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Production of equine herpesvirus 1 recombinant glycoprotein D and development of an agar gel immunodiffusion test for serological diagnosis.  

Science.gov (United States)

Equine herpesvirus 1 and 4 (EHV-1 and 4) infect most of the world's horses, causing serious clinical illness. Viral glycoproteins have been identified as the immunodominant antigens that generate the antiviral serological responses to EHV-1 and EHV-4 in infected horses. Here, glycoprotein D of EHV-1 was expressed by a recombinant baculovirus, purified and evaluated by a simple agar gel immunodiffusion test (AGID). Compared with virus neutralization, serological analysis by AGID showed good specificity (100%) and sensitivity (99.5%). The estimated Kappa values for repeatability and reproducibility were satisfactory. Thus, this rapid, inexpensive, simple and highly specific AGID test seems to be a valuable alternative tool for serological detection of antibodies against both EHV-1 and EHV-4. PMID:24631347

Fuentealba, Nadia; Sguazza, Guillermo; Scrochi, Mariela; Bravi, Maria; Zanuzzi, Carolina; Corva, Santiago; Gimeno, Eduardo; Pecoraro, Marcelo; Galosi, Cecilia

2014-06-15

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Simple procedure for preparation of bluetongue virus and epizootic hemorrhagic disease virus antigens for agar gel immunodiffusion.  

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A simplified procedure was developed for preparing soluble antigen from two related orbiviruses, bluetongue and epizootic hemorrhagic disease viruses, for agar gel immunodiffusion. The antigens gave excellent results in both micro-agar gel diffusion (agar gel precipitin) and macro-agar gel diffusion (bluetongue immunodiffusion). Minor modification in the spatial arrangement of reference antisera, commonly utilized in the agar gel immunodiffusion tests, was employed to reduce the possible deve...

Stott, J. L.; Osburn, B. I.

1983-01-01

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Evaluation of the agar-gel immunodiffusion test for the detection of precipitating antibodies against progressive pneumonia virus of sheep.  

Science.gov (United States)

Various cell cultures were evaluated for their ability to support progressive pneumonia virus infection in vitro. Ovine trachea cells supported progressive pneumonia virus infection for an extended time,were extremely durable and could be passaged up until 30 passages. Progressive pneumonia virus infected ovine trachea cells were then used for the production of antigen for agar-gel immunodiffusion. A method for concentrating antigen, diafiltration, was compared to dialysis against polyethylene glycol. Using diafiltration, the concentrated virus was easily quantitated, less viscous (and therefore easier to apply) and only produced one precipitation line. Agar-gel immunodiffusion was used to survey 401 animals from two sheep flocks. One flock (96 sheep) was free of progressive pneumonia while the other flock had 111 of 305 total animals positive for precipitating antibodies. The incidence of precipitating antibodies in sheep ranged from 23% for yearling ewes to 80% in ewes seven years old. PMID:226244

Molitor, T W; Schipper, I A; Berryhill, D L; Light, M R

1979-07-01

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Rapid serum agglutination and agar gel immunodiffusion tests associated to clinical signs in rams experimentally infected with Brucella ovis Teste de soro aglutinação rápida e do teste de imunodifusão em gel de ágar associados aos sinais clínicos em carneiros infectados experimentalmente com Brucella ovis  

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The purpose of this study was to evaluate the agar gel immunodiffusion and the rapid serum agglutination tests associated to clinical signs in rams experimentally infected with Brucella ovis. The serological profile during the 12 months of infection showed a large fluctuation of antibodies that favors the failure in the diagnostic. The evaluation of tests after the experimental infection allowed to suggest that none of the tests were able to detect the infection throughout the period of study...

Cristiane Nakada Nozaki; Nair Silva Cavalcanti de Lira; Otávio Augusto Filho; Hymerson Costa Azevedo; Leandro Rodello; Maurício Gaudério Dasso; Sony Dimas Bicudo; João Marcelo Azevedo de Paula Antunes; Jane Megid

2011-01-01

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Immunodiffusion method for detection of type A Clostridium botulinum.  

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A simple gel immunodiffusion agar procedure was developed for detecting toxigenic strains of Clostridium botulinum type A. The method consisted of overlaying colonies grown on thin-layer tryptone-peptone-glucose-yeast extract agar with gel diffusion agar containing desired levels of C. botulinum type A antitoxin. Concentric precipitin zones formed around colonies of C. botulinum type A. Strains of C. botulinum type A were detected by this procedure. However, C. botulinum type B reacted to a l...

Ferreira, J. L.; Hamdy, M. K.; Zapatka, F. A.; Hebert, W. O.

1981-01-01

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Estudio comparativo de un PCR anidado, ELISA y AGID en la detección del virus de la leucosis bovina en muestras de suero, sangre y leche Comparative study of nested PCR, ELISA and AGID tests in the detection of bovine leukaemia virus infection in serum, blood and milk samples  

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Full Text Available Se evaluaron distintos métodos actualmente disponibles para el diagnóstico de la infección por el virus de la leucosis bovina (VLB. Los métodos empleados fueron AGID en suero, ELISA en muestras de suero y leche y PCR en linfocitos sanguíneos. De un total de 126 animales analizados, AGID identificó un menor número de animales positivos (75 comparado con las pruebas PCR y ELISA aplicadas en muestras de suero y leche (100. Tres animales positivos a AGID fueron negativos a PCR y 28 de las 51 muestras negativas a AGID fueron positivas mediante PCR. La sensibilidad diagnóstica de PCR con respecto a AGID fue de 96%, mientras que la especificidad fue de 45% (kappa 0,45. Todos los animales positivos a AGID fueron también positivos a ELISA aplicado tanto en suero como en leche, mientras que 25 animales negativos a AGID fueron consignados como positivos a ELISA, en ambas muestras biológicas. De esta forma, la sensibilidad diagnóstica de ELISA respecto a AGID fue de un 100%, mientras que la especificidad fue de 51% (kappa 0,55. La menor sensibilidad observada de AGID no es debido a reacciones falso positivas de ELISA y PCR, sino más bien a una mayor sensibilidad de estas últimas, lo que sugiere reconsiderar la utilización del método AGID en aquellos países en que aún se utiliza como método oficial en los programas de erradicación de leucosis.Different methods available for the detection of bovine leukaemia virus (BLV infection were evaluated. The methods evaluated were AGID in serum, ELISA in serum and milk, and PCR in blood lymphocytes. The AGID test identified a smaller number of positive animals (75/126 compared to PCR and ELISA tests (100/126. Three positive animals by AGID were negative by PCR and 28 of the 51 negative samples by AGID were positive by PCR. The sensitivity of PCR with respect to AGID was 96%, whereas the specificity was 45% (kappa 0.45. All positive animals by AGID were also positive by ELISA in serum and milk samples, whereas 25 negative animals by AGID were considered positive by the ELISA test, in both biological samples. Thus, sensitivity of the ELISA with respect to AGID was 100%, whereas specificity was 51% (kappa 0.55. The smaller sensitivity of AGID is not due to false positive reactions of ELISA and PCR tests, but rather to a greater sensitivity of these, which suggests a revision of AGID in those countries in which it is still used as the official method in the erradication programs of leukaemia.

R Felmer

2006-01-01

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Rapid serum agglutination and agar gel immunodiffusion tests associated to clinical signs in rams experimentally infected with Brucella ovis Teste de soro aglutinação rápida e do teste de imunodifusão em gel de ágar associados aos sinais clínicos em carneiros infectados experimentalmente com Brucella ovis  

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Full Text Available The purpose of this study was to evaluate the agar gel immunodiffusion and the rapid serum agglutination tests associated to clinical signs in rams experimentally infected with Brucella ovis. The serological profile during the 12 months of infection showed a large fluctuation of antibodies that favors the failure in the diagnostic. The evaluation of tests after the experimental infection allowed to suggest that none of the tests were able to detect the infection throughout the period of study. The study reinforces the importance of considering the clinical signs to support the diagnosis of Brucella ovis infection in rams.O objetivo deste estudo foi avaliar o uso do teste de imunodifusão em gel de ágar e o teste sorológico de aglutinação rápida comparados aos sinais clínicos em carneiros infectados experimentalmente com Brucella ovis para o diagnóstico confirmatório da brucelose ovina. O perfil sorológico durante os 12 meses pós-infecção mostrou flutuação da resposta por anticorpos, que favorece a falha no diagnóstico. A avaliação dos testes indicou que nenhum dos testes foi capaz de detectar a infecção durante todo o período de estudo. O estudo ressalta a importância de considerar os sinais clínicos para apoiar o diagnóstico confirmatório da infecção por Brucella ovis em carneiros.

Cristiane Nakada Nozaki

2011-08-01

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21 CFR 866.4800 - Radial immunodiffusion plate.  

Science.gov (United States)

...2009-04-01 false Radial immunodiffusion plate. 866.4800 Section 866.4800 Food and Drugs FOOD AND DRUG ADMINISTRATION...Immunology Laboratory Equipment and Reagents § 866.4800 Radial immunodiffusion plate. (a)...

2009-04-01

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Immunodiffusion--A Technique for Coelenterate Polyp Identification.  

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An immunodiffusion test can identify Chrysaora quinquecirrha polyps and differentiate them from the polyps of Cyanea capillata which are also found in the Chesapeake Bay. The polyps of Aurelia aurita and Chrysaora contain antigenic material which form lin...

J. W. Burnett W. M. Gould

1971-01-01

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Comparison of serological methods for the diagnostic of Caprine arthritis-encephalitis (CAE in Rio de Janeiro, Brazil Comparação entre métodos sorológicos para o diagnóstico da Artrite-encefalite caprina (CAE no Rio de Janeiro, Brasil  

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Full Text Available Serum samples of 562 goats were tested for Caprine arthritis-encephalitis using agar gel immunodiffusion test (AGID and enzyme linked immunosorbent assay (ELISA. Seventy-nine samples (14.1% were reactive by both testes but 141 (25.1% were reactive only by ELISA. ELISA, when compared to AGID, presented 100% sensitivity and 70.8% specificity.Soros de 562 caprinos foram submetidos à pesquisa de Artrite-encefalite caprina através dos testes de imunodifusão em gel de agarose (AGID de teste imunoenzimático (ELISA. Das amostras testadas, 79 (14,1% foram reativas em ambos os testes, mas 141 (25,1% foram positivos apenas no ELISA. Assim, a sensibilidade do ELISA em relação ao AGID foi de 100% e a especificidade de 70,8%.

Madelayne Cortez-Moreira

2005-03-01

11

Serogrouping of Halophilic Bdellovibrios from Chesapeake Bay and Environs by Immunodiffusion and Immunoelectrophoresis  

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Little has been reported on the serological relationship of halophilic bdellovibrios (Bd). Immunodiffusion analysis performed with rabbit or mouse Bd antisera developed against eight halophilic Bd isolates and one terrestrial Bd isolate, when reacted with soluble antigen preparations of 45 isolates of halophilic Bd, allowed separation into seven serogroups, which were distinct from the terrestrial isolate. Soluble antigen preparations of prey bacteria, Vibrio parahaemolyticus P-5 (P-5) and Es...

Schoeffield, Andrew J.; Falkler, William A.; Desai, Darshana; Williams, Henry N.

1991-01-01

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Ocorrência da leucose enzoótica dos bovinos no Estado do Pará, Brasil / Occurrence of enzootic bovine leukosis in the State of Pará, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A ocorrência da infecção pelo Vírus da Leucose Enzoótica dos Bovinos (BLV) no Estado do Pará, foi estudada através do método de imunodifusão em ágar-gel (AGID) e por um ensaio imunoenzimatico (ELISA) indireto, paralelamente. Os exames foram realizados com amostras de soros sanguíneos oriundos de bov [...] inos de diferentes raças sendo a maioria deles adultos. A prevalência observada foi de 49,8% (359/721) no ELISA e 26,0% (174/668) no AGID. Todos os 14 grupos dos animais estudados pelo ELISA indireto, mostraram a existência da infeção, enquanto que pelo método da AGID, dois grupos de animais foram negativos. Abstract in english The occurrence of the infection with Bovine Leukosis Virus (BLV) was examined in agar-gel immunodiffusion (AGID) test and with indirect enzyme-linked immunosorbent assay (ELISA), in the State of Pará, Brazil. The blood sera were collected from different breeds including Nelore, Piemontes, Simental, [...] Holstein Frisian, Indubrasil, Girolanda, Simbrasil and their cross-breedings. The majority of the animals were adults. The overall occurrence of infections was 49.8% (359/721) and 26.0% (174/668) for ELISA and AGID test, respectively. All animal groups examined showed infection in ELISA, however in the AGID test two groups were sera negative.

Éva, Molnár; László, Molnár; Hilma Tavares, Dias; Aluízio Otávio Almeida da, Silva; William Gomes, Vale.

13

Non-immunological precipitation by the neutral detergent triton X-100 in agar gel diffusion.  

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Triton X-100 can be used to clarify vague immunoprecipitin lines from bacterial antigens; however, non-immunological precipitation can lead to mistaken interpretation of immunodiffusion results. If Triton X-100 is added directly to the gel during preparation rather than to the antigen well, this detergent artifact can be eliminated.

Mansheim, B. J.; Stenstrom, M. L.

1980-01-01

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Evaluation of western blotting for the diagnosis of enzootic bovine leukemia  

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Full Text Available A western blotting (WB procedure has been developed for detecting antibodies to bovine leukosis virus (BLV in cattle sera. Two hundred and thirty three serum samples from naturally infected cattle with BLV virus and serial bleedings from experimentally BLV infected cows were used. An agar gel immunodiffusion test (AGID was used for comparing with the results obtained by WB. The AGID positive sera showed a different degree of reactivity by WB test against the two most important viral antigens (gp51 and p24, or against one of them. Other proteins (gp30, p15, p12 and p10 were not detected with any AGID positive sera, being observed occasionally three bands corresponding to the p24 protein. Using sera obtained by BLV experimental inoculation, the antibodies directed to p24 appeared early (between the 2nd and 4th week post inoculation and thereafter antibodies to gp51were detected in some animals. The analysis of field serum samples by AGID as compared to WB showed an agreement of 90.9%. Only 1.7% of sera were negative by AGID and positive by WB and 7.2% that were not conclusive by AGID and were defined by WB (4.2% as positive and 3.0% as negative.

Gonzalez E.T.

1999-01-01

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A competitive ELISA for the detection of group-specific antibodies to African horse sickness virus.  

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A competition enzyme-linked immunosorbent assay (ELISA) has been developed for the rapid identification and quantification of antibodies against African horse sickness (AHS) in sera from solipeds. The data showed the ELISA to be sensitive, specific and reliable. More than 1600 sera from 37 different countries were examined and results compared with those obtained by agar gel immuno-diffusion (AGID) tests. In no case did any of 775 sera from countries where AHS has never been reported and wher...

Hamblin, C.; Graham, S. D.; Anderson, E. C.; Crowther, J. R.

1990-01-01

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Interaction Between Newcastle Disease and Infectious Bursal Disease Vaccines Commonly Used in Sudan  

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It was the aim of this study to determine the interaction between the Newcastle disease (ND) and infectious bursal disease (IBD) vaccines used to control these two important viral infections greatly affecting poultry industry worldwide. The commercially available vaccines in the Sudan were used. Haemagglutination inhibition (HI) and agar gel immunodiffusion (AGID) tests were employed to measure the Ab titres in chicks sera to ND and IBD respectively. Generally, IBD vaccine was reported to hav...

2004-01-01

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Numerical Taxonomic Analysis of Some Strains of Rhizobium spp. That Uses a Qualitative Coding of Immunodiffusion Reactions  

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Antigenic relationships among seven strains of Bradyrhizobium japonicum were examined by immunodiffusion reactions, in which cells of each strain were reacted against each of the seven corresponding antisera. Similar analyses were performed with Rhizobium trifolii (28 strains), Rhizobium meliloti (9 strains), and rhizobia of the cowpea miscellany (13 strains). Antigens and antisera were reacted within each species only; serological interspecies cross-reactions were not performed. The results,...

Dudman, William F.; Belbin, Lee

1988-01-01

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Epidemiological studies on bluetongue virus infection in West Java, Indonesia  

International Nuclear Information System (INIS)

In monitoring of sentinel cattle in West Java, seroconversions to orbiviruses occurred mostly at the end of the wet season. A low altitude site gave more reactors than did a high altitude site. Due to perceived inefficiencies of the agar gel immunodiffusion (AGID) test, a competitive ELISA (C-ELISA) was applied and the results compared with the AGID test results. C-ELISA detected antibodies at an earlier stage of infection than did the AGID test. Not all sera reacting in the AGID test reacted in C-ELISA, suggesting that the C-ELISA is more specific in detecting bluetongue virus (BTV) antibodies than the AGID. However, as the infection status of most field sera was not known, this could not be confirmed conclusively from the available data. A comparison of isolation methods indicated that isolates were obtained more frequently if samples were passaged in embryonated eggs before blind passage in A edes albopictus cells followed by passage in BHK-21 cells. Six BTV serotypes, 1,7,9,12,20,21 and 23 were identified and confirmed from apparently healthy sentinel cattle blood at low altitudes; BTV serotype 21 was also isolated from a pool of the Avaritia sub-genus of the Culicoides spp which contained 227 C. fulvus and 20 C. orientalis. (author). 17 refs, 2 figs, 1 tab

1994-02-01

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Numerical Taxonomic Analysis of Some Strains of Rhizobium spp. That Uses a Qualitative Coding of Immunodiffusion Reactions.  

Science.gov (United States)

Antigenic relationships among seven strains of Bradyrhizobium japonicum were examined by immunodiffusion reactions, in which cells of each strain were reacted against each of the seven corresponding antisera. Similar analyses were performed with Rhizobium trifolii (28 strains), Rhizobium meliloti (9 strains), and rhizobia of the cowpea miscellany (13 strains). Antigens and antisera were reacted within each species only; serological interspecies cross-reactions were not performed. The results, scored qualitatively as reactions of identity, cross-reactions, or no reaction, were formed into datum matrices and used to analyze the relationships between strains by applying the association measure of Bray and Curtis (J. R. Bray and J. T. Curtis, Ecol. Monogr. 27:325-349, 1957) and the UPGMA clustering algorithm (P. H. A. Sneath and R. R. Sokal, Numerical Taxonomy, 1973). No two strains were regarded as being serologically identical unless each gave the same results as the other in each immunodiffusion reaction against every antiserum. Despite the high level of cross-reactions and reactions of identity (totalling 93% of all cell-antiserum combinations) among strains of R. trifolii and R. meliloti, no strains were identical by the criterion described above; however, the strains of these species clustered rapidly and fused at the 70% similarity level. The B. japonicum strains and the rhizobia of the cowpea miscellany were much less cross-reactive (67 and 86% of all combinations were negative, respectively), and they clustered more slowly. The strains of B. japonicum fused completely only at the 4% similarity level, whereas of the 13 cowpea-nodulating strains, 4 reacted as two pairs of identical strains and 6 remained unfused. PMID:16347692

Dudman, W F; Belbin, L

1988-07-01

20

GEL PROCESSING  

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Gel processing technology has been classified into four groups : Sol-gel, Gel-precipitation, Gel addition and the Alkoxide route. Each of the groups has merit for preparing specialised ceramic materials. Investigations into the hydrous oxide gel structures revealed they could be used to thermally decompose alkali and alkaline-earth metal salts. In some cases the acidic thermal decomposition products reacted with the hydrous gel substrate to give deaggregated oxides which readily formed concen...

Woodhead, J. L.

1986-01-01

 
 
 
 
21

Development and evaluation of an enzyme-linked immunosorbent assay for detection of bovine antibodies to epizootic hemorrhagic disease of deer viruses.  

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An indirect enzyme-linked immunosorbent assay (I.ELISA) is described for detection of bovine serum antibody to epizootic hemorrhagic diseases of deer virus (EHDV). Serum samples, at a dilution of 1:200, were incubated with group-specific EHDV antigens, pre-adsorbed to microtiter plates. Bound antibodies were detected by a murine monoclonal antibody to bovine immunoglobulin (Ig)G1 (heavy-chain specific) conjugated with horseradish peroxidase. The performance of the I.ELISA in detecting antibodies to EHDV in sequential serum samples from calves experimentally infected with serotypes 1,2,3 and 4 was evaluated. The I.ELISA detected EHDV antibodies from 14 days postinfection when seroconversion by the standard agar gel immunodiffusion (AGID) test was also evident. The group-specific antibodies to EHDV increased exponentially during the first two to four weeks postinfection and remained relatively stable for about 12 months in some calves. Unlike observations with the AGID test, no reaction was seen in the I.ELISA between blue-tongue virus (BTV) antigen and sera from calves given a single dose of EHDV. The performance of the I.ELISA and AGID were compared using 3,135 AGID negative bovine field sera from herds in Ontario, Alberta and British Columbia and 130 AGID positive samples collected from cattle in 1987 and 1988 during and after outbreaks of EHD in the Okanagan Valley, British Columbia. The specificity and sensitivity of the assay relative to the AGID test were 99.3% and 91.5% respectively, with an overall agreement of 99.0% between the tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Afshar, A; Wright, P F; Taylor, L A; Shapiro, J L; Dulac, G C

1992-01-01

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Comparison of modified immunodiffusion and Bacteriological Analytical Manual (BAM) methods for detection of Salmonella in raw flesh and highly contaminated food types.  

Science.gov (United States)

A wide variety of naturally contaminated and inoculated raw flesh and highly contaminated food types was analyzed by a modified immunodiffusion enrichment protocol and the Bacteriological Analytical Manual (BAM) method to determine the equivalence of these methods. This modification was developed by Agriculture Canada to allow addition of a high-temperature selective enrichment step in tetrathionate brilliant green broth at 42 degrees C while maintaining a 2-day total test time. Foods representing red meat, white meat, frog, and seafoods and one type of animal meal were evaluated. A total of 320 samples was tested, resulting in false negative rates of 5.2 and 3.5%, respectively, for the modified immunodiffusion and the BAM culture methods. The overall agreement rate was 96.9%. PMID:7580341

Feldsine, P T; Falbo-Nelson, M T

1995-01-01

23

The bovine immune response to Brucella abortus IV. Studies with a double immunodiffusion test for antibody against A2.  

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A double immunodiffusion test for precipitins against Brucella antigen A2 was developed and applied to a variety of samples. The A2 precipitins were produced by a heifer infected with B. abortus strain 2308, cattle vaccinated with killed B. melitensis strain H38 or live B. abortus strain 19 and by a dog infected with B. canis. Precipitins were also detected in the second International Standard for anti-Brucella abortus serum, in several anti-B. canis sera and at low levels in one anti-B. ovis serum tested. Antisera produced in calves against Yersinia enterocolitica serotype 0:9 had no anti-A2 activity despite titers greater than or equal to 1/1024 and greater than or equal to 1/80 in standard Brucella agglutination and CF tests, respectively. The test for A2 precipitins lacked specificity as weak reactions were obtained with five of 295 sera from brucellosis-free herds. This test was relatively insensitive, detecting precipitins in only 16 of 24 sera from infected cattle and 27 of 54 sera positive by complement fixation and enzyme labelled antiglobulin tests performed with whole cell and smooth lipopolysaccharide antigens, respectively. The A2 precipitins were detected in nine sera from five cattle, in two infected herds, which were negative by agglutination and complement fixation tests. PMID:6790144

Stemshorn, B; Nielsen, K

1981-04-01

24

Aspergillus fumigatus fungus ball in hospitalized patients with chronic pulmonary disease: usefulness of double immunodiffusion test as a screening procedure  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Trezentos e cinquenta pacientes sintomáticos respiratórios admitidos no Hospial Raphael de Paula Souza, sem diagnóstico etiológico definitivo, foram triados pela técnica de imunodifusão dupla (IDD) para aspergilose. Quando a IDD foi positiva, informações adicionais como histórico e exames radiológic [...] os foram requisitados e, quando possível, espécimes clínicos foram processados para exames micológicos e histopatológicos. Linhas de precipitação específicas para o antígeno de A. fumigatus foram encontradas em 29(8,3%) dos 350 soros de pacientes testados. Dezenove (65,5% dos 29 pacientes cm sorologia positiva foram reconhecidos como tendo boa fúngica pelos achados radiológicos em dois ou por ambos em oito pacientes. Este estudo prospectivo de dois anos mostrou que aspergilose pulmonar é um problema considerável entre pacientes admitidos em um hospital para sintomáticos respiratórios, especialmente aqueles com cavidades pulmonares ou bronquiectasias. Abstract in english Double immunodiffusion (DID) was used as a screening test for the diagnosis of aspergillosis. Three hundred and fifty patients were tested, all of them referred from a specialized chest disease hospital and without a definitive etiological diagnosis. When DID was positive addtional information such [...] as clinical history and radiographic findings were requested and also surgical specimens were obtained whenever possible. Specific precipitin hamds for Aspergillus fumigatus antigen were found in 29 (8.3%) of 350 patients sera. Nineteen (65.5%) of the 29 patients with positive serology were recognized as having a fungus ball by X-rays signs in 17 or by pathological examination in 2 or by both in 8 patients. This two-year prospective study has shown that pulmonary aspergillos is a considerable problem among patiens admitted to a Chest Diseases Hospital, especially in those with pulmonary cavities or bronchiectasis.

M. F., Ferreira-da-Cruz; B., Wanke; C., Pirmez; B., Galvão-Castro.

25

Aerosol gels  

Science.gov (United States)

An improved process for the production of ultralow density, high specific surface area gel products is provided which comprises providing, in an enclosed chamber, a mixture made up of small particles of material suspended in gas; the particles are then caused to aggregate in the chamber to form ramified fractal aggregate gels. The particles should have a radius (a) of up to about 50 nm and the aerosol should have a volume fraction (f.sub.v) of at least 10.sup.-4. In preferred practice, the mixture is created by a spark-induced explosion of a precursor material (e.g., a hydrocarbon) and oxygen within the chamber. New compositions of matter are disclosed having densities below 3.0 mg/cc.

Sorensen, Christopher M. (Inventor); Chakrabarti, Amitabha (Inventor); Dhaubhadel, Rajan (Inventor); Gerving, Corey (Inventor)

2010-01-01

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The feasibility of using antigens prepared with rough Brucella strains for diagnosis of canine brucellosis Utilidad de los antígenos preparados con cepas rugosas de Brucella en el diagnóstico de brucelosis canina  

Directory of Open Access Journals (Sweden)

Full Text Available Clinical diagnosis of canine brucellosis is not sensitive enough and a negative blood culture cannot rule out the disease. Indirect methods of serological testing such as agar gel immunodiffusion (AGID, rapid slide agglutination test (RSAT and indirect enzyme linked immunoassay (IELISA are preferred for routine diagnosis. Since Brucella canis shares antigenic components with the Brucella ovis and Brucella abortus RB51 strain, it would seem that either strain could be used as antigen. We present data on AGID and IELISA tests using the B. ovis antigen, RSAT and IELISA using the B. canis antigen and IELISA using the B. abortus RB51 antigen. The cut-off values were adjusted by the ROC analysis; the IELISA-B. ovis cut-off value was 23 (%P and the IELISA-B. abortus RB51, 24 (%P, with 100% sensitivity and 98.8% specificity. RSAT detected 100% of positive cases, while AGID was less sensitive. The sera from dogs treated with antibiotic showed that %P correlated well with the clinical course. Sera from dogs presumptively infected with B. suis were negative in all tests performed with the rough Brucella strains. RSAT is a very sensitive screening test and IELISA-B. canis, B. ovis and B. abortus RB51 could be used as confirmatory tests, since they show good specificity and sensitivity.Las técnicas más usadas en el diagnóstico de brucelosis canina son la inmunodifusión en gel de agar (AGID, la microaglutinación en portaobjetos (RSAT y el ELISA indirecto ya que el diagnóstico clínico es poco sensible y el bacteriológico no excluye la enfermedad. Como Brucella canis comparte componentes antigénicos con Brucella ovis y Brucella abortus RB51, estas cepas podrían ser usadas indistintamente como antígenos. En este trabajo presentamos datos sobre las pruebas de AGID e IELISA con antígeno B. ovis, RSAT e IELISA con antígeno B. canis e IELISA con antígeno B. abortus RB51. Los puntos de corte ajustados con la curva ROC fueron (%P 23 para IELISA-B. ovis y (%P 24 para IELISA-RB51 con 100% de sensibilidad y 98,8% de especificidad. RSAT detectó el 100% de los casos positivos, pero AGID fue menos sensible. Los sueros de los perros tratados con antibióticos tuvieron un %P que correlacionó con la evolución clínica. Los perros presumiblemente infectados con B. suis fueron negativos a todos los ensayos realizados con antígenos de cepas de Brucella rugosas. RSAT es muy sensible como prueba tamiz y los IELISA con antígenos de B. canis, B. ovis y B. abortus RB51 podrían ser usados como confirmatorios ya que han demostrado alta sensibilidad y especificidad.

G. I. Escobar

2010-02-01

27

Fundamentals of gel dosimeters  

International Nuclear Information System (INIS)

Fundamental chemical and physical phenomena that occur in Fricke gel dosimeters, polymer gel dosimeters, micelle gel dosimeters and genipin gel dosimeters are discussed. Fricke gel dosimeters are effective even though their radiation sensitivity depends on oxygen concentration. Oxygen contamination can cause severe problems in polymer gel dosimeters, even when THPC is used. Oxygen leakage must be prevented between manufacturing and irradiation of polymer gels, and internal calibration methods should be used so that contamination problems can be detected. Micelle gel dosimeters are promising due to their favourable diffusion properties. The introduction of micelles to gel dosimetry may open up new areas of dosimetry research wherein a range of water-insoluble radiochromic materials can be explored as reporter molecules.

2013-06-26

28

Fundamentals of gel dosimeters  

Science.gov (United States)

Fundamental chemical and physical phenomena that occur in Fricke gel dosimeters, polymer gel dosimeters, micelle gel dosimeters and genipin gel dosimeters are discussed. Fricke gel dosimeters are effective even though their radiation sensitivity depends on oxygen concentration. Oxygen contamination can cause severe problems in polymer gel dosimeters, even when THPC is used. Oxygen leakage must be prevented between manufacturing and irradiation of polymer gels, and internal calibration methods should be used so that contamination problems can be detected. Micelle gel dosimeters are promising due to their favourable diffusion properties. The introduction of micelles to gel dosimetry may open up new areas of dosimetry research wherein a range of water-insoluble radiochromic materials can be explored as reporter molecules.

McAuley, K. B.; Nasr, A. T.

2013-06-01

29

Physico-chemical and antigenic characterization of unconventional heavy chain antibodies of Indian desert camel (Camelus dromedarius L.).  

Science.gov (United States)

Heavy chain antibodies (HCAbs) of IgG2 and IgG3 subtypes were purified from the sera of Indian desert camel (Camelus dromedarius L.) by ammonium sulphate precipitation, followed by ion-exchange chromatography on DEAE-cellulose and affinity chromatography on protein A-sepharose and protein G-sepharose, and characterized by SDS-polyacrylamide gel electrophoresis, agar gel immunodiffusion (AGID), counter-immunoelectrophoresis (CIEP), immunoelectrophoresis (IEP), ELISA and immunoblotting. IgG2 and IgG3 were found to have molecular mass 46.77 kDa and 43.65 kDa, respectively by SDS-PAGE under reducing conditions. They migrated in beta-region in IEP and could be detected in CIEP, because of being more negatively charged and smaller size. Anti-camel IgG3 cross-reacted in AGID, ELISA and immunoblotting with IgGs of pig and ruminants (cattle, buffalo, sheep and goat), but not with immunoglobulins from horse, dog, guinea pigs, mice, fish, poultry and human. The present findings suggest close antigenic relationship of camels with pigs and ruminants. PMID:22900358

Sehrawat, Sharvan; Singh, Ajit

2004-12-01

30

SOROPREVALÊNCIA DA PNEUMONIA PROGRESSIVA OVINA (MAEDI-VISNA NA REGIÃO DE BOTUCATU – SP PREVALENCE OF SERUM ANTIBODIES TO OVINE PROGRESSIVE PNEUMONIA (MAEDI-VISNA IN BOTUCATU REGION  

Directory of Open Access Journals (Sweden)

Full Text Available O presente estudo visou determinar a soroprevalência da pneumonia progressiva ovina, na região de Botucatu, mediante prova de imunodifusão em gel de ágar (IDGA. Foram avaliadas quatrocentas amostras de soro sanguíneo de ovinos de oito propriedades de corte, com criação em sistema semi-intensivo, de diferentes municípios da região. Nenhuma das amostras de soro foi reagente na prova de IDGA. A análise desses resultados mostra discordância com estudos realizados em outros estados brasileiros, nos quais a prevalência da doença vem aumentando progressivamente.

PALAVRAS-CHAVES: IDGA, lentivírus, ovinos.

The present study aimed to verify the prevalence of the ovine progressive pneumonia in Botucatu region by agar gel immunodiffusion test (AGID.  Serum samples of 400 sheep from eight specific farms for meat, with type of semi-intensive breeding of different areas. All the samples tested were negative to Maedi-Visna. The analysis of results was discordant with studies made in others Brazilians states, where the prevalence of the disease comes increasing progressively.

KEY WORDS: AGID, lentivirus, sheep.

José Rafael Modolo

2009-09-01

31

Removing water from gels  

International Nuclear Information System (INIS)

Water is removed from a gel material by contacting the gel material with a gaseous mixture of an organic compound and a gas. The organic compound, the gas and conditions of contacting are selected such that water is extracted from the gel material and passes into the gaseous mixture. In examples, the invention is applied to spherical gel precipitated particles prepared from a mixture of thorium and uranium nitrate solutions. (author)

1982-01-01

32

Removing water from gels  

International Nuclear Information System (INIS)

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)

1982-01-01

33

Applications of gel dosimetry  

Energy Technology Data Exchange (ETDEWEB)

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.

Ibbott, Geoffrey S [Department of Radiation Physics, UT M.D. Anderson Cancer Center, Houston, Texas 77030 (United States)

2004-01-01

34

Radiotherapy gel dosimetry  

International Nuclear Information System (INIS)

The use of radiation sensitive gels for dosimetry measurements was first suggested in the 1950s. It was subsequently shown that radiation induced changes in the nuclear magnetic resonance relaxation properties of gels infused with conventional Fricke dosimetry solutions could be measured. Owing to diffusion related limitations in the use of Fricke gels, alternative polymer gel dosimeters were suggested. Both magnetic resonance imaging and optical laser techniques have been used to evaluate gel dosimeters and to produce three dimensional dose distributions. More recently, the use of X ray computer tomography, ultrasound and vibrational spectroscopy have also been demonstrated as valuable techniques in the evaluation of polymer dosimetry gels. Gel dosimetry has been shown to have great potential in the evaluation of complex dose distributions, such as in external beam radiotherapy, including intensity modulated radiation therapy and brachytherapy. (author)

2003-12-01

35

Sol-gel glasses  

Science.gov (United States)

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.

Mukherjee, S. P.

1985-01-01

36

Sol-gel science  

Energy Technology Data Exchange (ETDEWEB)

Although the science and technology of sol-gel processing has experienced enormous growth in the last decade, few books have been available to help researchers cope with the flood of results published in various journals and conference proceedings. This book presents and understanding of sol-gel processing. Following the sol-gel processing sequence from beginning to end, it includes discussions on the chemistry of hydrolysis and condensation of metalorganics and inorganic salts, the growth of polymeric or particulate species in sols, gelation, aging of gels, drying, structure of gels, and sintering. In addition, it compares the properties of gel-derived and conventionally prepared ceramics, examines films in detail, and presents a variety of applications.

Brinker, C.J. (Sandia National Laboratories, Albuquerque, NM (US)); Scherer, G.W. (E.I. du Pont de Nemours and Company, Wilmington, DE (US))

1990-01-01

37

Buckling of swelling gels  

CERN Document Server

The patterns arising from the differential swelling of gels are investigated experimentally and theoretically as a model for the differential growth of living tissues. Two geometries are considered: a thin strip of soft gel clamped to a stiff gel, and a thin corona of soft gel clamped to a disk of stiff gel. When the structure is immersed in water, the soft gel swells and bends out of plane leading to a wavy periodic pattern which wavelength is measured. The linear stability of the flat state is studied in the framework of linear elasticity using the equations for thin plates. The flat state is shown to become unstable to oscillations above a critical swelling rate and the computed wavelengths are in quantitative agreement with the experiment.

Mora, T; Mora, Thierry; Boudaoud, Arezki

2005-01-01

38

Sol-gel processing  

Energy Technology Data Exchange (ETDEWEB)

Sol gel processing has been reviewed from the standpoint of preparing materials in the shape of a bulk cylinder or plate, fiber or coating. Also, microstructures achieved by sol-gel processing have been reviewed. It is indicated that sol-gel processing is versatile and produces a wide variety of high technology materials having optical, electronic, chemical and biological functions. Processing of some optical coating films is discussed in more detail.

Sakka, Sumio [Fukui Univ. of Technology, Gakuen (Japan)

1995-12-31

39

CONFORMANCE IMPROVEMENT USING GELS  

Energy Technology Data Exchange (ETDEWEB)

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

Randall S. Seright

2003-09-01

40

Polymer gel; Kobunshi geru  

Energy Technology Data Exchange (ETDEWEB)

Gel being swollen by water is named hydrogel, and is adopted in the field of medicine such as slow release drug in drug delivery system, artificial muscles, and intelligent materials developing function by responding to irritation. Water in gel has strong mutual action with chain of polymer, and water not freezing in 0 degree C exists. This kind of water is orientated directly with functional group of gel, and is called non-freezing water by reason of not freezing in -196 degree C. Water being orientated loosely around non-freezing water is called bound water, and can be distinguish from free water freezing 0 degree C. Factors giving influence to speed of swelling and shrinking are size of gel and porosity. As of response time being in proportion to square of representative length of gel, velocity of response is fast by the size of gel being as fine as possible. The soft contact lens developed in Czechoslovakia in 1960 is poly-hydroxy-ethyl-cellulose gel. The permeability of oxygen is superior due to moisture content being increased. Furthermore, the devise releasing insulin responding glucose is developed. (NEDO)

Sudo, M. [Shizuoka Univ., Shizuoka (Japan)

2000-02-05

 
 
 
 
41

Fracture energy of gels  

CERN Multimedia

To clarify effects of crack speed and cross-link density on fracture energy of acrylamide gels, we evaluated the roughness of the fracture surface and measured the fracture energy taking into account the roughness. The fracture energy increases linearly with crack speed $V$ in a fast crack speed region, and the increasing rate of fracture energy with $V$ decreases with increasing cross link density in the gels. In a slow crack speed region the fracture energy depends on crack speed more strongly than in the fast crack speed region. This indicates that a qualitative change exists in fracture process of the gels.

Tanaka, Y; Miyamoto, Y; Tanaka, Yoshimi; Fukao, Koji; Miyamoto, Yoshihisa

2000-01-01

42

Bouncing gel balls  

CERN Multimedia

We investigated impacts of nearly elastic spherical gels (very soft balls) onto a solid substrate. The Hertz contact deformation expected in the static (elastic) limit was observed only at very small impact velocities. For larger velocities, a gel ball deformed into flattened forms like a pancake. We measured the size of gel balls at the maximal deformation and a contact time as a function of velocities for samples different in the original spherical radius and the Young modulus. The experimental results revealed a number of scaling relations. To interpret these relations, we developed scaling arguments to propose a physical picture.

Tanaka, Y; Okumura, K; Tanaka, Yoshimi; Yamazaki, Yoshihiro; Okumura, Ko

2003-01-01

43

Cellulosic polymers in gels  

Energy Technology Data Exchange (ETDEWEB)

Currently there is renewed interest in the subject of gels. Their utility depends on their unusual physical form and rheology, and methods for characterizing them will be outlined. Clear gels usually contain soluble macromolecules or elongated micelles. A further requirement is that these building blocks form contact points or overlaps in order to develop the structural network crucial for gel formation. Various polysaccharides, including several cellulosic polymers can satisfy these criteria. It is now known that the network structure can be promoted by incorporating suitable combinations of such polymers with various surfactants and/or modifying the polymers by hydrophobic substitution. Recent work along these lines will be described.

Goddard, E.D.

1995-12-01

44

Mechanically Induced Gel Formation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Mechanical triggering of gelation of an organic solution by a carbazole-based bisurea organogelator is described. Both the duration of the mechanical stimulation and the gelator concentration control the gelation process and the characteristics of the gel obtained.

Herpt, Jochem T.; Stuart, Marc C. A.; Browne, Wesley R.; Feringa, Ben L.

2013-01-01

45

Periodic mesoporous silica gels  

Energy Technology Data Exchange (ETDEWEB)

We have synthesized monolithic particulate gels of periodic mesoporous silica by adding tetramethoxysilane to a homogeneous alkaline micellar precursor solution. The gels exhibit 5 characteristic length scales over 4 orders of magnitude: fractal domains larger than the particle size (>500 nm), particles that are {approximately}150 to 500 nm in diameter, interparticle pores that are on the order of the particle size, a feature in the gas adsorption measurements that indicates pores {approximately}10-50 nm, and periodic hexagonal arrays of {approximately}3 nm channels within each particle. The wet gel monoliths exhibit calculated densities as low as {approximately}0.02 g/cc; the dried and calcined gels have bulk densities that range from {approximately}0.3-0.5 g/cc. The materials possess large interparticle ({approximately}1.0-2.3 cc/g) and intraparticle ({approximately}0.6 cc/g) porosities.

Anderson, M.T.; Martin, J.E.; Odinek, J.G. [and others

1996-06-01

46

Inquérito sorológico e fatores de risco para a brucelose por Brucella canis em cães do município de Santana de Parnaíba, Estado de São Paulo / Serological survey and risk factors for brucellosis due to Brucella canis in dogs of the Santana de Parnaíba municipality, State of São Paulo  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Foi investigada a prevalência da brucelose causada por Brucella canis em cães do município de Santana de Parnaíba, SP, Brasil, e realizado um estudo de possíveis fatores de risco associados à soropositividade para B. canis. Foram examinadas 410 amostras de soro sanguíneo de cães colhidas durante a c [...] ampanha de vacinação anti-rábica animal, realizada em agosto de 1999. A imunodifusão em gel de ágar (IDGA), utilizando antígeno de lipopolissacarídeos e proteínas de Brucella ovis, amostra Reo 198, foi empregada em soros normais como teste de triagem, e, para a confirmação, a mesma técnica foi aplicada em soros tratados pelo 2-mercaptoetanol (IDGA-ME). A reação de fixação de complemento (CFT), utilizando antígeno de B. ovis, amostra 63/290, também foi utilizada como prova confirmatória. A determinação da prevalência considerou como positivos os animais que reagiram positivamente nos dois testes confirmatórios (IDGA-ME e CFT). A prevalência da B. canis foi de 2,2% (I.C. 95% = 1,01-4,13%). A análise estatística mostrou que os cães com acesso irrestrito à rua o dia todo (manejo do tipo solto) estiveram mais expostos ao risco da infecção por B. canis, com um valor de odds ratio de 8,73 (I.C. 95% = 1,48-51,55) e p=0,04. Abstract in english The prevalence of brucellosis due to Brucella canis was investigated in dogs of the Santana de Parnaíba county, State of São Paulo, southeastern Brazil, and the risk factors for infection were analyzed. For this purpose, 410 blood samples were collected from dogs during the rabies vaccination campai [...] gn, in August 1999. The agar gel immunodiffusion test (AGID), using lipopolysaccharides and protein antigens from Brucella ovis, strain Reo 198, was applied first as a screening test on normal sera, and secondly, for confirmation. The same AGID test was applied to sera treated previously with 2-mercaptoethanol (ME-AGID). The complement fixation test (CFT), using B. ovis antigen, strain 63/290, was applied also as a confirmatory test. For the prevalence analysis, animals presenting positive results in both ME-AGID and CFT were considered positive. The prevalence of brucellosis due to B. canis was 2.2% (95% C.I.=1.01-4.13%). Dogs that were allowed by their owners to stay free outside their home had a higher risk for contracting B. canis infection, with an odds ratio value of 8.73 (95% C.I.=1.48-51.55) and p=0.04.

