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Sample records for prevent gel weakening

  1. Weakened Immune Systems

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    ... Issues Health Issues Health Issues Conditions Injuries & Emergencies Vaccine Preventable Diseases ... Children > Safety & Prevention > Immunizations > Weakened Immune Systems Safety & Prevention ...

  2. Preventing disulfide bond formation weakens non-covalent forces among lysozyme aggregates.

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    Vijay Kumar Ravi

    Full Text Available Nonnative disulfide bonds have been observed among protein aggregates in several diseases like amyotrophic lateral sclerosis, cataract and so on. The molecular mechanism by which formation of such bonds promotes protein aggregation is poorly understood. Here in this work we employ previously well characterized aggregation of hen eggwhite lysozyme (HEWL at alkaline pH to dissect the molecular role of nonnative disulfide bonds on growth of HEWL aggregates. We employed time-resolved fluorescence anisotropy, atomic force microscopy and single-molecule force spectroscopy to quantify the size, morphology and non-covalent interaction forces among the aggregates, respectively. These measurements were performed under conditions when disulfide bond formation was allowed (control and alternatively when it was prevented by alkylation of free thiols using iodoacetamide. Blocking disulfide bond formation affected growth but not growth kinetics of aggregates which were ∼50% reduced in volume, flatter in vertical dimension and non-fibrillar in comparison to control. Interestingly, single-molecule force spectroscopy data revealed that preventing disulfide bond formation weakened the non-covalent interaction forces among monomers in the aggregate by at least ten fold, thereby stalling their growth and yielding smaller aggregates in comparison to control. We conclude that while constrained protein chain dynamics in correctly disulfide bonded amyloidogenic proteins may protect them from venturing into partial folded conformations that can trigger entry into aggregation pathways, aberrant disulfide bonds in non-amyloidogenic proteins (like HEWL on the other hand, may strengthen non-covalent intermolecular forces among monomers and promote their aggregation.

  3. Fluoride gels for preventing dental caries in children and adolescents.

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    Marinho, Valeria C C; Worthington, Helen V; Walsh, Tanya; Chong, Lee Yee

    2015-06-15

    Topically applied fluoride gels have been widely used as a caries-preventive intervention in dental surgeries and school-based programmes for over three decades. This updates the Cochrane review of fluoride gels for preventing dental caries in children and adolescents that was first published in 2002. The primary objective is to determine the effectiveness and safety of fluoride gels in preventing dental caries in the child and adolescent population.The secondary objectives are to examine whether the effect of fluoride gels is influenced by the following: initial level of caries severity; background exposure to fluoride in water (or salt), toothpastes, or reported fluoride sources other than the study option(s); mode of use (self applied under supervision or operator-applied), and whether there is a differential effect between the tray and toothbrush methods of application; frequency of use (times per year) or fluoride concentration (ppm F). We searched the Cochrane Oral Health Group Trials Register (to 5 November 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library 2014, Issue 11), MEDLINE via OVID (1946 to 5 November 2014), EMBASE via OVID (1980 to 5 November 2014), CINAHL via EBSCO (1980 to 5 November 2014), LILACS and BBO via the BIREME Virtual Health Library (1980 to 5 November 2014), ProQuest Dissertations and Theses (1861 to 5 November 2014) and Web of Science Conference Proceedings (1945 to 5 November 2014). We undertook a search for ongoing trials on ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform on 5 November 2014. We placed no restrictions on language or date of publication in the search of the electronic databases. We also searched reference lists of articles and contacted selected authors and manufacturers. Randomised or quasi-randomised controlled trials where blind outcome assessment was stated or indicated, comparing topically applied fluoride gel with placebo or no treatment in

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

    Science.gov (United States)

    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.

  5. Pulsed estrogen therapy prevents post-OVX porcine dura mater microvascular network weakening via a PDGF-BB-dependent mechanism.

    Directory of Open Access Journals (Sweden)

    Olga V Glinskii

    Full Text Available In postmenopausal women, estrogen (E2 deficiencies are frequently associated with higher risk of intracranial hemorrhage, increased incidence of stroke, cerebral aneurysm, and decline in cognitive abilities. In younger postpartum women and those using oral contraceptives, perturbations in E2 are associated with higher risk of cerebral venous thrombosis. A number of serious intracranial pathologic conditions linked to E2 deficiencies, such as dural sinus thrombosis, dural fistulae, non-parenchymal intracranial hemorrhages, migraines, and spontaneous cerebrospinal fluid leaks, involve the vessels not of the brain itself, but of the outer fibrous membrane of the brain, the dura mater (DM. The pathogenesis of these disorders remains mysterious and how estrogen regulates structural and functional integrity of DM vasculature is largely unknown. Here, we demonstrate that post ovariectomy (OVX DM vascular remodeling is manifested by microvessel destabilization, capillary rarefaction, increased vascular permeability, and aberrant angio-architecture, and is the result of disrupted E2-regulated PDGF-BB signaling within dura microvasculature. These changes, associated with the reduction in systemic PDGF-BB levels, are not corrected by a flat-dose E2 hormone replacement therapy (HRT, but are largely prevented using HRT schedules mimicking physiological E2 fluctuations. We demonstrate that 1 E2 regulates PDGF-BB production by endothelial cells in a dose-dependent manner and 2 optimization of PDGF-BB levels and induction of robust PDGF-mediated endothelial cell-vascular pericyte interactions require high (estrous E2 concentrations. We conclude that high (estrous levels of E2 are important in controlling PDGF-mediated crosstalk between endothelial cells and pericytes, a fundamental mechanism governing microvessel stability and essential for preserving intracranial homeostasis.

  6. Bactericidal micron-thin sol-gel films prevent pin tract and periprosthetic infection.

    Science.gov (United States)

    Qu, Haibo; Knabe, Christine; Burke, Megan; Radin, Shula; Garino, Jonathan; Schaer, Thomas; Ducheyne, Paul

    2014-08-01

    Orthopedic injuries constitute the majority of wounds sustained by U.S. soldiers in recent conflicts. The risk of infection is considerable with fracture fixation devices. In this pilot study, we examined the use of unique bactericidal micron-thin sol-gel films on fracture fixation devices and their ability to prevent and eradicate infections. External fixation was studied with micron-thin sol-gel coated percutaneous pins releasing triclosan and inserted medially into rabbit tibiae. A total of 11 rabbits received percutaneous pins that were either uncoated or sol-gel/triclosan coated. Internal fracture fixation was also studied using sol-gel coated intramedullary (IM) nails releasing vancomycin in the intramedullary tibiae. Six sheep received IM nails that were coated with a sol-gel film that either contained vancomycin or did not contain vancomycin. All animals were challenged with Staphylococcus aureus around the implant. Animals were euthanized at 1 month postoperative. Rabbits receiving triclosan/sol-gel coated percutaneous pins did not show signs of infection. Uncoated percutaneous pins had a significantly higher infection rate. In the sheep study, there were no radiographic signs of osteomyelitis with vancomycin/sol-gel coated IM nails, in contrast to the observations in the control cohort. Hence, the nanostructured sol-gel controlled release technology offers the promise of a reliable and continuous delivery system of bactericidals from orthopedic devices to prevent and treat infection. Reprint & Copyright © 2014 Association of Military Surgeons of the U.S.

  7. Randomised trial of neonatal hypoglycaemia prevention with oral dextrose gel (hPOD): study protocol.

    Science.gov (United States)

    Harding, Jane E; Hegarty, Joanne E; Crowther, Caroline A; Edlin, Richard; Gamble, Greg; Alsweiler, Jane M

    2015-09-16

    Neonatal hypoglycaemia is common, affecting up to 15% of newborn babies and 50% of those with risk factors (preterm, infant of a diabetic, high or low birthweight). Hypoglycaemia can cause brain damage and death, and babies born at risk have an increased risk of developmental delay in later life. Treatment of hypoglycaemia usually involves additional feeding, often with infant formula, and admission to Neonatal Intensive Care for intravenous dextrose. This can be costly and inhibit the establishment of breast feeding. Prevention of neonatal hypoglycaemia would be desirable, but there are currently no strategies, beyond early feeding, for prevention of neonatal hypoglycaemia. Buccal dextrose gel is safe and effective in treatment of hypoglycaemia. The aim of this trial is to determine whether 40% dextrose gel given to babies at risk prevents neonatal hypoglycaemia and hence reduces admission to Neonatal Intensive Care. Randomised, multicentre, placebo controlled trial. Babies at risk of hypoglycaemia (preterm, infant of a diabetic, small or large), less than 1 h old, with no apparent indication for Neonatal Intensive Care Unit admission and mother intends to breastfeed. Trial entry & randomisation: Eligible babies of consenting parents will be allocated by online randomisation to the dextrose gel group or placebo group, using a study number and corresponding trial intervention pack. Babies will receive a single dose of 0.5 ml/kg study gel at 1 h after birth; either 40% dextrose gel (200 mg/kg) or 2% hydroxymethylcellulose placebo. Gel will be massaged into the buccal mucosal and followed by a breast feed. Primary study outcome: Admission to Neonatal Intensive Care. 2,129 babies are required to detect a decrease in admission to Neonatal Intensive Care from 10-6% (two-sided alpha 0.05, 90% power, 5% drop-out rate). This study will investigate whether admission to Neonatal Intensive Care can be prevented by prophylactic oral dextrose gel; a simple, cheap and painless

  8. Aqueous clay suspensions stabilized by alginate fluid gels for coal spontaneous combustion prevention and control.

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    Qin, Botao; Ma, Dong; Li, Fanglei; Li, Yong

    2017-11-01

    We have developed aqueous clay suspensions stabilized by alginate fluid gels (AFG) for coal spontaneous combustion prevention and control. Specially, this study aimed to characterize the effect of AFG on the microstructure, static and dynamic stability, and coal fire inhibition performances of the prepared AFG-stabilized clay suspensions. Compared with aqueous clay suspensions, the AFG-stabilized clay suspensions manifest high static and dynamic stability, which can be ascribed to the formation of a robust three-dimensional gel network by AFG. The coal acceleration oxidation experimental results show that the prepared AFG-stabilized clay suspensions can improve the coal thermal stability and effectively inhibit the coal spontaneous oxidation process by increasing crossing point temperature (CPT) and reducing CO emission. The prepared low-cost and nontoxic AFG-stabilized clay suspensions, exhibiting excellent coal fire extinguishing performances, indicate great application potentials in coal spontaneous combustion prevention and control.

  9. [Preventing complications due to dilatation by intracervical application of a prostaglandin-gel (author's transl)].

    Science.gov (United States)

    Kühnie, H; Grande, P; Kuhn, W

    1977-08-01

    Mechanical injuries by dilatating the cervix uteri for artificial abortion may lead to intra- and postoperative complications; of these cervical insufficiency during subsequent pregnancy is of main importance. In order to prevent this complication 160 patients in the 8th to 18th week of pregnancy, who were going to have a legal abortion, were treated with a gel consisting of 3--5 mg Prostaglandin F2alpha which was applicated in the cervix uteri. In more than 90% of these cases a mechanical dilatation was not necessary afterwards. Generally the cervix uteri was softened and dilatated to Hegar 12. 32% of the patients had a spontaneous abortion. Therefore only a curettage without a dilatation had to be performed. Complications due to the application of the gel did not occur. The combined application of the gel with the extraamnial instillation of Prostaglandin for artificial abortion during the second trimenon reduced by half the period of indwelling of the intrauterine foley-catheter and therewith the risk of infection as well as the period of labour pains. Further possible ways of applicating the Prostaglandin gel in gynecology and obstetrics concern missed abortion, intrauterine death, and cervical dystocia during delivery.

  10. Chemico-therapeutic approach to prevention of dental caries. [using stannous fluoride gel

    Science.gov (United States)

    Shannon, I. L.

    1975-01-01

    The program of chemical preventive dentistry is based primarily upon the development of a procedure for stabilizing stannous fluoride in solution by forcing it into glycerin. New topical fluoride treatment concentrates, fluoride containing gels and prophylaxis pastes, as well as a completely stable stannous fluoride dentifrice are made possible by the development of a rather complicated heat application method to force stannous fluoride into solution in glycerin. That the stannous fluoride is clinically effective in such a preparation is demonstrated briefly on orthodontic patients.

  11. Effect of supervised brushing with fluoride gel during primary school, taking into account the group prevention schedule in kindergarten.

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    Winter, Julia; Jablonski-Momeni, Anahita; Ladda, Annett; Pieper, Klaus

    2017-07-01

    In one region of Germany, a group of children took part in regular fluoride gel applications during primary school following intensified prevention in kindergarten. This observational study aimed to ascertain whether the dental health of primary school children can be improved by introducing a group prevention program based on applications of fluoride gel. The subjects were distributed among six groups with varying preventive measures in kindergarten and at school. The basis for determining caries experience and calculating the caries increment consisted of dental findings gathered in the second and fourth grade. While second graders without professionally supported daily toothbrushing in kindergarten exhibited an average d 3 -6 mft of 2.17, in those who had enjoyed intensive dental prevention, the corresponding value was 19% lower (d 3-6 mft = 1.74). The caries increment was significantly lower mainly among children who had received the maximum of group prevention (intensive prevention in kindergarten and gel program at school). The results show that intensified preventive programs in kindergartens and schools, based mainly on supervised toothbrushing, have a positive effect on the dental health of primary school children. Such programs are efficient in reducing caries experience especially in socially deprived areas.

  12. [Prevention of intrauterine adhesion with auto-crosslinked hyaluronic acid gel: a prospective, randomized, controlled clinical study].

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    Xiao, Songshu; Wan, Yajun; Zou, Fangjun; Ye, Mingzhu; Deng, Henan; Ma, Jiezhi; Wei, Yingying; Tan, Chen; Xue, Min

    2015-01-01

    To evaluate the efficacy and safety of auto-crosslinked hyaluronic acid (HA) gel for preventing intrauterine adhesion (IUA) after hysteroscopic adhesiolysis. A prospective, randomized, double blinded and controlled clinical trial (level I) was performed. According to American Fertility Society (AFS) scoring system, 120 patients (treatment group: 60 cases, control group: 60 cases) with moderate to severe IUA were enrolled. Upon completion of adhesiolysis, a Foley balloon catheter was first introduced into the uterine cavity and then 3 ml of auto-crosslinked HA gel for patients in the treatment group; patients in the control group, however, only received Foley balloon catheter. Second-look hysteroscopic examination was performed to all patients at 3 months postoperatively for evaluation of IUA. Primary endpoint was the reduction rate of IUA at 3 months after surgery. The secondary endpoints include total AFS score, score of each individual AFS category. At 3 months after surgery, auto-crosslinked HA gel resulted in significantly higher effective rate for reduction of adhesion, the effective rate were 76% (42/55) and 48% (27/56) respectively (P = 0.000 9); the total AFS score of treatment group was 2.1 ± 1.1, and significantly lower than that of control group (3.7 ± 2.5, P = 0.000 8). Application of auto-crosslinked HA gel after surgery significantly enhanced the improvement for each individual patient with regard to their adhesive type and menstrual pattern (P = 0.037 8, P = 0.000 4). The treatment group had significantly lower proportion of patients with moderate to severe adhesive stages than that of control group [13% (7/55) versus 38% (21/56), P = 0.000 6]. No adverse events and complications were observed. Auto-crosslinked HA gel coule be able to reduce IUA, decrease adhesion severity, and improve menopause postoperatively. This absorbable auto-crosslinked HA gel is proposed as a barrier for preventing IUA after intrauterine procedures.

  13. Formation and prevention of fractures in sol-gel-derived thin films

    NARCIS (Netherlands)

    Kappert, Emiel; Pavlenko, Denys; Malzbender, J.; Nijmeijer, Arian; Benes, Nieck Edwin; Tsai, Peichun Amy

    2015-01-01

    Sol–gel-derived thin films play an important role as the functional coatings for various applications that require crack-free films to fully function. However, the fast drying process of a standard sol–gel coating often induces mechanical stresses, which may fracture the thin films. An experimental

  14. Weakened Immune System and Adult Vaccination

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    ... Basics Adult Vaccination Resources for Healthcare Professionals Weakened Immune System and Adult Vaccination Recommend on Facebook Tweet Share ... people with health conditions such as a weakened immune system. If you have cancer or other immunocompromising conditions, ...

  15. Percutaneous external fixator pins with bactericidal micron-thin sol-gel films for the prevention of pin tract infection.

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    Qu, Haibo; Knabe, Christine; Radin, Shula; Garino, Jonathan; Ducheyne, Paul

    2015-09-01

    Risk of infection is considerable in open fractures, especially when fracture fixation devices are used to stabilize the fractured bones. Overall deep infection rates of 16.2% have been reported. The infection rate is even greater, up to 32.2%, with external fixation of femoral fractures. The use of percutaneous implants for certain clinical applications, such as percutaneous implants for external fracture fixation, still represents a challenge today. Currently, bone infections are very difficult to treat. Very potent antibiotics are needed, which creates the risk of irreversible damage to other organs, when the antibiotics are administered systemically. As such, controlled, local release is being pursued, but no such treatments are in clinical use. Herein, the use of bactericidal micron-thin sol-gel films on metallic fracture fixation pins is reported. The data demonstrates that triclosan (2,4,4'-trichloro-2'-hydroxydiphenylether), an antimicrobial agent, can be successfully incorporated into micron-thin sol-gel films deposited on percutaneous pins. The sol-gel films continuously release triclosan in vitro for durations exceeding 8 weeks (longest measured time point). The bactericidal effect of the micron-thin sol-gel films follows from both in vitro and in vivo studies. Inserting percutaneous pins in distal rabbit tibiae, there were no signs of infection around implants coated with a micron-thin sol-gel/triclosan film. Healing had progressed normally, bone tissue growth was normal and there was no epithelial downgrowth. This result was in contrast with the results in rabbits that received control, uncoated percutaneous pins, in which abundant signs of infection and epithelial downgrowth were observed. Thus, well-adherent, micron-thin sol-gel films laden with a bactericidal molecule successfully prevented pin tract infection. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Prophylactic Dextrose Gel Does Not Prevent Neonatal Hypoglycemia: A Quasi-Experimental Pilot Study.

    Science.gov (United States)

    Coors, Sarah M; Cousin, Joshua J; Hagan, Joseph L; Kaiser, Jeffrey R

    2018-03-28

    To test the hypothesis that prophylactic dextrose gel administered to newborn infants at risk for hypoglycemia will increase the initial blood glucose concentration after the first feeding and decrease neonatal intensive care unit (NICU) admissions for treatment of asymptomatic neonatal hypoglycemia compared with feedings alone. This quasi-experimental study allocated asymptomatic at-risk newborn infants (late preterm, birth weight 4000 g, and infants of mothers with diabetes) to receive prophylactic dextrose gel (Insta-Glucose; Valeant Pharmaceuticals North America LLC, Bridgewater, New Jersey); other at-risk infants formed the control group. After the initial feeding, the prophylactic group received dextrose gel (0.5 mL/kg) rubbed into the buccal mucosa. The blood glucose concentration was checked 30 minutes later. Initial glucose concentrations and rate of NICU admissions were compared between the prophylactic group and controls using bivariate analyses. A multivariable linear regression compared first glucose concentrations between groups, adjusting for at-risk categories and age at first glucose concentration. There were 236 subjects (72 prophylactic, 164 controls). The first glucose concentration was not different between the prophylactic and control groups in bivariate analysis (52.1 ± 17.1 vs 50.5 ± 15.3 mg/dL, P = .69) and after adjusting for covariates (P  = .18). Rates of NICU admission for treatment of transient neonatal hypoglycemia were 9.7% and 14.6%, respectively (P = .40). Prophylactic dextrose gel did not reduce transient neonatal hypoglycemia or NICU admissions for hypoglycemia. The carbohydrate concentration of Insta-Glucose (77%) may have caused a hyperinsulinemic response, or alternatively, exogenous enteral dextrose influences glucose homeostasis minimally during the first few hours when counter-regulatory mechanisms are especially active. ClinicalTrials.gov: NCT02523222. Copyright © 2018 Elsevier Inc. All

  17. Technical improvement to prevent DNA degradation of Leptospira spp. in pulsed field gel electrophoresis.

    Science.gov (United States)

    Ribeiro, R L; Machry, L; Brazil, J M V; Ramos, T M V; Avelar, K E S; Pereira, M M

    2009-08-01

    Leptospirosis is a public health problem. Infection with pathogenic Leptospira occurs by exposure to many environments and is traditionally associated with occupational risk activities. Pulsed-field gel electrophoresis was used to investigate the epidemiological relatedness among Leptospira isolates. However, analysis by PFGE yielded inconclusive data as a result of extensive DNA degradation. This degradation can be significantly reduced by the inclusion of thiourea in the electrophoresis buffer, improving the analysis of DNA banding patterns.

  18. Effectiveness of cellulose sulfate vaginal gel for the prevention of HIV infection: results of a Phase III trial in Nigeria.

    Directory of Open Access Journals (Sweden)

    Vera Halpern

    Full Text Available This trial evaluated the safety and effectiveness of 6% cellulose sulfate vaginal gel in preventing male-to-female vaginal transmission of HIV, gonorrhea and chlamydial infection.This Phase III, double-blind, randomized, placebo-controlled trial was conducted between November 2004 and March 2007 in Lagos and Port Harcourt, Nigeria. We enrolled 1644 HIV-antibody negative women at high risk of HIV acquisition. Study participants were randomized 1:1 to cellulose sulfate or placebo and asked to use gel plus a condom for each act of vaginal intercourse over one year of follow-up. The participants were evaluated monthly for HIV, gonorrhea and chlamydial infection, and for adverse events.The trial was stopped prematurely after the data safety monitoring board of a parallel trial concluded that cellulose sulfate might be increasing the risk of HIV. In contrast, we observed fewer infections in the active arm (10 than on placebo (13, a difference that was nonetheless not statistically significant (HR = 0.8, 95% CI 0.3-1.8; p = 0.56. Rates of gonorrhea and chlamydial infection were lower in the CS group but the difference was likewise not statistically significant (HR = 0.8, 95% CI 0.5-1.1; p = 0.19 for the combined STI outcome. Rates of adverse events were similar across study arms. No serious adverse events related to cellulose sulfate use were reported.Cellulose sulfate gel appeared to be safe in the evaluated study population but we found insufficient evidence that it prevented male-to-female vaginal transmission of HIV, gonorrhea or chlamydial infection. The early closure of the trial compromised the ability to draw definitive conclusions about the effectiveness of cellulose sulfate against HIV.ClinicalTrials.gov NCT00120770.

  19. Diabetes Prevention and Treatment Programs for Western PA - Pediatrics/Platelet Gel

    Science.gov (United States)

    2009-09-01

    Diabetes Education Program results for self-management decision making f. Preventing, detecting , and treating acute complications. g. Preventing...SYSTEM AT WHMC 2.4.1 Expand Image Reading Center at WHMC Diabetic retinopathy is the leading cause of new cases of blindness in Americans...between the ages of 20 to 74 (45-50). It has been estimated that blindness from diabetic retinopathy is preventable in at least 65% of cases, if

  20. Comparison and Application of Two types of Filling Gel to Prevent Spontaneous Combustion at the Region where Top-Coal Caves above Entry

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    Wang Yuhuai

    2016-01-01

    Full Text Available Two types of gel were developed, by taking fly ash and foaming cement as aggregate, which is usually used as filling material at the region where top-coal caves above coal entry in the Jinggezhuang coal mine, and adding high molecular polymer and bio-gel as additive. Sweating rates of the two types of gel under various matching ratio and temperature were tested. And then sweating ratio and water retention ratio of the two gels were calculated, based on which, the optimized matching ratios, were determined. Viscosity indexes of the two-type gel under different ratios were tested. The optimized filling ratios of the two types of gel were determined according to the two indexes, water retention rate and the viscosity. The filling experiments were implemented and evaluated in site, the Jinggezhuang coal mine. The results show that the fly ash gel has a good achievement on preventing spontaneous combustion at the Region where Top-Coal Caves above entries. It is promising, economically and environmental friendly, and valuable in popularization in coal mines.

  1. Efficacy of a hydroactive colloid gel versus historical controls for the prevention of radiotherapy-induced moist desquamation in breast cancer patients.

    Science.gov (United States)

    Censabella, Sandrine; Claes, Stefan; Orlandini, Marc; Braekers, Roel; Bulens, Paul

    2017-08-01

    Radiotherapy-induced moist desquamation (RIMD) is a complication that can affect patients' quality of life and jeopardize radiotherapy outcomes. The curative use of a hydroactive colloid gel has previously been shown effective in the management of RIMD in breast cancer patients. This study aimed at investigating the efficacy of this same gel but in the prevention of RIMD. A group of breast cancer patients who applied the hydroactive gel from start to end of post-lumpectomy radiotherapy (Preventive Hydrogel group) were compared with two groups of matched historical controls: a group applying a dexpanthenol cream throughout their therapy and a group applying first the dexpanthenol cream then, after 11-14 fractions of radiotherapy, the hydroactive gel (Curative Hydrogel group). All patients received identical fractionation regimen. The clinical outcomes were the incidence and time to onset of RIMD. After 25 fractions of radiotherapy (50 Gy), patients in the Preventive Hydrogel group (N = 202) developed RIMD significantly less frequently and later than patients in the Dexpanthenol group (N = 131; incidence = 7% vs 35% respectively, odds ratios = 7.27; probability of RIMD-free survival after 50 Gy = 0.88 vs 0.62). There were no significant differences between the Preventive and the Curative Hydrogel group (N = 87). These findings confirm our previous results: applying the hydroactive colloid gel, rather than dexpanthenol, delayed the onset and reduced the incidence of RIMD in breast cancer patients. However, applying the hydrogel preventively offered no statistically significant advantages over applying it curatively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. A phase III trial comparing an anionic phospholipid-based cream and aloe vera-based gel in the prevention of radiation dermatitis in pediatric patients

    International Nuclear Information System (INIS)

    Merchant, Thomas E; Bosley, Christina; Smith, Julie; Baratti, Pam; Pritchard, David; Davis, Tina; Li, Chenghong; Xiong, Xiaoping

    2007-01-01

    Radiation dermatitis is a common side effect of radiation therapy (RT). In severe cases, RT must be interrupted until the skin heals, which can compromise treatment. The purpose of the study was to compare an anionic polar phospholipid (APP)-based cream and an aloe vera-based gel to determine their effectiveness in preventing and treating radiation dermatitis. Forty-five pediatric patients (median age, 11 years) with various diagnoses who received at least 23.4 Gy participated. APP cream and aloe vera gel were symmetrically applied within the irradiated field after each treatment. Three measures were collected before, during and after completion of treatment: subject's skin comfort, dermatologic assessment, and common toxicity criteria (CTC). Significant differences in specific variables favoring APP cream use were noted in some patients including skin comfort variables, dry (p = 0.002), soft (p = 0.057), feels good (p = 0.002), rough (p = 0.065), smooth (p = 0.012) and dermatologic variables, dryness (p = 0.013), erythema (p = 0.002) and peely (p = 0.008). Grouped CTC scores were supportive of APP cream (p = 0.004). In comparing the first and last assessments, two dermatologic variables, dryness (p = 0.035) and peely (p = 0.016), favored APP cream. APP cream is more effective than aloe vera-based gel for prevention and treatment of radiation dermatitis

  3. Macroalgal spore dysfunction: ocean acidification delays and weakens adhesion.

    Science.gov (United States)

    Guenther, Rebecca; Miklasz, Kevin; Carrington, Emily; Martone, Patrick T

    2018-04-01

    Early life stages of marine organisms are predicted to be vulnerable to ocean acidification. For macroalgae, reproduction and population persistence rely on spores to settle, adhere and continue the algal life cycle, yet the effect of ocean acidification on this critical life stage has been largely overlooked. We explicitly tested the biomechanical impact of reduced pH on early spore adhesion. We developed a shear flume to examine the effect of reduced pH on spore attachment time and strength in two intertidal rhodophyte macroalgae, one calcified (Corallina vancouveriensis) and one noncalcified (Polyostea robusta). Reduced pH delayed spore attachment of both species by 40%-52% and weakened attachment strength in C. vancouveriensis, causing spores to dislodge at lower flow-induced shear forces, but had no effect on the attachment strength of P. robusta. Results are consistent with our prediction that reduced pH disrupts proper curing and gel formation of spore adhesives (anionic polysaccharides and glycoproteins) via protonation and cation displacement, although experimental verification is needed. Our results demonstrate that ocean acidification negatively, and differentially, impacts spore adhesion in two macroalgae. If results hold in field conditions, reduced ocean pH has the potential to impact macroalgal communities via spore dysfunction, regardless of the physiological tolerance of mature thalli. © 2017 Phycological Society of America.

  4. Hyaluronic Acid Gel Injection to Prevent Thermal Injury of Adjacent Gastrointestinal Tract during Percutaneous Liver Radiofrequency Ablation

    International Nuclear Information System (INIS)

    Hasegawa, Takaaki; Takaki, Haruyuki; Miyagi, Hideki; Nakatsuka, Atsuhiro; Uraki, Junji; Yamanaka, Takashi; Fujimori, Masashi; Sakuma, Hajime; Yamakado, Koichiro

    2013-01-01

    This study evaluated the safety, feasibility, and clinical utility of hyaluronic acid gel injection to separate the gastrointestinal tract from the tumor during liver radiofrequency ablation (RFA). Eleven patients with liver tumors measuring 0.9–3.5 cm (mean ± standard deviation, 2.1 ± 0.8 cm) that were adjacent to the gastrointestinal tracts received RFA after the mixture of hyaluronic acid gel and contrast material (volume, 26.4 ± 14.5 mL; range, 10–60 mL) was injected between the tumor and the gastrointestinal tract under computed tomographic–fluoroscopic guidance. Each tumor was separated from the gastrointestinal tract by 1.0–1.5 cm (distance, 1.2 ± 0.2 cm) after injection of hyaluronic acid gel, and subsequent RFA was performed without any complications in all patients. Although tumor enhancement disappeared in all patients, local tumor progression was found in a patient (9.1 %, 1 of 11) during the follow-up of 5.5 ± 3.2 months (range, 0.4–9.9 months). In conclusion, hyaluronic acid gel injection is a safe and useful technique to avoid thermal injury of the adjacent gastrointestinal tract during liver RFA

  5. Hyaluronic Acid Gel Injection to Prevent Thermal Injury of Adjacent Gastrointestinal Tract during Percutaneous Liver Radiofrequency Ablation

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Takaaki, E-mail: hasegawat@clin.medic.mie-u.ac.jp; Takaki, Haruyuki; Miyagi, Hideki; Nakatsuka, Atsuhiro; Uraki, Junji; Yamanaka, Takashi; Fujimori, Masashi; Sakuma, Hajime; Yamakado, Koichiro [Mie University School of Medicine, Department of Radiology (Japan)

    2013-08-01

    This study evaluated the safety, feasibility, and clinical utility of hyaluronic acid gel injection to separate the gastrointestinal tract from the tumor during liver radiofrequency ablation (RFA). Eleven patients with liver tumors measuring 0.9-3.5 cm (mean {+-} standard deviation, 2.1 {+-} 0.8 cm) that were adjacent to the gastrointestinal tracts received RFA after the mixture of hyaluronic acid gel and contrast material (volume, 26.4 {+-} 14.5 mL; range, 10-60 mL) was injected between the tumor and the gastrointestinal tract under computed tomographic-fluoroscopic guidance. Each tumor was separated from the gastrointestinal tract by 1.0-1.5 cm (distance, 1.2 {+-} 0.2 cm) after injection of hyaluronic acid gel, and subsequent RFA was performed without any complications in all patients. Although tumor enhancement disappeared in all patients, local tumor progression was found in a patient (9.1 %, 1 of 11) during the follow-up of 5.5 {+-} 3.2 months (range, 0.4-9.9 months). In conclusion, hyaluronic acid gel injection is a safe and useful technique to avoid thermal injury of the adjacent gastrointestinal tract during liver RFA.

  6. Nanoencapsulation of Rose-Hip Oil Prevents Oil Oxidation and Allows Obtainment of Gel and Film Topical Formulations.

    Science.gov (United States)

    Contri, Renata V; Kulkamp-Guerreiro, Irene C; da Silva, Sheila Janine; Frank, Luiza A; Pohlmann, Adriana R; Guterres, Silvia S

    2016-08-01

    The rose-hip oil holds skin regenerating properties with applications in the dermatological and cosmetic area. Its nanoencapsulation might favor the oil stability and its incorporation into hydrophilic formulations, besides increasing the contact with the skin and prolonging its effect. The aim of the present investigation was to develop suitable rose-hip-oil-loaded nanocapsules, to verify the nanocapsule effect on the UV-induced oxidation of the oil and to obtain topical formulations by the incorporation of the nanocapsules into chitosan gel and film. The rose-hip oil (500 or 600 μL), polymer (Eudragit RS100®, 100 or 200 mg), and acetone (50 or 100 mL) contents were separately varied aiming to obtain an adequate size distribution. The results led to a combination of the factors acetone and oil. The developed formulation showed average diameter of 158 ± 6 nm with low polydispersity, pH of 5.8 ± 0.9, zeta potential of +9.8 ± 1.5 mV, rose-hip oil content of 54 ± 1 μL/mL and tendency to reversible creaming. No differences were observed in the nanocapsules properties after storage. The nanoencapsulation of rose-hip oil decreased the UVA and UVC oxidation of the oil. The chitosan gel and film containing rose-hip-oil-loaded nanocapsules showed suitable properties for cutaneous use. In conclusion, it was possible to successfully obtain rose-hip-oil-loaded nanocapsules and to confirm the nanocapsules effect in protecting the oil from the UV rays. The chitosan gel and film were considered interesting alternatives for incorporating the nanoencapsulated rose-hip oil, combining the advantages of the nanoparticles to the advantages of chitosan.

  7. Prevention of SIV rectal transmission and priming of T cell responses in macaques after local pre-exposure application of tenofovir gel.

    Directory of Open Access Journals (Sweden)

    Martin Cranage

    2008-08-01

    Full Text Available The rectum is particularly vulnerable to HIV transmission having only a single protective layer of columnar epithelium overlying tissue rich in activated lymphoid cells; thus, unprotected anal intercourse in both women and men carries a higher risk of infection than other sexual routes. In the absence of effective prophylactic vaccines, increasing attention is being given to the use of microbicides and preventative antiretroviral (ARV drugs. To prevent mucosal transmission of HIV, a microbicide/ARV should ideally act locally at and near the virus portal of entry. As part of an integrated rectal microbicide development programme, we have evaluated rectal application of the nucleotide reverse transcriptase (RT inhibitor tenofovir (PMPA, 9-[(R-2-(phosphonomethoxy propyl] adenine monohydrate, a drug licensed for therapeutic use, for protective efficacy against rectal challenge with simian immunodeficiency virus (SIV in a well-established and standardised macaque model.A total of 20 purpose-bred Indian rhesus macaques were used to evaluate the protective efficacy of topical tenofovir. Nine animals received 1% tenofovir gel per rectum up to 2 h prior to virus challenge, four macaques received placebo gel, and four macaques remained untreated. In addition, three macaques were given tenofovir gel 2 h after virus challenge. Following intrarectal instillation of 20 median rectal infectious doses (MID50 of a noncloned, virulent stock of SIVmac251/32H, all animals were analysed for virus infection, by virus isolation from peripheral blood mononuclear cells (PBMC, quantitative proviral DNA load in PBMC, plasma viral RNA (vRNA load by sensitive quantitative competitive (qc RT-PCR, and presence of SIV-specific serum antibodies by ELISA. We report here a significant protective effect (p = 0.003; Fisher exact probability test wherein eight of nine macaques given tenofovir per rectum up to 2 h prior to virus challenge were protected from infection (n = 6 or had

  8. Oral administration of Aloe vera gel powder prevents UVB-induced decrease in skin elasticity via suppression of overexpression of MMPs in hairless mice.

    Science.gov (United States)

    Saito, Marie; Tanaka, Miyuki; Misawa, Eriko; Yao, Ruiquing; Nabeshima, Kazumi; Yamauchi, Kouji; Abe, Fumiaki; Yamamoto, Yuki; Furukawa, Fukumi

    2016-07-01

    This study reports the effects of oral Aloe vera gel powder (AVGP) containing Aloe sterols on skin elasticity and the extracellular matrix in ultraviolet B (UVB)-irradiated hairless mice. Ten-week-old hairless mice were fed diets containing 0.3% AVGP for 8 weeks and irradiated UVB for 6 weeks. Mice treated with AVGP showed significant prevention of the UVB-induced decrease in skin elasticity. To investigate the mechanism underlying this suppression of skin elasticity loss, we measured the expression of matrix metalloproteinase (MMP)-2, -9, and -13. AVGP prevented both the UVB-induced increases in MMPs expressions. Moreover, we investigated hyaluronic acid (HA) content of mice dorsal skin and gene expression of HA synthase-2 (Has2). In the results, AVGP oral administration prevented UVB-induced decreasing in skin HA content and Has2 expression and attenuates the UVB-induced decrease in serum adiponectin, which promotes Has2 expression. These results suggested that AVGP has the ability to prevent the skin photoaging.

  9. Use of onion extract, heparin, allantoin gel in prevention of scarring in chinese patients having laser removal of tattoos: a prospective randomized controlled trial.

    Science.gov (United States)

    Ho, Wai Sun; Ying, Shun Yuen; Chan, Pik Chu; Chan, Henry H

    2006-07-01

    With rapid advancement in cutaneous laser therapy, Q-switched lasers have become the standard treatment for tattoo removal. The longer wavelength Q-switched Nd:YAG laser is used when removing tattoos in darker skin patients to avoid scarring and permanent pigment changes. Nevertheless, the local experience revealed that nearly 25% of the Chinese patients developed scarring. Meanwhile, multiple clinical studies have shown that Contractubex gel (Merz Pharma, Frankfurt, Germany) was effective in the treatment and prevention of hypertrophic scars and keloids. To evaluate the efficacy of Contractubex gel in the prevention of scarring after laser removal of tattoos in Chinese patients. A total of 120 Chinese patients with 144 professional blue-black tattoos were recruited into the study. They were randomly assigned into the Contractubex group or the control group. All patients were treated with a QS 1,064-nm Nd:YAG laser using a 3-mm spot size, a 10-Hz repeat rate, a pulse duration of 6 nanoseconds, and fluences that ranged from 3.6 to 4.8 J/cm2 (mean fluence, 4.2 J/cm2). The treated areas were assessed 3 months after the last treatments for clinical clearance and complications. Fifty-two patients with 61 tattoos in the Contractubex group were able to achieve a mean clearing rate of 82.3+/-11.6%. There were 7 tattoos in 7 patients that developed scarring, 4 patients had permanent hypopigmentation, and 3 patients had transient hyperpigmentation. In contrast, 55 patients with 68 tattoos in the control group had a mean clearing rate of 80.4+/-11.3%. Among them, 16 tattoos in 14 patients developed scarring, 4 patients had permanent hypopigmentation, and 5 patients had transient hyperpigmentation. Although there was no significant difference in age, sex, fluence, treatment session, and clinical clearance between the two groups, the Contractubex group had a statistically significantly lower rate of scarring than the control group (ptattoos.

  10. Myo-inositol soft gel capsules may prevent the risk of coffee-induced neural tube defects.

    Science.gov (United States)

    De Grazia, Sara; Carlomagno, Gianfranco; Unfer, Vittorio; Cavalli, Pietro

    2012-09-01

    Neural tube defects (NTDs) are classified as folate sensitive (about 70%) and folate resistant (about 30%); although folic acid is able to prevent the former, several data have shown that inositol may prevent the latter. It has recently been proposed that coffee intake might represent a risk factor for NTD, likely by interfering with the inositol signaling. In the present study, we tested the hypothesis that, beside affecting the inositol signaling pathway, coffee also interferes with inositol absorption. In order to evaluate coffee possible negative effects on inositol gastrointestinal absorption, a single-dose bioavailability trial was conducted. Pharmacokinetics (PK) parameters of myo-inositol (MI) powder and MI soft gelatin capsules swallowed with water and with a single 'espresso' were compared. PK profiles were obtained by analysis of MI plasma concentration, and the respective MI bioavailability was compared. Myo-inositol powder administration was negatively affected by coffee intake, thus suggesting an additional explanation to the interference between inositol deficiency and coffee consumption. On the contrary, the concomitant single 'espresso' consumption did not affect MI absorption following MI soft gelatin capsules administration. Furthermore, it was observed that MI soft gelatin capsule administration resulted in improved bioavailability compared to the MI powder form. Myo-inositol soft gelatin capsules should be considered for the preventive treatment of NTDs in folate-resistant subjects due to their higher bioavailability and to the capability to reduce espresso interference.

  11. Whisker Deprivation Drives Two Phases of Inhibitory Synapse Weakening in Layer 4 of Rat Somatosensory Cortex.

    Directory of Open Access Journals (Sweden)

    Melanie A Gainey

    Full Text Available Inhibitory synapse development in sensory neocortex is experience-dependent, with sustained sensory deprivation yielding fewer and weaker inhibitory synapses. Whether this represents arrest of synapse maturation, or a more complex set of processes, is unclear. To test this, we measured the dynamics of inhibitory synapse development in layer 4 of rat somatosensory cortex (S1 during continuous whisker deprivation from postnatal day 7, and in age-matched controls. In deprived columns, spontaneous miniature inhibitory postsynaptic currents (mIPSCs and evoked IPSCs developed normally until P15, when IPSC amplitude transiently decreased, recovering by P16 despite ongoing deprivation. IPSCs remained normal until P22, when a second, sustained phase of weakening began. Delaying deprivation onset by 5 days prevented the P15 weakening. Both early and late phase weakening involved measurable reduction in IPSC amplitude relative to prior time points. Thus, deprivation appears to drive two distinct phases of active IPSC weakening, rather than simple arrest of synapse maturation.

  12. Analysis of ventilator-associated pneumonia infection route by genome macrorestriction-pulsed-field gel electrophoresis and its prevention with combined nursing strategies.

    Science.gov (United States)

    Wang, Xiaodong; Wang, Junping; Li, Jing; Wang, Jing

    2014-12-01

    The aim of the present study was to explore the infection route of ventilator-associated pneumonia (VAP) and assess the effectiveness of a combined nursing strategy to prevent VAP in intensive care units. Bacteria from the gastric juice and drainage from the hypolarynx and lower respiratory tracts of patients with VAP were analyzed using genome macrorestriction-pulsed-field gel electrophoresis (GM-PFGE). A total of 124 patients with tracheal intubation were placed in the intervention group and were treated with a combined nursing strategy, comprising mosapride (gastric motility stimulant) administration and semi-reclining positioning. A total of 112 intubated patients were placed in the control group and received routine nursing care. The incidence rate of VAP, days of ventilation and mortality rate of patients were compared between the two groups. The GM-PFGE fingerprinting results of three strains of Pseudomonas aeruginosa from the gastric juice, subglottic secretion drainage and drainage of the lower respiratory tract in patients with VAP were similar across groups. The number of days spent on a ventilator by patients in the intervention group (7.37±5.32 days) was lower compared with that by patients in the control group (12.34±4.98 days) (PVAP was reduced from 40.81 to 21.25% following intervention with the combined nursing strategy (Ppatients in the intervention group was 29.46%, a significant reduction compared with the 41.94% mortality rate observed in the control group (PVAP. The combined nursing strategy of gastric motility stimulant administration and the adoption of a semi-reclining position was effective in preventing VAP by reducing the occurrence of GER.

  13. Attention during adaptation weakens negative afterimages of perceptually colour-spread surfaces.

    Science.gov (United States)

    Lak, Armin

    2008-06-01

    The visual system can complete coloured surfaces from stimulus fragments, inducing the subjective perception of a colour-spread figure. Negative afterimages of these induced colours were first reported by S. Shimojo, Y. Kamitani, and S. Nishida (2001). Two experiments were conducted to examine the effect of attention on the duration of these afterimages. The results showed that shifting attention to the colour-spread figure during the adaptation phase weakened the subsequent afterimage. On the basis of previous findings that the duration of these afterimages is correlated with the strength of perceptual filling-in (grouping) among local inducers during the adaptation phase, it is proposed that attention weakens perceptual filling-in during the adaptation phase and thereby prevents the stimulus from being segmented into an illusory figure. (PsycINFO Database Record (c) 2008 APA, all rights reserved).

  14. Fluoride Rinses, Gels and Foams

    DEFF Research Database (Denmark)

    Twetman, Svante; Keller, Mette K

    2016-01-01

    AIM: The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. METHODS: Relevant papers were selected after...... (6 on fluoride mouth rinse, 10 on fluoride gel and 3 on fluoride foam); 6 had a low risk of bias while 2 had a moderate risk. All fluoride measures appeared to be beneficial in preventing crown caries and reversing root caries, but the quality of evidence was graded as low for fluoride mouth rinse......, moderate for fluoride gel and very low for acidulated fluoride foam. No conclusions could be drawn on the cost-effectiveness. CONCLUSIONS: This review, covering the recent decade, has further substantiated the evidence for a caries-preventive effect of fluoride mouth rinse, fluoride gel and foam...

  15. A self-assembling matrix-forming gel can be easily and safely applied to prevent delayed bleeding after endoscopic resections.

    Science.gov (United States)

    Pioche, Mathieu; Camus, Marine; Rivory, Jérôme; Leblanc, Sarah; Lienhart, Isabelle; Barret, Maximilien; Chaussade, Stanislas; Saurin, Jean-Christophe; Prat, Frederic; Ponchon, Thierry

    2016-04-01

    Endoscopic resections have low morbidity and mortality. Delayed bleeding has been reported in approximately 1 - 15 % of cases, increasing with antiplatelet/anticoagulant therapy or portal hypertension. A self-assembling peptide (SAP) forming a gel could protect the mucosal defect during early healing. This retrospective trial aimed to assess the safety and efficacy of SAP in preventing delayed bleeding after endoscopic resections. Consecutive patients with endoscopic resections were enrolled in two tertiary referral centers. Patients with a high risk of bleeding (antiplatelet agents, anticoagulation drugs with heparin bridge therapy, and cirrhosis with portal hypertension) were also included. The SAP gel was applied immediately after resection to cover the whole ulcer bed. In total, 56 patients were included with 65 lesions (esophagus [n = 8], stomach [n = 22], duodenum [n = 10], ampullary [n = 3], colon [n = 7], and rectum [n = 15]) in two centers. Among those 65 lesions, 29 were resected in high risk situations (9 uninterrupted aspirin therapy, 6 heparin bridge therapies, 5 cirrhosis and portal hypertension, 1 both cirrhosis and heparin bridge, 3 both cirrhosis and uninterrupted aspirin, 3 large duodenal lesions > 2 cm, and 2 early introduction of clopidogrel at day 1). The resection technique was endoscopic submucosal dissection (ESD) in 40 cases, en bloc endoscopic mucosal resection (EMR) in 16, piecemeal EMR in 6, and ampullectomy in 3. The mean lesion size was 37.9 mm (SD: 2.2 mm) with a mean area of 6.3 cm(2) (SD: 3.5 cm(2)). No difficulty was noted during application. Four delayed overt bleedings occurred (6.2 %) (3 hematochezia, 1 hematemesis) requiring endoscopic hemostasis. The mean hemoglobin drop off was 0.6 g/dL (- 0.6 to 3.1 g/dL). No adverse events occurred. The use of this novel extracellular matrix scaffold may help to reduce post-endoscopic resection bleedings including in high risk situations

  16. A self-assembling matrix-forming gel can be easily and safely applied to prevent delayed bleeding after endoscopic resections

    Science.gov (United States)

    Pioche, Mathieu; Camus, Marine; Rivory, Jérôme; Leblanc, Sarah; Lienhart, Isabelle; Barret, Maximilien; Chaussade, Stanislas; Saurin, Jean-Christophe; Prat, Frederic; Ponchon, Thierry

    2016-01-01

    Background: Endoscopic resections have low morbidity and mortality. Delayed bleeding has been reported in approximately 1 – 15 % of cases, increasing with antiplatelet/anticoagulant therapy or portal hypertension. A self-assembling peptide (SAP) forming a gel could protect the mucosal defect during early healing. This retrospective trial aimed to assess the safety and efficacy of SAP in preventing delayed bleeding after endoscopic resections. Methods: Consecutive patients with endoscopic resections were enrolled in two tertiary referral centers. Patients with a high risk of bleeding (antiplatelet agents, anticoagulation drugs with heparin bridge therapy, and cirrhosis with portal hypertension) were also included. The SAP gel was applied immediately after resection to cover the whole ulcer bed. Results: In total, 56 patients were included with 65 lesions (esophagus [n = 8], stomach [n = 22], duodenum [n = 10], ampullary [n = 3], colon [n = 7], and rectum [n = 15]) in two centers. Among those 65 lesions, 29 were resected in high risk situations (9 uninterrupted aspirin therapy, 6 heparin bridge therapies, 5 cirrhosis and portal hypertension, 1 both cirrhosis and heparin bridge, 3 both cirrhosis and uninterrupted aspirin, 3 large duodenal lesions > 2 cm, and 2 early introduction of clopidogrel at day 1). The resection technique was endoscopic submucosal dissection (ESD) in 40 cases, en bloc endoscopic mucosal resection (EMR) in 16, piecemeal EMR in 6, and ampullectomy in 3. The mean lesion size was 37.9 mm (SD: 2.2 mm) with a mean area of 6.3 cm2 (SD: 3.5 cm2). No difficulty was noted during application. Four delayed overt bleedings occurred (6.2 %) (3 hematochezia, 1 hematemesis) requiring endoscopic hemostasis. The mean hemoglobin drop off was 0.6 g/dL (– 0.6 to 3.1 g/dL). No adverse events occurred. Conclusion: The use of this novel extracellular matrix scaffold may help to reduce post-endoscopic resection

  17. An improved recommendation algorithm via weakening indirect linkage effect

    International Nuclear Information System (INIS)

    Chen Guang; Qiu Tian; Shen Xiao-Quan

    2015-01-01

    We propose an indirect-link-weakened mass diffusion method (IMD), by considering the indirect linkage and the source object heterogeneity effect in the mass diffusion (MD) recommendation method. Experimental results on the MovieLens, Netflix, and RYM datasets show that, the IMD method greatly improves both the recommendation accuracy and diversity, compared with a heterogeneity-weakened MD method (HMD), which only considers the source object heterogeneity. Moreover, the recommendation accuracy of the cold objects is also better elevated in the IMD than the HMD method. It suggests that eliminating the redundancy induced by the indirect linkages could have a prominent effect on the recommendation efficiency in the MD method. (paper)

  18. Failing to Fulfill Tasks of Social Justice Weakens Country.

    Science.gov (United States)

    USA Today, 1981

    1981-01-01

    Presents excerpts from an interview with Walter Mondale in which the former vice president expressed fears that the United States will be weakened by current policies of removing government from the tasks of social justice. Topics discussed include social security cuts, reduction of student loans, and elimination of the legal aid program. (DB)

  19. The Dugdale solution for two unequal straight cracks weakening

    Indian Academy of Sciences (India)

    A crack arrest model is proposed for an infinite elastic perfectly-plastic plate weakened by two unequal, quasi-static, collinear straight cracks. The Dugdale model solution is obtained for the above problem when the developed plastic zones are subjected to normal cohesive quadratically varying yield point stress. Employing ...

  20. Shear weakening for different lithologies observed at different saturation stages

    Science.gov (United States)

    Diethart-Jauk, Elisabeth; Gegenhuber, Nina

    2018-01-01

    For this study, samples from different lithologies ("Leitha"-limestone, "Dachstein"-limestone, "Haupt"-dolomite, "Bunt"-sandstone, Grey Berea sandstone, granite, quartzite and basalt) were selected. Samples were dried at 70 °C, respectively 105 °C and were saturated with brine. Mass, porosity, permeability, compressional and shear wave velocity were determined from dry and brine saturated samples at laboratory conditions, based on an individual measurement program. Shear modulus was calculated to find out, if shear weakening exists for the dataset. Shear weakening means that shear modulus of dry samples is higher than of saturated samples, but it is assumed that shear modulus is unaffected by saturation. "Dachstein"-limestone and basalt show shear weakening, quartzite samples show both weakening and hardening. Granite samples are affected by temperature, after drying with 105 °C no change can be observed anymore. "Bunt"-sandstone samples show a change in the shear modulus in a small extent, although they may contain clay minerals. The other lithologies show no effect. Explanations for carbonate samples can be the complicated pore structure, for basalt it could be that weathering creates clay minerals which are known as causes for a change of the shear modulus. Fluid viscosity can also be an important factor.

  1. Special Advanced Studies for Pollution Prevention. Delivery Order 0017: Sol-Gel Surface Preparation for Carbon Steel and Stainless Steel Bonding

    National Research Council Canada - National Science Library

    Zheng, Haixing

    1997-01-01

    The objective of this program is to study the feasibility of using sol-gel active alumina coatings for the surface preparation of carbon steel and stainless steel for adhesive bonding, and to optimize...

  2. Horizontal effect of the surgical weakening of the oblique muscles

    Directory of Open Access Journals (Sweden)

    Carlos Souza-Dias

    2011-06-01

    Full Text Available PURPOSE: To evaluate the influence of the oblique muscles surgical weakening on the horizontal alignment in the primary position (PP and its efficacy on the correction of the "A" and "V" anisotropies. METHODS: In order to study the influence of bilateral superior oblique muscles (SO weakening on the horizontal alignment in PP, we analyzed the files of 12 patients who underwent only that operation; no other muscle was operated on. We took the opportunity of those 12 patients to analyze the effect of their operation on the correction of "A" incomitance. For evaluating the effect of the inferior oblique muscles (IO weakening on the correction of the "V" pattern, we analyzed retrospectively the files of 67 anisotropic patients who underwent a bilateral SO weakening. In 10 of them, the only operation was the oblique muscles weakening and, in 57 patients, the horizontal recti were also operated on for the horizontal deviations in primary position. These patients were divided into two groups: 50 were esotropic and 17 exotropic. There was not any mixed anisotropy. RESULTS: The mean value of the preoperative "V" incomitance of the 50 esotropic patients was 24.25∆ ± 10.15∆; the mean postoperative correction was 15.56 ∆ ± 8.74∆. The mean correction between the PP and upgaze was 7.52∆ ± 7.47∆ and from the PP to downgaze was 8.56∆ ± 9.21∆. The same values of the 17 exotropic patients was: preoperative 31.88∆ ± 9.4∆; primary position to upgaze was 13.11∆ ± 4.9∆ and primary position to downgaze 14.11∆ ± 12.48∆. The mean preoperative value of the "A" incomitance among the 12 patients who underwent isolated SO weakening was 30.50∆ ± 19.25∆ and the postoperative was of 9,92∆, therefore a mean correction of 22.58∆ ± 17.54∆. Among these ones, in 5 there was no alteration of the deviation in primary position, in 4 there was an exo-effect and in 3 there was an eso-effect. The mean alteration of the deviation in PP was an

  3. Weakened tropical circulation and reduced precipitation in response to geoengineering

    International Nuclear Information System (INIS)

    Ferraro, Angus J; Highwood, Eleanor J; Charlton-Perez, Andrew J

    2014-01-01

    Geoengineering by injection of reflective aerosols into the stratosphere has been proposed as a way to counteract the warming effect of greenhouse gases by reducing the intensity of solar radiation reaching the surface. Here, climate model simulations are used to examine the effect of geoengineering on the tropical overturning circulation. The strength of the circulation is related to the atmospheric static stability and has implications for tropical rainfall. The tropical circulation is projected to weaken under anthropogenic global warming. Geoengineering with stratospheric sulfate aerosol does not mitigate this weakening of the circulation. This response is due to a fast adjustment of the troposphere to radiative heating from the aerosol layer. This effect is not captured when geoengineering is modelled as a reduction in total solar irradiance, suggesting caution is required when interpreting model results from solar dimming experiments as analogues for stratospheric aerosol geoengineering. (letter)

  4. An improved recommendation algorithm via weakening indirect linkage effect

    Science.gov (United States)

    Chen, Guang; Qiu, Tian; Shen, Xiao-Quan

    2015-07-01

    We propose an indirect-link-weakened mass diffusion method (IMD), by considering the indirect linkage and the source object heterogeneity effect in the mass diffusion (MD) recommendation method. Experimental results on the MovieLens, Netflix, and RYM datasets show that, the IMD method greatly improves both the recommendation accuracy and diversity, compared with a heterogeneity-weakened MD method (HMD), which only considers the source object heterogeneity. Moreover, the recommendation accuracy of the cold objects is also better elevated in the IMD than the HMD method. It suggests that eliminating the redundancy induced by the indirect linkages could have a prominent effect on the recommendation efficiency in the MD method. Project supported by the National Natural Science Foundation of China (Grant No. 11175079) and the Young Scientist Training Project of Jiangxi Province, China (Grant No. 20133BCB23017).

  5. Flux-weakening control methods for hybrid excitation synchronous motor

    Directory of Open Access Journals (Sweden)

    Mingming Huang

    2015-09-01

    Full Text Available The hybrid excitation synchronous motor (HESM, which aim at combining the advantages of permanent magnet motor and wound excitation motor, have the characteristics of low-speed high-torque hill climbing and wide speed range. Firstly, a new kind of HESM is presented in the paper, and its structure and mathematical model are illustrated. Then, based on a space voltage vector control, a novel flux-weakening method for speed adjustment in the high speed region is presented. The unique feature of the proposed control method is that the HESM driving system keeps the q-axis back-EMF components invariable during the flux-weakening operation process. Moreover, a copper loss minimization algorithm is adopted to reduce the copper loss of the HESM in the high speed region. Lastly, the proposed method is validated by the simulation and the experimental results.

  6. Plate Like Convection with Viscous Strain Weakening and Corresponding Surface Deformation Pattern

    Science.gov (United States)

    Fuchs, L.; Becker, T. W.

    2017-12-01

    How plate tectonic surface motions are generated by mantle convection on Earth and possibly other terrestrial type planets has recently become more readily accessible with fully dynamic convection computations. However, it remains debated how plate-like the behavior in such models truly is, and in particular how the well plate boundary dynamics are captured in models which typically exclude the effects of deformation history and memory. Here, we analyze some of the effects of viscous strain weakening on plate behavior and the interactions between interior convection dynamics and surface deformation patterns. We use the finite element code CitcomCU to model convection in a 3D Cartesian model setup. The models are internally heated, with an Arrhenius-type temperature dependent viscosity including plastic yielding and viscous strain weakening (VSW) and healing (VSWH). VSW can mimic first order features of more complex damage mechanisms such as grain-size dependent rheology. Besides plate diagnostic parameters (Plateness, Mobility, and Toroidal: Poloidal ratio) to analyze the tectonic behavior our models, we also explore how "plate boundaries" link to convective patterns. In a first model series, we analyze general surface deformation patterns without VSW. In the early stages, deformation patterns are clearly co-located with up- and downwelling limbs of convection. Along downwellings strain-rates are high and localized, whereas upwellings tend to lead to broad zones of high deformation. At a more advanced stage, however, the plates' interior is highly deformed due to continuous strain accumulation and resurfaced inherited strain. Including only VSW leads to more localized deformation along downwellings. However, at a more advanced stage plate-like convection fails due an overall weakening of the material. This is prevented including strain healing. Deformation pattern at the surface more closely coincide with the internal convection patterns. The average surface

  7. Fluid thermodynamics control thermal weakening during earthquake rupture.

    Science.gov (United States)

    Acosta, M.; Passelegue, F. X.; Schubnel, A.; Violay, M.

    2017-12-01

    Although fluids are pervasive among tectonic faults, thermo-hydro-mechanical couplings during earthquake slip remain unclear. We report full dynamic records of stick-slip events, performed on saw cut Westerly Granite samples loaded under triaxial conditions at stresses representative of the upper continental crust (σ3' 70 MPa) Three fluid pressure conditions were tested, dry, low , and high pressure (i.e. Pf=0, 1, and 25 MPa). Friction (μ) evolution recorded at 10 MHz sampling frequency showed that, for a single event, μ initially increased from its static pre-stress level, μ0 to a peak value μ p it then abruptly dropped to a minimum dynamic value μd before recovering to its residual value μr, where the fault reloaded elastically. Under dry and low fluid pressure conditions, dynamic friction (μd) was extremely low ( 0.2) and co-seismic slip (δ) was large ( 250 and 200 μm respectively) due to flash heating (FH) and melting of asperities as supported by microstructures. Conversely, at pf=25 MPa, μd was higher ( 0.45), δ was smaller ( 80 μm), and frictional melting was not found. We calculated flash temperatures at asperity contacts including heat buffering by on-fault fluid. Considering the isobaric evolution of water's thermodynamic properties with rising temperature showed that pressurized water controlled fault heating and weakening, through sharp variations of specific heat (cpw) and density (ρw) at water's phase transitions. Injecting the computed flash temperatures into slip-on-a-plane model for thermal pressurization (TP) showed that: (i) if pf was low enough so that frictional heating induced liquid/vapour phase transition, FH operated, allowing very low μd during earthquakes. (ii) Conversely, if pf was high enough that shear heating induced a sharp phase transition directly from liquid to supercritical state, an extraordinary rise in water's specific heat acted as a major energy sink inhibiting FH and limiting TP, allowing higher dynamic fault

  8. Point defect weakened thermal contraction in monolayer graphene.

    Science.gov (United States)

    Zha, Xian-Hu; Zhang, Rui-Qin; Lin, Zijing

    2014-08-14

    We investigate the thermal expansion behaviors of monolayer graphene and three configurations of graphene with point defects, namely the replacement of one carbon atom with a boron or nitrogen atom, or of two neighboring carbon atoms by boron-nitrogen atoms, based on calculations using first-principles density functional theory. It is found that the thermal contraction of monolayer graphene is significantly decreased by point defects. Moreover, the corresponding temperature for negative linear thermal expansion coefficient with the maximum absolute value is reduced. The cause is determined to be point defects that enhance the mechanical strength of graphene and then reduce the amplitude and phonon frequency of the out-of-plane acoustic vibration mode. Such defect weakening of graphene thermal contraction will be useful in nanotechnology to diminish the mismatching or strain between the graphene and its substrate.

