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Prevalence of Peste Des Petits Ruminants Virus (PPRV in Mardan, Hangu and Kohat District of Pakistan; Comparative Analysis of PPRV Suspected serum samples using Competitive ELISA (cELISA and Agar Gel Immunodiffusion (AGID  

Directory of Open Access Journals (Sweden)

Full Text Available Peste des petits Ruminants (PPR is an acute, febrile, highly contagious and economically important viral disease of small ruminants. However PPR is more prevalent in sheep and goat. Competitive ELISA, Virus neutrilization test, and RT-PCR are the available techniques for diagnosis of PPR which give rapid detection where as Agar gel immunodiffusion and Counter immunoelectrophoresis were previously used for PPR detection. In this study two serological techniques were compared for PPR diagnosis. The main aim of this study was to evaluate the comparative sensitivity of both techniques for PPR detection. For this purpose one hundred and sixty PPR suspected serum samples collected from goats and sheep flocks (unvaccinated from three Districts of NWFP including Mardan, Hangu and Kohat were analyzed in National Veterinary Laboratories, Islamabad. Out of these 160 samples, fifty (50 were found positive for PPR antibodies with cELISA (Prevalence = 31.25%. The cELISA positive serum samples however gave negative results when tested with AGID although the control well was always positive. Thus it was concluded that cELISA technique is more sensitive and specific than AGID for PPR antibody detection. [Vet. World 2009; 2(3.000: 89-92

Misbah Aslam

2009-06-01

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Prevalence of Peste Des Petits Ruminants Virus (PPRV) in Mardan, Hangu and Kohat District of Pakistan; Comparative Analysis of PPRV Suspected serum samples using Competitive ELISA (cELISA) and Agar Gel Immunodiffusion (AGID)  

OpenAIRE

Peste des petits Ruminants (PPR) is an acute, febrile, highly contagious and economically important viral disease of small ruminants. However PPR is more prevalent in sheep and goat. Competitive ELISA, Virus neutrilization test, and RT-PCR are the available techniques for diagnosis of PPR which give rapid detection where as Agar gel immunodiffusion and Counter immunoelectrophoresis were previously used for PPR detection. In this study two serological techniques were compared for PPR diagnosis...

Misbah Aslam; Muhammad Abubakar; Rehana Anjum; Shamim Saleha; and Qurban Ali

2009-01-01

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Comparison of agar gel immunodiffusion test, enzyme-linked immunosorbent assay and PCR in diagnostics of enzootic bovine leukosis  

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Full Text Available Bovine leukaemia virus (BLV is a retrovirus that induces a chronic infection in cattle. Once infected, cattle remain virus carriers for life and start to show an antibody response within a few weeks after infection. Eradication and control of the disease are based on early diagnostics and segregation of the carriers. The choice of a diagnostic method depends on the eradication programme, money resources and characteristics of the herd to be analysed. The agar gel immunodiffusion (AGID test has been the serological test of choice for routine diagnosis of serum samples. Nevertheless, in more recent years, the enzyme-linked immunosorbent assay (ELISA has replaced the AGID for large scale testing. For this purpose, commercially available BLV-ELISA kits were compared to the AGID and to the polymerase chain reaction (PCR method performed with two sets of primers, amplifying env region. The ELISA kit based on the p24 core protein was found to be less specific and served as a screening test. The ELISA kit based on the envelope glycoprotein (gpSI served as a verification test and gave a good correlation with the AGID test and PCR method. However, ELISA showed a higher sensitivity than AGID. The p24 based ELiSA was useful for screening a large number of samples, whereas gp51 based ELISA, AGID and PCR were more important for detecting the antibody response against the individual BLV-proteins and therefore for verification of the infection with BLV.

Malovrh Tadej

2005-01-01

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Evaluation of agar gel immunodiffusion and indirect fluorescent antibody assays as supplemental tests for dourine in equids.  

Science.gov (United States)

The agar gel immunodiffusion (AGID) and indirect fluorescent antibody (IFA) assays were evaluated as supplemental tests to the complement-fixation (CF) test, the official US importation certification test for dourine in equids. The American stabilate (n = 10 animals) or the Canadian stabilate (n = 6 animals) of Trypanosoma equiperdum cultured in rat blood was administered by catheterization and infusion in the urogenital tract of 16 equids. To assess parasitemia and serologic responses by use of the CF, AGID, and IFA tests, a total of 787 serum and blood samples were obtained from equids before exposure and 3 times a week after exposure to T equiperdum. Results of the IFA and AGID tests were compared with the CF test results. The disease was diagnosed earlier by the IFA test than by the AGID test, regardless of antigen preparation or exposure group. The mean number of days between exposure and positive result by the CF and IFA tests was the same when either homologous or heterologous antigen was used in the IFA test. In general, the IFA test was more sensitive than the AGID test in diagnosing dourine, regardless of the antigen preparation used in the test or exposure group. Differences in test specificity were observed among both groups of exposed equids when either antigen was used (P < 0.05). The AGID test, using the American antigen, was more specific than the IFA test for sera from both groups of equids. When the Canadian antigen was used, the IFA test was a more specific test than the AGID test (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8214884

Hagebock, J M; Chieves, L; Frerichs, W M; Miller, C D

1993-08-01

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An enzyme-linked immunosorbent assay for detection of antibodies to maedi-visna virus in sheep. II. Comparison to conventional agar gel immunodiffusion test.  

OpenAIRE

A study was conducted to compare the indirect enzyme-linked immunosorbent-assay (i-ELISA) test using antigen prepared by a simple technique using sodium dodecyl sulfate (SDS) treatment to the conventional agar gel immunodiffusion test (AGID). Ten specific-pathogen-free (SPF) sheep were inoculated with maedi-visna virus (MVV) and serum antibody titers compared over a period of 14 weeks. All the sheep seroconverted by the i-ELISA compared to 90% by the AGID. The i-ELISA detected antibody at a m...

Simard, C. L.; Briscoe, M. R.

1990-01-01

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An enzyme-linked immunosorbent assay for detection of antibodies to maedi-visna virus in sheep. II. Comparison to conventional agar gel immunodiffusion test.  

Science.gov (United States)

A study was conducted to compare the indirect enzyme-linked immunosorbent-assay (i-ELISA) test using antigen prepared by a simple technique using sodium dodecyl sulfate (SDS) treatment to the conventional agar gel immunodiffusion test (AGID). Ten specific-pathogen-free (SPF) sheep were inoculated with maedi-visna virus (MVV) and serum antibody titers compared over a period of 14 weeks. All the sheep seroconverted by the i-ELISA compared to 90% by the AGID. The i-ELISA detected antibody at a mean of 2.6 weeks prior to the AGID. In both tests, fluctuations were observed in the serum antibody response of two sheep. The i-ELISA had a specificity of at least 98.8% and an increased relative sensitivity of 15.5% compared to the AGID, based on the analysis of sera from experimental sheep with MVV free status and sera from sheep from various sources. Of the sera from a seronegative flock which had been monitored with the AGID after a "test and remove" eradication program, 10.2% were positive by the i-ELISA. It was concluded that the AGID test may not be adequate to monitor samples for an eradication scheme. PMID:2174296

Simard, C L; Briscoe, M R

1990-10-01

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Comparison of agar gel immunodiffusion test, rapid slide agglutination test, microbiological culture and PCR for the diagnosis of canine brucellosis.  

Science.gov (United States)

The performance of the rapid slide agglutination test, with and without 2-mercaptoethanol (RSAT and 2ME-RSAT) and agar gel immunodiffusion test (AGID) was evaluated for the diagnosis of brucellosis in naturally infected dogs. The microbiological culture, PCR and clinical parameters were used as reference. A total of 167 dogs were clinically examined and tested by blood culture, culture of semen/vaginal swab and PCR in blood and semen/vaginal swab. According to the results observed the 167 dogs were divided into three groups: Brucella canis infected dogs (Group 1), B. canis non-infected dogs (Group 2) and dogs with suspected brucellosis (Group 3). The dogs were then tested by RSAT, 2ME-RSAT and AGID. Groups 1 and 2 were used to calculate the diagnostic sensitivity and specificity of the serological tests and the results observed in Group 3 were also discussed. The diagnostic sensitivity of RSAT, 2ME-RSAT and AGID was respectively 70.58%, 31.76%, and 52.94%. The diagnostic specificity of RSAT, 2ME-RSAT and AGID was respectively 83.34%, 100%, and 100%. In dogs with suspected brucellosis 15% were RSAT positive, none was 2ME-RSAT positive and 5% were AGID positive. Although the serological tests are the most commonly used methods for brucellosis diagnosis, a significant proportion of false-negative results were observed highlighting the importance of the direct methods of diagnosis, like blood culture and PCR to improve the diagnosis of canine brucellosis. PMID:18656213

Keid, Lara B; Soares, Rodrigo M; Vasconcellos, Silvio A; Megid, Jane; Salgado, Vanessa R; Richtzenhain, Leonardo J

2009-02-01

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Comparative efficacy of standard AGID and precipitinogen inhibition test with monoclonal antibodies based competitive ELISA for the serology of Peste des Petits Ruminants in sheep and goats.  

Science.gov (United States)

This project was conducted to investigate the comparative efficiency of competitive ELISA (cELISA), standard Agar Gel Immunodiffusion Test (AGID) and Precipitinogen Inhibition Test (PIT) for the diagnosis of Peste des Petits Ruminants (PPR) in Pakistan. To deal with this, serum samples from 198 sheep and 82 goats were collected from three different government livestock farms and all the samples were run simultaneously with the three serological tests. The samples found positive for PPR antibodies through cELISA, AGID and PIT were 96 (34.2%), 60 (21.4%) and 72 (25.7%), respectively. Kappa statistics were applied to evaluate the concordance between the laboratory-based test (cELISA) and field-based tests (AGID and PIT). Kappa statistics scores for cELISA versus AGID and PIT were 0.6343 (95% Confidence Interval CI 0.5231-0.7456) and 0.7134 (95% Confidence Interval CI 0.5987-0.8281), respectively, which indicate a "substantial" agreement between cELISA and AGID and "significant" agreement between cELISA and PIT. AGID and PIT revealed relative diagnostic sensitivities with cELISA of 59.3% and 69.7% and relative diagnostic specificities of 98.3% and 97.2%, respectively. The data suggested that for mass screening and control of PPR, these serological tests proved practical in the absence of cELISA since they have high relative diagnostic specificities and a satisfactory relative diagnostic sensitivities. PMID:18622735

Munir, Muhammad; Siddique, Muhammad; Ali, Qurban

2009-03-01

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Development of a multispecies identification field test by modified agar-gel immunodiffusion.  

Science.gov (United States)

A multispecies identification field test (MULTI-SIFT) was developed for detection of beef, poultry, pork, sheep, horse, and deer in a wide variety of raw meat products. The test is an adaptation of previously developed field screening immunodiffusion tests for detection of single species. MULTI-SIFT was demonstrated to be specific, relatively sensitive, and accurate in the complete speciation of 100 meat samples. PMID:8241808

Cutufelli, M E; Mageau, R P; Schwab, B; Johnston, R W

1993-01-01

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Use of enzyme immunoassay (ELISA) for monitoring effectiveness of rinderpest vaccination and comparative evaluation with Agar-Gel immunodiffusion test  

International Nuclear Information System (INIS)

In line with other countries participating in the Pan African Rinderpest Campaign, Ghana wishes to monitor the success of a national rinderpest vaccination campaign. This involves the collection of sera from throughout the country in an epidemiologically acceptable manner and the use of a serological procedure that can test the sera for the presence of antibodies to the rinderpest virus. A comparison was carried out between an FAO/IAEA ELISA based system and an Agar-Gel Immunodiffusion test for the detection of antibodies to rinderpest virus in cattle. the ELISA was found to be faster than the Agar-Gel test, could handle larger number of samples in a short time and could detect lower levels than of immunoglobulins. Utilising the ELISA system to examine sera collected in two surveys of 3,500 and 1,818 samples from three regions (Greater Accra, Central and Volta regions) a very marked variable rate of seroconversion was demonstrated with levels lower than the desired 85%. It would appear that the primary cause of these lower than expected levels was related to an inadequate cold-chain. (author). 7 refs, 1 fig., 4 tabs

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Evaluación de la eficacia de la prueba de inmunodifusión en gel agar para la detección de anticuerpos contra el virus de la leucosis enzootica bovina Assessment of the Efficacy of the Agar Gel Immunodiffusion Test for the Detection of Antibodies Against the Enzootic Bovine Leukosis Virus  

Directory of Open Access Journals (Sweden)

Full Text Available contra el virus de la leucosis enzoótica bovina (VLEB, comparándola con el ensayo inmunoenzimático (ELISA. Se procesaron 360 muestras de suero bovino para ambas pruebas, siguiendo las indicaciones del fabricante. El grado de concordancia (GC, valores predictivos (VP y razones de verosimilitud (RV fueron determinados y analizados. El GC entre ambas pruebas resultó ser del 86,4%, con un coeficiente Kappa (K = 0,7. La IDGA detectó una significativa (PThe efficacy of the agar gel immunodifusion test (AGID for the detection of antibodies against the enzootic bovine leucosis virus (EBLV was evaluated and compared with the ELISA test. A total of 360 bovine serum samples were tested for both tests, following the manufacturer instructions. The agreement degree (AD, predictive values (PV, and coefficient of probability (CP were determined and analyzed. There was a good AD between both tests (86.4%; Kappa coefficient =0.7. The AGID test detected a significant (P<0.001 lesser proportion (47.2% of positive sera than the ELISA test (60.8%. The AGID sensitivity was 77.6% lower than the expected, while there was 100% specificity. The positive PV of a 100% and the positive CP with an undetermined value (? showed that AGID is a safe test for the detection of cattle infected with EBLV. In contrast, the negative PV of 74.2% and the negative CP of 0.2 indicate that there is a slight probability that cattle, whose sera were negative to EBLV using the AGID, are really free of EBLV infection. These results suggest that AGID is a suitable test for epidemiological studies, inpopulations with high EBLV prevalence, due to the minor risk of producing false positive results. However in populations with low prevalence of the disease, the use of the AGID test would be restricted due to the high possibility of giving false negative results. Therefore, the ELISA should be the test selected for eradication programs. This work is a contribution to the control and eradication programs of the enzootic bovine leucosis, since it provides information which allows the selection of the most adequate technique, according to the epidemiological status of this disease in the zone and the sanitary target pursued

Zoraida Nava

2012-06-01

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Imunodifusão em gel de ágar com polissacarídeos de membrana de Brucella abortus 1119-3 no diagnóstico da brucelose bovina / Membrane polysaccharides of Brucella abortus 1119-3 in agar gel immunodifusion test in diagnosis of bovine brucellosis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Comparou-se a prova de imunodifusão em gel de ágar (IDGA), utilizando extrato polissacarídico (POLI O), obtido da amostra de B. abortus 1119-3, com os testes de soroaglutinação rápida em placa, de soroaglutinação lenta em tubos, de antígeno acidificado e de 2-mercaptoetanol para o diagnóstico da bru [...] celose bovina. O IDGA mostrou alta especificidade, porém sensibilidade inferior aos métodos convencionais. Abstract in english An agar gel immunodiffusion (AGID) test using the polysaccharide (POLIO O) extract obtained from Brucella abortus strain 1119-3, was compared to plate agglutination, tube agglutination, rose bengal plate and mercaptoethanol tests in the diagnosis of bovine brucellosis. The AGID assay with B. abortur [...] s polysaccharide antigens, presented a greater specificity but lower sensitivity for detecting brucellosis infected animals as compared to the conventional methods of antibody detection.

J., Megid; M.G., Ribeiro; J.V.B., Agottani; G., Marcos Jr.

1999-10-01

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Imunodifusão em gel de ágar com polissacarídeos de membrana de Brucella abortus 1119-3 no diagnóstico da brucelose bovina Membrane polysaccharides of Brucella abortus 1119-3 in agar gel immunodifusion test in diagnosis of bovine brucellosis  

Directory of Open Access Journals (Sweden)

Full Text Available Comparou-se a prova de imunodifusão em gel de ágar (IDGA, utilizando extrato polissacarídico (POLI O, obtido da amostra de B. abortus 1119-3, com os testes de soroaglutinação rápida em placa, de soroaglutinação lenta em tubos, de antígeno acidificado e de 2-mercaptoetanol para o diagnóstico da brucelose bovina. O IDGA mostrou alta especificidade, porém sensibilidade inferior aos métodos convencionais.An agar gel immunodiffusion (AGID test using the polysaccharide (POLIO O extract obtained from Brucella abortus strain 1119-3, was compared to plate agglutination, tube agglutination, rose bengal plate and mercaptoethanol tests in the diagnosis of bovine brucellosis. The AGID assay with B. aborturs polysaccharide antigens, presented a greater specificity but lower sensitivity for detecting brucellosis infected animals as compared to the conventional methods of antibody detection.

J. Megid

1999-10-01

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Evaluación de la eficacia de la prueba de inmunodifusión en gel agar para la detección de anticuerpos contra el virus de la leucosis enzootica bovina / Assessment of the Efficacy of the Agar Gel Immunodiffusion Test for the Detection of Antibodies Against the Enzootic Bovine Leukosis Virus  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish contra el virus de la leucosis enzoótica bovina (VLEB), comparándola con el ensayo inmunoenzimático (ELISA). Se procesaron 360 muestras de suero bovino para ambas pruebas, siguiendo las indicaciones del fabricante. El grado de concordancia (GC), valores predictivos (VP) y razones de verosimilitud (R [...] V) fueron determinados y analizados. El GC entre ambas pruebas resultó ser del 86,4%, con un coeficiente Kappa (K) = 0,7. La IDGA detectó una significativa (P Abstract in english The efficacy of the agar gel immunodifusion test (AGID) for the detection of antibodies against the enzootic bovine leucosis virus (EBLV) was evaluated and compared with the ELISA test. A total of 360 bovine serum samples were tested for both tests, following the manufacturer instructions. The agree [...] ment degree (AD), predictive values (PV), and coefficient of probability (CP) were determined and analyzed. There was a good AD between both tests (86.4%; Kappa coefficient =0.7). The AGID test detected a significant (P

Zoraida, Nava; César, Obando; Magaly, Bracamonte; Aurico, Sousa; Mayra, Hidalgo.

2012-06-01

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Diagnostic efficiency of Brucella soluble antigens in immunodiffusion tests and ability to differentiate Brucella abortus strain 19 vaccinated cattle / Eficiência diagnóstica de antígenos solúveis de Brucella em testes de imunodifusão e capacidade para diferenciar bovinos vacinados com Brucella abortus CEPA 19  

Scientific Electronic Library Online (English)

Full Text Available Foram comparados três antígenos solúveis: um hapteno nativo (NH) de B. melitensis 16M, um polissacarídeo (PS) obtido de B. abortus 1119-3 e outro polissacarídeo de cadeia O (O-Chain) originado também da última Brucella. Os testes de imunodifusão radial (RID) e imunodifusão em gel de ágar (AGID) fora [...] m confrontados com as três classes de soros bovinos: a) infectados naturalmente (n = 76), b) não infectados (n = 130) e c) vacinados com B19 (n = 61) reagindo a testes sorológicos clássicos. Foram determinadas a sensibilidade (Se), a especificidade (Sp) e a capacidade para discriminar vacinados (ADV). A Se mais alta (84,3%) no teste RID foi demonstrada pelo antígeno NH, enquanto os três antígenos tiveram 100% de Sp. O antígeno O-Chain teve 100% de ADV nesse teste. O teste AGID com estes antígenos demonstrou 100% Sp e ADV, enquanto o antígeno PS mostrou uma melhor Se (86,6%). Finalmente, por sua qualidade de produção e eficiência, os antígenos PS e NH representam uma alternativa segura e econômica para o diagnóstico suplementar da brucelose. Abstract in english Three soluble antigens were compared by radial immunodiffusion (RID) and agar gel immunodiffusion (AGID) tests: a native haptene (NH) from Brucella melitensis 16M, and a polysaccharide (PS) from B. abortus 1119-3, both obtained by non-hydrolytic methods, and the (O-Chain) polysaccharide extracted al [...] so from B. abortus 1119-3 but using an hydrolytic method. Three groups of bovine sera were tested: a) Naturally infected (n = 76); b) Non-infected (n = 130) and c) S-19 vaccinated (n = 61); the sensitivity (Se), the specificity (Sp) and the ability to differentiate vaccinated (ADV) were determined in each group a, b and c respectively. The highest Se in the RID test (84.3%) was achieved by NH; while the three antigens gave 100% Sp. The O-Chain showed 100% ADV in this test. In the AGID test PS antigen showed the best Se (86.6%), and all antigens showed 100% of Sp and ADV. Finally, for its production qualities and efficiency the antigens PS and NH represent a promising alternative for complementary diagnosis of brucellosis.

José, DAFFNER; Pedro, ABALOS; Lautaro, PINOCHET; Mariela, SCORTTI; Santiago, URCELAY.

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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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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  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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. Abstract in english 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 favo [...] rs 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.

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.

1441-14-01

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21 CFR 866.4800 - Radial immunodiffusion plate.  

Science.gov (United States)

...2010-04-01 2010-04-01 false Radial immunodiffusion plate. 866.4800 Section 866.4800 Food and Drugs...and Reagents § 866.4800 Radial immunodiffusion plate. (a) Identification. A radial immunodiffusion plate...

2010-04-01

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9 CFR 147.9 - Standard test procedures for avian influenza.  

Science.gov (United States)

... Standard test procedures for avian influenza. 147.9 Section 147.9... Standard test procedures for avian influenza. (a) The agar gel immunodiffusion...A-6877 or equivalent). (iii) Avian influenza AGID antigen and positive...

2010-01-01

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A comparison of two agar gel immunodiffusion methods and a complement fixation test for serologic diagnosis of Brucella ovis infection in experimentally infected rams / Comparação entre dois métodos de imunodifusão em gel de Agar e um método de fixação de complemento para o diagnóstico sorológico da infecção por Brucella ovis em carneiros experimentalmente infectados  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A infecção por Brucella ovis é considerada uma das principais causas de epididimite e infertilidade em carneiros, resultando em falhas reprodutivas e perdas econômicas significativas em rebanhos ovinos ao redor do mundo. O estudo teve o objetivo de avaliar três testes sorológicos disponíveis para o [...] diagnóstico da brucelose ovina por B. ovis, utilizando 181 soros ovinos. Amostras de soro provenientes de carneiros experimentalmente infectados foram coletadas ao longo de 192 dias pós-infecção (n=117) e durante o período pré-infecção (n=9). Adicionalmente, amostras de soro foram obtidas de ovinos provenientes de um rebanho livre para B. ovis (n=55). As técnicas de imunodifusão em gel de agar (IDGA), utilizando dois antígenos disponíveis comercialmente, e de fixação de complemento foram comparadas (FC). Foram obtidos resultados de sensibilidade especificidade semelhantes para ambos os métodos de IDGA e ainda, a técnica de IDGA foi mais eficiente do que a da FC para o diagnóstico sorológico da infecção por B. ovis. Abstract in english [...

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Immunodiffusion test for diagnosis and monitoring of human pythiosis insidiosi.  

Science.gov (United States)

To facilitate the laboratory diagnosis of human cases of pythiosis insidiosi, an immunological test was evaluated. A soluble antigen was prepared from a human isolate of Pythium insidiosum, an aquatic, thermotolerant oomycete that causes infections in cattle, dogs, horses, and humans. Sera from seven proven cases of disseminated human pythiosis insidiosi were tested in an immunodiffusion test along with appropriate control sera from patients with a variety of actinomycotic, bacterial, and mycotic diseases as well as sera from uninfected individuals. Titers ranged from 1:1 to 1:32 in the seven serum samples from the disseminated cases of pythiosis insidiosi of varying severity. The heterologous sera gave negative reactions. The rapidity and specificity of the immunodiffusion test makes it a useful diagnostic tool for the serodiagnosis of P. insidiosum infections. PMID:1774283

Pracharktam, R; Changtrakool, P; Sathapatayavongs, B; Jayanetra, P; Ajello, L

1991-01-01

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Immunodiffusion test for diagnosing and monitoring pythiosis in horses.  

Science.gov (United States)

A practical, sensitive, and specific immunodiffusion test was developed for diagnosing and monitoring pythiosis in horses. Culture filtrates, a soluble cell mass, and trypsinized Pythium sp. antigens were evaluated against prepared rabbit anti-Pythium sp. serum and pythiosis horse case sera. The culture filtrate antigens demonstrated the greatest capacity for detecting precipitins and the greatest stability during storage. In contrast, the trypsinized antigens had the weakest capability for detecting multiple precipitins and the poorest stability. The 13 sera from horses with proven active pythiosis were positive in immunodiffusion tests with the culture filtrate antigens. Each serum contained from three to six precipitins. Treated horses lost precipitins, and some became antibody negative. No false-positive reactions were noted in tests with sera from normal horses and humans or with sera from a variety of heterologous horse and human infections. Images PMID:3086368

Mendoza, L; Kaufman, L; Standard, P G

1986-01-01

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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  

OpenAIRE

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...

Madelayne Cortez-Moreira; Oelemann, Walter M. R.; Walter Lilenbaum

2005-01-01

24

Bluetongue virus: comparative evaluation of enzyme-linked immunosorbent assay, immunodiffusion, and serum neutralization for detection of viral antibodies.  

OpenAIRE

Comparative studies on the detection of bovine serum immunoglobulin G antibodies to bluetongue virus with an enzyme-linked immunosorbent assay, an immunodiffusion method, and a serum neutralization assay demonstrated complete concordance between the enzyme-linked immunosorbent assay and the serum neutralization assay results. However, the immunodiffusion method failed to detect bluetongue virus antibody in a substantial number of sera found to possess bluetongue virus immunoglobulin G with th...

Poli, G.; Stott, J.; Liu, Y. S.; Manning, J. S.

1982-01-01

25

Avaliação da nested PCR em comparação aos testes sorológicos IDGA e ELISA para o diagnóstico da anemia infecciosa equina / Evaluation of nested PCR compared with AGID and ELISA serological tests for equine infectious anemia diagnosis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Comparou-se a técnica nested PCR (nPCR) com os testes sorológicos IDGA e ELISA para o diagnóstico da anemia infecciosa equina. Amostras do DNA provenientes das células mononucleares do sangue periférico foram submetidas à amplificação do gene gag pela nPCR, que apresentou valores de sensibilidade e [...] especificidade relativas de 90% e 52,9%, respectivamente, em relação à IDGA, e valores de 85,7% e 49%, respectivamente, em relação ao ELISA. Considerando-se os fatores referentes às limitações de cada técnica, pode ser sugerido o uso da nPCR como teste de diagnóstico complementar para AIE em amostras brasileiras. Abstract in english The nested polymerase chain reaction (nPCR) technique was compared to AGID and ELISA serological tests for the diagnosis of Equine Infectious Anemia. DNA samples from the peripheral blood mononuclear cells were subjected to the amplification of the gag gene by nPCR, which showed relative sensibility [...] and specificity values of 90.0% and 52.9% respectively, compared to the AGID and values of 85.7% and 49.0%, respectively, as compared to ELISA. Considering the factors concerning the limitations of each technique, the use of nPCR can be suggested as a complementary diagnostic test for EIA in Brazilian samples.

E.M., Santos; P.M.C., Motta; M.B., Heinemann; R.C., Leite; J.K.P., Reis.

2011-04-01

26

Evaluation of standard reagents for radial-immunodiffusion assays. In vitro control of rabies vaccines  

Directory of Open Access Journals (Sweden)

Full Text Available The RID assay is one of the in vitro methods used for in-process control in the production of rabies vaccines for veterinary use. It has been shown to be very useful for determining antigen concentration in the final bulk product. The work presented in this paper, including the production and standardization of candidate standard reagents for use in the Radial Immunodiffusion Assay (RID was carried out at the Pan American Institute for Food Protection and Zoonoses (INPPAZ/PAHO/WHO. The study was completed with the cooperation of the Faculty of Veterinary Sciences, National University of La Plata (NULP, Argentina, where the validation of the proposed standards and the quality control of samples from 28 different batches of rabies vaccines produced with Pasteur strain rabies virus (PV in BHK cells were performed. The activity of the vaccines was determined by in vivo (NIH and in vitro (RIDassays. The results of the candidate reagents for the reagent standardization tests showed stability, sensitivity and reproducibility. The Relative Potency the 1.2 between the problem vaccines and the reference vaccine was estimated by variance and regression analysis. The results of our validation study show that the INPPAZ (PAHO/WHO is capable of producing and distributing the above-mentioned standard reagents, as well as of providing support for the incorporation of the RID technique (sensitive, rapid and inexpensive to the laboratories that manufacture rabies vaccines in Latin America and the Caribbean.

MICELI Graciela S.

2000-01-01

27

Evaluation of a Commercial Blocking Enzyme-Linked Immunosorbent Assay To Detect Avian Influenza Virus Antibodies in Multiple Experimentally Infected Avian Species?  

OpenAIRE

Wild birds of the orders Anseriformes and Charadriiformes are the natural reservoirs for avian influenza (AI) viruses. Traditionally, AI virus surveillance in wild birds has relied on virus identification strategies, including virus isolation and detection. To evaluate the accuracy of a commercial blocking enzyme-linked immunosorbent assay (bELISA) and the agar gel immunodiffusion (AGID) test for detection of antibodies in wild birds, which is indicative of AI virus infection, we tested 281 s...

Brown, Justin D.; Stallknecht, David E.; Berghaus, Roy D.; Luttrell, M. Page; Velek, Katherine; Kistler, Whitney; Costa, Taiana; Yabsley, Michael J.; Swayne, David

2009-01-01

28

Prevalência da infecção por lentivírus de pequenos ruminantes em caprinos em Teresina, Piauí Prevalence of small ruminants lentiviruses infection in goats from Teresina, Piauí, Brazil  

OpenAIRE

The prevalence of anti-lentiviruses antibodies of small ruminants was investigated in goat herds in the city of Teresina, PI, Brazil. A seroepidemiological survey was conducted involving 480 animals, apparently healthy, belonging to six rural properties. The diagnostic test was the agar gel immunodiffusion (AGID), using antigens produced from cellular cultures infected with caprine arthritis encephalitis virus (CAEV Cork). Prevalences by gender and age were estimated considering sampling frac...

Sampaio Ju?nior, A.; Batista, M. C. S.; Cruz, M. S. P.; Silva, R. A. B.; Bona Nascimento, C.; Werneck, G. L.

2011-01-01

29

Improved methods for the fluorographic detection of weak ?-emitting radioisotopes in agarose and acrylamide gel electrophoresis media  

International Nuclear Information System (INIS)

The use of acetic acid as a solvent for diphenyloxazole (PPO) in fluorographic procedures has been investigated. It is demonstrated to be superior to both dimethyl sulfoxide and methanol with respect to its suitability in both agarose and acrylamide gel electrophoresis systems. In addition, a method has been developed for impregnating fragile gels such as those used for immunodiffusion with PPO in preparation for fluorography. (Auth.)

30

Measurement of serum immunoglobulin concentration in killer whales and sea otters by radial immunodiffusion.  