Sérgio S., Azevedo; Sílvio A., Vasconcellos; Clebert J., Alves; Lara B., Keid; Lília M.P. S., Grasso; Roberta, Mascolli; Sônia R., Pinheiro.

47

Preparation of chitosan gel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aerogel conditioning of the chitosan makes it possible to prepare porous solids of significant specific surface. The increase in the chitosan concentration or the degree of acetylation decreases the specific surface of the synthesized chitosan gel. Whereas drying with supercritical CO2 more effectively makes it possible to preserve the volume of the spheres of gel and to have a more significant specific surface in comparison with evaporative drying.

Moussaoui Y.; Mnasri N.; Elaloui E.; Ben Salem R.; Lagerge S.; de Menorval L. C.

2012-01-01

48

Polymer gel dosimetry  

Energy Technology Data Exchange (ETDEWEB)

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)

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

49

CONFORMANCE IMPROVEMENT USING GELS  

Energy Technology Data Exchange (ETDEWEB)

This report describes work performed during the third and final year of the project, ''Conformance Improvement Using Gels.'' Corefloods revealed throughput dependencies of permeability reduction by polymers and gels that were much more prolonged during oil flow than water flow. This behavior was explained using simple mobility ratio arguments. A model was developed that quantitatively fits the results and predicts ''clean up'' times for oil productivity when production wells are returned to service after application of a polymer or gel treatment. X-ray computed microtomography studies of gels in strongly water-wet Berea sandstone and strongly oil-wet porous polyethylene suggested that oil penetration through gel-filled pores occurs by a gel-dehydration mechanism, rather than gel-ripping or gel-displacement mechanisms. In contrast, analysis of data from the University of Kansas suggests that the gel-ripping or displacement mechanisms are more important in more permeable, strongly water-wet sandpacks. These findings help to explain why aqueous gels can reduce permeability to water more than to oil under different conditions. Since cement is the most commonly used material for water shutoff, we considered when gels are preferred over cements. Our analysis and experimental results indicated that cement cannot be expected to completely fill (top to bottom) a vertical fracture of any width, except near the wellbore. For vertical fractures with apertures less than 4 mm, the cement slurry will simply not penetrate very far into the fracture. For vertical fractures with apertures greater than 4 mm, the slurry may penetrate a substantial distance into the bottom part of the fracture. However, except near the wellbore, the upper part of the fracture will remain open due to gravity segregation. We compared various approaches to plugging fractures using gels, including (1) varying polymer content, (2) varying placement (extrusion) rate, (3) using partially formed gels, (4) using combinations of high and low molecular weight (Mw) polymers, (5) using secondary crosslinking reactions, (6) injecting un-hydrated polymer particles, and (7) incorporating particulates. All of these methods showed promise in some aspects, but required performance improvements in other aspects. All materials investigated to date showed significant performance variations with fracture width. High pressure gradients and limited distance of penetration are common problems in tight fractures. Gravity segregation and low resistance to breaching are common problems in wide fractures. These will be key issues to address in future work. Although gels can exhibit disproportionate permeability reduction in fractures, the levels of permeability reduction for oil flow are too high to allow practical exploitation in most circumstances. In contrast, disproportionate permeability reduction provided by gels that form in porous rock (adjacent to the fractures) has considerable potential in fractured systems.

Randall S. Seright

2004-09-30

50

CONFORMANCE IMPROVEMENT USING GELS  

Energy Technology Data Exchange (ETDEWEB)

This technical progress report describes work performed from June 20 through December 19, 2001, for the project, ''Conformance Improvement Using Gels''. Interest has increased in some new polymeric products that purport to substantially reduce permeability to water while causing minimum permeability reduction to oil. In view of this interest, we are currently studying BJ's Aqua Con. Results from six corefloods revealed that the Aqua Con gelant consistently reduced permeability to water more than that to oil. However, the magnitude of the disproportionate permeability reduction varied significantly for the various experiments. Thus, as with most materials tested to date, the issue of reproducibility and control of the disproportionate permeability remains to be resolved. Concern exists about the ability of gels to resist washout after placement in fractures. We examined whether a width constriction in the middle of a fracture would cause different gel washout behavior upstream versus downstream of the constriction. Tests were performed using a formed Cr(III)-acetate-HPAM gel in a 48-in.-long fracture with three sections of equal length, but with widths of 0.08-, 0.02-, and 0.08-in., respectively. The pressure gradients during gel extrusion (i.e., placement) were similar in the two 0.08-in.-wide fracture sections, even though they were separated by a 0.02-in.-wide fracture section. The constriction associated with the middle fracture section may have inhibited gel washout during the first pulse of brine injection after gel placement. However, during subsequent phases of brine injection, the constriction did not inhibit washout in the upstream fracture section any more than in the downstream section.

Randall S. Seright

2002-02-28

51

Design of Autonomous Gel Actuators  

Directory of Open Access Journals (Sweden)

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.

Shuji Hashimoto

2011-01-01

52

Design of Autonomous Gel Actuators  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 c...

Shingo Maeda; Yusuke Hara; Satoshi Nakamaru; Shuji Hashimoto

2011-01-01

53

Review of Fricke gel dosimeters  

Energy Technology Data Exchange (ETDEWEB)

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.

Schreiner, L J [Kingston Regional Cancer Centre, Queen' s University, Kingston (Canada)

2004-01-01

54

Transdermal delivery of paeonol using cubic gel and microemulsion gel  

Directory of Open Access Journals (Sweden)

Full Text Available Maofu Luo1,2, Qi Shen1, Jinjin Chen11School of Pharmacy, Shanghai Jiao Tong University, Shanghai, 2Jiangxi University of Traditional Chinese Medicine, Nanchang, People’s Republic of ChinaBackground: 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.Keywords: microemulsion gel, cubic gel, transdermal delivery, paeonol

Chen J

2011-08-01

55

Structure of mineral gels  

International Nuclear Information System (INIS)

Small Angle Neutron Scattering (SANS) measurements have been performed to investigate the nanoscale structure of materials of the systems xTiO2-(1-x)SiO2 and xZrO2-(1-x)SiO2 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)

1999-03-01

56

Polymer gel dosimetry technique  

Energy Technology Data Exchange (ETDEWEB)

Recent advances in radiation therapy techniques, including non-coplanar beams, dynamic wedge, multi-leaf collimator, sterotactic radiosurgery, high-dose-rate brachytherapy using remote afterloading and shielded applicators, and heavy-particle beams such as protons, have created a need for three-dimensional, tissue-equivalent dosimeters, capable of recording time-integrated dose distributions with high spatial resolution and accuracy, and independent of energy and dose rate. All these requirements are met by the recently developed polymer gel dosimetry technique, based on radiation induced formation of polymer microparticles in a tissue-equivalent gel. A permanent image of the dose distribution is encoded in the gel as the distribution of its optical turbidity and of the NMR relaxation rates of the water protons in the gel. Three dimensional dose distributions can be measured using magnetic resonance imaging or optical transmission tomography. The prototype gel, called BANG{trademark}, is now being tested at several hospital sites throughout the U.S. and Europe.

Maryanski, M.J.

1995-12-31

57

Sol-gel ionics  

Energy Technology Data Exchange (ETDEWEB)

The sol-gel synthesis of metal oxides offers new possibilities in the field of solid state ionics. The chemical design of molecular precursors allows a better control of the polymerization process so that taylor-made materials could be obtained. New hybrid organic-inorganic compounds exhibit high ionic conductivities and could be used as electrolytes. Oxide gels are actually particle hydrates. Water adsorption and dissociation at the oxide-water interface are responsible for their properties as ion exchangers or fast proton conductors. Colloidal particles are very small so that the large solid-liquid interface provides improved electrochemical properties which can be used for making reversible cathodes or electrochromic devices. The sol-gel deposition of thin coatings of large area could open the possibility to make multilayer micro-ionic devices. (orig.).

Livage, J. (Chimie de la Matiere Condensee, Univ. Pierre et Marie Curie, 75 - Paris (France))

1992-02-01

58

Polymer gel dosimetry  

Energy Technology Data Exchange (ETDEWEB)

Polymer gels are chemical dosimeters based on dose dependent radiation-induced polymerization and cross-linking of monomers in an irradiated volume. The changes are spatially localized in the volume by incorporating the initial monomers in an aqueous gel matrix in the dosimeter and can be probed by various imaging techniques such as magnetic resonance imaging (MRI), x-ray computed tomography (CT), and optical CT. As they are chemical dosimeters, polymer gels are sensitive to preparation conditions. The three dimensional dose readout is sensitive to the imaging modality and also to the technical conditions in use during specific scans. This brief article is intended to present an introduction to these points which need to be taken into account as one attempts to establish this dosimetry in the clinic.

Schreiner, L J; Olding, T; McAuley, K B, E-mail: John.Schreiner@krcc.on.c

2010-11-01

59

Gel-silica science  

Energy Technology Data Exchange (ETDEWEB)

Sol-gel techniques can be used to produce two new types of optical silicas, termed Type V for the full density material and Type VI for the optically transparent porous material. This paper summarizes the processing differences between these six types of commercial silicas. The primary emphasis of this paper is to discuss the scientific basis for the processing of Types V and VI optical silica. First, however, the use of sol-gel processing of other systems will be briefly reviewed. The controlled hydrolysis of alkoxides has also been used to produce submicrometer TiO{sub 2}, doped TiO{sub 2} (17), ZrO{sub 2} (18), doped ZrO{sub 2} (18), doped SiO{sub 2} (19), SrTiO{sub 3} (20), and corderite (20) powders. Emulsions have been employed to produce spherical powders of mixed cation oxides, such as yttrium aluminum garnets (YAG) and many other systems (20). Sol-gel powder processes have also been applied to fissile elements (21) where spray form sols UO{sub 2}, and rigid gel spheres of UO-PuO{sub 2} are formed during passage through a column of heated liquid. Both crystalline and vitreous ceramic fibers have been prepared using the sol-gel method. Compositions include TiO{sub 2}-SiO{sub 2} and ZrO{sub 2}-SiO{sub 2} glass fibers (22), high purity SiO{sub 2} waveguide fibers (23), Al{sub 2}O{sub 3}, ZrO{sub 2}, ThO{sub 2}, MgO, TiO{sub 2}, ZrSiO{sub 4}, 3AlO{sub 3}-2SiO{sub 2} fibers (24). Sol-gel derived alumina grains are important commercial products (25).

Hench, L.L.; Vasconcelos, W. (Advanced Materials Research Center, Univ. of Florida, Gainesville, FL (US))

1990-01-01

60

3D MR gel dosimetry with lung equivalent gel; 3D MR-Gel-Dosimetrie mit lungenaequivalentem Gel  

Energy Technology Data Exchange (ETDEWEB)

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{sup 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.) [Deutsch] Die MR-Gel-Dosimetrie zur Verifikation komplexer 3D-Bestrahlungsplaene wurde bislang ausschliesslich in homogenen Phantomen durchgefuehrt. Auf dem Wege zum Bau eines inhomogenen Humanoid-Gel-Phantoms wurde ein lungenaequivalentes Gel mit der Dichte 0,4 g/cm{sup 3} entwickelt. Erste Messungen zeigen ein um den Faktor 1,55 hoeheres Ansprechvermoegen in dem low-density-Gel (LD-Gel). Der Vergleich einer gemessen Dosisverteilung in einem Gel/LD-Gel/Gel Schichtphantom als einfaches Thoraxmodell mit Monte-Carlo-Rechnungen zeigt eine gute Uebereinstimmung innerhalb 5%. Ausserdem wurden Untersuchungen zur Messgenauigkeit des Kernspintomographen im Rahmen der nun ausschliesslich digitalen Auswertung mit Hilfe des Programms MRD (MR-Dosimetrie) durchgefuehrt. Es zeigt sich, dass eine Artefaktkorrektur auf der Basis einer Messung des unbestrahlten Phantoms bei grossen Fricke-Gel-Phantomen notwendig ist. (orig.)

Scherer, J.; Solleder, M.; Schiessl, I.; Bogner, L.; Herbst, M. [Klinik und Poliklinik fuer Strahlentherapie und Radioonkologie, Regensburg Univ. (Germany)

1998-12-31

 
 
 
 
61

Sol-gel processing  

Energy Technology Data Exchange (ETDEWEB)

Sol-gel processing techniques using colloidal hydrous oxide intermediates can be used to prepare inorganic oxides of very high density. First applied to the fabrication of oxide fuel for nuclear reactors, the techniques are being used increasingly to produce a range of materials of controlled shape, density and porosity for non-nuclear applications in the field of ceramics.

Woodhead, J.L.; Segal, D.L. (UKAEA Atomic Energy Research Establishment, Harwell. Chemistry Div.)

1984-04-01

62

Gel filtration chromatography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Gel-filtration chromatography is a popular and versatile technique that permits the effective separation of proteins and other biological molecules in high yield. Here, the basis of the method is described and typical matrix types are contrasted. The selection of suitable operating conditions and applications of the method are also discussed.

O Fagain, Ciaran; Cummins, Phil; O Connor, Brendan

2011-01-01

63

Running an Agarose Gel  

Science.gov (United States)

This video from CUNY Kingsborough Community College shows the process of running an agarose gel. The video describes the process step by step and would be easy to replicate in a laboratory setting. Running time for the video is 2:52.

Hinkley, Craig

2013-06-17

64

Calcium tartrate gel.  

Science.gov (United States)

A method for preparation of a gel for chromatography has been developed. The adsorbent is calcium tartrate treated with potassium phosphate. By changing the temperature of synthesis (10-65 degrees C) and concentration of the salts (calcium chloride and sodium potassium tartrate) from 0.3 to 3.0 M, we have been able to prepare adsorbent crystals of definite sizes in the range 35-200 microns. In all cases, for synthesis of adsorbent, the Ca2+/K+Na+ ratio was greater than 1. After treatment of calcium tartrate crystals with 0.075-1.5 M potassium phosphate at 80-100 degrees C and pH 8.5-9.0, an appropriate chromatographic adsorbent was prepared. The chromatographic properties of calcium tartrate gel have been studied. The adsorbent permits flow rates of 25-150 ml/h, depending on the particle size. The capacity of calcium tartrate gel for binding BSA, RNA, and DNA was similar to that of Tiselius' hydroxyapatite (A. Tiselius, S. Hjerten, O. Levin (1956) Arch. Biochem. Biophys. 65, 132-155). The spheric shape of gel particles permits uniform and compact packing of adsorbent under the conditions of column chromatography. PMID:2757203

Akhrem, A A; Drozhdenyuk, A P

1989-05-15

65

Electrochemical Light-Emitting Gel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Light-emitting gel, a gel state electroluminescence material, is reported. It is composed of a ruthenium complex as the emitter, an ionic liquid as the electrolyte, and oxide nanoparticles as the gelation filler. Emitted light was produced via electrogenerated chemiluminescence. The light-emitting gel operated at low voltage when an alternating current was passed through it, regardless of its structure, which is quite thick. The luminescence property of the gel is strongly affected by nanopar...

Nobuyuki Itoh

2010-01-01

66

Active Polymer Gel Actuators  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Many kinds of stimuli-responsive polymer and gels have been developed and applied to biomimetic actuators or artificial muscles. Electroactive polymers that change shape when stimulated electrically seem to be particularly promising. In all cases, however, the mechanical motion is driven by external stimuli, for example, reversing the direction of electric field. On the other hand, many living organisms can generate an autonomous motion without external driving stimuli like self-beating of he...

Shingo Maeda; Yusuke Hara; Ryo Yoshida; Shuji Hashimoto

2010-01-01

67

The Gel Generator option  

International Nuclear Information System (INIS)

The development of a national policy for guaranteeing an ample supply of 99mTc 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 99Mo generator versus the direct cyclotron production of 99mTc. There is a third option (also neutron ?-based), an alternative to the fission 99Mo generator, which ought not be overlooked. The application of low specific activity (n,?) 99Mo 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 99mTc 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 99mTc demand. (author)

1999-02-01

68

Crosslinked Acid Gel  

Energy Technology Data Exchange (ETDEWEB)

A new, stable, crosslinked acid gel has been developed for fracture acidizing applications. This crosslinked acid can be prepared from acid strengths up to 28 per cent hydrochloric acid. Laboratory tests show the fluid possesses high viscosity and shear stability at temperatures up to 93/sup 0/C (200/sup 0/F). Viscosity of the acid gel can be reduced in a controlled manner by a chemical additive to aid well cleanup. Rheological data were obtained in a newly designed viscometer, the pressure rheometer. The rheometer used a bob/cup arrangement to measure the fluid rheology and the fluid was fed to the gap between the bob and cup. A desired pressure was directly applied to the test fluid without using a second pressurizing fluid such as mineral oil or nitrogen. In addition to its viscosity characteristics, the acid reactivity of the crosslinked acid gel with limestone specimens, in a dynamic reaction setup, is drastically retarded. The crosslinked fluid is also residue free in live or spent acid minimizing formation damage. This newly developed fracture acidizing fluid possesses other important fracturing fluid properties such as low friction pressure, good proppant transport characteristics, and good fluid loss control. Results from computer simulation of fracture acidizing treatments indicate deeper penetration is achieved by the crosslinked acid compared to unaltered acid. Field results also show that in several carbonaceous formations, production could be substantially improved if stimulated with this crosslinked acid.

Sedillo, L.P.; Knoll-Davis, S.

1984-01-01

69

Detecção de Erwinia psidii via enriquecimento em extrato de folhas de goiabeira e imunodifusão radial dupla / Detection of Erwinia psidii through enrichment in guava leaf extract and double radial immunodiffusion  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Uma das principais doenças que afetam a produção de goiaba no Brasil é a seca-dos-ponteiros, causada pela bactéria Erwinia psidii, cuja disseminação é favorecida por mudas contaminadas. O desenvolvimento de métodos diagnósticos mais eficazes poderia reduzir a disseminação da bactéria no país. Consid [...] erando a necessidade de se disponibilizar um método eficiente e simples para a detecção de E. psidii em material de propagação, foi objetivo desse trabalho produzir antissoros policlonais específicos contra a bactéria e desenvolver um método de detecção utilizando o enriquecimento da população bacteriana em extrato de folhas de goiabeira seguido de imunodifusão radial dupla. Um antissoro foi produzido contra a estirpe tipo da bactéria IBSBF 435 (ICMP 8426, NCPPB 3555), avaliado quanto à eficiência e especificidade e utilizado na determinação dos limiares de detecção da mesma. O antissoro As15-1 reagiu positivamente com todos as estirpes testadas de E. psidii, não reagindo com estirpes de outros gêneros e espécies de bactérias fitopatogênicas e apresentou reação cruzada com dois isolados não patogênicos da flora da goiabeira. O crescimento da população bacteriana no extrato de folhas foi observado após 12 h de incubação a partir de populações iniciais de 10³, 10(5) e 10(7) ufc/mL, até 60 h. A partir de 12 h, já foi possível detectar E. psidii por enriquecimento e imunodifusão radial nas amostras com populações iniciais de 10(7) ufc/mL e a partir de 36 h, detectou-se a bactéria mesmo em amostras com populações iniciais de 10³ ufc/mL. Considerando a possibilidade de falsos positivos, é recomendável associar outros métodos diagnósticos ao método aqui proposto. Abstract in english One of the most important diseases affecting guava production in Brazil is bacterial blight, caused by the bacterium Erwinia psidii. Pathogen dissemination often occurs through contaminated propagating plant material. The development of more effective diagnostic methods may reduce pathogen dissemina [...] tion in the country. Considering the need for a reliable and simple method for detecting the pathogen in plant material, the objectives of this study were to produce E. psdii-specific polyclonal antibodies and to develop a detection method using bacterial population enrichment on guava leaf extracts followed by double radial immunodiffusion. The antiserum was produced against the E. psidii type strain IBSBF 435 (ICMP 8426, NCPPB 3555) and its efficiency, specificity and sensitivity threshold were determined. The antiserum As15-1 was tested with strains of several plant-pathogenic bacteria and reacted positively with all strains of E. psidii, although cross reactions were detected with two non-pathogenic isolates from guava flora. Bacterial multiplication on leaf extracts was observed 12 h after incubation from initial populations of 10³, 10(5) and 10(7) ufc/mL, up to 60 h. After 12 h it was already possible to detect E. psidii in samples with starting populations of 10(7) cfu/mL. After 36 h, the enrichment technique allowed the detection of E. psidii using double radial immunodiffusion in samples with populations as low as 10³ cfu/mL. Considering the possibility of false positives it is desirable to associate other diagnostic methods with the method proposed in this study.

Ana Cristina O., Teixeira; Marisa A.S.V., Ferreira; Abi S.A., Marques.

70

Ocular tolerance of sertaconazole gel.  

Science.gov (United States)

The in vitro and in vivo tolerance of sertaconazole gel, a new topical azole antifungal, was studied. Ketoconazole gel (Panfungol) was used as a reference substance. The methods applied for tolerance assessment were the bovine corneal opacity and permeability test for the in vitro assay and a modified Draize test for the in vivo assay. The results obtained show that both substances can be classified as slightly irritant and with acceptable tolerance. However, unlike ketoconazole gel, sertaconazole gel did not cause a positive lesion index in vivo. Ketoconazole was 5.25 times more irritant in vitro than sertaconazole gel, whose effect was similar to that of saline solution. Consequently, the negligible irritant effect of sertaconazole gel on a type of epithelium that is extremely sensitive, i.e. the cornea, confirms the good tolerance of this new antifungal gel on other structures such as the skin and mucous membranes. PMID:8786760

Romero, A; Grau, M T; Villamayor, F; Zapatero, J; Mayordomo, L; Tortajada, A; Sacristán, A; Ortiz, J A

1996-01-01

71

All optical gel memory  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have studied the behavior of organic molecules (Rhodamine 640) that are encaged in a matrix synthesized by the sol-gel process. By applying a strong optical-polarized electric field, we can control the alignment of the molecules within the sample and locally create a birefringent effect. Using this sample in a Kerr experiment, we obtained a transmission ratio of 6%. Since the birefringent effect lasts at least several days, this type of sample could be used in an optical process for storag...

Canva, Michael; Le Saux, Gilles; Georges, Patrick; Brun, Alain; Chaput, Fre?de?ric; Boilot, Jean-pierre

1992-01-01

72

Clarification Procedure for Gels  

Science.gov (United States)

Procedure developed to obtain transparent gels with consistencies suitable for crystal growth, by replacing sodium ions in silicate solution with potassium ions. Clarification process uses cation-exchange resin to replace sodium ions in stock solution with potassium ions, placed in 1M solution of soluble potassium salt. Slurry stirred for several hours to allow potassium ions to replace all other cations on resin. Supernatant solution decanted through filter, and beads rinsed with distilled water. Rinsing removes excess salt but leaves cation-exchange beads fully charged with potassium ions.

Barber, Patrick G.; Simpson, Norman R.

1987-01-01

73

Gel for retarding water flow  

Energy Technology Data Exchange (ETDEWEB)

A process is described for forming, in situ, a gel in a porous structure comprising: introducing an effective amount of a gel-forming composition into pores of a porous structure; and allowing the gel-forming composition to form a gel in the pores. The thusly formed gel is capable of being formed by reacting an aqueous solution comprising a first substance selected from the group consisting of polyvinyl alcohols, polyvinyl alcohol copolymers, and mixtures thereof. A second substance comprises aldehyde operable for effecting a crosslinking reaction with the first substance, wherein the total amount of aldehyde is from about 0.005 to about 2.5% of the weight of the gel.

Marrocco, M.L.

1987-05-12

74

Foam and gel decontamination techniques  

Energy Technology Data Exchange (ETDEWEB)

The Savannah River Site is investigating decontamination technology to improve current decontamination techniques, and thereby reduce radiation exposure to plant personnel, reduce uptake of radioactive material, and improve safety during decontamination and decommissioning activities. When decontamination chemicals are applied as foam and gels, the contact time and cleaning ability of the chemical increases. Foam and gel applicators apply foam or gel that adheres to the surface being decontaminated for periods ranging from fifteen minutes (foam) to infinite contact (gel). This equipment was started up in a cold environment. The desired foam and gel consistency was achieved, operators were trained in its proper maintenance and operation, and the foam and gel were applied to walls, ceilings, and hard to reach surfaces. 17 figs.

McGlynn, J.F.; Rankin, W.N.

1989-01-01

75

THE PROPERTIES OF CARRAGEENAN GELS  

Directory of Open Access Journals (Sweden)

Full Text Available The article presents the results of studies on the functional properties of carrageenan, depending on the concentration of sodium chloride and xanthan in gels. It is established that the main factors in the syneresis of carrageenan gels are its concentration, the presence of ions and gums in solution. If using sodium chloride there is a change in the structure of mesh of the resulting gel, which leads to an increase in syneresis.

Grubnik I.M., Gladukh Ye.V., Chernyaev S.V.

2012-04-01

76

Polyoxometalate-based Supramolecular Gel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Self-assemblyings of surfactant-encapsulated Wells-Dawson polyoxometalates (SEPs) nanobuilding blocks in butanone and esters yielded supramolecular gels showing thermo and photo responsive properties. The gels can be further polymerized if unsaturated esters were used and subsequently electrospinned into nanowires and non-woven mats. The as-prepared non-woven mats have a Young's modulus as high as 542.55?MPa. It is believed that this supramolecular gel is a good platform for polyoxometalate...

He, Peilei; Xu, Biao; Liu, Huiling; He, Su; Saleem, Faisal; Wang, Xun

2013-01-01

77

Polyoxometalate-based Supramolecular Gel  

Science.gov (United States)

Self-assemblyings of surfactant-encapsulated Wells-Dawson polyoxometalates (SEPs) nanobuilding blocks in butanone and esters yielded supramolecular gels showing thermo and photo responsive properties. The gels can be further polymerized if unsaturated esters were used and subsequently electrospinned into nanowires and non-woven mats. The as-prepared non-woven mats have a Young's modulus as high as 542.55 MPa. It is believed that this supramolecular gel is a good platform for polyoxometalates processing.

He, Peilei; Xu, Biao; Liu, Huiling; He, Su; Saleem, Faisal; Wang, Xun

2013-05-01

78

Aqueous gel blasting agent  

Energy Technology Data Exchange (ETDEWEB)

A method of manufacturing a water-resistant extrudable aqueous gel blasting agent is claimed. A stabilizing amount of finely divided water-soluble hydroxy-substituted thickening agent is mixed with a substantial proportion (between one-tenth and three-fourths of the total amount) of particulate solid ammonium nitrate to yield a substantially uniform mixture of particulate solids. To this mixture is added at least 6% by weight hexamethylenetetramine, sufficient nitric acid (2 to 5% by weight) to yield a pH between 3.5 and 6.0, and sufficient water to produce 10 to 13% by weight of the total composition. The remainder of the solid particulate ammonium nitrate, sufficient to yield a total ammonium nitrate content of 75 to 85% by weight, is added. After a period of time sufficient to permit the thickening effect to become substantially complete a cross-linking effect agent is added to produce a gelling effect, yielding an extrudable aqueous gel blasting agent.

Gehrig, N.E.; Marhofer, E.G.

1980-12-18

79

Radiotherapy Gel Dosimetry: Development and Application of Normoxic Polymer Gels  

International Nuclear Information System (INIS)

In many radiotherapy applications, true three-dimensional dosimetry with good spatial resolution that can be achieved in a single measurement would be of great value. Polymer gel dosimetry fulfils many of the demands on such a system. In this study, methods to facilitate the implementation of gel dosimetry have been investigated. A new type of polymer gel, for which the response to absorbed dose is not negatively affected even if manufacturing is undertaken at normal levels of oxygen, called normoxic gel, was studied. The concept of percentage dose resolution was introduced to enable optimization of gel compositions for use in relative dosimetry applications. This concept was applied to demonstrate the effects of varying the gel composition on gel performance. Comparison between data obtained using magnetic resonance imaging and FT-Raman spectroscopy indicated that not all water protons attached to the polymer are accessible for exchange of magnetization with other proton groups. Dose response characteristics were investigated for a polymer gel containing the antioxidant tetrakis(hydroxymethyl)phosphonium. The transversal relaxation time (R2) versus dose response increased with increasing amounts of monomer, while no systematic dependence on antioxidant concentration was observed. The investigated normoxic gel exhibited a dependence on temperature during irradiation, leading to differences in absolute R2 as well as deviations in relative depth dose curves. It was suggested that the deviation in R2 can be attributed to structural differences in the polymer matrix, caused by varying polymerisation temperature. A linear relationship between absorbed dose and optical attenuation coefficient was observed, which demonstrates the potential for evaluation using light transmission measurements. Low-density gel was manufactured by mixing normal density normoxic gel with Styrofoam spheres. A linear correlation between R2 and dose was observed for doses up to 15 Gy. Possible dose response dependence on linear energy transfer (LET) was investigated using proton beam absorbed dose measurements. An increased LET with depth was closely followed by a decrease in relative detector sensitivity, indicating that the response of this type of gel detector is dependent on LET. No significant effects were observed for LET < 2.5 keV/mm, indicating that the detector response would not be altered in the range of LET values expected for photons or electrons in a clinical range of energies. The feasibility of using normoxic gel for intensity-modulated radiation therapy verification was investigated. Good agreement between treatment planning system calculations and measured data was obtained. For the planning target volume, the calculated and the measured mean relative dose was 96.8±2.5% (±1 SD) and 98.6±2.2%, respectively. The results indicated great potential for intensity-modulated radiation therapy verification using normoxic polymer gel

2004-01-01

80

Electromechanical nonionic gels  

International Nuclear Information System (INIS)

The electrically induced bending of nonionic polyvinyl alcohol gels, bending over 900 within 100 ms, is the fastest motion in the field of electroactuation of polymers. This rapid bending produces initial mechanical vibrations followed by a durable displacement that contrasts highly with the relaxation observed with elastomer- and polyelectrolyte-based actuators. Here, we characterize the bending process using video imaging and laser detecting technology and establish a physical model for the electromechanical conversion, based on our observation of an induced solvent migration. Our results show excellent agreement between the measurements and calculations. This study provides general rules for understanding the electrically induced bending of isotropic dielectrics and may also shed light on nonmuscular biological engines

2008-02-01

 
 
 
 
81

Vanadium pentoxide gels  

International Nuclear Information System (INIS)

This paper reports on cryogenic transmission electron Microscopy (cry-TEM) and rheological characterization conducted in order to understand structural development of vanadium pentoxide gels during processing. Sols were prepared by ion exchange from sodium metavanadate solutions. Cryo-TEM revealed that fine threads about 1.5nm wide initially form and grow into ribbons approximately 25nm wide and at least 1000nm long. The threads appear to self assembly into the ribbons. During this structural development, the dynamic viscosity increased. Upon steady shearing of the sols, the system exhibited thixotropy, i.e. the viscosity decreased with time under constant shear stress and subsequently rheopexy, the viscosity increased with time. Comparison of the structure before and after shearing indicated that during the rheological experiments aggregation of small particles or fragments was occurring

1990-04-16

82

Nanocrystal/sol-gel nanocomposites  

Energy Technology Data Exchange (ETDEWEB)

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

Petruska, Melissa A. (Los Alamos, NM); Klimov, Victor L. (Los Alamos, NM)

2012-06-12

83

Nanocrystal/sol-gel nanocomposites  

Energy Technology Data Exchange (ETDEWEB)

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.

Petruska, Melissa A. (Los Alamos, NM); Klimov, Victor L. (Los Alamos, NM)

2007-06-05

84

Silica gel in organic synthesis  

Energy Technology Data Exchange (ETDEWEB)

The data on the use of silica gel in organic synthesis are presented. Some specific features of cyclisation (both intra- and intermolecular) reactions, rearrangements, reduction, oxidation, condensation, formylation, hydration and dehydration, protection of functional groups, etc., in the presence of silica gel, are discussed. The bibliography includes 96 references.

Banerjee, Ajoy K; Laya, M S; Vera, W J [Centre of Chemistry, Venezuelan Scientific Research Institute, Caracas (Venezuela, Bolivarian Republic of)

2001-11-30

85

Chemical Gel for Surface Decontamination  

Energy Technology Data Exchange (ETDEWEB)

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

Jung, Chong Hun; Moon, J. K.; Won, H. J.; Lee, K. W.; Kim, C. K. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2010-10-15

86

Risk factors and presence of antibodies to Brucella canis and smooth Brucella in dogs from the municipality of Araguaína, Tocantins, Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available Canine brucellosis is an infectious disease of worldwide distribution that can affect dogs, wild canids and man. It is caused by Brucella canis, but dogs can also be infected by smooth Brucella such as B. abortus and B. suis. Due to the increasing importance of dogs in our society, to the scarcity of information about canine brucellosis in the country and its zoonotic character, the aims of the present study were (i to conduct a survey on the infection by B. canis and smooth Brucella in dogs from the municipality of Araguaína, Tocantins, Brazil, and (ii to evaluate the risk factors associated with these infections. Sera from 241 dogs were analyzed by agar gel immunodiffusion (AGID to detect B. canisantibodies, and Buffered Acidified Plate Antigen test (BAPA and fluorescence polarization assay (FPA to detect antibodies to smooth Brucella. From the 241 tested dogs, 132 reacted in the AGID and 128 reacted in the BAPA, but only two were positive in FPA. The seroprevalences of B. canis and smooth Brucella infections in dogs in Araguaína were 54.77% (95% CI: 48.25 to 61.17% and 0.83% (95% CI: 0.10 to 2.97%, respectively. The analysis of risk factors showed associations between B. canis infection and vaccination against leptospirosis, and between B. canis infection and use of manufactured food. In conclusion, data from the present study showed a low prevalence of infection by smooth Brucella and a widespread and high prevalence of infection by B. canis in the city of Araguaína, Tocantins, Brazil.

Jordana Almeida Santana

2013-12-01

87

Clinical applications of gel dosimeters  

Energy Technology Data Exchange (ETDEWEB)

This short communication raises some issues regarding the use of gel dosimeters in a clinical setting. Further, the need for improvements to attract future interest is discussed. The gel dosimetry method is unique owing to its 3D properties. This is not fully utilised in the present publications. New methods to evaluate and compare dose distributions are needed to further develop the dosimeter gel systems. Undoubtedly there is a continuous need for 3D dosimetry as radiation therapy applications become more and more complex.

Baeck, Sven AJ [Department of Medical Radiation Physics, Lund University, Malmoe University Hospital (Sweden)], E-mail: Sven.Back@med.lu.se

2009-05-01

88

Transdermal delivery of paeonol using cubic gel and microemulsion gel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Maofu Luo1,2, Qi Shen1, Jinjin Chen11School of Pharmacy, Shanghai Jiao Tong University, Shanghai, 2Jiangxi University of Traditional Chinese Medicine, Nanchang, People’s Republic of ChinaBackground: 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...

Luo M; Shen Q; Chen J.

2011-01-01

89

Padronização do Elisa indireto e Western Blot para diagnóstico da artrite-encefalite caprina / Standardization of indirect Elisa and Western Blot for diagnosis of Caprine Arthritis-Encephalitis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A artrite-encefalite caprina (CAE) é diagnosticada rotineiramente pela técnica de imunodifusão em gel de agarose (IDGA), que é considerada pouco sensível. Objetivou-se com este estudo padronizar testes de Elisa-i e Western Blot (WB) para diagnóstico precoce de anticorpos em caprinos contra CAEV e co [...] mparar os resultados obtidos nesses testes com a prova de IDGA. Para a padronização dos testes Elisa-i e WB, utilizaram-se diferentes concentrações e diluições de antígeno, soros e conjugado. No Elisa-i, adotaram-se microplacas rígidas com 96 poços, sendo a combinação de concentração de 0,5µg/poço de antígeno e diluições de 1:100 de soro e 1:1500 de conjugado a que apresentou melhor resultado. No WB foram utilizadas membranas de nitrocelulose, definindo-se as diluições de 1:50 de soro e 1:15000 de conjugado. Para avaliar o desempenho das técnicas, 222 amostras de soro caprino foram testadas e os dados obtidos foram comparados com o IDGA. A sensibilidade e a especificidade do Elisa-i/IDGA, WB/IDGA e WB/Elisa-i foram de 70% e 91%, 100% e 72,6%, 84,6% e 76,5%, concomitantemente. O índice Kappa desses testes foi de 0,35, 0,2 e 0,36, respectivamente. As técnicas de Elisa-i e WB apresentaram-se mais sensíveis que a IDGA, podendo ser utilizadas como ferramentas para o diagnóstico precoce da CAE. Abstract in english Caprine arthritis-encephalitis (CAE) is routinely diagnosed with the Agarose Gel Immunodiffusion (AGID) technique, which is considered to have low sensitivity. The objective of this study was to standardize testing i-Elisa and Western Blot for early detection of antibodies against CAEV in goats and [...] compare the results obtained in these tests with proof of AGID. For standardization of i-Elisa and WB, different concentrations and dilutions of antigen, sera and conjugate were used. In the i-Elisa, rigid microplate with 96 wells was adopted, and the combination that showed the best result was a concentration of 0.5µg/ well of antigen and dilutions of the serum of 1:100 and conjugate of 1:1500. In the WB nitrocellulose membranes were used, and the dilutions of the serum were defined at 1:50 and conjugate at 1:15000. To evaluate the performance of the techniques, 222 goat serum samples were tested and the data were compared with the AGID. The sensitivity and specificity of Elisa-i/IDGA, WB/AGID and WB/Elisa-i were 70% and 91%, 100% and 72.6%, 84.6% and 76.5%, concomitantly. The Kappa index of these tests was 0.35, 0.2 and 0.36, respectively. The i-Elisa and WB techniques were more sensitive than the AGID and can be used as tools for early diagnosis of CAE.

A.S., Rodrigues; R.L.L., Brito; R.R., Pinheiro; R.P., Dias; S.M., Alves; T.S., Souza; K.C., Souza; D.A.A., Azevedo; A., Andrioli; D.C.T., Magalhães; M.F.S., Teixeira.

90

Gel placement in production wells  

Energy Technology Data Exchange (ETDEWEB)

Straightforward applications of fractional-flow theory and material-balance calculations demonstrate that, if zones are not isolated during gel placement in production wells, gelant can penetrate significantly into all open zones, not just those with highwater saturations. Unless oil saturations in the oil-productive zones are extremely high, oil productivity will be damaged even if the gel reduces water permeability without affecting oil permeability. Also, in field applications, capillary pressure will not prevent gelant penetration into oil-productive zones. An explanation is provided for the occurrence of successful applications of gels in fractured wells produced by bottomwater drive. With the right properties, gels could significantly increase the critical rate for water influx in fractured wells.

Liang, Jenn Tai; Lee, R.L.; Seright, R.S. (New Mexico Inst. of Mining and Technology, Socorro, NM (United States))

1993-11-01

91

PREPARATION AND CHARACTERIZATION OFCHITOSAN GELS  

Directory of Open Access Journals (Sweden)

Full Text Available The main goal of this work is the preparation and characterization of gelsusingchitosan for further formulation and topic applications. To achieve this goal several gels from pharmaceutical quality chitosan of low( Mw= 72.180 g/mol andmedium.( Mw= 103.000 g/mol molecular weight with a 4% w/w were employed.The prepared gels were characterized by infrared spectroscopy, scanning electron microscopy andreological analyses.The spectroscopic study shows no great difference between both gels and most of chitosan bands are exhibited.The reological studies shows that both gels exhibit a non newtonian flow independent of the time, with seudoplastic for low molecular weight chitosan and plastic behavior for the medium molecular weight

MARCOS FERNÁNDEZ

2006-12-01

92

Raft Instability of Biopolymer Gels  

CERN Multimedia

Following recent X-ray diffraction experiments by Wong, Li, and Safinya on biopolymer gels, we apply Onsager excluded volume theory to a nematic mixture of rigid rods and strong ``$\\pi/2$'' cross-linkers obtaining a long-ranged, highly anisotropic depletion attraction between the linkers. This attraction leads to breakdown of the percolation theory for this class of gels, to breakdown of Onsager's second-order virial method, and to formation of heterogeneities in the form of raft-like ribbons.

Borukhov, I

2001-01-01

93

Microbubble tunneling in gel phantoms  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Insonified microbubbles were observed in vessels within a gel with a Young’s modulus similar to that of tissue, demonstrating shape instabilities, liquid jets, and the formation of small tunnels. In this study, tunnel formulation occurred in the direction of the propagating ultrasound wave, where radiation pressure directed the contact of the bubble and gel, facilitating the activity of the liquid jets. Combinations of ultrasonic parameters and microbubble concentrations that are relevant f...

Caskey, Charles F.; Qin, Shengping; Dayton, Paul A.; Ferrara, Katherine W.

2009-01-01

94

Topical Review: Polymer gel dosimetry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Baldock, C.; Deene, Y.; Doran, S.; Ibbott, G.; Jirasek, A.; Lepage, M.; Mcauley, K. B.; Oldham, M.; Schreiner, L. J.

2010-01-01

95

Alternative imaging modalities for polymer gel dosimetry  

Energy Technology Data Exchange (ETDEWEB)

This review summarizes recent work in the area of imaging polymer gel dosimeters using x-ray CT imaging, ultrasound, and radiation-induced changes in gel mechanical properties. In addition, recent work in the area of Raman tomographic imaging of canine bone, in conjunction with past efforts in Raman imaging of polymer gel dosimeters, raises new possibilities for new polymer gel imaging techniques.

Jirasek, Andrew, E-mail: jirasek@uvic.c [Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8W 3P6 (Canada)

2010-11-01

96

Prevalence of bluetongue virus antibodies in sheep from Distrito Federal, BrazilPrevalência de anticorpos contra o vírus da língua azul em ovinos do Distrito Federal  

Directory of Open Access Journals (Sweden)

Full Text Available The aims of the present study were to determine the prevalence of bluetongue virus antibodies in sheep from Distrito Federal. Sera from 606 sheep of 18 herds were submitted to the agar-gel immunodiffusion for bluetongue virus antibodies. The prevalences of bluetongue infection found in Distrito Federal were 100% (CI 95%: 84.67 to 100.00 for flocks and 52.37% (389/606 (CI 95%: 35.76 to 68.98 for animals. Thus, data from the present study showed that infection by bluetongue virus is highly widespread in sheep flocks in the Distrito Federal, which intensifies the need for assessments on the impact of this disease in Brazil. O objetivo deste trabalho foi estimar a prevalência de anticorpos contra o vírus da língua azul (BTV em rebanhos ovinos do Distrito Federal. Soros de 606 ovinos, pertencentes a 18 propriedades, foram analisados pela técnica de imunodifusão em ágar gel (AGID, para pesquisa de anticorpos contra o BTV. As prevalências de rebanhos e de animais infectados pelo vírus da língua azul no Distrito Federal foram respectivamente de 100% (IC 95%: 84,67% a 100% e de 52,37% (389/606 (IC 95%: 35,76% a 68,98%. Assim, o presente estudo permite concluir que o vírus da língua azul está amplamente disseminada no rebanho ovino do Distrito Federal.

Aurora Maria Guimarães Gouveia

2012-08-01

97

NMR mechanisms in gel dosimetry  

Energy Technology Data Exchange (ETDEWEB)

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 observed rate is a function of the absorbed dose. In this review I will first develop the fast exchange model for the spin lattice relaxation Fricke gel dosimeter system, as this is conceptually the simpler system. Fundamental concepts such as relaxivity (which specifies the ability of some species to enhance the relaxation of water protons) and chemical yield will be presented. The linear dose relationship for Fricke gel dosimeters, and the reduced dose sensitivity of Fricke dosimeters containing chelators, will be explained. The model will then be extended to the spin-spin relaxation of polymer gel systems and the main differences discussed. The reasons for the enhanced dose sensitivy and dynamic range for spin-spin (R2) rather than spin-lattice (R1) relaxation will be presented.

Schreiner, L J [Departments of Oncology and Physics, Queen' s University (United Kingdom), and Cancer of Centre Southeastern Ontario at KGH, Kingston, Canada, K7L 5P9 (Canada)], E-mail: john.schreiner@krcc.on.ca

2009-05-01

98

Rheology and structure of milk protein gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 that both the fraction whey protein aggregated with the casein particles and whey protein aggregates dispersed in the continuous phase have a large impact on the structural and mechanical properties ...