  9. Speed Regulated Continuous DTC Induction Motor Drive in Field Weakening

    Directory of Open Access Journals (Sweden)

    MATIC, P.

    2011-02-01

    Full Text Available The paper describes sensorless speed controlled continuous Direct Torque Control (DTC Induction Motor (IM drive in the field weakening regime. Drive comprises an inner torque loop and an outer speed loop. Torque control is based on Proportional - Integral (PI controller with adaptive Gain Scheduling (GS parameters. The GS PI control provides full DC link voltage utilization and a robust disturbance rejection along with a fast torque response. Outer speed loop has a PI regulator with the gains selected so as to obtain a fast and strictly aperiodic response. Proposed drive fully utilizes the available DC bus voltage. The paper comprises analytical considerations, simulation results, and detailed description of the implementation steps. Experimental verification of the proposed solution is conducted on a fixed point Digital Signal Processor (DSP platform.

  10. A Machine Approach for Field Weakening of Permanent-Magnet Motors

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, J.S.

    2000-04-02

    The commonly known technology of field weakening for permanent-magnet (PM) motors is achieved by controlling the direct-axis current component through an inverter, without using mechanical variation of the air gap, a new machine approach for field weakening of PM machines by direct control of air-gap fluxes is introduced. The demagnetization situation due to field weakening is not an issue with this new method. In fact, the PMs are strengthened at field weakening. The field-weakening ratio can reach 1O:1 or higher. This technology is particularly useful for the PM generators and electric vehicle drives.

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

    Science.gov (United States)

    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.

  12. Weakening of the North American monsoon with global warming

    Science.gov (United States)

    Pascale, Salvatore; Boos, William R.; Bordoni, Simona; Delworth, Thomas L.; Kapnick, Sarah B.; Murakami, Hiroyuki; Vecchi, Gabriel A.; Zhang, Wei

    2017-11-01

    Future changes in the North American monsoon, a circulation system that brings abundant summer rains to vast areas of the North American Southwest, could have significant consequences for regional water resources. How this monsoon will change with increasing greenhouse gases, however, remains unclear, not least because coarse horizontal resolution and systematic sea-surface temperature biases limit the reliability of its numerical model simulations. Here we investigate the monsoon response to increased atmospheric carbon dioxide (CO2) concentrations using a 50-km-resolution global climate model which features a realistic representation of the monsoon climatology and its synoptic-scale variability. It is found that the monsoon response to CO2 doubling is sensitive to sea-surface temperature biases. When minimizing these biases, the model projects a robust reduction in monsoonal precipitation over the southwestern United States, contrasting with previous multi-model assessments. Most of this precipitation decline can be attributed to increased atmospheric stability, and hence weakened convection, caused by uniform sea-surface warming. These results suggest improved adaptation measures, particularly water resource planning, will be required to cope with projected reductions in monsoon rainfall in the American Southwest.

  13. Slip weakening, strain and short-termpreseismic disturbances

    Directory of Open Access Journals (Sweden)

    V. A. Morgounov

    2004-06-01

    Full Text Available The problem of short-term earthquake precursors is discussed. In contrast to the increasing number of reports on short-lived precursors of various types, direct strain measurements cannot detect clearly expressed preseismic anomalies, as follows from the aseismic nucleation mechanism. Based on previously published data and the assumption that the attenuation of the stress-strain field is proportional to r- 3, a possible scenario of the final stage of earthquake nucleation process is proposed on the basis of the slip weakening mechanism in the source and the associated mosaic pattern of precursors on the Earth?s surface. The formulas for estimating the maximum distance of precursor detection and minimum duration of the final stage of inelastic deformation preceding brittle failure of rocks are derived. The data of electromagnetic precursors are interpreted in terms of a skin-layer model. A considerable increase in strain rates at the final stage of the earthquake nucleation provides an opportunity to explain teleseismic effects before strong earthquakes in terms of normalized epicenter distance. The modeling results are compared with in situ observations.

  14. Prevention

    DEFF Research Database (Denmark)

    Halken, S; Høst, A

    2001-01-01

    , breastfeeding should be encouraged for 4-6 months. In high-risk infants a documented extensively hydrolysed formula is recommended if exclusive breastfeeding is not possible for the first 4 months of life. There is no evidence for preventive dietary intervention neither during pregnancy nor lactation...... populations. These theories remain to be documented in proper, controlled and prospective studies. Breastfeeding and the late introduction of solid foods (>4 months) is associated with a reduced risk of food allergy, atopic dermatitis, and recurrent wheezing and asthma in early childhood. In all infants....... Preventive dietary restrictions after the age of 4-6 months are not scientifically documented....

  15. Radiotherapy gel dosimetry

    International Nuclear Information System (INIS)

    Baldock, C.

    2002-01-01

    In radiotherapy, the primary objective is to deliver a prescribed dose of radiation to a tumour or lesion within a patient while minimising the dose delivered to the surrounding healthy tissue. Traditional radiotherapy treatments usually involve simple external or internal irradiations of a tumour. External irradiations are normally achieved in the clinic with photon or electron beams produced by high energy linear accelerators. The photon or electron beams are collimated into regular shapes as they emerge from the treatment head of the unit which is supported by a gantry that can be rotated isocentrically to any position. A discrete number of photon or electron beams with different angles of incidence that intersect at the iso-centre are used to produce a region of high dose around the tumour volume (positioned at the iso-centre). Internal irradiations are normally achieved in the clinic by implanting radioactive sources in and around the tumour or lesion. Such irradiations are characterised by very high doses local to the tumour. Radioactive sources are also used to prevent post-angioplasty restenosis by inserting sources into arteries. Usually when treating a tumour, a compromise is made between tumour control and complications arising from normal tissue damage. One measure of this compromise, the therapeutic ratio, is defined as the radiation dose producing complications in 50% of patients divided by the dose providing tumour control in 50% of the patients. The therapeutic ratio depends on the radiobiological characteristics of the cancerous tissue and surrounding healthy tissues and on the radiation dose distribution achieved by the radiotherapy treatment. It is generally believed that the therapeutic ratio can be minimised by optimising the conformation of the radiation dose distribution to the target volume. This is difficult with traditional radiotherapy techniques since they do not produce dose distributions that adequately cover tumour volumes of complex

  16. Cigarette smoking weakens exercise habits in healthy men.

    Science.gov (United States)

    Nagaya, Teruo; Yoshida, Hideyo; Takahashi, Hidekatsu; Kawai, Makoto

    2007-10-01

    To investigate the longitudinal impact of smoking cessation and relapse on the exercise habits of apparently healthy Japanese men, 750 subjects presenting for a checkup at a metropolitan health center were surveyed annually for 7 years. Exercise was dichotomously classified as none or any. Subjects were grouped in two categories: 98 smokers who ceased smoking during the second year of the study, matched with 196 continuing smokers and 196 men who had never smoked; and 52 relapsed smokers (including 2 new smokers) who did not smoke at baseline or at Year 1 but smoked from Year 2 to final follow-up, matched with 104 continuing smokers and 104 never-smokers. Based on self-reported responses to questionnaires, exercise was consistently less prevalent among smokers who did not quit than among never-smokers throughout the study. Habitual exercise in subjects who had quit smoking increased during the follow-up (any exercise: 42.9% at baseline increased to 51% at final follow-up, p for longitudinal trend = .115). Habitual exercise in matched never-smokers did not change during the study and decreased significantly among persistent smokers (p = .025). Habitual exercise in relapsed smokers decreased during the follow-up (any exercise: 50.0% at baseline declined to 32.7% at final follow-up, p = .007), but habitual exercise in matched persistent smokers and never-smokers did not change. We conclude that smoking and sedentary lifestyle coexist continuously, that smoking cessation is associated with increased habitual exercise among healthy men, and that relapse is associated with reduced habitual exercise, suggesting that cigarette smoking weakens exercise habits.

  17. Black carbon reduction will weaken the aerosol net cooling effect

    Science.gov (United States)

    Wang, Z. L.; Zhang, H.; Zhang, X. Y.

    2014-12-01

    Black carbon (BC), a distinct type of carbonaceous material formed from the incomplete combustion of fossil and biomass based fuels under certain conditions, can interact with solar radiation and clouds through its strong light-absorption ability, thereby warming the Earth's climate system. Some studies have even suggested that global warming could be slowed down in a short term by eliminating BC emission due to its short lifetime. In this study, we estimate the influence of removing some sources of BC and other co-emitted species on the aerosol radiative effect by using an aerosol-climate coupled model BCC_AGCM2.0.1_CUACE/Aero, in combination with the aerosol emissions from the Representative Concentration Pathways (RCPs) scenarios. We find that the global annual mean aerosol net cooling effect at the top of the atmosphere (TOA) will be enhanced by 0.12 W m-2 compared with present-day conditions if the BC emission is reduced exclusively to the level projected for 2100 based on the RCP2.6 scenario. This will be beneficial for the mitigation of global warming. However, the global annual mean aerosol net cooling effect at the TOA will be weakened by 1.7-2.0 W m-2 relative to present-day conditions if emissions of BC and co-emitted sulfur dioxide and organic carbon are simultaneously reduced as the most close conditions to the actual situation to the level projected for 2100 in different ways based on the RCP2.6, RCP4.5, and RCP8.5 scenarios. Because there are no effective ways to remove the BC exclusively without influencing the other co-emitted components, our results therefore indicate that a reduction in BC emission can lead to an unexpected warming on the Earth's climate system in the future.

  18. The use of silicone occlusive sheeting (Sil-K) and silicone occlusive gel (epiderm) in the prevention of hypertrophic scar formation

    NARCIS (Netherlands)

    Niessen, FB; Spauwen, PHM; Robinson, PH; Fidler, [No Value; Kon, M

    The development of hypertrophic scars and keloids is an unsolved problem in the process of found healing. For this reason, a successful treatment to prevent excessive scar formation still has not been found. Over the last decade, however, a promising new treatment has been introduced. Silicone

  19. Removing water from gels

    International Nuclear Information System (INIS)

    Lane, E.S.; Winter, J.A.

    1982-01-01

    Water is removed from a gel material by contacting the gel material with an organic liquid and contacting the organic liquid with a gas such that water is taken up by the gas. The invention, in one embodiment, may be used to dry gel materials whilst maintaining an open porous network therein. In one example, the invention is applied to gel precipitated spheres containing uranium and plutonium. (author)

  20. Polymer gels and networks

    National Research Council Canada - National Science Library

    Osada, Yoshihito; Khokhlov, A. R

    2002-01-01

    ... or magnetic field, etc.). It was realized that not only can polymer gels absorb and hold a considerable volume of liquids, but they can also be forced to expel the absorbed liquid in a controlled manner. Of particular interest are hydrogels, i.e., polymer gels, which swell extensively in water. The most common hydrogels are polyelectrolyte gels: ...

  1. Antibiotic-containing hyaluronic acid gel as an antibacterial carrier: Usefulness of sponge and film-formed HA gel in deep infection.

    Science.gov (United States)

    Matsuno, Hiroaki; Yudoh, Kazuo; Hashimoto, Masamichi; Himeda, Yasukazu; Miyoshi, Teruzo; Yoshida, Kaoru; Kano, Syogo

    2006-03-01

    We have developed a novel bioabsorbable antibacterial carrier using hyaluronic acid (HA) gel for prevention and treatment of orthopedic infections. In this study, we investigated the in vivo antibacterial effects of two forms of this new material, an HA gel sponge and an HA gel film. A titanium cylinder was inserted into the intramedullary cavity of each rabbit femur, along with an HA gel sponge or HA gel film containing antibiotics. The HA gel sponge contained gentamycin, vancomycin, tobramycin, or minomycin. The HA gel film contained gentamycin or vancomycin. After 0, 7, and 14 days, the rabbit bone marrow was collected, and the antibacterial activity of the HA gel was determined by agar diffusion test. As a control, we used Septocoll, a commercially available antibacterial carrier. Both the HA gel sponge and HA gel film exhibited antibacterial activity. The present results indicate that HA gel containing antibiotics is a clinically useful bioabsorbable antibacterial carrier. Copyright 2006 Orthopaedic Research Society.

  2. Applications of gel dosimetry

    International Nuclear Information System (INIS)

    Ibbott, Geoffrey S

    2004-01-01

    Gel dosimetry has been examined as a clinical dosimeter since the 1950s. During the last two decades, however, a rapid increase in the number of investigators has been seen, and the body of knowledge regarding gel dosimetry has expanded considerably. Gel dosimetry is still considered a research project, and the introduction of this tool into clinical use is proceeding slowly. This paper will review the characteristics of gel dosimetry that make it desirable for clinical use, the postulated and demonstrated applications of gel dosimetry, and some complications, set-backs, and failures that have contributed to the slow introduction into routine clinical use

  3. Transport Phenomena in Gel

    Directory of Open Access Journals (Sweden)

    Masayuki Tokita

    2016-05-01

    Full Text Available Gel becomes an important class of soft materials since it can be seen in a wide variety of the chemical and the biological systems. The unique properties of gel arise from the structure, namely, the three-dimensional polymer network that is swollen by a huge amount of solvent. Despite the small volume fraction of the polymer network, which is usually only a few percent or less, gel shows the typical properties that belong to solids such as the elasticity. Gel is, therefore, regarded as a dilute solid because its elasticity is much smaller than that of typical solids. Because of the diluted structure, small molecules can pass along the open space of the polymer network. In addition to the viscous resistance of gel fluid, however, the substance experiences resistance due to the polymer network of gel during the transport process. It is, therefore, of importance to study the diffusion of the small molecules in gel as well as the flow of gel fluid itself through the polymer network of gel. It may be natural to assume that the effects of the resistance due to the polymer network of gel depends strongly on the network structure. Therefore, detailed study on the transport processes in and through gel may open a new insight into the relationship between the structure and the transport properties of gel. The two typical transport processes in and through gel, that is, the diffusion of small molecules due to the thermal fluctuations and the flow of gel fluid that is caused by the mechanical pressure gradient will be reviewed.

  4. Effect of Temperature-Sensitive Poloxamer Solution/Gel Material on Pericardial Adhesion Prevention: Supine Rabbit Model Study Mimicking Cardiac Surgery.

    Directory of Open Access Journals (Sweden)

    Hyun Kang

    Full Text Available We investigated the mobility of a temperature-sensitive poloxamer/Alginate/CaCl2 mixture (PACM in relation to gravity and cardiac motion and the efficacy of PACM on the prevention of pericardial adhesion in a supine rabbit model.A total of 50 rabbits were randomly divided into two groups according to materials applied after epicardial abrasion: PACM and dye mixture (group PD; n = 25 and saline as the control group (group CO; n = 25. In group PD, rabbits were maintained in a supine position with appropriate sedation, and location of mixture of PACM and dye was assessed by CT scan at the immediate postoperative period and 12 hours after surgery. The grade of adhesions was evaluated macroscopically and microscopically two weeks after surgery.In group PD, enhancement was localized in the anterior pericardial space, where PACM and dye mixture was applied, on immediate post-surgical CT scans. However, the volume of the enhancement was significantly decreased at the anterior pericardial space 12 hours later (P < .001. Two weeks after surgery, group PD had significantly lower macroscopic adhesion score (P = .002 and fibrosis score (P = .018 than did group CO. Inflammation score and expression of anti-macrophage antibody in group PD were lower than those in group CO, although the differences were not significant.In a supine rabbit model study, the anti-adhesion effect was maintained at the area of PACM application, although PACM shifted with gravity and heart motion. For more potent pericardial adhesion prevention, further research and development on the maintenance of anti-adhesion material position are required.

  5. Sol-Gel Glasses

    Science.gov (United States)

    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.

  6. Interannual Weakening of the Tropical Pacific Walker Circulation Due to Strong Tropical Volcanism

    Science.gov (United States)

    Miao, Jiapeng; Wang, Tao; Wang, Huijun; Sun, Jianqi

    2018-06-01

    In order to examine the response of the tropical Pacific Walker circulation (PWC) to strong tropical volcanic eruptions (SVEs), we analyzed a three-member long-term simulation performed with HadCM3, and carried out four additional CAM4 experiments. We found that the PWC shows a significant interannual weakening after SVEs. The cooling effect from SVEs is able to cool the entire tropics. However, cooling over the Maritime Continent is stronger than that over the central-eastern tropical Pacific. Thus, non-uniform zonal temperature anomalies can be seen following SVEs. As a result, the sea level pressure gradient between the tropical Pacific and the Maritime Continent is reduced, which weakens trade winds over the tropical Pacific. Therefore, the PWC is weakened during this period. At the same time, due to the cooling subtropical and midlatitude Pacific, the Intertropical Convergence Zone (ITCZ) and South Pacific convergence zone (SPCZ) are weakened and shift to the equator. These changes also contribute to the weakened PWC. Meanwhile, through the positive Bjerknes feedback, weakened trade winds cause El Niño-like SST anomalies over the tropical Pacific, which in turn further influence the PWC. Therefore, the PWC significantly weakens after SVEs. The CAM4 experiments further confirm the influences from surface cooling over the Maritime Continent and subtropical/midlatitude Pacific on the PWC. Moreover, they indicate that the stronger cooling over the Maritime Continent plays a dominant role in weakening the PWC after SVEs. In the observations, a weakened PWC and a related El Niño-like SST pattern can be found following SVEs.

  7. In an in-vitro model using human fetal membranes, 17-α hydroxyprogesterone caproate is not an optimal progestogen for inhibition of fetal membrane weakening.

    Science.gov (United States)

    Kumar, Deepak; Moore, Robert M; Mercer, Brian M; Mansour, Joseph M; Mesiano, Sam; Schatz, Frederick; Lockwood, Charles J; Moore, John J

    2017-12-01

    The progestogen 17-α hydroxyprogesterone caproate (17-OHPC) is 1 of only 2 agents recommended for clinical use in the prevention of spontaneous preterm delivery, and studies of its efficacy have been conflicting. We have developed an in-vitro model to study the fetal membrane weakening process that leads to rupture in preterm premature rupture of the fetal membranes (pPROM). Inflammation/infection associated with tumor necrosis factor-α (TNF-α) induction and decidual bleeding/abruption associated thrombin release are leading causes of preterm premature rupture of the fetal membranes. Both agents (TNF-α and thrombin) cause fetal membrane weakening in the model system. Furthermore, granulocyte-macrophage colony-stimulating factor (GM-CSF) is a critical intermediate for both TNF-α and thrombin-induced fetal membrane weakening. In a previous report, we demonstrated that 3 progestogens, progesterone, 17-alpha hydroxyprogesterone (17-OHP), and medroxyprogesterone acetate (MPA), each inhibit both TNF-α- and thrombin-induced fetal membrane weakening at 2 distinct points of the fetal membrane weakening pathway. Each block both the production of and the downstream action of the critical intermediate granulocyte-macrophage colony-stimulating factor. The objective of the study was to characterize the inhibitory effects of 17-OHPC on TNF-α- and thrombin-induced fetal membrane weakening in vitro. Full-thickness human fetal membrane fragments from uncomplicated term repeat cesarean deliveries were mounted in 2.5 cm Transwell inserts and cultured with/without 17-alpha hydroxyprogesterone caproate (10 -9 to 10 -7 M). After 24 hours, medium (supernatant) was removed and replaced with/without the addition of tumor necrosis factor-alpha (20 ng/mL) or thrombin (10 U/mL) or granulocyte-macrophage colony-stimulating factor (200 ng/mL). After 48 hours of culture, medium from the maternal side compartment of the model was assayed for granulocyte-macrophage colony

  8. GelTouch

    DEFF Research Database (Denmark)

    Miruchna, Viktor; Walter, Robert; Lindlbauer, David

    2015-01-01

    We present GelTouch, a gel-based layer that can selectively transition between soft and stiff to provide tactile multi-touch feedback. It is flexible, transparent when not activated, and contains no mechanical, electromagnetic, or hydraulic components, resulting in a compact form factor (a 2mm thin...... touchscreen layer for our prototype). The activated areas can be morphed freely and continuously, without being limited to fixed, predefined shapes. GelTouch consists of a poly(N-isopropylacrylamide) gel layer which alters its viscoelasticity when activated by applying heat (>32 C). We present three different...

  9. Thorium inorganic gels

    International Nuclear Information System (INIS)

    Genet, M.; Brandel, V.

    1988-01-01

    The optimum pH and concentration values of thorium salts and oxoacids or oxoacid salts which lead to transparent and stable inorganic gels have been determined. The isotherm drying process of the gel at 50 0 C leads successively to a partly dehydrated gel, then, to the formation of an unusual liquid phase and, finally to a dry amorphous solid phase which is still transparent. This kind of transparent inorganic gels and amorphous phase can be used as matrices for spectroscopic studies [fr

  10. A Psychophysiologic Study of Weakening Traumatic Combat Memories With Post-Reactivation Propranolol

    National Research Council Canada - National Science Library

    Pitman, Roger K

    2008-01-01

    ...) propranolol, will show significantly smaller psychophysiologic responses during script-driven imagery testing a week later, indicative of weakening of the emotional memory, compared to those who receive (non-reactivation...

  11. A Psychophysiologic Study of Weakening Traumatic Combat Memories With Post-Reactivation Propranolol

    National Research Council Canada - National Science Library

    Pitman, Roger K

    2008-01-01

    The objective of this project is to test whether the beta-adrenergic blocker propranolol, given following combat memory reactivation, results in a significantly greater weakening of traumatic memories...

  12. Loss of the Greatwall Kinase Weakens the Spindle Assembly Checkpoint.

    Directory of Open Access Journals (Sweden)

    M Kasim Diril

    2016-09-01

    Full Text Available The Greatwall kinase/Mastl is an essential gene that indirectly inhibits the phosphatase activity toward mitotic Cdk1 substrates. Here we show that although Mastl knockout (MastlNULL MEFs enter mitosis, they progress through mitosis without completing cytokinesis despite the presence of misaligned chromosomes, which causes chromosome segregation defects. Furthermore, we uncover the requirement of Mastl for robust spindle assembly checkpoint (SAC maintenance since the duration of mitotic arrest caused by microtubule poisons in MastlNULL MEFs is shortened, which correlates with premature disappearance of the essential SAC protein Mad1 at the kinetochores. Notably, MastlNULL MEFs display reduced phosphorylation of a number of proteins in mitosis, which include the essential SAC kinase MPS1. We further demonstrate that Mastl is required for multi-site phosphorylation of MPS1 as well as robust MPS1 kinase activity in mitosis. In contrast, treatment of MastlNULL cells with the phosphatase inhibitor okadaic acid (OKA rescues the defects in MPS1 kinase activity, mislocalization of phospho-MPS1 as well as Mad1 at the kinetochore, and premature SAC silencing. Moreover, using in vitro dephosphorylation assays, we demonstrate that Mastl promotes persistent MPS1 phosphorylation by inhibiting PP2A/B55-mediated MPS1 dephosphorylation rather than affecting Cdk1 kinase activity. Our findings establish a key regulatory function of the Greatwall kinase/Mastl->PP2A/B55 pathway in preventing premature SAC silencing.

  13. Loss of the Greatwall Kinase Weakens the Spindle Assembly Checkpoint.

    Science.gov (United States)

    Diril, M Kasim; Bisteau, Xavier; Kitagawa, Mayumi; Caldez, Matias J; Wee, Sheena; Gunaratne, Jayantha; Lee, Sang Hyun; Kaldis, Philipp

    2016-09-01

    The Greatwall kinase/Mastl is an essential gene that indirectly inhibits the phosphatase activity toward mitotic Cdk1 substrates. Here we show that although Mastl knockout (MastlNULL) MEFs enter mitosis, they progress through mitosis without completing cytokinesis despite the presence of misaligned chromosomes, which causes chromosome segregation defects. Furthermore, we uncover the requirement of Mastl for robust spindle assembly checkpoint (SAC) maintenance since the duration of mitotic arrest caused by microtubule poisons in MastlNULL MEFs is shortened, which correlates with premature disappearance of the essential SAC protein Mad1 at the kinetochores. Notably, MastlNULL MEFs display reduced phosphorylation of a number of proteins in mitosis, which include the essential SAC kinase MPS1. We further demonstrate that Mastl is required for multi-site phosphorylation of MPS1 as well as robust MPS1 kinase activity in mitosis. In contrast, treatment of MastlNULL cells with the phosphatase inhibitor okadaic acid (OKA) rescues the defects in MPS1 kinase activity, mislocalization of phospho-MPS1 as well as Mad1 at the kinetochore, and premature SAC silencing. Moreover, using in vitro dephosphorylation assays, we demonstrate that Mastl promotes persistent MPS1 phosphorylation by inhibiting PP2A/B55-mediated MPS1 dephosphorylation rather than affecting Cdk1 kinase activity. Our findings establish a key regulatory function of the Greatwall kinase/Mastl->PP2A/B55 pathway in preventing premature SAC silencing.

  14. Using fractional order method to generalize strengthening generating operator buffer operator and weakening buffer operator

    OpenAIRE

    Wu, L.; Liu, S.; Yang, Yingjie

    2016-01-01

    Traditional integer order buffer operator is extended to fractional order buffer operator, the corresponding relationship between the weakening buffer operator and the strengthening buffer operator is revealed. Fractional order buffer operator not only can generalize the weakening buffer operator and the strengthening buffer operator, but also realize tiny adjustment of buffer effect. The effectiveness of GM(1,1) with the fractional order buffer operator is validated by six cases.

  15. Cyanocobalamin Nasal Gel

    Science.gov (United States)

    ... to supply extra vitamin B12 to people who need unusually large amounts of this vitamin because they are pregnant or have certain diseases. ... Cyanocobalamin nasal gel will supply you with enough vitamin B12 only as ... it regularly. You may need to use cyanocobalamin nasal gel every week for ...

  16. Sealing wells with gel

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, E C

    1967-10-01

    A new system is being used in Mexico to temporarily plug producing wells. The temporary seal is a gel with a catalyst. The use of this temporary plug allows gas-lift wells to be taken off production in order to carry out emergency repairs. The gel solidifies by the action of the catalyst to a high temperature (70 - 150/sup 0/C). By locating the bottom of the tubing at the top of the production interval, the gel material will go into the permeable formation, and immediately set. When the gel has solidified, it seals off the horizon that must not be stimulated, and leaves the others exposed to the acid action. When the treatment is finished, the gel, by action of the catalyst, is liquefied and removed from the formation, being produced with the oil.

  17. Dislocation Motion and the Microphysics of Flash Heating and Weakening of Faults during Earthquakes

    Directory of Open Access Journals (Sweden)

    Elena Spagnuolo

    2016-07-01

    Full Text Available Earthquakes are the result of slip along faults and are due to the decrease of rock frictional strength (dynamic weakening with increasing slip and slip rate. Friction experiments simulating the abrupt accelerations (>>10 m/s2, slip rates (~1 m/s, and normal stresses (>>10 MPa expected at the passage of the earthquake rupture along the front of fault patches, measured large fault dynamic weakening for slip rates larger than a critical velocity of 0.01–0.1 m/s. The dynamic weakening corresponds to a decrease of the friction coefficient (defined as the ratio of shear stress vs. normal stress up to 40%–50% after few millimetres of slip (flash weakening, almost independently of rock type. The microstructural evolution of the sliding interfaces with slip may yield hints on the microphysical processes responsible for flash weakening. At the microscopic scale, the frictional strength results from the interaction of micro- to nano-scale surface irregularities (asperities which deform during fault sliding. During flash weakening, the visco-plastic and brittle work on the asperities results in abrupt frictional heating (flash heating and grain size reduction associated with mechano-chemical reactions (e.g., decarbonation in CO2-bearing minerals such as calcite and dolomite; dehydration in water-bearing minerals such as clays, serpentine, etc. and phase transitions (e.g., flash melting in silicate-bearing rocks. However, flash weakening is also associated with grain size reduction down to the nanoscale. Using focused ion beam scanning and transmission electron microscopy, we studied the micro-physical mechanisms associated with flash heating and nanograin formation in carbonate-bearing fault rocks. Experiments were conducted on pre-cut Carrara marble (99.9% calcite cylinders using a rotary shear apparatus at conditions relevant to seismic rupture propagation. Flash heating and weakening in calcite-bearing rocks is associated with a shock-like stress

  18. Direct weakening of tropical circulations from masked CO2 radiative forcing.

    Science.gov (United States)

    Merlis, Timothy M

    2015-10-27

    Climate models robustly simulate weakened mean circulations of the tropical atmosphere in direct response to increased carbon dioxide (CO2). The direct response to CO2, defined by the response to radiative forcing in the absence of changes in sea surface temperature, affects tropical precipitation and tropical cyclone genesis, and these changes have been tied to the weakening of the mean tropical circulation. The mechanism underlying this direct CO2-forced circulation change has not been elucidated. Here, I demonstrate that this circulation weakening results from spatial structure in CO2's radiative forcing. In regions of ascending circulation, such as the intertropical convergence zone, the CO2 radiative forcing is reduced, or "masked," by deep-convective clouds and high humidity; in subsiding regions, such as the subtropics, the CO2 radiative forcing is larger because the atmosphere is drier and deep-convective clouds are infrequent. The spatial structure of the radiative forcing reduces the need for the atmosphere to transport energy. This, in turn, weakens the mass overturning of the tropical circulation. The previously unidentified mechanism is demonstrated in a hierarchy of atmospheric general circulation model simulations with altered radiative transfer to suppress the cloud masking of the radiative forcing. The mechanism depends on the climatological distribution of clouds and humidity, rather than uncertain changes in these quantities. Masked radiative forcing thereby offers an explanation for the robustness of the direct circulation weakening under increased CO2.

  19. Bioactive materials for biomedical applications using sol-gel technology

    International Nuclear Information System (INIS)

    Gupta, Radha; Kumar, Ashok

    2008-01-01

    This review paper focuses on the sol-gel technology that has been applied in many of the potential research areas and highlights the importance of sol-gel technology for preparing bioactive materials for biomedical applications. The versatility of sol-gel chemistry enables us to manipulate the characteristics of material required for particular applications. Sol-gel derived materials have proved to be good biomaterials for coating films and for the construction of super-paramagnetic nanoparticles, bioactive glasses and fiberoptic applicators for various biomedical applications. The introduction of the sol-gel route in a conventional method of preparing implants improves the mechanical strength, biocompatibility and bioactivity of scaffolds and prevents corrosion of metallic implants. The use of organically modified silanes (ORMOSILS) yields flexible and bioactive materials for soft and hard tissue replacement. A novel approach of nitric-oxide-releasing sol-gels as antibacterial coatings for reducing the infection around orthopedic implants has also been discussed

  20. ANALISA DAYA SERAP SILIKA GEL BERBAHAN DASAR ABU SEKAM PADI

    Directory of Open Access Journals (Sweden)

    Hendriwan Fahmi

    2016-08-01

    Full Text Available Rice husk ash Silica Gel is aproduct which call be used in preventing the humidity by absorbing the water ion on the water andonthe air. This absorbing isbased onthe size, the composition and the total amount ofpolluter which contained on the Silica Gel. The purpose of making this silica gel is to seehow much thiskind of Silica Gel can absorb and compare it to the synthetic one,and also processing rise husk ashto be something useful, Ion water can be absorbed much more by using this natural silica gel if it is compared to the synthetic silica gel. This is because of its capable inabsorbing more –OHand O from water and air. Afterdoing a research with column method, silica gel was beingput in 50 ml water. Fromthis research, natural silica can absorb much more water (0.0010 gr/ml, 0.285 % water level ofweigh in comparing with synthetic one (0.008gr/ml with 0.248 %water level ofweight andsintering (0,007 gr/ml 0.253%water level and non-sintering silica gel contains 39.22 % weight of silica, 30.93 %weight of sintering silica gel, and 33.40 % of the synthetic. More silica and water level, means more total amount of absorbing. This silica gel application is considered with capability ofabsorbing andthe level of the water.

  1. Polymer gel dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Baldock, C [Institute of Medical Physics, School of Physics, University of Sydney (Australia); De Deene, Y [Radiotherapy and Nuclear Medicine, Ghent University Hospital (Belgium); Doran, S [CRUK Clinical Magnetic Resonance Research Group, Institute of Cancer Research, Surrey (United Kingdom); Ibbott, G [Radiation Physics, UT M D Anderson Cancer Center, Houston, TX (United States); Jirasek, A [Department of Physics and Astronomy, University of Victoria, Victoria, BC (Canada); Lepage, M [Centre d' imagerie moleculaire de Sherbrooke, Departement de medecine nucleaire et de radiobiologie, Universite de Sherbrooke, Sherbrooke, QC (Canada); McAuley, K B [Department of Chemical Engineering, Queen' s University, Kingston, ON (Canada); Oldham, M [Department of Radiation Oncology, Duke University Medical Center, Durham, NC (United States); Schreiner, L J [Cancer Centre of South Eastern Ontario, Kingston, ON (Canada)], E-mail: c.baldock@physics.usyd.edu.au, E-mail: yves.dedeene@ugent.be

    2010-03-07

    Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented. (topical review)

  2. Effects of Shear Fracture on In-depth Profile Modification of Weak Gels

    Institute of Scientific and Technical Information of China (English)

    Li Xianjie; Song Xinwang; Yue Xiang'an; Hou Jirui; Fang Lichun; Zhang Huazhen

    2007-01-01

    Two sand packs were filled with fine glass beads and quartz sand respectively. The characteristics of crosslinked polymer flowing through the sand packs as well as the influence of shear fracture of porous media on the in-depth profile modification of the weak gel generated from the crosslinked polymer were investigated. The results indicated that under the dynamic condition crosslinking reaction happened in both sand packs,and the weak gels in these two cases became small gel particles after water flooding. The differences were:the dynamic gelation time in the quartz sand pack was longer than that in the glass bead pack. Residual resistance factor (FRR) caused by the weak gel in the quartz sand pack was smaller than that in the glass bead pack. The weak gel became gel particles after being scoured by subsequent flood water. A weak gel with uniform apparent viscosity and sealing characteristics was generated in every part of the glass bead pack,which could not only move deeply into the sand pack but also seal the high capacity channels again when it reached the deep part. The weak gel performed in-depth profile modification in the glass bead pack,while in the quartz sand pack,the weak gel was concentrated with 100 cm from the entrance of the sand pack. When propelled by the subsequent flood water,the weak gel could move towards the deep part of the sand pack but then became tiny gel particles and could not effectively seal the high capacity channels there. The in-depth profile modification of the weak gel was very weak in the quartz sand pack. It was the shear fracture of porous media that mainly affected the properties and weakened the in-depth profile modification of the weak gel.

  3. Strong Velocity-Weakening of Nanograins at High Slip-Rates

    Science.gov (United States)

    Han, R.; Hirose, T.; Ando, J.

    2008-12-01

    It has been observed that slip localization zones in some experimental and natural faults consist of crystalline or amorphous nanograins of different minerals. Prolonged grinding of silicate rocks (e.g., quartz rock and granite) is known to produce amorphous silica nanograins and mechanical properties of the material (especially under wet condition) have been attributed to a mechanism of fault weakening. Also, recent high- velocity friction tests on carbonate rocks showed that faults can be weakened by thermal decomposition of calcite into nanograins of lime and carbon dioxide and the lubrication effect of the nanograins would be critical for the fault weakening. However, mechanical behavior(s) and friction mechanism(s) of fault slip zones with nanograins, especially at high slip-rates, are still poorly understood, despite their potential importance to the understanding of seismic faulting. In this contribution, we show you our experimental results indicating velocity-weakening of nanograins (probably caused by still unknown mechanical behaviors of nanograins) rather than by temperature-related weakening behavior. In our high-velocity friction tests on Carrara marble at seismic slip-rates, we have tried to "cool" the simulated fault with liquid nitrogen and compressed air during frictional sliding, and found, in the simulated fault coated with nanopowders of lime (CaO) formed by thermal decomposition, no correlation between friction and temperature measured with thermocouples (i.e., no temperature-related weakening behavior), although strong "velocity-weakening" behavior appeared. The observation was confirmed by another experiment: from (1) the calculated "maximum" sliding surface temperature [Carslaw and Jaeger, 1959] using the mechanical data, with an assumption of strong slip localization into a very thin layer, and (2) the measured temperature with thermocouples at a place just below the sliding surface and close to the periphery of the specimen, it was found

  4. Design of Autonomous Gel Actuators

    Directory of Open Access Journals (Sweden)

    Shuji Hashimoto

    2011-01-01

    Full Text Available In this paper, we introduce autonomous gel actuators driven by chemical energy. The polymer gels prepared here have cyclic chemical reaction networks. With a cyclic reaction, the polymer gels generate periodical motion. The periodic motion of the gel is produced by the chemical energy of the oscillatory Belouzov-Zhabotinsky (BZ reaction. We have succeeded in making synthetic polymer gel move autonomously like a living organism. This experimental fact represents the great possibility of the chemical robot.

  5. Review of Fricke gel dosimeters

    International Nuclear Information System (INIS)

    Schreiner, L J

    2004-01-01

    The innovation of adding a gel matrix to the traditional Fricke dosimeter to stabilize geometric information established the field of gel dosimetry for radiation therapy. A discussion of Fricke gels provides an overview of the issues that determine the dose response of all gel dosimeters in general. In this paper we review some of the features of Fricke systems to illustrate these issues and, in addition, to motivate renewed clinical interest in Fricke gels

  6. 3D MR gel dosimetry with lung equivalent gel

    International Nuclear Information System (INIS)

    Scherer, J.; Solleder, M.; Schiessl, I.; Bogner, L.; Herbst, M.

    1998-01-01

    The MR gel dosimetry is used to verify complex 3D treatment plans. Till now this method served only for dose evaluation in homogeneous phantoms. On the way to build a heterogeneous anthropomorphic gel phantom, a lung equivalent gel with the density 0.4 g/cm 3 was developed. First experiments show a 1.55 times higher dose reponse in the low density gel (LD gel). The comparison of a dose distribution in a gel/LD gel/gel slab phantom with Monte Carlo calculations shows good agreement within 5%. More over the accuray of the measuring device magnetic resonance imager was studied in respect to the now exclusive digital image processing with the software MRD (MR dosimetry). Because of the dimensions of the Fricke gel phantom an artefact correction, based on the data from the unirradiated phantom proved to be essential. (orig.) [de

  7. Structure of mineral gels

    International Nuclear Information System (INIS)

    Miranda Salvado, I.M.; Margaca, F.M.A.; Teixeira, J.

    1999-01-01

    Small Angle Neutron Scattering (SANS) measurements have been performed to investigate the nanoscale structure of materials of the systems xTiO 2 -(1-x)SiO 2 and xZrO 2 -(1-x)SiO 2 with x ≤ 10 mol % at different processing stages. The materials were prepared by sol-gel using the alkoxides method, in strong acidic conditions. Samples were studied as xerogels heat-treated at 120 and 850 deg. C and as wet gels at gel point and after aging. All samples showed identical microstructure at gel point, extended linear chains ∼10 nm long. The aged gel has a mass fractal structure with fractal dimension of 1.7 - 1.9. The 120 deg. C heat-treated xerogels show homogeneous oxide regions with mass fractal structure. For the 850 deg. C heat-treated xerogel the oxide regions average size has reduced and it has densified as compared to 120 deg. C heat-treated sample. (author)

  8. Mucosal effects of tenofovir 1% gel.

    Science.gov (United States)

    Hladik, Florian; Burgener, Adam; Ballweber, Lamar; Gottardo, Raphael; Vojtech, Lucia; Fourati, Slim; Dai, James Y; Cameron, Mark J; Strobl, Johanna; Hughes, Sean M; Hoesley, Craig; Andrew, Philip; Johnson, Sherri; Piper, Jeanna; Friend, David R; Ball, T Blake; Cranston, Ross D; Mayer, Kenneth H; McElrath, M Juliana; McGowan, Ian

    2015-02-03

    Tenofovir gel is being evaluated for vaginal and rectal pre-exposure prophylaxis against HIV transmission. Because this is a new prevention strategy, we broadly assessed its effects on the mucosa. In MTN-007, a phase-1, randomized, double-blinded rectal microbicide trial, we used systems genomics/proteomics to determine the effect of tenofovir 1% gel, nonoxynol-9 2% gel, placebo gel or no treatment on rectal biopsies (15 subjects/arm). We also treated primary vaginal epithelial cells from four healthy women with tenofovir in vitro. After seven days of administration, tenofovir 1% gel had broad-ranging effects on the rectal mucosa, which were more pronounced than, but different from, those of the detergent nonoxynol-9. Tenofovir suppressed anti-inflammatory mediators, increased T cell densities, caused mitochondrial dysfunction, altered regulatory pathways of cell differentiation and survival, and stimulated epithelial cell proliferation. The breadth of mucosal changes induced by tenofovir indicates that its safety over longer-term topical use should be carefully monitored.

  9. Slow oil shocks and the 'weakening of the oil price-macroeconomy relationship'

    International Nuclear Information System (INIS)

    Naccache, Theo

    2010-01-01

    Many papers have been documenting and analysing the asymmetry and the weakening of the oil price-macroeconomy relationship as off the early eighties. While there seems to be a consensus about the factors causing the asymmetry, namely adjustment costs which offset the benefits of low energy prices, the debate about the weakening of the relationship is not over yet. Moreover, the alternative oil price specifications which have been proposed by, and to restore the stability of the relationship fail to Granger cause output or unemployment in post-1980 data. By using the concept of accelerations of the oil price, we show that the weakening of this relationship corresponds to the appearance of slow oil price increases, which have less impact on the economy. When filtering out these slow oil price variations from the sample, we manage to rehabilitate the causality running from the oil price to the macroeconomy and show that far from weakening, the oil price accelerations-GDP relationship has even been growing stronger since the early eighties. (author)

  10. Perception of a Regional Spanish Sound: The Case of /s/-Weakening

    Science.gov (United States)

    George, Angela

    2014-01-01

    While taking foreign language classes or interacting in the target language community, language learners will be exposed to dialectal differences. This paper addresses how adult learners of Spanish in beginning, intermediate, and advanced Spanish courses at a large US university perceived a common sociolinguistic feature of Spanish, /s/-weakening,…

  11. Field weakening performance of flux-switching machines for hybrid/electric vehicles

    NARCIS (Netherlands)

    Tang, Y.; Paulides, J.J.H.; Lomonova, E.A.

    2015-01-01

    Flux-switching machines (FSMs) are a viable candidate for electric propulsion of hybrid/electric vehicles. This paper investigates the field weakening performance of FSMs. The investigation starts with general torque and voltage expressions, which reveal the relationships between certain parameters

  12. Dislocation motion and the microphysics of flash heating and weakening of faults during earthquakes

    NARCIS (Netherlands)

    Spagnuolo, Elena; Plümper, Oliver; Violay, Marie; Cavallo, Andrea; Di Toro, Giulio

    2016-01-01

    Earthquakes are the result of slip along faults and are due to the decrease of rock frictional strength (dynamic weakening) with increasing slip and slip rate. Friction experiments simulating the abrupt accelerations (>>10 m/s2), slip rates (~1 m/s), and normal stresses (>>10 MPa) expected at the

  13. Solutions of weakened field equations in Gödel space-time

    Directory of Open Access Journals (Sweden)

    Aditya Mani Mishra

    2019-04-01

    Full Text Available We have solved Weakened field equations, collected work of Lovelock for cylindrically symmetric G¨odel type spacetime. A comparative study of these solutions to solution of Einstein’s field equation have shown. Conformality of Gödel spacetime has discussed with vanishing and non-vanishing scalar curvature of the spacetime.

  14. Gel electrolytes and electrodes

    Science.gov (United States)

    Fleischmann, Sven; Bunte, Christine; Mikhaylik, Yuriy V.; Viner, Veronika G.

    2017-09-05

    Gel electrolytes, especially gel electrolytes for electrochemical cells, are generally described. In some embodiments, the gel electrolyte layers comprise components a) to c). Component a) may be at least one layer of at least one polymer comprising polymerized units of: a1) at least one monomer containing an ethylenically unsaturated unit and an amido group and a2) at least one crosslinker. Component b) may be at least one conducting salt and component c) may be at least one solvent. Electrodes may comprise the components a), d) and e), wherein component a) may be at least one layer of at least one polymer as described herein. Component d) may be at least one electroactive layer and component e) may be at least one ceramic layer. Furthermore, electrochemical cells comprising component a) which may be at least one layer of at least one polymer as described herein, are also provided.

  15. Electroblotting from Polyacrylamide Gels.

    Science.gov (United States)

    Goldman, Aaron; Ursitti, Jeanine A; Mozdzanowski, Jacek; Speicher, David W

    2015-11-02

    Transferring proteins from polyacrylamide gels onto retentive membranes is now primarily used for immunoblotting. A second application that was quite common up to about a decade ago was electroblotting of proteins for N-terminal and internal sequencing using Edman chemistry. This unit contains procedures for electroblotting proteins from polyacrylamide gels onto a variety of membranes, including polyvinylidene difluoride (PVDF) and nitrocellulose. In addition to the commonly used tank or wet transfer system, protocols are provided for electroblotting using semidry and dry systems. This unit also describes procedures for eluting proteins from membranes using detergents or acidic extraction with organic solvents for specialized applications. Copyright © 2015 John Wiley & Sons, Inc.

  16. The Role of Compliance and Reaction Rate in Dehydration Weakening and Frictional Stability of Antigorite

    Science.gov (United States)

    Burdette, E.; Okazaki, K.; Hirth, G.

    2017-12-01

    The complicated brittle-ductile rheology of antigorite at subduction zone pressures and temperatures, resulting from its anisotropic mechanical properties, low dehydration temperature, and high water content has made interpretation of dehydration weakening problematic. Recent analyses indicate that antigorite is both ductile and brittle at high temperatures, and follows effective pressure frictional laws while dehydrating. In this study we focus on the role of rig compliance and reaction kinetics on frictional weakening and frictional stability. In addition, we correlate the evolution of mechanical behavior with AE activity at conditions within and above the thermal stability limit of antigorite. We conducted experiments at confining pressures from 0.25 GPa to 1GPa in a Griggs apparatus and modified rig compliance by including compliant components within the loading frame. We also modeled in-situ reaction progress using parameters from Sawai et al. (2013) to quantify relationships between weakening and fluid production. Without modifying the compliance, low pressure runs show stable dehydration weakening. With a modified, low compliance, results were nearly identical to stable weakening at standard compliance at 1 GPa. However, at lower pressures, many acoustic emissions were recorded at peak reaction rates during temperature ramping, with a rapid failure event occurring several minutes afterward (with the caveat that we still need to verify that AEs occur within the sample). No AEs are observed during room temperature experiments in samples that fault, nor were any observed in the high temperature experiments at conditions within the antigorite stability field - consistent with prior studies. Our results demonstrate that understanding in-situ dehydration reaction kinetics and their feedback with rheology and system compliance are key to scaling laboratory antigorite rheology to earth.

  17. gel template method

    Indian Academy of Sciences (India)

    TiO2 nanotubes have been synthesized by sol–gel template method using alumina membrane. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, UV absorption spectrum and X-ray diffraction techniques have been used to investigate the structure, morphology and optical ...

  18. Transdermal delivery of paeonol using cubic gel and microemulsion gel

    Science.gov (United States)

    Luo, Maofu; Shen, Qi; Chen, Jinjin

    2011-01-01

    Background The aim of this study was to develop new systems for transdermal delivery of paeonol, in particular microemulsion gel and cubic gel formulations. Methods Various microemulsion vehicles were prepared using isopropyl myristate as an oil phase, polyoxyethylated castor oil (Cremophor® EL) as a surfactant, and polyethylene glycol 400 as a cosurfactant. In the optimum microemulsion gel formulation, carbomer 940 was selected as the gel matrix, and consisted of 1% paeonol, 4% isopropyl myristate, 28% Cremophor EL/polyethylene glycol 400 (1:1), and 67% water. The cubic gel was prepared containing 3% paeonol, 30% water, and 67% glyceryl monooleate. Results A skin permeability test using excised rat skins indicated that both the cubic gel and microemulsion gel formulations had higher permeability than did the paeonol solution. An in vivo pharmacokinetic study done in rats showed that the relative bioavailability of the cubic gel and microemulsion gel was enhanced by about 1.51-fold and 1.28-fold, respectively, compared with orally administered paeonol suspension. Conclusion Both the cubic gel and microemulsion gel formulations are promising delivery systems to enhance the skin permeability of paeonol, in particular the cubic gel. PMID:21904450

  19. Weakened cyclones, intensified anticyclones and recent extreme cold winter weather events in Eurasia

    International Nuclear Information System (INIS)

    Zhang Xiangdong; Lu Chuhan; Guan Zhaoyong

    2012-01-01

    Extreme cold winter weather events over Eurasia have occurred more frequently in recent years in spite of a warming global climate. To gain further insight into this regional mismatch with the global mean warming trend, we analyzed winter cyclone and anticyclone activities, and their interplay with the regional atmospheric circulation pattern characterized by the semi-permanent Siberian high. We found a persistent weakening of both cyclones and anticyclones between the 1990s and early 2000s, and a pronounced intensification of anticyclone activity afterwards. It is suggested that this intensified anticyclone activity drives the substantially strengthening and northwestward shifting/expanding Siberian high, and explains the decreased midlatitude Eurasian surface air temperature and the increased frequency of cold weather events. The weakened tropospheric midlatitude westerlies in the context of the intensified anticyclones would reduce the eastward propagation speed of Rossby waves, favoring persistence and further intensification of surface anticyclone systems. (letter)

  20. On the relative significance of lithospheric weakening mechanisms for sustained plate tectonics

    Science.gov (United States)

    Araceli Sanchez-Maes, Sophia

    2018-01-01

    Plate tectonics requires the bending of strong plates at subduction zones, which is difficult to achieve without a secondary weakening mechanism. Two classes of weakening mechanisms have been proposed for the generation of ongoing plate tectonics, distinguished by whether or not they require water. Here we show that the energy budget of global subduction zones offers a simple yet decisive test on their relative significance. Theoretical studies of mantle convection suggest bending dissipation to occupy only 10-20 % of total dissipation in the mantle, and our results indicate that the hydrous mechanism in the shallow part of plates is essential to satisfy the requirement. Thus, surface oceans are required for the long-term operation of plate tectonics on terrestrial worlds. Establishing this necessary and observable condition for sustained plate tectonics carries important implications for planetary habitability at large.

  1. Frictional velocity-weakening in landslides on Earth and on other planetary bodies.

    Science.gov (United States)

    Lucas, Antoine; Mangeney, Anne; Ampuero, Jean Paul

    2014-03-04

    One of the ultimate goals in landslide hazard assessment is to predict maximum landslide extension and velocity. Despite much work, the physical processes governing energy dissipation during these natural granular flows remain uncertain. Field observations show that large landslides travel over unexpectedly long distances, suggesting low dissipation. Numerical simulations of landslides require a small friction coefficient to reproduce the extension of their deposits. Here, based on analytical and numerical solutions for granular flows constrained by remote-sensing observations, we develop a consistent method to estimate the effective friction coefficient of landslides. This method uses a constant basal friction coefficient that reproduces the first-order landslide properties. We show that friction decreases with increasing volume or, more fundamentally, with increasing sliding velocity. Inspired by frictional weakening mechanisms thought to operate during earthquakes, we propose an empirical velocity-weakening friction law under a unifying phenomenological framework applicable to small and large landslides observed on Earth and beyond.

  2. Substantiation of effectiveness of trainings on health related methodic for students with weakened motor fitness

    Directory of Open Access Journals (Sweden)

    V.A. Kuzmin

    2015-12-01

    Full Text Available Purpose: to work out methodic, facilitating successful conduct of health related trainings of students withy weakened motor (physical fitness. Material: in the research 47 students with weakened motor fitness participated. Analysis of indicators of morbidity frequency and duration was carried out on the base of medical records’ studying during all academic year. Experimental methodic consisted of three chapters: execution of specifically selected Hatha yoga static postures, breathing exercises and boxing techniques. Breathing exercises were grouped in four complexes. Every complex was fulfilled during 6 trainings, after each of them the next followed. Results: it was found that frequency and duration of diseases statistically confidently decreased in academic year. It was shown that formation of healthy life style skills statistically confidently improved. Conclusions: we have determined: increased students’ interest to physical culture practicing; reduction of frequency and duration of diseases; higher level of formation of healthy life style skills.

  3. Enhanced or Weakened Western North Pacific Subtropical High under Global Warming?

    OpenAIRE

    He, Chao; Zhou, Tianjun; Lin, Ailan; Wu, Bo; Gu, Dejun; Li, Chunhui; Zheng, Bin

    2015-01-01

    The Western North Pacific Subtropical High (WNPSH) regulates East Asian climate in summer. Anomalous WNPSH causes floods, droughts and heat waves in China, Japan and Korea. The potential change of the WNPSH under global warming is concerned by Asian people, but whether the WNPSH would be enhanced or weakened remains inconclusive. Based on the multi-model climate change projection from the 5th phase of Coupled Model Intercomparison Project (CMIP5), we show evidences that the WNPSH tends to wea...

  4. Dynamic weakening of serpentinite gouges and bare surfaces at seismic slip rates

    Science.gov (United States)

    Proctor, B. P.; Mitchell, T. M.; Hirth, G.; Goldsby, D.; Zorzi, F.; Platt, J. D.; Di Toro, G.

    2014-11-01

    To investigate differences in the frictional behavior between initially bare rock surfaces of serpentinite and powdered serpentinite ("gouge") at subseismic to seismic slip rates, we conducted single-velocity step and multiple-velocity step friction experiments on an antigorite-rich and lizardite-rich serpentinite at slip rates (V) from 0.003 m/s to 6.5 m/s, sliding displacements up to 1.6 m, and normal stresses (σn) up to 22 MPa for gouge and 97 MPa for bare surfaces. Nominal steady state friction values (μnss) in gouge at V = 1 m/s are larger than in bare surfaces for all σn tested and demonstrate a strong σn dependence; μnss decreased from 0.51 at 4.0 MPa to 0.39 at 22.4 MPa. Conversely, μnss values for bare surfaces remained ~0.1 with increasing σn and V. Additionally, the velocity at the onset of frictional weakening and the amount of slip prior to weakening were orders of magnitude larger in gouge than in bare surfaces. Extrapolation of the normal stress dependence for μnss suggests that the behavior of antigorite gouge approaches that of bare surfaces at σn ≥ 60 MPa. X-ray diffraction revealed dehydration reaction products in samples that frictionally weakened. Microstructural analysis revealed highly localized slip zones with melt-like textures in some cases gouge experiments and in all bare surfaces experiments for V ≥ 1 m/s. One-dimensional thermal modeling indicates that flash heating causes frictional weakening in both bare surfaces and gouge. Friction values for gouge decrease at higher velocities and after longer displacements than bare surfaces because strain is more distributed.

  5. Investigation of multi-scale flash-weakening of rock surfaces during high speed slip

    Science.gov (United States)

    Barbery, M. R.; Saber, O.; Chester, F. M.; Chester, J. S.

    2017-12-01

    A significant reduction in the coefficient of friction of rock can occur if sliding velocity approaches seismic rates as a consequence of weakening of microscopic sliding contacts by flash heating. Using a high-acceleration and -speed biaxial apparatus equipped with a high-speed Infra-Red (IR) camera to capture thermographs of the sliding surface, we have documented the heterogeneous distribution of temperature on flash-heated decimetric surfaces characterized by linear arrays of high-temperature, mm-size spots, and streaks. Numerical models that are informed by the character of flash heated surfaces and that consider the coupling of changes in temperature and changes in the friction of contacts, supports the hypothesis that independent mechanisms of flash weakening operate at different contact scales. Here, we report on new experiments that provide additional constraints on the life-times and rest-times of populations of millimeter-scale contacts. Rock friction experiments conducted on Westerly granite samples in a double-direct shear configuration achieve velocity steps from 1 mm/s to 900 mm/s at 100g accelerations over 2 mm of displacement with normal stresses of 22-36 MPa and 30 mm of displacement during sustained high-speed sliding. Sliding surfaces are machined to roughness similar to natural fault surfaces and that allow us to control the characteristics of millimeter-scale contact populations. Thermographs of the sliding surface show temperatures up to 200 C on millimeter-scale contacts, in agreement with 1-D heat conduction model estimates of 180 C. Preliminary comparison of thermal modeling results and experiment observations demonstrate that we can distinguish the different life-times and rest-times of contacts in thermographs and the corresponding frictional weakening behaviors. Continued work on machined surfaces that lead to different contact population characteristics will be used to test the multi-scale and multi-mechanism hypothesis for flash

  6. Seismological evidence of fault weakening due to erosion by fluids from observations of intraplate earthquake swarms

    Czech Academy of Sciences Publication Activity Database

    Vavryčuk, Václav; Hrubcová, Pavla

    2017-01-01

    Roč. 122, č. 5 (2017), s. 3701-3718 ISSN 2169-9313 R&D Projects: GA MŠk(CZ) LM2015079; GA ČR GC16-19751J; GA ČR GA17-19297S Institutional support: RVO:67985530 Keywords : earthquke swarm * seismic cycle * moment tensor * fault weakening * fluids Subject RIV: DC - Siesmology, Volcanology, Earth Structure OBOR OECD: Volcanology Impact factor: 3.350, year: 2016

  7. Simplified Fuzzy Control for Flux-Weakening Speed Control of IPMSM Drive

    Directory of Open Access Journals (Sweden)

    M. J. Hossain

    2011-01-01

    Full Text Available This paper presents a simplified fuzzy logic-based speed control scheme of an interior permanent magnet synchronous motor (IPMSM above the base speed using a flux-weakening method. In this work, nonlinear expressions of d-axis and q-axis currents of the IPMSM have been derived and subsequently incorporated in the control algorithm for the practical purpose in order to implement fuzzy-based flux-weakening strategy to operate the motor above the base speed. The fundamentals of fuzzy logic algorithms as related to motor control applications are also illustrated. A simplified fuzzy speed controller (FLC for the IPMSM drive has been designed and incorporated in the drive system to maintain high performance standards. The efficacy of the proposed simplified FLC-based IPMSM drive is verified by simulation at various dynamic operating conditions. The simplified FLC is found to be robust and efficient. Laboratory test results of proportional integral (PI controller-based IPMSM drive have been compared with the simulated results of fuzzy controller-based flux-weakening IPMSM drive system.

  8. Design and Optimization of IPM Motor Considering Flux Weakening Capability and Vibration for Electric Vehicle Applications

    Directory of Open Access Journals (Sweden)

    Fangwu Ma

    2018-05-01

    Full Text Available As motor design is key to the development of electric vehicles (EVs and hybrid EVs (HEVs, it has recently become the subject of considerable interest. Interior permanent magnet (IPM motors offer advantages such as high torque density and high efficiency, benefiting from both permanent magnet (PM torque and reluctance torque. However an obvious disadvantage of IPM motors is that operation at high speed involves difficulties in achieving the required flux-weakening capability and low vibration. This study focuses on optimizing the flux-weakening performance and reducing the vibration of an IPM motor for EVs. Firstly, flux-weakening capability, cogging torque, torque ripple, and radical vibration force are analyzed based on the mathematical model. Secondly, three kinds of motors are optimized by the genetic algorithm and analyzed, providing visible insights into the contribution of different rotor structures to the torque characteristics, efficiency, and extended speed range. Thirdly, a slotted rotor configuration is proposed to reduce the torque ripple and radical vibration force. The flux density distributions are discussed, explaining the principle that motors with slotted rotors and stator skew slots have smaller torque ripple and radical vibration force. Lastly, the design and optimization results have been validated against experiments.

  9. A new method for weakening the combined effect of residual errors on multibeam bathymetric data

    Science.gov (United States)

    Zhao, Jianhu; Yan, Jun; Zhang, Hongmei; Zhang, Yuqing; Wang, Aixue

    2014-12-01

    Multibeam bathymetric system (MBS) has been widely applied in the marine surveying for providing high-resolution seabed topography. However, some factors degrade the precision of bathymetry, including the sound velocity, the vessel attitude, the misalignment angle of the transducer and so on. Although these factors have been corrected strictly in bathymetric data processing, the final bathymetric result is still affected by their residual errors. In deep water, the result usually cannot meet the requirements of high-precision seabed topography. The combined effect of these residual errors is systematic, and it's difficult to separate and weaken the effect using traditional single-error correction methods. Therefore, the paper puts forward a new method for weakening the effect of residual errors based on the frequency-spectrum characteristics of seabed topography and multibeam bathymetric data. Four steps, namely the separation of the low-frequency and the high-frequency part of bathymetric data, the reconstruction of the trend of actual seabed topography, the merging of the actual trend and the extracted microtopography, and the accuracy evaluation, are involved in the method. Experiment results prove that the proposed method could weaken the combined effect of residual errors on multibeam bathymetric data and efficiently improve the accuracy of the final post-processing results. We suggest that the method should be widely applied to MBS data processing in deep water.

  10. Fracture resistance of weakened teeth restored with condensable resin with and without cusp coverage

    Directory of Open Access Journals (Sweden)

    Rafael Francisco Lia Mondelli

    2009-06-01

    Full Text Available OBJECTIVES: This in vitro study evaluated the fracture resistance of weakened human premolars (MOD cavity preparation and pulp chamber roof removal restored with condensable resin composite with and without cusp coverage. MATERIAL AND METHODS: Thirty human maxillary premolars were divided into three groups: Group A (control, sound teeth; Group B, wide MOD cavities prepared and the pulp chamber roof removed and restored with resin composite without cusp coverage; Group C, same as Group B with 2.0 mm of buccal and palatal cusps reduced and restored with the same resin. The teeth were included in metal rings with self-curing acrylic resin, stored in water for 24 h and thereafter subjected to a compressive axial load in a universal testing machine at 0.5 mm/min. RESULTS: The mean fracture resistance values ± standart deviation (kgf were: group A: 151.40 ± 55.32, group B: 60.54 ± 12.61, group C: 141.90 ± 30.82. Statistically significant differences were found only between Group B and the other groups (p<0.05. The condensable resin restoration of weakened human premolars with cusp coverage significantly increased the fracture resistance of the teeth as compared to teeth restored without cusp coverage. CONCLUSION: The results showed that cusp coverage with condensable resin might be a safe option for restoring weakened endodontically treated teeth.