Science.gov (United States)

Killer whales and sea otters maintained in captivity are the subjects of routine health monitoring programs, and interest in immunologic studies in sea otters has been rising recently in response to potential impacts from infectious disease and environmental pollution on the threatened southern sea otter population. Development of species-specific reagents for immunologic studies in these two marine mammals is currently in its infancy. In this study, killer whale and sea otter immunoglobulin-specific polyclonal antibodies were generated, and used to develop tests for serum Ig concentration in the killer whale (Orcinus orca) and the southern (Enhydra lutris nereis) and northern sea otter (Enhydra lutris lutris). Killer whale serum IgG was purified using caprylic acid/ammonium sulfate precipitation. Sea otter plasma IgG was purified using protein-A-agarose. Polyclonal anti-Ig antisera were produced in rabbits, and specificity confirmed by immunoelectrophoresis. Radial immunodiffusion was used to measure Ig concentration in serum or plasma samples derived from 21 captive killer whales, 18 wild and 4 captive southern sea otters and 15 wild and 4 captive northern sea otters grouped by age. Mean killer whale serum Ig concentration (+/-95% confidence interval) ranged from 15.04 +/- 3.97 g/l for animals aged 0-5 years to 26.65 +/- 9.8 g/l for animals aged >10 years. Mean sea otter serum Ig concentration (+/-95% confidence interval) ranged from 28.39 +/- 11.00 g/l for southern sub-adults to 32.76 +/- 11.58 g/l for southern adults. No significant difference in serum Ig concentration was found between southern and northern sea otters. Serum Ig concentrations in two northern sea otter pups were low compared to those of adult sea otters. The two serum Ig quantitation assays produced were highly specific and reproducible and will be useful additions to the limited number of tests available for immune function in these marine mammal species. PMID:12383650

Taylor, Bernadette C; Brotheridge, Rory M; Jessup, David A; Stott, Jeffrey L

2002-10-28

31

Designation of 15 serovars of Haemophilus parasuis on the basis of immunodiffusion using heat-stable antigen extracts.  

OpenAIRE

Previous independent investigations of the serotyping of Haemophilus parasuis strains have led to the designation of serovars A to D, 1 to 7, Jena 6 to Jena 12, and ND1 to ND5. Heat-stable antigen preparations from the reference strains for these serovars were tested by immunodiffusion with rabbit hyperimmune antisera. The existence of 15 distinct serologic groups was apparent, for which we propose the designations serovars 1 to 15. Examination of 290 field isolates from swine in the former G...

Kielstein, P.; Rapp-gabrielson, V. J.

1992-01-01

32

Ocorrência de anticorpos anti-Brucella abortus e anti-Brucella canis em cães rurais e urbanos do Município de Monte Negro, Rondônia, Brasil / Anti-Brucella abortus and anti-Brucella canis antibodies occurrence in rural and urban dogs from Monte Negro county, Rondônia, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Foram avaliados 304 cães de ambiente rural e urbano do município de Monte Negro, Rondônia, através do Antígeno Acidificado Tamponado (AAT), Soroaglutinação Lenta em Tubos (SAL) e 2-Mercaptoetanol (2-ME) para a pesquisa de anticorpos anti-Brucella abortus e da Imunodifusão em gel de ágar (IDGA) e Imu [...] nodifusão em gel de ágar com soro tratado com 2-Mercaptoetanol (IDGA-ME) para Brucella canis. Foram consideradas positivas as amostras reagentes nas provas confirmatórias do 2-ME e IDGA-ME. Verificaram-se 56 (18,4%) animais reagentes ao AAT e 12 (4,0%) reagentes a SAL. Apenas um cão (0,3%) foi considerado positivo, confirmado pela prova do 2-ME. Foram observadas 11 (3,6%) reações á IDGA, porém não houve confirmação na prova do IDGA-ME. Ressalta-se a baixa ocorrência de cães positivos ao 2-ME e a ausência de animais reagentes á IDGA-ME. Abstract in english Serum samples from 304 dogs living in urban or rural areas of Monte Negro County, Rondônia State, Brazil, were evaluated for Brucella abortus reactivity using the Rose-Bengal Test (RBT), Standard Tube agglutination Test (SAT), and Mercaptoethanol Test (MET), and for Brucella canis reactivity using t [...] he Immunodiffusion test (AGID) and Immunodiffusion test with 2-Mercaptoethanol (ME-AGID). Serum was considered positive if reacted in the MET or ME-AGID. Fifty-six (18.4%) dogs reacted by the RBT, and 12 (4.0%) by the SAT. One (0.3%) dog was positive by the MET. Eleven (3.6%) dogs reacted by the AGID, but with no confirmation by the ME-AGID. It the small occurrence of dogs reacting by the MET and the absence of reactivity by ME-AGID is emphasized.

Daniel Moura de, Aguiar; Guacyara Tenório, Cavalcante; Silvio Arruda, Vasconcellos; Jane, Megid; Vanessa Riesz, Salgado; Tais Fukuta, Cruz; Marcelo Bahia, Labruna; Adriano, Pinter; Jean Carlos Ramos da, Silva; Zenaide Maria, Moraes; Luís Marcelo Aranha, Camargo; Solange Maria, Gennari.

1216-12-01

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Serological diagnosis of brucellosis caused by Brucella canis.  

Science.gov (United States)

Blood serum samples from 2,328 dogs were tested to detect antibodies against Brucella canis with the agar gel immunodiffusion (AGID) and 2-mercaptoethanol slide agglutination test (ME-SAT) using Brucella ovis as the antigen. All blood serum samples were also evaluated for antibodies against Brucella abortus and Brucella melitensis using the Rose Bengal test. Twentyfive (1.07%) of the sera evaluated were considered positive with AGID test. Only 4 (16%) of these blood serum samples were positive when evaluated with ME-SAT. The 25 AGID positive samples and 25 AGID negative serum samples were also examined by: the complement fixation test (CFT) using B. ovis hot saline extract (HSE) as the antigen, indirect enzyme linked immunosorbent assay (ELISA) and immunoblotting (IB) using B. canis and B. ovis HSE antigens. Two positive canine sera from culture positive dogs and the serum of an experimentally RM6/66 B. canis-infected rabbit were employed as positive controls and one serum from a known uninfected dog as a negative control. ELISA with B. canis antigen gave 9 (18%) positive results (6 AGID-positive and 3 AGID-negative sera). ELISA performed with B. ovis antigen detected 15 (30%) positive samples (10 AGID-positive, 5 AGID-negative and 8 B. canis ELISA positive sera). IB analysis of known positive controls sera employing B. canis antigen detected bands with molecular weights of 94-80, 64-50, 35, 32-30, 28, 23, 20-18, 15-12 kDa. The same sera tested with B. ovis antigen revealed bands of 35, 32-30, 25, 23, 20-18, 15-12 kDa. No bands were observed with the negative control serum and the 50 canine tested sera. PMID:12578313

Ebani, V V; Cerri, D; Fratini, F; Bey, R F; Andreani, E

2003-01-01

34

GEL PROCESSING  

OpenAIRE

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

35

Quantitation of IgE by means of a modified radial immunodiffusion method in comparison with the radioimmunosorbent test (RIST)  

International Nuclear Information System (INIS)

Serum IgE were quantitied by means of modified radial immunodiffusion technique (RID). To improve visibility of precipitin bands a staining procedure with DOPA was applied. Pretreatment of sera with dextransulfate proved necessary in order to avoid unspecific ringformation in the agargel. In comparison with the RIST it turned out that sera containing less than 500 I.U. IgE/ml did not produce precipitin bands with this method. Sera containing 500-999 I.U. IgE/ml occasionally exhibited positive results with the RID technique, whereas sera with more than 1,000 I.U./ml were regulary positive. In its present form the RID may be used as screening method for sera with higher IgE levels. Within the above mentioned limits the IgE levels calculated by means of the RID-test roughly corresponded the values determined by the RIST. (orig.)

36

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

37

Evaluation of a competitive ELISA for detection of antibodies against avian influenza virus nucleoprotein.  

Science.gov (United States)

A competitive enzyme-linked immunosorbent assay (C-ELISA) employing a baculovirus-expressed recombinant nucleoprotein and a monoclonal antibody was developed for the detection of antibodies to type A influenza virus nucleoprotein. The performance of the C-ELISA was evaluated by testing 756 chickens, 1123 turkeys, 707 emus, and 1261 ostriches, for a total of 3847 serum samples. Relative to the agar gel immunodiffusion (AGID) test, the C-ELISA had a sensitivity of 100% for all four species. The C-ELISA's sensitivity relative to the hemagglutination-inhibition (HI) test results was 100% for chicken, turkey, and emu and 96.2% for the ostrich serum samples. More than 90% of the AGID-negative/C-ELISA-positive serum samples were found positive by HI for at least one influenza serotype. The specificity of C-ELISA relative to AGID ranged from 85.5% to 99.8% for sera collected from these species. These results indicated that the C-ELISA was more sensitive and more specific than the AGID test and as sensitive and as specific as the HI test. The C-ELISA has the potential to replace the AGID test for screening sera from avian species, including ratites, for detection of antibodies to type A influenza virus. PMID:9777152

Zhou, E M; Chan, M; Heckert, R A; Riva, J; Cantin, M F

1998-01-01

38

Performance comparison of immunodiffusion, enzyme-linked immunosorbent assay, immunochromatography and hemagglutination for serodiagnosis of human pythiosis.  

Science.gov (United States)

Pythiosis is a life-threatening infectious disease caused by the fungus-like organism Pythium insidiosum. Morbidity and mortality rates of pythiosis are high. The treatment of choice for pythiosis is surgical debridement of infected tissue. Early and accurate diagnosis is critical for effective treatment. In-house serodiagnostic tests, including immunodiffusion (ID), enzyme-linked immunosorbent assay (ELISA), immunochromatography (ICT) and hemagglutination (HA) have been developed to detect antibodies against P. insidiosum in sera. This study compares the diagnostic performance of ID, ELISA, ICT, and HA, using sera from 37 pythiosis patients and 248 control subjects. ICT and ELISA showed optimal diagnostic performance (100% sensitivity, specificity, positive predictive value and negative predictive value). ICT was both rapid and user-friendly. ELISA results were readily quantitated. ID is relatively insensitive. HA was rapid, but diagnostic performance was poor. Understanding the advantages offered by each assay facilitates selection of an assay that is circumstance-appropriate. This will promote earlier diagnoses and improved outcomes for patients with pythiosis. PMID:23537786

Chareonsirisuthigul, Takol; Khositnithikul, Rommanee; Intaramat, Akarin; Inkomlue, Ruchuros; Sriwanichrak, Kanchana; Piromsontikorn, Savittree; Kitiwanwanich, Sureewan; Lowhnoo, Tassanee; Yingyong, Wanta; Chaiprasert, Angkana; Banyong, Ramrada; Ratanabanangkoon, Kavi; Brandhorst, Tristan T; Krajaejun, Theerapong

2013-05-01

39

Gel Electrophoresis  

Science.gov (United States)

In the early days of DNA manipulation, DNA fragments were laboriously separated by gravity. In the 1970s, the powerful tool of DNA gel electrophoresis was developed. This process uses electricity to separate DNA fragments by size as they migrate through a gel matrix. This animation from Cold Spring Harbor Laboratory's Dolan DNA Learning Center presents Gel Electrophoresis through a series of illustrations of the processes involved.

40

Polyelectrolyte gels  

Energy Technology Data Exchange (ETDEWEB)

Polyelectrolyte (PE) gels are swollen polymer/solvent networks that undergo a reversible volume collapse/expansion through various types of stimulation. Applications that could exploit this large deformation and solvent expulsion/absorption characteristics include robotic {open_quotes}fingers{close_quotes} and drug delivery systems. The goals of the research were to first explore the feasibility of using the PE gels as {open_quotes}smart materials{close_quotes} - materials whose response can be controlled by an external stimulus through a feedback mechanism. Then develop a predictive capability to simulate the dynamic behavior of these gels. This involved experimentally characterizing the response of well-characterized gels to an applied electric field and other stimuli to develop an understanding of the underlying mechanisms which cause the volume collapse. Lastly, the numerical analysis tool was used to simulate various potential engineering devices based on PE gels. This report discusses the pursuit of those goals through experimental and computational means.

Segalman, D.J.; Witkowski, W.R.

1995-06-01

41

Brucella canis infection in dogs attended in veterinary clinics from patos, Paraíba state, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english To determine the frequency of anti-Brucella canis antibodies in dogs attended in veterinary clinics from Patos, Paraíba State, Brazil, as well as to identify risk factors and to isolate and identify the agent, 193 dogs were used. Agar gel immunodiffusion test (AGID) was used to detect B. canis antib [...] odies in sera. Isolation of B. canis was carried out in blood and bone marrow from seropositive animals. Six animals tested seropositive in AGID, resulting in a frequency of 3.11%. B. canis was isolated from bone marrow of one seropositive animal, with confirmation by PCR. Lack of cleaning of the dog's environment was identified as risk factor (odds ratio = 7.91). This is the first report of isolation of B. canis in dogs from the Northeast region of Brazil.

Annielle Regina Fonseca, Fernandes; Sérgio Santos de, Azevedo; Rosa Maria, Piatti; Eliana Scarcelli, Pinheiro; Margareth Élide, Genovez; Adílio Santos de, Azevedo; Carolina de Sousa Américo, Batista; Clebert José, Alves.

1405-14-01

42

Brucella canis infection in dogs attended in veterinary clinics from patos, Paraíba state, Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available To determine the frequency of anti-Brucella canis antibodies in dogs attended in veterinary clinics from Patos, Paraíba State, Brazil, as well as to identify risk factors and to isolate and identify the agent, 193 dogs were used. Agar gel immunodiffusion test (AGID was used to detect B. canis antibodies in sera. Isolation of B. canis was carried out in blood and bone marrow from seropositive animals. Six animals tested seropositive in AGID, resulting in a frequency of 3.11%. B. canis was isolated from bone marrow of one seropositive animal, with confirmation by PCR. Lack of cleaning of the dog's environment was identified as risk factor (odds ratio = 7.91. This is the first report of isolation of B. canis in dogs from the Northeast region of Brazil.

Annielle Regina Fonseca Fernandes

2011-12-01

43

Development and validation of a competitive enzyme-linked immunosorbent assay for detection of type A influenza antibodies in avian sera.  

Science.gov (United States)

Serologic screening of avian sera for group-specific antibodies to type A influenza is currently accomplished by using the avian influenza (AI) agar gel immunodiffusion (AGID) test. A competitive enzyme-linked immunosorbent assay (CELISA) was developed using a baculovirus vector, Autographa californica nuclear polyhedrosis virus, expressing the nucleoprotein (NP) gene of A/Ann Arbor/6/60 influenza virus. The recombinant NP was obtained by inoculation of Spodoptera frugiperda (Sf9) insect cells or Trichoplusia ni insect larvae with the recombinant baculovirus. A hybridoma cell line producing monoclonal antibody against influenza virus A nucleoprotein was used to generate mouse ascitic fluid for the CELISA. The nucleoprotein and the monoclonal antibody were used without further purification in a CELISA for detection of avian-origin serum antibodies to type A influenza. The AI AGID and CELISA tests were compared for sensitivity and specificity using 1651 experimental and reference antisera. Samples discrepant in AGID and CELISA test results were further evaluated by the AI indirect fluorescent antibody (IFA), hemagglutination-inhibition (HI), and neuraminidase-inhibition (NI) tests. The results demonstrated a high degree of correlation between the AGID and CELISA test results, with the IFA, HI, and NI tests offering additional support of CELISA test specificity. The CELISA is a rapid, economical, sensitive, and specific serodiagnostic method for screening large numbers of avian sera for antibodies to avian influenza virus. PMID:9533078

Shafer, A L; Katz, J B; Eernisse, K A

1998-01-01

44

Preliminary study of an immunochromatography test for serological diagnosis of canine brucellosis.  

Science.gov (United States)

The most widely used screening test for the diagnosis of brucellosis in the dog is the rapid slide agglutination test in the presence of 2-mercaptoethanol (2ME-RSAT). The diagnosis is partially confirmed by the agar gel immunodiffusion test (AGID) and definitively confirmed by bacteriological isolation. Some chronic cases not detected by these tests may be detected by ELISA tests. The use of 2ME-RSAT in routine clinical practice requires a microscope and an experienced operator. An immunochromatographic diagnostic test for canine brucellosis (FASTest(®) Brucella c., Megacor, Hörbranz, Austria) has been recently released. In this study, we compared the diagnostic performance of the FASTest with those of 2ME-RSAT, AGID and ELISAs. Sera from 17 healthy dogs used as negative controls yielded negative results by FASTest, indicating a 100% specificity in this sample. Among 27 sera of dogs with acute or subacute brucellosis confirmed by B. canis isolation, all of which were positive by RSAT and ELISAs, the FASTest was positive in 24 cases and AGID in 23. In acute and subacute cases, the sensitivity of FASTest was 89%. Sera from six dogs with bacteriologically confirmed chronic brucellosis, which were positive by ELISAs but negative by 2ME-RSAT, were also tested; 1 was positive by FASTest and 4 were positive by AGID. These preliminary results indicate a good specificity of the FASTest (100% in this sample) but an unacceptable sensitivity as a screening test. In cases with chronic brucellosis, the sensitivity of the FASTest was lower than that of ELISAs but this assay could make a good intermediate test to be run after a positive RSAT and before running an AGID. PMID:23279541

Wanke, M M; Cairó, F; Rossano, M; Laiño, M; Baldi, P C; Monachesi, N E; Comercio, E A; Vivot, M M

2012-12-01

45

Detection of rubella-specific serum IgG and IgA and nasopharyngeal IgA responses using a radioactive single radial immunodiffusion technique  

International Nuclear Information System (INIS)

A radioactive, single radial immunodiffusion technique (RSRID) employing 125I-labelled antiglobulins, was developed to determine rubella-specific serum IgG and IgA and nasopharyngeal IgA antibody responses following both naturally acquired rubella and vaccination with four attenuated vaccines. Rubella-specific IgG antibodies developed in parallel with haemagglutination inhibiting (HAI) antibodies and both persisted for at least a year in all cases of naturally acquired and vaccine induced infection. However, the RSRID test detected rises in titre in all of five volunteers challenged intranasally with RA27/3, whereas only one volunteer showed a rise by HAI. Serum IgA antibodies generally persisted for at least a year following naturally acquired infection but rubella vaccines induced variable responses. Thus, following administration of RA27/3 and To-336 vaccines, rubella-specific IgA usually persisted for a year, whereas Cendehill vaccine failed to induce a detectable response. Rubella-specific nasopharyngeal IgA was detected in all five patients following naturally acquired infection and was still present in the only two patients tested a year after infection. These antibodies were detected in fourteen of twenty-three vaccinees at 3 weeks, but persisted for a year in only two vaccinees, both of whom were given RA27/3 intranasally. (author)

46

The feasibility of using antigens prepared with rough Brucella strains for diagnosis of canine brucellosis.  

Science.gov (United States)

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. PMID:20461292

Escobar, G I; Boeri, E J; Ayala, S M; Lucero, N E

2010-01-01

47

Running an Agarose Gel  

Science.gov (United States)

This video adapted from the University of Leicester provides step-by-step instructions for loading samples into an agarose gel and then running the gel to separate DNA molecules according to their size.

WGBH Educational Foundation

2011-11-07

48

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

49

BLUETONGUE VIRUS ANTIBODIES DETECTIONS IN SHEEP FROM ARAÇATUBA REGION –SAO PAULO, BRAZIL DETECÇÃO DE ANTICORPOS CONTRA O VÍRUS DA LÍNGUA AZUL EM OVINOS NA REGIÃO DE ARAÇATUBA – SÃO PAULO, BRASIL  

Directory of Open Access Journals (Sweden)

Full Text Available

Bluetongue (BT is an infectious, insect-born viral disease of ruminants. The causative agent of BT is bluetongue virus (BTV that belongs to the family Reoviridae genus Orbivirus. Insect vectors in the genus Culicoides transmit this virus. BT affects domestic and wild ruminants, however small ruminants are considered the most affected specie. The aim of the study was to detect antibodies against BTV in commercial sheep farms, of the Northeastern region of Sao Paulo State, Brazil. A total of 1002 sera samples collected from adult sheep (above 1 year-old, comprising a total of 31 farms, were screened for the presence of BTV antibodies, by agar gel immunodiffusion test (AGID and ELISA-CFS (Enzyme Linked Immunosorbent Assay – competitive solid phase, both produced by Pan American Center of FMDV. From a total of 1002 samples, 651 (65% were positive by AGID and 742 (74.1%, were positive by ELISA-CFS. These results suggest that the BTV is widespread among farms, probably causing subclinical infections.

KEY WORDS: AGID, bluetongue virus, ELISA-CFS, seroepidemiological survey.

A língua azul é uma doença viral, cujo agente etiológico pertence à família Reoviridae, gênero Orbivirus, transmitida por um vetor (artrópode hematófago, do gênero Culicoides. Os animais acometidos são ruminantes domésticos e selvagens, porém os pequenos ruminantes são os mais afetados. O estudo teve como objetivo detectar a presença de anticorpos para língua azul em ovinos da região de Araçatuba, por possuir um rebanho expressivo e condições climáticas favoráveis à multiplicação de insetos. Foram analisadas 1.002 amostras de soros ovinos, provenientes de 31 cabanhas, pelas provas de imunodifusão dupla em gel de ágar (AGID e ELISA (Enzyme Linked immunosorbent Assay de competição da fase sólida (ELISA CFS, provenientes do Centro Panamericano de Febre Aftosa. Desses soros, 651 (65% foram reagentes ao vírus da língua azul, pela técnica de AGID, e 742 (74,1% ao teste de ELISA–CFS. Esses resultados sugerem que o vírus da língua azul encontra-se disseminado nessas regiões, ocasionando infecções inaparentes. 

PALAVRAS-CHAVES: AGID, ELISA, inquérito soroepidemiológico, vírus da língua azul.

Adriana Hellmeister de Campos Nogueira

2009-12-01

50

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  

Scientific Electronic Library Online (English)

Full Text Available 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 compo [...] nentes 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. Abstract in english 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 prefer [...] red 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.

G. I., Escobar; E. J., Boeri; S. M., Ayala; N. E., Lucero.

2010-02-01

51

Use of Brucella canis antigen for detection of ovine serum antibodies against Brucella ovis.  

Science.gov (United States)

Brucella ovis causes a genital disease of sheep manifested by epididymitis in rams and placentitis in ewes producing reduced fertility in the flock. Clinical diagnosis is not sensitive enough and bacteriological testing is not feasible for detection of the disease in large numbers of animals. Indirect methods of serological testing are preferred for routine diagnosis, of which agar gel immunodiffusion (AGID), complement fixation (CF) and ELISA tests are recommended as the most efficient. Since B. ovis shares antigenic components with Brucella canis, it would seem that either strain could be used as antigen with the same results; however, the advantage of the B. canis (M-) strain variant is that it can be used to develop a satisfactory antigen for agglutination tests. We present data on AGID and IELISA tests using B. ovis antigen and rapid screening agglutination test (RSAT), 2-mercapto-ethanol RSAT (2ME-RSAT) and IELISA using B. canis antigen. We tested 225 animals. The cut-off values were adjusted by ROC analysis using 51 negative and 32 positive sera; the IELISA-B. canis cut-off value was 39 (%P) and IELISA-B. ovis, 51 (%P), with 100% sensitivity and specificity. Of the 32 positive sera from the infected flock RSAT detected 32 (100%), 2ME-RSAT 29 (91%) and AGID 31 (97%). Of the 142 sera from suspicious flocks, 46 were negative and 56 positive in all the tests; 16 were positive by RSAT, IELISA-B. canis and IELISA-B. ovis, 20 positive only with RSAT and 2 positive only by both IELISAs. RSAT is a very sensitive screening test that, because of its simplicity and easy interpretation, following a study in larger sample, could replace AGID as a screening test for diagnosis of ovine brucellosis caused by B. ovis. The IELISA-B. canis or IELISA-B. ovis could be used as confirmatory tests, since they show equal specificity and sensitivity. PMID:15708814

López, G; Ayala, S M; Escobar, G I; Lucero, N E

2005-02-25

52

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

53

Functional molecular gels  

CERN Document Server

There is much recent interest in the field of molecular gels because of their potential use in many different applications including biomedicine and electronic materials. Functional Molecular Gels details the latest research on molecular gels from the fundamentals of molecular gel formation to their uses in a variety of fields. The book introduces the key concepts of designing molecular gels and their characterization techniques, followed by chapters discussing different stimuli responsive systems. Specific chapters are then dedicated to the diverse range of applications including catalysis, tissue engineering, photonic materials and as templates for nanostructured materials. Written by active researchers in the area, this book gives a taste of the possibilities that molecular gels offer for those both new to and already working in the area.

Miravet, Juan F

2013-01-01

54

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

55

Surfactant Templated Polyacrylamide Gels  

Science.gov (United States)

The controlled modification of gel structure by using surfactant self-assemblies as templates provides new opportunities in the development of novel materials. Polyacrylamide gels were synthesized in the presence of tetradecyltrimethylammonium bromide (TTAB) surfactant. Small-angle X-ray scattering (SAXS) results indicate that acrylamide monomer does not prevent the self-assembly of TTAB surfactants. Dynamic rheology measurements indicated a transition from an isotropic micellar phase to a hexagonal columnar phase occurred about 10% higher TTAB concentration in the presence of acrylamide (the transition occurs at 35% (by weight) for TTAB in buffer solution). The presence of surfactant during the gelation profoundly affected the final gel structure. Real time rheology measurements showed evidence of a demixing of the polymer and the surfactant phase in gels formed in the presence of high TTAB concentration (> 30% by weight) leading to the formation of highly macroporous gels. Bulk structure characterization using SAXS showed that TTAB micelles were separated by about 10 nm in gels synthesized in the presence of low and moderate TTAB concentration (Protein separation on gels templated by TTAB surfactants showed significant improvements over conventional gels.

Chakrapani, Mukundan; van Winkle, D. H.; Rill, R. L.

2003-03-01

56

Agarose Gel Demos  

Science.gov (United States)

This video, presented by WGBH, is a great overview of how to prepare Agarose gel for electrophoresis. The video goes in-depth with the finer points including how to insert the pipette as to not disturb the gel and get the best results. This video would be useful for anyone in biochemistry or molecular biology fields. This video would also be helpful for instructors looking to provide their students with an overview on how to prepare Agarose gel. Educators will also find a background essay, discussion questions, and standards alignment for the material.

57

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  

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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

58

Electrophoresis and Gel Analysis  

Science.gov (United States)

In this animation produced by WGBH and Digizyme, Inc., see how molecules of DNA are separated using gel electrophoresis, and how this process enables scientists to compare the molecular variations of two or more DNA samples.

WGBH Educational Foundation

2011-09-22

59

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

60

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

61

Leaching of ?-doped gels  

International Nuclear Information System (INIS)

Full text of publication follows: ?-doped (Np, Pu, Am) SON68 glasses have been completely altered under hydrothermal conditions at 300 deg. C to form gels. These gels then have been leached at 50 deg. C under static mode, 44 cm-1 and under oxidizing (Eh/HNE ? +0.15 V) and reducing (Eh/HNE ? -0.25 V, obtained by hydrogenated argon bubbling in the reactor) conditions during one year. The goal of these experiments was to study the actinides release in solution during gels leaching and to determine what mechanism controlled this release at long term. SEM observations of gels showed that there were secondary phases made of needles and sheets with the amorphous gel grains. The XRD patterns indicated that the gels were mainly amorphous with crystallized phases (sodium and calcium alumino-silicates: analcime, albite). The pH values of the leachates decreased versus time from 1 day to 3 months and after they were constant. This decrease of the pH values was due to an increase of dissolved CO2 in the leachates, resulting from samplings for solutions analysis. The pH values obtained during the Am-doped gel leaching were lower of about 0.5 pH unit compared to those observed with Np- and Pu-doped gels. This phenomenon was due to ? radiolysis of the N2- O2-H2O system leading to HNO3 formation. The Am-doped gel dissolution rate, calculated with regard to silicon, was 2 to 3 times higher thasilicon, was 2 to 3 times higher than those measured for Np- and Pu-doped gels, whatever the oxidation-reduction potential of the leachates. The three alkali metals had not the same behavior during gels leaching and the following relation was found: r(Li) ? 2 r(Na), r(Na) ? 2 r(Cs) and r(Cs) ? r(Si). In fact, alkali metals were preferentially included in crystallized phases, except Cs that was partially trapped in the amorphous silicated gel; this could explain the different behavior between cesium and the other alkali metals. The actinides in solution were found very mainly in colloidal form and the fraction > 0.45 ?m represented more than 50% of the released actinides. The soluble neptunium concentrations were about 3 10-7 and 5 10-8 mol.L-1 under oxidizing and reducing conditions and the colloidal fraction increased under reducing medium, in relation with the presence of Np(V) and Np(IV) for respectively oxidizing and reducing media. The plutonium concentrations were about 4 10-9 and 10-9 mol.L-1 under oxidizing and reducing conditions and Pu(IV) prevailed in both media. The plutonium colloidal fraction did not vary according to the Eh value. Americium had the same behavior than plutonium under reducing conditions and its solubility was about 10-9 mol.L-1. Solubility calculations showed that no simple phases (hydroxide, carbonate) controlled the actinides concentrations in solution. (authors)

62

Gel Electrophoresis of Dyes  

Science.gov (United States)

In this experiment related to plant biotechnology, learners discover how to prepare and load an electrophoresis gel. They will then run the gels in an electrophoresis system to separate several dyes that are of different molecular sizes and carry different charges. This technique is fundamental to many of the procedures used in biotechnology. This lesson guide includes background information for the educator, safety precautions, and questions with answers for learners. For safety reasons, adult supervision is recommended. Modifications for use with younger learners are described in a related PDF (see related resource).

Janice Stephens

2011-01-01

63

Preparing an Agarose Gel  

Science.gov (United States)

This video from CUNY Kingsborough Community College describes the technique of preparing 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 3:10.

Shun Ho, Ivan

64

Testing for Mycobacterium avium subsp. paratuberculosis infection in asymptomatic free-ranging tule elk from an infected herd.  

Science.gov (United States)

Forty-five adult tule elk (Cervus elaphus nannodes) in good physical condition were translocated from a population located at Point Reyes National Seashore, Marin County (California, USA), to a holding pen 6 mo prior to release in an unfenced region of the park. Because infection with Mycobacterium avium subsp. paratuberculosis (Mptb) had been reported in the source population, the translocated elk underwent extensive ante-mortem testing using three Johne's disease assays: enzyme linked immunosorbent assay (ELISA); agar gel immunodiffusion assay (AGID), and fecal culture. Isolation of Mptb was made from fecal samples in six of 45 elk (13%). All AGID results were negative while ELISA results for 18 elk (40%) were considered elevated. Elevated ELISA results or Mptb isolation from fecal samples were obtained for 22 of 45 elk (49%); these elk were euthanized and necropsied. Mycobacterium avium subsp. paratuberculosis was isolated from tissue in 10 of 22 euthanized elk (45%); of these 10 cases of confirmed infection, eight had elevated ELISA results (80%) and four were fecal culture positive (40%). One of 10 cases had histopathologic lesions consistent with Mptb infection. Mycobacterium avium subsp. paratuberculosis was also isolated from tissue from one of eight fetuses sampled. The number of tule elk found to be infected was unexpected, both because of the continued overall health of the source herd and the normal clinical status of all study animals. PMID:12910759

Manning, Elizabeth J; Kucera, Thomas E; Gates, Natalie B; Woods, Leslie M; Fallon-McKnight, Maura

2003-04-01

65

Serologic survey of brucellosis in captive neotropical wild carnivores in northeast Brazil.  