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

2004-01-01

99

Thixotropic gel for vadose zone remediation  

Energy Technology Data Exchange (ETDEWEB)

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.

Rhia, Brian D. (Augusta, GA)

2011-03-01

100

A model of ideal elastomeric gels for polyelectrolyte gels.  

Science.gov (United States)

The concept of the ideal elastomeric gel is extended to polyelectrolyte gels and verified using a polyacrylamide-co-acrylic acid hydrogel as a model material system. A comparison between mixing and ion osmosis shows that the mixing osmosis is larger than the ion osmosis for small swelling ratios, while the ion osmosis dominates for large swelling ratios. We show further that the non-Gaussian chain effect becomes important in the elasticity of the polymer network at the very large swelling ratios that may occur under certain conditions of pH and salinity. We demonstrate that the Gent model captures the non-Gaussian chain effect well and that it provides a good description of the free energy associated with the stretching of the network. The model of ideal elastomeric gels fits the experimental data very well. PMID:24647731

Li, Jianyu; Suo, Zhigang; Vlassak, Joost J

2014-04-21

 
 
 
 
101

Gel placement in fractured systems  

Energy Technology Data Exchange (ETDEWEB)

This paper examines several factors that can have an important effect on gel placement in fractured systems, including gelant viscosity, degree of gelation, and gravity. For an effective gel treatment, the conductivity of the fracture must be reduced and a viable flow path must remain open between the wellbore and mobile oil in the reservoir. During placement, the gelant that``leaks off`` from the fracture into the rock plays an important role in determining how well a gel treatment will reduce channeling. For a given volume of gelant injected the distance of gelant leakoff is greater for a viscous gelant than for a low-viscosity gelant. In one method to minimize gelant leakoff, sufficient gelation is designed to occur before the gelant leaves the wellbore. The authors investigated this approach in numerous experiments with both fractured and unfractured cores. They studied Cr(III)/acetate/hydrolyzed polyacrylamide (HPAM), resorcinol/formaldehyde, Cr(III)/xanthan, aluminum/citrate/HPAM, and other gelants and gels with various delay times between gelant preparation and injection. Their results suggest both hope and caution concerning the injection of gels into fractured systems.

Seright, R.S. [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States)

1995-11-01

102

Capillary fracture of soft gels  

CERN Document Server

A liquid droplet resting on a soft gel substrate can deform that substrate to the point of material failure, whereby fractures develop on the gel surface that propagate outwards from the contact-line in a starburst pattern. In this paper, we characterize i) the initiation process in which the number of arms in the starburst is controlled by the ratio of surface tension contrast to the gel's elastic modulus and ii) the propagation dynamics showing that once fractures are initiated they propagate with a universal power law $L\\propto t^{3/4}$. We develop a model for crack initiation by treating the gel as a linear elastic solid and computing the deformations within the substrate from the liquid/solid wetting forces. The elastic solution shows that both the location and magnitude of the wetting forces are critical in providing a quantitative prediction for the number of fractures and, hence, an interpretation of the initiation of capillary fractures. This solution also reveals that the depth of the gel is an impo...

Bostwick, Joshua B

2013-01-01

103

Transport properties of incipient gels  

CERN Multimedia

We investigate the behavior of the shear viscosity $eta(p)$ and the mass-dependent diffusion coefficient $D(m,p)$ in the context of a simple model that, as the crosslink density $p$ is increased, undergoes a continuous transition from a fluid to a gel. The shear viscosity diverges at the gel point according to $eta(p)sim (p_c-p)^{-s}$ with $sapprox 0.65$. The diffusion constant shows a remarkable dependence on the mass of the clusters: $D(m,p)sim m^{-0.69}$, not only at $p_c$ but well into the liquid phase. We also find that the Stokes-Einstein relation $Detapropto k_BT$ breaks down already quite far from the gel point.

Jespersen, S N; Jespersen, Sune Norhoj; Plischke, Michael

2003-01-01

104

Fibers from sol-gel  

Energy Technology Data Exchange (ETDEWEB)

The applicability of the sol-gel method to the fiberization of various kinds of oxides, oxycarbides, oxynitrides and nitrides in glassy or crystalline state are reviewed. It was shown that even nonconventional glass fibers of the systems such as Pb0-Ti0{sub 2} with high Ti0{sub 2} content were realized for the first time by the sol-gel method. The incorporation of carbon into the silica glass fiber to form carbidic bonds was found to result in the increment of the heat-treatment temperature, where the maximum tensile strength was attained, to 1200{degrees}C from 800{degrees}C for the carbon-free sol-gel silica glass fiber.

Kamiya, K. [Mie Univ., Mie-ken (Japan)

1995-12-31

105

Antibiotic gels for periodontal disease.  

Science.gov (United States)

Periodontal disease is a major cause of tooth loss. The underlying pathology is inflammation caused by bacterial plaque affecting the supporting structures of the teeth. Conventional treatment involves mechanical debridement of calcified plaque (calculus) by the dentist combined with meticulous oral hygiene by the patient. A more recent approach is to apply antimicrobial drugs locally to the diseased gingival tissue after debridement. Two antibiotic preparations, minocycline 2% gel (Dentomycin-Lederle) and metronidazole 25% gel (Elyzol-Dumex), are now licensed for the treatment of patients with periodontal disease. Are these treatments an advance on conventional therapy? PMID:7635031

1994-06-16

106

Statistical physics of polymer gels  

Science.gov (United States)

This work presents a comprehensive analysis of the statistical mechanics of randomly cross-linked polymer gels, starting from a microscopic model of a network made of instantaneously cross-linked Gaussian chains with excluded volume, and ending with the derivation of explicit expressions for the thermodynamic functions and for the density correlation functions which can be tested by experiments. Using replica field theory we calculate the mean field density in replica space and show that this solution contains statistical information about the behavior of individual chains in the network. The average monomer positions change affinely with macroscopic deformation and fluctuations about these positions are limited to length scales of the order of the mesh size. We prove that a given gel has a unique state of microscopic equilibrium which depends on the temperature, the solvent, the average monomer density and the imposed deformation. This state is characterized by the set of the average positions of all the monomers or, equivalently, by a unique inhomogeneous monomer density profile. Gels are thus the only known example of equilibrium solids with no long-range order. We calculate the RPA density correlation functions that describe the statistical properties of small deviations from the average density, due to both static spatial heterogeneities (which characterize the inhomogeneous equilibrium state) and thermal fluctuations (about this equilibrium). We explain how the deformation-induced anisotropy of the inhomogeneous equilibrium density profile is revealed by small angle neutron scattering and light scattering experiments, through the observation of the butterfly effect. We show that all the statistical information about the structure of polymer networks is contained in two parameters whose values are determined by the conditions of synthesis: the density of cross-links and the heterogeneity parameter. We find that the structure of instantaneously cross-linked gels becomes increasingly inhomogeneous with the approach to the cross-link saturation threshold at which the heterogeneity parameter diverges. Analytical expressions for the correlators of deformed gels are derived in both the long wavelength and the short wavelength limits and an exact expression for the total static structure factor, valid for arbitrary wavelengths, is obtained for gels in the state of preparation. We adapt the RPA results to gels permeated by free labelled chains and to gels in good solvents (in the latter case, excluded volume effects are taken into account exactly) and make predictions which can be directly tested by scattering and thermodynamic experiments. Finally, we discuss the limitations and the possible extensions of our work.

Panyukov, Sergei; Rabin, Yitzhak

1996-05-01

107

Heterogeneous diffusion in a reversible gel  

CERN Multimedia

We introduce a microscopically realistic model of a physical gel and use computer simulations to study its static and dynamic properties at thermal equilibrium. The phase diagram comprises a sol phase, a coexistence region ending at a critical point, a gelation line determined by geometric percolation, and an equilibrium gel phase unrelated to phase separation. The global structure of the gel is homogeneous, but the stress is supported by a fractal network. The gel dynamics is highly heterogeneous and we propose a theoretical model to quantitatively describe dynamic heterogeneity in gels. We elucidate several differences between the dynamics of gels and that of glass-formers.

Hurtado, P I; Kob, W; Hurtado, Pablo I.; Berthier, Ludovic; Kob, Walter

2007-01-01

108

Screening effect on nanostructure of charged gel  

DEFF Research Database (Denmark)

Charge screening effects on nanostructures of N-isopropylacrylamide-sodium acrylate (NIPA-SA) and -acrylic acid (NIPA-AAc) gels are investigated with small-angle neutron scattering. The NIPA-SA and NIPA-AAc gels with low water content exhibit microphase separations with different dimensions. The dehydrated NIPA-SA gel also makes the microphase separation but the dehydrated NIPA-AAc gel does not. These results indicate that ionic circumstance around charged bases strongly affects the nanostructures both of the dehydrated gel and the gel with low water content. (C) 2004 Elsevier B. V. All rights reserved.

Sugiyama, M; Annaka, M

2004-01-01

109

Capillary fracture of soft gels.  

Science.gov (United States)

A liquid droplet resting on a soft gel substrate can deform that substrate to the point of material failure, whereby fractures develop on the gel surface that propagate outwards from the contact line in a starburst pattern. In this paper, we characterize (i) the initiation process, in which the number of arms in the starburst is controlled by the ratio of the surface tension contrast to the gel's elastic modulus, and (ii) the propagation dynamics showing that once fractures are initiated they propagate with a universal power law L[proportional]t(3/4). We develop a model for crack initiation by treating the gel as a linear elastic solid and computing the deformations within the substrate from the liquid-solid wetting forces. The elastic solution shows that both the location and the magnitude of the wetting forces are critical in providing a quantitative prediction for the number of fractures and, hence, an interpretation of the initiation of capillary fractures. This solution also reveals that the depth of the gel is an important factor in the fracture process, as it can help mitigate large surface tractions; this finding is confirmed with experiments. We then develop a model for crack propagation by considering the transport of an inviscid fluid into the fracture tip of an incompressible material and find that a simple energy-conservation argument can explain the observed material-independent power law. We compare predictions for both linear elastic and neo-Hookean solids, finding that the latter better explains the observed exponent. PMID:24229192

Bostwick, Joshua B; Daniels, Karen E

2013-10-01

110

Regenerative medicine: Noodle gels for cells  

Science.gov (United States)

Heating and cooling of peptide amphiphile suspensions converts disorganized nanofibres into liquid-crystalline nanofibre bundles that gel on addition of salts. The noodle-shaped strings of gel can entrap and align cells.

Deming, Timothy J.

2010-07-01

111

Gel catalysts that switch on and off  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report development of a polymer gel with a catalytic activity that can be switched on and off when the solvent composition is changed. The gel consists of two species of monomers. The major component, N-isopropylacrylamide, makes the gel swell and shrink in response to a change in composition of ethanol/water mixtures. The minor component, vinylimidazole, which is capable of catalysis, is copolymerized into the gel network. The reaction rate for catalytic hydrolysis of p-nitrophenyl capryl...

Wang, Guoqiang; Kuroda, Kenichi; Enoki, Takashi; Grosberg, Alexander; Masamune, Satoru; Oya, Taro; Takeoka, Yukikazu; Tanaka, Toyoichi

2000-01-01

112

Polyelectrolyte intelligent gels. Design and applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this chapter polyelectrolyte intelligent gels are examined along three broad lines. The effects of different physical, chemical and biological stimuli on gels response are analysed and mechanisms of response are outlined. The broad range of biomedical applications of smart gels is reviewed and limits and perspectives of the proposed techniques and devices are crititically discussed. Finally, continuous modelling of gel electromechanochemistry is described, providing quant...

Chiarelli, Piero; Rossi, Danilo

2012-01-01

113

Yield stress determination of a physical gel  

DEFF Research Database (Denmark)

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.

Hvidt, Søren

2013-01-01

114

Consolidation of Inorganic Precipitated Silica Gel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Colloidal gels are possible intermediates in the generation of highly porous particle systems. In the production process the gels are fragmented after their formation. These gel fragments compact to particles whose application-technological properties are determined by their size and porosity. In the case of precipitated silica gels, this consolidation process depends on temperature and pH, among other parameters. It is shown that these dependencies can be characterized by oedometer measureme...

Hussein Sahabi; Matthias Kind

2011-01-01

115

Perrhenate ion uptake by aluminium hydroxide gels  

International Nuclear Information System (INIS)

The adsorption of perrhenate ions onto aluminium hydroxide gels was investigated. These gels were prepared by the sol-gel method in non aqueous solutions using a tertiary amine as template. They were amorphous and presented high specific surface areas. The amount of perrhenate ions adsorbed from aqueous solutions depended on the specific surface area of the gels. Removal of perrhenate ions up to 84% could be achieved without reaching saturation. (author). 15 refs., 6 figs

1996-01-01

116

Bleach Gel: A Simple Agarose Gel for Analyzing RNA Quality  

Digital Repository Infrastructure Vision for European Research (DRIVER)

RNA-based applications requiring high quality, non-degraded RNA are a foundational element of many research studies. As such, it is paramount that the integrity of experimental RNA is validated prior to cDNA synthesis or other downstream applications. In the absence of expensive equipment such as microfluidic electrophoretic devices, and as an alternative to the costly and time-consuming standard formaldehyde gel, RNA quality can be quickly analyzed by adding small amounts of commercial bleac...

Aranda, Patrick S.; Lajoie, Dollie M.; Jorcyk, Cheryl L.

2012-01-01

117

A clarified gel for crystal growth  

Science.gov (United States)

A procedure for preparing clarified sodium silicate gels suitable for crystal growth is described. In the method described here, the silicate stock is clarified by pretreating it with cation exchange resins before preparing the gels. Also, a modified recipe is proposed for preparing gels to achieve improved transparency.

Barber, P. G.; Simpson, N. R.

1985-01-01

118

Spring-loaded polymeric gel actuators  

Energy Technology Data Exchange (ETDEWEB)

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

Shahinpoor, Mohsen (Albuquerque, NM)

1995-01-01

119

Crosslinked fracture acidizing acid gel  

Energy Technology Data Exchange (ETDEWEB)

A crosslinked acid gel has been developed for use in fracturing-acidizing applications. Crosslinked acid can be prepared from acid strengths up to 28% hydrochloric acid. Laboratory tests show the fluid to possess moderately high viscosities with substantial shear stability at temperatures up to 80/sup 0/C (175/sup 0/F). The viscosity of the acid gel can be reduced in a controlled manner for easy clean-up by the addition of a chemical additive. The rheologic data are obtained in a newly designed viscometer, the pressure rheometer. This new rheometer uses a bob/cup arrangement and the fluid is fed to the gap between the bob and cup. A desired pressure can be applied directly to the test fluid without using a second pressurizing fluid such as mineral oil or nitrogen.

Deysarkar, A.K.; Dawson, J.C.; Sedillo, L.P.; Knoll-Davis, S.

1982-01-01

120

Gel dosimetry for conformal radiotherapy  

Energy Technology Data Exchange (ETDEWEB)

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)

Gambarini, G. [Department of Physics of the University and INFN, Milan (Italy)]. e-mail: grazia.gambarini@mi.infn.it

2005-07-01

 
 
 
 
121

EIAV Effectiveness Detection by Nested PCR Comparing two Different Samples: PBMCs and Bronchoalveolar Wash  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: Equine Infectious Anemia (EIA is a chronic, relapsing infectious disease of horses caused by Equine Infectious Anemia Virus (EIAV. The objective of this experiment was compared EIAV effectiveness detection in Peripheral Blood Mononuclear Cells (PBMCs and Bronchoalveolar wash (BAW from naturally infected horses. Approach: Fifty seven DNA samples isolated from PBMCs and BAW of naturally infected animals were used for a nested PCR amplifying a 408 bp gag gene fragment region. Equine Dermal cells (ED infected and non infected by EIAV was used as nested PCR negative and positive control. Horses? blood samples were firstly tested as positive in Agar Gel Immunodiffusion Assay (AGID. Results: Results demonstrated 89% (51/57 of gag gene amplification in PBMCs samples and only 47% (27/57 of gag gene amplification in BAW samples. Conclusion: The nested PCR assay used in the present study detected more EIAV positive samples in PBMC than in BAW, indicating PBMCs as a reliable source for EIAV diagnosis.

Elizangela M.D. Santos

2010-01-01

122

Interaction Between Newcastle Disease and Infectious Bursal Disease Vaccines Commonly Used in Sudan  

Directory of Open Access Journals (Sweden)

Full Text Available It was the aim of this study to determine the interaction between the Newcastle disease (ND and infectious bursal disease (IBD vaccines used to control these two important viral infections greatly affecting poultry industry worldwide. The commercially available vaccines in the Sudan were used. Haemagglutination inhibition (HI and agar gel immunodiffusion (AGID tests were employed to measure the Ab titres in chicks sera to ND and IBD respectively. Generally, IBD vaccine was reported to have adverse effect on the ND vaccine whereas the reverse was not true. The results obtained also revealed that better Ab responses against NDV were detected when ND vaccine was administered before IBD vaccine. The deleterious effect of IBD vaccine on Ab levels against NDV antigens was slightly (p<0.05 low when IBD vaccine is administered at two weeks as compared to three weeks of chicken age. No variations in the Ab titres when chicks were boostered with ND vaccine containing LaSota or Komorov strain of the virus at 4 weeks were observed. However, slightly (p<0.01 better Ab responses were noted for LaSota over Komorov strain. It was, therefore, concluded that vaccination of chicks with ND vaccine containing LaSota strain of the virus when they were 10 days followed by vaccination with IBD vaccine at two weeks and boostering with the same ND vaccine yielded better Ab responses but slightly lower protection levels.

A.S. Ali

2004-01-01

123

Development of Texture Model in the Fish Gels Using Eigen-gel Patterns  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study proposes two texture development models for Cod surimi gel. Dimensionality of the training data sets (12 patterns) of surimi gel strength are reduced to four eigen-gel patterns using an unsupervised method, the PCA method. Then we obtain an eigen-gel pattern for each cluster. Two texture models, consecutive and competitive-consecutive first order reactions are developed based on an eigen-gel pattern for each cluster. The correlation coefficient method is introduced to achieve a goo...

Sirima Chinnasarn; Krisana Chinnasarn; David Leo Pyle; Chidphong Pradistsuwana

2006-01-01

124

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Human Proteome Organisation’s Proteomics Standards Initiative (HUPO-PSI) has developed the GelML data exchange format for representing gel electrophoresis experiments performed in proteomics investigations. The format closely follows the reporting guidelines for gel electrophoresis, which are part of the Minimum Information About a Proteomics Experiment (MIAPE) set of modules. GelML supports the capture of metadata (such as experimental protocols) and data (such as gel images) resulting...

Gibson, Frank; Hoogland, Christine; Martinez-bartolome?, 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.

2010-01-01

125

Gel transitions in colloidal suspensions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The idealized mode-coupling theory (MCT) is applied to colloidal systems interacting via short-range attractive interactions of Yukawa form. At low temperatures, MCT predicts a slowing down of the local dynamics and ergodicity-breaking transitions. The non-ergodicity transitions share many features with the colloidal gel transition, and are proposed to be the source of gelation in colloidal systems. Previous calculations of the phase diagram are complemented with additional data for shorter r...

Bergenholtz, Johan; Fuchs, Matthias

1999-01-01

126

Sol-gel derived ceramics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis of ceramic raw materials has become an important factor in ceramic technologies. The increasing demands to the performance of ceramic compounds has caused increased activities for the preparation of tailor-made raw materials. Amongst a variety of new syntheses like flame pyrolysis, reactive spray drying, plasma or laser assisted techniques, the sol-gel process plays an important and increasing role. The process describes the building up of an inorganic (in general an oxide) netw...

Schmidt, Helmut K.

1990-01-01

127

Temperature sensitive gels as size selective absorbants  

Energy Technology Data Exchange (ETDEWEB)

The authors used crosslinked polymer gels as extraction solvents for aqueous solutions. The gels swell to many times their dry weight by absorbing water and low molecular weight solutes, but excluding proteins and other high molecular weight solutes. The swollen gel is removed by filtration. When it is slightly warmed, it collapses, releasing most of the absorbed material. This sudden change of swelling with temperature occurs because the gel is near a critical point. After the gel is separated from the desorbed water by filtration, it is cooled and then can be reused.

Freitas, R.F.S.; Cussler, E.L.

1987-01-01

128

Diffusion of potassium chromate in Agar gel  

International Nuclear Information System (INIS)

Tracer and self-diffusion coefficients for potassium chromate labelled with "5"1Cr are determined in agar gel medium at different temperatures and the activation energies for the two processes are determined. The role of the obstruction effect on the self-diffusion coefficient is examined. The marked discrepancy observed between the experimentally determined formation factor and that predicted from the theory, whether on the basis of needle or spherical shape for the gel, suggests that apart from gel structure and known obstruction effect due to the gel matrix, other factors as specific binding between ions and gel matrix and electrostatic effects appear to influence the diffusion of ions. (orig.)

1980-01-01

129

Gels from rigid rod polymer isocyanate systems  

Energy Technology Data Exchange (ETDEWEB)

The rigid rod character of polyisocyanates and polyisonitriles is due primarily to steric forces. This permits alternation of the functionality of the pendant groups and allows the polymer to be engineered to specific applications, such as organic conductors or optically active films. Since under the proper conditions these polymers form gels, they may also be useful as controlled release gels or low density foams. So far, we have shown that crosslinked gels and foams can be made. Details of synthesis and characterization of both crosslinked and uncrosslinked isocyanate gels with a hexyl pendant group and gels with a dodecyl pendant group will be discussed. 14 refs., 1 fig.

Lucht, L.M.; Shell, P.K.; Cook, R.C.; Cook, A.R. (Lawrence Livermore National Lab., CA (USA)); Green, M.M.; Gross, R.A.; Reidy, M. (Polytechnic Univ., Brooklyn, NY (USA). Dept. of Chemistry)

1986-05-01

130

Detection efficiency of scintillator gels  

International Nuclear Information System (INIS)

A study was performed to determine whether the increased counting efficiency of gel scintillants (containing dioxan, PPO, dimethyl POPOP and naphthalene) with the addition of increasing amounts of silica could be due to increased fluorescence from PPO resulting from the increasing viscosity. This was tested by studying a series of gel scintillants of the same composition but containing no silica; an increasing viscosity was obtained by adding different quantities of liquid HP_5_5 (hydroxypropyl-methyl-phthalate cellulose). The overall results with the scintillants containing HP showed a decreased fluorescence from PPO with increasing viscosity. However this was a result of two opposing mechanisms, i.e. an increased fluorescence from PPO due to increased viscosity and a direct quenching effect of HP_5_5, the latter effect being predominant. The importance of the viscosity was thus confirmed, raised values leading to increased fluorescence from PPO and thus increased scintillation counting efficiency. A further study was made of other gel scintillants containing silica. (UK)

1980-01-01

131

Symmetries and Elasticity of Nematic Gels  

CERN Multimedia

A nematic liquid-crystal gel is a macroscopically homogeneous elastic medium with the rotational symmetry of a nematic liquid crystal. In this paper, we develop a general approach to the study of these gels that incorporates all underlying symmetries. After reviewing traditional elasticity and clarifying the role of broken rotational symmetries in both the reference space of points in the undistorted medium and the target space into which these points are mapped, we explore the unusual properties of nematic gels from a number of perspectives. We show how symmetries of nematic gels formed via spontaneous symmetry breaking from an isotropic gel enforce soft elastic response characterized by the vanishing of a shear modulus and the vanishing of stress up to a critical value of strain along certain directions. We also study the phase transition from isotropic to nematic gels. In addition to being fully consistent with approaches to nematic gels based on rubber elasticity, our description has the important advanta...

Lubenskii, T C; Radzihovsky, L R; Xing, X; Mukhopadhyay, Ranjan; Radzihovsky, Leo; Xing, Xiangjun

2002-01-01

132

Generative force of self-oscillating gel.  

Science.gov (United States)

We succeeded in measuring the generative force of a self-oscillating polymer gel in an aqueous solution comprising the three substrates of the Belousov-Zhabotinsky (BZ) reaction (malonic acid, sodium bromate, and nitric acid) under constant temperature. In this study, we developed an apparatus with a microforce sensor for measuring the generative force of small-sized gels (1 mm(3)). The self-oscillating polymer gel directly converts the chemical energy of the BZ reaction into mechanical work. It was determined that the generative force of the self-oscillating gel was 972 Pa, and the period of self-oscillation was 480 s at 18 °C. We demonstrated that the generative force of the gel was about a hundredth the generative force of a muscle in the body. We analyzed the time dependence of the color change in the self-oscillating polymer gel. The color of the gel changed periodically owing to the cyclic change in the redox state of the Ru moiety, induced by the BZ reaction. The peaks of the waveforms of the generative force and color change were almost identical. This result showed that the generative force was synchronized with the periodical change in the oxidation number of the Ru catalytic moiety in the gel. To understand a theoretical basis for the generative force of a self-oscillating gel, we considered a general theory that is based on the volume phase transition of gel and the two-parameter Oregonator model of the BZ reaction. PMID:24524539

Hara, Yusuke; Mayama, Hiroyuki; Morishima, Keisuke

2014-03-01

133

Sol/gel transition of chitosan solutions.  

Science.gov (United States)

This work studies the occurrence of sol/gel transition and the gel rheology for chitosan solution under various conditions. Experiments were conducted in an oscillatory shear apparatus with small amplitude, using a Rheometrics SR-5 rheometer, with Couette and parallel plate geometries. The experimental results demonstrate that the sol/gel transition concentration and the elastic modulus (G') for CS gel decrease as the pH value and the molecular weight (Mw) increase. However, the sol/gel transition concentration and G' became independent of Mw when Mw exceeded a threshold. The higher ionization constant, Kp, is responsible for the higher sol/gel transition concentration in a formic acid solution than in an acetic acid solution with equivalent molar concentration. The elastic modulus G' of a CS gel increases with temperature, which relationship differs from that for many polysaccharides, and can be understood through classical rubber elastic theory. Finally, a gel whose concentration was barely above the sol/gel point exhibited aging, and its G' and G" declined rather than increase with time, accompanied by a reversal from the sol/gel state back to the sol state. This is an uncommon aging behavior for a polysaccharide and a detailed explanation is provided. PMID:16370243

Rwei, S P; Chen, T Y; Cheng, Y Y

2005-01-01

134

An evaluation of the gel pond performance  

Energy Technology Data Exchange (ETDEWEB)

The gel pond concept replaces the stratified non-convective zone of the traditional salt gradient pond by a transparent layer of viscous or near-solid polymer gel. As part of the continuing development of this technology, the effect of gel thickness upon the performance of the gel solar pond is being studied. A simplified steady state model describing the physics of the pond has been constructed and tested. Preliminary comparison between the surface heat losses from the gel pond and a nearby salt gradient pond have been made. The measured values of insolation were used in the model to compute the temperature profiles in the gel layer, and in the non-convective layer of the salt gradient pond. The model was used to calculate collection, retention, and effective retention efficiencies for the gel pond for different gel thicknesses and estimate the surface heat losses for both the gel pond and the salt gradient pond. The calculated temperature profiles, for both the gel layer and the non-convective layer in the two ponds compared well with experimental data. It was found that a minimum gel thickness of 0.15 m was adequate on the basis of the effective retention efficiency. The surface heat losses from the 0.25 m gel pond were approximately half those from the salt gradient pond with 1 m stratified zone under the same conditions. Based on the preliminary work, the gel pond concept appears to be superior to the classic salt gradient pond, for solar collection and storage.

Wilkins, E.; El-Genk, M.; El-Husseini, K.; Thakur, D.

1982-01-01

135

Predictive value of serologic tests in the diagnosis and follow-up of patients with paracoccidioidomycosis / Valor predictivo de las pruebas serologicas para el diagnostico y seguimiento de la paracoccidoidomycosis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in spanish Con el objeto de determinar el valor predictivo de las pruebas serológicas (F¡jación de Complemento, FC, e Inmunodifusión en Gel de Agar, IDGA), utilizadas regularmente en nuestro laboratorio para el diagnóstico y el seguimiento de la paracoccidioidomicosis, se analizaron los datos provenientes de 4 [...] 3 pacientes con la enfermedad. Tales pacientes fueron tratados en forma identica (Ketoconazol, 200 mg/dia por 6 meses); además ambas pruebas serológicas utilizaron un mismo lote de antigeno, eliminando asi posibles variables. Fuera de los sueros provenientes de los 43 pacientes con paracoccidioidomicosis (A), se estudiaron 50 sueros de pacientes con otras micosis profundas (B) y 92 sueros de personas sanas (C). Empleamos las fórmulas dadas por GALEN y GAMBINO6 y hallamos que la sensibilidad de ambas pruebas serológicas era comparable, sin diferencia estadísticamente significativa entre ellas (FC = 93%, IDGA - 88.4%). Dicha sesibilidad tendia a disminuir con el tratamiento, siendo más marcada su baja durante las observaciones post-terapia. Al analizar la especificidad se encontró que la IDGA era totalmente específica, no encontrandose falsos positivos en las poblaciones controles estudiadâs (B y C). La FC mostró un 96.7% de especificidad frente a la población C y un 82% frente a la B, siendo estadistisarnente significativa la diferencia entre ambas. Basados en los datos ariteriores, se buscó et valor predictivo, hallaridose que la IDGA da seguridad completa para el diagnóstiso en cualquiera de los períodos evaluados no asi la FC, la que mostró disminución de tales valores durante la terapia y la post-terapia. La curva respectiva mostró como a medida que pasaba el tiempo, disminuía la posibiildad de diferenciar la paracoccidioidomicosis (A) de otras micosis (B), manteniendose, sinembargo, la diferencia con los controles normales (C). Abstract in english A serologic study was undertaken in a group of 43 patients with active paracoccidioidomycosis who were treated in the same form (ketoconazole), for identical periods of time (6 months), and folio wed-up for various periods posttherapy. The tests employed were agar gel immunodiffusion (AGID) and comp [...] lement fixation (FC). Also studied were 50 sera from patients with proven histoplasmosis and pulmonary aspergilloma, 30 patients with culturaly proven tuberculosis as well as 92 specimens from healthy individuals, residents in the endemic area for paracoccidioidomycosis. A single lot of yeast filtrate antigen was used throughout the study. The value of each test was measured according to GALEN and GAMBINO6. Both tests were highly sensitive, 89 and 93% respectively. Regarding their specificity, the AGID was totally specific while the CF exhibited 96.6% and 97% specificity in front of tuberculosis patients and healthy individuals respectively and 82% in comparison with patients with other mycoses. The concept of predictive value, that is, the certainty one has in accepting a positive test as diagnostic of paracoccidioidomycosis, favored the AGID procedure (100%) over the CF test. The latter could sort out with 93% certainty a patient with paracoccidioidomycosis among a group of healthy individuals and with 97.5% in the case of TB patients; when the group in question was composed by individuals with other deep mycoses, such certainty was lower (81%). The above results indicate that both the AGID and the CF tests furnish results of high confidence; one should not relay, however, in the CF alone as a means to establish the specific diagnosis of paracoccidioidomycosis.

Cano, Luz Elena; Restrepo, Angela.

136

Lentivírus em caprinos leiteiros do semiárido paraibano: prevalência de anticorpos, fatores de risco e detecção molecular / Lentivirus in dairy goats from the semiarid region of Paraiba state: seroprevalence, risk factors and molecular detection  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Os objetivos do presente trabalho foram determinar a prevalência de caprinos leiteiros soropositivos para a infecção por Lentivirus de pequenos ruminantes no semiárido do Estado da Paraíba, Nordeste do Brasil, identificar fatores de risco associados à prevalência de rebanhos positivos, e realizar a [...] detecção molecular do agente. Foram utilizadas 1047 cabras leiteiras de 110 propriedades selecionadas aleatoriamente no Município de Monteiro, Estado da Paraíba, no período de março de 2009 a dezembro de 2011. Para o diagnóstico da infecção por Lentivirus, foi utilizado o teste de imunodifusão em gel de ágar (AGID). Um ano após foi realizada nova sorologia, e PCR em tempo real foi aplicada em amostras de sangue e leite de 48 cabras procedentes de quatro propriedades com animais soropositivos. As prevalências de propriedades positivas e de animais soropositivos na AGID foram 44,6% (IC 95% = 35,1% - 54,3%) e 8,1% (IC 95% = 5,6% - 16,8%), respectivamente. Realizar corte e desinfecção de umbigo (odds ratio = 2,44; p = 0,048) e condições de aglomeração de animais (odds ratio = 3,45; p = 0,048) foram associadas com a prevalência de propriedades positivas. Um ano após a realização do inquérito sorológico, foi verificada a permanência de animais infectados, detectados por PCR em tempo real a partir de amostras de sangue e leite. A PCR em tempo real das amostras de leucócitos circulantes apresentou boa performance, com sensibilidade de 100%, especificidade de 92,86%, concordância de 93,75% e indicador Kappa de 0,765. Sugere-se que seja realizado um trabalho de educação sanitária junto aos produtores sobre medidas de prevenção com o objetivo de reduzir a disseminação da infecção nos rebanhos. Abstract in english The aims of this study were to determine the seroprevalence of infection by ruminants Lentivirus in dairy goats in the semiarid of the Paraiba State, Northeastern Brazil, to identify risk factors associated with the herd-level prevalence and to perform molecular detection of the agent. A total of 1, [...] 047 dairy goats from 110 herds were randomly selected from the county of Monteiro, Paraiba State, and serum samples were collected from March 2009 to December 2011. For the diagnosis of Lentivirus infection, the agar gel immunodiffusion test (AGID) was used. One year after that a new serology was performed and the real-time PCR assay was applied in blood and milk samples from 48 goats from four herds with seropositive animals. Prevalence of positive herds and seropositive animals at AGID were 44.6% (95% CI=35.1-54.3%) and 8.1% (95% CI =5.6-16.8%), respectively. Umbilical cord cutting and disinfection (odds ratio = 2.44; p = 0.048) and conditions of animal agglomeration (odds ratio=3.45; p=0.048) were associated with herd-level prevalence. One year after the serological profile, the permanence of infected animals detected by real-time PCR in blood and milk samples was verified. Real-time PCR using white blood cells had a good performance, with sensitivity of 100%, specificity of 92.86%, concordance of 93.75% and Kappa index of 0.765. It was suggested to teach sanitary measures to the herd owners in order to encourage them to adopt prevention measures aiming to reduce the spread of the infection in the herds.

Silva, Maria L.C.R.; Castro, Roberto S.; Maia, Rita C.; Nascimento, Sergio A.; Gomes, Ana Lisa V.; Azevedo, Sérgio S..

137

Comparative study of haemagglutination inhibition, Agar gel precipitation test, Serum neutralization and Enzyme linked immunosorbent assay for detection to avian influenza viruses  

Directory of Open Access Journals (Sweden)

Full Text Available The sensitivity, specificity and reproducibility of the serological tests for detection of avian in-fluenza viruses were carried-out by using Ham- agglutination inhibition (HI, Agar gel precipita-tion test (AGPT, and Enzyme linked immu-nosorbent assay (ELISA and Serum neutraliza-tion test. The geometric mean titre (GMT of hae- magglutination inhibition antibodies recor- ded as log2 indicated that the post vaccination titres in the field were on higher side i.e., 7.9 for H7 and 5.9 for H9. The correlation between HI titre and AGPT affirmed that for the AGPT test need high antibody titre for positive reaction. The pooled sera were also used to correlate the se-rum neutralization test and enzyme linked im- muno-sorbent assay. The serial two fold dilute- ons were tested for the serum neutralization ac- tivity and concluded that the HI titre log2 4 pro-vided 100% protection, than 52% and 45% pro-tection in 1:2 and 1:4 dilution was recorded, respectively. Similarly, the ELISA test showed positive results up to 1:16 HI titre, i.e. log2 4 and confirmed the linear relation between these two serological tests. In HI test, the concentration of antigen can influence the result. It also needs careful preparation of concentration of eryth-rocyte suspension. Agar Gel immuno-diffusion is basically a qualitative test as it can not de-termine the quantity of antigen or antibody with the help of this test. It lacks the level of sensi-tivity as offered by other test. If serum neutrali-zation test is performed on a pooled serum sam- ples, then it could lead to a false conclusion on antibodies status. ELISA is most sensitive, spe-cific and accurate as compare to all other sero-logical tests.

Ghluam Hussain Jaffar

2010-02-01

138

Development of Texture Model in the Fish Gels Using Eigen-gel Patterns  

Directory of Open Access Journals (Sweden)

Full Text Available This study proposes two texture development models for Cod surimi gel. Dimensionality of the training data sets (12 patterns of surimi gel strength are reduced to four eigen-gel patterns using an unsupervised method, the PCA method. Then we obtain an eigen-gel pattern for each cluster. Two texture models, consecutive and competitive-consecutive first order reactions are developed based on an eigen-gel pattern for each cluster. The correlation coefficient method is introduced to achieve a good identification rate of similarity between the two proposed methods and the eigen-gel pattern for each cluster.

Sirima Chinnasarn

2006-01-01

139

Sol-gel electrochromic device  

Digital Repository Infrastructure Vision for European Research (DRIVER)

All solid state electrochromic devices have potential applications in architectural and automotive fields to regulate the transmission and reflection of radiant energy. We present the optical and electrochemical characteristics of two solid state windows having the configuration glass/ITO/TiO2-CeO2/TiO2/TiO2-CeO2/ITO/glass and glass/ITO/WOa/TiO2/TiO2-CeO2/ITO/glass where the three internal layers have been prepared by sol gel methods. The preparation of the individual sols and some physical p...

Macedo, Marcelo A.; Aegerter, Michel A.

1994-01-01

140

Photolithographic sol-gel processing  

Energy Technology Data Exchange (ETDEWEB)

Two-dimensionally patterned oxide films are important components of optical-glass waveguides, multichip modules, and other devices. However, techniques for the photolithographic fabrication of such films are not well-established. The authors are developing precursors and strategies for photochemical sol-gel processing, which is a potentially useful approach to the photolithographic patterning of oxide microstructures under mild processing conditions. The authors have prepared several photoreactive precursors which may be deposited as films, masked, irradiated, developed, and annealed to produce negative metal-oxide images. Precursor structures and photoreactivity will be discussed.

Crane, J.L.; Phelps, C.W.; Krchnavek, R.R.; Buhro, W.E. [Washington Univ., St. Louis, MO (United States)

1993-12-31

 
 
 
 
141

Photorefractive sol-gel materials  

Energy Technology Data Exchange (ETDEWEB)

The authors report the synthesis and characterization of photorefractive sol-gel materials that possess covalently attached push-pull azobenzene and carbazole moieties. Molecular structural characterization of the modified silane monomers was achieved by {sup 1}H NMR and infra red spectroscopy. The second-order nonlinear optical properties of the organic-inorganic hybrid films prepared from modified silane monomers were evaluated by second-harmonic generation. The stabilized value of the second harmonic coefficient, d{sub 33}, of films poled by corona discharge, at 1,064 nm fundamental wavelength was found to be 107 pm/V. Photorefractivity was clearly displayed from a two beam coupling experiment.

Chaput, F.; Boilot, J.P.; Gacoin, T. [Ecole Polytechnique, Palaiseau (France); Darracq, B.; Riehl, D.; Canva, M.; Levy, Y.; Brun, A. [CNRS, Orsay (France)

1996-12-31

142

Thermally stable mixed oxide gels  

International Nuclear Information System (INIS)

A process is disclosed for cogelling a smectite with an inorganic metal oxide which is unstable with respect to retaining a high surface area, to produce a cogel of high surface area which has good retention of surface area at high temperatures. Suitable smectites for the practice of this invention are hectorite, chlorite, montmorillionite, beidellite, or admixtures of two or more of these materials with each other or with other materials, or the like. Exemplary of inorganic oxide gels suitable for the practice of this invention are the Group IV-B metal oxides, especially titanium oxide, and other metal oxides such as the oxides of thorium, uranium, silicon, aluminum, and the like

1985-01-01

143

Microwave densification of porous silica gel  

International Nuclear Information System (INIS)

Ultrahigh optical quality silica glass can be fabricated using the sol-gel method. However, long processing times with chlorination are required for the gel to undergo dehydration and densification at high temperature. In this work, microwave hybrid heating (2.45GHz) was used to produce dense, gel-derived silica glasses. A heating schedule was established based on BET analysis and the pore texture evolution of the gel. Using microwave energy, dehydration and densification of the gel were achieved within a few hours with no cracking or foaming. In this presentation, the microwave-processed and conventionally sintered silica gels will be evaluated with respect to bulk density, microhardness, FTIR and UV-VIS-NIR spectra. 12 refs., 4 figs., 1 tab

1993-04-18

144

Kinetics of phase separation of thermoreversible gels  

Science.gov (United States)

We study the kinetics of phase separation and thermoreversible gel formation of LCST-type polymers. A large number of NIPAM-based polymers exhibit transitions near room temperature from a liquid phase to a two-phase state. In the two phase-region of the phase diagram, a polymer dilute phase coexists with a gel. The corresponding shrinking transition for chemically-linked gels has been extensively studied in both its thermodynamic and kinetic aspects. We show that, in the thermoreversible case, the formation of the gel phase proceeds in a similar way. Upon entrance to the two-phase region, the gel volume follows a double exponential decay. The gel undergoes a fast shrinking associated with water ejection, followed by a slower reorganization regime.

Solis, Francisco J.; Leon, Christine; Vernon, Brent

2009-03-01

145

Active Gel Model of Amoeboid Cell Motility  

CERN Multimedia

We develop a model of amoeboid cell motility based on active gel theory. Modeling the motile apparatus of a eukaryotic cell as a confined layer of finite length of poroelastic active gel permeated by a solvent, we first show that, due to active stress and gel turnover, an initially static and homogeneous layer can undergo a contractile-type instability to a polarized moving state in which the rear is enriched in gel polymer. This agrees qualitatively with motile cells containing an actomyosin-rich uropod at their rear. We find that the gel layer settles into a steadily moving, inhomogeneous state at long times, sustained by a balance between contractility and filament turnover. In addition, our model predicts an optimal value of the gel-susbstrate adhesion leading to maximum layer speed, in agreement with cell motility assays. The model may be relevant to motility of cells translocating in complex, confining environments that can be mimicked experimentally by cell migration through microchannels.

Callan-Jones, A C

2013-01-01

146

The Behavior of Selected Arthropod-Borne Viruses in Agar Gel Diffusion Systems.  

Science.gov (United States)

Antigenicity and concentration of reagents are most important to the outcome of tests employing arboviruses in immunodiffusion provided that the pH is held above 8.2. Type of buffer solution is next in importance and in the work reported here, EDTA was su...

R. E. Williams M. I. Moussa

1972-01-01

147

Stiffening in gels containing whey protein isolate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Gels made only from whey protein isolate (WPI) stiffened over the first few days of storage, after which the textural properties remained nearly constant. However, protein gels containing WPI microparticles, at the same total protein content, stiffened over a longer period than those without microparticles. This stiffening was suggested to be the result of rearrangement of crosslinks in the gel. Addition of particles induces additional effects leading to water distribution between the protein...

2013-01-01

148

FORMULATION AND EVALUATION OF CELECOXIB GEL  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present research has been undertaken with the aim to develop a topical gel formulation of celecoxib, which would attenuate the gastrointestinal relater toxicities associated with oral administration and to investigate the effect of DMSO on permeation of celecoxib. Celecoxib is a highly selective cyclooxygenase-2 (cox-2) inhibitor.  In the present study gel with different concentrations of carbapol, sodium alginate and sodium carboxy methylcellulose were prepared. Gels were subjected for ...

Preeti Karade

2012-01-01

149

Rheological characterization of Poloxamer 407 nimesulide gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The thermal gelling property of Poloxamer 407- nimesulide gels was characterized by rheological studies. Nimesulide, a local anti-inflammatory and anesthetic drug used for the treatment of acute and chronic pain, has a short duration of action and a long-acting single-dose injection would be of clinical importance. Thus a poloxamer 407 gel applied intramuscularly could prolong the release and action of nimesulide. In this study, aqueous gels with nimesulide, containing three different concent...

Freitas, M. N.; Farah, M.; Bretas, R. E. S.; Ricci-ju?nior, E.; Marchetti, J. M.