  11. The Gel Generator option

    International Nuclear Information System (INIS)

    Boyd, R.E.

    1999-01-01

    The development of a national policy for guaranteeing an ample supply of 99m Tc to nuclear medicine, involves issues which go beyond the means by which radioactivation is achieved. Indeed, in such an exercise the pragmatic dictates of business and the sensitivities of politics must also be taken into account. Furthermore where a preference towards the nuclear reactor or the potential of cyclotrons is being questioned, the debate is incomplete if the only options that are considered are the fission-based 99 Mo generator versus the direct cyclotron production of 99m Tc. There is a third option (also neutron γ-based), an alternative to the fission 99 Mo generator, which ought not be overlooked. The application of low specific activity (n,γ) 99 Mo to a new type of generator, the Gel Generator, has been the focus of much research, particularly in Australia and more recently in China. After the initial concept had been established in the laboratory, the Australian researchers then undertook a comprehensive program of tests on the Gel Generator to assess its potential, either in the clinical laboratory or the centralised radiopharmacy, for supplying 99m Tc suitable for nuclear medicine. The outcome of this program was a clear indication that the Gel Generator innovation had the capability to provide both technical and economic advantages to the nuclear medicine industry. These advantages are described. Since that time the Gel Generator has been selected for routine use in China where it now satisfies more than 30% of the 99m Tc demand. (author)

  12. Caffeine-catalyzed gels.

    Science.gov (United States)

    DiCiccio, Angela M; Lee, Young-Ah Lucy; Glettig, Dean L; Walton, Elizabeth S E; de la Serna, Eva L; Montgomery, Veronica A; Grant, Tyler M; Langer, Robert; Traverso, Giovanni

    2018-07-01

    Covalently cross-linked gels are utilized in a broad range of biomedical applications though their synthesis often compromises easy implementation. Cross-linking reactions commonly utilize catalysts or conditions that can damage biologics and sensitive compounds, producing materials that require extensive post processing to achieve acceptable biocompatibility. As an alternative, we report a batch synthesis platform to produce covalently cross-linked materials appropriate for direct biomedical application enabled by green chemistry and commonly available food grade ingredients. Using caffeine, a mild base, to catalyze anhydrous carboxylate ring-opening of diglycidyl-ether functionalized monomers with citric acid as a tri-functional crosslinking agent we introduce a novel poly(ester-ether) gel synthesis platform. We demonstrate that biocompatible Caffeine Catalyzed Gels (CCGs) exhibit dynamic physical, chemical, and mechanical properties, which can be tailored in shape, surface texture, solvent response, cargo release, shear and tensile strength, among other potential attributes. The demonstrated versatility, low cost and facile synthesis of these CCGs renders them appropriate for a broad range of customized engineering applications including drug delivery constructs, tissue engineering scaffolds, and medical devices. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. Chiromagnetic nanoparticles and gels

    Science.gov (United States)

    Yeom, Jihyeon; Santos, Uallisson S.; Chekini, Mahshid; Cha, Minjeong; de Moura, André F.; Kotov, Nicholas A.

    2018-01-01

    Chiral inorganic nanostructures have high circular dichroism, but real-time control of their optical activity has so far been achieved only by irreversible chemical changes. Field modulation is a far more desirable path to chiroptical devices. We hypothesized that magnetic field modulation can be attained for chiral nanostructures with large contributions of the magnetic transition dipole moments to polarization rotation. We found that dispersions and gels of paramagnetic Co3O4 nanoparticles with chiral distortions of the crystal lattices exhibited chiroptical activity in the visible range that was 10 times as strong as that of nonparamagnetic nanoparticles of comparable size. Transparency of the nanoparticle gels to circularly polarized light beams in the ultraviolet range was reversibly modulated by magnetic fields. These phenomena were also observed for other nanoscale metal oxides with lattice distortions from imprinted amino acids and other chiral ligands. The large family of chiral ceramic nanostructures and gels can be pivotal for new technologies and knowledge at the nexus of chirality and magnetism.

  14. Strain Localization and Weakening Processes in Viscously Deforming Rocks: Numerical Modeling Based on Laboratory Torsion Experiments

    Science.gov (United States)

    Doehmann, M.; Brune, S.; Nardini, L.; Rybacki, E.; Dresen, G.

    2017-12-01

    Strain localization is an ubiquitous process in earth materials observed over a broad range of scales in space and time. Localized deformation and the formation of shear zones and faults typically involves material softening by various processes, like shear heating and grain size reduction. Numerical modeling enables us to study the complex physical and chemical weakening processes by separating the effect of individual parameters and boundary conditions. Using simple piece-wise linear functions for the parametrization of weakening processes allows studying a system at a chosen (lower) level of complexity (e.g. Cyprych et al., 2016). In this study, we utilize a finite element model to test two weakening laws that reduce the strength of the material depending on either the I) amount of accumulated strain or II) deformational work. Our 2D Cartesian models are benchmarked to single inclusion torsion experiments performed at elevated temperatures of 900 °C and pressures of up to 400 MPa (Rybacki et al., 2014). The experiments were performed on Carrara marble samples containing a weak Solnhofen limestone inclusion at a maximum strain rate of 2.0*10-4 s-1. Our models are designed to reproduce shear deformation of a hollow cylinder equivalent to the laboratory setup, such that material leaving one side of the model in shear direction enters again on the opposite side using periodic boundary conditions. Similar to the laboratory tests, we applied constant strain rate and constant stress boundary conditions.We use our model to investigate the time-dependent distribution of stress and strain and the effect of different parameters. For instance, inclusion rotation is shown to be strongly dependent on the viscosity ratio between matrix and inclusion and stronger ductile weakening increases the localization rate while decreasing shear zone width. The most suitable weakening law for representation of ductile rock is determined by combining the results of parameter tests with

  15. Antibacterial Inhibitory Effects of Punica Granatum Gel on Cariogenic Bacteria: An in vitro Study.

    Science.gov (United States)

    Millo, Grazielle; Juntavee, Apa; Ratanathongkam, Ariya; Nualkaew, Natsajee; Peerapattana, Jomjai; Chatchiwiwattana, Supaporn

    2017-01-01

    This study evaluated the in vitro antibacterial effects of the formulated Punica granatum (PG) gel against Streptococcus mutans, Streptococcus sanguinis, and Lactobacillus casei. The PG extract was dissolved in water at 500 mg/mL. High performance liquid chromatography (HPLC) was used for identification and quantification of chemical marker punicalagin. Minimum bactericidal concentration (MBC) and time-kill assay (TKA) were investigated. Antibacterial activities of the formulated PG gel, 2% chlorhexidine (CHX) gel and blank gel were tested by measuring the zones of inhibition through agar well diffusion method. The HPLC results showed presence of punicalagin at 2023.58 ± 25.29 pg/mL in the aqueous PG extract and at 0.234% (w/w) in the formulated PG gel. The MBC for S. mutans, S. Sanguinis, and L. casei were 250, 125, and 500 mg/mL respectively. The TKA of 500 mg/mL aqueous PG extract showed total inhibition of S. mutans, S. Sanguinis, and L. casei at 6, 1, and 24 hours contact time respectively. Agar well diffusion revealed that for S. mutans, CHX gel > PG gel > blank gel; for S. sanguinis, CHX gel = PG gel > blank gel; for L. casei, CHX gel > PG gel = blank gel. Comparison of the PG gel potency showed that S. sanguinis = S. mutans > L. casei. The PG gel equivalent to 0.234% punicalagin (w/w) inhibited S. mutans and S. sanguinis but not L. casei within 24 hours incubation period and has the potential to be used for caries prevention. Millo G, Juntavee A, Ratanathongkam A, Nualkaew N, Peerapattana J, Chatchiwiwattana S. Antibacterial Inhibitory Effects of Punica Granatum Gel on Cariogenic Bacteria: An in vitro Study. Int J Clin Pediatr Dent 2017;10(2):152-157.

  16. Rheology of confined granular flows: scale invariance, glass transition, and friction weakening.

    Science.gov (United States)

    Richard, P; Valance, A; Métayer, J-F; Sanchez, P; Crassous, J; Louge, M; Delannay, R

    2008-12-12

    We study fully developed, steady granular flows confined between parallel flat frictional sidewalls using numerical simulations and experiments. Above a critical rate, sidewall friction stabilizes the underlying heap at an inclination larger than the angle of repose. The shear rate is constant and independent of inclination over much of the flowing layer. In the direction normal to the free surface, the solid volume fraction increases on a scale equal to half the flowing layer depth. Beneath a critical depth at which internal friction is invariant, grains exhibit creeping and intermittent cage motion similar to that in glasses, causing gradual weakening of friction at the walls.

  17. Cermet reinforcement of a weakened endodontically treated root: a case report.

    Science.gov (United States)

    Lui, J L

    1992-08-01

    Many clinical applications have been recommended for glass-cermet cement because of its improved properties compared to the original glass-ionomer cements. It has also been accepted as a dentinal substitute that can strengthen teeth. In this paper, an additional clinical application for glass-cermet cement, the reinforcement of weakened endodontically treated roots, is suggested. This technique is in keeping with the trends of tooth conservation and the use of an adhesive restorative material in the restoration of severely damaged teeth by a conservative approach.

  18. Could spaceflight-associated immune system weakening preclude the expansion of human presence beyond Earth's orbit?

    Science.gov (United States)

    Guéguinou, Nathan; Huin-Schohn, Cécile; Bascove, Matthieu; Bueb, Jean-Luc; Tschirhart, Eric; Legrand-Frossi, Christine; Frippiat, Jean-Pol

    2009-11-01

    This year, we celebrate the 40th birthday of the first landing of humans on the moon. By 2020, astronauts should return to the lunar surface and establish an outpost there that will provide a technical basis for future manned missions to Mars. This paper summarizes major constraints associated with a trip to Mars, presents immunological hazards associated with this type of mission, and shows that our current understanding of the immunosuppressive effects of spaceflight is limited. Weakening of the immune system associated with spaceflight is therefore an area that should be considered more thoroughly before we undertake prolonged space voyages.

  19. The Effect of Plant Supplements on the Development of Artificially Weaken Bee Families

    Directory of Open Access Journals (Sweden)

    Liviu Al. Mărghitaş

    2010-05-01

    Full Text Available In this study, infusions from nettle, thyme and Echinacea, fresh juice of onion and garlic, and Protofil (alcoholic extract of different plants enriched with vitamins and mineral elements, were used in supplementary feeding of artificially weaken bee families. Correlation between total phenolic content, total flavonoid content and antioxidant activity of the supplements used in honeybee feeding and uncapped, capped and total brood surface of experimental groups were established. The highest content of biologically active compounds exhibit nettle infusion, which present the most effective growth in field experiments.

  20. Origin of intergranular embrittlement of Al alloys induced by Na and Ca segregation: Grain boundary weakening

    International Nuclear Information System (INIS)

    Lu Guanghong; Zhang Ying; Deng Shenghua; Wang Tianmin; Kohyama, Masanori; Yamamoto, Ryoichi; Liu Feng; Horikawa, Keitaro; Kanno, Motohiro

    2006-01-01

    Using a first-principles computational tensile test, we show that the ideal tensile strength of an Al grain boundary (GB) is reduced with both Na and Ca GB segregation. We demonstrate that the fracture occurs in the GB interface, dominated by the break of the interfacial bonds. Experimentally, we further show that the presence of Na or Ca impurity, which causes intergranular fracture, reduces the ultimate tensile strength when embrittlement occurs. These results suggest that the Na/Ca-induced intergranular embrittlement of an Al alloy originates mainly from the GB weakening due to the Na/Ca segregation

  1. Dynamic weakening of smectite-rich faults at intermediate to high velocities

    Science.gov (United States)

    Oohashi, K.; Hirose, T.; Takahashi, M.

    2013-12-01

    Smectite, one of the hydrous clay mineral, is ubiquitous in incoming sediments to subduction zones and is thought to weaken and stabilize subduction thrust faults. However, frictional properties of smectite alone cannot explain the nucleation and propagation of earthquake slip at the shallow plate boundary thrust which potentially causes the devastating tsunamis. Here, we investigate for the first time the effect of smectite fraction in smectite-quartz mixtures on friction at 30 μm/s to 1.3 m/s, to shed a light on the frictional response for the intermediate to high slip rates where the conventional friction experiments have not been explored. In the low slip rate of 30 μm/s, the steady-state coefficient of friction decreases non-linearly increasing smectite fraction: it drops rapidly at moderate fraction of 30-50 vol%. On the other hand, at the faster slip rates of ≥ 150 μm/s the friction lowers from 10-20 vol% fraction since drastic slip weakening appears for the mixtures of ~20 vol % smectite. Hence the fault suddenly loses the strength by adding only 20 % of smectite. The weakening seems to be associated with an excess pore pressure invoked by shear compaction and thermal pressurization during the experiments. This property weakens the fault strength and accelerates the fault slip, even if clay content is small (c.a. 15-35 %), leading to the large stress drop. In contrast, the faults rich in smectite (≥ 50 %) may cause small stress drop during the faulting owing to low friction coefficient of smectite at any slip rates. The results highlight that smectite content significantly affects frictional properties of faults and may generates the diversity in the subduction zone earthquakes. ACKNOLEDGEMENTS We thank Kyuichi Kanagawa, Masaya Suzuki, Osamu Tadai, and Hiroko Kitajima for constructive discussions and technical help. This work was supported by a JSPS Grant-in-Aid for JSPS fellows (25-04960) to KO, a JSPS Grant-in-Aid for Young Scientists (B) (20740264

  2. High transparent shape memory gel

    Science.gov (United States)

    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.

  3. Rubber-like poly(vinyl alcohol) gel

    Energy Technology Data Exchange (ETDEWEB)

    Nambu, Masao (Nippon Oil Co. Ltd., Yokohama (Japan). Central Technical Research Lab.)

    1990-09-01

    Anomalous poly (vinyl alcohol) gel has been found in our laboratory since 1980. The gel is prepared by repeated freezing (or freeze-dehydration) of aqueous poly (vinyl alcohol). Experiments establish the fact that anomalous gel is never produced in the course of freezing, but during sustained thawing the gelation does occur. Moreover, it was found that the softening point of the gel increases at 37degC. It is assumed that crystal nuclei are generated on freezing, then on thawing, some of them grow to very fine crystals which act as polymer network-knots (cross-linking). Additional freezing provide other seeds, which grow similarly, and these are accumulated until rubber-like gel is produced. The gel was always water-resistant at 37degC, and the potassium permanganate consumption of the extracted water layer remained far below the official restricted value for medical materials. The gel can be sterilized with gamma-rays or chlorhexidine. Moreover, it satisfies the official standards of acute toxicity, pyrogen, intracutaneous reaction, hemolyzation, and intracorporeal implantation, respectively. Applications to adhesion-preventing membrane (for joint or pericardium), tamponade (for jaw defects), electrode (for electroretinogram or artificial inner ear), artificial denture base and phantoms for magnetic resonance imaging were examined. (author) 54 refs.

  4. Thoria sol-gel processes

    International Nuclear Information System (INIS)

    Matthews, R.B.

    1978-10-01

    Alternate fuel fabrication techniques are being developed at WNRE as part of the thorium fuel cycle program. The sol-gel techniques are attractive and this report assembles and summarizes information relating to thoria sol-gel fuels. Some background information on the behaviour and advantages of sol-gel fuel forms is presented, followed by a review of relevant colloid chemistry and an explanation of the fundamental steps of sol-gel processes. Finally, several variants to the basic process are reviewed and evaluated. (author)

  5. Silver nitrate based gel dosimeter

    International Nuclear Information System (INIS)

    Titus, D; Samuel, E J J; Srinivasan, K; Roopan, S M; Madhu, C S

    2017-01-01

    A new radiochromic gel dosimeter based on silver nitrate and a normoxic gel dosimeter was investigated using UV-Visible spectrophotometry in the clinical dose range. Gamma radiation induced the synthesis of silver nanoparticles in the gel and is confirmed from the UV-Visible spectrum which shows an absorbance peak at around 450 nm. The dose response function of the dosimeter is found to be linear upto12Gy. In addition, the gel samples were found to be stable which were kept under refrigeration. (paper)

  6. Gel polymer electrolytes for batteries

    Science.gov (United States)

    Balsara, Nitash Pervez; Eitouni, Hany Basam; Gur, Ilan; Singh, Mohit; Hudson, William

    2014-11-18

    Nanostructured gel polymer electrolytes that have both high ionic conductivity and high mechanical strength are disclosed. The electrolytes have at least two domains--one domain contains an ionically-conductive gel polymer and the other domain contains a rigid polymer that provides structure for the electrolyte. The domains are formed by block copolymers. The first block provides a polymer matrix that may or may not be conductive on by itself, but that can soak up a liquid electrolyte, thereby making a gel. An exemplary nanostructured gel polymer electrolyte has an ionic conductivity of at least 1.times.10.sup.-4 S cm.sup.-1 at 25.degree. C.

  7. Universal slip dynamics in metallic glasses and granular matter - linking frictional weakening with inertial effects

    Science.gov (United States)

    Denisov, Dmitry V.; Lőrincz, Kinga A.; Wright, Wendelin J.; Hufnagel, Todd C.; Nawano, Aya; Gu, Xiaojun; Uhl, Jonathan T.; Dahmen, Karin A.; Schall, Peter

    2017-03-01

    Slowly strained solids deform via intermittent slips that exhibit a material-independent critical size distribution. Here, by comparing two disparate systems - granular materials and bulk metallic glasses - we show evidence that not only the statistics of slips but also their dynamics are remarkably similar, i.e. independent of the microscopic details of the material. By resolving and comparing the full time evolution of avalanches in bulk metallic glasses and granular materials, we uncover a regime of universal deformation dynamics. We experimentally verify the predicted universal scaling functions for the dynamics of individual avalanches in both systems, and show that both the slip statistics and dynamics are independent of the scale and details of the material structure and interactions, thus settling a long-standing debate as to whether or not the claim of universality includes only the slip statistics or also the slip dynamics. The results imply that the frictional weakening in granular materials and the interplay of damping, weakening and inertial effects in bulk metallic glasses have strikingly similar effects on the slip dynamics. These results are important for transferring experimental results across scales and material structures in a single theory of deformation dynamics.

  8. The Capacity for Compaction Weakening in Fault Gouge in Nature and Experiment

    Science.gov (United States)

    Faulkner, D.; Boulton, C. J.; Sanchez Roa, C.; Den Hartog, S. A. M.; Bedford, J. D.

    2017-12-01

    As faults form in low permeability rocks, the compaction of fault gouge can lead to significant pore-fluid pressure increases. The pore pressure increase results from the collapse of the porosity through shear-enhanced compaction and the low hydraulic diffusivity of the gouge that inhibits fluid flow. In experiments, the frictional properties of clay-bearing fault gouges are significantly affected by the development of locally high pore-fluid pressures when compaction rates are high due to fast displacement rates or slip in underconsolidated materials. We show how the coefficient of friction of fault gouges sheared at different slip velocities can be explained with a numerical model that is constrained by laboratory measurements of contemporaneous changes in permeability and porosity. In nature, for compaction weakening to play an important role in earthquake nucleation (and rupture propagation), a mechanism is required to reset the porosity, i.e., maintain underconsolidated gouge along the fault plane. We use the observations of structures within the principal slip zone of the Alpine Fault in New Zealand to suggest that cyclic fluidization of the gouge occurs during coseismic slip, thereby resetting the gouge porosity prior to the next seismic event. Results from confined laboratory rotary shear measurements at elevated slip rates appear to support the hypothesis that fluidization leads to underconsolidation and, thus, to potential weakening by shear-enhanced compaction-induced pore-fluid pressurization.

  9. Think leader, think White? Capturing and weakening an implicit pro-White leadership bias.

    Science.gov (United States)

    Gündemir, Seval; Homan, Astrid C; de Dreu, Carsten K W; van Vugt, Mark

    2014-01-01

    Across four studies, we found evidence for an implicit pro-White leadership bias that helps explain the underrepresentation of ethnic minorities in leadership positions. Both White-majority and ethnic minority participants reacted significantly faster when ethnically White names and leadership roles (e.g., manager; Study 1) or leadership traits (e.g., decisiveness; Study 2 & 3) were paired in an Implicit Association Test (IAT) rather than when ethnic minority names and leadership traits were paired. Moreover, the implicit pro-White leadership bias showed discriminant validity with the conventional implicit bias measures (Study 3). Importantly, results showed that the pro-White leadership bias can be weakened when situational cues increase the salience of a dual identity (Study 4). This, in turn, can diminish the explicit pro-White bias in promotion related decision making processes (Study 4). This research offers a new tool to measure the implicit psychological processes underlying the underrepresentation of ethnic minorities in leadership positions and proposes interventions to weaken such biases.

  10. Think Leader, Think White? Capturing and Weakening an Implicit Pro-White Leadership Bias

    Science.gov (United States)

    Gündemir, Seval; Homan, Astrid C.; de Dreu, Carsten K. W.; van Vugt, Mark

    2014-01-01

    Across four studies, we found evidence for an implicit pro-White leadership bias that helps explain the underrepresentation of ethnic minorities in leadership positions. Both White-majority and ethnic minority participants reacted significantly faster when ethnically White names and leadership roles (e.g., manager; Study 1) or leadership traits (e.g., decisiveness; Study 2 & 3) were paired in an Implicit Association Test (IAT) rather than when ethnic minority names and leadership traits were paired. Moreover, the implicit pro-White leadership bias showed discriminant validity with the conventional implicit bias measures (Study 3). Importantly, results showed that the pro-White leadership bias can be weakened when situational cues increase the salience of a dual identity (Study 4). This, in turn, can diminish the explicit pro-White bias in promotion related decision making processes (Study 4). This research offers a new tool to measure the implicit psychological processes underlying the underrepresentation of ethnic minorities in leadership positions and proposes interventions to weaken such biases. PMID:24416181

  11. Landslide maps and seismic noise: Rockmass weakening caused by shallow earthquakes

    Science.gov (United States)

    Uchida, Tara; Marc, Odin; Sens-Schönfelder, Christoph; Sawazaki, Kaoru; Hobiger, Manuel; Hovius, Niels

    2015-04-01

    Some studies have suggested that the shaking and deformation associated with earthquake would result in a temporary increased hillslope erodibility. However very few data have been able to clarify such effect. We present integrated geomorphic data constraining an elevated landslide rate following 4 continental shallow earthquakes, the Mw 6.9 Finisterre (1993), the Mw 7.6 ChiChi (1999), the Mw 6.6 Niigata (2004) and the Mw 6.8 Iwate-Miyagi (2008) earthquakes. We constrained the magnitude, the recovery time and somewhat the mechanism at the source of this higher landslide risk. We provide some evidences excluding aftershocks or rain forcing intensity as possible mechanism and leaving subsurface weakening as the most likely. The landslide data suggest that this ground strength weakening is not limited to the soil cover but also affect the shallow bedrock. Additionally, we used ambient noise autocorrelation techniques to monitor shallow subsurface seismic velocity within the epicentral area of three of those earthquakes. For most stations we observe a velocity drop followed by a recovery processes of several years in fair agreement with the recovery time estimated based on landslide observation. Thus a common processes could alter the strength of the first 10m of soil/rock and simultaneously drive the landslide rate increase and the seismic velocity drop. The ability to firmly demonstrate this link require additional constraints on the seismic signal interpretation but would provide a very useful tool for post-earthquake risk managment.

  12. Think leader, think White? Capturing and weakening an implicit pro-White leadership bias.

    Directory of Open Access Journals (Sweden)

    Seval Gündemir

    Full Text Available Across four studies, we found evidence for an implicit pro-White leadership bias that helps explain the underrepresentation of ethnic minorities in leadership positions. Both White-majority and ethnic minority participants reacted significantly faster when ethnically White names and leadership roles (e.g., manager; Study 1 or leadership traits (e.g., decisiveness; Study 2 & 3 were paired in an Implicit Association Test (IAT rather than when ethnic minority names and leadership traits were paired. Moreover, the implicit pro-White leadership bias showed discriminant validity with the conventional implicit bias measures (Study 3. Importantly, results showed that the pro-White leadership bias can be weakened when situational cues increase the salience of a dual identity (Study 4. This, in turn, can diminish the explicit pro-White bias in promotion related decision making processes (Study 4. This research offers a new tool to measure the implicit psychological processes underlying the underrepresentation of ethnic minorities in leadership positions and proposes interventions to weaken such biases.

  13. Rapid acceleration leads to rapid weakening in earthquake-like laboratory experiments

    Science.gov (United States)

    Chang, J. C.; Lockner, D. A.; Reches, Z.

    2012-12-01

    We simulated the slip of a fault-patch during a large earthquake by rapidly loading an experimental, ring-shaped fault with energy stored in a spinning flywheel. The flywheel abruptly delivers a finite amount of energy by spinning the fault-patch that spontaneously dissipates the energy without operator intervention. We conducted 42 experiments on Sierra White granite (SWG) samples, and 24 experiments on Kasota dolomite (KD) samples. Each experiment starts by spinning a 225 kg disk-shaped flywheel to a prescribed angular velocity. We refer to this experiment as an "earthquake-like slip-event" (ELSE). The strength-evolution in ELSE experiments is similar to the strength-evolution proposed for earthquake models and observed in stick-slip experiments. Further, we found that ELSE experiments are similar to earthquakes in at least three ways: (1) slip driven by the release of a finite amount of stored energy; (2) pattern of fault strength evolution; and (3) seismically observed values, such as average slip, peak-velocity and rise-time. By assuming that the measured slip, D, in ELSE experiments is equivalent to the average slip during an earthquake, we found that ELSE experiments (D = 0.003-4.6 m) correspond to earthquakes in moment-magnitude range of Mw = 4-8. In ELSE experiments, the critical-slip-distance, dc, has mean values of 2.7 cm and 1.2 cm for SWG and KD, that are much shorter than the 1-10 m in steady-state classical experiments in rotary shear systems. We attribute these dc values, to ELSE loading in which the fault-patch is abruptly loaded by impact with a spinning flywheel. Under this loading, the friction-velocity relations are strikingly different from those under steady-state loading on the same rock samples with the same shear system (Reches and Lockner, Nature, 2010). We further note that the slip acceleration in ELSE evolves systematically with fault strength and wear-rate, and that the dynamic weakening is restricted to the period of intense

  14. Rheology and structure of milk protein gels

    NARCIS (Netherlands)

    Vliet, van T.; Lakemond, C.M.M.; Visschers, R.W.

    2004-01-01

    Recent studies on gel formation and rheology of milk gels are reviewed. A distinction is made between gels formed by aggregated casein, gels of `pure` whey proteins and gels in which both casein and whey proteins contribute to their properties. For casein' whey protein mixtures, it has been shown

  15. User-identified gel characteristics: a qualitative exploration of perceived product efficacy of topical vaginal microbicides.

    Science.gov (United States)

    Morrow, Kathleen M; Underhill, Kristen; van den Berg, Jacob J; Vargas, Sara; Rosen, Rochelle K; Katz, David F

    2014-10-01

    Research has demonstrated that certain vaginal gel products--microbicides containing antiretroviral drugs--may reduce HIV infection risk among women. But for vaginal gels to avert HIV and other sexually transmitted infections (STIs), at-risk women must be willing to use them as directed. These products must therefore be "acceptable" to women and an important component of acceptability is users' perception that the product will work to prevent infection. We sought to understand how women's perceptions of vaginal gel properties may shape their understanding of product efficacy for HIV and STI prevention. Sixteen women completed two in-depth qualitative interviews (k = 32) to identify the range and types of sensory perceptions they experienced when using two vaginal gels. We identified emergent themes and linkages between users' sensory perceptions and their beliefs about product efficacy. Users' predictions about product efficacy for preventing infection corresponded to measurable physical properties, including gel volume, location in the vagina, coating behavior, sensation of the gel in the vagina, leakage, and gel changes during coital acts. Although the women described similar sensory experiences (e.g., gel leaked from the vagina), they interpreted these experiences to have varying implications for product efficacy (e.g., leakage was predicted to increase or decrease efficacy). To improve microbicide acceptability, gel developers should investigate and deliberately incorporate properties that influence users' perceptions of efficacy. When a microbicide is approved for use, providers should educate users to anticipate and understand their sensory experiences; improving users' experience can maximize adherence and product effectiveness.

  16. Pecan drying with silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Ghate, S.R.; Chhinnan, M.S.

    1983-07-01

    High moisture in-shell pecans were dried by keeping them in direct and indirect contact with silica gel to investigate their drying characteristics. In-shell pecans were also dried with ambient air from a controlled environment chamber and with air dehumidified by silica gel. Direct contact and dehumidified air drying seemed feasible approaches.

  17. Nanocrystal/sol-gel nanocomposites

    Science.gov (United States)

    Petruska, Melissa A [Los Alamos, NM; Klimov, Victor L [Los Alamos, NM

    2007-06-05

    The present invention is directed to solid composites including colloidal nanocrystals within a sol-gel host or matrix and to processes of forming such solid composites. The present invention is further directed to alcohol soluble colloidal nanocrystals useful in formation of sol-gel based solid composites.

  18. 3D printing cybersecurity: detecting and preventing attacks that seek to weaken a printed object by changing fill level

    Science.gov (United States)

    Straub, Jeremy

    2017-06-01

    Prior work by Zeltmann, et al. has demonstrated the impact of small defects and other irregularities on the structural integrity of 3D printed objects. It posited that such defects could be introduced intentionally. The current work looks at the impact of changing the fill level on object structural integrity. It considers whether the existence of an appropriate level of fill can be determined through visible light imagery-based assessment of a 3D printed object. A technique for assessing the quality and sufficiency of quantity of 3D printed fill material is presented. It is assessed experimentally and results are presented and analyzed.

  19. The effect of dual complexing agents of lactic and citric acids on the formation of sol-gel derived Ag–PbTiO3 percolative thin film

    International Nuclear Information System (INIS)

    Su, Yanbo; Hu, Tao; Tang, Liwen; Weng, Wenjian; Han, Gaorong; Ma, Ning; Du, Piyi

    2014-01-01

    Controlling the formation of conductive particles to be nano-scale is important for achieving percolation effect in metal dispersed thin film composite to contribute extraordinary dielectric properties required for miniaturization of electronic devices. In this paper, lactic acid (LA) and citric acid (CA) were used as dual complexing agents to prepare a typical Ag nanoparticle dispersed PbTiO 3 (PTO) composite thin film by using a sol-gel method. The phase structure of the thin film and the coordination effect between complexing agent and metallic ions were investigated. It revealed that LA coordinated with Ti 4+ and Pb 2+ and CA coordinated with Ag + . Lead was fixed inside the gel network by LA and restricted to evaporate during heat treatment thus the pyrochlore phase was prevented from forming in the thin film. Ag + was coordinated by CA and the diffusion and thus aggregation of silver during gelation and annealing process were weakened. Silver nanoparticles dispersed in the PTO matrix formed with dual complexing agents of LA and CA introduced during the preparation process. The composite thin film of perfect perovskite phase with silver nanoparticles embedded was obtained at the molar ratio of LA/lead = 0.5 and CA/lead = 0.5. The dielectric constant of the thin film with silver nanoparticles is 5 times higher than that without silver nanoparticles. - Highlights: • Ag nanoparticle–PbTiO 3 percolative film with high dielectric property is prepared. • Evaporation of lead was prevented by coordinating Pb with lactic acid agent. • Dual complexing agents contribute block and pinning effects to form Ag nanoparticles

  20. Selection of methods and parameters for forced weakening of roofing in stoping faces

    Energy Technology Data Exchange (ETDEWEB)

    Bekbulatov, A K

    1982-01-01

    The use of the method of advanced shooting on mines of different basins of the country indicated the need to generalize results of work for forced weakening of the roofing on mines in the sector in order to create ''Instructions For Selecting the Methods and Parameters of Forced Weakening of Roofing in the Stoping Faces'' with the participation of the basin scientific research institutes under the leadership of the VNIMI. The main method of weakening which has been introduced in the Karaganda basin is frontal shooting with the use of torpedo-charges. Shooting of the roofing in order reduce the intensity of the primary settling of the main roofing is done in parallel and perpendicular plans. With the parallel plan, the wells are drilled out from the adjoining roadways parallel to the stoping face, and with perpendicular plan, from the assembly chamber perpendicular to the stoping face. In order to reduce the intensity of secondary settling of the main roofing, the parallel or parallel-inclined method is used in designing of the torpedo-charge and the torpedo-head. It is reported that the torpedo-charge is a set of individual torpedos made of polyethylene pipes of length 1500 mm connected to each other with the help of couplings and splints. The torpedo-head consists of a polyethylene pipe of length 700 mm with wall thickness 15-17 mm filled with bulk explosives. Within the torpedo there are 2 explosive charges with electric-detonators for instantaneous action. The main cables of the explosive circuit are connected to the electric detonators and are passed through the packing pipe. In the improved design of the torpedo-head and the torpedo-charge, there are no metal parts. This excludes blow-out of particles of incandescent metal during the explosion and increases the level of work safety. The torpedo-charge is installed manually or mechanically with the help of a metal guide (rammer) which is removed from the well after it delivers the torpedo-charge.

  1. Mechanical Weakening during Fluid Injection in Critically Stressed Sandstones with Acoustic Monitoring

    Science.gov (United States)

    David, C.; Dautriat, J. D.; Sarout, J.; Macault, R.; Bertauld, D.

    2014-12-01

    Water weakening is a well-known phenomenon which can lead to subsidence during the production of hydrocarbon reservoirs. The example of the Ekofisk oil field in the North Sea has been well documented for years. In order to assess water weakening effects in reservoir rocks, previous studies have focused on changes in the failure envelopes derived from mechanical tests conducted on rocks saturated either with water or with inert fluids. However, little attention has been paid so far on the mechanical behaviour during the fluid injection stage, like in enhanced oil recovery operations. We studied the effect of fluid injection on the mechanical behaviour of Sherwood sandstone, a weakly-consolidated sandstone sampled at Ladram Bay in UK. In order to highlight possible weakening effects, water and inert oil have been injected into critically-loaded samples to assess their effect on strength and elastic properties and to derive the acoustic signature of the saturation front for each fluid. The specimens were instrumented with 16 ultrasonic P-wave transducers for both passive and active acoustic monitoring during fluid injection and loading. After conducting standard triaxial tests on three samples saturated with air, water and oil respectively, mechanical creep tests were conducted on dry samples loaded at 80% of the compressive strength of the dry rock. While these conditions are kept constant, a fluid is injected at the bottom end of the sample with a low back pressure (0.5 MPa) to minimize effective stress variations during injection. Both water and oil were used as the injected pore fluid in two experiments. As soon as the fluids start to flow into the samples, creep is taking place with a much higher strain rate for water injection compared to oil injection. A transition from secondary creep to tertiary creep is observed in the water injection test whereas in the oil injection test no significant creep acceleration is observed after one pore volume of oil was

  2. Water weakening of chalk explaied from a fluid-solid friction factor

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling; Fabricius, Ida Lykke

    2010-01-01

    to where it is dominated by inertial forces, i.e. when the pore fluid motion lags behind the applied frequency. It is therefore a measure of the internal surface friction between solid and fluid which can be interpreted as a friction factor on the pore scale and we propose it can be extrapolated...... using the Biot critical frequency as a single reference. Other viscoplastic parameters were investigated in the same manner to verify the range of the functioning of the friction factor. The findings show that the Biot critical frequency can be used as a common friction factor and is useful in combining...... laboratory results. It is also inferred that the observed water weakening phenomenon may be attributed to the friction between solid and fluid....

  3. The signal of ill-defined CPT weakening entanglement in the B{sub d} system

    Energy Technology Data Exchange (ETDEWEB)

    Bernabeu, Jose; Botella, Francisco J. [Valencia Univ.-CSIC, Burjassot (Spain). Dept. de Fisica Teorica, IFIC; Mavromatos, Nick E. [Valencia Univ.-CSIC, Burjassot (Spain). Dept. de Fisica Teorica, IFIC; King' s College London (United Kingdom). Theoretical Particle Physics and Cosmology Group; Nebot, Miguel [Lisboa Univ. (Portugal). Centro de Fisica Teorica de Particulas (CFTP)

    2017-12-15

    In the presence of quantum-gravity fluctuations (space-time foam), the CPT operator may be ill-defined. Its perturbative treatment leads to a modification of the Einstein-Podolsky-Rosen correlation of the neutral meson system by adding an entanglement-weakening term of the wrong exchange symmetry, the ω-effect. In the current paper we identify how to probe the complex ω in the entangled B{sub d}-system using the flavour (f)-CP(g) eigenstate decay channels: the connection between the intensities for the two time-ordered decays (f, g) and (g, f) is lost. Appropriate observables are constructed allowing independent experimental determinations of Re(ω) and Im(ω), disentangled from CPT violation in the evolution Hamiltonian Re(θ) and Im(θ). 2σ tensions for both Re(θ) and Im(ω) are shown to be uncorrelated. (orig.)

  4. Experimental investigations on the weakening of pulsed X-radiation by contrast media

    Energy Technology Data Exchange (ETDEWEB)

    Moldenhauer, K

    1973-07-25

    In order to be able to carry out a videodensitometry simultaneously with the cineangiocardiography with pulsed X-rays, the weakening of the X-radiation by contrast media is more closely examined and a calibration of the amplitudes is carried out. The determination of the extinction curves for different parts of the X-ray pulses show that under unfavourable conditions (high voltage, low tube current, no Cu filtration) the spectrum is displaced to larger wavelengths, white an influence on the weakness coefficient only occurs after the intensity has fallen to 10% of the impulse maximum. On the other hand, the quantity depedence of the extinction coefficient is significant. The densitometry simulations performed with a digital computer using empirically gained calibration curves show that a quantitative densitometry is possible even if the Lambert-Beer law is not valid.

  5. Dynamic performance analysis of permanent magnet contactor with a flux-weakening control strategy

    Science.gov (United States)

    Wang, Xianbing; Lin, Heyun; Fang, Shuhua; Jin, Ping; Wang, Junhua; Ho, S. L.

    2011-04-01

    A new flux-weakening control strategy for permanent magnet contactors is proposed. By matching the dynamic attraction force and the antiforce, the terminal velocity and collision energy of the movable iron in the closing process are significantly reduced. The movable iron displacement is estimated by detecting the closing voltage and current with the proposed control. A dynamic mathematical model is also established under four kinds of excitation scenarios. The attraction force and flux linkage are predicted by finite element method and the dynamics of the closing process is simulated using the 4th-order Runge-Kutta algorithm. Experiments are carried out on a 250A prototype with an intelligent control unit to verify the proposed control strategy.

  6. Weakening of flux-pinning strength for high-Tc superconductors in an alternating magnetic field

    International Nuclear Information System (INIS)

    Chen, Q.Y.

    1992-01-01

    This paper reports on the flux-pinning forces in high temperature superconductors which were found to be weakened in an ac field as the applied field strength or the frequency increases. In the weakly pinned regime, flux dynamics could be described with the concept of magnetic diffusion. Flux-motion-induced finite resistivity could lead to significant skin-effect which was reflected in the ac screening effectiveness. The frequency dependence of the relative local field within a superconducting hollow cylinder were used to deduce the flux-motion resistivity ρ. For superconducting YB 2 Cu 3 O 7 - x compounds at 77K it was found that ρ ∼(mu, Omega)-cm. The corresponding magnetic diffusion coefficient was ∼ 224 cm 2 /s. At 750 Hz the skin depth is around 1.54 mm as compared with the 2-mm sample wall thickness

  7. Between the processes of strengthening and weakening of the Family Health Strategy

    Directory of Open Access Journals (Sweden)

    Regina Stella Spagnuolo

    2013-06-01

    Full Text Available This was a qualitative study with the purpose of designing a meta-model for the work process of the Family Health Strategy (FHS team. It was based on the experience of six sample groups, composed of their members (physicians, professional nurses, dentists, dental assistants, licensed technical nurses and community health agents in a city in São Paulo state, Brazil, totaling 54 subjects. Six theoretical models emerged from non-directive interviews. These were analyzed according to Grounded Theory and submitted to the meta-synthesis strategy, which produced the meta-model "between the processes of strengthening and weakening of the FHS model: professional-team-community reciprocity as an intervening component". When analyzed in light of the Theory of Complexity (TC, it showed to be a work with a vertical and authoritarian tendency, which is largely hegemonic in the tradition of public health care policies.

  8. Experimental investigations on the weakening of pulsed X-radiation by contrast media

    International Nuclear Information System (INIS)

    Moldenhauer, K.

    1973-01-01

    In order to be able to carry out a videodensitometry simultaneously with the cineangiocardiography with pulsed X-rays, the weakening of the X-radiation by contrast media is more closely examined and a calibration of the amplitudes is carried out. The determination of the extinction curves for different parts of the X-ray pulses show that under unfavourable conditions (high voltage, low tube current, no Cu filtration) the spectrum is displaced to larger wavelengths, white an influence on the weakness coefficient only occurs after the intensity has fallen to 10% of the impulse maximum. On the other hand, the quantity depedence of the extinction coefficient is significant. The densitometry simulations performed with a digital computer using empirically gained calibration curves show that a quantitative densitometry is possible even if the Lambert-Beer law is not valid. (ORU/LH) [de

  9. Weakening of the radioprotective action of gas hypoxia with growth of ascitic tumors

    Energy Technology Data Exchange (ETDEWEB)

    Aytmagambetova, B Z; Shmakova, N L; Fadeyeva, T A

    1975-06-27

    It was shown previously that moderate hypoxia induced by breathing oxygen-poor air (5 percent O/sub 2/) reduces the lethal effect of the total irradiation of mice, while with local irradiation of tumors reduction of tumor growth rate is even more marked in hypoxia-protected animals than with irradiation of mice in normal air. This suggests the possible therapeutic application of hypoxia. It was found that acute gas hypoxia strongly retards radiation damage to bone marrow, both qualitatively (type of cells affected) and quantitatively. In addition, a definite weakening of the protective effect of hypoxia was observed, this being proportional to increase in tumor size. Planned future tests involving direct dynamic measurement of oxygen stress as a function of amount of ascites are expected to supply further information on reduction of radiosensitivity of normal tissues and on the selective intensification of tumor regression. Graphic data accompany the paper. (JPRS)

  10. Rapid acceleration leads to rapid weakening in earthquake-like laboratory experiments

    Science.gov (United States)

    Chang, Jefferson C.; Lockner, David A.; Reches, Z.

    2012-01-01

    After nucleation, a large earthquake propagates as an expanding rupture front along a fault. This front activates countless fault patches that slip by consuming energy stored in Earth’s crust. We simulated the slip of a fault patch by rapidly loading an experimental fault with energy stored in a spinning flywheel. The spontaneous evolution of strength, acceleration, and velocity indicates that our experiments are proxies of fault-patch behavior during earthquakes of moment magnitude (Mw) = 4 to 8. We show that seismically determined earthquake parameters (e.g., displacement, velocity, magnitude, or fracture energy) can be used to estimate the intensity of the energy release during an earthquake. Our experiments further indicate that high acceleration imposed by the earthquake’s rupture front quickens dynamic weakening by intense wear of the fault zone.

  11. The transition of dynamic rupture styles in elastic media under velocity-weakening friction

    KAUST Repository

    Gabriel, A.-A.; Ampuero, J.-P.; Dalguer, L. A.; Mai, Paul Martin

    2012-01-01

    Although kinematic earthquake source inversions show dominantly pulse-like subshear rupture behavior, seismological observations, laboratory experiments and theoretical models indicate that earthquakes can operate with different rupture styles: either as pulses or cracks, that propagate at subshear or supershear speeds. The determination of rupture style and speed has important implications for ground motions and may inform about the state of stress and strength of active fault zones. We conduct 2D in-plane dynamic rupture simulations with a spectral element method to investigate the diversity of rupture styles on faults governed by velocity-and-state-dependent friction with dramatic velocity-weakening at high slip rate. Our rupture models are governed by uniform initial stresses, and are artificially initiated. We identify the conditions that lead to different rupture styles by investigating the transitions between decaying, steady state and growing pulses, cracks, sub-shear and super-shear ruptures as a function of background stress, nucleation size and characteristic velocity at the onset of severe weakening. Our models show that small changes of background stress or nucleation size may lead to dramatic changes of rupture style. We characterize the asymptotic properties of steady state and self-similar pulses as a function of background stress. We show that an earthquake may not be restricted to a single rupture style, but that complex rupture patterns may emerge that consist of multiple rupture fronts, possibly involving different styles and back-propagating fronts. We also demonstrate the possibility of a super-shear transition for pulse-like ruptures. Finally, we draw connections between our findings and recent seismological observations.

  12. The transition of dynamic rupture styles in elastic media under velocity-weakening friction

    KAUST Repository

    Gabriel, A.-A.

    2012-09-01

    Although kinematic earthquake source inversions show dominantly pulse-like subshear rupture behavior, seismological observations, laboratory experiments and theoretical models indicate that earthquakes can operate with different rupture styles: either as pulses or cracks, that propagate at subshear or supershear speeds. The determination of rupture style and speed has important implications for ground motions and may inform about the state of stress and strength of active fault zones. We conduct 2D in-plane dynamic rupture simulations with a spectral element method to investigate the diversity of rupture styles on faults governed by velocity-and-state-dependent friction with dramatic velocity-weakening at high slip rate. Our rupture models are governed by uniform initial stresses, and are artificially initiated. We identify the conditions that lead to different rupture styles by investigating the transitions between decaying, steady state and growing pulses, cracks, sub-shear and super-shear ruptures as a function of background stress, nucleation size and characteristic velocity at the onset of severe weakening. Our models show that small changes of background stress or nucleation size may lead to dramatic changes of rupture style. We characterize the asymptotic properties of steady state and self-similar pulses as a function of background stress. We show that an earthquake may not be restricted to a single rupture style, but that complex rupture patterns may emerge that consist of multiple rupture fronts, possibly involving different styles and back-propagating fronts. We also demonstrate the possibility of a super-shear transition for pulse-like ruptures. Finally, we draw connections between our findings and recent seismological observations.

  13. Fluorine profiling after application of various anti-caries gels

    International Nuclear Information System (INIS)

    Zschau, H.E.; Plier, F.; Otto, G.; Wyrwich, C.; Treide, A.

    1990-01-01

    Two newly developed caries-preventing gels were tested together with Elmex on pre-school children over a time of 3 years. Proton-induced gamma-ray emission spectrometry (PIGE) was used to measure the fluorine profiles in milk teeth (incisors). In accordance with the clinical statement the results allow to produce a new anti-caries drug. (orig.)

  14. Chemical Gel for Surface Decontamination

    International Nuclear Information System (INIS)

    Jung, Chong Hun; Moon, J. K.; Won, H. J.; Lee, K. W.; Kim, C. K.

    2010-01-01

    Many chemical decontamination processes operate by immersing components in aggressive chemical solutions. In these applications chemical decontamination technique produce large amounts of radioactive liquid waste. Therefore it is necessary to develop processes using chemical gels instead of chemical solutions, to avoid the well-known disadvantages of chemical decontamination techniques while retaining their high efficiency. Chemical gels decontamination process consists of applying the gel by spraying it onto the surface of large area components (floors, walls, etc) to be decontaminated. The gel adheres to any vertical or complex surface due to their thixotropic properties and operates by dissolving the radioactive deposit, along with a thin layer of the gel support, so that the radioactivity trapped at the surface can be removed. Important aspects of the gels are that small quantities can be used and they show thixitropic properties : liquid during spraying, and solid when stationary, allowing for strong adherence to surfaces. This work investigates the decontamination behaviors of organic-based chemical gel for SS 304 metallic surfaces contaminated with radioactive materials

  15. Formulation of a poly herbal gel for uterus flux

    Directory of Open Access Journals (Sweden)

    M. Rezghi

    2017-11-01

    Full Text Available Background and objectives: Over the centuries, herbal drugs have been used as major sources of medicine for the prevention and treatment of diseases. In recent years, there has been an exponential growth in the field of herbal medicines and these drugs are gaining popularity both in developing and developed countries because of their natural origin and less side effects. The present research has been undertaken to formulate and evaluate an herbal gel for uterus flux based on Iranian traditional medicine references. Methods: An aqueous extracts of fruit peels of Punica granatum and leaves of Myrtus communis, ethanol extract of oleo gum resins of Boswellia carterii and hydro-alcoholic extract of Carum carvi fruits were obtained. The gel was prepared by using the plants extract, carbopol 940, propylene glycol, tri-ethanolamine and distilled water. Further, the prepared gel was evaluated for physicochemical and microbial characteristics. Moreover, accelerated laboratory stability tests were performed. Results: The results showed good appearance and homogeneity of the gel. It was yellow-brown in color with acceptable physicochemical characteristics. Besides, the gel was stable towards physical changes and successfully passed microbiological tests. Conclusion: The prepared gel contained tannins which are astringent agents; therefore, this product could be an appropriate candidate for disorders like uterus flux with respect to its traditional use.

  16. Denaturing gradient gel electrophoresis

    International Nuclear Information System (INIS)

    Kocherginskaya, S.A.; Cann, I.K.O.; Mackie, R.I.

    2005-01-01

    It is worthwhile considering that only some 30 species make up the bulk of the bacterial population in human faeces at any one time based on the classical cultivation-based approach. The situation in the rumen is similar. Thus, it is practical to focus on specific groups of interest within the complex community. These may be the predominant or the most active species, specific physiological groups or readily identifiable (genetic) clusters of phylogenetically related organisms. Several 16S rDNA fingerprinting techniques can be invaluable for selecting and monitoring sequences or phylogenetic groups of interest and are described below. Over the past few decades, considerable attention was focussed on the identification of pure cultures of microbes on the basis of genetic polymorphisms of DNA encoding rRNA such as ribotyping, amplified fragment length polymorphism and randomly amplified polymorphic DNA. However, many of these methods require prior cultivation and are less suitable for use in analysis of complex mixed populations although important in describing cultivated microbial diversity in molecular terms. Much less attention was given to molecular characterization of complex communities. In particular, research into diversity and community structure over time has been revolutionized by the advent of molecular fingerprinting techniques for complex communities. Denaturing or temperature gradient gel electrophoresis (DGGE/TGGE) methods have been successfully applied to the analysis of human, pig, cattle, dog and rodent intestinal populations

  17. Quasi-dynamic versus fully dynamic simulations of earthquakes and aseismic slip with and without enhanced coseismic weakening

    Science.gov (United States)

    Thomas, Marion Y.; Lapusta, Nadia; Noda, Hiroyuki; Avouac, Jean-Philippe

    2014-03-01

    Physics-based numerical simulations of earthquakes and slow slip, coupled with field observations and laboratory experiments, can, in principle, be used to determine fault properties and potential fault behaviors. Because of the computational cost of simulating inertial wave-mediated effects, their representation is often simplified. The quasi-dynamic (QD) approach approximately accounts for inertial effects through a radiation damping term. We compare QD and fully dynamic (FD) simulations by exploring the long-term behavior of rate-and-state fault models with and without additional weakening during seismic slip. The models incorporate a velocity-strengthening (VS) patch in a velocity-weakening (VW) zone, to consider rupture interaction with a slip-inhibiting heterogeneity. Without additional weakening, the QD and FD approaches generate qualitatively similar slip patterns with quantitative differences, such as slower slip velocities and rupture speeds during earthquakes and more propensity for rupture arrest at the VS patch in the QD cases. Simulations with additional coseismic weakening produce qualitatively different patterns of earthquakes, with near-periodic pulse-like events in the FD simulations and much larger crack-like events accompanied by smaller events in the QD simulations. This is because the FD simulations with additional weakening allow earthquake rupture to propagate at a much lower level of prestress than the QD simulations. The resulting much larger ruptures in the QD simulations are more likely to propagate through the VS patch, unlike for the cases with no additional weakening. Overall, the QD approach should be used with caution, as the QD simulation results could drastically differ from the true response of the physical model considered.

  18. Gel electrophoresis of inorganic cations

    International Nuclear Information System (INIS)

    Schoenhofer, F.; Grass, F.

    1978-01-01

    In order to be able to separate the largest possible amounts of substance, polyacryl amide gel (PAA) and silica gel are used as carrier for the electrophoresis. Milligramme quantities can easily be separated on PAA gel plates. Electrophoretic ion focussing considerably improves it. Separations of Sr/Y and lanthanoids were carried out. The behaviour of the readily soluble complexing agent acids on silica gel thin layers was minutely investigated and an interpretation of the focussing effect was derived. The conditions for separating radionuclides were optimized. A further improved separation can be achieved by a time sequence combination of normal electrophoresis and ion focussing. Selective isolation methods are advantageous to determine radionuclide traces in environmental samples. The selective adsorption on preformed deposits was transferred to electrophoresis. After pre-investigations on silica gel layers, strontium and barium could also be retained on PAA gel and radium on strontium sulphate in PAA, whereas the disturbing calcium can easily pass through. Cesium can also be retained by prussian blue in the electrophoresis. (orig.) [de

  19. Metasomatism and the Weakening of Cratons: A Mechanism to Rift Cratons

    Science.gov (United States)

    Wenker, Stefanie; Beaumont, Christopher

    2016-04-01

    The preservation of cratons is a demonstration of their strength and resistance to deformation. However, several cratons are rifting now (e.g. Tanzania and North China Craton) or have rifted in the past (e.g. North Atlantic Craton). To explain this paradox, we suggest that widespread metasomatism of the originally cold depleted dehydrated craton mantle lithosphere root can act as a potential weakening mechanism. This process, particularly melt metasomatism, increases root density through a melt-peridotite reaction, and reduces root viscosity by increasing the temperature and rehydrating the cratonic mantle lithosphere. Using 2D numerical models, we model silicate-melt metasomatism and rehydration of cold cratonic mantle lithosphere that is positioned beside standard Phanerozoic lithosphere. The models are designed to investigate when a craton is sufficiently weakened to undergo rifting and is no longer protected by the initially weaker adjacent standard Phanerozoic lithosphere. Melt is added to specified layers in the cratonic mantle lithosphere at a uniform volumetric rate determined by the duration of metasomatism (3 Myr, 10 Myr or 30 Myr), until a total of ~30% by volume of melt has been added. During melt addition heat and mass are properly conserved and the density and volume increase by the respective amounts required by the reaction with the peridotite. No extensional boundary conditions are applied to the models during the metasomatism process. As expected, significant refertilization leads to removal and thinning of progressively more gravitationally unstable cratonic mantle lithosphere. We show that the duration of metasomatism dictates the final temperature in the cratonic upper mantle lithosphere. Consequently, when extensional boundary conditions are applied in our rifting tests in most cases the Phanerozoic lithosphere rifts. The craton rifts only in the models with the hottest cratonic upper mantle lithosphere. Our results indicate rifting of cratons

  20. NMR mechanisms in gel dosimetry

    International Nuclear Information System (INIS)

    Schreiner, L J

    2009-01-01

    Nuclear magnetic resonance was critical to the development of gel dosimetry, as it established the potential for three dimensional dosimetry with chemical dosimeter systems through magnetic resonance imaging [1]. In the last two decades MRI has served as the gold standard for imaging, while NMR relaxometry has played an important role in the development and understanding of the behaviour of new gel dosimetry systems. Therefore, an appreciation of the relaxation mechanisms determining the NMR behaviour of irradiated gel dosimeters is important for a full comprehension of a considerable component of the literature on gel dosimetry. A number of excellent papers have presented this important theory, this brief review will highlight some of the salient points made previously [1-5]. The spin relaxation of gel dosimeters (which determines the dose dependence in most conventional MR imaging) is determined principally by the protons on water molecules in the system. These water protons exist in different environments, or groups (see Figure 1): on bulk water, on water hydrating the chemical species that are being modified under irradiation, and on water hydrating the gel matrix used to spatially stabilize the dosimeter (e.g., gelatin, agarose, etc). The spin relaxation depends on the inherent relaxation rate of each spin group, that is, on the relaxation rate which would be observed for the specific group if it were isolated. Also, the different water environments are not isolated from each other, and the observed relaxation rate also depends on the rate of exchange of magnetization between the groups, and on the fraction of protons in each group. In fact, the water exchanges quickly between the environments, so that relaxation is in what is usually termed the fast exchange regime. In the limit of fast exchange, the relaxation of the water protons is well characterized by a single exponential and hence by a single apparent relaxation rate. In irradiated gel dosimeters this

  1. Weakening temperature control on the interannual variations of spring carbon uptake across northern lands

    Energy Technology Data Exchange (ETDEWEB)

    Piao, Shilong [Chinese Academy of Sciences (CAS), Beijing (China); Peking Univ., Beijing (China); Liu, Zhuo [Peking Univ., Beijing (China); Wang, Tao [Chinese Academy of Sciences (CAS), Beijing (China); Peng, Shushi [Peking Univ., Beijing (China); Ciais, Philippe [Alternative Energies and Atomic Energy Commission (CEA), Gif-sur-Yvette (France); Huang, Mengtian [Peking Univ., Beijing (China); Ahlstrom, Anders [Stanford Univ., CA (United States); Burkhart, John F. [Univ. of Oslo (Norway); Chevallier, Frédéric [Alternative Energies and Atomic Energy Commission (CEA), Gif-sur-Yvette (France); Janssens, Ivan A. [Univ. of Antwerp, Wilrijk (Belgium); Jeong, Su-Jong [South Univ. of Science and Technology of China, Shenzhen (China); Lin, Xin [Alternative Energies and Atomic Energy Commission (CEA), Gif-sur-Yvette (France); Mao, Jiafu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Miller, John [National Oceanic and Atmospheric Administration Earth Systems Research Lab., Boulder, CO (United States); Univ. of Colorado, Boulder, CO (United States); Mohammat, Anwar [Chinese Academy of Sciences (CAS), Beijing (China); Myneni, Ranga B. [Boston Univ., MA (United States); Peñuelas, Josep [Centre for Ecological Research and Forestry Applications (CREAF), Barcelona (Spain); Shi, Xiaoying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stohl, Andreas [Norwegian Institute for Air Research (NILU), Kjeller (Norway); Yao, Yitong [Peking Univ., Beijing (China); Zhu, Zaichun [Peking Univ., Beijing (China); Tans, Pieter P. [National Oceanic and Atmospheric Administration Earth Systems Research Lab., Boulder, CO (United States)

    2017-04-24

    Ongoing spring warming allows the growing season to begin earlier, enhancing carbon uptake in northern ecosystems. We use 34 years of atmospheric CO2 concentration measurements at Barrow, Alaska (BRW, 71° N) to show that the interannual relationship between spring temperature and carbon uptake has recently shifted. Here, we use two indicators: the spring zero-crossing date of atmospheric CO2 (SZC) and the magnitude of CO2 drawdown between May and June (SCC). The previously reported strong correlation between SZC, SCC and spring land temperature (ST) was found in the first 17 years of measurements, but disappeared in the last 17 years. As a result, the sensitivity of both SZC and SCC to warming decreased. Simulations with an atmospheric transport model coupled to a terrestrial ecosystem model suggest that the weakened interannual correlation of SZC and SCC with ST in the last 17 years is attributable to the declining temperature response of spring net primary productivity (NPP) rather than to changes in heterotrophic respiration or in atmospheric transport patterns. Reduced chilling during dormancy and emerging light limitation are possible mechanisms that may have contributed to the loss of NPP response to ST. These results thus challenge the ‘warmer spring–bigger sink’ mechanism.

  2. Drought-induced weakening of growth-temperature associations in high-elevation Iberian pines

    Science.gov (United States)

    Diego Galván, J.; Büntgen, Ulf; Ginzler, Christian; Grudd, Håkan; Gutiérrez, Emilia; Labuhn, Inga; Julio Camarero, J.

    2015-01-01

    The growth/climate relationship of theoretically temperature-controlled high-elevation forests has been demonstrated to weaken over recent decades. This is likely due to new tree growth limiting factors, such as an increasing drought risk for ecosystem functioning and productivity across the Mediterranean Basin. In addition, declining tree growth sensitivity to spring temperature may emerge in response to increasing drought stress. Here, we evaluate these ideas by assessing the growth/climate sensitivity of 1500 tree-ring width (TRW) and 102 maximum density (MXD) measurement series from 711 and 74 Pinus uncinata trees, respectively, sampled at 28 high-elevation forest sites across the Pyrenees and two relict populations of the Iberian System. Different dendroclimatological standardization and split period approaches were used to assess the high- to low-frequency behavior of 20th century tree growth in response to temperature means, precipitation totals and drought indices. Long-term variations in TRW track summer temperatures until about 1970 but diverge afterwards, whereas MXD captures the recent temperature increase in the low-frequency domain fairly well. On the other hand summer drought has increasingly driven TRW along the 20th century. Our results suggest fading temperature sensitivity of Iberian high-elevation P. uncinata forest growth, and reveal the importance of summer drought that is becoming the emergent limiting factor of tree ring width formation in many parts of the Mediterranean Basin.

  3. Weakening gravity on redshift-survey scales with kinetic matter mixing

    Energy Technology Data Exchange (ETDEWEB)

    D' Amico, Guido [Theoretical Physics Department, CERN, Geneva (Switzerland); Huang, Zhiqi [School of Physics and Astronomy, Sun Yat-Sen University, 135 Xingang Xi Road, 510275, Guangzhou (China); Mancarella, Michele; Vernizzi, Filippo [CEA, IPhT, CNRS, URA-2306, 91191 Gif-sur-Yvette cédex (France)

    2017-02-01

    We explore general scalar-tensor models in the presence of a kinetic mixing between matter and the scalar field, which we call Kinetic Matter Mixing. In the frame where gravity is de-mixed from the scalar this is due to disformal couplings of matter species to the gravitational sector, with disformal coefficients that depend on the gradient of the scalar field. In the frame where matter is minimally coupled, it originates from the so-called beyond Horndeski quadratic Lagrangian. We extend the Effective Theory of Interacting Dark Energy by allowing disformal coupling coefficients to depend on the gradient of the scalar field as well. In this very general approach, we derive the conditions to avoid ghost and gradient instabilities and we define Kinetic Matter Mixing independently of the frame metric used to described the action. We study its phenomenological consequences for a ΛCDM background evolution, first analytically on small scales. Then, we compute the matter power spectrum and the angular spectra of the CMB anisotropies and the CMB lensing potential, on all scales. We employ the public version of COOP, a numerical Einstein-Boltzmann solver that implements very general scalar-tensor modifications of gravity. Rather uniquely, Kinetic Matter Mixing weakens gravity on short scales, predicting a lower σ{sub 8} with respect to the ΛCDM case. We propose this as a possible solution to the tension between the CMB best-fit model and low-redshift observables.