Science.gov (United States)

Abstract. This study reports the detection of antibodies against Brucella abortus and B. canis in wild neotropical carnivores kept in captivity in three zoos in northeastern Brazil. A total of 42 serum samples were examined, 17 from coatis (Nasua nasua), eight from crab-eating raccoons (Procyon cancrivorus), three from crab-eating foxes (Cerdocyon thous), three from hoary foxes (Lycalopex vetulus), two from little spotted cats (Leopardus tigrinus), five from tayras (Eira barbara), two from greater grisons (Galictis vittata), and two from neotropical river otters (Lontra longicaudis). The Rose-Bengal test and complement fixation test (CFT) were performed to detect anti-Brucella spp. antibodies, whereas the agar gel immunodiffusion test (AGID) was employed to detect anti-B. canis antibodies. The overall seroprevalence varied by species and by test; in addition, CFT and AGID seemed better able to detect antibodies against B. abortus and B. canis, respectively. This is the first study on the presence of anti-Brucella spp. antibodies in captive carnivores from Brazil, as well as the first report of antibodies to Brucella spp. in coatis, crab-eating raccoons, hoary foxes, little spotted cats, tayras, and greater grisons. PMID:22779245

Oliveira-Filho, Edmilson F; Pinheiro, José W Junior; Souza, Marcília M A; Santana, Vânia L A; Silva, Jean C R; Mota, Rinaldo A; Sá, Fabricio B

2012-06-01

66

Toxoplasmosis, leptospirosis and brucellosis in stray dogs housed at the shelter in Umuarama municipality, Paraná, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Background : Leptospirosis, toxoplasmosis and brucellosis are diseases with worldwide distribution. Among stray dogs, these zoonoses are facilitated by direct contact with other animal species, by the habit of scavenging garbage and hunting in search of food, drinking standing water, smelling othe [...] r animals' urine, licking female genitalia and the sexual act itself. The objective of this study was to detect antibodies anti-Toxoplasma gondii, anti-Leptospira spp., anti-Brucella canis and anti-Brucella abortus in stray dogs housed in shelters at Umuarama city, Paraná, Brazil. In order to detect toxoplasmosis, indirect immunofluorescence assay (IFA) was performed, agglutination microscopic (MAT) test for leptospirosis and agar gel immunodiffusion (AGID) and buffered acidified antigen (BAA) tests for brucellosis. Results : Of the 175 serum samples analyzed, 70.85% were considered positive for toxoplasmosis by IFA, 20% by MAT for leptospirosis and 2.85% by AGID for Brucella canis. Conclusions : The serological results of this study showed that stray dogs housed at the private shelter are potential carriers of these three different zoonoses and contribute to the spread and maintenance of these etiologic agents in the urban area of Umuarama (PR), Brazil.

Márcia Küster de Paula, Dreer; Daniela Dib, Gonçalves; Isabel Cristina da Silva, Caetano; Edson, Gerônimo; Paulo Henrique, Menegas; Danilo, Bergo; Fabiana Maria Ruiz, Lopes-Mori; Aline, Benitez; Julio Cesar de, Freitas; Fernanda, Evers; Italmar Teodorico, Navarro; Lisiane de Almeida, Martins.

2013-09-25

67

Evaluation of a Commercial Blocking Enzyme-Linked Immunosorbent Assay To Detect Avian Influenza Virus Antibodies in Multiple Experimentally Infected Avian Species?  

Science.gov (United States)

Wild birds of the orders Anseriformes and Charadriiformes are the natural reservoirs for avian influenza (AI) viruses. Traditionally, AI virus surveillance in wild birds has relied on virus identification strategies, including virus isolation and detection. To evaluate the accuracy of a commercial blocking enzyme-linked immunosorbent assay (bELISA) and the agar gel immunodiffusion (AGID) test for detection of antibodies in wild birds, which is indicative of AI virus infection, we tested 281 serum samples from various wild avian species that were experimentally infected with AI viruses. Included in these samples were 178 samples from birds with confirmed AI virus infections (122 infected with low-pathogenic AI [LPAI] viruses and 56 infected with highly pathogenic AI [HPAI] viruses) and 103 samples from birds that were uninfected, negative controls. The sensitivities of the bELISA and the AGID test were 0.820 (95% confidence interval [95% CI], 0.756 to 0.874) and 0.674 (95% CI, 0.600 to 0.742), respectively. Both tests had an estimated specificity of 1.00 (95% CI, 0.965 to 1.00). The bELISA was significantly more sensitive than the AGID test for both LPAI virus- and HPAI virus-infected birds. Both assays, however, had a higher sensitivity for birds infected with HPAI virus than for birds infected with LPAI virus. These results demonstrate the potential utility of the bELISA for detection of antibodies to both LPAI and HPAI viruses in multiple avian species, representing five avian orders and 17 genera. Additional studies are warranted to further evaluate the utility of the bELISA for use with naturally infected birds. PMID:19386796

Brown, Justin D.; Stallknecht, David E.; Berghaus, Roy D.; Luttrell, M. Page; Velek, Katherine; Kistler, Whitney; Costa, Taiana; Yabsley, Michael J.; Swayne, David

2009-01-01

68

Active Polymer Gel Actuators  

OpenAIRE

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...

Shuji Hashimoto; Ryo Yoshida; Yusuke Hara; Shingo Maeda

2010-01-01

69

Gel Polymer Electrolytes.  

Czech Academy of Sciences Publication Activity Database

Brno : University of Technology Brno, 2002, s. 49-1-49-3. ISBN 80-214-2082-0. [Advanced Batteries and Accumulators /3./. Brno (CZ), 16.06.2002-20.06.2002] R&D Projects: GA AV ?R IAA4032002; GA ?R GA104/02/0731 Institutional research plan: CEZ:AV0Z4032918 Keywords : gel polymer * lithium ion batteries * PMMA Subject RIV: CA - Inorganic Chemistry

Vondrák, Ji?í; Sedla?íková, M.; Nová?ek, T.; Reiter, J.

70

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  

Directory of Open Access Journals (Sweden)

Full Text Available 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. Considerando 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.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 dissemination 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

2008-06-01

71

Thoria sol-gel processes  

International Nuclear Information System (INIS)

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

72

Radiotherapy gel dosimetry: a review  

International Nuclear Information System (INIS)

Radiation therapy or radiotherapy is a common form of cancer treatment. Recent advances in radiotherapy such as intensity modulated radiation therapy indicate that treatment outcomes may be improved. The principle limitation of these more advanced techniques of radiation therapy is the ability to quantify the absorbed radiation dose to the tumour which is related to the 3- dimensional geometry of the tumour. The main advances in 3-dimensional radiation dosimetry are the development of radiation sensitive polymer gel dosimeters. The use of radiation sensitive gels for radiation dosimetry in cancer therapy was first suggested in the 1950s. It was subsequently shown in 1984 that radiation induced changes in nuclear magnetic resonance relaxation properties of gels infused with conventional Fricke dosimetry solutions could be measured. Due to diffusion-related limitations in the use of Fricke gels, alternative polymer gel dosimeters were subsequently suggested in 1992. Since then, both magnetic resonance and optical imaging techniques have been used to evaluate polymer gel dosimeters to produce three-dimensional radiation dose distributions. More recently the uses of x-ray computer tomography and vibrational spectroscopy have also been demonstrated as valuable techniques in the evaluation of these dosimetry gels. Although not yet used routinely clinically, applications of these radiologically soft-tissue equivalent gel dosimeters have been shown to have great potential in ave been shown to have great potential in the evaluation of complex radiation dose distributions. A review of 3-dimensional radiotherapy gel dosimetry is presented

73

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.

2003-12-01

74

Nanocrystal/sol-gel nanocomposites  

Science.gov (United States)

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

75

Electrochemical Light-Emitting Gel  

Directory of Open Access Journals (Sweden)

Full Text Available 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 nanoparticle materials. TiO2 nanoparticles were a better gelation filler than silica or ZnO was, with respect to luminescence stability, thus indicating a catalytic effect. It is demonstrated that the light-emitting gel device, with quite a simple fabrication process, flashes with the application of voltage.

Nobuyuki Itoh

2010-06-01

76

21 CFR 520.1452 - Moxidectin gel.  

Science.gov (United States)

...2010-04-01 2010-04-01 false Moxidectin gel. 520.1452 Section 520.1452 Food and...NEW ANIMAL DRUGS § 520.1452 Moxidectin gel. (a) Specifications . Each milliliter of gel contains 20 milligrams (2 percent)...

2010-04-01

77

Introduction to Agarose Gel Electrophoresis  

Science.gov (United States)

In this module, developed as part of Cornell's Learning Initiative in Medicine and Bioengineering (CLIMB), students are introduced to the concepts of gel electrophoresis without requiring all the equipment needed to run a full gel electrophoresis experiment. The goal is to have students understand how gels are made for DNA separation and how altering the composition can affect the experimental parameters. This module contains a teacher's guide, classroom activity, and suggestions for extended activities. This lab is a precursor to Cornell’s Institute for Biology Teachers lab’s entitled DNA Profiling – Paternity Testing, which is linked within the teacher's guide. CLIMB is part of the NSF GK-12 program.

CLIMB: Cornell's Learning Initiative in Medicine and Bioengineering

78

Sol-gel capillary microextraction.  

Science.gov (United States)

Sol-gel capillary microextraction (sol-gel CME) is introduced as a viable solventless extraction technique for the preconcentration of trace analytes. To our knowledge, this is the first report on the use of sol-gel-coated capillaries in analytical microextraction. Sol-gel-coated capillaries were employed for the extraction and preconcentration of a wide variety of polar and nonpolar analytes. Two different types of sol-gel coatings were used for extraction: sol-gel poly(dimethylsiloxane) (PDMS) and sol-gel poly(ethylene glycol) (PEG). An in-house-assembled gravity-fed sample dispensing unit was used to perform the extraction. The analysis of the extracted analytes was performed by gas chromatography (GC). The extracted analytes were transferred to the GC column via thermal desorption. For this, the capillary with the extracted analytes was connected to the inlet end of the GC column using a two-way press-fit fused-silica connector housed inside the GC injection port. Desorption of the analytes from the extraction capillary was performed by rapid temperature programming (at 100 degrees C/min) of the GC injection port. The desorbed analytes were transported down the system by the helium flow and further focused at the inlet end of the GC column maintained at 30 degrees C. Sol-gel PDMS capillaries were used for the extraction of nonpolar and moderately polar compounds (polycyclic aromatic hydrocarbons, aldehydes, ketones), while sol-gel PEG capillaries were used for the extraction of polar compounds (alcohols, phenols, amines). The technique is characterized by excellent reproducibility. For both polar and nonpolar analytes, the run-to-run and capillary-to-capillary RSD values for GC peak areas remained under 6% and 4%, respectively. The technique also demonstrated excellent extraction sensitivity. Parts per quadrillion level detection limits were achieved by coupling sol-gel CME with GC-FID. The use of thicker sol-gel coatings and longer capillary segments of larger diameter (or capillaries with sol-gel monolithic beds) should lead to further enhancement of the extraction sensitivity. PMID:11866054

Bigham, Shaun; Medlar, Jennifer; Kabir, Abuzar; Shende, Chetan; Alli, Abdel; Malik, Abdul

2002-02-15

79

Adhesive, elastomeric gel impregnating composition  

Science.gov (United States)

An improved capacitor roll with alternating film and foil layers is impregnated with an adhesive, elastomeric gel composition. The gel composition is a blend of a plasticizer, a polyol, a maleic anhydride that reacts with the polyol to form a polyester, and a catalyst for the reaction. The impregnant composition is introduced to the film and foil layers while still in a liquid form and then pressure is applied to aid with impregnation. The impregnant composition is cured to form the adhesive, elastomeric gel. Pressure is maintained during curing.

Shaw, David Glenn (Tucson, AZ); Pollard, John Randolph (Tucson, AZ); Brooks, Robert Aubrey (Tijeras, NM)

2002-01-01

80

Transdermal delivery of paeonol using cubic gel and microemulsion gel  

OpenAIRE

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®...

Chen J.; Shen Q; Luo M

2011-01-01

81

Denaturing gradient gel electrophoresis  

International Nuclear Information System (INIS)

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

82

PREPARATION AND CHARACTERIZATION OFCHITOSAN GELS  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english 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; CARLOS, VON PLESSING; GALO, CÁRDENAS.

1022-10-01

83

Microbubble tunneling in gel phantoms  

OpenAIRE

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

84

Raft Instability of Biopolymer Gels  

CERN Document Server

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

85

Tracer diffusion in colloidal gels  

OpenAIRE

Computer simulations were done of the mean square displacement (MSD) of tracer particles in colloidal gels formed by diffusion or reaction limited aggregation of hard spheres. The diffusion coefficient was found to be determined by the volume fraction accessible to the spherical tracers ($\\phi_a$) independent of the gel structure or the tracer size. In all cases, critical slowing down was observed at $\\phi_a\\approx 0.03$ and was characterized by the same scaling laws reporte...

Babu, Sujin; Gimel, Jean Christophe; Nicolai, Taco

2007-01-01

86

TOPICAL REVIEW: Polymer gel dosimetry  

Science.gov (United States)

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.

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

2010-03-01

87

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

88

NMR mechanisms in gel dosimetry  

Science.gov (United States)

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.

2009-05-01

89

Thixotropic gel for vadose zone remediation  

Science.gov (United States)

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.

Riha, Brian D.

2012-07-03

90

Evaluation of standard reagents for radial-immunodiffusion assays. In vitro control of rabies vaccines / Avaliação de reativos padrões para provas de Imunodifusão Radial. Controle in vitro de vacinas antirrábicas  

Scientific Electronic Library Online (English)

Full Text Available A prova de Imunodifusão Radial (IDR) é um método in vitro conveniente para determinar a concentração de antígenos no produto final como um todo, de vacinas anti-rábicas para uso veterinário. Os reativos padrões candidatos para uso na prova IDR, proposta para o controle de processo de vacinas de cult [...] ivo celular, elaboradas na América Latina e Caribe, foram produzidos e padronizados no Instituto Panamericano de Proteção de Alimentos e Zoonoses (INPPAZ). A validação dos padrões e o controle de qualidade de 28 lotes de vacinas anti-rábicas, de diferentes procedências, foram realizados na Faculdade de Ciências Veterinárias da Universidade de La Plata, Argentina (UNLP). Todas as vacinas foram elaboradas com virus rábico cepa Pasteur (PV) em células BHK e sua atividade foi determinada através de provas in vivo (NIH) e in vitro (IDR). Os resultados dos reativos, candidatos para as provas de padronização, demonstraram estabilidade, sensibilidade e reprodutibilidade. Por análise de variância e de regressão foi estimada a potência relativa de 1.2 entre as vacinas problemas e a vacina de referência. Os resultados deste estudo de validação indicam que o INPPAZ, está em condições de elaborar e distribuir os reativos padrões acima mencionados e apoiar a adoção da técnica de IDR (sensível, rápida, econômica) pelos laboratórios de produção de vacinas anti-rábicas da América Latina e Caribe. Abstract in english The RID assay is one of the in vitro methods used for in-process control in the production of rabies vaccines for veterinary use. It has been shown to be very useful for determining antigen concentration in the final bulk product. The work presented in this paper, including the production and standa [...] rdization of candidate standard reagents for use in the Radial Immunodiffusion Assay (RID) was carried out at the Pan American Institute for Food Protection and Zoonoses (INPPAZ/PAHO/WHO). The study was completed with the cooperation of the Faculty of Veterinary Sciences, National University of La Plata (NULP), Argentina, where the validation of the proposed standards and the quality control of samples from 28 different batches of rabies vaccines produced with Pasteur strain rabies virus (PV) in BHK cells were performed. The activity of the vaccines was determined by in vivo (NIH) and in vitro (RID)assays. The results of the candidate reagents for the reagent standardization tests showed stability, sensitivity and reproducibility. The Relative Potency the 1.2 between the problem vaccines and the reference vaccine was estimated by variance and regression analysis. The results of our validation study show that the INPPAZ (PAHO/WHO) is capable of producing and distributing the above-mentioned standard reagents, as well as of providing support for the incorporation of the RID technique (sensitive, rapid and inexpensive) to the laboratories that manufacture rabies vaccines in Latin America and the Caribbean.

Graciela S., MICELI; Jorge, TORROBA; Walter, TORRES; Jorge, ESTEVES MADERO; Ana Maria, DÍAZ.

2000-06-01

91

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

92

Fundamentals of Polymer Gel Dosimeters  

Science.gov (United States)

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

McAuley, Kim B.

2006-12-01

93

3-dimensional polymer gel dosimetry  

International Nuclear Information System (INIS)

Recently developed techniques in conformal radiotherapy demand special properties of radiation dosimeters. Polymer gel dosimeter evaluated by nuclear magnetic resonance (NMR) is promising tool which can be used for measuring rather complicated 3-dimensional dose distributions with required precision of ± 5 %. This system is based on radiation-induced polymerisation and cross-linking of acrylic monomers which are uniformly dispersed in aqueous gel. The formation of cross-linked polymers in the irradiated regions of the gel increases the NMR relaxation rates of neighbouring water protons. BANG-2 type polymer gel was prepared. The composition of gel dosimeter was as follows: 3 % N,N'-methylene-bisacrylamide, 3 % acrylic acid, 1 % sodium hydroxide, 5 % gelatine, and 88 % water, where all percentages are by weight. The dosimeters in glass vessels were homogeneously irradiated by 60Co gamma photons in a Gammacell 220 unit and by 4 MV, 6 MV and 18 MV X ray photons on Varian Clinac 600C and 2100 C linear accelerators by doses in the range of 0-50 Gy. Evaluation of dosimeters was performed on Siemens EXPERT 1 T and Siemens VISION 1,5 T scanners. Multi-echo CPMG sequence with 16 echoes was used for the evaluation of T2-relaxation times in irradiated gel dosimeters. The dependence of 1/T2 response of dosimeters was studied on following factors: absorbed dose, energy of applied radiation, temperature during NMR evaluation, time since irradiation to NMR evaluation and since irradiation to NMR evaluation and strength of the magnetic field. An exponential dependence of 1/T2 response on absorbed dose in the range of 0-50 Gy was observed, in the range 0-10 Gy the data could be fitted by a linear function. There was observed no dependence of 1/T2 response on: energy (for three different photon energies used in this study), strength of magnetic field of NMR scanner, time from irradiation of the dosimeters to NMR evaluation. Increase of gel dosimeter 1/T2 response with the decrease of the temperature during NMR evaluation was observed. Polymer gel dosimetry system used in this study proved that it is reliable system for dose distribution measurement with error less than 5 % for doses higher than 3 Gy. (author)

94

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

95

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

DEFF Research Database (Denmark)

Responsive biomaterial hydrogels attract significant attention due to their biocompatibility and degradability. In order to make chitosan based gels, we first graft one layer of chitosan to silica, and then build a chitosan/poly(acrylic acid) multilayer using the layer-by-layer approach. After cross-linking the chitosan present in the polyelectrolyte multilayer, poly(acrylic acid) is partly removed by exposing the multilayer structure to a concentrated carbonate buffer solution at a high pH, leaving a surface-grafted cross-linked gel. Chemical cross-linking enhances the gel stability against detachment and decomposition. The chemical reaction between gluteraldehyde, the cross-linking agent, and chitosan was followed in situ using total internal reflection Raman (TIRR) spectroscopy, which provided a molecular insight into the complex reaction mechanism, as well as the means to quantify the cross-linking density. The amount of poly(acrylic acid) trapped inside the surface grafted films was found to decrease with decreasing cross-linking density, as confirmed in situ using TIRR, and ex situ by Fourier transform infrared (FTIR) measurements on dried films. The responsiveness of the chitosan-based gels with respect to pH changes was probed by quartz crystal microbalance with dissipation (QCM-D) and TIRR. Highly cross-linked gels show a small and fully reversible behavior when the solution pH is switched between pH 2.7 and 5.7. In contrast, low cross-linked gels are more responsive to pH changes, but the response is fully reversible only after the first exposure to the acidic solution, once an internal restructuring of the gel has taken place. Two distinct pKa's for both chitosan and poly(acrylic acid), were determined for the cross-linked structure using TIRR. They are associated with populations of chargeable groups displaying either a bulk like dissociation behavior or forming ionic complexes inside the hydrogel film. © 2014 American Chemical Society.

Liu, Chao; Thormann, Esben

2014-01-01

96

Gel Electrophoresis Lab: DNA Fingerprinting  

Science.gov (United States)

This lab activity from the Biotechnology Alliance for Suncoast Biology Educators introduces the methods of RFLP analysis, or DNA fingerprinting, by using gel electrophoresis. Students will learn the role of restriction enzymes in DNA fingerprinting. Required materials, procedure and instructions are provided. This lesson plan may be downloaded in Microsoft Word document file format.

Ehlers, Megan

97

Gel Electrophoresis Lab: Paternity Case  

Science.gov (United States)

This lab activity from the Biotechnology Alliance for Suncoast Biology Educators provides instructions for conducting a gel electrophoresis lab. Students will try to solve a paternity case with this activity by obtaining a DNA fingerprint from each potential father, the mother and the child. This activity may be downloaded in PDF file format. A data collection sheet and student questions are also included.

98

Gluing gels: A nanoparticle solution  

Science.gov (United States)

Synthetic polymer gels with certain surface chemistries can be glued together by a simple and inexpensive method that uses commercially available silica nanoparticles. Biological tissues can also be joined by this nanotechnological route, eliminating the need for sutures, additional adhesives or chemical reactions.

Appel, Eric A.; Scherman, Oren A.

2014-03-01

99

Polyelectrolyte intelligent gels. Design and applications  

OpenAIRE

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

100

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

101

Clindamycin phosphate 1% gel in acne vulgaris.  

Science.gov (United States)

A 12-week study compared Clindagel, a unique water-based gel formulation of clindamycin phosphate 1%, administered once daily, and Cleocin T, a slightly different gel formulation indicated for twice-daily use, in the treatment of acne vulgaris. Clindagel was safe and effective and equivalent to Cleocin T gel, albeit with a better tolerability profile. Clindagel is a viable alternative to Cleocin T gel. PMID:11841194

Rizer, R L; Sklar, J L; Whiting, D; Bucko, A; Shavin, J; Jarratt, M

2001-01-01

102

Characteristics of platelet gels combined with silk.  

Science.gov (United States)

Platelet gel, a fibrin network containing activated platelets, is widely used in regenerative medicine due the capacity of platelet-derived growth factors to accelerate and direct healing processes. However, limitations to this approach include poor mechanical properties, relatively rapid degradation, and the lack of control of release of growth factors at the site of injection. These issues compromise the ability of platelet gels for sustained function in regenerative medicine. In the present study, a combination of platelet gels with silk fibroin gel was studied to address the above limitations. Mixing sonicated silk gels with platelet gels extended the release of growth factors without inhibiting gel-forming ability. The released growth factors were biologically active and their delivery was modified further by manipulation of the charge of the silk protein. Moreover, the silk gel augmented both the rheological properties and compressive stiffness of the platelet gel, tuned by the silk concentration and/or silk/platelet gel ratio. Silk-platelet gel injections in nude rats supported enhanced cell infiltration and blood vessel formation representing a step towards new platelet gel formulations with enhanced therapeutic impact. PMID:24480538

Pallotta, Isabella; Kluge, Jonathan A; Moreau, Jodie; Calabrese, Rossella; Kaplan, David L; Balduini, Alessandra

2014-04-01

103

Study of Fricke gel dosimeter response for different gel quality  

International Nuclear Information System (INIS)

The Fricke xylenol gel (FXG) dosimeter has been studied for application in radiotherapy because it is capable of to measure the spatial distribution of radiation doses. The dosimetry is based on the oxidation of ferrous (Fe2+) to ferric (Fe3+) ions radiation induced, related to the radiation dose. The gel material usually employed is the 300 Bloom gelatin, which is imported and very expensive in Brazil. Aiming to analyze the viability of to use a locally produced and low cost gel material, in this work the spectrophotometric responses of FXG solutions prepared using 270 Bloom gelatin commercially available and 300 Bloom gelatin imported were compared. The absorption spectra of solutions prepared with 5% by weight 270 and 300 Bloom gelatins non-irradiated and irradiated with 60Co gamma radiation in the dose range between 0.5 and 100 Gy were analysed, the dose-response curves were evaluated and the useful dose range was established. The obtained results indicate that the FXG solution prepared with 270 Bloom gelatin presents good performance, similar to that presented by the FXG solution prepared with 300 Bloom gelatin and its use can be recommended owing to the low cost and the availability in local market.

104

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

OpenAIRE

This review describes the electrophoresis of curved and normal DNA molecules in agarose gels, polyacrylamide gels and in free solution. These studies were undertaken to clarify why curved DNA molecules migrate anomalously slowly in polyacrylamide gels but not in agarose gels. Two milestone papers are cited, in which Ferguson plots were used to estimate the effective pore size of agarose and polyacrylamide gels. Subsequent studies on the effect of the electric field on agarose and polyacrylami...

Stellwagen, Nancy C.

2009-01-01

105

Diffusion of potassium chromate in Agar gel  

International Nuclear Information System (INIS)

Tracer and self-diffusion coefficients for potassium chromate labelled with 51Cr 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.)

106

Gel transitions in colloidal suspensions  

OpenAIRE

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

107

Elasticity of c*-Gels  

OpenAIRE

A junction affine network model is solved for chains following a Redner–des Cloizeaux distribution. In a gel at c* the network strands behave as isolated chains. In a good solvent their elastic properties cannot be obtained from Gaussian statistics as in the classical models of rubber elasticity. Instead the Redner-des Cloizeaux distribution is employed, which is known to be an excellent approximation to the end–to–end distance distribution of flexible polymer chains in a good solvent. ...

Everaers, Ralf

1995-01-01

108

Counting efficiency of scintillating gels  

International Nuclear Information System (INIS)

Scintillating gels that are suitable for the counting of insoluble radioact+ve samples, sometimes exhibit in addition a higher scintillation yield than the corresponding liquid scintillators. This property, observable when silica is added into dioxane liquid scintillators, is inherent in some primary solutes (PPO, PBD, butyl-PBD) while not obvious for others (CPO, PFD, BPO, ?NPO). Quenching properties of chlorinated compounds (CHCl3, CCl4) and energy transfer mechanisms are not changed by silica addition. On the other hand, PPO, PBD and butyl-PBD fluorescence quantum yields are markedly increased under these conditions, probably because of the higher viscosity of the samples. Another scintillating gel was prepared by the addition of HP55 (hydroxy propyl methyl cellulose phthalate) into PPO-dioxane liquid scintillator; its scintillation yield is reduced without any change of transfer mechanisms and at the same time PPO fluorescence quantum yield is diminished. A static quenching process by HP55 is likely to occur, which screens the viscosity effect noticed in the presence of Cab-O-Sil. Thus, PPO, PBD and butyl-PBD seem to be the most efficient primary solutes among those studied since they provide gel scintillator giving improved counting efficiency compared to that of liquid scintillator. (author)

109

Detection of antibodies to Brucella ovis in sheep milk using B. ovis and B. canis antigen.  

Science.gov (United States)

The diagnostic techniques most widely used for detecting brucellosis caused by Brucella ovis are serological tests such as complement fixation (CFT), agar gel immunodiffusion (AGID), and ELISAs. However, to our knowledge, milk tests, with the advantage that samples may be taken in a non invasive manner, have not been investigated as diagnostic tools. We studied 144 samples of milk and sera from lactating ewes, comparing bacteriological studies, serological and milk tests using Brucella canis and B. ovis antigens. A group of 75 ewes in an uninfected flock were serologically negative to rapid slide agglutination test (RSAT), indirect ELISA (IELISA)-B. canis, AGID and IELISA-B. ovis. The milk of these ewes had an IELISA-B. canis mean (%P) value of 16.18 (S.D. 5.63), while the IELISA-B. ovis had a mean (%P) value of 12.52 (S.D. 4.94). A cut-off value of (%P) 27.44 (+2 S.D.) or (%P) 33 (+3 S.D.) was determined by milk-ELISA-B. canis and (%P) 22.4 (+2 S.D.) and (%P) 27.34 (+3 S.D.) by milk-IELISA-B. ovis. These cut-off values were adjusted by receiver-operator characteristics (ROC) analysis using 23 positive samples from infected ewes, which indicated a milk-IELISA-B. canis cut-off value of (%P) 33 and milk-IELISA-B. ovis of (%P) 26 with 100% sensitivity and specificity. Based on our results, we propose that, following a study of a larger number of samples, the milk-IELISA-B. canis could be considered a suitable test for the diagnosis of B. ovis brucellosis in lactating ewes. PMID:16678362

López, G; Escobar, G I; Ayala, S M; Lucero, N E

2006-08-25

110

Diagnosis of peste des petits ruminants infection in small ruminants through in-house developed Indirect ELISA: Practical considerations  

Directory of Open Access Journals (Sweden)

Full Text Available Aim: The work was conducted to diagnose peste des petits ruminants (PPR outbreak through an in house developed indirect ELISA (thereafter referred as iELISA its comparison with other available diagnostic tests and description of practical considerations in its development, utility and limitations. Materials and Methods: An outbreak resembled to PPR occurred in two different places of southern Gujarat viz. Vapi and Navsari, affecting 622 animals, including both goat (n = 476 and sheep (n = 146. Animals displayed the typical signs of PPR at Vapi; however diarrhea was the inconsistent feature in animals of Navsari. The affection caused morbidity of 100% and mortality were 73.68% (n = 392/532 and 56.67% (n = 51/90 in Vapi and Navsari outbreaks, respectively. Relevant ante mortem and post mortem samples were collected from representative animals. At the outset of the epidemic no kit was available with us, so agar gel immunodiffusion (AGID was carried out and a commercial ELISA (cELISA kit was ordered for making diagnosis through antibody demonstration. Meanwhile, an iELISA was developed in house using PPR vaccine as antigen and protein G conjugated HRPO antibody as detector. Histopathology and results of sandwich ELISA were also used to diagnose PPR virus (PPRV in the outbreak. Results: The iELISA developed had detected PPRV antibodies in 22/24 samples (91.66%. Significant difference was observed in disease sensitivity pattern of two species by Chi-square test. While AGID failed to detect antibodies in any sample. Results were reconfirmed by comparing with commercially available cELISA kit. Conclusion: PPR is an economically important disease and for the rapid diagnosis of PPR the in house developed antibody capture iELISA can be a suitable cost effective alternative.

K. K. Sharma

2015-04-01

111

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

112

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

113

Expression and antigenic characterization of the major core protein VP7 of Chuzan virus, a member of the Palyam serogroup orbiviruses.  