2009-01-01

150

Electrochemical detection of gel microparticles in seawater  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present the first atomic force microscopy (AFM) images of the native marine gel network and a new type of electrochemical signals of individual gel microparticles in seawater. Gel microparticles in seawater are selectively detected through specific amperometric signals using a dropping mercury electrode (DME) as a sensor. We have demonstrated that organic microparticles naturally present in Northern Adriatic seawater can be detected as single particles and sorted at the DME/seawater interf...

Svetlic?ic?, Vesna; Balnois, Eric; Z?utic?, Vera; Chevalet, Jean; Hozic? Zimmermann, Amela; Kovac?, Solveg; Vdovic?, Neda

2006-01-01

151

Local gel methods for conditional moment restrictions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The principal purpose of this paper is to adapt to the conditional moment context the GEL unconditional moment methods described in Smith(1997, 2001) and Newey and Smith(2004). In particular we develop GEL estimators which achieve the semiparametric efficiency lower bound. The requisite GEL criteria are constructed by local smoothing and parallel the local semiparametric efficient EL method formulated by Kitamura, Tripathi and Ahn (2004) for conditional moment restrictions. A particular advan...

Smith, Richard J.

2005-01-01

152

Polyelectrolyte gels: Properties, preparation, and applications  

Energy Technology Data Exchange (ETDEWEB)

The articles contained in this book originated at a symposium sponsored by the American Institute of Chemical Engineers at the American Institute of Chemical Engineers Annual Meeting, held November 11-16, 1990 in Chicago. Considerable attention is given to the characterization of polyelectrolyte gels. Methods are described for synthesizing gels with unique or more desirable properties. Mechanisms of ion transport in various polymers and of polymerization are discussed. Possible of existing uses for these gels are proposed.

Harland, R.S.; Prud' homme, R.K. (eds.)

1992-01-01

153

Principles of Gel Permeation Chromatography  

Science.gov (United States)

Principles of Gel Permeation Chromatography presents the principles of gel permeation chromatography (GPC) for students in introductory undergraduate courses of chemistry and biochemistry. These principles are presented in four sections: Introduction, Real Lab, Virtual Lab, and Microscopic Model. The Introduction and Real Lab sections present a brief view of the basic experimental apparatus typically used in laboratory GPC in order to provide a concrete connection of the real process of separation. The basic elements of column chromatography, emphasizing the stationary and mobile phases, are presented in the Introduction, followed by a sequence of pictures and texts describing major steps in GPC analysis in the Real Lab section. The Virtual Lab section is a simulator. Three samples are available for a virtual GPC experiment: sample 1, containing hemoglobin; sample 2, containing methylene blue; and sample 3, containing both methylene blue and hemoglobin. Each sample undergoes a virtual separation run, which is dynamically represented in three ways in the software: a virtual column, the collected fractions, and a virtual chromatogram. This threefold representation allows the simultaneous view of key aspects of the process to demonstrate the correlation between the experimental procedure and the resulting chromatogram.

154

Brillouin light-scattering from polymer gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The experimental results of th Brillouin shift and width for poly(vinyl alcohol) and poly(vinyl chloride) gels as a function of gel network volume fraction have been analysed using the theory of Marqusee and Deutch for Brillouin light-scattering from polymer gels, incorporated with a new plausible assumption relating the speed of sound in the gel network with its volume fraction. It has been found that the essential features of the behaviour of th Brillouin shift and width are well described ...

Ng, S.; Li, Y.

1993-01-01

155

SOL-GEL processes and their applications  

Energy Technology Data Exchange (ETDEWEB)

The SOL-GEL process was invented at the end of sixties for the preparation of ceramic nuclear fuel. The history of its development, with special stress upon the contribution from Italian scientists, is discussed. Basic principles of SOL-GEL processes, not only the classical but also the recent ones, starting from metallorganic compounds (generally alkoxides) are described. Practical realizations of the SOL-GEL processes are presented. All known methods of starting preparation i.e. sols or broths, especially those concerning the Italian liquid-liquid extraction method, are described. A list of the materials obtained by the SOL-GEL processes and their field of application is also reported.

Deptula, A.; Majani, C.

1986-09-01

156

Diffusion of thallous sulphates in agar gel  

International Nuclear Information System (INIS)

Tracer and self-diffusion coefficients for thallous sulphate labelled with 204Tl are determined in agar gel at different temperatures and the activation energies for the two processes are determined. The obstruction effect on the self-diffusion coefficient for different gel concentration is also studied. The observed formation factor is found to be higher than that predicted from the structure fo the gel suggesting that other factors such as specific bonding between ions and the gel matrix and electrostatic effects appear to play an important role in the diffusion process. (author)

1981-05-01

157

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

Science.gov (United States)

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. PMID:19384038

Heng, See Kah; Heng, Chua Kek; Puthucheary, S D

2009-01-01

158

The relationship of agarose gel structure to the sieving of spheres during agarose gel electrophoresis.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

To understand the organization of fibers in an agarose gel, digitized electron micrographs are used here to determine the frequency distribution of interfiber distance (2Pc) in thin sections of agarose gels. For a preparation of underivatized agarose, a 1.5% gel has a Pc distribution that is indistinguishable from the Pc distribution of a computer-generated, random-fiber gel; the log of the occurrence frequency (F) decreases linearly as a function of Pc. As the agarose concentration decreases...

Griess, G. A.; Guiseley, K. B.; Serwer, P.

1993-01-01

159

Heparin modulates the organization of hydrated collagen gels and inhibits gel contraction by fibroblasts  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We studied the effects of extracellular matrix components on fibroblast contraction of hydrated collagen gels. After 4-h incubations, heparin- containing collagen gels contracted only 10% compared with 50% contraction of control gels. Contraction was not affected by hyaluronic acid, dermatan sulfate, or fibronectin, implying that the activity of heparin was specific. The possibility that heparin inhibited attachment of the cells to the gels was ruled out. Also, addition of heparin to the incu...

1987-01-01

160

Evaluation of western blotting for the diagnosis of enzootic bovine leukemia / Avaliação da técnica de western blot no diagnóstico da leucose enzoótica bovina  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Um sistema de western blotting (WB) foi desenvolvido para detecção de anticorpos contra o vírus da leucose em soros de bovinos. Foram utilizadas amostras de soros de 233 animais naturalmente infectados e soros de vacas experimentalmente infectadas. O teste de imunodifusão em ágar (AGID) foi usado pa [...] ra comparação dos resultados. Graus diferentes de reatividade foram observados em soros positivos ao AGID, quando testados em WB frente a um ou aos dois antígenos mais importantes (gp51 e p24). Outras proteínas (gp30, p15, p12 e p10) não foram detectadas por nenhum soro positivo ao AGID, sendo que três bandas correspondentes à proteína p24 foram observadas ocasionalmente. Em soros obtidos por inoculação experimental, anticorpos contra a proteína p24 foram detectados entre a segunda e a quarta semanas após a inoculação e, em alguns animais, detectaram-se anticorpos anti-gp51 mais tardiamente. O estudo de soros de campo com AGID e WB mostrou concordância de 90,9% sendo que apenas 1,7% dos soros negativos pelo AGID foram positivos ao WB e 7,2% dos resultados não conclusivos por AGID foram definidos por WB (4,2% como positivos e 3% como negativos). Abstract in english A western blotting (WB) procedure has been developed for detecting antibodies to bovine leukosis virus (BLV) in cattle sera. Two hundred and thirty three serum samples from naturally infected cattle with BLV virus and serial bleedings from experimentally BLV infected cows were used. An agar gel immu [...] nodiffusion test (AGID) was used for comparing with the results obtained by WB. The AGID positive sera showed a different degree of reactivity by WB test against the two most important viral antigens (gp51 and p24), or against one of them. Other proteins (gp30, p15, p12 and p10) were not detected with any AGID positive sera, being observed occasionally three bands corresponding to the p24 protein. Using sera obtained by BLV experimental inoculation, the antibodies directed to p24 appeared early (between the 2nd and 4th week post inoculation) and thereafter antibodies to gp51were detected in some animals. The analysis of field serum samples by AGID as compared to WB showed an agreement of 90.9%. Only 1.7% of sera were negative by AGID and positive by WB and 7.2% that were not conclusive by AGID and were defined by WB (4.2% as positive and 3.0% as negative).

E.T., Gonzalez; G.A., Oliva; J., Norimine; V., Cid de la Paz; M.G., Echeverría.

 
 
 
 
161

Effect of gel structure on the gastric digestion of whey protein emulsion gels.  

Science.gov (United States)

This study aimed to characterize and determine the disintegration of emulsion gels in a human gastric simulator (HGS) and the physicochemical characteristics of gastric digesta. Using thermal treatment at 90 °C, whey protein emulsion gels with different structures and gel strengths were formed by varying the ionic strength. Simulated boluses of soft (containing 10 mM NaCl) and hard (200 mM NaCl) gels, which had similar particle sizes to those of human subjects, were created for gastric digestion. Soft gels disintegrated faster than hard gels in the HGS. The boluses of both gels gradually disintegrated into particles of size ?10 ?m. With further digestion, the protein matrix of the soft gel particles dissolved, the proteins were disrupted mainly by proteolysis and large quantities of oil droplets were released. In contrast, for the hard gel particles, although all proteins were hydrolysed after 240 min the breakdown of the particles was slow and no oil droplets were released after 300 min. The differences in the breakdown of soft and hard gels in the HGS were attributed to the structures of the emulsion gel, which may result in different sets of peptides in the digestion. In addition, coalescence of the oil droplets was observed only for the soft gel. PMID:24652237

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

2014-02-28

162

Sorptive diffusion in clay gels  

International Nuclear Information System (INIS)

Additional protection for the underground storage of high-level nuclear wastes can be provided by an engineered barrier or backfill material. If properly designed, such a barrier can significantly retard the migration of toxic ions even after failure of the waste canister. The backfill material should be inexpensive, relatively impermeable, thermally stable, highly sorptive to toxic ions, compatible with the host rock, easily applied, and, if possible, a fissure sealant. One material that apparently meets most of these qualifications is a swelling clay known as smectite or montmorillonite. The purpose of this research is to investigate experimentally the migration of representative nuclides in swollen clay gels and to formulate a quantitative transport model allowing reliable design of such an engineered barrier

1982-09-01

163

Viscoelastic Properties of Vitreous Gel  

Science.gov (United States)

We studied the rheological properties of porcine vitreous humor using a stressed-control shear rheometer. All experiments were performed in a closed environment at body temperature to mimic in-vivo conditions. We modeled the creep deformation using a two-element retardation spectrum model. By associating each element of the model to an individual biopolymeric system in the vitreous gel, a separate response to the applied stress was obtained from each component. The short time scale was associated with the collagen structure, while the longer time scale was related to the microfibrilis and hyaluronan network. We were able to distinguish the role of each main component from the overall rheological properties. Knowledge of this correlation enables us to relate the physical properties of vitreous to its pathology, as well as optimize surgical procedures such as vitrectomy.

Pirouz Kavehpour, H.; Sharif-Kashani, Pooria

2010-11-01

164

Light-sensitive polymer gel  

Energy Technology Data Exchange (ETDEWEB)

Complex reaction processes involved in light-sensitive functions of plants have been studied; however, details are still unknown. One of the findings common to any light sensitive system of plants is that the light receptor has photochromic molecules, that protein structural changes are induced as triggered by structural or electric charge condition changes which occur in these molecules when they are excited by light, and that, as a consequence, the enzyme reaction system is perturbed to produce a light sensitive effect. This paper discusses part of this mechanism in the light of materials science, suggests a guideline for designing soft polymer light-sensitive materials, and gives an introduction to polymer gels which have light sensitive functions simulating the corresponding functions of organisms' light sensitive systems. 12 refs., 10 figs.

Irie, Tadahiro (Kyushu Univ., Fukuoka (Japan))

1988-12-15

165

Gel transitions in colloidal suspensions  

CERN Multimedia

The idealized mode coupling theory (MCT) is applied to colloidal systems interacting via short-range attractive interactions of Yukawa form. At low temperatures MCT predicts a slowing down of the local dynamics and ergodicity breaking transitions. The nonergodicity transitions share many features with the colloidal gel transition, and are proposed to be the source of gelation in colloidal systems. Previous calculations of the phase diagram are complemented with additional data for shorter ranges of the attractive interaction, showing that the path of the nonergodicity transition line is then unimpeded by the gas-liquid critical curve at low temperatures. Particular attention is given to the critical nonergodicity parameters, motivated by recent experimental measurements. An asymptotic model is developed, valid for dilute systems of spheres interacting via strong short-range attractions, and is shown to capture all aspects of the low temperature MCT nonergodicity transitions.

Bergenholtz, J

1999-01-01

166

Nonlinear Elasticity in Biological Gels  

CERN Multimedia

Unlike most synthetic materials, biological materials often stiffen as they are deformed. This nonlinear elastic response, critical for the physiological function of some tissues, has been documented since at least the 19th century, but the molecular structure and the design principles responsible for it are unknown. Current models for this response require geometrically complex ordered structures unique to each material. In this Article we show that a much simpler molecular theory accounts for strain stiffening in a wide range of molecularly distinct biopolymer gels formed from purified cytoskeletal and extracellular proteins. This theory shows that systems of semi-flexible chains such as filamentous proteins arranged in an open crosslinked meshwork invariably stiffen at low strains without the need for a specific architecture or multiple elements with different intrinsic stiffnesses.

Storm, C; MacKintosh, F C; Lubensky, T C; Janmey, P A; Storm, Cornelis; Pastore, Jennifer J.; Kintosh, Fred C. Mac; Lubensky, Tom C.; Janmey, Paul A.

2004-01-01

167

Radiation sensitive polymer gel dosimeters  

International Nuclear Information System (INIS)

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 (T2) 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 T2 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. 1H, 13C 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 (fxH ) in the xth 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

2000-01-01

168

A Simple Vertical Slab Gel Electrophoresis Apparatus.  

Science.gov (United States)

Describes an inexpensive, easily constructed, and safe vertical slab gel kit used routinely for sodium dodecyl sulphate-polyacrylamide gel electrophoresis research and student experiments. Five kits are run from a single transformer. Because toxic solutions are used, students are given plastic gloves and closely supervised during laboratory…

Carter, J. B.; And Others

1983-01-01

169

Effect of iron gel on dentin permeability.  

Science.gov (United States)

This study evaluated in vitro the effect of an experimental gel containing iron on the reduction of hydraulic conductance of dentin. Thirty-six 1-mm-thick dentin discs obtained from extracted human third molars were divided into 3 groups of 10 specimens each. The groups corresponded to the following experimental materials: 1.23% acidulated phosphate fluoride gel, pH 4.1; 3% potassium oxalate gel, pH 4.1 (Oxa-Gel®); and iron sulfate gel (10 mmol/L FeSO4), pH 4.1. The gels were applied to dentin under the following conditions: after 37% phosphoric acid and before 6% citric acid. Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. There was no significant differences (p0.05) among the gels. This study suggests that the iron gel promoted reduction in dentin permeability comparable to that of the other agents and thus may be considered a good clinical alternative for the treatment of dentin hypersensitivity. PMID:21915516

Sales-Peres, Sílvia Helena de Carvalho; Reinato, João Victor Donazan; Sales-Peres, André de Carvalho; Marsicano, Juliane Avansini

2011-01-01

170

Structure and Frictional Properties of Colloid Gel  

Directory of Open Access Journals (Sweden)

Full Text Available Polymer gels are known to be opaque when the preparation conditions, such as the reaction temperature and the composition, are changed. The increase of the opaqueness of the gel suggests strongly the change of network structure. Here, we are going to review the recent studies on the structure and the frictional study of the opaque poly(acrylamide gel. The results indicate that the opaque poly(acrylamide gel consists of the fractal aggregate of the colloidal particles of sub-micrometer in size. The density of the colloid particle is calculated from the structural parameters and is found to be of the order of about 1 g/cm3. The results indicate that the main chain component and the cross-linker is densely cross-linked into the particle. The frictional property of poly(acrylamide gel is analyzed in terms of the structural parameters of the gel. It is found that the frictional property of the opaque gel is well explained in terms of the structural parameters of the opaque gel.

Masayuki Tokita

2014-03-01

171

Sol-gel kinetics by NMR  

Energy Technology Data Exchange (ETDEWEB)

The chemical synthesis of advanced ceramic and glass materials by the sol-gel process has become an area of increasing activity in the field of material science. The sol-gel process provides a means to prepare homogeneous, high purity materials with tailored chemical and physical properties. This paper surveyed the nuclear magnetic resonance (NMR) studies of silicon-based sol-gel kinetics. A review of the various models which have been used to analyze the chemical kinetics of various sol-gel systems was presented. The utility of NMR spectroscopy was demonstrated in investigating the influence that various reaction conditions have on the reaction pathways by which sol-gel derived materials are synthesized. By observing in a direct fashion the chemical pathway of the sol-gel, it is often possible to relate the final properties of the material to the formulation and reaction conditions of the sol-gel. The study of reaction kinetics by NMR is expected to play an increasingly important role in understanding sol-gel processing and material properties. 15 refs. (DP)

Assink, R.A.; Kay, B.D.

1991-01-01

172

Halogen-bonding-triggered supramolecular gel formation  

Science.gov (United States)

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

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

2013-01-01

173

Desiccant grade silica gel from paddy huck  

Energy Technology Data Exchange (ETDEWEB)

The process for the production of silica gel from Paddy husk was comprised of screening the husk to remove impurities, burning the husk in a controlled manner, and reacting the ash with a mild alkali. The procedure yielded a desiccant grade silica gel suitable for dehydration and purification of air and other industrial gases. 4 references, 3 tables.

Saran, T.; Basu, P.K.; Pal, B.; Ramachandran, L.V.

1986-07-01

174

Effect of iron gel on dentin permeability  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este estudo objetivou avaliar in vitro o efeito do gel experimental contendo ferro na redução da condutividade hidráulica na dentina. Trinta e seis discos de dentina humana de 1 mm de espessura, foram obtidos de terceiros molares extraídos divididos em 3 grupos de 10 espécimes cada. Os grupos foram [...] divididos nos seguintes grupos experimentais: F- flúor gel a 1,23%, pH 4,1; O- gel de oxalato de potássio a 3%, pH 4,1; I- gel de sulfato ferroso FeSO4 a 10 mmol/L, pH 4,1. Os géis foram aplicados na dentina sob as diferentes condições: após o ácido fosfórico a 37% a antes do ácido cítrico a 6%. Os resultados foram analisados por ANOVA e teste de Tukey, com nível de significância de 5%. Todos os grupos (gel de flúor, oxalato de potássio e gel de ferro) não apresentaram diferenças significativas entre si para todas as condições testadas, exceto na presença da smear layer (p Abstract in english This study evaluated in vitro the effect of an experimental gel containing iron on the reduction of hydraulic conductance of dentin. Thirty-six 1-mm-thick dentin discs obtained from extracted human third molars were divided into 3 groups of 10 specimens each. The groups corresponded to the following [...] experimental materials: 1.23% acidulated phosphate fluoride gel, pH 4.1; 3% potassium oxalate gel, pH 4.1 (Oxa-Gel®); and iron sulfate gel (10 mmol/L FeSO4), pH 4.1. The gels were applied to dentin under the following conditions: after 37% phosphoric acid and before 6% citric acid. Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. There was no significant differences (p0.05) among the gels. This study suggests that the iron gel promoted reduction in dentin permeability comparable to that of the other agents and thus may be considered a good clinical alternative for the treatment of dentin hypersensitivity.

Sílvia Helena de Carvalho, Sales-Peres; João Victor Donazan, Reinato; André de Carvalho, Sales-Peres; Juliane Avansini, Marsicano.

175

Gel electrophoresis: DNA Science Without the DNA!  

Science.gov (United States)

The aim of this project is to develop a simple system for the teaching and demonstration of DNA gel electrophoresis. DNA gel electrophoresis requires the use of specialized apparatus, toxic reagents, expensive agarose gel, and DNA samples, as well as a considerable amount of valuable classroom time to complete. A systematic evaluation of suitable alternative materials and components for the simulation of DNA gel electrophoresis was undertaken. A tried and tested set of combinations is presented here for educators to use in hands-on classroom teaching, which does not require DNA, agarose, or Tris-borate-EDTA buffer. The use of common biological stains in place of DNA samples, agar-agar-based gels, and weak electrolyte solutions provides a simple, inexpensive, and highly reproducible system that is adaptable to instructional needs. The migration of multicolored bands during electrophoresis provides an intuitive, compelling demonstration of the concept of electrophoresis. PMID:21591121

Tan, Timothy Ter Ming; Tan, Zong Ying; Tan, Wei Liang; Lee, Peng Foo Peter

2007-09-01

176

Polymer gel dosimetry using computed tomography  

International Nuclear Information System (INIS)

Polymer gel dosimeter (PGD) is a type of integrating chemical dosimeter that, with the use of a suitable phantom, can be used for evaluation of the absorbed dose (dose distribution) deposited into a polymer gel by various irradiation modalities. Using suitable compounds of gel and appropriate parameters affecting the quality of the final image, evaluation using computed tomography (CT) should become a more advantageous alternative to magnetic resonance (MR), which is the most frequently applied method for the purposes of polymer gel dosimetry so far. In our work, several compositions of polymer gels (PG) were tested; evaluation was made via CT and MR, and values of dose and relative dose resolution were calculated. The optimal protocol for CT imaging and comparison of results from CT and MR are discussed.

2011-10-01

177

On shear rheology of gel propellants  

Energy Technology Data Exchange (ETDEWEB)

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.)

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

178

FTIR thermal analysis on organofunctionalized silica gel  

Directory of Open Access Journals (Sweden)

Full Text Available Silica gel modified with organic groups is widely used as a stationary phase for liquid chromatography. Grafting synthesis can be used to obtain stable modified silica gel surfaces. In this work, silica gel (10 nm of pore diameter and surface area of 320 m² g-1 was chemically modified with 3-chloropropyltrimethoxysilane or 3-aminopropyltrimethoxysilane and reacted with aniline, p-anisidine, benzylamine and 3-phenylpropylchloride in order to yield aromatic groups immobilized on the silica gel surface. Infrared spectroscopy was utilized for characterization of the aromatic groups grafted on the silica gel surface, using a quartz cell. The solids were heated at several temperatures in high vacuum and the infrared band areas of the organic groups were used to evaluate the thermal stability.

Foschiera José L.

2001-01-01

179

Mechanical properties of active polyacrylonitrile gels  

Science.gov (United States)

The ability of some polymeric gels to shrink and swell with changes in their environment makes them of interest in many applications such as artificial muscles and drug delivery systems. While much work has been done to study the behavior and properties of these gels, little information is available regarding the full constitutive description of the mechanical and actuation properties. This work is focused on developing constitutive descriptions of the mechanical properties of such gels, and to determine how these properties change due to changes in the environment. Since these gels can undergo finite elastic deformations, uniaxial tests do not provide sufficient property information and a combination of loading conditions must be used. A biaxial testing system has been developed to test thin sheets of these films, and includes the ability to monitor and change the environmental conditions around the specimen. Initial tests were performed on latex to determine the quality of the testing apparatus. Preliminary results on a polyacrylonitrile gel are presented.

Marra, Steven P.; Ramesh, Kaliat T.; Douglas, Andrew S.

1999-05-01

180

Oilfield applications of colloidal silica gel  

Energy Technology Data Exchange (ETDEWEB)

This paper reports on a practical reservoir fluid-flow control system based on colloidal silica gel that was developed. Colloidal silica gel is an environmentally benign system that provides easy surface handling, reliable gel-time control at temperatures up to 250{degrees} F, and high in-situ performance. Extensive laboratory testing was completed and is discussed elsewhere. Colloidal silica gel has been used in 11 well work-overs for water-injection-profile modification (four wells), water-production control (three wells), and remedial casing repair (four wells). Only one of the four injection-well treatments was a clear-cut technical success, with failure typically caused by pressure parting the gel plug after the well treatment. Two of the three water-production-control jobs were technical and economic successes. Temporary success was achieved in three of the four casing-repair treatments.

Jurinak, J.J.; Summers, L.E. (Conoco Inc. (US))

1991-11-01

 
 
 
 
181

Development of the gel pond technology  

Energy Technology Data Exchange (ETDEWEB)

A review of the development of the gel pond technology is presented. First, the emergence and growth of solar pond technology since the 1950's is described. The inherent problems encountered with the conventional salt gradient ponds are discussed, leading to the concept of the solar gel pond in which the salt gradient layer in the former is replaced by a transparent polymer gel. The first phase dealt with the experimental development of a polymer gel which met selection criteria including transmissivity, stability of physical and chemical properties, high viscosity and other physical and optical properties. The gradual development of the polymer gel through an alternating process of testing and elimination and evaluation of relevant properties of the gel has been described. Modeling and optimization studies of the solar gel pond have been presented. Bansal and Kaushik's model for a salt gradient pond has been modified for a solar gel pond, and the results of the simulation are presented in a graphical form to serve as a quick reference for estimation of pond surface area, depth and flow rate for heat extraction depending on the extreme temperature required in the storage zone and the required heat load. Then, a cost-benefit economic analysis compares the economics of a solar gel pond with a conventional salt gradient pond. The construction of an experimental gel pond (18 m/sup 2/) at The University of New Mexico is described, and the results of the study are summarized. Information on commercial scale ponds at Chamberino, New Mexico (110 m/sup 2/), and in Albuquerque, New Mexico (400 m/sup 2/), is provided.

Wilkins, E.S.; Lee, T.K.

1987-01-01

182

Moisture Transport in Silica Gel Particle Beds: I. Theoretical Study  

Energy Technology Data Exchange (ETDEWEB)

Diffusion mechanisms of moisture within silica gel particles are investigated. It is found that for microporous silica gel surface diffusion is the dominant mechanism of moisture transport, while for macroporous silica gel both Knudsen and surface diffusion are important.

Pesaran, A. A.; Mills, A. F.

1986-08-01

183

Forma nervosa da artrite-encefalite caprina / Nervous form of caprine arthritis-encephalitis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese São descritos dois casos de caprinos, fêmeas, mestiços da raça Saanen de dois meses de idade com sinais clínicos de paresia de membros posteriores, incoordenação, dificuldade respiratória e caquexia, que foram submetidos à eutanásia, devido ao prognóstico desfavorável. Na necropsia, observou-se cong [...] estão do sistema nervoso central (SNC) e consolidação pulmonar nos dois caprinos. Microscopicamente, as alterações foram caracterizadas por leucoencefalomielite linfoplasmocítica multifocal, com vacuolização do neurópilo e esferoides axonais, leptomeningite, pneumonia intersticial não supurativa no caprino A e broncopneumonia bacteriana no caprino B. O exame de imuno-histoquímica (IHQ) foi positivo para o vírus da artrite-encefalite caprina em fragmento de tálamo. A prova de imunodifusão em gel de ágar (IDGA) foi realizada em vinte animais do rebanho de origem e dezesseis animais foram positivos. O diagnóstico da forma nervosa da infecção pelo vírus da artrite-encefalite caprina (CAEV) foi baseado no quadro clínico-patológico, IHQ e IDGA. Esta apresentação clínica da CAE pode ser pouco comum no Brasil, mas deve ser considerada em caso de doenças neurológicas em pequenos ruminantes. Abstract in english Two cases are described of female goats, Saanen crossbreds, two months old, with clinical signs of hind limb paresis, incoordination, difficulty breathing and cachexia, which were subjected to euthanasia due to unfavorable prognosis. At necropsy it was possible to observe that there was congestion o [...] f the central nervous system (CNS) and pulmonary consolidation in both goats. Microscopic changes were characterized by multifocal lymphoplasmacytic leucoencephalomielitis, with vacuolization of neuropile and axonal spheroids, leptomeningitis, interstitial nonsupurative pneumonia in goat A and bacterial bronchopneumonia in goat B. Immunohistochemistry (IHC) was positive for the caprine arthritis - encephalitis virus in thalamus fragments. The agar gel immunodiffusion (AGID) test was performed in sera sample of twenty animals and sixteen resulted positive. Diagnosis of the nervous form of caprine arthritis-encephalitis virus (CAEV) infection was based on clinical and pathological status, IHC and AGID. This clinical presentation of CAE could be uncommon in Brazil, but must be considered in case of neurologic diseases in small ruminants.

Karla Moraes Rocha, Guedes; Vanessa da Silva, Mustafa; Pedro Miguel Ocampos, Pedroso; David, Driemeier; Fábio Henrique Bezerra, Ximenes; Cristiano Barros de, Melo; José Renato Junqueira, Borges; Márcio Botelho de, Castro.

184

Inquérito soroepidemiológico do lentivírus caprino e perfil das criações de caprinos na região do Baixo Médio São Francisco (BA) / Seroepidemiological survey of caprine arthritis encephalitis and profile of goat breeding systems in the region of Baixo Médio São Francisco (BA)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este trabalho teve como finalidade verificar a prevalência sorológica da lentivirose caprina (LVC) na microrregião de Juazeiro, na Bahia, por meio da técnica de imunodifusão em gel de agar (IDGA), bem como caracterizar os sistemas de criação da região. Para tal, foram avaliadas 693 amostras de soros [...] sanguíneos de caprinos de 46 propriedades rurais em diferentes localidades, pertencentes aos 8 municípios formadores da microrregião (Campo Alegre de Lourdes, Casa Nova, Curaçá, Juazeiro, Pilão Arcado, Remanso, Sento Sé e Sobradinho). Na realização das visitas, aplicou-se um questionário com ênfase nas informações referentes ao manejo sanitário. Das propriedades visitadas, todas apresentavam sistema de criação extensivo, com predomínio de animais sem raça definida, baixa produtividade e baixo índice de tecnificação, visando principalmente à obtenção de carne. As principais enfermidades relatadas foram linfadenite caseosa, diarreias, ectoparasitoses e ceratoconjuntivite. Quanto à soroprevalência, 0,29% (2/693) das amostras apresentaram sorologia positiva para a LVC. Os animais positivos pertenciam à mesma propriedade, no município de Curaçá, que apresentou 12,5% (1/8) de propriedades positivas, contrastando com 2,17% (1/46) de soroprevalência total dos rebanhos visitados. Estes resultados sugerem, portanto, a necessidade da efetivação de medidas preventivas na região, principalmente no momento em que se verifica a importação de animais para melhoramento genético. Abstract in english This work aimed to determine the serological prevalence of caprine artrithis encephalitis (CAE) in the microregion of Juazeiro, in the state of Bahia, using the technique of agar gel immunodiffusion (AGID) to characterize the farming systems of the region. We collected 693 blood serum samples of goa [...] ts from 46 farms in 8 different locations belonging to the municipalities forming the microregion (Campo Alegre de Lourdes, Casa Nova, Curaçá, Juazeiro, Pilão Arcado, Remanso, and Sobradinho). During the visits, a questionnaire was applied emphasizing information related to health management. All of the visited properties had extensive breeding systems, with predominance of mixed breed animals, low productivity and low technology rate, aiming mainly to use the meat. The main diseases reported were caseous lymphadenitis, diarrhea, ectoparasites and keratoconjunctivitis. Concerning seroprevalence, 0.29% (2/693) of samples tested positive for AGID. The positive animals belonged to the same property in the municipality of Curaçá, which showed 12.5% (1/8) of positive properties, in contrast to 2.17% (1/46) of total seroprevalence in the other visited properties. These results therefore suggest the need for new epidemiological surveys in the region, especially at a time when the importation of animals for genetic improvement is taking place.

Lima, Carla Caroline Valença de; Costa, Joselito Nunes; Souza, Thiago Sampaio de; Martinez, Priscila; Costa Neto, Antônio Oliveira; Anunciação, Antônio Vicente Magnavita; Almeida, Maria das Graças Ávila Ribeiro; Araújo, Byanca Ribeiro; Pinheiro, Raymundo Rizaldo.

185

Marine biofouling - microbial adhesion to non-solid gel surfaces  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The scope for this work was to develop rapid assays for enumerating microorganisms on gels, and to test whether fouling of gel surfaces is principally different from that of solid substrata. For this purpose, a standard set of different gels were selected, based on biocompatibility, polymer charge and gel strength. Bacterial adhesion to gels could be conveniently enumerated by first staining with SYBR Green I nucleic acid gel strain. Images were then collected using a confocal scanning laser...

2002-01-01

186

Electromechanical coupling in polyelectrolyte gels  

Science.gov (United States)

This work concerns the systematic characterization of the electromechanical coupling in polyelectrolyte gels (PGs) in correlation with their structure and physical properties in view of their potential application as pressure sensors. PGs are electroactive polymers that respond with an electrical potential difference to gradients in mechanical stress and vice versa. So far, these materials have mainly been studied as electrical actuators, but they can also be used as mechanical sensors. Polyelectrolyte gels are biocompatible, and could form the basis for incorporating tactile sensitivity into artificial skin systems. However, how PGs respond to mechanical stimuli in relation to their structure and electrochemical properties has not been studied systematically in a quantitative manner. In this work, the physical-electrochemical properties of copolymers of acrylamide and acrylic acid of varying compositions were characterized in terms of their equilibrium swelling degree, elastic modulus and Donnan potential. Experimental results were tested against the theory of large deformation and electrochemistry of PGs recently developed by Hong et al. Systematic characterization of the electromechanical coupling in PGs was carried out using a new quantitative test based on the indentation of a flat polymer sample with a spherical indenter, while the potential was monitored with an array of planar electrodes. The experimental results suggest that electromechanical coupling in soft PGs directly subjected to a pressure gradient can be understood as a pressure modulation of the Donnan potential. The idea of the potential application of PGs as pressure transducers was illustrated by showing the prototype of the PG spatially resolved sensor capable of distinguishing between sharp and blunt loads and the prototype of the PG pressure sensor in a microfluidic chip. Spatial resolution of both prototypes was solely given by the resolution of the patterned electrodes. The design framework of the potential application of PGs as sensing layers was discussed with a view to the limitations imposed by the increased electrical impedance and reduced signal-to-noise ratio of the voltage measurements on small-length scales. These limitations were experimentally verified by quantifying the electromechanical response with an array of planar electrodes of systematically varying size.

Prudnikova, Katsiaryna I.

187

Defects in gel-derived glasses  

Energy Technology Data Exchange (ETDEWEB)

Defects in gel-derived glasses were reviewed for the three principal stages of the sol-gel process: solution, porous gel, and consolidated glass. The most prominent defects in gel-derived SiO2 are Raman active defects characterized by sharp bands at 490 cm (D1) and 608 cm (D2). YO enrichment, experimental estimates of heats of formation, and structural studies of cyclic model compounds were used to identify the structural origins of D1 and D2 in gels. We conclude that D1 and D2 in gel-derived SiO2 are the oxygen breathing modes of 4- and 3-fold siloxane rings, respectively, as originally proposed by Galeener to explain these Raman-active defects in conventional vitreous silica (v-SiO2). During heat treatments near T/sub g/ (defined by eta = 10/sup 13.5/ poises), the gel-derived SiO2 structure rapidly approaches that of conventional v-SiO2.

Brinker, C.J.; Tallant, D.R.; Roth, E.P.; Ashley, C.S.

1985-01-01

188

Sol-gel processing of silica  

Energy Technology Data Exchange (ETDEWEB)

The sol-gel process for preparing silica and silicates from metal alkoxide precursors is reviewed and compared to the processing of aqueous silicates as described by Iler. Sol-gel processing combines control of composition and microstructure at the molecular level with the ability to shape material in bulk, powder, fiber, and thin-film form. In sol-gel processing of metal alkoxides, hydrolysis reactions replace an alkoxide group with a hydroxyl group. Subsequent condensation reactions involving the hydroxyl groups produce siloxane bonds. The structure of the evolving silicates is a consequence of the successive polymerization, gelation, aging, drying, and heating steps. Often the structures of polymers, gels, and dried gels (either xerogels or aerogels) may be characterized on the 1-20-nm length scale by a mass or surface fractal dimension. On longer length scales, dried gels are micro- or mesoporous, with surface areas often exceeding 800 m{sup 2}/g. During heating, these gels undergo continued polymerization, structural relaxation, and viscous sintering; dense amorphous silica essentially indistinguishable from its conventionally prepared counterpart ultimately results. 123 refs., 18 figs., 2 tabs.

Brinker, C.J. [Sandia National Labs., Albuquerque, NM (United States)

1994-12-31

189

Electroacoustics of Particles Dispersed in Polymer Gel  

Energy Technology Data Exchange (ETDEWEB)

This study examines the acoustic electrophoresis of particles dispersed in polymer hydrogels, with the particle size either less than or greater than the gel mesh size. When the particles are smaller than the gel mesh size, their acoustic vibration is resisted by only the background water medium, and the measured dynamic electrophoretic mobility, ?d (obtained in terms of colloid vibration current, CVI), is the same as in water. For the case of particles larger than the gel mesh size, ?d is decreased due to trapping, and the net decrease depends on the viscoelastic properties of the gel. The gel mesh size was varied by varying its crosslink density, the latter being characterized as the storage modulus, G’. The dependence of mobility on G’, for systems of a given particle size, and on particle size, for gels of a given G’, are investigated. The measured mobility remains constant as G’ is increased (i.e., mesh size is decreased) up to a value of approximately 300 Pa, beyond which it decreases. In the second set of measurements, the trapped particle size was increased in a gel medium of constant mesh size, with G’ approximately 100 Pa. In this case, the measured ?d is found to be effectively constant over the particle size range studied (14-120 nm), i.e., it is independent of the degree of trapping as expressed by the ratio of the particle size to the mesh size.

Bhosale, Prasad S.; Chun, Jaehun; Berg, John C.

2011-06-27

190

Sol-Gel Manufactured Energetic Materials  

Science.gov (United States)

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.

Simpson, Randall L. (Livermore, CA); Lee, Ronald S. (Livermore, CA); Tillotson, Thomas M. (Tracy, CA); Hrubesh, Lawrence W. (Pleasanton, CA); Swansiger, Rosalind W. (Livermore, CA); Fox, Glenn A. (Livermore, CA)

2005-05-17

191

Preparation and Characteristics of ADU gel Particles  

International Nuclear Information System (INIS)

HTGR (High Temperature Gas Reactor) energy technology development has been spot-lighted for a clean hydrogen gas and electricity production for the countermeasures of supplying a massive energy production in the next decades because other energies such as solar heat, wind power, and tidal energy, can only produce a small amount of electricity or they are not as effective. Generally, the production of spherical UO2 kernels for a HTGR nuclear fuel can be carried out by wet chemical processes, a sol-gel process, based on a solidification of uranium liquid droplets as a raw material. Sol-gel process is a proper way to produce the UO2 kernel because of its advantages in a high quality of products, low heat treatment temperature, and an easy control of the components. However, there are only a few reports on the preparation of a spherical UO2 kernel by a sol-gel method. In this study, spherical ADU gel particle and UO3 particles via an UN(uranyl nitrate, UO2(NO3) solution as a raw material were prepared. And the characteristics of these liquid droplets and the ADU gel particle prepared with the sol-gel method were analyzed, and the heat treatment characteristics from the ADU gel to UO3 particle were analyzed by a Streoscope, TG/DTA, and X-ray

2007-10-01

192

Water equivalence of polymer gel dosimeters  

Science.gov (United States)

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 ( Zeff), electron density ( ?e), photon mass attenuation coefficient ( ?/?), photon mass energy absorption coefficient ( ?en/?) and total stopping power (S/?)tot of electrons using the XCOM and the ESTAR database. The study showed that the effective atomic number of polymer gels were very close ( NIPAM which had the variation of 3%, 2% and 3%, respectively. The value of ?/? and ?en/? for all polymer gels were in close agreement ( <1%) with that of water beyond 80 keV. The value of (S/?)tot of electrons in polymer gel dosimeters were within 1% agreement with that of water. From the study we conclude that at lower energy ( <80 keV) the polymer gel dosimeters cannot be considered water equivalent and study has to be carried out before using the polymer gel for clinical application.

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

2007-07-01

193

FTIR thermal analysis on organofunctionalized silica gel  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Sílica gel modificada com grupos orgânicos tem sido muito utilizada como fase estacionária para cromatografia líquida. Reações de enxerto podem ser usadas na obtenção de superfícies modificadas estáveis de sílica gel. Neste trabalho a sílica gel (10 nm de diâmetro de poro e 320 m² g-1 de área superf [...] icial) foi modificada quimicamente com 3-cloropropiltrimetoxisilano ou com 3-aminopropiltrimetoxisilano e posteriormente com anilina, p-anisidina, benzilamina e 3-fenilpropilcloreto a fim de se obter grupos aromáticos imobilizados na superfície de sílica gel. A espectroscopia no infravermelho foi utilizada para a caracterização dos grupos aromáticos enxertados, usando-se uma cela de quartzo. Os sólidos foram aquecidos a várias temperaturas em alto vácuo sendo que as áreas sob as bandas dos grupos orgânicos obtidas no infravermelho foram usadas para estimar a estabilidade térmica. Abstract in english Silica gel modified with organic groups is widely used as a stationary phase for liquid chromatography. Grafting synthesis can be used to obtain stable modified silica gel surfaces. In this work, silica gel (10 nm of pore diameter and surface area of 320 m² g-1) was chemically modified with 3-chloro [...] propyltrimethoxysilane or 3-aminopropyltrimethoxysilane and reacted with aniline, p-anisidine, benzylamine and 3-phenylpropylchloride in order to yield aromatic groups immobilized on the silica gel surface. Infrared spectroscopy was utilized for characterization of the aromatic groups grafted on the silica gel surface, using a quartz cell. The solids were heated at several temperatures in high vacuum and the infrared band areas of the organic groups were used to evaluate the thermal stability.

José L., Foschiera; Tania M., Pizzolato; Edilson V., Benvenutti.

194

Acoustic evaluation of polymer gel dosimeters  

International Nuclear Information System (INIS)

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

2002-11-25

195

Pulsed field gel electrophoresis a practical guide  

CERN Document Server

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

Birren, Bruce

2012-01-01

196

Effect of rheology on gel placement  

Energy Technology Data Exchange (ETDEWEB)

This paper investigates whether rheology can be exploited to eliminate the need for zone isolation during gel placement. Eight different rheological models were used to represent the properties of existing non-Newtonian gelling agents. Gel placement was examined in linear and radial parallel corefloods and in fractured and unfractured injection wells. The analysis indicates that, compared with water-like gelling agents, existing non-Newtonian gelling agents will not reduce the need for zone isolation during gel placement in radial-flow systems.

Seright, R.S. (New Mexico Petroleum Recovery Research Center (US))

1991-05-01

197

Advances in sol-gel coating technologies  

Energy Technology Data Exchange (ETDEWEB)

Sol-gel coatings are thin, oxide layers applied from aqueous and non-aqueous media. In a dipping operation, the layer is typically less than one micron thick. This approach to depositing oxide layers has been used primarily in optical and electronic applications. Uses of these coatings in areas of wear and corrosion are known only in a few cases, such as semiconductor passivation layers or infiltrated fiber composites. The prospects for using sol-gel coatings for wear and corrosion are improving with new studies of electrochemical infiltration of gel layers and organic/inorganic hybrid layers. 57 refs., 6 figs., 2 tabs.

Klein, L.C. [Rutgers-The State Univ., Piscataway, NJ (United States). Ceramics Dept.; Sheppard, K. [Stevens Inst. of Technology, Hoboken, NJ (United States)

1995-12-31

198

Frictional properties of gel engineering materials with laser surface texturing  

Science.gov (United States)

Several synthesis methods have been devised to improve the mechanical strength of gels extraordinarily after 2001. It was a trigger to use gels as a new industrial materials, since gels had been considered difficult for industrial materials because of their weakness. In a recent study, we had designed transparency shape memory gels for the first time. Shape memory gels are one of the gels with characteristic networks, and have a shape memory function by copolymerizing an acrylic monomer with a hydrophobic long alkyl side group. It is well known that the mechanical properties such as Young's modulus and friction coefficient of shape memory gels depend on temperature. In this study, we tried to change the frictional properties of shape memory gels by laser surface texturing. Two types of processed surface were prepared. The hexagonal close packed pattern and the square close packed pattern of dimples were formed on the surface of gel sheets with CO2 laser. The intensity of laser was optimized to avoid cutting gels. The friction coefficients of unprocessed gels and two types of processed gels were measured by ball-on-disk method. Measurement partner material was sodalime glass ball. The measurement results of processed gels showed clear differences from unprocessed gels. The friction coefficients of processed gels were larger than unprocessed gels. However, these results specifically showed the velocity dependence. It indicates that surface texturing enable to control the friction coefficient of polymer gels by surface pattern and velocity.

Yamada, Naoya; Gong, Jin; Kabir, M. Hasnat; Makino, Masato; Maekawa, Keisuke; Wada, Masato; Furukawa, Hidemitsu

2014-03-01

199

Analysis of firing processes of titania gel films fabricated by sol-gel processes  

Energy Technology Data Exchange (ETDEWEB)

Firing processes of sol-gel-derived titania gel films were investigated by temperature programmed desorption (TPD), X-ray diffraction and X-ray photoelectron spectroscopy (XPS). Two kinds of gel films (T-1 and T-2) were prepared from Ti(OC{sub 2}H{sub 5}){sub 4} and TiCl{sub 4} as titanium sources, respectively. TPD results for both types of film showed different TPD curves depending on the titanium sources, indicating that the components in the gel films and their firing processes differed corresponding to the starting materials. The amounts of the evolved species were calculated on the basis of the TPD and XPS data. The Ti/O ratio in the titania gel films was estimated by analyzing the XPS and TPD results. These experiments also revealed that the crystallization temperature of the gel films corresponded to their components and Ti/O ratio.

Toshikazu, Nishide; Takayuki, Yabe; Nobuyoshi, Miyabayashi; Makiko, Sano

2004-11-22

200

Use of organic crosslinkers to control gel formation and gel properties  

Energy Technology Data Exchange (ETDEWEB)

Polymer gels can be used for blocking high permeability zones in an oil reservoir to improve sweep frequency and reduce water cut and therefore give improved oil recovery. In order to use polymer gels for near well treatment of high permeable zones it is important to know which variables are critical for the gel formation. It is also important to know the stability of the gel at conditions similar to reservoir conditions. This paper studies gel formation and stability using organically crosslinked polyvinyl alcohol (PVA)/dialdehyde, emphasizing the influence of pH, temperature and concentration of polymer and crosslinker on gelation rate and gel stability. Several experimental techniques have been used, including nuclear magnetic resonance (NMR). 7 refs., 8 figs., 4 tabs.

Olafsen, K.; Hansen, E.W.; Hustoft, A.G.; Jahr, D.M.; Stori, Aa.

1995-12-01

 
 
 
 
201

Sol-gel antireflective coating on plastics  

Science.gov (United States)

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.

Ashley, Carol S. (Albuquerque, NM); Reed, Scott T. (Albuquerque, NM)

1990-01-01

202

Radiation protection on polysaccharide solutions and gels  

International Nuclear Information System (INIS)

The effects of ionizing radiation on solutions of (1) sodium alginate, (2) alginate gels (wet and dry), (3) xanthan glum, (4), locust bean gum (LBG) and (5) carboxymethyl cellulose (CMC), have been investigated. Problems arise in the radiation sterilization of these gums (either as a solution or gel) due to reduction in their viscosity and the gel strength, caused by the high doses (25kGy) commonly used for the purpose of sterilization. The alginates used here were manugel DMB, manugel DPB and manucol DMF. The irradiations were carried out using 60Co-?-source and the gels and solutions were analysed by measurement of their apparent viscosities using a Brookfield viscometer L.V.T. (author)

1996-01-01

203

Radiation protection on polysaccharide solutions and gels  

Energy Technology Data Exchange (ETDEWEB)

The effects of ionizing radiation on solutions of (1) sodium alginate, (2) alginate gels (wet and dry), (3) xanthan glum, (4), locust bean gum (LBG) and (5) carboxymethyl cellulose (CMC), have been investigated. Problems arise in the radiation sterilization of these gums (either as a solution or gel) due to reduction in their viscosity and the gel strength, caused by the high doses (25kGy) commonly used for the purpose of sterilization. The alginates used here were manugel DMB, manugel DPB and manucol DMF. The irradiations were carried out using {sup 60}Co-{gamma}-source and the gels and solutions were analysed by measurement of their apparent viscosities using a Brookfield viscometer L.V.T. (author).

Bazafkan, Sedighealsharieh

1996-12-31

204

K-Basin gel formation studies  

International Nuclear Information System (INIS)

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

1998-01-01

205

K-Basin gel formation studies  

Energy Technology Data Exchange (ETDEWEB)

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.

Beck, M.A.

1998-07-23

206

Coordination Polymer Gels by Electron Beam  

International Nuclear Information System (INIS)

Hydrogenation of a pyridine derivative possessing tetrazole moieties as end groups, without long alkyl chain groups, results in the formation of a Mg(NO3)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 SO42-, NO3-, Cl-, Br- and I-, indicating that the coordination polymer gel formation of 1 does not strongly depends on anions. The Seam and ABM images of Mg2+ 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 ?-? transition and gives rise to high fluorescence behavior. The coordination polymer hydrogel exhibits viscoelastic behavior as evidenced from the rheological studies

2011-03-25

207

Maize Arabinoxylan Gels as Protein Delivery Matrices  

Directory of Open Access Journals (Sweden)

Full Text Available The laccase induced gelation of maize bran arabinoxylans at 2.5% (w/v in the presence of insulin or ?-lactoglobulin at 0.1% (w/v was investigated. Insulin and ?-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 ?-lactoglobulin (18 kDa, respectively. The results suggest that maize bran arabinoxylan gels can be potential candidates for the controlled release of proteins.

Ana Luisa Martínez-López

2009-04-01

208

Superconductive Ceramics Obtained with Sol Gel Method.  

Science.gov (United States)

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 ...

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

1988-01-01

209

Fricke xylenol gel energy dependence  

Energy Technology Data Exchange (ETDEWEB)

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{sup +2} oxidation to Fe{sup +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)

Costa, Rosangela T.; Moreira, Marcos V.; Almeida, Adelaide de, E-mail: dalmeida@ffclrp.usp.b, E-mail: marcos_vasques@yahoo.com.b [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Dept. de Fisica e Matematica

2009-07-01

210

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 gel...

2009-01-01

211

Ocular contact time of a carbomer gel (GelTears) in humans  

Digital Repository Infrastructure Vision for European Research (DRIVER)

BACKGROUND/AIMS—Carbomers are widely used in products for the treatment of dry eye; however, the polymer gel thins on addition of probes (for example, fluorescein salt) confounding the comparison of products by objective clinical tests such as spectrophotofluorimetry or scintigraphy. A novel method of radiolabelling carbomer gels, with minimum change to their rheology, has permitted the non-invasive evaluation of precorneal residence of the gel in volunteers using gamma scintigraphy. The te...

Wilson, C.; Zhu, Y. P.; Frier, M.; Rao, L.; Gilchrist, P.; Perkins, A.

1998-01-01

212

Absorption, luminescent and lasing properties of laser dyes in silica gel matrices and thin gel films  

International Nuclear Information System (INIS)

The absorption and emission properties of eight organic compounds in silica gel matrices of different chemical compositions and different types (bulk samples and thin films) are studied upon excitation by a XeCl laser and the second harmonic of a Nd:YAG laser. The mechanisms of the laser-induced changes in the spectral parameters of molecules in silica gel matrices are discussed and the photostability of the laser dyes in silica gel films is estimated. (active media)

2004-08-31

213

White-light-emitting supramolecular gels.  

Science.gov (United States)

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. PMID:24282050

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

2014-01-01

214

Orientation of DNA in agarose gels.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An orientation of the lambda DNA during the electrophoresis in agarose gels was measured by a microscopic linear dichroism technique. The method involved staining the DNA with the dye ethidium bromide and measuring under the microscope the polarization properties of the fluorescence field around the electrophoretic band containing the nucleic acid. It was first established that the fluorescence properties of the ethidium bromide-DNA complex were the same in agarose gel and in a solution. Then...

Borejdo, J.

1989-01-01

215

Elasticity of entangled polymer loops Olympic gels  

CERN Multimedia

In this note we present a scaling theory for the elasticity of olympic gels, i.e., gels where the elasticity is a consequence of topology only. It is shown that two deformation regimes exist. The first is the non affine deformation regime where the free energy scales linear with the deformation. In the large (affine) deformation regime the free energy is shown to scale as $F \\propto Hookian stress - strain relation is predicted.

Vilgis, T A

1997-01-01

216

GEL criteria for moment condition models  

Digital Repository Infrastructure Vision for European Research (DRIVER)

GEL methods which generalize and extend previous contributions are defined and analysed for moment condition models specified in terms of weakly dependent data. These procedures offer alternative one-step estimators and tests that are asymptotically equivalent to their efficient two-step GMM counterparts. The basis for GEL estimation is via a smoothed version of the moment indicators using kernel function weights which incorporate a bandwidth parameter. Examples for the choice of bandwidth pa...

Smith, Richard J.

2004-01-01

217

Fibroblast migration in fibrin gel matrices.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In healing wounds and many solid tumors, locally increased microvascular permeability results in extravasation of fibrinogen and its extravascular coagulation to form a fibrin gel, with concomitant covalent cross-linking of fibrin by factor XIIIa. Subsequently, inflammatory cells, fibroblasts, and endothelial cells migrate into the gel and organize it into granulation tissue and later into mature collagenous connective tissue. To gain insight into some of the cell migration events associated ...

Brown, L. F.; Lanir, N.; Mcdonagh, J.; Tognazzi, K.; Dvorak, A. M.; Dvorak, H. F.

1993-01-01

218

The yielding dynamics of a colloidal gel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Attractive colloidal gels display a solid-to-fluid transition as shear stresses above the yield stress are applied. This shear-induced transition is involved in virtually any application of colloidal gels. It is also crucial for controlling material properties. Still, in spite of its ubiquity, the yielding transition is far from understood, mainly because rheological measurements are spatially averaged over the whole sample. Here, the instrumentation of creep and oscillatory shear experiments...

Gibaud, Thomas; Frelat, Damien; Manneville, Se?bastien

2010-01-01

219

GEL methods for nonsmooth moment indicators  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper considers the first order large sample properties of the GEL class of estimators for models specified by non-smooth indicators. The GEL class includes a number of estimators recently introduced as alternatives to the efficient GMM estimator which may suffer from substantial biases in finite samples. These include EL, ET and the CUE. This paper also establishes the validity of tests suggested in the smooth moment indicators case for over-identifying restrictions and specification. I...

Parente, Paulo; Smith, Richard J.

2008-01-01

220

Controlling the Morphology of Carbon Gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

[EN] Carbon gels are unique porous carbons, which are typically obtained through the carbonization of resorcinol-formaldehyde gels. This material is practically an aggregate of nanometer-sized carbon particles. Nanopores, mostly in the size range of mesopores, exist between the particles. Smaller pores, micropores being the majority, also exist within the particles. Therefore, this material has a hierarchical pore system in which short micropores are directly connec...

Mukai, R. S.

2012-01-01

 
 
 
 
221

PRONIOSOMAL GEL OF FLURBIPROFEN: FORMULATION AND EVALUATION  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The purpose of this research is to design proniosomal gel drug delivery system of flurbiprofen in a trial to overcome the adverse effects associated with oral administration of the drug. This can be overcome by the use of vesicular drug delivery system. Encapsulation of a drug in vesicular structure can be predicted to prolong the existence of the drug in the systemic circulation and thus enhance penetration into target tissue and reduce toxicity. Proniosomal gels are generally present in ...

Sunil Kumar

2012-01-01

222

Brillouin scattering from cross-linked gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this letter we report Brillouin scattering measurements on methyl-methacrylate (MMA) gels crosslinked with varying amounts of ethylene-dimethacrylate (EDMA). We find that the k dependence of the phase velocity changes on increasing the cross-link content. For higher concentrations of crosslink we observe maxima and minima in the k dependence of the phase velocity. We associate these minima and maxima with spatial inhomogeneities in the gel, with the formation of regions of low and high cro...

1992-01-01

223

Serum release boosts sweetness intensity in gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 gum concentration the size of the pores present in the protein network, the permeability and the serum release increased, as well as the Young's modulus, the fracture stress and the fracture strain....

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

2010-01-01

224

Annular gel reactor for chemical pattern formation  

Energy Technology Data Exchange (ETDEWEB)

The present invention is directed to an annular gel reactor suitable for the production and observation of spatiotemporal patterns created during a chemical reaction. The apparatus comprises a vessel having at least a first and second chamber separated one from the other by an annular polymer gel layer (or other fine porous medium) which is inert to the materials to be reacted but capable of allowing diffusion of the chemicals into it.

Nosticzius, Zoltan (Budapest, HU); Horsthemke, Werner (Austin, TX); McCormick, William D. (Austin, TX); Swinney, Harry L. (Austin, TX); Tam, Wing Y. (Austin, TX)

1990-01-01

225

Method of manufacturino spherical gel particles  

International Nuclear Information System (INIS)

The thermally instable solution of a material intended for gelation and of hexamethylene tetramine and/or urea is dispersed in a heated dispersion medium immiscible with water. Gel particles formed are separated from the dispersion medium, incorporated in oil at a temperature of 1O to 60 degC and cooled in this bath to room temperature. The spherical gel particles formed show increased resistant to cracking and destruction in further production operations. (M.S.)

1979-01-01

226

A Practical Use for FXG Gel Dosimetry  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2010-11-01

227

Sol-gel derived PZT fibers  

International Nuclear Information System (INIS)

Sol-gel routes were developed to prepare densified PZT fibers. The effects of the degree of hydrolysis and the addition of an organic polymer to the precursor sol on fiber forming ability were investigated. In this paper results on the crystalline and microstructural development of gels and fibers are presented. The effects of the incorporation of excess PbO and sintering atmosphere are also discussed, particularly in relation to densification

1992-05-02

228

Carbon gels derived from natural resources  

Digital Repository Infrastructure Vision for European Research (DRIVER)

[EN] Most carbon gels investigated so far and reported in the literature were prepared from resorcinol crosslinked with formaldehyde in water, and were generally dried with supercritical CO2 before being pyrolysed. In the present paper, through some selected examples, we show how valuable carbon gels can be derived from other phenolic resources having a natural origin. Special emphasis is given to tannin and lignin, both derived from wood, as potential precursors of...

Celzard, A.; Fierro, V.; Amaral-labat, G.; Szczurek, A.; Braghiroli, F.; Parmentier, J.; Pizzi, A.; Grishechko, L. I.; Kuznetsov, B. N.

2012-01-01

229

Influence of drying conditions of zirconium molybdate gel on performance of 99mTc gel generator  

International Nuclear Information System (INIS)

99mTc can be produced from 99Mo/99mTc gel generators. These gels are part of the generator and the 99Mo/99mTc gel generator performance is directly related with gel structure. In this work a series of zirconium molybdate gels have been synthesized and dried under different conditions and characterized using thermal analysis (TGA, DTA), SEM, XRD and porosity measurements. It is found that the water content of the gel determines the structure porosity which allows the diffusion of the 99mTcO4- ions inside the gel and was directly connected with performance of the 99Mo/99mTc gel generators. Drying conditions of the gel is as an important factor that influence water content and physical-chemical properties of this gel and must be carefully studied to optimize the properties of the gel generators.

2009-10-01

230

Influence of drying conditions of zirconium molybdate gel on performance of {sup 99m}Tc gel generator  

Energy Technology Data Exchange (ETDEWEB)

{sup 99m}Tc can be produced from {sup 99}Mo/{sup 99m}Tc gel generators. These gels are part of the generator and the {sup 99}Mo/{sup 99m}Tc gel generator performance is directly related with gel structure. In this work a series of zirconium molybdate gels have been synthesized and dried under different conditions and characterized using thermal analysis (TGA, DTA), SEM, XRD and porosity measurements. It is found that the water content of the gel determines the structure porosity which allows the diffusion of the {sup 99m}TcO{sub 4}{sup -} ions inside the gel and was directly connected with performance of the {sup 99}Mo/{sup 99m}Tc gel generators. Drying conditions of the gel is as an important factor that influence water content and physical-chemical properties of this gel and must be carefully studied to optimize the properties of the gel generators.

Davarpanah, M.R. [Nuclear Science and Technology Research Institute, Nuclear Science Research School, P.O. Box 11365/8486, Tehran (Iran, Islamic Republic of); Attar Nosrati, S. [Nuclear Science and Technology Research Institute, Nuclear Science Research School, P.O. Box 11365/8486, Tehran (Iran, Islamic Republic of)], E-mail: snosrati@aeoi.org.ir; Fazlali, M.; Kazemi Boudani, M.; Khoshhosn, H.; Ghannadi Maragheh, M. [Nuclear Science and Technology Research Institute, Nuclear Science Research School, P.O. Box 11365/8486, Tehran (Iran, Islamic Republic of)

2009-10-15

231

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)

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.

Ricol, S.

1995-10-05

232

Optimized MR imaging for polyacrylamide gel dosimetry  

International Nuclear Information System (INIS)

Polyacrylamide gels are a powerful tool to measure radiation dose by quantifying the NMR T2 relaxation times of the irradiated gel. The exploitation of these radiation sensitive gels in clinical radiotherapy requires accurate mapping of T2 values. This paper describes the optimization strategy used to identify accurate and practical methods of measuring the range of T2 values typical of gel dosimeters (140-700 ms). The MR imaging techniques used to measure T2 values and the choice of image acquisition parameters are described. Four sequences are compared and the results are analysed in terms of accuracy, signal-to-noise ratio and acquisition time. A multiple spin echo sequence was found to yield the most accurate results (98.9%). Single spin echo sequences, such as Hahn spin echo and EPI spin echo, were found to measure gel T2 values with an accuracy of 90.1%. This paper reports the importance of careful selection and optimization of the MR imaging sequences for accurate and reliable polyacrylamide gel dosimetry. (author)

2000-04-01

233

FORMULATION AND EVALUATION OF CELECOXIB GEL  

Directory of Open Access Journals (Sweden)

Full Text Available The present research has been undertaken with the aim to develop a topical gel formulation of celecoxib, which would attenuate the gastrointestinal relater toxicities associated with oral administration and to investigate the effect of DMSO on permeation of celecoxib. Celecoxib is a highly selective cyclooxygenase-2 (cox-2 inhibitor.  In the present study gel with different concentrations of carbapol, sodium alginate and sodium carboxy methylcellulose were prepared. Gels were subjected for various evaluation tests such as pH measurement, spreadibility and extrudability. In-vitro dissolution studies were performed in phosphate buffer of pH 5.6 and polyethylene glycol 400 (7.4 pH for 12 hrs by using Keshary-Chien diffusion cell apparatus. The gel formulation consisting of 7.5% w/w sodium alginate with DMSO found to be suitable for topical application based on in vitro evaluation. Sodium alginate based gels with DMSO revealed of 90% cumulative drug release after 12 hours. From the above observations, Sodium alginate seems to be a promising pharmaceutical adjuvant in the formulation of celecoxib gels

Preeti Karade

2012-05-01

234

Sol-Gel derived glass-ceramics  

Energy Technology Data Exchange (ETDEWEB)

Usually, glass-ceramics are prepared by heating the shaped dense glass for crystallization without deformation or cracks. In order to avoid deformation or cracks, the glass must be crystallized through whole body of the glass; that is, bulk nucleation and subsequent growth of the nuclei to crystals have to take place. Accordingly, the suitable compositions are limited. It has been shown that gels prepared by the sol-gel method, in which the starting solution containing metal compounds are converted to sols and subsequently to gels through the hydrolysis and polycondensation reactions of the compounds, are crystallized in the whole body, forming glass-ceramics without deformation or cracks. This indicates that the sol-gel method may broaden the composition range for glass-ceramics formation. The examination of the data on bulk and surface nucleations in glasses and gels indicate that the easy bulk nucleation in gels may come from micropore surfaces which give high water contents at the crystallization temperatures. Detailed explanation will be given.

Sakka, S. [Fukui Univ. of Technology (Japan)

1995-12-01

235

Ultrasound increases flow through fibrin gels.  

Science.gov (United States)

Ultrasound accelerates fibrinolysis in vitro and in animal models of thrombosis. Since transport of fibrinolytic enzymes into clots by permeation may be an important determinant of the rate of fibrinolysis, we examined the effect of ultrasound on permeation through fibrin gels in vitro. Gels of purified fibrin were prepared in plastic tubes, and the rate of pressure-mediated fluid permeation was measured. Exposure to 1 MHz ultrasound at 2 W/cm2 and a duty cycle of 5 msec on, 5 msec off resulted in a significant (p = .005) increase in flow through the gel of 29.0 +/- 4.2% (SEM). The ultrasound-induced flow increase was intensity-dependent, increasing from 17.0 +/- 1.2% at 1 W/cm2 to 30.1 +/- 1.9% at 2.3 W/cm2. Increased flow was not due to heating, detachment of fibrin from the tube wall or fragmentation of the gel resulting in channeling. However, degassing the fluid by autoclaving significantly reduced the ultrasound-induced increase in flow. We conclude that exposure of fibrin gels to ultrasound increases pressure-mediated permeation. This effect may be related to cavitation-induced changes in fibrin gel structure, and could contribute to the accelerated fibrinolysis observed in an ultrasound field. PMID:7667834

Siddiqi, F; Blinc, A; Braaten, J; Francis, C W

1995-03-01

236

Gel-eletroforese no diagnóstico da varíola / Gel-electrophoresis in the smallpox diagnosis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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 t [...] estados 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. Abstract in english 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 tes [...] t, 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.

Mesquita, Julio A.; Homma, Akira; Schatzmayr, Hermann G..

237

The use of highly ordered vesicle gels as template for the formation of silica gels.  

Science.gov (United States)

A spontaneously forming gel of unilamellar vesicles based on sodium oleate (Na oleate) and 1-octanol as amphiphiles has been employed as a template in the formation of a silica gel formed by the hydrolysis of the inorganic precursor tetraethyl orthosilicate (TEOS). Up to about 10 wt % TEOS can be incorporated into this vesicle gel without phase separation and in a fully homogeneous formation process by simple mixing of the components. The process itself relies solely upon the self-organizing properties of this amphiphilic template system. The formation process was followed by means of time-resolved turbidity, rheology, and small-angle neutron scattering (SANS) experiments. It can be concluded that the presence of the precursor TEOS affects the kinetics of the process but the original vesicle gel structure is retained even up to highest TEOS content. The kinetic studies confirm that under the chosen conditions the vesicle formation proceeds much faster than the hydrolysis of TEOS and the subsequent formation of the silica gel. SANS displays in the low q-range an additional scattering due to the silica gel network, i.e., a hybrid material of an amphiphilic vesicle gel and an inorganic oxide gel is formed. Thus, this method is a very facile novel route of forming a highly ordered silica/vesicle gel by employing a self-organizing amphiphilic system as template and the formation of the silica network proceeds in a fully homogeneous fashion under kinetic control. PMID:21692463

Oppel, Claudia; Prévost, Sylvain; Noirez, Laurence; Gradzielski, Michael

2011-07-19

238

Aqueous gel for heat storage pond and method for making the gel  

Energy Technology Data Exchange (ETDEWEB)

A gel is formed by copolymerizing an acrylic monofunctional monomer and an acrylic bifunctional monomer in an aqueous solution exposed to an oxygen containing atmosphere. Spontaneous polymerization takes place in an atmosphere containing oxygen after the solution is placed in sunlight, or in the dark if the solution also contains a dissolved inorganic salt. The gel so formed is transparent to solar radiation, and is stable in the presence of such radiation and of temperatures in the vicinity of the boiling point of water. As a consequence, the gel is suitable for covering a heat storage liquid and thermally insulates the liquid against significant conductive heat loss to an ambient medium above the gel. By providing a myriad of small bubbles trapped in the gel, the insulating efficiency of the gel is increased without significantly interferring with the transmission of solar radiation to the heat storage layer below the gel. A gel having such bubbles is produced by including constituents in the solution from which the gel is formed which produce a gas (i.e., CO/sub 2/).

Yogev, A.; Mahlab, D.

1984-07-24

239

Ferramentas diagnósticas de Lentivirose de Pequenos Ruminantes: padronização da técnica de ELISA indireto / Diagnostic tools of small ruminant lentiviruses: standardization of indirect ELISA  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese As Lentiviroses de Pequenos Ruminantes (LVPR) incluem a Maedi-Visna (MV) em ovinos e a Artrite Encefalite Caprina (CAE). Essas enfermidades estão difundidas no mundo e são responsáveis por grandes perdas na produtividade destes animais. Os LVPR são vírus RNA da subfamíl [...] ia Lentivirinae que causam uma infecção persistente, sendo a detecção precoce uma das formas mais eficientes para limitar sua disseminação no rebanho. Visando contribuir com essas questões, este experimento foi realizado na Universidade Federal do Piauí (UFPI) em parceria com a Embrapa Caprinos e Ovinos, com o objetivo de padronizar a técnica de ensaio imunoenzimático indireto e compará-lo com a imunodifusão em gel de agarose no diagnóstico da CAE. Foram utilizadas 696 amostras de soros de caprinos machos e fêmeas oriundas do banco de soros da Unidade de Pesquisa de LVPR do Centro de Ciências Agrárias da UFPI. As amostras foram coletadas no período de janeiro de 2007 a março de 2010. Na padronização, verificou-se que 0,25 µg de proteína/poço, diluição de 1:200 do soro e concentração de 1:3.000 do conjugado anticorpo anti-IgG cabra apresentaram os melhores resultados. O ponto de corte obtido foi de 0,36. Na comparação, o Imunodifusão em Gel de Ágar (IDGA) detectou 128 (18,4%) amostras positivas, e o ELISA indireto (ELISA-i), 259 (37,2%). A sensibilidade e a especificidade do teste ELISA-i com relação ao IDGA foi de 94,5% e 75,7%, respectivamente. Verificou-se maior índice de positividade em caprinos acima de seis meses (p < 0,05), e nos machos obteve-se prevalência de 56,7% em comparação às fêmeas, 35,4%, (p < 0,01). Abstract in english The Small Ruminant Lentiviruses (SRLVs) include Maedi-Visna (MV) of sheep and Caprine Arthritis-Encephalitis (CAE). These diseases are widespread and responsible for major production losses regarding sheep and goats. The SRLV is a RNA virus of the subfamily Lentivirus genus that causes persistent in [...] fections in goats. Early detection is one of the best ways to limit its spread in the herd. To contribute to these issues, this experiment was conducted at Universidade Federal do Piauí in partnership with Embrapa Goats and Sheep, with the objective of standardizing the technique of indirect ELISA (i-ELISA) and to compare it with Immunodiffusion in Agarose Gel to diagnose Caprine Lentiviruses (LC). Six hundred ninety six serum samples were used from the University Veterinary Hospital, Universidade Federal do Piauí, from January 2007 to March 2010. Standardization showed that 0.25 µg protein/well, a 1:200 dilution of the serum and concentration of 1:3,000 of the conjugated anti-goat IgG presented the best results. It was observed that the Agar Gel Immunodiffusion (AGID) detected 128 (18.4%) positive samples, and ELISA, 259 (37.2%). The sensitivity and specificity of i-ELISA regarding AGID were 94.5% and 75.7%, respectively. A higher prevalence was observed among animals older than six months (p < 0.05). The prevalence among males was of 56.7%, and among females, 35.4% (p < 0.01).

Nascimento, Caliandra Bona; Pinheiro, Raymundo Rizaldo; Alves, Francisco Selmo Fernandes; Brito, Roberta Lomonte Lemos de; Rodrigues, Apoliana de Sousa; Bezerra e Silva, Ricardo Abílio; Paula, Ney Rômulo de Oliveira; Batista, Maria do Carmo de Souza.

240

Interaction between hepatocytes and collagen gel in hollow fibers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Gel entrapment culture of primary mammalian cells within collagen gel is one important configuration for construction of bioartificial organ as well as in vitro model for predicting drug situation in vivo. Gel contraction in entrapment culture, resulting from cell-mediated reorganization of the extracellular matrix, was commonly used to estimate cell viability. However, the exact influence of gel contraction on cell activities has rarely been addressed. This paper investigated the gel contr...

Dai, Jing; Zhang, Guo-liang; Meng, Qin

2009-01-01

 
 
 
 
241

Bradyrhizobium japonicum Survival in and Soybean Inoculation with Fluid Gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The utilization of gels, which are used for fluid drilling of seeds, as carriers of Bradyrhizobium japonicum for soybean (Glycine max (L.) Merr.) inoculation was studied. Gels of various chemical composition (magnesium silicate, potassium acrylate-acrylamide, grafted starch, and hydroxyethyl cellulose) were used, although the hydroxyethyl cellulose gels were more extensively investigated. Gel inocula were prepared by mixing gel powder with liquid cultures of B. japonicum (2% [wt/vol]). The po...

Jawson, Michael D.; Franzluebbers, Alan J.; Berg, Robert K.

1989-01-01

242

Soroprevalence and risk factors associated to “Brucella canis” infection in dogs from Campina Grande, Paraíba Soroprevalência e fatores de risco associados à infecção por Brucella canis em cães da  

Directory of Open Access Journals (Sweden)

Full Text Available The prevalence of brucellosis due to Brucella canis was investigated in dogs from Campina Grande, Paraíba, Northern region of Brazil, and the risk factors for seropositivity were also analyzed. For this purposes, 170 dogs’ blood samples were collected during the rabies vaccination campaign, in September, 2003. The agar gel immunodiffusion test (AGID, by Brucella ovis lipopolysaccharides and proteins antigens, sample Reo 198, was used for serological diagnosis. The seroprevalence was 2.35% (95% CI = 0.64% - 5.91%. The epidemiological evidences showed that canine brucellosis due to Brucella canis in this area presented no association with the variables sex, age and management, however, there was statistic association between Brucella canis seropositivity and abortions occurrence.Foi investigada a soroprevalência de brucelose canina por Brucella canis em cães da cidade de Campina Grande, estado da Paraíba, Brasil, e realizado um estudo de possíveis fatores de riscos associados à soropositividade. Foram examinadas 170 amostras de soro sangüíneo de cães colhidas durante a campanha de vacinação anti-rábica animal, realizada em setembro de 2003. Para o diagnóstico sorológico da infecção por Brucella canis, foi empregada a prova de imunodifusão em gel de ágar (IDGA, utilizando antígeno de lipopolissacarídeos e proteínas de Brucella ovis, amostra Reo 198. A soroprevalência encontrada foi de 2,35% (IC 95% = 0,64% - 5,91%. O perfil epidemiológico da doença mostrou que o agente infecta em iguais condições os animais sem diferença de sexo, tipo de manejo e idade, havendo, contudo, associação estatística entre soropositividade para Brucella canis e ocorrência de abortamentos.

Robério Macedo de Oliveira

2008-09-01

243

Estudio serológico de fiebre aftosa y brucelosis en rebaños mixtos de camélidos y ovinos en la ecorregión de serranía en Apolobamba, La Paz - Bolivia / Foot and mouth disease and brucellosis serological survey in mixed herds of camelids and sheep in the highlands of Apolobamba eco-region, La Paz - Bolivia  

Scientific Electronic Library Online (English)

Full Text Available SciELO Peru | Language: Spanish Abstract in spanish El objetivo del presente estudio fue determinar niveles serológicos de anticuerpos contra fiebre aftosa y brucelosis en rebaños mixtos de alpacas y ovejas en cuatro comunidades de la ecorregión serranía en el Área Natural de Manejo Integrado Nacional Apolobamba, La Paz - Bolivia, colindante con Perú [...] . Se colectaron 99 muestras de sangre de alpacas y 42 de ovinos de ambos sexos y edad diversa. Las muestras se procesaron mediante la prueba de inmunodifusión en gel agar para detectar anticuerpos VIA contra el virus de la fiebre aftosa y las pruebas de Aglutinación Rápida en Placa (prueba tamiz) y ELISA de competición (c-ELISA) (prueba confirmativa) para la detección de anticuerpos contra cepas lisas de Brucella sp. No se detectó anticuerpos contra fiebre aftosa o brucelosis. Abstract in english The objective of the present study was to determine serological levels of antibodies against foot and mouth disease (FMD) and brucellosis in mixed herds of alpacas and sheep in four communities of the highland ecorregion of the Apolobamba Protected Area (National Integrated Management Natural Area - [...] ANMIN), La Paz - Bolivia, bordering with Peru. Blood samples of 99 alpacas and 42 sheep of different sex and ages were collected. Plasma samples were tested for the detection of VIA antibodies against FMD virus using the agar gel immunodiffusion test (AGID-VIA) and for the detection of antibodies against smooth strains of Brucella spp. using a plate agglutination test as screening and a competitive ELISA (c-ELISA) as a confirmatory test. The results of the study showed no seropositive reactors for FMD or brucellosis.

Beltrán-Saavedra S, L. Fabián; Ticona Ch, Herminio; Nallar G, Rodolfo; Gonzáles R, José Luis.

244

Anticorpos anti Brucella abortus, anti Brucella canis e anti Leptospira spp. em raposas (Pseudalopex vetulus do semiárido paraibano, Nordeste do Brasil Detection of anti Brucella abortus, anti Brucella canis and anti Leptospira spp. Antibodies in hoary foxes (Pseudalopex vetulus from semi-arid of Paraiba state, Northeastern region of Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available O objetivo do presente trabalho foi determinar a ocorrência de anticorpos anti Brucella abortus, anti Brucella canis e anti Leptospira spp. em raposas (Pseudalopex vetulus. Para tanto, foram utilizadas 60 raposas atropeladas em rodovias no semiárido da Paraíba, Nordeste do Brasil. Para a detecção de anticorpos anti Brucella abortus, o teste do antígeno acidificado tamponado (AAT foi empregado como teste de triagem, e a prova do 2-mercaptoetanol foi empregada como método confirmatório. Para o diagnóstico sorológico das infecções por Brucella canis e Leptospira spp., foram utilizados os testes de imunodifusão em gel de agar (IDGA e soroaglutinação microscópica, respectivamente. Todas as amostras foram negativas na pesquisa de anticorpos anti Brucella canis e anti Leptospira spp. Das 60 raposas testadas, 16 (26,6% foram positivas para anticorpos anti Brucella abortus no teste de AAT, e quatro (6,7% amostras foram confirmadas no teste de 2-mercaptoetanol, sendo duas amostras com título 100 e duas com título 50.The aim of this research was to determine the occurrence of anti Brucella abortus, anti B. canis and anti Leptospira spp. antibodies in foxes (Pseudalopex vetulus. Sixty road-killed wild foxes from semi-arid of Paraiba state, Northeastern region of Brazil, were used. For the detection of anti B. abortus antibodies, the buffered plate agglutination test (BPAT was applied as a screening method and the 2-mercaptoethanol test as a confirmatory method. For serological diagnosis of infections by B. canis and Leptospira spp., the agar gel immunodiffusion test (AGID and the microscopic agglutination test (MAT were used, respectively. All samples were negative for anti B. canis and anti Leptospira spp. antibodies. Of the 60 foxes tested, 16 (26.6 % were positive for anti B. abortus antibodies at BPAT, four (6.7% samples were confirmed in the 2-mercaptoethanol test, and two samples presented titer 100 and two titer 50.

Sérgio Santos de Azevedo

2010-02-01

245

Evolution of gel structure during thermal processing of Na-geopolymer gels.  

Science.gov (United States)

The present work examines how the gel structure and phase composition of Na-geopolymers derived from metakaolin with varied Si/Al ratio evolve with exposure to temperatures up to 1000 degrees C. Gels were thermally treated and characterized using quantitative XRD, DTA, and FTIR to elucidate the changes in gel structure, phase composition, and porosity at each stage of heating. It is found that the phase stability, defined by the amount and onset temperature of crystallization, is improved at higher Si/Al ratios. Two different mechanisms of densification have been isolated by FTIR, related to viscous flow and collapse of the highly distributed pore network in the gel. Gels with low Si/Al ratio only experience viscous flow that correlates with low thermal shrinkage. Gels at a higher Si/Al ratio, which have a homogeneous microstructure composed of a highly distributed porosity, undergo both densification processes corresponding to a large extent of thermal shrinkage during densification. This work elucidates the intimate relationship between gel microstructure, chemistry, and thermal evolution of Na-geopolymer gels. PMID:17014113

Duxson, Peter; Lukey, Grant C; van Deventer, Jannie S J

2006-10-10

246

New polymer gel dosimeters consisting of less toxic monomers with radiation-crosslinked gel matrix  

International Nuclear Information System (INIS)

New polymer gel dosimeters consisting of less toxic methacrylate-type monomers such as 2-hydroxymethyl methacrylate (HEMA) and polyethylene glycol 400 dimethacrylate (9G) with hydroxypropyl cellulose (HPC) gel were prepared. The HPC gels were obtained by using a radiation-induced crosslinking technique to be applied in a matrix instead of a gelatin, which is conventionally used in earlier dosimeters, for the polymer gel dosimeters. The prepared polymer gel dosimeters showed cloudiness by exposing to 60Co ?-ray, in which the cloudiness increased with the dose up to 10 Gy. At the same dose, the increase in the cloudiness appeared with increasing concentration of 9G. As a result of the absorbance measurement, it was found that the dose response depended on the composition ratio between HEMA and 9G.

2013-06-26

247

New polymer gel dosimeters consisting of less toxic monomers with radiation-crosslinked gel matrix  

Science.gov (United States)

New polymer gel dosimeters consisting of less toxic methacrylate-type monomers such as 2-hydroxymethyl methacrylate (HEMA) and polyethylene glycol 400 dimethacrylate (9G) with hydroxypropyl cellulose (HPC) gel were prepared. The HPC gels were obtained by using a radiation-induced crosslinking technique to be applied in a matrix instead of a gelatin, which is conventionally used in earlier dosimeters, for the polymer gel dosimeters. The prepared polymer gel dosimeters showed cloudiness by exposing to 60Co ?-ray, in which the cloudiness increased with the dose up to 10 Gy. At the same dose, the increase in the cloudiness appeared with increasing concentration of 9G. As a result of the absorbance measurement, it was found that the dose response depended on the composition ratio between HEMA and 9G.

Hiroki, A.; Yamashita, S.; Sato, Y.; Nagasawa, N.; Taguchi, M.

2013-06-01

248

Long time response of soft magnetorheological gels.  

Science.gov (United States)

Swollen physical magnetorheological (MR) gels were obtained by self-assembling of triblock copolymers containing dispersed soft magnetic particles. The transient rheological responses of these systems were investigated experimentally. Upon sudden application of a homogeneous magnetic field step change, the storage modulus of MR gels continued to increase with time. Such increase trend of the storage modulus could be expressed by a double-exponential function with two distinct modes, a fast and a slow one. The result was compared with the transient rheological response of equivalent MR fluids (paraffin oil without copolymer) and a MR elastomer (PDMS) and interpreted as the consequence of strong rearrangement of the original particle network under magnetic field. Similar to the structure evolution of MR fluids, the ensemble of results suggests that "chaining" and "clustering" processes are also happening inside the gel and are responsible for the rheological behavior, provided they are happening on a smaller length scale (long chains and clusters are hindered). We show that response times of several minutes are typical for the slow response of MR gels. The characteristic time t(2) for the slow process is significantly dependent on the magnetic flux density, the matrix viscoelastic property, particle volume fraction, and sample's initial particle distribution. In order to validate our results, the role of dynamic strain history was clarified. We show that, in the linear viscoelastic region, the particle rearrangement of MR gels was not hindered or accelerated by the dynamic strain history. PMID:22439870

An, Hai-Ning; Sun, Bin; Picken, Stephen J; Mendes, Eduardo

2012-04-19

249

Toward sol-gel-based sensors  

Energy Technology Data Exchange (ETDEWEB)

Advances in biotechnology have produced a variety of antibodies and other biomolecules that possess selective recognition capabilities. Current techniques for the immobilization of these biomolecules typically involve multistep derivatization of a primary substrate, which is labor intensive and often requires large volumes of costly reagents. Further, these immobilization chemistries often adversely affect the characteristic properties of the protein (e.g., the binding affinity). As a result, the need for fast, accurate, inexpensive, and simple to operate diagnostic assays escalates. Because of their room temperature processing, transparency, inertness, and tunable pore structure, sol-gel-derived composites represent promising chemical and biosensing platforms. To date, many researchers have entrapped proteins and enzymes in sol-gel monoliths, and found that they retain some of their native properties. Our group first reported on the affinity of a sol-gel entrapped antibody. However, although these biogel monoliths were promising, analyte diffusion through the monolith matrix is slow, resulting in long response times. Thus, it is clear that the next level of sol-gel-derived biosensor must depend on thin film technology. In the current work, the affinity of fluorescein entrapped within a sol-gel derived thin film for the anti fluorescent hapten, 5- (and 6-)-carboxy 4{prime}, 5{prime}-dimethylfluorescein, is investigated. A novel film preparation technique will be introduced, and the response and response times of these films as a function of processing and storage conditions will be discussed.

Jordan, J.D.; Ingersoll, C.M.; Dunbar, R.A. [State Univ. of New York, Buffalo, NY (United States)] [and others

1995-12-31

250

Sol-gel processing of ceramics  

Energy Technology Data Exchange (ETDEWEB)

The sol-gel process is an extremely versatile method for preparing metal oxide based materials. The wide applicability of the process arises from the enormous range of inorganic and metal-organic precursors which can be utilised as well as the ability to incorporate organic, inorganic and biological molecules with specific functions into the final products. Sol-gel products can be obtained in the form of powders or as molded pieces (monoliths), fibres or thin films. This review describes the general principles of the sol-gel process concentrating primarily on the `organic route`, which makes use of the readily hydrolysable metal alkoxides. Such compounds are formed by all the metallic elements thus giving enormous potential for the formation of their oxides by a common procedure. A general description of the basic chemistry of these precursors is provided together with a discussion of the factors that influence their hydrolysis and the polymerisation of the hydrolysis products. These are the two most important processes involved in the formation of sols and gels. Finally, applications of the sol- gel process are described concentrating mainly on products which are presently available on the market with some coverage of products that are close to commercialization or are excellent commercial prospects. Copyright (1996) Institute of Metals and Materials Australasia Ltd. 73 refs., 1 tab., 4 figs.

Spiccia, L.; West, B.O. [Monash University, Clayton, VIC (Australia). Centre for Chemical Synthesis, Department of Chemistry; Watkins, I.D. [Silicon Technologies Australia Limited, Queenbeyan, NSW (Australia)

1996-12-31

251

RegStatGel: proteomic software for identifying differentially expressed proteins based on 2D gel images  

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Image analysis of two-dimensional gel electrophoresis is a key step in proteomic workflow for identifying proteins that change under different experimental conditions. Since there are usually large amount of proteins and variations shown in the gel images, the use of software for analysis of 2D gel images is inevitable. We developed open-source software with graphical user interface for differential analysis of 2D gel images. The user-friendly software, RegStatGel, contains fully aut...

Li, Feng; Seillier-moiseiwitsch, Franc?oise

2011-01-01

252

Sol-gel synthesis of hydroxyapatite  

International Nuclear Information System (INIS)

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)

2010-11-21

253

Sol-gel preparation of zirconium oxide  

Energy Technology Data Exchange (ETDEWEB)

Preparing catalytic materials via the sol-gel route offers the ability to control product properties by changing the so-called sol-gel parameters in any of the processing steps. Some of these parameters are the type of precursor, acid and water content, temperature, solvent, and drying conditions. For example, we have prepared aerogels that are precursors to zirconium oxide by starting with either a metal alkoxide or preformed sols. The properties of the calcined oxides, in term of surface area, pore characteristics, and crystal structure, vary significantly with the starting material. The removal of solvent from aerogels with supercritical drying leads to aerogels, the properties of which are also dependent on synthetic parameters such as the amounts of acid and water used. Finally, drying temperature itself offers another level of control over the same physical properties. We will discuss these observations in terms of the underlying sol-gel chemistry.

Ko, E.I. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

1995-12-01

254

Gel composition and method of treatment  

Energy Technology Data Exchange (ETDEWEB)

This patent describes a method of treating at least one of formations intersected by a well bore. It comprises: introducing into one of the plurality of formations which has a permeability which differs from another of the formations a first aqueous solution comprising a polymeric material selected from a biopolymer or a synthetic polymer, a crosslinking agent comprising a chromic carboxylate complex, a solvent selected from water or brine and a gel breaker consisting essentially of ethylenediaminetetraacetic acid, the polymeric material crosslinking with the chromic carboxylate complex to form a gel impervious to fluid flow, the ethylenediaminetetraacetic acid being present in amount sufficient to break the gel after a predetermined period of time to a predetermined degree whereby limited permeability is restored to the one of the plurality of formations, the limited permeability more closely matching the permeability of the another of the formations.

Falk, D.O.

1991-04-30

255

Two-dimensional difference gel electrophoresis.  

Science.gov (United States)

Two-dimensional difference gel electrophoresis (2D DIGE) is a modified form of 2D electrophoresis (2DE) that allows one to compare two or three protein samples simultaneously on the same gel. The proteins in each sample are covalently tagged with different color fluorescent dyes that are designed to have no effect on the relative migration of proteins during electrophoresis. Proteins that are common to the samples appear as "spots" with a fixed ratio of fluorescent signals, whereas proteins that differ between the samples have different fluorescence ratios. With the appropriate imaging system, difference gel electrophoresis (DIGE) is capable of reliably detecting as little as 0.2 fmol of protein, and protein differences down to ±15%, over a ?20,000-fold protein concentration range. DIGE combined with digital image analysis therefore greatly improves the statistical assessment of proteome variation. Here we describe a protocol for conducting DIGE experiments, which takes 2-3 days to complete. PMID:22585495

Minden, Jonathan S

2012-01-01

256

Sol gel process for nuclear fuels  

International Nuclear Information System (INIS)

Sol-gel processes are alternate routes for the fabrication of Pu and 233U based fuels as they offer many advantages over the conventional powder pellet processes of fuel fabrication. The sol-gel processes are solution based routes and eliminate handling of radiotoxic powders and are highly amenable to remote handling. Internal gelation process one of the important sol gel routes has been developed at BARC to fabricate microspheres of controlled size and shape of variety fuel materials like UO2, ThO2, (U,Pu)O2, (U,Th)O2, UC,UN etc. The SGMP process has also been developed for the fabrication of pellets of UO2, ThO2, (U,Pu)O2, (U,Th)O2 using the respective oxide microspheres. (author)

2009-10-01

257

Ageing of uranyl gel spherical particles  

International Nuclear Information System (INIS)

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 H2O and NH3 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)

1978-01-01

258

Produção e padronização dos antígenos de Paracoccidioides brasiliensis (Pb), Histoplasma capsulatum (Hc) e Aspergillus fumigatus (Af) para uso no imunodiagnóstico: comparação entre as técnicas de imunodifusão e imunoeletroosmoforese / Production and standardization of Paracoccidioides brasiliensis, Histoplasm capsulatum and Aspergillus fumigatus antigens to be used in immunodiagnosis: comparison between immunodiffusion and immunoelectrophoresis technics  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Foram produzidos antígenos solúveis de P. brasiliensis, H. capsulatum e A. fumigatus e padronizados nas técnicas de imunodifusão dupla (IDD) e imunoeletroosmoforese (IEOF). A especificidade dos antígenos foi testada utilizando-se 96 soros de pacientes com paracoccidioidomicose, histoplasmose, asperg [...] ilose, candidíase sistêmica, esporotricose, tuberculose, neoplasia pulmonar, leishmaniose tegumentar e visceral e em 18 indivíduos sadios. Na IDD, a especificidade foi de 100% usando-se como critério de positividade linhas de precipitação com identidade total com soro de referência. Entretanto na IEOF, a especificidade variou de acordo com o antígeno testado, sendo observadas reações cruzadas com antígeno de P. brasiliensis frente a soros de pacientes com histoplasmose (16,7%) e leishmaniose tegumentar (10%) e com antígeno de H. capsulatum frente a soros de pacientes com paracoccidioidomicose (31,8%) e leishmaniose tegumentar (10%). Ambas as técnicas mostraram a mesma sensibilidade para o sorodiagnóstico de paracoccidioidomicose, histoplasmose e aspergilose, respectivamente 100%, 83,3% e 100%. A grande sensibilidade e especificidade da IDD observadas nos soros desses pacientes, aliadas à fácil reprodutibilidade e baixo custo, fazem esta técnica muito apropriada como procedimento de rotina, para a triagem de pacientes sintomáticos respiratórios. Abstract in english Soluble antigens (Ag) from Paracoccidioides brasiliensis, Histoplasma capsulatum and Aspergillus fumigatus were prepared and standardized by double immunodiffusion (DID) and immunoelectroosmophoresis (IEOP). No difference in sensitivity was observed between the two techniques; 100% of standard patie [...] nt sera were positive with P. brasiliensis and A. fumigatus Ag and 83.3% were positive with H. capsulatum Ag. The specificity of the tests was verified testing 96 sera from patients with paracoccidioidomycosis, histoplasmosis, systemic candidiasis, sporotrichosis, tuberculosis, lung cancer, visceral or cutaneous leishmaniasis and 18 sera from healthy individuals. All the three antigens were 100% specific with the DID (using the identification pattern indicated by the confluence of test serum with standard serum precipitin lines as a positive criterium). However in the IEOP, the specificity varied with each Ag. Positive reactions with P. brasiliensis Ag were observed in 16.7% of histoplasmosis sera and in 10% of cutaneous leishmaniasis sera. On the other hand 31.8% of paracoccidioidomycosis and 10% of cutaneous leishmaniasis sera reacted with H. capsulatum Ag. The high sensitivity and specificity of the DID test, its easy reproducibility and low cost, led us to consider it highly appropriate as a routine procedure for the screening of patients with respiratory infections.

Maria de Fátima, Ferreira-da-Cruz; Bernardo, Galvão-Castro; Bodo, Wanke.

259

Produção e padronização dos antígenos de Paracoccidioides brasiliensis (Pb, Histoplasma capsulatum (Hc e Aspergillus fumigatus (Af para uso no imunodiagnóstico: comparação entre as técnicas de imunodifusão e imunoeletroosmoforese Production and standardization of Paracoccidioides brasiliensis, Histoplasm capsulatum and Aspergillus fumigatus antigens to be used in immunodiagnosis: comparison between immunodiffusion and immunoelectrophoresis technics  

Directory of Open Access Journals (Sweden)

Full Text Available Foram produzidos antígenos solúveis de P. brasiliensis, H. capsulatum e A. fumigatus e padronizados nas técnicas de imunodifusão dupla (IDD e imunoeletroosmoforese (IEOF. A especificidade dos antígenos foi testada utilizando-se 96 soros de pacientes com paracoccidioidomicose, histoplasmose, aspergilose, candidíase sistêmica, esporotricose, tuberculose, neoplasia pulmonar, leishmaniose tegumentar e visceral e em 18 indivíduos sadios. Na IDD, a especificidade foi de 100% usando-se como critério de positividade linhas de precipitação com identidade total com soro de referência. Entretanto na IEOF, a especificidade variou de acordo com o antígeno testado, sendo observadas reações cruzadas com antígeno de P. brasiliensis frente a soros de pacientes com histoplasmose (16,7% e leishmaniose tegumentar (10% e com antígeno de H. capsulatum frente a soros de pacientes com paracoccidioidomicose (31,8% e leishmaniose tegumentar (10%. Ambas as técnicas mostraram a mesma sensibilidade para o sorodiagnóstico de paracoccidioidomicose, histoplasmose e aspergilose, respectivamente 100%, 83,3% e 100%. A grande sensibilidade e especificidade da IDD observadas nos soros desses pacientes, aliadas à fácil reprodutibilidade e baixo custo, fazem esta técnica muito apropriada como procedimento de rotina, para a triagem de pacientes sintomáticos respiratórios.Soluble antigens (Ag from Paracoccidioides brasiliensis, Histoplasma capsulatum and Aspergillus fumigatus were prepared and standardized by double immunodiffusion (DID and immunoelectroosmophoresis (IEOP. No difference in sensitivity was observed between the two techniques; 100% of standard patient sera were positive with P. brasiliensis and A. fumigatus Ag and 83.3% were positive with H. capsulatum Ag. The specificity of the tests was verified testing 96 sera from patients with paracoccidioidomycosis, histoplasmosis, systemic candidiasis, sporotrichosis, tuberculosis, lung cancer, visceral or cutaneous leishmaniasis and 18 sera from healthy individuals. All the three antigens were 100% specific with the DID (using the identification pattern indicated by the confluence of test serum with standard serum precipitin lines as a positive criterium. However in the IEOP, the specificity varied with each Ag. Positive reactions with P. brasiliensis Ag were observed in 16.7% of histoplasmosis sera and in 10% of cutaneous leishmaniasis sera. On the other hand 31.8% of paracoccidioidomycosis and 10% of cutaneous leishmaniasis sera reacted with H. capsulatum Ag. The high sensitivity and specificity of the DID test, its easy reproducibility and low cost, led us to consider it highly appropriate as a routine procedure for the screening of patients with respiratory infections.

Maria de Fátima Ferreira-da-Cruz

1985-09-01

260

Sol-gel synthesis of orthosilicates ????-???? ?????? ?????????????  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The objective of the research is the sol-gel preparation of the crystalline or amorphous orthosilicates of some bivalent metals, namely, copper orthosilicate (Cu2SiO4), which seems to be a quite efficient catalyst, although it has not been synthesized yet. The main obstacles that prevent the sol-gel synthesis of orthosilicates include high metal/silica molar ratios in precursor mixtures. They cause (i) formation of the crystalline of metal oxides at intermediate stages of synthesis and (ii) a...

Malyavskiy Nikolay Ivanovich; Pokidko Boris Vladimirovich

2012-01-01

 
 
 
 
261

Development of Stable Restructured Mango Gel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Restructured mango gel was prepared by alginate texturization of mango pulp using sodium alginate, glucono-?-lactone and calcium hydrogen orthophosphate. The requisite quantities of the chemical additives were mixed, added together to the neutralized mango pulp in a mixer and allowed to set at 4°C for 16 h. The mango gel was cut into 1.5 cm cubes and stabilized by Hurdle Technology (HT) through adjustment of water activity to 0.89, pH 4.4 and pasteurization in polypropylene pouches. Storage...

Das Gupta, D. K.; Roopa, N.; Leela, R. K.

2007-01-01

262

Process for encapsulating active agents in gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 biopolymer is at least partially dissolved before and/or after addition of the active agent. The gels obtained with the present invention are particularly suitable for coating or impregnating packagi...

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

2001-01-01

263

Effective Management of FXG Gel Dosimetry  

Energy Technology Data Exchange (ETDEWEB)

The details of a calibration basis for the Fricke-xylenol orange-gelatin (FXG) gel dosimeter combined with the fast, easily accessible readout tool of cone beam optical computed tomography (CT) are described in this report. With proper controls in place, the results from a test intensity modulated radiation therapy (IMRT) treatment plan evaluation indicate that greater than 95% Low's gamma function agreement between plan and gel-measured dose using 3% dose and 3 mm distance-to-agreement criteria is achievable.

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

2010-11-01

264

An x-ray CT polymer gel dosimetry prototype: II. Gel characterization and clinical application  

International Nuclear Information System (INIS)

This article reports on the dosimetric properties of a new N-isopropylacrylamide, high %T, polymer gel formulation (19.5%T, 23%C), optimized for x-ray computed tomography (CT) polymer gel dosimetry (PGD). In addition, a new gel calibration technique is introduced together with an intensity-modulated radiation therapy (IMRT) treatment validation as an example of a clinical application of the new gel dosimeter. The dosimetric properties investigated include the temporal stability, spatial stability, batch reproducibility and dose rate dependence. The polymerization reaction is found to stabilize after 15 h post-irradiation. Spatial stability investigations reveal a small overshoot in response for gels imaged later than 36 h post-irradiation. Based on these findings, it is recommended that the new gel formulation be imaged between 15–36 h after irradiation. Intra- and inter-batch reproducibility are found to be excellent over the entire range of doses studied (0–28 Gy). A significant dose rate dependence is found for gels irradiated between 100–600 MU?min?1. Overall, the new gel is shown to have promising characteristics for CT PGD, however the implication of the observed dose rate dependence for some clinical applications remains to be determined. The new gel calibration method, based on pixel-by-pixel matching of dose and measured CT numbers, is found to be robust and to agree with the previously used region of interest technique. Pixel-by-pixel calibration is the new recommended standard for CT PGD. The dose resolution for the system was excellent, ranging from 0.2–0.5 Gy for doses between 0–20 Gy and 0.3–0.6 Gy for doses beyond 20 Gy. Comparison of the IMRT irradiation with planned doses yields excellent results: gamma pass rate (3%, 3 mm) of 99.3% at the isocentre slice and 93.4% over the entire treated volume. (paper)

2012-05-21

265

An x-ray CT polymer gel dosimetry prototype: II. Gel characterization and clinical application  

Science.gov (United States)

This article reports on the dosimetric properties of a new N-isopropylacrylamide, high %T, polymer gel formulation (19.5%T, 23%C), optimized for x-ray computed tomography (CT) polymer gel dosimetry (PGD). In addition, a new gel calibration technique is introduced together with an intensity-modulated radiation therapy (IMRT) treatment validation as an example of a clinical application of the new gel dosimeter. The dosimetric properties investigated include the temporal stability, spatial stability, batch reproducibility and dose rate dependence. The polymerization reaction is found to stabilize after 15 h post-irradiation. Spatial stability investigations reveal a small overshoot in response for gels imaged later than 36 h post-irradiation. Based on these findings, it is recommended that the new gel formulation be imaged between 15-36 h after irradiation. Intra- and inter-batch reproducibility are found to be excellent over the entire range of doses studied (0-28 Gy). A significant dose rate dependence is found for gels irradiated between 100-600 MU?min-1. Overall, the new gel is shown to have promising characteristics for CT PGD, however the implication of the observed dose rate dependence for some clinical applications remains to be determined. The new gel calibration method, based on pixel-by-pixel matching of dose and measured CT numbers, is found to be robust and to agree with the previously used region of interest technique. Pixel-by-pixel calibration is the new recommended standard for CT PGD. The dose resolution for the system was excellent, ranging from 0.2-0.5 Gy for doses between 0-20 Gy and 0.3-0.6 Gy for doses beyond 20 Gy. Comparison of the IMRT irradiation with planned doses yields excellent results: gamma pass rate (3%, 3 mm) of 99.3% at the isocentre slice and 93.4% over the entire treated volume.

Johnston, H.; Hilts, M.; Carrick, J.; Jirasek, A.

2012-05-01

266

Normoxic polymer gel - basic characterisation and clinical use  

Energy Technology Data Exchange (ETDEWEB)

The formulation for a new polymer gel, which is made under normal atmospheric conditions, has been published. Because manufacturing and processing can be performed under normal atmospheric conditions, the gel is also called normoxic. Only a few accessories for gel production are necessary, facilitating the use of this gel, which can be easily produced in a clinical environment. The purpose of this study, which is work in progress, was to produce several gel batches with varying concentrations of their compounds, to measure dose response curves, to investigate ageing effects and to use this polymer gel in 3D absolute dose verifications in radiosurgery, IMRT and proton therapy.

Scheib, S G [Department of Medical Radiation Physics, Klinik Im Park, Zurich (Switzerland); Vogelsanger, W [Kantonsschule Schaffhausen, Schaffhausen (Switzerland); Gianolini, S [Department of Medical Radiation Physics, Klinik Im Park, Zurich (Switzerland); Crescenti, R [Institute of Biomedical Engineering, Federal Institute of Technology, Zurich (Switzerland)

2004-01-01

267

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

International Nuclear Information System (INIS)

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)

1988-04-24

268

Detección de Mycobacterium avium subespecie paratuberculosis, por medio de PCR-anidada a partir de muestras de heces de ovinos / Detection of Mycobacterium avium subspecies paratuberculosis by nested-PCR of ovine fecal samples  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish La paratuberculosis es una enteritis granulomatosa de curso crónico ocasionada por Mycobacterium avium subespecie paratuberculosis (Map), afecta a rumiantes domésticos y silvestres. Map es excretada en las heces de animales que desarrollan la enfermedad, y la transmisión de la infección se da median [...] te la ingestión de alimentos y agua contaminados por heces de animales infectados. Con el objetivo de establecer el diagnóstico de paratuberculosis en ovinos por medio de la PCR-anidada a partir de muestras de heces, se trabajaron 204 muestras de heces y sueros de ovinos; las heces se evaluaron por PCR-anidada y cultivo bacteriológico, las muestras de sueros fueron analizadas por medio de inmunodifusión en agar gel (lDGA). Con la PCR-anidada se obtuvo un producto de amplificación 210 pb que corresponde a la IS900 de Map, en 61 de las 204 muestras. De éstas, 43 eran de animales positivos a IDGA y 18 negativos. Mediante cultivo bacteriológico se aislaron 17 cepas de Map; en este contexto, la IDGA detectó a 91 animales como positivos. La PCR-anidada permitió detectar en menor tiempo a mayor cantidad de animales que estaban eliminando al bacilo, aun cuando habían resultado negativos a la prueba serológica; este resultado se considera importante, ya que generalmente estos animales, al permanecer dentro de la granja, constituyen la principal fuente de infección para el rebaño. Se debe considerar a la PCR-anidada como alternativa, cuando se requiera el diagnóstico en breve tiempo, para conocer el estado sanitario del rebaño con respecto a paratuberculosis. Abstract in english Paratuberculosis is a chronic granulomatous enteritis caused by Mycobacterium avium subspecies paratuberculosis (Map), which affects wild and domestic ruminants. Map is shed in feces from infected animals. Transmission of the infection takes place by oral ingestion of the bacterium from contaminated [...] food and water with feces. With the objective to establish a paratuberculosis diagnosis in ovine by nested-PCR from fecal samples, 204 fecal and serum ovine samples were studied. Feces were evaluated by nested-PCR and bacterial culture, serum samples were analyzed by agar gel immunodiffusion (AGID). Nested-PCR yielded a 210 bp amplification product that corresponds to Map-IS900, in 61 out of 204 samples. From these, 43 were from AGID positive animals and 18 from negative animals. Seventeen Map strains were isolated by bacterial culture and AGID detected 91 positive animals. Nested-PCR allowed to detect, sooner, greater number of animals shedding bacillus, even when they had resulted negative to the serological test. This result is considered important because generally these animals, while remaining in the farm, constitute the main source of infection for the herd. Nested-PCR should be considered as an alternative, when a prompt result is required to know the health status of the herd with respect to paratuberculosis.

Norma G, Jaimes; Marco Antonio, Santillán Flores; Oscar A, Hernández Cruz; Dionisio, Córdova López; Claudia Celic, Guzmán Ruiz; Beatriz, Arellano Reynoso; Efrén, Díaz Aparicio; Víctor R, Tenorio Gutiérrez; Alfredo, Cuéllar Ordaz.

269

Thermosensitive sol-gel reversible hydrogels.  

Science.gov (United States)

Aqueous polymer solutions that are transformed into gels by changes in environmental conditions, such as temperature and pH, thus resulting in in situ hydrogel formation, have recently attracted the attention of many investigators for scientific interest and for practical biomedical or pharmaceutical applications. When the hydrogel is formed under physiological conditions and maintains its integrity for a desired period of time, the process may provide various advantages over conventional hydrogels. Because of the simplicity of pharmaceutical formulation by solution mixing, biocompatibility with biological systems, and convenient administration, the pharmaceutical and biomedical uses of the water-based sol-gel transition include solubilization of low-molecular-weight hydrophobic drugs, controlled release, labile biomacromolecule delivery, such as proteins and genes, cell immobilization, and tissue engineering. When the formed gel is proven to be biocompatible and biodegradable, producing non-toxic degradation products, it will provide further benefits for in vivo applications where degradation is desired. It is timely to summarize the polymeric systems that undergo sol-gel transitions, particularly due to temperature, with emphasis on the underlying transition mechanisms and potential delivery aspects. This review stresses the polymeric systems of natural or modified natural polymers, N-isopropylacrylamide copolymers, poly(ethylene oxide)/poly(propylene oxide) block copolymers, and poly(ethylene glycol)/poly(D,L-lactide-co-glycolide) block copolymers. PMID:11755705

Jeong, Byeongmoon; Kim, Sung Wan; Bae, You Han

2002-01-17

270

Pulsed field gel electrophoresis of Staphylococcus epidermidis.  

Science.gov (United States)

Pulsed field gel electrophoresis (PFGE) is one of the older methods for the molecular characterization and comparison of microorganisms including bacteria. Nevertheless, PFGE continues to be recognized as the gold standard for molecular typing due to output spanning >90 % of the bacterial genome and standardized protocols and reagents applicable to a wide range of organisms including S. epidermidis. PMID:24222454

Goering, Richard V; Fey, Paul D

2014-01-01

271

Non-diffusing radiochromic micelle gel  

Energy Technology Data Exchange (ETDEWEB)

The addition of Laponite, a synthetic clay nanoparticle material to radiochromic leuco Malachite Green micelle hydrogel eliminates diffusion of the cationic dye by electrostatic binding. The clay nanoparticles also increased dose sensitivity ten-fold relative to the parent gel formulation. This material is a suitable 3D water equivalent dosimeter with optical CT readout.

Jordan, Kevin; Sekimoto, Masaya, E-mail: Kevin.jordan@lhsc.on.c [London Regional Cancer Program, London Health Sciences Centre and Department of Medical Biophysics, University of Western Ontario, London, ON (Canada)

2010-11-01

272

Simple Cloud Chambers Using Gel Ice Packs  

Science.gov (United States)

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…

Kamata, Masahiro; Kubota, Miki

2012-01-01

273

Polyacrylamide gel polymerization with adjustable gelation rate.  

Czech Academy of Sciences Publication Activity Database

. Ro?. 32, - (2002), s. 740-742. ISSN 0736-6205Grant CEP: GA AV ?R KSK5052113; GA ?R GA521/00/0075Klí?ová slova: polyacrylamide gelKód oboru RIV: CD - Makromolekulární chemieImpakt faktor: 2.173, rok: 2002

Wiesner, Ivo; Wiesnerová, Dana

274

Sol-Gel Derived Hafnia Coatings  

Science.gov (United States)

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.

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

2002-01-01

275

Sol-Gel Synthesis Of Aluminoborosilicate Powders  

Science.gov (United States)

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.

Bull, Jeffrey; Leiser, Daniel; Selvaduray, Guna

1992-01-01

276

Scaling of megabase DNA undergoing gel electrophoresis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a simple description of configuration and dynamical properties of megabase DNA undergoing gel electrophoresis. The molecule moves in the field in the shape of a self-similar tree-like structure. The electrophoretic mobility of DNA in this regime is independent of its molecular weight.

Obukhov, S.; Rubinstein, M.

1993-01-01

277

Gel electrophoresis for elemental speciation purposes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This work has shown that gel electrophoresis is a relevant fractionation method for trace elements bound to or complexed by macromolecules. Furthermore, detection methods of the trace elements that do not rely on the use of radiotracers were applied, making this combination relevant for materials of human origin, where the use of radioactive material is restricted for reasons of safety.

Che?ry, Cyrille Ce?dric

2003-01-01

278

Mobility of microparticles in protein gel  

Energy Technology Data Exchange (ETDEWEB)

The hematite Fe{sub 2}O{sub 3} submicron particles, 90 and 170 nm in diameter, exhibit bounded diffusion in water voids formed by gelatin networks in gel. Such particles occupy two different types of local states, distinguished by the microviscosity.

Fornal, Piotr [Cracow University of Technology, Institute of Physics (Poland); Stanek, Jan, E-mail: Jan.Stanek@uj.edu.pl; Wilk, Alicja [Jagiellonian University, Marian Smoluchowski Institute of Physics (Poland)

2008-07-15

279

Easy Silica Gel Supported Desymmetrization of PEG  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Our work shows how poly(ethylene glycol), differentially functionalized at two ends, can be easily and efficiently synthesized from commercial symmetric dihydroxy PEG 600. First, we linked the polymer onto functionalized silica gel using one of its hydroxy ends. Then, the second hydroxy group was modified, and finally, the desymmetrized PEG was cleaved from the solid support.

La Ferla, Barbara; Zona, Cristiano; Nicotra, Francesco

2009-01-01

280

The charge transport in polymeric gel electrolytes  

CERN Document Server

The aim of the present thesis consisted in the study of the charge transport in gel electrolytes, which were obtained by photopolymerization of oligo(ethylene glycol) sub n -dimethacrylates with n=3, 9, and 23, and the survey of structure and property relations for the optimization of the electrolyte composition. The pressure dependence of the electric conductivity was measured. (HSI)

Reiche, A

2001-01-01

 
 
 
 
281

Mechanical properties and morphology of polymer gels  

Science.gov (United States)

Understanding morphology and mechanical response of polymeric gels is of particular importance to design materials with required energy dissipation characteristics. We will present our latest results for polymer gels based on 1) self-assembled block copolymers and 2) chemically cross-linked polymers. The dissipative particle dynamics (DPD) was used to predict morphology in good agreement with atomic force microscopy. We have performed DPD non-equilibrium oscillatory shear calculations predicting elastic modulus of unentangled gels that correlates well with experimental rheology data. However, this methodology fails to predict mechanics of entangled polymer networks due to unphysical chain crossing brought by the soft potentials used in DPD simulations. Recently, we have introduced an improved segmental repulsion potential that removes the bond crossing allowing for reptation dynamics. The improved DPD method was used in simulations for entangled gels to explore impact of branched architecture of solvent on the mechanical response to the tensile deformation. Novel architectures of solvent resulting in a dramatic increase of the elastic modulus were identified. The topological analysis was applied to understand contributions of chemical cross-links and entanglements to the stress.

Sliozberg, Yelena; Sirk, Timothy; Brennan, John; Andzelm, Jan; Mrozek, Randy; Lenhart, Joseph

2012-02-01

282

Decontamination of radioactive uranium by chemical gels  

Energy Technology Data Exchange (ETDEWEB)

Chemical decontamination technology represents a highly effective removal of radioactive contamination through chemical dissolution or a Redox reaction. However, the generation of large amounts of waste limits its use as an in-situ technology. Therefore, to avoid the well-known disadvantages of chemical decontamination techniques while retaining their high decontamination efficiency, it is necessary to develop processes using chemical gels instead of chemical solutions. This method is effective in situations in which long contact times are required, and when a need to minimize waste exists. A chemical deco nta-mi nation gel can be prepared by adding gelling agents composed of a viscosifier and a coviscosifier to the chemical decontamination agents used in traditional decontamination processes. The appropriate combination of viscosifier and coviscosifier is a very important factor in the control of the viscosity and adhesion properties of chemical decontamination gels. Gelling agents were prepared by adding PEG-based non-ionic coviscosifiers (diethylene glycol hexyl ether and tripropylene glycol butyl ether, and tripropylene glycol dodecyl ether) into a stable pyro Si viscosifier. The decontamination and rheological behaviors of chemical gels prepared in a Ce(IV).HNO{sub 3} or HNO{sub 3} based solution for tile surfaces contaminated with uranium radionuclides were investigated.

Jung, Chong Hun; Moon, J. K.; Choi, B. S.; Won, H. J.; Choi, W. K.; Kim, C. K. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-10-15

283

Cell viability in a wet silica gel.  

Science.gov (United States)

A modified two-step sol-gel route using silicon ethoxide (TEOS) has been used to synthesize amorphous sol-gel-derived silica, which has been successfully used as a cell encapsulation matrix for 3T3 mouse fibroblasts and CRL-2595 epithelial cells due to its non-toxicity. The sol-gel procedure comprised a first, low pH hydrolysis step, followed by a neutral condensation-gelation step. A high water-to-TEOS ratio and the addition of d-glucose as a porogen and source of nutrients were chosen to minimize silica dissolution and improve the biocompatibility of the process. Indeed, the cell integrity in the encapsulation process was preserved by alcohol removal from the starting solution. Cells were then added in a buffered medium, causing rapid gelation and entrapment of the cells within a randomly structured siloxane matrix in the shape of a monolith, which was maintained in the wet state. MTT and alamarBlue assays were used to check the cytotoxicity of the silica gels and the viability of entrapped cells at initial times in contact with silica. To improve cell attachment, cell clumping experiments - where groups of cells were formed - were designed, rendering improved viability. The obtained materials are therefore excellent candidates for designing tissue-culture scaffolds and implantable bioreactors for biomedical applications. PMID:19481618

Nieto, Alejandra; Areva, Sami; Wilson, Timothy; Viitala, Reeta; Vallet-Regi, Maria

2009-11-01

284

Relationships between the sol-to-gel and gel-to-glass conversions  

Energy Technology Data Exchange (ETDEWEB)

Multicomponent gels were prepared with a wide range of pH- water combinations so that the skeletal structure of the desiccated gels varied from being less highly (low pH, low H/sub 2/O) to more highly (high pH, high H/sub 2/O) polymerized. The apparent value of isothermal viscosity, determined by isothermal shrinkage experiments, was found to increase with time, presumably due to polymerization and structural relaxation of the skeletal framework. This increase was dramatic (>200X) for less highly polymerized gels but was found to occur in all cases, and it therefore is predicted to be a general property of metal alkoxide-derived gels.

Brinker, C.J.; Scherer, G.W.

1983-01-01

285

Sol-Gel Synthesis of Au-Nanoparticle Dispersed Bicontinuous Macroporous Siloxane Gel  

Energy Technology Data Exchange (ETDEWEB)

We synthesized Au-nanoparticle dispersed siloxane gel with well-defined bicontinuous macroporous morphologies. We employed methyltrimethoxysilane (MTMS) as a precursor of the gel skeleton, and also employed hydrogen tetrachloroaurate(III) as both a precursor of Au nanoparticles and an acid catalyst for hydrolysis/condensation of methoxysilanes. The effect of adding (3-mercaptopropyl)trimethoxysilane (MPTMS) as a starting material on the obtained structure was also investigated. It is found that Au nanoparticles of 20-30 nm in grain size are uniformly dispersed on the gel surface in the system containing MPTMS; in contrast, Au nanoparticles assembled in the pits in the MPTMS-free system. All the heat-treated MPTMS-containing gels showed surface plasmon absorption, and the peaks shifted from 550 to 520 nm with increasing the calcination temperature.

Hamada, Y; Nishi, M; Shimotsuma, Y; Miura, K; Hirao, K, E-mail: west@collon1.kuic.kyoto-u.ac.jp [Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan)

2011-10-29

286

Structure and properties of resorcinol-formaldehyde gels.  

Science.gov (United States)

The condensation polymerization of resorcinol and formaldehyde catalized by sodium carbonate produces a sol that aggregates to form a gel. Using viscometry the effect of temperature and catalyst concentration on the sol-gel transition was investigated. At...

S. A. Letts S. R. Buckley F. M. Kong E. F. Lindsey M. L. Sattler

1989-01-01

287

Gel-Based and Gel-Free Quantitative Proteomics Approaches at a Glance  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two-dimensional gel electrophoresis (2-DE) is widely applied and remains the method of choice in proteomics; however, pervasive 2-DE-related concerns undermine its prospects as a dominant separation technique in proteome research. Consequently, the state-of-the-art shotgun techniques are slowly taking over and utilising the rapid expansion and advancement of mass spectrometry (MS) to provide a new toolbox of gel-free quantitative techniques. When coupled to MS, the shotgun proteomic pipeline ...

Cosette Abdallah; Eliane Dumas-Gaudot; Jenny Renaut; Kjell Sergeant

2012-01-01

288

On the Structure and Dynamics of Polyelectrolyte Gel Systems and Gel-surfactant Complexes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis describes the results of experimental work on polyelectrolyte gels and their interaction with oppositely charged surfactants, and presents two new algorithms applicable to the simulation of colloid and polymer systems. The model systems investigated were crosslinked poly(acrylate) (PA) and poly(styrene sulphonate) (PSS), and the surfactant was dodecyl trimethylammonium bromide (DoTAB). Pure gel materials were studied using dynamic light scattering. It was shown that the diffusion ...

Ra?smark, Per Johan

2004-01-01

289

Effects of Gel Thickness on Microscopic Indentation Measurements of Gel Modulus  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In vitro, animal cells are mostly cultured on a gel substrate. It was recently shown that substrate stiffness affects cellular behaviors in a significant way, including adhesion, differentiation, and migration. Therefore, an accurate method is needed to characterize the modulus of the substrate. In situ microscopic measurements of the gel substrate modulus are based on Hertz contact mechanics, where Young's modulus is derived from the indentation force and displacement measurements. In Hertz ...

Long, Rong; Hall, Matthew s; Wu, Mingming; Hui, Chung-yuen

2011-01-01

290

Gel2DE - A software tool for correlation analysis of 2D gel electrophoresis data  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background: Two-dimensional gel electrophoresis (2DE) is a powerful technique for studying protein isoforms and their modifications. Existing commercial 2D image analysis tools rely on spot detection that limits analysis of complex protein profiles, e.g. spot appearance/disappearance or overlapping spots. Pixel-by-pixel correlation analysis, an analysis technique for identifying relations between protein patterns in gel images and external variables, can overcome such limitations in...

Øye, Ola Kristoffer; Jørgensen, Katarina Mariann; Hjelle, Sigrun Margrethe; Sulen, Andre?; Ulvang, Dag Magne; Gjertsen, Bjørn Tore

2013-01-01

291

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

International Nuclear Information System (INIS)

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

1995-01-01

292

Concept to control the phase behavior of stimulisensitive polymer gel  

Energy Technology Data Exchange (ETDEWEB)

The phase control (phase transition, hydrophobic-hydrophilic balance) of a thermosensitive polymer gel was performed by an electrochemical method at constant temperature. The relationships of the amount of charge supplied to induce the phase transition of gel, ionic content and electrolyte content were examined. The mechanism of electrochemical phase control of gel was clarified in terms of ionic transport in the gel. 12 refs., 6 figs.

Seida, Y.; Nakano, Y. [Tokyo Institute of Technology, Tokyo (Japan)

1995-08-20

293

Automatic DNA sequencing for electrophoresis gels using image processing algorithms  

Digital Repository Infrastructure Vision for European Research (DRIVER)

DNA electrophoresis gel is an important biologically experimental technique and DNA sequencing can be defined by it. Traditionally, it is time consuming for biologists to exam the gel images by their eyes and often has human errors during the process. Therefore, automatic analysis of the gel image could provide more information that is usually ignored by human expert. However, basic tasks such as the identification of lanes in a gel image, easily done by human experts, emerge as problems that...

Jiann-Der Lee; Chung-Hsien Huang; Neng-Wei Wang; Chin-Song Lu

2011-01-01

294

Interaction between Crosslinked Polyelectrolyte Gels and Oppositely Charged Surfactants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The interactions between anionic, crosslinked gels and cationic surfactants have been investigated. When exposed to oppositely charged surfactant, the gel collapses into a dense complex of polyion and micelles. During deswelling, the gel phase separates into a micelle-rich, collapsed surface phase, and a swollen, micelle-free core, both still part of the same network. As more surfactant is absorbed, the surface phase grows at the expense of the core, until the entire gel has collapsed. Polyac...

Nilsson, Peter

2007-01-01

295

Comparison Between the Elasticity of Polyacrylamide and Polyacrylic Gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We measured the Young modulus E of polyacrylamide and polyacrylic gels as a function of the crosslink and polymer concentrations. We found that the variation of E with these two parameters is completely different for the two kinds of gels. For the polyacrylic gels, E is an increasing function of the crosslink and polymer concentrations. However, in the case of the polyacrylamide gels, E increases with polymer concentration but not always with the crosslink concentration. For low polymer conce...

1995-01-01

296

Relationship between texture of gels and flavour release  

Digital Repository Infrastructure Vision for European Research (DRIVER)

To provide further insight into the relationship between the structure of hydrocolloid solutions and gels and perception of taste and flavour, solutions of gelatin and locust bean gum, and gels prepared from mixtures of (a) high acyl and low acyl gellan (b) carrageenan and locust bean gum were studied. Both solutions contained sodium chloride and the gels were flavoured with ethyl butyrate. The gels were classified from rheological measurements into 3 categories: strong/brittle, intermedi...

Koliandris, Andreas

2009-01-01

297

Preparation of silica by sol-gel method using formamide  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this work we obtained microporous and mesoporous silica gels by sol-gel processing. Tetraethylortosilicate (TEOS) was used as precursor. Nitric acid and hydrofluoric acid were used as catalysts. In order to study the affect of formamide as drying additive, we used a molar ratio alkoxide/formamide of 1/1. The performance of formamide in obtaining crack-free gels was evaluated through monolithicity measurements. The structural evolution occurring in the interconnected network of the gels dur...

Lenza, R. F. S.; Vasconcelos, W. L.

2001-01-01

298

A multistimuli-responsive photochromic metal-organic gel.  

Science.gov (United States)

A photochromic metal-organic gel with thermo-, photo-, and anion-responsive behavior is obtained. Unusually, heating of the Al-ligand solution leads to gel formation and cooling to room temperature reverses the process to reform the solution. The gel is sensitive to weakly coordinating anions. Additionally, reversible photochromic transformations take place both in the solution and gel states, accompanied by reversibly switched luminescence. PMID:24339174

Wei, Shi-Chao; Pan, Mei; Li, Kang; Wang, Sujuan; Zhang, Jianyong; Su, Cheng-Yong

2014-04-01

299

Improvements in or relating to the drying of gel materials  

International Nuclear Information System (INIS)

A process is described for the drying of a gel material, comprising mixing together steam and gas in controlled amounts to form a mixture, feeding the mixture to a gel material to be dried thereby to contact the gel material with an atmosphere containing steam and gas in controlled amounts and thereby dry the gel material. One application of the process is in the production of ceramic particles for nuclear fuels. (author)

1981-01-01

300

Gel dosimetry for HDR Brachytherapy 3-D distribution through MRI  

International Nuclear Information System (INIS)

Gel dosimetry using MRI is increasingly being utilized in contemporary literature. In our work we investigated the calibration of an acrylic gel by means of imaging with magnetic resonance and its application to the dose measurement in a 3D distribution 192Ir HDR brachytherapy treatment. Early gel dosimetry used Fricke gels and T1 relaxation time. In 2001 Fong et al. introduced a new normoxic gel known as ''MAGIC'' gel, the main components of which are Metacrylic Acid (polymer) and Hydroquinone ( polymerizing inhibitor). For this material, the evidence of radiation dose is indicated by a change in the T2 relaxation time on an MR image. Later studies varied concentrations of the MAGIC gel components in order to observe its effect and the behavior of the gel sensitivity, for magnetic fields over 0.5 T. In the 1980s a series of studies on dose quantification using magnetic resonance images and Fricke gels were performed by evaluating T1 signal through means of an Inversion Recovery technique. Polymer gels have been developed to avoid the adverse effects of oxygen that plague Fricke gels. Normoxic gels have a component which helps to capture the oxygen dissolved in the gel (MAGIC). For these type of gels, measurements of T2 are made using a Spin-Echo technique. For both groups of gels, the Relaxativity compared to either T1 or T2 varies linearly with the absorbed dose. Novotny et al. has obtained a dose response curve for BANG-2 gel showing a linear relationship of 1/T2 vs D[Gy]. In the work presented here we tested and found the same linear relation between spin-spin relaxation (R2=1/T2) versus dose up to 8.0Gy

2010-11-09

 
 
 
 
301

Formulation and method for preparing gels comprising hydrous hafnium oxide  

Science.gov (United States)

Formulations useful for preparing hydrous hafnium oxide gels contain a metal salt including hafnium, an acid, an organic base, and a complexing agent. Methods for preparing gels containing hydrous hafnium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including hafnium, an acid, an organic base, and a complexing agent.

Collins, Jack L; Hunt, Rodney D; Montgomery, Frederick C

2013-08-06

302

Formulation and method for preparing gels comprising hydrous cerium oxide  

Science.gov (United States)

Formulations useful for preparing hydrous cerium oxide gels contain a metal salt including cerium, an organic base, and a complexing agent. Methods for preparing gels containing hydrous cerium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including cerium, an organic base, and a complexing agent.

Collins, Jack L; Chi, Anthony

2013-05-07

303

Formulation and method for preparing gels comprising hydrous aluminum oxide  

Energy Technology Data Exchange (ETDEWEB)

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.

Collins, Jack L.

2014-06-17

304

Advanced ceramics by sol-gel processing  

International Nuclear Information System (INIS)

Sol-gel processing techniques have been used at Ansto to prepare a wide range of advanced ceramic materials, including Synroc, nanoceramics, electronic ceramics, bioceramics, thin films and membranes and multicomponent powders. The major current project involves the production of uniform, 30 to 50 microns spherical Synroc particles, with a high sorption capacity for nuclear waste. These particles are produced by spray-drying a concentrated titania/zirconia sol manufactured using proprietary techniques developed by the Advanced Materials Program at Ansto. A ceramic membrane filter is also being developed for the industrial processing of hot liquids. The filtration membrane is fabricated using sol-gel methods to produce a ceramic layer about 10 microns thick with closely controlled nano-sized pores. ills

1991-12-01

305

Uncertainty analysis in polymer gel dosimetry.  

Science.gov (United States)

Verification of advanced radiotherapy treatment modalities requires measurement of three-dimensional absorbed dose distributions with high spatial resolution and precision. Polymer gel dosimeters combined with magnetic resonance imaging may be able to fulfil this requirement. However, verification requires that the uncertainty in the dosimeter is well known. One method of estimating the overall uncertainty in polymer gel dosimeters involves the propagation of the uncertainty in the R2 (nuclear magnetic resonance relaxation rate) map and the uncertainties in the calibration data. This work shows that using this method with current data suggests that the lowest uncertainty currently obtainable is about 3% at 8 Gy and 7% at 2 Gy. Furthermore, the most significant reductions in overall uncertainty will be achieved by reducing the noise in the R2 map. PMID:10588291

Baldock, C; Murry, P; Kron, T

1999-11-01

306

NOTE: Uncertainty analysis in polymer gel dosimetry  

Science.gov (United States)

Verification of advanced radiotherapy treatment modalities requires measurement of three-dimensional absorbed dose distributions with high spatial resolution and precision. Polymer gel dosimeters combined with magnetic resonance imaging may be able to fulfil this requirement. However, verification requires that the uncertainty in the dosimeter is well known. One method of estimating the overall uncertainty in polymer gel dosimeters involves the propagation of the uncertainty in the R2 (nuclear magnetic resonance relaxation rate) map and the uncertainties in the calibration data. This work shows that using this method with current data suggests that the lowest uncertainty currently obtainable is about 3% at 8 Gy and 7% at 2 Gy. Furthermore, the most significant reductions in overall uncertainty will be achieved by reducing the noise in the R2 map.

Baldock, C.; Murry, P.; Kron, T.

1999-11-01

307

Acoustic evaluation of polymer gel dosimeters  

International Nuclear Information System (INIS)

The effect of polymer gel dosimeter composition, temperature and ultrasonic signal frequency on ultrasonic dose response was investigated. Ultrasonic attenuation and speed were measured in PAG and MAGIC polymer gel dosimeters to assess the effect of dosimeter composition on dose response. Ultrasonic attenuation and speed were also determined in PAGs for a range of temperatures (10-25 deg C) and the ultrasonic attenuation coefficient was measured for three different ultrasonic frequencies (25.7, 46.3 and 66.2 MHz). Variations in dosimeter composition, temperature and ultrasonic frequency were found to alter the dynamic range and dose sensitivity of ultrasonic dose response curves, as well as the absolute values of speed and attenuation. (author)

2003-12-01

308

Polymeric Gel Electrolytes for Electrochemical Capacitors  

Science.gov (United States)

Three kinds of the polymer matrix, poly(ethylene oxide)-grafted polymethacrylate (PEO-PMA), poly(vinyldene fluoride) (PVdF) and poly(vinyldene-co-hexafluoropripylene) (PVdF-HFP), were used for gel preparation. A proper amount of organic salts or acids were dissolved in the polymer matrix together with organic plasticizers, dimethylformamide (DMF) and/or poly-(efhylene glycol)-dimethylether (PEGDE), without water. Thin films of the polymeric gel were obtained by either direct polymerization of the mixed monomer solution or a thermal casting method. The composition of the polymer-electrolyte complex system is optimized to obtain good capacitor performances of the electrochemical capacitor (ECC) system.

Morita, Masayuki; Qiao, Jin-Li; Ohsumi, Naoki; Yoshimoto, Nobuko; Egashira, Minato

2006-06-01

309

Dynamics of colloidal glasses and gels.  

Science.gov (United States)

Many household and industrially important soft colloidal materials, such as pastes, concentrated suspensions and emulsions, foams, slurries, inks, and paints, are very viscous and do not flow over practical timescales until sufficient stress is applied. This behavior originates from restricted mobility of the constituents arrested in disordered structures of varying length scales, termed colloidal glasses and gels. Usually these materials are thermodynamically out of equilibrium, which induces a time-dependent evolution of the structure and the properties. This review presents an overview of the rheological behavior of this class of materials. We discuss the experimental observations and theoretical developments regarding the microstructure of these materials, emphasizing the complex coupling between the deformation field and nonequilibrium structures in colloidal glasses and gels, which leads to a rich array of rheological behaviors with profound implications for various industrial processes and products. PMID:24655137

Joshi, Yogesh M

2014-01-01

310

Schiff base mediated sol-gel polymerization  

Energy Technology Data Exchange (ETDEWEB)

Formation of a Schiff base imine by reacting a primary amine with either an aldehyde or ketone was initiated by an aluminum compound acting as a Lewis acid catalyst. The water byproduct of the reaction then was used as an in situ reagent for subsequent hydrolysis and sol-gel condensation of the aluminum species. These reactions yielded a gel network containing the entrained Schiff base. Two examples of this synthetic approach are described with two different aluminum catalyst/reagents: a diethylaluminum diethylphosphate ester [(CH{sub 3}CH{sub 2}){sub 2}Al-O-P(O)(OCH{sub 2}CH{sub 3}){sub 2}] and triethyl aluminum [Al(CH{sub 3}CH{sub 2}){sub 3}]. Anhydrous ammonia and acetone were used as the Schiff base precursors.

Lindquist, D.A.; Harrison, C.M.; Williams, B.; Morris, R.D. [Univ. of Arkansas, Little Rock, AR (United States). Dept. of Chemistry

1996-12-31

311

Ceramica sphere production by a gel casting  

International Nuclear Information System (INIS)

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 ?mm) 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)

1987-05-17

312

Sol-gel preparation of ceramic fuel  

International Nuclear Information System (INIS)

The principle is described of a method based on the homogeneous hydrolysis of a uranyl nitrate solution in the presence of urea and urotropin. The procedure is given and the equipment described for the production of particles having 0.5 to 4.0 mm in dia. The gelation column (capacity 1.5 kg of gel U/hour) consists of a glass tube 50 mm in dia and 2,000 mm in length through which ascends hot oil. The finished gel is washed in ammonia water, dried, calcinated and reduced in a N2+6%H2 atmosphere. Sintering of the undamaged microspheres is carried out at temperatures between 1,200 to 1,500 degC. (M.K.)

1975-06-12

313

Novel carboxy functionalized sol-gel precursors  

Energy Technology Data Exchange (ETDEWEB)

A novel family of inorganic-organic copolymers (ORMOCER`s) derived from urethane- and thioether(meth)acrylate alkoxysilanes has been successfully exploited for a variety of diverse applications. In order to widen the range of applications an additional functionality (carboxy group) has been incorporated int his silane type. Conventional sol-gel processing facilitates the formation of an inorganic Si-O-Si-network via hydrolysis and polycondensation reactions of alkoxysilyl moieties and in addition, the (meth)acrylate groups are available for radically induced polymerization to obtain a complementary organic polymer structure. The presence of a carboxy group would appear to have great potential for a range of diverse areas of application, such as an internal catalyst for the sol-gel process, complexation of elements such as Zr and Ti, increasing the adhesion to various substrates and modification of solubility. A number of novel silanes and their syntheses will be described in this paper.

Wolter, H.; Storch, W.; Gellermann, C. [Fraunhofer-Inst. fuer Silicatforschung, Wuerzburg (Germany)

1996-12-31

314

Instabilities in droplets spreading on gels  

CERN Document Server

The surface-tension driven spreading of liquids is industrially and biologically important, and has been studied in detail on both solid and liquid substrates. Less is known about how droplet spreading is modified in the presence of a compliant substrate, a situation especially relevant to biological applications. We perform droplet-spreading experiments on gel agar, a viscoelastic material, to explore the influence of substrate on the spreading dynamics of the droplet. We find a novel branching instability with an onset that is controlled by the ratio of surface tension difference to the shear strength of the gel. The existence of a spreading morphology in which a spreading droplet becomes spatially localized has important implications for the industrial and medical application ofsurfactants.

Daniels, K E; Behringer, R P; Daniels, Karen E.; Mukhopadhyay, Shomeek; Behringer, Robert P.

2006-01-01

315

Local mobility and topology in gels  

International Nuclear Information System (INIS)

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.)

1981-01-01

316

Surface tension-induced gel fracture. Part 1. Fracture of agar gels.  

Science.gov (United States)

This work involves an experimental investigation of the spreading of liquids on gel layers in the presence of surfactants. Of primary interest is the instability that accompanies the cracking of gels through the deposition and subsequent spreading of a drop of surfactant solution on their surfaces. This instability manifests itself via the shaping of crack-like spreading "arms", in formations that resemble starbursts. The main aim of this study is to elucidate the complex interactions between spreading surfactants and underlying gels and to achieve a fundamental understanding of the mechanism behind the observed phenomenon of the cracking pattern formation. By spreading SDS and Silwet L-77 surfactant solutions on the surfaces of agar gels, the different ways that system parameters such as the surfactant chemistry and concentration and the gel strength can affect the morphology and dynamics of the starburst patterns are explored. The crack propagation dynamics is fitted to a power law by measuring the temporal evolution of the length of the spreading arms that form each one of the observed patterns. The values of the exponent of the power law are within the predicted limits for Marangoni-driven spreading on thick layers. Therefore, Marangoni stresses, induced by surface tension gradients between the spreading surfactant and the underlying gel layer, are identified to be the main driving force behind these phenomena, whereas gravitational forces were also found to play an important role. A mechanism that involves the "unzipping" of the gel in a manner perpendicular to the direction of the largest surface tension gradient is proposed. This mechanism highlights the important role of the width of the arms in the process; it is demonstrated that a cracking pattern is formed only within the experimental conditions that allow S/?w to be greater than G', where S is the spreading coefficient, ?w is the change in the width of the crack, and G' is the storage modulus of the substrate. PMID:22512657

Spandagos, Constantinos; Goudoulas, Thomas B; Luckham, Paul F; Matar, Omar K

2012-05-01

317

Films by sol-gel processes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The sol-gel process is a method for the preparation of inorganic materials and organically modified ceramics by "soft" chemistry. The possibility of adjusting the rheology of intermediates leads to products for coating procedures. As coating techniques dip, spin-on, spray, roll, and others are possible. Different applications for glasses are possible: to improve the surface properties of glass (e.g. strength) and to generate special effects or functions (optical, chemical reactivity, sensitiv...

Schmidt, Helmut K.

1988-01-01

318

GEL, a DNA sequencing project management system.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have developed an automated system for management of DNA sequencing projects. The system, named GEL, can handle data from both random sequences and from fragments whose relative positions are known. The system is highly interactive, self-documenting, and forgiving; it is designed for use by computer-naive molecular biologists. An editor designed specifically for sequences allows simple entry of data. Special functions allow direct checking and immediate editing of paired readings of the sa...

Clayton, J.; Kedes, L.

1982-01-01

319

'Laterally aggregated' polyacrylamide gels for electrophoresis.  

Science.gov (United States)

A new method is described for producing highly porous polyacrylamide matrices: polymerization in presence of a preformed hydrophilic polymer. If a standard mixture of monomers (e.g., 5%T, 4%C) is polymerized in presence of, e.g., polyethylene glycol (PEG) 10 kDa, lateral chain aggregation occurs, with formation of large pore sizes. In PEG 10 kDa, the transition from a small- to a large-pore gel is clearly apparent at 0.5% PEG addition and reaches a plateau already at 2.5% PEG. Even with shorter PEG fragments (6.2 and 1 kDa) this transition occurs, but with progressively larger amounts of PEG in solution (up to 25% for the 1 kDa species). Other polymers such as hydroxymethyl cellulose (1000 kDa) and polyvinyl-pyrrolidone (360 kDa and 25 kDa) are also able to elicit this phenomenon. It appears that lateral chain aggregation (before the cross-linking event) is induced via intra-chain hydrogen bonding, since urea and temperature strongly inhibit it, whereas tetramethylurea (an agent quenching hydrophobic interactions) does not hamper it. By scanning electron microscope, it is found that the maximum pore size obtained in a 5%T, 4%C gel in presence of 2.5% PEG 10 kDA is of the order of 0.5 micron, whereas the same 5%T, 4%C control gel would have an average pore diameter of 5 nm. Thus, an increment of pore size of about 2 orders of magnitude is obtained: in these new matrices, a 21000 bp DNA fragment exhibits a much greater migration than in a control gel in which the sample is entrapped at the application site. PMID:1459071

Righetti, P G; Caglio, S; Saracchi, M; Quaroni, S

1992-01-01

320

Biological macromolecules as gels: functional similarities.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Functional biological macromolecules arising from folding, cross-connection, and solvation of long-chain biopolymers forming three-dimensional networks can be compared to gels. Both involve identical internal competitive forces that are selectively influenced by external conditions and conspire to adjust conformations and modulate functions. In spite of important differences in size, chemical composition, polymer density, and configuration, biological macromolecules indeed manifest some of th...

Douzou, P.

1987-01-01

 
 
 
 
321

Sol-gel-derived lead titanate powders  

Energy Technology Data Exchange (ETDEWEB)

A review of the literature will be presented detailing the complexation chemistry of lead-titanium sol-gel solutions. On the basis of this chemistry, the rationale will be described for the preparation of homogeneous, doped and undoped lead titanate powders. Powders prepared by Silicon Technologies Australia Limited (STA) using this complexation rationale will be described. Appropriate selection of hydrolysis conditions and reagents enabled production of powders of appropriate size and shape for piezoelectric applications. 31 refs.

Watkins, I.D.; Tulloch, G.E.; Jenkins, S.M. [Silicon Technologies Australia Limited, NSW, (Australia)

1996-12-31

322

Sol-gel-derived lead titanate powders  

International Nuclear Information System (INIS)

A review of the literature will be presented detailing the complexation chemistry of lead-titanium sol-gel solutions. On the basis of this chemistry, the rationale will be described for the preparation of homogeneous, doped and undoped lead titanate powders. Powders prepared by Silicon Technologies Australia Limited (STA) using this complexation rationale will be described. Appropriate selection of hydrolysis conditions and reagents enabled production of powders of appropriate size and shape for piezoelectric applications

1996-01-01

323

Ring-Resonator/Sol-Gel Interferometric Immunosensor  

Science.gov (United States)

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.

Bearman, Gregory; Cohen, David

2007-01-01

324

Photoswitchable gel assembly based on molecular recognition  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The formation of effective and precise linkages in bottom-up or top-down processes is important for the development of self-assembled materials. Self-assembly through molecular recognition events is a powerful tool for producing functionalized materials. Photoresponsive molecular recognition systems can permit the creation of photoregulated self-assembled macroscopic objects. Here we demonstrate that macroscopic gel assembly can be highly regulated through photoisomerization of an azobenzene ...

Yamaguchi, Hiroyasu; Kobayashi, Yuichiro; Kobayashi, Ryosuke; Takashima, Yoshinori; Hashidzume, Akihito; Harada, Akira

2012-01-01

325

Gel-derived porous alumina systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Highly porous alumina systems were aimed to produce by a low energy-consuming sal-gel technique. Using the newly developed method based on a freeze drying technique, the expensive supercritical extraction can be avoided. Only two materials are needed for the synthesis: an inorganic Al salt and an organic solvent. Basic or chelating agents are not necessary to apply for gelation. The cryogels produced by freeze drying were compared with the aerogels obtained by the supercritical technique. The...

Sinko, Katalin

2013-01-01

326

Gel Evolution in Oil Based Drilling Fluids  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Drilling fluids make up an essential part of the drilling operation. Successful drilling operations rely on adequate drilling fluid quality. With the development of new drilling techniques such as long deviated sections and drilling in ultra-deep waters, the standard of required performance of the drilling fluids continue to increase. Narrow pressure margins and low tolerance for barite sag requires accurate prediction of the gel evolution in drilling fluids. Increased knowledge of how dri...

Sandvold, Ida

2012-01-01

327

Semiconductor Gel in Shark Sense Organs?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Sharks can sense bioelectric fields of prey and other animals in seawater using an extraordinary system of sense organs (ampullae of Lorenzini) [9]. A recent study reported that these sense organs also enable sharks to locate prey-rich thermal fronts using a novel mode of temperature reception without ion channels. The study reported that gel extracted from the organs operates as a thermoelectric semiconductor, generating electricity when it is heated or cooled [2]. Here we report biophysical...

Fields, R. Douglas; Fields, Kyle D.; Fields, Melanie C.

2007-01-01

328

The case of the floating gel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In patients with chronic renal failure, blood samples for laboratory analysis are often taken via dialysis catheters. This report describes a case of gross spurious hypernatraemia in a blood sample collected from a patient undergoing haemodialysis. After centrifugation of the blood sample in question, the separator gel formed the topmost layer, with the serum in the middle and the clot at the bottom. Subsequent analysis of the serum showed severe hypernatraemia (serum sodium, 744 mmol/litre)....

Srivastava, R.; Murphy, M. J.; Card, J.; Severn, A.; Fraser, C. G.

2004-01-01

329

Silver staining of 2D electrophoresis gels.  

Science.gov (United States)

Silver staining is used to detect proteins after electrophoretic separation on polyacrylamide gels. It -combines excellent sensitivity (in the low nanogram range) with the use of very simple and cheap equipment and chemicals. For its use in proteomics, two important additional features must be considered, compatibility with mass spectrometry and quantitative response. Both features are discussed in this chapter, and optimized silver staining protocols are proposed. PMID:22665294

Rabilloud, Thierry

2012-01-01

330

Silver Staining of 2D Electrophoresis Gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Silver staining is used to detect proteins after electrophoretic separation on polyacrylamide gels. It -combines excellent sensitivity (in the low nanogram range) with the use of very simple and cheap equipment and chemicals. For its use in proteomics, two important additional features must be considered, compatibility with mass spectrometry and quantitative response. Both features are discussed in this chapter, and optimized silver staining protocols are proposed.

Rabilloud, Thierry

2012-01-01

331

Adiabatic nucleation and crystallization of gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Adiabatic Nucleation Theory (ANT) has been successfully applied to pure liquid metals, oxide glasses, metallic glasses and polymers. This paper shows that ANT gives an interesting correlation between the crystallization data of gels of both reluctant and good (dense) glass forming systems. For reluctant glass formers, one finds that Tch T14-. T-14 is the temperature predicted by ANT at which nucleation starts in cooling experiment...

Meyer, Erich; Zanotto, Edgar D.; Aegerter, Michel A.

1990-01-01

332

Scattering from deformed swollen gels with heterogeneities  

Digital Repository Infrastructure Vision for European Research (DRIVER)

When elastic materials are anisotropically deformed, heterogeneities in stiffness generally produce long-range density variations. The effect is particularly enhanced in swollen gels. We calculate the structure factor from such frozen denstiy deviations under general affine deformations. It is maximized in the most stretched direction, whereas that from the thermal fluctuatins is minimized in the same direction. As a result, under uniaxial extension, a crossover occurs from normal to abnormal...

Onuki, Akira

1992-01-01

333

Impact of Corynebacterium pseudotuberculosis infection on serologic surveillance for Johne's disease in goats.  

Science.gov (United States)

False-positive results on serologic assays for Mycobacterium avium subsp. paratuberculosis (MAP) are believed to occur due to cross-reacting antibody produced by Corynebacterium pseudotuberculosis (C. pstb) infection in goats. This issue of compromised specificity was evaluated by testing 771 adult goats from 10 Midwestern goat herds in 2004. Assays for MAP infection included radiometric fecal culture and 2 enzyme-linked immunosorbent assays (ELISAs); ELISA-positive samples were tested by agar gel immunodiffusion (AGID). A synergistic hemolysin inhibition assay (SHI) was used to detect C. pstb antibody. Four infection status categories were evaluated. Category 1 goats (free of both MAP and C. pstb infection) tested negative on all MAP fecal cultures and SHI tests. Five of 181 goats were positive in both ELISAs, and 2 more were positive in ELISA-1 only. For Category 2 (MAP infected; no C. pstb infection), all animals were SHI negative. Six goats were fecal culture positive and strongly positive in both ELISAs; 2 more goats were positive only in ELISA-1. For Category 3 (C. pstb infected or vaccinated; no history of MAP infection), all fecal cultures were negative and 91% were SHI test-positive. In this population, only 2 goats were positive in both MAP ELISAs, while 84 additional goats were test-positive only on ELISA-1. In the absence of C. pstb infection, both ELISAs performed comparably, but when C. pstb infection was present the performance of ELISA-1 was significantly perturbed. Use of the ELISA-2 for goats is an effective and efficient method for Johne's disease surveillance in any goat herd. PMID:17402615

Manning, Elizabeth J B; Cushing, Heather F; Hietala, Sharon; Wolf, Cynthia B

2007-03-01

334

Serological Evaluation of Brucella abortus S99 Lipopolysaccharide Extracted by an Optimized Method  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: Brucellosis is a globally found infectious disease and there is no licensed vaccine against human brucellosis. The present study carried-out to evaluate the potency of our modified extracted lipopolysaccharide (LPS of B. abortus to elicit specific anti-Brucella antibodies in animal model (Rabbit as a part of a candidate vaccine for brucellosis. Lipopolysaccharide is one of the main virulence factors and the most immunogenic structure of smooth strains of Brucella. Approach: Lipopolysaccharide of B. abortus S99 (S-LPS initially extracted through an optimized method as described previously. After biochemical and pyrogenicity evaluations of the extracted S-LPS humoral immune response against the extracted LPS analyzed in animal model through serological assays such as Rose Bengal assay, Rapid agglutination (Rapid Wright test and Standard agglutination test (SAT or Wright test to demonstrate the specific elicited antibodies against the injected LPS. In addition, the interaction of LPS and anti-LPS antibodies was demonstrated by Agarose Gel Immunodiffusion (AGID assay. Results: Higher doses of B. abortus S99 LPS caused less or equal body temperature increase in comparison to E. coli LPS doses. Sera of immunized animals had been reported positive by RBT because of B. abortus LPS immunogenicity which we extracted through our optimized method. The highest titer of anti-Brucella antibodies detected two weeks after the third immunization (assayed by rapid slide agglutination and standard agglutination tests. Anti-Brucella antibodies of immunized animals reacted more specifically with the LPS of B. abortus in comparison with E. coli LPS and precipitation lines between B. abortus LPS and immune sera appeared after 30 min while detected after three hours for E. coli LPS. Conclusions/Recommendations: The properties of B. abortus S99 LPS concluded from the present study results, suggest the possible use of this component as a carrier or a part of a sub-unit or conjugated vaccine for human brucellosis.

Ali S. Salmani

2009-01-01

335

Para tuberculosis (Johnes disease: Basic characteristics and current situation locally  

Directory of Open Access Journals (Sweden)

Full Text Available Para tuberculosis or Johne's Disease, is a disease of the digestive tract of animals caused by Mycobacterium avium subspecies Para tuberculosis (M. a. Para tuberculosis. Para tuberculosis has been registered in many countries and it today presents one of the most widely-spread bacterial diseases in ruminants that causes severe economic damages. In our country, Para tuberculosis has not been studied extensively. The disease was registered for the first time in Serbia in 1995 in an isolated herd of sheep of the II-de-France breed, and serologically positive cattle were determined in 2001. Infection with M.a. Para tuberculosis occurs mostly in young animals which are the most sensitive to infection. The main source of infection is the feces of diseased animals. Furthermore, colostrums and milk of diseased animals can contain micro bacteria, and there is a possibility also of intra-uterine infection. A long period of incubation, a chronic course, and not always clear clinical picture render diagnosis of Para tuberculosis very complex, in spite of the existence of numerous diagnostic methods. There are a number of serological tests with which it is possible to detect antibodies against M.a. Para tuberculosis in infected animals. The most frequently used are complement binding reaction (CBR, the agar gel immunodiffusion test (AGID, and the immunioenzyme test (ELISA. The isolation of causes or parts of their genome, present important methods in the diagnosis of Para tuberculosis. Pieces of tissue obtained through autopsies or biopsies, feces or milk samples, can serve as material for isolation. A diagnosis of Para tuberculosis for dead or sacrificed animals is made on the grounds of path anatomical or path histological findings. Para tuberculosis of ruminants has certain similarities with Crohn's Disease in humans, from the clinical, morphological, and etiological aspects.

Jovanovi? Milijan

2005-01-01

336

Textural attributes of mixed whey proteins and carrageenan gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The sensory and rheological textural characteristics of heat induced and cold-set mixed whey proteins (WP) – carrageenan (CAR) gels were investigated. Mixed gels containing from 3.0 to 6.0 % WP and from 1.0 to 2.0 % of dry CAR were made. Sensory and instrumental texture characteristics of mixed gels were determined. A list of 15 sensory visual and in-hand attributes of the gels was formed. Panelists perceived textural differences in gels more sensitive by fingers in comparison with those ob...

Leskauskaite?, D.; Kriu?kova, I.; Brantas, A.; Miez?eliene?, A.; Alenc?ikiene?, G.

2005-01-01

337

Equipment for production of hydrogel by sol-gel method  

International Nuclear Information System (INIS)

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)

1975-01-01

338

Sol-gel processing of metal-oxide-semiconductor structures  

Energy Technology Data Exchange (ETDEWEB)

We have investigated the electronic properties of sol-gel derived films on silicon substrates. Our investigation involves SiO/sub 2/, aluminosilicate and borosilicate oxides on silicon. Some sol-gel oxides are excellent insulators; some sol-gel films on silicon also exhibit quite low oxidesilicon interface state densities. We have also subjected sol-gel films on silicon to 4 MRAD of radiation and have found that these structures appear to be radiation hard (very little oxide space charge or interface state generation). Our results strongly suggest that sol-gel processing could provide insulating films for a variety of microelectronic device applications. 21 refs., 6 figs., 2 tabs.

Warren, W.L.; Lenahan, P.M.; Brinker, C.J.

1988-01-01

339

Research software for radiotherapy gel dosimetry.  

Science.gov (United States)

Gel dosimetry using magnetic resonance imaging is a technique which allows measurement of three-dimensional absorbed dose distributions in radiation therapy. This paper presents details of a software tool written specifically to provide facilities to perform image processing required in research and development of gel dosimetry. Collections of magnetic resonance images can be converted into either longitudinal or transverse nuclear magnetic resonance relaxation images. The conversions are accomplished by means of a pixel-by-pixel non-linear least squares fitting algorithm. Adjustments can be made to the number of parameters used in the fitting algorithm. Fundamental image manipulation tools such as window width/level display adjustment, zooming, profile and region of interest tools are provided. The software has been developed using MATLAB (The MathWorks Inc., Natick, MA) running on Windows 95. User interaction is via a windows graphical user interface (GUI). Data such as statistics from regions of interest can be exported to other windows applications for further processing. Flexibility is incorporated in the GUI design by taking advantage of the developmental aspects of the MATLAB environment. Although originally designed for gel dosimetry, the software can be used in any application of MRI which requires production and manipulation of relaxation time images. PMID:10979593

Murry, P; Baldock, C

2000-06-01

340

Research software for radiotherapy gel dosimetry  

International Nuclear Information System (INIS)

Gel dosimetry using magnetic resonance imaging is a technique which allows measurement of three-dimensional absorbed dose distributions in radiation therapy. This paper presents details of a software tool written specifically to provide facilities to perform image processing required in research and development of gel dosimetry. Collections of magnetic resonance images can be converted into either longitudinal or transverse nuclear magnetic resonance relaxation images. The conversions are accomplished by means of a pixel-by-pixel non-linear least squares fitting algorithm. Adjustments can be made to the number of parameters used in the fitting algorithm. Fundamental image manipulation tools such as window width / level display adjustment zooming, profile and region of interest tools are provided. The software has been developed using MATLAB (The MathWorks Inc., Natick, MA) running on Windows 95. User interaction is via a windows graphical user interface (GUI). Data such as statistics from regions of interest can be exported to other windows applications for further processing. Flexibility is incorporated in the GUI design by taking advantage of the developmental aspects of the MATLAB environment. Although originally designed for gel dosimetry, the software can be used in any application of MRI which requires production and manipulation of relaxation time images

2000-06-01

 
 
 
 
341

Decontamination using chemical gels, electrolytical swab, abrasives  

International Nuclear Information System (INIS)

Decontamination for decommissioning purposes differs from usual in-service decontamination procedures. The main factors which have to be considered in setting up decontamination procedures for nuclear installation decommissioning are: rapidity and ease of application, efficiency of decontamination, possibility of remote operation and small quantities of secondary generated wastes. The aim of this research work is to develop three decontamination methods which appear to be well adapted to dismantling. After laboratory tests where several procedures are compared, actual nuclear installation dismantling operations were performed. Among the decontamination procedures developed by CEA Cadarache, the following have been the subject of extensive studies: spraying of gels containing decontaminating agents, electropolishing with swab device and abrasive blasting. Examples of industrial applications of these three techniques which have been carried out are for these procedures: gels spraying performed on pieces coming from German BW Reactor ISAR, Brennilis Bitumization plant decontamination and dismantling, gels spraying decontamination performed on the cooling circuit of the graphite gas reactor G2 and a mechanical sodium cleaning method by abrasive blasting on SuperPhenix fuel storage drum intervessel. For each of these in-situ decontamination operations, a balance has to be made between the quantity of decontaminated metallic wastes and the amount of chemical reagent used as well as the quantity of secondary wastes generated. (author)

1990-01-01

342

Correlations predict friction pressures of fracturing gels  

Energy Technology Data Exchange (ETDEWEB)

Friction pressure calculations are very important in the design of any hydraulic fracturing treatment. They are useful in determining horsepower requirements, bottomhole treating pressure, and maximum wellhead pressure. This article presents a classical approach in which flow data of various gels in multiple pipes are presented as two dimensionless quantities, Fanning friction factor and generalized Reynolds number. These dimensionless quantities are then correlated as a function of power-law flow behavior index n'. Fluids with a wide range of generalized Reynolds number (N' /SUB Re/ = 2 X 10/sup 3/ to 5 X 10/sup 5/) and flow behavior index n' = 0.272 to 1.0) have been investigated. The correlations can be used to estimate friction pressures of both uncrosslinked and crosslinked gels. A method predicting friction pressures based on these correlations has already been implemented on a field transportable rheology system and good success has been reported. The friction pressures estimated from these correlations have been compared favorably with field data from several fracturing treatments. Effect of pipe roughness pressure of gelled fluid has also been examined. This testing indicates that pipe roughness does not affect pressure at high gel concentration. This contradicts previous thinking.

Shah, S.N.

1984-01-01

343

Pulsed-field gel electrophoresis of MRSA.  

Science.gov (United States)

Pulsed-field gel electrophoresis (PFGE) is a genetic typing method that is widely used as a molecular epidemiological tool for studying the genetic diversity of Staphylococcus aureus and numerous other bacterial pathogens. For PFGE, intact bacterial cells are embedded in soft agarose plugs followed by lysis of the cell wall in situ to minimize shearing of the chromosome. The genome, which for S. aureus is approx 2.8 Mb, is then digested with a rare cutting restriction endonuclease and separated by agarose gel electrophoresis. The restriction fragments generated are too large to be resolved by conventional electrophoresis. Therefore, resolution of the bands is achieved in a "contour-clamped homogeneous electrical field" where electrical current to the gel switches direction between multiple electrodes over a period of time. Initially, current switches are short (pulsed) but become longer (ramped) as electrophoresis continues. Banding patterns are captured by an imaging system and comparisons are made based on the Dice coefficient and the unweighted pair group method using arithmetic averages with BioNumerics software. PMID:18025669

Reed, Kurt D; Stemper, Mary E; Shukla, Sanjay K

2007-01-01

344

Fabrication, modeling and optimization of an ionic polymer gel actuator  

International Nuclear Information System (INIS)

The modeling of the electro-active behavior of ionic polymer gel is studied and the optimum conditions that maximize the deflection of the gel are investigated. The bending deformation of polymer gel under an electric field is formulated by using chemo-electro-mechanical parameters. In the modeling, swelling and shrinking phenomena due to the differences in ion concentration at the boundary between the gel and solution are considered prior to the application of an electric field, and then bending actuation is applied. As the driving force of swelling, shrinking and bending deformation, differential osmotic pressure at the boundary of the gel and solution is considered. From this behavior, the strain or deflection of the gel is calculated. To find the optimum design parameter settings (electric voltage, thickness of gel, concentration of polyion in the gel, ion concentration in the solution, and degree of cross-linking in the gel) for bending deformation, a nonlinear constrained optimization model is formulated. In the optimization model, a bending deflection equation of the gel is used as an objective function, and a range of decision variables and their relationships are used as constraint equations. Also, actuation experiments are conducted using poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) gel and the optimum conditions predicted by the proposed model have been verified by the experiments

2011-04-01

345

Electrochemical performance of nonflammable polymeric gel electrolyte containing triethylphosphate  

Energy Technology Data Exchange (ETDEWEB)

Nonflammable polymeric gel electrolyte has been prepared by immobilizing 1 M LiBF{sub 4}/EC + DEC + TEP (55:25:20, v/v/v, EC: ethylene carbonate, DEC: diethyl carbonate and TEP: triethylphosphate) solution in poly(vinylidene fluoride-co-hexafluoro propylene) (PVdF-HFP) where TEP acts as a fire-retardant solvent in the gel electrolyte. The polymeric gel electrolyte has a high value of ionic conductivity of 1.76 mS cm{sup -1} at 28 C. Thermal safety calorimetry (TSC) experiments show good thermal stability of the gel electrolyte. Cyclic voltammetry and charge/discharge cycling tests were performed on LiMn{sub 2}O{sub 4}/gel electrolyte and graphite/gel electrolyte half cells. The gel electrolyte works well for graphite/LiMn{sub 2}O{sub 4} cell although some improvement in the cycleability of the graphite electrode is still needed. (author)

Lalia, Boor Singh; Fujita, Takayoshi; Yoshimoto, Nobuko; Egashira, Minato; Morita, Masayuki [Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611 (Japan)

2009-01-01

346

Transfer printing of thermoreversible ion gels for flexible electronics.  

Science.gov (United States)

Thermally assisted transfer printing was employed to pattern thin films of high capacitance ion gels on polyimide, poly(ethylene terephthalate), and SiO2 substrates. The ion gels consisted of 20 wt?% block copolymer poly(styrene-b-ethylene oxide-b-styrene and 80 wt?% ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)amide. Patterning resolution was on the order of 10 ?m. Importantly, ion gels containing the block polymer with short PS end blocks (3.4 kg/mol) could be transfer-printed because of thermoreversible gelation that enabled intimate gel-substrate contact at 100 °C, while gels with long PS blocks (11 kg/mol) were not printable at the same temperature due to poor wetting contact between the gel and substrates. By using printed ion gels as high-capacitance gate insulators, electrolyte-gated thin-film transistors were fabricated that operated at low voltages (film devices. PMID:24028461

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

2013-10-01

347

Direct from polyacrylamide gel infrared laser desorption/ionization.  

Science.gov (United States)

The direct combination of gel electrophoresis and infrared laser desorption/ionization time-of-flight mass spectrometry has been demonstrated. We present results for infrared laser desorption and ionization mass spectrometry of peptides and proteins directly from a polyacrylamide gel without the addition of a matrix. Analyte molecules up to 6 kDa were ionized directly from a vacuum-dried sodium dodecyl sulfate-polyacrylamide gel after electrophoretic separation. Mass spectra were obtained at the wavelength of 2.94 microm, which is consistent with IR absorption by N-H and O-H stretch vibrations of water and other constituents of the gel. A 5-nmol quantity of peptide or protein was loaded per gel slot, although it was possible to obtain mass spectra from a small fraction of the gel spot. This technique shows promise for the direct identification of both parent and fragment masses of proteins contained in polyacrylamide gels. PMID:14961741

Xu, Yichuan; Little, Mark W; Rousell, David J; Laboy, Jorge L; Murray, Kermit K

2004-02-15

348

Formation of magnetite nanoparticles in poly(acrylamide) gels  

International Nuclear Information System (INIS)

Magnetic gels with magnetite nanoparticles incorporated in a matrix of poly(acrylamide) gel were studied. Magnetite was synthesized through coprecipitation of Fe(II) and Fe(III) in the gel phase, in the solution of linear polymer and in aqueous solution without polymer in alkaline media. The effects of network structure and of the concentration of iron salts in the swollen networks on the composition, structure and properties of magnetic gels have been studied by electron diffraction, XRD, transmission electron microscopy and vibration sample magnetometry. The average size of magnetite nanoparticles, D, is of the order of 10 nm. It decreases with the increase of polymer concentration in the gel phase. In the dried gels the particles form spherical aggregates (diameter about 150 nm), whereas in the solution of linear polymer, in the aqueous solution of iron salts and in the gel with high content of polymer the aggregates have irregular shape

2005-03-16

349

Fouling mechanisms of gel layer in a submerged membrane bioreactor.  

Science.gov (United States)

The fouling mechanisms underlying gel layer formation and its filtration resistance in a submerged membrane bioreactor (MBR) were investigated. It was found that gel layer rather than cake layer was more easily formed when soluble microbial products content in sludge suspension was relatively high. Thermodynamic analyses showed that gel layer formation process should overcome a higher energy barrier as compared with cake layer formation process. However, when separation distance <2.3nm, attractive interaction energy of gelling foulant-membrane combination was remarkably higher than that of sludge floc-membrane combination. The combined effects were responsible for gel layer formation. Filtration tests showed that specific filtration resistance (SFR) of gel layer was almost 100 times higher than that of cake layer. The unusually high SFR of gel layer could be ascribed to the gelling propensity and osmotic pressure mechanism. These findings shed significant light on fouling mechanisms of gel layer in MBRs. PMID:24926602

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

2014-08-01

350

G-Quadruplex Guanosine Gels and Single Walled Carbon Nanotubes  

Directory of Open Access Journals (Sweden)

Full Text Available Solubilization of single walled carbon nanotubes (SWNTs in aqueous gel phases formed by reversible, G-quadruplex self-assembly of guanosine monophosphate (GMP alone or with guanosine (Guo is described. Unlike other media and methods for aqueous solubilization of SWNTs, the guanosine gels (“G-gels” are found to readily disperse high (>mg/mL concentrations of individual rather than bundled SWNTs. SWNT dispersions in GMP alone precipitate in several hours and re-form upon shaking; however, dispersions in the binary GMP/Guo gels are indefinitely stable. Increasing GMP or KCl concentration in the binary gels increased the relative abundance of large diameter and semi-conducting SWNTs. Different gel compositions also displayed different selectivities toward SWNTs of different chiralities. These results indicate a strong connection between the self-assembled G-gels and the dimensions and structures of the SWNTs that they solubilize.

Yuehua Yu

2013-12-01

351

Colloid molecular weight estimation by gel chromatography/acrylamide gel electrophoresis  

International Nuclear Information System (INIS)

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 (m?AA) 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-m?AA 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-m?AA, 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-m?AA, 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-m?AA, 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-m?AA migrated farther into the separating gel; while pH 8.5 Tc-99m-m?AA 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

1984-06-05

352

Direct Force Measurements on Neurofilaments: Gel Expanded to Gel Condensed Transition  

Science.gov (United States)

Neurofilaments (NFs)--the major cytoskeletal constituent of axons in vertebrates, consist of three subunit proteins assembled to form filaments with protruding unstructured C-terminus sidearms. Liquid crystal gel networks of sidearm-mediated NF assemblies play a key role in the mechanical while disruptions of this network, due to over-accumulation or incorrect sidearm interactions, are a hallmark of motor neuron diseases. Using synchrotron SAXS [1,2] and microscopy techniques [1,3] we report a direct force measurement of reconstituted NF-gels under osmotic pressure (P), which revealed the role of subunit sidearms on structure and interaction of NFs. With increasing P, near physiological condition, the gels undergo an abrupt nonreversible gel expanded to gel condensed transition that indicates sidearm-mediated attractions between NFs. This attraction is consistent with an electrostatic model of interpenetrating chains.[4pt] [1] J.B. Jones, C.R. Safinya, Biophys. J. 95, 823 (2008);[0pt] [2] R. Beck et al., Nature Mat. (2009) in press;[0pt] [3] H. Hess et al. Langmuir 24, 8397 (2008)

Beck, R.; Deek, J.; Jones, J. B.; Safinya, C. R.

2010-03-01

353

Evaluation of the pharmacokinetic profiles of the new testosterone topical gel formulation, Testim, compared to AndroGel.  

Science.gov (United States)

A two-period, randomized, complete crossover study was performed to evaluate the pharmacokinetic profiles of Testim (AA2500), a new 1% testosterone topical gel formulation, compared to AndroGel, an already available 1% testosterone topical gel. Twenty-nine hypogonadal subjects received a single dose (50 mg testosterone) of each formulation seven days apart. C(max) estimates for total testosterone, dihydrotestosterone and free testosterone were greater (30, 19 and 38%, respectively) following the application of Testim compared to AndroGel. Similarly, AUC(0-24) estimates for total testosterone, dihydrotestosterone, and free testosterone were greater (30, 11 and 47%, respectively) following the application of Testim compared to AndroGel. Confidence intervals for C(max) and AUC(0-24) were not wholly contained within the bioequivalence limits for testosterone, therefore Testim trade mark and AndroGel are not bioequivalent with Testim providing higher serum levels and greater bioavailability than AndroGel. PMID:12673669

Marbury, T; Hamill, E; Bachand, R; Sebree, T; Smith, T

2003-04-01

354

Photosensitive YBCO gel film and its patterning by sol-gel process  

Energy Technology Data Exchange (ETDEWEB)

Acrylic acid (AA) as chemical modifier. The AA-modified YBCO gel film exhibits the photosensitivity to UV-light. The patterned YBCO film was fabricated by chemically modified sol-gel method. The YBCO precursor solution was prepared using yttrium acetate, barium acetate and copper acetate as starting material, diethylenetriamine, trifluoroacetate, acrylic acid (AA) as chemical additives, methanol as solvent. The precursor solution was modified by AA, in which the Cu{sup 2+} of Cu(OAc){sub 2} and AA were reacted to form the photosensitive copper complex. The coated gel film using this precursor solution exhibited the photosensitivity to UV light at around 245 nm. Utilizing the photosensitivity, the patterned YBCO film with a high critical transition temperature (Tc) of 91.5 K was fabricated.

Zhang Huangli, E-mail: hl_zhang@126.com [School of Science, Xi' an University of Posts and Telecommunications, Xi' an 710121 (China); Zhao Gaoyang [School of Material Science and Engineering, Xi' an University of Technology, Xi' an 710048 (China)

2012-01-15

355

Photosensitive YBCO gel film and its patterning by sol-gel process  

International Nuclear Information System (INIS)

Acrylic acid (AA) as chemical modifier. The AA-modified YBCO gel film exhibits the photosensitivity to UV-light. The patterned YBCO film was fabricated by chemically modified sol-gel method. The YBCO precursor solution was prepared using yttrium acetate, barium acetate and copper acetate as starting material, diethylenetriamine, trifluoroacetate, acrylic acid (AA) as chemical additives, methanol as solvent. The precursor solution was modified by AA, in which the Cu2+ of Cu(OAc)2 and AA were reacted to form the photosensitive copper complex. The coated gel film using this precursor solution exhibited the photosensitivity to UV light at around 245 nm. Utilizing the photosensitivity, the patterned YBCO film with a high critical transition temperature (Tc) of 91.5 K was fabricated.

2012-01-01

356

Investigation of the Peroxovanadate Sol-Gel Process and Characterization of the Gels  

Energy Technology Data Exchange (ETDEWEB)

In general, the peroxovanadate solution sol-gel process can be thought of as consisting of two parts: (1) the decomposition of the peroxo species and (2) cation hydrolysis leading to gelation. By controlling the synthesis conditions, both layered and amorphous compounds can be created. However, the type of water coordination observed in these gels was found to be identical no matter what the long-range order. The current work clarified many of the discrepancies found in the literature and offered much new valuable information. Highlights include the types of vanadium environments present at various stages of hydration, the role of adsorbed water, oxygen exchange from adsorbed water into the gel sites, and the ability to create metastable VMoO solid solution phases. These results could have a variety of impacts on future catalysis research.

Craig Joseph Fontenot

2001-12-31

357

Dosimetry in HDR brachytherapy with Fricke-gel layers and Fricke-gel catheters  

Energy Technology Data Exchange (ETDEWEB)

Fricke-gel layer dosimeters (FGLD) and Fricke gel dosimetric catheters (FGDC) have been designed and tested with the aim of enquiring their suitability for HDR {sup 192}Ir brachytherapy source control and for in-vivo dose verification during treatment. Anisotropy function measurements have been carried out with FGLDs in which a thin plastic tube has been placed in for the {sup 192}Ir source insertion. FGDCs are constituted by plastic tubes (3 mm of external diameter and 13 cm of length) filled with the dosimeter-gel. Absorbed dose images and profiles were attained by means of optical analysis. Dedicated software has been developed both for achieving anisotropy function values and for obtaining reliable results in visible light absorbance measurements across the thin cylindrical dosimeters. Preparation and analysis procedures have been optimised. The results confirm that the proposed methods are very promising for HDR brachytherapy dosimetry.

Gambarini, G; Carrara, M; Negri, A; Invernizzi, M; Tenconi, C; Scotti, A; Pirola, L; Borroni, M; Tomatis, S; Fallai, C, E-mail: grazia.gambarini@mi.infn.i

2010-11-01

358

Sol-gel synthesis of hydroxyapatite; Sintese de hidroxiapatita via sol-gel  

Energy Technology Data Exchange (ETDEWEB)

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)

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

359

Low pH induces an interdigitated gel to bilayer gel phase transition in dihexadecylphosphatidylcholine membrane.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have investigated the influence of pH on the structures and phase behaviors of multilamellar vesicles of the ether-linked dihexadecylphosphatidylcholine (DHPC-MLV). This phospholipid is known to be in the interdigitated gel (L(beta)I) phase in excess water at 20 degrees C at neutral pH. The results of X-ray diffraction experiments indicate that a phase transition from L(beta)I phase to the bilayer gel phase occurred in DHPC-MLV in 0.5 M KCl around pH 3.9 with a decrease in pH, and that at ...

1999-01-01

360

Thoria-urania gel characterisation for sol-gel microsphere pelletisation (SGMP)  

International Nuclear Information System (INIS)

Thorium is an important component of the nuclear power program. Fabrication of thorium-based fuels is associated with radiation exposure problems due to the presence of 232U. Sol-gel process which uses liquids or free flowing solids are amenable for automation and remote handling and hence ideally suited for manufacture of such fuel. Accordingly, the present investigation is aimed at development of a process flow sheet for obtaining dense ThO2 and (Th,U)O2 pellets via Sol Gel Microsphere Pelletisation (SGMP)

2004-01-01

 
 
 
 
361

Sol-gel process for thermal reactor fuel fabrication  

International Nuclear Information System (INIS)

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 233U. 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

2008-12-01

362

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)

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.

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

2002-01-01

363

Enzootic bovine Leukosis: development of an indirect enzyme linked immunosorbent assay (I-Elisa in seroepidemiological studies  

Directory of Open Access Journals (Sweden)

Full Text Available Bovine Leukemia Virus (BLV is the etiologic agent of Enzootic Bovine Leukosis, a retrovirus exogenous to the bovine species. Once infected, there is no detectable viraemia but instead there is a strong and persistent immunological response to BLV structural proteins, essentially the gp51 envelope glycoprotein and the mayor core protein p24. We describe the test procedure of an indirect ELISA (I-ELISA using polyclonal reagents for the detection of antibodies to BLV. For comparison, the sera were simultaneously tested by agar gel immunodiffussion (AGID test, which is currently used as diagnostic standard for BLV infection. The antigen applied does not require a high degree of purification and the data from the analysis of the negative sera showed that the establishment of a cut-off level corresponding to 3 times the standard deviation (SD above the mean for the negative control set of sera provided acceptable specificity, reducing the risk of false positives results. A comparison of the results obtained by AGID test and I-ELISA showed that considering a total of 465 serum samples, all of the 234 samples (50% that were positive by AGID were positive to the I-ELISA. Of 225 serum samples which yielded negative results in the AGID test, 69 (15% were found to be positive by the I-ELISA and 156 (33% were negative by both techniques. Few sera (2% that were non-specific by AGID were defined as negative or positive by I-ELISA.

González Ester Teresa

1999-01-01

364

Enhancement of ion dissociation in polyelectrolyte gels  

Energy Technology Data Exchange (ETDEWEB)

High conductivity in single ion conducting polymer electrolytes is still the ultimate aim for many electrochemical devices such as secondary lithium batteries. Achieving effective ion dissociation in these cases remains a challenge since the active ion tends to remain in close proximity to the backbone charge as a result of a low degree of ion dissociation. A unique aspect of this dissociation problem in polyelectrolytes is the repulsion between the backbone charges created by dissociation. One way of enhancing ion dissociation in polyelectrolyte systems is to use copolymers in which only a fraction (<20%) of the mer units are charged and where the comonomer is itself chosen to be polar and preferably to be compatible with potential solvents. We have also found that certain dissociation enhancers based on ionic liquids or boroxine ring compounds can lead to high ionic conductivity. In the cases where an ionic liquid is used as the solvent in a polyelectrolyte gel, the viscosity of the ionic liquid and its hydrophilicity are critical to achieving high conductivity. Compounds based on the dicyanamide anion appear to be very effective ionic solvents; polyelectrolyte gels incorporating such ionic liquids exhibit conductivities as high as 10{sup -2} S/cm at room temperature. In the case of boroxine ring dissociation enhancers, gels based on poly(lithium-2-acrylamido-2-methyl-1-propanesulfonate) and ethylene carbonate produce conductivities approaching 10{sup -3} S/cm. This paper will discuss these approaches for achieving higher conductivity in polyelectrolyte materials and suggest future directions to ensure single ion transport. (author)

Forsyth, M.; Sun, J. [Monash University, Clayton, Victoria (Australia). School of Physics and Materials Engineering; Zhou, F.; MacFarlane, D.R. [Monash University, Clayton, Victoria (Australia). School of Chemistry

2003-06-30

365

Dynamical heterogeneities: from glasses to gels  

Energy Technology Data Exchange (ETDEWEB)

One of the challenges in soft and condensed matter over the last few years has been understanding the phenomena of glass and jamming transitions. A recent advance in the field is the idea that the dynamical heterogeneities play here the same role as the critical fluctuations in ordinary critical phenomena. This is due to the fact that the decay of density fluctuations in glasses and jammed systems takes place thanks to the dynamically correlated motions of groups of particles. In this paper, after a brief review of the properties of the dynamical heterogeneities in glasses we analyze the cases of chemical and colloidal gels, which are still intensely debated.

Coniglio, A; Abete, T; De Candia, A [Dipartimento di Scienze Fisiche, Universita degli Studi di Napoli ' Federico II' , via Cinthia, I-80126 Napoli (Italy); Del Gado, E [ETH Zuerich, Department of Materials, Polymer Physics, CH-8093 Zuerich (Switzerland); Fierro, A [INFM-CNR Coherentia, Via Cinthia, I-80126 Napoli (Italy)

2008-12-10

366

Calibration of an alanine/agarose gel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In brachy therapy treatment, as well as in treatment with external beams, it is of crucial importance to thoroughly determine the absorbed dose in the tumour, in surrounding normal tissue and in risk organs. Several kinds of gel dosimeters have been, or are about to be, developed in order to get a three dimensional dosimeter, which would be very useful, especially in the context of brachy therapy. The need for high spatial resolution is raised by the fact that the absorbed dose decreases very...

1998-01-01

367

Industrial applications of sol-gel technology  

International Nuclear Information System (INIS)

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

1991-07-11

368

Higher Gel'fand-Dikii structures  

CERN Document Server

We apply the procedure of Magri and Weinstein to produce an infinity of compatible Poisson structures on a bihamiltonian manifold, to the case of the KdV phase space. The higher Gel'fand-Dikii structures thus obtained contain non local terms, which we express with the help of the r.h.s. of the KdV hierarchy. We also give a generating function for all these Poisson structues, in terms of the Baker-Akhiezer functions. Finally we describe the symplectic leaves of these Poisson structures.

Enriquez, B; Rubtsov, V N

1993-01-01

369

Repton model of gel electrophoresis and diffusion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We analyse the repton model of Rubinstein as adapted by Duke as a model for the gel electrophoresis of DNA. Parameters in the model are the number N of reptons in the chain, a length a, a microscopic transition frequency w, and the product eE of the electric field E (assumed constant) and the charge e per repton. Formally exact formulas are derived for the dimensionless diffusion coefficient D/a2w and drift velocity V/aw, the latter as a function of the field. Calculation of V/aw requires the...

Widom, B.; Viovy, J.; Defontaines, A.

1991-01-01

370

Sol-gel-coated products in Australia  

Energy Technology Data Exchange (ETDEWEB)

Australian research into various ceramic coatings prepared by the sol-gel process has led to the development of several products for which commercialisation is imminent. These coatings include indium tin oxide, doped lead titanate and lead zirconate titanate, titania, silica, mixed titania/silica, zirconia and partially stabilised zirconia. Products incorporating these coatings find application in glazing for scratch resistance, and architecturally for Low-E properties and as spectrally-selective filters. Other products include coated metals suitable for wear resistant applications such as dies. Sensors have also been produced based on piezoelectric, ferroelectric and pyroelectric properties. A selection of these products is discussed.

Watkins, I.D.; Tulloch, G. [Silicon Technologies Australia Limited, Queanbeyan (Australia)

1995-12-31

371

Length scale dependent relaxation in colloidal gels  

CERN Multimedia

We use molecular dynamics computer simulations to investigate the relaxation dynamics of a simple model for a colloidal gel at a low volume fraction. We find that due to the presence of the open spanning network this dynamics shows at low temperature a dependence on the wave-vector which is very different from the one observed in dense glass-forming liquids. In particular the time correlation functions show a cross-cover from a stretched exponential behavior for distances larger than the mesh size to a compressed exponential at smaller distance.

Gado, E D

2005-01-01

372

Sol-gel processing of ceramics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The sol-gel process can be considered as an interesting method for the synthesis of tailor-made ceramic raw materials. Two points of view are of special interest: powder synthesis and the processing of ultrafine raw materials. In the case of powder synthesis, high quality and multicomponent powders can be synthesized by control of surface chemistry and agglomerate-free subµm powder can be obtained. The preparation of tailor-made sols offers the possibility of powder-free processing of coatin...

Schmidt, Helmut K.

1991-01-01

373

Real Gel'fand-Mazur division algebras  

Directory of Open Access Journals (Sweden)

Full Text Available We show that the complexification (A˜,τ˜ of a real locally pseudoconvex (locally absorbingly pseudoconvex, locally multiplicatively pseudoconvex, and exponentially galbed algebra (A,τ is a complex locally pseudoconvex (resp., locally absorbingly pseudoconvex, locally multiplicatively pseudoconvex, and exponentially galbed algebra and all elements in the complexification (A˜,τ˜ of a commutative real exponentially galbed algebra (A,τ with bounded elements are bounded if the multiplication in (A,τ is jointly continuous. We give conditions for a commutative strictly real topological division algebra to be a commutative real Gel'fand-Mazur division algebra.

Olga Panova

2003-07-01

374

Sol-gel chromogenic materials and devices  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the last few years the sol-gel process has turned into an interesting and promising method of synthesizing materials for obtaining thin or thick films with definite functions. The techniques of film preparation such as dip and spin coating are simple and allow us to prepare coatings with smooth optical surfaces with controlled stoichiometry, structure and texture. In this paper we give an up to date overview of what has been achieved in the field of chromogenic materials such as anodic or ...

Aegerter, Michel A.

1996-01-01

375

Sol-gel coatings for electrochromic devices  

Digital Repository Infrastructure Vision for European Research (DRIVER)

All solid state electrochromic smart windows with the configuration glass/ITO/WO3/electrolyte/TiO2-CeO2/ITO/glass have been realized. These devices have potential applications in architectural and automotive fields to regulate the transmission and reflection of the radiant energy. The ion storage electrode TiO2-CeO2 have been realized by sol-gel process and its electrochemical properties are studied as a function of various parameters. The electrochemical and optical performance of two cells ...

Macedo, Marcelo A.; Dall Antonia, Luiz H.; Aegerter, Michel A.

1992-01-01

376

Alignment and Nonlinear Elasticity in Biopolymer Gels  

CERN Document Server

We present a Landau type theory for the non-linear elasticity of biopolymer gels with a part of the order parameter describing induced nematic order. Our point of view is that all of the non-linear elastic behavior of these materials can be attributed to the onset of fiber alignment with induced strain. We suggest an application to contact guidance of cell motility in tissue. We compare our theory to simulation of a disordered lattice model for biopolymers. We treat homogeneous deformations such as shear and extension, and also treat the case of a localized perturbation which is intended to be a simple model for a contacting cell in a medium.

Feng, Jingchen; Sander, Leonard M

2014-01-01

377

[Comparative evaluation of the acceptability of a new estradiol gel TX11323(A) and a reference gel].  

Science.gov (United States)

This randomized, crossed, single-blind study compared the acceptability and drying time of the new estradiol gel TX11323(A) (Estréva Gel, Laboratoire Théramex) to that of a reference gel (CEstrodose, Laboratories Besins-Iscovesco), in two phases. In phase 1, 48 healthy menopausal female volunteers applied 1.5 mg estradiol of each form of estradiol gel on the outer side of the arm for 8 days, with a free period of 7 days between the two treatments. Acceptability, evaluated by self-questionnaire and drying time for the two treatments were noted at day 1 and day 8. The second phase applied only to 16 subjects who followed the same therapeutic protocol, except that this time application was made on the antero-external side of the thighs. Only the subjectively and objectively quantified drying-time was taken into account. A significant difference was found in favor of TX11323(A) gel in terms of the following items: consistency, ease of application and penetration, quantity of gel to apply, sensation of lasting stickness. We note that 68.8% subjects prefer TX11323(A) gel and 27.1% prefer the reference gel (p = 0.001). The timed drying-time for TX11323(A) gel is significantly reduced, 40 to 50% on average depending on the phase, compared to that of the reference gel. The subjective evaluation of the subjects confirms this shorter drying time. PMID:8926345

Zartarian, M; Roux, I; Cohen-Leber, C; Gelas, B; Thébault, J

1996-01-01

378

Bioactive materials for biomedical applications using sol-gel technology  

International Nuclear Information System (INIS)

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

2008-09-01

379

Bioactive materials for biomedical applications using sol-gel technology  

Energy Technology Data Exchange (ETDEWEB)

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.

Gupta, Radha; Kumar, Ashok [Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)], E-mail: ashokkum@iitk.ac.in

2008-09-01

380

Method for imparting selectivity to polymeric gel systems  

Energy Technology Data Exchange (ETDEWEB)

This patent describes a method for imparting selectivity to an in-situ gel-forming composition for placement within a subterranean oil-bearing formation having relatively high permeability zones and relatively low permeability zones. It comprises: preparing an aqueous-based mixture comprising: a first stage gel-forming composition; at least one second stage in-situ gel-forming composition comprising a water-dispersible polymer and a crosslinking agent for the water-dispersible polymer in an amount effective to form a stable gel; and gelling the first stage gel-forming composition exsitu by reacting the Xanthomonas campestris NCIB 1185 heteropolysaccharide with the crosslinking agent for the heteropolysaccharide; wherein the mixture exhibits greater selectivity than would a like mixture in the absence of the first stage selective gel-forming composition.

Hoskin, D.H.; Sifferman, T.R.

1992-10-20

 
 
 
 
381

Introduction and overview of problems related to the gel  

Energy Technology Data Exchange (ETDEWEB)

During alteration of most nuclear glasses in aqueous media, an alteration film or gel forms on the glass surface. This gel is characterized by 2 significant properties: -1) Its role as a diffusion barrier, the apparent silicon diffusion coefficients in the interstitial water of the gel, derived by fitting the curves for R7T7 glass leaching experiments, are very low: in the order of 10{sup -16} m{sup 2}.s{sup -1} at 90 Celsius degrees. These values assume very small gel pore dimension (a few nanometers) and strong silicon adsorption on the gel. -2) Its significant retention capacity for some radionuclides such as rare earth elements and actinides, which significantly diminishes the flow of radioelements released from the glass package. A lot of experimental and more theoretical studies are needed to understand nuclear gels as material in order to model them and estimate their evolution over long periods of time. (A.C.)

Jollivet, P.; Vernaz, E. [CEA Valrho, Dir. de l' Energie Nucleaire, DEN, 30 - Marcoule (France)

1997-07-01

382

Fabrication of nanocrystalline cobalt oxide via sol-gel coating  

Energy Technology Data Exchange (ETDEWEB)

Nanocrystalline cobalt oxide thin films were fabricated by sol-gel processing method. The effect of cobalt salt amount in sol-gel mixture on film properties was investigated by means of Raman spectroscopy and atomic force microscopy. Micropatterns of these sol-gel mixtures were fabricated by spin coating followed by a lift-off method. It is generally known that sol-gel processed films are difficult to etch or remove by chemical and plasma techniques. In this novel process, cobalt oxide microstructures could be fabricated by transformation of pre-fabricated nanocrystalline cobalt oxide particles in a sol-gel process. Also, the growth of carbon nanotubes on fabricated cobalt oxide films was investigated. It was found that different size multiwall carbon nanotubes could be grown on the cobalt oxide films depending on the concentration of cobalt salt in sol-gel mixtures.

Jayatissa, Ahalapitiya H. [MIME Department, University of Toledo, OH 43560 (United States)], E-mail: ajayati@utnet.utoledo.edu; Guo, Kun [MIME Department, University of Toledo, OH 43560 (United States); Jayasuriya, Ambalangodage C. [Orthopaedic Department, University of Toledo, OH 43614 (United States); Gupta, Tarun [IME Department, Western Michigan University, MI 49008 (United States)

2007-11-25

383

A NOVEL OPHTHALMIC DRUG DELIVERY SYSTEM: IN-SITU GEL  

Directory of Open Access Journals (Sweden)

Full Text Available The ophthalmic in-situ gels now days proved an palpable sustained drug delivery in various eye diseases. The formulation of in-situ gels for eye which carries the advantages like easy for administration, reduces frequency of dose and improves patient compliance. The formation of in-situ gels depends on phase transition system or sol-gel transition system. The formulation approaches like temperature intonation, pH change and presence of ions from which the drug gets released in a sustained and controlled manner are utilised for in-situ gels. Various polymers that are used for the formulation of in-situ gels include chitosan, Pluronic F-127, poly-caprolactone, gellan gum, alginic acid, xyloglucan, pectin etc.

A.P. Patil*, A.A. Tagalpallewar, G.M. Rasve, A.V. Bendre, P.G. Khapekar

2012-09-01

384

Minimizing of blank values of the miniature silica gel column  

Energy Technology Data Exchange (ETDEWEB)

Several methods involving silica gel separations of polychlorinated biphenyls from chlorinated insecticides are already described in literature. The authors intention was to find a system of solvent and silica gel of the lowest blank values. The first step was to find a solvent mixture which will keep the homogenity of a silica gel column, PCBs elution was performed with pentane, while the chlorinated insecticides eluated with diethylether, acetone, methanol, and benzene. Separation of pesticides from polychlorinated biphenyls found in a synthetic mixture was also examined. It was found that all solvent systems used gave similar results of separation. However, only if benzene is used as eluant, the silica gel column can be used for four successive separations after the ''on column'' regeneration. In order to obtain the lowest blank values silica gel was cleaned with several solvents. The eluates after the silica gel separation were also cleaned up by means of deactivation alumina and concentrated sulfuric acid.

Picer, N.; Picer, M.; Mikac, N.

1982-01-01

385

Preparation of zirconium molybdate gel for 99mTc gel generator  

International Nuclear Information System (INIS)

Zirconium molybdate gel has excellent characteristics for use as column matrix material of 99mTc 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 99mTc generator was prepared with an amorphous zirconium molybdate containing a tracer level of 99Mo as column matrix material. Elution of 99mTc 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)

1988-01-01

386

Surface tension-induced gel fracture. Part 2. Fracture of gelatin gels.  

Science.gov (United States)

The spreading of surfactants on gel layers has been found to be accompanied by an intriguing instability which involves the formation of crack-like patterns on the surface of the gel. In an attempt to extend the findings on the spreading on agar gels presented in part 1 of this series, this paper examines the case of surfactant spreading on gelatin, which is a characteristic example of a protein-based gel. Aqueous solutions of Silwet L-77 of varying concentrations were spread on thick gelatin layers of varying concentrations. The resulting pattern formation was found to have many similarities to the corresponding phenomenon on agar. In terms of spreading dynamics, the values of the spreading exponent, n, of the power law L(t) ~ kt(n), which describes the temporal evolution of the cracks, are similar to those of the agar case, within the predicted limits for surface tension gradient-induced spreading on thick films, highlighting the dominant presence of Marangoni stresses. However, the values of the spreading coefficient, k, are much smaller compared to those measured during the spreading on agar. Further observations are linked with the rheological properties of gelatin, which are also measured in detail. PMID:22512694

Spandagos, Constantinos; Goudoulas, Thomas B; Luckham, Paul F; Matar, Omar K

2012-05-29

387

Sol-Gel Processing of Silica Nuclear Waste Glasses  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A complex Sol-Gel process has been used for synthesis of silica glasses designed to contain high-level nuclear wastes. Cs, Sr, Co, and Nd (generically denoted Me) were used, the last as surrogate for actinides. Gels in the form of powders and sintered compacts were prepared by hydrolysis and polycondensation of tetraethoxide/Me nitrate solutions, which contained ascorbic acid as a catalyst. Thermal treatment studies were conducted on the resulting gels. Transformation to final products was st...

Andrzej Deptu?a; Magdalena Mi?kowska; Wies?awa ?ada; Tadeusz Olczak; Danuta Wawszczak; Tomasz Smolinski; Fabio Zaza; Marcin Brykala; Chmielewski, Andrzej G.; Goretta, Kenneth C.

2011-01-01

388

Capillary gel electrophoresis for rapid, high resolution DNA sequencing.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Swerdlow, H.; Gesteland, R.

1990-01-01

389

Stability of the gel formed during nuclear glass alteration  

International Nuclear Information System (INIS)

This thesis is divided in two parts. The first part is dedicated to the study of the protective properties of the gels formed during the alteration of nuclear glass and the second part the stability of these gels after drying and the effect of the sulfate ions are studied. The protective properties of the gel of SON68 glass are assessed at different alteration progress and related to their morphology analyzed by X-ray reflectometry and gas adsorption. Initially a depleted glass layer is obtained, followed by the formation of a gel with an open porosity. Subsequently the gel densifies as the glass alteration rate decreases and finally the pore size increases upon the formation of a dense and thin zone within the film on the glass surface. The increase of the gradient density zone could explain the increase of the protective properties of the gel. A high reaction progress, when the thin and dense zone within the gel is formed, the protective properties are constant. Various simplified glasses are also studied. At high reaction progress there is a dense zone within the gel. The location of this zone depends on the glass composition which control the competition between the species diffusion in solution and their recondensation. The gel morphology, the protective properties, its stability and the glass composition are correlated. The drying induces some modifications of the morphology of the SON68 glass alteration layer (density, thickness and porosity) and of the mechanical properties (cracks, adhesion on glass). For protective gels these modifications are limited and don't raise the protective properties of the gel. The effect of the sulfate ions in a closed system is essentially to complex calcium. For sulfate ions concentrations in geological repository, the stability of the gel is not raised. (author)

2004-01-01

390

Progress on sol-gel sphere-pac development  

International Nuclear Information System (INIS)

The ORNL sol-gel program is reviewed briefly. Advantages of the sol-gel sphere-pac are listed. Three sizes of microspheres are being used; the two largest sized fractions are blended and then loaded into the fuel rod, followed by packing of the smallest microspheres into void spaces using a low-energy vibrator. Sol-gel sphere-pac also appears attractive for breeder reactor fuel fabrication

1978-05-04

391

Electrophoretic properties of the scrapie agent in agarose gels.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The molecular properties of the scrapie agent were investigated by subjecting partially purified preparations to electrophoresis on agarose gels. When electrophoresis was performed at room temperature in the presence of sodium dodecyl sulfate (NaDodSO4), most of the recoverable agent was found at the top of the gel, consistent with previous studies indicating aggregation of the agent upon exposure to elevated temperatures. In addition, less than 5% of the agent applied to the gel was found af...

Prusiner, S. B.; Groth, D. F.; Bildstein, C.; Masiarz, F. R.; Mckinley, M. P.; Cochran, S. P.

1980-01-01

392

Leading-edge-gel coupling in lamellipodium motion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a model for actin-based motility that combines the dynamics of the semiflexible region at the leading edge of the lamellipodium with actomyosin gel properties in the bulk described by the theory of active polar gels. We calculate the velocity of the lamellipodium determined by the interaction of the gel and adhesion with forces in the semiflexible region. The stationary concave force-velocity relation of the model reproduces experimental results. We suggest that it is determined by...

Zimmermann, J.; Enculescu, M.; Falcke, M.

2010-01-01

393

Preparation of biomolecule gel matrices for electron microscopy  

Energy Technology Data Exchange (ETDEWEB)

We report a new sample preparation method that allows the direct transmission electron microscopy evaluation of the architectural characteristics of biomolecules entrapped in gel matrices. We demonstrate that this sample preparation technique can be used for the identification and ultrastructural characterization of liposomes, collagen I and collagen III embedded in gel matrices, and has the potential to be useful for transmission electron microscopy (TEM) characterization of other biomolecule-gel matrix systems.

Padalkar, Sonal [School of Materials Engineering, Purdue University, 501 Northwestern Avenue, West Lafayette, IN 47907-2044 (United States); Zhao, Jianxiu [Department of Agricultural and Biological Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907-2093 (United States); Stuart, Kate; Panitch, Alyssa [Weldon School of Biomedical Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907-2032 (United States); Rickus, Jenna [Department of Agricultural and Biological Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907-2093 (United States); Weldon School of Biomedical Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907-2032 (United States); Stanciu, Lia [School of Materials Engineering, Purdue University, 501 Northwestern Avenue, West Lafayette, IN 47907-2044 (United States); Weldon School of Biomedical Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907-2032 (United States)], E-mail: lstanciu@purdue.edu

2008-03-15

394

Production of silica gel from residual rice husk ash  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a study on the production of silica gel in hydrothermal process using residual rice husk ash. Measurements of the chemical composition, X-ray diffraction, infrared spectroscopy, particle size distribution, and pozzolanic activity were carried out in order to characterize the obtained material, and the optimal silica gel was selected for use as a mineral additive in cement pastes. The compressive strengths were determined for cement pastes containing silica gel (0.0, 2.5 or...

Samantha Pinheiro Buás de Lima; Raimundo Pereira de Vasconcelos; Otávio Augusto Paiva; Guilherme Chagas Cordeiro; Márcia Rodrigues de Morais Chaves; Romildo Dias Toledo Filho; Eduardo de Moraes Rego Fairbairn

2011-01-01

395

Prenatal Virilization Associated with Paternal Testosterone Gel Therapy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Transdermal testosterone gels are used in the treatment of hypoandrogenism of males. Virilization due to exposure to testosterone gels has been reported in children resulting in a US Food and Drug Administration (FDA) warning about secondary exposure to these products. At present, we are unaware of prenatal virilization associated with unintentional testosterone gel exposure. We report prenatal virilization in a female infant due to secondary maternal exposure to the father's testoste...

Patel Anisha; Rivkees ScottA

2010-01-01

396

Collective Movement of Epithelial Cells on a Collagen Gel Substrate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Collective cell movement acts as an efficient strategy in many physiological events, including wound healing, embryonic development, and morphogenesis. We found that epithelial cells (Madin-Darby canine kidney cell) migrated collectively along one direction on a collagen gel substrate. Time-lapse images of Madin-Darby canine kidney cells cultured on type-I collagen gels and glass substrates were captured by phase contrast microscopy equipped with an incubation system. On the gel substrate, th...

Haga, Hisashi; Irahara, Chikako; Kobayashi, Ryo; Nakagaki, Toshiyuki; Kawabata, Kazushige

2005-01-01

397

Pacman percolation: a model for enzyme gel degradation  

CERN Multimedia

We study a model for the gel degradation by an enzyme, where the gel is schematized as a cubic lattice, and the enzyme as a random walker, that cuts the bonds over which it passes. The model undergoes a (reverse) percolation transition, which for low density of enzymes falls in a universality class different from random percolation. In particular we have measured a gel fraction critical exponent beta=1.0+-0.1, in excellent agreement with experiments made on the real system.

Abete, T; Lairez, D; Coniglio, A

2004-01-01

398

Accumulation of humic acid in DET/DGT gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Gel layer based sensors are increasingly employed for dynamic trace metal speciation analysis in aquatic and soil media. In DGT (Diffusive Gradient in Thin film), polyacrylamide hydrogels are commonly used for the diffusive gel layer. While some effects of humic and fulvic acids on the DGT detection of metal species have been observed, the gel permeation properties of the actual humic and fulvic acid compounds themselves have not been analyzed thus far. Here we show with DET (Diffusive Equili...

Veeken, P. L. R.; Chakraborty, P.; Leeuwen, H. P.

2010-01-01

399

A reproducible, high throughput method for fabricating fibrin gels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background Fibrin gels are a promising biomaterial for tissue engineering. However, current fabrication methods are time intensive with inherent variation. There is a pressing need to develop new and consistent approaches for producing fibrin-based hydrogels for examination. Findings We developed a high throughput method for creating fibrin gels using molds fabricated from polydimethylsiloxane (PDMS). Fibrin gels were produced by adding solutions of fib...

Murphy Kaitlin C; Leach J

2012-01-01

400

Nanocrystalline Pentaerythritoltetranitrate using Sol-Gel Process  

Directory of Open Access Journals (Sweden)

Full Text Available The secondary explosives developed with reduced particle size tend to be more insensitive for mechanical stimuli and may release energy with faster rate and gaining more importance nowadays. Therefore, aiming to reduce the particle size of one of the popular explosives, viz., pentaerythritoltetranitrate (PETN to the nanometer range, a method for preparation of nanocrystalline PETN in the silica (SiO2 gel matrix using sol-gel process has been demonstrated. The PETN-SiO2 xerogels were prepared containing PETN content ranging from 50 per cent to 90 per cent (w/w and the xerogels were characterised using different techniques. An exothermic peak at around 185 oC preceded by an endotherm in thermal analysis accompanied with weight loss in the temperature range from 150 oC to 200 oC for the xerogel confirmed the presence of PETN in xerogel. Infrared spectra of xerogels showed peaks at around 1285 cm-1 and 1700 cm-1 assigned to O-NO2 and C-O bond representing PETN. Small angle x-ray scattering measurements on xerogels indicated that PETN entered in the pores of silica matrix. Transmission electron microscopy revealed that cystalline PETN with particle size of around 15 nm dispersed in silica xerogel. The specific surface area for the PETN-SiO2 (90:10 xerogels was found to be 75 m2/g.

S.V. Ingale

2011-11-01

 
 
 
 
401

Brownian Dynamics simulations of aging colloidal gels  

CERN Multimedia

Colloidal gel aging is investigated using very long runs of brownian dynamics simulations. The Asakura Oosawa description of the depletion interaction is used to model a simple colloid polymer mixture. Several regimes are identified during gel formation. The Intermediate scattering function displays a double decay characteristic of systems where some kinetic processes are frozen. The $\\beta$ relaxation at short times is explained in terms of the Krall-Weitz model for the decorelation due to the elastic modes present. The $\\alpha$ relaxation at long times is well described by a stretched exponential, showing a wide spectrum of relaxation times for which the $q$ dependence is $\\tau_{\\alpha} = q^{-2.2}$, lower than for diffusion. For the shortest waiting times, a combination of two stretched exponentials is used, suggesting a bimodal distribution. The extracted relaxation times vary with waiting time as $\\tau_{\\alpha}=\\tau_w^{0.66}$, slower than the simple aging case. The real space displacements are found to be...

D'Arjuzon, R J M; Melrose, J R; Arjuzon, Rodolphe J. M. d'; Frith, William; Melrose, John R.

2002-01-01

402

Sol-gel synthesis of heterometallic oxopolymers  

Energy Technology Data Exchange (ETDEWEB)

Oxopolymers can be obtained via the hydrolysis and condensation of metal alkoxides M(OR){sub z}. The design of these molecular precursors by chemical modification provides a chemical control over the formation of condensed species. Depending on the hydrolysis ratio h=H{sub 2}O/M and the amount of complexing ligands x-X/M, molecular species, oxopolymers or colloidal particles can be obtained. More condensed species are obtained as x decreases and h increases. A major problem in forming homogeneous multicomponent gels is the unequal hydrolysis and condensation rates of the metal alkoxides which may result in chemical inhomogeneities. Several approaches have been attempted to overcome this problem, including partial prehydrolysis, matching of hydrolysis rates by chemical modification with chelating ligands and synthesis of double alkoxides. This paper discusses the formation of heterometallic alkoxides or oxo-alkoxides as precursors for heterometallic oxopolymers. Special attention will be given to silica based materials and the stability of Si-O-Ti or Si-O-Al bonds during the course of sol-gel chemistry.

Livage, J.; Babonneau, F.; Coury, L. [Universite Pierre et Marie Curie, Paris (France)

1993-12-31

403

Ionic diffusion in frozen starch gels.  

Science.gov (United States)

Quality changes in food frozen by different conditions and at different storage temperatures were demonstrated using a model system. A frozen starch gel represents a frozen food matrix, and ions in the external medium represent the reactant molecules. We determined the effective diffusion rates of Zn+2 ions into frozen starch gel cylinders that were frozen at different freezing rates. The diffusion was performed at -8 degrees and -15 degrees C. The amounts of ion diffused were determined by atomic absorption, whilst the structure of the frozen samples could be simultaneously determined by scanning electron microscopy. The effective diffusion rates were found to correlate with the amount of unfrozen portion of the samples. This suggests that ions move mainly through the unfrozen portion around the ice crystals. Fast- and slow-frozen samples exhibited significantly different effective diffusion rates at -15 degrees C, which might be due to differences in size and orientation of ice crystals. Zn+2 ions moved slower at -15 degrees C than at -8 degrees C. PMID:1746358

Charoenrein, S; Reid, D S

1991-01-01

404

Il Gel Piastrinico in chirurgia orale  

Directory of Open Access Journals (Sweden)

Full Text Available Obiettivi: L’utilizzo topico di emocomponenti autologhi, il concentrato piastrinico (CP ed il plasma povero di piastrine, rappresenta una delle strategie più innovative per modulare ed amplificare i processi di guarigione e di rigenerazione tessutale. Con questo studio si è dimostrato che l’applicazione del gel piastrinico, quando viene applicato in chirurgia orale ed in particolare nell’implantologia, è in grado di migliorare ed accelerare i processi osteogenetici;Metodologia: il CP, preparato a partire da un prelievo contenuto di sangue venoso (30-60 ml, viene attivato mediante una miscela di calcio gluconato e batroxobina (un enzima similtrombinico. Nell’arco di 3-5 minuti si ottiene un bioprodotto pronto per rilasciare in situ, verosimilmente, quei GFs fondamentali per la guarigione e la rigenerazione dei tessuti circostanti.;Conclusioni: il gel piastrinico, una biotecnologia efficace, semplice e dai costi contenuti, offre ai clinici l’opportunità di poter disporre di uno strumento innovativo atto a ridurre i tempi di guarigione e le complicanze post-operative, migliorando notevolmente la qualità di vita dei pazienti;

Sacchi M.C.

2012-01-01

405

DEVELOPMENT OF MELOXICAM SODIUM TRANSDERMAL GEL  

Directory of Open Access Journals (Sweden)

Full Text Available High molecular weight water soluble homopolymer of carbapol 934P resins are reported to possess very high viscosity in low concentration, transparency and film forming properties useful for gels. The meloxicam sodium gels were prepared by varying the concentration of penetration enhancer’s ethanol, PEG 400, menthol and azone. Selection of optimized batch was done on the basis of results of rheological studies and in-vitro drug permeation. Formulation F19 with highest amount of menthol shows highest permeability of meloxicam sodium (89.96% at the end of 12 hrs this indicates that menthol showed significant permeation enhancement effect. The permeation rate (flux for F19 was 260.11 µg/cm2/h. Obtained R2 values for zero-order model suggests that the drug follows zero-order release kinetics. The rheological characterization of formulated systems showed that the systems exhibit non-Newtonian behavior and The optimized formulation C1 showed higher % cumulative permeation of meloxicam sodium (> 95.00% and permeation rates (flux.

Dr. Shashikant D. Barhate

2010-07-01

406

Microfluidic dielectrophoretic sorter using gel vertical electrodes.  

Science.gov (United States)

We report the development and results of a two-step method for sorting cells and small particles in a microfluidic device. This approach uses a single microfluidic channel that has (1) a microfabricated sieve which efficiently focuses particles into a thin stream, followed by (2) a dielectrophoresis (DEP) section consisting of electrodes along the channel walls for efficient continuous sorting based on dielectric properties of the particles. For our demonstration, the device was constructed of polydimethylsiloxane, bonded to a glass surface, and conductive agarose gel electrodes. Gold traces were used to make electrical connections to the conductive gel. The device had several novel features that aided performance of the sorting. These included a sieving structure that performed continuous displacement of particles into a single stream within the microfluidic channel (improving the performance of downstream DEP, and avoiding the need for additional focusing flow inlets), and DEP electrodes that were the full height of the microfluidic walls ("vertical electrodes"), allowing for improved formation and control of electric field gradients in the microfluidic device. The device was used to sort polymer particles and HeLa cells, demonstrating that this unique combination provides improved capability for continuous DEP sorting of particles in a microfluidic device. PMID:24926390

Luo, Jason; Nelson, Edward L; Li, G P; Bachman, Mark

2014-05-01

407

Investigation of ultrasonic properties of MAGIC gels for pulse-echo gel dosimetry  

International Nuclear Information System (INIS)

Ultrasound has been proposed as an alternative 3D method to read out dosimetric gels. The ultrasonic properties of MAGIC gel are investigated in relation to producing a dosimetry system based on a pulse-echo technique. The sound speed, attenuation coefficient, and density of MAGIC gel were measured over a range of temperatures and doses. A nonlinear relationship between ultrasonic attenuation and dose was observed, with the attenuation below 10 Gy being approximately constant. The sound speed was 1550.3 ± 1.5 m s-1 at 25 0C with a dose sensitivity of 0.14 ± 0.03 m s-1 Gy-1; both properties changed with temperature and were 1535.4 ± 0.8 m s-1 and -0.08 ± 0.01 m s-1 Gy-1 respectively at 15 0C. The density also varied with temperature and dose, and was 1028.9 ± 0.3 kg m-3 with a dose sensitivity of 0.178 ± 0.004 kg m-3 Gy-1 at 26 0C. The characteristic acoustic impedance of MAGIC gel was calculated to be 1.596 x 106 kg m2 s-1 at 0 Gy and 25 0C. The dose sensitivities measured indicate that changes to the characteristic acoustic impedance caused by irradiation are small, and therefore a reflector that has a similar characteristic acoustic impedance is required to maximise sensitivity of the pulse-echo technique. A suitable material has been developed and the reflection characteristics of the interface between MAGIC gel and the reflector are also temperature dependent. It is concluded that temperature management will be central to the development of any practical pulse-echo dosimetry system.

2010-11-01

408

Demonstration of a solar gel pond. Final report  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this work was to demonstrate the gel pond concept in a small pond, to document performance and to study various aspects of this new technology. The pond and the surrounding ground was instrumented with thermocouples, and meteorological parameters were monitored. Insofar as comparisons could be made, the gel pond was superior to a similar salt gradient pond. Surface heat losses were considerably less, and stability problems of course nonexistent. Existing models of stratified ponds were reviewed and both steady state and unsteady state model for the gel pond were constructed. Prediction of these models agreed well with actual experimental data from the gel pond. Possible use of phase change materials to enhance heat storage in the gel pond was investigated. Both calculation and laboratory experiments for selected materials were performed; it was concluded that the present cost of the best material does not justify their use at present. Physical properties of various gel material were measured (density, specific heat, thermal conductivity, life time, and optical transmissivity). In general the physical properties of gel were similar to that of water. Optical transmissivity was also monitored out doors in a pond. A restrictive cost-benefit analysis was conducted comparing the salt gradient and the gel pond in the same location for varying location, load, size. It is demonstrated that the gel pond energy cost is lower than that from salt gradient ponds.

Wilkins, E.S.

1984-04-01

409

Successful treatment of Darier's disease with adapalene gel.  

Science.gov (United States)

We report a 12-year-old Japanese boy with a 3-year history of skin lesions that had been unsuccessfully treated with topical steroids. We initiated two different topical treatments with adapalene gel 0.1% (Differin(®) Gel 0.1%) and high-concentration vitamin D3 (tacalcitol) ointment; the lesions treated with adapalene gel improved dramatically in the first 2 months, whereas the high-concentration vitamin D3 ointment resulted in little improvement. Topical adapalene gel 0.1% may be a promising choice as a topical treatment of Darier's disease because of its high efficiency and lack of adverse effects. PMID:20403120

Abe, Masatoshi; Inoue, Chizuru; Yokoyama, Yoko; Ishikawa, Osamu

2011-01-01

410

Moisture transport in silica gel particle beds. [DESSICANT  

Energy Technology Data Exchange (ETDEWEB)

A theoretical and experimental study of the performance of silica gel packed particle beds is described. A bench-state test rig was used to obtain data for parameter values pertinent to solar air-conditioning applications. Both adsorption and desorption experiments were performed for Regular Density (RD) silica gel for a wide range of particle size. Adsorption data was also obtained for Intermediate Density (ID) gel. A model of heat and mass transfer in the bed was developed with special attention paid to the modeling of solid side resistance. For this latter purpose an extensive review of the available literature on moisture adsorption and moisture transport in silica gel was made. Both Knudsen and surface diffusion are found to be important mechanisms of moisture transport in Intermediate Density gels (mean pore radius 68 A) while surface diffusion is dominant in Regular Density gels (mean pore radius 11 A). A general equation for moisture transport in a spherical silica gel particle was developed and was incorporated into the model equations governing heat and mass transfer between the gel particles and air flowing through a packed particle bed. A computer code DESICCANT was written to solve the coupled set of partial differential equations using a finite difference numerical method. The agreement between theory and experiment for adsorption on RD gel is satisfactory, and is somewhat better for the outlet water vapor concentration than for the outlet air temperature.

Pesaran, A.A.

1983-01-01

411

Investigation of polymer gel dosimetry for small circular irradiated fields  

International Nuclear Information System (INIS)

Polymer gels can be used as tissue equivalent dosimeters, and polymer gel dosimetry can be employed without perturbation of the radiation field. In this study, polymer gel dosimetry was used for small circular irradiation fields 10-30 mm in diameter using a radiation planning system. The irradiated gels were compared with planned data for a 50% dose width of 6 Gy dose maximum, and for the dose difference between gels and planned data over an 80% dose maximum area. The present study investigated magnetic resonance imaging (MRI) conditions based on an optimal dose-R2 calibration curve. The average difference between the full width half maximum of the 50% dose width between gels and planned data was 11%. The average dose difference over 80% of the dose was 5.6%. Optimal dose-R2 calibration curves were acquired using images with echo times of 30 and 60 ms. For cases of larger thicknesses and an increasing number of averages, the coefficients of variance of the curves were smaller than under other conditions. Compared to other traditional dosimetric tools, polymer gels have the advantage of providing three-dimensional dosimetric data. An arbitrary profile from the gel's data can be compared with the profile of the planned data. In the future, new gel dosimeters will be needed that demonstrate improved dose evaluation under 1 Gy and stability in high dose areas. (author)

2013-09-01

412

Production of silica gel from residual rice husk ash  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a study on the production of silica gel in hydrothermal process using residual rice husk ash. Measurements of the chemical composition, X-ray diffraction, infrared spectroscopy, particle size distribution, and pozzolanic activity were carried out in order to characterize the obtained material, and the optimal silica gel was selected for use as a mineral additive in cement pastes. The compressive strengths were determined for cement pastes containing silica gel (0.0, 2.5 or 5% by mass in different times. The results indicate that the mixtures containing silica gel showed improved mechanical behavior over all time periods evaluated.

Samantha Pinheiro Buás de Lima

2011-01-01

413

Deswelling kinetics of polyacrylate gels in solutions of cetyltrimethylammonium bromide.  

Science.gov (United States)

The deswelling kinetics of single sodium polyacrylate gel beads (radius 40-160 microm) in aqueous solutions of cetyltrimethylammonium bromide under conditions of forced convection are investigated using micromanipulator assisted light microscopy. The purpose of the study is to further evaluate a previously published model (J. Phys. Chem. B 2003, 107, 9203) using a higher homolog surfactant. For gels with expected fast deswelling (small gel size/low surfactant concentration) and/or in low electrolyte concentration, the model is found to correctly predict the deswelling characteristics of the gel beads. However, for some gels with expected slow deswelling, especially in high electrolyte concentration (10 mM NaBr), the model widely underestimates the required deswelling time. The reason for this is argued to be the longer time frame and high bromide concentration allowing the formation of a denser, more ordered structure in the surface phase, which resists the deformation and reorganization of material necessary for deswelling. Unexpectedly long lag times before the start of deswelling are also found for gels in low surfactant concentration, indicating that a relatively high surfactant concentration in the gel, greatly exceeding the critical aggregation concentration, is needed to start formation of a collapsed surface phase. This critical surfactant concentration is found to be dependent on initial gel radius, as small gels require a relatively higher concentration to initiate collapse. PMID:17655349

Nilsson, Peter; Hansson, Per

2007-08-23

414

Dynamic performance characterization of bound, porous silica gel desiccant  

Energy Technology Data Exchange (ETDEWEB)

Drying of air with silica gel is a well established procedure. However, for the specific use of silica gel in a novel desiccant air conditioning system, which continually cools the silica gel and utilizes solar energy for silica gel regeneration, conventional packed bed devices are not suitable. For this system to operate effectively the silica gel must not rise in its temperature or its capacity will be greatly diminished. Dynamic dehumidificatuion performance was investigted for a silica gel desiccant fabricated in bound, porous paper-like sheets. Sheets of various thickness (0.7 to 3 mm) were fabricated and tested under several dynamic flow conditions in a flat rectangular channel apparatus. During each experiment conditions of inlet moisture, air flowrate, and sheet temperature were maintained constant. Comparisons were also made with conventional silica gel pellets and with other forms of bound silica gel. The sheets show superior utilization of silica gel in short times (30 minutes or less). Tests were also made to examine the sheet structure in order to explore the effect of temperature on the porous structure, and to obtain pore size distributions.

Onischak, M.; Gidaspow, D.; Perkari, S.; Sasaki, T.

1979-10-01

415

Sol-gel preparation of uranium oxide spheres  

International Nuclear Information System (INIS)

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)

1978-01-01

416

Radiation effect on polystyrene deposited and grafted on silica gel  

International Nuclear Information System (INIS)

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

1978-01-01

417

Preparation and Evaluation of Topical Gel of Valdecoxib  

Directory of Open Access Journals (Sweden)

Full Text Available Topical gels of Valdecoxib topical gel prepared using different gelling agents (Viz, carbopol, HPMC, sodium alginate, sodium CMC. Formulations were evaluated for pH, rheological behavior, drug content and in vitro drug diffusion. Selected formulations of all the gelling agents appeared to be non-Newtonian and pseudo plastic behavior. Drug content was high (>98 % in gels. Drug release from the carbopol gels increased with the increase in the concentration of PG up to 10 %. However, drug release decreased as the concentration of the PG increased to 20 %. The drug release increased with the increase in concentration of ethanol. In case of gels containing HPMC, sodium alginate, sodium CMC as gelling agents, addition of PG up to 5 %, increased the release of dru