  4. Lateral extrusion of a thermally weakened pluton overburden (Campiglia Marittima, Tuscany)

    Science.gov (United States)

    Vezzoni, Simone; Rocchi, Sergio; Dini, Andrea

    2017-10-01

    The ascent and emplacement of magmas in the upper crust modify the local pre-existing thermal and rheological settings. Such changes have important effects in producing anomalous structures, mass extrusion, rock fracturing, and in some conditions, hydrothermal mineralizations. In the Campiglia Marittima area, detailed field mapping led to the reconstruction of a local deformation history that overlaps, chronologically and spatially, with regional extension. This local deformation was triggered at the Miocene-Pliocene boundary by the intrusion of a monzogranitic pluton beneath a carbonate sedimentary sequence. The emplacement of the pluton produced a perturbation in the rheological behaviour of the carbonate host rocks, producing transient ductile conditions in the very shallow crust. The carbonate rocks were thermally weakened and flowed laterally, accumulating downslope of the pluton roof, mainly toward the east. As the thermal anomaly was decaying, the brittle-ductile boundary moved progressively back towards the pluton, and large tension gash-shaped volumes of fractured marble were generated. These fractured volumes were exploited by rising hydrothermal fluids generating sigmoidal skarn bodies and ore shoots. This work presents the Campiglia Marittima case study as a prime example of structural interference between regional extensional structures and local, lateral mass extrusion in a transient ductile rheological regime triggered by pluton emplacement.

  5. Strain-weakening rheology of marine sponges and its evolutionary implication

    Science.gov (United States)

    Kraus, Emily; Janmey, Paul; Sweeney, Alison; van Oosten, Anne

    Animal cells respond to mechanical stimuli as sensitively as they do to chemical stimuli. Further, cell proliferation is dependent on the viscoelasticity of the polymeric extracellular matrix (ECM) in which they are embedded. Biophysicists are therefore motivated to understand the biomechanics of the ECM itself. To date, this work has focused on the more familiar Bilateria, animals, including humans, with bilateral symmetry. The ECM of this group of animals is now understood to exhibit non-linear rheology that is typically strain- and compression-stiffening, and shear moduli that are frequency-dependent. These complex properties have been attributed to the semi-flexible nature of the underlying polymers. In contrast, we show that marine sponges are markedly strain-weakening under physiologically relevant conditions. Since sponges are a much earlier evolutionary branch than Bilateria, we interrogate the evolutionary potential and biochemical underpinnings of this novel complex rheology in filamentous networks, and cells ability to respond. Further, their life history strategy is uniquely dependent on flow and correlated shear stress, making them a model organism to study self-assembly algorithms organized around flow.

  6. Torque capability improvement of sensorless FOC induction machine in field weakening for propulsion purposes

    Directory of Open Access Journals (Sweden)

    Nisha G.K.

    2017-05-01

    Full Text Available An electric propulsion system is generally based on torque controlled electric drive and DC series motors are traditionally used for propulsion system. Induction machines, which are reliable, low cost and have less maintenance, satisfy the characteristics of the propulsion and reinstating the DC series motor. Field oriented control (FOC of induction machines can decouple its torque control from field control which allows the induction motor to act like a separately excited DC motor. In this paper, the characteristic control of induction motor is achieved through appropriate design modification of induction motor by varying magnetizing current to produce maximum torque in field weakening (FW region. Thus to improve the torque capability of induction machine in FW region by varying machine parameters. The sensorless operation of the induction motor is carried out by adopting model reference adaptive system (MRAS using sliding mode control (SMC and a FW algorithm based on the voltage and current constraints. The simulation of the induction motor drive models based on the design options have been carried out and analyzed the simulation results.

  7. A quantitative assessment of the weakening of wire ropes based on the magnetic testing

    Energy Technology Data Exchange (ETDEWEB)

    Kwasniewski, J.; Lankosz, L.; Tytko, A.

    1985-01-01

    Discusses the use of magnetic defectoscopes and defectographs in the nondestructive testing of wire ropes. Emphasizes the need for laboratory pre-calibration where quantitave results are required. Individual system calibration is recommended where instruments with a 95% confidence level in reading are used, e.g. MD-8 defectograph and DLS unit, but improved tolerances achieved in sensor head manufacture have made possible a universal calibration characteristic for use with defectoscopes and a wide variety of heads. A chart is given covering all heads and induction sensors available in Poland. Describes methods of interpreting presented results to indicate degree of wear due to fatigue, abrasion and corrosion in ropes with constituent wires of differing profile. States that the form of rope wear can be deduced from the character of the defectograph pulse readings. Formulae relating the degree of rope weakening to these readings and also to the integrated output are given. Briefly describes a method for determining the loss of rope cross sectional area based on Hall effect chart records. Outlines the use of the MD-9 and MD-10 defectoscopes in assessing rope wear in discrete ranges. Suggests that regular measurements permit an accurate determination of the character of progressive wear and further that pulse analysis of MD-10 results can permit a quantitative determination of wear. 4 refs.

  8. Negative Emotion Weakens the Degree of Self-reference Effect: Evidence from ERPs

    Directory of Open Access Journals (Sweden)

    Wei Fan

    2016-09-01

    Full Text Available We investigated the influence of negative emotion on the degree of self-reference effect using event-related potentials (ERPs. We presented emotional pictures and self-referential stimuli (stimuli that accelerate and improve processing and improve memory of information related to an individual’s self-concept in sequence. Participants judged the color of the target stimulus (self-referential stimuli. ERP results showed that the target stimuli elicited larger P2 amplitudes under neutral conditions than under negative emotional conditions. Under neutral conditions, N2 amplitudes for highly self-relevant names (target stimulus were smaller than those for any other names. Under negative emotional conditions, highly and moderately self-referential stimuli activated smaller N2 amplitudes. P3 amplitudes activated by self-referential processing under negative emotional conditions were smaller than neutral conditions. In the left and central sites, highly self-relevant names activated larger P3 amplitudes than any other names. But in the central sites, moderately self-relevant names activated larger P3 amplitudes than non-self-relevant names. The findings indicate that negative emotional processing could weaken the degree of self-reference effect.

  9. Resistance to compression of weakened roots subjected to different root reconstruction protocols

    Directory of Open Access Journals (Sweden)

    Lucas Villaça Zogheib

    2011-12-01

    Full Text Available OBJECTIVE: This study evaluated, in vitro, the fracture resistance of human non-vital teeth restored with different reconstruction protocols. MATERIAL AND METHODS: Forty human anterior roots of similar shape and dimensions were assigned to four groups (n=10, according to the root reconstruction protocol: Group I (control: non-weakened roots with glass fiber post; Group II: roots with composite resin by incremental technique and glass fiber post; Group III: roots with accessory glass fiber posts and glass fiber post; and Group IV: roots with anatomic glass fiber post technique. Following post cementation and core reconstruction, the roots were embedded in chemically activated acrylic resin and submitted to fracture resistance testing, with a compressive load at an angle of 45º in relation to the long axis of the root at a speed of 0.5 mm/min until fracture. All data were statistically analyzed with bilateral Dunnett's test (α=0.05. RESULTS: Group I presented higher mean values of fracture resistance when compared with the three experimental groups, which, in turn, presented similar resistance to fracture among each other. None of the techniques of root reconstruction with intraradicular posts improved root strength, and the incremental technique was suggested as being the most recommendable, since the type of fracture that occurred allowed the remaining dental structure to be repaired. CONCLUSION: The results of this in vitro study suggest that the healthy remaining radicular dentin is more important to increase fracture resistance than the root reconstruction protocol.

  10. Weakening Pin Bone Attachment in Fish Fillets Using High-Intensity Focused Ultrasound.

    Science.gov (United States)

    Skjelvareid, Martin H; Stormo, Svein Kristian; Þórarinsdóttir, Kristín Anna; Heia, Karsten

    2017-09-18

    High Intensity Focused Ultrasound (HIFU) can be used for the localized heating of biological tissue through the conversion of sound waves into heat. Although originally developed for human medicine, HIFU may also be used to weaken the attachment of pin bones in fish fillets to enable easier removal of such bones. This was shown in the present study, where a series of experiments were performed on HIFU phantoms and fillets of cod and salmon. In thin objects such as fish fillets, the heat is mainly dissipated at the surfaces. However, bones inside the fillet absorb ultrasound energy more efficiently than the surrounding tissue, resulting in a "self-focusing" heating of the bones. Salmon skin was found to effectively block the ultrasound, resulting in a significantly lower heating effect in fillets with skin. Cod skin partly blocked the ultrasound, but only to a small degree, enabling HIFU treatment through the skin. The treatment of fillets to reduce the pin bone attachment yielded an average reduction in the required pulling force by 50% in cod fillets with skin, with little muscle denaturation, and 72% in skinned fillets, with significant muscle denaturation. Salmon fillets were treated from the muscle side of the fillet to circumvent the need for penetration through skin. The treatment resulted in a 30% reduction in the peak pulling force and 10% reduction in the total pulling work, with a slight denaturation of the fillet surface.

  11. Nectar bacteria, but not yeast, weaken a plant-pollinator mutualism.

    Science.gov (United States)

    Vannette, Rachel L; Gauthier, Marie-Pierre L; Fukami, Tadashi

    2013-02-07

    Mutualistic interactions are often subject to exploitation by species that are not directly involved in the mutualism. Understanding which organisms act as such 'third-party' species and how they do so is a major challenge in the current study of mutualistic interactions. Here, we show that even species that appear ecologically similar can have contrasting effects as third-party species. We experimentally compared the effects of nectar-inhabiting bacteria and yeasts on the strength of a mutualism between a hummingbird-pollinated shrub, Mimulus aurantiacus, and its pollinators. We found that the common bacterium Gluconobacter sp., but not the common yeast Metschnikowia reukaufii, reduced pollination success, seed set and nectar consumption by pollinators, thereby weakening the plant-pollinator mutualism. We also found that the bacteria reduced nectar pH and total sugar concentration more greatly than the yeasts did and that the bacteria decreased glucose concentration and increased fructose concentration whereas the yeasts affected neither. These distinct changes to nectar chemistry may underlie the microbes' contrasting effects on the mutualism. Our results suggest that it is necessary to understand the determinants of microbial species composition in nectar and their differential modification of floral rewards to explain the mutual benefits that plants and pollinators gain from each other.

  12. Nectar bacteria, but not yeast, weaken a plant–pollinator mutualism

    Science.gov (United States)

    Vannette, Rachel L.; Gauthier, Marie-Pierre L.; Fukami, Tadashi

    2013-01-01

    Mutualistic interactions are often subject to exploitation by species that are not directly involved in the mutualism. Understanding which organisms act as such ‘third-party’ species and how they do so is a major challenge in the current study of mutualistic interactions. Here, we show that even species that appear ecologically similar can have contrasting effects as third-party species. We experimentally compared the effects of nectar-inhabiting bacteria and yeasts on the strength of a mutualism between a hummingbird-pollinated shrub, Mimulus aurantiacus, and its pollinators. We found that the common bacterium Gluconobacter sp., but not the common yeast Metschnikowia reukaufii, reduced pollination success, seed set and nectar consumption by pollinators, thereby weakening the plant–pollinator mutualism. We also found that the bacteria reduced nectar pH and total sugar concentration more greatly than the yeasts did and that the bacteria decreased glucose concentration and increased fructose concentration whereas the yeasts affected neither. These distinct changes to nectar chemistry may underlie the microbes' contrasting effects on the mutualism. Our results suggest that it is necessary to understand the determinants of microbial species composition in nectar and their differential modification of floral rewards to explain the mutual benefits that plants and pollinators gain from each other. PMID:23222453

  13. The Weakening of Kin Ties: Exploring the Need for Life-World Led Interventions.

    Science.gov (United States)

    Schout, Gert; de Jong, Gideon

    2018-01-25

    The protective features that families and wider social relationships can have are required to meet the demands of life in contemporary Western societies. Choice and detraditionalization, however; impede this source of solidarity. Family Group Conferencing (FGC) and other life-world led interventions have the potential to strengthen primary groups. This paper explores the need for such a social intervention, using insights from sociological and philosophical theories and empirical findings from a case study of the research project 'FGC in mental health'. This need is understandable considering the weakening of kin ties, the poor qualities of state agencies to mobilise self-care and informal care, its capacity to produce a shift of power from public to private spheres and its capacity to mitigate the co-isolation of individuals, families and communities. A life-world led intervention like FGC with a specific and modest ambition contributes to small-scale solidarity. This ambition is not inclined to establish a broad social cohesion within society but to restore; in terms of the German philosopher Peter Sloterdijk; immunity (protection) and solidarity in primary groups, and consequently, resolve issues with those (family, neighbours, colleagues) who share a sphere (a situation, a process, a fate).

  14. Priority effects are weakened by a short, but not long, history of sympatric evolution.

    Science.gov (United States)

    Zee, Peter C; Fukami, Tadashi

    2018-01-31

    Priority effects, or the effects of species arrival history on local species abundances, have been documented in a range of taxa. However, factors determining the extent to which priority effects affect community assembly remain unclear. Using laboratory populations of the bacterium Pseudomonas fluorescens , we examined whether shared evolutionary history affected the strength of priority effects. We hypothesized that sympatric evolution of populations belonging to the same guild would lead to niche differentiation, resulting in phenotypic complementarity that weakens priority effects. Consistent with this hypothesis, we found that priority effects tended to be weaker in sympatrically evolved pairs of immigrating populations than in allopatrically evolved pairs. Furthermore, priority effects were weaker under higher phenotypic complementarity. However, these patterns were observed only in populations with a relatively short history of sympatric evolution, and disappeared when populations had evolved together for a long time. Together, our results suggest that the evolutionary history of organismal traits may dictate the strength of priority effects and, consequently, the extent of historical contingency in the assembly of ecological communities. © 2018 The Author(s).

  15. Investigation of mechanical field weakening of axial flux permanent magnet motor

    Science.gov (United States)

    Syaifuddin Mohd, M.; Aziz, A. Rashid A.; Syafiq Mohd, M.

    2015-12-01

    An investigation of axial flux permanent magnet motor (AFPM) characteristics was conducted with a proposed mechanical field weakening control mechanisms (by means of stator-rotor force manipulation) on the motor through modeling and experimentation. By varying the air gap between at least two bistable positions, the peak torque and top speed of the motor can be extended. The motor high efficiency region can also be extended to cover greater part of the motor operating points. An analytical model of the motor had been developed to study the correlation between the total attraction force (between the rotor and the stator) and the operating parameters of the motor. The test results shows that the motor output complies with the prediction of the research hypothesis and it is likely that a spring locking mechanism can be built to dynamically adjust the air gap of the motor to increase the operating range and could be applied in electric drivetrain applications to improve overall efficiency of electric and hybrid electric vehicles.

  16. ON THE WEAKENING OF THE POLAR MAGNETIC FIELDS DURING SOLAR CYCLE 23

    International Nuclear Information System (INIS)

    Wang, Y.-M.; Sheeley, N. R.; Robbrecht, E.

    2009-01-01

    The Sun's polar fields are currently ∼40% weaker than they were during the previous three sunspot minima. This weakening has been accompanied by a corresponding decrease in the interplanetary magnetic field (IMF) strength, by a ∼20% shrinkage in the polar coronal-hole areas, and by a reduction in the solar-wind mass flux over the poles. It has also been reflected in coronal streamer structure and the heliospheric current sheet, which only showed the expected flattening into the equatorial plane after sunspot numbers fell to unusually low values in mid-2008. From latitude-time plots of the photospheric field, it has long been apparent that the polar fields are formed through the transport of trailing-polarity flux from the sunspot latitudes to the poles. To address the question of why the polar fields are now so weak, we simulate the evolution of the photospheric field and radial IMF strength from 1965 to the present, employing a surface transport model that includes the effects of active region emergence, differential rotation, supergranular convection, and a poleward bulk flow. We find that the observed evolution can be reproduced if the amplitude of the surface meridional flow is varied by as little as 15% (between 14.5 and 17 m s -1 ), with the higher average speeds being required during the long cycles 20 and 23.

  17. Future equivalent of 2010 Russian heatwave intensified by weakening soil moisture constraints

    Science.gov (United States)

    Rasmijn, L. M.; van der Schrier, G.; Bintanja, R.; Barkmeijer, J.; Sterl, A.; Hazeleger, W.

    2018-05-01

    The 2010 heatwave in eastern Europe and Russia ranks among the hottest events ever recorded in the region1,2. The excessive summer warmth was related to an anomalously widespread and intense quasi-stationary anticyclonic circulation anomaly over western Russia, reinforced by depletion of spring soil moisture1,3-5. At present, high soil moisture levels and strong surface evaporation generally tend to cap maximum summer temperatures6-8, but these constraints may weaken under future warming9,10. Here, we use a data assimilation technique in which future climate model simulations are nudged to realistically represent the persistence and strength of the 2010 blocked atmospheric flow. In the future, synoptically driven extreme warming under favourable large-scale atmospheric conditions will no longer be suppressed by abundant soil moisture, leading to a disproportional intensification of future heatwaves. This implies that future mid-latitude heatwaves analogous to the 2010 event will become even more extreme than previously thought, with temperature extremes increasing by 8.4 °C over western Russia. Thus, the socioeconomic impacts of future heatwaves will probably be amplified beyond current estimates.

  18. Gel phase formation in dilute triblock copolyelectrolyte complexes

    Science.gov (United States)

    Srivastava, Samanvaya; Andreev, Marat; Levi, Adam E.; Goldfeld, David J.; Mao, Jun; Heller, William T.; Prabhu, Vivek M.; de Pablo, Juan J.; Tirrell, Matthew V.

    2017-02-01

    Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at low polymer concentrations (simulations. Here we show that in contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing concentration, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assembly of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously on solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chain aggregates in early stages of copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Our discoveries contribute to the fundamental understanding of the structure and pathways of complexation-driven assemblies, and raise intriguing prospects for gel formation at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.

  19. Thixotropic gel for vadose zone remediation

    Science.gov (United States)

    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.

  20. Surface grafted chitosan gels. Part II. Gel formation and characterization

    DEFF Research Database (Denmark)

    Liu, Chao; Thormann, Esben; Claesson, Per M.

    2014-01-01

    Responsive biomaterial hydrogels attract significant attention due to their biocompatibility and degradability. In order to make chitosan based gels, we first graft one layer of chitosan to silica, and then build a chitosan/poly(acrylic acid) multilayer using the layer-by-layer approach. After...... cross-linking the chitosan present in the polyelectrolyte multilayer, poly(acrylic acid) is partly removed by exposing the multilayer structure to a concentrated carbonate buffer solution at a high pH, leaving a surface-grafted cross-linked gel. Chemical cross-linking enhances the gel stability against...... detachment and decomposition. The chemical reaction between gluteraldehyde, the cross-linking agent, and chitosan was followed in situ using total internal reflection Raman (TIRR) spectroscopy, which provided a molecular insight into the complex reaction mechanism, as well as the means to quantify the cross...

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

    Science.gov (United States)

    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

  2. Changes in extreme regional sea surface height due to an abrupt weakening of the Atlantic meridional overturning circulation

    NARCIS (Netherlands)

    Brunnabend, S.-E.; Dijkstra, H. A.; Kliphuis, M. A.; van Werkhoven, B.J.C.; Bal, H. E.; Seinstra, F.; Maassen, J.; van Meersbergen, M.

    2014-01-01

    As an extreme scenario of dynamical sea level changes, regional sea surface height (SSH) changes that occur in the North Atlantic due to an abrupt weakening of the Atlantic meridional overturning circulation (AMOC) are simulated. Two versions of the same ocean-only model are used to study the effect

  3. Analysis of variationfor horizontal deviation in the primary position after the inferior oblique muscle weakening

    Directory of Open Access Journals (Sweden)

    Ming-Yu Si

    2015-06-01

    Full Text Available AIM: To analyse the variation of horizontal deviation in the primary position after the inferior oblique muscle weakening, and to explore the effect of the inferior oblique muscle recession on horizontal deviations in primary position.METHODS:, In the study, 30 cases in the Department of ophthalmology of our hospital from January 2014 to September 2014 underwent the inferior oblique muscle recession as the sole without horizontal muscles surgery, who were superior obliquer paralysis and V pattern strabismus with small angle of horizontal strabismus, were analyzed. Of the 30 patients, 25 had unilateral inferior oblique muscle surgery, and then 5 had bilateral surgeries.Followed up for three to six mo, all patients were received full ophthalmologic and orthoptic examinations, including measurement of the deviation in the diagnostic positions of gaze at near 33cm and at distance 6m by prism and alternate cover test, synoptophore, Titmus stereo graph examination, Worth four lighting inspection, eye movement examination, and fundus photography preoperatively and postoperatively. The changes of horizontal deviations in the primary position after procedures were investigated. RESULT:(1The comparison of horizontal deviation showed significant difference pre- and post-operation in the exotropia group(P=0.00. It was postoperative respectively to reduce the original in external oblique average 3.35±2.87△ and 4.37±2.65△.(2The comparison of horizontal deviation showed significant difference pre-and post-operation in the esotropia group(P=0.02, and it decreased postoperatively in average 2.43±1.99△. There was no significant difference for horizontal deviation position between pre- and post-operation(P=0.089. CONCLUSION:The horizontal deviation in primary position, either exotropia or esotropia, will decrease after the Inferior oblique muscle recession. This change can be compensated by the gradually improving and establishing the fusion function.

  4. Targeted Memory Reactivation during Sleep Adaptively Promotes the Strengthening or Weakening of Overlapping Memories.

    Science.gov (United States)

    Oyarzún, Javiera P; Morís, Joaquín; Luque, David; de Diego-Balaguer, Ruth; Fuentemilla, Lluís

    2017-08-09

    System memory consolidation is conceptualized as an active process whereby newly encoded memory representations are strengthened through selective memory reactivation during sleep. However, our learning experience is highly overlapping in content (i.e., shares common elements), and memories of these events are organized in an intricate network of overlapping associated events. It remains to be explored whether and how selective memory reactivation during sleep has an impact on these overlapping memories acquired during awake time. Here, we test in a group of adult women and men the prediction that selective memory reactivation during sleep entails the reactivation of associated events and that this may lead the brain to adaptively regulate whether these associated memories are strengthened or pruned from memory networks on the basis of their relative associative strength with the shared element. Our findings demonstrate the existence of efficient regulatory neural mechanisms governing how complex memory networks are shaped during sleep as a function of their associative memory strength. SIGNIFICANCE STATEMENT Numerous studies have demonstrated that system memory consolidation is an active, selective, and sleep-dependent process in which only subsets of new memories become stabilized through their reactivation. However, the learning experience is highly overlapping in content and thus events are encoded in an intricate network of related memories. It remains to be explored whether and how memory reactivation has an impact on overlapping memories acquired during awake time. Here, we show that sleep memory reactivation promotes strengthening and weakening of overlapping memories based on their associative memory strength. These results suggest the existence of an efficient regulatory neural mechanism that avoids the formation of cluttered memory representation of multiple events and promotes stabilization of complex memory networks. Copyright © 2017 the authors 0270-6474/17/377748-11$15.00/0.

  5. Regime shifts and weakened environmental gradients in open oak and pine ecosystems.

    Science.gov (United States)

    Hanberry, Brice B; Dey, Dan C; He, Hong S

    2012-01-01

    Fire suppression allows tree species that are intolerant of fire stress to increase their distribution, potentially resulting in disruption of historical species-environmental relationships. To measure changes between historical General Land Office surveys (1815 to 1850) and current USDA Forest Inventory and Assessment surveys (2004 to 2008), we compared composition, distribution, and site factors of 21 tree species or species groups in the Missouri Ozarks. We used 24 environmental variables and random forests as a classification method to model distributions. Eastern redcedar, elms, maples, and other fire-sensitive species have increased in dominance in oak forests, with concurrent reductions by oak species; specific changes varied by ecological subsection. Ordinations displayed loss of separation between formerly distinctive oak and fire-sensitive tree species groups. Distribution maps showed decreased presence of disturbance-dependent oak and pine species and increased presence of fire-sensitive species that generally expanded from subsections protected from fire along rivers to upland areas, except for eastern redcedar, which expanded into these subsections. Large scale differences in spatial gradients between past and present communities paralleled reduced influence of local topographic gradients in the varied relief of the Missouri Ozarks, as fire-sensitive species have moved to higher, drier, and sunnier sites away from riverine corridors. Due to changes in land use, landscapes in the Missouri Ozarks, eastern United States, and world-wide are changing from open oak and pine-dominated ecosystems to novel oak-mixed species forests, although at fine scales, forests are becoming more diverse in tree species today. Fire suppression weakened the influence by environmental gradients over species dominance, allowing succession from disturbance-dependent oaks to an alternative state of fire-sensitive species. Current and future research and conservation that rely on

  6. Regime shifts and weakened environmental gradients in open oak and pine ecosystems.

    Directory of Open Access Journals (Sweden)

    Brice B Hanberry

    Full Text Available Fire suppression allows tree species that are intolerant of fire stress to increase their distribution, potentially resulting in disruption of historical species-environmental relationships. To measure changes between historical General Land Office surveys (1815 to 1850 and current USDA Forest Inventory and Assessment surveys (2004 to 2008, we compared composition, distribution, and site factors of 21 tree species or species groups in the Missouri Ozarks. We used 24 environmental variables and random forests as a classification method to model distributions. Eastern redcedar, elms, maples, and other fire-sensitive species have increased in dominance in oak forests, with concurrent reductions by oak species; specific changes varied by ecological subsection. Ordinations displayed loss of separation between formerly distinctive oak and fire-sensitive tree species groups. Distribution maps showed decreased presence of disturbance-dependent oak and pine species and increased presence of fire-sensitive species that generally expanded from subsections protected from fire along rivers to upland areas, except for eastern redcedar, which expanded into these subsections. Large scale differences in spatial gradients between past and present communities paralleled reduced influence of local topographic gradients in the varied relief of the Missouri Ozarks, as fire-sensitive species have moved to higher, drier, and sunnier sites away from riverine corridors. Due to changes in land use, landscapes in the Missouri Ozarks, eastern United States, and world-wide are changing from open oak and pine-dominated ecosystems to novel oak-mixed species forests, although at fine scales, forests are becoming more diverse in tree species today. Fire suppression weakened the influence by environmental gradients over species dominance, allowing succession from disturbance-dependent oaks to an alternative state of fire-sensitive species. Current and future research and

  7. Feelings of disgust and disgust-induced avoidance weaken following induced sexual arousal in women.

    Directory of Open Access Journals (Sweden)

    Charmaine Borg

    Full Text Available BACKGROUND: Sex and disgust are basic, evolutionary relevant functions that are often construed as paradoxical. In general the stimuli involved in sexual encounters are, at least out of context strongly perceived to hold high disgust qualities. Saliva, sweat, semen and body odours are among the strongest disgust elicitors. This results in the intriguing question of how people succeed in having pleasurable sex at all. One possible explanation could be that sexual engagement temporarily reduces the disgust eliciting properties of particular stimuli or that sexual engagement might weaken the hesitation to actually approach these stimuli. METHODOLOGY: Participants were healthy women (n = 90 randomly allocated to one of three groups: the sexual arousal, the non-sexual positive arousal, or the neutral control group. Film clips were used to elicit the relevant mood state. Participants engaged in 16 behavioural tasks, involving sex related (e.g., lubricate the vibrator and non-sex related (e.g., take a sip of juice with a large insect in the cup stimuli, to measure the impact of sexual arousal on feelings of disgust and actual avoidance behaviour. PRINCIPAL FINDINGS: The sexual arousal group rated the sex related stimuli as less disgusting compared to the other groups. A similar tendency was evident for the non-sex disgusting stimuli. For both the sex and non-sex related behavioural tasks the sexual arousal group showed less avoidance behaviour (i.e., they conducted the highest percentage of tasks compared to the other groups. SIGNIFICANCE: This study has investigated how sexual arousal interplays with disgust and disgust eliciting properties in women, and has demonstrated that this relationship goes beyond subjective report by affecting the actual approach to disgusting stimuli. Hence, this could explain how we still manage to engage in pleasurable sexual activity. Moreover, these findings suggest that low sexual arousal might be a key feature in the

  8. Non-Native Ambrosia Beetles as Opportunistic Exploiters of Living but Weakened Trees.

    Science.gov (United States)

    Ranger, Christopher M; Schultz, Peter B; Frank, Steven D; Chong, Juang H; Reding, Michael E

    2015-01-01

    detection of stress-induced ethanol emission and early colonization of living but weakened trees.

  9. On the initiation of sustained slip-weakening ruptures by localized stresses

    KAUST Repository

    Galis, Martin

    2014-12-10

    Numerical simulations of dynamic earthquake rupture require an artificial initiation procedure, if they are not integrated in long-term earthquake cycle simulations. A widely applied procedure involves an \\'overstressed asperity\\', a localized region stressed beyond the static frictional strength. The physical properties of the asperity (size, shape and overstress) may significantly impact rupture propagation. In particular, to induce a sustained rupture the asperity size needs to exceed a critical value. Although criteria for estimating the critical nucleation size under linear slip-weakening friction have been proposed for 2-D and 3-D problems based on simplifying assumptions, they do not provide general rules for designing 3-D numerical simulations. We conduct a parametric study to estimate parameters of the asperity that minimize numerical artefacts (e.g. changes of rupture shape and speed, artificial supershear transition, higher slip-rate amplitudes). We examine the critical size of square, circular and elliptical asperities as a function of asperity overstress and background (off-asperity) stress. For a given overstress, we find that asperity area controls rupture initiation while asperity shape is of lesser importance. The critical area obtained from our numerical results contrasts with published theoretical estimates when background stress is low. Therefore, we derive two new theoretical estimates of the critical size under low background stress while also accounting for overstress. Our numerical results suggest that setting the asperity overstress and area close to their critical values eliminates strong numerical artefacts even when the overstress is large. We also find that properly chosen asperity size or overstress may significantly shorten the duration of the initiation. Overall, our results provide guidelines for determining the size of the asperity and overstress to minimize the effects of the forced initiation on the subsequent spontaneous

  10. Non-Native Ambrosia Beetles as Opportunistic Exploiters of Living but Weakened Trees.

    Directory of Open Access Journals (Sweden)

    Christopher M Ranger

    involves detection of stress-induced ethanol emission and early colonization of living but weakened trees.

  11. Sol-gel derived sorbents

    Science.gov (United States)

    Sigman, Michael E.; Dindal, Amy B.

    2003-11-11

    Described is a method for producing copolymerized sol-gel derived sorbent particles for the production of copolymerized sol-gel derived sorbent material. The method for producing copolymerized sol-gel derived sorbent particles comprises adding a basic solution to an aqueous metal alkoxide mixture for a pH.ltoreq.8 to hydrolyze the metal alkoxides. Then, allowing the mixture to react at room temperature for a precalculated period of time for the mixture to undergo an increased in viscosity to obtain a desired pore size and surface area. The copolymerized mixture is then added to an immiscible, nonpolar solvent that has been heated to a sufficient temperature wherein the copolymerized mixture forms a solid upon the addition. The solid is recovered from the mixture, and is ready for use in an active sampling trap or activated for use in a passive sampling trap.

  12. Fundamentals of Polymer Gel Dosimeters

    Science.gov (United States)

    McAuley, Kim B.

    2006-12-01

    The recent literature on polymer gel dosimetry contains application papers and basic experimental studies involving polymethacrylic-acid-based and polyacrylamide-based gel dosimeters. The basic studies assess the relative merits of these two most commonly used dosimeters, and explore the effects of tetrakis hydroxymethyl phosphonium chloride (THPC) antioxidant on dosimeter performance. Polymer gel dosimeters that contain THPC or other oxygen scavengers are called normoxic dosimeters, because they can be prepared under normal atmospheric conditions, rather than in a glove box that excludes oxygen. In this review, an effort is made to explain some of the underlying chemical phenomena that affect dosimeter performance using THPC, and that lead to differences in behaviour between dosimeters made using the two types of monomer systems. Progress on the development of new more effective and less toxic dosimeters is also reported.

  13. Water-gel for gating graphene transistors.

    Science.gov (United States)

    Kim, Beom Joon; Um, Soong Ho; Song, Woo Chul; Kim, Yong Ho; Kang, Moon Sung; Cho, Jeong Ho

    2014-05-14

    Water, the primary electrolyte in biology, attracts significant interest as an electrolyte-type dielectric material for transistors compatible with biological systems. Unfortunately, the fluidic nature and low ionic conductivity of water prevents its practical usage in such applications. Here, we describe the development of a solid state, megahertz-operating, water-based gate dielectric system for operating graphene transistors. The new electrolyte systems were prepared by dissolving metal-substituted DNA polyelectrolytes into water. The addition of these biocompatible polyelectrolytes induced hydrogelation to provide solid-state integrity to the system. They also enhanced the ionic conductivities of the electrolytes, which in turn led to the quick formation of an electric double layer at the graphene/electrolyte interface that is beneficial for modulating currents in graphene transistors at high frequencies. At the optimized conditions, the Na-DNA water-gel-gated flexible transistors and inverters were operated at frequencies above 1 MHz and 100 kHz, respectively.

  14. Silica reinforced triblock copolymer gels

    DEFF Research Database (Denmark)

    Theunissen, E.; Overbergh, N.; Reynaers, H.

    2004-01-01

    The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order...

  15. Retaining in-gel zymographic activity of cysteine proteases via a cysteine-supplemented running buffer.

    Science.gov (United States)

    Vootukuri Reddy, Sreekanth; Philpott, Mike P; Trigiante, Giuseppe

    2016-10-01

    Zymography is a powerful technique to separate and identify different enzymatic activities on a standard acrylamide gel. For oxidation prone enzymes such as cysteine proteases however, the oxidizing species generated by electrolysis of the gel running buffer may result in partial or complete inactivation, thus compromising the final readout. This can be only partially remedied by subsequent treatment of the gel with reducing agents. We demonstrate the generation of reactive oxidizing species during electrophoresis and discovered that supplementation of the gel running buffer with a minimum of 5 mM cysteine prevents enzyme inactivation and allows retention of proteolytic activity as measured by zymography on model substrate N α-benzoyl-l-arginine p-nitroanilide, without at the same time altering the mobilities of the gel proteins. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. 21 CFR 866.4900 - Support gel.

    Science.gov (United States)

    2010-04-01

    ... IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4900 Support gel. (a) Identification. A support gel for clinical use is a device that consists of an agar or agarose preparation that...

  17. Increases in aerosol concentrations over eastern China due to the decadal-scale weakening of the East Asian summer monsoon

    Science.gov (United States)

    Zhu, Jianlei; Liao, Hong; Li, Jianping

    2012-05-01

    China has been experiencing increased concentrations of aerosols, commonly attributed to the large increases in emissions associated with the rapid economic development. We show by using a chemical transport model driven by the assimilated meteorological fields that the observed decadal-scale weakening of the East Asian summer monsoon also contributed to the increases in aerosols in China. We find that the simulated aerosol concentrations have strong negative correlations with the strength of the East Asian Summer monsoon. Accounting for sulfate, nitrate, ammonium, black carbon, and organic carbon aerosols, the summer surface-layer PM2.5 concentration averaged over eastern China (110°-125°E, 20°-45°N) can be 17.7% higher in the weakest monsoon years than in the strongest monsoon years. The weakening of the East Asian Summer monsoon increases aerosol concentrations mainly by the changes in atmospheric circulation (the convergence of air pollutants) in eastern China.

  18. Yield stress determination of a physical gel

    DEFF Research Database (Denmark)

    Hvidt, Søren

    2013-01-01

    Pluronic F127 solutions form gels in water with high elastic moduli. Pluronic gels can, however, only withstand small deformations and stresses. Different steady shear and oscillatory methods traditionally used to determine yield stress values are compared. The results show that the yield stresses...... values of these gels depend on test type and measurement time, and no absolute yield stress value can be determined for these physical gels....

  19. Physical Properties of Silicone Gel Breast Implants.

    Science.gov (United States)

    Jewell, Mark L; Bengtson, Bradley P; Smither, Kate; Nuti, Gina; Perry, TracyAnn

    2018-04-28

    Surgical applications using breast implants are individualized operations to fill and shape the breast. Physical properties beyond shape, size, and surface texture are important considerations during implant selection. Compare form stability, gel material properties, and shell thickness of textured shaped, textured round, and smooth round breast implants from 4 manufacturers: Allergan, Mentor, Sientra, and Establishment Labs through bench testing. Using a mandrel height gauge, form stability was measured by retention of dimensions on device movement from a horizontal to vertical supported orientation. Dynamic response of gel material (gel cohesivity, resistance to gel deformation, energy absorption) was measured using a synchronized target laser following application of graded negative pressure. Shell thickness was measured using digital thickness gauge calipers. Form stability, gel material properties, and shell thickness differed across breast implants. Of textured shaped devices, Allergan Natrelle 410 exhibited greater form stability than Mentor MemoryShape and Sientra Shaped implants. Allergan Inspira round implants containing TruForm 3 gel had greater form stability, higher gel cohesivity, greater resistance to gel deformation, and lower energy absorption than those containing TruForm 2 gel and in turn, implants containing TruForm 1 gel. Shell thickness was greater for textured versus smooth devices, and differed across styles. Gel cohesivity, resistance to gel deformation, and energy absorption are directly related to form stability, which in turn determines shape retention. These characteristics provide information to aid surgeons choosing an implant based on surgical application, patient tissue characteristics, and desired outcome.

  20. Role of pluronics on rheological, drying and crack initiation of 'suckable' gels of decontamination

    International Nuclear Information System (INIS)

    Bousquet, C.

    2007-12-01

    The aim of this work was to understand the role of an addition of pluronics on the rheological behaviour, the drying and the fracturing of 'suckable' gels used for nuclear decontamination. The system studied was an aqueous suspension of silica (100 g/L of Aerosil 380) in a strong acidic medium (HNO 3 /H 3 PO 4 1.5 mol/L/1.5 mol/L) in presence of pluronics. Pluronics are amphiphilic tri-blocks copolymers composed of ethylene poly-oxide blocks and of propylene poly-oxide. The first part of this study deals with the characterization of the rheological properties of the gels. From viscosity retaking measurements, flow rheo-grams analysis and the viscoelastic properties of the gels, have been determined an improvement of the rheological properties of the gels significant from the addition of 5 g/L of copolymer. In a second part, the determination of adsorption isotherms coupled to small angles neutrons diffusion measurements has revealed that copolymers are adsorbed flat on silica in bridging the aggregates between them and that the improvement of the rheological behaviour of the gels is due to the increase of the bonds density of the gelled lattice. Moreover, beyond 10 g/L, the adsorption saturation of copolymers at the surface of the silica prevents the bridging of the aggregates which induces the gel destabilization. The last part of this work deals with the characterization of characteristic values of drying and of crack initiation of gels. Then is revealed a relation between the drying kinetics and the formation of cracks in the gel layer. Moreover, the study of the evolution of stresses in the gel layer during time allows to reveal that the addition of pluronics to the formulation of gels allows to improve the gel resistance to the crack initiation and to the delamination. (O.M.)

  1. The gel electrophoresis markup language (GelML) from the Proteomics Standards Initiative.

    Science.gov (United States)

    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

    2010-09-01

    The Human Proteome Organisation's Proteomics Standards Initiative has developed the GelML (gel electrophoresis markup language) 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 MS 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.

  2. Gel dosimetry for conformal radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G [Department of Physics of the University and INFN, Milan (Italy)

    2005-07-01

    With the continuum development of conformal radio therapies, aimed at delivering high dose to tumor tissue and low dose to the healthy tissue around, the necessities has appeared of suitable improvement of dosimetry techniques giving the possibility of obtaining dose images to be compared with diagnostic images. Also if wide software has been developed for calculating dose distributions in the fields of various radiotherapy units, experimental verifications are necessary, in particular in the case of complex geometries in conformal radiotherapy. Gel dosimetry is a promising method for imaging the absorbed dose in tissue-equivalent phantoms, with the possibility of 3D reconstruction of the spatial dose distribution, with milli metric resolution. Optical imaging of gel dosimeters, based on visible light absorbance analysis, has shown to be a reliable technique for achieving dose distributions. (Author)

  3. Reduction in 24-Hour Plasma Testosterone Levels in Subjects Who Showered 15 or 30 Minutes After Application of Testosterone Gel

    NARCIS (Netherlands)

    de Ronde, W.; Vogel, S.; Bui, H.N.; Heijboer, A.C.

    2011-01-01

    Study Objective. To investigate whether showering, to prevent the involuntary transfer of testosterone to others through skin contact, either 15 or 30 minutes after application of testosterone gel would significantly affect plasma testosterone levels. Design. Prospective 3-way crossover trial.

  4. Water equivalence of polymer gel dosimeters

    International Nuclear Information System (INIS)

    Sellakumar, P.; James Jebaseelan Samuel, E.; Supe, Sanjay S.

    2007-01-01

    To evaluate the water equivalence and radiation transport properties of polymer gel dosimeters over the wide range of photon and electron energies 14 different types of polymer gels were considered. Their water equivalence was evaluated in terms of effective atomic number (Z eff ), electron density (ρ e ), photon mass attenuation coefficient (μ/ρ), photon mass energy absorption coefficient (μ en /ρ) and total stopping power (S/ρ) tot of electrons using the XCOM and the ESTAR database. The study showed that the effective atomic number of polymer gels were very close ( en /ρ for all polymer gels were in close agreement ( tot of electrons in polymer gel dosimeters were within 1% agreement with that of water. From the study we conclude that at lower energy (<80keV) the polymer gel dosimeters cannot be considered water equivalent and study has to be carried out before using the polymer gel for clinical application

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

    Science.gov (United States)

    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.

  6. Prevention and Reduction of Atrophic Acne Scars with Adapalene 0.3%/Benzoyl Peroxide 2.5% Gel in Subjects with Moderate or Severe Facial Acne: Results of a 6-Month Randomized, Vehicle-Controlled Trial Using Intra-Individual Comparison.

    Science.gov (United States)

    Dréno, Brigitte; Bissonnette, Robert; Gagné-Henley, Angélique; Barankin, Benjamin; Lynde, Charles; Kerrouche, Nabil; Tan, Jerry

    2018-04-01

    Very few clinical trials have investigated the effect of topical acne treatment on scarring. Our objective was to evaluate the efficacy of adapalene 0.3%/benzoyl peroxide 2.5% gel (A0.3/BPO2.5) in atrophic acne scar formation in patients with acne. In this multicenter, randomized, investigator-blinded, vehicle-controlled study, subjects with moderate or severe facial acne (Investigator's Global Assessment [IGA] score 3 or 4; ≥ 25 inflammatory lesions; ten or more atrophic acne scars) applied A0.3/BPO2.5 or vehicle daily per half face for 24 weeks. Subjects with acne requiring systemic treatment were excluded. Assessments included investigator atrophic acne scar count, Scar Global Assessment (SGA), acne lesion count, IGA, skin roughness and skin texture, subject self-assessment of clinical acne-related scars and satisfaction questionnaire, tolerability, and safety. Included subjects (n = 67) had mainly moderate acne (92.5% IGA 3); mean scores at baseline were approximately 40 acne lesions and 12 scars per half face. By week 24, the change from baseline in total scar count was - 15.5% for A0.3/BPO2.5 versus  + 14.4% for vehicle (approximately 30% difference), with a mean of 9.5 scars versus 13.3 per half face, respectively (p vehicle (p vehicle (p vehicle side, most commonly skin irritation (14.9 vs. 6%, respectively). Topical A0.3/BPO2.5 prevented and reduced atrophic scar formation. Scar count increased with vehicle (+ 14.4%) but decreased with A0.3/BPO2.5 (- 15.5%) over 24 weeks. ClinicalTrials.gov identifier NCT02735421.

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

    Science.gov (United States)

    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

  8. Metal-silica sol-gel materials

    Science.gov (United States)

    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.

  9. Analysis and control of excitation, field weakening and stability in direct torque controlled electrically excited synchronous motor drives

    Energy Technology Data Exchange (ETDEWEB)

    Pyrhoenen, O

    1999-12-31

    Direct torque control (DTC) is a new control method for rotating field electrical machines. DTC controls directly the motor stator flux linkage with the stator voltage, and no stator current controllers are used. With the DTC method very good torque dynamics can be achieved. Until now, DTC has been applied to asynchronous motor drives. The purpose of this work is to analyse the applicability of DTC to electrically excited synchronous motor drives. Compared with asynchronous motor drives, electrically excited synchronous motor drives require an additional control for the rotor field current. The field current control is called excitation control in this study. The dependence of the static and dynamic performance of DTC synchronous motor drives on the excitation control has been analysed and a straightforward excitation control method has been developed and tested. In the field weakening range the stator flux linkage modulus must be reduced in order to keep the electro motive force of the synchronous motor smaller than the stator voltage and in order to maintain a sufficient voltage reserve. The dynamic performance of the DTC synchronous motor drive depends on the stator flux linkage modulus. Another important factor for the dynamic performance in the field weakening range is the excitation control. The field weakening analysis considers both dependencies. A modified excitation control method, which maximises the dynamic performance in the field weakening range, has been developed. In synchronous motor drives the load angle must be kept in a stabile working area in order to avoid loss of synchronism. The traditional vector control methods allow to adjust the load angle of the synchronous motor directly by the stator current control. In the DTC synchronous motor drive the load angle is not a directly controllable variable, but it is formed freely according to the motor`s electromagnetic state and load. The load angle can be limited indirectly by limiting the torque

  10. Analysis and control of excitation, field weakening and stability in direct torque controlled electrically excited synchronous motor drives

    Energy Technology Data Exchange (ETDEWEB)

    Pyrhoenen, O.

    1998-12-31

    Direct torque control (DTC) is a new control method for rotating field electrical machines. DTC controls directly the motor stator flux linkage with the stator voltage, and no stator current controllers are used. With the DTC method very good torque dynamics can be achieved. Until now, DTC has been applied to asynchronous motor drives. The purpose of this work is to analyse the applicability of DTC to electrically excited synchronous motor drives. Compared with asynchronous motor drives, electrically excited synchronous motor drives require an additional control for the rotor field current. The field current control is called excitation control in this study. The dependence of the static and dynamic performance of DTC synchronous motor drives on the excitation control has been analysed and a straightforward excitation control method has been developed and tested. In the field weakening range the stator flux linkage modulus must be reduced in order to keep the electro motive force of the synchronous motor smaller than the stator voltage and in order to maintain a sufficient voltage reserve. The dynamic performance of the DTC synchronous motor drive depends on the stator flux linkage modulus. Another important factor for the dynamic performance in the field weakening range is the excitation control. The field weakening analysis considers both dependencies. A modified excitation control method, which maximises the dynamic performance in the field weakening range, has been developed. In synchronous motor drives the load angle must be kept in a stabile working area in order to avoid loss of synchronism. The traditional vector control methods allow to adjust the load angle of the synchronous motor directly by the stator current control. In the DTC synchronous motor drive the load angle is not a directly controllable variable, but it is formed freely according to the motor`s electromagnetic state and load. The load angle can be limited indirectly by limiting the torque

  11. Method and System for Weakening Shock Wave Strength at Leading Edge Surfaces of Vehicle in Supersonic Atmospheric Flight

    Science.gov (United States)

    Daso, Endwell O. (Inventor); Pritchett, Victor E., II (Inventor); Wang, Ten-See (Inventor); Farr, Rebecca Ann (Inventor); Auslender, Aaron Howard (Inventor); Blankson, Isaiah M. (Inventor); Plotkin, Kenneth J. (Inventor)

    2015-01-01

    A method and system are provided to weaken shock wave strength at leading edge surfaces of a vehicle in atmospheric flight. One or more flight-related attribute sensed along a vehicle's outer mold line are used to control the injection of a non-heated, non-plasma-producing gas into a local external flowfield of the vehicle from at least one leading-edge surface location along the vehicle's outer mold line. Pressure and/or mass flow rate of the gas so-injected is adjusted in order to cause a Rankine-Hugoniot Jump Condition along the vehicle's outer mold line to be violated.

  12. Research on pre-staining gel electrophoresis

    International Nuclear Information System (INIS)

    Zhong Ruibo; Liu Yushuang; Zhang Ping; Liu Jingran; Zhao Guofen; Zhang Feng

    2014-01-01

    Background: Gel electrophoresis is a powerful biochemical separation technique. Most biological molecules are completely transparent in the visible region of light, so it is necessary to use staining to show the results after gel electrophoresis, and the general steps of conventional staining methods are time-consuming. Purpose: We try to develop a novel approach to simplify the gel electrophoresis: Pre-Staining Gel Electrophoresis (PSGE), which can make the gel electrophoresis results monitored in real time. Methods: Pre-stain the protein samples with Coomassie Brilliant Blue (CBB) for 30 min before loading the sample into the gel well. Results and Conclusion: PSGE can be successfully used to analyze the binding efficiency of Bovine Serum Albumin (BSA) and amphiphilic polymer via chemical coupling and physical absorption, and the double PSGE also shows a great potential in bio-analytical chemistry. (authors)

  13. Functional coatings: the sol-gel approach

    International Nuclear Information System (INIS)

    Belleville, Ph.

    2010-01-01

    CEA's sol-gel laboratory is specialized in the development of innovative sol-gel optical coatings and has extended its application field to membrane materials and coatings for energy conversion, to electric coatings for microelectronics devices and to thin films for gas sensing. This article describes, by way of examples, the laboratory's research on sol-gel functional coatings, including nano-material synthesis, organic-inorganic hybrid-based solution preparation as well as deposition process development and prototyping. (author)

  14. Dosimetry Evolution in Teletherapy: Polimer Gel

    Science.gov (United States)

    Hamann, J. H.; Peixoto, J. G. P.

    2018-03-01

    Polymer gels evolution and chemical composition used in dosimetry. Type Composition First gels Folin’s Phenol or Gallic Acid Polymer Gel Agarose and N,N’-methylene-bis-acrylamide BANANA Bis, acrylamide, nitrous oxide and agarose BANG-1TM Bis, acrylamide, nitrogen and gelatin BANG-2TM Bis, acrylic acid, sodium hydroxide, nitrogen and gelatin BANG-3TM Bis, methacrylate acid, sodium hydroxide, nitrogen and gelatin MAGIC Methacrylate acid, ascorbic acid, gelatin and copper sulphate

  15. Stabilized aqueous gels and uses thereof

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Three-dimensional fracture instability of a displacement-weakening planar interface under locally peaked nonuniform loading

    Science.gov (United States)

    Uenishi, Koji

    2018-06-01

    We consider stability of fracture on a three-dimensional planar interface subjected to a loading stress that is locally peaked spatially, the level of which increases quasi-statically in time. Similar to the earlier study on the two-dimensional case (Uenishi and Rice, 2003; Rice and Uenishi, 2010), as the loading stress increases, a crack, or a region of displacement discontinuity (opening gap in tension or slip for shear fracture), develops on the interface where the stress is presumed to decrease according to a displacement-weakening constitutive relation. Upon reaching the instability point at which no further quasi-static solution for the extension of the crack on the interface exists, dynamic fracture follows. For the investigation of this instability point, we employ a dimensional analysis as well as an energy approach that gives a Rayleigh-Ritz approximation for the dependence of crack size and maximum displacement discontinuity on the level and quadratic shape of the loading stress distribution. We show that, if the linear displacement-weakening law is applied and the crack may be assumed of an elliptical form, the critical crack size at instability is independent of the curvature of the loading stress distribution and it is of the same order for all two- and three-dimensional cases.

  17. Weakening density dependence from climate change and agricultural intensification triggers pest outbreaks: a 37-year observation of cotton bollworms.

    Science.gov (United States)

    Ouyang, Fang; Hui, Cang; Ge, Saiying; Men, Xin-Yuan; Zhao, Zi-Hua; Shi, Pei-Jian; Zhang, Yong-Sheng; Li, Bai-Lian

    2014-09-01

    Understanding drivers of population fluctuation, especially for agricultural pests, is central to the provision of agro-ecosystem services. Here, we examine the role of endogenous density dependence and exogenous factors of climate and human activity in regulating the 37-year population dynamics of an important agricultural insect pest, the cotton bollworm (Helicoverpa armigera), in North China from 1975 to 2011. Quantitative time-series analysis provided strong evidence explaining long-term population dynamics of the cotton bollworm and its driving factors. Rising temperature and declining rainfall exacerbated the effect of agricultural intensification on continuously weakening the negative density dependence in regulating the population dynamics of cotton bollworms. Consequently, ongoing climate change and agricultural intensification unleashed the tightly regulated pest population and triggered the regional outbreak of H. armigera in 1992. Although the negative density dependence can effectively regulate the population change rate to fluctuate around zero at stable equilibrium levels before and after outbreak in the 1992, the population equilibrium jumped to a higher density level with apparently larger amplitudes after the outbreak. The results highlight the possibility for exogenous factors to induce pest outbreaks and alter the population regulating mechanism of negative density dependence and, thus, the stable equilibrium of the pest population, often to a higher level, posing considerable risks to the provision of agro-ecosystem services and regional food security. Efficient and timely measures of pest management in the era of Anthropocene should target the strengthening and revival of weakening density dependence caused by climate change and human activities.

  18. Sea level rise, surface warming, and the weakened buffering ability of South China Sea to strong typhoons in recent decades.

    Science.gov (United States)

    Sun, Jingru; Oey, Leo; Xu, F-H; Lin, Y-C

    2017-08-07

    Each year, a number of typhoons in the western North Pacific pass through the Luzon Strait into South China Sea (SCS). Although the storms remain above a warm open sea, the majority of them weaken due to atmospheric and oceanic environments unfavorable for typhoon intensification in SCS, which therefore serves as a natural buffer that shields the surrounding coasts from potentially more powerful storms. This study examines how this buffer has changed over inter-decadal and longer time scales. We show that the buffer weakens (i.e. greater potential for more powerful typhoons) in negative Pacific Decadal Oscillation (PDO) years, as well as with sea-level-rise and surface warming, caused primarily by the deepening of the ocean's 26 °C isotherm Z 26 . A new Intensity Change Index is proposed to describe the typhoon intensity change as a function of Z 26 and other environmental variables. In SCS, the new index accounts for as high as 75% of the total variance of typhoon intensity change.

  19. Income and Well-Being: Relative Income and Absolute Income Weaken Negative Emotion, but Only Relative Income Improves Positive Emotion.

    Science.gov (United States)

    Yu, Zonghuo; Chen, Li

    2016-01-01

    Whether relative income or absolute income could affect subjective well-being has been a bone of contention for years. Life satisfaction and the relative frequency of positive and negative emotions are parts of subjective well-being. According to the prospect theory, hedonic adaptation helps to explain why positive emotion is often so hard to be maintained, and negative emotion wouldn't be easy to be eliminated. So we expect the relationship between income and positive emotion is different from that between income and negative emotion. Given that regional reference is the main comparison mechanism, effects of regional average income on regional average subjective well-being should be potentially zero if only relative income matters. Using multilevel analysis, we tested the hypotheses with a dataset of 30,144 individuals from 162 counties in China. The results suggested that household income at the individual level is associated with life satisfaction, happiness and negative emotions. On the contrary, at a county level, household income is only associated with negative emotion. In other words, happiness and life satisfaction was only associated with relative income, but negative emotion was associated with relative income and absolute income. Without social comparison, income doesn't improve happiness, but it could weaken negative emotion. Therefore, it is possible for economic growth to weaken negative emotion without improving happiness. These findings also contribute to the current debate about the "Esterling paradox."

  20. The Hybridization Barrier between Herbaceous Medicago sativa and Woody M. arborea Is Weakened by Selection of Seed Parents

    Science.gov (United States)

    Bingham, Edwin; Armour, David; Irwin, John

    2013-01-01

    Medicago sativa, alfalfa or lucerne, and M. arborea were considered reproductively isolated until recently. Then, in 2003, an alfalfa genotype was identified that produced a few seeds and progeny with hybrid traits after a large number of pollinations by M. arborea. A derivative of this alfalfa genotype also produced a low frequency of progeny with hybrid traits. Thus, the hybridization barrier was weakened by selection of seed parents. Hybrids from both events expressed traits from M. arborea and M. arborea-specific DNA bands, although more of the M. sativa genome was retained, based on the DNA results. Thus, there was chromatin elimination during embryogenesis, resulting in partial hybrids (hereafter hybrids). However, more than 30 hybrids with an array of M. arborea traits have been obtained thus far, and research continues on the nature of the hybrids. Traits have been genetically transmitted in crosses, and selected traits are in use for alfalfa breeding. This paper reviews the first hybrids and then focuses on further weakening of the hybridization barrier with the discovery of a more efficient hybridizer derived from crossing Medicago sativa subspecies, sativa, coerulea and falcata. This genotype was found to have reproductive abnormalities associated with its complex subspecies origin that are best described as hybrid breakdown. In effect, this subspecies derivative is a bridge-cross parent that consistently produces hybrids. Reproductive abnormalities in the bridge-cross parent are reported and discussed. PMID:27137379

  1. The Hybridization Barrier between Herbaceous Medicago sativa and Woody M. arborea Is Weakened by Selection of Seed Parents

    Directory of Open Access Journals (Sweden)

    Edwin Bingham

    2013-05-01

    Full Text Available Medicago sativa, alfalfa or lucerne, and M. arborea were considered reproductively isolated until recently. Then, in 2003, an alfalfa genotype was identified that produced a few seeds and progeny with hybrid traits after a large number of pollinations by M. arborea. A derivative of this alfalfa genotype also produced a low frequency of progeny with hybrid traits. Thus, the hybridization barrier was weakened by selection of seed parents. Hybrids from both events expressed traits from M. arborea and M. arborea-specific DNA bands, although more of the M. sativa genome was retained, based on the DNA results. Thus, there was chromatin elimination during embryogenesis, resulting in partial hybrids (hereafter hybrids. However, more than 30 hybrids with an array of M. arborea traits have been obtained thus far, and research continues on the nature of the hybrids. Traits have been genetically transmitted in crosses, and selected traits are in use for alfalfa breeding. This paper reviews the first hybrids and then focuses on further weakening of the hybridization barrier with the discovery of a more efficient hybridizer derived from crossing Medicago sativa subspecies, sativa, coerulea and falcata. This genotype was found to have reproductive abnormalities associated with its complex subspecies origin that are best described as hybrid breakdown. In effect, this subspecies derivative is a bridge-cross parent that consistently produces hybrids. Reproductive abnormalities in the bridge-cross parent are reported and discussed.

  2. Microfluidics of soft granular gels

    Science.gov (United States)

    Nixon, Ryan; Bhattacharjee, Tapomoy; Sawyer, W. Gregory; Angelini, Thomas E.

    Microfluidic methods for encapsulating cells and particles typically involve drop making with two immiscible fluids. The main materials constraint in this approach is surface tension, creating inherent instability between the two fluids. We can eliminate this instability by using miscible inner and outer phases. This is achieved by using granular micro gels which are chemically miscible but physically do not mix. These microgels are yield stress materials, so they flow as solid plugs far from shear gradients, and fluidize where gradients are generated - near an injection nozzle for example. We have found that tuning the yield stress of the material by varying polymer concentration, device performance can be controlled. The solid like behavior of the gel allows us to produces infinitely stable jets that maintain their integrity and configuration over long distances and times. These properties can be combined and manipulated to produce discrete particulate bunches of an inner phase, flowing inside of an outer phase, well enough even to print a Morse code message suspended within flow chambers about a millimeter in diameter moving at millimeters a second.

  3. Natural tooth pontic with splinting of periodontally weakened teeth using fiber-reinforced composite resin

    Directory of Open Access Journals (Sweden)

    Gauri Srinidhi

    2014-01-01

    Full Text Available Replacement of missing anterior teeth due to periodontal reasons is challenging due to the poor support of abutment teeth. This prevents the use of fixed partial dentures (FPDs. Fiber-reinforced splinting provides a viable alternative to the dentist while choosing a treatment plan in replacing missing anterior teeth in periodontally compromised patients as opposed to conventional modalities like FPDs or removable partial dentures. Replacing missing teeth using either patient′s own tooth or a denture tooth as pontic can be done by splinting adjacent teeth with fiber reinforced composite. The splinting has an additional advantage of stabilizing adjacent mobile teeth. This case report details the case selection, procedure with follow-up of a case where the natural extracted tooth of the patient was used as pontic to replace a missing anterior tooth. The splinting was done with fiber reinforced composite resin. Fiber-reinforced composite resin splinting of patient′s extracted natural tooth is economical, fast, and easy to use chairside technique with the added benefit of periodontal stabilization.

  4. Conducting polymer electrodes for gel electrophoresis.

    Directory of Open Access Journals (Sweden)

    Katarina Bengtsson

    Full Text Available In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that π-conjugated polymers such as poly(3,4-ethylenedioxythiophene (PEDOT can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation.

  5. Ionic liquid based multifunctional double network gel

    Science.gov (United States)

    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.

  6. Gel nano-particulates against radioactivity

    International Nuclear Information System (INIS)

    Deroin, Ph.

    2004-01-01

    The Argonne research center (USA) has developed a 'super-gel' compound, a polymer close to those used in baby's diapers, which can reach a 90% efficiency in the radioactive decontamination of porous materials, like bricks or concrete. The contaminated materials are sprayed with a mixture of polymer gel and wetting agent with nano-particulates in suspension. Under the action of the wetting agent, radioactivity migrates from the pores to the gel and is trapped by the nano-particulates. The drying and recycling of the gel allows to reduce the volume of radioactive wastes. Short paper. (J.S.)

  7. Conducting polymer electrodes for gel electrophoresis.

    Science.gov (United States)

    Bengtsson, Katarina; Nilsson, Sara; Robinson, Nathaniel D

    2014-01-01

    In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that π-conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis) systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation.

  8. Comparison effect of azithromycin gel 2% with clindamycin gel 1% in patients with acne

    Directory of Open Access Journals (Sweden)

    Fatemeh Mokhtari

    2016-01-01

    Conclusion: Azithromycin gel has medical impact at least similar to Clindamycin Gel in treatment of mild to moderate acne vulgaris, and it may be consider as suitable drug for resistant acne to conventional topical therapy.

  9. The role of crosslinkers in epoxy-amine crosslinked silicon sol-gel barrier protection coatings

    International Nuclear Information System (INIS)

    Vreugdenhil, A.J.; Gelling, V.J.; Woods, M.E.; Schmelz, J.R.; Enderson, B.P.

    2008-01-01

    The search for chromate replacements in corrosion prevention materials has identified the use of hybrid sol-gel coatings as one, very promising approach. Appropriately functionalized hybrid sol-gel materials can be crosslinked to enhance their chemical durability and mechanical strength. In this work, we evaluate three crosslinkers used in a tetramethoxysilane-glycidoxypropyltrimethoxysilane binary sol-gel system in order to identify the role of the crosslinkers in corrosion protection. The crosslinkers examined were ethylenediamine, N-aminethylepiperazine, and diethylenetriamine. The sol-gel coatings were examined by contact angle, atomic force microscopy, and electrochemical impedance spectroscopy (EIS). Circuit modeling of the EIS results yielded valuable insights into the significant differences between the durabilities of the variously crosslinked coatings. Crosslinker hydrophobicity was identified as not playing a significant role whereas the number of reactive sites per crosslinker and the resulting morphology of the material may be an important parameter

  10. Stacking gels: A method for maximising output for pulsed-field gel electrophoresis

    Directory of Open Access Journals (Sweden)

    Heng See

    2009-01-01

    Full Text Available Pulsed field gel electrophoresis (PFGE, the gold standard of molecular typing methods, has a major disadvantage of an unusually long electrophoretic time. From the original protocol of 6 days, it was modified to 3 days and subsequently to a single day. We describe the procedure of stacking five to six gels one on top of another in order to increase and maximize the output in a shorter time without compromising the resolution and reproducibility. All the variables that affect pulsed field gels during electrophoresis were taken into consideration. We firstly optimized the parameters to be used and secondly determined whether stacking of five to six gels had any effect on the molecular separation during electrophoresis in comparison with a single gel run. DNA preparation, restriction, electrophoresis, staining and gel documentation was carried out based on previously published methods. Gels were analysed using BioNumerics and dice coefficient and unweighted pair group methods were used to generate dendrograms based on 1.5% tolerance values. Identical band profiles and band resolution-separation were seen in the PFGE patterns with single gel and multiple stacking gels. Cluster analysis further strengthened the fact that results from stacking gels were reproducible and comparable with a single gel run. This method of stacking gels saves time and maximizes the output at the same time. The run time for a single gel was about 28 hours, but with six stacked gels the run time was 54 hours compared with 28 x 6 = 168 hours if they were run separately as single gels thus saving time of 67.86%. Beside the big factor of saving time, stacking gels save resources (electricity, reagents, water, chemicals and working time by increasing the sample throughput in a shorter time without compromising on quality of data. But optimization of working parameters is vital depending on the PFGE system used.

  11. Categorization of rheological scaling models for particle gels applied to casein gels

    NARCIS (Netherlands)

    Mellema, M.; Opheusden, van J.H.J.; Vliet, van T.

    2002-01-01

    Rennet-induced casein gels made from skim milk were studied rheologically. A scaling model or framework for describing the rheological behavior of gels is discussed and used for classification of the structure of casein gels. There are two main parameters in the model that describe the number of

  12. Ophthalmic gels: Past, present and future.

    Science.gov (United States)

    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.

  13. Radiation sensitive polymer gel dosimeters

    International Nuclear Information System (INIS)

    Lepage, M.; Back, S.A.J.; Baldock, C.; Whittaker, A.K.; Rintoul, L.

    2000-01-01

    Full text: Radiation sensitive gels are studied for their potential to retain a permanent 3D dose distribution for applications in radiotherapy. Co-monomers dissolved in a tissue-equivalent hydrogel undergo a polymerization reaction upon absorption of ionizing radiation. The polymer formed influences the local spin-spin relaxation time (T 2 ) of the dosimeter that can be determined using magnetic resonance imaging (MRI). The relationship between T2 and the absorbed dose was studied for different initial chemical compositions. The aim was to find a model linking the changes in T 2 with absorbed dose to the initial composition of the dosimeter. It is believed this will help designing new gel dosimeters having desired properties to minimize the uncertainty in the determination of the dose distribution. 1 H, 13 C nuclear magnetic resonance spectroscopy and FT-Raman spectroscopy were used to quantify the amount of monomers still remaining after the absorption of a given dose of radiation. This data is used to model the changes of T2 as a function of the absorbed dose. A model of fast exchange of magnetization between three proton pools was used, where the fraction of protons (f x H ) in the x th pool is obtained from the chemical composition of the dosimeter and the apparent T2 of each pool is determined for a given composition. Initially, the protons are contained in two pools; a mobile (mob), which contains the water protons and the monomers protons, and a gelatin (gela) proton pool. The mobile pool is partially depleted as polymer is formed, the protons are transferred into the polymer (pol) pool. In the figure, the experimental data along with the calculated values are plotted for three different monomer concentrations, with the gelatin concentration fixed. The model is seen to provide a good fit to the experimental data

  14. Repair of glass by sol-gel coating using either conventional or microwave heating

    International Nuclear Information System (INIS)

    Boonyapiwat, A.; Fathi, Z.; Folz, D.C.; Clark, D.E.

    1993-01-01

    A method of repairing glass is discussed. Microindentation was used to deliberately weaken the glass. Some samples were dip coated with silica sol. Effects of dipping the glass in copper nitrate solution also were studied. Heat treatments were conducted in either a conventional furnace or a microwave oven. Four-point bend testing was used to evaluate the merit of each process. Microwave hybrid heating had the same effect on the repair of uncoated glass as conventional heating. Coating the glass with sol resulted in higher strength of glass than heat treatment alone. Treating the glass with copper nitrate without heat treating had no effect on strength. Microwave hybrid heating appears to yield higher reliability in sol-gel coated samples than conventional processing. 21 refs., 8 figs., 2 tabs

  15. Silica gel matrix immobilized Chlorophyta hydrodictyon africanum ...

    African Journals Online (AJOL)

    Chlorophyta hydrodictyon africanum was immobilized on a silica gel matrix to improve its mechanical properties. The algae-silica gel adsorbent was used for batch sorption studies of a cationic dye, methylene blue (MB). Optimum adsorption was obtained with a dosage of 0.8 g bio sorbent. Results from sorption studies ...

  16. Contaminant containment using polymer gel barriers

    NARCIS (Netherlands)

    Darwish, M.I.M.; Rowe, R.K.; Maarel, van der J.R.C.; Pel, L.; Huinink, H.P.; Zitha, P.L.J.

    2004-01-01

    Polymer gels are well known in the oil industry, but their potential for use as barriers to contaminant transport has not previously received significant study. As a first step, this paper examines the potential for a polyelectrolyte gel to serve as a barrier to the migration of sodium chloride. Two

  17. Serum release boosts sweetness intensity in gels

    NARCIS (Netherlands)

    Sala, G.; Stieger, M.A.; Velde, van de F.

    2010-01-01

    This paper describes the effect of serum release on sweetness intensity in mixed whey protein isolate/gellan gum gels. The impact of gellan gum and sugar concentration on microstructure, permeability, serum release and large deformation properties of the gels was determined. With increasing gellan

  18. Fast Processing of Sol-Gel TCO

    NARCIS (Netherlands)

    Deelen, J. van; Rem, M.; Arfsten, N.; Buskens, P.P.

    2016-01-01

    TCOs are usually deposited using sputtering or chemical vapor deposition, which have a yield of typically 50-75%. The sol gel method does not need low pressure and can be done with a high precursor yield in the range of 90 – 100%. Sol gel enables also the TCO function as a planarization or

  19. Meso-Decorated Switching-Knot Gels

    Science.gov (United States)

    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.

  20. Polymer architecture of magnetic gels: a review

    Science.gov (United States)

    Weeber, Rudolf; Hermes, Melissa; Schmidt, Annette M.; Holm, Christian

    2018-02-01

    In this review article, we provide an introduction to ferrogels, i.e. polymeric gels with embedded magnetic particles. Due to the interplay between magnetic and elastic properties of these materials, they are promising candidates for engineering and biomedical applications such as actuation and controlled drug release. Particular emphasis will be put on the polymer architecture of magnetic gels since it controls the degrees of freedom of the magnetic particles in the gel, and it is important for the particle-polymer coupling determining the mechanisms available for the gel deformation in magnetic fields. We report on the different polymer architectures that have been realized so far, and provide an overview of synthesis strategies and experimental techniques for the characterization of these materials. We further focus on theoretical and simulational studies carried out on magnetic gels, and highlight their contributions towards understanding the influence of the gels’ polymer architecture.

  1. On shear rheology of gel propellants

    Energy Technology Data Exchange (ETDEWEB)

    Rahimi, Shai; Peretz, Arie [RAFAEL, MANOR Propulsion and Explosive Systems Division, Haifa (Israel); Natan, Benveniste [Faculty of Aerospace Engineering, Technion - Israel Institute of Technology, Haifa (Israel)

    2007-04-15

    Selected fuel, oxidizer and simulant gels were prepared and rheologically characterized using a rotational rheometer. For fuel gelation both organic and inorganic gellants were utilized, whereas oxidizers and simulants were gelled with addition of silica and polysaccharides, respectively. The generalized Herschel-Bulkley constitutive model was found to most adequately represent the gels studied. Hydrazine-based fuels, gelled with polysaccharides, were characterized as shear-thinning pseudoplastic fluids with low shear yield stress, whereas inhibited red-fuming nitric acid (IRFNA) and hydrogen peroxide oxidizers, gelled with silica, were characterized as yield thixotropic fluids with significant shear yield stress. Creep tests were conducted on two rheological types of gels with different gellant content and the results were fitted by Burgers-Kelvin viscoelastic constitutive model. The effect of temperature on the rheological properties of gel propellant simulants was also investigated. A general rheological classification of gel propellants and simulants is proposed. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  2. Double elevator weakening for unilateral congenital superior oblique palsy with ipsilateral superior rectus contracture and lax superior oblique tendon.

    Science.gov (United States)

    Khan, Arif O

    2012-06-01

    In unilateral congenital superior oblique palsy, a large hypertropia is sometimes associated with ipsilateral contracture of the superior rectus muscle and apparent overaction of the contralateral superior oblique. Ipsilateral double elevator weakening is one surgical approach; however, this procedure could compromise supraduction. We report a series of three consecutive patients who underwent ipsilateral superior rectus and inferior oblique recessions for unilateral superior oblique palsy. Intraoperatively, all three patients were found to have a lax ipsilateral superior oblique tendon. Postoperatively, all three patients had satisfactory correction of the hypertropia and abnormal head position with minimal supraduction defect. This procedure seems to be an acceptable initial surgical option for treating congenital superior oblique muscle palsy with ipsilateral contracture of the superior rectus muscle, even when the ipsilateral superior oblique tendon is lax. Copyright © 2012 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.

  3. Field- to nano-scale evidence for weakening mechanisms along the fault of the 2016 Amatrice and Norcia earthquakes, Italy

    Science.gov (United States)

    Smeraglia, Luca; Billi, Andrea; Carminati, Eugenio; Cavallo, Andrea; Doglioni, Carlo

    2017-08-01

    In August and October 2016, two normal fault earthquakes (Mw 6.0 and Mw 6.5, respectively) struck the Amatrice-Norcia area in the central Apennines, Italy. The mainshocks nucleated at depths of 7-9 km with the co-seismic slip propagating upward along the Mt. Gorzano Fault (MGF) and Mt. Vettore Fault System (MVFS). To recognize possible weakening mechanisms along the carbonate-hosted seismogenic faults that generated the Amatrice-Norcia earthquakes, the fresh co-seismic fault exposure (i.e., "nastrino") exposed along the Mt. Vettoretto Fault was sampled and analyzed. This exposed fault belongs to the MVFS and was exhumed from 2-3 km depth. Over the fresh fault surface, phyllosilicates concentrated and localized along mm- to μm-thick layers, and truncated clasts and fluid-like structures were found. At the nano-scale, instead of their common platy-lamellar crystallographic texture, the analyzed phyllosilicates consist of welded nm-thick nanospherules and nanotubes similar to phyllosilicates deformed in rotary shear apparatus at seismic velocities or altered under high hydrothermal temperatures (> 250 °C). Moreover, the attitude of the Mt. Vettoretto Fault and its kinematics inferred from exposed slickenlines are consistent with the co-seismic fault and slip vectors obtained from the focal mechanisms computed for the 2016 mainshocks. All these pieces of evidence suggest that the Mt. Vettoretto Fault slipped seismically during past earthquakes and that co-seismic slip was assisted and facilitated at depths of synoptic picture of co-seismic processes and weakening mechanisms that may occur in carbonate-hosted seismogenic faults.

  4. Involvement of reactive oxygen species in endosperm cap weakening and embryo elongation growth during lettuce seed germination

    Science.gov (United States)

    Zhang, Yu; Chen, Bingxian; Xu, Zhenjiang; Shi, Zhaowan; Chen, Shanli; Huang, Xi; Chen, Jianxun; Wang, Xiaofeng

    2014-01-01

    Endosperm cap (CAP) weakening and embryo elongation growth are prerequisites for the completion of lettuce seed germination. Although it has been proposed that the cell wall loosening underlying these processes results from an enzymatic mechanism, it is still unclear which enzymes are involved. Here it is shown that reactive oxygen species (ROS), which are non-enzymatic factors, may be involved in the two processes. In Guasihong lettuce seeds imbibed in water, O2·– and H2O2 accumulated and peroxidase activity increased in the CAP, whereas its puncture force decreased. In addition, in the radicle, the increase in embryo growth potential was accompanied by accumulation of O2·– and an increase in peroxidase activity. Imbibing seeds in 0.3% sodium dichloroisocyanurate (SDIC) reduced endosperm viability and the levels of O2·–, H2O2, and peroxidase activity in the CAP, whereas the decrease in its puncture force was inhibited. However, in the embryo, SDIC did not affect the accumulation of O2·–, peroxidase activity, and the embryo growth potential. As a result, SDIC caused atypical germination, in which the endosperm ruptured at the boundary between the CAP and lateral endosperm. ROS scavengers and ROS generation inhibitors inhibited the CAP weakening and also decreased the embryo growth potential, thus decreasing the percentage of seed germination. Exogenous ROS and ROS generation inducers increased the percentage of CAP rupture to some extent, and the addition of H2O2 to 0.3% SDIC enabled some seeds to undergo typical germination. PMID:24744430

  5. Weakened Intracellular Zn2+-Buffering in the Aged Dentate Gyrus and Its Involvement in Erasure of Maintained LTP.

    Science.gov (United States)

    Takeda, Atsushi; Tamano, Haruna; Murakami, Taku; Nakada, Hiroyuki; Minamino, Tatsuya; Koike, Yuta

    2018-05-01

    Memory is lost by the increased influx of extracellular Zn 2+ into neurons. It is possible that intracellular Zn 2+ dynamics is modified even at non-zincergic medial perforant pathway-dentate granule cell synapses along with aging and that vulnerability to the modification is linked to age-related cognitive decline. To examine these possibilities, vulnerability of long-term potentiation (LTP) maintenance, which underlies memory retention, to modification of synaptic Zn 2+ dynamics was compared between young and aged rats. The influx of extracellular Zn 2+ into dentate granule cells was increased in aged rats after injection of high K + into the dentate gyrus, but not in young rats. This increase impaired maintained LTP in aged rats. However, the impairment was rescued by co-injection of CaEDTA, an extracellular Zn 2+ chelator, or CNQX, an AMPA receptor antagonist, which suppressed the Zn 2+ influx. Maintained LTP was also impaired in aged rats after injection of ZnAF-2DA into the dentate gyrus that chelates intracellular Zn 2+ , but not in young rats. Interestingly, the capacity of chelating intracellular Zn 2+ with intracellular ZnAF-2 was almost lost in the aged dentate gyrus 2 h after injection of ZnAF-2DA into the dentate gyrus, suggesting that intracellular Zn 2+ -buffering is weakened in the aged dentate gyrus, compared to the young dentate gyrus. In the dentate gyrus of aged rats, maintained LTP is more vulnerable to modification of intracellular Zn 2+ dynamics than in young rats, probably due to weakened intracellular Zn 2+ -buffering.

  6. [Analysis for Discordance of Positive and Negative Blood Typing by Gel Card].

    Science.gov (United States)

    Li, Cui-Ying; Xu, Hong; Lei, Hui-Fen; Liu, Juan; Li, Xiao-Wei

    2017-08-01

    To explore the method of Gel card identifying ABO blood group, determine the inconsistent cause and the distribution of disease affecting factors, and put forward a method of its solutions. To collect 240 positive and negative typing-discordant blood speciments from patients examined by Gel card and send these speciments to blood type reference laboratory for examining with the classic tube method and serological test, such as salivary blood-group substance, in order to performe genotyping method when serologic test can not be determined. Among 240 positive and negative typing-discordant blood speciments from patients examined by Gel card, 107 blood speciments were positive and negative consistent examined by false agglutination test (44.58%), 133 blood specinents were discordent examined by false agglutination (55.42%), out of them, 35 cases (14.58%) with inconsistent cold agglutination test, 22 cases (9.17%) with weakened AB antigenicity, 16 cases (6.67%) with ABO subtyping, 12 cases (5.00%) with positive direct antiglobulin test, 11 cases (4.58%) with reduced or without antibodies, 11 cases (4.58%) with false aggregation caused by drugs or protein, 11 cases (4.58%) with salivary blood-type substances, 8 cases (3.33%) with non-ABO alloantibody, and 7 cases (2.92%) with allogeneic bone marrow transplantation. The distribution of disease were following: blood disease (16.83%), tumor (11.88%), and cardiopulmonary diseases (11.39%); chi-square test results indicated that the distribution significantly different. The analysis of ABO blood grouping shows a variety factors influencing positive and negative blood typing, and the Gel Card identification can produc more false positive blood types. Therefore, more attention should be paid on the high incidence diseases, such as blood disease, tumor, and cardiopulmonary disease.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  9. Electrochemical corrosion behavior of composite MAO/sol-gel coatings on magnesium alloy AZ91D using combined micro-arc oxidation and sol-gel technique

    International Nuclear Information System (INIS)

    Shang Wei; Chen Baizhen; Shi Xichang; Chen Ya; Xiao Xiang

    2009-01-01

    Protective composite coatings were obtained on a magnesium alloy by micro-arc oxidation (MAO) and sol-gel technique. The coatings consisted of a MAO layer and a sol-gel layer. The microstructure and composition of the MAO coating and the composite coatings were analyzed by scanning electron microscopy (SEM) and energy dispersive X-rays (EDX). Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and total immersion tests were used to evaluate the corrosion behavior of these coatings in a 3.5 wt.% NaCl solution. The results show that the sol-gel layer provides corrosion protection by physically sealing the pores in the MAO coating and acting as a barrier. The composite coatings can suppress the corrosion process by preventing the corrosive ions from transferring or diffusing to the magnesium alloy substrate. This enhances the corrosion resistance of the magnesium alloy AZ91D significantly

  10. Ionic liquid gel materials: applications in green and sustainable chemistry

    OpenAIRE

    Marr, Patricia C.; Marr, Andrew C.

    2016-01-01

    Ionic liquid gel materials offer a way to further utilise ionic liquids in technological applications. Combining the controlled and directed assembly of gels, with the diverse applications of ionic liquids, enables the design of a heady combination of functional tailored materials, leading to the development of task specific / functional ionic liquid gels. This review introduces gels and gel classification, focusing on ionic liquid gels and their potential roles in a more sustainable future. ...

  11. Role of pluronics on rheological, drying and crack initiation of 'suckable' gels of decontamination; Role des pluronics sur les proprietes rheologiques, de sechage et de fracturation des gels 'aspirables' de decontamination

    Energy Technology Data Exchange (ETDEWEB)

    Bousquet, C

    2007-12-15

    The aim of this work was to understand the role of an addition of pluronics on the rheological behaviour, the drying and the fracturing of 'suckable' gels used for nuclear decontamination. The system studied was an aqueous suspension of silica (100 g/L of Aerosil 380) in a strong acidic medium (HNO{sub 3}/H{sub 3}PO{sub 4} 1.5 mol/L/1.5 mol/L) in presence of pluronics. Pluronics are amphiphilic tri-blocks copolymers composed of ethylene poly-oxide blocks and of propylene poly-oxide. The first part of this study deals with the characterization of the rheological properties of the gels. From viscosity retaking measurements, flow rheo-grams analysis and the viscoelastic properties of the gels, have been determined an improvement of the rheological properties of the gels significant from the addition of 5 g/L of copolymer. In a second part, the determination of adsorption isotherms coupled to small angles neutrons diffusion measurements has revealed that copolymers are adsorbed flat on silica in bridging the aggregates between them and that the improvement of the rheological behaviour of the gels is due to the increase of the bonds density of the gelled lattice. Moreover, beyond 10 g/L, the adsorption saturation of copolymers at the surface of the silica prevents the bridging of the aggregates which induces the gel destabilization. The last part of this work deals with the characterization of characteristic values of drying and of crack initiation of gels. Then is revealed a relation between the drying kinetics and the formation of cracks in the gel layer. Moreover, the study of the evolution of stresses in the gel layer during time allows to reveal that the addition of pluronics to the formulation of gels allows to improve the gel resistance to the crack initiation and to the delamination. (O.M.)

  12. Sol-gel technology for biomedical engineering

    International Nuclear Information System (INIS)

    Podbielska, H.; Ulatowska-Jarza, A.

    2005-01-01

    Sol-gel derived silica possess many promising features, including low-temperature preparation procedure, porosity, chemical and physical stability. Applications exploiting porous materials to encapsulate sensor molecules, enzymes and many other compounds, are developing rapidly. In this paper some potential applications, with emphasis on biomedical and environmental ones, are reviewed. The material preparation procedure is described and practical remarks on silica-based sol-gels are included. It is reported that sol-gels with entrapped various molecules may be used in construction of implants and coatings with bioactive properties. It is shown how to exploit the sol-gel production route for construction of sol-gel coated fiberoptic applicators for laser therapy. The applications of bioactive materials are discussed, as well. It is demonstrated that it is possible to immobilize photosensitive compounds in sol-gel matrix without loosing their photoactivity. Some examples of sol-gel based biosensors are demonstrated, as well, showing their potential for detecting various gases, toxic substances, acidity, humidity, enzymes and biologically active agents. (authors)

  13. Sol-Gel Manufactured Energetic Materials

    Science.gov (United States)

    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.

  14. Sol-gel bonding of silicon wafers

    International Nuclear Information System (INIS)

    Barbe, C.J.; Cassidy, D.J.; Triani, G.; Latella, B.A.; Mitchell, D.R.G.; Finnie, K.S.; Short, K.; Bartlett, J.R.; Woolfrey, J.L.; Collins, G.A.

    2005-01-01

    Sol-gel bonds have been produced between smooth, clean silicon substrates by spin-coating solutions containing partially hydrolysed silicon alkoxides. The two coated substrates were assembled and the resulting sandwich fired at temperatures ranging from 60 to 600 deg. C. The sol-gel coatings were characterised using attenuated total reflectance Fourier transform infrared spectroscopy, ellipsometry, and atomic force microscopy, while the corresponding bonded specimens were investigated using scanning electron microscopy and cross-sectional transmission electron microscopy. Mechanical properties were characterised using both microindentation and tensile testing. Bonding of silicon wafers has been successfully achieved at temperatures as low as 60 deg. C. At 300 deg. C, the interfacial fracture energy was 1.55 J/m 2 . At 600 deg. C, sol-gel bonding provided superior interfacial fracture energy over classical hydrophilic bonding (3.4 J/m 2 vs. 1.5 J/m 2 ). The increase in the interfacial fracture energy is related to the increase in film density due to the sintering of the sol-gel interface with increasing temperature. The superior interfacial fracture energy obtained by sol-gel bonding at low temperature is due to the formation of an interfacial layer, which chemically bonds the two sol-gel coatings on each wafer. Application of a tensile stress on the resulting bond leads to fracture of the samples at the silicon/sol-gel interface

  15. The effectiveness of betel leaf (Piper betle Linn extract gel and cocoa bean (Theobroma cacao L extract gel application against the hardness of enamel surface in vitro.

    Directory of Open Access Journals (Sweden)

    Juni Jekti Nugroho

    2017-04-01

    Full Text Available Objective : Nowadays several ways  have been evolved  to increase the hardness of the enamel surface as an effort to prevent caries. One of the alternatives that can be used is application of gel with herbal basic material. Material and Methods : The use of herbal basic material is preferred by people because the side effects are relatively small compared to synthetic drugs. Piper betle and cocoa beans are medicinal plants that is often used by people to inhibit caries. This is because piper betle and cocoa beans contain hardness that may influence the enamel surface. The purpose of this research was to determine the effect of piper betle extract gel and cocoa bean extract gel against the hardness of enamel surface. The samples, maxillary first premolar teeth, which has been extracted and does not have caries, were divided into 3 treatment groups: piper betle extract gel, cocoa bean extract gel, and distilled water as a negative control. Each treatment group consisted of 8 samples. The samples are decoronated in cemento-enamel junction (CEJ areas and planted on orthoplast blocks with labial surface facing up. Samples were applied in labial enamel surface to 5, 15 and 35 minutes period times. Samples before and after the application in each treatment group were measured using Universal Hardness Tester. Data were collected and analyzed using ANNOVA Repeated test. Results : Showed there were significant differences (p 0.05 of enamel surface hardness before and after the application of piper betel extract gel and distilled water. Conclusion : Therefore it can be concluded that cocoa been extract gel is more effective to increase the hardness of email surface.

  16. Unexpected Inflammatory Effects of Intravaginal Gels (Universal Placebo Gel and Nonoxynol-9 on the Upper Female Reproductive Tract: A Randomized Crossover Study.

    Directory of Open Access Journals (Sweden)

    Karen Smith-McCune

    Full Text Available Intravaginal anti-HIV microbicides could provide women with a self-controlled means for HIV prevention, but results from clinical trials have been largely disappointing. We postulated that unrecognized effects of intravaginal gels on the upper female reproductive tract might contribute to the lower-than-expected efficacy of HIV microbicides. Our objective was to study the effects of intravaginal gels on the immune microenvironment of the cervix and uterus. In this randomized crossover study, 27 healthy female volunteers used a nightly application of intravaginal nonoxynol-9 (N9 gel as a "failed" microbicide or the universal placebo gel (UPG as a "safe" gel (intervention cycles, or nothing (control cycle from the end of menses to the mid-luteal phase. At a specific time-point following ovulation, all participants underwent sample collection for measurements of T-cell phenotypes, gene expression, and cytokine/chemokine protein concentrations from 3 anatomic sites above the vagina: the cervical transformation zone, the endocervix and the endometrium. We used hierarchical statistical models to estimate mean (95% CI intervention effects, for N9 and UPG relative to control. Exposure to N9 gel and UPG generated a common "harm signal" that included transcriptional up-regulation of inflammatory genes chemokine (C-C motif ligand 20 (macrophage inflammatory factor-3alpha and interleukin 8 in the cervix, decreased protein concentrations of secretory leukocyte protease inhibitor, and transcriptional up-regulation of inflammatory mediators glycodelin-A and osteopontin in the endometrium. These results need to be replicated with a larger sample, but underscore the need to consider the effects of microbicide agents and gel excipients on the upper female reproductive tract in studies of vaginal microbicides.

  17. Novel hybrid sol-gel coatings for corrosion protection of AZ31B magnesium alloy

    International Nuclear Information System (INIS)

    Lamaka, S.V.; Montemor, M.F.; Galio, A.F.; Zheludkevich, M.L.; Trindade, C.; Dick, L.F.; Ferreira, M.G.S.

    2008-01-01

    This work aims to develop and study new anticorrosion films for AZ31B magnesium alloy based on the sol-gel coating approach. Hybrid organic-inorganic sols were synthesized by copolymerization of epoxy-siloxane and titanium or zirconium alkoxides. Tris(trimethylsilyl) phosphate was also used as additive to confer additional corrosion protection to magnesium-based alloy. A sol-gel coating, about 5-μm thick, shows good adhesion to the metal substrate and prevents corrosion attack in 0.005 M NaCl solution for 2 weeks. The sol-gel coating system doped with tris(trimethylsilyl)-phosphate revealed improved corrosion protection of the magnesium alloy due to formation of hydrolytically stable Mg-O-P chemical bonds. The structure and the thickness of the sol-gel film were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The corrosion behaviour of AZ31B substrates pre-treated with the sol-gel derived hybrid coatings was tested by electrochemical impedance spectroscopy (EIS). The chemical composition of the silylphosphate-containing sol-gel film at different depths was investigated by X-ray photoelectron spectroscopy (XPS) with depth profiling

  18. Thermoreversible gel formulation containing sodium lauryl sulfate as a potential contraceptive device.

    Science.gov (United States)

    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.

  19. Some Structural Observations of Self-Assembling, Fibrillar Gels Composed of Two-Directional Bolaform Arborols

    Energy Technology Data Exchange (ETDEWEB)

    Sun, J.

    2005-01-12

    Arborols are dumbbell shaped molecules (bolaform amphiphiles) in which a hydrophobic spacer separates two hydrophilic end groups. They are a valuable model for naturally occurring fibers, such as actin or amyloid. Applications to materials science can be envisioned. On cooling from warm aqueous or methanolic solutions, arborols spontaneously assemble into long fibers. When the solutions are above a certain concentration that depends on the hydrophilic/hydrophobic balance, this leads to thermally reversible gels stabilized by a mechanism that is poorly understood. With the help of wide angle X-ray scattering, details of the arborol fiber and gel structure were obtained on wet gels. The characteristic dimensions of the fibers vary in a sensible fashion with the molecular specifics. Solvent character appears to affect the average domain length of arborols stacked into fibers. Fluorescently labeled arborols were prepared. The label does not prevent incorporation into the fibrillar structure, rendering fibril bundles visible in wet gels. Bundles are visible in concentrated gels, but not in less concentrated sols. These results are consistent with observations of dried arborols using atomic force microscopy and with previously published freeze-fracture electron microscopy and small angle X-ray scattering experiments on dried gels.

  20. Exploring the possible applications of catechin (gel for oral care of the elderly and disabled individuals

    Directory of Open Access Journals (Sweden)

    Muneaki Tamura

    2012-08-01

    Full Text Available The oral cavity contains more than hundreds of microbial species. An increase in the number of these microorganisms like high pathogenic potential species, such as cariogenic and periodontopathic bacteria, and the change of microbial biota may result in, not only oral infection, but also systemic diseases, such as infective endocarditis and aspiration pneumonia. It is very important to control the growth of these microorganisms and its biota just after oral cleaning in order to suppress disease onset. In this regard, it is useful to use the anti-microbial component which acts against pathogenic microorganisms. Here, we highlight the importance of catechin, and feature its possible oral, especially periodontal applications. By combining catechin with gel (catechin gel, antimicrobial activity of catechin was prolonged in gel and catechin anti-oxidization property was observed. Catechin gel inhibited the growth of the Actinomyces, periodontopathic bacteria and Candida strains tested, but did not inhibit that of the oral streptococci that are important in the normal oral flora. In contrast, commercially available moisture gels containing antimicrobial components showed antimicrobial activity against all of the tested strains including the oral streptococci. This show that catechin has selective antimicrobial activity, attributable to hydrogen peroxide production. This paper reviews previous works using catechin and, likewise, catechin gel may be show its possible oral application for prevent dental caries and periodontal disease.

  1. Polymer gel dosimeter with AQUAJOINT® as hydrogel matrix

    Science.gov (United States)

    Maeyama, Takuya; Ishida, Yasuhiro; Kudo, Yoshihiro; Fukasaku, Kazuaki; Ishikawa, Kenichi L.; Fukunishi, Nobuhisa

    2018-05-01

    We report a polymer gel dosimeter based on a new gel matrix (AQUAJOINT®) that is a thermo-irreversible hydrogel formed by mixing two types of water-based liquids at room temperature. Normoxic N-vinylpyrrolidone-based polymer gels were prepared with AQUAJOINT® instead of gelatin. This AQUAJOINT®-based gel dosimeter exhibits a 2.5-fold increase in sensitivity over a gelatin-based gel dosimeter and a linear dose-response in the dose range of 0-8 Gy. This gel has heat resistance in a jar and controlled gel properties such as viscoelastic and mechanical characters, which may be useful for deformable polymer gel dosimetry.

  2. PVA gel as a potential adhesion barrier: a safety study in a large animal model of intestinal surgery.

    Science.gov (United States)

    Renz, Bernhard W; Leitner, Kurt; Odermatt, Erich; Worthley, Daniel L; Angele, Martin K; Jauch, Karl-Walter; Lang, Reinhold A

    2014-03-01

    Intra-abdominal adhesions following surgery are a major source of morbidity and mortality including abdominal pain and small bowel obstruction. This study evaluated the safety of PVA gel (polyvinyl alcohol and carboxymethylated cellulose gel) on intestinal anastomoses and its potential effectiveness in preventing adhesions in a clinically relevant large animal model. Experiments were performed in a pig model with median laparotomy and intestinal anastomosis following small bowel resection. The primary endpoint was the safety of PVA on small intestinal anastomoses. We also measured the incidence of postoperative adhesions in PVA vs. control groups: group A (eight pigs): stapled anastomosis with PVA gel compared to group B (eight pigs), which had no PVA gel; group C (eight pigs): hand-sewn anastomosis with PVA gel compared to group B (eight pigs), which had no anti-adhesive barrier. Animals were sacrificed 14 days after surgery and analyzed. All anastomoses had a patent lumen without any stenosis. No anastomoses leaked at an intraluminal pressure of 40 cmH2O. Thus, anastomoses healed very well in both groups, regardless of whether PVA was administered. PVA-treated animals, however, had significantly fewer adhesions in the area of stapled anastomoses. The hand-sewn PVA group also had weaker adhesions and trended towards fewer adhesions to adjacent organs. These results suggest that PVA gel does not jeopardize the integrity of intestinal anastomoses. However, larger trials are needed to investigate the potential of PVA gel to prevent adhesions in gastrointestinal surgery.

  3. Acoustic evaluation of polymer gel dosimeters

    International Nuclear Information System (INIS)

    Mather, M.L.; De Deene, Y.; Baldock, C.; Whittaker, A.K.

    2002-01-01

    Advances in radiotherapy treatment techniques such as intensity modulated radiotherapy are placing increasing demands on radiation dosimetry for verification of dose distributions in 3D. In response, polymer gel dosimeters that are capable of recording dose distributions in 3D are currently being developed. Recently, a new technique for evaluation of absorbed dose distributions in these dosimeters using ultrasound was introduced. The current work aims to demonstrate the potential of ultrasound as an evaluation technique for polymer gel dosimeters and to investigate the ultrasound properties of two different dosimeter formulations, PAG and MAGIC gels

  4. Pulsed field gel electrophoresis a practical guide

    CERN Document Server

    Birren, Bruce

    1993-01-01

    Pulsed Field Gel Electrophoresis: A Practical Guide is the first laboratory manual to describe the theory and practice of this technique. Based on the authors' experience developing pulsed field gel instruments and teaching procedures, this book provides everything a researcher or student needs to know in order to understand and carry out pulsed field gel experiments. Clear, well-tested protocols assume only that users have a basic familiarity with molecular biology. Thorough coverage of useful data, theory, and applications ensures that this book is also a lasting resource for more adv

  5. Applications of sol gel ceramic coatings

    International Nuclear Information System (INIS)

    Barrow, D.

    1996-01-01

    The sol gel method is a chemical technique in which polycrystalline ceramic films are fabricated from a solution of organometallic precursors. The technique is attractive for many industrial applications because it is a simple (films are processed in air), flexible (can be used to coat complex geometries) and cost effective (does not require expensive equipment) process. In addition, dense, high quality coatings can be achieved at much lower temperatures than is generally required for sintering bulk ceramics. In this paper the conventional sol gel method and the new datec process are reviewed and potential applications of sol gel coatings in automotive, aerospace, petrochemical, nuclear and electronic industries are discussed. (orig.)

  6. Administration of dried Aloe vera gel powder reduced body fat mass in diet-induced obesity (DIO) rats.

    Science.gov (United States)

    Misawa, Eriko; Tanaka, Miyuki; Nabeshima, Kazumi; Nomaguchi, Kouji; Yamada, Muneo; Toida, Tomohiro; Iwatsuki, Keiji

    2012-01-01

    The aim of the present study was to investigate the anti-obesity effects of Aloe vera gel administration in male Sprague-Dawley (SD) rats with diet-induced obesity (DIO). SD rats at 7 wk of age were fed either a standard diet (10 kcal% fat) (StdD) or high-fat (60 kcal% fat) diet (HFD) during the experimental period. Four weeks after of HFD-feeding, DIO rats (11 wk of age) were orally administered with two doses of Aloe vera gel powder (20 and 200 mg/kg/d) for 90 d. Body weights (g) and body fat (%) of HFD fed rats were significantly higher than those of StdD-fed rats. Although a modest decrease of body weight (g) was observed with the administration of dried Aloe vera gel powder, both subcutaneous and visceral fat weight (g) and body fat (%) were reduced significantly in Aloe vera gel-treated rats. Serum lipid parameters elevated by HFD were also improved by the Aloe vera gel treatment. The oxygen consumption (VO(2)), an index of energy expenditure, was decreased in HFD-fed rats compared with that in StdD-fed rats. Administration of Aloe vera gel reversed the change in VO(2) in the HFD-fed rats. These results suggest that intake of Aloe vera gel reduced body fat accumulation, in part, by stimulation of energy expenditure. Aloe vera gel might be beneficial for the prevention and improvement of diet-induced obesity.

  7. Exploring encapsulation mechanism of DNA and mononucleotides in sol-gel derived silica.

    Science.gov (United States)

    Kapusuz, Derya; Durucan, Caner

    2017-07-01

    The encapsulation mechanism of DNA in sol-gel derived silica has been explored in order to elucidate the effect of DNA conformation on encapsulation and to identify the nature of chemical/physical interaction of DNA with silica during and after sol-gel transition. In this respect, double stranded DNA and dAMP (2'-deoxyadenosine 5'-monophosphate) were encapsulated in silica using an alkoxide-based sol-gel route. Biomolecule-encapsulating gels have been characterized using UV-Vis, 29 Si NMR, FTIR spectroscopy and gas adsorption (BET) to investigate chemical interactions of biomolecules with the porous silica network and to examine the extent of sol-gel reactions upon encapsulation. Ethidium bromide intercalation and leach out tests showed that helix conformation of DNA was preserved after encapsulation. For both biomolecules, high water-to-alkoxide ratio promoted water-producing condensation and prevented alcoholic denaturation. NMR and FTIR analyses confirmed high hydraulic reactivity (water adsorption) for more silanol groups-containing DNA and dAMP encapsulated gels than plain silica gel. No chemical binding/interaction occurred between biomolecules and silica network. DNA and dAMP encapsulated silica gelled faster than plain silica due to basic nature of DNA or dAMP containing buffer solutions. DNA was not released from silica gels to aqueous environment up to 9 days. The chemical association between DNA/dAMP and silica host was through phosphate groups and molecular water attached to silanols, acting as a barrier around biomolecules. The helix morphology was found not to be essential for such interaction. BET analyses showed that interconnected, inkbottle-shaped mesoporous silica network was condensed around DNA and dAMP molecules.

  8. Assessment of a gel-type chelating preparation containing 1-hydroxyethylidene-1, 1-bisphosphonate.

    Science.gov (United States)

    Girard, S; Paqué, F; Badertscher, M; Sener, B; Zehnder, M

    2005-11-01

    To test an aqueous gel containing 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) regarding its interactions with sodium hypochlorite, its calcium binding capacity, and its potential in preventing the formation of a smear layer when used in conjunction with rotary root canal preparation. The experimental aqueous gel consisted of (w/v) 2% alginate, 3% aerosil, 10% Tween 80 and 18% HEBP. Interactions of gel components with hypochlorite were assessed using iodometric titration and monochromatic ultraviolet spectrometry. Two commercial paste-type chelators containing ethylenediaminetetraacetic acid (EDTA) and peroxide (RC-Prep and Glyde) served as controls. Calcium-binding capacities were measured in mixtures with a Ca2+ standard solution buffered at pH 10 using a calcium-selective measuring chain. Finally, root canals of 16 extracted single-rooted premolars per group were instrumented using ProFile instruments dipped in the experimental gel, RC-Prep, or nothing. Additionally, canals were rinsed with 10 mL of a 1% NaOCl solution during/after preparation. Smear scores in instrumented teeth were monitored using scanning electron microscopy. None of the experimental gel components showed short-term interactions with hypochlorite, whilst EDTA, peroxide, RC-Prep and Glyde immediately reduced the hypochlorite in solution. The experimental gel chelated 30 mg Ca2+ g-1, compared with 16 mg Ca2+ g-1 and 11 mg Ca2+ g-1 chelated by RC-Prep and Glyde respectively. Smear scores obtained with the experimental gel were significantly (P<0.05) lower than with RC-Prep in coronal and middle root thirds, whilst no differences were observed in apical root thirds. Under the conditions of this study, an HEBP gel appeared advantageous over currently available products.

  9. Water holding of protein gels

    NARCIS (Netherlands)

    Urbonaite, V.

    2015-01-01

    Abstract

    Food products are typically multicomponent systems, where often the spatial volume is set by a protein continuous network. The ability of protein-based food products to entrap water and to prevent its exudation upon mechanical deformation is important for the

  10. Migration of the deforming zone during seismic shear and implications for field observations, dynamic weakening, and the onset of melting

    Science.gov (United States)

    Platt, J. D.; Rice, J. R.

    2013-12-01

    diffusivity. Similarly, regions of high reactant mass fraction allow more vigorous thermal decomposition and thus attract straining. The migration outlined above has three important consequences: (1) Migration must be taken into account when inferring the width of the deforming zone from field observations. Even when the zone of localized straining is only a few tens of microns wide, migration can lead to a final strain profile with a zone of roughly uniform strain on the order of a millimeter wide. (2) For thermal pressurization the width of the deforming zone largely controls the initial weakening of the fault. A pre-existing zone of low hydraulic diffusivity localizes straining more efficiently leading to faster weakening. Thus, dynamic weakening may be controlled by the gouge properties in the region most susceptible to strain rate localization. (3) Migration of the localized zone distributes frictional heating over a broader region, leading to a much lower temperature rise when compared with a stationary shear zone. Our results rarely show temperatures above the melting temperature, providing a plausible explanation for the fact that melt signatures are rarely observed on mature faults active at shallower crustal depths.

  11. Ellipticity Weakens Chameleon Screening

    OpenAIRE

    Burrage, Clare; Copeland, Edmund J.; Stevenson, James

    2014-01-01

    The chameleon mechanism enables a long range fifth force to be screened in dense environments when non-trivial self interactions of the field cause its mass to increase with the local density. To date, chameleon fifth forces have mainly been studied for spherically symmetric sources, however the non-linear self interactions mean that the chameleon responds to changes in the shape of the source differently to gravity. In this work we focus on ellipsoidal departures from spherical symmetry and ...

  12. Pneumonia - weakened immune system

    Science.gov (United States)

    ... lung ( pleural effusion ). Tests may include: Arterial blood gases Blood chemistries Blood culture Bronchoscopy (in certain cases) ... 2018, A.D.A.M., Inc. Duplication for commercial use must be authorized in writing by ADAM ...

  13. Velocity- and slip-dependent weakening on the Tohoku plate boundary fault: shallow coseismic slip facilitated by foreshock afterslip

    Science.gov (United States)

    Ito, Y.; Ikari, M.; Ujiie, K.; Kopf, A.

    2016-12-01

    Understanding of role of slow earthquakes as they relate to the occurrence of both megathrust earthquakes and tsunami earthquakes is necessary to mitigate these disasters in the near future. Laboratory shearing experiments is one of important approach to evaluate these relationships. Here, we use powdered gouge samples from JFAST (IODP Expedition 343) Hole C0019E, core sample 17R-1, which is the plate boundary fault zone in the Japan Trench subduction zone. In this region, both large coseismic slip during the 2011 Tohoku-Oki earthquake as well as discrete slow slip events (SSE) have occurred. Experiments were conducted in a single-direct shear apparatus under normal stress of 16 MPa, with total shear displacements of up to 16 mm. We evaluate both the velocity- and slip-dependence of friction by extracting the velocity-dependent friction parameters a, b, and Dc, and measuring the rate of change in friction coefficient with shear displacement as the slip-dependence of friction. We report that in friction experiments using the Tohoku fault zone samples, an increase in sliding velocity exceeding that of earthquake afterslip can induce a change from steady-state frictional strength or slip hardening friction to slip-weakening frictional behavior. Our results show that the slip weakening is observed when the slip velocity exceeds 1 x 10-6 m/s during our experiments, while steady-state frictional strength or slip hardening is observed below 1x10-6 m/s. In the Japan Trench region, two slow events were observed at the downdip edge of the mainshock coseismic slip zone (< 30 m) were observed. These are an episodic SSE with a slip velocity of 0.1 x 10-6, and afterslip after the largest foreshock with a slip velocity of 2 x 10-6 m/s. This suggests that the afterslip may have facilitated the large coseismic slip during the mainshock on the plate boundary fault of the Tohoku-Oki earthquake.

  14. Simultaneous reductions in emissions of black carbon and co-emitted species will weaken the aerosol net cooling effect

    Science.gov (United States)

    Wang, Z. L.; Zhang, H.; Zhang, X. Y.

    2015-04-01

    Black carbon (BC), a distinct type of carbonaceous material formed from the incomplete combustion of fossil and biomass based fuels under certain conditions, can interact with solar radiation and clouds through its strong light-absorption ability, thereby warming the Earth's climate system. Some studies have even suggested that global warming could be slowed down in the short term by eliminating BC emission due to its short lifetime. In this study, we estimate the influence of removing some sources of BC and other co-emitted species on the aerosol radiative effect by using an aerosol-climate atmosphere-only model BCC_AGCM2.0.1_CUACE/Aero with prescribed sea surface temperature and sea ice cover, in combination with the aerosol emissions from the Representative Concentration Pathways (RCPs) scenarios. We find that the global annual mean aerosol net cooling effect at the top of the atmosphere (TOA) will be enhanced by 0.12 W m-2 compared with recent past year 2000 levels if the emissions of only BC are reduced to the level projected for 2100 based on the RCP2.6 scenario. This will be beneficial~for the mitigation of global warming. However, both aerosol negative direct and indirect radiative effects are weakened when BC and its co-emitted species (sulfur dioxide and organic carbon) are simultaneously reduced. Relative to year 2000 levels, the global annual mean aerosol net cooling effect at the TOA will be weakened by 1.7-2.0 W m-2 if the emissions of all these aerosols are decreased to the levels projected for 2100 in different ways based on the RCP2.6, RCP4.5, and RCP8.5 scenarios. Because there are no effective ways to remove the BC exclusively without influencing the other co-emitted components, our results therefore indicate that a reduction in BC emission can lead to an unexpected warming on the Earth's climate system in the future.

  15. Sodium Dedecyl Suphate Polyacrilamide Gel Electrophosis of ...

    African Journals Online (AJOL)

    polyacrilamide gel electrophoresis (SDS-PAGE). The isolates were obtained from the faeces of diarrhoeic children with the age range of 0 t 36 months attending paediatric clinic at the Lagos University Teaching Hospital (LUTH) and Obafemi Awolowo ...

  16. Preparation of zirconium molybdate gel generator

    International Nuclear Information System (INIS)

    Charoen, S.; Aungurarat, G.; Laohawilai, S.; Sukontpradit, W.; Jingjit, S.

    1994-01-01

    A procedure for preparation of 99mTc generator based on conversion to zirconium molybdate gel of 99Mo produced by neutron activation was reported. The gel was prepared from zirconium oxychloride solution pH 1.6, ammonium molybdate solution pH 3-5 and mole ratio of Zr:Mo 1:1 which had water content about 7-8%. Small generators containing 1-1.5 g of gel were eluted with average efficiencies of 77% and the activity peak in the first 3 ml of 10 ml of saline solution. The amount of Mo and Zr in eluates were below the acceptance limit. The gel generators of activity about 100 mCi were prepared and had the good performance in elutability and stability

  17. Buckling of paramagnetic chains in soft gels

    Science.gov (United States)

    Huang, Shilin; Pessot, Giorgio; Cremer, Peet; Weeber, Rudolf; Holm, Christian; Nowak, Johannes; Odenbach, Stefan; Menzel, Andreas M.; Auernhammer, Günter K.

    We study the magneto-elastic coupling behavior of paramagnetic chains in soft polymer gels exposed to external magnetic fields. To this end, a laser scanning confocal microscope is used to observe the morphology of the paramagnetic chains together with the deformation field of the surrounding gel network. The paramagnetic chains in soft polymer gels show rich morphological shape changes under oblique magnetic fields, in particular a pronounced buckling deformation. The details of the resulting morphological shapes depend on the length of the chain, the strength of the external magnetic field, and the modulus of the gel. Based on the observation that the magnetic chains are strongly coupled to the surrounding polymer network, a simplified model is developed to describe their buckling behavior. A coarse-grained molecular dynamics simulation model featuring an increased matrix stiffness on the surfaces of the particles leads to morphologies in agreement with the experimentally observed buckling effects.

  18. K-Basin gel formation studies

    International Nuclear Information System (INIS)

    Beck, M.A.

    1998-01-01

    A key part of the proposed waste treatment for K Basin sludge is the elimination of reactive uranium metal by dissolution in nitric acid (Fkirnent, 1998). It has been found (Delegard, 1998a) that upon nitric acid dissolution of the sludge, a gel sometimes forms. Gels are known to sometimes impair solid/liquid separation and/or material transfer. The purpose of the work reported here is to determine the cause(s) of the gel formation and to determine operating parameters for the sludge dissolution that avoid formation of gel. This work and related work were planned in (Fkunent, 1998), (Jewett, 1998) and (Beck, 1998a). This report describes the results of the tests in (Beck, 1998a) with non-radioactive surrogates

  19. Formulation of Bioadhesive Carbomer Gel Incorporating Drug ...

    African Journals Online (AJOL)

    incorporated into carbomer gel and evaluated for drug release. Results: ... localized delivery system for the treatment inflammation and infection in periodontal pockets. ..... loaded with diclofenac sodium for intra- articular administration. J Drug ...

  20. Structure of gels layers with cells

    Science.gov (United States)

    Pokusaev, B. G.; Karlov, S. P.; Vyazmin, A. V.; Nekrasov, D. A.; Zakharov, N. S.; Khramtsov, D. P.; Skladnev, D. A.; Tyupa, D. V.

    2017-11-01

    The structure of two-layer agarose gels containing yeast cells is investigated experimentally by spectrometry, to shed a light on the theoretical foundations for the development of bioreactors by the method of 3D bioprinting. Due to division, cells overcome the layer of the dispersion phase separating successively applied layers of the agarose gel. However a gel layer of 100 μm thick with a high concentration of silver nanoparticles completely excludes the infiltration of yeast cells through it. A special sort of agarose is suggested where the concentration of silver nanoparticles formed by cells from salt of silver can serve as an indicator of the state of the yeast cells in the volume of the gel.

  1. Thixotropic corrosive gels for nuclear decontamination

    International Nuclear Information System (INIS)

    Bargues, St.

    1998-01-01

    The aim of this thesis was the development of corrosive gels for metallic surface decontamination. These gels formulation, based on a powerful oxidant (the cerium IV), the nitric acid, a mineral charge (silica) and a non ionic surface-active, has been developed according to the specific constraints of the nuclear industry. The objective was to prepare thixotropic gels becoming liquid after shacking to allow an easy pulverization and coming again solid to permit a perfect adhesion on the metallic surface. This rheological study of the gels has been completed by an evaluation of their corrosive properties. The last part of the work presents an industrial utilization during two years. (A.L.B.)

  2. Sol-gel antireflective coating on plastics

    Science.gov (United States)

    Ashley, Carol S.; Reed, Scott T.

    1990-01-01

    An antireflection film made from a reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

  3. Coordination Polymer Gels by Electron Beam

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ji Ha; Cho, Young Je; Jung, Jong Hwa [Gyeongsang National Univ., Jinju (Korea, Republic of)

    2011-07-01

    Hydrogenation of a pyridine derivative possessing tetrazole moieties as end groups, without long alkyl chain groups, results in the formation of a Mg(NO{sub 3}){sub 2} coordination polymer gel. The polymer exhibits a strong fluorescence enhancement upon gel formation. 1 can also be gloated with a variety of magnesium anions such as SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, Cl{sup -}, Br{sup -} and I{sup -}, indicating that the coordination polymer gel formation of 1 does not strongly depends on anions. The Seam and ABM images of Mg{sup 2+} coordination polymer gel 1 display a flabbier network with several micrometers long, widths in the range 60-70 nm and thicknesses of about 3 nm. In addition, photophysical studies show that the hydrogel exhibits a typical {pi}-{pi} transition and gives rise to high fluorescence behavior. The coordination polymer hydrogel exhibits viscoelastic behavior as evidenced from the rheological studies.

  4. Maize Arabinoxylan Gels as Protein Delivery Matrices

    Directory of Open Access Journals (Sweden)

    Ana Luisa Martínez-López

    2009-04-01

    Full Text Available The laccase induced gelation of maize bran arabinoxylans at 2.5% (w/v in the presence of insulin or β-lactoglobulin at 0.1% (w/v was investigated. Insulin and β-lacto-globulin did not modify either the gel elasticity (9 Pa or the cross-links content (0.03 and 0.015 mg di- and triferulic acids/mg arabinoxylan, respectively. The protein release capability of the gel was also investigated. The rate of protein release from gels was dependent on the protein molecular weight. The apparent diffusion coefficient was 0.99 × 10-7 and 0.79 × 10-7 cm2/s for insulin (5 kDa and β-lactoglobulin (18 kDa, respectively. The results suggest that maize bran arabinoxylan gels can be potential candidates for the controlled release of proteins.

  5. Oxygen-17 relaxation in aqueous agarose gels

    International Nuclear Information System (INIS)

    Ablett, S.; Lillford, P.J.

    1977-01-01

    Nuclear magnetic relaxation of oxygen-17 in H 2 17 O enriched agarose gels shows that existing explanations of water behaviour are oversimplified. Satisfactory models must include at least three proton phases, two of which involve water molecules. (Auth.)

  6. Fricke xylenol gel energy dependence

    International Nuclear Information System (INIS)

    Costa, Rosangela T.; Moreira, Marcos V.; Almeida, Adelaide de

    2009-01-01

    The advancement of technology has increasingly use the of ionizing radiation mainly in the areas of medicine, industry and research. The development of instruments and methods for an effective performance for detection and measurement of each radiation area was crucial. The literature have demonstrated the effectiveness of the Fricke Xylenol Gel (FXG) as an adequate chemical sensor to be used for dosimetry, once its effective atomic number and density are near to those of the soft tissue. The use of photon beams for therapeutic purpose requires knowledge of their characteristics that can vary for each equipment. Therefore, is important to know all parameters involved for the patient irradiation as the total geometry involved, type of radiation, target material composition and beam energy, that have to be taken into account in the beam dosimetry for the treatment success being the energy parameter is one of the most important. This work was developed to study the energetic dependence of the FXG dosimeter. This chemical solution is made with gelatine 300 Bloom, ferrous ammonium sulfate, xylenol orange, sulfuric acid and Milli-Q water and is based on the Fe +2 oxidation to Fe +3 , due to the ionizing radiation leading to the xylenol orange - ferric complex formation, that is linear depend on the absorbed dose. The FXG samples were irradiated with photons of different energies and the absorbance measurements were done with the spectrophotometric technique at the 585 nm, FXG highest absorption peak. The energetic dependence results presented a stronger dependence for low energies and almost independence for high energies, as expected by the interaction of radiation with matter. (author)

  7. Polymer gel dosimeters with enhanced sensitivity for use in x-ray CT polymer gel dosimetry

    International Nuclear Information System (INIS)

    Jirasek, A; Hilts, M; McAuley, K B

    2010-01-01

    A primary limitation of current x-ray CT polymer gel dosimetry is the low contrast, and hence poor dose resolution, of dose images produced by the system. The low contrast is largely due to the low-dose sensitivity of current formulations of polymer gel for x-ray CT imaging. This study reports on the investigation of new dosimeter formulations with improved dose sensitivity for x-ray CT polymer gel dosimetry. We incorporate an isopropanol co-solvent into an N-isopropylacrylamide-based gel formulation in order to increase the total monomer/crosslinker concentration (%T) within the formulation. It is shown that gels of high %T exhibit enhanced dose sensitivity and dose resolutions over traditional formulations. The gels are shown to be temporally stable and reproducible. A single formulation (16%T) is used to demonstrate the capabilities of the x-ray CT polymer gel dosimetry system in measuring known dose distributions. A 1 L gel volume is exposed to three separate irradiations: a single-field percent depth dose, a two-field 'cross' and a three-field 'test case'. The first two irradiations are used to generate a dose calibration curve by which images are calibrated. The calibrated images are compared with treatment planning predictions and it is shown that the x-ray CT polymer gel dosimetry system is capable of capturing spatial and dose information accurately. The proposed new gel formulation is shown to be sensitive, stable and to improve the dose resolution over current formulations so as to provide a feasible gel for clinical applications of x-ray CT polymer gel dosimetry.

  8. Polymer gel dosimeters with enhanced sensitivity for use in x-ray CT polymer gel dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Jirasek, A [Department of Physics and Astronomy, University of Victoria, Victoria BC V8W 3P6 (Canada); Hilts, M [Medical Physics, BC Cancer Agency-Vancouver Island Centre, Victoria BC V6R 2B6 (Canada); McAuley, K B, E-mail: jirasek@uvic.c [Department of Chemical Engineering, Queens University, Kingston, ON K7 L 3N6 (Canada)

    2010-09-21

    A primary limitation of current x-ray CT polymer gel dosimetry is the low contrast, and hence poor dose resolution, of dose images produced by the system. The low contrast is largely due to the low-dose sensitivity of current formulations of polymer gel for x-ray CT imaging. This study reports on the investigation of new dosimeter formulations with improved dose sensitivity for x-ray CT polymer gel dosimetry. We incorporate an isopropanol co-solvent into an N-isopropylacrylamide-based gel formulation in order to increase the total monomer/crosslinker concentration (%T) within the formulation. It is shown that gels of high %T exhibit enhanced dose sensitivity and dose resolutions over traditional formulations. The gels are shown to be temporally stable and reproducible. A single formulation (16%T) is used to demonstrate the capabilities of the x-ray CT polymer gel dosimetry system in measuring known dose distributions. A 1 L gel volume is exposed to three separate irradiations: a single-field percent depth dose, a two-field 'cross' and a three-field 'test case'. The first two irradiations are used to generate a dose calibration curve by which images are calibrated. The calibrated images are compared with treatment planning predictions and it is shown that the x-ray CT polymer gel dosimetry system is capable of capturing spatial and dose information accurately. The proposed new gel formulation is shown to be sensitive, stable and to improve the dose resolution over current formulations so as to provide a feasible gel for clinical applications of x-ray CT polymer gel dosimetry.

  9. A Practical Use for FXG Gel Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Olding, T; Salomons, G; Darko, J; Schreiner, L J, E-mail: Tim.Olding@krcc.on.c

    2010-11-01

    In-phantom Fricke-xylenol orange-gelatin (FXG) gel dosimetry yields three dimensional (3D) dose data for intensity modulated radiation therapy (IMRT) treatment plan verification within 18-24 hours from the point of request. The information obtained from a 3% dose difference, 3 mm distance-to-agreement gamma function comparison between treatment plan dose and gel-measured dose then provides a useful secondary 3D quality assurance check of the treatment plan prior to delivery.

  10. Conducting Polymer Electrodes for Gel Electrophoresis

    OpenAIRE

    Bengtsson, Katarina; Nilsson, Sara; Robinson, Nathaniel D

    2014-01-01

    In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that p-conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis) systems. In this report, we extend our previous result to gel ...

  11. A theory for fracture of polymeric gels

    Science.gov (United States)

    Mao, Yunwei; Anand, Lallit

    2018-06-01

    A polymeric gel is a cross-linked polymer network swollen with a solvent. If the concentration of the solvent or the deformation is increased to substantial levels, especially in the presence of flaws, then the gel may rupture. Although various theoretical aspects of coupling of fluid permeation with large deformation of polymeric gels are reasonably well-understood and modeled in the literature, the understanding and modeling of the effects of fluid diffusion on the damage and fracture of polymeric gels is still in its infancy. In this paper we formulate a thermodynamically-consistent theory for fracture of polymeric gels - a theory which accounts for the coupled effects of fluid diffusion, large deformations, damage, and also the gradient effects of damage. The particular constitutive equations for fracture of a gel proposed in our paper, contain two essential new ingredients: (i) Our constitutive equation for the change in free energy of a polymer network accounts for not only changes in the entropy, but also changes in the internal energy due the stretching of the Kuhn segments of the polymer chains in the network. (ii) The damage and failure of the polymer network is taken to occur by chain-scission, a process which is driven by the changes in the internal energy of the stretched polymer chains in the network, and not directly by changes in the configurational entropy of the polymer chains. The theory developed in this paper is numerically implemented in an open-source finite element code MOOSE, by writing our own application. Using this simulation capability we report on our study of the fracture of a polymeric gel, and some interesting phenomena which show the importance of the diffusion of the fluid on fracture response of the gel are highlighted.

  12. Improving calibration accuracy in gel dosimetry

    International Nuclear Information System (INIS)

    Oldham, M.; McJury, M.; Webb, S.; Baustert, I.B.; Leach, M.O.

    1998-01-01

    A new method of calibrating gel dosimeters (applicable to both Fricke and polyacrylamide gels) is presented which has intrinsically higher accuracy than current methods, and requires less gel. Two test-tubes of gel (inner diameter 2.5 cm, length 20 cm) are irradiated separately with a 10x10cm 2 field end-on in a water bath, such that the characteristic depth-dose curve is recorded in the gel. The calibration is then determined by fitting the depth-dose measured in water, against the measured change in relaxivity with depth in the gel. Increased accuracy is achieved in this simple depth-dose geometry by averaging the relaxivity at each depth. A large number of calibration data points, each with relatively high accuracy, are obtained. Calibration data over the full range of dose (1.6-10 Gy) is obtained by irradiating one test-tube to 10 Gy at dose maximum (D max ), and the other to 4.5 Gy at D max . The new calibration method is compared with a 'standard method' where five identical test-tubes of gel were irradiated to different known doses between 2 and 10 Gy. The percentage uncertainties in the slope and intercept of the calibration fit are found to be lower with the new method by a factor of about 4 and 10 respectively, when compared with the standard method and with published values. The gel was found to respond linearly within the error bars up to doses of 7 Gy, with a slope of 0.233±0.001 s -1 Gy -1 and an intercept of 1.106±0.005 Gy. For higher doses, nonlinear behaviour was observed. (author)

  13. White-light-emitting supramolecular gels.

    Science.gov (United States)

    Praveen, Vakayil K; Ranjith, Choorikkat; Armaroli, Nicola

    2014-01-07

    Let there be light, let it be white: Recent developments in the use of chromophore-based gels as scaffolds for the assembly of white-light-emitting soft materials have been significant. The main advantage of this approach lies in the facile accommodation of selected luminescent components within the gel. Excitation-energy-transfer processes between these components ultimately generate the desired light output. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Instrumental texture profile analysis of gelatin gel extracted from grouper skin and commercial (bovine and porcine) gelatin gels.

    Science.gov (United States)

    Rahman, Mohammad Shafiur; Al-Mahrouqi, Abdullah Issa

    2009-01-01

    Mechanical compression was used to study the gelling characteristics of gelatin gels. Texture profile analysis (TPA) showed that the hardness of fish and mammalian gelatin increased significantly as the concentrations of gels increased. TPA attributes of 10% fish skin gel showed significant differences from those obtained from 20% and 30% gels. In bovine and porcine cases, such generic trends were not observed. Mechanical characteristics of 10% gels of gelatin from fish skin, determined from one cycle compression, were significantly lower than other sources of gelatin gels, while bovine and porcine gels did not show any significant differences. In the case of TPA, hardness of bovine gelatin gel was highest at 41 N for 10% gel, followed by porcine (30 N) then fish skin (5 N) gelatin gels. The gels prepared from different sources did not show any generic trends when all other mechanical attributes were considered.

  15. Study of nuclear glasses alteration gel and synthesis of some model gels; Etude du gel d`alteration des verres nucleaires et synthese de gels modeles

    Energy Technology Data Exchange (ETDEWEB)

    Ricol, S

    1995-10-05

    This work deals with the general problem of alteration of the reference nuclear glass R7T7. Attention is paid particularly to the altered layer formed at the glass surface during alteration process. In opposition to previous works, related essentially to glass dissolution kinetics based on chemical analyses of lixiviated elements, this thesis deals with alteration problems through structural studies of the reference glass and derived gel. This approach allows the determination of mechanisms for the gel formation and a better understanding of the behaviour of glasses towards lixiviation. Both approaches appeared complementary. Based on several spectroscopic techniques, this work showed the particular role of cations such as calcium, zirconium and iron. Studies of silica-based synthetic gels showed the synergic effect of formers cation and of one highly coordinated cation. The variation of the wavenumber related to Si-O-Si asymmetric stretching vibration can be correlated to O/Si ratio for ternary systems Si/Na/Zr. On the contrary, the Si losses of the materials depend on the number of non-bridging oxygen atoms. In the perspective of long-term behaviour, the alteration gel presents better characteristics than initial glass. It is therefore a highly stable material in static conditions. In the same way, synthetic gels are materials with very low solubilities (much lower than the alteration gel) and could be used as confining matrices. (authors). refs., 71 figs., 37 tabs.

  16. Actuator device utilizing a conductive polymer gel

    Science.gov (United States)

    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.

  17. Basic investigations on LCV micelle gel

    International Nuclear Information System (INIS)

    Ebenezer, S B; Rafic, M K; Ravindran, P B

    2013-01-01

    The aim of this study was to investigate the feasibility of using Leuco Crystal Violet (LCV) based micelle gel dosimeter as a quality assurance tool in radiotherapy applications. Basic properties such as absorption coefficient and diffusion of LCV gel phantom over time were evaluated. The gel formulation consisted of 25 mM Trichloroacetic acid, 1mM LCV, 4 mM Triton X-100, 4% gelatin by mass and distilled water. The advantages of using this gel are its tissue equivalence, easy and less preparation time, lower diffusion rate and it can be read with an optical scanner. We were able to reproduce some of the results of Babic et al. The peak absorption was found to be at 600 nm and hence a matrix of yellow LEDs was used as light source. The profiles obtained from projection images confirmed the diffusion of LCV gel after 6 hours of irradiation. Hence the LCV gel phantom should be read before 6 hours post irradiation to get accurate dose information as suggested previously.

  18. Gel nano-particulates against radioactivity; Des nanoparticules en gel contre la radioactivite

    Energy Technology Data Exchange (ETDEWEB)

    Deroin, Ph

    2004-11-01

    The Argonne research center (USA) has developed a 'super-gel' compound, a polymer close to those used in baby's diapers, which can reach a 90% efficiency in the radioactive decontamination of porous materials, like bricks or concrete. The contaminated materials are sprayed with a mixture of polymer gel and wetting agent with nano-particulates in suspension. Under the action of the wetting agent, radioactivity migrates from the pores to the gel and is trapped by the nano-particulates. The drying and recycling of the gel allows to reduce the volume of radioactive wastes. Short paper. (J.S.)

  19. Iron Loss Prediction Using Modified IEM-Formula during the Field Weakening for Permanent Magnet Synchronous Machines

    Directory of Open Access Journals (Sweden)

    Pedram Asef

    2017-12-01

    Full Text Available During field weakening operation time (FWOT, the total iron loss rises and affects the accuracy of loss prediction and efficiency, especially if a large range of FWOT exists due to a large voltage drop that was rooted from the resistance of the used material. Iron loss prediction is widely employed in investigations for a fast electrical machine analysis using 2D finite element analysis (FEA. This paper proposes harmonic loss analytically by a steady-state equivalent circuit with a novel procedure. Consideration of skin effects and iron saturation are utilized in order to examine the accuracy through the relative error distribution in the frequency domain of each model from 50 to 700 Hz. Additionally, this comparative study presents a torque-frequency-field density calculation over each single term of the modified institute of electrical machines formula (IEM-Formula. The proposed analytical calculation is performed using 2D FEA for a classic and modified IEM-Formula along with experimental verifications on a surface-mounted permanent magnet synchronous generator (PMSG for a wind generation application.

  20. Research into the usage of integrated jamming of IR weakening and smoke-screen resisting the IR imaging guided missiles

    Science.gov (United States)

    Wang, Long-tao; Jiang, Ning; Lv, Ming-shan

    2015-10-01

    With the emergence of the anti-ship missle with the capability of infrared imaging guidance, the traditional single jamming measures, because of the jamming mechanism and technical flaws or unsuitable use, greatly reduced the survival probability of the war-ship in the future naval battle. Intergrated jamming of IR weakening + smoke-screen Can not only make jamming to the search and tracking of IR imaging guidance system , but also has feasibility in conjunction, besides , which also make the best jamming effect. The research conclusion has important realistic meaning for raising the antimissile ability of surface ships. With the development of guidance technology, infrared guidance system has expanded by ir point-source homing guidance to infrared imaging guidance, Infrared imaging guidance has made breakthrough progress, Infrared imaging guidance system can use two-dimensional infrared image information of the target, achieve the precise tracking. Which has Higher guidance precision, better concealment, stronger anti-interference ability and could Target the key parts. The traditional single infrared smoke screen jamming or infrared decoy flare interference cannot be imposed effective interference. So, Research how to effectively fight against infrared imaging guided weapons threat measures and means, improving the surface ship antimissile ability is an urgent need to solve.

  1. Disrupting the memory of places induced by drugs of abuse weakens motivational withdrawal in a context-dependent manner.

    Science.gov (United States)

    Taubenfeld, Stephen M; Muravieva, Elizaveta V; Garcia-Osta, Ana; Alberini, Cristina M

    2010-07-06

    Addicts repeatedly relapse to drug seeking even after years of abstinence, and this behavior is frequently induced by the recall of memories of the rewarding effects of the drug. Established memories, including those induced by drugs of abuse, can become transiently fragile if reactivated, and during this labile phase, known as reconsolidation, can be persistently disrupted. Here we show that, in rats, a morphine-induced place preference (mCPP) memory is linked to context-dependent withdrawal as disrupting the reconsolidation of the memory leads to a significant reduction of withdrawal evoked in the same context. Moreover, the hippocampus plays a critical role in linking the place preference memory with the context-conditioned withdrawal, as disrupting hippocampal protein synthesis and cAMP-dependent-protein kinase A after the reactivation of mCPP significantly weakens the withdrawal. Hence, targeting memories induced by drugs may represent an important strategy for attenuating context-conditioned withdrawal and therefore subsequent relapse in opiate addicts.

  2. Natural gels in the Yucca Mountain Area, Nevada, USA

    International Nuclear Information System (INIS)

    Levy, S.S.

    1991-01-01

    Relict gels at Yucca Mountain include pore- and fracture-fillings of silica and zeolite related to diagenetic and hydrothermal alternation of vitric tuffs. Water-rich free gels in fractures at Rainier Mesa consist of smectite with or without silica-rich gel fragments. Gels are being studied for their potential role in transport of radionuclides from a nuclear-waste repository

  3. Performance of Magnetic Filter for Separation of Magnetic Gel Particles

    OpenAIRE

    栗延, 俊太郎; 尾崎, 博明; 渡辺, 恒雄; クリノブ, シュンタロウ; オザキ, ヒロアキ; ワタナベ, ツネオ; Shuntaro, KURINOBU; Hiroaki, OZAKI; Tuneo, WATANABE

    2003-01-01

    We have developed a new wastewater treatment process using magnetic gel particles containing immobilized microorganisms and magnetic particles. The performance of magnetic gel particles using a magnetic filter is very important to control the process. In this study, the performance of a magnetic filter was studied for magnetic gel, particles. Agar particles containing magnetite particles were used as gel particles. The recovery and the relative retention area of magnetic gel particles on the ...

  4. Preparation of continuous alumina gel fibres by aqueous sol–gel ...

    Indian Academy of Sciences (India)

    Abstract. Continuous alumina gel fibres were prepared by sol–gel method. The spinning sol was prepared by mixing aluminum nitrate, lactic acid and polyvinylpyrrolidone with a mass ratio of 10:3:1·5. Thermogravimetry– differential scanning calorimetry (TG–DSC), Fourier transform infrared (FTIR) spectra, X-ray diffraction ...

  5. The Effect of Gel Microstructure on Simulated Gastric Digestion of Protein Gels

    NARCIS (Netherlands)

    Opazo-Navarrete, Mauricio; Altenburg, Marte D.; Boom, Remko M.; Janssen, Anja E.M.

    2018-01-01

    The objective of this study was to analyse the impact of the gel structure obtained by different heat-induced temperatures on the in vitro gastric digestibility at pH 2. To achieve this, gels were prepared from soy protein, pea protein, albumin from chicken egg white and whey protein isolate at

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

    Science.gov (United States)

    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.

  7. The key role of ozone depleting substances in weakening the Walker Circulation over the second half of the 20th Century

    Science.gov (United States)

    Bellomo, K.; Polvani, L. M.

    2017-12-01

    It is widely believed that the Walker Circulation will weaken in response to increasing greenhouse gases (GHG) by the end of the 21st century. But over the 20th century, the existence of a statistical significant weakening trends in the observations remains unclear. We here present new modelling evidence showing that Ozone Depleting Substances (ODS) may have significantly contributed to the weakening of the Walker Circulation over the years 1955-2005. While the primary impact of increasing ODS has been the formation of the ozone hole, it is perhaps not as widely appreciated that ODS are also powerful greenhouse gases. Using an ensemble of integrations with the the Whole Atmosphere Chemistry Climate Model, we show that the surface warming caused by increasing ODS over the second half of the 20th century causes a statistically significant weakening of the Walker Circulation in the model. In fact, we find that the increase of the other well-mixed GHG alone leads to a strengthening, not a weakening of the Walker Circulation, over that period in our model. When ODS concentrations are held fixed at 1950's levels, the effect of the other GHG is not sufficient, and a warming delay in the eastern tropical Pacific SST leads to an increase in the east-west SST gradient which is accompanied by a strengthening of the Walker Circulation. But, when the forcing from ODS is added in, the additional radiative forcing causes the eastern Pacific to warm faster, and the trend in the Walker Circulation reverses sign and becomes negative over the second half of the 20th century.

  8. The mechanical behavior and weakening mechanisms of smectite-rich SAFOD gouge at seismic slip-rates

    Science.gov (United States)

    French, M. E.; Kitajima, H.; Chester, J. S.; Chester, F. M.

    2011-12-01

    We present the results of high-speed rotary shear experiments on gouge recovered from the Central Deforming Zone (CDZ) of the San Andreas Fault (SAF) during Phase 3 drilling of the San Andreas Fault Observatory at Depth (SAFOD). The SAFOD borehole transected and recovered samples from two actively creeping segments of the fault. Aseismic creep produced noticeable borehole deformation between 2005 and 2007 in the vicinity of the two m-thick gouge interval that defines the CDZ. The sample tested is a well-foliated smectite - rich gouge that contains clasts of serpentine, quartz, feldspar, and opaques. The sample was gently flaked to ~600 μm to preserve the clay fabric; a ~1 mm thick layer was sheared between gabbro blocks 25 mm in diameter and semi-sealed with a press-fit Teflon ring. Experiments were conducted at a constant normal stress of 0.3 to 1.5 MPa, velocity of 0.1 to 1.3 m/s, and displacement up to 20 m (velocity and displacement refer to the local condition at 2/3 the sample radius). We tested both room-dry and water-saturated gouge at room temperature. Temperatures were measured on a representative suite of samples using 5 thermocouples at various radial positions and distances from the gouge layer. Microstructural analyses were conducted on radial cut thin sections which show slip-perpendicular structures formed under spatial gradients in velocity and displacement. The CDZ gouge weakens with an increase in velocity. The steady-state coefficient of friction of the wet gouge varies from μ = 0.40 at 0.1 m/s to μ = 0.14 at 1.3 m/s. Temperature within the gouge layer exceeds the water-vapor phase transition temperature in the water-saturated gouge sheared at 0.35-1.3 m/s. In general, the coefficient of friction and temperature of the dry gouge is greater than that of the wet gouge. Microstructures show a progression in deformation mechanisms with increasing displacement and velocity. Lens-shaped zones of poorly-foliated starting material are preserved in

  9. Physical and chemical properties of gels. Application to protein nucleation control in the gel acupuncture technique

    Science.gov (United States)

    Moreno, Abel; Juárez-Martínez, Gabriela; Hernández-Pérez, Tomás; Batina, Nikola; Mundo, Manuel; McPherson, Alexander

    1999-09-01

    In this work, we present a new approach using analytical and optical techniques in order to determine the physical and chemical properties of silica gel, as well as the measurement of the pore size in the network of the gel by scanning electron microscopy. The gel acupuncture technique developed by García-Ruiz et al. (Mater. Res. Bull 28 (1993) 541) García-Ruiz and Moreno (Acta Crystallogr. D 50 (1994) 484) was used throughout the history of crystal growth. Several experiments were done in order to evaluate the nucleation control of model proteins (thaumatin I from Thaumatococcus daniellii, lysozyme from hen egg white and catalase from bovine liver) by the porous network of the gel. Finally, it is shown how the number and the size of the crystals obtained inside X-ray capillaries is controlled by the size of the porous structure of the gel.

  10. Viscoplastic fracture transition of a biopolymer gel.

    Science.gov (United States)

    Frieberg, Bradley R; Garatsa, Ray-Shimry; Jones, Ronald L; Bachert, John O; Crawshaw, Benjamin; Liu, X Michael; Chan, Edwin P

    2018-06-13

    Physical gels are swollen polymer networks consisting of transient crosslink junctions associated with hydrogen or ionic bonds. Unlike covalently crosslinked gels, these physical crosslinks are reversible thus enabling these materials to display highly tunable and dynamic mechanical properties. In this work, we study the polymer composition effects on the fracture behavior of a gelatin gel, which is a thermoreversible biopolymer gel consisting of denatured collagen chains bridging physical network junctions formed from triple helices. Below the critical volume fraction for chain entanglement, which we confirm via neutron scattering measurements, we find that the fracture behavior is consistent with a viscoplastic type process characterized by hydrodynamic friction of individual polymer chains through the polymer mesh to show that the enhancement in fracture scales inversely with the squared of the mesh size of the gelatin gel network. Above this critical volume fraction, the fracture process can be described by the Lake-Thomas theory that considers fracture as a chain scission process due to chain entanglements.

  11. DNA DAMAGE QUANTITATION BY ALKALINE GEL ELECTROPHORESIS.

    Energy Technology Data Exchange (ETDEWEB)

    SUTHERLAND,B.M.; BENNETT,P.V.; SUTHERLAND, J.C.

    2004-03-24

    Physical and chemical agents in the environment, those used in clinical applications, or encountered during recreational exposures to sunlight, induce damages in DNA. Understanding the biological impact of these agents requires quantitation of the levels of such damages in laboratory test systems as well as in field or clinical samples. Alkaline gel electrophoresis provides a sensitive (down to {approx} a few lesions/5Mb), rapid method of direct quantitation of a wide variety of DNA damages in nanogram quantities of non-radioactive DNAs from laboratory, field, or clinical specimens, including higher plants and animals. This method stems from velocity sedimentation studies of DNA populations, and from the simple methods of agarose gel electrophoresis. Our laboratories have developed quantitative agarose gel methods, analytical descriptions of DNA migration during electrophoresis on agarose gels (1-6), and electronic imaging for accurate determinations of DNA mass (7-9). Although all these components improve sensitivity and throughput of large numbers of samples (7,8,10), a simple version using only standard molecular biology equipment allows routine analysis of DNA damages at moderate frequencies. We present here a description of the methods, as well as a brief description of the underlying principles, required for a simplified approach to quantitation of DNA damages by alkaline gel electrophoresis.

  12. Sol-gel growth of vanadium dioxide

    International Nuclear Information System (INIS)

    Speck, K.R.

    1990-01-01

    This thesis examines the chemical reactivity of vanadium (IV) tetrakis(t-butoxide) as a precursor for the sol-gel synthesis of vanadium dioxide. Hydrolysis and condensation of the alkoxide was studied by FTIR spectroscopy. Chemical modification of the vanadium tetraalkoxide by alcohol interchange was studied using 51 V NMR and FTIR. Vanadium dioxide thin films and powders were made from vanadium tetrakis(t-butoxide) by standard sol-gel techniques. Post-deposition heating under nitrogen was necessary to transform amorphous gels into vanadium dioxide. Crystallization of films and powders was studied by FTIR, DSC, TGA, and XRD. Gel-derived vanadium dioxide films undergo a reversible semiconductor-to-metal phase transition near 68C, exhibiting characteristic resistive and spectral changes. The electrical resistance decreased by two to three orders of magnitude and the infrared transmission sharply dropped as the material was cycled through this thermally induced phase transition. The sol-gel method was also used to make doped vanadium dioxide films. Films were doped with tungsten and molybdenum ions to effectively lower the temperature at which the transition occurs

  13. Sillica Gel-Amine from Geothermal Sludge

    Science.gov (United States)

    Muljani, S.; Pujiastuti, C.; Wicaksono, P.; Lutfianingrum, R.

    2018-01-01

    Silica Gel-Amine (SGA) has been made from geothermal sludge by grafting amine method. Sodium silicate solution is prepared by extracted geothermal sludge powder using sodium hidroxide solution then acidification in the range of pH 5 - 9 by using tartaric acid 1N. The grafting process uses 1 ml of ammonia solution and 10 ml of toluene at a rate of 0.1 ml min-1 accompanied by a reflux process. The amine grafting is done in two methods. The first method is grafting amine in silicate solution and the second method is grafting amine in washed gel. Product SGA was confirmed by FTIR, TGA-DTG and BET characterization. The results show that the pH affects the amount of amine that is grafted onto silica gel. Differences in grafting method affect the size of the pore and surface area. SGA product prepared by grafting washed gel at pH 8 have pore diameter of 12.06 nm, surface area of 173.44 m2g-1, and mass of decomposed amine compound 0.4 mg. In the presence of amine groups on the silica gel surface, these adsorbents may be able to selectively adsorb CO2 gas from natural gas.

  14. Anti-biofilm activity of chitosan gels formulated with silver nanoparticles and their cytotoxic effect on human fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Pérez-Díaz, M.; Alvarado-Gomez, E. [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi (Mexico); Magaña-Aquino, M. [Servicio de Epidemiologia del Hospital Central “Dr. Ignacio Morones Prieto”, San Luis Potosi (Mexico); Sánchez-Sánchez, R.; Velasquillo, C. [Laboratorio de Biotecnologia, Instituto Nacional de Rehabilitacion, Mexico, D.F. (Mexico); Gonzalez, C. [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi (Mexico); Ganem-Rondero, A. [Division de Estudios de Posgrado (Tecnologia Farmaceutica), Facultad de Estudios Superiores Cuautitlan, Universidad Nacional Autonoma de Mexico, Cuautitlan Izcalli, Estado de Mexico (Mexico); Martínez-Castañon, G.; Zavala-Alonso, N. [Doctorado en Ciencias Odontológicas Facultad de Estomatologia, UASLP (Mexico); Martinez-Gutierrez, F. [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi (Mexico)

    2016-03-01

    The development of multi-species biofilms in chronic wounds is a serious health problem that primarily generates strong resistance mechanisms to antimicrobial therapy. The use of silver nanoparticles (AgNPs) as a broad-spectrum antimicrobial agent has been studied previously. However, their cytotoxic effects limit its use within the medical area. The purpose of this study was to evaluate the anti-biofilm capacity of chitosan gel formulations loaded with AgNPs, using silver sulfadiazine (SSD) as a standard treatment, on strains of clinical isolates, as well as their cytotoxic effect on human primary fibroblasts. Multi-species biofilm of Staphylococcus aureus oxacillin resistant (MRSA) and Pseudomonas aeruginosa obtained from a patient with chronic wound infection were carried out using a standard Drip Flow Reactor (DFR) under conditions that mimic the flow of nutrients in the human skin. Anti-biofilm activity of chitosan gels and SSD showed a log-reduction of 6.0 for MRSA when chitosan gel with AgNPs at a concentration of 100 ppm was used, however it was necessary to increase the concentration of the chitosan gel with AgNPs to 1000 ppm to get a log-reduction of 3.3, while the SSD showed a total reduction of both bacteria in comparison with the negative control. The biocompatibility evaluation on primary fibroblasts showed better results when the chitosan gels with AgNPs were tested even in the high concentration, in contrast with SSD, which killed all the primary fibroblasts. In conclusion, chitosan gel formulations loaded with AgNPs effectively prevent the formation of biofilm and kill bacteria in established biofilm, which suggest that chitosan gels with AgNPs could be used for prevention and treatment of infections in chronic wounds. The statistic significance of the biocompatibility of chitosan gel formulations loaded with AgNPs represents an advance; however further research and development are necessary to translate this technology into therapeutic and

  15. Anti-biofilm activity of chitosan gels formulated with silver nanoparticles and their cytotoxic effect on human fibroblasts

    International Nuclear Information System (INIS)

    Pérez-Díaz, M.; Alvarado-Gomez, E.; Magaña-Aquino, M.; Sánchez-Sánchez, R.; Velasquillo, C.; Gonzalez, C.; Ganem-Rondero, A.; Martínez-Castañon, G.; Zavala-Alonso, N.; Martinez-Gutierrez, F.

    2016-01-01

    The development of multi-species biofilms in chronic wounds is a serious health problem that primarily generates strong resistance mechanisms to antimicrobial therapy. The use of silver nanoparticles (AgNPs) as a broad-spectrum antimicrobial agent has been studied previously. However, their cytotoxic effects limit its use within the medical area. The purpose of this study was to evaluate the anti-biofilm capacity of chitosan gel formulations loaded with AgNPs, using silver sulfadiazine (SSD) as a standard treatment, on strains of clinical isolates, as well as their cytotoxic effect on human primary fibroblasts. Multi-species biofilm of Staphylococcus aureus oxacillin resistant (MRSA) and Pseudomonas aeruginosa obtained from a patient with chronic wound infection were carried out using a standard Drip Flow Reactor (DFR) under conditions that mimic the flow of nutrients in the human skin. Anti-biofilm activity of chitosan gels and SSD showed a log-reduction of 6.0 for MRSA when chitosan gel with AgNPs at a concentration of 100 ppm was used, however it was necessary to increase the concentration of the chitosan gel with AgNPs to 1000 ppm to get a log-reduction of 3.3, while the SSD showed a total reduction of both bacteria in comparison with the negative control. The biocompatibility evaluation on primary fibroblasts showed better results when the chitosan gels with AgNPs were tested even in the high concentration, in contrast with SSD, which killed all the primary fibroblasts. In conclusion, chitosan gel formulations loaded with AgNPs effectively prevent the formation of biofilm and kill bacteria in established biofilm, which suggest that chitosan gels with AgNPs could be used for prevention and treatment of infections in chronic wounds. The statistic significance of the biocompatibility of chitosan gel formulations loaded with AgNPs represents an advance; however further research and development are necessary to translate this technology into therapeutic and

  16. Sol-gel synthesis of hydroxyapatite

    International Nuclear Information System (INIS)

    Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P.

    2010-01-01

    Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)

  17. Superconductive ceramics obtained with sol gel method

    International Nuclear Information System (INIS)

    Arcangeli, A.; Mosci, A.; Nardi, A.; Vatteroni, R.; Zondini, C.

    1988-01-01

    Several sol gel routes have been considered, studied and developed to produce large quantities of granulates which can be processed to obtain ceramics having good superconducting characteristics. In the considered process a mixture of commercial nitrates is atomized, at room temperature, in a solution 1:1 of Primene JMT and Benzene and a pale blue gel of the starting elements is suddently formed. The granulates obtained are free flowing, very reactive and well suited for pressing. For their intrinsic characteristics they could be very good precursors for the production of large quantities of superconductive ceramics in different forms. The precipitated gel is dried, calcinated, pressed in the form of cylindrical pellets which are sintered up to 960 degrees C. No griding or different thermal treatments are needed. The sintered material has low electric resistence, shows a clear Meissner effect and has a transition temperature of between 91 and 95 K

  18. Ageing of uranyl gel spherical particles

    International Nuclear Information System (INIS)

    Benadik, A.; Urbanek, V.; Vosecek, V.; Skvor, V.

    1978-01-01

    The structure and chemical composition of U(VI) gel are described and the course of crystal growth in ageing process at 22+-2 degC was found. Store conditions of probes had no influence on crystal growth rate. However, the way of probe storage influenced the quality and appearance of the xerogel obtained by drying via azeotropic distillation. The gel particles stored under trichloroethylene had a good appearance also after storing for 44 hours long. Particles stored in air saturated with H 2 O and NH 3 showed a worse appearance already after 20 hours. After 70 hours particles of spiny form were found. The worst particles were those stored under a trichloroethylene-ethylalcohol mixture. For storing purposes trichloroethylene was recommended as the most appropriate medium of gel protection. (author)

  19. Pouring and running a protein gel by reusing commercial cassettes.

    Science.gov (United States)

    Hwang, Alexander C; Grey, Paris H; Cuddy, Katrina; Oppenheimer, David G

    2012-02-12

    The evaluation of proteins using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis is a common technique used by biochemistry and molecular biology researchers. For laboratories that perform daily analyses of proteins, the cost of commercially available polyacrylamide gels (~$10/gel) can be considerable over time. To mitigate this cost, some researchers prepare their own polyacrylamide gels. Traditional methods of pouring these gels typically utilize specialized equipment and glass gel plates that can be expensive and preclude pouring many gels and storing them for future use. Furthermore, handling of glass plates during cleaning or gel pouring can result in accidental breakage creating a safety hazard, which may preclude their use in undergraduate laboratory classes. Our protocol demonstrates how to pour multiple protein gels simultaneously by recycling Invitrogen Nupage Novex minigel cassettes, and inexpensive materials purchased at a home improvement store. This economical and streamlined method includes a way to store the gels at 4°C for a few weeks. By re-using the plastic gel cassettes from commercially available gels, labs that run frequent protein gels can save significant costs and help the environment. In addition, plastic gel cassettes are extremely resistant to breakage, which makes them ideal for undergraduate laboratory classrooms.

  20. Multifunctional nano-hydroxyapatite and alginate/gelatin based sticky gel composites for potential bone regeneration

    International Nuclear Information System (INIS)

    Cai, Yurong; Yu, Juhong; Kundu, Subhas C.; Yao, Juming

    2016-01-01

    To improve the fixations of the implant and implant-bone integration after joint arthroplasty from locally preventing inflammation and promoting the bone regeneration, we design a multifunctional biomaterial consisting of recombinant human bone morphogenetic protein 2 (rhBMP-2) and antibiotic loaded nano-hydroxyapatite with an alginate/gelatin sticky gel. We investigate its role for the prevention of the inflammation and possibility of inducing a new bone growth along with its adhesive ability. The stickiness exists in the composite, which may help to fix itself on the bone fracture surface. The composite sustains the antibacterial effect and promotes the proliferation and differentiation of MG63 cells in vitro. In vivo experimentation also shows that the composite gel has a role for the reduction of inflammation. It enhances the formation of new bone and blood vessels compared to both the sole rhBMP-2 and non-rhBMP-2/antibiotic loaded composite gels. The multifunctional composite provides a promising material for the prosthetic and bone tissue regeneration. - Highlights: • Multifunctional nanohydroxyapatite composite is fabricated. • The composite consists of nHAP, growth factor, antibiotic and alginate/gelatin gel. • The composite shows antibacterial effect and good cytocompatibility. • No adverse effect to the cells tested in vitro and in vivo.

  1. Multifunctional nano-hydroxyapatite and alginate/gelatin based sticky gel composites for potential bone regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Yurong; Yu, Juhong [The Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, National Engineering Lab of Textile Fiber Materials & Processing Technology, College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Kundu, Subhas C. [Department of Biotechnology, Indian Institute of Technology (IIT) Kharagpur, West Bengal 721302 (India); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330-714 (Korea, Republic of); Yao, Juming, E-mail: yaoj@zstu.edu.cn [The Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, National Engineering Lab of Textile Fiber Materials & Processing Technology, College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2016-09-15

    To improve the fixations of the implant and implant-bone integration after joint arthroplasty from locally preventing inflammation and promoting the bone regeneration, we design a multifunctional biomaterial consisting of recombinant human bone morphogenetic protein 2 (rhBMP-2) and antibiotic loaded nano-hydroxyapatite with an alginate/gelatin sticky gel. We investigate its role for the prevention of the inflammation and possibility of inducing a new bone growth along with its adhesive ability. The stickiness exists in the composite, which may help to fix itself on the bone fracture surface. The composite sustains the antibacterial effect and promotes the proliferation and differentiation of MG63 cells in vitro. In vivo experimentation also shows that the composite gel has a role for the reduction of inflammation. It enhances the formation of new bone and blood vessels compared to both the sole rhBMP-2 and non-rhBMP-2/antibiotic loaded composite gels. The multifunctional composite provides a promising material for the prosthetic and bone tissue regeneration. - Highlights: • Multifunctional nanohydroxyapatite composite is fabricated. • The composite consists of nHAP, growth factor, antibiotic and alginate/gelatin gel. • The composite shows antibacterial effect and good cytocompatibility. • No adverse effect to the cells tested in vitro and in vivo.

  2. Electroactive polymer gels based on epoxy resin

    Science.gov (United States)

    Samui, A. B.; Jayakumar, S.; Jayalakshmi, C. G.; Pandey, K.; Sivaraman, P.

    2007-04-01

    Five types of epoxy gels have been synthesized from common epoxy resins and hardeners. Fumed silica and nanoclay, respectively, were used as fillers and butyl methacrylate/acrylamide were used as monomer(s) for making interpenetrating polymer networks (IPNs) in three compositions. Swelling study, tensile property evaluation, dynamic mechanical thermal analysis, thermo-gravimetric analysis, scanning electron microscopy and electroactive property evaluation were done. The gels have sufficient mechanical strength and the time taken for bending to 20° was found to be 22 min for forward bias whereas it was just 12 min for reverse bias.

  3. Recent developments in polymer gel dosimetry

    International Nuclear Information System (INIS)

    John Schreiner, L.; Olding, Tim; Holmes, Oliver; McAuley, Kim

    2008-01-01

    Modern radiation therapy particularly with intensity modulation techniques (IMRT) offers the potential to improve patient outcomes by better limiting high doses to the tumour alone. In this presentation we report our progress in developing gel dosimetry with new less toxic dosimeters using a fast commercial optical computed tomography (OCT) scanner. We will demonstrate that these adjustments in the approach to gel dosimetry help facilitate its introduction into clinical use. We will review practical advances in system quality assurance and scatter correction to improve optical CT quantification, and show an example of a clinical implementation of an IGRT treatment validation

  4. Neutron detector using sol-gel absorber

    Science.gov (United States)

    Hiller, John M.; Wallace, Steven A.; Dai, Sheng

    1999-01-01

    An neutron detector composed of fissionable material having ions of lithium, uranium, thorium, plutonium, or neptunium, contained within a glass film fabricated using a sol-gel method combined with a particle detector is disclosed. When the glass film is bombarded with neutrons, the fissionable material emits fission particles and electrons. Prompt emitting activated elements yielding a high energy electron contained within a sol-gel glass film in combination with a particle detector is also disclosed. The emissions resulting from neutron bombardment can then be detected using standard UV and particle detection methods well known in the art, such as microchannel plates, channeltrons, and silicon avalanche photodiodes.

  5. Hybrid sol-gel optical materials

    Science.gov (United States)

    Zeigler, John M.

    1992-01-01

    Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

  6. Ordering phenomena in ABA triblock copolymer gels

    DEFF Research Database (Denmark)

    Reynders, K.; Mischenko, N.; Kleppinger, R.

    1997-01-01

    Temperature and concentration dependencies of the degree of order in ABA triblock copolymer gels are discussed. Two factors can influence the ordering phenomena: the conformation of the midblocks (links of the network) and the polydispersity of the endblock domains (nodes of the network). The lat......Temperature and concentration dependencies of the degree of order in ABA triblock copolymer gels are discussed. Two factors can influence the ordering phenomena: the conformation of the midblocks (links of the network) and the polydispersity of the endblock domains (nodes of the network...

  7. Processing of radioactive ruthenium with aluminosilicate gels

    International Nuclear Information System (INIS)

    Kanno, Takuji; Ichinose, Yasuhiro; Ito, Katsuo

    1979-01-01

    Coprecipitation of radioactive Ru with hydroxides has been studied for the purpose of the management of the high level waste from the nuclear fuel reprocessing. Aluminosilicate gel used as coprecipitant was prepared by addition of aqueous sodium hydroxide to sodium aluminate-sodium silicate solution containing ruthenium nitrate. Ruthenium quantitatively precipitates under the conditions, aluminate > 4 x 10 -2 M, Al/Si 0 C. However, volatilization rate of Ru is suppressed by coating with mullite phase into which aluminosilicate gel transformes above 900 0 C. The amount of Ru volatilized in Ar-flow was reduced to about 10% of that in air-flow. (author)

  8. The weakening of cell protection as a result of the Chernobyl NPP accident recovery factors affect on liquidator's organism

    International Nuclear Information System (INIS)

    Zybina, N.; Dryguina, L.; Katashkova, G.

    1997-01-01

    The markers of oxidative stress as well as intracellular antioxidants (enzymatic and non- enzymatic) were studied in 100 Chernobyl accident recovery workers(liquidators). Hormone screening tests were carried out in 250 liquidators. All persons (mean age - 35 years) have got external irradiation dose from 2 to 30 cGr. Control group was selected from persons of same age having not participated in accident liquidation. The significant antioxidant imbalance was found. ROS inactivating enzymes deficiency was revealed in neutrofils, lymphocytes and alveolar macrophages (AM). For instance, superoxide dismutase(SOD) activity in liquidator's AM was 2,8±0,3 U/mg protein (4,1-±1,8 U/mg protein in controls, P<0,05). Catalase activity was also lower than in control group (P<0,05). The significant disorder of the thiol-disulfide turnover was revealed: depression of reduced glutathione by 1,71-±0,46 μmol/l (control: 3,15±-0,34 μtmol/l, P<0,05). The oxidative stress destructive action realized in the conditions of excessive production of ROS, while the antioxidant potential was diminished(P<0,05). The oxidative destruction of lipids and proteins was found to be induced by free radical action. TBARS level in alveolar macrophages of liquidators was more than three times higher compared to controls. Enhanced levels of protein carbonyl groups were found as well. The decrease of TT3 in liquidators was detected most frequently. In 19% liquidators examined, TT3 was below the reference value (0,8 ng/ml). The TT3 level was registered at the low limit of the reference range (0,8 ng/ml) in 18% of liquidators. ''Low T3'' syndrome may be considered as a cell protection weakening. All the cellular protective mechanisms take part in processes of DNA synthesis and repair, transcription and translation, cell respiration and metabolism. Significant impairment of the cellular protective systems in liquidators could be regarded as a base of persistent ''chromosomal pathology'' and imbalance of

  9. Discovery of amorphous carbon veins in the 2008 Wenchuan earthquake fault zone: implications for the fault weakening mechanism

    Science.gov (United States)

    Liu, J.; Zhang, J.; Zhang, B.; Li, H.

    2013-12-01

    The 2008 Wenchuan earthquake generated 270- and 80-km-long surface ruptures along Yingxiu-Beichuan fault and Guanxian-Anxian fault, respectively. At the outcrop near Hongkou village, southwest segment of Yingxiu-Beichuan rupture, network black amorphous carbon veins were discovered near fault planes in the 190-m-wide earthquake fault zone. These veins are mainly composed of ultrafine- and fine-grained amorphous carbon, usually narrower than 5mm and injected into faults and cracks as far as several meter. Flowage structures like asymmetrical structures around few stiff rock fragments indicate materials flew when the veins formed. Fluidization of cataclastic amorphous carbon and the powerful driving force in the veins imply high pore pressure built up during earthquakes. High pore pressure solution and graphite reported in the fault gouge (Togo et al., 2011) can lead very low dynamic friction during the Wenchuan earthquake. This deduction hypothesis is in accordance with the very low thermal abnormal measured on the principle fault zone following the Wenchuan earthquake (Mori et al., 2010). Furthermore, network amorphous carbon veins of different generations suggest similar weakening mechanism also worked on historical earthquakes in Longmenshan fault zone. Reference: Brodsky, E. E., Li, H., Mori, J. J., Kano, Y., and Xue, L., 2012, Frictional Stress Measured Through Temperature Profiles in the Wenchuan Scientific Fault Zone Drilling Project. American Geophysical Union, Fall Meeting. San Francisco, T44B-07 Li, H., Xu, Z., Si, J., Pei, J., Song, S., Sun, Z., and Chevalier, M., 2012, Wenchuan Earthquake Fault Scientific Drilling program (WFSD): Overview and Results. American Geophysical Union, Fall Meeting. San Francisco, T44B-01 Mori, J. J., Li, H., Wang, H., Kano, Y., Pei, J., Xu, Z., and Brodsky, E. E., 2010, Temperature measurements in the WFSD-1 borehole following the 2008 Wenchuan earthquake (MW7.9). American Geophysical Union, Fall Meeting. San Francisco, T53E

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

    Directory of Open Access Journals (Sweden)

    Mohan Daburkar

    2014-01-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  12. Protein electrophoretic migration data from custom and commercial gradient gels

    Directory of Open Access Journals (Sweden)

    Andrew J. Miller

    2016-12-01

    Full Text Available This paper presents data related to the article “A method for easily customizable gradient gel electrophoresis” (A.J. Miller, B. Roman, E.M. Norstrom, 2016 [1]. Data is presented on the rate of electrophoretic migration of proteins in both hand-poured and commercially acquired acrylamide gradient gels. For each gel, migration of 9 polypeptides of various masses was measured upon completion of gel electrophoresis. Data are presented on the migration of proteins within separate lanes of the same gel as well as migration rates from multiple gels.

  13. The mechanism and properties of acid-coagulated milk gels

    Directory of Open Access Journals (Sweden)

    Chanokphat Phadungath

    2005-03-01

    Full Text Available Acid-coagulated milk products such as fresh acid-coagulated cheese varieties and yogurt areimportant dairy food products. However, little is known regarding the mechanisms involved in gel formation, physical properties of acid gels, and the effects of processing variables such as heat treatment and gelation temperature on the important physical properties of acid milk gels. This paper reviews the modern concepts of possible mechanisms involved in the formation of particle milk gel aggregation, along with recent developments including the use of techniques such as dynamic low amplitude oscillatory rheology to observe the gel formation process, and confocal laser scanning microscopy to monitor gel microstructure.

  14. Sol-gel additive for systems with inorganic binders

    International Nuclear Information System (INIS)

    Akstinat, M.; Antenen, D.; Suter, W.

    1996-01-01

    A sol-gel additive for inorganic binder systems and sol-gel process for producing air-placed concrete and mortar by using such sol-gel additives are disclosed. Sol-gel additives for gel-derived inorganic binder systems (for example plaster, cement, lime, special slags, etc.) marked improve the consistency of such binder systems during processing or allow their consistency to be regulated. In addition, these sol-gel additives regulate setting times and substantially improve durability (chemical resistance, reduced permeability) and the mechanical properties of the set binder system. (author)

  15. Multiple-phase behavior and memory effect of polymer gel

    CERN Document Server

    Annaka, M; Nakahira, T; Sugiyama, M; Hara, K; Matsuura, T

    2002-01-01

    A poly(4-acrylamidosalicylic acid) gel (PASA gel) exhibits multiple phases as characterized by distinct degrees of swelling; the gel can take one of four different swelling values, but none of the intermediate values. The gel has remarkable memory: the phase behavior of the gel depends on whether the gel has experienced the most swollen phase or the most collapsed phase in the immediate past. The information is stored and reversibly erased in the form of a macroscopic phase transition behavior. The structure factors corresponding to these four phases were obtained by SANS, which indicated the presence of characteristic structures depending on pH and temperature, particularly in the shrunken state. (orig.)

  16. Initial investigation of a novel light-scattering gel phantom for evaluation of optical CT scanners for radiotherapy gel dosimetry

    International Nuclear Information System (INIS)

    Bosi, Stephen; Naseri, Pourandokht; Puran, Alicia; Davies, Justin; Baldock, Clive

    2007-01-01

    There is a need for stable gel materials for phantoms used to validate optical computerized tomography (CT) scanners used in conjunction with radiation-induced polymerizing gel dosimeters. Phantoms based on addition of light-absorbing dyes to gelatine to simulate gel dosimeters have been employed. However, to more accurately simulate polymerizing gels one requires phantoms that employ light-scattering colloidal suspensions added to the gel. In this paper, we present the initial results of using an optical CT scanner to evaluate a novel phantom in which radiation-exposed polymer gels are simulated by the addition of colloidal suspensions of varying turbidity. The phantom may be useful as a calibration transfer standard for polymer gel dosimeters. The tests reveal some phenomena peculiar to light-scattering gels that need to be taken into account when calibrating polymer gel dosimeters

  17. SAXS study of silica sols, gels and glasses obtained by the sol gel process

    International Nuclear Information System (INIS)

    Santos, D.I. dos; Aegerter, M.A.

    1988-01-01

    Systematic SAXS studies have been performed at the LURE Synchrotron, Orsay, using an intense beam of point like cross-section to obtain information about the sol -> humid gel -> dried gel -> silica glass transformation. The intensity curves have been analysed in term of power law in log-log plots, whose exponent is related to mass and surface fractal dimensions of the structure. It was found that almost all phases present fractal structures and for the case of basic gels, is of hierarchical nature. The aerogels are formed by a dense matrix, with a smooth surface and exhibit a very narrow auto-similarity range that gives a mass fractal dimension. (author) [pt

  18. Facile synthesis of Ca-doped manganite nanoparticles by a nonaqueous sol-gel method and their magnetic properties

    International Nuclear Information System (INIS)

    Zhou, S.M.; Zhao, S.Y.; He, L.F.; Guo, Y.Q.; Shi, L.

    2010-01-01

    Perovskite manganite La 1-x Ca x MnO 3 (x=1/3, 1/2 and 2/3) nanoparticles with the average particle size of about 20 nm have been synthesized by a facile nonaqueous sol-gel method using methanol as a solvent and characterized by X-ray diffraction, transmission electron microscopy and superconducting quantum interference device magnetometer. Magnetic measurements reveal that although their bulk counterparts have quite different magnetic ground states, the three-nanosized samples exhibit similar ferromagnetic behaviors below about 270 K. This result implies that with the particle size reduced to nanoscale, the ferromagnetism for x=1/3 is weaken, while it is enhanced, accompanied by the suppression of the charge ordering, for x=1/2 and 2/3. Moreover, the exchange bias phenomena are observed in the two latter nanoparticles, which is of special interest for potential applications.

  19. Screening of mucoadhesive vaginal gel formulations

    Directory of Open Access Journals (Sweden)

    Ana Ochoa Andrade

    2014-12-01

    Full Text Available Rational design of vaginal drug delivery formulations requires special attention to vehicle properties that optimize vaginal coating and retention. The aim of the present work was to perform a screening of mucoadhesive vaginal gels formulated with carbomer or carrageenan in binary combination with a second polymer (carbomer, guar or xanthan gum. The gels were characterised using in vitroadhesion, spreadability and leakage potential studies, as well as rheological measurements (stress and frequency sweep tests and the effect of dilution with simulated vaginal fluid (SVF on spreadability. Results were analysed using analysis of variance and multiple factor analysis. The combination of polymers enhanced adhesion of both primary gelling agents, carbomer and carrageenan. From the rheological point of view all formulations presented a similar behaviour, prevalently elastic and characterised by loss tangent values well below 1. No correlation between rheological and adhesion behaviour was found. Carbomer and carrageenan gels containing the highest percentage of xanthan gum displayed good in vitro mucoadhesion and spreadability, minimal leakage potential and high resistance to dilution. The positive results obtained with carrageenan-xanthan gum-based gels can encourage the use of natural biocompatible adjuvants in the composition of vaginal products, a formulation field that is currently under the synthetic domain.

  20. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS ...

    African Journals Online (AJOL)

    Four strains of eri, Samia cynthia ricini Lepidoptera: Saturniidae that can be identified morphologically and maintained at North East Institute of Science and Technology, Jorhat were characterized based on their protein profile by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and DNA by random ...

  1. Polyacrylamide gel polymerization with adjustable gelation rate

    Czech Academy of Sciences Publication Activity Database

    Wiesner, Ivo; Wiesnerová, Dana

    2002-01-01

    Roč. 32, - (2002), s. 740-742 ISSN 0736-6205 R&D Projects: GA AV ČR KSK5052113; GA ČR GA521/00/0075 Keywords : polyacrylamide gel Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.173, year: 2002

  2. Structuring of gels of zirconium oxohydrate

    International Nuclear Information System (INIS)

    Sukharev, Yu.I.; Skuratovich, L.P.

    1991-01-01

    Genetic relationship between formation of mesophase states of zirconium oxohydrate gel, coprecipitated with dimethylamine, and ordered macrocrystallites of sorption material after cryogranulation or decryptation granulating is shown. This phenomenon is followed on example of formation of flattened crystallites when preparing granules in the presence of appl. The successive polymerization growth of crystallites leads to the frame ordered aggregation or aggregation of another type

  3. Calcium Impact on Milk Gels Formation

    DEFF Research Database (Denmark)

    Koutina, Glykeria

    of temperature and pH may result in different final structure properties in dairy products such as cheese. A significant amount of calcium remained in the micelles between pH 4.8 and 4.6, this can contribute to the final strength of acid milk gels, such as in yogurt or in cream cheeses. After the gelation point...

  4. Drying and Rehydration of Calcium Alginate Gels

    NARCIS (Netherlands)

    Vreeker, R.; Li, L.; Fang, Y.; Appelqvist, I.; Mendes, E.

    2008-01-01

    In this paper, we study the rehydration properties of air-dried calcium alginate gel beads. Rehydration is shown to depend on alginate source (i.e. mannuronic to guluronic acid ratio) and the salt concentration in the rehydration medium. Rehydration curves are described adequately by the empirical

  5. Simple Cloud Chambers Using Gel Ice Packs

    Science.gov (United States)

    Kamata, Masahiro; Kubota, Miki

    2012-01-01

    Although cloud chambers are highly regarded as teaching aids for radiation education, school teachers have difficulty in using cloud chambers because they have to prepare dry ice or liquid nitrogen before the experiment. We developed a very simple and inexpensive cloud chamber that uses the contents of gel ice packs which can substitute for dry…

  6. Matching Two-dimensional Gel Electrophoresis' Spots

    DEFF Research Database (Denmark)

    Dos Anjos, António; AL-Tam, Faroq; Shahbazkia, Hamid Reza

    2012-01-01

    This paper describes an approach for matching Two-Dimensional Electrophoresis (2-DE) gels' spots, involving the use of image registration. The number of false positive matches produced by the proposed approach is small, when compared to academic and commercial state-of-the-art approaches. This ar...

  7. Sol-Gel Synthesis Of Aluminoborosilicate Powders

    Science.gov (United States)

    Bull, Jeffrey; Leiser, Daniel; Selvaduray, Guna

    1992-01-01

    Application of sol-gel process to synthesis of aluminoborosilicate powders shows potential for control of microstructures of materials. Development of materials having enhanced processing characteristics prove advantageous in extending high-temperature endurance of fibrous refractory composite insulation made from ceramic fibers.

  8. Sol-Gel Derived Hafnia Coatings

    Science.gov (United States)

    Feldman, Jay D.; Stackpoole, Mairead; Blum, Yigal; Sacks, Michael; Ellerby, Don; Johnson, Sylvia M.; Venkatapathy, Ethiras (Technical Monitor)

    2002-01-01

    Sol-gel derived hafnia coatings are being developed to provide an oxidation protection layer on ultra-high temperature ceramics for potential use in turbine engines (ultra-efficient engine technology being developed by NASA). Coatings using hafnia sol hafnia filler particles will be discussed along with sol synthesis and characterization.

  9. Electrophoretic Porosimetry of Sol-Gels

    Science.gov (United States)

    Snow, L. A.; Smith, D. D.; Sibille, L.; Hunt, A. J.; Ng, J.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    It has been hypothesized that gravity has an effect on the formation and resulting microstructure of sol-gels. In order to more clearly resolve the effect of gravity, pores may be non-destructively analyzed in the wet gel, circumventing the shrinkage and coarsening associated with the drying procedure. We discuss the development of an electrophoretic technique, analogous to affinity chromatography, for the determination of pore size distribution and its application to silica gels. Specifically a monodisperse charged dye is monitored by an optical densitometer as it moves through the wet gel under the influence of an electric field. The transmittance data (output) represents the convolution of the dye concentration profile at the beginning of the run (input) with the pore size distribution (transfer function), i.e. linear systems theory applies. Because of the practical difficulty in producing a delta function input dye profile we prefer instead to use a step function. Average pore size is then related to the velocity of this dye front, while the pore size distribution is related to the spreading of the front. Preliminary results of this electrophoretic porosimetry and its application to ground and space-grown samples will be discussed.

  10. Effectiveness of Gel Repellents on Feral Pigeons

    Directory of Open Access Journals (Sweden)

    Birte Stock

    2013-12-01

    Full Text Available Millions of feral pigeons (Columba livia live in close association with the human population in our cities. They pose serious health risks to humans and lead to high economic loss due to damage caused to buildings. Consequently, house owners and city authorities are not willing to allow pigeons on their buildings. While various avian repellents are regularly introduced onto the market, scientific proof of efficacy is lacking. This study aimed at testing the effectiveness of two avian gel repellents and additionally examined their application from animal welfare standpoint. The gels used an alleged tactile or visual aversion of the birds, reinforced by additional sensory cues. We mounted experimental shelves with the installed repellents in a pigeon loft and observed the behavior of free-living feral pigeons towards the systems. Both gels showed a restricted, transient repellent effect, but failed to prove the claimed complete effectiveness. Additionally, the gels’ adhesive effect remains doubtful in view of animal welfare because gluing of plumage presents a risk to feral pigeons and also to other non-target birds. This study infers that both gels lack the promised complete efficacy, conflict with animal welfare concerns and are therefore not suitable for feral pigeon management in urban areas.

  11. Silica gel matrix immobilized Chlorophyta hydrodictyon africanum ...

    African Journals Online (AJOL)

    Aghomotsegin

    2015-08-05

    Aug 5, 2015 ... The algae-silica gel adsorbent was used for batch sorption studies of a cationic dye, ... traditional methods of treating industrial effluent, these ... Author(s) agree that this article remains permanently open access under the terms of the Creative ... sodium silicate solution (v/v) and 25 mL of distilled water. With.

  12. Force percolation of contractile active gels

    NARCIS (Netherlands)

    Alvarado, José; Sheinman, Michael; Sharma, Abhinav; MacKintosh, Fred C.; Koenderink, Gijsje H.

    2017-01-01

    Living systems provide a paradigmatic example of active soft matter. Cells and tissues comprise viscoelastic materials that exert forces and can actively change shape. This strikingly autonomous behavior is powered by the cytoskeleton, an active gel of semiflexible filaments, crosslinks, and

  13. Process for encapsulating active agents in gels

    NARCIS (Netherlands)

    Yilmaz, G.; Jongboom, R.O.J.; Oosterhaven, J.

    2001-01-01

    The present invention relates to a process for encapsulating an active agent in a biopolymer in the form of a gel, comprising the steps of: a) forming a dispersion or solution of the biopolymer in water; and b) adding the active agent to the dispersion or solution obtained in step a); wherein the

  14. Investigation on safety of gel decontamination technology

    International Nuclear Information System (INIS)

    Liu Zhihui; Song Fengli; Wang Yongxian; Zhang Taoge

    2014-01-01

    Gel decontamination technology is an advanced decontamination process of metal contaminated by radionuclide. It has the advantages such as simple operation process, high decontaminating factor, etc. But the disadvantages are that it has high spraying pressure and is strongly corrosive, which has safety risk to the operator and equipment. The effect of such factors as spraying pressure on operators was analyzed based on process feature, and it is proposed that it be worthwhile to make further study on the corrosion of gels to spraying equipment, taking into account corrosion feature of gels to stainless steel. Meanwhile, the safety issue was demonstrated on collecting and handling wastes from gel decontamination process. And then, protective measures, study methods, and solutions are put forward. The results show that protection should be strengthened during spraying to reduce the effect of splashing and fogging on workers; the equipment should be cleaned in time to reduce the effect of corrosion, and reducers should be added into waste liquid to eliminate the effect of residual detergent. (authors)

  15. Fluorescence metrology of silica sol-gels

    Indian Academy of Sciences (India)

    We have developed a new method for measuring in-situ the growth of the nanometre-size silica particles which lead to the formation of sol-gel glasses. This technique is based on the decay of fluorescence polarisation anisotropy due to Brownian rotation of dye molecules bound to the particles. Results to date give near ...

  16. Experimental investigation of the degree of weakening in structural notch area of 7075-T6 aluminum alloy sheet welded with the RFSSW method

    Directory of Open Access Journals (Sweden)

    Kubit Andrzej

    2017-01-01

    Full Text Available The paper presents the methodology of the research determining the degree of weakening of the welded sheet obtained by the refill friction stir spot welding (RFSSW method. The considered weakness is the effect of a structural notch resulting from penetration by the tool. RFSSW technology is a relatively new method of joining metals, which can successfully provide an alternative to resistance welding or riveting - traditionally used methods of joining thin-walled structures in the aerospace and automotive industries. The study presented in the paper focuses on the overlapping of sheet metal with 7075-T6 aluminum alloy combined in the configuration: 1.6 mm top sheet and 0.8 mm bottom sheet. Joints were assembled following the following process parameters: Welding time 1.5 s, the tool plunge depth in the range of 1.5 ÷ 1.9 mm, and the spindle speed of 2600 rpm. The analysis of the microstructure of joints revealed that along the edge of the tool path a structural notch is formed, the size and shape of which depend on the parameters applied. The paper describes the study consisting in punching the welded area along the formed notch in the upper sheet. The punching process was performed on a universal testing machine and the punching force was measured during the test. Based on the force value, the degree of sheet weakening in the notched area was determined. The smallest weakening was observed in joints made with the smallest tool depth, i.e. 1.5 mm, whereas the biggest weakening was obtained for tool depth of 1.9 mm. The load applied to the joints was equal to 5290N and 7585N respectively.

  17. {beta}-decay studies at the N=28 shell closure: indications for a weakening of the spin-orbit force far from stability?

    Energy Technology Data Exchange (ETDEWEB)

    Grevy, S. [Laboratoire de Physique Corpusculaire de Caen, IN2P3-CNRS, ENSICAEN et Universite de Caen, F-14050 Caen Cedex (France)]. E-mail: grevy@in2p3.fr; Angelique, J.C.; Baumann, P.; Borcea, C.; Buta, A.; Canchel, G.; Catford, W.N.; Courtin, S.; Daugas, J.M.; Oliveira, F. de; Dessagne, P.; Dlouhy, Z.; Knipper, A.; Kratz, K.L.; Lecolley, F.R.; Lecouey, J.L.; Lehrsenneau, G.; Lewitowicz, M.; Lienard, E.; Lukyanov, S.; Marechal, F.; Miehe, C.; Mrazek, J.; Negoita, F.; Orr, N.A.; Pantelica, D.; Penionzhkevich, Y.; Peter, J.; Pfeiffer, B.; Pietri, S.; Poirier, E.; Sorlin, O.; Stanoiu, M.; Stefan, I.; Stodel, C.; Timis, C

    2004-12-27

    A {beta}-decay experiment on nuclei in the region of N=28 has been performed at the GANIL facility. New measured half-lives for the Si isotopes from N=25 to N=28 are reported and discussed in the light of the deformation occurring in this region. Comparison with QRPA calculations suggests that a weakening of the spin-orbit force occurs for the very neutron-rich Si isotopes.

  18. Phase III double-blind evaluation of an aloe vera gel as a prophylactic agent for radiation-induced skin toxicity

    International Nuclear Information System (INIS)

    Williams, Maureen S.; Burk, Mary; Loprinzi, Charles L.; Hill, Mary; Schomberg, Paula J.; Nearhood, Kim; O'Fallon, Judith R.; Laurie, John A.; Shanahan, Thomas G.; Moore, Randy L.; Urias, Rodolfo E.; Kuske, Robert R.; Engel, Roland E.; Eggleston, William D.

    1996-01-01

    Purpose: Considerable pilot data and clinical experience suggested that an aloe vera gel might help to prevent radiation therapy-induced dermatitis. Methods and Materials: Two Phase III randomized trials were conducted. The first one was double blinded, utilized a placebo gel, and involved 194 women receiving breast or chest wall irradiation. The second trial randomized 108 such patients to aloe vera gel vs. no treatment. Skin dermatitis was scored weekly during both trials both by patients and by health care providers. Results: Skin dermatitis scores were virtually identical on both treatment arms during both of the trials. The only toxicity from the gel was rare contact dermatitis. Conclusions: This dose and schedule of an aloe vera gel does not protect against radiation therapy-induced dermatitis

  19. The effect of theobromine 200 mg/l topical gel exposure duration against surface enamel hardness resistance from 1% citric acid

    Science.gov (United States)

    Herisa, H. M.; Noerdin, A.; Eriwati, Y. K.

    2017-08-01

    Theobromine can be used to prevent the demineralization of enamel and can stimulate the growth of new enamels. This study analyzes the effect of theobromine’s gel duration exposure on enamel hardness resistance from 1% citric acid. Twenty-eight specimens were divided into three experimental groups; were exposed to theobromine gel 200 mg/l for 16, 48, and 96 minutes; and were then immersed in 1% citric acid. The control group was only immersed in 1% citric acid. Results: A Wilcoxon test showed a significant increase and decrease in enamel microhardness after exposure to theobromine gel and citric acid (p enamel microhardness between different durations of exposure to theobromine gel and immersion in citric acid (p enamel microhardness but did not contribute to the enamel’s hardness resistance after immersion in 1% citric acid. The duration of theobromine gel application affected enamel microhardness and acid resistance.

  20. Diffusion measurement in ferrous infused gel dosimeters

    International Nuclear Information System (INIS)

    Zahmatkesh, M. H.; Healy, B. J.

    2003-01-01

    Background: The compositions of Ferrous sulphate, Agarose and Xylenol orange dye and Ferrous sulphate, Gelatin and Xylenol orange dye in solution of distilled water and sulphuric acid are two tissue-equivalent gel dosimeters. Ionizing radiation causes oxidation of Fe 2+ ion to Fe 3+ ions which diffuse through the gel matrix and blur the image of absorbed dose over a period of hours after irradiation. Materials and methods: 25 m M sulphuric acid, 0.4 mm ferrous ammonium sulphate, 0.2 mm xylenol orange dye and 1% by weight agarose in distilled water named Agarose and Xylenol orange dye and 0.1 mm ferrous ammonium sulphate, 0.1 mm xylenol orange dye, 50 mm sulphuric acid and 5% by weight gelatin in distilled water named Gelatin and Xylenol orange dye are used as two gel dosimeters. All chemicals were supplied by Sigma Ald ridge Company, Germany. The gels were poured in Perspex casts and were irradiated to a beam of X ray from linear accelerators or X ray machine. Results: In this study diffusion coefficients of Agarose and Xylenol orange dye and Gelatin and Xylenol orange dye dosimeters have been measured through a computer program for different temperature. The ferric ion diffusion coefficient (D) for the Agarose and Xylenol orange dye and Gelatin and Xylenol orange dye dosimeters were measured as (1.19.±0.03) x 10 -2 cm 2 .hr -1 and (0.83±0.03) x 10 -2 cm 2 .hr -1 respectively at room temperature. Conclusion: For both dosimeters the diffusion coefficients decreased with gel storage temperatures down to 6 d ig C . Gelatin and Xylenol orange dye dosimeters have advantage of lower diffusion coefficient for a specified temperature

  1. Ultraviolet absorption detection of DNA in gels

    International Nuclear Information System (INIS)

    Mahon, A.R.

    1998-01-01

    A method and apparatus for the detection and quantification of large fragments of unlabelled deoxyribonucleic acid (DNA) in agarose gels is presented. The technique is based on ultra-violet (UV) absorption by nucleotides. A deuterium lamp was used to illuminate regions of an electrophoresis gel. As DNA bands passed through the illuminated region of the gel the amount of UV light transmitted was reduced due to DNA absorption. Two detection systems were investigated. In the first system, synthetic chemical vapour deposition (CVD) diamond strip detectors were used to locate regions of DNA in the gels by detecting the transmitted light. CVD diamond has a high indirect band gap of 5.45 eV and is therefore sensitive to UV photons of wavelengths < 224 nm. A number of CVD diamond samples were characterised to investigate their suitability as detectors for this application. The detectors' quantum efficiency, UV response and time response were measured. DNA bands containing as little as 20 ng were detected by the diamond. In a second system, a deuterium lamp was used to illuminate individual sample lanes of an electrophoresis gel via an array of optical fibres. During electrophoresis the regions of DNA were detected with illumination at 260 nm, using a UV-sensitive charge coupled device (CCD). As the absorption coefficient of a DNA sample is approximately proportional to its mass, the technique is inherently quantitative. This system had a detection limit of 0.25 ng compared with 2-10 ng for the most popular conventional technique, ethidium bromide (EtBr) staining. Using this detection technique, the DNA sample remains in its native state. The removal of carcinogenic dyes from the detection procedure greatly reduces associated biological hazards. (author)

  2. Normal modes of weak colloidal gels

    Science.gov (United States)

    Varga, Zsigmond; Swan, James W.

    2018-01-01

    The normal modes and relaxation rates of weak colloidal gels are investigated in calculations using different models of the hydrodynamic interactions between suspended particles. The relaxation spectrum is computed for freely draining, Rotne-Prager-Yamakawa, and accelerated Stokesian dynamics approximations of the hydrodynamic mobility in a normal mode analysis of a harmonic network representing several colloidal gels. We find that the density of states and spatial structure of the normal modes are fundamentally altered by long-ranged hydrodynamic coupling among the particles. Short-ranged coupling due to hydrodynamic lubrication affects only the relaxation rates of short-wavelength modes. Hydrodynamic models accounting for long-ranged coupling exhibit a microscopic relaxation rate for each normal mode, λ that scales as l-2, where l is the spatial correlation length of the normal mode. For the freely draining approximation, which neglects long-ranged coupling, the microscopic relaxation rate scales as l-γ, where γ varies between three and two with increasing particle volume fraction. A simple phenomenological model of the internal elastic response to normal mode fluctuations is developed, which shows that long-ranged hydrodynamic interactions play a central role in the viscoelasticity of the gel network. Dynamic simulations of hard spheres that gel in response to short-ranged depletion attractions are used to test the applicability of the density of states predictions. For particle concentrations up to 30% by volume, the power law decay of the relaxation modulus in simulations accounting for long-ranged hydrodynamic interactions agrees with predictions generated by the density of states of the corresponding harmonic networks as well as experimental measurements. For higher volume fractions, excluded volume interactions dominate the stress response, and the prediction from the harmonic network density of states fails. Analogous to the Zimm model in polymer

  3. Encapsulation of nanoclusters in dried gel materials via an inverse micelle/sol gel synthesis

    Science.gov (United States)

    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.

  4. Correlation between ionic conductivity and fluidity of polymer gel ...

    Indian Academy of Sciences (India)

    Unknown

    Ionic conductivity; ion aggregates; FTIR spectroscopy; gels; fluidity. 1. Introduction ... liquid and polymer gel electrolytes have been studied as functions of salt ..... Ratner M A 1987 in Polymer electrolyte reviews (eds) J R. MacCallum and C A ...

  5. Simplified riboprobe purification using translucent straws as gel tubes.

    Science.gov (United States)

    Kol, S; Ben-Shlomo, I; Adashi, E Y; Rohan, R M

    1996-01-01

    Gel purification of radioactive riboprobes enhances the quality of the ribonuclease protection assay. A simple and effective method for riboprobe purification is described. The method uses acrylamide gels in plastic tubes to achieve electrophoretic separation of the RNA polymerase products.

  6. Study of nuclear glasses alteration gel and synthesis of some model gels

    International Nuclear Information System (INIS)

    Ricol, S.

    1995-01-01

    This work deals with the general problem of alteration of the reference nuclear glass R7T7. Attention is paid particularly to the altered layer formed at the glass surface during alteration process. In opposition to previous works, related essentially to glass dissolution kinetics based on chemical analyses of lixiviated elements, this thesis deals with alteration problems through structural studies of the reference glass and derived gel. This approach allows the determination of mechanisms for the gel formation and a better understanding of the behaviour of glasses towards lixiviation. Both approaches appeared complementary. Based on several spectroscopic techniques, this work showed the particular role of cations such as calcium, zirconium and iron. Studies of silica-based synthetic gels showed the synergic effect of formers cation and of one highly coordinated cation. The variation of the wavenumber related to Si-O-Si asymmetric stretching vibration can be correlated to O/Si ratio for ternary systems Si/Na/Zr. On the contrary, the Si losses of the materials depend on the number of non-bridging oxygen atoms. In the perspective of long-term behaviour, the alteration gel presents better characteristics than initial glass. It is therefore a highly stable material in static conditions. In the same way, synthetic gels are materials with very low solubilities (much lower than the alteration gel) and could be used as confining matrices. (authors). refs., 71 figs., 37 tabs

  7. Development and dosimetric evaluation of radiochromic PCDA vesicle gel dosimeters

    International Nuclear Information System (INIS)

    Sun, P.; Fu, Y.C.; Hu, J.; Hao, N.; Huang, W.; Jiang, B.

    2016-01-01

    The gel dosimeter has the unique capacity in recording radiation dose distribution in three dimensions (3D), which has the specific advantages in dosimetry measurements where steep dose gradients exist, such as in intensity-modulated radiation therapy (IMRT), brachytherapy and so on. Some 3D dosimeters, such as Fricke gel dosimeters, polymer gel dosimeters, the PRESAGE plastic dosimeters and micelle gel dosimeters have appeared recently. However, there are several disadvantages of these 3D dosimeters limit their application in radiotherapy dose verification. In this study, a novel radiochromic gel dosimeter for 3D dose verification of radiotherapy was developed by dispersing nanovesicles self-assembled by 10,12-pentacosadiynoic acid (PCDA) into the tissue equivalence gel matrix. The characteristics of radiochromic PCDA vesicle gel dosimeters were evaluated. The results indicate that these radiochromic gel dosimeters have good linear dose response to X-ray irradiation in the dose range of 2–100 Gy. In addition, the radiochromic gel dosimeters breakthrough the limitations of the existing gel dosimeters such as diffusion effect, post-radiation effect, and poor forming ability. The response of the gel dosimeter does not show any dose rate dependence, energy dependence and temperature effect, and there was no obvious difference in the gel response between single and cumulative dose of fractional irradiation. Hence, the radiochromic PCDA vesicle gel dosimeters developed in this study could be generally applied to 3D dose verification in radiotherapy. - Highlights: • A novel radiochromic gel dosimeter was developed by dispersing PCDA nanovesicles into the tissue equivalence gel matrix. • This nanovesicle overcomes the dose image blurring caused by the diffusion of monomer molecules. • This nanovesicle limits the polymer chain growth, so as to reduce the post-radiation effect. • The gel matrixes possess excellent tissue equivalence and elastic strength, which

  8. Intravaginal insertion in KwaZulu Natal: sexual practices and preferences in the context of microbicide gel use

    NARCIS (Netherlands)

    Gafos, M.; Mzimela, M.; Sukazi, S.; Pool, R.; Montgomery, C.; Elford, J.

    2010-01-01

    Intravaginal insertion is often associated with the concept of ‘dry’ sex. All HIV-prevention microbicides tested to date have been vaginally applied lubricant-based gels. In this paper, we examine whether the use of intravaginal insertions could be in conflict with the introduction of vaginal

  9. Antimicrobial efficacy of alcohol-based hand gels.

    Science.gov (United States)

    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.

  10. Formulation and method for preparing gels comprising hydrous aluminum oxide

    Science.gov (United States)

    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.

  11. Reduction of Pulmonary Air Leaks with a Combination of Polyglycolic Acid Sheet and Alginate Gel in Rats

    Directory of Open Access Journals (Sweden)

    Mari Matoba

    2018-01-01

    Full Text Available Postoperative air leaks remain a major cause of morbidity after lung resection. This study evaluated the effect of a combination of polyglycolic acid (PGA sheet and alginate gel on pulmonary air leaks in rats. Four pulmonary sealing materials were evaluated in lung injury: fibrin glue, combination of PGA sheet and fibrin glue, alginate gel, and combination of PGA sheet and alginate gel. With the airway pressure maintained at 20 cmH2O, a 2 mm deep puncture wound was created on the lung surface using a needle. Lowering the airway pressure to 5 cmH2O, each sealing material was applied. The lowest airway pressure that broke the seal was measured. The seal-breaking pressure in each experimental group was fibrin, 10.4±6.8 cmH2O; PGA + fibrin, 13.5±6.5 cmH2O; alginate gel, 10.3±4.9 cmH2O; and PGA + alginate, 35.8±11.9 cmH2O, respectively. The seal-breaking pressure was significantly greater in the PGA + alginate gel group than in the other groups (p<0.01. There were no significant differences among the other three groups. Alginate gel combined with a PGA sheet is a promising alternative to fibrin glue as a safe and low-cost material for air leak prevention in pulmonary surgery.

  12. Preparation of sol-gel TiO2/purified Na-bentonite composites and their photovoltaic application for natural dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Saelim, Ni-on; Magaraphan, Rathanawan; Sreethawong, Thammanoon

    2011-01-01

    Highlights: → Natural dye from red cabbage was successfully employed in DSSC. → A fast sol-gel method to produce TiO 2 /clay thin film was proposed. → The sol-gel-prepared TiO 2 /clay was applied as the scattering layer on top of TiO 2 electrode. → Thicker sol-gel-prepared TiO 2 /clay electrode showed higher DSSC efficiency. - Abstract: The sol-gel TiO 2 /purified natural clay electrodes having Ti:Si molar ratios of 95:5 and 90:10 were initially prepared, sensitized with natural red cabbage dye, and compared to the sol-gel TiO 2 electrode in terms of physicochemical characteristics and solar cell efficiency. The results showed that the increase in purified Na-bentonite content greatly increased the specific surface area and total pore volume of the prepared sol-gel TiO 2 /purified Na-bentonite composites because the clay platelets prevented TiO 2 particle agglomeration. The sol-gel TiO 2 /5 mol% Si purified Na-bentonite and sol-gel TiO 2 /10 mol% Si purified Na-bentonite composites could increase the film thickness of solar cells without cracking when they were coated as a scattering layer on the TiO 2 semiconductor-based film, leading to increasing the efficiency of the natural dye-sensitized solar cells in this work.

  13. Environmentally benign sol-gel antifouling and foul-releasing coatings.

    Science.gov (United States)

    Detty, Michael R; Ciriminna, Rosaria; Bright, Frank V; Pagliaro, Mario

    2014-02-18

    Biofouling on ships and boats, characterized by aquatic bacteria and small organisms attaching to the hull, is an important global issue, since over 80000 tons of antifouling paint is used annually. This biofilm, which can form in as little as 48 hours depending on water temperature, increases drag on watercraft, which greatly reduces their fuel efficiency. In addition, biofouling can lead to microbially induced corrosion (MIC) due to H2S formed by the bacteria, especially sulfate-reducing bacteria. When the International Maritime Organization (IMO) international convention banned the use of effective but environmentally damaging coatings containing tributyl tin in 2008, the development of clean and effective antifouling systems became more important than ever. New nonbiocidal coatings are now in high demand. Scientists have developed new polymers, materials, and biocides, including new elastomeric coatings that they have obtained by improving the original silicone (polydimethylsiloxane) formulation patented in 1975. However, the high cost of silicones, especially of fluoropolymer-modified silicones, has generally prevented their large-scale diffusion. In 2009, traditional antifouling coatings using cuprous oxide formulated in copolymer paints still represented 95% of the global market volume of anti-fouling paints. The sol-gel nanochemistry approach to functional materials has emerged as an attractive candidate for creating low fouling surfaces due to the unique structure and properties of silica-based coatings and of hybrid inorganic-organic silicas in particular. Sol-gel formulations easily bind to all types of surfaces, such as steel, fiberglass, aluminum, and wood. In addition, they can cure at room temperature and form thin glassy coatings that are markedly different from thick silicone elastomeric foul-releasing coatings. Good to excellent performance against biofouling, low cure temperatures, enhanced and prolonged chemical and physical stability, ease of

  14. Carbon Redox-Polymer-Gel Hybrid Supercapacitors

    Science.gov (United States)

    Vlad, A.; Singh, N.; Melinte, S.; Gohy, J.-F.; Ajayan, P.M.

    2016-01-01

    Energy storage devices that provide high specific power without compromising on specific energy are highly desirable for many electric-powered applications. Here, we demonstrate that polymer organic radical gel materials support fast bulk-redox charge storage, commensurate to surface double layer ion exchange at carbon electrodes. When integrated with a carbon-based electrical double layer capacitor, nearly ideal electrode properties such as high electrical and ionic conductivity, fast bulk redox and surface charge storage as well as excellent cycling stability are attained. Such hybrid carbon redox-polymer-gel electrodes support unprecedented discharge rate of 1,000C with 50% of the nominal capacity delivered in less than 2 seconds. Devices made with such electrodes hold the potential for battery-scale energy storage while attaining supercapacitor-like power performances. PMID:26917470

  15. Solvent induced supramolecular anisotropy in molecular gels

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Michael A., E-mail: mroger09@uoguelph.ca [Department of Food Science, University of Guelph, Guelph, Ontario, N3C3X9 (Canada); Corradini, Maria G. [Department of Food Science, University of Massachusetts Amherst, Amherst, MA, 01003 (United States); Emge, Thomas [Department of Chemistry and Biochemistry, Rutgers University, New Brunswick, NJ, 08901 (United States)

    2017-06-15

    Herein is the first report of solvent induced anisotropy in 12-hydroxystearic acid self-assembled fibrillar networks. Increasing the chain length of polar solvent, such as nitriles and ketones, tailored the anisotropy of the fibrillar aggregates. 12HSA molecular gels, comprised of alkanes, exhibited an isotropic fibrillar network irrespective of the alkane chain length. In polar solvents, anisotropy, observed using 2D powder x-ray diffraction profiles, is correlated to a fibrillar supramolecular morphologies in long chain nitriles and ketones while sphereulitic crystals are correlated to x-ray diffraction patterns with an isotropic scatter intensity in short chain ketones and nitriles. These changes directly modify the final physical properties of the gels. - Highlights: • 12-HSA self-assembles into crystalline supramolecular morphologies depending on the solvent. • Alkanes, short chain nitriles and ketones led to 12-HSA displaying supramolecular isotropy. • In long chain nitriles and ketones, 12-HSA displays supramolecular anisotropy.

  16. Solvent induced supramolecular anisotropy in molecular gels

    International Nuclear Information System (INIS)

    Rogers, Michael A.; Corradini, Maria G.; Emge, Thomas

    2017-01-01

    Herein is the first report of solvent induced anisotropy in 12-hydroxystearic acid self-assembled fibrillar networks. Increasing the chain length of polar solvent, such as nitriles and ketones, tailored the anisotropy of the fibrillar aggregates. 12HSA molecular gels, comprised of alkanes, exhibited an isotropic fibrillar network irrespective of the alkane chain length. In polar solvents, anisotropy, observed using 2D powder x-ray diffraction profiles, is correlated to a fibrillar supramolecular morphologies in long chain nitriles and ketones while sphereulitic crystals are correlated to x-ray diffraction patterns with an isotropic scatter intensity in short chain ketones and nitriles. These changes directly modify the final physical properties of the gels. - Highlights: • 12-HSA self-assembles into crystalline supramolecular morphologies depending on the solvent. • Alkanes, short chain nitriles and ketones led to 12-HSA displaying supramolecular isotropy. • In long chain nitriles and ketones, 12-HSA displays supramolecular anisotropy.

  17. Optical-CT scanning of polymer gels

    Energy Technology Data Exchange (ETDEWEB)

    Oldham, M [Radiation Oncology Physics, Duke University Medical Center, Duke University, NC (United States)

    2004-01-01

    The application of optical-CT scanning to achieve accurate high-resolution 3D dosimetry is a subject of current interest. The purpose of this paper is to provide a brief overview of past research and achievements in optical-CT polymer gel dosimetry, and to review current issues and challenges. The origins of optical-CT imaging of light-scattering polymer gels are reviewed. Techniques to characterize and optimize optical-CT performance are presented. Particular attention is given to studies of artifacts in optical-CT imaging, an important area that has not been well studied to date. The technique of optical-CT simulation by Monte-Carlo modeling is introduced as a tool to explore such artifacts. New simulation studies are presented and compared with experimental data.

  18. Local mobility and topology in gels

    International Nuclear Information System (INIS)

    Higgins, J.S.; Ma, K.; Hall, R.H.; Warner, M.

    1981-04-01

    In the first section of this two part report entitled 'Separation of the motion around cross-link points from main chain motion in network samples' by Higgins, Ma and Hall, experimental evidence for topologically dependent diffusion in gels and rubbers is presented from high resolution neutron scattering experiments on deuterium labelled model trifunctional networks which show that the junction points move more slowly than the free chain centres by a factor of about two. In the second part by Warner entitled 'The dynamics of particular points on a polymer chain', the diffusional dynamics of particular points of a polymer chain is calculated in the Rouse approximation. The points considered correspond, in the case of incoherent neutron scattering, to the proton-labelled free ends of chains, crosslinks between chains in rubbers or gels, or the central monomers in branched or star polymers. Results derived are also relevant to NMR, ESR and computer simulation experiments. (U.K.)

  19. Strand Plasticity Governs Fatigue in Colloidal Gels

    Science.gov (United States)

    van Doorn, Jan Maarten; Verweij, Joanne E.; Sprakel, Joris; van der Gucht, Jasper

    2018-05-01

    The repeated loading of a solid leads to microstructural damage that ultimately results in catastrophic material failure. While posing a major threat to the stability of virtually all materials, the microscopic origins of fatigue, especially for soft solids, remain elusive. Here we explore fatigue in colloidal gels as prototypical inhomogeneous soft solids by combining experiments and computer simulations. Our results reveal how mechanical loading leads to irreversible strand stretching, which builds slack into the network that softens the solid at small strains and causes strain hardening at larger deformations. We thus find that microscopic plasticity governs fatigue at much larger scales. This gives rise to a new picture of fatigue in soft thermal solids and calls for new theoretical descriptions of soft gel mechanics in which local plasticity is taken into account.

  20. Gel Fabrication of Molybdenum “Beads”

    Energy Technology Data Exchange (ETDEWEB)

    Lowden, Richard Andrew [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Armstrong, Beth L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Cooley, Kevin M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division

    2016-11-01

    Spherical molybdenum particles or “beads” of various diameters are of interest as feedstock materials for the additive manufacture of targets and assemblies used in the production of 99Mo medical isotopes using accelerator technology. Small metallic beads or ball bearings are typically fabricated from wire; however, small molybdenum spheres cannot readily be produced in this manner. Sol-gel processes are often employed to produce small dense microspheres of metal oxides across a broad diameter range that in the case of molybdenum could be reduced and sintered to produce metallic spheres. These Sol-gel type processes were examined for forming molybdenum oxide beads; however, the molybdenum trioxide was chemically incompatible with commonly used gelation materials. As an alternative, an aqueous alginate process being assessed for the fabrication of oxide spheres for catalyst applications was employed to form molybdenum trioxide beads that were successfully reduced and sintered to produce small molybdenum spheres.

  1. Ceramica sphere production by a gel casting

    International Nuclear Information System (INIS)

    Santos, A.; Assis, G. de; Ferreira, R.A.N.; Ferraz, W.B.; Lopes, J.A.M.; Prado, M.A.S.; Miranda, O.; Drumond, F.J.

    1987-01-01

    The technology of (Th,U)O 2 microspheres production by gel casting and subsequente thermal treatment has been transferred from NUKEM GmbH assisted by Kraftwerk Union A.G., both West Germany, to NUCLEBRAS, where it was jointly adapted to produce microspheres suitable for pressing. As a result, there are now available various possibilities to produce ceramic spheres with different characteristics that can be used in different applications. Examples of these characteristics are the range of gel sphere diameters (200 to 5000 μmm) and the value of the specific surface (about 50m 2 /g for calcined (Th, U)O 2 and potentially higher than m 2 /g for other ceramic materials) (Author) [pt

  2. Optical-CT scanning of polymer gels

    International Nuclear Information System (INIS)

    Oldham, M

    2004-01-01

    The application of optical-CT scanning to achieve accurate high-resolution 3D dosimetry is a subject of current interest. The purpose of this paper is to provide a brief overview of past research and achievements in optical-CT polymer gel dosimetry, and to review current issues and challenges. The origins of optical-CT imaging of light-scattering polymer gels are reviewed. Techniques to characterize and optimize optical-CT performance are presented. Particular attention is given to studies of artifacts in optical-CT imaging, an important area that has not been well studied to date. The technique of optical-CT simulation by Monte-Carlo modeling is introduced as a tool to explore such artifacts. New simulation studies are presented and compared with experimental data

  3. Salmonella Prevention

    Science.gov (United States)

    ... and in vegetable and fruit harvesting and packing operations may help prevent salmonellosis caused by contaminated foods. Better education of food industry workers in basic food safety and restaurant inspection procedures may prevent cross-contamination and other ...

  4. Ring-Resonator/Sol-Gel Interferometric Immunosensor

    Science.gov (United States)

    Bearman, Gregory; Cohen, David

    2007-01-01

    A proposed biosensing system would be based on a combination of (1) a sensing volume containing antibodies immobilized in a sol-gel matrix and (2) an optical interferometer having a ring resonator configuration. The antibodies would be specific to an antigen species that one seeks to detect. In the ring resonator of the proposed system, light would make multiple passes through the sensing volume, affording greater interaction length and, hence, greater antibody- detection sensitivity.

  5. Rheology of Biopolymer Solutions and Gels

    Directory of Open Access Journals (Sweden)

    David R. Picout

    2003-01-01

    Full Text Available Rheological techniques and methods have been employed for many decades in the characterization of polymers. Originally developed and used on synthetic polymers, rheology has then found much interest in the field of natural (bio polymers. This review concentrates on introducing the fundamentals of rheology and on discussing the rheological aspects and properties of the two major classes of biopolymers: polysaccharides and proteins. An overview of both their solution properties (dilute to semi-dilute and gel properties is described.

  6. Transparent Hydrophobic Coating by Sol Gel Method

    International Nuclear Information System (INIS)

    Mohd Hamzah Harun; Nik Ghazali Nik Salleh; Mahathir Mohamed; Mohd Sofian Alias

    2016-01-01

    Transparent hydrophobic coating of inorganic based tetra orthosilicate (TEOS) was prepared by sol gel method by varying fluoroalkylsilane (FAS) content which works as hydrophobic agent. Surface contact angle, transmittance degree and surface morphology were characterized for each sample. All samples show good transparency which was confirmed by UV visible spectroscopy. The hydrophobicity obtained increases with FAS content indicates that FAS is best candidate to induce hydrophobicity for inorganic coating. (author)

  7. Role of gel dosimeters in boron neutron capture therapy

    International Nuclear Information System (INIS)

    Khajeali, Azim; Farajollahi, Ali Reza; Khodadadi, Roghayeh; Kasesaz, Yaser; Khalili, Assef

    2015-01-01

    Gel dosimeters have acquired a unique status in radiotherapy, especially with the advent of the new techniques in which there is a need for three-dimensional dose measurement with high spatial resolution. One of the techniques in which the use of gel dosimeters has drawn the attention of the researchers is the boron neutron capture therapy. Exploring the history of gel dosimeters, this paper sets out to study their role in the boron neutron capture therapy dosimetric process. - Highlights: • Gel dosimeters have been investigated. • Conventional dosimetric proses of BNCT has been investigated. • Role of gel dosimeters in BNCT has been investigated

  8. Equipment for production of hydrogel by sol-gel method

    International Nuclear Information System (INIS)

    Urbanek, V.

    1975-01-01

    The method of uranyl gel preparation is described by the sol-gel process of the internal gelation type. A laboratory-scale equipment with an output of 1.5 kg of gel per hour was built at the Nuclear Research Institute, Rez; the diameter of the microspheres produced may vary between 0.5 and 4.0 mm. The reliability of the equipment was verified by producing several tens of kilograms of uranyl gels and of gels based on other non-nuclear materials. (author)

  9. Harnessing reconsolidation to weaken fear and appetitive memories: A meta-analysis of post-retrieval extinction effects.

    Science.gov (United States)

    Kredlow, M Alexandra; Unger, Leslie D; Otto, Michael W

    2016-03-01

    A new understanding of the mechanisms of memory retrieval and reconsolidation holds the potential for improving exposure-based treatments. Basic research indicates that following fear extinction, safety and fear memories may compete, raising the possibility of return of fear. One possible solution is to modify original fear memories through reconsolidation interference, reducing the likelihood of return of fear. Postretrieval extinction is a behavioral method of reconsolidation interference that has been explored in the context of conditioned fear and appetitive memory paradigms. This meta-analysis examines the magnitude of postretrieval extinction effects and potential moderators of these effects. A PubMed and PsycINFO search was conducted through June 2014. Sixty-three comparisons examining postretrieval extinction for preventing the return of fear or appetitive responses in animals or humans met inclusion criteria. Postretrieval extinction demonstrated a significant, small-to-moderate effect (g = .40) for further reducing the return of fear in humans and a significant, large effect (g = 0.89) for preventing the return of appetitive responses in animals relative to standard extinction. For fear outcomes in animals, effects were small (g = 0.21) and nonsignificant, but moderated by the number of animals housed together and the duration of time between postretrieval extinction/extinction and test. Across paradigms, these findings support the efficacy of this preclinical strategy for preventing the return of conditioned fear and appetitive responses. Overall, findings to date support the continued translation of postretrieval extinction research to human and clinical applications, with particular application to the treatment of anxiety, traumatic stress, and substance use disorders. (c) 2016 APA, all rights reserved).

  10. Harnessing Reconsolidation to Weaken Fear and Appetitive Memories: A Meta-Analysis of Post-Retrieval Extinction Effects

    Science.gov (United States)

    Kredlow, M. Alexandra; Unger, Leslie D.; Otto, Michael W.

    2015-01-01

    A new understanding of the mechanisms of memory retrieval and reconsolidation holds the potential for improving exposure-based treatments. Basic research indicates that following fear extinction, safety and fear memories may compete, raising the possibility of return of fear. One possible solution is to modify original fear memories through reconsolidation interference, reducing the likelihood of return of fear. Post-retrieval extinction is a behavioral method of reconsolidation interference that has been explored in the context of conditioned fear and appetitive memory paradigms. This meta-analysis examines the magnitude of post-retrieval extinction effects and potential moderators of these effects. A PubMed and PsycINFO search was conducted through June 2014. Sixty-three comparisons examining post-retrieval extinction for preventing the return of fear or appetitive responses in animals or humans met inclusion criteria. Post-retrieval extinction demonstrated a significant, small-to-moderate effect (g = .40) for further reducing the return of fear in humans and a significant, large effect (g = 0.89) for preventing the return of appetitive responses in animals relative to standard extinction. For fear outcomes in animals, effects were small (g = 0.21) and non-significant, but moderated by the number of animals housed together and the duration of time between post-retrieval extinction/extinction and test. Across paradigms, these findings support the efficacy of this pre-clinical strategy for preventing the return of conditioned fear and appetitive responses. Overall, findings to date support the continued translation of post-retrieval extinction research to human and clinical applications, with particular application to the treatment of anxiety, traumatic stress, and substance use disorders. PMID:26689086

  11. Silica-Based Sol-Gel Coating on Magnesium Alloy with Green Inhibitors

    Directory of Open Access Journals (Sweden)

    Vinod Upadhyay

    2017-06-01

    Full Text Available In this work, the performances of several natural organic inhibitors were investigated in a sol-gel system (applied on the magnesium alloy Mg AZ31B substrate. The inhibitors were quinaldic acid (QDA, betaine (BET, dopamine hydrochloride (DOP, and diazolidinyl urea (DZU. Thin, uniform, and defect-free sol-gel coatings were prepared with and without organic inhibitors, and applied on the Mg AZ31B substrate. SEM and EDX were performed to analyze the coating surface properties, the adhesion to the substrate, and the thickness. Electrochemical measurements, including electrochemical impedance spectroscopy (EIS and anodic potentiodynamic polarization scan (PDS, were performed on the coated samples to characterize the coatings’ protective properties. Also, hydrogen evolution measurement—an easy method to measure magnesium corrosion—was performed in order to characterize the efficiency of coating protection on the magnesium substrate. Moreover, scanning vibrating electrode technique (SVET measurements were performed to examine the efficiency of the coatings loaded with inhibitors in preventing and containing corrosion events in defect areas. From the testing results it was observed that the formulated sol-gel coatings provided a good barrier to the substrate, affording some protection even without the presence of inhibitors. Finally, when the inhibitors’ performances were compared, the QDA-doped sol-gel was able to contain the corrosion event at the defect.

  12. Stretchable carbon nanotube/ion-gel supercapacitors with high durability realized through interfacial microroughness.

    Science.gov (United States)

    Lee, Jiho; Kim, Wonbin; Kim, Woong

    2014-08-27

    A critical problem with stretchable supercapacitors developed to date has been evaporation of a volatile component of their electrolyte, causing failure. In this work, we demonstrated successful use of an ionic-liquid-based nonvolatile gel (ion-gel) electrolyte in carbon nanotube (CNT)-based stretchable supercapacitors. The CNT/ion-gel supercapacitors showed high capacitance retention (96.6%) over 3000 stretch cycles at 20% strain. The high durability against stretch cycles was achieved by introducing microroughness at the interfaces between different materials. The microroughness was produced by the simple process of imprinting the surface microstructure of office paper onto a poly(dimethylsiloxane) substrate; the surface texture is reproduced in successive current collector and CNT layers. Adhesion between the different layers was strengthened by this roughness and prevented delamination over repeated stretch cycles. The addition of a CNT layer decreased the sensitivity of electrical characteristics to stretching. Moreover, the ion-gel increases the operating voltage window (3 V) and hence the energy density. We believe our demonstration will greatly contribute to the development of flexible and/or stretchable energy-storage devices with high durability.

  13. Hydrogen permeation through sol-gel-coated iron during galvanostatic charging

    International Nuclear Information System (INIS)

    Zakorchemna, I.; Carmona, N.; Zakroczymski, T.

    2008-01-01

    One-layer sol-gel silica-zirconia and two-layer silica-zirconia and zirconia coatings were deposited on one side of iron membranes by spin-coating, densified in air and annealed up to 800 deg. C in vacuum. Hydrogen permeation through the membranes, coated and uncoated, polarised cathodically under galvanostatic control in 0.1 M NaOH solution was studied using the electrochemical permeation technique. During the initial period, the effect of the sol-gel coatings was insignificant. However, the coatings quite efficiently prevented the iron surface become more active to hydrogen entry during a long-lasting cathodic polarisation. In addition, the electrochemical-corrosion behaviour of the coated iron and the effect of the sol-gel coatings on the effective diffusivity of hydrogen in the coated membranes were studied. On the basis of the polarisation curves and the hydrogen permeation data it was proved that the sol-gel coatings blocked the iron surface for the hydrogen evolution reaction and, consequently, for the hydrogen entry into iron. The effective coating coverage was determined by comparison of the hydrogen fluxes permeating the coated and uncoated membranes. Finally the real concentration of hydrogen beneath the uncoated iron sites and the amount of hydrogen stored in a membrane were evaluated

  14. Effect of hydrothermal process for inorganic alumina sol on crystal structure of alumina gel

    Directory of Open Access Journals (Sweden)

    K. Yamamura

    2016-09-01

    Full Text Available This paper reports the effect of a hydrothermal process for alumina sol on the crystal structure of alumina gel derived from hydrothermally treated alumina sol to help push forward the development of low temperature synthesis of α-Al2O3. White precipitate of aluminum hydroxide was prepared with a homogeneous precipitation method using aluminum nitrate and urea in aqueous solution. The obtained aluminum hydroxide precipitate was peptized by using acetic acid at room temperature, which resulted in the production of a transparent alumina sol. The alumina sol was treated with a hydrothermal process and transformed into an alumina gel film by drying at room temperature. Crystallization of the alumina gel to α-Al2O3 with 900 °C annealing was dominant for a hydrothermal temperature of 100 °C and a hydrothermal time of 60 min, as production of diaspore-like species was promoted with the hydrothermal temperature and time. Excess treatments with hydrothermal processes at higher hydrothermal temperature for longer hydrothermal time prevented the alumina gel from being crystallized to α-Al2O3 because the excess hydrothermal treatments promoted production of boehmite.

  15. Sol-Gel Chemistry for Carbon Dots.

    Science.gov (United States)

    Malfatti, Luca; Innocenzi, Plinio

    2018-03-14

    Carbon dots are an emerging class of carbon-based nanostructures produced by low-cost raw materials which exhibit a widely-tunable photoluminescence and a high quantum yield. The potential of these nanomaterials as a substitute of semiconductor quantum dots in optoelectronics and biomedicine is very high, however they need a customized chemistry to be integrated in host-guest systems or functionalized in core-shell structures. This review is focused on recent advances of the sol-gel chemistry applied to the C-dots technology. The surface modification, the fine tailoring of the chemical composition and the embedding into a complex nanostructured material are the main targets of combining sol-gel processing with C-dots chemistry. In addition, the synergistic effect of the sol-gel precursor combined with the C-dots contribute to modify the intrinsic chemo-physical properties of the dots, empowering the emission efficiency or enabling the tuning of the photoluminescence over a wide range of the visible spectrum. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Sol-gel bonding of silicon wafers

    International Nuclear Information System (INIS)

    Barbe, C.J.; Cassidy, D.J.; Triani, G.; Latella, B.A.; Mitchell, D.R.G.; Finnie, K.S.; Bartlett, J.R.; Woolfrey, J.L.; Collins, G.A.

    2005-01-01

    Low temperature bonding of silicon wafers was achieved using sol-gel technology. The initial sol-gel chemistry of the coating solution was found to influence the mechanical properties of the resulting bonds. More precisely, the influence of parameters such as the alkoxide concentration, water-to-alkoxide molar ratio, pH, and solution aging on the final bond morphologies and interfacial fracture energy was studied. The thickness and density of the sol-gel coating were characterised using ellipsometry. The corresponding bonded specimens were investigated using attenuated total reflectance Fourier transformed infrared spectroscopy to monitor their chemical composition, infrared imaging to control bond integrity, and cross-sectional transmission electron microscopy to study their microstructure. Their interfacial fracture energy was measured using microindentation. An optimum water-to-alkoxide molar ratio of 10 and hydrolysis water at pH = 2 were found. Such conditions led to relatively dense films (> 90%), resulting in bonds with a fracture energy of 3.5 J/m 2 , significantly higher than those obtained using classical hydrophilic bonding (typically 1.5-2.5 J/m 2 ). Ageing of the coating solution was found to decrease the bond strength

  17. Highly-correlated charges in polyelectrolyte gels

    Science.gov (United States)

    Sing, Charles; Zwanikken, Johannes; Olvera de La Cruz, Monica

    2013-03-01

    Polyelectrolyte gels are ubiquitous in polymer physics due to their attractive combination of structural and chemical features that permit the realization of ``environmentally responsive'' systems. The conventional conceptual picture of the volume response of these systems is based on a competition between osmotic and elastic effects. We elaborate on this fundamental understanding by including ion correlations through the use of liquid-state integral equation theory. This allows for a statistical mechanical representation of the state of the system that not only surpasses traditional Poisson-Boltzmann theories but also renders structural features in a highly accurate fashion. In particular, the local ion structure is elucidated, allowing for detailed articulation of charge inversion and condensation effects in the context of gel swelling. The inclusion of correlations has a number of ramifications that become apparent, with enhanced gel collapse and excluded volume competitions that give rise to novel and ion-dependent reentrant swelling effects. We expect this rigorous theory to prove instructive in understanding any number of gelated structures, such as chromosomes or designed synthetic materials for drug delivery.

  18. Polymer gel dosimeter based on itaconic acid

    International Nuclear Information System (INIS)

    Mattea, Facundo; Chacón, David

    2015-01-01

    A new polymeric dosimeter based on itaconic acid and N, N’-methylenebisacrylamide was studied. The preparation method, compositions of monomer and crosslinking agent and the presence of oxygen in the dosimetric system were analyzed. The resulting materials were irradiated with an X-ray tube at 158 cGy/min, 226 cGy min and 298 cGy/min with doses up to 1000 Gy. The dosimeters presented a linear response in the dose range 75–1000 Gy, sensitivities of 0.037 1/Gy at 298 cGy/min and an increase in the sensitivity with lower dose rates. One of the most relevant outcomes in this study was obtaining different monomer to crosslinker inclusion in the formed gel for the dosimeters where oxygen was purged during the preparation method. This effect has not been reported in other typical dosimeters and could be attributed to the large differences in the reactivity among these species. - Highlights: • A novel polymer gel dosimeters based on itaconic acid is presented and characterized. • The typical linear trend of the dose behavior in a specific dose range was found. • Different gel structures were formed when oxygen and an antioxidant were present. • Absorbed dose is univocally correlated with optic absorbance and Raman spectroscopy. • Itaconic acid appears as a reliable radiation dosimeter that may be further improved.

  19. Sol-gel method for encapsulating molecules

    Science.gov (United States)

    Brinker, C. Jeffrey; Ashley, Carol S.; Bhatia, Rimple; Singh, Anup K.

    2002-01-01

    A method for encapsulating organic molecules, and in particular, biomolecules using sol-gel chemistry. A silica sol is prepared from an aqueous alkali metal silicate solution, such as a mixture of silicon dioxide and sodium or potassium oxide in water. The pH is adjusted to a suitably low value to stabilize the sol by minimizing the rate of siloxane condensation, thereby allowing storage stability of the sol prior to gelation. The organic molecules, generally in solution, is then added with the organic molecules being encapsulated in the sol matrix. After aging, either a thin film can be prepared or a gel can be formed with the encapsulated molecules. Depending upon the acid used, pH, and other processing conditions, the gelation time can be from one minute up to several days. In the method of the present invention, no alcohols are generated as by-products during the sol-gel and encapsulation steps. The organic molecules can be added at any desired pH value, where the pH value is generally chosen to achieve the desired reactivity of the organic molecules. The method of the present invention thereby presents a sufficiently mild encapsulation method to retain a significant portion of the activity of the biomolecules, compared with the activity of the biomolecules in free solution.

  20. Modelling of the inhomogeneous interior of polymer gels

    International Nuclear Information System (INIS)

    Shew, C-Y; Iwaki, Takafumi

    2006-01-01

    A simple model has been investigated to elucidate the mean squared displacement (MSD) of probe molecules in cross-linked polymer gels. In the model, we assume that numerous cavities distribute in the inhomogeneous interior of a gel, and probe molecules are confined within these cavities. The individual probe molecules trapped in a gel are treated as Brownian particles confined to a spherical harmonic potential. The harmonic potential is chosen to model the effective potential experienced by the probe particle in the cavity of a gel. Each field strength is corresponding to the characteristic of one type of effective cavity. Since the statistical distribution of different effective cavity sizes is unknown, several distribution functions are examined. Meanwhile, the calculated averaged MSDs are compared to the experimental data by Nisato et al (2000 Phys. Rev. E 61 2879). We find that the theoretical results of the MSD are sensitive to the shape of the distribution function. For low cross-linked gels, the best fit is obtained when the interior cavities of a gel follow a bimodal distribution. Such a result may be attributed to the presence of at least two distinct classes of cavity in gels. For high cross-linked gels, the cavities in the gel can be depicted by a single-modal uniform distribution function, suggesting that the range of cavity sizes becomes smaller. These results manifest the voids inside a gel, and the shape of distribution functions may provide the insight into the inhomogeneous interior of a gel

  1. Rumours about blood and reimbursements in a microbicide gel trial.

    Science.gov (United States)

    Stadler, Jonathan; Saethre, Eirik

    2010-12-01

    A rumour that emerged during a microbicide gel trial tells the tale of clinic staff purchasing trial participants' blood. This paper documents the rumour and explores its divergent interpretations and meanings in relation to the context of the trial and the social and economic setting at two of the trial sites (Soweto and Orange Farm) in South Africa. The article is based on qualitative research conducted during the Microbicides Development Programme (MDP) 301 trial to evaluate a microbicide vaginal gel for HIV prevention in women. The research incorporated in-depth interviews with female trial participants and their male partners, focus group discussions with male and female community members, and participant observation in the trial clinic and community setting at the two sites. The article analyses the different perspectives among the clinic staff, community and trial participants in terms of which the rumour about the exchange of blood for cash is seen as: 1) the result of ignorance of the clinical trial procedures; 2) the exploitation of poor and vulnerable women; 3) an example of young women's desire for material gain; and 4) a reciprocal exchange of 'clean blood' for cash between women trial participants and the health services. We suggest that the rumours about selling blood verbalise notions of gender and morality while also providing an appraisal of the behaviour of young women and a critique of social relationships between foreign researchers and local participants. Through stories about the clinical trial procedures and its potential reimbursements, the participants were creating and reconfiguring social relationships. Ultimately, rumours are one way in which foreign enterprises such as a clinical trial are rendered local.

  2. Gel chromatography of sup(99m)Tc-labelled compounds

    International Nuclear Information System (INIS)

    Vilcek, S.; Machan, V.; Kalincak, M.

    1976-01-01

    The present state of gel chromatography of sup(99m)Tc-labelled compounds is reviewed. Examples are given of gel chromatography for preparing labelled compounds and for quality control analysis and the development of new types of sup(99m)Tc-labelled compounds. The factors which influence the gel chromatography of these compounds are discussed, i.e., the nature of the elution agent, the duration of the contact of the gel and the preparation the gel type, the nature of the labelled compound. The GCS method (gel chromatography scanning) is briefly described. The advantages of gel chromatography as compared with other chromatographic techniques for sup(99m)Tc-labelled compounds are summarized. (author)

  3. Antioxidant effect of green tea on polymer gel dosimeter

    International Nuclear Information System (INIS)

    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

  4. Colloid molecular weight estimation by gel chromatography/acrylamide gel electrophoresis

    International Nuclear Information System (INIS)

    Liberatore, F.A.; Dearborn, C.; Nigam, S.; Poon, C.; Camin, L.; Liteplo, M.

    1984-01-01

    Size or molecular weight (MW) estimation of radiolabeled collides in aqueous solutions has long been a problem. The authors have prepared several minimicroaggregated albumin colloids (mμAA) by heat denaturation of stannous-containing HSA solutions at pH 7.0, 7.5, and 8.5). The resulting colloids were labeled with Tc-99m and compared with Au-198 colloid and Tc-99m-antimony sulfide colloid (Tc-99m-Sb/sub 2/S3) by gel chromatography and gel electrophoresis. Tc-99mm-mμAA aggregated at pH 7.0 and the Au-198 colloid appeared in the external void volume of a BioRad A5.0 agarose column indicating an apparent MW of > 5 x 10/sup 6/ daltons. The pH7.5 Tc-99m-mμAA, migrated within the filtration range of the column as did a small fraction of Tc-99m-Sb/sub 2/S/sub 3/, suggesting that the MW is between 6 x 10/sup 4/ - 5 x 10/sup 6/ daltons. The Tc-99m-mμAA, aggregated at pH 8.5, had an apparent MW on gel filtration similar to that of untreated albumin, MW 6.6 x 10-/sup 4/ daltons. The mobilities of the colloids, on acrylamide disc gel electrophoresis, were consistent with the results on gel chromatography. The largest colloids, Au-198 colloid and pH 7.0 Tc-99m-mμAA, barely entered the separating gel; intermediate sized colloids, a small fraction of Tc-99m-Sb/sub 2/S/sub 3/ and pH 7.5 Tc-99m-mμAA migrated farther into the separating gel; while pH 8.5 Tc-99m-mμAA had mobility approaching that of untreated albumin. Lymphoscintigraphy studies using these colloids in animals showed the predicted, particle size-related differences in migration and clearance. The authors conclude that gel chromatography and gel electrophoresis are useful methods for estimating the apparent size of the colloidal particles

  5. Agarose gel electrophoresis and polyacrylamide gel electrophoresis for visualization of simple sequence repeats.

    Science.gov (United States)

    Anderson, James; Wright, Drew; Meksem, Khalid

    2013-01-01

    In the modern age of genetic research there is a constant search for ways to improve the efficiency of plant selection. The most recent technology that can result in a highly efficient means of selection and still be done at a low cost is through plant selection directed by simple sequence repeats (SSRs or microsatellites). The molecular markers are used to select for certain desirable plant traits without relying on ambiguous phenotypic data. The best way to detect these is the use of gel electrophoresis. Gel electrophoresis is a common technique in laboratory settings which is used to separate deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) by size. Loading DNA and RNA onto gels allows for visualization of the size of fragments through the separation of DNA and RNA fragments. This is achieved through the use of the charge in the particles. As the fragments separate, they form into distinct bands at set sizes. We describe the ability to visualize SSRs on slab gels of agarose and polyacrylamide gel electrophoresis.

  6. Ionogel Electrolytes through Sol-Gel Processing

    Science.gov (United States)

    Horowitz, Ariel I.

    Electrical energy needs have intensified due to the ubiquity of personal electronics, the decarbonization of energy services through electrification, and the use of intermittent renewable energy sources. Despite developments in mechanical and thermal methods, electrochemical technologies are the most convenient and effective means of storing electrical energy. These technologies include both electrochemical cells, commonly called batteries, and electrochemical double-layer capacitors, or "supercapacitors", which store energy electrostatically. Both device types require an ion-conducting electrolyte. Current devices use solutions of complex salts in organic solvents, leading to both toxicity and flammability concerns. These drawbacks can be avoided by replacing conventional electrolytes with room-temperature molten salts, known as ionic liquids (ILs). ILs are non-volatile, non-flammable, and offer high conductivity and good electrochemical stability. Device mass can be reduced by combining ILs with a solid scaffold material to form an "ionogel," further improving performance metrics. In this work, sol-gel chemistry is explored as a means of forming ionogel electrolytes. Sol-gel chemistry is a solution-based, industrially-relevant, well-studied technique by which solids such as silica can be formed in situ. Previous works used a simple acid-catalyzed sol-gel reaction to create brittle, glassy ionogels. Here, both the range of products that can be accomplished through sol-gel processing and the understanding of interactions between ILs and the sol-gel reaction network are greatly expanded. This work introduces novel ionogel materials, including soft and compliant silica-supported ionogels and PDMS-supported ionogels. The impacts of the reactive formulation, IL identity, and casting time are detailed. It is demonstrated that variations in formulation can lead to rapid gelation and open pore structures in the silica scaffold or slow gelation and more dense silica

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

    Science.gov (United States)

    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.

  8. Sol-gel synthesis of hydroxyapatite; Sintese de hidroxiapatita via sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P., E-mail: michelledunin@yahoo.com.b [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)

    2010-07-01

    Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)

  9. Positron annihilation lifetime studies of sol-gel transition of carrageenan gels

    International Nuclear Information System (INIS)

    Wakabayashi, Y.; Ito, K.; Li, H.L.; Ujihara, Y.

    1996-01-01

    Positron annihilation lifetime measurement was applied to study the sol-gel transition of anionic polysaccharide aqueous solutions in terms of free-volume parameters the size, intensity, and size distribution of free volumes of the gelation of K-form κ-carrageenan solutions as a function of temperature. Slight variations of free volume size and intensity against temperature were observed near 295 K. The correlation of free-volume data with other physical properties vibrational spectra (IR and Raman), conductivity, SAXS, elastic measurement, differential scanning calorimetry were investigated to understand the mechanism of sol-gel transition of carrageenan. (author)

  10. Epidemic models for phase transitions: application to a physical gel

    Science.gov (United States)

    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.

  11. Sol-gel process for thermal reactor fuel fabrication

    International Nuclear Information System (INIS)

    Mukerjee, S.K.

    2008-01-01

    Full text: Sol-gel processes have revolutionized conventional ceramic technology by providing extremely fine and uniform powders for the fabrication of ceramics. The use of this technology for nuclear fuel fabrication has also been explored in many countries. Unlike the conventional sol-gel process, sol-gel process for nuclear fuels tries to eliminate the preparation of powders in view of the toxic nature of the powders particularly those of plutonium and 233 U. The elimination of powder handling thus makes this process more readily amenable for use in glove boxes or for remote handling. In this process, the first step is the preparation of microspheres of the fuel material from a solution which is then followed by vibro-compaction of these microspheres of different sizes to obtain the required smear density of fuel inside a pin. The maximum achievable packing density of 92 % makes it suitable for fast reactors only. With a view to extend the applicability of sol-gel process for thermal reactor fuel fabrication the concept of converting the gel microspheres derived from sol-gel process, to the pellets, has been under investigation for several years. The unique feature of this process is that it combines the advantages of sol-gel process for the preparation of fuel oxide gel microspheres of reproducible quality with proven irradiation behavior of the pellet fuel. One of the important pre-requisite for the success of this process is the preparation of soft oxide gel microspheres suitable for conversion to dense pellets free from berry structure. Studies on the internal gelation process, one of the many variants of sol-gel process, for obtaining soft oxide gel microspheres suitable for gel pelletisation is now under investigation at BARC. Some of the recent findings related to Sol-Gel Microsphere Pelletisation (SGMP) in urania-plutonia and thoria-urania systems will be presented

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

    Science.gov (United States)

    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.

  13. Clampless anastomosis with an intraluminal thermosensitive gel: first application in reconstructive microsurgery and literature review.

    Science.gov (United States)

    Giessler, G A; Fischborn, G T; Schmidt, A B

    2012-01-01

    Microvascular clamps of various designs provide a bloodless field for a safe anastomosis but can cause intimal lesions, occupy space in confined sites and have a risk of backwalling due to vessel flattening. They are often insufficient in their haemostatic effect in plaque-filled atherosclerotic vessels. A new, CE-certified thermosensitive gel (LeGoo™) clinically proven in cardiovascular surgery allows a clampless microanastomosis technique. We operated on a series of five consecutive patients aged 24-71 years with six flaps for lower-extremity reconstruction using a clampless anastomosis technique with LeGoo™. We transplanted one fabricated chimaeric fibula plus gracilis, three gracilis muscle and one anterolateral thigh (ALT) flap. Pre- and postoperative protocols were similar to a 'standard' procedure with micro-clamps. All flaps survived completely except for a small area on fibula skin island, which was unrelated to gel use. The gel-assisted technique has a quick learning curve, according to this case series. The veins should be sutured first to prevent stasis in the flap. The gel provides circular stenting and gentle distension of the vessels for a safe and blood-free anastomotic site. It is completely dissolved after completion of the anastomosis with cold saline irrigation. Repolymerisation in the periphery will not occur, making it safe for microvascular flap surgery. From the experiences from this series and other specialities, the use of the thermosensitive gel LeGoo™ permits a safe clampless microanastomosis technique minimising mechanical vessel manipulation and compression. This makes it an attractive alternative to micro-clamps, especially for atherosclerotic arteries and confined anastomosis sites. Copyright © 2011 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  14. Influence of gel morphology on the corrosion kinetics of borosilicate glass: calcium and zirconium effect

    International Nuclear Information System (INIS)

    Cailleteau, C.

    2008-12-01

    This study is related to the question of the long-term behaviour of the nuclear waste confinement glass. A glass alteration layer (known as the 'gel'), formed at the glass surface in contact with water, can limit the exchanges between the glass and the solution. We studied five oxide based glasses SiO 2 -B 2 O 3 -Na 2 O-CaO-ZrO 2 . Two series of glasses were synthesized by substituting CaO for Na 2 O and ZrO 2 for SiO 2 . The leaching showed that the presence of Ca improves the reticulation of the vitreous network, inducing a decrease in the final degree of corrosion and the presence of Zr prevents the hydrolysis of silicon, which leads to a decrease of the initial dissolution rate. However, the introduction of Zr delays the drop of the alteration rate and leads to an increase in the alteration degree. In order to explain this unexpected behaviour, the gel morphology was investigated by small angle X-ray scattering. These experiments showed that the restructuring of porous network during the glass alteration process is limited by the increase of the Zr-content. Then, the restructuring of gel is at the origin of the major drop in the alteration rate observed for the low Zr-content glasses. Besides, both time-of-flight secondary-ion mass spectroscopy (ToF-SIMS) that provides an evaluation of extraneous element penetration into the gel pores and neutron scattering with index matching showed that the porosity closed during the corrosion in the glass without zirconia, but remained open in the high Zr-content glasses. These experiments, associated to simulations by a Monte Carlo method, establish a relationship between the morphologic transformations of gel and the alteration kinetics. (author)

  15. Prevention: Exercise

    Medline Plus

    Full Text Available ... Steroid Injections Lumbar Zygapophysical (Facet) Joint Injections PREVENTION Lifestyle Choices 10 Tips for a Healthy Back Smoking Weight Patient Safety Exercise Strengthening Strengthen ...

  16. Increasing persistent haze in Beijing: potential impacts of weakening East Asian winter monsoons associated with northwestern Pacific sea surface temperature trends

    Directory of Open Access Journals (Sweden)

    L. Pei

    2018-03-01

    Full Text Available Over the past decades, Beijing, the capital city of China, has encountered increasingly frequent persistent haze events (PHE. While the increased pollutant emissions are considered as the most important reason, changes in regional atmospheric circulations associated with large-scale climate warming also play a role. In this study, we find a significant positive trend of PHE in Beijing for the winters from 1980 to 2016 based on updated daily observations. This trend is closely related to an increasing frequency of extreme anomalous southerly episodes in North China, a weakened East Asian trough in the mid-troposphere and a northward shift of the East Asian jet stream in the upper troposphere. These conditions together depict a weakened East Asian winter monsoon (EAWM system, which is then found to be associated with an anomalous warm, high-pressure system in the middle–lower troposphere over the northwestern Pacific. A practical EAWM index is defined as the seasonal meridional wind anomaly at 850 hPa in winter over North China. Over the period 1900–2016, this EAWM index is positively correlated with the sea surface temperature anomalies over the northwestern Pacific, which indicates a wavy positive trend, with an enhanced positive phase since the mid-1980s. Our results suggest an observation-based mechanism linking the increase in PHE in Beijing with large-scale climatic warming through changes in the typical regional atmospheric circulation.

  17. Patterning titania with the conventional and modified micromolding in capillaries technique from sol–gel and dispersion solutions

    Directory of Open Access Journals (Sweden)

    Sajid Ullah Khan and Johan E ten Elshof

    2012-01-01

    Full Text Available We report TiO2 patterns obtained by a soft-lithographic technique called 'micromolding in capillaries' using sol–gel and dispersion solutions. A comparison between patterning with a sol–gel and dispersion solutions has been performed. The patterns obtained from sol–gel solutions showed good adhesion to the substrate and uniform shapes, but large shrinkage, whereas those obtained from dispersion solution had high solid content, but exhibited poor adhesion and non-uniform shapes. A fabrication method of a layer-by-layer structured pattern is also demonstrated. This type of pattern may find application in sensors, waveguides and other photonics elements. The occurrence of an undesirable residue layer, which hinders the fabrication of isolated patterns, is highlighted and a method of prevention is suggested.

  18. Industrial applications of sol-gel technology

    International Nuclear Information System (INIS)

    Tuloch, S.M.; Tulloch, G.E.

    1995-01-01

    The purpose of this paper has been to provide a broad, rather than comprehensive view. We have presented a range of applications and only a selection of involved companies and researchers and have relied to a large extent on published information. Nevertheless, we are sure that our view of the importance of Sol-gel technology as an emerging technology, with enormous impact across a wide range of manufacturing, is demonstrated. Applications which are either in production or have been foreshadowed include four broad categories: coatings, fibres, powders and monoliths

  19. Native gel analysis for RISC assembly.

    Science.gov (United States)

    Kawamata, Tomoko; Tomari, Yukihide

    2011-01-01

    Small-interfering RNAs (siRNAs) and microRNAs (miRNAs) regulate expression of their target mRNAs via the RNA-induced silencing complex (RISC). A core component of RISC is the Argonaute (Ago) protein, which dictates the RISC function. In Drosophila, miRNAs and siRNAs are generally loaded into Ago1-containing RISC (Ago1-RISC) and Ago2-containing RISC (Ago2-RISC), respectively. We developed a native agarose gel system to directly detect Ago1-RISC, Ago2-RISC, and their precursor complexes. Methods presented here will provide powerful tools to biochemically dissect the RISC assembly pathways.

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

    Science.gov (United States)

    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 cooking. Gel-setting conditions had a greater (P 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.

  1. Investigating potential physicochemical errors in polymer gel dosimeters

    International Nuclear Information System (INIS)

    Sedaghat, Mahbod; Lepage, Martin; Bujold, Rachel

    2011-01-01

    Measurement errors in polymer gel dosimetry can originate either during irradiation or scanning. One concern related to the exothermic nature of polymerization reaction was that the heat released in polymer gel dosimeters during irradiation modifies their dose response. In this paper, the effect of heat released from the exothermal polymerization reaction on the dose response of a number of dosimeters was studied. In addition, we investigated whether heat-generated geometric distortion existed in newly proposed gel dosimeters that contain highly thermoresponsive polymers. Our results suggest that despite a significant internal temperature increase in some gel compositions, their dose responses are not affected when oxygen is well expelled mechanically from the gel mixture. We also report on significant pre-irradiation instability in some recently developed polymer gel dosimeters but that geometric distortions were not observed. Data obtained by a set of small calibration vials are compared to those obtained from larger phantoms, and potential physicochemical causes of deviations between them are identified.

  2. Detection of Aspartic Proteinase Activities Using Gel Zymography.

    Science.gov (United States)

    Perera, Handunge Kumudu Irani

    2017-01-01

    Gel zymography is a two-stage process where the proteins from the test sample are first separated by electrophoresis followed by the detection of the activity of hydrolytic enzymes. Many zymography procedures use sodium dodecyl sulfate (SDS) polyacrylamide gels copolymerized with an appropriate substrate. The procedure described here uses native polyacrylamide gel electrophoresis (PAGE) in the absence of both SDS and substrate. In order to visualize aspartic proteinase activity, the gel is impregnated in bovine hemoglobin at pH 3.0 for 15 min after the electrophoresis procedure. Subsequently, the gel is incubated in a humid container in the absence of hemoglobin for 1 h at 37 °C. At the end, the gel is stained with amido black and destained. Clear areas against a dark background corresponding to aspartic proteinase activities can be detected.

  3. Encapsulation of biological species in sol-gel matrices

    International Nuclear Information System (INIS)

    Finnie, K.S.; Bartlett, J.R.; Woolfrey, J.L.

    2000-01-01

    Two examples are given of the gelation of silica sols containing bio catalysts, resulting in their encapsulation in porous matrices. Urease was encapsulated in gels made from a mixture of TMOS and alkyltrimethoxysilane. Enzyme activities, monitored by measuring the rate of production of ammoniacal nitrogen as urea was decomposed, ranged up to 60% of that of the unencapsulated species. Anaerobic sulphate-reducing bacteria were encapsulated in a gel produced from colloidal silica, thus avoiding contact with alcohol. The detection of H 2 S produced in the doped gel indicated that the bacteria were able to continue normal metabolic function within the gel matrix. A gel initially doped with ∼ 5 x 10 5 cells cm -3 , exhibited an optimum sulphate reduction rate of 11 ug h -1 cm -3 ; this reduction rate was quickly re-established after storage of the gel for 14 weeks. Copyright (2000) The Australian Ceramic Society

  4. Investigating potential physicochemical errors in polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Sedaghat, Mahbod; Lepage, Martin [Centre d' imagerie moleculaire de Sherbrooke, Departement de medecine nucleaire et radiobiologie, Universite de Sherbrooke, Sherbrooke, QC (Canada); Bujold, Rachel, E-mail: martin.lepage@usherbrooke.ca [Service de radio-oncologie, Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC (Canada)

    2011-09-21

    Measurement errors in polymer gel dosimetry can originate either during irradiation or scanning. One concern related to the exothermic nature of polymerization reaction was that the heat released in polymer gel dosimeters during irradiation modifies their dose response. In this paper, the effect of heat released from the exothermal polymerization reaction on the dose response of a number of dosimeters was studied. In addition, we investigated whether heat-generated geometric distortion existed in newly proposed gel dosimeters that contain highly thermoresponsive polymers. Our results suggest that despite a significant internal temperature increase in some gel compositions, their dose responses are not affected when oxygen is well expelled mechanically from the gel mixture. We also report on significant pre-irradiation instability in some recently developed polymer gel dosimeters but that geometric distortions were not observed. Data obtained by a set of small calibration vials are compared to those obtained from larger phantoms, and potential physicochemical causes of deviations between them are identified.

  5. Non-stationary heat transfer in gels applied to biotehnology

    Directory of Open Access Journals (Sweden)

    Pokusaev Boris

    2017-01-01

    Full Text Available Unsteady heat transfer in agarose gels of various concentrations was studied in order to make a breakthrough in the technology of 3-D additive bioprinting. Data on the kinetics of the phase transformation was obtained using spectroscopy as a function of temperature during the formation of agarose hydrogel. The dynamics of aging was investigated for gels of different densities. The time dependence of the structural changes was obtained. Particular attention was paid to the changes in the structure of the gel due to the processes of evaporation of the liquid during the gel formation and during long-term storage. Experiments were performed to determine the dynamics of the temperature fields simultaneously with heat flux measurements during the formation of agarose gels from different initial concentrations. A technique based on experimental data for the computations of the thermophysical coefficients of agarose gels was developed.

  6. Explorative data analysis of two-dimensional electrophoresis gels

    DEFF Research Database (Denmark)

    Schultz, J.; Gottlieb, D.M.; Petersen, Marianne Kjerstine

    2004-01-01

    of gels is presented. First, an approach is demonstrated in which no prior knowledge of the separated proteins is used. Alignment of the gels followed by a simple transformation of data makes it possible to analyze the gels in an automated explorative manner by principal component analysis, to determine......Methods for classification of two-dimensional (2-DE) electrophoresis gels based on multivariate data analysis are demonstrated. Two-dimensional gels of ten wheat varieties are analyzed and it is demonstrated how to classify the wheat varieties in two qualities and a method for initial screening...... if the gels should be further analyzed. A more detailed approach is done by analyzing spot volume lists by principal components analysis and partial least square regression. The use of spot volume data offers a mean to investigate the spot pattern and link the classified protein patterns to distinct spots...

  7. Further developments and applications of layer gel dosimetry

    International Nuclear Information System (INIS)

    Gambarini, G; Carrara, M; Colli, V; Gay, S; Tomatis, S

    2004-01-01

    The method used to perform dosimetry with Fricke-xylenol orange-infused gels in form of layers remains the most reliable method for in-phantom dose profiling and imaging in high fluxes of thermal and epithermal neutrons. Gel-dosimeters in form of layers really give the possibility not only of obtaining spatial dose distributions but also of achieving measurements of each dose contribution in neutron fields. These advantages arise from the layer-geometry thanks to which neutron transport is not sensibly altered, even if the elemental gel composition is changed adding particular isotopes (for example 10 B), as necessary to perform the separation of dose contributions. The gel matrix composition and the experimental procedures, adopted for both dosimeter preparation and analysis, have been already described in previous works. In the present work, the improvements of the method employed for gel analysis, dose imaging and gel applications are illustrated

  8. A simple gel electrophoresis method for separating polyhedral gold nanoparticles

    Science.gov (United States)

    Kim, Suhee; Lee, Hye Jin

    2015-07-01

    In this paper, a simple approach to separate differently shaped and sized polyhedral gold nanoparticles (NPs) within colloidal solutions via gel electrophoresis is described. Gel running parameters for separating efficiently gold NPs including gel composition, added surfactant types and applied voltage were investigated. The plasmonic properties and physical structure of the separated NPs extracted from the gel matrix were then investigated using transmission electron microscopy (TEM) and UV-vis spectrophotometry respectively. Data analysis revealed that gel electrophoresis conditions of a 1.5 % agarose gel with 0.1 % sodium dodecyl sulfate (SDS) surfactant under an applied voltage of 100 V resulted in the selective isolation of ~ 50 nm polyhedral shaped gold nanoparticles. Further efforts are underway to apply the method to purify biomolecule-conjugated polyhedral Au NPs that can be readily used for NP-enhanced biosensing platforms.

  9. Comparison effect of azithromycin gel 2% with clindamycin gel 1% in patients with acne.

    Science.gov (United States)

    Mokhtari, Fatemeh; Faghihi, Gita; Basiri, Akram; Farhadi, Sadaf; Nilforoushzadeh, Mohammadali; Behfar, Shadi

    2016-01-01

    Acne vulgaris is the most common skin disease. Local and systemic antimicrobial drugs are used for its treatment. But increasing resistance of Propionibacterium acnes to antibiotics has been reported. In a double-blind clinical trial, 40 patients with mild to moderate acne vulgaris were recruited. one side of the face was treated with Clindamycin Gel 1% and the other side with Azithromycin Topical Gel 2% BID for 8 weeks and then they were assessed. Average age was 21. 8 ± 7 years. 82.5% of them were female. Average number of papules, pustules and comedones was similarly reduced in both groups and, no significant difference was observed between the two groups (P > 0.05, repeated measurs ANOVA). The mean indexes of ASI and TLC also significantly decreased during treatment in both groups, no significant difference was observed between the two groups. (P > 0.05, repeated measurs ANOVA). Also, impact of both drugs on papules and pustules was 2-3 times greater than the effect on comedones. Average satisfaction score was not significant between the two groups (P = 0.6, repeated measurs ANOVA). finally, frequency distribution of complications was not significant between the two groups (P > 0.05, Fisher Exact test). Azithromycin gel has medical impact at least similar to Clindamycin Gel in treatment of mild to moderate acne vulgaris, and it may be consider as suitable drug for resistant acne to conventional topical therapy.

  10. Preparation of zirconium molybdate gel for 99mTc gel generator

    International Nuclear Information System (INIS)

    Aliludin, Z.; Ohkubo, Masatake; Kushita, Kouhei

    1988-09-01

    Zirconium molybdate gel has excellent characteristics for use as column matrix material of 99m Tc generators. In this work, zirconium molybdate gels were prepared under different conditions; pH's of molybdate solutions from 2.5 to 7.0, Mo:Zr molar ratios from 0.7:1.0 to 1.3:1.0, drying temperatures from an ambient temperature to 200 deg C, and drying times from 1 h to 25 h. Contents of water, nitrate, molybdenum and zirconium were measured to examine the fundamental conditions in gel preparation. The Mo:Zr molar ratio was 1.0:1.0 for the most of gels obtained. A 99m Tc generator was prepared with an amorphous zirconium molybdate containing a tracer level of 99 Mo as column matrix material. Elution of 99m Tc was rapid and the average elution efficiency was 90 % for 6 ml elutions. Contents of radionuclidic impurities, Zr and Mo in the eluates, were low enough to meet the pharmacopoeia requirements for human use. (author)

  11. Gel stabilization in chelate sol-gel preparation of Bi-2223 superconductors

    Czech Academy of Sciences Publication Activity Database

    Rubešová, K.; Jakeš, V.; Hlásek, T.; Vašek, Petr; Matějka, P.

    2012-01-01

    Roč. 73, č. 3 (2012), s. 448-453 ISSN 0022-3697 Institutional research plan: CEZ:AV0Z10100521 Keywords : superconductors * sol-gel growth * infrared spectroscopy * thermogravimetric analysis (TGA) * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.527, year: 2012

  12. Preventative Maintenance.

    Science.gov (United States)

    Migliorino, James

    Boards of education must be convinced that spending money up front for preventive maintenance will, in the long run, save districts' tax dollars. A good program of preventive maintenance can minimize disruption of service; reduce repair costs, energy consumption, and overtime; improve labor productivity and system equipment reliability; handle…

  13. Abstracts of International Conference on Sol-Gel Materials' 04

    International Nuclear Information System (INIS)

    2004-01-01

    International Conference on Sol-Gel Materials '04 was an important forum for discussion on problems related to sol-gel processes applied for preparation materials with special physical properties and assignment. The application of sol-gel materials as phosphors, surface coatings, sensors, waveguides, medical implants, joints etc. has been presented. Preparation conditions, methods of physical characterization as well as optimal chemical composition of such materials have been also discussed in detail

  14. Formulation and evaluation of antipsoriatic gel using natural excipients

    OpenAIRE

    Raghupatruni Jhansi Laxmi; R. Karthikeyan; P. Srinivasa Babu; R.V.V. Narendra Babu

    2013-01-01

    Objective: To develop topical gel formulations of Psoralen using natural excipients to minimize the side effects of synthetic drugs. Methods: The Psoralen gel formulations were prepared using different natural gums and polymers. The physicochemical compatibility between Psoralen and other excipients was confirmed by using Fourier transform infrared spectroscopy. All prepared gel formulations were evaluated for drug content uniformity, viscosity, pH, and stability. The release of psoralen f...

  15. Current and future possibilities of sol-gel process

    International Nuclear Information System (INIS)

    Sakka, Sumio

    2004-01-01

    The sol-gel method is characterized by the low temperature processing. Since this method starts from solutions, the product is essentially nanomaterials. So far, various kinds of microstructures, including dense, porous, hybrid, amorphous and crystalline microstructures have been realized. Accordingly, sol-gel materials cover a wide range of functions, such as optical, electronic, mechanical, chemical and bio-functions. Future perspectives of the sol-gel method are described in the article. (author)

  16. Zirconium molybdate gel as a generator for technetium-99m

    International Nuclear Information System (INIS)

    Evans, J.V.; Shying, M.E.

    1984-12-01

    A new sup(99m)Tc generator based on zirconium molybdate gel is described. Essentially the gel is a cation ion exchanger which permits the elution of the pertechnetate ion. The high molybdenum content of this gel, its stability under self-irradiation, and the absence of organic materials during preparation provide a generator concept that eliminates high processing costs, active waste storage costs and stability problems in other types of generator

  17. Capillary gel electrophoresis for rapid, high resolution DNA sequencing.

    OpenAIRE

    Swerdlow, H; Gesteland, R

    1990-01-01

    Capillary gel electrophoresis has been demonstrated for the separation and detection of DNA sequencing samples. Enzymatic dideoxy nucleotide chain termination was employed, using fluorescently tagged oligonucleotide primers and laser based on-column detection (limit of detection is 6,000 molecules per peak). Capillary gel separations were shown to be three times faster, with better resolution (2.4 x), and higher separation efficiency (5.4 x) than a conventional automated slab gel DNA sequenci...

  18. Pelepasan Ibuprofen Dari Gel Karbomer 940 Kokristal Ibuprofen-Nikotinamida

    OpenAIRE

    Agustin, Rini; Sari, Novica; Zaini, Erizal

    2014-01-01

    Salah satu metode untuk meningkatkan kelarutan adalah co-kristalisasi. Ibuprofen dapat digunakan dalam aplikasi topikal untuk rheumatoid arthrisi, sehingga telah dilakukan sebuah studi tentang formulasi dan pelepasan kokristal ibuprofen-nikotinamida dari gel karbomer 940. Kokristal diperoleh dari metode penguapan pelarut dengan komposisi equimol (1:1). Gel terdiri dari dua formula dengan jumlah ibuprofen yang sama (5%). Formula pertama adalah gel kokristal ibuprofen-nicotinamida dan Formula d...

  19. Sol-gel precursors and products thereof

    Science.gov (United States)

    Warren, Scott C.; DiSalvo, Jr., Francis J.; Weisner, Ulrich B.

    2017-02-14

    The present invention provides a generalizable single-source sol-gel precursor capable of introducing a wide range of functionalities to metal oxides such as silica. The sol-gel precursor facilitates a one-molecule, one-step approach to the synthesis of metal-silica hybrids with combinations of biological, catalytic, magnetic, and optical functionalities. The single-source precursor also provides a flexible route for simultaneously incorporating functional species of many different types. The ligands employed for functionalizing the metal oxides are derived from a library of amino acids, hydroxy acids, or peptides and a silicon alkoxide, allowing many biological functionalities to be built into silica hybrids. The ligands can coordinate with a wide range of metals via a carboxylic acid, thereby allowing direct incorporation of inorganic functionalities from across the periodic table. Using the single-source precursor a wide range of functionalized nanostructures such as monolith structures, mesostructures, multiple metal gradient mesostructures and Stober-type nanoparticles can be synthesized. ##STR00001##

  20. Supramolecular gel electrophoresis of large DNA fragments.

    Science.gov (United States)

    Tazawa, Shohei; Kobayashi, Kazuhiro; Oyoshi, Takanori; Yamanaka, Masamichi

    2017-10-01

    Pulsed-field gel electrophoresis is a frequent technique used to separate exceptionally large DNA fragments. In a typical continuous field electrophoresis, it is challenging to separate DNA fragments larger than 20 kbp because they migrate at a comparable rate. To overcome this challenge, it is necessary to develop a novel matrix for the electrophoresis. Here, we describe the electrophoresis of large DNA fragments up to 166 kbp using a supramolecular gel matrix and a typical continuous field electrophoresis system. C 3 -symmetric tris-urea self-assembled into a supramolecular hydrogel in tris-boric acid-EDTA buffer, a typical buffer for DNA electrophoresis, and the supramolecular hydrogel was used as a matrix for electrophoresis to separate large DNA fragments. Three types of DNA marker, the λ-Hind III digest (2 to 23 kbp), Lambda DNA-Mono Cut Mix (10 to 49 kbp), and Marker 7 GT (10 to 165 kbp), were analyzed in this study. Large DNA fragments of greater than 100 kbp showed distinct mobility using a typical continuous field electrophoresis system. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. ANTIPLAQUE AND ANTIGINGIVITIS EFFECTS OF A GEL CONTAINING PUNICA GRANATUM LINN EXTRACT. A DOUBLE-BLIND CLINICAL STUDY IN HUMANS

    Science.gov (United States)

    Salgado, Alexandre Daher Yunes; Maia, Juliana Lemos; Pereira, Sérgio Luís da Silva; de Lemos, Telma Leda Gomes; Mota, Olívia Morais de Lima

    2006-01-01

    Objectives: The antiplaque and antigingivitis effects of a gel containing 10% Punica granatum Linn extract were evaluated using a 21-day partial-mouth experimental model of gingivitis. Methods: 23 volunteers participated in this cross-over, doubleblind study, carried out in 2 phases of 21 days each. For each period of the experiment, an acrylic toothshield was made for each volunteer to carry the test or placebo gel as well as to avoid brushing of the 4 experimental teeth (posterior teeth in the lower left quadrant). The subjects were randomly assigned to use either the placebo gel (control group) or the test gel (experimental group) and were instructed to brush the remaining teeth normally 3 times a day. On days 0 and 21, the visible plaque index (VPI) and gingival bleeding index (GBI) were recorded. Results: The results did not show statistically significant difference between control and experimental groups for either of the indices (VPI and GBI). Conclusion: The gel containing 10% Punica granatum Linn extract was not efficient in preventing supragingival dental plaque formation and gingivitis. PMID:19089066

  2. Aging and nonlinear rheology of thermoreversible colloidal gels

    Science.gov (United States)

    Wagner, Norman; Gordon, Melissa; Kloxin, Christopher

    Colloidal dispersions are found in a wide variety of consumer products such as paint, food and pharmaceuticals. We investigate gel formation and aging in a thermoreverible gel consisting of octadecyl-coated silica nanoparticles suspended in n-tetradecane. In this system, the octadecyl brush can undergo a phase change allowing the attractions between particles to be tuned by temperature (1,2). By probing the system with steady shear and large amplitude oscillatory shear, we have studied the effect of thermal history and shear history on gel formation and gel mechanical properties during aging. Gels were formed by approaching a common temperature from above and below to determine a reference state from which creep tests were conducted. Creep ringing was observed as expected for the viscoelastic gel. The rheological aging is interpreted in terms of the gel microstructure formed with differing thermal and shear histories to determine how processing affects structure. Recently proposed scaling laws for the rheology and structure under flow are explored within the context of gel aging (3). Through rheological and microstructural measurements, we will further the understanding of gel formation and aging in this model system which may be applied to processing conditions in an industrial setting.

  3. Disc electrophoresis and related techniques of polyacrylamide gel electrophoresis

    National Research Council Canada - National Science Library

    Maurer, H. R

    1971-01-01

    ..., enzymes, antingens and radioactively labelled materials, and detailed treatments of micro disc electrophoresis, preparative polyacrylamide gel electrophoresis and many other techniques for special problems...

  4. Radiation effect on polystyrene deposited and grafted on silica gel

    International Nuclear Information System (INIS)

    Kusama, Y.; Udagawa, A.; Takehisa, M.

    1978-01-01

    The effect of radiation on polystyrene was studied in the presence and absence of silica gel by molecular weight measurement with gel permeation chromatography (GPC). Polystyrene crosslinked under vacuum in the absence of silica gel, but it either crosslinked or degraded by radiation, depending on the molecular weight of the polymer in the presence of silica gel. part of the deposited polymer bonded to silica gel by radiation; the G value for graft-chain formation is in the range of 0.01 to 0.1. Irradiation of polystyrene grafted on silica gel resulted in degradation of the graft chain because of the transfer of energy from silica gel. The G value for main chain scission was about 2 when graft polymer was irradiated in the absence of homopolymer. The degradation of graft polymer was suppressed when the polymer was irradiated in the presence of homopolymer, and the amount of unextractable polymer from silica gel increased with increasing irradiation. This adds evidence to the estimation that an increase in grafting percent coupled with a slight decrease in molecular weight at a later stage of radiation-induced polymerization of styrene adsorbed on slica gel is due to a secondary effect of radiation on the polymer

  5. A method for easily customizable gradient gel electrophoresis.

    Science.gov (United States)

    Miller, Andrew J; Roman, Brandon; Norstrom, Eric

    2016-09-15

    Gradient polyacrylamide gel electrophoresis is a powerful tool for the resolution of polypeptides by relative mobility. Here, we present a simplified method for generating polyacrylamide gradient gels for routine analysis without the need for specialized mixing equipment. The method allows for easily customizable gradients which can be optimized for specific polypeptide resolution requirements. Moreover, the method eliminates the possibility of buffer cross contamination in mixing equipment, and the time and resources saved with this method in place of traditional gradient mixing, or the purchase of pre-cast gels, are noteworthy given the frequency with which many labs use gradient gel SDS-PAGE. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Optimized Benzalkonium Chloride Gel: A Potential Vaginal Microbicides

    Institute of Scientific and Technical Information of China (English)

    Xun-cheng DING; Wei-hua LI; Jie-fei LI; Qiang-yi WANG

    2007-01-01

    Objective To develop an optimized BZK gel with good pharmaceutical effect and less toxicity to vaginal mucosa.Methods Four methods as below were used to research the spermicidal activity of BZK gel: 1)in vitro spermicidal test; 2) in vivo spermicidal test in rabbits; 3) anti-fertility test in rabbits; 4)contraceptive test in rabbits. Mucosal irritation test was used in rats to evaluate the safety of optimized BZK gel. Microbiological assessments were used to research anti-STI pathogens (including treponema pallidum, neisseria gonorrhoeae, trichomona vaginalis, candida albicans,ureaplama urealyticum, herpes simplex virus type-2, chlamydiae trachomatis) effect of optimized BZK gel.Results In vitro spermicidal test, EC50 of BZK gel was 0.029 mg/ml, a little higher than that of N-9 (0.019 mg/ml). The MIC of BZK gel was 0.25 mg/ml, similar to that of N-9 (0.20 mg/ml).The vaginal mucosal irritation test in rats showed that 0.429% BZK gel showed only minimal vaginal irritation, and did not damage the vaginal epithelium or cause local inflammation in rats. Microbiological assessments showed that optimized BZK gel could inhibit or inactivate common STI pathogens even after 3-fold or 5-fold dilution.Conclusion Optimized BZK gel was an effective microbicides.

  7. Silica scintillating materials prepared by sol-gel methods

    International Nuclear Information System (INIS)

    Werst, D.W.; Sauer, M.C. Jr.; Cromack, K.R.; Lin, Y.; Tartakovsky, E.A.; Trifunac, A.D.

    1993-01-01

    Silica was investigated as a rad-hard alternative to organic polymer hosts for organic scintillators. Silica sol-gels were prepared by hydrolysis of tetramethoxysilane in alcohol solutions. organic dyes were incorporated into the gels by dissolving in methanol at the sol stage of gel formation. The silica sol-gel matrix is very rad-hard. The radiation stability of silica scintillators prepared by this method is dye-limited. Transient radioluminescence was measured following excitation with 30 ps pulses of 20 MeV electrons

  8. Sol-gel preparation of uranium oxide spheres

    International Nuclear Information System (INIS)

    Dolezal, J.; Urbanek, V.

    1978-01-01

    Information is presented on problems of preparing nuclear fuel by the sol-gel method. Basic data on different process types are given. A more detailed description of the method of preparation of spherical particles of uranium oxide gel developed and used at the Nuclear Research Institute at Rez is given. Advantages and disadvantages of sol-gel materials are discussed in comparison with fuel materials prepared by classical precipitation methods. The feasibility of the sol-gel methods for preparing other materials is shortly mentioned and their application outlined. (author)

  9. PCR amplification on microarrays of gel immobilized oligonucleotides

    Science.gov (United States)

    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.

  10. High Impulse Nanoparticulate-Based Gel Propellants, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposed Small Business Innovative Research (SBIR) Phase I addresses the development of advanced gel propellants and determination of their suitability for...

  11. Release study of diclofenac from new carbomer gels.

    Science.gov (United States)

    Bregni, Carlos; Chiappetta, Diego; Faiden, Natalia; Carlucci, Adriana; García, Roberto; Pasquali, Ricardoc

    2008-01-01

    Carbopol gels were prepared using a traditional polymer with mucoadhesive properties (974P). A new Carbomer derivative Ultrez 21 was also evaluated. Mineral oil, as occlusive ingredient, glycerol as humectant and ethanol were included in all the compositions. The feasibility of preparing these formulations with or without a bioadhesive polymer (Polycarbophil AA-1) and a second oil phase with enhancer activity (Miglyol 840) was evaluated. Further characterization including physical stability during a year was carried out. In vitro release behaviour of diclofenac sodium in Franz diffusion cell was evaluated with some selected formulations using an ethanol-water (50% w/w) solution as receptor medium. Addition of Polycarbophil AA-1 increased formulation viscosity and decreased drug release. These types of topical dosage forms could give sustained delivery of drug onto the skin, could tolerate the incorporation of an enhancer, a humectant and an occlusive phase, so they are interesting promises to improve skin absorption of nonsteroidal anti-inflammatory drugs and to prevent side effects associated.

  12. Processed Aloe vera Gel Ameliorates Cyclophosphamide-Induced Immunotoxicity

    Directory of Open Access Journals (Sweden)

    Sun-A Im

    2014-10-01

    Full Text Available The effects of processed Aloe vera gel (PAG on cyclophosphamide (CP-induced immunotoxicity were examined in mice. Intraperitoneal injection of CP significantly reduced the total number of lymphocytes and erythrocytes in the blood. Oral administration of PAG quickly restored CP-induced lymphopenia and erythropenia in a dose-dependent manner. The reversal of CP-induced hematotoxicity by PAG was mediated by the functional preservation of Peyer’s patch cells. Peyer’s patch cells isolated from CP-treated mice, which were administered PAG, produced higher levels of T helper 1 cytokines and colony-stimulating factors (CSF in response to concanavalin A stimulation as compared with those isolated from CP-treated control mice. PAG-derived polysaccharides directly activated Peyer’s patch cells isolated from normal mice to produce cytokines including interleukin (IL-6, IL-12, interferon-γ, granulocyte-CSF, and granulocyte-macrophage-CSF. The cytokines produced by polysaccharide-stimulated Peyer’s patch cells had potent proliferation-inducing activity on mouse bone marrow cells. In addition, oral administration of PAG restored IgA secretion in the intestine after CP treatment. These results indicated that PAG could be an effective immunomodulator and that it could prevent CP-induced immunotoxic side effects.

  13. Slip-dependent weakening on shallow plate boundary fault in the Japan subduction zone: shallow coseismic slip facilitated by foreshock afterslip

    Science.gov (United States)

    Ito, Yoshi; Ikari, Matt; Ujiie, Kohtaro; Kopf, Achim

    2017-04-01

    Understanding of role of slow earthquakes as they relate to the occurrence of both megathrust earthquakes and tsunami earthquakes is necessary to mitigate these disasters in the near future. Laboratory shearing experiments is one of important approach to evaluate these relationships. Here, we use powdered gouge samples from JFAST (IODP Expedition 343) Hole C0019E, core sample 17R-1, which is the plate boundary fault zone in the Japan Trench subduction zone. In this region, both large coseismic slip during the 2011 Tohoku-Oki earthquake as well as discrete slow slip events (SSE) have occurred. Experiments were conducted in a single-direct shear apparatus under normal stress of 16 MPa, with total shear displacements of up to 16 mm. We evaluate the slip-dependence of friction by extracting the velocity-dependent friction parameters a, b, and Dc , and also measure the rate of change in friction coefficient with shear displacement as the slip-dependence of friction. We report that in friction experiments using the Tohoku fault zone samples, an increase in sliding velocity exceeding that of earthquake afterslip can induce a change from steady-state frictional strength or slip hardening friction to slip-weakening frictional behavior. Our results show that the slip weakening is observed when the slip velocity exceeds 3.7 × 10-6 m/s during our experiments, while steady-state frictional strength or slip hardening is observed below 1 × 10-6 m/s. In the Japan Trench region, two slow events prior to the mainshock were observed in the mainshock area with a coseismic slip exceeding 30 m . One event is an episodic SSE with a slip velocity of 0.1 × 10-6 , and the other is afterslip after the largest Tohoku earthquake foreshock with a slip velocity exceeding 2 × 10-6 m/s. Our experiments show that slip-weakening friction should be expected at the afterslip rate, suggesting that the afterslip may have facilitated the large coseismic slip during the mainshock on the plate boundary

  14. Fluvial incision by the Qingyijiang River on the northern fringe of Mt. Huangshan, eastern China: Responses to weakening of the East Asian summer monsoon

    Science.gov (United States)

    Hu, Chunsheng; Liu, Shaochen; Hu, Chenqi; Xu, Guanglai; Zhou, Yingqiu

    2017-12-01

    This paper focuses on climatic and tectonic controls to determine their relative importance to the Quaternary fluvial incision by the Qingyijiang River, eastern China. The Qingyijiang, which is one of longest tributaries of the lower Yangtze River, drains the northern piedmont of Mt. Huangshan. A field survey focused on three natural sections of the Qingyijiang in the Jingxian basin, where a well-preserved sequence of one alluvial platform (P) and three fluvial terraces (T3, T2, and T1) is presented. The heights of the platform and the terraces above river level are 65, 40, 20, and 7 m respectively. In this study, electron spin resonance (ESR), optical stimulated luminescence (OSL), and palaeomagnetic dating were applied to reconstruct the fluvial incision history of the Qingyijiang and evaluate the possible influence of tectonic uplift and/or climate change on the fluvial incision. The main results show that (1) the ages of P, T3, T2, and T1 were determined to be ∼ 1300, ∼ 900, ∼ 600, and ∼ 1.5 ka respectively, corresponding to four incision events in the Qingyijiang; (2) the East Asian summer monsoon (EASM) experienced four significant weakening events at 1300, 900, 600, and ∼ 1.5 ka, according to previous research. Correspondingly, we propose that four significant increased periods of regional precipitation occurred at 1300, 900, 600, and ∼ 1.5 ka in the study area because of the negative correlation between the intensity of the EASM and regional precipitation from 1960 to 2012; and (3) fluvial incision by the Qingyijiang arose as a result of the weakening of the EASM in combination with tectonic uplift, determined by matching fluvial incision history of the Qingyijiang with tectonic movement and EASM change. In addition, the weakening of the EASM climatically triggered fluvial incision by the Qingyijiang. This study supports the conclusion that major fluvial incision has been climatically triggered; however, it also suggests that the mechanism of

  15. Protective Effect of Tea Polyphenol Ophthalmic Gel on Lens Epithelial Cells in Rabbits with Silicone Oil Tamponade after Vitrectomy

    Directory of Open Access Journals (Sweden)

    Xianzhen Ma

    2014-01-01

    Full Text Available Purpose. The aim of this study was to investigate the effect of tea polyphenols (TP ophthalmic gel on lens epithelial cells (LECs in rabbits with silicone oil tamponade after vitrectomy. Methods. In this study, unilateral vitrectomy with silicone oil tamponade was performed using 2-month-old New Zealand white rabbits (n = 72; meanwhile, age-matched nonoperated rabbits (n = 18 were used as controls. The TP ophthalmic gel was administered topically in the surgical eyes till they were sacrificed. On days 45 and 90 after operation, the levels of reactive oxygen species (ROS, mitochondrial membrane potential (ΔΨm, and apoptosis of LECs were analyzed, respectively. Meanwhile, caspase-3 mRNA and protein levels were also determined. Results. The results indicate that the levels of ROS and apoptosis were elevated for LECs in rabbits after operation, whereas ΔΨm was decreased. Caspase-3 was apparently increased at both mRNA and protein levels. Treatment of TP ophthalmic gel could reduce the generation of ROS, maintain ΔΨm, inhibit the overexpression of caspase-3, and thus decrease the apoptosis of LECs of rabbits after operation. Conclusions. TP ophthalmic gel can efficiently inhibit caspase-3 overexpression, reduce the apoptosis of LECs, and prevent LECs from damage. Our result provides a new approach to prevent the development of complicated cataract after vitrectomy.

  16. Preventive analgesia

    DEFF Research Database (Denmark)

    Dahl, Jørgen B; Kehlet, Henrik

    2011-01-01

    This paper will discuss the concepts of pre-emptive and preventive analgesia in acute and persistent postsurgical pain, based on the most recent experimental and clinical literature, with a special focus on injury-induced central sensitization and the development from acute to chronic pain. Recent...... of preventive analgesia for persistent postoperative pain are promising. However, clinicians must be aware of the demands for improved design of their clinical studies in order to get more conclusive answers regarding the different avenues for intervention. Summary: The concept of preventive analgesia is still...

  17. Gel-eletroforese no diagnóstico da varíola Gel-electrophoresis in the smallpox diagnosis

    Directory of Open Access Journals (Sweden)

    Julio A. Mesquita

    1972-01-01

    Full Text Available O emprego de gel-eletroforese no diagnóstico da varíola, demonstrou ser ao menos trinta vezes (30X mais sensível que o teste de agar-gel, nas condições descritas (tabela I. Doze (12 espécimes, cujos testes convencionais de inoculação em ovos embrionados e de agar-gel resultaram positivos, foram testados em suas diluições originais congeladas por mais de um ano, sendo seis deles revelados por gel-eletroforese enquanto nenhum o foi por agar-gel (tabela II. Trinta e três (33 amostras isoladas no laboratório, foram testadas com material colhido de membrana cório-alantóica da primeira inoculação para o diagnóstico, conservado em glicerina 50%, resultando 15 positivas em gel-eletroforese e apenas 3 em agar-gel (tabela II. Os últimos 60 espécimes recebidos para diagnóstico, através a Campanha de Erradicação da Varíola, também resultaram negativos em gel-eletroforese, que não mostrou falsos-positivos nas condições descritas.The test of gel-electrophoresis applied to the pox virus group showed to be at least thirth times (30X more sensitive than agar-gel test on the described conditions (Table I. Twelve specimens, which were positives form Smallpox in the conventional tests of egg inoculation and agar-gel difusion test, have been screened in their original dilutions frozen for more than 1 year and six of them were still detectable by gel-eletrophoresis, while by agar-gel test any of them was positive (Table II. Thirty three Smallpox isolates have been tested with material from first egg inoculation (chorioallantoic membranes which have been stored in glycerin 50%, at - 15ºC. Fifteen of them were still positive by gel-electrophoresis and only 3 by agar-gel (Table II. The last 60 specimens received for diagnosis from Smallpox Erradication Campaign (CEV, were negatives by both tests. The gel-electrophoresis, did not show false-positives on described conditions.

  18. Influence of Uranium and Polivinyl Alcohol Concentration in the Feed of Sol Gel Process on the Gel Spherical Product

    International Nuclear Information System (INIS)

    Indra Suryawan; Endang Susiantini

    2007-01-01

    The gel particles have been made at various uranium and polyvinyl alcohol concentration in the sol gel process. The variables of uranium concentration were 0.3; 0.5; 0.7; 0.9; 1.1; 1.3; 1.5; 1.7; 1.9 and 2.1 M The variables of polyvinyl alcohol concentration were 0.3; 0.6; 0.9; 1.2; 1.5; 1.8; 2.1 and 2.4 M After drying the sol gel process products were heated at 300, 500 and 750°C during 4 hours. The gel particles were characterized using an optic microscope to know the shape and condition morphology of gel. From experimental result using uranium concentration of 0.3 until 2.1 M and polyvinyl alcohol of 1.8 until 2.4 M spherical and gel was formed elastic, after heating at 750°C it was unbreakable. At the concentration of polyvinyl alcohol from 0.3 to 0.5 M, the gel product was soft and broken after being dried. At the concentration of polyvinyl alcohol from 0.6 to 0.8 M, the dried gel product was not perfect. At the concentration of polyvinyl alcohol from 0.9 to 1.7 M, the gel product of gelation process was spherical and it was broken after being heated up to 300°C. (author)

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

    Science.gov (United States)

    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.

  20. Prevention: Exercise

    Medline Plus

    Full Text Available ... Tips for a Healthy Back Smoking Weight Patient Safety Exercise Strengthening Strengthen Your Core! Stretching/Flexibility Aerobic ... Strength Training for the Elderly Other Back Pack Safety Pregnancy and Back Pain Preventing Osteoporosis Back Pain ...

  1. Preventing Rejection

    Science.gov (United States)

    ... After the transplant Preventing rejection Post-transplant medications Types of immunosuppressants Switching immunosuppressants Side effects Other medications Generic and brand name drugs Post-transplant tests Infections and immunity Lifestyle changes Health concerns Back to work or ...

  2. Prevent Cyberbullying

    Science.gov (United States)

    ... Tips for Teachers Report Cyberbullying Print Share Prevent Cyberbullying Be Aware of What Your Kids are Doing ... Signs a Child is Being Cyberbullied or is Cyberbullying Others Many of the warning signs that cyberbullying ...

  3. Preventing Suicide

    Science.gov (United States)

    ... protective factors listed below: Skills in problem solving, conflict resolution, and nonviolent ways of handling disputes Effective ... 2017 Page last updated: August 9, 2017 Content source: National Center for Injury Prevention and Control, Division ...

  4. Prevention: Exercise

    Medline Plus

    Full Text Available ... A SPECIALIST Prevention Strengthening Exercise Committee Exercise Committee Core Strengthening Many popular forms of exercise focus on ... acute pain, you should stop doing it. Transverse Core Strengthening This strengthens the muscles that cross from ...

  5. Prevention: Exercise

    Medline Plus

    Full Text Available ... Training for the Elderly Other Back Pack Safety Pregnancy and Back Pain Preventing Osteoporosis Back Pain Basics ... increases your back pain after five repetitions, or causes acute pain, you should stop doing it. Transverse ...

  6. Preventing accidents

    Science.gov (United States)

    2005-08-01

    As the most effective strategy for improving safety is to prevent accidents from occurring at all, the Volpe Center applies a broad range of research techniques and capabilities to determine causes and consequences of accidents and to identify, asses...

  7. Prevention: Exercise

    Medline Plus

    Full Text Available ... 10 Tips for a Healthy Back Smoking Weight Patient Safety Exercise Strengthening Strengthen Your Core! Stretching/Flexibility ... Pain Preventing Osteoporosis Back Pain Basics Book RESOURCES Patient Information Feature Articles Patient Q&A Success Stories ...

  8. Prevention: Exercise

    Medline Plus

    Full Text Available ... Preventing Osteoporosis Back Pain Basics Book RESOURCES Patient Information Feature Articles Patient Q&A Success Stories Definitions Anatomy of the Spine Definitions A-Z Spine Specialists Videos 9 ...

  9. HIV Prevention

    Centers for Disease Control (CDC) Podcasts

    2012-02-01

    Dr. Kevin Fenton, Director of CDC’s National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, talks about steps people can take to protect their health from HIV.  Created: 2/1/2012 by National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP).   Date Released: 2/1/2012.

  10. Enhanced 1,3-propanediol production in Klebsiella pneumoniae by a combined strategy of strengthening the TCA cycle and weakening the glucose effect.

    Science.gov (United States)

    Lu, X Y; Ren, S L; Lu, J Z; Zong, H; Song, J; Zhuge, B

    2018-03-01

    This study aimed to strengthen the reducing equivalent generation in Klebsiella pneumoniae for improving 1,3-propanediol (PDO) production. Disruption of the arcA gene activated the transcription levels of the TCA cycle genes and thus increased the NADH/NAD + ratio by 54·2%, leading to the improved PDO titre and yield per cell from 16·1 g l -1 and 4·0 g gDCW -1 to 18·8 g l -1 and 6·4 g gDCW -1 respectively. Further ldhA gene deletion eliminated lactate accumulation and promoted the PDO titre to 19·9 g l -1 . Finally, the glucose effect was weakened by deleting the crr gene to enhance the co-utilization of glucose and glycerol, resulting in the increased PDO production to 23·8 g l -1 with the glycerol conversion rate of 59·5%. The PDO titre in bioreactor was promoted from 61·2 to 78·1 g l -1 . Deletions of the arcA and the crr genes showed positive effects on the TCA cycle activity and the co-utilization of glucose and glycerol, leading to the strengthened reducing equivalent generation and the improved PDO titre by 47·8% in shaker. The PDO titre in the bioreactor was enhanced to 78·1 g l -1 . This study provided novel information on generating reducing equivalent for the PDO biosynthesis by strengthening the TCA cycle and weakening the glucose effect in K. pneumoniae. © 2018 The Society for Applied Microbiology.

  11. Chemical controls on fault behavior: weakening of serpentinite sheared against quartz-bearing rocks and its significance for fault creep in the San Andreas system

    Science.gov (United States)

    Moore, Diane E.; Lockner, David A.

    2013-01-01

    The serpentinized ultramafic rocks found in many plate-tectonic settings commonly are juxtaposed against crustal rocks along faults, and the chemical contrast between the rock types potentially could influence the mechanical behavior of such faults. To investigate this possibility, we conducted triaxial experiments under hydrothermal conditions (200-350°C), shearing serpentinite gouge between forcing blocks of granite or quartzite. In an ultramafic chemical environment, the coefficient of friction, µ, of lizardite and antigorite serpentinite is 0.5-0.6, and µ increases with increasing temperature over the tested range. However, when either lizardite or antigorite serpentinite is sheared against granite or quartzite, strength is reduced to µ ~ 0.3, with the greatest strength reductions at the highest temperatures (temperature weakening) and slowest shearing rates (velocity strengthening). The weakening is attributed to a solution-transfer process that is promoted by the enhanced solubility of serpentine in pore fluids whose chemistry has been modified by interaction with the quartzose wall rocks. The operation of this process will promote aseismic slip (creep) along serpentinite-bearing crustal faults at otherwise seismogenic depths. During short-term experiments serpentine minerals reprecipitate in low-stress areas, whereas in longer experiments new Mg-rich phyllosilicates crystallize in response to metasomatic exchanges across the serpentinite-crustal rock contact. Long-term shear of serpentinite against crustal rocks will cause the metasomatic mineral assemblages, which may include extremely weak minerals such as saponite or talc, to play an increasingly important role in the mechanical behavior of the fault. Our results may explain the distribution of creep on faults in the San Andreas system.

  12. Active nematic gels as active relaxing solids

    Science.gov (United States)

    Turzi, Stefano S.

    2017-11-01

    I propose a continuum theory for active nematic gels, defined as fluids or suspensions of orientable rodlike objects endowed with active dynamics, that is based on symmetry arguments and compatibility with thermodynamics. The starting point is our recent theory that models (passive) nematic liquid crystals as relaxing nematic elastomers. The interplay between viscoelastic response and active dynamics of the microscopic constituents is naturally taken into account. By contrast with standard theories, activity is not introduced as an additional term of the stress tensor, but it is added as an external remodeling force that competes with the passive relaxation dynamics and drags the system out of equilibrium. In a simple one-dimensional channel geometry, we show that the interaction between nonuniform nematic order and activity results in either a spontaneous flow of particles or a self-organization into subchannels flowing in opposite directions.

  13. Novel macroporous amphoteric gels: Preparation and characterization

    Directory of Open Access Journals (Sweden)

    S. Kudaibergenov

    2012-05-01

    Full Text Available Macroporous amphoteric gels based on allylamine, methacrylic acid and acrylamide crosslinked by N,N'-methylenebisacrylamide were synthesized by radical copolymerization of monomers in cryoconditions. The composition of cryogels was determined by combination of potentiometric and conductimetric titrations. The morphology of cryogels was evaluated by scanning electron microscope (SEM. Cryogels exhibited sponge-like porous structure with pore size ranging from 50 to 200 μm. The values of the isoelectric points (IEPs determined from the swelling experiments arranged between 3.5 and 4.3. The high adsorption-desorption capacity of amphoteric cryogels with respect to mM and trace concentrations of copper, nickel, and cobalt ions was demonstrated. It was shown that the macroporous amphoteric cryogels are able to adsorb up to 99.9% of copper, nickel, and cobalt ions from 10–3 mol•L–1 aqueous solution.

  14. Bucky gel actuator displacement: experiment and model

    International Nuclear Information System (INIS)

    Ghamsari, A K; Zegeye, E; Woldesenbet, E; Jin, Y

    2013-01-01

    Bucky gel actuator (BGA) is a dry electroactive nanocomposite which is driven with a few volts. BGA’s remarkable features make this tri-layered actuator a potential candidate for morphing applications. However, most of these applications would require a better understanding of the effective parameters that influence the BGA displacement. In this study, various sets of experiments were designed to investigate the effect of several parameters on the maximum lateral displacement of BGA. Two input parameters, voltage and frequency, and three material/design parameters, carbon nanotube type, thickness, and weight fraction of constituents were selected. A new thickness ratio term was also introduced to study the role of individual layers on BGA displacement. A model was established to predict BGA maximum displacement based on the effect of these parameters. This model showed good agreement with reported results from the literature. In addition, an important factor in the design of BGA-based devices, lifetime, was investigated. (paper)

  15. Processing hexavalent uranium gels and their properties

    International Nuclear Information System (INIS)

    Landspersky, H.; Benadik, A.; Spitzer, Z.

    1980-01-01

    The properties of xerogels of ammonium polyuranate prepared by various drying procedures were studied. The individual drying procedures affect differently both the chemical structure of the material (its composition) and the physicochemical properties of the final product (specific surface area, porosity). In addition, the physicochemical properties of xerogels depend on the properties of the starting material, i.e., on the type of the initial gel. The physicochemical properties of xerogels, in particular their porosity, are in turn relevant for their subsequent high-temperature processing. The porous structure is essential for thermal treatment. The structure of xerogels obtained by distillation procedures is affected both by the conditions of azeotropic distillation and by the medium employed. By judicious selection of these two variables it is possible to prepare materials with different pore size distributions. (author)

  16. Phyllosilicates and Amorphous Gel in the Nakhlites

    Science.gov (United States)

    Hicks, L. J.; Bridges, J. C.; Gurman, S. J.

    2013-09-01

    Previous studies of the nakhlite martian meteorites have revealed hydrothermal minerals present within the fractures of the olivine minerals and the mesostasis. The olivine fractures of the Lafayette nakhlite reveal variations with initial deposits of siderite on the fracture walls, followed by crystalline phyllosilicates (smectite), and finishing with a rapidly cooled amorphous silicate gel within the central regions of the fractures. The mesostasis fractures of Lafayette also contain a crystalline phyllosilicate (serpentine). The amorphous gel is the most abundant secondary phase within the fractures of the other nakhlites [1, 2]. By studying nine nakhlite samples, including Lafayette, Governador Valadares, Nakhla, Y-000593, Y-000749, Miller-Range 03346, NWA 817, NWA 998, and NWA 5790, our aim is to constrain the identity of the phyllosilicate secondary phase minerals found throughout the nakhlite martian meteorites. This is achieved using methods including Electron Probe Micro-analysis (EPMA); X-ray Absorption Near-Edge Structure (Fe-K XANES) spectroscopy measured using Beamline I-18 at the Diamond Light Source synchrotron; and the use of Transmission Electron Microscopy (TEM) at the University of Leicester for High-Resolution (HR) imaging and Selected Area Electron Diffraction (SAED). BF studying nine nakhlite samples, including Lafayette, Governador Valadares, Nakhla, Y-000593, Y-000749, Miller-Range 03346, NWA 817, NWA 998, and NWA 5790, our aim is to constrain the identity of the phyllosilicate secondary phase minerals found throughout the nakhlite martian meteorites. This is achieved using methods including Electron Probe Micro-analysis (EPMA); X-ray Absorption Near-Edge Structure (Fe-K XANES) spectroscopy measured using Beamline I-18 at the Diamond Light Source synchrotron; and the use of Transmission Electron Microscopy (TEM) at the University of Leicester for High-Resolution (HR) imaging and Selected Area Electron Diffraction (SAED).

  17. Clotrimazole nanoparticle gel for mucosal administration

    Energy Technology Data Exchange (ETDEWEB)

    Esposito, Elisabetta, E-mail: ese@unife.it [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Ravani, Laura [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Contado, Catia [Department of Chemistry, University of Ferrara, Ferrara (Italy); Costenaro, Andrea [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Drechsler, Markus [Macromolecular Chemistry II, University of Bayreuth (Germany); Rossi, Damiano [Department of Biology and Evolution, LT Terra and Acqua Tech UR7, University of Ferrara, Ferrara (Italy); Menegatti, Enea [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Grandini, Alessandro [Department of Biology and Evolution, LT Terra and Acqua Tech UR7, University of Ferrara, Ferrara (Italy); Cortesi, Rita [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy)

    2013-01-01

    In this study a formulation suitable to be applied on oral and/or vaginal mucosa has been developed for the treatment of fungal infections. The aim of the research is a comparison between clotrimazole (CLO) containing semisolid formulations based on monoolein aqueous dispersion (MAD) or nanostructured lipid carrier (NLC). MAD and NLC have been characterized in terms of morphology and dimensional distribution by cryogenic Transmission Electron Microscopy (cryo-TEM) and Photon Correlation Spectroscopy (PCS). CLO was encapsulated with high entrapment efficiency both in MAD and in NLC, according to Sedimentation Field Flow Fractionation (SdFFF) combined with HPLC. CLO recovery in MAD and NLC has been investigated by time. In order to obtain formulations with suitable viscosity for mucosal application, MAD was diluted with a carbomer gel, while NLC was directly viscosized by the addition of poloxamer 407 in the dispersion. The rheological properties of MAD and NLC after viscosizing have been investigated. Franz cell has been employed to study CLO diffusion from the different vehicles, evidencing diffusion rates from MAD and NLC superimposable to that obtained using Canesten{sup Registered-Sign }. An anticandidal activity study demonstrated that both CLO-MAD and CLO-NLC were more active against Candida albicans with respect to the pure drug. Highlights: Black-Right-Pointing-Pointer Comparison between monoolein aqueous dispersion (MAD) and nanostructured lipid carrier (NLC). Black-Right-Pointing-Pointer Clotrimazole (CLO) encapsulated with high entrapment efficiency both in MAD and in NLC. Black-Right-Pointing-Pointer The solid matrix of NLC controls CLO degradation better than MAD. Black-Right-Pointing-Pointer CLO containing MAD and NLC exhibits a higher anticandidal activity than the free drug. Black-Right-Pointing-Pointer Simple production of CLO-NLC based poloxamer gel, suitable for industry scaling up.

  18. Clotrimazole nanoparticle gel for mucosal administration

    International Nuclear Information System (INIS)

    Esposito, Elisabetta; Ravani, Laura; Contado, Catia; Costenaro, Andrea; Drechsler, Markus; Rossi, Damiano; Menegatti, Enea; Grandini, Alessandro; Cortesi, Rita

    2013-01-01

    In this study a formulation suitable to be applied on oral and/or vaginal mucosa has been developed for the treatment of fungal infections. The aim of the research is a comparison between clotrimazole (CLO) containing semisolid formulations based on monoolein aqueous dispersion (MAD) or nanostructured lipid carrier (NLC). MAD and NLC have been characterized in terms of morphology and dimensional distribution by cryogenic Transmission Electron Microscopy (cryo-TEM) and Photon Correlation Spectroscopy (PCS). CLO was encapsulated with high entrapment efficiency both in MAD and in NLC, according to Sedimentation Field Flow Fractionation (SdFFF) combined with HPLC. CLO recovery in MAD and NLC has been investigated by time. In order to obtain formulations with suitable viscosity for mucosal application, MAD was diluted with a carbomer gel, while NLC was directly viscosized by the addition of poloxamer 407 in the dispersion. The rheological properties of MAD and NLC after viscosizing have been investigated. Franz cell has been employed to study CLO diffusion from the different vehicles, evidencing diffusion rates from MAD and NLC superimposable to that obtained using Canesten ® . An anticandidal activity study demonstrated that both CLO-MAD and CLO-NLC were more active against Candida albicans with respect to the pure drug. Highlights: ► Comparison between monoolein aqueous dispersion (MAD) and nanostructured lipid carrier (NLC). ► Clotrimazole (CLO) encapsulated with high entrapment efficiency both in MAD and in NLC. ► The solid matrix of NLC controls CLO degradation better than MAD. ► CLO containing MAD and NLC exhibits a higher anticandidal activity than the free drug. ► Simple production of CLO-NLC based poloxamer gel, suitable for industry scaling up

  19. Deformation and fracture behavior of simulated particle gels

    NARCIS (Netherlands)

    Rzepiela, A.A.

    2003-01-01

    In this PhD project rheological properties of model particle gels are investigated using Brownian Dynamics (BD) simulations. Particle gels are systems of colloidal particles that form weakly bonded percolating networks interpenetrated by a suspending fluid. They are characterized as

  20. Biocatalysis with Sol-Gel Encapsulated Acid Phosphatase

    Science.gov (United States)

    Kulkarni, Suhasini; Tran, Vu; Ho, Maggie K.-M.; Phan, Chieu; Chin, Elizabeth; Wemmer, Zeke; Sommerhalter, Monika

    2010-01-01

    This experiment was performed in an upper-level undergraduate biochemistry laboratory course. Students learned how to immobilize an enzyme in a sol-gel matrix and how to perform and evaluate enzyme-activity measurements. The enzyme acid phosphatase (APase) from wheat germ was encapsulated in sol-gel beads that were prepared from the precursor…

  1. Reversible sol-gel-sol medium for enzymatic optical biosensors

    NARCIS (Netherlands)

    Safaryan, S.; Yakovlev, A.; Pidko, E.A.; Vinogradov, A.; Vinogradov, V.

    2017-01-01

    In this paper we for the first time report a reversible sol-gel-sol approach to obtain optical enzymatic biosensors with improved enzyme stability and good sensitivity by using desktop inkjet printing. The developed technique is based on the bio-inorganic inks allowing for a sol-gel-sol transition

  2. Cost Analysis of Treating Neonatal Hypoglycemia with Dextrose Gel.

    Science.gov (United States)

    Glasgow, Matthew J; Harding, Jane E; Edlin, Richard

    2018-04-03

    To evaluate the costs of using dextrose gel as a primary treatment for neonatal hypoglycemia in the first 48 hours after birth compared with standard care. We used a decision tree to model overall costs, including those specific to hypoglycemia monitoring and treatment and those related to the infant's length of stay in the postnatal ward or neonatal intensive care unit, comparing the use of dextrose gel for treatment of neonatal hypoglycemia with placebo, using data from the Sugar Babies randomized trial. Sensitivity analyses assessed the impact of dextrose gel cost, neonatal intensive care cost, cesarean delivery rate, and costs of glucose monitoring. In the primary analysis, treating neonatal hypoglycemia using dextrose gel had an overall cost of NZ$6863.81 and standard care (placebo) cost NZ$8178.25; a saving of NZ$1314.44 per infant treated. Sensitivity analyses showed that dextrose gel remained cost saving with wide variations in dextrose gel costs, neonatal intensive care unit costs, cesarean delivery rates, and costs of monitoring. Use of buccal dextrose gel reduces hospital costs for management of neonatal hypoglycemia. Because it is also noninvasive, well tolerated, safe, and associated with improved breastfeeding, buccal dextrose gel should be routinely used for initial treatment of neonatal hypoglycemia. Australian New Zealand Clinical Trials Registry: ACTRN12608000623392. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. Fibril Formation from Pea Protein and Sesequent Gel Formation

    NARCIS (Netherlands)

    Munialo, C.D.; Martin, A.H.; Linden, van der E.; Jongh, de H.H.J.

    2014-01-01

    The objective of this study was to characterize fibrillar aggregates made using pea proteins, to assemble formed fibrils into protein-based gels, and to study the rheological behavior of these gels. Micrometer-long fibrillar aggregates were observed after pea protein solutions had been heated for 20

  4. Fibril Formation from Pea Protein and Subsequent Gel Formation

    NARCIS (Netherlands)

    Munialo, XC.D.; Martin, A.H.; Linden, E. van der; Jongh, H.H.J de

    2014-01-01

    The objective of this study was to characterize fibrillar aggregates made using pea proteins, to assemble formed fibrils into protein-based gels, and to study the rheological behavior of these gels. Micrometer-long fibrillar aggregates were observed after pea protein solutions had been heated for 20

  5. The performance of gel technetium-99m generator

    International Nuclear Information System (INIS)

    Liu Yishu

    2004-01-01

    Technetium-99m, as one of the important radionuclides in nuclear medical science, has been widely used for diseases diagnosis in both developed and developing countries for many years. Technetium-99m can be obtained from both fission-type and gel-type Tc-99m generator. Fission-type generator was prepared by Molybdenum-99 separated from fission products of uranium-235 and gel-type was prepared by irradiating nature MoO 3 in reactor, and a series of chemical and physical processes. This paper briefly describes the manufacturing technical process of gel-type Technetium-99 generator, including the preparation of target containing nature MoO 3 , the target irradiation in reactor, gel preparation, gel filtration and drying, dried gel cracking, generator loading and activity calibration of generator. The performances of gel-type Technetium-99m generator, such as elution efficiency, elution profile, the pH, Mo breakthrough, Zirconium content, radiochemical purity, radionuclidic purity, sterility and pyrogencity of eluate, are also expatiated in detail. Comparing with fission-type Technetium-99m generator, the defects of gel-type Technetium-99m generator are enumerated and their overcoming solutions are recommended in this paper. (author)

  6. Development and evaluation of ibuprofen transdermal gel formulations

    African Journals Online (AJOL)

    A commercial ibuprofen gel product (Ibutop®) was used as a reference. Results: The formulations containing 5 % of either menthol or glycerol as permeation enhancers gave drug release patterns comparable to that of the reference product. Propanol increased the apparent viscosity of the test gels to the same extent as that ...

  7. Preparation And Evaluation Of Fluconazole Gels | Abdel-Mottaleb ...

    African Journals Online (AJOL)

    Gels dosage forms are successfully used as drug delivery systems considering their ability to control drug release and to protect medicaments from a hostile environment. Thus, it was desired in this study to formulate fluconazole into a gel that could be used locally in the treatment of different skin fungal infections. Cellulose ...

  8. Viscoelastic nature of Au nanoparticle–PDMS nanocomposite gels

    Indian Academy of Sciences (India)

    A stable gel of Au nanoparticles in polydimethylsiloxane (PDMS) nanocomposite is prepared by employing the curing agent of PDMS elastomer as a reducing agent for the formation of Au nanoparticles by an in-situ process. The viscoelastic nature of these gels is very sensitive to the Au nanoparticle loading and the ...

  9. Method of making ionic liquid mediated sol-gel sorbents

    Science.gov (United States)

    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.

  10. Self-Healing Corrosion Protective Sol-Gel Coatings

    NARCIS (Netherlands)

    Abdolah Zadeh, M.

    2016-01-01

    Inspired by the state of the art and the recent advances in the field of self-healing corrosion protective coatings, the thesis entitled “Self-healing corrosion protective sol-gel coatings” addresses novel routes to self-healing corrosion protective sol-gel coatings via extrinsic and intrinsic

  11. Electrochemical behavior of ionically crosslinked polyampholytic gel electrolytes

    International Nuclear Information System (INIS)

    Chen Wanyu; Tang Haitao; Ou Ziwei; Wang Hong; Yang Yajiang

    2007-01-01

    An ionic complex of anionic and cationic monomers was obtained by protonation of (N,N-diethylamino)ethylmethacrylate (DEA) with acrylic acid (AAc). Free radical copolymerization of the ionic complex and acrylamide (AAm), yielded the ionically crosslinked polyampholytic gel electrolytes [poly(AAc-DEA-AAm), designated as PADA] using two types of organic solvents containing a lithium salt. The PADA gel electrolyte exhibited good thermal stability shown by the DSC thermogram. The impedance analysis at temperatures ranging from -30 to 75 deg. C indicated that the ionic conductivities of the PADA gel electrolytes were rather close to those of liquid electrolytes. The temperature dependence of the ionic conductivities was found to be in accord with the Arrhenius equation. Moreover, the ionic conductivities of PADA gel electrolytes increased with an increase of the molar ratios of cationic/anionic monomers. The ionic conductivities of PADA gels prepared in solvent mixtures of propylene carbonate, ethyl methyl ether and dioxolane (3:1:1, v/v) were higher than those of PADA gels prepared in propylene carbonate only. Significantly, the ionic conductivities of two kinds of PADA gel electrolytes were in the range of 10 -3 and 10 -4 S cm -1 even at -30 deg. C. The electrochemical windows of PADA gel electrolytes measured by cyclic voltammetry were in the range from -1 V to 4.5 V

  12. Radiation reaction of skin treatment with nucliderm-gel

    International Nuclear Information System (INIS)

    Pandova, V.; Marinova, Ts.; Stefanova, D.; Pantev, T.; Yankova, S.

    1988-01-01

    The process of epithelization and the anticeptic effect of nucliderm-gel applied locally have been studied in 63 oncological patients subjected to radiotherapy. In all cases under study nucliderm-gel promotes skin epithelization and has a high antiseptic effect as compared with the drugs applied hitherto

  13. Comparative antimicrobial activities of aloe vera gel and leaf ...

    African Journals Online (AJOL)

    The comparative antimicrobial activities of the gel and leaf of Aloe vera were tested against Staphylococcus aureus, Pseudomonas aeruginosa, Trichophyton mentagraphytes, T. schoeleinii, Microsporium canis and Candida albicans. Ethanol was used for the extraction of the leaf after obtaining the gel from it. Antimicrobial ...

  14. Fast Dissolving Tablets of Aloe Vera Gel | Madan | Tropical Journal ...

    African Journals Online (AJOL)

    Purpose: The objective of this work was to prepare and evaluate fast dissolving tablets of the nutraceutical, freeze dried Aloe vera gel. Methods: Fast dissolving tablets of the nutraceutical, freeze-dried Aloe vera gel, were prepared by dry granulation method. The tablets were evaluated for crushing strength, disintegration ...

  15. Gel Electrophoresis--The Easy Way for Students

    Science.gov (United States)

    VanRooy, Wilhelmina; Sultana, Khalida

    2010-01-01

    This article describes a simple, inexpensive, easy to conduct gel-electrophoresis activity using food dyes. It is an alternative to the more expensive counterparts which require agarose gel, DNA samples, purchased chamber and Tris-borate-EDTA buffer. We suggest some learning activities for senior biology students along with comments on several…

  16. Inexpensive and Safe DNA Gel Electrophoresis Using Household Materials

    Science.gov (United States)

    Ens, S.; Olson, A. B.; Dudley, C.; Ross, N. D., III; Siddiqi, A. A.; Umoh, K. M.; Schneegurt, M. A.

    2012-01-01

    Gel electrophoresis is the single most important molecular biology technique and it is central to life sciences research, but it is often too expensive for the secondary science classroom or homeschoolers. A simple safe low-cost procedure is described here that uses household materials to construct and run DNA gel electrophoresis. Plastic…

  17. Evaluation of wheat by polyacrylamide gel electrophoresis | Shuaib ...

    African Journals Online (AJOL)

    ... polyacrylamide gel electrophoresis (SDS-PAGE). Electrophorogram for each variety were scored and presence or absence of each band noted and was entered in a binary data matrix. Based on the data of SDS-PAGE gels cluster analysis was performed to check the variations among varieties. The overall result shows ...

  18. Evaluation of Topical Gel Bases Formulated with Various Essential ...

    African Journals Online (AJOL)

    Evaluation of Topical Gel Bases Formulated with Various Essential Oils for Antibacterial Activity against Methicillin- Resistant Staphylococcus Aureus. ... Lemon grass and thyme oils were chosen for further studies, including analysis of their composition by gas chromatography–mass spectrometry (GC/MS). Gels were ...

  19. Incorporation of high-level nuclear waste in gel spheres

    International Nuclear Information System (INIS)

    Robinson, S.M.; Arnold, W.D.; Bond, W.D.; Angelini, P.; Stinton, D.P.

    1981-01-01

    Waste sludge is incorporated in gel spheres by the method of internal gelation. Gel spheres containing up to 90 wt % waste have been produced from defense and commercial wastes. A generic cesium-bearing waste form has been developed. Pyrolytic carbon and SiC coatings reduce the leachability of all tested articles to the detection limits

  20. Rheological properties of soybean protein isolate gels containing emulsion droplets

    NARCIS (Netherlands)

    Kim, K.H.; Renkema, J.M.S.; Vliet, van T.

    2001-01-01

    Rheological properties of soybean protein gels containing various volume fractions oil droplets have been studied at small and large deformations. Dynamic viscoelastic properties of soybean protein isolate gels were determined as a function of the volume fraction of oil droplets stabilised by the