Science.gov (United States)

The Palyam serogroup-specific antigen, VP7, of Chuzan virus strain K-47 was expressed in insect cells by a recombinant baculovirus. The expressed protein appeared as a single band of 38kDa corresponding to the predicted molecular mass of Chuzan virus VP7 by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). In immunoprecipitation analysis, the recombinant VP7 was not only recognized by all polyclonal antibodies against the Palyam serogroup viruses (PALV) tested in this study, but also by antisera to bluetongue virus (BTV) serotype 1, epizootic haemorrhagic disease virus (EHDV) serotypes 1 and 2. However, in Western immunoblot assay, no positive signals were observed between this protein and these antisera, even in the homologous reaction using antiserum to Chuzan virus. These findings demonstrate that the common antigenic determinants on the VP7 proteins of Chuzan virus and the other PALV serotypes are mainly conformational and that the proteins share some epitopes with those of BTV and EHDV beyond the serogroup. No cross-reactivities were detected between Chuzan virus VP7 and antisera to BTV and EHDV in agar gel immunodiffusion (AGID) and indirect ELISA tests, indicating that the recombinant VP7 is useful as a diagnostic reagent for serological tests of congenital abnormalities of cattle caused by PALV. PMID:11600267

Yamakawa, M; Furuuchi, S

2001-12-01

114

Rheological characterization of Poloxamer 407 nimesulide gels  

Directory of Open Access Journals (Sweden)

Full Text Available 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 concentrations of Poloxamer 407, were prepared. Viscosity measurements were performed by rheologial studies to obtain the optimal sol-gel transition temperature . Poloxamer 407 gels are pseudoplastic and viscoelastic materials, which have an elastic modulus (G', characteristic of the solid, and a viscous modulus (G'', characteristic of the liquid material. Moreover, being pseudoplastic gels, when they are deformed by shearing, their viscosity decreases. Increase of the polymer concentration increased the viscosity of the gels, which could affect the releasing process of nimesulide. Furthermore, the presence of nimesulide led to a lowering of the sol-gel transition temperature. Keywords: Poloxamer 407 gels; nimesulide; rheological characterization; viscosity; sol-gel transition temperature.

M. N. Freitas

2009-01-01

115

Bacterial cellulose gels with high mechanical strength.  

Science.gov (United States)

A composite structure was formed between polyethylene glycol diacrylate (PEGDA) and bacterial cellulose (BC) gels swollen in polyethylene glycol (PEG) as a solvent (BC/PEG gel) to improve the mechanical strength of the gels. The mechanical strength under compression and the rheostatic properties of the gels were evaluated. The compression test results indicated that the mechanical strength of the gels depended on the weight percent of cross-linked PEGDA in the gel, the chain length between the cross-linking points, and the cross-linking density of PEGDA polymers. The PEGDA polymers around the cellulose fibers were resistant to pressure; thus, the BC/PEG-PEGDA gel was stronger than the BC/PEG gel under compression. The results of transmittance measurements and thermomechanical analysis showed that the rheostatic properties of the gels were retained even after composite structure formation. BC/PEG-PEGDA gels, which are expected to be biocompatible, may be useful for clinical applications as a soft material. PMID:25492172

Numata, Yukari; Sakata, Tadanori; Furukawa, Hidemitsu; Tajima, Kenji

2015-02-01

116

Tailoring the properties of supramolecular gels  

Science.gov (United States)

Supramolecular gels created from low molecular weight species (gelators) have gathered wide attention over the past few decades on account of their highly ordered assembly and ability to respond to external stimuli. These properties make such gels highly promising candidates for a diverse range of applications including biomaterials, viscosity modifiers, sensors, and liquid crystalline materials. We have focused on the design and tailoring of guanosine (the ribonucleoside of the nucleobase guanine) hydrogels. It is well known that in an aqueous environment, guanosine forms circular hydrogen-bonded quartets around a monovalent metal ion, most commonly potassium. These quartets then stack to form high-aspect ratio fibers that entangle and branch to form gels. Despite facile gel formation, crystallization of the guanosine molecules out of the gel is a common occurrence that leads to gel collapse within hours of fabrication. In addition, guanosine and related gelators often require a high potassium concentration or acidic pH to gel, which presents limited practical use in our target application of tissue engineering. We have focused on the modification and analysis of guanosine gels via an additive and/or a change in chemical structure to inhibit crystallization and promote gelation at physiological salt concentrations. Additionally, initial cell culture experiments suggest that these gel materials show great potential as an easily accessible and inexpensive tissue engineering scaffold. We also examined the potential for supramolecular gels for use in personal care formulations as electrolyte-resistant rheology modifiers for aqueous systems. Sugar-based gels fit the necessary criteria; however, many of these molecules also crystallize from the gel over time. We achieved lifetime stabilization again via a mixing approach and examined the resulting properties of the stabilized gels.

Buerkle, Lauren

117

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 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.

2014-04-01

118

Active Gel Model of Amoeboid Cell Motility  

CERN Document Server

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

119

Tridimensional dosimetry using MAGIC gel with formaldehyde  

International Nuclear Information System (INIS)

This paper presents the application of MAGIC gel with formaldehyde (MAGIC-f) in the tri dimensional dose distribution measurement of an IMRT planning. A high similarity was found between the dose distributions measured by the gel dosimeter and the dose distributions expected by the treatment planning system (TPS) in all of the irradiated volume, this was proved by the direct overlapping of these isodoses. These results show that MAGIC-f gel is feasible for tridimensional dose distribution measurements. (author)

120

Stiffening in gels containing whey protein isolate  

OpenAIRE

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...

Purwanti, N.; Veen, E.; Goot, A. J.; Boom, R. M.

2013-01-01

121

Crystal structure of thermally reversible maltodextrin gels  

International Nuclear Information System (INIS)

Aqueous solutions of starch solidify at room temperature to form thermally irreversible gels. These gels exhibit the wide angle X-ray pattern of B-starch. In thermally reversible gels of a special digestion product of starch the B-pattern of starch is also observed. The property of thermal reversibility therefore is not due to amorphous or different crystalline structures, but is a consequence of smaller macromolecules. (author)

122

Computer Analysis of Two-Dimensional Gels  

OpenAIRE

This work identifies statistical algorithms which need to be included in analysis of two-dimensional gels for accurate determination of differential changes. Two-dimensional electrophoresis is a powerful tool for determining differential protein expression in complex mixtures, but the methodology, to date, is not producing expected results due to the degree of gel variability. The new DIGE procedure, comparing two samples in the same gel, does eliminate some of the variability introduced with...

Goldfarb, Marcia

2007-01-01

123

Brillouin light-scattering from polymer gels  

OpenAIRE

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

124

Penile application of dextrin sulphate gel (Emmelle)  

OpenAIRE

Dextrin sulphate (DS) gel (Emmelle) is under development as a vaginal microbicide. Males who do not use condoms will be exposed to DS gel through sexual intercourse. A randomized, double-blind, placebo-controlled trial was conducted among 16 HIV-positive and 12 HIV-negative men to establish whether 4% DS gel has an acceptable safety profile. Men were asked to apply the gel to the penis once per day for 14 consecutive days and to leave it on for a minimum of 6 h. Results from laboratory evalua...

Damme, L.; Jespers, V.; Dyck, E.; Chapman, A.

2002-01-01

125

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)

126

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.

127

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

Directory of Open Access Journals (Sweden)

Full Text Available O emprego de gel-eletroforese no diagnóstico da varíola, demonstrou ser ao menos trinta vezes (30X mais sensível que o teste de agar-gel, nas condições descritas (tabela I. Doze (12 espécimes, cujos testes convencionais de inoculação em ovos embrionados e de agar-gel resultaram positivos, foram testados em suas diluições originais congeladas por mais de um ano, sendo seis deles revelados por gel-eletroforese enquanto nenhum o foi por agar-gel (tabela II. Trinta e três (33 amostras isoladas no laboratório, foram testadas com material colhido de membrana cório-alantóica da primeira inoculação para o diagnóstico, conservado em glicerina 50%, resultando 15 positivas em gel-eletroforese e apenas 3 em agar-gel (tabela II. Os últimos 60 espécimes recebidos para diagnóstico, através a Campanha de Erradicação da Varíola, também resultaram negativos em gel-eletroforese, que não mostrou falsos-positivos nas condições descritas.The test of gel-electrophoresis applied to the pox virus group showed to be at least thirth times (30X more sensitive than agar-gel test on the described conditions (Table I. Twelve specimens, which were positives form Smallpox in the conventional tests of egg inoculation and agar-gel difusion test, have been screened in their original dilutions frozen for more than 1 year and six of them were still detectable by gel-eletrophoresis, while by agar-gel test any of them was positive (Table II. Thirty three Smallpox isolates have been tested with material from first egg inoculation (chorioallantoic membranes which have been stored in glycerin 50%, at - 15ºC. Fifteen of them were still positive by gel-electrophoresis and only 3 by agar-gel (Table II. The last 60 specimens received for diagnosis from Smallpox Erradication Campaign (CEV, were negatives by both tests. The gel-electrophoresis, did not show false-positives on described conditions.

Julio A. Mesquita

1972-01-01

128

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

OpenAIRE

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

129

Radiological properties of normoxic polymer gel dosimeters  

International Nuclear Information System (INIS)

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

130

Problems in the serodiagnosis of canine brucellosis: dog responses to cell wall and internal antigens of Brucella canis.  

Science.gov (United States)

Three procedures are commonly used for the serodiagnosis of B. canis infection: 1) The rapid slide agglutination test (RSAT), 2) the tube agglutination test (TAT), and 3) the modified 2-mercaptoethanol tube agglutination test (2ME-TAT). Hemocultures are always essential for diagnosis. The RSAT was developed to provide a presumptive diagnosis rapidly. It has been found accurate in identifying non-infected dogs; however false positive reactions are common due to shared determinants between the surface antigens of B. canis and certain other gram-negative bacteria. The RSAT has recently been modified to include brief reaction of test sera with 2ME (0.2M) prior to adding test antigen. The modification has improved specificity, but it has not eliminated false positive reactions. The TAT and 2ME-TAT are widely used. Although there is good agreement between tests, both suffer from lack of specificity but are valuable in kennels where B. canis has been identified by blood cultures. Agarose gel immunodiffusion (AGID) tests using extracted (SDC or hot PBS) cell wall antigenic complexes reveal precipitins in the sera of infected dogs usually 8 to 12 weeks postinfection (PI) that may persist 5 years. The antigenic complexes consist of at least 3 antigens; one (antigen '2R') appears to possess high B. canis specificity. Sera from noninfected dogs also may react nonspecifically in AGID tests that employ crude SDC or PBS antigenic extracts leading to 'false positive' interpretations. Cytoplasmic antigens gave up to four precipitin lines with sera from B. canis infected dogs. The antigens (protein or glycoprotein) were present in both S and R Brucella cells, but not in other gram-negative organisms examined. AGID tests that employed cytoplasmic antigens revealed precipitins against one or more (usually 2-3) antigens from PI months 4 through 64. In some dogs, precipitins were present 12 months after the bacteremia had ceased, a time when other tests were diagnostically insignificant, or equivocal. No 'false positive' field sera reached with the cytoplasmic antigens. PMID:6489621

Carmichael, L E; Zoha, S J; Flores-Castro, R

1984-01-01

131

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

132

Sol-gel bonding of silicon wafers  

International Nuclear Information System (INIS)

Sol-gel bonds have been produced between smooth, clean silicon substrates by spin-coating solutions containing partially hydrolysed silicon alkoxides. The two coated substrates were assembled and the resulting sandwich fired at temperatures ranging from 60 to 600 deg. C. The sol-gel coatings were characterised using attenuated total reflectance Fourier transform infrared spectroscopy, ellipsometry, and atomic force microscopy, while the corresponding bonded specimens were investigated using scanning electron microscopy and cross-sectional transmission electron microscopy. Mechanical properties were characterised using both microindentation and tensile testing. Bonding of silicon wafers has been successfully achieved at temperatures as low as 60 deg. C. At 300 deg. C, the interfacial fracture energy was 1.55 J/m2. At 600 deg. C, sol-gel bonding provided superior interfacial fracture energy over classical hydrophilic bonding (3.4 J/m2 vs. 1.5 J/m2). The increase in the interfacial fracture energy is related to the increase in film density due to the sintering of the sol-gel interface with increasing temperature. The superior interfacial fracture energy obtained by sol-gel bonding at low temperature is due to the formation of an interfacial layer, which chemically bonds the two sol-gel coatings on each wafer. Application of a tensile stress on the resulting bond leads to fracture of the samples at the silicon/sol-gel interface the silicon/sol-gel interface

133

Silver nanowires embedded gel electrodes  

Science.gov (United States)

The polyelectrolyte of high-strength gels was made to improve the mechanical properties in our previous study. In the field of electronic devices, the demand of polymer electrodes, which have high conductivity, high flexibility and transparence, is increasing. In this study, we attempt to make a transparent polymer electrode by laminating polymer thin film and silver nanowire (AgNW). High transparenct poly(methyl methacrylate) (PMMA) film, which is produced by using solvent cast method is used. AgNW is prepared by reacting Silver chloride (AgCl) with Silver nitrate (AgNO3) based on previous study. The AgNWs taking on different shapes were obtained. Fibrous AgNWs are formed by using high molecular weight polyvinylpyrrolidone (PVP). These results showed a possibility of developing the polymer electrode with high conductivity, high flexibility and transparence.

Abe, Yuta; Gong, Jin; Furukawa, Hidemitsu

2013-04-01

134

Gel transitions in colloidal suspensions  

CERN Document Server

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

135

Chitosan: Gels and Interfacial Properties  

Directory of Open Access Journals (Sweden)

Full Text Available Chitosan is a unique biopolymer in the respect that it is abundant, cationic, low-toxic, non-immunogenic and biodegradable. The relative occurrence of the two monomeric building units (N-acetyl-glucosamine and d-glucosamine is crucial to whether chitosan is predominantly an ampholyte or predominantly a polyelectrolyte at acidic pH-values. The chemical composition is not only crucial to its surface activity properties, but also to whether and why chitosan can undergo a sol–gel transition. This review gives an overview of chitosan hydrogels and their biomedical applications, e.g., in tissue engineering and drug delivery, as well as the chitosan’s surface activity and its role in emulsion formation, stabilization and destabilization. Previously unpublished original data where chitosan acts as an emulsifier and flocculant are presented and discussed, showing that highly-acetylated chitosans can act both as an emulsifier and as a flocculant.

Julie Nilsen-Nygaard

2015-03-01

136

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 contd 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

137

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.

138

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

139

21 CFR 524.660b - Dimethyl sulfoxide gel.  

Science.gov (United States)

... 2010-04-01 false Dimethyl sulfoxide gel. 524.660b Section 524.660b Food and...ANIMAL DRUGS § 524.660b Dimethyl sulfoxide gel. (a) Specifications. Dimethyl sulfoxide gel, veterinary contains 90 percent dimethyl...

2010-04-01

140

21 CFR 872.1730 - Electrode gel for pulp testers.  

Science.gov (United States)

...2010-04-01 false Electrode gel for pulp testers. 872.1730 Section 872.1730 ...§ 872.1730 Electrode gel for pulp testers. (a) Identification. An electrode gel for pulp testers is a device intended to be applied...

2010-04-01

141

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

International Nuclear Information System (INIS)

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

142

Analysis of gel heterogeneities on a local level  

Science.gov (United States)

We study the heterogeneity of gels near the sol-gel transition through measurements of the spatial variations in gel strength. The correlated motion of fluorescent polystyrene microspheres suspended in gels is measured via two-point microrheology. Analysis of this correlated motion provides a local measure of gel heterogeneity. Additionally, we divide the images into micron-wide squares and determine how rheological properties spatially vary as a function of gel concentration. Our results imply that weaker gels exhibit more heterogeneity than stronger gels.

Boyne, Philip; Lechenault, Frederic; Daniels, Karen

2008-10-01

143

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

2003-12-23

144

Sol-gel technology for biomedical engineering  

International Nuclear Information System (INIS)

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

145

Gel phantom in selective laser phototherapy  

Science.gov (United States)

Tissue-simulating gel phantoms have been used in selective laser photothermal interaction. The gelatin phantom provides a uniform tissue-simulating medium for analyzing thermal performance under laser radiation. The gelatin phantom gel is used particularly in measurements of thermal reactions in laser thermology. The gelatin phantom is made from gelatin and Liposyn. A special gel sphere with Indocyanine Green (ICG) laser absorption enhancement dye is embedded in normal gel to simulate the dye-enhanced tumor in normal tissue. The concentration of ICG within the dye sphere is optimized using simulation for selective phototherapy. As a first attempt, the concentration of ICG and laser power density was optimized using a temperature ratio of target tissue versus surrounding tissue. The gel thermal performance is also monitored using MRI thermology imaging technology. The thermal imaging shows in vivo, 3D temperature mapping inside the gel. The study of thermal distribution using gel phantom provides information to guide the future selective laser photothermal thermal therapy.

Chen, Yichao; Bailey, Christopher A.; Cowan, Thomas M.; Wu, Feng; Liu, Hong; Towner, Rheal A.; Chen, Wei R.

2008-02-01

146

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

147

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

148

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.

2001-04-01

149

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

Science.gov (United States)

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

Vandecasteele, Jan; De Deene, Yves

2013-09-01

150

Phase Transitions in Lyotropic Nematic Gels  

CERN Document Server

In this paper, we discuss the equilibrium phases and collapse transitions of a lyotropic nematic gel immersed in an isotropic solvent. A nematic gel consists of a cross-linked polymer network with rod-like molecules embedded in it. Upon decreasing the quality of the solvent, we find that a lyotropic nematic gel undergoes a discontinuous volume change accompanied by an isotropic-nematic transition. We also present phase diagrams that these systems may exhibit. In particular, we show that coexistence of two isotropic phases, of two nematic phases, or of an isotropic and a nematic phase can occur.

Lacoste, D; Lubenskii, T C

2002-01-01

151

Reusable gels for germanium-68 sources  

International Nuclear Information System (INIS)

Two water-soluble gels, gelatin and Carbowax, were mixed with radioactive 68Ge solutions and evaluated for their use as long-lived (half-life, 280 days) radioactive sources. These gels melt at 40-50oC and solidify at room temperature. The amount of 68Ge mixed with them can be increased or decreased as needed, eliminating waste of 68Ge. These gel sources also may replace short-lived 68Ga (half-life 68 min) as attenuation correction sources in positron emission tomography (PET) and reduce frequency of source preparation, thus reducing exposure of PET operators to radiation. (author)

152

Reaction-induced swelling of ionic gels.  

Science.gov (United States)

A chemomechanical theory is proposed to describe the dynamic behavior and response time of ionic gels. The large deformation of these gels accompanied by the migration of mobile ions is driven by a common non-equilibrium chemical reaction. The theoretical model was validated using existing experimental data. Further investigations showed that the dynamic deformation and response time of an ionic gel are dependent on the concentration of reactive and non-reactive ions, the time of exposure to external stimuli, the initial state and the density of ionizable groups on the polymer chains. PMID:25409653

Liu, ShaoBao; Wang, PengFei; Huang, GuoYou; Wang, Lin; Zhou, JinXiong; Lu, Tian Jian; Xu, Feng; Lin, Min

2015-01-21

153

Magnetization transfer in polymer gel dosimeters  

Science.gov (United States)

Radiation dose distributions in polymer gel dosimeters can be quantified using various MRI methods. Currently, measurements of R2 are in common use for measuring doses. The dose response mechanism is believed to involve magnetization exchange between the polymer formed by radiation and the solvent in the gel. In this paper we used quantitative measurements of magnetization transfer (MT) to characterize polymer gels before and after irradiation to better understand their dose response, and to explore the potential advantages of imaging based on MT.

Whitney, Heather M.; Gochberg, Daniel F.; Gore, John C.

2006-12-01

154

Nucleation and growth of thermoreversible polymer gels  

Science.gov (United States)

We study the spatiotemporal low-frequency microrheology of a gelatin gel during the sol-gel transition after a fast temperature quench by tracking the motion of embedded colloidal particles. From the particle dynamics two different mechanisms responsible for the gelation of the sol phase can be identified: a fast process associated to the local nucleation of triple helices and a slow fiber growth triggered by presence of an intact network. We associate the latter to a gelation front propagating into the sol phase whose speed depends linearly on the quench depth and which accelerates the local rate of the sol-gel transition.

Gomez-Solano, J. R.; Blickle, V.; Bechinger, C.

2013-01-01

155

Sorption of uranyl ions on alumosilicate gels  

International Nuclear Information System (INIS)

Sorption of uranyl ions on alumosilicate gels from 0.09 mol/l KCl solutions is studied experimentally. It is established that alumosilicate gels may sorbate considerable quantities of uranyl ions and efficiency of their sorption increases when acidity of solutions decreases. Presence of dissolved carbonates does not effect substantially on uranium adsorption in spite of well-known uranyl ions ability to form strong carbonate complexes. High efficiency of uranyl ions sorption permits to use alumosilicate gels in creation of artificial geochemical barriers for underground water protection from uranium

156

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

157

Molecular approach to understanding and controlling morbillivirus infections  

International Nuclear Information System (INIS)

Rapid and accurate diagnosis is the most important factor which will determine the success of the current efforts to achieve global eradication of rinderpest. Improved diagnostic capabilities have great relevance for this programme, and molecular biology has provided many valuable new techniques which have been adapted for use in diagnostic and epidemiological studies on viruses. Nucleic acid probe hybridization and monoclonal antibody based ELISAs, which are more sensitive and more specific than classic diagnostic techniques such as agar gel immunodiffusion (AGID) and complement fixation, have proved their usefulness in recent years. However, the most significant advance has been the introduction of the polymerase chain reaction for the detection and identification of disease causing pathogens of medical and veterinary importance. This technique has revolutionized understanding of the epidemiology of rinderpest and other morbiliviruses. Molecular biology has also produced a new generation of recombinant vaccines which will be of use in controlling rinderpest and other morbillivirus diseases, and the molecular basis of morbillivirus pathogenicity is being studied using newly perfected techniques to obtain live virus from DNA copies of their genomes. (author)

158

Prevalence of Gumboro disease in vaccinated and non-vaccinated village chickens in Egypt  

International Nuclear Information System (INIS)

In order to investigate the incidence of Gumboro disease virus (IBDV) in village poultry in Egypt, 3000 one-day-old Balady chicks were distributed to 60 householders keeping free- ranging chicken (traditional) with an average of 50 chicks/ household. These were put under observed from one-day-old until seventy days of age and visited once a week. On 30 of these household farms the one-day-old chicken were vaccinated before delivery with an intermediate IBDV strain while the chicken on the other 30 farms were not vaccinated. Fifteen of each vaccinated and unvaccinated householder farms had other avian species while the other fifteen of each vaccinated and unvaccinated householders had not. The clinical symptoms, post-mortem and serological results using the Agar Gel Immuno-diffusion test (AGID) revealed that Gumboro disease is one of the most important diseases in rural chicken. Mortality rates were very high (5-32%) and decreasing body weights due to IBDV infection were significant, especially in chicken reared with other avian species. Results from the survey showed the significant efficacy of IBDV classical vaccine in one day old chicken. It showed a decrease in mortality and an increase in body weight gain on vaccinated farms independent whether they were kept with other avian species. Vaccination programs to control Gumboro disease would be an advantage in traditional poultry farms. (author)

159

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

160

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

International Nuclear Information System (INIS)

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(OC2H5)4 and TiCl4 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

161

Mobility of microparticles in protein gel  

International Nuclear Information System (INIS)

The hematite Fe2O3 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.

162

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

163

Functional gels based on chemically modified graphenes.  

Science.gov (United States)

Chemically modified graphene (CMG) materials have been extensively studied because of their unique structures, excellent properties, and potential applications in energy storage and conversion, catalysis, and environment remediation. However, the unique two-dimensional structure and amphiphilicity make CMG sheets easily restack into irregular aggregates, which greatly reduces their accessible surface area, and thereby deteriorates their performance in practical applications. To exploit their inherent properties fully, CMGs usually have to be fabricated or assembled into functional gels with desired three-dimensional (3D) interconnected porous microstructures. In this review, we summarize the recent achievements in the synthesis of CMG-based functional gels, including hydrogels, organogels, aerogels, and their composites. The mechanisms of gel formation and the applications of these functional gels will also be discussed. PMID:24659376

Li, Chun; Shi, Gaoquan

2014-06-25

164

Corrosive thixotropic gels for nuclear surface decontamination  

International Nuclear Information System (INIS)

Corrosive organo-mineral thixotropic gels have been developed by the laboratory of molecular aggregates and inorganic materials (LAMMI/CNRS Montpellier 2 univ., France) in collaboration with the society of techniques in ionising environment. These gels allow the solubilization of the radioactive elements localized on the surface of contaminated nuclear parts. They are made of cerium IV salts in a concentrated nitric acid solution with sub-micron silica particulates, in association with poly-oxy-ethylene-glycol or poly-acrylic acid as wetting agent. A airless device is used to project the gel on the surface to be treated and water under pressure can easily remove the gel after some few hours of action. The liquid effluents are pumped for further processing. Short note. (J.S.)

165

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

166

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

167

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)

168

Formation of Anisotropic Block Copolymer Gels  

Science.gov (United States)

Anisotropic, fibrillar gels are important in a variety of processes. Biomineralization is one example, where the mineralization process often occurs within a matrix of collagen or chitin fibers that trap the mineral precursors and direct the mineralization process. We wish to replicate this type of behavior within block copolymer gels. Particularly, we are interested in employing gels composed of cylindrical micelles, which are anisotropic and closely mimic biological fibers. Micelle geometry is controlled in our system by manipulating the ratio of molecular weights of the two blocks and by controlling the detailed thermal processing history of the copolymer solutions. Small-Angle X-ray Scattering and Dynamic Light Scattering are used to determine the temperature dependence of the gel formation process. Initial experiments are based on a thermally-reversible alcohol-soluble system, that can be subsequently converted to a water soluble system by hydrolysis of a poly(t-butyl methacrylate) block to a poly (methacrylic acid) block.

Liaw, Chya Yan; Shull, Kenneth; Henderson, Kevin; Joester, Derk

2011-03-01

169

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

OpenAIRE

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

170

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-09-21

171

DEVELOPMENT OF MELOXICAM SODIUM TRANSDERMAL GEL  

OpenAIRE

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...

Barhate, Dr Shashikant D.

2010-01-01

172

Carbon gels derived from natural resources  

OpenAIRE

[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

173

PRONIOSOMAL GEL OF FLURBIPROFEN: FORMULATION AND EVALUATION  

OpenAIRE

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 tra...

Sk, Prajapati; Kumar S.; Vk, Sahu; Prakash G

2012-01-01

174

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

175

Drying and Rehydration of Calcium Alginate Gels:  

OpenAIRE

In this paper, we study the rehydration properties of air-dried calcium alginate gel beads. Rehydration is shown to depend on alginate source (i.e. mannuronic to guluronic acid ratio) and the salt concentration in the rehydration medium. Rehydration curves are described adequately by the empirical Weibull equation. Wide-angle X-ray diffraction measurements are performed to obtain information on the microstructure of dried alginate gels. The X-ray diffraction patterns provide evidence for form...

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

2008-01-01

176

Particle size analysis of PAGAT gel dosimetry  

Science.gov (United States)

This work represents the response of PAGAT gel dosimeter using UV-Visible Spectrophotometry. The particle size and optimal wavelength of the gel sample were analyzed from the obtained spectrum. In addition, the compressibility was estimated using Ultrasonic Interferometer. The results showed that the particle size of the PAGAT varied appreciably with respect to the dose applied but did not vary significantly with the post irradiation time.

Samuel, E. J. J.; Sathiyaraj, P.; Titus, D.; Kumar, D. S.

2015-01-01

177

Gel Electrophoresis of Gold-DNA Nanoconjugates  

OpenAIRE

Gold-DNA conjugates were investigated in detail by a comprehensive gel electrophoresis study based on 1200 gels. A controlled number of single-stranded DNA of different length was attached specifically via thiol-Au bonds to phosphine-stabilized colloidal gold nanoparticles. Alternatively, the surface of the gold particles was saturated with single stranded DNA of different length either specifically via thiol-Au bonds or by nonspecific adsorption. From the experimentally determined electropho...

Parak, W. J.; Alivisatos, A. P.; Sperling, R. A.; Pellegrino, T.

2008-01-01

178

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

OpenAIRE

Rennet-induced casein gels made from skim milk were studied rheologically. A scaling model or framework for describing the rheological behavior of gels is discussed and used for classification of the structure of casein gels. There are two main parameters in the model that describe the number of deformable links in a strand and the bendability of the links. In the model at least five types of gel structure can be distinguished. Application of the model to experimental data on rennet-induced c...

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

2002-01-01

179

A thermodynamic model of physical gels  

Science.gov (United States)

Physical gels are characterized by dynamic cross-links that are constantly created and broken, changing its state between solid and liquid under influence of environmental factors. This restructuring ability of physical gels makes them an important class of materials with many applications, such as in drug delivery. In this article, we present a thermodynamic model for physical gels that considers both the elastic properties of the network and the transient nature of the cross-links. The cross-links' reformation is captured through a connectivity tensor M at the microscopic level. The macroscopic quantities, such as the volume fraction of the monomer ?, number of monomers per cross-link s, and the number of cross-links per volume q, are defined by statistic averaging. A mean-field energy functional for the gel is constructed based on these variables. The equilibrium equations and the stress are obtained at the current state. We study the static thermodynamic properties of physical gels predicted by the model. We discuss the problems of un-constrained swelling and stress driven phase transitions of physical gels and describe the conditions under which these phenomena arise as functions of the bond activation energy Ea, polymer/solvent interaction parameter ?, and external stress p.

An, Yonghao; Solis, Francisco J.; Jiang, Hanqing

2010-12-01

180

Basic investigations on LCV micelle gel  

International Nuclear Information System (INIS)

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

181

Treatment of osteochondral injuries with platelet gel  

Scientific Electronic Library Online (English)

Full Text Available OBJECTIVES: Treatments for injured articular cartilage have not advanced to the point that efficient regeneration is possible. However, there has been an increase in the use of platelet-rich plasma for the treatment of several orthopedic disorders, including chondral injuries. Our hypothesis is tha [...] t the treatment of chondral injuries with platelet gel results in higher-quality repair tissue after 180 days compared with chondral injuries not treated with gel. METHODS: A controlled experimental laboratory study was performed on 30 male rabbits to evaluate osteochondral injury repair after treatment with or without platelet gel. Osteochondral injuries were surgically induced in both knees of each rabbit at the medial femoral condyle. The left knee injury was filled with the platelet gel, and the right knee was not treated. Microscopic analysis of both knee samples was performed after 180 days using a histological grading scale. RESULTS: The only histological evaluation criterion that was not significantly different between treatments was metachromasia. The group that was treated with platelet gel exhibited superior results in all other criteria (cell morphology, surface regularity, chondral thickness and repair tissue integration) and in the total score. CONCLUSION: The repair tissue was histologically superior after 180 days in the study group treated with platelet gel compared with the group of untreated injuries.

Marcus Vinicius, Danieli; Hamilton da Rosa, Pereira; Carlos Augusto de Sá, Carneiro; Sérgio Luiz, Felisbino; Elenice, Deffune.

2014-12-01

182

Ionic flexogelectric effect in polymeric gels  

Science.gov (United States)

Reported are a number of quantitative observations and analytical modeling of a new effect in ionic polymeric gels such as poly(2-acrylamido-2-methylpropanesulfonic acid) or PAMPS, polyacrylic acid plus sodium acrylate cross-linked with bisacrylamide (PAAM) or various chemically-doped combinations of polyacrylic acid plus polyvinylalcohol(PAA-PVA). This new effect, hereafter, referred to as "Flexogelectric Effect" is basically the inverse of the effect originally reported in 1965 by three GE researchers, namely, Hamlen, Kent and Shafer in which the imposition of an electric field on an ionic polymeric gel fiber produced extension or contraction. Here, it is shown , both theoretically and experimentally, that mechanically induced nonhomogeneous deformations, and in particular bending of strips of such ionic gels can produce an electric field and the associated voltage. For typical samples of such gels (4x4x4Omm) with copper or platinum foil electrodes snugly contacting a pair of opposite sides (4x4Omm) of the strip, the difference in voltage measured between the electrodes for extreme bending configurations of the gel is typically in the 10's of milivolts range. This voltage difference which is quite significant for many engineering applications, such as large strain and deformation sensing, is still an order of magnitude smaller than the voltage necessary to induce similar deformations in the gel itself. A plausible explanation is also presented for such discrepancies.

Shahinpoor, Mohsen

1996-04-01

183

Fricke xylenol gel energy dependence  

International Nuclear Information System (INIS)

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

184

Natural gels in the Yucca Mountain Area, Nevada, USA  

International Nuclear Information System (INIS)

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

185

Natural gels in the Yucca Mountain Area, Nevada, USA  

Energy Technology Data Exchange (ETDEWEB)

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

Levy, S.S.

1991-12-31

186

Formulation and study of decontamination gels adhering to wall  

International Nuclear Information System (INIS)

The aim of this work is to establish relations between structure and rheological properties, adhesion and drying of a decontamination gel used for the cleansing of spent fuel reprocessing plants. Are successively described here: the formulation of the gels, the rheological behaviour, the relation existing between the drying and the efficiency of the gel, the adhesion of the gel. (O.M.)

187

Interaction between hepatocytes and collagen gel in hollow fibers  

OpenAIRE

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

188

Characterization of schistosome antigens by SDS-polyacrylamide gel electrophoresis  

International Nuclear Information System (INIS)

Separation of polypeptides by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) is based upon the relationship between the electrophoretic mobility of SDS-protein complexes and their molecular weights. Tegumental proteins extracted from Schistosoma mansoni have been analyzed by SDS-PAGE using slab gels by a number of investigators. Valuable information has also been obtained using tube gels to analyze radiolabeled proteins. The procedures for electrophoresis using tube gels and electrophoresis using gradient slab gels are described

189

Recycling of superfine resolution agarose gel.  

Science.gov (United States)

Genetic markers are now routinely used in a wide range of applications, from forensic DNA analysis to marker-assisted plant and animal breeding. The usual practice in such work is to extract the DNA, prime the markers of interest, and sift them out by electrically driving them through an appropriate matrix, usually a gel. The gels, made from polyacrylamide or agarose, are of high cost, limiting their greater applications in molecular marker work, especially in developing countries where such technology has great potential. Trials using superfine resolution (SFR) agarose for SSR marker screening showed that it is capable of resolving SSR loci and can be reused up to 14 times, thus greatly reducing the cost of each gel run. Furthermore, for certain applications, low concentrations of agarose sufficed and switching to lithium borate buffer, instead of the conventional Tris-borate-ethylenediaminetetraacetic acid buffer, will further save time and cost. The 2.5% gel was prepared following the Agarose SFR(TM) manual by adding 2.5 g agarose powder into 100 mL 1X lithium borate buffer in a 250-mL flask with rapid stirring. Two midigels (105 x 83 mm, 17 wells) or 4 minigels (50 x 83 mm, 8 wells), 4 mm thickness can be prepared from 100 mL gel solution. A total of 1680 PCR products amplified using 140 SSR markers from oil palm DNA samples were tested in this study using SFR recycled gel. As average, the gel can be recycled 8 times with good resolution, but can be recycled up to 14 times before the resolutions get blurred. PMID:23546970

Seng, T-Y; Singh, R; Faridah, Q Z; Tan, S-G; Alwee, S S R S

2013-01-01

190

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

OpenAIRE

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

191

Reprogramming cellular phenotype by soft collagen gels.  

Science.gov (United States)

A variety of cell types exhibit phenotype changes in response to the mechanical stiffness of the substrate. Many cells excluding neurons display an increase in the spread area, actin stress fiber formation and larger focal adhesion complexes as substrate stiffness increases in a sparsely populated culture. Cell proliferation is also known to directly correlate with these phenotype changes/changes in substrate stiffness. Augmented spreading and proliferation on stiffer substrates require nuclear transcriptional regulator YAP (Yes associated protein) localization in the cell nucleus and is tightly coupled to larger traction force generation. In this study, we show that different types of fibroblasts can exhibit spread morphology, well defined actin stress fibers, and larger focal adhesions even on very soft collagen gels (modulus in hundreds of Pascals) as if they are on hard glass substrates (modulus in GPa, several orders of magnitude higher). Strikingly, we show, for the first time, that augmented spreading and other hard substrate cytoskeleton architectures on soft collagen gels are not correlated with the cell proliferation pattern and do not require YAP localization in the cell nucleus. Finally, we examine the response of human colon carcinoma (HCT-8) cells on soft collagen gels. Recent studies show that human colon carcinoma (HCT-8) cells form multicellular clusters by 2-3 days when cultured on soft polyacrylamide (PA) gels with a wide range of stiffness (0.5-50 kPa) and coated with an extracellular matrix, ECM (collagen monomer/fibronectin). These clusters show limited spreading/wetting on PA gels, form 3D structures at the edges, and eventually display a remarkable, dissociative metastasis like phenotype (MLP), i.e., epithelial to rounded morphological transition after a week of culture on PA gels only, but not on collagen monomer coated stiff polystyrene/glass where they exhibit enhanced wetting and form confluent monolayers. Here, we show that HCT-8 cell clusters also show augmented spreading/wetting on soft collagen gels and eventually form confluent monolayers as on rigid glass substrates and MLP is completely inhibited on soft collagen gels. Overall, these results suggest that cell-material interactions (soft collagen gels in this case) can induce cellular phenotype and cytoskeleton organization in a remarkably distinct manner compared to a classical synthetic polyacrylamide (PA) hydrogel cell culture model and may contribute in designing new functional biomaterials. PMID:25284029

Ali, M Yakut; Chuang, Chih-Yuan; Saif, M Taher A

2014-11-28

192

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

193

Sol-gel processing of ceramics  

International Nuclear Information System (INIS)

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

194

DNA DAMAGE QUANTITATION BY ALKALINE GEL ELECTROPHORESIS.  

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-03-24

195

Thixotropic corrosive gels for nuclear decontamination  

International Nuclear Information System (INIS)

Inspired by an industrial problem, this work consisted in the development of decontamination processes using corrosive gels for the treatment of metallic surfaces. The gels were formulated using a corrosive solution of a strong oxidizing reagent (Ce(IV)) as dissolving agent. This solution was stabilized in a concentrated acidic medium (nitric acid). To obtain a gel from this solution, we used a mineral support (fumed silica) and an organic coviscosing compound (nonionic surfactant). Nuclear requirements were carefully followed. The aim of this project was to prepare thixotropic gels which are liquid under stress (vigorous shaking) to allow an easy splattering, and are solids when stationary to permit strong adhesion to any surface. The study of the rheological properties of these gels was completed by the quantitative as well as qualitative measurements of their corrosive abilities: corrosion control, surface comparison carried out before and after treatment by electron microscopy techniques. The chemical behaviour in solution was also studied, particularly the chemical behaviour of the organic coviscosing agent and the oxidizing reagent. The structure of a by product, (NH4)3Ce2(NO3)9, was determined using powder X-ray diffraction techniques. During the past two years, these processes have been used industrially both in France and abroad. As a conclusion, these industrial results are briefly presented. (author)results are briefly presented. (author)

196

Effectiveness of Gel Repellents on Feral Pigeons  

Directory of Open Access Journals (Sweden)

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

Birte Stock

2013-12-01

197

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.

Luz Elena, Cano; Angela, Restrepo.

1987-10-01

198

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 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.

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

2013-04-01

199

Low-Reynolds number swimming in gels  

CERN Document Server

Many microorganisms swim through gels, materials with nonzero zero-frequency elastic shear modulus, such as mucus. Biological gels are typically heterogeneous, containing both a structural scaffold (network) and a fluid solvent. We analyze the swimming of an infinite sheet undergoing transverse traveling wave deformations in the "two-fluid" model of a gel, which treats the network and solvent as two coupled elastic and viscous continuum phases. We show that geometric nonlinearities must be incorporated to obtain physically meaningful results. We identify a transition between regimes where the network deforms to follow solvent flows and where the network is stationary. Swimming speeds can be enhanced relative to Newtonian fluids when the network is stationary. Compressibility effects can also enhance swimming velocities. Finally, microscopic details of sheet-network interactions influence the boundary conditions between the sheet and network. The nature of these boundary conditions significantly impacts swimmi...

Fu, Henry C; Powers, Thomas R

2010-01-01

200

Cooperative Processes in Restructuring Gel Networks  

Science.gov (United States)

Colloidal gel networks are disordered elastic solids that can form even in extremely dilute particle suspensions. Similarly to other network-forming soft materials, including many with important biological function or technological potential, they can locally restructure via breaking and reforming interparticle bonds. Although controlling the link between local restructuring and mechanical response bears enormous potential for designing smart nanocomposites, there is at present little understanding of how local bond changes affect the dynamics of the gel network and the stress transmission through it. Here, using numerical simulations of a model system and a space-resolved analysis of dynamical heterogeneities, we show that bond breaking has non-local consequences and induces cooperative relaxation further away along the network. This provides explicit microscopic insight into why non-local constitutive relations are required to rationalize the non-trivial mechanical response of colloidal gels.

Colombo, Jader; Widmer-Cooper, Asaph; Del Gado, Emanuela

2013-03-01

201

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)

202

Carbon gels derived from natural resources  

Directory of Open Access Journals (Sweden)

Full Text Available Most carbon gels investigated so far and reportedin the literature were prepared from resorcinolcrosslinked with formaldehyde in water, and weregenerally dried with supercritical CO2 before beingpyrolysed. In the present paper, through someselected examples, we show how valuable carbongels can be derived from other phenolic resourceshaving a natural origin. Special emphasis is givento tannin and lignin, both derived from wood, aspotential precursors of carbon aero- and cryogels.However, natural compounds not obeying the usualconcepts of sol-gel chemistry may also be used forpreparing carbon gels, such as cellulose, and evenglucose. In the latter case, hydrothermal treatmentforces the phase separation to occur, and leads tomonoliths which can be advantageously convertedinto carbon aerogels by supercritical drying andsubsequent pyrolysis.

A. Celzard

2012-12-01

203

Charge screening effects in charged gel  

International Nuclear Information System (INIS)

Structures of micro-phase separation are studied in the aqueous gel consisting of hydrophobic and hydrophilic monomers with charged groups. Small angle neutron scattering (SANS) measurements are applied for nano-scale structures of N-isopropylacrylamide-sodium acrylate (NIPA-SA) gel with Na+ pair ions and N-isopropylacrylamide-acrylic acid (NIPA-AAc) gel with H+ pair ions. Structural size in micro-phase separation in aqueous gel is presumed to be dependent of the difference of hydrophilicity between hydrophilic and hydrophobic regions. Since hydrophilicity of charged groups is changed by electrolytic dissociation of themselves, screening of charges of charged groups in gel causes the change of electrolytic dissociation and hydrophilicity. Attention is paid for the structural change resulted from above change of electrolytic dissociation and hydrophilicity. The screening of charged groups depends on pair ions. Correlation between difference of the pair ions and nano-scale structures is measured by SANS. Water evaporates initially from the vicinity of high hydrophobic NIPA and condenses around the vicinity of high hydrophilic carboxy groups (CG). As the result of this, a phase separation is caused in the gel at this stage. Further dehydration reduces water around the vicinity of CG. At this stage, CG in the case of the H+ pair ions does not dissociate and the structure of the micro-phase separation annihilates. On the other hand, in caseon annihilates. On the other hand, in case of the Na+ pair ions CG dissociates and the structure of the micro-phase separation is observed in a fairly progressive stage of dehydration. (Y. Kazumata)

204

Recent developments in polymer gel dosimetry  

International Nuclear Information System (INIS)

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

205

Connectivity in sol-gel silica glasses  

Directory of Open Access Journals (Sweden)

Full Text Available In this work it is carried out a review on structural parameters related to the evaluation of pore connectivity of nanostructures. The work describes parameters and methods of evaluation of geometric parameters. The concepts of connectivity are applied to silica gels and glasses obtained from sol-gel process. The study of pores connectivity was carried out using a combination of geometric modeling and experimental evaluation of specific surface area and pore volume. The permeability of the pore structure is evaluated and a permeability geometric factor, Pg, is proposed.

Vasconcelos Wander L.

1998-01-01

206

Hybrid sol-gel optical materials  

Science.gov (United States)

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

Zeigler, John M. (Albuquerque, NM)

1993-01-01

207

Contractile stress generation by actomyosin gels.  

Science.gov (United States)

The tension generated by randomly distributed myosin minifilaments in an actin gel is evaluated using a rigorous theorem relating the surface forces acting on the gel to the forces exerted by the myosins. The maximum tension generated per myosin depends strongly on the lengths of the myosin minifilaments and the actin filaments. The result is used to place an upper bound on the tension that can be generated during cytokinesis. It is found that actomyosin contraction by itself generates too little force for ring contraction during cytokinesis unless the actin filaments are tightly crosslinked into inextensible units much longer than a single actin filament. PMID:17279944

Carlsson, A E

2006-11-01

208

Determining optimal gel sensitivity in optical CT scanning of gel dosimeters  

International Nuclear Information System (INIS)

A method for determining the gel sensitivity that is necessary for obtaining optimal image contrast in optical CT scanning of gel dosimeters is presented. The effective dynamic range of the OCTOPUS-ONE trade mark sign research scanner (MGS Research, Inc., Madison, CT) is analyzed. Optical density increments for selected straight-line paths across a gel cylinder to be scanned are calculated based on the optical properties of the polymer gel and the dose distribution from a commercial treatment planning system (Cadplan, Varian Corporation, Palo Alto, CA). Maximum optical density increment across the entire gel is obtained by searching the gel cylinder over a set of transverse planes at different rotational angles. The application of this quantity as a criterion for optimizing the quality of the optical CT scanning is demonstrated through dose verification of two representative treatment plans. When the MU dependence of the dose distribution for a treatment plan is linear, as is the case for static field irradiation, it is possible to scale the treatment plan such that the intensity variation of the signals received by the photodetector spans its entire dynamic range. For treatment plans that are possibly nonlinear, IMRT plans, for example, modification of the sensitivity of the gel material is necessary for the high-dose signals to be collected at a certain signal-to-noise ratio. Results obtained using the optimized CT scanning approach are compared with those from the approach are compared with those from the treatment planning system and the film measurement

209

Multiple-phase behavior and memory effect of polymer gel  

CERN Document Server

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

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

2002-01-01

210

The mechanism and properties of acid-coagulated milk gels  

Directory of Open Access Journals (Sweden)

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

Chanokphat Phadungath

2005-03-01

211

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

International Nuclear Information System (INIS)

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

212

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)

213

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

Science.gov (United States)

...Bioequivalence Recommendations for Metronidazole Vaginal Gel; Availability AGENCY...Bioequivalence Recommendations for Metronidazole Vaginal Gel.'' The guidance provides...applications (ANDAs) for metronidazole vaginal gel. DATES: Although you...

2013-03-29

214

(3-Mercaptopropyl)trimethoxysilane-derived Porous Gel Monolith via Thioacetal Reaction-Assisted Sol-Gel Route  

International Nuclear Information System (INIS)

Porous gel monolith was synthesized by reacting (3-mercaptopropyl)trimethoxysilane (MPTMS) with acetone on acidic conditions. It is known that MPTMS itself is difficult to turn into gel on acidic conditions and instead oligomers are obtained owing to the large mercaptopropyl group. In our system, the gels were obtained since acetone worked as a cross-linker via thioacetal reaction. Additionally, Au ions were selectively adsorbed on the obtained gel. When an obtained white gel was soaked in a chloroauric acid solution, the gel turned brown and was getting dark depending on the soaked time; on the other hand, the color of the solution turned from yellow to colorless.

215

(3-Mercaptopropyl)trimethoxysilane-derived Porous Gel Monolith via Thioacetal Reaction-Assisted Sol-Gel Route  

Energy Technology Data Exchange (ETDEWEB)

Porous gel monolith was synthesized by reacting (3-mercaptopropyl)trimethoxysilane (MPTMS) with acetone on acidic conditions. It is known that MPTMS itself is difficult to turn into gel on acidic conditions and instead oligomers are obtained owing to the large mercaptopropyl group. In our system, the gels were obtained since acetone worked as a cross-linker via thioacetal reaction. Additionally, Au ions were selectively adsorbed on the obtained gel. When an obtained white gel was soaked in a chloroauric acid solution, the gel turned brown and was getting dark depending on the soaked time; on the other hand, the color of the solution turned from yellow to colorless.

Ito, S; Nishi, M; Kurahashi, T; Matsubara, S; Shimotsuma, Y; Miura, K; Hirao, K [Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan); Kanamori, K; Nakanishi, K, E-mail: west@collon1.kuic.kyoto-u.ac.jp [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan)

2011-10-29

216

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

217

Matching Two-dimensional Gel Electrophoresis' Spots  

DEFF Research Database (Denmark)

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

Dos Anjos, Anto?nio; AL-Tam, Faroq

2012-01-01

218

Growth of hydroxyapatite nanoparticles on silica gels.  

Science.gov (United States)

Synthetic, hydroxyapatite nanoparticles were grown on the surface of silica gels. The synthesis of those nanoparticles was obtained by immersing silica gels in a simulated body fluid (SBF) at 37 degrees C. The SBF was replaced every week to keep constant the Ca and P ion concentration and subsequent growth of hydroxyapatite was evaluated after 1-6 weeks of total soaking time in SBF. Hydroxyapatite nanoparticles were observed by scanning electron microscopy (SEM) on the surface of silica gel samples and confirmed by energy dispersive X-ray spectroscopy (EDS), Fourier Transform Infra Red Spectroscopy (FTIR) and powder X-ray Diffractometry (XRD) analysis. These particles show a regular shape and uniform size every week, keeping within the nanoscale always. Both the size and morphology of hydroxyapatite nanoparticles obtained are the result of the use of different chemical additives in the synthesis of silica gels, since they affect the liquid-to-solid interface, and the growth could correspond to a diffusion limited aggregation (DLA) process. A more detailed analysis, with higher magnifications, showed that hydroxyapatite nanoparticles are not solid spheres, showing a branched texture and their size depends on the scale and resolution of the measure instrument. PMID:21770224

Rivera-Muñoz, E M; Huirache-Acuña, R; Velázquez, R; Alonso-Núñez, G; Eguía-Eguía, S

2011-06-01

219

Gel bead composition for metal adsorption  

Science.gov (United States)

The invention is a gel bead comprising propylene glycol alginate and bone gelatin and is capable of removing metals such as Sr and Cs from solution without adding other adsorbents. The invention could have application to the nuclear industry's waste removal activities.

Scott, Charles D. (Oak Ridge, TN); Woodward, Charlene A. (Oak Ridge, TN); Byers, Charles H. (Oak Ridge, TN)

1991-01-01

220

Preparation for Pouring an Agarose Gel  

Science.gov (United States)

This video from CUNY Kingsborough Community College describes the technique of preparing to pour 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 3:22.

Hinkley, Craig

221

Staining and Imaging an Agarose Gel  

Science.gov (United States)

This video from CUNY Kingsborough Community College shows the process of staining and imaging 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 3:18.

Hinkley, Craig

222

Thermal Decomposition Characteristics of ADU Gel Spheres  

International Nuclear Information System (INIS)

HTGR nuclear fuel uses a modified sol.gel GSP (Gel Supported Precipitation) method, which is a wet method used in most countries. ADU(Ammonium DiUranate) gel particles fabricated in this way pass through thermal treatments and become final UO2 microspheres. The washing characteristics such as washing volume, duration, and times during AWD(ageing, washing and drying) process after the spherical ADU gel particles preparation by the GSP method was studied. The VHTR (Very High Temperature Gas Reactor) is one of the reactor concepts in the Gen IV International Collaboration. Unlike light water reactor currently in use in Korea, a HTGR actually functions as a gas cooled reactor where the high temperature heat generated from nuclear fission in a reactor is cooled by He gas, with uranium dioxide (UO2 is globally used) used as fuel for the nuclear fission. Generally, nuclear fuel used in a HTGR is fabricated into a TRISO (TRi.ISOtropic) structure that can prevent the leakage of nuclear fission products at high temperatures

223

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

224

Decontamination of radioactive uranium by chemical gels  

International Nuclear Information System (INIS)

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).HNO3 or HNO3 based solution for tile surfaces contaminated with uranium radionuclides were investigated

225

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

226

Gel Filtration Chromatography: A Laboratory Experiment.  

Science.gov (United States)

Describes a rapid, visual demonstration of protein separation by gel filtration chromatography. The procedure separates two highly colored proteins of different molecular weights on a Sephadex G-75 in 45 minutes. This time includes packing the column as well. Background information, reagents needed, procedures used, and results obtained are…

Hurlbut, Jeffrey A.; Schonbeck, Niels D.

1984-01-01

227

Gels and microgels for nanotechnological applications.  

Science.gov (United States)

In recent years, "smart" materials have been the focus of considerable interest, from both fundamental and applied perspectives. Polymer gels are within this category; they respond to specific environmental stimuli by changing their size. Thus, the internal structure, the refractive index, and the mechanical properties of the polymer network change. They are considered super absorbent materials, as they can absorb solvent up to several hundred times their own weight. They respond rapidly to local environmental variations, an important fact in device miniaturization and microsensor developments. As size changes are accompanied by changes in internal dimensions, microgels have found application as carriers of therapeutic drugs and as diagnostic agents. They have also been used as microreactors, optically active materials, for template synthesis of nanoparticles or fabrication of artificial muscle. In this paper we review a set of application based on the special features associated to this systems. Basic concepts on the physical-chemistry of gel swelling is first described, followed by different applications covering drug delivery, composite materials using polymer gels to modulate optical or magnetic and electrical properties, molecular imprinting, gel-based biosensors and polymer sensors and actuators used in the field of artificial muscles. PMID:19217018

Fernández-Barbero, Antonio; Suárez, Iván J; Sierra-Martín, B; Fernández-Nieves, A; de Las Nieves, F Javier; Marquez, Manuel; Rubio-Retama, J; López-Cabarcos, Enrique

2009-01-01

228

Metronidazole gel ineffective for minimally abnormal Pap.  

Science.gov (United States)

Empiric treatment of women with minimally abnormal Papanicolaou smears (limited by inflammation, benign, or reactive cellular changes) with 0.75% metronidazole vaginal gel is ineffective in yielding a higher rate of reversion to normal cytology when compared with no treatment. PMID:12540306

Smith, Catherine; Church, Lili

2003-01-01

229

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

230

Bioactive nanocrystalline sol-gel hydroxyapatite coatings.  

Science.gov (United States)

Sol-gel technology offers an alternative technique for producing bioactive surfaces for improved bone attachment. Previous work indicated that monophasic hydroxyapatite coatings were difficult to produce. In the present work hydroxyapatite was synthesized using the sol-gel technique with alkoxide precursors and the solution was allowed to age up to seven days prior to coating. It was found that, similar to the wet-chemical method of hydroxyapatite powder synthesis, an aging time is required to produce a pure hydroxyapatite phase. A methodology that has been successfully used to produce nanocrystalline hydroxyapatite thin film coatings via the sol-gel route on various substrates including alumina, Vycor glass, partially stabilized zirconia, Ti-6Al-4V alloy and single crystal MgO is described. Coatings produced on MgO substrates were characterized by X-ray diffraction and atomic force microscopy, while the analogous gels were examined with thermogravimetric and differential thermal analyses. The coatings were crack free and the surface was covered with small grains, of approximately 200 nm in size for samples fired to 1000 degrees C. Coating thickness varied between 70 and 1000 nm depending on the number of applied layers. PMID:15348113

Chai, C S; Ben-Nissan, B

1999-08-01

231

The repton model of gel electrophoresis  

OpenAIRE

We discuss the repton model of agarose gel electrophoresis of DNA. We review previous results, both analytic and numerical, as well as presenting a new numerical algorithm for the efficient simulation of the model, and suggesting a new approach to the model's analytic solution.

Barkema, G. T.; Newman, M. E. J.

1996-01-01

232

Aloe vera leaf gel: a review update.  

Science.gov (United States)

Research since the 1986 review has largely upheld the therapeutic claims made in the earlier papers and indeed extended them into other areas. Treatment of inflammation is still the key effect for most types of healing but it is now realized that this is a complex process and that many of its constituent processes may be addressed in different ways by different gel components. A common theme running though much recent research is the immunomodulatory properties of the gel polysaccharides, especially the acetylated mannans from Aloe vera, which are now a proprietary substance covered by many patents. There have also been, however, persistent reports of active glycoprotein fractions from both Aloe vera and Aloe arborescens. There are also cautionary investigations warning of possible allergic effects on some patients. Reports also describe antidiabetic, anticancer and antibiotic activities, so we may expect to see a widening use of aloe gel. Several reputable suppliers produce a stabilized aloe gel for use as itself or in formulations and there may be moves towards isolating and eventually providing verified active ingredients in dosable quantities PMID:10624859

Reynolds, T; Dweck, A C

1999-12-15

233

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

234

Sol-gel Application in the Environment.  

Czech Academy of Sciences Publication Activity Database

Maribor : Univerza v Mariboru, 2013. [Nanofuture. Maribor (SI), 03.02.2013-07.02.2013] R&D Projects: GA TA ?R TA01020804 Institutional support: RVO:67985858 Keywords : sol-gel methods * biosenzors * environment monitoring Subject RIV: CI - Industrial Chemistry, Chemical Engineering

Kaštánek, František; Šolcová, Olga; Maléterová, Ywetta

235

21 CFR 520.1453 - Moxidectin and praziquantel gel.  

Science.gov (United States)

...2010-04-01 false Moxidectin and praziquantel gel. 520.1453 Section 520...DRUGS § 520.1453 Moxidectin and praziquantel gel. (a) Specifications ...moxidectin and 125 mg (12.5 percent) praziquantel. (b) Sponsor . See No....

2010-04-01

236

21 CFR 520.1242f - Levamisole hydrochloride gel.  

Science.gov (United States)

...2010-04-01 false Levamisole hydrochloride gel. 520.1242f Section 520...DRUGS § 520.1242f Levamisole hydrochloride gel. (a) Specifications. The...containing 11.5 percent levamisole hydrochloride. (b) Sponsor. See No....

2010-04-01

237

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

International Nuclear Information System (INIS)

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.

238

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

239

Optimization of topical gels with betamethasone dipropionate: selection of gel forming and optimal cosolvent system.  

Science.gov (United States)

The purpose of these studies was to develop a 0.05% betamethasone gel characterized by physical-chemical stability and good release properties. The preliminary studies were designed to select the gel-forming agents and the excipients compatible with betamethasone dipropionate. In order to formulate a clear gel without particles of drug substances in suspension, a solvent system for the drug substance was selected. The content of drug substance released, the rheological and in vitro release tests were the tools used for the optimal formulation selection. A stable carbomer gel was obtained by solubilization of betamethasone dipropionate in a vehicle composed by 40% PEG 400, 10% ethanol and 5% Transcutol. PMID:21870764

B?i?an, Mariana; Lionte, Mihaela; Moisuc, L?cr?mioara; Gafi?anu, Eliza

2011-01-01

240

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

Science.gov (United States)

A dried gel material sterically entrapping nanoclusters of a catalytically active material and a process to make the material via an inverse micelle/sol-gel synthesis. A surfactant is mixed with an apolar solvent to form an inverse micelle solution. A salt of a catalytically active material, such as gold chloride, is added along with a silica gel precursor to the solution to form a mixture. To the mixture are then added a reducing agent for the purpose of reducing the gold in the gold chloride to atomic gold to form the nanoclusters and a condensing agent to form the gel which sterically entraps the nanoclusters. The nanoclusters are normally in the average size range of from 5-10 nm in diameter with a monodisperse size distribution.

Martino, Anthony (Albuquerque, NM); Yamanaka, Stacey A. (Dallas, TX); Kawola, Jeffrey S. (Albuquerque, NM); Showalter, Steven K. (Albuquerque, NM); Loy, Douglas A. (Albuquerque, NM)

1998-01-01

241

Ultraviolet absorption detection of DNA in gels  

International Nuclear Information System (INIS)

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

242

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

OpenAIRE

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

243

Continuous alumina gel fibers by sol-gel method using glycolic acid, aluminum nitrate and polyvinylpyrrolidone  

OpenAIRE

Continuous alumina fibers were prepared by sol-gel method. The spinning sol was obtained by mixing aluminum nitrate, glycolic acid and polyvinylpyrrolidone with a weight ratio of 10:3:1.5. Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to characterize the properties of the gel and ceramic fibers. The fibers with a uniform diameter and smooth surface were obtained by sintering at 1473K, and its main phase was indentified as ...

Hongbin Tan; Jianhua Zhang; Haiwa Bo

2011-01-01

244

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)

245

Gel-forming reagents and uses thereof for preparing microarrays  

Science.gov (United States)

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

Golova, Julia (Burr Ridge, IL); Chernov, Boris (Burr Ridge, IL); Perov, Alexander (Woodridge, IL)

2010-11-09

246

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 obtainedabsorbed 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

247

Mapping the Local Osmotic Modulus of Polymer Gels  

OpenAIRE

Polymer gels undergo volume phase transition in a thermodynamically poor solvent as a result of changes in molecular interactions. The osmotic pressure of gels, both synthetic and biological in nature, induces swelling and imparts the materials with the capacity to resist compressive loads. We have investigated the mechanical and swelling properties of poly(vinyl alcohol) (PVA) gels brought into the unstable state by changing the composition of the solvent. Chemically crosslinked PVA gels wer...

Horkay, Ferenc; Lin, David C.

2009-01-01

248

Photochromic properties of spirooxazine dyes in ormocer gels and coatings  

OpenAIRE

The wet- and "cold"-chemical characteristic of sol-gel process makes the sol-gel derived materials offer exciting potentials as hosts for photochromic dyes. In the present work, using mixed organically modified silicon alkoxides as starting compounds a novel ORMOCER material has been prepared via the sol-gel process as a host for spirooxazines. The photochromic properties of the dyes in the ORMOCER gel and coating are compared with those in ethanol. The experimental results show that both the...

Hou, Lisong; Mennig, Martin; Schmidt, Helmut K.

1992-01-01

249

Preparation and Evaluation of Topical Gel of Valdecoxib  

OpenAIRE

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 rele...

Jani Rupal; Jani Kaushal; Mallikarjuna, Setty C.; Patel Dipti

2010-01-01

250

Regioselective immobilization of short oligonucleotides to acrylic copolymer gels.  

OpenAIRE

Four types of polyacrylamide or polydimethyl-acrylamide gels for regioselective (by immobilization at the 3' end) of short oligonucleotides have been designed for use in manufacturing oligonucleotide microchips. Two of these supports contain amino or aldehyde groups in the gel, allowing coupling with oligonucleotides bearing aldehyde or amino groups, respectively, in the presence of a reducing agent. The aldehyde gel support showed a higher immobilization efficiency relative to the amino gel....

Timofeev, E.; Kochetkova, S. V.; Mirzabekov, A. D.; Florentiev, V. L.

1996-01-01

251

Metal-doped organic gels and method thereof  

Science.gov (United States)

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

Satcher, Jr., Joe H. (Patterson, CA); Baumann, Theodore F. (Tracy, CA)

2007-10-23

252

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

Scientific Electronic Library Online (English)

Full Text Available 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.

2191-21-01

253

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 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.

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

2013-09-01

254

ELISA FOR BOVINE SCHISTOSOMIASIS VACCINE EVALUATION: A PRELIMINARY REPORT / USO DO ELISA PARA AVALIAÇÃO DA RESPOSTA IMUNE EM BEZERROS VACINADOS CONTRA S. bovis: ESTUDO PRELIMINAR  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Seis bezerros foram imunizados com esquistossomuíde Schistosoma bovis irradiados com 3 ou 20 Kilorad (Krad) e três animais serviram de controles. Vinte e quatro semanas após a imunização três bezerros (um com 20Krad e dois do 3Krad grupo) foram desafiados com cercarias normais de S. bovis. A respost [...] a imune foi medida pela prova de imunodifusão em gel de ágar (IDGA) e a prova imunoenzimática (ELISA) usando como antígeno o parasita adulto. Quando a prova do IDGA foi usada linhas de precipitação foram observadas somente no soro dos animais desafiados. Usando o ELISA nos animais vacinados a resposta foi detectada pela primeira vez entre a segunda e a terceira semana com pique máximo entre 6-8 semana após a vacinação. A resposta imune dos três animais desafiados estava elevada as duas semanas após o desafio com pique entre a 8-10ª semana e permaneceu alto durante todo período do experimento. Este estudo sugere que o ELISA pode ser utilizado para o diagnóstico da esquistossomíase bovina. Abstract in english Six calves were immunized with schistosomula of Schistosoma bovis irradiated at 3 or 20 Kilorad (Krad) and three calves were kept as controls. Twenty four weeks post immunization, three calves (one from the 20 Krad and two from the 3 Krad group) were challenged with normal cercaria of S. bovis. The [...] immune response was monitored by agar gel immunodiffusion (AGID) and the Enzyme Linked Immunosorbent Assay (ELISA) using adult worm antigen. Using AGID, precipitin lines were observed only with sera from challenged animals. Using ELISA, the immune response of the vaccinated calves was first detected by 2-3 weeks, peaking by 6-8 weeks post vaccination. The immune response of the three challenged calves was elevated by 2 weeks post challenge, peaking at 8-10 weeks post challenge and remained high throughout the experimental period. This study suggests that ELISA could be used for diagnosis of bovine schistosomiasis.

Imadeldin Elamin, Aradaib; Babiker, Abbas; Bennie, Osburn; Hamid Omer, Bushara; Martin, Taylor.

1994-12-01

255

Formulation and method for preparing gels comprising hydrous hafnium oxide  

Energy Technology Data Exchange (ETDEWEB)

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

256

21 CFR 520.1720d - Phenylbutazone gel.  

Science.gov (United States)

...2010-04-01 2010-04-01 false Phenylbutazone gel. 520.1720d Section 520.1720d Food...ANIMAL DRUGS § 520.1720d Phenylbutazone gel. (a) Specifications. Each 30 grams of gel contains 4 grams of phenylbutazone....

2010-04-01

257

A low molecular weight hydrogel with unusual gel aging.  

Science.gov (United States)

We describe a dipeptide hydrogel with unusual aging characteristics. Over time, a transformation from a turbid gel to a transparent gel occurs which is initiated from the air-water interface. Here, we investigate this transition and discuss the implications of this aging on the bulk properties of the gel. PMID:25775220

Draper, Emily R; McDonald, Tom O; Adams, Dave J

2015-03-31

258

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

259

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

260

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

OpenAIRE

A dispersed particle gel (DPG) was successfully prepared from a polymer gel at room temperature. The polymer gel system, morphology, viscosity changes, size distribution, and zeta potential of DPG particles were investigated. The results showed that zirconium gel systems with different strengths can be cross-linked within 2.5 h at low temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) results showed that the particles wer...

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

2013-01-01

261

Radiological attenuation properties of normoxic polymer gel dosimeters  

Energy Technology Data Exchange (ETDEWEB)

Since the development of normoxic gels several others have been evaluated for dose response and spatial stability with MRI. Tetrakis (hydroxymethyl) phosphonium chloride (THP) has been used as an oxygen scavenger in MAGAT and PAGAT polymer gel dosimeters. X-ray CT has been used as an evaluation tool to measure dose response and dose distributions of irradiated polymer gel dosimeters. In this work the radiological attenuation properties of the PAGAT and MAGAT normoxic polymer gels are investigated as part of a feasibility study in using x-ray CT as an evaluation tool for normoxic polymer gel dosimeters.

Brindha, S [Department of Radiation Oncology, Christian Medical College, Vellore (India); Venning, A J [School of Physical and Chemical Sciences, Queensland University of Technology, QLD 4000 (Australia); Hill, B [Medical Physics Section, Biomedical Engineering Services, Canberra Hospital, ACT 2606 (Australia); Baldock, C [Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006 (Australia)

2004-01-01

262

Radiological attenuation properties of normoxic polymer gel dosimeters  

International Nuclear Information System (INIS)

Since the development of normoxic gels several others have been evaluated for dose response and spatial stability with MRI. Tetrakis (hydroxymethyl) phosphonium chloride (THP) has been used as an oxygen scavenger in MAGAT and PAGAT polymer gel dosimeters. X-ray CT has been used as an evaluation tool to measure dose response and dose distributions of irradiated polymer gel dosimeters. In this work the radiological attenuation properties of the PAGAT and MAGAT normoxic polymer gels are investigated as part of a feasibility study in using x-ray CT as an evaluation tool for normoxic polymer gel dosimeters

263

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.)

264

Molecular recognition in gels, monolayers, and solids  

Science.gov (United States)

This paper describes work in four areas: affinity electrophoresis of carbonic anhydrase in cross-linked polyacrylamide derived gels containing immobilized derivatives of aryl sulfonamides; inhibition of the hemagglutination of erythrocytes induced by influenza virus using water-soluble polyacrylamides bearing sialic acid groups; the application of self-assembled monolayers (SAMs) of alkyl thiolates on gold to the study of protein adsorption on organic surfaces; and the use of networks of hydrogen bonds to generate new classes of non-covalently assembled organic materials, both in solution and in crystals. This paper summarizes research in two areas of molecular recognition: affinity polymers and molecular self assembly. We illustrate these areas by examples drawn from affinity gel electrophoresis, soluble synthetic macromolecular inhibitors of binding of influenza virus to erythrocytes protein adsorption on self assembled monolayers and self assembling hydrogen bonded molecular aggregates.

Prime, Kevin L.; Chu, Yen-Ho; Schmid, Walther; Seto, Christopher T.; Chen, James K.

1991-12-01

265

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)

266

Fundamentals of MRI measurements for gel dosimetry  

International Nuclear Information System (INIS)

In radiotherapy gel dosimetry a humanoid phantom is irradiated according to the planned treatment of a patient. This results in a three-dimensional dose distribution. In order to read-out the gel dosimeter phantom, magnetic resonance imaging (MRI) is often used. Due to specific disturbances both the spatial and the dose reliability can be compromised. It is essential that the measurement sequence is optimized and that possible imaging artifacts are compensated in such a way that the proposed spatial and dose accuracy are met. In this review, several sources of disturbances are treated and compensation strategies are proposed. A code of good practice for the read-out technique is proposed. Finally, a tool for quality control of the imaging sequence is presented

267

Wick materials by sol-gel processing  

International Nuclear Information System (INIS)

In capillary pumped loops (CPL) devices, the fine porous wick, located in the evaporator, provides the means for passively pumping the fluid through the system, using surface tension forces exerted onto a liquid in a small diameter pore at the liquid/vapor interface. The Naval Research Laboratory's Materials Science and technology Division and Naval Center for Space Technology have been investigating the use of sol-gel processing for development of organically modified ceramic wicks with micron or submicron pores, high porosity, low thermal conductivity and structural flexibility. Gels with average pore sizes as small as 0.5 ?m, 30-80% continuous porosity, some flexibility and thermal stability to at least 473K were successfully prepared. Microstructures of these hybrids were examined by scanning electron microscopy (SEM), and some conventional wick property testing were performed

268

Ceramic sphere production by a gel casting  

International Nuclear Information System (INIS)

The technology of (Th,U)O2 microspheres production by gel casting and subsequente thermal treatment has been transferred from NUKEM CmbH 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?m) and the value of the specific surface (about 50 m2/g for calcined (Th,U)O2 and potentially higher than 200 m2/g for other ceramic materials). (Author)

269

Effectiveness of Gel Repellents on Feral Pigeons  

OpenAIRE

Millions of feral pigeons (Columba livia) live in close association with the human population in our cities. They pose serious health risks to humans and lead to high economic loss due to damage caused to buildings. Consequently, house owners and city authorities are not willing to allow pigeons on their buildings. While various avian repellents are regularly introduced onto the market, scientific proof of efficacy is lacking. This study aimed at testing the effectiveness of two avian gel rep...

Birte Stock; Daniel Haag-Wackernagel

2013-01-01

270

Photoswitchable gel assembly based on molecular recognition  

OpenAIRE

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

271

Films by sol-gel processes  

OpenAIRE

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

272

Gel Evolution in Oil Based Drilling Fluids  

OpenAIRE

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

273

3 D gel dosimetry - method review and our first experience  

International Nuclear Information System (INIS)

In this paper a preliminary results of new 3-dimensional gel dosimetry are presented. The dosimeter gel and its use together with nuclear magnetic resonance (NMR) is a new and promising tool and an attempt to satisfy the requirements of the ideal dosimetry system. NMR gel dosimetry is totally non-invasive. There is no need to introduce a probe into the phantom, nor it is necessary to remove part of the irradiated material for testing because the phantom itself forms the detector. The atomic composition and electron density of the gel are such that it is quite close to water-equivalence. The site of measurement is determined entirely by the measuring system, which can be programmed to scan the complete 3-dimensional dose distribution. NMR gel dosimetry can be divided based, on the composition of the gel detector into two groups: Fricke-infused gel dosimeter and polymer-gel dosimeter. Before starting with 3 D gel dosimetry two important quality factors of the NMR scanner had to be evaluated: spatial distortion effect and absolute and relative precision of the relaxation time measurements. Measurements of geometrical precision and R2 relaxation rates precision proved that our NMR scanner can be used for evaluation of gel dosimeters. Only preliminary measurements of polymer-gel dosimeters irradiated by different homogeneous doses (0-28 Gy) in 60Co gamma cell unit were carried out so far

274

Influence of elasticity on the syneresis properties of ?-carrageenan gels.  

Science.gov (United States)

Kappa-carrageenan hydrogels spontaneously release fluid (syneresis) under certain elasticity conditions, which depend on the temperature, the salt concentration in the gel (KCl) and the polysaccharide concentration. Strong and weak gels exhibit notably weak syneresis properties. The maximum syneresis was found at intermediate elasticity where the gel was neither strong nor weak. The variation in the gel composition indicated that the fluid is released according to the thermal retraction coefficient, which depends on the elasticity. Experiments revealed a dynamic equilibrium of the syneresis process where syneresis fluid was not withdrawn. However, once the fluid was removed from the gel surface, the release of solvent starts again if the elasticity is below the compressive pressure in the gel. Therefore, swelling of the gel is suggested as an explanation for the dynamic equilibrium of the syneresis process. PMID:25439912

Ako, Komla

2015-01-22

275

Antioxidant effect of green tea on polymer gel dosimeter  

Science.gov (United States)

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

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

2015-01-01

276

Substrate effects of gel surfaces on cell adhesion and disruption.  

Science.gov (United States)

Substrate effects of hydrogel surfaces prepared on hydrophilic and hydrophobic substrates on the cell adhesion and disruption were studied. The adhesion of tobacco protoplasts onto anionic hydrogels was strongly influenced by the substrates on which the gels were synthesized. In the case of anionic poly(2-acrylamido-2-methylpropanesulfonic acid) gel, more cells adhered on the gel surface prepared on hydrophobic substrates than that prepared on hydrophilic substrates. On the other hand, in the case of cationic quaternized poly-(dimethylaminopropylacrylamide) gel, cell disruption occurred in a few seconds accompanied with an intensive release of cellular contents on the gel surface prepared on the hydrophilic substrates, while the cationic gel synthesized on hydrophobic substrates induced no cell disruption. These different behaviors of the cell have been made in terms of different structures of gel surfaces associated with the presence of flexible dangling chains. PMID:11710095

Narita, T; Hirai, A; Xu, J; Gong, J P; Osada, Y

2000-01-01

277

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

278

Bucky gel actuators optimization towards haptic applications  

Science.gov (United States)

An ideal plastic actuator for haptic applications should generate a relatively large displacement (minimum 0.2-0.6 mm, force (~50 mN/cm2) and a fast actuation response to the applied voltage. Although many different types of flexible, plastic actuators based on electroactive polymers (EAP) are currently under investigation, the ionic EAPs are the only ones that can be operated at low voltage. This property makes them suitable for applications that require inherently safe actuators. Among the ionic EAPs, bucky gel based actuators are very promising. Bucky gel is a physical gel made by grounding imidazolium ionic liquids with carbon nanotubes, which can then be incorporated in a polymeric composite matrix to prepare the active electrode layers of linear and bending actuators. Anyhow, many conflicting factors have to be balanced to obtain required performance. In order to produce high force a large stiffness is preferable but this limits the displacement. Moreover, the bigger the active electrode the larger the force. However the thicker an actuator is, the slower the charging process becomes (it is diffusion limited). In order to increase the charging speed a thin electrolyte would be desirable, but this increases the probability of pinholes and device failure. In this paper we will present how different approaches in electrolyte and electrode preparation influence actuator performance and properties taking particularly into account the device ionic conductivity (which influences the charging speed) and the electrode surface resistance (which influences both the recruitment of the whole actuator length and its speed).

Bubak, Grzegorz; Ansaldo, Alberto; Ceseracciu, Luca; Hata, Kenji; Ricci, Davide

2014-03-01

279

Staining proteins in gels with silver nitrate.  

Science.gov (United States)

INTRODUCTIONSilver staining is one of the commonly used procedures for visualizing proteins in acrylamide gels. All silver staining methods rely on the reduction of ionic to metallic silver to provide metallic silver images; the selective reduction at gel sites occupied by proteins compared to nonprotein sites is dependent on differences in the oxidation-reduction potentials at these sites. There are two broad methodologies for silver staining. One approach (nondiamine silver nitrate stains) uses silver nitrate as the silvering agent and formaldehyde in alkaline carbonate solution as the developing agent, whereas the other approach (diamine or ammoniacal stains) uses ammoniacal silver as the silvering agent and formaldehyde in dilute citric acid as the developing agent. Although protocols using ammoniacal silver are arguably more sensitive and give darker hues than those based on silver nitrate, they are more prone to negative staining, resulting in hollow or "doughnut" spots, give unacceptable backgrounds with tricine-based gel systems, and are not very robust because of their reliance on the ammonia-silver ratio. Additionally, ammoniacal silver staining is more sensitive for basic proteins but less so for very acidic proteins. This protocol describes a silver nitrate staining approach. Its sensitivity is in the low-nanogram range, which is 50-100 times more sensitive than classical Coomassie Blue staining, ~10 times better than colloidal Coomassie Blue staining, and at least twice as sensitive as the zinc/imidazole negative staining method. PMID:21357115

Simpson, Richard J

2007-01-01

280

Microcavities elaborated by sol-gel process  

Science.gov (United States)

The fabrication and the optical properties of sol-gel high quality DBRs and microcavities are described and the emission of the europium ions included in the cavity observed. The microcavities are constituted of an SiO2 half wave Eu3+ doped active layer inserted between two sol-gel Bragg reflectors. These reflectors are formed by a stack of alternated quarter wave films of SiO2 and TiO2. Films were deposited by a dip coating method. To fabricate high quality Bragg mirrors, a large number of layers has to be stacked, but sol gel thin layers develop internal stresses during the drying and firing processes, leading to defects and cracks into the stacked films. The study of the stresses in the layers shows that a short 900°C layer annealing solves this problem and the number of stacked layers can be greater than 60 without cracks. A microcavity with 7 doublets Bragg mirrors has been fabricated using this process. Eu3+ luminescence modification due to the cavity effect, intensity enhancement and modification of the lineshape, has been observed, showing a cavity quality factor of 1200. The reflectivity factor of the associated Bragg mirrors reaches 99.8% for seven alternated SiO2/TiO2 layers.

Bellessa, Joel; Rabaste, Sebastien; Plenet, Jean-Claude; Mugnier, Jacques

2003-04-01

281

Sol-gel method for encapsulating molecules  

Science.gov (United States)

A method for encapsulating organic molecules, and in particular, biomolecules using sol-gel chemistry. A silica sol is prepared from an aqueous alkali metal silicate solution, such as a mixture of silicon dioxide and sodium or potassium oxide in water. The pH is adjusted to a suitably low value to stabilize the sol by minimizing the rate of siloxane condensation, thereby allowing storage stability of the sol prior to gelation. The organic molecules, generally in solution, is then added with the organic molecules being encapsulated in the sol matrix. After aging, either a thin film can be prepared or a gel can be formed with the encapsulated molecules. Depending upon the acid used, pH, and other processing conditions, the gelation time can be from one minute up to several days. In the method of the present invention, no alcohols are generated as by-products during the sol-gel and encapsulation steps. The organic molecules can be added at any desired pH value, where the pH value is generally chosen to achieve the desired reactivity of the organic molecules. The method of the present invention thereby presents a sufficiently mild encapsulation method to retain a significant portion of the activity of the biomolecules, compared with the activity of the biomolecules in free solution.

Brinker, C. Jeffrey (Albuquerque, NM); Ashley, Carol S. (Albuquerque, NM); Bhatia, Rimple (Albuquerque, NM); Singh, Anup K. (San Francisco, CA)

2002-01-01

282

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

283

Highly-correlated charges in polyelectrolyte gels  

Science.gov (United States)

Polyelectrolyte gels are ubiquitous in polymer physics due to their attractive combination of structural and chemical features that permit the realization of ``environmentally responsive'' systems. The conventional conceptual picture of the volume response of these systems is based on a competition between osmotic and elastic effects. We elaborate on this fundamental understanding by including ion correlations through the use of liquid-state integral equation theory. This allows for a statistical mechanical representation of the state of the system that not only surpasses traditional Poisson-Boltzmann theories but also renders structural features in a highly accurate fashion. In particular, the local ion structure is elucidated, allowing for detailed articulation of charge inversion and condensation effects in the context of gel swelling. The inclusion of correlations has a number of ramifications that become apparent, with enhanced gel collapse and excluded volume competitions that give rise to novel and ion-dependent reentrant swelling effects. We expect this rigorous theory to prove instructive in understanding any number of gelated structures, such as chromosomes or designed synthetic materials for drug delivery.

Sing, Charles; Zwanikken, Johannes; Olvera de La Cruz, Monica

2013-03-01

284

Gel Electrophoresis of Gold-DNA Nanoconjugates  

Science.gov (United States)

Gold-DNA conjugates were investigated in detail by a comprehensive gel electrophoresis study based on 1200 gels. A controlled number of single-stranded DNA of different length was attached specifically via thiol-Au bonds to phosphine-stabilized colloidal gold nanoparticles. Alternatively, the surface of the gold particles was saturated with single stranded DNA of different length either specifically via thiol-Au bonds or by nonspecific adsorption. From the experimentally determined electrophoretic mobilities, estimates for the effective diameters of the gold-DNA conjugates were derived by applying two different data treatment approaches. The first method is based on making a calibration curve for the relation between effective diameters and mobilities with gold nanoparticles of known diameter. The second method is based on Ferguson analysis which uses gold nanoparticles of known diameter as reference database. Our study shows that effective diameters derived from gel electrophoresis measurements are affected with a high error bar as the determined values strongly depend on the method of evaluation, though relative changes in size upon binding of molecules can be detected with high precision. Furthermore, in this study, the specific attachment of DNA via gold-thiol bonds to Au nanoparticles is compared to nonspecific adsorption of DNA. Also, the maximum number of DNA molecules that can be bound per particle was determined. PMID:18401452

Pellegrino, T.; Sperling, R. A.; Alivisatos, A. P.; Parak, W. J.

2007-01-01

285

Gel Electrophoresis of Gold-DNA Nanoconjugates  

Directory of Open Access Journals (Sweden)

Full Text Available Gold-DNA conjugates were investigated in detail by a comprehensive gel electrophoresis study based on 1200 gels. A controlled number of single-stranded DNA of different length was attached specifically via thiol-Au bonds to phosphine-stabilized colloidal gold nanoparticles. Alternatively, the surface of the gold particles was saturated with single stranded DNA of different length either specifically via thiol-Au bonds or by nonspecific adsorption. From the experimentally determined electrophoretic mobilities, estimates for the effective diameters of the gold-DNA conjugates were derived by applying two different data treatment approaches. The first method is based on making a calibration curve for the relation between effective diameters and mobilities with gold nanoparticles of known diameter. The second method is based on Ferguson analysis which uses gold nanoparticles of known diameter as reference database. Our study shows that effective diameters derived from gel electrophoresis measurements are affected with a high error bar as the determined values strongly depend on the method of evaluation, though relative changes in size upon binding of molecules can be detected with high precision. Furthermore, in this study, the specific attachment of DNA via gold-thiol bonds to Au nanoparticles is compared to nonspecific adsorption of DNA. Also, the maximum number of DNA molecules that can be bound per particle was determined.

W. J. Parak

2008-03-01

286

Magnetization transfer imaging for polymer gel dosimetry  

Energy Technology Data Exchange (ETDEWEB)

Off-resonance RF pre-saturation was used to obtain contrast in MRI images of polymer gel dosimeters irradiated to doses up to 50 Gy. Two different polymer gel dosimeters composed of 2-hydroxyethyl-acrylate or methacrylic acid monomers mixed with N, N'-methylene-bisacrylamide (BIS), dispersed in an aqueous gelatin matrix were evaluated. Radiation-induced polymerization of the co-monomers generates a fast-relaxing insoluble polymer. Saturation of the polymer using off-resonance Gaussian RF pulses prior to a spin-echo read-out with a short echo time leads to contrast that is dependent on the absorbed dose. This contrast is attributed to magnetization transfer (MT) between free water and the polymer, and direct saturation of water was found to be negligible under the prevailing experimental conditions. The usefulness of MT imaging was assessed by computing the dose resolution obtained with this technique. We found a low value of dose resolution over a wide range of doses could be obtained with a single experiment. This is an advantage over multiple spin echo (MSE) experiments using a single echo spacing where an optimal dose resolution is achieved over only very limited ranges of doses. The results suggest MT imaging protocols may be developed into a useful tool for polymer gel dosimetry. (author)

Lepage, M. [Centre for Medical, Health and Environmental Physics, Queensland University of Technology, Brisbane, QLD (Australia)]. E-mail: martin.lepage@yale.edu; Deene, Y. de; Baldock, C. [Centre for Medical, Health and Environmental Physics, Queensland University of Technology, Brisbane, QLD (Australia); McMahon, K.; Galloway, G.J. [Centre for Magnetic Resonance, University of Queensland, Brisbane, QLD (Australia); Baeck, S.A.J. [Centre for Medical, Health and Environmental Physics, Queensland University of Technology, Brisbane, QLD (Australia); Department of Radiation Physics, Lund University, Malmoe University Hospital (Sweden)

2002-06-07

287

Sol-gel bonding of silicon wafers  

International Nuclear Information System (INIS)

Low temperature bonding of silicon wafers was achieved using sol-gel technology. The initial sol-gel chemistry of the coating solution was found to influence the mechanical properties of the resulting bonds. More precisely, the influence of parameters such as the alkoxide concentration, water-to-alkoxide molar ratio, pH, and solution aging on the final bond morphologies and interfacial fracture energy was studied. The thickness and density of the sol-gel coating were characterised using ellipsometry. The corresponding bonded specimens were investigated using attenuated total reflectance Fourier transformed infrared spectroscopy to monitor their chemical composition, infrared imaging to control bond integrity, and cross-sectional transmission electron microscopy to study their microstructure. Their interfacial fracture energy was measured using microindentation. An optimum water-to-alkoxide molar ratio of 10 and hydrolysis water at pH = 2 were found. Such conditions led to relatively dense films (> 90%), resulting in bonds with a fracture energy of 3.5 J/m2, significantly higher than those obtained using classical hydrophilic bonding (typically 1.5-2.5 J/m2). Ageing of the coating solution was found to decrease the bond strength

288

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 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 subfamília 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 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

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

2014-03-01

289

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

290

Bi-Sr-Co-O thermoelectrics prepared by sol-gel methods with modified gel decomposition  

International Nuclear Information System (INIS)

We prepared misfit Bi2Sr2Co1.8Ox (Bi-222) phase as a member of a Bi-Sr-Co-O family. Two water based sol-gel methods were chosen with regard to the presence of a strongly hydrolysing Bi3+ ion - chelating route combining EDTA (ethylenediaminetetraacetic acid) and TEA (triethanolamine) and, secondly, water soluble polymer method using PEI (polyethylenimine). We focused on the influence of gel decomposition process on the grain size of precursor and, consequently, on the bulk density of the final samples. We tested decomposition in N2 atmosphere followed by a treatment in pure oxygen. The precursors decomposed in 'N2/O2' regime were mainly composed of Bi2O3, SrCO3 and cobalt oxides with the grain size of approximately 50-100 nm. The powders arising from gel decomposition in air contained the desired Bi-Sr-Co-O oxide as the major phase independently of the chosen sol-gel method. The final sintered samples were almost single-phase with traces of the other pseudoternary phase Bi2Sr2CoOx independently of the decomposition atmosphere. For comparison, samples were also prepared by solid state reaction. The sol-gel prepared samples were always of higher bulk density with larger grains, moreover partly microstructurally ordered. These facts were also reflected in transport thermoelectric measurements. measurements.

291

Dynamics around the sol-gel transition in thermoreversible polymer gels  

Science.gov (United States)

Recently, a number of intriguing similarities have been found between the dynamical behaviour of gel- and glass-forming materials [1-3]. For instance, both the glass and gel transitions are reversible, they show typical kinetic features and occur as a result of the physical arrest of either molecules or molecular structures. An obvious difference between glasses and gels is one of length and correspondingly time scales, with those of gels being much longer than those of glasses. In order to investigate what similarities and indeed differences that exist between thermoreversible gelation and glass formation we have investigated the dynamics around the sol-gel transition in two different thermoreversibly gelling systems: poly(N-acetamido acrylamide) in water and atactic polystyrene in toluene. The studies include a wide range of experimental techniques including dynamic light scattering, diffusing wave spectroscopy, rheology, calorimetry,quasi-elastic neutron scattering and dielectric spectrocopy. The results will be discussed in the light of models and theories suggested to describe gelation in these types of systems. [1] Ren, S.Z. And Sorensen, C.M., Phys. Rev. Lett., 70, 1727 (1993) [2] Ikkai, F. and Shibayama, M., Phys. Rev. Lett. 82, 4946 (1999) [3] Kumar, S. and Douglas, J.F., Phys. Rev. Lett., 87, 188301 (2001)

Mattsson, Johan; Dasgupta, Bivash; Matic, Aleksandar; Bergman, Rikard; Nystrom, Bo; Weitz, David A.

2004-03-01

292

Gniuždom?j? gelžbetonini? konstrukcij? stiprinimo gelžbetoniniais apvalkalais analiz?  

Directory of Open Access Journals (Sweden)

Full Text Available Šiame straipsnyje analizuojamos dvi pasirinktos gniuždom?j? gelžbetonini? element?, sustiprint? gelžbetoniniais apvalkalais, laikomosios galios skai?iavimo metodikos. Trumpai aprašomi laikomosios galios skai?iavimo metodik? algoritmai. Pateikiamos element? laikomosios galios pagrindin?s lygtys ir priklausomyb?s. Siekiant palyginti ir patikslinti laikomosios galios skai?iavimo metodikas, atlikti gniuždom?j? dispersiškai armuot? element?, sustiprint? gelžbetoniniais apvalkalais, laikomosios galios eksperimentiniai tyrimai. Atliktas teorini? skai?iavimo rezultat? palyginimas su eksperimentini? tyrim? rezultatais. Trumpai aprašomi analizuot? skai?iavimo metodik? bei eksperimentini? tyrim? privalumai ir tr?kumai. Remiantis gautomis skai?iavimo metodik? palyginimo ir eksperimentini? tyrim? išvadomis, pateikiama patobulinta laikomosios galios skai?iavimo metodika.Straipsnis lietuvi? kalba

Saulius Pilkavi?ius

2011-06-01

293

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

294

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

295

The biophysical properties of Basal lamina gels depend on the biochemical composition of the gel.  

Science.gov (United States)

The migration of cells within a three-dimensional extracellular matrix (ECM) depends sensitively on the biochemical and biophysical properties of the matrix. An example for a biological ECM is given by reconstituted basal lamina gels purified from the Engelbreth-Holm-Swarm sarcoma of mice. Here, we compare four different commercial variants of this ECM, which have all been purified according to the same protocol. Nevertheless, in those gels, we detect strong differences in the migration behavior of leukocyte cells as well as in the Brownian motion of nanoparticles. We show that these differences correlate with the mechanical properties and the microarchitecture of the gels which in turn arise from small variations in their biochemical composition. PMID:25689062

Arends, Fabienna; Nowald, Constantin; Pflieger, Kerstin; Boettcher, Kathrin; Zahler, Stefan; Lieleg, Oliver

2015-01-01

296

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.

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

2010-07-01

297

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  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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 d [...] e 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. Abstract in english 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. ab [...] ortus 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; Maria Luana Cristiny Rodrigues, Silva; Carolina de Sousa Américo, Batista; Albério Antônio de Barros, Gomes; Sílvio Arruda, Vasconcellos; Clebert José, Alves.

2010-02-01

298

Self-oscillating surface of gel for autonomous mass transport.  

Science.gov (United States)

As a novel biomimetic gels deffering from conventonal stimuli-responsive polymer gels, we have developed a "self-oscillating" gel that swells and deswells periodically under constant condition without on-off switching of external stimuli. The gel is composed of poly(N-isopropylacrylamide) to which the catalyst of the oscillating chemical reaction, called Belousov-Zhabotinsky reaction, is covalently immobilized. The chemical oscillation is converted to the mechanical oscillation of the gel through the change in hydrophilicity of polymer chains with the redox changes of the immobilized catalyst. By utilizing the self-oscillating gel, several kinds of functional material systems such as biomimetic actuators, etc. are expected. Here we review a potential application to functional surface to realize autonomous mass-transport by utilizing the peristaltic motion of the gel. With the propagation of the chemical wave, the loaded cargo is autonomously transported on the surface. In order to fabricate the self-driven gel conveyer for a wider use including biomedical applications, the interactions between the self-oscillating gel and the loaded gel cargo were investigated and their influence on the transport phenomena were evaluated. PMID:22019050

Yoshida, Ryo; Murase, Yoko

2012-11-01

299

Deuterium isotope effect on swelling process in aqueous polymer gels  

International Nuclear Information System (INIS)

The deuterium isotope effects on the swelling process of typical aqueous polymer gels (poly(N-isopropylacrylamide) gel and polyacrylamide gel) have been investigated in this study. The swelling times of both the poly(N-isopropylacrylamide) gel and the polyacrylamide gel in heavy water are longer than those in water. The deuterium isotope effect in the swelling process of gels is mainly arising from the higher viscosity in heavy water than in water. The additional deuterium isotope effect on the diffusion coefficient related to the swelling process should be due to the larger microscopic friction arising from the stronger polymer-solvent interaction in heavier water than in water. We also discuss in this paper the deuterium isotope effects on the size of the aqueous gels in the equilibrium state. Interestingly, the size in the equilibrium state of poly(N-isopropylacrylamide) gel in heavy water is larger than that in water. In contrast to poly(N-isopropylacrylamide) gel, the size in the equilibrium state of polyacrylamide gel in heavy water is smaller than that in water. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

300

Photo-induced locomotion of chemo-responsive polymer gels  

Science.gov (United States)

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

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

2009-03-01

301

Evaluation of effective parameters on cold duration in cryo accumulator gels  

International Nuclear Information System (INIS)

Cryo accumulator gels can retain cold temperature for long periods of time. These gels are used in medicine and transporting of medico-biological objects in cold condition. In this paper, two types of gels, the so-called soft gel and hard gel, have been formulated. Polyacrylamide, which was synthesized by precipitation polymerization in acetone, has been used as a gel in formulation of these cold packs. To evaluate the cold duration in the formulated gels, temperature changes of these gels have been measured versus time. Performed tests showed that cold duration in hard gels is longer than in soft gels, on precise term, average life of a soft gel is about 3 h and for a hard gel is about 10 h. Also, the polyacrylamide crosslinking density affects the cold duration in soft gels. It has been evaluated and observed that with changing this parameter we can substantially extend the cold life of these gels

302

Calibration of an alanine/agarose gel  

OpenAIRE

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...

Olsson, Sara

1998-01-01

303

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

304

Hybrid slab-microchannel gel electrophoresis system  

Science.gov (United States)

A hybrid slab-microchannel gel electrophoresis system. The hybrid system permits the fabrication of isolated microchannels for biomolecule separations without imposing the constraint of a totally sealed system. The hybrid system is reusable and ultimately much simpler and less costly to manufacture than a closed channel plate system. The hybrid system incorporates a microslab portion of the separation medium above the microchannels, thus at least substantially reducing the possibility of non-uniform field distribution and breakdown due to uncontrollable leakage. A microslab of the sieving matrix is built into the system by using plastic spacer materials and is used to uniformly couple the top plate with the bottom microchannel plate.

Balch, Joseph W. (Livermore, CA); Carrano, Anthony V. (Livermore, CA); Davidson, James C. (Livermore, CA); Koo, Jackson C. (San Ramon, CA)

1998-01-01

305

Connectivity in sol-gel silica glasses  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english In this work it is carried out a review on structural parameters related to the evaluation of pore connectivity of nanostructures. The work describes parameters and methods of evaluation of geometric parameters. The concepts of connectivity are applied to silica gels and glasses obtained from sol-ge [...] l process. The study of pores connectivity was carried out using a combination of geometric modeling and experimental evaluation of specific surface area and pore volume. The permeability of the pore structure is evaluated and a permeability geometric factor, Pg, is proposed.

Wander L., Vasconcelos.

1998-07-01

306

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

307

Biotechnology Laboratory: Gel Electrophoresis of Dyes  

Science.gov (United States)

A portion of the Partnership for Plant Genomics Education, hosted by the University of California-Davis, this PDF presents a student activity where students will use agarose gel electrophoresis to separate several different dyes. The lab is described as a â??precursor to DNA separationsâ? and thus provides an important step in the subject matter. The lab provides for students: detailed instructions, background information, and a quiz and group questions. Answers to the questions, and also the general objective of the lab, are provided for the instructor. Overall, the lab is introductory in nature and perfect for any science classroom.

308

Screening of mucoadhesive vaginal gel formulations  

Scientific Electronic Library Online (English)

Full Text Available O planejamento racional de formulações para a liberação vaginal de fármacos requer atenção especial às propriedades do veículo, que otimizem o revestimento e a retenção vaginal. O objetivo do presente trabalho foi realizar uma triagem de géis vaginais mucoadesivos formulados com carbomero ou carrage [...] nina em combinação binária com um segundo polímero (carbomero, goma guár ou xantana). Os géis foram caracterizados usando estudos in vitro de aderência, espalhabilidade e potencial de vazamento, bem como medições reológicas (testes de varredura de tensão e frequência) e o efeito de diluição com fluido vaginal simulado (SVF) na espalhabilidade. Os resultados foram analisados utilizando a análise de variância e de fator múltiplo. A combinação de polímeros reforçou a adesão de ambos os agentes gelificantes primários, carbomero e carragenina. Do ponto de vista reológico todas as formulações apresentaram comportamento semelhante, predominantemente elástico e caracterizado por valores de tangente de perda bem abaixo de 1. Não se encontrou correlação entre as medições reológicas e o comportamento de adesão. Os géis de carbomero e carragenina contendo o maior porcentual de goma xantana apresentaram melhor mucoadesão e espalhabilidade, menor potencial de vazamento e maior resistência à diluição in vitro. Os resultados positivos obtidos com géis de carragenina-goma xantana podem incentivar o uso de adjuvantes biocompatíveis naturais na composição dos produtos vaginais, um campo de formulação atualmente sob o domínio de produtos sintéticos. Abstract in english Rational design of vaginal drug delivery formulations requires special attention to vehicle properties that optimize vaginal coating and retention. The aim of the present work was to perform a screening of mucoadhesive vaginal gels formulated with carbomer or carrageenan in binary combination with a [...] second polymer (carbomer, guar or xanthan gum). The gels were characterised using in vitro adhesion, spreadability and leakage potential studies, as well as rheological measurements (stress and frequency sweep tests) and the effect of dilution with simulated vaginal fluid (SVF) on spreadability. Results were analysed using analysis of variance and multiple factor analysis. The combination of polymers enhanced adhesion of both primary gelling agents, carbomer and carrageenan. From the rheological point of view all formulations presented a similar behaviour, prevalently elastic and characterised by loss tangent values well below 1. No correlation between rheological and adhesion behaviour was found. Carbomer and carrageenan gels containing the highest percentage of xanthan gum displayed good in vitro mucoadhesion and spreadability, minimal leakage potential and high resistance to dilution. The positive results obtained with carrageenan-xanthan gum-based gels can encourage the use of natural biocompatible adjuvants in the composition of vaginal products, a formulation field that is currently under the synthetic domain.

Ana Ochoa, Andrade; María Emma, Parente; Gastón, Ares.

2014-12-01

309

SANS studies of liquid crystalline microemulsion gels  

Science.gov (United States)

We have investigated by small-angle neutron scattering (SANS) the ternary system containing water, alkane and the surfactant mixture benzyltetradecyldimethylammonium chloride and tetradecyltrimethylammonium bromide, which we have found to form a cubic liquid crystalline phase. A contrast variation experiment with equal volume fractions of water and oil showed three Bragg reflections varying in agreement with theoretically calculated scattering amplitudes for an infinite periodic minimal surface (IPMS) with cubic symmetry. We have, in addition, studied the “ringing” gel phases of the system water/octane/didodecyldimethylammonium bromide by SANS and electron microscopy.

Rädler, J. O.; Radiman, S.; De Vallera, A.; Toprakcioglu, C.

1989-01-01

310

Investigating potential physicochemical errors in polymer gel dosimeters  

Energy Technology Data Exchange (ETDEWEB)

Measurement errors in polymer gel dosimetry can originate either during irradiation or scanning. One concern related to the exothermic nature of polymerization reaction was that the heat released in polymer gel dosimeters during irradiation modifies their dose response. In this paper, the effect of heat released from the exothermal polymerization reaction on the dose response of a number of dosimeters was studied. In addition, we investigated whether heat-generated geometric distortion existed in newly proposed gel dosimeters that contain highly thermoresponsive polymers. Our results suggest that despite a significant internal temperature increase in some gel compositions, their dose responses are not affected when oxygen is well expelled mechanically from the gel mixture. We also report on significant pre-irradiation instability in some recently developed polymer gel dosimeters but that geometric distortions were not observed. Data obtained by a set of small calibration vials are compared to those obtained from larger phantoms, and potential physicochemical causes of deviations between them are identified.

Sedaghat, Mahbod; Lepage, Martin [Centre d' imagerie moleculaire de Sherbrooke, Departement de medecine nucleaire et radiobiologie, Universite de Sherbrooke, Sherbrooke, QC (Canada); Bujold, Rachel, E-mail: martin.lepage@usherbrooke.ca [Service de radio-oncologie, Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC (Canada)

2011-09-21

311

Investigating potential physicochemical errors in polymer gel dosimeters  

International Nuclear Information System (INIS)

Measurement errors in polymer gel dosimetry can originate either during irradiation or scanning. One concern related to the exothermic nature of polymerization reaction was that the heat released in polymer gel dosimeters during irradiation modifies their dose response. In this paper, the effect of heat released from the exothermal polymerization reaction on the dose response of a number of dosimeters was studied. In addition, we investigated whether heat-generated geometric distortion existed in newly proposed gel dosimeters that contain highly thermoresponsive polymers. Our results suggest that despite a significant internal temperature increase in some gel compositions, their dose responses are not affected when oxygen is well expelled mechanically from the gel mixture. We also report on significant pre-irradiation instability in some recently developed polymer gel dosimeters but that geometric distortions were not observed. Data obtained by a set of small calibration vials are compared to those obtained from larger phantoms, and potential physicochemical causes of deviations between them are identified.

312

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

313

Encapsulation of biological species in sol-gel matrices  

International Nuclear Information System (INIS)

Two examples are given of the gelation of silica sols containing bio catalysts, resulting in their encapsulation in porous matrices. Urease was encapsulated in gels made from a mixture of TMOS and alkyltrimethoxysilane. Enzyme activities, monitored by measuring the rate of production of ammoniacal nitrogen as urea was decomposed, ranged up to 60% of that of the unencapsulated species. Anaerobic sulphate-reducing bacteria were encapsulated in a gel produced from colloidal silica, thus avoiding contact with alcohol. The detection of H2S produced in the doped gel indicated that the bacteria were able to continue normal metabolic function within the gel matrix. A gel initially doped with ? 5 x 105 cells cm-3, exhibited an optimum sulphate reduction rate of 11 ug h-1 cm-3; this reduction rate was quickly re-established after storage of the gel for 14 weeks. Copyright (2000) The Australian Ceramic Society

314

Buccoadhesive gels of glibenclamide: a means for achieving enhanced bioavailability.  

Science.gov (United States)

The aim of the present study was to formulate and evaluate buccoadhesive gels of model drug, glibenclamide indented as an alternate route of drug delivery to have enhanced bioavailability. The buccoadhesive gels were prepared by solution polymerization technique containing Hydroxy Propyl Methyl Cellulose (HPMC, E15 LV) and Carbopol (CP, 934P). An apparatus, simulating the in-vivo conditions of the mouth was designed in order to assess in-vitro release kinetics of the prepared gels. The gels were also evaluated for buccoadhesive strength, hydration, and swelling index, and viscosity. In-vivo evaluation for pharmacodynamic and pharmacokinetic properties of the optimized gel was done in rabbits. The drug release of buccoadhesive gels through rabbit buccal mucosa increased significantly (p glibenclamide. PMID:19624249

Philip, A K; Srivastava, M; Pathak, K

2009-10-01

315

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)

316

Spherulitic Growth of Neodymium Tartrate Crystals in Silica Gel  

OpenAIRE

Neodymium tartrate crystals in the form of spherulites were synthesized by using a controlled diffusion system in silica gel at ambient temperature. The influence of growth parameters e.g. reactant concentration, gel pH, gel ageing, on the size and nucleation density of the crystals has been studied. The mechanisms of crystallization for spherulites are described. Three distinct mechanisms are found to be operative. The information presented contributes to the understanding of spherulitic gro...

Jayashree Hiralal Patil; Dilip Kashinath Sawant; Hiralal Motilal Patil; Bhavsar, Deelip S.

2010-01-01

317

Efficacy of a New Autologus Platelet Gel: in Vitro Study  

OpenAIRE

BackgroundAutologus platelet gel is easy to prepare and is relatively low cost. The aim of this study was to prepare and evaluate in vitro efficacy of autologus platelet gel.Materials and MethodsIn this experimental study, platelet concentrate and platelet poor plasma were prepared with aphaeresis method. Thrombin was prepared by mixing the plasma with calcium. Thrombin activity level was determined by spectrophotometric method. The platelet gel was obtained by adding thrombin and calcium to ...

Heidari Bateni M; Alizadeh Sh; Hashemi Tayer A

2012-01-01

318

Stimuli responsive smart-gels realized via modular protein design  

OpenAIRE

Smart-gels have a variety of applications including tissue engineering and controlled drug delivery. Here we present a modular, bottom-up approach that permits the creation of protein-based smart-gels with encoded morphology, functionality, and responsiveness to external stimuli. The properties of these gels are encoded by the proteins from which they are synthesized. In particular, the strength and density of the network of intermolecular cross-links are specified by the interactions of the ...

Grove, Tijana Z.; Osuji, Chinedum O.; Forster, Jason D.; Dufresne, Eric R.; Regan, Lynne

2010-01-01

319

Pacman percolation: a model for enzyme gel degradation  

OpenAIRE

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.; Candia, A.; Lairez, D.; Coniglio, A.

2004-01-01

320

Prenatal Virilization Associated with Paternal Testosterone Gel Therapy  

OpenAIRE

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 testosterone ge...

Anisha Patel; Rivkees, Scott A.

2010-01-01

321

Image Mining from Gel Diagrams in Biomedical Publications  

OpenAIRE

Authors of biomedical publications often use gel images to report experimental results such as protein-protein interactions or protein expressions under different conditions. Gel images offer a way to concisely communicate such findings, not all of which need to be explicitly discussed in the article text. This fact together with the abundance of gel images and their shared common patterns makes them prime candidates for image mining endeavors. We introduce an approach for t...

Kuhn, Tobias; Krauthammer, Michael

2012-01-01

322

FORMULATION AND EVALUATION OF POLYHERBAL GEL FOR ANTI - INFLAMMATORY ACTIVITY  

OpenAIRE

ABSTRACT: In the present study, three medicinal plants Cynodon dactylon (L.) Pers, Cassia tora Linn. and Cassia alata Linn having significant anti-inflammatory potential were selected to be formulated as polyherbal gels. The gels were prepared using the dried methanolic extract of Cassia tora Linn, Cassia alata Linn and Cynodon dactylon (L.) Pers. Polyherbal gel formulations were evaluated for its pH, appearance and homogeneity, viscosity, spreadability and skin irritation studies. Assessmen...

Gouri Dixit, Ganesh Misal

2013-01-01

323

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)

324

Strain identification in Rhizobium by starch gel electrophoresis of isoenzymes  

OpenAIRE

Sonieated extracts of rhizobia, especiaUy Rhizobium leguminosarum from pea and vetch, were run in horizontal starch gel electrophoresis in the cold. The rhizobia were grown on agar on a slime suppressing substrate of tryptone-yeast extract-CaCl2 with small amounts of mannitol, sorbitol and arabinose and other sugars as enzyme inducers. After electrophoresis the gels were separated into several slabs by a gel cutter. Each slab was stained for a particular enzyme. Among numerous ...

Engvild, Kjeld Christensen; Nielsen, G.

2011-01-01

325

Antimicrobial activity and the mechanism of silver nanoparticle thermosensitive gel  

Directory of Open Access Journals (Sweden)

Full Text Available Meiwan Chen1,2,‡, Zhiwen Yang1,‡, Hongmei Wu1, Xin Pan1, Xiaobao Xie3, Chuanbin Wu11Research and Development Center of Pharmaceutical Engineering, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China; 2State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau, China; 3Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangzhou, China ‡These authors contributed equally to this workPurpose: The purpose of the present study was to elucidate the antimicrobial activity and mechanism of silver nanoparticles incorporated into thermosensitive gel (S-T-Gel on Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa.Patients and methods: This study investigated the growth, permeability, and morphology of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa cells in order to observe the action of S-T-Gel on the membrane structure of these three bacteria. The cell morphology of normal and treated bacteria cells was assessed by transmission electron microscopy (TEM, and the effects of S-T-Gel on genome DNA of bacterial cells were evaluated by agarose gel electrophoresis.Results: S-T-Gel showed promising activity against Staphylococcus aureus and moderate activity against Escherichia coli and Pseudomonas aeruginosa. The observation with TEM suggested that S-T-Gel may destroy the structure of bacterial cell membranes in order to enter the bacterial cell. S-T-Gel then condensed DNA and combined and coagulated with the cytoplasm of the damaged bacteria, resulting in the leakage of the cytoplasmic component and the eventual death of these three bacteria. In addition, the analysis of agarose gel electrophoresis demonstrated that S-T-Gel could increase the decomposability of genome DNA.Conclusion: These results about promising antimicrobial activity and mechanism of S-T-Gel may be useful for further research and development in in-vivo studies.Keywords: molecule mechanism, bacterial cells, S-T-Gel

Chen M

2011-11-01

326

Diffusion and partitioning of proteins in charged agarose gels.  

OpenAIRE

The effects of electrostatic interactions on the diffusion and equilibrium partitioning of fluorescein-labeled proteins in charged gels were examined using fluorescence recovery after photobleaching and gel chromatography, respectively. Measurements were made with BSA, ovalbumin, and lactalbumin in SP-Sepharose (6% sulfated agarose), in phosphate buffers at pH 7 and ionic strengths ranging from 0.01 to 1.0 M. Diffusivities in individual gel beads (D) and in the adjacent bulk solution (D infin...

Johnson, E. M.; Berk, D. A.; Jain, R. K.; Deen, W. M.

1995-01-01

327

Formation and Rupture of Ca$^{2+}$ Induced Pectin Biopolymer Gels  

OpenAIRE

When calcium salts are added to an aqueous solution of polysaccharide pectin, ionic cross-links form between pectin chains, giving rise to a gel network in dilute solution. In this work, dynamic light scattering (DLS) is employed to study the microscopic dynamics of the fractal aggregates (flocs) that constitute the gels, while rheological measurements are performed to study the process of gel rupture. As calcium salt concentration is increased, DLS experiments reveal that t...

Basak, Rajib; Bandyopadhyay, Ranjini

2014-01-01

328

Production of silica gel from residual rice husk ash  

OpenAIRE

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

329

Accumulation of humic acid in DET/DGT gels  

OpenAIRE

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

330

A systematic study of field inversion gel electrophoresis.  

OpenAIRE

The mobilities of oligomers of phage lambda DNA and of yeast chromosomes in agarose gels during field inversion gel electrophoresis (FIGE) were measured at different pulse times and electric fields. Also the ratios between forward and backward pulse times and/or field gradients were varied. The problem of 'band inversion' during FIGE, leading to an ambiguity in the mobility of large DNA fragments, was solved by using two dimensional gel electrophoresis with different parameters in the first a...

Heller, C.; Pohl, F. M.

1989-01-01

331

Electrophoretic properties of the scrapie agent in agarose gels.  

OpenAIRE

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

332

The Substitute Brain and the Potential of the Gel Model  

OpenAIRE

This purpose of this paper is to review the recent history of the use of agarose gels. Although originally confined to electrophoresis work, agarose gels have proven themselves useful to a number of disciplines in the modern world, which includes brain infusion studies for research involving the treatment of various neurological conditions, such as Parkinson’s Disease. In reviewing the relevant research leading up to the modern day, this paper attempts to track agarose gels through their st...

Pomfret, Roland; Miranpuri, Gurwattan; Sillay, Karl

2013-01-01

333

Size Effects on Diffusion Processes within Agarose Gels  

OpenAIRE

To investigate diffusion processes in agarose gel, nanoparticles with sizes in the range between 1 and 140 nm have been tested by means of fluorescence correlation spectroscopy. Understanding the diffusion properties in agarose gels is interesting, because such gels are good models for microbial biofilms and cells cytoplasm. The fluorescence correlation spectroscopy technique is very useful for such investigations due to its high sensitivity and selectivity, its excellent spatial resolution c...

Fatin-rouge, Nicolas; Starchev, Konstantin; Buffle, Jacques

2004-01-01

334

Characterization of a novel influenza virus in cattle and Swine: proposal for a new genus in the Orthomyxoviridae family.  

Science.gov (United States)

We have recently reported the isolation of a novel virus, provisionally designated C/swine/Oklahoma/1334/2011 (C/OK), with 50% overall homology to human influenza C viruses (ICV), from a pig in Oklahoma. Deep RNA sequencing of C/OK virus found a matrix 1 (M1) protein expression strategy that differed from that of ICV. The novelty of C/OK virus prompted us to investigate whether C/OK virus could exist in a nonswine species. Significantly, we found that C/OK virus was widespread in U.S. bovine herds, as demonstrated by reverse transcription (RT)-PCR and serological assays. Genome sequencing of three bovine viruses isolated from two herds in different states further confirmed these findings. To determine whether swine/bovine C/OK viruses can undergo reassortment with human ICV, and to clarify the taxonomic status of C/OK, in vitro reassortment and serological typing by agar gel immunodiffusion (AGID) were conducted. In vitro reassortment using two human ICV and two swine and bovine C/OK viruses demonstrated that human ICV and C/OK viruses were unable to reassort and produce viable progeny. Antigenically, no cross-recognition of detergent split virions was observed in AGID between human and nonhuman viruses by using polyclonal antibodies that were reactive to cognate antigens. Taken together, these results demonstrate that C/OK virus is genetically and antigenically distinct from ICV. The classification of the new virus in a separate genus of the Orthomyxoviridae family is proposed. The finding of C/OK virus in swine and bovine indicates that this new virus may spread and establish infection in other mammals, including humans. IMPORTANCE Influenza C viruses (ICV) are common human pathogens, infecting most people during childhood and adolescence, and typically cause mild respiratory symptoms. While ICV have been isolated from both pigs and dogs, humans are thought to be the natural viral reservoir. Previously, we characterized an ICV-like virus isolated from pigs exhibiting symptoms of influenza virus-like illness. Here, we show molecular and serological data demonstrating widespread circulation of similar viruses in bovines. Deep RNA sequencing, phylogenetic analysis, and in vitro reassortment experiments demonstrate that animal ICV-like viruses are genetically distinct from human ICV. Antigenically, we show that ICV-like viruses are not recognized by ICV antibodies. En masse, these results suggest that bovine influenza virus warrants classification as a new genus of influenza virus. The finding of this novel virus that can infect multiple mammalian species warrants further research into its role in human health. PMID:24595369

Hause, Ben M; Collin, Emily A; Liu, Runxia; Huang, Bing; Sheng, Zizhang; Lu, Wuxun; Wang, Dan; Nelson, Eric A; Li, Feng

2014-01-01

335

An improvement for polymer gel dosimeter of type PAGAT  

International Nuclear Information System (INIS)

Four types of polymer gel dosimeter, containing acrylamide, gelatin, BIS, THPC, formaldehyde and agarose, were prepared under normal atmospheric conditions. According to the principle of U-type test tube, we screened out the gel with high melting point at 32 degree C and 60 degree C. It turned out that the PAGAT gel mixed with formaldehyde had a melting point over 60 degree C. which made the gel resist the varied environment temperature to a great extent. And it also had a good liner response with its absorbed dose. (authors)

336

Polyacrylamide gel miniaturization improves protein visualization and autoradiographic detection  

International Nuclear Information System (INIS)

Polyacrylamide gels shrink to one-quarter of their original area when soaked in a 50% (w/v) solution of polyethylene glycol. Gel miniaturization improves the contrast of protein bands, with four valuable consequences. (i) A 5- to 10-fold increase in sensitivity for Coomassie blue is observed. (ii) Gels are more durable; i.e., they resist tearing when wet and they do not crack during drying under vacuum. (iii) Shrunken gels give sharper photographic images and provide better interlane protein band comparisons. (iv) Condensed protein bands lead to an increased sensitivity for detecting low-abundance, radioactively-labeled proteins by fluorography

337

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

338

Electrophoretic separation of DNA in gels and nanostructures.  

Science.gov (United States)

The development of nanostructure devices has opened the door to new DNA separation techniques and fundamental investigations. With advanced nanotechnologies, artificial gels (e.g. nanopillar arrays, nanofilters) can be manufactured with controlled and ordered geometries. This contrast with gels, where the pores are disordered and the range of available pore sizes is limited by the level of cross-linking and the mechanical properties of the gel. In this review, we recall the theories developed for free-solution and gel electrophoresis (extended Ogston model, biased reptation and entropic trapping) and from this perspective, suggestions for future concepts for fast DNA separation using nanostructures will be given. PMID:19680576

Salieb-Beugelaar, G B; Dorfman, K D; van den Berg, A; Eijkel, J C T

2009-09-01

339

Developmental Studies on Metallised UDMH and Kerosene Gels  

Directory of Open Access Journals (Sweden)

Full Text Available The influence of particulate and hydrocolloid gellants and different surfactants on gellation of metallised stable gels of unsymmetrical dimethyl hydrazine (UDMH and kerosene containing 30 per cent 15 micron Aluminium was studied. Metallised UDMH and kerosene gels were characterised with respect to pseudoplasticity, thixotropy, consistency and yield stress using Contrave's rheometer. The effect of shear rate and temperature on the viscosity of these gels was determined. Thermal stability, hypergolicity tests and flow rate studies were also conducted. Metallised UDMH and kerosene gels are found to be stable, thixotropic and pseudoplastic and easily flowing like a liquid under shear force.

T. L. Varghese

2013-04-01

340

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 drug from the gels. However, release decreased with increase in the concentration of PG up to 10 %. In case of HPMC gels, addition of ethanol decreased the release of Valdecoxib from the gels. It is concluded that PG is a good penetration enhancer and carbopol good gelling agent for Valdecoxib gels.

Jani Rupal

2010-01-01

341

Inclusion type radiochromic gel dosimeter for threedimensional dose verification  

Science.gov (United States)

For the verification of 3D dose distributions in modern radiation therapy, a new inclusion type radiochromic gel detector has been developed. In this gel, a hydrophobic leuco dye (leucomalachite green: LMG) was dissolved in water as an inclusion complex with highly branched cyclic dextrin. The radiation induced radical oxidation property of the LMG gel with various sensitizers was investigated. As a result, the optical dose responses were enhanced by the addition of bromoacetic acid and manganese (II) chloride. Unfavorable auto-oxidation of the gel was reduced when it was stored at 4°C.

Usui, Shuji; Yoshioka, Munenori; Hayashi, Shin-ichiro; Tominaga, Takahiro

2015-01-01

342

Studies on PVdF-based gel polymer electrolytes  

Science.gov (United States)

A complex of polymer, plasticizer and lithium salts can be used as a solid gel polymer electrolyte in lightweight and rechargeable lithium batteries. Considerable research has been directed towards the development of a gel polymer with high conductivity at room temperature. In this work, a gel polymer electrolyte using polyvinylidene fluoride (PVdF)-1000 (KF), a plasticizer of 1:1 ethylene carbonate (EC) and propylene carbonate (PC), and LiBF 4 salt is optimized. Gel electrolytes have high ionic conductivity, good mechanical stability, a wide electrochemical stable window, and a stable lithium interface. The results of preliminary charge-discharge of cells are discussed in detail.

Periasamy, P.; Tatsumi, K.; Shikano, M.; Fujieda, T.; Saito, Y.; Sakai, T.; Mizuhata, M.; Kajinami, A.; Deki, S.

343

Carbopol-incorporated thermoreversible gel for intranasal drug delivery.  

Science.gov (United States)

The present study describes the preparation and evaluation of a poloxamer 407 (P407)-based thermoreversible gel using Carbopol 934P (C934P) as a mucoadhesive polymer and hydroxypropyl-?-cyclodextrin (HP-?-CD) for enhancing the aqueous solubility and intranasal absorption of fexofenadine hydrochloride (FXD HCl). The prepared gels were characterized by gelation temperature, viscoelasticity, and drug release profile. Thermoreversibility of P407/C934P gel was demonstrated by rheological studies. The incorporation of carbopol into P407 gel also reduced the amounts of drug released from the gel formulations (p < 0.05). In vivo pharmacokinetic results of the prepared gel formulations in rabbits (at 0.5 mg/kg dose) showed that the relative bioavailability of drug from P407/C934P gel was 11.3 and 2.7-fold higher than those of drug solution and P407 gel group, respectively. These findings suggested that developed thermoreversible gels could be used as promising dosage forms to improve intranasal drug absorption. PMID:25749681

Balakrishnan, Prabagar; Park, Eun-Kyoung; Song, Chung-Kil; Ko, Hyun-Jeong; Hahn, Tae-Wook; Song, Ki-Won; Cho, Hyun-Jong

2015-01-01

344

Effect of bloom strength on radiochromic gel dosimeters  

Science.gov (United States)

The Fricke gel dosimeter has been the widely used dosimeter among the gel dosimeters because of its dose response characteristics and easy preparation. The ferrous to ferric conversion that happens in this gel dosimeter on irradiation, corresponds to the absorbed dose of radiation. Gel dosimetry in India is not moving forward because of the import restrictions on the commercially available high bloom strength gelatin (imported 300 bloom). The feasibility of using Fricke gel dosimeter prepared with the locally available gelatin of 240 bloom and 200 bloom were compared with the 300 bloom gelatin taken as standard. The gel samples were prepared with 5% gelatin by weight and irradiated with 60Co gamma radiation for a dose range from 0-3 Gy used clinically. The optical absorption of gel samples were analyzed using spectrophotometer at 585 nm and dose response curves were generated. The results indicate that Fricke gels prepared with 240 bloom have linear dose response and comparable with those prepared with 300 bloom but the use of gels prepared with 200 bloom was found to be limited because of its poor optical transmittance.

Ebenezer Suman Babu, S.; Ravindran, B. Paul

2015-01-01

345

Block copolymer ion gels for gas separation  

Science.gov (United States)

Carbon dioxide removal from light gases (eg. N2, CH4, and H2) is a very important technology for industrial applications such as natural gas sweetening, CO2 capture from coal-fire power plant exhausts and hydrogen production. Current CO2 separation method uses amine-absorption, which is energy-intensive and requires frequent maintenance. Membrane separation is a cost-effective solution to this problem, especially in small-scale applications. Ionic liquids have recently received increasing interest in this area because of their selective solubility for CO2 and non-volatility. However, ionic liquid itself lacks the persistent structure and mechanical integrity to withstand the high pressure for gas separation. Here, we report the development and gas separation performances of physically crosslinked ion gels based on self-assembly of ABA-triblock copolymers in ionic liquids. Three different types of polymers was used to achieve gelation in ionic liquids. Specifically, a triblock copolymer ion gel with a polymerized ionic liquid mid-block shows performances higher than the upper bound of well-known ``Robeson Plot'' for CO2/N2.

Gu, Yuanyan; Lodge, Timothy

2012-02-01

346

DEVELOPMENT OF MELOXICAM SODIUM TRANSDERMAL GEL  

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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

347

Preparation of highly luminescent hybrid gel incorporating NAC-capped CdTe quantum dots through sol–gel processing  

Science.gov (United States)

Highly photoluminescent gel was prepared by embedding water soluble quantum dots (QDs) in an inorganic–organic hybrid gel matrix using a conventional sol–gel process. Aminopropyltrimethoxysilane and citric acid (CA) were found to be the best combination for the gel preparation. 13C-NMR and FT-IR studies indicated hydrogen bond formation between the amine group of APS and the carboxyl group of CA. IR-light radiation curing was comparable to thermal curing and reduced the gelation time to a considerable extent (71 %). The resulting composite formed a hybrid gel phosphor with excellent transparency by embedding CdTe QDs into the matrix and emitted light of various colors with high photoluminescence efficiency (40 %). The gel phosphor retained the PL properties after storage in air for one year. In addition, the strength of the hybrid phosphor was demonstrated by a coin-flipping test.

Bu, Hang-Beom; Watanabe, Taichi; Hizume, Masayuki; Takagi, Tomomi; Sobue, Susumu; Kawai, Shoichi; Okuno, Eiichi; Kim, DaeGwi

2015-03-01

348

The interactions between oil droplets and gel matrix affect the lubrication properties of sheared emulsion-filled gels  

OpenAIRE

In this work the lubrication behaviour of emulsions, gels, and emulsion-filled gels was studied in relation to their composition and structure. It was found that emulsions had much lower friction coefficients than their continuous phases. Emulsions with 40 wt% oil had the same friction coefficient as the pure oil. The lubrication properties of the gels, sheared by pressing them through a syringe, strongly depended on the molecular properties of the gelling agent and on the breakdown behaviour...

Chojnicka, A.; Sala, G.; Kruif, C. G.; Velde, F.

2009-01-01

349

13C-nuclear magnetic resonance study of benzene derivatives, ketones, and 1-hexene adsorbed on silica-gel, silver-silica-gel, and trimethylsilanized-silica-gel  

International Nuclear Information System (INIS)

13C-NMR measurements of benzene derivatives (benzene, toluene, o-xylene, m-xylene, p-xylene), ketones (acetone, methylethylketone), and l-hexene adsorbed on silica-gel, Ag-silica-gel, and TMS-silica-gel (trimethylsilanized-silica-gel) were carried out. Upon adsorption, all the methyl carbons of benzene derivatives showed upper field shifts ((0.8 -- 2.4)ppm) irrespective of adsorbents. In the case of benzene derivatives adsorbed on Ag-silica-gel, ring carbons at which a methyl group bonded gave lower field shifts ((0.6 -- 0.9)ppm), whereas other ring carbons showed upper field shifts ((0.8 -- 4.4)ppm). These chemical shifts data suggest a formation of ?-complex between surface silver ions and benzene rings. A C1 carbon of l-hexene on Ag-silica-gel gave an upper field shift (10.4 ppm) and gave the same result as benzene derivatives. All the carbonyl carbons of ketones adsorbed on any of silica-gel and modified ones showed a characteristic lower field chemical shift based on hydrogen bonds between carbonyl groups and surface silanol groups (=Si-OH) of various silica-gels. 13C-NMR spectra of the trimethylsilyl group (TMS-group) of TMS-silica-gel dispersed in various solvents were also measured. The TMS-group showed a broad line width (98Hz) and an upper field chemical shift (4.1 ppm) in the dry state, whereas, upon dispersing in solvents, both the line width and the chemical shifts were reduced to about half of those obtained without solvabout half of those obtained without solvents. (author)

350

Influence of Uranium and Polivinyl Alcohol Concentration in the Feed of Sol Gel Process on the Gel Spherical Product  

International Nuclear Information System (INIS)

The gel particles have been made at various uranium and polyvinyl alcohol concentration in the sol gel process. The variables of uranium concentration were 0.3; 0.5; 0.7; 0.9; 1.1; 1.3; 1.5; 1.7; 1.9 and 2.1 M The variables of polyvinyl alcohol concentration were 0.3; 0.6; 0.9; 1.2; 1.5; 1.8; 2.1 and 2.4 M After drying the sol gel process products were heated at 300, 500 and 750°C during 4 hours. The gel particles were characterized using an optic microscope to know the shape and condition morphology of gel. From experimental result using uranium concentration of 0.3 until 2.1 M and polyvinyl alcohol of 1.8 until 2.4 M spherical and gel was formed elastic, after heating at 750°C it was unbreakable. At the concentration of polyvinyl alcohol from 0.3 to 0.5 M, the gel product was soft and broken after being dried. At the concentration of polyvinyl alcohol from 0.6 to 0.8 M, the dried gel product was not perfect. At the concentration of polyvinyl alcohol from 0.9 to 1.7 M, the gel product of gelation process was spherical and it was broken after being heated up to 300°C. (author)

351

A new method for assigning common spot boundaries for multiple gels in two-dimensional gel electrophoresis.  

Science.gov (United States)

The benefits of defining common spot boundaries when several gels from 2-DE are compared and analyzed have lately been stressed by both commercial software producers and users of this software. Though the importance of common spot boundaries is clearly stated, few reports exist that target this issue explicitly. In this study a method for defining common spots boundaries is developed, called the spot density method. The method consists of the following steps: segmentation and spot identification on each individual gel, transferring the spot-center coordinates for all gels onto a single new gel, collecting spot centers clustered together in the new gel and finally assigning pixels and new spot boundaries based on the spots in each cluster. The method is compared to a synthetic gel approach, and validated by visual inspection of three representative areas in the gels. The gel images need to be aligned prior to segmentation and spot identification, but the method can be used regardless of the choice of segmentation procedure. This makes the method an easy extension to existing methods for spot identification and matching. Conclusions based on the visual inspection are that the spot density method identifies partly overlapping spots and low-intensity spots better than the synthetic gel approach. PMID:18348212

Rye, Morten Beck; Faergestad, Ellen M; Alsberg, Bjørn K

2008-03-01

352

Experimental properties of THPC based normoxic polyacrylamide gels for use in x-ray computed tomography gel dosimetry  

Science.gov (United States)

The aim of the present study is to investigate the effects of tetrakis(hydroxymethyl)phosphonium chloride (THPC) on the experimental properties of normoxic polyacrylamide gels. Specifically we: (1) assess the use of THPC as an anti-oxidant for x-ray CT PAGAT dosimetry by investigating dose response reproducibility and stability, and optimal THPC concentration for maximum dose sensitivity while ensuring no O2 inhibition; (2) investigate the reactions of THPC with gel constituents; (3) describe the reaction mechanisms of THPC in PAGAT polymer gels; (4) assess the effects of THPC on O2 diffusion through the polymer gel.

Jirasek, A.; Hilts, M.; Shaw, C.; Baxter, P.

2006-12-01

353

Modelling of the inhomogeneous interior of polymer gels  

International Nuclear Information System (INIS)

A simple model has been investigated to elucidate the mean squared displacement (MSD) of probe molecules in cross-linked polymer gels. In the model, we assume that numerous cavities distribute in the inhomogeneous interior of a gel, and probe molecules are confined within these cavities. The individual probe molecules trapped in a gel are treated as Brownian particles confined to a spherical harmonic potential. The harmonic potential is chosen to model the effective potential experienced by the probe particle in the cavity of a gel. Each field strength is corresponding to the characteristic of one type of effective cavity. Since the statistical distribution of different effective cavity sizes is unknown, several distribution functions are examined. Meanwhile, the calculated averaged MSDs are compared to the experimental data by Nisato et al (2000 Phys. Rev. E 61 2879). We find that the theoretical results of the MSD are sensitive to the shape of the distribution function. For low cross-linked gels, the best fit is obtained when the interior cavities of a gel follow a bimodal distribution. Such a result may be attributed to the presence of at least two distinct classes of cavity in gels. For high cross-linked gels, the cavities in the gel can be depicted by a single-modal uniform distribution function, suggesting that the range of cavity sizes becomes smaller. These results manifest the voids inside a gel, and the shape of distribution functions may provide the insightribution functions may provide the insight into the inhomogeneous interior of a gel

354

How deeply cells feel: methods for thin gels  

International Nuclear Information System (INIS)

Tissue cells lack the ability to see or hear but have evolved mechanisms to feel into their surroundings and sense a collective stiffness. A cell can even sense the effective stiffness of rigid objects that are not in direct cellular contact-like the proverbial princess who feels a pea placed beneath soft mattresses. How deeply a cell feels into a matrix can be measured by assessing cell responses on a controlled series of thin and elastic gels that are affixed to a rigid substrate. Gel elasticity E is readily varied with polymer concentrations of now-standard polyacrylamide hydrogels, but to eliminate wrinkling and detachment of thin gels from an underlying glass coverslip, vinyl groups are bonded to the glass before polymerization. Gel thickness is nominally specified using micron-scale beads that act as spacers, but gels swell after polymerization as measured by z-section, confocal microscopy of fluorescent gels. Atomic force microscopy is used to measure E at gel surfaces, employing stresses and strains that are typically generated by cells and yielding values for E that span a broad range of tissue microenvironments. To illustrate cell sensitivities to a series of thin-to-thick gels, the adhesive spreading of mesenchymal stem cells was measured on gel mimics of a very soft tissue (e.g. brain, E ? 1 kPa). Initial results show that cells increasingly respond to the rigidity of an underlying 'hidden' surface starting at about 10-20 ?m gel thickness with a charactt 10-20 ?m gel thickness with a characteristic tactile length of less than about 5 ?m.

355

Radiological properties of MAGIC normoxic polymer gel dosimetry  

Science.gov (United States)

For a polymer gel dosimeter to be of use in radiation dosimetry, it should display water-equivalent radiological properties. In this study, the radiological properties of the MAGIC (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper) normoxic polymer gels were investigated. The mass density (?) was determined based on Archimedes' principle. The weight fraction of elemental composition and the effective atomic number (Zeff) were calculated. The electron density was also measured with 90° scattering angle at room temperature. The linear attenuation coefficient (?) of unirradiated gel, irradiated gel, and water were determined using Am-241 based on narrow beam geometry. Monte Carlo simulation was used to calculate the depth doses response of MAGIC gel and water for 6MV photon beam. The weight fractions of elements composition of MAGIC gel were close to that for water. The mass density was found to be 1027 ± 2 kg m-3, which is also very close to mass density of muscle tissue (1030 kg m-3) and 2.7% higher than that of water. The electron density (?e) and atomic number (Zeff) were found to be 3.43 × 1029 e m-3 and 7.105, respectively. The electron density measured was 2.6% greater than that for water. The atomic number was very close to that for water. The prepared MAGIC gel was found to be water equivalent based on the study of element composition, mass density, electron density and atomic number. The linear attenuation coefficient of unirradiated gel was very close to that of water. The ? of irradiated gel was found to be linear with dose 2-40 Gy. The depth dose response for MAGIC gel from a 6 MV photon beam had a percentage dose difference to water of less than 1%. Therefore it satisfies the criteria to be a good polymer gel dosimeter for radiotherapy.

Aljamal, M.; Zakaria, A.; Shamsuddin, S.

2013-04-01

356

Sorption of neptunium(V) on silicate gels  

International Nuclear Information System (INIS)

Aqueous corrosion of nuclear waste glasses induces the formation of a gel layer enriched in hydrolyzable elements. To assess the role of such layers on the migration of Np(V) from repositories to environment, and determine the retention mechanisms, experiments have been undertaken on synthetic pure silica and on ferrisilicate gels as model solids. No detailed and systematic studies on silicate gels as scavengers for Np(V) appear to have been devoted to the influence of solution parameters and gel composition on the sorption of Np(V) on silicate gels. In this work, the fractional uptake of Np(V) on a synthetic pure silica gel and on synthetic ferrisilicate gels of controlled Si/Fe proportions (3 and 10) was measured at different ionic strengths (0.5 to 0.01 M) and Np(V) concentration levels ?10-10 M and 10-6 M with pH as the main variable (3 to 10). The pH dependence of Np(V) sorption on the alternation gel was also investigated for different initial concentrations of Np(V) in the aqueous phase ?10-10 M, 10-6 M and 10-5 M. Batch experiments were carried out at 298 K under CO2-free conditions to avoid the formation of Np(V) carbonate complexes in the solution. As a part of this work, the charge characteristics of the gel surfaces were determined either by studying the retention of the electrolyte ions as counterions to the surface charges, as a function of pH and ionic strength of the solution contacted with gels, or by performing acid/base titrations of the alteration gel suspensions. (J.P.N.)

357

Phase transitions in liquid crystal + aerosil gels  

Science.gov (United States)

Liquid Crystals (LCs) are found in many different phases, the most well-known, basic ones being Isotropic (I), Nematic (N), and Smectic-A (SmA). LCs show a rich variety of phase transitions between these phases. This makes them very interesting materials in which to study the basics of phase transitions and related topics. In the low symmetry phases, LCs show both positional and directional orders. X-ray scattering is an important tool to study these phase transitions as it probes the instantaneous positional correlations in these phases. Random forces have a nontrivial effect on ordering in nature, and the problem of phase transitions in the presence of a random field is a current and not well-understood topic. It has been found that aerosils posses a quenched randomness in the mixture of LC+aerosil samples, forming a gel random network which destroys long-range order (LRO) in the SmA phase. This can be modeled as a random field problem. In the N to SmA phase transition in 4O.8 LC (butyloxybenzlidene octylaniline), orientational order (N ) is modified by a 1-D density wave describing 2-D fluid layer spacing structure (SmA). Likewise the I to Sm A phase transition in 10CB LC (decylcyanobiphenyl), a transitional ordered phase develops without going through an orientational ordered phase. To study these phase transitions with aerosil dispersion carries the opportunity to probe the effect of induced quenched random disorder on phase transitions, which are 2nd order in the first case and 1st order in the second case. A two-component line-shape analysis is developed to define the phases in all temperature ranges. It consists of the thermal and the static structure factors. The reentered nematic (RN) phase of the [6:8]OCB+aerosil gels ([6:8]OCB is a mixture of hexyloxycyanobiphenyl and octyloxcyanobiphenyl) is another interesting case in which to study the quenched random disorder effects. The weak SmA phase of [6:8]OCB+aerosil gels is followed by a RN phase at low temperatures. The results of the studies of this thesis provide models for random filed systems. Particularly, the developed line-shape analysis can be used to analyze all random field problems in general.

Ramazanoglu, Mehmet Kerim

358

Treatment of cutaneous leishmaniasis: cassia fistula fruit gel- intralesional glucantime Vs. placebo gel- intralesional glucantime combination  

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Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: Cutaneous leishmaniasis is a major health problem in Iran and especially Isfahan province is considered as an endemic area for this disease. Regarding the previous report of positive effects of Cassia fistula boiled extract in the treatment of cutaneous leishmaniasis, this study was designed to evaluate the effect of combination therapy with intralesional meglumine antimoniate and Cassia fistula fruit gel compared to placebo in this disease."n"nMethods: 140 patients with cutaneous leishmaniasis referring to Skin Disease and Leishmaniasis Research Center of Isfahan (SDLRC were randomly allocated in two groups. One group received intralesional meglumine antimoniate injection and Cassia fistula fruit gel and the second group were treated with intralesional meglumine antimoniate and placebo gel. Improvement was defined as complete cure, partial cure and treatment failure. "n"nResults: At 12 week, 47 patients treated with intralesional meglumine antimoniate and topical Cassia fistula fruit gel achieved complete cure (67.1% compared to 29(41.4% patients in placebo treated group. There was significant difference in cure rate between two treatment groups of this study (p<0.001. Nine patients (19% in each group suffered from adverse effects of the treatment such as itching and erythema. There was no significant difference in this regard between two groups (p=0.82. "n"nConclusions: The results of this study shows the efficacy of Cassia fistula fruit gel in increasing the cure rate of cutaneous leishmaniasis lesions achieved by intralesional meglumine antimoniate. Combination therapy of intralesional meglumine antimoniate and Cassia fistula fruit gel could be suggested as a choice for the treatment of acute cutaneous leishmaniasis lesions.

Jaffary F

2010-01-01

359

Enhanced transdermal delivery of ketoprofen from bioadhesive gels.  

Science.gov (United States)

The aim of this study was to evaluate and compare the in vitro and in vivo transdermal potential of bioadhesive gels of ketoprofen by using gelling polymers like sodium carboxymethylcellulose, xanthan gum, poloxamer 407 and carbopol 934P as bioadhesive polymer with and without penetration enhancer (oleic acid). The effect of oleic acid as a penetration enhancer was examined when it was added to the bioadhesive formulations. Gels were evaluated for bioadhesive force and viscosity. To study the in vitro potential of these formulations, permeation studies were performed with Franz diffusion cell using excised rat abdominal skin. Carrageenan induced rat paw edema model was used to investigate their in vivo performance. The commercial formulation of ketoprofen was used as a reference formulation. The in vitro permeation studies indicate that ketoprofen bioadhesive gel of poloxamer 407 with penetration enhancer was superior to gels of sodium carboxymethylcellulose and xanthan gum with penetration enhancer (oleic acid). The permeation rate of ketoprofen from poloxamer 407 based bioadhesive gel with 15% v/w penetration enhancer was higher (rat abdominal skin flux = 0.421 +/- 0.032 mg/cm(2)/h) than the permeation rate of sodium carboxymethylcellulose and xanthan gum based bioadhesive gel with 15% v/w penetration enhancer. In the paw edema test poloxamer 407 based bioadhesive gel with 15% v/w penetration enhancer showed the best permeation and effectiveness. The in vitro and in vivo studies showed that bioadhesive gels of ketoprofen could be used for effective therapy. PMID:19339232

Singh, S; Gajra, B; Rawat, M; Muthu, M S

2009-04-01

360

Biocatalysis with Sol-Gel Encapsulated Acid Phosphatase  

Science.gov (United States)

This experiment was performed in an upper-level undergraduate biochemistry laboratory course. Students learned how to immobilize an enzyme in a sol-gel matrix and how to perform and evaluate enzyme-activity measurements. The enzyme acid phosphatase (APase) from wheat germ was encapsulated in sol-gel beads that were prepared from the precursor…

Kulkarni, Suhasini; Tran, Vu; Ho, Maggie K.-M.; Phan, Chieu; Chin, Elizabeth; Wemmer, Zeke; Sommerhalter, Monika

2010-01-01

361

Ion - exchange properties of tungstocerate (IV) gel matrices  

International Nuclear Information System (INIS)

Heteropolyacids and their salts have found a wide spread use in industry and nuclear applications. Some heteropolysolid matrices of Mo(VI) and W(VI) exhibit fairly good chemical stability towards high temperature and ionizing radiation as well as high selectivity to metal ions in mineral acid solutions. Tungstocerate(IV) gel matrices can be prepared in the form of granular particles suitable for packing into the form of chromatographic columns, which have found versatile applications in radiochemical separation, and concentration of radionuclides from aqueous solutions. The high mechanical stability of tungstocerate(IV) gel matrices is promising for use as the base matrix of chromatographic columns. The present study will include investigation of (ion exchange properties of tungstocerate(IV) gel matrices) as the following:1-Preparation of the tungstocerate(IV) gel matrices by mixing solutions of sodium tungstate with ammonium cerium sulfate.2-Characterization of the physical and chemical properties of the prepared gel matrix: stability in mineral acid solutions and their salts, density, crystallinity, infra-red spectra, thermal analysis, acidity, etc.3-Investigation of the selectivity patterns of the gel matrix for some radionuclides from aqueous solutions.4-Determination of the sorption capacity of the gel matrix for some metal cations from aqueous solutions.5-Applications of the gel matrix in radiochemical separation of mixture of radionuclides from each other, prepure of radionuclides from each other, preparation of radioisotope generators and preconcentration of radionuclides from waste solutions

362

Long-range forces extending from polymer-gel surfaces  

CERN Document Server

Aqueous suspensions of microspheres were infused around gels of varying composition. The solutes were excluded from zones on the order of 100 micrometers from the gel surface. We present evidence that this finding is not an artifact, and that solute-repulsion forces exist at distances far greater than conventional theory predicts. The observations imply that solutes may interact over an unexpectedly long range.

Zheng, J; Zheng, Jian-ming; Pollack, Gerald H.

2003-01-01

363

Optimized conditions for pulsed field gel electrophoretic separations of DNA.  

OpenAIRE

Quantitative measurement of DNA migration in gel electrophoresis requires precisely controlled homogeneous electric fields. A new electrophoresis system has allowed us to explore several parameters governing DNA migration during homogeneous field pulsed field gel (PFG) electrophoresis. Migration was measured at different switch times, temperatures, agarose concentrations, and voltage gradients. Conditions which increase DNA velocities permit separation over a wider size range, but reduce reso...

Birren, B. W.; Lai, E.; Clark, S. M.; Hood, L.; Simon, M. I.

1988-01-01

364

Raman study of lower toxicity polymer gel for radiotherapy dosimetry  

Science.gov (United States)

N-isopropyl acrylamide (NIPAM) monomer and N, N' – methylene-bis-acrylamide (BIS) crosslinker were used to synthesize polymer gel dosimeters for a reason that the monomer is lower toxicity which gives a significant advantage over the other polymer gel compositions. The gels were irradiated with Co-60 gamma rays at doses up to 21 Gy and the irradiated NIPAM polymer gels were used to investigate the dose response characteristics based on Raman spectroscopy analysis on the formation of the polymer gels and the consumptions of NIPAM and BIS co-monomers. From the findings, the polymerization was referred to an increment in Raman intensity at 815 cm?1, assigned for C-C stretching mode of NIPAM polymer gel, as the dose increased. The consumptions of the co-monomers were referred to a decrement in Raman intensities at 1025 cm?1 2353 cm?1 for C=C stretching modes of NIPAM and BIS respectively as the dose increased. The increment and decrement in Raman intensities of polymer and co-monomers respectively with increase of dose indicate that there is occurrence of polymerization of NIPAM polymer gels which could be applied in 3D dose distributions for radiotherapy treatment planning. The correlation factor kBIS is greater than kNIPAM showing that the reaction of BIS crosslinker is more efficient than NIPAM monomer to generate 37% of the NIPAM polymer gel.

Adenan, M. Z.; Ahmad, M.; Mohd Noor, N.; Deyhimihaghighi, N.; Saion, E.

2014-11-01

365

Phase behavior and rheological characterization of silica nanoparticle gel  

Science.gov (United States)

Preferential injection into high permeability thief zones or fractures can result in early breakthrough at production wells and large unswept areas of high oil saturation, which impact the economic life of a well. A variety of conformance control techniques, including polymer and silica gel treatments, have been designed to block flow through the swept zones. Over a certain range of salinities, silica nanoparticle suspensions form a gel in bulk phase behavior tests. These gels have potential for in situ flow diversion, but in situ flow tests are required to determine their applicability. To determine the appropriate scope of the in situ tests, it is necessary to obtain an accurate description of nanoparticle phase behavior and gel rheology. In this paper, the equilibrium phase behavior of silica nanoparticle solutions in the presence of sodium chloride (NaCl) is presented with four phase regions classified as a function of salinity and nanoparticle concentration. Once the gelation window was clearly defined, rheology experiments of silica nanoparticle gels were also carried out. Gelation time decreases exponentially as a function of silica concentration, salinity, and temperature. Following a power law behavior, the storage modulus, G', increases with particle concentration. Steady shear measurements show that silica nanoparticle gels exhibit non-Newtonian, shear thinning behavior. This comprehensive study of the silica nanoparticle gels has provided a clear path forward for in situ tests to determine the gel's applicability for conformance control operations.

Metin, Cigdem O.; Rankin, Kelli M.; Nguyen, Quoc P.

2014-01-01

366

Self diffusion of chloride ion in agar gel  

International Nuclear Information System (INIS)

Self-diffusioin of labelled chloride ion through the solution of potassium chloride in agar-agar gel medium with concentration is studied by the zone-diffusion technique. The experimental values of Dsup(*) and theoretical Dsup(*) are compared. The effect of varying the gel percentage on Dsup(*) was also studied. (author)

367

High-resolution gel dosimetry of a HDR brachytherapy source using normoxic polymer gel dosimeters: Preliminary study  

International Nuclear Information System (INIS)

Polymer gel dosimetry has been shown to be an effective tool in the analysis of radiotherapy treatments in cancer therapy, being used to map the dose distribution around an irradiation pattern of a polymer gel dosimeter. Combined with high-resolution magnetic resonance imaging (MRI), polymer gel dosimetry can be an effective dosimetry tool to map dose distributions with high spatial resolution (?100 ?m). Previously polyacrylamide polymer gel dosimetry required a strict hypoxic environment to protect the gel from oxygen infiltration as oxygen inhibits the polymerization reaction used to correlate to absorbed dose. However, with the advent of normoxic polymer gels, a strict hypoxic environment is not required. Normoxic polymer gel dosimeters can be manufactured under normal atmospheric conditions. This study assessed the use of a MAGIC normoxic polymer gel dosimeter to accurately map the dose distribution of a single-line irradiation and a point source irradiation from a brachytherapy radiation source administered through a nylon catheter inserted into the gel dosimeter. The phantoms were irradiated to a dose of 10 Gy at 2 mm from the source center and imaged using high-resolution MRI with an in-plane pixel size of 0.1055 mm/pixel. Good agreement was found between the dose points predicted by the computer treatment-planning system and the measured normalized dose profiles in the gel dosimeter. The use of normoxic polymer gel dosimeters with high-resolution MRI evaluaimeters with high-resolution MRI evaluation shows promise as an effective tool in applications requiring accurate dose distributions in high resolution, such as intravascular brachytherapy

368

Zirconyl-containing microspheric silica gel surfaces  

Science.gov (United States)

The adsorption properties of two samples of zirconyl-containing silica gels derived from zirconium oxychloride, polyetoxysiloxane oligomer 3% ZrOCl2/SiO2 (composite 1) and tetraetoxysilane 5% ZrOCl2/SiO2 (composite 2) were investigated by gas chromatography at low surface coverages. n-Alkanes and n-alkenes (C6-C8), C6H6 were used as test adsorbates, along with polar compounds whose molecules had different donor-acceptor interaction abilities. The dispersion and specific (electron-donor and electronacceptor) components of the energy of intermolecular interactions for the studied systems were determined from the experimental data on chromatographic retention. It was shown that composite 2 had a higher dispersion potential and higher surface energy characteristics of the surface's electron-donating and electronacceptor centers, as compared to composite 1.

Lanin, S. N.; Kabulov, B. D.; Vlasenko, E. V.; Kovaleva, N. V.; Lanina, K. S.; Strepetova, T. A.; Akhundzhanov, K. A.; Yunusov, F. U.

2011-01-01

369

Sol-gel processing of energetic materials  

Energy Technology Data Exchange (ETDEWEB)

As part of a new materials effort, we are exploring the use of sol- gel chemistry to manufacture energetic materials. Traditional manufacturing of energetic materials involves processing of granular solids. One application is the production of detonators where powders of energetic material and a binder are typically mixed and compacted at high pressure to make pellets. Performance properties are strongly dependent on particle size distribution, surface area of its constituents, homogeneity of the mix, and void volume. The goal is to produce detonators with fast energy release rate the are insensitive to unintended initiation. In this paper, we report results of our early work in this field of research, including the preparation of detonators from xerogel molding powders and aerogels, comparing the material properties with present state-of-the-art technology.

Tillotson, T.M.; Hrubesh, L.H.; Fox, G.L.; Simpson, R.L.; Lee, R.W.; Swansiger, R.W.; Simpson, L.R.

1997-08-18

370

Clotrimazole nanoparticle gel for mucosal administration  

International Nuclear Information System (INIS)

In this study a formulation suitable to be applied on oral and/or vaginal mucosa has been developed for the treatment of fungal infections. The aim of the research is a comparison between clotrimazole (CLO) containing semisolid formulations based on monoolein aqueous dispersion (MAD) or nanostructured lipid carrier (NLC). MAD and NLC have been characterized in terms of morphology and dimensional distribution by cryogenic Transmission Electron Microscopy (cryo-TEM) and Photon Correlation Spectroscopy (PCS). CLO was encapsulated with high entrapment efficiency both in MAD and in NLC, according to Sedimentation Field Flow Fractionation (SdFFF) combined with HPLC. CLO recovery in MAD and NLC has been investigated by time. In order to obtain formulations with suitable viscosity for mucosal application, MAD was diluted with a carbomer gel, while NLC was directly viscosized by the addition of poloxamer 407 in the dispersion. The rheological properties of MAD and NLC after viscosizing have been investigated. Franz cell has been employed to study CLO diffusion from the different vehicles, evidencing diffusion rates from MAD and NLC superimposable to that obtained using Canesten®. An anticandidal activity study demonstrated that both CLO-MAD and CLO-NLC were more active against Candida albicans with respect to the pure drug. Highlights: ? Comparison between monoolein aqueous dispersion (MAD) and nanostructured lipid carrier (NLC). ? Clotrimazole (CLO) encapsulatNLC). ? Clotrimazole (CLO) encapsulated with high entrapment efficiency both in MAD and in NLC. ? The solid matrix of NLC controls CLO degradation better than MAD. ? CLO containing MAD and NLC exhibits a higher anticandidal activity than the free drug. ? Simple production of CLO-NLC based poloxamer gel, suitable for industry scaling up

371

Clotrimazole nanoparticle gel for mucosal administration  

Energy Technology Data Exchange (ETDEWEB)

In this study a formulation suitable to be applied on oral and/or vaginal mucosa has been developed for the treatment of fungal infections. The aim of the research is a comparison between clotrimazole (CLO) containing semisolid formulations based on monoolein aqueous dispersion (MAD) or nanostructured lipid carrier (NLC). MAD and NLC have been characterized in terms of morphology and dimensional distribution by cryogenic Transmission Electron Microscopy (cryo-TEM) and Photon Correlation Spectroscopy (PCS). CLO was encapsulated with high entrapment efficiency both in MAD and in NLC, according to Sedimentation Field Flow Fractionation (SdFFF) combined with HPLC. CLO recovery in MAD and NLC has been investigated by time. In order to obtain formulations with suitable viscosity for mucosal application, MAD was diluted with a carbomer gel, while NLC was directly viscosized by the addition of poloxamer 407 in the dispersion. The rheological properties of MAD and NLC after viscosizing have been investigated. Franz cell has been employed to study CLO diffusion from the different vehicles, evidencing diffusion rates from MAD and NLC superimposable to that obtained using Canesten{sup Registered-Sign }. An anticandidal activity study demonstrated that both CLO-MAD and CLO-NLC were more active against Candida albicans with respect to the pure drug. Highlights: Black-Right-Pointing-Pointer Comparison between monoolein aqueous dispersion (MAD) and nanostructured lipid carrier (NLC). Black-Right-Pointing-Pointer Clotrimazole (CLO) encapsulated with high entrapment efficiency both in MAD and in NLC. Black-Right-Pointing-Pointer The solid matrix of NLC controls CLO degradation better than MAD. Black-Right-Pointing-Pointer CLO containing MAD and NLC exhibits a higher anticandidal activity than the free drug. Black-Right-Pointing-Pointer Simple production of CLO-NLC based poloxamer gel, suitable for industry scaling up.

Esposito, Elisabetta, E-mail: ese@unife.it [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Ravani, Laura [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Contado, Catia [Department of Chemistry, University of Ferrara, Ferrara (Italy); Costenaro, Andrea [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Drechsler, Markus [Macromolecular Chemistry II, University of Bayreuth (Germany); Rossi, Damiano [Department of Biology and Evolution, LT Terra and Acqua Tech UR7, University of Ferrara, Ferrara (Italy); Menegatti, Enea [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Grandini, