the gel. In this work, we develop a rigorous nonequilibrium thermodynamic framework to study the coupled photo-chemo-electro-mechanical responses of the photo-ionizable gels. We first discuss the mathematical descriptions of the light propagation and photo-induced chemical reactions inside the gel, as well as the equations governing the kinetics of the photo-chemical reactions. We then explore the consequences of the fundamental laws of thermodynamics in deriving the governing equations of the photo-ionizable gels. The continuous light irradiation drives the gel system towards a new thermodynamic stationary state that is away from equilibrium and is accompanied by energy dissipation. Next, we focus on the photo stationary state of the gel and explore the consequences of the continuous irradiation on the mechanical response of the gel in both optically thin and optically thick configurations. In the optically thin cases, we quantitatively compare the theoretical prediction with experimental data available in the literature. In one example, we show that the model can quantitatively capture the photo-tunable volume-phase transition of the Poly(N-isopropylacrylamide) (PNIPAM) gel grafted with photo-responsive triphenylmethane leucocyanide groups. In another example, we show that the model can quantitatively study the effect of salt concentration and pH value of the external solution on the photo-induced swelling of the polyacrylamide gels incorporated with triphenylmethane leucohydroxide groups. Finally, for the optically thick gels, we develop a finite element code to study their inhomogeneous deformations due to the light attenuation. This work will be of great importance for precise control and optimal design of photo-ionizable gels in future applications.

Molecular weight dependency of polyrotaxane-cross-linked polymer gel extensibility.

PubMed

Ohmori, Kana; Abu Bin, Imran; Seki, Takahiro; Liu, Chang; Mayumi, Koichi; Ito, Kohzo; Takeoka, Yukikazu

2016-12-11

This work investigates the influence of the molecular weight of polyrotaxane (PR) cross-linkers on the extensibility of polymer gels. The polymer gels, which were prepared using PR cross-linkers of three different molecular weights but the same number of cross-linking points per unit volume of gel, have almost the same Young's modulus. By contrast, the extensibility and rupture strength of the polymer gels are substantially increased with increasing molecular weight of the PR cross-linker.

Fixation of radioactive ions in porous media with ion exchange gels

DOEpatents

Mercer, Jr., Basil W.; Godfrey, Wesley L.

1979-01-01

A method is provided for fixing radioactive ions in porous media by injecting into the porous media water-soluble organic monomers which are polymerizable to gel structures with ion exchange sites and polymerizing the monomers to form ion exchange gels. The ions and the particles of the porous media are thereby physically fixed in place by the gel structure and, in addition, the ions are chemically fixed by the ion exchange properties of the resulting gel.

Inter-crosslinking network gels having both shape memory and high ductility

NASA Astrophysics Data System (ADS)

Amano, Yoshitaka; Hidema, Ruri; Furukawa, Hidemitsu

2012-04-01

Medical treatment for injuries should be easy and quick in many accidents. Plasters or bandages are frequently used to wrap and fix injured parts. If plasters or bandages have additional smart functions, such as cooling, removability and repeatability, they will be much more useful and effective. Here we propose innovative biocompatible materials, that is, nontoxic high-strength shape-memory gels as novel smart medical materials. These smart gels were prepared from two monomers (DMAAm and SA), a polymer (HPC), and an inter-crosslinking agent (Karenz-MOI). In the synthesis of the gels, 1) a shape-memory copolymer network is made from the DMAAm and the SA, and 2) the copolymer and the HPC are crosslinked by the Karenz-MOI. Thus the crosslinking points are connected only between the different polymers. This is our original technique of developing a new network structure of gels, named Inter-Crosslinking Network (ICN). The ICN gels achieve high ductility, going up to 700% strain in tensile tests, while the ICN gels contain about 44% water. Moreover the SA has temperature dependence due to its crystallization properties; thus the ICN gels obtain shape memory properties and are named ICN-SMG. While the Young's modulus of the ICN-SMG is large below their crystallization temperature and the gels behave like plastic materials, the modulus becomes smaller above the temperature and the gels turn back to their original shape.

Preparation and in vitro evaluation of a pluronic lecithin organogel containing ricinoleic acid for transdermal delivery.

PubMed

Boddu, Sai Hs; Bonam, Sindhu Prabha; Wei, Yangjie; Alexander, Kenneth

2014-01-01

The present study deals with the preparation and in vitro evaluation of a Pluronic lecithin organogel gel containing ricinoleic acid for transdermal delivery. Blank Pluronic lecithin organogel gels were prepared using ricinoleic acid as the oil phase and characterized for pH, viscosity, gelation temperature, and microscopic structure. The optimized Pluronic lecithin organogel gel formulation was further evaluated using ketoprofen (10%) and dexamethasone (0.5%) as model drugs. The stability and in vitro permeability of ketoprofen and dexamethasone was evaluated and compared with the corresponding control formulation (Pluronic lecithin organogel gel made with isopropyl palmitate as the oil phase). The pH and viscosity of blank Pluronic lecithin organogel gel prepared with ricinoleic acid was comparable with the isopropyl palmitate Pluronic lecithin organogel gel. The thixotropic property of ricinoleic acid Pluronic lecithin organogel gel was found to be better than the control. Drug-loaded Pluronic lecithin organogel gels behaved in a similar manner and all formulations were found to be stable at 25 degrees C, 35 degrees C, and 40 degrees C for up to 35 days. The penetration profile of dexamethasone was similar from both the Pluronic lecithin organogel gels, while the permeability for ketoprofen from Pluronic lecithin organogel gel containing ricinoleic acid was found to be three times higher as compared to the control formulation.

Formulation and evaluation of once-a-day transdermal gels of diclofenac diethylamine.

PubMed

Baboota, S; Shakeel, F; Kohli, K

2006-03-01

The present study was undertaken to prepare and evaluate transdermal gels of diclofenac diethylamine (DDEA) containing penetration enhancers such as olesan oil and dimethyl sulfoxide (DMSO). Transdermal gels were prepared using different polymers such as carbopol-940, polyvinyl alcohol (PVA), hydroxy propyl methyl cellulose-K(4) M, hydroxy propyl cellulose-M, and sodium carboxy methyl cellulose. The formulated gels were subjected to physicochemical studies, in vitro release studies and in vitro skin permeations studies and were evaluated for drug content, viscosity, extrudability, spreadability, and pH. The in vitro release studies of prepared gels were performed using specially designed Fites cell and in vitro skin permeation studies were performed using keshary-chien diffusion cell through rat skin. Selected formulations were evaluated for their antiinflammatory activity using the carrageenan-induced paw edema in rats. The carbopol-940 and PVA gels containing 10% DMSO showed best in vitro skin permeation of DDEA. In vivo study for the selected formulation showed a sustained reduction in inflammation in the carrageenan induced paw edema in rats. The efficacies of carbopol-940 and PVA gels were also compared with that of the marketed Voveran gel,(R) and it was found that carbopol and PVA gels produced better results than the Voveran gel. (c) 2006 Prous Science. All rights reserved. (c) 2006 Prous Science. All rights reserved.

Deswelling kinetics of polyacrylate gels in solutions of cetyltrimethylammonium bromide.

PubMed

Nilsson, Peter; Hansson, Per

2007-08-23

The deswelling kinetics of single sodium polyacrylate gel beads (radius 40-160 microm) in aqueous solutions of cetyltrimethylammonium bromide under conditions of forced convection are investigated using micromanipulator assisted light microscopy. The purpose of the study is to further evaluate a previously published model (J. Phys. Chem. B 2003, 107, 9203) using a higher homolog surfactant. For gels with expected fast deswelling (small gel size/low surfactant concentration) and/or in low electrolyte concentration, the model is found to correctly predict the deswelling characteristics of the gel beads. However, for some gels with expected slow deswelling, especially in high electrolyte concentration (10 mM NaBr), the model widely underestimates the required deswelling time. The reason for this is argued to be the longer time frame and high bromide concentration allowing the formation of a denser, more ordered structure in the surface phase, which resists the deformation and reorganization of material necessary for deswelling. Unexpectedly long lag times before the start of deswelling are also found for gels in low surfactant concentration, indicating that a relatively high surfactant concentration in the gel, greatly exceeding the critical aggregation concentration, is needed to start formation of a collapsed surface phase. This critical surfactant concentration is found to be dependent on initial gel radius, as small gels require a relatively higher concentration to initiate collapse.

Network confinement and heterogeneity slows nanoparticle diffusion in polymer gels

NASA Astrophysics Data System (ADS)

Parrish, Emmabeth; Caporizzo, Matthew A.; Composto, Russell J.

2017-05-01

Nanoparticle (NP) diffusion was measured in polyacrylamide gels (PAGs) with a mesh size comparable to the NP size, 21 nm. The confinement ratio (CR), NP diameter/mesh size, increased from 0.4 to 3.8 by increasing crosslinker density and from 0.4 to 2.1 by adding acetone, which collapsed the PAGs. In all gels, NPs either became localized, moving less than 200 nm, diffused microns, or exhibited a combination of these behaviors, as measured by single particle tracking. Mean squared displacements (MSDs) of mobile NPs decreased as CR increased. In collapsed gels, the localized NP population increased and MSD of mobile NPs decreased compared to crosslinked PAGs. For all CRs, van Hove distributions exhibited non-Gaussian displacements, consistent with intermittent localization of NPs. The non-Gaussian parameter increased from a maximum of 1.5 for crosslinked PAG to 5 for collapsed PAG, consistent with greater network heterogeneity in these gels. Diffusion coefficients decreased exponentially as CR increased for crosslinked gels; however, in collapsed gels, the diffusion coefficients decreased more strongly, which was attributed to network heterogeneity. Collapsing the gel resulted in an increasingly tortuous pathway for NPs, slowing diffusion at a given CR. Understanding how gel structure affects NP mobility will allow the design and enhanced performance of gels that separate and release molecules in membranes and drug delivery platforms.

Effect of residual water content on the physico-chemical properties of sucralfate dried gel obtained by microwave drying.

PubMed

Gainotti, Alessandro; Losi, Elena; Bettini, Ruggero; Colombo, Paolo; Sonvico, Fabio; Baroni, Daniela; Santi, Patrizia; Colombo, Gaia

2005-08-01

The purpose of this study was to investigate the physico-chemical characteristics of sucralfate humid gel dried by microwaves, in relation to the residual water content. Differential scanning calorimetry (DSC) allowed for the determination of the water state in sucralfate samples. Fourier-transform infrared (FT-IR) spectroscopy was used to monitor the changes in sucralfate gel structure induced by the microwave drying. A boundary value of total water content for sucralfate gel samples was found at 42% (w/w). Below this value only bound water was present, whereas above this value, the increase in total water was due to free water. In the physical form of gel, the strength of the coordination between sulfate anions and the positively charged aluminum hydroxide was dependent on the residual water content. The study of the sedimentation behavior of water suspensions prepared with dried sucralfate allowed for the evaluation of the retention of gel properties. We found that the microwave drying process affected the sedimentation of sucralfate dried gel suspensions independent of the residual water content: when suspensions were prepared from sucralfate dried gel powders containing more than 42% (w/w) of residual water, the sedimentation ratio was higher than 0.9. The non-gel powder suspension showed a sedimentation ratio of 0.68 +/- 0.02, whereas the sucralfate humid gel suspension did not sediment.

Supramolecular Gel-Templated In Situ Synthesis and Assembly of CdS Quantum Dots Gels

NASA Astrophysics Data System (ADS)

Zhu, Lili; He, Jie; Wang, Xiaoliang; Li, Dawei; He, Haibing; Ren, Lianbing; Jiang, Biwang; Wang, Yong; Teng, Chao; Xue, Gi; Tao, Huchun

2017-01-01

Although many studies have attempted to develop strategies for spontaneously organizing nanoparticles (NPs) into three-dimensional (3D) geometries, it remains a fascinating challenge. In this study, a method for in situ synthesis and self-assembly of a CdS quantum dots (QDs) gel using a Cd supramolecular gel as a scaffold was demonstrated. During the QDs formation process, the Cd ions that constituted the Cd gels served as the precursors of the CdS QDs, and the oleic acid (OA) that ligated with the Cd in the supramolecular gels was capped on the surface of the CdS QDs in the form of carboxylate. The OA-stabilized CdS QDs were in situ synthesized in the entangled self-assembled fibrillar networks (SAFIN) of the Cd gels through reactions between the gelator and H2S. As a result, the QDs exactly replicated the framework of the SAFIN in the CdS QD gels instead of simply assembling along the SAFIN of the supramolecular gels. Moreover, the CdS QDs showed extraordinary sensitivity in the fluorescence detection of IO4 - anions. The facile one-step method developed here is a new approach to assembling nanostructured materials into 3D architectures and has general implications for the design of low molecular mass gelators to bring desired functionality to the developed supramolecular gels.

Oxygen diffusion and consumption in extracellular matrix gels: implications for designing three-dimensional cultures.

PubMed

Colom, Adai; Galgoczy, Roland; Almendros, Isaac; Xaubet, Antonio; Farré, Ramon; Alcaraz, Jordi

2014-08-01

Three-dimensional (3D) cultures are increasingly used as tissue surrogates to study many physiopathological processes. However, to what extent current 3D culture protocols provide physiologic oxygen tension conditions remains ill defined. To address this limitation, oxygen tension was measured in a panel of acellular or cellularized extracellular matrix (ECM) gels with A549 cells, and analyzed in terms of oxygen diffusion and consumption. Gels included reconstituted basement membrane, fibrin and collagen. Oxygen diffusivity in acellular gels was up to 40% smaller than that of water, and the lower values were observed in the denser gels. In 3D cultures, physiologic oxygen tension was achieved after 2 days in dense (≥3 mg/mL) but not sparse gels, revealing that the latter gels are not suitable tissue surrogates in terms of oxygen distribution. In dense gels, we observed a dominant effect of ECM composition over density in oxygen consumption. All diffusion and consumption data were used in a simple model to estimate ranges for gel thickness, seeding density and time-window that may support physiologic oxygen tension. Thus, we identified critical variables for oxygen tension in ECM gels, and introduced a model to assess initial values of these variables, which may short-cut the optimization step of 3D culture studies. © 2013 Wiley Periodicals, Inc.

Ionic liquid based multifunctional double network gel

NASA Astrophysics Data System (ADS)

Ahmed, Kumkum; Higashihara, Tomoya; Arafune, Hiroyuki; Kamijo, Toshio; Morinaga, Takashi; Sato, Takaya; Furukawa, Hidemitsu

2015-04-01

Gels are a promising class of soft and wet materials with diverse application in tissue engineering and bio-medical purpose. In order to accelerate the development of gels, it is required to synthesize multi-functional gels of high mechanical strength, ultra low surface friction and suitable elastic modulus with a variety of methods and new materials. Among many types of gel ionic gel made from ionic liquids (ILs) could be used for diverse applications in electrochemical devices and in the field of tribology. IL, a promising materials for lubrication, is a salt with a melting point lower than 100 °C. As a lubricant, ILs are characterized by an extremely low vapor pressure, high thermal stability and high ion conductivity. In this work a novel approach of making double network DN ionic gel using IL has been made utilizing photo polymerization process. A hydrophobic monomer Methyl methacrylate (MMA) has been used as a first network and a hydrophobic IL monomer, N,N-diethyl-N-(2-mthacryloylethyl)-N-methylammonium bistrifluoromethylsulfonyl)imide (DEMM-TFSI) has been used as a second network using photo initiator benzophenon and crosslinker triethylene glycol dimethacrylate (TEGDMA). The resulting DN ionic gel shows transparency, flexibility, high thermal stability, good mechanical toughness and low friction coefficient value which can be a potential candidate as a gel slider in different mechanical devices and can open a new area in the field of gel tribology.

Solvent exchange-induced in situ forming gel comprising ethyl cellulose-antimicrobial drugs.

PubMed

Phaechamud, Thawatchai; Mahadlek, Jongjan

2015-10-15

Solvent-exchanged in situ forming gel is a drug delivery system which is in sol form before administration. When it contacts with the body fluid, then the water miscible organic solvent dissipates and water penetrates into the system, leading the polymer precipitation as in situ gel at the site of injection. The aim of this research was to study the parameters affecting the gel properties, drug release and antimicrobial activities of the in situ forming gels prepared from ethyl cellulose (EC) dissolved in N-methyl pyrrolidone (NMP) to deliver the antimicrobial agents (doxycycline hyclate, metronidazole and benzyl peroxide) for periodontitis treatment. The gel appearance, pH, viscosity, rheology, syringeability, gel formation, rate of water diffusion into the gels, in vitro degradation, drug release behavior and antimicrobial activities against Staphylococcus aureus, Escherichia coli, Candida albicans, Streptococcus mutans and Porphyrommonas gingivalis were determined. Increasing the amount of EC increased the viscosity of system while still exhibiting Newtonian flow and increased the work of syringeability whereas decreased the releasing of drug. The system transformed into the rigid gel formation after being injected into the simulated gingival crevicular fluid. The developed systems containing 5% w/w antimicrobial agent showed the antimicrobial activities against all test bacteria. Thus the developed solvent exchange-induced in situ forming gels comprising EC-antimicrobial drugs exhibited potential use for periodontitis treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Aperture-Tolerant, Chemical-Based Methods to Reduce Channeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Randall S. Seright

2007-09-30

This final technical progress report describes work performed from October 1, 2004, through May 16, 2007, for the project, 'Aperture-Tolerant, Chemical-Based Methods to Reduce Channeling'. We explored the potential of pore-filling gels for reducing excess water production from both fractured and unfractured production wells. Several gel formulations were identified that met the requirements--i.e., providing water residual resistance factors greater than 2,000 and ultimate oil residual resistance factors (F{sub rro}) of 2 or less. Significant oil throughput was required to achieve low F{sub rro} values, suggesting that gelant penetration into porous rock must be small (a few feet or less) formore » existing pore-filling gels to provide effective disproportionate permeability reduction. Compared with adsorbed polymers and weak gels, strong pore-filling gels can provide greater reliability and behavior that is insensitive to the initial rock permeability. Guidance is provided on where relative-permeability-modification/disproportionate-permeability-reduction treatments can be successfully applied for use in either oil or gas production wells. When properly designed and executed, these treatments can be successfully applied to a limited range of oilfield excessive-water-production problems. We examined whether gel rheology can explain behavior during extrusion through fractures. The rheology behavior of the gels tested showed a strong parallel to the results obtained from previous gel extrusion experiments. However, for a given aperture (fracture width or plate-plate separation), the pressure gradients measured during the gel extrusion experiments were much higher than anticipated from rheology measurements. Extensive experiments established that wall slip and first normal stress difference were not responsible for the pressure gradient discrepancy. To explain the discrepancy, we noted that the aperture for gel flow (for mobile gel wormholing through concentrated immobile gel within the fracture) was much narrower than the width of the fracture. The potential of various approaches were investigated for improving sweep in parts of the Daqing Oil Field that have been EOR targets. Possibilities included (1) gel treatments that are directed at channeling through fractures, (2) colloidal dispersion gels, (3) reduced polymer degradation, (4) more viscous polymer solutions, and (5) foams and other methods. Fractures were present in a number of Daqing wells (both injectors and producers). Because the fractures were narrow far from the wellbore, severe channeling did not occur. On the contrary, fractures near the wellbore aided reservoir sweep. In the February 2006 issue of the Journal of Petroleum Technology, a 'Distinguished-Author-Series' paper claimed that a process using aqueous colloidal dispersion gels (CDG gels) performed superior to polymer flooding. Unfortunately, this claim is misleading and generally incorrect. Colloidal dispersion gels, in their present state of technological development, should not be advocated as an improvement to, or substitute for, polymer flooding.« less

Structural colored gels for tunable soft photonic crystals.

PubMed

Harun-Ur-Rashid, Mohammad; Seki, Takahiro; Takeoka, Yukikazu

2009-01-01

A periodically ordered interconnecting porous structure can be embodied in chemical gels by using closest-packed colloidal crystals as templates. The interconnecting porosity not only provides a quick response but also endows the porous gels with structural color arising from coherent Bragg optical diffraction. The structural colors revealed by porous gels can be regulated by several techniques, and thus, it is feasible to obtain desirable, smart, soft materials. A well-known thermosensitive monomer, N-isopropylacrylamide (NIPA), and other minor monomers were used to fabricate various structural colored gels. The selection of minor monomers depended on the targeted properties. This review focuses on the synthesis of templates, structural colored porous gels, and the applications of structural colored gel as smart soft materials for tunable photonic crystals. (c) 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Lipophilic polyelectrolyte gel derived from phosphonium borate can absorb a wide range of organic solvents.

PubMed

Sunaga, Sokuro; Kokado, Kenta; Sada, Kazuki

2018-01-24

Herein, we demonstrate a polyelectrolyte gel which can absorb a wide range of organic solvents from dimethylsulfoxide (DMSO, permittivity: ε = 47.0) to tetrahydrofuran (ε = 5.6). The gel consists of polystyrene chains with small amounts (∼5 mol%) of lipophilic electrolytes derived from triphenylphosphonium tetraaryl borate. The swelling ability of the polyelectrolyte gel was higher than that of the alkyl ammonium tetraaryl borate previously reported by us, and this is attributed to the higher compatibility with organic solvents, as well as the higher dissociating ability, of the triphenyl phosphonium salt. The role of the ionic moieties was additionally confirmed by post modification of the polyelectrolyte gel via a conventional Wittig reaction, resulting in a nonionic gel. Our findings introduced here will lead to a clear-cut molecular design for polyelectrolyte gels which absorb all solvents.

Tretinoin Photostability

PubMed Central

Harper, Julie; Pillai, Radhakrishnan; Moore, Robert

2012-01-01

Background: Various formulations of tretinoin (gel, liquid, cream) have been reported to be unstable on the skin under bright artificial light or sunlight. This photodegradation can potentially influence treatment regimens and possibly modify efficacy. The maximum light energy absorption of tretinoin is in the ultraviolet A region. Objective: To compare the photostability of a micronized formulation of tretinoin (0.05%) aqueos gel with tretinoin (0.025%) gel following exposure to ultraviolet A light for eight hours. Methods: Micronized tretinoin (0.05%) gel and tretinoin (0.025%) gel were then exposed to ultraviolet A light with an integrated intensity from 315 to 400nm of 22watt/m2. Samples of both products were prepared and analyzed for tretinoin and its degradation products using a high-performance liquid chromatography method. Additional duplicate samples were similarly prepared and analyzed after 2,4,6, and 8 hours. Results: There was a nine-percent degradation of micronized tretinoin in the 0.05% aqueous gel compared to 72-percent degradation of tretinoin in the 0.025% gel following eight-hour ultraviolet A light exposure. The small increase in tretinoin degradation products with micronized tretinoin (0.05%) aqueous gel remained below six percent of the labeled concentration compared to a marked increase in tretinoin degradation products with tretinoin 0.025% gel at two hours that increased to over 66-percent labeled concentration at eight hours. Conclusion: Micronized tretinoin (0.05%) aqueous gel showed less than 10-percent degradation when exposed to eight hours of ultraviolet A light, while tretinoin (0.025%) gel showed significant tretinoin degradation. PMID:22328956

Radiological properties of normoxic polymer gel dosimeters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Venning, A.J.; Nitschke, K.N.; Keall, P.J.

2005-04-01

The radiological properties of the normoxic polymer gel dosimeters MAGIC, MAGAS, and MAGAT [methacrylic and ascorbic acid in gelatin initiated by copper; methacrylic acid gelatine gel with ascorbic acid; and methacrylic acid gelatine and tetrakis (hydroxymethyl) phosphonium chloride, respectively] have been investigated. The radiological water equivalence was determined by comparing the polymer gel macroscopic photon and electron interaction cross sections over the energy range from 10 keV to 20 MeV and by Monte Carlo modeling of depth doses. Normoxic polymer gel dosimeters have a high gelatine and monomer concentration and therefore mass density (kg m{sup -3}) up to 3.8% highermore » than water. This results in differences between the cross-section ratios of the normoxic polymer gels and water of up to 3% for the attenuation, energy absorption, and collision stopping power coefficient ratios through the Compton dominant energy range. The mass cross-section ratios were within 2% of water except for the mass attenuation and energy absorption coefficients ratios, which showed differences with water of up to 6% for energies less than 100 keV. Monte Carlo modeling was undertaken for the polymer gel dosimeters to model the electron and photon transport resulting from a 6 MV photon beam. The absolute percentage differences between gel and water were within 1% and the relative percentage differences were within 3.5%. The results show that the MAGAT gel formulation is the most radiological water equivalent of the normoxic polymer gel dosimeters investigated due to its lower mass density measurement compared with MAGAS and MAGIC gels.« less

Improved gel electrophoresis matrix for hydrophobic protein separation and identification.

PubMed

Tokarski, Caroline; Fillet, Marianne; Rolando, Christian

2011-03-01

We propose an improved acrylamide gel for the separation of hydrophobic proteins. The separation strategy is based on the incorporation of N-alkylated and N,N'-dialkylated acrylamide monomers in the gel composition in order to increase hydrophobic interactions between the gel matrix and the membrane proteins. Focusing on the most efficient monomer, N,N'-dimethylacrylamide, the potentiality of the new matrix was evaluated on membrane proteins of the human colon HCT-116 cell line. Protein analysis was performed using an adapted analytical strategy based on FT-ICR tandem mass spectrometry. As a result of this comparative study, including advanced reproducibility experiments, more hydrophobic proteins were identified in the new gel (average GRAVY: -0.085) than in the classical gel (average GRAVY: -0.411). Highly hydrophobic peptides were identified reaching a GRAVY value up to 1.450, therefore indicating their probable locations in the membrane. Focusing on predicted transmembrane domains, it can be pointed out that 27 proteins were identified in the hydrophobic gel containing up to 11 transmembrane domains; in the classical gel, only 5 proteins containing 1 transmembrane domain were successfully identified. For example, multiple ionic channels and receptors were characterized in the hydrophobic gel such as the sodium/potassium channel and the glutamate or the transferrin receptors whereas they are traditionally detected using specific enrichment techniques such as immunoprecipitation. In total, membrane proteins identified in the classical gel are well documented in the literature, while most of the membrane proteins only identified on the hydrophobic gel have rarely or never been described using a proteomic-based approach. 2010 Elsevier Inc. All rights reserved.

Effectiveness of 1% versus 0.2% chlorhexidine gels in reducing alveolar osteitis from mandibular third molar surgery: A randomized, double-blind clinical trial

PubMed Central

Bravo-Pérez, Manuel; Sánchez-López, José D.; Muñoz-Soto, Esther; Romero-Olid, María N.; Baca-García, Pilar

2013-01-01

Purpose: Alveolar osteitis (AO) is the most common postoperative complication of dental extractions. The purpose of this study was to compare the effectiveness of 1% versus 0.2% chlorhexidine (CHX) gel in reducing postoperative AO after surgical extraction of mandibular third molars, and assess the impact of treatment on the Oral HealthRelated Quality of Life (OHRQoL). Material and Methods: This clinical study was a randomized, double-blind clinical trial. Eighty eight patients underwent surgical extraction of one retained mandibular third molar with the intra-alveolar application of 0.2% CHX gel. Afterwards, they were assigned to one of two groups: 1% CHX gel (n=42) or 0.2% CHX gel (n=46). The patients applied the gel twice a day to the wound for one week. All patients were evaluated for AO. Results: In the 0.2% CHX gel group, 13% of AO incidence was found, while in the 1% CHX gel group, AO incidence was 7%, a difference that was not statistically significant. Variables such as sensation of pain and inflammation at baseline and during one week, as well as OHRQoL of the patients at 24 hours and 7 days post-extraction, gave no statistically significant differences. Conclusions: There are no significant differences in AO after surgical extraction of mandibular third molars, when comparing applying 1% CHX gel twice a day for 7 days with 0.2% CHX gel. Key words:Alveolar osteitis, chlorhexidine gel, third molar. PMID:23722126

Investigation of microemulsion system for transdermal delivery of itraconazole

PubMed Central

Chudasama, Arpan; Patel, Vineetkumar; Nivsarkar, Manish; Vasu, Kamala; Shishoo, Chamanlal

2011-01-01

A new oil-in-water microemulsion-based (ME) gel containing 1% itraconazole (ITZ) was developed for topical delivery. The solubility of ITZ in oils and surfactants was evaluated to identify potential excipients. The microemulsion existence ranges were defined through the construction of the pseudoternary phase diagrams. The optimized microemulsion was characterized for its morphology and particle size distribution. The optimized microemulsion was incorporated into polymeric gels of Lutrol F127, Xanthan gum, and Carbopol 934 for convenient application and evaluated for pH, drug content, viscosity, and spreadability. In vitro drug permeation of ME gels was determined across excised rat skins. Furthermore, in vitro antimycotic inhibitory activity of the gels was conducted using agar-cup method and Candida albicans as a test organism. The droplet size of the optimized microemulsion was found to be <100 nm. The optimized Lutrol F 127 ME gel showed pH in the range of 5.68±0.02 and spreadability of 5.75±1.396 gcm/s. The viscosity of ME gel was found to be 1805.535±542.4 mPa s. The permeation rate (flux) of ITZ from prepared ME gel was found to be 4.234 μg/cm/h. The release profile exhibited diffusion controlled mechanism of drug release from ME ITZ gel. The developed ME gels were nonirritant and there was no erythema or edema. The antifungal activity of ITZ showed the widest zone of inhibition with Lutrol F127 ME gel. These results indicate that the studied ME gel may be a promising vehicle for topical delivery of ITZ. PMID:22171289

Specialist gelator for ionic liquids.

PubMed

Hanabusa, Kenji; Fukui, Hiroaki; Suzuki, Masahiro; Shirai, Hirofusa

2005-11-08

Cyclo(l-beta-3,7-dimethyloctylasparaginyl-L-phenylalanyl) (1) and cyclo(L-beta-2-ethylhexylasparaginyl-L-phenylalanyl) (2), prepared from L-asparaginyl-L-phenylalanine methyl ester, have been found to be specialist gelators for ionic liquids. They can gel a wide variety of ionic liquids, including imizazolium, pyridinium, pyrazolidinium, piperidinium, morpholinium, and ammonium salts. The mean minimum gel concentrations (MGCs) necessary to make gels at 25 degrees C were determined for ionic liquids. The gel strength increased at a rate nearly proportional to the concentration of added gelator. The strength of the transparent gel of 1-butylpyridinium tetrafluoroborate ([C(4)py]BF(4)), prepared at a concentration of 60 g L(-1) (gelator 1/[C(4)py]BF(4)), was ca. 1500 g cm(-2). FT-IR spectroscopy indicated that a driving force for gelation was intermolecular hydrogen bonding between amides and that the phase transition from gel to liquid upon heating was brought about by the collapse of hydrogen bonding. The gels formed from ionic liquids were very thermally stable; no melting occurs up to 140 degrees C when the gels were prepared at a concentration of 70 g L(-1) (gelator/ionic liquid). The ionic conductivities of the gels were nearly the same as those of pure ionic liquids. The gelator had electrochemical stability and a wide electrochemical window. When the gels were prepared from ionic liquids containing propylene carbonate, the ionic conductivities of the resulting gels increased to levels rather higher than those of pure ionic liquids. The gelators also gelled ionic liquids containing supporting electrolytes.

The solvent-gelator interaction as the origin of different diffusivity behavior of diols in gels formed with sugar-based low-molecular-mass gelator.

PubMed

Kowalczuk, Joanna; Bielejewski, Michał; Lapiński, Andrzej; Luboradzki, Roman; Tritt-Goc, Jadwiga

2014-04-10

Organogels are soft materials consisting of low-molecular-mass gelators (LMOGs) self-assembled through noncovalent interactions into 3D structures, in which free spaces are filled by organic solvents. 4,6,4',6'-O-terephthylidene-bis(methyl-α-d-glucopyranoside) (1) is found to be a new LMOG. It gelatinizes only a limited number of solvents. Here, the gels of 1 with ethylene glycol (EG) and 1,3-propanediol (PG) are investigated with FT-IR, Raman, and UV-vis spectroscopies, the NMR relaxometry and diffusometry methods, and microscopic observation. The chemical structures of both solvents are closely related, but the variety of physical characteristics of the gels is large. The 1/PG gels are thermally more stable compared to 1/EG gels. The types of aggregates are most likely the H- and J-type in 1/EG gels and the J-type in 1/PG gels. Different microstructures are observed: bundles of crossing fibers for 1/EG and a honeycomb-like matrix for 1/PG gels. The diffusivity of the EG solvent in gels with 1 behaves as expected, decreasing with increasing gelator concentration, whereas the opposite behavior is observed for the PG solvent. This is a most fascinating result. To explain the diffusion enhancement, we suggest that a dynamic hydrogen bonding network of PG solvent in gel matrixes is disrupted due to solvent-gelator interaction. The direct proof of this interaction is given by the observed low frequency dispersion of the spin-lattice relaxation time of solvents in the gel matrixes.

Study on Movable gel Profiling/Flooding System Optimization at Boundary Temperature

NASA Astrophysics Data System (ADS)

Gao, Shanshan; Xie, Gang; Zhang, Tiantian; Wang, Zhiqiang; Jiang, Peijun; Wei, Junjie; Gu, Yi; Lei, Xiaoyang; Guo, Suzhen; Lei, Shi

2017-12-01

65-75°C is the boundary temperature of phenol-formaldehyde resin and organic chrome crosslink with HPAM to generate movable gel. Generally speaking, when the reservoir temperature is below 65-75°C, the crosslinking agent is Organic chrome. Phenol-formaldehyde resin is used when the temperature is above 65-75°C. In this paper the gelation properties of phenol-formaldehyde resin and organic chrome were compared at 70°C. The experiment results showed that the crosslinking time of phenol-formaldehyde resin gel was longer and more conducive to field injection. In addition the phenol-formaldehyde resin gel had greater viscosity, adhesion and shearing resistance compared with the organic chrome gel. So the phenol-formaldehyde resin was chosen for further optimization. The crosslinking time was shortened and the gel viscosity increased with the increase of the polymer concentration. As the polymer crosslinker proportion increased The crosslinking time was shortened and the gel viscosity increased first and then decreased. Reinforcer NC and stabilizer WG were added to improve the temperature and salt tolerance of the gel. The gel formula suitable for the boundary temperature was obtained. The optimum polymer concentration is 1200mg/L, the polymer crosslinker proportion is 1:1.1, the best reinforcer concentration is 400mg/L and the concentration of the stabilizer is 150mg/L. The crosslinking time is 31h, the gel viscosity is above 2100mPa·s. The gel did not shrink and no water separation was observed at 70°C for 150 days. The viscosity retention rate was more than 70%.

Compatibility between weak gel and microorganisms in weak gel-assisted microbial enhanced oil recovery.

PubMed

Qi, Yi-Bin; Zheng, Cheng-Gang; Lv, Cheng-Yuan; Lun, Zeng-Min; Ma, Tao

2018-03-20

To investigate weak gel-assisted microbial flooding in Block Wang Long Zhuang in the Jiangsu Oilfield, the compatibility of weak gel and microbe was evaluated using laboratory experiments. Bacillus sp. W5 was isolated from the formation water in Block Wang Long Zhuang. The rate of oil degradation reached 178 mg/day, and the rate of viscosity reduction reached 75.3%. Strain W5 could produce lipopeptide with a yield of 1254 mg/L. Emulsified crude oil was dispersed in the microbial degradation system, and the average diameter of the emulsified oil particles was 18.54 μm. Bacillus sp. W5 did not affect the rheological properties of the weak gel, and the presence of the weak gel did not significantly affect bacterial reproduction (as indicated by an unchanged microbial biomass), emulsification (surface tension is 35.56 mN/m and average oil particles size is 21.38 μm), oil degradation (162 mg/day) and oil viscosity reduction (72.7%). Core-flooding experiments indicated oil recovery of 23.6% when both weak gel and Bacillus sp. W5 were injected into the system, 14.76% when only the weak gel was injected, and 9.78% with strain W5 was injected without the weak gel. The results demonstrate good compatibility between strains W5 and the weak gel and highlight the application potential of weak gel-assisted microbial flooding. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

New scale-down methodology from commercial to lab scale to optimize plant-derived soft gel capsule formulations on a commercial scale.

PubMed

Oishi, Sana; Kimura, Shin-Ichiro; Noguchi, Shuji; Kondo, Mio; Kondo, Yosuke; Shimokawa, Yoshiyuki; Iwao, Yasunori; Itai, Shigeru

2018-01-15

A new scale-down methodology from commercial rotary die scale to laboratory scale was developed to optimize a plant-derived soft gel capsule formulation and eventually manufacture superior soft gel capsules on a commercial scale, in order to reduce the time and cost for formulation development. Animal-derived and plant-derived soft gel film sheets were prepared using an applicator on a laboratory scale and their physicochemical properties, such as tensile strength, Young's modulus, and adhesive strength, were evaluated. The tensile strength of the animal-derived and plant-derived soft gel film sheets was 11.7 MPa and 4.41 MPa, respectively. The Young's modulus of the animal-derived and plant-derived soft gel film sheets was 169 MPa and 17.8 MPa, respectively, and both sheets showed a similar adhesion strength of approximately 4.5-10 MPa. Using a D-optimal mixture design, plant-derived soft gel film sheets were prepared and optimized by varying their composition, including variations in the mass of κ-carrageenan, ι-carrageenan, oxidized starch and heat-treated starch. The physicochemical properties of the sheets were evaluated to determine the optimal formulation. Finally, plant-derived soft gel capsules were manufactured using the rotary die method and the prepared soft gel capsules showed equivalent or superior physical properties compared with pre-existing soft gel capsules. Therefore, we successfully developed a new scale-down methodology to optimize the formulation of plant-derived soft gel capsules on a commercial scale. Copyright © 2017 Elsevier B.V. All rights reserved.

78 FR 19271 - Draft Guidance for Industry on Bioequivalence Recommendations for Metronidazole Vaginal Gel...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-29

... Metronidazole Vaginal Gel; Availability AGENCY: Food and Drug Administration, HHS. ACTION: Notice. SUMMARY: The... entitled ``Bioequivalence Recommendations for Metronidazole Vaginal Gel.'' The guidance provides specific...) for metronidazole vaginal gel. DATES: Although you can comment on any guidance at any time (see 21 CFR...

Spring-loaded polymeric gel actuators

DOEpatents

Shahinpoor, Mohsen

1995-01-01

Spring-loaded electrically controllable polymeric gel actuators are disclosed. The polymeric gels can be polyvinyl alcohol, polyacrylic acid, or polyacrylamide, and are contained in an electrolytic solvent bath such as water plus acetone. The action of the gel is mechanically biased, allowing the expansive and contractile forces to be optimized for specific applications.

Crystallization of Na2O-SiO2 gel and glass

NASA Technical Reports Server (NTRS)

Neilson, G. F.; Weinberg, M. C.

1984-01-01

The crystallization behavior of a 19 wt pct soda silica gel and gel-derived glass was compared to that of the ordinary glass of the same composition. Both bulk and ground glass samples were utilized. X-ray diffraction measurements were made to identify the crystalline phases and gauge the extent of crystallization. It was found that the gel crystallized in a distinctive manner, while the gel glass behavior was not qualitatively different from that of the ordinary glass.

Making MgO/SiO2 Glasses By The Sol-Gel Process

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1989-01-01

Silicon dioxide glasses containing 15 mole percent magnesium oxide prepared by sol-gel process. Not made by conventional melting because ingredients immiscible liquids. Synthesis of MgO/SiO2 glass starts with mixing of magnesium nitrate hexahydrate with silicon tetraethoxide, both in alcohol. Water added, and transparent gel forms. Subsequent processing converts gel into glass. Besides producing glasses of new composition at lower processing temperatures, sol-gel method leads to improved homogeneity and higher purity.

An improved silver staining procedure for schizodeme analysis in polyacrylamide gradient gels.

PubMed

Gonçalves, A M; Nehme, N S; Morel, C M

1990-01-01

A simple protocol is described for the silver staining of polyacrylamide gradient gels used for the separation of restriction fragments of kinetoplast DNA [schizodeme analysis of trypanosomatids (Morel et al., 1980)]. The method overcomes the problems of non-uniform staining and strong background color which are frequently encountered when conventional protocols for silver staining of linear gels are applied to gradient gels. The method described has proven to be of general applicability for DNA, RNA and protein separations in gradient gels.

Characterization of the Rheological and Swelling Properties of Synthetic Alkali Silicate Gels in Order to Predict Their Behavior in ASR Damaged Concrete

NASA Astrophysics Data System (ADS)

Vayghan, Asghar Gholizadeh

Alkali-silica reaction (ASR) is a major concrete durability concern that is responsible for the deterioration of concrete infrastructure in the world. The resultant of the reaction between the cement alkali hydroxides and the metastable silicates in the aggregates is a hygroscopic and expansive alkali-silicate gel (referred to as ASR gel in this document). The swelling behavior of ASR gels determines the extent of damage to concrete structures and, as such, mitigation of ASR relies on understanding these gels and finding ways to prevent them either from formation, or from swelling after formation. This dissertation focuses on the synthesis and characterization of ASR gels with wide ranges of compositions similar to what has been reported for the filed ASR gels in the literature. The experimental work consisted of three phases as follow. Phase I: Investigation of rheology, chemistry and physics of ASR gels produced through sol-method. Inspired from the existing literature, two sol-gel methods have been developed for the synthesis of ASR gels. The rheological (primarily gelation time, yield stress, and equilibrium stress), chemical (pore solution pH, pore solution composition, osmotic pressure, solid phase composition, stoichiometry of gelation reactions) and physical (evaporable water, solid content, etc.) properties of synthetic ASR gels have been extensively investigated in this phase. Ca/Si, Na/Si and K/Si, and water content were considered as the main chemical composition variables. In order to investigate the suppressing effects of lithium on the swelling properties of ASR gels, the gels were added with lithium in a part of the experimental program. The results strongly suggested that Ca/Si has a positive effect on the yield stress of the gels and their rate of gelation. Na/Si was found to have a decreasing effect on the yield stress and gelation rate (especially at low Ca/Si levels). K/Si and Li/Si had second-order (i.e., polynomial) effects on the yield stress of the gels, causing a significant drop in this parameter followed by some increase as they approached their upper values. Na/Si and K/Si were both found contribute to the osmotic potential of the ASR gels, while increase in Ca/Si generally led to a drop in this parameter. The presence of all components (Ca, Na, and K) were found to contribute to the pH of the gels' pore solution, and Ca/Si and Na/Si showed a synergistic effect on this parameter. Lithium, on the other hand, was found to be able to drop the OH- concentration of the pore solution by a factor of five in the case of high-sodium gels, which could partially explain its ASR mitigating effect. Phase II: Investigation of the free and restrained swelling behavior, hydrophilic potential and viscoelastic properties of ASR gels produced through the "paste method". 20 gel compositions were selected (using the central composite design method) with Ca/Si, Na/Si and K/Si molar ratios varying in the ranges (0.05-0.5), (0.1-1.0) and (0.0-0.3), respectively. The gels were produced by batching appropriate amounts of certain precursors containing different chemical components. After curing, the gels were tested for the abovementioned parameters using some innovative test methods as explained in the relevant chapters. The results suggest that increasing the alkali content (Na/Si and K/Si) in ASR gels resulted in an increase in the gels' free swelling and water absorption, and a reduction in the equilibrium relative humidity (ERH). However, no significant effect was found for Ca/Si with respect to the ERH. Ca/Si was found to have a multi-episode effect on the swelling and water absorption properties of the gels. An increase in Ca/Si up to 0.18 led to a considerable reduction in the swelling strain, followed by a slight increasing effect as it approached 0.4. Further increase in Ca/Si resulted in complete elimination of swelling strain. While Na/Si and K/Si could constantly increase the free swelling strain, their excessive presence was found to have a softening effect on the gels' structure, leading to a drop in their swelling pressure. Finally, all gels were found to show viscoelastic behavior that could be best explained via Burger's model. The elastic and viscous components have been measured for each gel and related to their composition using regression. Phase III: An Extended Chemical Index Model to Predict the Fly Ash Dosage Necessary for Mitigating Alkali-Silica Reaction in Concrete . In order to have an applied and ready-to-implement contribution to the realm of alkali-silica reaction, a predictive statistical model was developed that determines the optimum fly ash dosage for ASR mitigation depending on the acceptable risk of ASR and structure's importance. (Abstract shortened by ProQuest.).

Analysis of the adhesion of Pseudomonas putida NCIB 9816-4 to a silica gel as a model soil using extended DLVO theory.

PubMed

Hwang, Geelsu; Lee, Chang-Ha; Ahn, Ik-Sung; Mhin, Byung Jin

2010-07-15

The extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was applied to explain the hydrophobic interaction-mediated adhesion of Pseudomonas putida NCIB 9816-4 to soil. Soil particles are heterogeneous, and it is difficult to define consistent physico-chemical properties such as a contact angle and zeta potential. Hence, a silica gel and a silanized (3-aminopropyltriethoxysilane-coated) silica gel, which showed greater hydrophobicity than the unmodified silica gel, were used as model soils. Gibbs energies for the cell adhesion to the silica gels were calculated with the physico-chemical properties of the microbes and the silica gels and then plotted as a function of the separation distance. The extended DLVO theory successfully explained that the adhesion of P. putida NCIB 9816-4 to the silica gel, a model soil, was primarily caused by hydrophobic interaction. 2010 Elsevier B.V. All rights reserved.

Solution Processable Electrochemiluminescent Ion Gels for Flexible, Low Voltage, Emissive Displays on Plastic

NASA Astrophysics Data System (ADS)

Moon, Hong Chul; Lodge, Timothy P.; Frisbie, C. Daniel

2014-03-01

We have expanded the functionality of ion gels and successfully demonstrated low voltage, flexible electrochemiluminescent (ECL) devices using patterned ECL gels. An ECL device composed of only an emissive gel and two electrodes was fabricated on an ITO-coated substrate by solution casting the ECL gel and brush-painting the top silver electrode. The device turned on at an AC voltage as low as 2.6 V (-1.3 V ~ +1.3 V) and showed a relatively rapid response (sub-ms). Also, we varied the mechanical properties of the ECL gel simply by substituting polystyrene-block-poly(methyl methacrylate)-block-polystyrene (SMS) with commercially available poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-co-HFP)), enabling the fabrication of flexible ECL devices on any target substrate by the ``cut-and-stick'' strategy. This simple, rubbery ECL gel should be attractive for flexible electronics applications such as displays on packaging.

Liquid Whey Protein Concentrates Produced by Ultrafiltration as Primary Raw Materials for Thermal
Dairy Gels

PubMed Central

2017-01-01

Summary The aim of this work is to study the gelation properties of liquid whey protein concentrates (LWPC) produced by ultrafiltration (UF) as raw material for thermally induced gels intended for food applications. LWPC thermal gelation was performed using different types of LWPC (non-
-defatted, defatted and diafiltered) of different protein mass fractions and pH. Most of the produced gels showed viscoelastic behaviour. Non-defatted LWPC gave stronger heat-induced gels with a more cohesive microstructure, a higher water holding capacity and also higher elastic modulus (G’) and viscous modulus (G’’). Gel properties were not improved in products with lower content of non-protein compounds. As expected, the increase in protein mass fraction positively influences protein interactions. However, the pH is responsible for the equilibrium between attraction and repulsion forces in the gel components that influence gel hardness and water holding capacity. PMID:29540980

Liquid Whey Protein Concentrates Produced by Ultrafiltration as Primary Raw Materials for Thermal
Dairy Gels.

PubMed

Henriques, Marta; Gomes, David; Pereira, Carlos

2017-12-01

The aim of this work is to study the gelation properties of liquid whey protein concentrates (LWPC) produced by ultrafiltration (UF) as raw material for thermally induced gels intended for food applications. LWPC thermal gelation was performed using different types of LWPC (non-
-defatted, defatted and diafiltered) of different protein mass fractions and pH. Most of the produced gels showed viscoelastic behaviour. Non-defatted LWPC gave stronger heat-induced gels with a more cohesive microstructure, a higher water holding capacity and also higher elastic modulus (G') and viscous modulus (G''). Gel properties were not improved in products with lower content of non-protein compounds. As expected, the increase in protein mass fraction positively influences protein interactions. However, the pH is responsible for the equilibrium between attraction and repulsion forces in the gel components that influence gel hardness and water holding capacity.

Development of poloxamer gel formulations via hot-melt extrusion technology.

PubMed

Mendonsa, Nicole S; Murthy, S Narasimha; Hashemnejad, Seyed Meysam; Kundu, Santanu; Zhang, Feng; Repka, Michael A

2018-02-15

Poloxamer gels are conventionally prepared by the "hot" or the "cold" process. But these techniques have some disadvantages such as high energy consumption, requires expensive equipment and often have scale up issues. Therefore, the objective of this work was to develop poloxamer gels by hot-melt extrusion technology. The model drug selected was ketoprofen. The formulations developed were 30% and 40% poloxamer gels. Of these formulations, the 30% poloxamer gels were selected as ideal gels. DSC and XRD studies showed an amorphous nature of the drug after extrusion. It was observed from the permeation studies that with increasing poloxamer concentration, a decrease in drug permeation was obtained. Other studies conducted for the formulations included in-vitro release studies, texture analysis, rheological studies and pH measurements. In conclusion, the hot-melt extrusion technology could be successfully employed to develop poloxamer gels by overcoming the drawbacks associated with the conventional techniques. Published by Elsevier B.V.

Automated apparatus for producing gradient gels

DOEpatents

Anderson, N.L.

1983-11-10

Apparatus for producing a gradient gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density gradient along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and vertical arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.

Automated apparatus for producing gradient gels

DOEpatents

Anderson, Norman L.

1986-01-01

Apparatus for producing a gradient gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density gradient along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and vertical arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.

2D dose distribution images of a hybrid low field MRI-γ detector

NASA Astrophysics Data System (ADS)

Abril, A.; Agulles-Pedrós, L.

2016-07-01

The proposed hybrid system is a combination of a low field MRI and dosimetric gel as a γ detector. The readout system is based on the polymerization process induced by the gel radiation. A gel dose map is obtained which represents the functional part of hybrid image alongside with the anatomical MRI one. Both images should be taken while the patient with a radiopharmaceutical is located inside the MRI system with a gel detector matrix. A relevant aspect of this proposal is that the dosimetric gel has never been used to acquire medical images. The results presented show the interaction of the 99mTc source with the dosimetric gel simulated in Geant4. The purpose was to obtain the planar γ 2D-image. The different source configurations are studied to explore the ability of the gel as radiation detector through the following parameters; resolution, shape definition and radio-pharmaceutical concentration.

Spring-loaded polymeric gel actuators

DOEpatents

Shahinpoor, M.

1995-02-14

Spring-loaded electrically controllable polymeric gel actuators are disclosed. The polymeric gels can be polyvinyl alcohol, polyacrylic acid, or polyacrylamide, and are contained in an electrolytic solvent bath such as water plus acetone. The action of the gel is mechanically biased, allowing the expansive and contractile forces to be optimized for specific applications. 5 figs.

Outdoor weathering of sol-gel-treated wood

Treesearch

Mandla A Tshabalala; Ryan Libert; Nancy Ross Sutherland

2009-01-01

Outdoor weathering of wood specimens treated with sol-gel formulations based on methyltrimethoxysilane (MTMOS), hexadecyltrimethoxysilane (HDTMOS), and ferric-zirconia-titania (Fe-Zr-Ti) sol was evaluated. The sol-gel process allowed deposition of a thin film of hybrid inorganic-organic networks (gel) in the wood cell wall that resulted in improved outdoor weathering...

40 CFR 721.9680 - Alkaline titania silica gel (generic name).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkaline titania silica gel (generic... Specific Chemical Substances § 721.9680 Alkaline titania silica gel (generic name). (a) Chemical substance... alkaline titania silica gel (PMN P-95-529) is subject to reporting under this section for the significant...

40 CFR 721.9680 - Alkaline titania silica gel (generic name).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkaline titania silica gel (generic... Specific Chemical Substances § 721.9680 Alkaline titania silica gel (generic name). (a) Chemical substance... alkaline titania silica gel (PMN P-95-529) is subject to reporting under this section for the significant...

40 CFR 721.9680 - Alkaline titania silica gel (generic name).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkaline titania silica gel (generic... Specific Chemical Substances § 721.9680 Alkaline titania silica gel (generic name). (a) Chemical substance... alkaline titania silica gel (PMN P-95-529) is subject to reporting under this section for the significant...

40 CFR 721.9680 - Alkaline titania silica gel (generic name).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkaline titania silica gel (generic... Specific Chemical Substances § 721.9680 Alkaline titania silica gel (generic name). (a) Chemical substance... alkaline titania silica gel (PMN P-95-529) is subject to reporting under this section for the significant...

40 CFR 721.9680 - Alkaline titania silica gel (generic name).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkaline titania silica gel (generic... Specific Chemical Substances § 721.9680 Alkaline titania silica gel (generic name). (a) Chemical substance... alkaline titania silica gel (PMN P-95-529) is subject to reporting under this section for the significant...

40 CFR 63.5734 - What standards must I meet for resin and gel coat application equipment cleaning operations?

Code of Federal Regulations, 2010 CFR

2010-07-01

...? (a) For routine flushing of resin and gel coat application equipment (e.g., spray guns, flowcoaters... and gel coat application equipment cleaning operations? 63.5734 Section 63.5734 Protection of... Pollutants for Boat Manufacturing Standards for Resin and Gel Coat Application Equipment Cleaning Operations...

75 FR 47027 - In the Matter of: Certain Devices Having Elastomeric Gel and Components Thereof; Notice of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-04

... Elastomeric Gel and Components Thereof; Notice of Investigation AGENCY: U.S. International Trade Commission... importation, and the sale within the United States after importation of certain devices having elastomeric gel... after importation of certain devices having elastomeric gel and components thereof that infringe one or...

Polyimide Aerogels with Three-Dimensional Cross-Linked Structure

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B. (Inventor)

2016-01-01

A method for creating a three dimensional cross-linked polyimide structure includes dissolving a diamine, a dianhydride, and a triamine in a solvent, imidizing a polyamic acid gel by heating the gel, extracting the gel in a second solvent, supercritically drying the gel, and removing the solvent to create a polyimide aerogel.

Comparison of gel properties and biochemical characteristics of myofibrillar protein from bighead carp (Aristichthys nobilis) affected by frozen storage and a hydroxyl radical-generation oxidizing system.

PubMed

Lu, Han; Zhang, Longteng; Li, Qingzheng; Luo, Yongkang

2017-05-15

We wanted to clarify whether gel properties can be affected by in vivo or in vitro myofibrillar protein oxidation and, thus, to provide relevant information and a scientific foundation for the processing of gel products. To accomplish this, we measured the changes in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), total disulfide (SS) content, surface hydrophobicity (So-ANS), carbonyl content, and gel texture and water-holding capacity (WHC) of isolated myofibrillar protein from bighead carp fillets during frozen storage and under different H 2 O 2 concentrations, which were used to represent in vivo and in vitro conditions, respectively. The results indicated that a certain range in content of disulfide crosslinks (0.91mol/10 5 g protein) would promote gel hardness. Mild protein oxidation caused by a certain degree of frozen storage and hydroxyl radicals can promote gel texture and WHC. Based on those results, freezing bighead carp for a certain period can be used to produce gel products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development of hydroxyapatite-chitosan gel sunscreen combating clinical multidrug-resistant bacteria

NASA Astrophysics Data System (ADS)

Morsy, Reda; Ali, Sameh S.; El-Shetehy, Mohamed

2017-09-01

The several harmful effects on infected human skin resulting from exposure to the sun's UV radiation generate an interest in the development of a multifunctional hydroxyapatite-chitosan (HAp-chitosan) gel that works as an antibacterial sunscreen agent for skin care. In this work, HAp-chitosan gel was synthesized via coprecipitation method by dissolving chitosan in phosphoric acid and adding HAp. The characteristics of HAp-chitosan composite were investigated by conventional techniques, such as XRD, FTIR, and SEM techniques, while its sunscreen property was investigated by UV-spectroscopy. In addition to the influence of the gel on bacterial cell morphology, the antibacterial activity of HAp-chitosan gel against clinical multidrug resistant skin pathogens, such as Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa has been studied. The results revealed the formation of HAp-chitosan gel having nanosized particles, which confers protection against UV-radiation. The antibacterial activity records showed that chitosan-HAp gel exhibits a significant effect on the growth and ultrastructure of multi-drug resistant bacterial activities. Therefore, the chitosan-HAp gel is promising for skin health care as an antibacterial sunscreen.

Enhanced mixing in polyacrylamide gels containing embedded silica nanoparticles as internal electroosmotic pumps.

PubMed

Matos, Marvi A; White, Lee R; Tilton, Robert D

2008-02-15

Many biosensors, including those based on sensing agents immobilized inside hydrogels, suffer from slow response dynamics due to mass transfer limitations. Here we present an internal pumping strategy to promote convective mixing inside crosslinked polymer gels. This is envisioned as a potential tool to enhance biosensor response dynamics. The method is based on electroosmotic flows driven by non-uniform, oscillating electric fields applied across a polyacrylamide gel that has been doped with charged colloidal silica inclusions. Evidence for enhanced mixing was obtained from florescence recovery after photobleaching (FRAP) measurements with fluorescein tracer dyes dissolved in the gel. Mixing rates in silica-laden gels under the action of the applied electric fields were more than an order of magnitude faster than either diffusion or electrophoretically driven mixing in gels that did not contain silica. The mixing enhancement was due in comparable parts to the electroosmotic pumping and to the increase in gel swelling caused by the presence of the silica inclusions. The latter had the effect of increasing tracer mobility in the silica-laden gels.

Molecular structural differences between low methoxy pectins induced by pectin methyl esterase II: effects on texture, release and perception of aroma in gels of similar modulus of elasticity.

PubMed

Kim, Yang; Kim, Young-Suk; Yoo, Sang-Ho; Kim, Kwang-Ok

2014-02-15

Six low-methoxy pectins with different degrees of methylesterification and amidation, and molecular weights were used to prepare gels with similar moduli of elasticity by varying the concentrations of pectin and calcium phosphate. Five aroma compounds were added to the gels and their sensory textural properties, release and perception of aromas were investigated. Sensory firmness, springiness, adhesiveness, chewiness and cohesiveness differed according to the gel type, even though the moduli of elasticity were not significantly different (p<0.05). Release and perception of aromas also displayed significant difference according to the gel type (p<0.05). Low-methoxy amidated pectin exhibited the lowest release and perception for all the aroma compounds, while pectin-methylesterase-treated pectin gels exhibited relatively higher aroma release and perception. These results showed that the structural properties of pectins and gelling factors that increase the non-polar character of the gel matrices could decrease the release and perception of aromas in pectin gel systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

Establishment of gel materials with different mechanical properties by 3D gel printer SWIM-ER

NASA Astrophysics Data System (ADS)

Ota, Takafumi; Tase, Taishi; Okada, Koji; Saito, Azusa; Takamatsu, Kyuuichiro; Kawakami, Masaru; Furukawa, Hidemitsu

2016-04-01

A 3D printer is a device which can directly produce objects whose shape is the same as the original 3D digital data. Hydrogels have unique properties such as high water content, low frictional properties, biocompatibility, material permeability and high transparency, which are rare in hard and dry materials. These superior characteristics of gels promise useful medical applications. We have been working on the development of a 3D gel printer, SWIM-ER (Soft and Wet Industrial - Easy Realizer), which can make models of organs and artificial blood vessels with gel material. However, 3D printing has a problem: the mechanical properties of the printed object vary depending on printing conditions, and this matter was investigated with SWIM-ER. In the past, we found that mechanical properties of 3D gel objects depend on the deposition orientation in SWIM-ER. In this study, gels were printed with different laser scanning speeds. The mechanical properties of these gels were investigated by compression tests, water content measurements and SMILS (Scanning Microscopic Light Scattering).

Changes in the myosin secondary structure and shrimp surimi gel strength induced by dense phase carbon dioxide.

PubMed

Guo, Minghui; Liu, Shucheng; Ismail, Marliya; Farid, Mohammed M; Ji, Hongwu; Mao, Weijie; Gao, Jing; Li, Chengyong

2017-07-15

Dense phase carbon dioxide (DPCD) could induce protein conformation changes. Myosin and shrimp surimi from Litopenaeus vannamei were treated with DPCD at 5-25MPa and 40-60°C for 20min. Myosin secondary structure was investigated by circular dichroism and shrimp surimi gel strength was determined using textural analysis to develop correlations between them. DPCD had a greater effect on secondary structure and gel strength than heating. With increasing pressure and temperature, the α-helix content of DPCD-treated myosin decreased, while the β-sheet, β-turn and random coil contents increased, and the shrimp surimi gel strength increased. The α-helix content was negatively correlated with gel strength, while the β-sheet, β-turn and random coil contents were positively correlated with gel strength. Therefore, when DPCD induced myosin to form a gel, the α-helix of myosin was unfolded and gradually converted to a β-sheet. Such transformations led to protein-protein interactions and cross-linking, which formed a three-dimensional network to enhance the gel strength. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mass spectrometry compatible surfactant for optimized in-gel protein digestion.

PubMed

Saveliev, Sergei V; Woodroofe, Carolyn C; Sabat, Grzegorz; Adams, Christopher M; Klaubert, Dieter; Wood, Keith; Urh, Marjeta

2013-01-15

Identification of proteins resolved by SDS-PAGE depends on robust in-gel protein digestion and efficient peptide extraction, requirements that are often difficult to achieve. A lengthy and laborious procedure is an additional challenge of protein identification in gel. We show here that with the use of the mass spectrometry compatible surfactant sodium 3-((1-(furan-2-yl)undecyloxy)carbonylamino)propane-1-sulfonate, the challenges of in-gel protein digestion are effectively addressed. Peptide quantitation based on stable isotope labeling showed that the surfactant induced 1.5-2 fold increase in peptide recovery. Consequently, protein sequence coverage was increased by 20-30%, on average, and the number of identified proteins saw a substantial boost. The surfactant also accelerated the digestion process. Maximal in-gel digestion was achieved in as little as one hour, depending on incubation temperature, and peptides were readily recovered from gel eliminating the need for postdigestion extraction. This study shows that the surfactant provides an efficient means of improving protein identification in gel and streamlining the in-gel digestion procedure requiring no extra handling steps or special equipment.

Gel-like properties of MCM-41 material and its transformation to MCM-50 in a caustic alkaline surround

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saputra, Hens; Othman, Raihan, E-mail: raihan@iium.edu.my; Sutjipto, A.G.E.

2012-03-15

Highlights: Black-Right-Pointing-Pointer MCM-41 material transforms gradually into MCM-50 lamellar gel upon controlled exposure to 6 M KOH. Black-Right-Pointing-Pointer The formation of MCM-50 ordered gel structure occurs at KOH weight content of 40-70 wt. %. Black-Right-Pointing-Pointer MCM gel phase shows pseudoplastic behavior and possesses homogeneous matrix texture. -- Abstract: MCM-41 material, prepared by sol-gel method, reveals gel-like properties in a caustic alkaline environment, i.e., 6 M potassium hydroxide (KOH) electrolyte. The gellation of MCM-41 starts at a KOH weight ratio of 40 wt.%. The structural change of the material is verified with X-Ray diffractograms and supported by observation using Scanning Electronmore » Microscope (SEM). As the KOH weight ratio increases, the MCM-41 hexagonal arrays structure gradually transforms into MCM-50 lamellar structure before disappearing completely at 80 wt.% KOH. The MCM gel phase is further characterized by rotational viscometry and texture analysis. The gel phase shows shear thinning or pseudoplastic behavior and possesses homogeneous matrix structure.« less

Fabrication and evaluation of variable focus and large deformation plano-convex microlens based on non-ionic poly(vinyl chloride)/dibutyl adipate gels

NASA Astrophysics Data System (ADS)

Kim, Sang-Youn; Yeo, Myoung; Shin, Eun-Jae; Park, Won-Hyeong; Jang, Jong-Seok; Nam, Byeong-Uk; Bae, Jin Woo

2015-11-01

In this paper, we propose a variable focus microlens module based on a transparent, electroactive, and non-ionic PVC/DBA gel. A non-ionic PVC/DBA (nPVC) gel on an ITO glass was confined beneath a rigid annular electrode, and applied pressure squeezed a bulge of the nPVC gel into the annular electrode, resulting in a hemispherical plano-convex nPVC gel microlens. The proposed nPVC gel microlens was analyzed and optimized. When voltage is applied to the circular perimeter (the annular electrode) of this fabricated microlens, electrically induced creep deformation of the nPVC gel occurs, changing its optical focal length. The focal length remarkably increases from 3.8 mm up to 14.3 mm with increasing applied voltages from 300 V to 800 V. Due to its compact, transparent, and electroactive characteristics, the proposed nPVC gel microlens can be easily inserted into small consumer electronic devices, such as digital cameras, camcorders, cell phones, and other portable optical devices.

Quality change of apple slices coated with Aloe vera gel during storage.

PubMed

Song, Hye-Yeon; Jo, Wan-Shin; Song, Nak-Bum; Min, Sea C; Song, Kyung Bin

2013-06-01

Fresh-cut apples are easily susceptible to browning and microbial spoilage. In this study, an edible coating prepared from Aloe vera gel containing antibrowning solution was applied to preserve the quality of fresh-cut apples during storage. Fresh-cut apples were treated with both an Aloe vera gel and an Aloe vera gel containing 0.5% cysteine and then stored at 4 °C for 16 d. The color, firmness, weight loss, soluble solid content, titratable acidity, microbial analysis, and sensory evaluation were analyzed during storage. Fresh-cut apples coated with the Aloe vera gel showed delayed browning and reduced weight loss and softening compared to the control. The Aloe vera gel coating was also effective in reducing the populations of the total aerobic bacteria and yeast and molds. In particular, Aloe vera gel containing 0.5% cysteine was most effective in delaying browning and the reduction of microbial populations among the treatments. These results suggest that an Aloe vera gel coating can be used for maintaining the quality of fresh-cut apples. © 2013 Institute of Food Technologists®

Analysis of PEG oligomers in black gel inks: Discrimination and ink dating.

PubMed

Sun, Qiran; Luo, Yiwen; Xiang, Ping; Yang, Xu; Shen, Min

2017-08-01

Carbon-based black gel inks are common samples in forensic practice of questioned document examination in China, but there are few analytical methods for this type of ink. In this study, a liquid chromatography-.high resolution mass spectrometry (LC-HRMS) method was established for the analysis of PEG oligomers in carbon-based black gel ink entries. The coupled instruments achieve both the identification and quantification of PEG oligomers in ink entries with reproducible results. Twenty carbon-based black gel inks, whose Raman spectra appeared identical, were analyzed using the LC-HRMS method. As a result, the twenty gel inks were classified into four groups according to the distribution of PEG oligomers. Artificially aging of PEG 400 and a gel ink showed that as PEG degraded, the relative amounts of low molecular weight PEG oligomers increased, while those of high molecular weight decreased. The degradation of PEG oligomers in a naturally aged gel ink was consistent with those in the artificially aged samples, but occurred more slowly. This study not only provided a new method for discriminating carbon-based black gel ink entries, but also offered a new approach for studying the relative ink dating of carbon-based black gel ink entries. Copyright © 2017 Elsevier B.V. All rights reserved.

Investigation of Preparation and Mechanisms of a Dispersed Particle Gel Formed from a Polymer Gel at Room Temperature

PubMed Central

Zhao, Guang; Dai, Caili; Zhao, Mingwei; You, Qing; Chen, Ang

2013-01-01

A dispersed particle gel (DPG) was successfully prepared from a polymer gel at room temperature. The polymer gel system, morphology, viscosity changes, size distribution, and zeta potential of DPG particles were investigated. The results showed that zirconium gel systems with different strengths can be cross-linked within 2.5 h at low temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) results showed that the particles were polygonal particles with nano-size distribution. According to the viscosity changes, the whole preparation process can be divided into two major stages: the bulk gel cross-linking reaction period and the DPG particle preparation period. A polymer gel with a 3-dimensional network was formed in the bulk gel cross-linking reaction period whereas shearing force and frictional force were the main driving forces for the preparation of DPG particles, and thus affected the morphology of DPG particles. High shearing force and frictional force reduced the particle size distribution, and then decreased the zeta potential (absolute value). The whole preparation process could be completed within 3 h at room temperature. It could be an efficient and energy-saving technology for preparation of DPG particles. PMID:24324817

Adapalene gel 0.1% is better tolerated than tretinoin gel 0.025% among healthy volunteers of various ethnic origins.

PubMed

Goh, Chee Leok; Tang, Mark B Y; Briantais, Philippe; Kaoukhov, Alexandre; Soto, Pascale

2009-01-01

The efficacious acne treatment adapalene gel 0.1% is significantly less irritating than tretinoin of various concentrations and formulations, according to several clinical studies conducted predominantly in Caucasian patients. To confirm the lower irritation potential of adapalene gel 0.1% compared to tretinoin gel 0.025% among volunteers of various ethnic origins and to explore the difference in the irritant susceptibility among ethnic groups. The study was a single-centre, randomized, investigator-masked and intra-individual comparison. Healthy volunteers applied adapalene and tretinoin daily to the face for 21 days and to the forearms for 4 days, and were then evaluated for the level of irritation. The irritation potential of adapalene gel 0.1% was significantly lower than that of tretinoin gel 0.025% in all tolerability assessments, irrespective of the volunteers' ethnic origins. The between-treatment differences were similar among various ethnic groups. Statistically significant but small inter-ethnicity differences were observed in the evaluation of facial signs, with Caucasians being less susceptible than Chinese, Asian Indians and Malays. Adapalene gel 0.1% was significantly better tolerated than tretinoin gel 0.025% among various ethnic groups. The patients' ethnic origins had no impact on the difference between adapalene and tretinoin treatments in terms of tolerability.

Measurement of the ferric diffusion coefficient in agarose and gelatine gels by utilization of the evolution of a radiation induced edge as reflected in relaxation rate images.

PubMed

Pedersen, T V; Olsen, D R; Skretting, A

1997-08-01

A method has been developed to determine the diffusion coefficients of ferric ions in ferrous sulphate doped gels. A radiation induced edge was created in the gel, and two spin-echo sequences were used to acquire a pair of images of the gel at different points of time. For each of these image pairs, a longitudinal relaxation rate image was derived. From profiles through these images, the standard deviations of the Gaussian functions that characterize diffusion were determined. These data provided the basis for the determination of the ferric diffusion coefficients by two different methods. Simulations indicate that the use of single spin-echo images in this procedure may in some cases lead to a significant underestimation of the diffusion coefficient. The technique was applied to different agarose and gelatine gels that were prepared, irradiated and imaged simultaneously. The results indicate that the diffusion coefficient is lower in a gelatine gel than in an agarose gel. Addition of xylenol orange to a gelatine gel lowers the diffusion coefficient from 1.45 to 0.81 mm2 h-1, at the cost of significantly lower Rl sensitivity. The addition of benzoic acid to the latter gel did not increase the Rl sensitivity.

Evaluation of hyaluronan gel (Gengigel(®) ) as a topical applicant in the treatment of gingivitis.

PubMed

Sapna, Nadiger; Vandana, Kharidi Laxman

2011-08-01

  To clinically and histopathologically evaluate the anti-inflammatory effect of 0.2% hyaluronan gel alone and with mechanical therapy on gingivitis. The argyrophilic nucleolar organizer region staining technique was attempted to routinely determine its diagnostic and prognostic dependability for periodontal lesions.   In each of the 28 gingivitis patients, the four quadrants were subjected to different treatments: scaling, scaling + topical hyaluronan gel, only topical hyaluronan gel, and topical + intrasulcular hyaluronan gel. Clinical parameters were recorded at baseline, and on days 7, 14, and 21. Biopsies were taken from each quadrant, inflammatory infiltrates were graded, and the argyrophilic nucleolar organizer region count was measured before and after treatment.   A significant reduction was seen in clinical parameters, inflammatory infiltrates, and the argyrophilic nucleolar organizer region count within the groups. The effect of topical + intrasulcular gel was equivalent to scaling (P > 0.05). Topical + intrasulcular hyaluronan gel application demonstrated a better reduction than topical hyaluronan gel alone.   Hyaluronan gel is an effective topical agent for treating gingivitis, along with scaling and intrasulcular application. The argyrophilic nucleolar organizer region count can be used as a histopathological indicator in cases of non-responsive gingivitis to assess the severity of gingival inflammation. © 2011 Blackwell Publishing Asia Pty Ltd.

Continuous monitoring of enzymatic activity within native electrophoresis gels: Application to mitochondrial oxidative phosphorylation complexes

PubMed Central

Covian, Raul; Chess, David; Balaban, Robert S.

2012-01-01

Native gel electrophoresis allows the separation of very small amounts of protein complexes while retaining aspects of their activity. In-gel enzymatic assays are usually performed by using reaction-dependent deposition of chromophores or light scattering precipitates quantified at fixed time points after gel removal and fixation, limiting the ability to analyze enzyme reaction kinetics. Herein, we describe a custom reaction chamber with reaction media recirculation and filtering and an imaging system that permits the continuous monitoring of in-gel enzymatic activity even in the presence of turbidity. Images were continuously collected using time-lapse high resolution digital imaging, and processing routines were developed to obtain kinetic traces of the in-gel activities and analyze reaction time courses. This system also permitted the evaluation of enzymatic activity topology within the protein bands of the gel. This approach was used to analyze the reaction kinetics of two mitochondrial complexes in native gels. Complex IV kinetics showed a short initial linear phase where catalytic rates could be calculated, whereas Complex V activity revealed a significant lag phase followed by two linear phases. The utility of monitoring the entire kinetic behavior of these reactions in native gels, as well as the general application of this approach, is discussed. PMID:22975200

Evaluation of desensitizing agents on dentin permeability and dentinal tubule occlusion: an in vitro study.

PubMed

Oberg, Carolina; Pochapski, Marcia Thais; Farago, Paulo Vitor; Granado, Carlos Jose Fernandes; Pilatti, Gibson Luiz; Santos, Fabio Andre

2009-01-01

One hundred twelve specimens from bovine incisors were divided into eight groups: Group 1 (treated with 10% strontium chloride gel), Group 2 (treated with 2% sodium fluoride gel), Group 3 (treated with 2% stannous fluoride gel), Group 4 (treated with 5% potassium nitrate gel), Group 5 (treated with 10% potassium nitrate gel), Group 6 (treated with 3% potassium oxalate gel), Group 7 (treated with hydroxyethylcellulose gel), and Group 8 (which received no treatment). Dentinal tubules were exposed after 0.5 mm of deep abrasion using a carbide bur and EDTA gel application. After each treatment, dentin permeability, tubule occlusion, and chemical elements on dentin were analyzed. There was a significant difference among groups in dentin permeability (p < 0.05 ANOVA). Groups 4, 5, and 6 showed the lowest values, while Groups 1, 7, and 8 exhibited the highest. Groups 1, 2, 3, 7, and 8 showed open dentinal tubules, Groups 4 and 5 had partial tubule occlusion, and most of the tubules in Group 6 were obliterated. Energy-dispersive x-rays revealed similar chemical characteristics among the experimental agents used, with traces of strontium, fluoride, sodium, and potassium. Within the limits of the study, 3% potassium oxalate gel showed the best results in terms of dentin permeability and dentinal tubule occlusion.

Network Confinement and Heterogeneity Slows Nanoparticle Diffusion in Polymer Gels

NASA Astrophysics Data System (ADS)

Parrish, Emmabeth; Caporizzo, Matthew; Composto, Russell

Nanoparticle (NP) diffusion was measured in polyacrylamide gels (PAG) with a mesh size comparable to NP size, 20nm. The confinement ratio (CR), NP diameter/mesh, increased from 0.4 to 3.8 by increasing crosslinker density and 0.4 to 2 by adding acetone, which collapsed PAG. In all gels, NPs either became localized (<200nm) or diffused microns, as measured by single particle tracking. Mean squared displacements (MSD) of mobile NPs decreased as CR increased. In collapsed gels, the localized NP population increased and MSD of mobile NPs decreased compared to crosslinked PAG. For all CRs, van Hove distributions exhibited non-Gaussian displacements consistent with intermittent localization of NPs. The non-Gaussian parameter increased from a maximum of 1.5 for crosslinked PAG to 5 for collapsed PAG, consistent with greater network heterogeneity. Diffusion coefficients, D, decreased exponentially as CR increased for crosslinked gels, but in collapsed gels D decreased more strongly, suggesting CR alone was insufficient to capture diffusion. Collapsing the gel resulted in an increasingly tortuous pathway for NPs, slowing diffusion at a given CR. Understanding how gel structure affects NP mobility will allow the design of gels with improved ability to separate and release molecules. ACS/PRF 54028-ND7, NSF/MWN DMR-1210379.

Flow of colloidal suspensions and gels

NASA Astrophysics Data System (ADS)

Zia, Roseanna

Our recent studies of yield of colloidal gels under shear show that yield in such gels occurs in distinct stages. Under fixed stress, yield follows a finite delay period of slow solid-like creep. Post yield, the gel fluidizes and may undergo long-time viscous flow or, in some cases, may re-solidify. Under imposed strain rate, the transition from equilibrium to long-time flow is characterized by one or more stress overshoots, signifying a yield process here as well. These rheological changes are accompanied by evolution in morphology and dynamics of the gel network. Similar regimes have been observed in gels subjected to gravitational forcing; the gel initially supports its own weight, or perhaps undergoes slow, weak compaction. This may be followed by a sudden transition to rapid compaction or sedimentation. Various models have been put forth to explain these behaviors based on structural evolution, but this detail is difficult to observe in experiment. Here we examine the detailed microstructural evolution and rheology of reversible colloidal gels as they deform under gravity, identifying the critical buoyant force at which yield occurs, the role played by ongoing gel coarsening, and similarities and differences compared to yield under shear. We gratefully acknowledge the support of the NSF XSEDE Computational Resource, the NSF Early CAREER Program, and the Office of Naval Research Young Investigator Program.

Physical therapy clinic therapeutic ultrasound equipment as a source for bacterial contamination.

PubMed

Spratt, Henry G; Levine, David; Tillman, Larry

2014-10-01

A procedure commonly used in physical therapy (PT) clinics is therapeutic ultrasound (US). This equipment and associated gel comes in contact with patient skin, potentially serving as a reservoir for bacteria. In this study, we sampled US heads, gel bottle tips and gel from nine outpatient PT clinics in Southeastern Tennessee. Samples were collected using sterile swabs. At the microbiology laboratory, these swabs were used to inoculate mannitol salt agar and CHROM-MRSA agar (for Staphylococcal species) and tryptic soy broth to determine non-specific bacterial contamination. US heads, gel bottle tips and gel had variable levels of contamination. Tips of gel bottles had the highest contamination, with 52.7% positive for non-specific bacterial contamination and 3.6% positive for methicillin-resistant Staphylococcus aureus (MRSA). Contamination of gel by non-specific bacteria was found in 14.5% of bottles sampled. US heads (35.5% of those sampled) had non-specific bacterial contamination, with no MRSA detected. Disinfecting US heads after initial swabbing resulted in removal of 90.9% of non-specific contamination. Gel storage at temperatures below 40 °C was found to encourage the growth of mesophilic bacteria. This study demonstrates the need for better cleaning and storage protocols for US heads and gel bottles in PT clinics.

Studies of (3-mercaptopropyl)trimethoxylsilane and bis(trimethoxysilyl)ethane sol-gel coating on copper and aluminum.

PubMed

Li, Ying-Sing; Lu, Weijie; Wang, Yu; Tran, Tuan

2009-09-01

Bis(trimethoxysilyl)ethane (BTMSE) and (3-mercaptopropyl)trimethoxysilane (MPTMS) have been used as precursors to prepare sol-gels and hybrid sol-gel under acidic condition. From the X-ray photoelectron spectroscopy data on MPTMS sol-gel coated aluminum and copper, it has been shown that the silane film is covalently bonded to Al surface through the interfacial condensation. There is no evidence of bonding interaction between the thiol group and the Cu. The recorded reflection adsorption IR (RAIR) spectrum has provided evidence that the coating BTMSE film covalently interacts with Al. Vibrational assignments have been suggested for pure BTMSE, BTMSE sol-gel, BTMSE xerogel, and BTMSE coated Al panel based on the group frequencies and the variation of frequencies with the sample treatment conditions. The progression of condensation reaction has been observed from the IR spectra of the BTMSE sol-gel and the sol-gel coated film after the treatments at different temperatures with different lengths of time. The corrosion protection of the sol-gel coated Al and Cu has been characterized in NaCl solutions by cyclic voltammetric, potentiodynamic polarization and impedance spectroscopy methods. All these electrochemical measurements indicate that the sol-gel coated metals have better corrosion protection than the corresponding uncoated metals.

Ion Electrodiffusion Governs Silk Electrogelation.

PubMed

Kojic, Nikola; Panzer, Matthew J; Leisk, Gary G; Raja, Waseem K; Kojic, Milos; Kaplan, David L

2012-07-14

Silk electrogelation involves the transition of an aqueous silk fibroin solution to a gel state (E-gel) in the presence of an electric current. The process is based on local pH changes as a result of water electrolysis - generating H(+) and OH(-) ions at the (+) and (-) electrodes, respectively. Silk fibroin has a pI=4.2 and when local pH

Finger-Shaped GelForce: Sensor for Measuring Surface Traction Fields for Robotic Hand.

PubMed

Sato, K; Kamiyama, K; Kawakami, N; Tachi, S

2010-01-01

It is believed that the use of haptic sensors to measure the magnitude, direction, and distribution of a force will enable a robotic hand to perform dexterous operations. Therefore, we develop a new type of finger-shaped haptic sensor using GelForce technology. GelForce is a vision-based sensor that can be used to measure the distribution of force vectors, or surface traction fields. The simple structure of the GelForce enables us to develop a compact finger-shaped GelForce for the robotic hand. GelForce that is developed on the basis of an elastic theory can be used to calculate surface traction fields using a conversion equation. However, this conversion equation cannot be analytically solved when the elastic body of the sensor has a complicated shape such as the shape of a finger. Therefore, we propose an observational method and construct a prototype of the finger-shaped GelForce. By using this prototype, we evaluate the basic performance of the finger-shaped GelForce. Then, we conduct a field test by performing grasping operations using a robotic hand. The results of this test show that using the observational method, the finger-shaped GelForce can be successfully used in a robotic hand.

Analysis of spatial diffusion of ferric ions in PVA-GTA gel dosimeters through magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Marrale, Maurizio; Collura, Giorgio; Gallo, Salvatore; Nici, Stefania; Tranchina, Luigi; Abbate, Boris Federico; Marineo, Sandra; Caracappa, Santo; d'Errico, Francesco

2017-04-01

This work focused on the analysis of the temporal diffusion of ferric ions through PVA-GTA gel dosimeters. PVA-GTA gel samples, partly exposed with 6 MV X-rays in order to create an initial steep gradient, were mapped using magnetic resonance imaging on a 7T MRI scanner for small animals. Multiple images of the gels were acquired over several hours after irradiation and were analyzed to quantitatively extract the signal profile. The spatial resolution achieved is 200 μm and this makes this technique particularly suitable for the analysis of steep gradients of ferric ion concentration. The results obtained with PVA-GTA gels were compared with those achieved with agarose gels, which is a standard dosimetric gel formulation. The analysis showed that the diffusion process is much slower (more than five times) for PVA-GTA gels than for agarose ones. Furthermore, it is noteworthy that the diffusion coefficient value obtained through MRI analysis is significantly consistent with that obtained in separate study Marini et al. (Submitted for publication) using a totally independent method such as spectrophotometry. This is a valuable result highlighting that the good dosimetric features of this gel matrix not only can be reproduced but also can be measured through independent experimental techniques based on different physical principles.

Effects of rare sugar d-allulose on heat-induced gelation of surimi prepared from marine fish.

PubMed

Ogawa, Masahiro; Inoue, Masaki; Hayakawa, Shigeru; O'Charoen, Siwaporn; Ogawa, Makiko

2017-11-01

d-Allulose (Alu), the C3-epimer of d-fructose, is a non-caloric sweetener (0.39 kcal g -1 ) with a suppressive effect on postprandial blood glucose elevation. The aim of this study was to investigate the effects of Alu used as a sweetener and gel improver instead of sucrose on heat-induced gelation of surimi. The puncture test of a heat-induced surimi gel showed that with 50 g kg -1 Alu the gel had 15% and 6% higher gel strength than the corresponding gel with sucrose (Suc) and with sorbitol (Sor), respectively. In addition, Alu-gel had 26% and 25% higher water-holding capacity (WHC) than Suc- and Sor-gel. Heating of myofibrillar protein with Alu, unlike Suc and Sor, facilitated the formation of both disulfide and non-disulfide crosslinks that might be associated with the mechanical properties and WHC of Alu-gel. Alu improves the mechanical properties and WHC of the heat-induced surimi gel. Furthermore, Alu is low in calories compared with Suc (4.0 kcal g -1 ) and Sor (3.0 kcal g -1 ). Thus Alu will be an alternative of Suc or Sor for developing surimi-based products with health benefits. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

PEG spacer gel and adaptive planning vs single plan in external prostate radiotherapy—clinical dosimetry evaluation

PubMed Central

2015-01-01

Objective: Spacer gel is used to reduce the rectal dose in prostate radiotherapy. It is injected to increase the distance between the prostate and rectum. During the course of external radiotherapy treatment, physiological changes in rectal volume exist. When using polyethylene glycol material, such as DuraSeal® (Covidien, Mansfield, MA), gel resorption also occurs. Together, these factors alter the original dose plan distribution. Methods: External dose planning and calculations were simulated using images acquired from 10 patients who were treated with brachytherapy and gel. The CT series was taken relative to gel injection: pre 1 day, post 1 day, post 1 month and post 2 months. Adaptive planning was compared with a single plan. Results: Adaptive planning shows better results compared with the single plan used in the total treatment course; however, the effect is minor. Conclusion: Gel usage is clearly favourable to rectal DVH. Using adaptive planning with gel improves rectal DVH but is not necessary according to this study. Advances in knowledge: Spacer gel is used in prostate radiotherapy to increase distance between the prostate and the rectum, thus reducing the rectal doses. During the treatment course, gel resorption exists which affects the rectal doses. The usefulness of adaptive planning to compensate this resorption effect has not been studied before. PMID:26370300

Continuous monitoring of enzymatic activity within native electrophoresis gels: application to mitochondrial oxidative phosphorylation complexes.

PubMed

Covian, Raul; Chess, David; Balaban, Robert S

2012-12-01

Native gel electrophoresis allows the separation of very small amounts of protein complexes while retaining aspects of their activity. In-gel enzymatic assays are usually performed by using reaction-dependent deposition of chromophores or light-scattering precipitates quantified at fixed time points after gel removal and fixation, limiting the ability to analyze the enzyme reaction kinetics. Herein, we describe a custom reaction chamber with reaction medium recirculation and filtering and an imaging system that permits the continuous monitoring of in-gel enzymatic activity even in the presence of turbidity. Images were continuously collected using time-lapse high-resolution digital imaging, and processing routines were developed to obtain kinetic traces of the in-gel activities and analyze reaction time courses. This system also permitted the evaluation of enzymatic activity topology within the protein bands of the gel. This approach was used to analyze the reaction kinetics of two mitochondrial complexes in native gels. Complex IV kinetics showed a short initial linear phase in which catalytic rates could be calculated, whereas Complex V activity revealed a significant lag phase followed by two linear phases. The utility of monitoring the entire kinetic behavior of these reactions in native gels, as well as the general application of this approach, is discussed. Published by Elsevier Inc.

The Effect of Preventive Agents (Mouthwashes/Gels) on the Color Stability of Dental Resin-Based Composite Materials

PubMed Central

Al-Samadani, Khalid H.

2017-01-01

The color of dental restorative material should be maintained throughout its functional lifetime in an oral environment. However, the frequent use of mouthwash may affect the color stability of these composite restorations. The aim of this study is to assess the effects of using various mouthwashes on the color stability of various dental restorative composite materials. For this purpose, four mouthwashes/gels (Flocare gel (0.4% stannous fluoride), Pascal gel (topical APF fluoride), Pro-Relief mouthwash (sodium fluoride), and Plax Soin mouthwash (sodium fluoride)), and distilled water as a control, were selected. These were divided into five groups: Group 1: Flocare gel; Group 2: Pascal gel; Group 3: Pro-Relief mouthwash; Group 4: Plax Soin mouthwash; and Group 5: distilled water (control). Prepared restorative materials samples were immersed in the groups of mouthwashes/gels and the distilled water (control) for 24, 48, and 72 h. The discoloration that all materials exhibited with all immersion groups was significantly different at each of the three time periods for all groups (p < 0.05). Results from immersion in Flocare gel, Pascal gel, Pro-Relief mouthwash, and Plax Soin mouthwash were statistically significant (p < 0.05). The color change chroma was not significant for Pro-Relief and Plax Soin mouthwash (p > 0.05). Mouthwashes/gels affect color shifting for all composite resin materials, and changes are exaggerated over time. However, discoloration effects are not perceptible to the human eye. PMID:29563424

Dosimetry study of diagnostic X-ray using doped iodide normoxic polymer gels

NASA Astrophysics Data System (ADS)

Huang, Y. R.; Chang, Y. J.; Hsieh, L. L.; Liu, M. H.; Liu, J. S.; Chu, C. H.; Hsieh, B. T.

2014-11-01

In radiotherapy, polymer gel dosimeters are used for three-dimensional (3D) dose distribution. However, the doses are within the Gy range. In this study, we attempted to develop a low-dose 3D dosimeter within the mGy range for diagnostic radiology. The effect of the iodinated compound was used as a dose enhancement sensitizer to enhance the dose sensitivity of normoxic polymer gel dosimeters. This study aims to use N-isopropylacrylamide(NIPAM)-based and methacrylic acid (MAGAT)-based gels to evaluate the potential dose enhancement sensitizer, as well as to compare two gels that may be suitable for measuring diagnostic radiation doses. The suitable formulation of NIPAM gel [5% (w/w) gelatin, 5% (w/w) NIPAM, 3% (w/w) N,N‧-methylenebisacrylamide (BIS), 5 mM tetrakis (hydroxymethyl) phosphonium chloride (THPC), and 87% (w/w) deionized distilled water] and MAGAT gel (4% MAA, 9% gelatin, 87% deionized water, and 10 mM THPC) were used and loaded with clinical iodinated contrast medium agent (Iobitridol, Xenetix® 350). Irradiation was conducted using X-ray computed tomography. The irradiation doses ranged from 0 mGy to 80 mGy. Optical computed tomography was the employed gel measurement system. The results indicate that the iodinated contrast agent yields a quantifiable dose enhancement ratio. The dose enhancement ratios of NIPAM and MAGAT gels are 3.35±0.6 and 1.36±0.3, respectively. The developed NIPAM gel in this study could be suitable for measuring diagnostic radiation doses.

Safety of coitally administered tenofovir 1% gel, a vaginal microbicide, in chronic hepatitis B virus carriers: Results from the CAPRISA 004 trial

PubMed Central

BAXTER, Cheryl; YENDE-ZUMA, Nonhlanhla; TSHABALALA, Phindile; KARIM, Quarraisha ABDOOL; KARIM, Salim S ABDOOL

2013-01-01

Tenofovir disoproxil fumarate, a licensed oral treatment for both HIV and Hepatitis B virus (HBV) infections, has been associated with severe rebound hepatic flares when treatment is interrupted. A gel formulation of tenofovir is currently being assessed as a microbicide against HIV. If licensed, it is possible that tenofovir gel could be used either intentionally or unintentionally by HBV carriers. The purpose of this study was to establish the safety of tenofovir gel use in this patient group participating in the CAPRISA 004 tenofovir gel trial. HBV infection status was assessed at enrolment and study exit. Liver function testing was performed at enrolment, study months 3, 12, 24, study exit, and two months after exiting the study. At enrolment, 34 women were identified as being HBV carriers and 22 women acquired HBV infections during follow-up; 14 and 8 in the tenofovir and placebo gel arms respectively (p=0.21). Intermittent tenofovir gel use did not cause an increase in hepatic flares or impact on viral load suppression in women with HBV infection. There were 2 hepatic flares in each gel arm during follow-up and none two months after cessation of gel at study exit. The mean HBV DNA levels were similar at enrolment and exit in both study arms. Tenofovir gel, when used intermittently, was safe to use in women with HBV infection. PMID:23832086

In Vivo skin hydration and anti-erythema effects of Aloe vera, Aloe ferox and Aloe marlothii gel materials after single and multiple applications.

PubMed

Fox, Lizelle T; du Plessis, Jeanetta; Gerber, Minja; van Zyl, Sterna; Boneschans, Banie; Hamman, Josias H

2014-04-01

To investigate the skin hydrating and anti-erythema activity of gel materials from Aloe marlothii A. Berger and A. ferox Mill. in comparison to that of Aloe barbadensis Miller (Aloe vera) in healthy human volunteers. Aqueous solutions of the polisaccharidic fractions of the selected aloe leaf gel materials were applied to the volar forearm skin of female subjects. The hydration effect of the aloe gel materials were measured with a Corneometer(®) CM 825, Visioscan(®) VC 98 and Cutometer(®) dual MPA 580 after single and multiple applications. The Mexameter(®) MX 18 was used to determine the anti-erythema effects of the aloe material solutions on irritated skin areas. The A. vera and A. marlothii gel materials hydrated the skin after a single application, whereas the A. ferox gel material showed dehydration effects compared to the placebo. After multiple applications all the aloe materials exhibited dehydration effects on the skin. Mexameter(®) readings showed that A. vera and A. ferox have anti-erythema activity similar to that of the positive control group (i.e. hydrocortisone gel) after 6 days of treatment. The polysaccharide component of the gel materials from selected aloe species has a dehydrating effect on the skin after multiple applications. Both A. vera and A. ferox gel materials showed potential to reduce erythema on the skin similar to that of hydrocortisone gel.

Automatic and quantitative measurement of collagen gel contraction using model-guided segmentation

NASA Astrophysics Data System (ADS)

Chen, Hsin-Chen; Yang, Tai-Hua; Thoreson, Andrew R.; Zhao, Chunfeng; Amadio, Peter C.; Sun, Yung-Nien; Su, Fong-Chin; An, Kai-Nan

2013-08-01

Quantitative measurement of collagen gel contraction plays a critical role in the field of tissue engineering because it provides spatial-temporal assessment (e.g., changes of gel area and diameter during the contraction process) reflecting the cell behavior and tissue material properties. So far the assessment of collagen gels relies on manual segmentation, which is time-consuming and suffers from serious intra- and inter-observer variability. In this study, we propose an automatic method combining various image processing techniques to resolve these problems. The proposed method first detects the maximal feasible contraction range of circular references (e.g., culture dish) and avoids the interference of irrelevant objects in the given image. Then, a three-step color conversion strategy is applied to normalize and enhance the contrast between the gel and background. We subsequently introduce a deformable circular model which utilizes regional intensity contrast and circular shape constraint to locate the gel boundary. An adaptive weighting scheme was employed to coordinate the model behavior, so that the proposed system can overcome variations of gel boundary appearances at different contraction stages. Two measurements of collagen gels (i.e., area and diameter) can readily be obtained based on the segmentation results. Experimental results, including 120 gel images for accuracy validation, showed high agreement between the proposed method and manual segmentation with an average dice similarity coefficient larger than 0.95. The results also demonstrated obvious improvement in gel contours obtained by the proposed method over two popular, generic segmentation methods.

Improved techniques for fluid diversion in oil recovery. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seright, R.

This three-year project had two technical objectives. The first objective was to compare the effectiveness of gels in fluid diversion (water shutoff) with those of other types of processes. Several different types of fluid-diversion processes were compared, including those using gels, foams, emulsions, particulates, and microorganisms. The ultimate goals of these comparisons were to (1) establish which of these processes are most effective in a given application and (2) determine whether aspects of one process can be combined with those of other processes to improve performance. Analyses and experiments were performed to verify which materials are the most effective inmore » entering and blocking high-permeability zones. The second objective of the project was to identify the mechanisms by which materials (particularly gels) selectively reduce permeability to water more than to oil. A capacity to reduce water permeability much more than oil or gas permeability is critical to the success of gel treatments in production wells if zones cannot be isolated during gel placement. Topics covered in this report include (1) determination of gel properties in fractures, (2) investigation of schemes to optimize gel placement in fractured systems, (3) an investigation of why some polymers and gels can reduce water permeability more than oil permeability, (4) consideration of whether microorganisms and particulates can exhibit placement properties that are superior to those of gels, and (5) examination of when foams may show placement properties that are superior to those of gels.« less

Gel nanostructure in alkali-activated binders based on slag and fly ash, and effects of accelerated carbonation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernal, Susan A., E-mail: s.bernal@sheffield.ac.uk; Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD; Provis, John L., E-mail: j.provis@sheffield.ac.uk

2013-11-15

Binders formed through alkali-activation of slags and fly ashes, including ‘fly ash geopolymers’, provide appealing properties as binders for low-emissions concrete production. However, the changes in pH and pore solution chemistry induced during accelerated carbonation testing provide unrealistically low predictions of in-service carbonation resistance. The aluminosilicate gel remaining in an alkali-activated slag system after accelerated carbonation is highly polymerised, consistent with a decalcification mechanism, while fly ash-based binders mainly carbonate through precipitation of alkali salts (bicarbonates at elevated CO{sub 2} concentrations, or carbonates under natural exposure) from the pore solution, with little change in the binder gel identifiable by nuclearmore » magnetic resonance spectroscopy. In activated fly ash/slag blends, two distinct gels (C–A–S–H and N–A–S–H) are formed; under accelerated carbonation, the N–A–S–H gel behaves comparably to fly ash-based systems, while the C–A–S–H gel is decalcified similarly to alkali-activated slag. This provides new scope for durability optimisation, and for developing appropriate testing methodologies. -- Highlights: •C-A-S-H gel in alkali-activated slag decalcifies during accelerated carbonation. •Alkali-activated fly ash gel changes much less under CO{sub 2} exposure. •Blended slag-fly ash binder contains two coexisting gel types. •These two gels respond differently to carbonation. •Understanding of carbonation mechanisms is essential in developing test methods.« less

Platelet-rich plasma combined with agarose as a bioactive scaffold to enhance cartilage repair: an in vitro study.

PubMed

Yin, Zhaowei; Yang, Xiaofei; Jiang, Yiqiu; Xing, Linzi; Xu, Yang; Lu, Yiming; Ding, Peng; Ma, Junxin; Xu, Yan; Gui, Jianchao

2014-03-01

The purpose of this study was to determine whether the platelet-rich plasma-agarose gel scaffold could be a bioactive scaffold capable of growth factors release for cartilage repair. Porcine chondrocytes were seeded in agarose gel and platelet-rich plasma-agarose gel. During the 28-days culture, microstructure of hydrogels and morphologies of chondrocytes seeded in the hydrogels were observed using scanning electron microscope; viability of chondrocytes in gels was examined by live/dead assay; qualitative and quantitative analysis of glycosaminoglycan, collagen and DNA were assessed by histological, immunohistochemical staining and biochemical assay; gene expression was measured by real-time polymerase chain reaction. In vitro cartilage ring models were used to evaluate the integration of the scaffolds, and the integration strength was analyzed by mechanical push-out tests. Scanning electron microscope revealed both scaffolds had highly uniform porous structure. Live/dead scaffolds showed 100% cells alive in both groups. After 28-days culture, glycosaminoglycan, collagen, DNA content and chondrocyte-related genes expression in platelet-rich plasma-agarose gel were significantly higher than pure agarose gel. Integration strength in platelet-rich plasma-agarose gel was also higher compared to pure agarose gel. Platelet-rich plasma showed a positive effect on chondrocytes proliferation, differentiation and integration between native cartilage and engineered tissue when combined with agarose gel. Our findings suggest that platelet-rich plasma-agarose gel scaffold is a promising bioactive scaffold for future cartilage tissue engineering and future clinical works.

Evolution of heterogeneity accompanying sol-gel transitions in a supramolecular hydrogel.

PubMed

Matsumoto, Yuji; Shundo, Atsuomi; Ohno, Masashi; Tsuruzoe, Nobutomo; Goto, Masahiro; Tanaka, Keiji

2017-10-18

When a peptide amphiphile is dispersed in water, it self-assembles into a fibrous network, leading to a supramolecular hydrogel. When the gel is physically disrupted by shaking, it transforms into a sol state. After aging at room temperature for a while, it spontaneously returns to the gel state, called sol-gel transition. However, repeating the sol-gel transition often causes a change in the rheological properties of the gel. To gain a better understanding of the sol-gel transition and its reversibility, we herein examined the thermal motion of probe particles at different locations in a supramolecular hydrogel. The sol obtained by shaking the gel was heterogeneous in terms of the rheological properties and the extent decreased with increasing aging time. This time course of heterogeneity, or homogeneity, which corresponded to the sol-to-gel transition, was observed for the 1st cycle. However, this was not the case for the 2nd and 3rd cycles; the heterogeneity was preserved even after aging. Fourier-transform infrared spectroscopy, small-angle X-ray scattering, and atomic force and confocal laser scanning microscopies revealed that, although the molecular aggregation states of amphiphiles both in the gel and sol remained unchanged with the cycles, the fibril density diversified to high and low density regions even after aging. The tracking of particles with different sizes indicated that the partial mesh size in the high density region and the characteristic length scale of the density fluctuation were smaller than 50 nm and 6 μm, respectively.

A supramolecular gel electrolyte formed from amide based co-gelator for quasi-solid-state dye-sensitized solar cell with boosted electron kinetic processes

NASA Astrophysics Data System (ADS)

Huo, Zhipeng; Wang, Lu; Tao, Li; Ding, Yong; Yi, Jinxin; Alsaedi, Ahmed; Hayat, Tasawar; Dai, Songyuan

2017-08-01

A supramolecular gel electrolyte (Tgel > 100 °C) is formed from N,N‧-1,8-octanediylbis-dodecanamide and iodoacetamide as two-component co-gelator, and introduced into the quasi-solid-state dye-sensitized solar cells (QS-DSSCs). The different morphologies of microscopic network between two-component and single-component gel electrolytes have influence on the diffusion of redox couple in gel electrolytes and further affect the electron kinetic processes in QS-DSSCs. Compared with the single-component gel electrolyte, the two-component gel electrolyte has less compact gel network and weaker steric hindrance effect, which provides more effective charge transport channel for the diffusion of I3/I- redox couple. Meanwhile, the sbnd NH2 groups of iodoacetamide molecules interact with Li+ and I3-, which also accelerate the transport of I3-/I- and decrease in the I3- concentration in the TiO2/electrolyte interface. As a result, nearly a 12% improvement in short-circuit photocurrent density (Jsc) and much higher open circuit potential (Voc) are found in the two-component gel electrolyte based QS-DSSC. Consequently, the QS-DSSC based on the supramolecular gel electrolyte obtains a 17% enhancement in the photoelectric conversion efficiency (7.32%) in comparison with the QS-DSSC based on the single-component gel electrolyte (6.24%). Furthermore, the degradations of these QS-DSSCs are negligible after one sun light soaking with UV cutoff filter at 50 °C for 1000 h.

Measurements of Elastic Moduli of Silicone Gel Substrates with a Microfluidic Device

PubMed Central

Gutierrez, Edgar; Groisman, Alex

2011-01-01

Thin layers of gels with mechanical properties mimicking animal tissues are widely used to study the rigidity sensing of adherent animal cells and to measure forces applied by cells to their substrate with traction force microscopy. The gels are usually based on polyacrylamide and their elastic modulus is measured with an atomic force microscope (AFM). Here we present a simple microfluidic device that generates high shear stresses in a laminar flow above a gel-coated substrate and apply the device to gels with elastic moduli in a range from 0.4 to 300 kPa that are all prepared by mixing two components of a transparent commercial silicone Sylgard 184. The elastic modulus is measured by tracking beads on the gel surface under a wide-field fluorescence microscope without any other specialized equipment. The measurements have small and simple to estimate errors and their results are confirmed by conventional tensile tests. A master curve is obtained relating the mixing ratios of the two components of Sylgard 184 with the resulting elastic moduli of the gels. The rigidity of the silicone gels is less susceptible to effects from drying, swelling, and aging than polyacrylamide gels and can be easily coated with fluorescent tracer particles and with molecules promoting cellular adhesion. This work can lead to broader use of silicone gels in the cell biology laboratory and to improved repeatability and accuracy of cell traction force microscopy and rigidity sensing experiments. PMID:21980487

The β‐1,3‐glucanosyltransferases (Gels) affect the structure of the rice blast fungal cell wall during appressorium‐mediated plant infection

PubMed Central

Samalova, Marketa; Mélida, Hugo; Vilaplana, Francisco; Bulone, Vincent; Soanes, Darren M.; Talbot, Nicholas J.

2016-01-01

Abstract The fungal wall is pivotal for cell shape and function, and in interfacial protection during host infection and environmental challenge. Here, we provide the first description of the carbohydrate composition and structure of the cell wall of the rice blast fungus Magnaporthe oryzae. We focus on the family of glucan elongation proteins (Gels) and characterize five putative β‐1,3‐glucan glucanosyltransferases that each carry the Glycoside Hydrolase 72 signature. We generated targeted deletion mutants of all Gel isoforms, that is, the GH72+, which carry a putative carbohydrate‐binding module, and the GH72− Gels, without this motif. We reveal that M. oryzae GH72 + GELs are expressed in spores and during both infective and vegetative growth, but each individual Gel enzymes are dispensable for pathogenicity. Further, we demonstrated that a Δgel1Δgel3Δgel4 null mutant has a modified cell wall in which 1,3‐glucans have a higher degree of polymerization and are less branched than the wild‐type strain. The mutant showed significant differences in global patterns of gene expression, a hyper‐branching phenotype and no sporulation, and thus was unable to cause rice blast lesions (except via wounded tissues). We conclude that Gel proteins play significant roles in structural modification of the fungal cell wall during appressorium‐mediated plant infection. PMID:27568483

Multi-gel casting apparatus for vertical polyacrylamide gels with in-built solution flow system and liquid level detectors.

PubMed

Maurye, Praveen; Basu, Arpita; Bandyopadhyay, Tapas Kumar; Biswas, Jayanta Kumar; Mohanty, Bimal Prasana

2017-08-01

PAGE is the most widely used technique for the separation and biochemical analysis of biomolecules. The ever growing field of proteomics and genomics necessitates the analysis of many proteins and nucleic acid samples to understand further about the structure and function of cells. Simultaneous analysis of multiple protein samples often requires casting of many PAGE gels. Several variants of multi-gel casting/electrophoresis apparatuses are frequently used in research laboratories. Requirement of supplementary gels to match the growing demand for analyzing additional protein samples sometimes become a cause of concern. Available apparatuses are not amenable to and therefore, not recommended for any modification to accommodate additional gel casting units other than what is prescribed by the manufacturer. A novel apparatus is described here for casting multiple PAGE gels comprising four detachable components that provide enhanced practicability and performance of the apparatus. This newly modified apparatus promises to be a reliable source for making multiple gels in less time without hassle. Synchronized functioning of unique components broaden the possibilities of developing inexpensive, safe, and time-saving multi-gel casting apparatus. This apparatus can be easily fabricated and modified to accommodate desired number of gel casting units. The estimated cost (∼$300) for fabrication of the main apparatus is very competitive and effortless assembly procedure can be completed within ∼30 min. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sol-Gel synthesis of MgO-SiO2 glass compositions having stable liquid-liquid immiscibility

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1987-01-01

MgO-SiO2 glasses containing up to 15 mol % MgO, which could not have been prepared by the conventional glass melting method due to the presence of stable liquid-liquid immiscibility, were synthesized by the sol-gel technique. Clear and transparent gels were obtained from the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) and magnesium nitrate hexahydrate when the water/TEOS mole ratio was four or more. The gelling time decreased with increase in magnesium content, water/TEOS ratio, and reaction temperature. Magnesium nitrate hexahydrate crystallized out of the gels containing 15 and 20 mol % MgO on slow drying. This problem was partially alleviated by drying the gels quickly at higher temperatures. Monolithic gel samples were prepared using glycerol as the drying control additive. The gels were subjected to various thermal treatments and characterized by several methods. No organic groups could be detected in the glasses after heat treatments to approx. 800 C, but trace amounts of hydroxyl groups were still present. No crystalline phase was found from X-ray diffraction in the gel samples to approx. 890 C. At higher temperatures, alpha quartz precipitated out as the crystalline phase in gels containing up to 10 mol % MgO. The overall activation energy for gel formation in 10MgO-90SiO2 (mol %) system for water/TEOS mole ratio of 7.5 was calculated to be 58.7 kJ/mol.

Sol-gel synthesis of magnesium oxide-silicon dioxide glass compositions

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1988-01-01

MgO-SiO2 glasses containing up to 15 mol pct MgO, which could not have been prepared by the conventional glass melting method due to the presence of stable liquid-liquid immiscibility, were synthesized by the sol-gel technique. Clear and transparent gels were obtained from the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) and magnesium nitrate hexahydrate when the water/TEOS mole ratio was four or more. The gelling time decreased with increase in magnesium content, water/TEOS ratio, and reaction temperature. Magnesium nitrate hexahydrate crystallized out of the gels containing 15 and 20 mol pct MgO on slow drying. This problem was partially alleviated by drying the gels quickly at higher temperatures. Monolithic gel samples were prepared using glycerol as the drying control additive. The gels were subjected to various thermal treatments and characterized by several methods. No organic groups could be detected in the glasses after heat treatments to approx. 800 C, but trace amounts of hydroxyl groups were still present. No crystalline phase was found from X-ray diffraction in the gel samples to approx. 890 C. At higher temperatures, alpha quartz precipitated out as the crystalline phase in gels containing up to 10 mol pct MgO. The overall activation energy for gel formation in 10MgO-90SiO2 (mol pct) system for water/TEOS mole ratio of 7.5 was calculated to be 58.7 kJ/mol.

Genetic and biochemical characterization of the GH72 family of cell wall transglycosylases in Neurospora crassa.

PubMed

Ao, Jie; Free, Stephen J

2017-04-01

The Neurospora crassa genome encodes five GH72 family transglycosylases, and four of these enzymes (GEL-1, GEL-2, GEL-3 and GEL-5) have been found to be present in the cell wall proteome. We carried out an extensive genetic analysis on the role of these four transglycosylases in cell wall biogenesis and demonstrated that the transglycosylases are required for the formation of a normal cell wall. As suggested by the proteomic analysis, we found that multiple transglycosylases were being expressed in N. crassa cells and that different combinations of the enzymes are required in different cell types. The combination of GEL-1, GEL-2 and GEL-5 is required for the growth of vegetative hyphae, while the GEL-1, GEL-2, GEL-3 combination is needed for the production of aerial hyphae and conidia. Our data demonstrates that the enzymes are redundant with partially overlapping enzymatic activities, which provides the fungus with a robust cell wall biosynthetic system. Characterization of the transglycosylase-deficient mutants demonstrated that the incorporation of cell wall proteins was severely compromised. Interestingly, we found that the transglycosylase-deficient mutant cell walls contained more β-1,3-glucan than the wild type cell wall. Our results demonstrate that the GH72 transglycosylases are not needed for the incorporation of β-1,3-glucan into the cell wall, but they are required for the incorporation of cell wall glycoprotein into the cell wall. Copyright © 2017 Elsevier Inc. All rights reserved.

In Vivo skin hydration and anti-erythema effects of Aloe vera, Aloe ferox and Aloe marlothii gel materials after single and multiple applications

PubMed Central

Fox, Lizelle T.; du Plessis, Jeanetta; Gerber, Minja; van Zyl, Sterna; Boneschans, Banie; Hamman, Josias H.

2014-01-01

Objective: To investigate the skin hydrating and anti-erythema activity of gel materials from Aloe marlothii A. Berger and A. ferox Mill. in comparison to that of Aloe barbadensis Miller (Aloe vera) in healthy human volunteers. Materials and Methods: Aqueous solutions of the polisaccharidic fractions of the selected aloe leaf gel materials were applied to the volar forearm skin of female subjects. The hydration effect of the aloe gel materials were measured with a Corneometer® CM 825, Visioscan® VC 98 and Cutometer® dual MPA 580 after single and multiple applications. The Mexameter® MX 18 was used to determine the anti-erythema effects of the aloe material solutions on irritated skin areas. Results: The A. vera and A. marlothii gel materials hydrated the skin after a single application, whereas the A. ferox gel material showed dehydration effects compared to the placebo. After multiple applications all the aloe materials exhibited dehydration effects on the skin. Mexameter® readings showed that A. vera and A. ferox have anti-erythema activity similar to that of the positive control group (i.e. hydrocortisone gel) after 6 days of treatment. Conclusion: The polysaccharide component of the gel materials from selected aloe species has a dehydrating effect on the skin after multiple applications. Both A. vera and A. ferox gel materials showed potential to reduce erythema on the skin similar to that of hydrocortisone gel. PMID:24991119

Anti-Cervical Cancer Role of Matrine, Oxymatrine and Sophora Flavescens Alkaloid Gels and its Mechanism.

PubMed

Zhou, Yu Jie; Guo, Ya Jie; Yang, Xiao Li; Ou, Zhou Luo

2018-01-01

Background: Cervical cancer is one of the leading severe malignancies throughout the world. Sophra flavescens alkaloid (SFA) gels, a compound Traditional Chinese Medicine, has been clinically used in China for many years. Its individual active ingredients are matrine and oxymatrine, which has been showed that they can restrain primary tumorigenesis, while the underlying molecular mechanisms of SFA gels in cervical cancer cells remain unclear. Methods: To detect the effect of SFA gels and its active ingredients, CCK-8 assay and colony assay were used on cervical cancer cells proliferation. Transwell assay was used to detect cancer cell migration. Apoptosis and cell cycle arrest were used to detect whether SFA gels effect the cervical cancer cells proliferation. Western blot was used to detect whether SFA gels regulate the cervical cancer cells via the suppression of AKT/mTOR signaling pathway. Results: SFA gels can restrain cervical cancer cell proliferation, inhibit metastasis, induce cell cycle arrest in G2/M phase, induce cellular apoptosis through stimulation of Bax and E-cadherin, and suppression of Bcl-2, cyclin A, MMP2. Further study shows that SFA gels may regulate the cervical cancer cells via the suppression of AKT/mTOR signaling pathway. Conclusions: SFA gels, like its active ingredients, can restrain cervical cancer cells proliferation, suppress cervical cancer cell migration, induce the apoptosis and cell cycle arrest in cervical cancer cells. SFA gels may be a potential anti-tumor therapeutic agent for treating cervical cancer.

Anti-Cervical Cancer Role of Matrine, Oxymatrine and Sophora Flavescens Alkaloid Gels and its Mechanism

PubMed Central

Zhou, Yu Jie; Guo, Ya Jie; Yang, Xiao Li; Ou, Zhou Luo

2018-01-01

Background: Cervical cancer is one of the leading severe malignancies throughout the world. Sophra flavescens alkaloid (SFA) gels, a compound Traditional Chinese Medicine, has been clinically used in China for many years. Its individual active ingredients are matrine and oxymatrine, which has been showed that they can restrain primary tumorigenesis, while the underlying molecular mechanisms of SFA gels in cervical cancer cells remain unclear. Methods: To detect the effect of SFA gels and its active ingredients, CCK-8 assay and colony assay were used on cervical cancer cells proliferation. Transwell assay was used to detect cancer cell migration. Apoptosis and cell cycle arrest were used to detect whether SFA gels effect the cervical cancer cells proliferation. Western blot was used to detect whether SFA gels regulate the cervical cancer cells via the suppression of AKT/mTOR signaling pathway. Results: SFA gels can restrain cervical cancer cell proliferation, inhibit metastasis, induce cell cycle arrest in G2/M phase, induce cellular apoptosis through stimulation of Bax and E-cadherin, and suppression of Bcl-2, cyclin A, MMP2. Further study shows that SFA gels may regulate the cervical cancer cells via the suppression of AKT/mTOR signaling pathway. Conclusions: SFA gels, like its active ingredients, can restrain cervical cancer cells proliferation, suppress cervical cancer cell migration, induce the apoptosis and cell cycle arrest in cervical cancer cells. SFA gels may be a potential anti-tumor therapeutic agent for treating cervical cancer. PMID:29721044

Redox-switchable copper(I) metallogel: a metal-organic material for selective and naked-eye sensing of picric acid.

PubMed

Sarkar, Sougata; Dutta, Soumen; Chakrabarti, Susmita; Bairi, Partha; Pal, Tarasankar

2014-05-14

Thiourea (TU), a commercially available laboratory chemical, has been discovered to introduce metallogelation when reacted with copper(II) chloride in aqueous medium. The chemistry involves the reduction of Cu(II) to Cu(I) with concomitant oxidation of thiourea to dithiobisformamidinium dichloride. The gel formation is triggered through metal-ligand complexation, i.e., Cu(I)-TU coordination and extensive hydrogen bonding interactions involving thiourea, the disulfide product, water, and chloride ions. Entangled network morphology of the gel selectively develops in water, maybe for its superior hydrogen-bonding ability, as accounted from Kamlet-Taft solvent parameters. Complete and systematic chemical analyses demonstrate the importance of both Cu(I) and chloride ions as the key ingredients in the metal-organic coordination gel framework. The gel is highly fluorescent. Again, exclusive presence of Cu(I) metal centers in the gel structure makes the gel redox-responsive and therefore it shows reversible gel-sol phase transition. However, the reversibility does not cause any morphological change in the gel phase. The gel practically exhibits its multiresponsive nature and therefore the influences of different probable interfering parameters (pH, selective metal ions and anions, selective complexing agents, etc.) have been studied mechanistically and the results might be promising for different applications. Finally, the gel material shows a highly selective visual response to a commonly used nitroexplosive, picric acid among a set of 19 congeners and the preferred selectivity has been mechanistically interpreted with density functional theory-based calculations.

Efficacy and safety of a novel submucosal lifting gel used for endoscopic submucosal dissection: a study in a porcine model.

PubMed

Schölvinck, D W; Alvarez Herrero, L; Goto, O; Meijer, S L; Neuhaus, H; Schumacher, B; Bergman, J J G H M; Weusten, B L A M

2015-09-01

Endoscopic submucosal dissection (ESD) is technically demanding. A viscous gel for submucosal lifting might induce mechanical submucosal dissection facilitating easier and safer ESD. In 12 female pigs (median 64 kg), ESDs of simulated lesions were performed at the posterior wall and greater curvature in the gastric body (one ESD per location) with randomly assigned injection fluids: gel or control fluid (0.9% saline with hydroxypropyl methylcellulose 3 mg/ml [7:1] and indigo carmine droplets). Additionally, 10 cc gel was injected into the submucosa at the anterior wall without ESD to assess effects of inappropriate injection. Pigs were euthanized at day 0, 3 or 28. In four additional pigs (euthanized day 3 or 28) 10 cc gel was injected into the muscularis propria (MP) after four endoscopic mucosal resections in the gastric body. Both fluid groups showed equal ESD-procedure times (28 [gel] vs. 26 min [control]) and complications. Gel-ESDs required less accessory interchanges (3.5 vs. 5.5; p = 0.01). Mechanical dissection after circumferential incision was achieved in 25% of gel-ESDs; none in control-ESDs. The severity of inflammation and fibrosis was equal in both fluid groups. Normal architecture and vital mucosa were found after inappropriate submucosal injection. MP-injections resulted in one transmural hematoma (day 3), and intramuscular encapsulation in 25% of the sites (day 28). A pig's stomach differs from the human stomach. The mechanical dissection properties of the gel may reduce the need for submucosal dissection during ESD. The gel is safe when advertently injected in the submucosa and MP. The porcine model appeared suboptimal to evaluate the true mechanical dissection properties of the gel.

Dose evaluation of an NIPAM polymer gel dosimeter using gamma index

NASA Astrophysics Data System (ADS)

Chang, Yuan-Jen; Lin, Jing-Quan; Hsieh, Bor-Tsung; Yao, Chun-Hsu; Chen, Chin-Hsing

2014-11-01

An N-isopropylacrylamide (NIPAM) polymer gel dosimeter has great potential in clinical applications. However, its three-dimensional dose distribution must be assessed. In this work, a quantitative evaluation of dose distributions was performed to evaluate the NIPAM polymer gel dosimeter using gamma analysis. A cylindrical acrylic phantom filled with NIPAM gel measuring 10 cm (diameter) by 10 cm (height) by 3 mm (thickness) was irradiated by a 4×4 cm2 square light field. The irradiated gel phantom was scanned using an optical computed tomography (optical CT) scanner (OCTOPUS™, MGS Research, Inc., Madison, CT, USA) at 1 mm resolution. The projection data were transferred to an image reconstruction program, which was written using MATLAB (The MathWorks, Natick, MA, USA). The program reconstructed the image of the optical density distribution using the algorithm of a filter back-projection. Three batches of replicated gel phantoms were independently measured. The average uncertainty of the measurements was less than 1%. The gel was found to have a high degree of spatial uniformity throughout the dosimeter and good temporal stability. A comparison of the line profiles of the treatment planning system and of the data measured by optical CT showed that the dose was overestimated in the penumbra region because of two factors. The first is light scattering due to changes in the refractive index at the edge of the irradiated field. The second is the edge enhancement caused by free radical diffusion. However, the effect of edge enhancement on the NIPAM gel dosimeter is not as significant as that on the BANG gel dosimeter. Moreover, the dose uncertainty is affected by the inaccuracy of the gel container positioning process. To reduce the uncertainty of 3D dose distribution, improvements in the gel container holder must be developed.

Inhibition of prostate cancer osteoblastic progression with VEGF121/rGel, a single agent targeting osteoblasts, osteoclasts, and tumor neovasculature.

PubMed

Mohamedali, Khalid A; Li, Zhi Gang; Starbuck, Michael W; Wan, Xinhai; Yang, Jun; Kim, Sehoon; Zhang, Wendy; Rosenblum, Michael G; Navone, Nora M

2011-04-15

A hallmark of prostate cancer (PCa) progression is the development of osteoblastic bone metastases, which respond poorly to available therapies. We previously reported that VEGF(121)/rGel targets osteoclast precursors and tumor neovasculature. Here we tested the hypothesis that targeting nontumor cells expressing these receptors can inhibit tumor progression in a clinically relevant model of osteoblastic PCa. Cells from MDA PCa 118b, a PCa xenograft obtained from a bone metastasis in a patient with castrate-resistant PCa, were injected into the femurs of mice. Osteoblastic progression was monitored following systemic administration of VEGF(121)/rGel. VEGF(121)/rGel was cytotoxic in vitro to osteoblast precursor cells. This cytotoxicity was specific as VEGF(121)/rGel internalization into osteoblasts was VEGF(121) receptor driven. Furthermore, VEGF(121)/rGel significantly inhibited PCa-induced bone formation in a mouse calvaria culture assay. In vivo, VEGF(121)/rGel significantly inhibited the osteoblastic progression of PCa cells in the femurs of nude mice. Microcomputed tomographic analysis revealed that VEGF(121)/rGel restored the bone volume fraction of tumor-bearing femurs to values similar to those of the contralateral (non-tumor-bearing) femurs. VEGF(121)/rGel significantly reduced the number of tumor-associated osteoclasts but did not change the numbers of peritumoral osteoblasts. Importantly, VEGF(121)/rGel-treated mice had significantly less tumor burden than control mice. Our results thus indicate that VEGF(121)/rGel inhibits osteoblastic tumor progression by targeting angiogenesis, osteoclastogenesis, and bone formation. Targeting VEGF receptor (VEGFR)-1- or VEGFR-2-expressing cells is effective in controlling the osteoblastic progression of PCa in bone. These findings provide the basis for an effective multitargeted approach for metastatic PCa. ©2011 AACR.

Fast and efficient proteolysis by reusable pepsin-encapsulated magnetic sol-gel material for mass spectrometry-based proteomics applications.

PubMed

Kayili, H Mehmet; Salih, Bekir

2016-08-01

Hydrophobic silicon-based material having magnetic properties was fairly synthesized by a classical sol-gel approach. Pepsin enzyme was encapsulated in the sol-gel material and the enzyme activity was evaluated in consequence of the digestion of some common proteins such as α- and β-casein, cytochrome c, myoglobin, and bovine serum albumin (BSA) both in a single protein batch and in the protein mixture. The optimum digestion time of the studied proteins using pepsin-encapsulated magnetic sol-gel material was found to be 20min. To produce the magnetic sol-gel material for convenient and easy proteomics applications, Fe3O4 was doped inside sol-gel material during the gelation step. It was observed that the activity of encapsulated pepsin was not affected by the amount of Fe3O4. Poly(ethylene glycol) was also inserted in sol-gel bulk to obtain suitable roughness and increase the hydrophilicity of the material surface to let protein molecules reach to the sol-gel material easily. The digestion of the protein mixture and non-fat bovine milk was performed with the pepsin-encapsulated magnetic sol-gel material and the digested solutions were analyzed using SDS-PAGE, MALDI-TOF-MS and LC-MS/MS for the protein identification. Reusability of the pepsin-encapsulated sol-gel material was examined and it was determined that they could be used at least 20 times. Finally, IgG digestions with a fast incubation time period were carried out using pepsin-encapsulated sol-gel material for generation of (Fab)2 product to evaluate the kinetic performance of the material. Copyright © 2016 Elsevier B.V. All rights reserved.

rhEGF-containing thermosensitive and mucoadhesive polymeric sol-gel for endoscopic treatment of gastric ulcer and bleeding.

PubMed

Maeng, Jin Hee; So, Jung Won; Kim, Jungju; Kim, In Ae; Jung, Ji Hoon; Min, Kyunghyun; Lee, Don Haeng; Yang, Su-Geun

2014-03-01

Gastrointestinal endoscopy is a standard diagnostic tool for gastrointestinal ulcers and cancer. In this study, we have developed recombinant human epidermal growth factor-containing ulcer-coating polymeric sol-gel for endoscopic application. Chitosan and pluronic F127 were employed for their thermoresponsive and bioadhesive properties. At temperatures below 21, polymeric sol-gel remains liquid during endoscopic application and transforms to gel at body temperature after application on ulcers. In an in vitro cellular wounding assay, recombinant human epidermal growth factor sol-gel significantly enhanced the cell migration and decreased the wounding area (68%) compared to nontreated, recombinant human epidermal growth factor solution, and sol-gel without recombinant human epidermal growth factor (42, 49, and 32 % decreased at day 1). The in vivo ulcer-healing study was performed in an acetic acid-induced gastric ulcer rat model and proved that our recombinant human epidermal growth factor endoscopic sol-gel facilitated the ulcer-healing process more efficiently than the other treatments. Ulcer sizes in the recombinant human epidermal growth factor sol-gel group were decreased 2.9- and 2.1-fold compared with those in the nontreated group on days 1 and 3 after ulceration, respectively. The mucosal thickness in the recombinant human epidermal growth factor sol-gel group was significantly increased compared to that in the nontreated group (3.2- and 6.9-fold on days 1 and 3 after ulceration, respectively). In a gastric retention study, recombinant human epidermal growth factor sol-gel stayed on the gastric mucosa more than 2 h after application. The present study suggests that recombinant human epidermal growth factor sol-gel is a prospective candidate for treating gastric ulcers via endoscopic application.

A single dose of a MIV-150/Zinc acetate gel provides 24 h of protection against vaginal simian human immunodeficiency virus reverse transcriptase infection, with more limited protection rectally 8-24 h after gel use.

PubMed

Kenney, Jessica; Singer, Rachel; Derby, Nina; Aravantinou, Meropi; Abraham, Ciby J; Menon, Radhika; Seidor, Samantha; Zhang, Shimin; Gettie, Agegnehu; Blanchard, James; Piatak, Michael; Lifson, Jeffrey D; Fernández-Romero, José A; Zydowsky, Thomas M; Robbiani, Melissa

2012-11-01

Previously we showed that repeated vaginal application of a MIV-150/zinc acetate carrageenan (MIV-150/ZA/CG) gel and a zinc acetate carrageenan (ZA/CG) gel significantly protected macaques from vaginal simian human immunodeficiency virus reverse transcriptase (SHIV-RT) infection. Gels were applied either daily for 2 weeks or every other day for 4 weeks, and the animals were challenged 4-24 h later. Herein, we examined the effects of a single vaginal dose administered either before or after virus challenge. Encouraged by the vaginal protection seen with MIV-150/ZA/CG, we also tested it rectally. Vaginal applications of MIV-150/ZA/CG, ZA/CG, and CG gel were performed once 8-24 h before, 1 h after, or 24 h before and 1 h after vaginal challenge. Rectal applications of MIV-150/ZA/CG and CG gel were performed once 8 or 24 h before rectal challenge. While vaginal pre-challenge and pre/post-challenge application of MIV-150/ZA/CG gel offered significant protection (88%, p<0.002), post-challenge application alone did not significantly protect. ZA/CG gel reduced infection prechallenge, but not significantly, and the effect was completely lost post-challenge. Rectal application of MIV-150/ZA/CG gel afforded limited protection against rectal challenge when applied 8-24 h before challenge. Thus, MIV-150/ZA/CG gel is a highly effective vaginal microbicide that demonstrates 24 h of protection from vaginal infection and may demonstrate efficacy against rectal infection when given close to the time of HIV exposure.

[Induced abortion using prostaglandin E2 and F2alpha gel].

PubMed

Lippert, T H; Modly, T

1974-01-01

In this study of 20 patients in the 13th-17th week of pregnancy abortion was induced with intrauterine, extraamniotic application of prostaglandins (PG) E2 or F2 in gel form. The gel composition was as follows: 4% tylose MH 300, 2% glycerine, 1% chlorhexidine digluconate, 83% sterile distilled water and 10% PG stock solution. Both PGE2 and PGF2 gels were used. Final concentration was 2.5 mg E2 or 2.5 mg F2 per g of gel. Gel was applied via transcervical, extraamniotic polyethylene catheter every 2-3 hours. Results: PGE2-gel was used in 14 cases. After 3-4 applications both fetus and placenta were expelled. Average dose used was 4.6 mg E2/patient. First contractions started in 30 minutes; induction to expulsion time was 11 hours 35 minutes. F2-gel given to 6 patients resulted in expulsion of the fetus in all cases but placenta needed removal by curettage in 4 patients. Average dose per patient was 17.7 mg of F2; first contractions in 30 minutes, average expulsion time 17 hours 38 minutes. With both PGs there were painful contractions which were controlled with a combination of pentazocine and Valium. PGE2 caused vomiting in 5 patients. No increased bleeding or postabortion infection occurred. Follow-up curettage was done in all patients to ensure removal of all tissues. Overall evaluation of the PG-gels was considered good. PG stability in gel form is good; during 8 months of preservation in sterile aluminum tubes at -25 degrees Celsius no decline in clinical effectiveness was noted. The gel application is less expensive than the slow-injection pump method.

A Single Dose of a MIV-150/Zinc Acetate Gel Provides 24 h of Protection Against Vaginal Simian Human Immunodeficiency Virus Reverse Transcriptase Infection, with More Limited Protection Rectally 8–24 h After Gel Use

PubMed Central

Kenney, Jessica; Singer, Rachel; Derby, Nina; Aravantinou, Meropi; Abraham, Ciby J.; Menon, Radhika; Seidor, Samantha; Zhang, Shimin; Gettie, Agegnehu; Blanchard, James; Piatak, Michael; Lifson, Jeffrey D.; Fernández-Romero, José A.; Zydowsky, Thomas M.

2012-01-01

Abstract Previously we showed that repeated vaginal application of a MIV-150/zinc acetate carrageenan (MIV-150/ZA/CG) gel and a zinc acetate carrageenan (ZA/CG) gel significantly protected macaques from vaginal simian human immunodeficiency virus reverse transcriptase (SHIV-RT) infection. Gels were applied either daily for 2 weeks or every other day for 4 weeks, and the animals were challenged 4–24 h later. Herein, we examined the effects of a single vaginal dose administered either before or after virus challenge. Encouraged by the vaginal protection seen with MIV-150/ZA/CG, we also tested it rectally. Vaginal applications of MIV-150/ZA/CG, ZA/CG, and CG gel were performed once 8–24 h before, 1 h after, or 24 h before and 1 h after vaginal challenge. Rectal applications of MIV-150/ZA/CG and CG gel were performed once 8 or 24 h before rectal challenge. While vaginal pre-challenge and pre/post-challenge application of MIV-150/ZA/CG gel offered significant protection (88%, p<0.002), post-challenge application alone did not significantly protect. ZA/CG gel reduced infection prechallenge, but not significantly, and the effect was completely lost post-challenge. Rectal application of MIV-150/ZA/CG gel afforded limited protection against rectal challenge when applied 8–24 h before challenge. Thus, MIV-150/ZA/CG gel is a highly effective vaginal microbicide that demonstrates 24 h of protection from vaginal infection and may demonstrate efficacy against rectal infection when given close to the time of HIV exposure. PMID:22737981

Sol-gel open tubular ODS columns with reversed electroosmotic flow for capillary electrochromatography.

PubMed

Hayes, J D; Malik, A

2001-03-01

Sol-gel chemistry was successfully used for the fabrication of open tubular columns with surface-bonded octadecylsilane (ODS) stationary-phase coating for capillary electrochromatography (OT-CEC). Following column preparations, a series of experiments were performed to investigate the performance of the sol-gel coated ODS columns in OT-CEC. The incorporation of N-octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride as one of the sol-gel precursors played an important role in the electrochromatographic performance of the prepared columns. This chemical reagent possesses a chromatographically favorable, bonded ODS moiety, in conjunction with three methoxy groups allowing for sol-gel reactivity. In addition, a positively charged nitrogen atom is present in the molecular structure of this reagent and provides a positively charged capillary surface responsible for the reversed electroosmotic flow (EOF) in the columns during CEC operation. Comparative studies involving the EOF within such sol-gel ODS coated and uncoated capillaries were performed using acetonitrile and methanol as the organic modifiers in the mobile phase. The use of a deactivating reagent, phenyldimethylsilane, in the sol-gel solution was evaluated. Efficiency values of over 400,000 theoretical plates per meter were achieved in CEC on a 64 cm x 25 microm i.d. sol-gel ODS open tubular column. Test mixtures of polycyclic aromatic hydrocarbons, benzene derivatives, and aromatic aldehydes and ketones were used to evaluate the CEC performances of both nondeactivated and deactivated open tubular sol-gel columns. The effects of mobile-phase organic modifier contents and pH on EOF in such columns were evaluated. The prepared sol-gel ODS columns are characterized by switchable electroosmotic flow. A pH value of approximately 8.5 was found correspond to the isoelectric point for the prepared sol-gel ODS coatings.

Combining strategies to optimize a gel formulation containing miconazole: the influence of modified cyclodextrin on textural properties and drug release.

PubMed

Ribeiro, Andreza Maria; Figueiras, Ana; Freire, Cristina; Santos, Delfim; Veiga, Francisco

2010-06-01

Miconazol, an antimycotic drug, is commonly formulated into semisolid formulations designed to be applied in the oral cavity to treat oral candidiasis. However, given its limited aqueous solubility, permeation through the biological membranes is low and therefore its activity is also limited. Cyclodextrins (CDs) have been widely used to increase the solubility and stability of poorly water-soluble drugs. The aim of this study is to formulate a gel containing an inclusion complex between a modified CD, methyl-beta-cyclodextrin (MbetaCD), and miconazole (MCZ). The influence of the CD on the textural properties of the prepared gel and the drug release from formulation were evaluated. The gels were prepared using two polymers, Carbopol 71G and Pluronic F127, which were selected taking into account their bioadhesiveness and thermal-sensitive gelling properties, respectively. Texture profile analyses were performed at two different temperatures to ascertain the influence of the temperature on the gel texture properties. The in vitro MCZ release profiles from the prepared gel and the commercial gel formulations were evaluated and compared using modified Franz diffusion cells. The addition of MbetaCD to the gel resulted in a decrease of the gel adhesiveness and firmness, and the MCZ release profile through f1 and f2 proved to be similar to the commercial product. A gel comprising miconazol in the form of an inclusion complex with MbetaCD showed suitable textural properties to be applied to the buccal mucosa. The MbetaCD enhanced the solubility of the MCZ in the gel formulation resulting in adequate in vitro drug release profiles.

Effect of eliminating the residual fluoride gel on titanium bracket corrosion.

PubMed

Khoury, Elie S; Abboud, Maher; Bassil-Nassif, Nayla; Bouserhal, Joseph

2011-09-01

Fluoride ions, in long-term applications on titanium brackets, cause their corrosion. Fluoride gel used for caries prevention during orthodontic treatment has a very high concentration in fluoride ions, and therefore has the potential for causing bracket corrosion. The main aim of this study was to determine the effect of eliminating the residual fluoride gel, by rinsing it, on the corrosion of titanium brackets. The secondary aim was to evaluate the corrosion of titanium brackets in the presence of fluoride gel. One hundred titanium brackets were divided into five groups of 20 brackets each. Group 1 being the control group, the rest of the groups were immersed in fluoride gel: Group 2 for 4 minutes and kept for 30 minutes with the residual fluoride gel on; Group 3 for 4 minutes followed by immediate water rinsing; Group 4 for 12 minutes and kept for 90 minutes with the residual fluoride gel on and Group 5 for 12 minutes followed by immediate water rinsing. All groups were rinsed then dried, for 20 hours, using Silica gel in a desiccator maintained at 37°C before testing. Gravimetrical results and SEM analysis showed no significant difference between Groups 2, 3 and 5 compared to each other and to the control group. Only Group 4 showed significant weight loss and pitting corrosion in four of the 20 brackets. In sliding resistance, no significant difference was detected between any of the groups. Short time applications of fluoride gel do not affect sliding resistance of titanium brackets. No titanium corrosion was detected for one application of concentrated fluoride gel and some brackets showed pitting corrosion for three applications. The rinsing of residual fluoride gel eliminates completely the risk of bracket corrosion. Copyright © 2011 CEO. Published by Elsevier Masson SAS. All rights reserved.

Regenerated silica gel as stationary phase on vacuum column chromatography to purify temulawak's extracts

NASA Astrophysics Data System (ADS)

Cahyono, Bambang; Maduwu, Ratna Dewi; Widayat, Suzery, Meiny

2015-12-01

Commercial silica gel only used once by many researchers and affected high cost for purification process, also less support the green chemistry program. This research focused in regeneration silica gel that used purification of temulawak's extracts (Curcuma xanthorrhiza Roxb) by vacuum column chromatography. Sample extracts (contains 10.1195±0.5971% of curcuminoids) was purified by vacuum column chromatography (pressure: 45 kPa, column: 100mm on length and 16mm on diameter). Ethanol 96% and acetone were compared as eluent. The amount of solvent and yield of curcuminoids used as indicator purification. The silica gel was regenerated with heating in 600°C for 8 hours The silica gels were analyzed by IR spectroscopy and X-ray diffraction. Furthermore, regenerated silica gel was used as the stationary phase in vacuum column chromatography under the same conditions with the previous purification. All the purification experiments were performed in three repetitions. Based on regression equation, y=0.132x+0.0011 (r2=0.9997) the yield of curcuminoids on purified products using ethanol as the eluent was improved 4.26% (to 14.3724±0.5749%) and by acetone was improved 3,03% (to 13.1450 ±0.6318%). The IR spectrum of both silica gel showed the same vibration profile and also there were three crystallinity peaks missing on its X-ray diffraction. Regenerated silica gel has the same performance with new silica gel in purification of temulawak's extract: by ethanol has increased 4.08% (14.1947±0.7415%) and 2.93% (13.0447±0.4822) by acetone. In addition, all purification products showed similar TLC profiles. Purification using regenerated silica gel as the adsorbent on vacuum column chromatography has exactly same potential with the new silica gel.

Characterization of microstructure, viscoelasticity, heterogeneity and ergodicity in pectin-laponite-CTAB-calcium nanocomposite hydrogels.

PubMed

Joshi, Nidhi; Rawat, Kamla; Bohidar, H B

2016-01-20

In order to customize the viscoelastic properties of pectin gels, it is necessary to work on a composite platform. Herein, the gelation kinetics, and viscoelastic characterization of anionic polysaccharide pectin dispersion prepared in presence of nanoclay laponite are reported using dynamic light scattering and rheology measurements. The ratio Rg/Rh (Rg and Rh are radius of gyration and hydrodynamic radius respectively) determined from light scattering data revealed the presence of random coils of pectin chains inside the gel matrix. When nanoclay laponite was added to the pectin chains solution, two-phase separation was noticed instantaneously. Therefore, the surfactant cetyltrimethylammonium bromide [CTAB] was added to exfoliate the clay platelets in the dispersion, and also in its gel phase. The exfoliating agent cetyltrimethylammonium bromide ([CTAB]≈ cmc/10) helped to enhance the homogeneity and stability of the pectin-clay sols and gels. The storage and loss moduli (G' and G") of the composite gel changed significantly as function of nanoclay laponite content for concentration up to 0.03% (w/v) causing the softening of the gels (gel strength reduced by close to 50%) compared to pectin-calcium gel. However, as the concentration of nanoclay laponite was maintained between 0.01% and 0.03% (w/v), the gel rigidity (G') recovered by 30% (35-45 Pa). The transition from ergodic to non-ergodic state occurred during sol-gel transition owing to the presence of the nanoclay laponite. The gelation time was not too different from the ergodicity breaking time. Thus, the presence of nanoclay laponite in such minute concentration is shown to cause considerable change in the thermo-physical property of the composite gels. This material property modulation will facilitate designing of soft gels having storage modulus continuously varying in the wide range of 10-70 Pa while keeping the gelation temperature mostly unaltered. Copyright © 2015 Elsevier Ltd. All rights reserved.

Apparatus and method for the production of gel beads containing a biocatalyst

DOEpatents

Scott, C.D.; Scott, T.C.; Davison, B.H.

1998-01-27

An apparatus and method are disclosed for the large-scale and continuous production of gel beads containing a biocatalyst. The apparatus is a columnar system based on the chemical cross-linking of hydrocolloidal gels that contain and immobilize a biocatalyst, the biocatalyst being a microorganism or an enzyme. Hydrocolloidal gels, such as alginate, carrageenan, and a mixture of bone gelatin and modified alginate, provide immobilization matrices that can be used to entrap and retain the biocatalyst while allowing effective contact with substrates and release of products. Such immobilized biocatalysts are generally formulated into small spheres or beads that have high concentrations of the biocatalyst within the gel matrix. The columnar system includes a gel dispersion nozzle submerged in a heated non-interacting liquid, typically an organic liquid, that is immiscible with water to allow efficient formation of spherical gel droplets, the non-interacting liquid having a specific gravity that is less than water so that the gel droplets will fall through the liquid by the force of gravity. The heated non-interacting liquid is in direct contact with a chilled upflowing non-interacting liquid that will provide sufficient residence time for the gel droplets as they fall through the liquid so that they will be cooled below the gelling temperature and form solid spheres. The upflowing non-interacting liquid is in direct contact with an upflowing temperature-controlled aqueous solution containing the necessary chemicals for cross-linking or fixing of the gel beads to add the necessary stability. The flow rates of the two liquid streams can be varied to control the proper residence time in each liquid section to accommodate the production of gel beads of differing settling velocities. A valve is provided for continuous removal of the stabilized gel beads from the bottom of the column. 1 fig.

All optical controlled photonic integrated circuits using azo dye functionized sol-gel material

NASA Astrophysics Data System (ADS)

Ke, Xianjun

The main focus of this dissertation is development and characterization of all-optical controllable azo dye functionized sol gel material, demonstrating a PIC fabrication technique on glass substrate using such material, and exploration and feasibility demonstration of three PIC functional devices namely optical variable attenuator, optical switches, and optical tunable filters using the material. The realization of all the devices in this dissertation are based on one material: dye functionalized sol-gel material. A photochromic sol-gel material functionalized with azo dye was synthesized and characterized. It possesses a photochromic characteristic under the control of green laser beam illumination. The material characteristics suggest the possibility of a new promising material platform candidate for the fabrication of alloptical controlled photonic integrated circuits. As the first potential application of the dye functionalized sol-gel material, an alloptical variable attenuator was designed and demonstrated. The optical variable attenuation is achieved in Mach-Zehnder interferometric configuration through all-optical modulation of sol-gel waveguide phase shifters. A 2 x 2 optical switch based on multimode interference (MMI) waveguide structure is proposed in the dissertation. The schematic configuration of the optical switch consists of a cascade of two identical MMIs with two all-optical controlled phase shifters realized by using the photochromic sol-gel material. The cross or bar switch state of the optical switch is determined by the phase difference between the two sol-gel waveguide phase shifters. An all-optical tunable filter is designed and its feasibility demonstrated by using the sol-gel photochromic material. Except for the phase change demonstrated on sol-gel waveguide phase shifters, dynamic gratings were observed on sol-gel film when exposed to two interference beams. This reveals the possibility of realizing Bragg grating-based tunable filters. The schematic configuration of proposed tunable filters consists of a single straight waveguide embedded with a sol-gel waveguide. The wavelength tuning of the tunable filters is accomplished by varying the grating period.

Kinetics and dynamics of annealing during sub-gel phase formation in phospholipid bilayers

PubMed Central

Páli, Tibor; Bartucci, Rosa; Horváth, László I.; Marsh, Derek

1993-01-01

The saturation transfer electron spin resonance (STESR) spectra of spin-labeled phosphatidylcholine have been used to follow the kinetics of conversion from the gel phase to the sub-gel phase in aqueous bilayers of dipalmitoyl phosphatidylcholine. This is a simple, well-defined model system for lipid domain formation in membranes. The integrated intensity of the STESR spectrum from the chain-labeled lipid first increases and then decreases with time of incubation in the gel phase at 0°C. The first, more rapid phase of the kinetics is attributed to the conversion of germ nuclei to growth nuclei of the sub-gel phase. The increase in STESR intensity corresponds to the reduction in chain mobility of spin labels located in the gel phase at the boundaries of the growth nuclei and correlates with the increase in the diagnostic STESR line height ratios over this time range. The second, slower phase of the kinetics is attributed to growth of the domains of the sub-gel phase. The decrease in STESR intensity over this time regime corresponds to exclusion of the spin-labeled lipids from the tightly packed sub-gel phase and correlates quantitatively with calibrations of the spin label concentration dependence of the STESR intensity in the gel phase. The kinetics of formation of the sub-gel phase are consistent with the classical model for domain formation and growth. At 0°C, the half-time for conversion of germ nuclei to growth nuclei is ∼7.7 h and domain growth of the sub-gel phase is characterized by a rate constant of 0.025 h-1. The temperature dependence of the STESR spectra from samples annealed at 0°C suggests that the subtransition takes place via dissolution of sub-gel phase domains, possibly accompanied by domain fission. PMID:19431899

Radiological properties of MAGIC normoxic polymer gel dosimetry

NASA Astrophysics Data System (ADS)

Aljamal, M.; Zakaria, A.; Shamsuddin, S.

2013-04-01

For a polymer gel dosimeter to be of use in radiation dosimetry, it should display water-equivalent radiological properties. In this study, the radiological properties of the MAGIC (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper) normoxic polymer gels were investigated. The mass density (ρ) was determined based on Archimedes' principle. The weight fraction of elemental composition and the effective atomic number (Zeff) were calculated. The electron density was also measured with 90° scattering angle at room temperature. The linear attenuation coefficient (μ) of unirradiated gel, irradiated gel, and water were determined using Am-241 based on narrow beam geometry. Monte Carlo simulation was used to calculate the depth doses response of MAGIC gel and water for 6MV photon beam. The weight fractions of elements composition of MAGIC gel were close to that for water. The mass density was found to be 1027 ± 2 kg m-3, which is also very close to mass density of muscle tissue (1030 kg m-3) and 2.7% higher than that of water. The electron density (ρe) and atomic number (Zeff) were found to be 3.43 × 1029 e m-3 and 7.105, respectively. The electron density measured was 2.6% greater than that for water. The atomic number was very close to that for water. The prepared MAGIC gel was found to be water equivalent based on the study of element composition, mass density, electron density and atomic number. The linear attenuation coefficient of unirradiated gel was very close to that of water. The μ of irradiated gel was found to be linear with dose 2-40 Gy. The depth dose response for MAGIC gel from a 6 MV photon beam had a percentage dose difference to water of less than 1%. Therefore it satisfies the criteria to be a good polymer gel dosimeter for radiotherapy.

Injectable biocompatible and biodegradable pH-responsive hollow particle gels containing poly(acrylic acid): the effect of copolymer composition on gel properties.

PubMed

Halacheva, Silvia S; Adlam, Daman J; Hendow, Eseelle K; Freemont, Tony J; Hoyland, Judith; Saunders, Brian R

2014-05-12

The potential of various pH-responsive alkyl (meth)acrylate ester- and (meth)acrylic acid-based copolymers, including poly(methyl methacrylate-co-acrylic acid) (PMMA-AA) and poly(n-butyl acrylate-co-methacrylic acid) (PBA-MAA), to form pH-sensitive biocompatible and biodegradable hollow particle gel scaffolds for use in non-load-bearing soft tissue regeneration have been explored. The optimal copolymer design criteria for preparation of these materials have been established. Physical gels which are both pH- and redox-sensitive were formed only from PMMA-AA copolymers. MMA is the optimal hydrophobic monomer, whereas the use of various COOH-containing monomers, e.g., MAA and AA, will always induce a pH-triggered physical gelation. The PMMA-AA gels were prepared at physiological pH range from concentrated dispersions of swollen, hollow, polymer-based particles cross-linked with either cystamine (CYS) or 3,3'-dithiodipropionic acid dihydrazide (DTP). A linear relationship between particle swelling ratios, gel elasticity, and ductility was observed. The PMMA-AA gels with lower AA contents feature lower swelling ratios, mechanical strengths, and ductilities. Increasing the swelling ratio (e.g., through increasing AA content) decreased the intraparticle elasticity; however, intershell contact and gel elasticity were found to increase. The mechanical properties and performance of the gels were tuneable upon varying the copolymers' compositions and the structure of the cross-linker. Compared to PMMA-AA/CYS, the PMMA-AA/DTP gels were more elastic and ductile. The biodegradability and cytotoxicity of the new hollow particle gels were tested for the first time and related to their composition, mechanical properties, and morphology. The new PMMA-AA/CYS and PMMA-AA/DTP gels have shown good biocompatibility, biodegradability, strength, and interconnected porosity and therefore have good potential as a tissue repair agent.

Increasing the activity and enantioselectivity of lipases by sol-gel immobilization: further advancements of practical interest

NASA Astrophysics Data System (ADS)

Tielmann, Patrick; Kierkels, Hans; Zonta, Albin; Ilie, Adriana; Reetz, Manfred T.

2014-05-01

The entrapment of lipases in hydrophobic silicate matrices formed by sol-gel mediated hydrolysis of RSi(OCH3)3/Si(OCH3)4 as originally reported in 1996 has been improved over the years by a number of modifications. In the production of second-generation sol-gel lipase immobilizates, a variety of additives during the sol-gel process leads to increased activity and enhanced stereoselectivity in esterifying kinetic resolution. Recent advances in this type of lipase immobilization are reviewed here, in addition to new results regarding the sol-gel entrapment of the lipase from Burkholderia cepacia. It constitutes an excellent heterogeneous biocatalyst in the acylating kinetic resolution of two synthetically and industrially important chiral alcohols, rac-sulcatol and rac-trans-2-methoxycyclohexanol. The observation that the catalyst can be used 10 times in recycling experiments without losing its significant activity or enantioselectivity demonstrates the practical viability of the sol-gel approach.The entrapment of lipases in hydrophobic silicate matrices formed by sol-gel mediated hydrolysis of RSi(OCH3)3/Si(OCH3)4 as originally reported in 1996 has been improved over the years by a number of modifications. In the production of second-generation sol-gel lipase immobilizates, a variety of additives during the sol-gel process leads to increased activity and enhanced stereoselectivity in esterifying kinetic resolution. Recent advances in this type of lipase immobilization are reviewed here, in addition to new results regarding the sol-gel entrapment of the lipase from Burkholderia cepacia. It constitutes an excellent heterogeneous biocatalyst in the acylating kinetic resolution of two synthetically and industrially important chiral alcohols, rac-sulcatol and rac-trans-2-methoxycyclohexanol. The observation that the catalyst can be used 10 times in recycling experiments without losing its significant activity or enantioselectivity demonstrates the practical viability of the sol-gel approach. Dedicated to the pioneer of sol-gel enzyme immobilization, Professor David Avnir, on the occasion of his 65th birthday.

SU-E-T-799: Verification of a Simultaneous Treatment of Multiple Brain Metastases Using VMAT Technique by a Composite Alanine-Gel Dosimeter Phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pavoni, J; Silveira, M; Filho, O Baffa

Purpose: This work presents an end-to-end test using a Gel-Alanine phantom to validate the three-dimensional (3D) dose distribution (DD) delivered by a single isocenter VMAT technique on the simultaneous treatment of multiple brain metastases. Methods: Three cylindrical phantons containing MAGIC-f gel dosimeter were used to measure the 3D DD of a VMAT treatment, the first two were filled with the gel dosimeter (Gel 1 and 2) and the third one was filled with gel and 12 alanine dosimeters distributed along it (Gel 3). Gels 1 and 3 were irradiated and gel 2 was used to map the magnetic resonance imagemore » (MRI) scanner field inomogeneities. A CT scan of gel 3 was used for the VMAT treatment planning and 5 alanine pellets were chosen as lesions, around them a PTV was grown and different dose prescriptions were assigned for each one, varying from 5 to 9Gy. Before treatment, the plan was approved in a QA based on an ionization chamber absolute dose measurement, a radiochromic film planar dose measurement and a portal dosimetry per field verification; and also the phantons positioning were verified by ExacTrac 6D correction and OBI kV Cone Beam CT. The gels were irradiated, the MRIs were acquired 24 hours after irradiation and finally, the alanine dosimeters were analysed in a X-band Electron Spin Resonance spectrometer. Results: The association of the two detectors enabled the 3D dose evaluation by gel and punctually inside target volumes by alanine. In the gamma analyses (3%/3mm) comparing the 5 PTVs’ central images DD with TPS expected DD more than 95% of the points were approved. The alanine absolute dose measurements were in agreement with TPS by less than 5%. Conclusion: The gel-alanine phantom enabled the dosimetric validation of multiple brain metastases treatment using VMAT, being an almost ideal tool for this application. This work is partially supported by FAPESP.« less

A Study of Dip-Coatable, High-Capacitance Ion Gel Dielectrics for 3D EWOD Device Fabrication

PubMed Central

Clement, Carlos E.; Jiang, Dongyue; Thio, Si Kuan; Park, Sung-Yong

2017-01-01

We present a dip-coatable, high-capacitance ion gel dielectric for scalable fabrication of three-dimensional (3D) electrowetting-on-dielectric (EWOD) devices such as an n × n liquid prism array. Due to the formation of a nanometer-thick electric double layer (EDL) capacitor, an ion gel dielectric offers two to three orders higher specific capacitance (c ≈ 10 μF/cm2) than that of conventional dielectrics such as SiO2. However, the previous spin-coating method used for gel layer deposition poses several issues for 3D EWOD device fabrication, particularly when assembling multiple modules. Not only does the spin-coating process require multiple repetitions per module, but the ion gel layer also comes in risks of damage or contamination due to handling errors caused during assembly. In addition, it was observed that the chemical formulation previously used for the spin-coating method causes the surface defects on the dip-coated gel layers and thus leads to poor EWOD performance. In this paper, we alternatively propose a dip-coating method with modified gel solutions to obtain defect-free, functional ion gel layers without the issues arising from the spin-coating method for 3D device fabrication. A dip-coating approach offers a single-step coating solution with the benefits of simplicity, scalability, and high throughput for deposition of high-capacitance gel layers on non-planar EWOD devices. An ion gel solution was prepared by combining the [EMIM][TFSI] ionic liquid and the [P(VDF-HFP)] copolymer at various wt % ratios in acetone solvent. Experimental studies were conducted to fully understand the effects of chemical composition ratios in the gel solution and how varying thicknesses of ion gel and Teflon layers affects EWOD performance. The effectiveness and potentiality of dip-coatable gel layers for 3D EWOD devices have been demonstrated through fabricating 5 × 1 arrayed liquid prisms using a single-step dip-coating method. Each prism module has been individually controlled to achieve spatial beam steering without the need for bulky mechanical moving parts. PMID:28772400

A Study of Dip-Coatable, High-Capacitance Ion Gel Dielectrics for 3D EWOD Device Fabrication.

PubMed

Clement, Carlos E; Jiang, Dongyue; Thio, Si Kuan; Park, Sung-Yong

2017-01-05

We present a dip-coatable, high-capacitance ion gel dielectric for scalable fabrication of three-dimensional (3D) electrowetting-on-dielectric (EWOD) devices such as an n × n liquid prism array. Due to the formation of a nanometer-thick electric double layer (EDL) capacitor, an ion gel dielectric offers two to three orders higher specific capacitance ( c ≈ 10 μF/cm²) than that of conventional dielectrics such as SiO₂. However, the previous spin-coating method used for gel layer deposition poses several issues for 3D EWOD device fabrication, particularly when assembling multiple modules. Not only does the spin-coating process require multiple repetitions per module, but the ion gel layer also comes in risks of damage or contamination due to handling errors caused during assembly. In addition, it was observed that the chemical formulation previously used for the spin-coating method causes the surface defects on the dip-coated gel layers and thus leads to poor EWOD performance. In this paper, we alternatively propose a dip-coating method with modified gel solutions to obtain defect-free, functional ion gel layers without the issues arising from the spin-coating method for 3D device fabrication. A dip-coating approach offers a single-step coating solution with the benefits of simplicity, scalability, and high throughput for deposition of high-capacitance gel layers on non-planar EWOD devices. An ion gel solution was prepared by combining the [EMIM][TFSI] ionic liquid and the [P(VDF-HFP)] copolymer at various wt % ratios in acetone solvent. Experimental studies were conducted to fully understand the effects of chemical composition ratios in the gel solution and how varying thicknesses of ion gel and Teflon layers affects EWOD performance. The effectiveness and potentiality of dip-coatable gel layers for 3D EWOD devices have been demonstrated through fabricating 5 × 1 arrayed liquid prisms using a single-step dip-coating method. Each prism module has been individually controlled to achieve spatial beam steering without the need for bulky mechanical moving parts.

Influence of the gel thickness on in vivo hyaline cartilage regeneration induced by double-network gel implanted at the bottom of a large osteochondral defect: short-term results.

PubMed

Matsuda, Hidetoshi; Kitamura, Nobuto; Kurokawa, Takayuki; Arakaki, Kazunobu; Gong, Jian Ping; Kanaya, Fuminori; Yasuda, Kazunori

2013-01-31

A double-network (DN) gel, which is composed of poly(2-acrylamido-2-methylpropanesulfonic acid) and poly(N,N'-dimethyl acrylamide), can induce hyaline cartilage regeneration in vivo in a large osteochondral defect. The purpose of this study was to clarify the influence of the thickness of the implanted DN gel on the induction ability of hyaline cartilage regeneration. Thirty-eight mature rabbits were used in this study. We created an osteochondral defect having a diameter of 4.3-mm in the patellofemoral joint. The knees were randomly divided into 4 groups (Group I: 0.5-mm thick gel, Group II: 1.0-mm thick gel, Group III: 5.0-mm thick gel, and Group IV: untreated control). Animals in each group were further divided into 3 sub-groups depending on the gel implant position (2.0-, 3.0-, or 4.0-mm depth from the articular surface) in the defect. The regenerated tissues were evaluated with the Wayne's gross and histological grading scales and real time PCR analysis of the cartilage marker genes at 4 weeks. According to the total Wayne's score, when the depth of the final vacant space was set at 2.0 mm, the scores in Groups I, II, and III were significantly greater than that Group IV (p<0.05), although there were no significant differences between Groups I and IV at a 3.0-mm deep vacant space. The expression levels of type-2 collagen in Groups II and III were significantly higher (p<0.05) than that in Group IV. The 1.0-mm thick DN gel sheet had the same ability to induce hyaline cartilage regeneration as the 5.0-mm thick DN gel plug. However, the induction ability of the 0.5-mm thick sheet was significantly lower when compared with the 1.0-mm thick gel sheet. The 1.0-mm DN gel sheet is a promising device to establish a cell-free cartilage regeneration strategy that minimizes bone loss from the gel implantation.

Matrix-associated implantation of predifferentiated mesenchymal stem cells versus articular chondrocytes: in vivo results of cartilage repair after 1 year.

PubMed

Marquass, Bastian; Schulz, Ronny; Hepp, Pierre; Zscharnack, Matthias; Aigner, Thomas; Schmidt, Stefanie; Stein, Frank; Richter, Robert; Osterhoff, Georg; Aust, Gabriele; Josten, Christoph; Bader, Augustinus

2011-07-01

The use of predifferentiated mesenchymal stem cells (MSC) leads to better histological results compared with undifferentiated MSC in sheep. This raises the need for a longer term follow-up study and comparison with a clinically established method. We hypothesized that chondrogenic in vitro predifferentiation of autologous MSC embedded in a collagen I hydrogel leads to better structural repair of a chronic osteochondral defect in an ovine stifle joint after 1 year. We further hypothesized that resulting histological results would be comparable with those of chondrocyte-seeded matrix-associated autologous chondrocyte transplantation (MACT). Controlled laboratory study. Predifferentiation period of ovine MSC within collagen gel in vitro was defined by assessment of several cellular and molecular biological parameters. For the animal study, 2 osteochondral lesions (7-mm diameter) were created at the medial femoral condyles of the hind legs in 9 sheep. Implantation of MSC gels was performed 6 weeks after defect creation. Thirty-six defects were divided into 4 treatment groups: (1) chondrogenically predifferentiated MSC gels (pre-MSC gels), (2) undifferentiated MSC gels (un-MSC gels), (3) MACT gels, and (4) untreated controls (UC). Histological, immunohistochemical, and radiological evaluations followed after 12 months. After 12 months in vivo, pre-MSC gels showed significantly better histological outcome compared with un-MSC gels and UC. Compared with MACT gels, the overall scores were higher for O'Driscoll and International Cartilage Repair Society (ICRS). The repair tissue of the pre-MSC group showed immunohistochemical detection of interzonal collagen type II staining. Radiological evaluation supported superior bonding of pre-MSC gels to perilesional native cartilage. Compared with previous work by our group, no degradation of the repair tissue between 6 and 12 months in vivo, particularly in pre-MSC gels, was observed. Repair of chronic osteochondral defects with collagen hydrogels composed of chondrogenically predifferentiated MSC shows no signs of degradation after 1 year in vivo. In addition, pre-MSC gels lead to partially superior histological results compared with articular chondrocytes. The results suggest an encouraging method for future treatment of focal osteochondral defects without donor site morbidity by harvesting articular chondrocytes.

SU-E-T-130: Dosimetric Evaluation of Tissue Equivalent Gel Dosimeter Using Saccharide in Radiotherapy System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Y; Lee, D; Jung, H

2014-06-01

Purpose: In this study, the dose responses of the MAGIC gel with various concentrations and type of saccharide are examined to clarify the roles of mono and disaccharide in the polymerization process. Then we focused on the tissue equivalence and dose sensitivity of MAGIC gel dosimeters. Methods: The gel is composed of HPLC, 8% gelatin, 2 × 10-3 M L-ascorbic acid, 1.8 × 10-2 M hydroquinone, 8 × 10-5 M copper(II)sulfate and 9% methacrylic acid, new polymer gels are synthesized by adding glucose(monosaccharide), sucrose(disaccharide) and urea in the concentration range of 5∼35%. For irradiation of the gel, cesium-137 gamma-ray irradiatormore » was used, radiation dose was delivered from 5∼50 Gy. MRI images of the gel were acquired by using a 3.0 T MRI system. Results: When saccharide and urea were added, the O/C, O/N and C/N ratios agreed with those of soft tissue with 1.7%. The dose-response of glucose and sucrose gel have slope-to-intercept ratio of 0.044 and 0.283 respectively. The slope-to-ratio is one important determinant of gel sensitivity. R-square values of glucose and sucrose gel dosimeters were 0.984 and 0.994 respectively. Moreover when urea were added, the slope-to-intercept ratio is 0.044 and 0.073 respectively. R-square values of mono and disaccharide gel were 0.973 and 0.989 respectively. When a saccharide is added into the MAGIC gel dosimeter, dose sensitivity is increased. However when urea were added, dose sensitivity is slightly decreased. Conclusion: In this study, it was possible to obtain the following conclusions by looking at the dose response characteristics after adding mono-, di-saccharide and urea to a MAGIC gel dosimeter. Saccharide was a tendency of increasing dose sensitivity with disaccharide. Sa.ccharide is cost effective, safe, soft tissue equivalent, and can be used under various experimental conditions, making it a suitable dosimeter for some radiotherapy applications.« less

Agarose gel electrophoresis for the separation of DNA fragments.

PubMed

Lee, Pei Yun; Costumbrado, John; Hsu, Chih-Yuan; Kim, Yong Hoon

2012-04-20

Agarose gel electrophoresis is the most effective way of separating DNA fragments of varying sizes ranging from 100 bp to 25 kb(1). Agarose is isolated from the seaweed genera Gelidium and Gracilaria, and consists of repeated agarobiose (L- and D-galactose) subunits(2). During gelation, agarose polymers associate non-covalently and form a network of bundles whose pore sizes determine a gel's molecular sieving properties. The use of agarose gel electrophoresis revolutionized the separation of DNA. Prior to the adoption of agarose gels, DNA was primarily separated using sucrose density gradient centrifugation, which only provided an approximation of size. To separate DNA using agarose gel electrophoresis, the DNA is loaded into pre-cast wells in the gel and a current applied. The phosphate backbone of the DNA (and RNA) molecule is negatively charged, therefore when placed in an electric field, DNA fragments will migrate to the positively charged anode. Because DNA has a uniform mass/charge ratio, DNA molecules are separated by size within an agarose gel in a pattern such that the distance traveled is inversely proportional to the log of its molecular weight(3). The leading model for DNA movement through an agarose gel is "biased reptation", whereby the leading edge moves forward and pulls the rest of the molecule along(4). The rate of migration of a DNA molecule through a gel is determined by the following: 1) size of DNA molecule; 2) agarose concentration; 3) DNA conformation(5); 4) voltage applied, 5) presence of ethidium bromide, 6) type of agarose and 7) electrophoresis buffer. After separation, the DNA molecules can be visualized under uv light after staining with an appropriate dye. By following this protocol, students should be able to: Understand the mechanism by which DNA fragments are separated within a gel matrix Understand how conformation of the DNA molecule will determine its mobility through a gel matrix Identify an agarose solution of appropriate concentration for their needs Prepare an agarose gel for electrophoresis of DNA samples Set up the gel electrophoresis apparatus and power supply Select an appropriate voltage for the separation of DNA fragments Understand the mechanism by which ethidium bromide allows for the visualization of DNA bands Determine the sizes of separated DNA fragments.

A novel tantalum-based sol-gel packed microextraction syringe for highly specific enrichment of phosphopeptides in MALDI-MS applications.

PubMed

Çelikbıçak, Ömür; Atakay, Mehmet; Güler, Ülkü; Salih, Bekir

2013-08-07

A new tantalum-based sol-gel material was synthesized using a unique sol-gel synthesis pathway by PEG incorporation into the sol-gel structure without performing a calcination step. This improved its chemical and physical properties for the high capacity and selective enrichment of phosphopeptides from protein digests in complex biological media. The specificity of the tantalum-based sol-gel material for phosphopeptides was evaluated and compared with tantalum(V) oxide (Ta2O5) in different phosphopeptide enrichment applications. The tantalum-based sol-gel and tantalum(V) oxide were characterized in detail using FT-IR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM), and also using a surface area and pore size analyzer. In the characterization studies, the surface morphology, pore volume, crystallinity of the materials and PEG incorporation into the sol-gel structure to produce a more hydrophilic material were successfully demonstrated. The X-ray diffractograms of the two different materials were compared and it was noted that the broad signals of the tantalum-based sol-gel clearly represented the amorphous structure of the sol-gel material, which was more likely to create enough surface area and to provide more accessible tantalum atoms for phosphopeptides to be easily adsorbed when compared with the neat and more crystalline structure of Ta2O5. Therefore, the phosphopeptide enrichment performance of the tantalum-based sol-gels was found to be remarkably higher than the more crystalline Ta2O5 in our studies. Phosphopeptides at femtomole levels could be selectively enriched using the tantalum-based sol-gel and detected with a higher signal-to-noise ratio by matrix-assisted laser desorption/ionization-mass spectrometer (MALDI-MS). Moreover, phosphopeptides in a tryptic digest of non-fat bovine milk as a complex real-world biological sample were retained with higher yield using a tantalum-based sol-gel. Additionally, the sol-gel material was packed into a standard syringe (0.5 mL) to enhance the ease of use of the sol-gel material and for the elimination of additional mixing and separation procedures during the adsorption, washing and elution steps of the enrichment procedure. It was found that up to 28 phosphopeptides in milk digest were easily detectable by MALDI-MS at femtomole levels (around 20 fmol) using the microextraction syringe within less than one minute.

Integration of gel-based and gel-free proteomic data for functional analysis of proteins through Soybean Proteome Database.

PubMed

Komatsu, Setsuko; Wang, Xin; Yin, Xiaojian; Nanjo, Yohei; Ohyanagi, Hajime; Sakata, Katsumi

2017-06-23

The Soybean Proteome Database (SPD) stores data on soybean proteins obtained with gel-based and gel-free proteomic techniques. The database was constructed to provide information on proteins for functional analyses. The majority of the data is focused on soybean (Glycine max 'Enrei'). The growth and yield of soybean are strongly affected by environmental stresses such as flooding. The database was originally constructed using data on soybean proteins separated by two-dimensional polyacrylamide gel electrophoresis, which is a gel-based proteomic technique. Since 2015, the database has been expanded to incorporate data obtained by label-free mass spectrometry-based quantitative proteomics, which is a gel-free proteomic technique. Here, the portions of the database consisting of gel-free proteomic data are described. The gel-free proteomic database contains 39,212 proteins identified in 63 sample sets, such as temporal and organ-specific samples of soybean plants grown under flooding stress or non-stressed conditions. In addition, data on organellar proteins identified in mitochondria, nuclei, and endoplasmic reticulum are stored. Furthermore, the database integrates multiple omics data such as genomics, transcriptomics, metabolomics, and proteomics. The SPD database is accessible at http://proteome.dc.affrc.go.jp/Soybean/. The Soybean Proteome Database stores data obtained from both gel-based and gel-free proteomic techniques. The gel-free proteomic database comprises 39,212 proteins identified in 63 sample sets, such as different organs of soybean plants grown under flooding stress or non-stressed conditions in a time-dependent manner. In addition, organellar proteins identified in mitochondria, nuclei, and endoplasmic reticulum are stored in the gel-free proteomics database. A total of 44,704 proteins, including 5490 proteins identified using a gel-based proteomic technique, are stored in the SPD. It accounts for approximately 80% of all predicted proteins from genome sequences, though there are over lapped proteins. Based on the demonstrated application of data stored in the database for functional analyses, it is suggested that these data will be useful for analyses of biological mechanisms in soybean. Furthermore, coupled with recent advances in information and communication technology, the usefulness of this database would increase in the analyses of biological mechanisms. Copyright © 2017 Elsevier B.V. All rights reserved.

Kinetic resolution of racemic mixtures in gel media

NASA Astrophysics Data System (ADS)

Petrova, Rositza Iordanova

The goal of this research was to investigate the effect of chiral gels on the chiral crystal nucleation and growth and assess the gels' potential as media for kinetic separation of racemic mixtures. The morphologies of asparagine monohydrate and sodium bromate crystals grown in different gel media were examined in order to discern the effect of gel structure and density on the relative growth rates of those materials. Different crystal habits were observed when the gel chemical composition, density and solute concentration were varied. These studies showed that the physical properties of the gel, such as gel density and pore size, as well as its chemical composition affect the crystal habit. The method of kinetic resolution in gel media was first applied to sodium chlorate, which is achiral in solution but crystallizes in a chiral space group. Crystallization in agarose gels yielded an enantiomorphic bias, the direction and magnitude of which could be affected by changing the temperature or by the addition of an achiral cosolvent. Aqueous gels at 6°C produced crystalline mixtures enriched with the d-enantiomorph, while crystallization under MeOH diffusion favored l-crystals. Optimized conditions yielded e.e. of 53% of l-enantiomorph. The method was next applied to the organic molecular crystals of asparagine monohydrate and threonine. Asparagine monohydrate growth in aqueous agarose and iota-carrageenan gels produced crystal mixtures enriched with D-enantiomer. The degree of resolution was higher when the total amount of asparagine crystallized was low. The success of the resolution depends strongly on the concentrations of solute and the geling substance. Growth from agarose gels yielded e.e. of 44% under optimized conditions. The same method was applied to the resolution of Thr, albeit with modest success. In an effort to improve the resolution of asparagine monohydrate, agarose was synthetically modified by esterifying its side chains with homochiral asparagyl groups and used as a kinetic resolution media. The crystallization from L-Asn-agarose favored crystallization of L-enantiomer (28% e.e.), while D-Asn-agarose favored D-enantiomer (40% e.e.). The degree of resolution was sensitive to the concentrations of the gel and the total amount of crystallized asparagine, but the media was no better than that in pure agarose.

Acceptability of Carraguard, a candidate microbicide and methyl cellulose placebo vaginal gels among HIV-positive women and men in Durban, South Africa

PubMed Central

Ramjee, Gita; Morar, Neetha S; Braunstein, Sarah; Friedland, Barbara; Jones, Heidi; van de Wijgert, Janneke

2007-01-01

Background and Methods When on the market, microbicides are likely to be used by individuals who do not know their HIV status. Hence, assessment of safety and acceptability among HIV positive men and women is important. Acceptability of Carraguard, the Population Council's lead microbicide candidate was assessed in a Phase I safety study among healthy HIV-positive sexually abstinent women and men, and sexually active women (20 per group), in Durban, South Africa. Participants were randomized to use Carraguard gel, placebo gel, or no product. All women in the gel arms applied 4 ml gel vaginally every evening for 14 intermenstrual days (women in the sexually active group inserted gel within 1 hour prior to sex on days when sex occurred), and sexually abstinent men applied gel directly to the penis every evening for 7 days. Acceptability was assessed by face-to-face structured questionnaires and semi-structured in-depth interviews with all participants. Gel use questions were applicable to participants in the gel arms only (13 sexually abstinent women, 14 sexually active women, and 13 abstinent men). Results Overall, 93% of the women liked the study gel (Carraguard or placebo) very much, 4% disliked it somewhat, and 4% were neutral. 15% of men and women disliked the gel's color, smell, or packaging. Most women and men reported never experiencing pain or irritation during or after gel application. Although over two thirds of the women preferred some lubrication during sex, some of the women felt that the gel was frequently too wet. Twenty-one percent of women and 42% of men said they felt covert use of a microbicide would be acceptable. Over 60% of women and men would prefer to use a microbicide alone instead of using it with a condom. Conclusion Acceptability of Carraguard among HIV-positive women and men in Durban was good. The wetness experienced by the women may be attributed to the delivery of gel volume. The applicator was designed to deliver 4 mls whereas in fact between 4 ml to 5 mls were actually dispensed. Condom migration in the event of a partially effective product is of concern. PMID:17900337

A placebo controlled clinical trial investigating the efficacy of a homeopathic after-bite gel in reducing mosquito bite induced erythema.

PubMed

Hill, N; Stam, C; Tuinder, S; van Haselen, R A

1995-01-01

A randomised, placebo controlled clinical trial was conducted to examine the efficacy of a homeopathic after-bite gel in the symptomatic relief of mosquito bites. Sixty eight healthy volunteers were bitten under laboratory conditions by Aedes aegypti mosquitoes at three spots, on the ventral aspect of the forearm. One bite was treated with the homeopathic after-bite gel, another bite with a placebo gel which was identical in appearance and smell to the homeopathic after-bite gel, and the third bite remained untreated. Immediately after the bites and 1, 3, 6, 26 and 31 hours post-bite, the length and width of the erythema were measured with a calliper, and photographs were taken of the bite sites from which the size of the erythema was subsequently determined. This was followed by assessment of the extent of itching with a verbal analogue scale, and finally treatment took place. For each spot the total erythema was calculated as the area under the plotted curve of the erythema at different time points (mm2*h) and the total sum of the itch scores was determined. For the bites treated with the homeopathic after-bite gel the median total erythema was 10.500 mm2*h. For the spots treated with the placebo gel and the untreated spots the median total erythema was 12.900 mm2*h and 13.300 mm2*h, respectively. The difference between the spots treated with the homeopathic after-bite gel and the untreated spots came close to significance (two-tailed P = 0.06), which was not the case for the difference between the spots treated with the homeopathic after-bite gel and the spots treated with placebo gel (P = 0.13). After pooling the data of a very similar previous pilot study and the present study (ntotal = 83), the homeopathic after-bite gel was significantly superior to no treatment (two-tailed P = 0.003) as well as to placebo gel (two-tailed P = 0.03). Comparing itching after the three treatments, no significant differences could be demonstrated. The extent of itching was positively correlated with the area of the erythema (r = 0.63). Treatment of mosquito bites with the homeopathic after-bite gel will reduce the erythema compared to no treatment. Comparison with the placebo gel suggests it is the plant extracts which are the active components of this gel.

Formulation and method for preparing gels comprising hydrous aluminum oxide

DOEpatents

Collins, Jack L.

2014-06-17

Formulations useful for preparing hydrous aluminum oxide gels contain a metal salt including aluminum, an organic base, and a complexing agent. Methods for preparing gels containing hydrous aluminum oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including aluminum, an organic base, and a complexing agent.

Formulation and method for preparing gels comprising hydrous cerium oxide

DOEpatents

Collins, Jack L; Chi, Anthony

2013-05-07

Formulations useful for preparing hydrous cerium oxide gels contain a metal salt including cerium, an organic base, and a complexing agent. Methods for preparing gels containing hydrous cerium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including cerium, an organic base, and a complexing agent.

Sol-Gel deposition of inorganic alkoxides on wood surfaces to enhance their durability under exposure to sunlight and moisture

Treesearch

Mandla A. Tshabalala

2005-01-01

Wood specimens were coated with sol-gel deposits of aluminum isopropoxide, titanium isopropoxide, or zirconium propoxide in the presence of methytrimethoxysilane. Both zirconium propoxide and titanium isopropoxide sol-gel deposits reduced water sorption, whereas aluminum isopropoxide sol-gel deposit increased water sorption, compared with uncoated wood specimens. There...

[Immobilization of pectawamorine G10x by gel entrapment].

PubMed

Bogatskiĭ, A V; Davidenko, T I; Areshidze, I V; Gren', T A; Sevast'ianov, O V

1979-01-01

Polyacrylamide gel immobilization of pectawamorine G10x was investigated. Its pectinesterase and polygalacturonase activity and stability in storage were measured. The degree of pectawamorine binding during gel immobilization was 80--90%, 55% of initial activity being retained. Thermal stability of the immobilized and native preparations was equal. Pectinesterase activity of the gel immobilized enzyme increased during storage.

Sol-gel optics for biomeasurements

NASA Astrophysics Data System (ADS)

Lechna-Marczynska, Monika I.; Podbielska, Halina; Ulatowska-Jarza, Agnieszka; Holowacz, Iwona; Andrzejewski, Damian

2001-10-01

Sol-gel technique is a method for producing of glass-like materials without involving a melting process. Organic compounds such as alcoholates of silicon, sodium or calcium can be used. The irregular non-crystalline network forms a gel structure where the metallic atoms are bonded to oxygen atoms. Low-temperature treatment turns this gel into an inorganic glass-like structure. There are numbers of applications of these materials that can be produced in various forms and shapes. Here, silica based sol-gel bulks and thin films optodes for biomedical applications will be presented.

Rheological Properties of Gels from Pyrene Based Low Molecular Weight Gelators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leivo, Kimmo T.; Hahma, Arno P.

2008-07-07

Gels of pyrene derived low molecular weight organogelators (LMOGs) in primary alcohols have been characterized by rheometry and scanning electron microscopy. Total gelator concentration was 1-2.7 % w/w depending on the solvent and the gelator, including equimolar amounts of the gelator and 2,4,7-trinitrofluorenone (TNF), which is necessary for gelation. Thermoreversible and strongly shear thinning gels were achieved as the two components interact non-covalently to form a gel network. A qualitative correlation between the rheological properties and the nanoscale gel structure were found.

Rheological Properties of Gels from Pyrene Based Low Molecular Weight Gelators

NASA Astrophysics Data System (ADS)

Leivo, Kimmo T.; Hahma, Arno P.

2008-07-01

Gels of pyrene derived low molecular weight organogelators (LMOGs) in primary alcohols have been characterized by rheometry and scanning electron microscopy. Total gelator concentration was 1-2.7 % w/w depending on the solvent and the gelator, including equimolar amounts of the gelator and 2,4,7-trinitrofluorenone (TNF), which is necessary for gelation. Thermoreversible and strongly shear thinning gels were achieved as the two components interact non-covalently to form a gel network. A qualitative correlation between the rheological properties and the nanoscale gel structure were found.

Method for long-term preservation of thin-layer polyacrylamide gels by producing a gelatine coating.

PubMed

Hofmann, K

1991-02-01

Thin-layer polyacrylamide gels can be preserved and stored for unlimited periods by covering them with a gelatine coating. The method is inexpensive and simple. After air-drying, the gel is immersed in an aqueous 10% solution of highly viscous gelatine between 55 and 60 degrees C. The coated gel is dried by hanging it in air. The method was checked successfully with gels of different thicknesses (0.15-0.50 mm) and after using different staining methods, e.g., with silver, Coomassie Brilliant Blue and pseudoperoxidase.

PCR amplification on microarrays of gel immobilized oligonucleotides

DOEpatents

Strizhkov, Boris; Tillib, Sergei; Mikhailovich, Vladimir; Mirzabekov, Andrei

2003-11-04

The invention relates two general methods for performing PCR amplification, combined with the detection and analysis of the PCR products on a microchip. In the first method, the amplification occurs both outside and within a plurality of gel pads on a microchip, with at least one oligonucleotide primer immobilized in a gel pad. In the second method, PCR amplification also takes place within gel pads on a microchip, but the pads are surrounded by a hydrophobic liquid such as that which separates the individual gel pads into environments which resemble micro-miniaturized test tubes.

Fabrication of micro-alginate gel tubes utilizing micro-gelatin fibers

NASA Astrophysics Data System (ADS)

Sakaguchi, Katsuhisa; Arai, Takafumi; Shimizu, Tatsuya; Umezu, Shinjiro

2017-05-01

Tissues engineered utilizing biofabrication techniques have recently been the focus of much attention, because these bioengineered tissues have great potential to improve the quality of life of patients with various hard-to-treat diseases. Most tissues contain micro-tubular structures including blood vessels, lymphatic vessels, and bile canaliculus. Therefore, we bioengineered a micro diameter tube using alginate gel to coat the core gelatin gel. Micro-gelatin fibers were fabricated by the coacervation method and then coated with a very thin alginate gel layer by dipping. A micro diameter alginate tube was produced by dissolving the core gelatin gel. Consequently, these procedures led to the formation of micro-alginate gel tubes of various shapes and sizes. This biofabrication technique should contribute to tissue engineering research fields.

Some rheological properties of sodium caseinate-starch gels.

PubMed

Bertolini, Andrea C; Creamer, Lawrence K; Eppink, Mieke; Boland, Mike

2005-03-23

The influence of sodium caseinate on the thermal and rheological properties of starch gels at different concentrations and from different botanical sources was evaluated. In sodium caseinate-starch gels, for all starches with the exception of potato starch, the sodium caseinate promoted an increase in the storage modulus and in the viscosity of the composite gel when compared with starch gels. The addition of sodium caseinate resulted in an increase in the onset temperature, the gelatinization temperature, and the end temperature, and there was a significant interaction between starch and sodium caseinate for the onset temperature, the peak temperature, and the end temperature. Microscopy results suggested that sodium caseinate promoted an increase in the homogeneity in the matrix of cereal starch gels.

2D-DIGE in Proteomics.

PubMed

Pasquali, Matias; Serchi, Tommaso; Planchon, Sebastien; Renaut, Jenny

2017-01-01

The two-dimensional difference gel electrophoresis method is a valuable approach for proteomics. The method, using cyanine fluorescent dyes, allows the co-migration of multiple protein samples in the same gel and their simultaneous detection, thus reducing experimental and analytical time. 2D-DIGE, compared to traditional post-staining 2D-PAGE protocols (e.g., colloidal Coomassie or silver nitrate), provides faster and more reliable gel matching, limiting the impact of gel to gel variation, and allows also a good dynamic range for quantitative comparisons. By the use of internal standards, it is possible to normalize for experimental variations in spot intensities and gel patterns. Here we describe the experimental steps we follow in our routine 2D-DIGE procedure that we then apply to multiple biological questions.

ELASTICITY, DOUBLE REFRACTION AND SWELLING OF ISOELECTRIC GELATIN

PubMed Central

Kunitz, M.

1930-01-01

Quincke's researches (1904) have demonstrated that when a 20 per cent gelatin gel is allowed to swell in water it gives rise to positive double refraction, as if the gel were under tensile stresses. If, on the other hand, the gel shrinks on being placed in alcohol it becomes negatively double refractive, as if it were compressed. But the double refraction as found by Quincke lasts only during the process of swelling or shrinking, and disappears as soon as the gel reaches a state of equilibrium. This phenomenon was investigated here and it was found that the reason for the disappearance of the double refraction is due to the fact that at equilibrium the percentage change in the size of a gel is equal in all three dimensions and the strain is therefore uniform. Double refraction persists as long as there is a difference in the elastic strain in the three dimensions of the strained material. It was found that when gels are cast on glass slides or in glass frames, so as to prevent swelling in certain directions, the double refraction produced by swelling at 6°C. persists permanently in the gel as long as it is swollen, and is proportional to the percentage change in the linear dimensions of the gel. Gels made up of various concentrations of isoelectric gelatin of less than 10 per cent when placed in dilute buffer of the same pH as that of the isoelectric point of the gelatin shrink and give rise to negative double refraction, while gels of concentrations of more than 10 per cent swell and give rise to positive double refraction. The double refraction produced in either case when divided by the percentage change in the dimensions of the gel and by its changed concentration gives a constant value both for swelling and shrinking. This constant which stands for the double refraction produced in a gel of unit concentration per unit strain is termed here the optical modulus of elasticity since it is proportional to the internal elastic stress in the swollen gelatin. It was found that the optical modulus of elasticity is the same both for gels cast on slides and in frames, although the mode of swelling is different in the two forms of gels. Gels removed from their glass supports after apparent swelling equilibrium, when placed in dilute buffer, begin to swell gradually in all three dimensions and the double refraction decreases slowly, though it persists for a long time. But the double refraction per unit change in dimension and per unit concentration still remains the same as before, thus proving that the internal elastic stress as indicated by the double refraction is brought about by the resistance of the gel itself to deformation. A study was also made on the effect of salts, acid and base on the double refraction of a 10 per cent gel during swelling. The experiments show that below M/8 salts affect very slightly the optical modulus of elasticity of the gel. At higher concentrations of salts the elasticity of the gel is reduced by some salts and increased by others, while such salts as sodium acetate and sodium and ammonium sulfates do not change the elasticity of the gels at all during swelling. The investigated salts may thus be arranged in this respect in the following approximate series: CaCl2, NaI, NaSCN, NaBr, AlCl3, NaCl, Na acetate, Na2SO4, (NH4)2SO4, Al2SO4 and MgSO4. The first five in the series decrease the elasticity while the last two in the series increase the elasticity of the gels during swelling. Acids and bases in higher concentrations exert a powerful influence on the reduction of the elasticity of the gel but in the range of pH between 2.0 and 10.0 the elasticity remains unaffected. The general conclusions to be drawn from these studies are as follows: 1. Swelling or shrinking produces elastic stresses in gels of gelatin, tensile in the first case and compressive in the second case, both being proportional to the percentage change in the dimensions of the gel. 2. Unsupported gels when immersed in aqueous solutions swell or shrink in such a manner that at equilibrium the percentage change in size is equal in all three dimensions, and the stresses become equalized throughout the gel. 3. Gels cast on glass slides or in frames when immersed in aqueous solutions swell or shrink mostly in one direction, and give rise to unidirectional stresses that can be determined accurately by measuring the double refraction produced. 4. The modulus of elasticity of swelling gelatin gels, as calculated from the double refraction measurements, is the same both for compression and for tension and is proportional to the concentration of gelatin in the gel. 5. The modulus of elasticity of gels during swelling is affected only slightly or not at all by salts at concentrations of less than M/8 and is independent of the pH in the range approximately between 2.0 and 10.0. 6. Higher concentrations of salts affect the modulus of elasticity of gelatin gels and the salts in their effectiveness may be arranged in a series similar to the known Hoffmeister series. 7. Acid and alkali have a strong reducing influence on the elastic modulus of swelling gels. 8. The swelling produced in isoelectric gelatin by salts is due primarily to a change brought about by the salts in the osmotic forces in the gel, but in high concentrations of some salts the swelling is increased by the influence of the salt on the elasticity of the gel. This agrees completely with the theory of swelling of isoelectric gelatin as developed by Northrop and the writer in former publications. 9. The studies of Loeb and the writer on the effect of salts on swelling of gelatin in acid and alkali have been in the range of concentrations of salts where the modulus of elasticity of the gelatin is practically constant, and the specific effect of the various salts has been negligible as compared with the effect of the valency of the ions. In concentrations of salts below M/4 or M/8 the Hoffmeister series plays no rôle. PMID:19872548

Comparative evaluation of effectiveness of intra-pocket anesthetic gel and injected local anesthesia during scaling and root planing - A split-mouth clinical trial.

PubMed

Chintala, Kalyan; Kumar, Sandhya Pavan; Murthy, K Raja V

2017-01-01

Pain control is an important outcome measure for successful periodontal therapy. Injected local anesthesia has been used to secure anesthesia for scaling and root planing (SRP) and continues to be the anesthetic of choice for pain control. Alternatively, intra-pocket anesthetic gel has been used as an anesthetic during SRP. Hence, this clinical trial was done to compare the effectiveness of intra-pocket anesthetic gel and injected local anesthesia during SRP and also to assess the influence of intra-pocket anesthetic gel on treatment outcomes in chronic periodontitis patients. Fifteen systemically healthy chronic periodontitis patients were recruited. The dental quadrants on right side received either intra-pocket 20% benzocaine gel (Gel group) or infiltration/block by 2% lidocaine with 1:80,000 adrenaline (injection group). Quadrants on the left side received the alternative. Pain perception and patients preference for the type of anesthesia was recorded. Clinical parameters: plaque index, modified gingival index, modified sulcular bleeding index, probing pocket depth, and clinical attachment level were recorded at baseline and 1 month after treatment. No difference was observed in visual analog scale (P > 0.05) and verbal rating scale (P > 0.05) pain perception between gel group and injection group. A slightly increased preference to gel as anesthesia (53% vs. 47%) was observed. The treatment outcome after SRP did not show a significant difference between gel and injection group (P > 0.05). Intra-pocket administration of 20% benzocaine gel may be effective for pain control during SRP and may offer an alternative to conventional injection anesthesia.

Surface folding-induced attraction and motion of particles in a soft elastic gel: cooperative effects of surface tension, elasticity, and gravity.

PubMed

Chakrabarti, Aditi; Chaudhury, Manoj K

2013-12-17

We report some experimental observations regarding a new type of long-range interaction between rigid particles that prevails when they are suspended in an ultrasoft elastic gel. A denser particle submerges itself to a considerable depth inside the gel and becomes elasto-buoyant by balancing its weight against the elastic force exerted by the surrounding medium. By virtue of a large elasto-capillary length, the surface of the gel wraps around the particle and closes to create a line singularity connecting the particle to the free surface of the gel. A substantial amount of tensile strain is thus developed in the gel network parallel to the free surface that penetrates to a significant depth inside the gel. The field of this tensile strain is rather long-range because of a large gravito-elastic correlation length and sufficiently strong to pull two submerged particles into contact. The particles move toward each other with an effective force following an inverse linear distance law. When more monomers or dimers of the particles are released inside the gel, they orient rather freely inside the capsules where they are located and attract each other to form closely packed clusters. Eventually, these clusters themselves interact and coalesce. This is an emergent phenomenon in which gravity, capillarity, and elasticity work in tandem to create a long-range interaction. We also present the results of a related experiment, in which a particle suspended inside a thickness-graded gel moves accompanied by the continuous folding and the relaxation of the gel's surface.

Versatility of azelaic acid 15% gel in treatment of inflammatory acne vulgaris.

PubMed

Thiboutot, Diane

2008-01-01

Azelaic acid (AzA) 15% gel is approved for the treatment of rosacea in the US, but also has approval for the treatment of acne vulgaris in many European countries where it has demonstrated success. Two randomized, multicenter, controlled clinical trials compared the effects of AzA 15% gel with those of topical benzoyl peroxide 5% or topical clindamycin 1%, all using a twice-daily dosing regimen. The primary endpoint in the intent-to-treat analysis was a reduction in inflammatory papules and pustules. AzA 15% gel resulted in a 70% to 71% median reduction of facial papules and pustules compared with a 77% reduction with benzoyl peroxide 5% gel and a 63% reduction with clindamycin. AzA 15% gel was well-tolerated. In addition, a 1-year European observational study conducted by dermatologists in private practice evaluated the safety and efficacy of AzA 15% gel used as monotherapy or in combination with other agents in more than 1200 patients with acne. Most physicians (81.9%) described an improvement in patients' symptoms after an average of 34.6 days, and 93.9% of physicians reported patient improvement after an average of 73.1 days. Both physicians and patients assessed AzA 15% gel to be effective with 74% of patients being "very satisfied" at the end of therapy. AzA 15% gel was considered "well-tolerated" or "very well-tolerated" by 95.7% of patients. The majority of patients were more satisfied with AzA than with previous therapies. AzA 15% gel represents a new therapeutic option for the treatment of acne vulgaris.

Modified thermoresponsive Poloxamer 407 and chitosan sol-gels as potential sustained-release vaccine delivery systems.

PubMed

Kojarunchitt, Thunjiradasiree; Baldursdottir, Stefania; Dong, Yao-Da; Boyd, Ben J; Rades, Thomas; Hook, Sarah

2015-01-01

Thermoresponsive, particle-loaded, Poloxamer 407 (P407)-Pluronic-R® (25R4) or chitosan-methyl cellulose (MC) formulations were developed as single-dose, sustained release vaccines. The sol-gels, loaded either with a particulate vaccine (cubosomes) or soluble antigen (ovalbumin) and adjuvants (Quil A and monophosphoryl lipid A), were free-flowing liquids at room temperature and formed stable gels at physiological temperatures. Rheological results showed that both systems meet the criteria of being thermoresponsive gels. The P407-25R4 sol-gels did not significantly sustain the release of antigen in vivo while the chitosan-MC sol-gels sustained the release of antigen up to at least 14 days after administration. The chitosan-MC sol-gels stimulated both cellular and humoral responses. The inclusion of cubosomes in the sol-gels did not provide a definitive beneficial effect. Further analysis of the formulations with small-angle X-ray scattering (SAXS) revealed that while cubosomes were stable in chitosan-MC gels they were not stable in P407-25R4 formulations. The reason for the mixed response to cubosome-loaded vehicles requires more investigation, however it appears that the cubosomes did not facilitate synchronous vaccine release and may in fact retard release, reducing efficacy in some cases. From these results, chitosan-MC sol-gels show potential as sustained release vaccine delivery systems, as compared to the P407-25R4 system that had a limited ability to sustain antigen release. Copyright © 2014 Elsevier B.V. All rights reserved.

A Novel Technique for Micro-patterning Proteins and Cells on Polyacrylamide Gels

PubMed Central

Tang, Xin; Ali, M. Yakut; Saif, M. Taher A.

2012-01-01

Spatial patterning of proteins (extracellular matrix, ECM) for living cells on polyacrylamide (PA) hydrogels has been technically challenging due to the compliant nature of the hydrogels and their aqueous environment. Traditional micro-fabrication process is not applicable. Here we report a simple, novel and general method to pattern a variety of commonly used cell adhesion molecules, i.e. Fibronectin (FN), Laminin (LN) and Collagen I (CN), etc. on PA gels. The pattern is first printed on a hydrophilic glass using polydimethylsiloxane (PDMS) stamp and micro-contact printing (μCP). Pre-polymerization solution is applied on the patterned glass and is then sandwiched by a functionalized glass slide, which covalently binds to the gel. The hydrophilic glass slide is then peeled off from the gel when the protein patterns detach from the glass, but remain intact with the gel. The pattern is thus transferred to the gel. The mechanism of pattern transfer is studied in light of interfacial mechanics. It is found that hydrophilic glass offers strong enough adhesion with ECM proteins such that a pattern can be printed, but weak enough adhesion such that they can be completely peeled off by the polymerized gel. This balance is essential for successful pattern transfer. As a demonstration, lines of FN, LN and CN with widths varying from 5–400 μm are patterned on PA gels. Normal fibroblasts (MKF) are cultured on the gel surfaces. The cell attachment and proliferation are confined within these patterns. The method avoids the use of any toxic chemistry often used to pattern different proteins on gel surfaces. PMID:23002394

Formulation development and evaluation of innovative two-polymer (SR-2P) bioadhesive vaginal gel.

PubMed

Podaralla, Satheesh; Alt, Carsten; Shankar, Gita N

2014-08-01

The main objective of this investigation was to study the feasibility of developing a vaginal bioadhesive microbicide using a SRI's proprietary two-polymer gel platform (SR-2P). Several formulations were prepared with different combinations of temperature-sensitive polymer (Pluronic® F-127) and mucoadhesive polymer (Noveon® AA-1), producing gels of different characteristics. Prototype polymeric gels were evaluated for pH, osmolality, buffering capacity, and viscosity under simulated vaginal semen dilutions, and bioadhesivity using ex vivo mini pig vaginal tissues and texture analyzer. The pH of the polymeric gel formulations ranged from 5.1 to 6.4; the osmolality varied from 13 to 173 mOsm. Absolute viscosity ranged from 513 to 3,780 cPs, and was significantly reduced (1.5- to 3-fold) upon incubation with simulated vaginal and semen fluid mixture. Among the tested gels (indicated in the middle row as a molar ratio of a mixture of Noveon vs. Pluronic), only SR-2P retained gel structure upon dilution with simulated fluids and mild simulated coital stress. The pH of the SR-2P gel was maintained at about 4.6 in simulated vaginal fluid and also showed high peak force of adhesion in mini pig vaginal tissue. Furthermore, SR-2P gel caused no or only minimal irritation in a mouse vaginal irritation model. The results of this preliminary study demonstrated the potential application of SR-2P gel as a vaginal microbicide vehicle for delivery of anti-HIV agents.

Composite wound dressings of pectin and gelatin with aloe vera and curcumin as bioactive agents.

PubMed

Tummalapalli, Mythili; Berthet, Morgane; Verrier, Bernard; Deopura, B L; Alam, M S; Gupta, Bhuvanesh

2016-01-01

Aloe vera and curcumin loaded oxidized pectin-gelatin (OP-Gel) matrices were used as antimicrobial finishes on nonwoven cotton fabrics to produce composite wound care devices. The drug release characteristics of the biocomposite dressings indicated that curcumin is released through a biphasic mechanism - erosion of the polymeric matrix, followed by diffusion, while aloe vera is released upon leaching of the polymeric matrix. A 50/50 composition of aloe vera/curcumin was used to fabricate OP-Gel-Aloe Curcumin dressings. However, contrary to our expectations, OP-Gel-Aloe Curcumin dressings exhibited lesser antimicrobial activity compared to OP-Gel-Aloe and OP-Gel-Curcumin dressings. The cytocompatibility of the fabricated dressings was evaluated using NIH3T3 mouse fibroblast cells. OP-Gel-Aloe treated fibroblasts had the highest viability, with the matrices providing a substrate for good cell attachment and proliferation. On the other hand, OP-Gel-Curcumin and OP-Gel-Aloe Curcumin seemed to have induced apoptosis in NIH3T3 cells. In vivo wound healing analysis was carried out using an excisional splint wound model on C57BL/6J mice. OP-Gel-Aloe treated wounds exhibited very rapid healing with 80% of the wound healing in just 8 days. Furthermore, aloe vera exerted a strong anti-inflammatory effect and prominent scar prevention. Histological examination revealed that an ordered collagen formation and neovascularization could be observed along with migration of nuclei. Therefore, OP-Gel-Aloe biocomposite dressings are proposed as viable materials for effective wound management. Copyright © 2015 Elsevier B.V. All rights reserved.

Microneedle-assisted permeation of lidocaine carboxymethylcellulose with gelatine co-polymer hydrogel.

PubMed

Nayak, Atul; Das, Diganta B; Vladisavljević, Goran T

2014-05-01

Lidocaine hydrochloride (LidH) was formulated in sodium carboxymethyl cellulose/ gelatine (NaCMC/GEL) hydrogel and a 'poke and patch' microneedle delivery method was used to enhance permeation flux of LidH. The microparticles were formed by electrostatic interactions between NaCMC and GEL macromolecules within a water/oil emulsion in paraffin oil and the covalent crosslinking was by glutaraldehyde. The GEL to NaCMC mass ratio was varied between 1.6 and 2.7. The LidH encapsulation yield was 1.2 to 7% w/w. LidH NaCMC/GEL was assessed for encapsulation efficiency, zeta potential, mean particle size and morphology. Subsequent in vitro skin permeation studies were performed via passive diffusion and microneedle assisted permeation of LidH NaCMC/GEL to determine the maximum permeation rate through full thickness skin. LidH 2.4% w/w NaCMC/GEL 1:1.6 and 1:2.3 respectively, possessed optimum zeta potential. LidH 2.4% w/w NaCMC/GEL 1:2.3 and 1:2.7 demonstrate higher pseudoplastic behaviour. Encapsulation efficiency (14.9-17.2%) was similar for LidH 2.4% w/w NaCMC/GEL 1:1.6-1:2.3. Microneedle assisted permeation flux was optimum for LidH 2.4% w/w NaCMC/GEL 1:2.3 at 6.1 μg/ml/h. LidH 2.4% w/w LidH NaCMC/GEL 1:2.3 crossed the minimum therapeutic drug threshold with microneedle skin permeation in less than 70 min.

Comparative study on protein cross-linking and gel enhancing effect of microbial transglutaminase on surimi from different fish.

PubMed

Chanarat, Sochaya; Benjakul, Soottawat; H-Kittikun, Aran

2012-03-15

Microbial transglutaminase (MTGase) has been used to increase the gel strength of surimi. Nevertheless, its effectiveness varies with fish species. The aim of this study was to elucidate the effect of MTGase at different levels on protein cross-linking and gel property of surimi from threadfin bream, Indian mackerel and sardine in the presence and absence of endogenous transglutaminase. Breaking force of all surimi gels increased as MTGase levels (0-0.6 U g⁻¹) increased except for threadfin bream surimi gel, where the breaking force decreased at 0.6 U g⁻¹ (P < 0.05). In the presence of EDTA, the gel strengthening effect was lower, suggesting the combined effect of endogenous transglutaminase with MTGase. With the addition of MTGase, the gel with the highest increase in breaking force showed highest decrease in myosin heavy chain. When cross-linking activity of MTGase on natural actomyosin (NAM) was determined, the highest decreasing rate in ε-amino group content with the concomitant increased formation of cross-linked proteins was found in NAM from threadfin bream. The reactivity of muscle proteins toward MTGase-induced cross-linking was in agreement with surimi gel strengthening. The composition and properties of muscle proteins of varying fish species more likely determined protein cross-linking induced by MTGase, thereby affecting their gel properties.

Preparation of ion-activated in situ gel systems of scopolamine hydrobromide and evaluation of its antimotion sickness efficacy.

PubMed

Cao, Shi-lei; Zhang, Qi-zhi; Jiang, Xin-guo

2007-04-01

To develop a novel, in situ gel system for nasal delivery of scopolamine hydrobromide (SCOP) and study its efficacy on motion sickness. SCOP in situ gels at 0.2%, 0.5%, and 1.0% gellan gum concentration (w/v) were prepared, respectively, and characterized in terms of viscosity, in vitro release, and nasal ciliotoxicity. Single photon emission computing tomography technique was used to evaluate the nasal residence time of gel containing (99m)Tc tracer. The antimotion sickness efficacy produced by the in situ gel formulation was investigated in rats and compared with those achieved after subcutaneous and oral administration. The viscosity of the gellan gum formulations either in solution or in gel increased with increasing concentrations of gellan gum. Its release in vitro was moderate in artificial nasal fluid. The micrographic results showed that in situ gels were safe, without nasal ciliotoxicity. In comparison with phosphate buffer saline, a prolonged radioactivity of (99m)Tc in the rabbit nasal cavity was observed after administration of the gellan gum formulation. Intranasal SCOP in situ gel at a dose of 100 microg/kg decreased symptoms of motion sickness significantly in comparison with subcutaneous and oral administration (P<0.01). SCOP nasal in situ gel is a safe and promising therapeutic alternative to existing medications for motion sickness.

Nanostructured DPA-MPC-DPA triblock copolymer gel for controlled drug release of ketoprofen and spironolactone.

PubMed

Azmy, Bahaa; Standen, Guy; Kristova, Petra; Flint, Andrew; Lewis, Andrew L; Salvage, Jonathan P

2017-08-01

Uncontrolled rapid release of drugs can reduce their therapeutic efficacy and cause undesirable toxicity; however, controlled release from reservoir materials helps overcome this issue. The aims of this study were to determine the release profiles of ketoprofen and spironolactone from a pH-responsive self-assembling DPA-MPC-DPA triblock copolymer gel and elucidate underlying physiochemical properties. Drug release profiles from DPA 50 -MPC 250 -DPA 50 gel (pH 7.5), over 32 h (37 °C), were determined using UV-Vis spectroscopy. Nanoparticle size was measured by dynamic light scattering (DLS) and critical micelle concentration (CMC) by pyrene fluorescence. Polymer gel viscosity was examined via rheology, nanoparticle morphology investigated using scanning transmission electron microscopy (STEM) and the gel matrix observed using cryo-scanning electron microscopy (Cryo-SEM). DPA 50 -MPC 250 -DPA 50 copolymer (15% w/v) formed a free-standing gel (pH 7.5) that controlled drug release relative to free drugs. The copolymer possessed a low CMC, nanoparticle size increased with copolymer concentration, and DLS data were consistent with STEM. The gel displayed thermostable viscosity at physiological temperatures, and the gel matrix was a nanostructured aggregation of smaller nanoparticles. The DPA 50 -MPC 250 -DPA 50 copolymer gel could be used as a drug delivery system to provide the controlled drug release of ketoprofen and spironolactone. © 2017 Royal Pharmaceutical Society.

Encapsulation of Mesenchymal Stem Cells Improves Vascularization of Alginate-Based Scaffolds.

PubMed

Steiner, Dominik; Lingens, Lara; Fischer, Laura; Köhn, Katrin; Detsch, Rainer; Boccaccini, Aldo R; Fey, Tobias; Greil, Peter; Weis, Christian; Beier, Justus P; Horch, Raymund E; Arkudas, Andreas

2018-05-09

Vascularization of bioartificial tissues can be significantly enhanced by the generation of an arteriovenous (AV) loop. Besides the surgical vascularization, the choice of the scaffold and the applied cells are indispensable cofactors. The combination of alginate dialdehyde and gelatin (ADA-GEL) and mesenchymal stem cells (MSCs) is a promising approach with regard to biocompatibility, biodegradation, as well as de novo tissue formation. In this study, we targeted the investigation of the vascularization of ADA-GEL with and in the absence of encapsulated MSCs in the AV loop model. A Teflon chamber filled with ADA-GEL microcapsules was placed in the groin of Lewis rats and an AV loop was placed into the chamber. Group A encompassed the ADA-GEL without MSCs, whereas group B contained 2 × 10 6 DiI-labeled MSCs/mL ADA-GEL. Four weeks postoperatively, tissue formation and vascularization were investigated by histology and microcomputed tomography. We were able to prove vascularization originating from the AV loop in both groups with statistically significant more vessels in group B containing MSCs. Moreover, encapsulated MSCs promoted biodegradation of the ADA-GEL microcapsules. In the present study, we were able to demonstrate for the first time, the successful vascularization of ADA-GEL microcapsules by means of the AV loop. Furthermore, ADA-GEL displayed a good biocompatibility and encapsulation of MSCs into ADA-GEL microcapsule-enhanced vascularization as well as biodegradation.

Controlled formation of emulsion gels stabilized by salted myofibrillar protein under malondialdehyde (MDA)-induced oxidative stress.

PubMed

Zhou, Feibai; Sun, Weizheng; Zhao, Mouming

2015-04-15

This study presented the cold-set gelation of emulsions stabilized by salted myofibrillar protein (MP) under oxidative stress originated from malondialdehyde (MDA). Gel properties were compared over a range of MDA/NaCl concentrations including gel viscoelastic properties, strength, water-holding capacity (WHC), amount of protein entrapped, and microstructure. The oxidative stability of emulsion gels as indicated by lipid hydroperoxide was further determined and compared. Results indicated that emulsion stabilized by MP at swollen state under certain ionic strengths (0.2-0.6 M) was the premise of gel formation under MDA. In the presence of intermediate MDA concentrations (2.5-10 mM), the emulsion gels showed an improved elasticity, strength, WHC, and oxidative stability. This improvement should be mainly attributed to the enhanced protein-protein cross-linkings via MDA, which were homogeneously formed among absorbed and/or unabsorbed proteins, entrapping a greater amount and fractions of protein within network. Therefore, the oil droplets were better adherent to the gel matrix. Nevertheless, addition of high MDA concentrations (25-50 mM) led to the formation of excessive covalent bonds, which might break protein-protein bonds and trigger the desorption of protein from the interface. This ultimately caused "oil leak" phenomena as well as the collapse of gel structure and, thus, overall decreased gel properties and oxidative stability.

Polymer gel dosimeters with reduced toxicity: a preliminary investigation of the NMR and optical dose response using different monomers

NASA Astrophysics Data System (ADS)

Senden, R. J.; DeJean, P.; McAuley, K. B.; Schreiner, L. J.

2006-07-01

In this work, three new polymer gel dosimeter recipes were investigated that may be more suitable for widespread applications than polyacrylamide gel dosimeters, since the extremely toxic acrylamide has been replaced with the less harmful monomers N-isopropylacrylamide (NIPAM), diacetone acrylamide and N-vinylformamide. The new gel dosimeters studied contained gelatin (5 wt%), monomer (3 wt%), N,N'-methylene-bis-acrylamide crosslinker (3 wt%) and tetrakis (hydroxymethyl) phosphonium chloride antioxidant (10 mM). The NMR response (R2) of the dosimeters was analysed for conditions of varying dose, dose rate, time post-irradiation, and temperature during irradiation and scanning. It was shown that the dose-response behaviour of the NIPAM/Bis gel dosimeter is comparable to that of normoxic polyacrylamide gel (PAGAT) in terms of high dose-sensitivity and low dependence on dose rate and irradiation temperature, within the ranges considered. The dose-response (R2) of NIPAM/Bis appears to be linear over a greater dose range than the PAGAT gel dosimeter. The effects of time post-irradiation (temporal instability) and temperature during NMR scanning on the R2 response were more significant for NIPAM/Bis dosimeters. Diacetone acrylamide and N-vinylformamide gel dosimeters possessed considerably lower dose-sensitivities. The optical dose-response, measured in terms of the attenuation coefficient for each polymer gel dosimeter, showed potential for the use of optical imaging techniques in future studies.

Spectroscopic studies of triethoxysilane sol-gel and coating process.

PubMed

Li, Ying-Sing; Ba, Abdul

2008-10-01

Silica sol-gels have been prepared under different conditions using triethoxysilane (TES) as precursor. The prepared sol-gels have been used to coat aluminum for corrosion protection. Vibrational assignments have been made for most vibration bands of TES, TES sol-gel, TES sol-gel-coated aluminum and xerogel. It has been noticed that air moisture may have helped the hydrolysis of the thin coating films. Xerogels have been obtained from the sol-gel under different temperature conditions and the resulting samples have been characterized by using infrared and Raman spectroscopic methods. IR data indicate that the sol-gel process is incomplete under the ambient conditions although an aqueous condition can have slightly improved the process. Two nonequivalent silicon atoms have been identified from the collected 29Si NMR spectra for the sol-gel, supporting the result derived from the IR data. The frequency of Si-H bending vibration has been found to be more sensitive to the skeletal structure than that of the Si-H stretching vibration. A higher temperature condition could favor the progression of hydrolysis and condensation. A temperature higher than 300 degrees C would cause sample decomposition without seriously damaging the silica network. From infrared intensity measurements and thermo-gravimetric analyses, the fractions of incomplete hydrolysis and condensation species have been estimated to be 4% and 3%, respectively. Electrochemical data have shown that the sol-gel coating significantly improves the corrosion protection properties of aluminum.

Physical Properties of Substituted Imidazolium Based Ionic Liquids Gel Electrolytes

NASA Astrophysics Data System (ADS)

Sutto, Thomas E.; De Long, Hugh C.; Trulove, Paul C.

2002-11-01

The physical properties of solid gel electrolytes of either polyvinylidene diflurohexafluoropropylene or a combination of polyvinylidene hexafluoropropylene and polyacrylic acid, and the molten salts 1-ethyl-3-methylimidazolium tetrafluoroborate, 1,2-dimethyl-3-n-propylimidazolium tetrafluoroborate, and the new molten salts 1,2-dimethyl-3-n-butylimidazolium tetrafluoroborate, and 1,2-dimethyl-3-n-butylimidazolium hexafluorophosphate were characterized by temperature dependent ionic conductivity measurements for both the pure molten salt and of the molten salt with 0.5 M Li+ present. Ionic conductivity data indicate that for each of the molten salts, the highest concentration of molten salt allowable in a single component polymer gel was 85%, while gels composed of 90%molten salt were possible when using both polyvinylidene hexafluorophosphate and polyacrylic acid. For polymer gel composites prepared using lithium containing ionic liquids, the optimum polymer gel composite consisted of 85% of the 0.5 M Li+/ionic liquid, 12.75% polyvinylidene hexafluoropropylene, and 2.25% poly (1-carboxyethylene). The highest ionic conductivity observed was for the gel containing 90%1-ethyl-3-methyl-imidazolium tetrafluoroborate, 9.08 mS/cm. For the lithium containing ionic liquid gels, their ionic conductivity ranged from 1.45 to 0.05 mS/cm, which is comparable to the value of 0.91 mS/cm, observed for polymer composite gels containing 0.5 M LiBF4 in propylene carbonate.

Biodistribution, pharmacokinetics, and nuclear imaging studies of 111In-labeled rGel/BLyS fusion toxin in SCID mice bearing B cell lymphoma.

PubMed

Wen, Xiaoxia; Lyu, Mi-Ae; Zhang, Rui; Lu, Wei; Huang, Qian; Liang, Dong; Rosenblum, Michael G; Li, Chun

2011-08-01

We examined the biodistribution and pharmacokinetics of (111)In-labeled rGel/BLyS, a gelonin toxin (rGel)-B lymphocyte stimulator (BLyS) fusion protein. rGel/BLyS was labeled with In-111 through DTPA with a labeling efficiency >95%. Biodistribution/imaging studies were obtained in severe-combined immunodeficiency mice bearing diffuse large B cell lymphoma OCI-Ly10. Pharmacokinetic studies were performed in BALB/c mice. In vitro, DTPA-conjugated rGel/BLyS displayed selective cytotoxicity against OCI-Ly10 cells and mantle cell lymphoma JeKo cells. In vivo, rGel/BLyS exhibited a tri-exponential disposition with a rapid initial mean distribution followed by an extensive mean distribution and a long terminal elimination phase. At 48 h after injection, uptake of the radiotracer in tumors was 1.25 %ID/g, with a tumor-to-blood ratio of 13. Tumors were clearly visualized at 24-72 h post-injection. Micro-SPECT-CT images and ex vivo analyses confirmed the accumulation of rGel/BLyS in OCI-Ly10 tumors. (111)In-DTPA-rGel/BLyS are distributed to B cell tumors and induce apoptosis in tumors. Preclinical antitumor studies using rGel/BLyS should use a twice-per-week treatment schedule.

Poly(ethylene imine)-based granular sorbents by a new process of templated gel-filling. High capacity and selectivity of copper sorption in acidic and alkaline media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chanda, M.; Rempel, G.L.

A new process has been developed for making granular gel-type sorbents from chelating resins using metal ion as template. Named as templated gel-filling, the process uses the chosen metal as templating host ion on high-surface-area silica to build a templated gel layer from a solution of the chelating resin in a suitable solvent in which the resin is soluble but its metal complex is insoluble. After cross-linking the templated gel layer, the silica support is removed by alkali to produce a hollow shell of the templated gel. The shells are then soaked in a concentrated aqueous solution of the samemore » metal ion and suspended in the same resin solution to afford gel-filling. The shells thus filled with metal-templated gel are treated with cross-linking agent, followed by acid to remove the template ion and activate the resin for metal sorption. Poly(ethyleneimine) and its partially ethylated derivative have been used to produce granular gel-type sorbents by this process, with Cu(II) as the template ion. These sorbents are found to offer high capacity and selectivity for copper over nickel, cobalt, and zinc in both acidic and alkaline media. Containing a relatively high fraction of imbibed water, the sorbents exhibit markedly enhanced rate behavior, in both sorption and stripping.« less

Preparation and brain delivery of nasal solid lipid nanoparticles of quetiapine fumarate in situ gel in rat model of schizophrenia

PubMed Central

Li, Jian-Chun; Zhang, Wen-Jing; Zhu, Jin-Xiu; Zhu, Na; Zhang, Hong-Min; Wang, Xiu; Zhang, Jin; Wang, Qing-Qing

2015-01-01

To investigate the brain delivery in rat by nasal Quetiapine fumarate (QF) loaded with solid lipid nanoparticles in situ gel (QF-SLN-gel). QF-SLN-gel was prepared through micro-emulsion technique. The rat model of schizophrenia was established by intraperitoneal injection of (+)-MK-801, evaluated by stereotypic behavior, Mori’s Water Maze (MWM) test and hematoxylin and eosin (HE) staining of hippocampus. The animals were administrated with QF via oral, nasal or tail vein approach and the concentration of QF in blood and brain was determined using high performance liquid chromatography (HPLC). The QF-SLN-gel was even and transparent, having size of 117.8±2.67 d.nm, potential of 57.2±0.24 mV and EF of 97.6±0.58%. After administration of QF-SLN-gel, the concentration of QF in blood and brain of rats in nasal QF-SLN-gel group was similar with that of rats in tail vein QF group, but significantly higher than that of rats in oral QF group. The hippocampal morphology changes induced by (+)-MK-801 were ameliorated by QF, with advantage of nasal QF-SLN-gel over tail vein QF. The nasal QF-SLN-gel had stable and good brain delivery and could ameliorate the damages in rat model of schizophrenia induced by (+)-MK-801. PMID:26770349

Irradiation Sterilized Gelatin-Water-Glycerol Ternary Gel as an Injectable Carrier for Bone Tissue Engineering.

PubMed

Zhao, Yantao; Han, Liwei; Yan, Jun; Li, Zhonghai; Wang, Fuli; Xia, Yang; Hou, Shuxun; Zhong, Hongbin; Zhang, Feimin; Gu, Ning

2017-01-01

Injectable gelatin gels offer an attractive option for filling bone defects. The challenge is to fabricate gelatin gels with optimal gelation properties, which can be irradiation sterilized. Here, a gelatin-water-glycerol (GWG) gel is reported for use as a broad-spectrum injectable carrier. This ternary gel is high in glycerol and low in water, and remains stable after gamma irradiation at doses (25 kGy). As an injectable gel, it remains a viscous solution at gelatin concentrations ≤2.0%, at room temperature. Its storage modulus increases dramatically and eventually exceeds the loss modulus around 46-50 °C, indicating a transition from a liquid-like state to an elastic gel-like state. This ternary gel ranges significantly in terms of storage modulus (12-1700 Pa) while demonstrating a narrow pH range (5.58-5.66), depending on the gelatin concentration. Therefore, it can be loaded with a variety of materials. It is highly cytocompatible compared with saline in vivo and culture media in vitro. When loaded with demineralized bone matrix, the composites show favorable injectability, and excellent osteogenesis performance, after irradiation. These features can be attributed to high hydrophilicity and fast degradability. These findings justify that this ternary gel is promising as an irradiation-sterilized and universal injectable delivery system. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Insights into gelation kinetics and gel front migration in cation-induced polysaccharide hydrogels by viscoelastic and turbidity measurements: Effect of the nature of divalent cations.

PubMed

Huynh, Uyen T D; Chambin, Odile; du Poset, Aline Maire; Assifaoui, Ali

2018-06-15

Polysaccharide-based hydrogels were prepared by the diffusion of various divalent cations (X 2+ ) into the polygalacturonate (polyGal) solution through a dialysis membrane. The diffusion of various divalent cations (Mg 2+ , Ca 2+ , Zn 2+ and Ba 2+ ) was investigated. The polyGal gel growth was studied as a function of the initial cation concentration by both viscoelastic and turbidity measurements. We have demonstrated for the first time that the determination of the spatiotemporal variation of turbidity during the gelation process allowed to study the gel front migration. For Ca-polyGal, Zn-polyGal and Ba-polyGal, the gel front migration was characterized by the presence of a peak at the sol/gel interface. This peak was not observed in the case of Mg-polyGal where the gel was not formed. The apparent diffusion coefficient of the gel front (D app ) which was calculated from the evolution of this peak increased when the initial cation concentration was increased. Moreover, we have suggested a gelation mechanism based on the presence of a threshold molar ratio R* (=[X 2+ ]/[Galacturonic unit]) in which some point-like crosslinks are precursors of the formation of dimers and multimers inducing the contraction of the gel and thus the formation of the gel front. Copyright © 2018 Elsevier Ltd. All rights reserved.

Gel-expanded to gel-condensed transition in neurofilament networks revealed by direct force measurements

NASA Astrophysics Data System (ADS)

Beck, Roy; Deek, Joanna; Jones, Jayna B.; Safinya, Cyrus R.

2010-01-01

Neurofilaments (NF)-the principal cytoskeletal constituent of myelinated axons in vertebrates-consist of three molecular-weight subunit proteins NF-L (low), NF-M (medium) and NF-H (high), assembled to form mature filaments with protruding unstructured C-terminus side arms. Liquid-crystal gel networks of side-arm-mediated neurofilament assemblies have a key role in the mechanical stability of neuronal processes. Disruptions of the neurofilament network, owing to neurofilament over-accumulation or incorrect side-arm interactions, are a hallmark of motor-neuron diseases including amyotrophic lateral sclerosis. Using synchrotron X-ray scattering, we report on a direct measurement of forces in reconstituted neurofilament gels under osmotic pressure (P). With increasing pressure near physiological salt and average phosphorylation conditions, NF-LMH, comprising the three subunits near in vivo composition, or NF-LH gels, undergo for P>Pc~10kPa, an abrupt non-reversible gel-expanded to gel-condensed transition. The transition indicates side-arm-mediated attractions between neurofilaments consistent with an electrostatic model of interpenetrating chains. In contrast, NF-LM gels remain in a collapsed state for PPc. These findings, which delineate the distinct roles of NF-M and NF-H in regulating neurofilament interactions, shed light on possible mechanisms for disruptions of optimal mechanical network properties.

Role of amino acids and their Maillard mixtures with ribose in the biosilicification process

NASA Astrophysics Data System (ADS)

Kolb, Vera M.; Liesch, Patrick J.

2006-08-01

Mode of preservation of organic materials on early Earth, Mars or other extraterrestrial objects, and during the space transport on objects such as meteors, is one of the NASA's interests. This is especially true for the bio-organic materials, which could indicate life, past or present. Finding of such materials preserved in some ancient rocks, for example, could be interpreted as a biosignature. We have developed an experimental model for silicification, in which we have synthesized silica gels by reacting sodium silicate solution with various amino acids and with their mixtures with sugars, so-called Maillard mixtures. Our results indicate that these organic materials cause rapid and massive polymerization of silica. Such process may encrust organics or small organisms and thus preserve them. We have studied the gels we synthesized by the infrared (IR) spectroscopic method, and have detected small amount of the organic material in the silica gel. The gels were distinct in each case and have aged differently. In some cases, gel-sol-gel transformations were observed, which may be important for transport of both gels and the organics under prebiotic conditions. The gels obtained from the Maillard mixtures differ from those from the amino acids. Deuteration of the gels was performed in an attempt to resolve the bands in the Si-O-Si and Si-O-C region.

Pharmacokinetics of 2 dapivirine vaginal microbicide gels and their safety vs. Hydroxyethyl cellulose-based universal placebo gel.

PubMed

Nel, Annalene M; Smythe, Shanique C; Habibi, Sepideh; Kaptur, Paulina E; Romano, Joseph W

2010-10-01

Dapivirine, a nonnucleoside reverse transcriptase inhibitor, is in development as a microbicide for the protection of women against HIV infection. A randomized, double-blind, phase 1 trial was conducted in 36 healthy HIV-negative women to compare the pharmacokinetics of 2 dapivirine vaginal gel formulations (0.05% each) and their safety with the hydroxyethyl cellulose-based universal placebo gel. Gel was self-administered once daily for a total of 11 days. Blood and vaginal fluid samples were collected sequentially over 24 days for pharmacokinetic analysis. Safety was evaluated by pelvic examination, colposcopy, adverse events, and clinical laboratory assessments. Adverse event profiles were similar for the 3 gels. Most events were mild and not related to study gel. Headache and vaginal hemorrhage (any vaginal bleeding) were most common. Plasma concentrations of dapivirine did not exceed 1.1 ng/mL. Steady-state conditions were reached within approximately 10 days. Dapivirine concentrations in vaginal fluids were slightly higher for Gel 4789, but Cmax values on days 1 and 14 were not significantly different. Terminal half-life was 72-73 hours in plasma and 15-17 hours in vaginal fluids. Both formulations of dapivirine gel were safe and well tolerated. Dapivirine was delivered to the lower genital tract at concentrations at least 5 logs greater than in vitro inhibitory concentrations.

In-vitro activity of sodium-hypochlorite gel on bacteria associated with periodontitis.

PubMed

Jurczyk, Karolina; Nietzsche, Sandor; Ender, Claudia; Sculean, Anton; Eick, Sigrun

2016-11-01

The aim of the present study was to assess the antimicrobial activity of a sodium hypochlorite formulation including its components against bacteria associated with periodontal disease. Sodium hypochlorite formulation (NaOCl gel), its components sodium hypochlorite (NaOCl), and the activating vehicle were compared with 0.1 % chlorhexidine digluconate (CHX) solution. The antimicrobial activity was proven by determination of minimal inhibitory concentrations (MIC), minimal bactericidal concentrations, and killing assays. Furthermore, the influence on formation as well as on a 4-day-old 6-species biofilm was tested. Except for one strain (Parvimonas micra ATCC 33270 in case of NaOCl gel), the MICs both of the CHX solution and NaOCl gel did not exceed 10 % of the formulations' concentration. In general, MICs of the NaOCl gel were equal as of the CHX solution against Gram-negatives but higher against Gram-positive bacteria. CHX but not NaOCl gel clearly inhibited biofilm formation; however, the activity of NaOCl gel was more remarkable on a 4-day-old biofilm. NaOCl killed bacteria in the biofilm and interfered with the matrix. The NaOCl gel acts antimicrobial in particular against Gram-negative species associated with periodontitis. Moreover, its component NaOCl hypochlorite is able to alter biofilm matrices. The NaOCl gel may represent a potential alternative for adjunctive topical antimicrobial treatment in periodontitis.

A chitosan/beta-glycerophosphate thermo-sensitive gel for the delivery of ellagic acid for the treatment of brain cancer.

PubMed

Kim, Sungwoo; Nishimoto, Satoru K; Bumgardner, Joel D; Haggard, Warren O; Gaber, M Waleed; Yang, Yunzhi

2010-05-01

We report here the development of a chitosan/beta-glycerophosphate(Ch/beta-GP) thermo-sensitive gel to deliver ellagic acid (EA) for cancer treatment. The properties of the Ch/beta-GP gels were characterized regarding chemical structure, surface morphology, and viscoelasticity. In vitro EA release rate from the EA loaded Ch/beta-GP gel and chitosan degradation rate were investigated. The anti-tumor effect of the EA loaded Ch/beta-GP gel on brain cancer cells (human U87 glioblastomas and rat C6 glioma cells) was evaluated by examining cell viability. Cell number and activity were monitored by the MTS assay. The Ch/beta-GP solution formed a heat-induced gel at body temperature, and the gelation temperature and time were affected by the final pH of the Ch/beta-GP solution. The lysozyme increased the EA release rate by 2.5 times higher than that in the absence of lysozyme. Dialyzed chitosan solution with final pH 6.3 greatly reduced the beta-GP needed for gelation, thereby significantly improving the biocompatibility of gel (p < 0.001). The chitosan gels containing 1% (w/v) of ellagic acid significantly reduced viability of U87 cells and C6 cells compared with the chitosan gels at 3 days incubation (p < 0.01, and p < 0.001, respectively). Copyright 2010 Elsevier Ltd. All rights reserved.

Formulation and method for preparing gels comprising hydrous hafnium oxide

DOEpatents

Collins, Jack L; Hunt, Rodney D; Montgomery, Frederick C

2013-08-06

Formulations useful for preparing hydrous hafnium oxide gels contain a metal salt including hafnium, an acid, an organic base, and a complexing agent. Methods for preparing gels containing hydrous hafnium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including hafnium, an acid, an organic base, and a complexing agent.

Sol-gel modification of wood substrates to retard weathering

Treesearch

Mandla A Tshabalala; Sam Williams

2008-01-01

Wood specimens were treated with sol-gel systems based on metalorganic precursors of silicon (Si), iron (Fe), zirconium (Zr), and titanium (Ti). The effect of these sol-gel systems on weathering properties of wood was investigated. These sol-gel systems were found to have a positive effect on surface color stability and water vapor resistance of the specimens. Under...

Stabilized aqueous gels and uses thereof

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swanson, B.L.

1978-08-29

New improved aqueous gels, and methods of using same in contacting subterranean formations, are provided. The gels are prepared by gelling an aqueous brine having incorporated therein a water-soluble cellulose ether such as a carboxymethylcellulose (CMC), and are rendered more stable to decomposition by incorporating a sulfoalkylated tannin stabilizing agent, such as a sulfomethylated quebracho (SMQ), in the gel during the preparation thereof.

Intraoperative use of a reflective blanket (Sirius rescue sheet) for temperature management in dogs less than 10 kg.

PubMed

Tünsmeyer, J; Bojarski, I; Nolte, I; Kramer, S

2009-07-01

To compare the effects of the Sirius rescue sheet with gel pads versus gel pads alone on intraoperative body temperature in dogs less than 10 kg. Forty small breed dogs undergoing elective surgical procedures were randomly assigned to two groups. One group was intraoperatively laid on warmed gel pads, and the other group was additionally wrapped in a Sirius rescue sheet. Oesophageal body temperature was determined every 10 minutes and compared between groups. Temperature of gel pads was measured preoperatively and postoperatively to compare heat loss of the gel pads between groups. The body temperature of dogs wrapped with the Sirius rescue sheet increased intraoperatively. In dogs just lying on warmed gel pads, a decrease in mean body temperature was revealed and mean body temperatures differed between groups after 40 minutes. Extent of heat loss from the gel pads did not differ between the groups. The Sirius rescue sheet, used in addition to warmed gel pads, led to higher intraoperative body temperatures in small breed dogs undergoing surgical procedures to the extremities and the head. The cost-effectiveness and ease of handling make this a useful addition to clinical practice.

PREFACE: Third International Conference on Radiotherapy Gel Dosimetry

NASA Astrophysics Data System (ADS)

DeDeene, Yves; Baldock, Clive

2004-01-01

Gel dosimetry is not merely another dosimetry technique. Gel dosimeters are integrating dosimeters that enable dose verification in three dimensions. The application of a 3D dosimetry technique in the clinic would give a real push to the implementation of advanced high-precision radiotherapy technologies in many institutes. It can be expected that with the recent developments in the field towards more user-friendly gel systems and imaging modalities, gel dosimetry will become a vital link in the chain of high-precision radiation cancer therapy in the near future. Many researchers all over the world have contributed to the emerging technology of gel dosimetry. The research field of gel dosimetry is recognized to be very broad from polymer and analytical chemistry and material research to imaging technologies. The DOSGEL conferences in the past have proven to be an important forum at which material scientists, chemists, medical physicists, magnetic resonance imaging and radiation specialists brought together a critical mass of thoughts, findings and considerations. DOSGEL 2004 has been endorsed by many international, supra-national and national medical physics organizations and publishers. These proceedings contain 51 papers that cover various aspects of gel dosimetry.

Effect of storage and drying temperature on the gelation behavior and structural characteristics of sericin.

PubMed

Jo, Yoon Nam; Park, Byung-Dae; Um, In Chul

2015-11-01

Owing to unique properties, including the wound healing effect, sericin gel and films have attracted significant attention in the biomedical and cosmetic fields. The structural characteristics and properties of sericin gels and films are especially important owing to their effect on the performance of sericin in biomedical and cosmetic applications. In the present study, the effect of temperature on the gelation behavior, gel disruption, and sol-gel transition of sericin was examined using rheometry. In addition, the effect of the drying temperature on the structural characteristics of the sericin film was determined via Fourier transform infrared (FTIR) spectroscopy. The strength of the sericin gel increased and the gelation process was prolonged with decreasing storage temperatures. FTIR and differential scanning calorimetry (DSC) results also revealed that the crystallinity and the thermal decomposition temperature of the sericin film increased with decreasing drying temperature. The sericin gels were disrupted at a storage time of 40min when they were stored at temperatures higher than 50°C, and the corresponding gel strength decreased with increasing temperature. Furthermore, the thermo-reversible nature of gel-sol transition of sericin was confirmed by rheological and FTIR measurements. Copyright © 2015 Elsevier B.V. All rights reserved.

Nanoscale supramolecular ordering in gel-surfactant complexes: Sodium alkyl sulfates in poly(diallyldimethylammonium chloride)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokolov, E.L.; Yeh, F.; Khokhlov, A.

1996-12-25

Studies of slightly cross-linked polycationic gels interacting with anionic surfactants have been performed by using random copolymers of poly(diallyldimethylammonium chloride) (PDADMACl) and polyacrylamide (PAAm) with varying content of PDADMACl and degree of cross-linking. Gel samples which had been fully swollen in water were placed in aqueous solutions of sodium alkyl sulfates (octyl(SOS), decyl-(SDCS), dodecyl (SDS), tetradecyl (STS), and hexyl (SHS) sulfates). The degree of the sample volume contraction depends on the PDADMACl content. The collapsed gel-surfactant complexes were studied using synchrotron small-angle X-ray scattering. All studied samples containing PDADMACl exhibited pronounced supramolecular nanostructures. The gel-SDCS complex exhibited a cubic structuremore » with a periodicity (7.75 nm) of approximately 4 times the surfactant molecular length, while the gel-SDS, gel-STS, and gel-SHS complexes showed hexagonal supramolecular ordering with a periodicity of approximately 2 times the surfactant molecular length. The d spacing of the longest periodicity in the complexes was dependent on the PDADMACl content and the surfactant. The d spacing generally increased with decreasing PDADMACl (charge) content and increasing number of carbon atoms in the surfactant alkyl chain. 20 refs., 11 figs., 5 tabs.« less

Human platelet gel supernatant inactivates opportunistic wound pathogens on skin.

PubMed

Edelblute, Chelsea M; Donate, Amy L; Hargrave, Barbara Y; Heller, Loree C

2015-01-01

Activation of human platelets produces a gel-like substance referred to as platelet rich plasma or platelet gel. Platelet gel is used clinically to promote wound healing; it also exhibits antimicrobial properties that may aid in the healing of infected wounds. The purpose of this study was to quantify the efficacy of human platelet gel against the opportunistic bacterial wound pathogens Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus on skin. These opportunistic pathogens may exhibit extensive antibiotic resistance, necessitating the development of alternative treatment options. The antimicrobial efficacy of platelet gel supernatants was quantified using an in vitro broth dilution assay, an ex vivo inoculated skin assay, and in an in vivo skin decontamination assay. Human platelet gel supernatants were highly bactericidal against A. baumannii and moderately but significantly bactericidal against S. aureus in vitro and in the ex vivo skin model. P. aeruginosa was not inactivated in vitro; a low but significant inactivation level was observed ex vivo. These supernatants were quite effective at inactivating a model organism on skin in vivo. These results suggest application of platelet gel has potential clinical applicability, not only in the acceleration of wound healing, but also against relevant bacteria causing wound infections.

Tolerability of clindamycin/tretinoin gel vs. tretinoin microsphere gel and adapalene gel.

PubMed

Leyden, James; Wortzman, Mitchell; Baldwin, Edward K

2009-04-01

Newer agents and formulations seek to improve the tolerability of topical retinoid therapy. Recently, a gel containing crystalline clindamycin 1.2% and tretinoin 0.025% (CLIN/RA) was approved by the U.S. Food and Drug Administration (FDA) for the treatment of treating mild-to-moderate acne. This single-center, randomized, evaluator-blind phase 1 study compared the tolerability of CLIN/RA to 0.1% tretinoin gel or 0.1% adapalene gel. Forty-five patients applied CLIN/RA once daily to one side of their face every day for 21 days. Patients were randomized to either tretinoin 0.1% (n = 23) or adapalene 0.1% (n = 22) on the contralateral side. A clinical evaluator assessed degree of erythema and scaling; patients provided subjective evaluations of burning, stinging, and itching. CLIN/RA was significantly better tolerated than was 0.1% tretinoin gel, as evidenced by significantly reduced erythema (P < 0.04), scaling (P < 0.03), itching (P < 0.02), burning (P < 0.03) and stinging (P < 0.04). A trend for greater erythema, scaling, and subjective discomfort for 0.1% adapalene gel compared to CLIN/RA was also evident.

Viscoelasticity measurement of gel formed at the liquid-liquid reactive interfaces

NASA Astrophysics Data System (ADS)

Ujiie, Tomohiro

2012-11-01

We have experimentally studied a reacting liquid flow with gel formation by using viscous fingering (VF) as a flow field. Here, two systems were employed. In one system, sodium polyacrylate (SPA) solution and ferric ion solution were used as the more and less viscous liquids, respectively. In another system, xthantan gum (XG) solution and the ferric ion solution were used as the more and less viscous liquids, respectively. We showed that influence of gel formation on VF were qualitatively different in these two systems. We consider that the difference in the two systems will be caused by the difference in the properties of the gels. Therefore, we have measured the rheological properties of the gels by means of a rheometer. In the present study, viscoelasticity measurement was performed by two methods. One is the method which uses Double Wall Ring sensor (TA instrument) and another is the method using parallel plate. In both viscoelasticity measurements, the behavior of the formed gel was qualitatively consistent. We have found that the gel in the SPA system shows viscoelastic fluid like behavior. Moreover, we have found that the gel in the XG system shows solid like behavior.

[Azelaic acid 15% gel in the treatment of acne vulgaris. Combined results of two double-blind clinical comparative studies].

PubMed

Gollnick, Harald P M; Graupe, Klaus; Zaumseil, Rolf-Peter

2004-10-01

Topical measures are still the mainstay in the therapy of mild-to-moderate acne vulgaris. Azelaic acid 20% in a cream formulation has been established as an efficacious and safe topical drug for 15 years. A new non-alcoholic hydrogel formulation containing 15% azelaic acid was clinically tested against two standard drugs--5% benzoyl peroxide (BPO) and 1% clindamycin. In two independent, randomized, blinded comparative trials 15% azelaic acid gel was clinically tested against 5% benzoyl peroxide (BPO) gel in 351 patients and against 1% clindamycin gel in 229 patients. The drugs were applied b.i.d. for 4 months. Azelaic acid 15% gel proved to be as effective as BPO and clindamycin with median % reduction of the inflamed lesion (papules and pustules) of 70%, and 71% respectively. The azelaic acid gel was well-tolerated, the side effects (local burning and irritation) were distinctly less than with BPO but more pronounced than with clindamycin. Despite these side effects, the treatment was well-accepted by the majority of patients. Azelaic acid gel is an effective topical monotherapy for mild-to-moderate acne vulgaris; its new gel form is an enrichment of acne therapy.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takeshita, Kenji

A mathematical model to predict the extraction behavior of metal ion between a polymer gel and an aqueous solution was proposed. It consists of the Flory-Huggins formula for evaluating thermodynamically the physico-chemical properties of polymer gel, the modified Stokes-Einstein equation to evaluate the mass transfer rate of metal ion into polymer gel and the equation to evaluate the extraction equilibrium. The extraction of lanthanide elements, Nd(III), Sm(III) and Gd(III), from an aqueous solution containing nitrate ion was carried out by the use of SDB (styrene-divinylbenzene copolymer) gel swollen with a bidentate organophosphorus compound, CMP (dihexyl-N,N-diethylcarbamoylmethylpohosphonate). The binary extraction and themore » effect of the crosslinking degree of SDB gel on the extraction rate were examined. These experimental results were in agreement with the predictions calculated by the proposed model. It was confirmed that the extraction behavior of lanthanide ions into the SDB gel was predicted accurately, when the physico-chemical properties of SDB gel, such as the affinity between SDB and CMP ({chi}) and the crosslinking degree ({nu}{sub e}), and a coefficient defined in the modified Stokes-Einstein equation (K{sub 0}) were known. This model is available as a tool to design an extraction chromatographic process using polymer gel.« less

Konjac flour improved textural and water retention properties of transglutaminase-mediated, heat-induced porcine myofibrillar protein gel: Effect of salt level and transglutaminase incubation.

PubMed

Chin, Koo B; Go, Mi Y; Xiong, Youling L

2009-03-01

Functional properties of heat-induced gels prepared from microbial transglutaminase (TG)-treated porcine myofibrillar protein (MP) containing sodium caseinate with or without konjac flour (KF) under various salt concentrations (0.1, 0.3 and 0.6MNaCl) were evaluated. The mixed MP gels with KF exhibited improved cooking yields at all salt concentrations. TG treatment greatly enhanced gel strength and elasticity (storage modulus, G') at 0.6M NaCl, but not at lower salt concentrations. The combination of KF and TG improved the gel strength at 0.1 and 0.3M NaCl and G' at all salt concentrations, when compared with non-TG controls. Incubation of MP suspensions (sols) with TG promoted the disappearance of myosin heavy chain and the production of polymers. The TG-treated MP mixed gels had a compact structure, compared to those without TG, and the KF incorporation modified the gel matrix and increased its water-holding capacity. Results from differential scanning calorimetry suggested possible interactions of MP with KF, which may explain the changes in the microstructure of the heat-induced gels.

Highly Reactive Thiol-Norbornene Photo-Click Hydrogels: Toward Improved Processability.

PubMed

Van Hoorick, Jasper; Gruber, Peter; Markovic, Marica; Rollot, Mélanie; Graulus, Geert-Jan; Vagenende, Maxime; Tromayer, Maximilian; Van Erps, Jürgen; Thienpont, Hugo; Martins, José C; Baudis, Stefan; Ovsianikov, Aleksandr; Dubruel, Peter; Van Vlierberghe, Sandra

2018-06-10

In the present work, gelatin type B is modified with highly reactive norbornene functionalities (Gel-NB) following a one-pot synthesis approach to enable subsequent thiol-ene photo-click crosslinking. The modification strategy displays close control over the amount of introduced functionalities. Additionally, Gel-NB exhibits considerably improved processing capabilities in terms of two-photon polymerization when benchmarked to earlier-reported crosslinkable gelatin derivatives (e.g., gelatin-methacrylamide (Gel-MOD) and gelatin-methacrylamide-aminoethylmethacrylate (Gel-MOD-AEMA)). The improvement is especially apparent in terms of minimally required laser power (20 mW vs ≥60 mW (Gel-MOD) vs ≥40 mW (Gel-MOD-AEMA) at 100 mm s -1 scan speed) and processable concentration range (≥5 w/v% vs ≥10 w/v% (Gel-MOD/Gel-MOD-AEMA)). Furthermore, the proposed functionalization scheme maintains the excellent biocompatibility and cell interactivity of gelatin. Additionally, the norbornene functionalities have potential for straightforward postprocessing "thiol-ene" surface grafting of active molecules. As a consequence, a very promising material toward tissue engineering applications and more specifically, biofabrication, is presented. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Coordination polymer gels with important environmental and biological applications.

PubMed

Jung, Jong Hwa; Lee, Ji Ha; Silverman, Julian R; John, George

2013-02-07

Coordination Polymer Gels (CPGs) constitute a subset of solid-like metal ion and bridging organic ligand structures (similar to metal-organic frameworks) that form multi-dimensional networks through a trapped solvent as a result of non-covalent interactions. While physical properties of these gels are similar to conventional high molecular weight organic polymer gels, coordination polymer gel systems are often fully reversible and can be assembled and disassembled in the presence of additional energy (heat, sonication, shaking) to give a solution of solvated gelators. Compared to gels resulting from purely organic self-assembled low molecular weight gelators, metal ions incorporated into the fibrilar networks spanning the bulk solvent can impart CPGs with added functionalities. The solid/liquid nature of the gels allows for species to migrate through the gel system and interact with metals, ligands, and the solvent. Chemosensing, catalysis, fluorescence, and drug-delivery applications are some of the many potential uses for these dynamic systems, taking advantage of the metal ion's coordination, the organic polydentate ligand's orientation and functionality, or a combination of these properties. By fine tuning these systems through metal ion and ligand selection and by directing self-assembly with external stimuli the rational synthesis of practical systems can be envisaged.

Effects of heating and calcium and phosphate mineral supplementation on the physical properties of rennet-induced coagulation of camel and cow milk gels.

PubMed

Kamal, Mohammad; Foukani, Mohammed; Karoui, Romdhane

2017-05-01

The physical properties of rennet-induced coagulation of preheated camel and cow milk gels (50 and 70 °C for 10 min) enriched with calcium chloride (CaCl2) and hydrogen phosphate dihydrate (Na2HPO42H2O) were evaluated using the dynamic low amplitude oscillatory shear analysis. The storage modulus (G') and loss modulus (G") of camel milk gels showed significant (P < 0·05) lower values than those of cow milk gels. The preheating of camel milk at 50 °C affected negatively the gelation properties, while the preheating at 70 °C prevented the formation of rennet-induced milk gels. No effect was observed on the gelation properties of cow milk gels. The CaCl2 added at 10 and 20 mM to preheated camel and cow milk reduced significantly (P < 0·05) the gelation time and increased the gel firmness. In contrast, Na2HPO42H2O added at 10 and 20 mM induced the formation of weak gels for preheated camel and cow milk at 50 °C, and even no gelation for preheated camel milk at 70 °C.

Effect of rice variety on the physicochemical properties of the modified rice powders and their derived mucoadhesive gels.

PubMed

Okonogi, Siriporn; Kaewpinta, Adchareeya; Khongkhunthian, Sakornrat; Yotsawimonwat, Songwut

2015-06-01

In the present study; the glutinous Niaw Sanpatong (NSP) and Niaw Koko-6 (NKK), and the non-glutinous Jasmine (JM) and Saohai (SH) were chemically modified. The difference of these rice varieties on the physicochemical characteristics of the modified rice powders and the properties of the derived gels were evaluated. X-ray diffractometer was used for crystalline structure investigation of the rice powders and gels. A parallel plate rheometer was used to measure the rheological property of the gels. It was found that the non-glutinous varieties produced gels with higher mucoadhesive properties than the glutinous rice. Rheological behavior of JM and SH gels was pseudoplastic without yield value whereas that of NSP and NKK gels was plastic with the yield values of 1077.4 ± 185.9 and 536.1 ± 45.8 millipascals-second (mPas), respectively. These different properties are considered to be due to the amylose content in different rice variety. The results suggest that the non-glutinous rice varieties with high amylose content are the most suitable for preparing gels as local delivery systems via the mucosal membrane.

A zwitterionic gel electrolyte for efficient solid-state supercapacitors

PubMed Central

Peng, Xu; Liu, Huili; Yin, Qin; Wu, Junchi; Chen, Pengzuo; Zhang, Guangzhao; Liu, Guangming; Wu, Changzheng; Xie, Yi

2016-01-01

Gel electrolytes have attracted increasing attention for solid-state supercapacitors. An ideal gel electrolyte usually requires a combination of advantages of high ion migration rate, reasonable mechanical strength and robust water retention ability at the solid state for ensuring excellent work durability. Here we report a zwitterionic gel electrolyte that successfully brings the synergic advantages of robust water retention ability and ion migration channels, manifesting in superior electrochemical performance. When applying the zwitterionic gel electrolyte, our graphene-based solid-state supercapacitor reaches a volume capacitance of 300.8 F cm−3 at 0.8 A cm−3 with a rate capacity of only 14.9% capacitance loss as the current density increases from 0.8 to 20 A cm−3, representing the best value among the previously reported graphene-based solid-state supercapacitors, to the best of our knowledge. We anticipate that zwitterionic gel electrolyte may be developed as a gel electrolyte in solid-state supercapacitors. PMID:27225484

Thermoreversible gel formulation containing sodium lauryl sulfate as a potential contraceptive device.

PubMed

Haineault, Caroline; Gourde, Pierrette; Perron, Sylvie; Désormeaux, André; Piret, Jocelyne; Omar, Rabeea F; Tremblay, Roland R; Bergeron, Michel G

2003-08-01

The contraceptive properties of a gel formulation containing sodium lauryl sulfate were investigated in both in vitro and in vivo models. Results showed that sodium lauryl sulfate inhibited, in a concentration-dependent manner, the activity of sheep testicular hyaluronidase. Sodium lauryl sulfate also completely inhibited human sperm motility as evaluated by the 30-sec Sander-Cramer test. The acid-buffering capacity of gel formulations containing sodium lauryl sulfate increased with the molarity of the citrate buffers used for their preparations. Furthermore, experiments in which semen was mixed with undiluted gel formulations in different proportions confirmed their physiologically relevant buffering capacity. Intravaginal application of the gel formulation containing sodium lauryl sulfate to rabbits before their artificial insemination with freshly ejaculated semen completely prevented egg fertilization. The gel formulation containing sodium lauryl sulfate was fully compatible with nonlubricated latex condoms. Taken together, these results suggest that the gel formulation containing sodium lauryl sulfate could represent a potential candidate for use as a topical vaginal spermicidal formulation to provide fertility control in women.

Effect of belimbing wuluh (averrhoa bilimbi l.) extract gel exposure duration to surface roughness of enamel

NASA Astrophysics Data System (ADS)

Karima, F.; Eriwati, Y. K.; Triaminingsih, S.

2017-08-01

The purpose of this study was to analyze the effect of Belimbing Wuluh Gel Extract to surface roughness of enamel. Thirty-six premolars teeth that divided into 4 groups (n = 9), were exposed to 37% phosphoric acid gel (pH = 1) for 15 seconds as a control group, and belimbing wuluh extract gel with a concentration of 80% (pH = 1.8) for 15 seconds, 20 seconds, and 25 seconds as the treatment groups. The statistical analysis of paired and unpaired T-test shows that all treatment groups experienced a significant change (p <0.05). The greatest changes in surface roughness of enamel occurred after exposed by belimbing extract gel with an exposure duration of 25 seconds, but the roughness of 37% phosphoric acid gel is still greater. There was a correlation between roughness on the surface of tooth enamel with prolonged exposure belimbing wuluh extract gel with a concentration of 80%.

Actuator device utilizing a conductive polymer gel

DOEpatents

Chinn, Douglas A.; Irvin, David J.

2004-02-03

A valve actuator based on a conductive polymer gel is disclosed. A nonconductive housing is provided having two separate chambers separated by a porous frit. The conductive polymer is held in one chamber and an electrolyte solution, used as a source of charged ions, is held in the second chamber. The ends of the housing a sealed with a flexible elastomer. The polymer gel is further provide with electrodes with which to apply an electrical potential across the gel in order to initiate an oxidation reaction which in turn drives anions across the porous frit and into the polymer gel, swelling the volume of the gel and simultaneously contracting the volume of the electrolyte solution. Because the two end chambers are sealed the flexible elastomer expands or contracts with the chamber volume change. By manipulating the potential across the gel the motion of the elastomer can be controlled to act as a "gate" to open or close a fluid channel and thereby control flow through that channel.

Sol-gel Technology and Advanced Electrochemical Energy Storage Materials

NASA Technical Reports Server (NTRS)

Chu, Chung-tse; Zheng, Haixing

1996-01-01

Advanced materials play an important role in the development of electrochemical energy devices such as batteries, fuel cells, and electrochemical capacitors. The sol-gel process is a versatile solution for use in the fabrication of ceramic materials with tailored stoichiometry, microstructure, and properties. This processing technique is particularly useful in producing porous materials with high surface area and low density, two of the most desirable characteristics for electrode materials. In addition,the porous surface of gels can be modified chemically to create tailored surface properties, and inorganic/organic micro-composites can be prepared for improved material performance device fabrication. Applications of several sol-gel derived electrode materials in different energy storage devices are illustrated in this paper. V2O5 gels are shown to be a promising cathode material for solid state lithium batteries. Carbon aerogels, amorphous RuO2 gels and sol-gel derived hafnium compounds have been studied as electrode materials for high energy density and high power density electrochemical capacitors.

Rheological and sensory properties of hydrophilic skin protection gels based on polyacrylates.

PubMed

Kulawik-Pióro, Agnieszka; Kurpiewska, Joanna; Kułaszka, Agnieszka

2018-03-01

With the current increases in occupational skin diseases, literature data attesting the decreasing efficiency of barrier creams with respect to the manufacturer's declarations and legal regulations granting skin protection gels for employees, research is required to analyse and evaluate the recipes used for hydrophilic skin protection gels based on polyacrylates. This study investigated the rheological properties, pH and sensory perception of hydrophilic barrier gels based on polyacrylates. The acrylic acid derivatives used were good thickeners, and helped to form transparent gels of adequate durability. They could be used to create hydrophilic films on the surface of the skin to protect it against hydrophobic substances. A correlation was shown between the results of the rheological properties and the barrier properties of the gels. This confirms the possibility of monitoring the quality of the gels at the stage of recipe development. Polyacrylates are viable for use in industry to produce hydrophilic barrier creams suitable for skin protection.

Effect of waxy rice flour and cassava starch on freeze-thaw stability of rice starch gels.

PubMed

Charoenrein, Sanguansri; Preechathammawong, Nutsuda

2012-10-01

Repeatedly frozen and thawed rice starch gel affects quality. This study investigated how incorporating waxy rice flour (WF) and cassava starch (CS) in rice starch gel affects factors used to measure quality. When rice starch gels containing 0-2% WF and CS were subjected to 5 freeze-thaw cycles, both WF and CS reduced the syneresis in first few cycles. However CS was more effective in reducing syneresis than WF. The different composite arrangement of rice starch with WF or CS caused different mechanisms associated with the rice starch gel retardation of retrogradation, reduced the spongy structure and lowered syneresis. Both swollen granules of rice starch and CS caused an increase in the hardness of the unfrozen and freeze-thawed starch gel while highly swollen WF granules caused softer gels. These results suggested that WF and CS were effective in preserving quality in frozen rice starch based products. Copyright © 2012 Elsevier Ltd. All rights reserved.

Controlled release of vancomycin from thin sol-gel films on implant surfaces successfully controls osteomyelitis.

PubMed

Adams, Christopher S; Antoci, Valentin; Harrison, Gerald; Patal, Payal; Freeman, Terry A; Shapiro, Irving M; Parvizi, Javad; Hickok, Noreen J; Radin, Shula; Ducheyne, Paul

2009-06-01

Peri-prosthetic infection remains a serious complication of joint replacement surgery. Herein, we demonstrate that a vancomycin-containing sol-gel film on Ti alloy rods can successfully treat bacterial infections in an animal model. The vancomycin-containing sol-gel films exhibited predictable release kinetics, while significantly inhibiting S. aureus adhesion. When evaluated in a rat osteomyelitis model, microbiological analysis indicated that the vancomycin-containing sol-gel film caused a profound decrease in S. aureus number. Radiologically, while the control side showed extensive bone degradation, including abscesses and an extensive periosteal reaction, rods coated with the vancomycin-containing sol-gel film resulted in minimal signs of infection. MicroCT analysis confirmed the radiological results, while demonstrating that the vancomycin-containing sol-gel film significantly protected dense bone from resorption and minimized remodeling. These results clearly demonstrate that this novel thin sol-gel technology can be used for the targeted delivery of antibiotics for the treatment of periprosthetic as well as other bone infections. Copyright 2008 Orthopaedic Research Society

Glass shell manufacturing in space

NASA Technical Reports Server (NTRS)

Downs, R. L.; Ebner, M. A.; Nolen, R. L., Jr.

1981-01-01

Highly-uniform, hollow glass spheres (shells), which are used for inertial confinement fusion targets, were formed from metal-organic gel powder feedstock in a vertical furnace. As a result of the rapid pyrolysis caused by the furnace, the gel is transformed to a shell in five distinct stages: (a) surface closure of the porous gel; (b) generation of a closed-cell foam structure in the gel; (c) spheridization of the gel and further expansion of the foam; (d) coalescence of the closed-cell foam to a single-void shell; and (e) fining of the glass shell. The heat transfer from the furnace to the falling gel particle was modeled to determine the effective heating rate of the gel. The model predicts the temperature history for a particle as a function of mass, dimensions, specific heat, and absorptance as well as furnace temperature profile and thermal conductivity of the furnace gas. A model was developed that predicts the gravity-induced degradation of shell concentricity in falling molten shells as a function of shell characteristics and time.

Direct Force Measurements on Neurofilaments: Gel Expanded to Gel Condensed Transition

NASA Astrophysics Data System (ADS)

Beck, R.; Deek, J.; Jones, J. B.; Safinya, C. R.

2010-03-01

Neurofilaments (NFs)--the major cytoskeletal constituent of axons in vertebrates, consist of three subunit proteins assembled to form filaments with protruding unstructured C-terminus sidearms. Liquid crystal gel networks of sidearm-mediated NF assemblies play a key role in the mechanical while disruptions of this network, due to over-accumulation or incorrect sidearm interactions, are a hallmark of motor neuron diseases. Using synchrotron SAXS [1,2] and microscopy techniques [1,3] we report a direct force measurement of reconstituted NF-gels under osmotic pressure (P), which revealed the role of subunit sidearms on structure and interaction of NFs. With increasing P, near physiological condition, the gels undergo an abrupt nonreversible gel expanded to gel condensed transition that indicates sidearm-mediated attractions between NFs. This attraction is consistent with an electrostatic model of interpenetrating chains.[4pt] [1] J.B. Jones, C.R. Safinya, Biophys. J. 95, 823 (2008);[0pt] [2] R. Beck et al., Nature Mat. (2009) in press;[0pt] [3] H. Hess et al. Langmuir 24, 8397 (2008)

Neutron spin-echo studies on dynamic and static fluctuations in two types of poly(vinyl alcohol) gels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanaya, T.; Takahashi, N.; Nishida, K.

2005-01-01

We report neutron spin-echo measurements on two types of poly(vinyl alcohol) (PVA) gels. The first is PVA gel in a mixture of dimethyl sulfoxide (DMSO) and water with volume ratio 60/40, and the second is PVA gel in an aqueous borax solution. The observed normalized intermediate scattering functions I(Q,t)/I(Q,0) are very different between them. The former I(Q,t)/I(Q,0) shows a nondecaying component in addition to a fast decay, but the latter does not have the nondecaying one. This clearly indicates that the fluctuations in the former PVA gel consist of static and dynamic fluctuations whereas the latter PVA gel does includemore » only the dynamic fluctuations. The dynamic fluctuations of the former and latter gels have been analyzed in terms of a restricted motion in the network and Zimm motion, respectively, and the origins of these motions will be discussed.« less

Chemomechanical synchronization in heterogeneous self-oscillating gels

NASA Astrophysics Data System (ADS)

Yashin, Victor V.; Balazs, Anna C.

2008-04-01

Using computational modeling, we introduce patches of self-oscillating gels undergoing the Belousov-Zhabotinsky (BZ) reaction into a nonreactive polymer network and thereby demonstrate how these BZ gels can be harnessed to impart remarkable functionality to the entire system. By first focusing on two adjacent patches of BZ gels, we show that the patches’ oscillations can become synchronized in phase or out of phase, with the oscillation frequency depending on the synchronization mode and the spatial separation between these domains. We then apply these results to an array of five adjacent BZ patches and by varying the distance between these pieces, we dramatically alter the dynamical behavior of the patterned gel. For example, the sample can be made to exhibit a unidirectional traveling wave or display a concerted expansion and contraction, properties that are valuable for creating gel-based devices, such as micropumps and microactuators. The findings point to a “modular” design approach, which can impart different functionality simply by arranging identical pieces of BZ gels into distinct spatial arrangements within a polymer matrix.

Unusual multiscale mechanics of biomimetic nanoparticle hydrogels

DOE PAGES

Zhou, Yunlong; Damasceno, Pablo F.; Somashekar, Bagganahalli S.; ...

2018-01-12

Viscoelastic properties are central for gels and other materials. Simultaneously, high storage and loss moduli are difficult to attain due to their contrarian requirements to chemical structure. Biomimetic inorganic nanoparticles offer a promising toolbox for multiscale engineering of gel mechanics, but a conceptual framework for their molecular, nanoscale, mesoscale, and microscale engineering as viscoelastic materials is absent. Here we show nanoparticle gels with simultaneously high storage and loss moduli from CdTe nanoparticles. Viscoelastic figure of merit reaches 1.83 MPa exceeding that of comparable gels by 100–1000 times for glutathione-stabilized nanoparticles. The gels made from the smallest nanoparticles display the highestmore » stiffness, which was attributed to the drastic change of GSH configurations when nanoparticles decrease in size. A computational model accounting for the difference in nanoparticle interactions for variable GSH configurations describes the unusual trends of nanoparticle gel viscoelasticity. These observations are generalizable to other NP gels interconnected by supramolecular interactions and lead to materials with high-load bearing abilities and energy dissipation needed for multiple technologies.« less

Process for preparing energetic materials

DOEpatents

Simpson, Randall L [Livermore, CA; Lee, Ronald S [Livermore, CA; Tillotson, Thomas M [Tracy, CA; Hrubesh, Lawrence W [Pleasanton, CA; Swansiger, Rosalind W [Livermore, CA; Fox, Glenn A [Livermore, CA

2011-12-13

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

Large-scale single-chirality separation of single-wall carbon nanotubes by simple gel chromatography

PubMed Central

Liu, Huaping; Nishide, Daisuke; Tanaka, Takeshi; Kataura, Hiromichi

2011-01-01

Monostructured single-wall carbon nanotubes (SWCNTs) are important in both scientific research and electronic and biomedical applications; however, the bulk separation of SWCNTs into populations of single-chirality nanotubes remains challenging. Here we report a simple and effective method for the large-scale chirality separation of SWCNTs using a single-surfactant multicolumn gel chromatography method utilizing one surfactant and a series of vertically connected gel columns. This method is based on the structure-dependent interaction strength of SWCNTs with an allyl dextran-based gel. Overloading an SWCNT dispersion on the top column results in the adsorption sites of the column becoming fully occupied by the nanotubes that exhibit the strongest interaction with the gel. The unbound nanotubes flow through to the next column, and the nanotubes with the second strongest interaction with the gel are adsorbed in this stage. In this manner, 13 different (n, m) species were separated. Metallic SWCNTs were finally collected as unbound nanotubes because they exhibited the lowest interaction with the gel. PMID:21556063

Preparation, characterization, and in vitro gastrointestinal digestibility of oil-in-water emulsion-agar gels.

PubMed

Wang, Zheng; Neves, Marcos A; Kobayashi, Isao; Uemura, Kunihiko; Nakajima, Mitsutoshi

2013-01-01

Soybean oil-in-water (O/W) emulsion-agar gel samples were prepared and their digestibility evaluated by using an in vitro gastrointestinal digestion model. Emulsion-agar sols were obtained by mixing the prepared O/W emulsions with a 1.5 wt % agar solution at 60 °C, and their subsequent cooling at 5 °C for 1 h formed emulsion-agar gels. Their gel strength values increased with increasing degree of polymerization of the emulsifiers, and the relative gel strength increased in the case of droplets with an average diameter smaller than 700 nm. Flocculation and coalescence of the released emulsion droplets depended strongly on the emulsifier type; however, the emulsifier type hardly affected the ζ-potential of emulsion droplets released from the emulsion-agar gels during in vitro digestion. The total FFA content released from each emulsion towards the end of the digestion period was nearly twice that released from the emulsion-agar gel, indicating that gelation of the O/W emulsion may have delayed lipid hydrolysis.

PREPARATION AND PROPERTIES OF COMPOUND ARNEBIAE RADIX MICROEMULSION GEL

PubMed Central

Chen, Jing; He, Yanping; Gao, Ting; Zhang, Licheng; Zhao, Yuna

2017-01-01

Background: Compound Arnebiae radix oil has been clinically applied to treat burns and scalds for a long time. However, it is unstable and inconvenient to use. The aim of this study was to prepare a compound Arnebiae radix microemulsion gel for transdermal delivery system and evaluate its characteristics. Materials and Methods: Based on the solubility of Shikonin, the active component of Arnebiae radix and the results of phase studies, adequate ratio of each component in microemulsion was determined. The optimized microemulsion gel was prepared using Carbomer 940. The gels were characterized in terms of appearance, preliminary stability test and the content of Shikonin in the compound Arnebiae radix microemulsion gel with HPLC analysis. Results: The optimized conditions for preparing microemulsion were Tween-80, glycerin, isopropyl myristate (IPM) with the ratio of 6:3:2. The optimal microemulsion gel was obtained with Carbomer 940 (1.0%). Conclusion: The prepared compound Arnebiae radix microemulsion gel showed good stability over time. It is more convenience in application than the previous used formulations. PMID:28480438

PREPARATION AND PROPERTIES OF COMPOUND ARNEBIAE RADIX MICROEMULSION GEL.

PubMed

Chen, Jing; He, Yanping; Gao, Ting; Zhang, Licheng; Zhao, Yuna

2017-01-01

Compound Arnebiae radix oil has been clinically applied to treat burns and scalds for a long time. However, it is unstable and inconvenient to use. The aim of this study was to prepare a compound Arnebiae radix microemulsion gel for transdermal delivery system and evaluate its characteristics. Based on the solubility of Shikonin, the active component of Arnebiae radix and the results of phase studies, adequate ratio of each component in microemulsion was determined. The optimized microemulsion gel was prepared using Carbomer 940. The gels were characterized in terms of appearance, preliminary stability test and the content of Shikonin in the compound Arnebiae radix microemulsion gel with HPLC analysis. The optimized conditions for preparing microemulsion were Tween-80, glycerin, isopropyl myristate (IPM) with the ratio of 6:3:2. The optimal microemulsion gel was obtained with Carbomer 940 (1.0%). The prepared compound Arnebiae radix microemulsion gel showed good stability over time. It is more convenience in application than the previous used formulations.

Ferroelectric and piezoelectric properties of poly(vinylidene fluoride-trifluoroethylene) gels

NASA Astrophysics Data System (ADS)

Fukagawa, Miki; Koshiba, Yausko; Morimoto, Masahiro; Ishida, Kenji

2017-04-01

The structural, ferroelectric, and piezoelectric properties of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] gels fabricated using poly(pyridinium-1,4-diyliminocarbonyl-1,4-phenylenemethylene thiocyanate) (PICPM-SCN) as a gelator are investigated in this study. The P(VDF-TrFE)/PICPM-SCN composites formed thermally reversible physical gels and their analysis by Fourier transform infrared spectroscopy revealed that the P(VDF-TrFE) molecules in these gels exhibit predominantly the ferroelectric phase I (Form β). Furthermore, the polarization switching peaks of the P(VDF-TrFE)/PICPM-SCN gel films were clearly observed. The coercive electric field for these gel films was estimated to be 2 MV/m, which is dramatically lower than the values typically observed for P(VDF-TrFE) solid films (50 MV/m). Finally, the P(VDF-TrFE)/PICPM-SCN gel films exhibited a piezoelectric response, and the highest piezoelectric coefficient was determined to be ˜53 pm/V at an applied voltage frequency of 4 kHz.

Different additives to enhance the gelation of surimi gel with reduced sodium content.

PubMed

Cando, Deysi; Herranz, Beatriz; Borderías, A Javier; Moreno, Helena M

2016-04-01

This study tested the effect of adding tetra-sodium pyrophosphate, cystine and lysine as surimi gelation enhancers (Alaska Pollock) in order to reduce the sodium content of gels up to 0.3%. These gels were compared with others that contained 3% NaCl content (the amount typically used for surimi processing). To induce protein gelation, gels were first heated and then set at 5 °C/24 h. Once the physicochemical and rheological properties of the gels were determined, cystine and lysine were found to be the most effective additives improving the characteristics of low NaCl surimi gels. The action of these additives is mainly based on the induction of myofibrillar protein unfolding thus facilitating the formation of the types of bonds needed to establish an appropriate network. It was found that a setting period was needed for gel processing to maximize the effect of the additives. Copyright © 2015 Elsevier Ltd. All rights reserved.

Unusual multiscale mechanics of biomimetic nanoparticle hydrogels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Yunlong; Damasceno, Pablo F.; Somashekar, Bagganahalli S.

Viscoelastic properties are central for gels and other materials. Simultaneously, high storage and loss moduli are difficult to attain due to their contrarian requirements to chemical structure. Biomimetic inorganic nanoparticles offer a promising toolbox for multiscale engineering of gel mechanics, but a conceptual framework for their molecular, nanoscale, mesoscale, and microscale engineering as viscoelastic materials is absent. Here we show nanoparticle gels with simultaneously high storage and loss moduli from CdTe nanoparticles. Viscoelastic figure of merit reaches 1.83 MPa exceeding that of comparable gels by 100–1000 times for glutathione-stabilized nanoparticles. The gels made from the smallest nanoparticles display the highestmore » stiffness, which was attributed to the drastic change of GSH configurations when nanoparticles decrease in size. A computational model accounting for the difference in nanoparticle interactions for variable GSH configurations describes the unusual trends of nanoparticle gel viscoelasticity. These observations are generalizable to other NP gels interconnected by supramolecular interactions and lead to materials with high-load bearing abilities and energy dissipation needed for multiple technologies.« less

Characteristics of a normoxic polymethacrylic acid gel dosimeter for a 72-MeV proton beam

NASA Astrophysics Data System (ADS)

Bong, Jihye; Shin, Dongho; Kwon, Soo-Il

2014-01-01

The characteristics of a normoxic polymethacrylic acid gel dosimeter for a 72-MeV proton beam were evaluated. A polymer gel dosimeter was synthesized using gelatin, methacrylic acid, hydroquinone, tetrakis(hydroxymethyl) phosphonium chloride, and highly purified distilled water. The dosimeter was manufactured by placement in a polyethylene (PE) container. Irradiated dosimeters were analyzed to determine the transverse relaxation time (T2) using a 1.5-T MRI. A calibration curve was obtained as a function of the absorbed dose. A Bragg curve made by irradiating the gel with mono-energy was compared with the results for a parallel plate ionization chamber. The spread-out Bragg peak (SOBP) range and distal dose fall-off (DDF) were comparatively analyzed by comparing the irradiated gel with a spread-out Bragg peak against with the ion chamber. Lastly, the gel's usefulness as a dosimeter for therapeutic radiation quality assurance was evaluated by obtaining its practical field size, flatness, and symmetry, through comparison of the profiles of the gel and ion chamber.

Hybrid gels assembled from Fmoc-amino acid and graphene oxide with controllable properties.

PubMed

Xing, Pengyao; Chu, Xiaoxiao; Li, Shangyang; Ma, Mingfang; Hao, Aiyou

2014-08-04

A supramolecular gel is obtained from the self-assembly of an ultralow-molecular-weight gelator (N-fluorenyl-9-methoxycarbonyl glutamic acid) in good and poor solvents. The gelators can self-assemble into a lamellar structure, which can further form twisted fibers and nanotubes in the gel phase. Rheological studies show that the gels are robust and rigid, and are able to rapidly self-recover to a gel after being destroyed by shear force. Fluorescence experiments reveal the aggregation-induced emission effects of the gel system; the fluorescence intensity is significantly enhanced by gel formation. Graphene oxide (GO) is introduced into the system efficiently to give a hybrid material, and the interaction between gelators-GO sheets is studied. Rheological and fluorescent studies imply that the mechanical properties and the fluorescent emission of the hybrid materials can be fine-tuned by controlling the addition of GO. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Smart membranes: Hydroxypropyl cellulose for flavor delivery

NASA Astrophysics Data System (ADS)

Heitfeld, Kevin A.

2007-12-01

This work focuses on the use of temperature responsive gels (TRGs) (polymeric hydrogels with a large temperature-dependent change in volume) for flavor retention at cooking temperatures. Specifically, we have studied a gel with a lower critical solution temperature (LCST) that swells at low temperatures and collapses at high temperatures. In the collapsed state, the polymer acts as a transport barrier, keeping the volatile flavors inside. An encapsulation system was designed to utilize the solution (phase separation) behavior of a temperature responsive gel. The gel morphology was understood and diffusive properties were tailored through morphology manipulation. Heterogeneous and homogeneous gels were processed by understanding the effect of temperature on gel morphology. A morphology model was developed linking bulk diffusive properties to molecular morphology. Flavor was encapsulated within the gel and the emulsifying capability was determined. The capsules responded to temperature similarly to the pure polymer. The release kinetcs were compared to commercial gelatin capsules and the temperature responsive polymer took longer to release.

Comparison of polyacrylamide and agarose gel thin-layer isoelectric focusing for the characterization of beta-lactamases.

PubMed

Vecoli, C; Prevost, F E; Ververis, J J; Medeiros, A A; O'Leary, G P

1983-08-01

Plasmid-mediated beta-lactamases from strains of Escherichia coli and Pseudomonas aeruginosa were separated by isoelectric focusing on a 0.8-mm thin-layer agarose gel with a pH gradient of 3.5 to 9.5. Their banding patterns and isoelectric points were compared with those obtained with a 2.0-mm polyacrylamide gel as the support medium. The agarose method produced banding patterns and isoelectric points which corresponded to the polyacrylamide gel data for most samples. Differences were observed for HMS-1 and PSE-1 beta-lactamases. The HMS-1 sample produced two highly resolvable enzyme bands in agarose gels rather than the single faint enzyme band observed on polyacrylamide gels. The PSE-1 sample showed an isoelectric point shift of 0.2 pH unit between polyacrylamide and agarose gel (pI 5.7 and 5.5, respectively). The short focusing time, lack of toxic hazard, and ease of formulation make agarose a practical medium for the characterization of beta-lactamases.

Comparison of polyacrylamide and agarose gel thin-layer isoelectric focusing for the characterization of beta-lactamases.

PubMed Central

Vecoli, C; Prevost, F E; Ververis, J J; Medeiros, A A; O'Leary, G P

1983-01-01

Plasmid-mediated beta-lactamases from strains of Escherichia coli and Pseudomonas aeruginosa were separated by isoelectric focusing on a 0.8-mm thin-layer agarose gel with a pH gradient of 3.5 to 9.5. Their banding patterns and isoelectric points were compared with those obtained with a 2.0-mm polyacrylamide gel as the support medium. The agarose method produced banding patterns and isoelectric points which corresponded to the polyacrylamide gel data for most samples. Differences were observed for HMS-1 and PSE-1 beta-lactamases. The HMS-1 sample produced two highly resolvable enzyme bands in agarose gels rather than the single faint enzyme band observed on polyacrylamide gels. The PSE-1 sample showed an isoelectric point shift of 0.2 pH unit between polyacrylamide and agarose gel (pI 5.7 and 5.5, respectively). The short focusing time, lack of toxic hazard, and ease of formulation make agarose a practical medium for the characterization of beta-lactamases. Images PMID:6605714

Stimuli responsive ion gels based on polysaccharides and other polymers prepared using ionic liquids and deep eutectic solvents.

PubMed

Prasad, Kamalesh; Mondal, Dibyendu; Sharma, Mukesh; Freire, Mara G; Mukesh, Chandrakant; Bhatt, Jitkumar

2018-01-15

Ion gels and self-healing gels prepared using ionic liquids (ILs) and deep eutectic solvents (DESs) have been largely investigated in the past years due to their remarkable applications in different research areas. Herewith we provide an overview on the ILs and DESs used for the preparation of ion gels, highlight the preparation and physicochemical characteristics of stimuli responsive gel materials based on co-polymers and biopolymers, with special emphasis on polysaccharides and discuss their applications. Overall, this review summarizes the fundamentals and advances in ion gels with switchable properties prepared using ILs or DESs, as well as their potential applications in electrochemistry, in sensing devices and as drug delivery vehicles. Copyright © 2017 Elsevier Ltd. All rights reserved.

A preliminary study on the use of FX-Glycine gel and an in-house optical cone beam CT readout for IMRT and RapidArc verification

NASA Astrophysics Data System (ADS)

Ravindran, Paul B.; Ebenezer, Suman Babu S.; Winfred, Michael Raj; Amalan, S.

2017-05-01

The radiochromic FX gel with Optical CT readout has been investigated by several authors and has shown promising results for 3D dosimetry. One of the applications of the gel dosimeters is their use in 3D dose verification for IMRT and RapidArc quality assurance. Though polymer gel has been used successfully for clinical dose verification, the use of FX gel for clinical dose verification with optical cone beam CT needs further validation. In this work, we have used FX gel and an in- house optical readout system for gamma analysis between the dose matrices of measured dose distribution and a treatment planning system (TPS) calculated dose distribution for a few test cases.

Preliminary study of MAGAT polymer gel dosimetry for boron-neutron capture therapy

NASA Astrophysics Data System (ADS)

Hayashi, Shin-ichiro; Sakurai, Yoshinori; Uchida, Ryohei; Suzuki, Minoru; Usui, Shuji; Tominaga, Takahiro

2015-01-01

MAGAT gel dosimeter with boron is irradiated in Heavy Water Neutron Irradiation Facility (HWNIF) of Kyoto University Research Reactor (KUR). The cylindrical gel phantoms are exposed to neutron beams of three different energy spectra (thermal neutron rich, epithermal and fast neutron rich and the mixed modes) in air. Preliminary results corresponding to depth-dose responses are obtained as the transverse relaxation rate (R2=1/T2) from magnetic resonance imaging data. As the results MAGAT gel dosimeter has the higher sensitivity on thermal neutron than on epi-thermal and fast neutron, and the gel with boron showed an enhancement and a change in the depth-R2 response explicitly. From these results, it is suggested that MAGAT gel dosimeter can be an effective tool in BNCT dosimetry.

Optical fiber sensor having a sol-gel fiber core and a method of making

DOEpatents

Tao, Shiquan; Jindal, Rajeev; Winstead, Christopher; Singh, Jagdish P.

2006-06-06

A simple, economic wet chemical procedure is described for making sol-gel fibers. The sol-gel fibers made from this process are transparent to ultraviolet, visible and near infrared light. Light can be guided in these fibers by using an organic polymer as a fiber cladding. Alternatively, air can be used as a low refractive index medium. The sol-gel fibers have a micro pore structure which allows molecules to diffuse into the fiber core from the surrounding environment. Chemical and biochemical reagents can be doped into the fiber core. The sol-gel fiber can be used as a transducer for constructing an optical fiber sensor. The optical fiber sensor having an active sol-gel fiber core is more sensitive than conventional evanescent wave absorption based optical fiber sensors.

Tetrapeptide-coumarin conjugate 3D networks based on hydrogen-bonded charge transfer complexes: gel formation and dye release.

PubMed

Guo, Zongxia; Gong, Ruiying; Jiang, Yi; Wan, Xiaobo

2015-08-14

Oligopeptide-based derivatives are important synthons for bio-based functional materials. In this article, a Gly-(L-Val)-Gly-(L-Val)-coumarin (GVGV-Cou) conjugate was synthesized, which forms 3D networks in ethanol. The gel nanostructures were characterized by UV-vis spectroscopy, FT-IR spectroscopy, X-ray diffraction (XRD), SEM and TEM. It is suggested that the formation of charge transfer (CT) complexes between the coumarin moieties is the main driving force for the gel formation. The capability of the gel to encapsulate and release dyes was explored. Both Congo Red (CR) and Methylene Blue (MB) can be trapped in the CT gel matrix and released over time. The present gel might be used as a functional soft material for guest encapsulation and release.

A novel gel based vehicle for the delivery of acetylcholine in quantitative sudomotor axon reflex testing.

PubMed

Sletten, David M; Kimpinski, Kurt; Weigand, Stephen D; Low, Phillip A

2009-10-05

This study describes a novel gel based vehicle for the delivery of acetylcholine (ACh) during quantitative sudomotor axon reflex testing (QSART). A dose and current response study were undertaken on 20 healthy control participants to characterize the efficiency of a gel based vehicle for the delivery of ACh. Values obtained for total sweat volume and latency to sweat onset with gel iontophoresis of ACh during QSART were comparable to previously published normative data using solution based vehicles. Patient discomfort, utilizing the gel based vehicle during the QSART procedure, was minimal. Improvement in iontophoresis using the gel formulation as a vehicle for ACh delivery has the potential to lower the voltage required to overcome skin resistance during QSART and may result in improved patient comfort during the procedure.

Encapsulation of nanoclusters in dried gel materials via an inverse micelle/sol gel synthesis

DOEpatents

Martino, Anthony; Yamanaka, Stacey A.; Kawola, Jeffrey S.; Showalter, Steven K.; Loy, Douglas A.

1998-01-01

A dried gel material sterically entrapping nanoclusters of a catalytically active material and a process to make the material via an inverse micelle/sol-gel synthesis. A surfactant is mixed with an apolar solvent to form an inverse micelle solution. A salt of a catalytically active material, such as gold chloride, is added along with a silica gel precursor to the solution to form a mixture. To the mixture are then added a reducing agent for the purpose of reducing the gold in the gold chloride to atomic gold to form the nanoclusters and a condensing agent to form the gel which sterically entraps the nanoclusters. The nanoclusters are normally in the average size range of from 5-10 nm in diameter with a monodisperse size distribution.

Strong circularly polarized luminescence from the supramolecular gels of an achiral gelator: tunable intensity and handedness.

PubMed

Shen, Zhaocun; Wang, Tianyu; Shi, Lin; Tang, Zhiyong; Liu, Minghua

2015-07-01

Although the importance of circularly polarized luminescence (CPL) materials has been widely recognized, the CPL responses of supramolecular gels are still rarely studied. Moreover, developing CPL materials based on supramolecular gels is of great significance, due to their special advantages and important applications. Herein, we report the first circularly polarized supramolecular gels self-assembled exclusively from a simple achiral C 3 -symmetric molecule. Most importantly, the excellent tunability of these novel CPL materials, which benefits from achiral molecular building blocks as well as the nature of supramolecular gels, has been investigated. Thus, the CPL intensity of these supramolecular gels is easily enhanced by mechanical stirring or doping chiral amines. The handedness of CPL signals is controlled by the chirality of organic amines.

High-performance liquid chromatographic method optimization for ondansetron assay in extemporaneous topical gel and in marketed products.

PubMed

Quamrun, Masuda; Mamoon, Rashid; Nasheed, Shams; Randy, Mullins

2014-01-01

The compounding and evaluation of ondansetron hydrochloride dihydrate topical gel, 2.5% w/w, were conducted in this study. The gelling agent was Carbopol 940. Ethanol 70% in purified water was used to dissolve the drug and disperse the gelling agent. A gel was formed by adding drops of 0.1 N sodium hydroxide solution. To assay this gel, we developed a simple and reproducible stability--indicating high-performance liquid chromatographic method. This method was validated for specificity, accuracy, and precision. The compounded gel was assayed in triplicate, and the average recovery was 98.3%. Ondansetron marketed products were analyzed for comparison with the compounded formulation. Assay, accuracy, and precision data of the compounded topical gel were comparable to the marketed products.

Antimicrobial efficacy of amine fluoride based tooth gels compared to a toothpaste in a phase 2/step 2 in-vitro test model

PubMed Central

Schiller, Anne; Großjohann, Beatrice; Welk, Alexander; Hübner, Nils-Olaf; Braun, Dagmar; Assadian, Ojan; Kramer, Axel

2012-01-01

Introduction: The aim of the present study was to determine the antimicrobial effect of various gel formulations on plaque formation; different tooth gels were compared to a toothpaste containing comparable antimicrobial ingredients with regard to its microbiocidal activity. The study was conducted under the assumption, that a chief requirement for the prevention of plaque formation is the combination of mechanical removal and antimicrobial activity, and not the sole capability of mechanical plaque removal. Methods: Ledermix® fluoride gel as commercially available with preservative, and without preservative and perfume oils, Elmex® gelée, and Meridol® toothpaste were tested in a standardized in-vitro test modification of the quantitative suspension test EN 1040. Instead of testing in a suspension, the respective product was directly placed on a standardized contaminated sterile stainless steel disk without adding any bio-burden. 50% egg yolk in Aqua dest. was used as a neutralizer. Results: Within 1 min, Elmex® gelée showed a RF >5 log10 against S. pyogenes and S. sanguinis. Against S. mutans, a log10 RF of ≥5 was achieved after 2 min, against C. albicans after 5 min, and against P. aeruginosa after 10 min S. aureus was the most difficult organisms to be reduced. After an application time of 10 min, only a log10 RF of 2.4 was achieved. Ledermix exceeded the antimicrobial efficacy of Elmex® gelée against S. mutans and C. albicans and was already effective against these organisms after 1 min, but did not show the same antimicrobial efficacy as Elmex® gelée against P. aeruginosa. Similar to Elmex® gelée, a required reduction of >5 log10 for antimicrobials under no organic challenge was not achieved against S. aureus. Ledermix® fluoride gel without preservatives and Ledermix® fluoride gel without preservatives and perfume oil did not show the antimicrobial efficacy of the standard Ledermix® fluoride gel formulation, indicating that the observed antimicrobial efficacy is chiefly based on the preservative, and possibly the perfume oil. Compared to the tested gels, Meridol® toothpaste was less effective and reached any antimicrobial effect >5 log10 only against S. sanguinis after 10 min. Conclusion: All unmodified tested gels showed an antimicrobial effect. Because no relevant antimicrobial efficacy against plaque forming bacteria was achieved within 2 min, in practice, an anti-plaque forming effect based on the antimicrobial action of gels cannot be assumed when used in the oral cavity. However, the results of the present study indicate that the antimicrobial efficacy of gels is determined by their formulation and that for the prevention of plaque formation the combination of mechanical removal and antimicrobial activity is not the chief requirement only, but a sustained antimicrobial effect may be of greater importance. PMID:22558041

Structure of chitosan gels mineralized by sorption

NASA Astrophysics Data System (ADS)

Modrzejewska, Z.; Skwarczyńska, A.; Douglas, T. E. L.; Biniaś, D.; Maniukiewicz, W.; Sielski, J.

2015-10-01

The paper presents the structural studies of mineralized chitosan hydrogels. Hydrogels produced by using sodium beta-glycerophosphate (Na-β-GP) as a neutralizing agent. Mineralization was performed method "post loading", which consisted in sorption to the gels structure Ca ions. In order to obtain - in the structure of gels - compounds similar to the hydroxyapatites present naturally in bone tissue, gels after sorption were modified in: pH 7 buffer and sodium hydrogen phosphate. In order to determine the structural properties of the gels, the following methods were used: infrared spectroscopy with Fourier transformation, FTIR, X-ray diffractometry, XRD, scanning electron microscopy, SEM.

Cation-induced folding of alginate-bearing bilayer gels: an unusual example of spontaneous folding along the long axis.

PubMed

Athas, Jasmin C; Nguyen, Catherine P; Kummar, Shailaa; Raghavan, Srinivasa R

2018-04-04

The spontaneous folding of flat gel films into tubes is an interesting example of self-assembly. Typically, a rectangular film folds along its short axis when forming a tube; folding along the long axis has been seen only in rare instances when the film is constrained. Here, we report a case where the same free-swelling gel film folds along either its long or short axis depending on the concentration of a solute. Our gels are sandwiches (bilayers) of two layers: a passive layer of cross-linked N,N'-dimethylyacrylamide (DMAA) and an active layer of cross-linked DMAA that also contains chains of the biopolymer alginate. Multivalent cations like Ca2+ and Cu2+ induce these bilayer gels to fold into tubes. The folding occurs instantly when a flat film of the gel is introduced into a solution of these cations. The likely cause for folding is that the active layer stiffens and shrinks (because the alginate chains in it get cross-linked by the cations) whereas the passive layer is unaffected. The resulting mismatch in swelling degree between the two layers creates internal stresses that drive folding. Cations that are incapable of cross-linking alginate, such as Na+ and Mg2+, do not induce gel folding. Moreover, the striking aspect is the direction of folding. When the Ca2+ concentration is high (100 mM or higher), the gels fold along their long axis, whereas when the Ca2+ concentration is low (40 to 80 mM), the gels fold along their short axis. We hypothesize that the folding axis is dictated by the inhomogeneous nature of alginate-cation cross-linking, i.e., that the edges get cross-linked before the faces of the gel. At high Ca2+ concentration, the stiffer edges constrain the folding; in turn, the gel folds such that the longer edges are deformed less, which explains the folding along the long axis. At low Ca2+ concentration, the edges and the faces of the gel are more similar in their degree of cross-linking; therefore, the gel folds along its short axis. An analogy can be made to natural structures (such as leaves and seed pods) where stiff elements provide the directionality for folding.

Procedures and computer program for deriving the Ferguson plot from electrophoresis in a single pore gradient gel: application to agarose gel and a polystyrene particle.

PubMed

Tietz, D; Gombocz, E; Chrambach, A

1991-10-01

This study presents a computerized evaluation of pore gradient gel electrophoretograms to arrive at estimates for both the particle-free mobility and retardation coefficient, which is related to particle size. Agarose pore gradient gels ranging from 0.2 to 1.1% agarose were formed. Gel gradients were stabilized during their formation by a density gradient of 0-20% 5-(N-2,3-dihydroxypropylacetamido)- 2,4,6-triiodo-N,N'bis-(2,3-dihydroxypropyl)-isophthalamide (Nycodenz). Densitometry of gelled-in Bromophenol Blue showed that these pore gradients exhibited a linear central segment and were reproducible. Migration distances of polystyrene sulfate microspheres (36.5 nm radius) in agarose pore gradient gel electrophoresis were determined by time-lapse photography at several durations of electrophoresis. These migration distances were evaluated as a function of migration time as previously reported (D. Tietz, Adv. Electrophoresis 1988, 2, 109-169). Although this is not necessarily required, the mathematical approach used in this study assumed linearity of both the pore gradient and the Ferguson plot for reasons of simplicity. The data evaluation on the basis of the extended Ogston model is incorporated in a user-friendly program, GRADFIT, which is designed for personal computers (Macintosh). The results obtained are compared with (1) conventional electrophoresis using several gels of single concentration with and without Nycodenz, and (ii) a different mathematical approach for the analysis of gradient gels (Rodbard et al., Anal. Biochem. 1971, 40, 135-157). Moreover, a simple procedure for evaluating linear pore gradient gels using linear regression analysis is presented. It is concluded that the values of particle-free mobility and retardation coefficient derived from pore gradient gel electrophoresis using the different mathematical methods are statistically indistinguishable from each other. However, these values are different, albeit close, to those obtained from conventional Ferguson plots. One of the possible reasons for this relatively minor discrepancy is that the particle-free mobility changed slightly during electrophoresis, which has a different effect on electrophoresis in homogeneous gels (single time measurement) and pore gradient gels (multiple time measurements). The characterization of particles according to size and charge by pore gradient electrophoresis provides a significant operational simplification and sample economy compared to that requiring the use of several gel concentrations, although at the price of increased requirements of instrumentation.

Biomaterials for Improved Wound Healing

DTIC Science & Technology

2013-10-01

is silver sulphadiazine (SSD) [6-7]. SSD possesses a broad spectrum of activity against gram- positive and gram-negative bacteria as well as fungi [8... polyethylene glycol-based fibrin gel (PEGylated fibrin gel) induces vasculogenesis both in vitro and in vivo [20]. To exploit the inherent ability of fibrin as...Loaded Chitosan Microspheres Impregnated in Polyethylene Glycol Fibrin Gels (SSD-CSM-PEGylated fibrin gels) and Adipose Derived Stem Cells embedded

"JCE" Classroom Activity Connections: NaCl or CaCl[subscript 2], Smart Polymer Gel Tells More

ERIC Educational Resources Information Center

Chen, Yueh-Huey; Lin, Jia-Ying; Wang, Yu-Chen; Yaung, Jing-Fun

2010-01-01

This classroom activity connection demonstrates the differences between the effects of NaCl (a salt of monovalent metal ions) and CaCl[subscript 2] (a salt of polyvalent metal ions) on swollen superabsorbent polymer gels. Being ionic compounds, NaCl and CaCl[subscript 2] both collapse the swollen polymer gels. The gel contracted by NaCl reswells…

Solventless sol-gel chemistry through ring-opening polymerization of bridged disilaoxacyclopentanes

DOE Office of Scientific and Technical Information (OSTI.GOV)

RAHIMIAN,KAMYAR; LOY,DOUGLAS A.

2000-04-04

Disilaoxacyclopentanes have proven to be excellent precursors to sol-gel type materials. These materials have shown promise as precursors for encapsulation and microelectronics applications. The polymers are highly crosslinked and are structurally similar to traditional sol-gels, but unlike typical sol-gels they are prepared without the use of solvents and water, they have low VOC's and show little shrinkage during processing.

PFGE MAPPER and PFGE READER: two tools to aid in the analysis and data input of pulse field gel electrophoresis maps.

PubMed Central

Shifman, M. A.; Nadkarni, P.; Miller, P. L.

1992-01-01

Pulse field gel electrophoresis mapping is an important technique for characterizing large segments of DNA. We have developed two tools to aid in the construction of pulse field electrophoresis gel maps: PFGE READER which stores experimental conditions and calculates fragment sizes and PFGE MAPPER which constructs pulse field gel electrophoresis maps. PMID:1482898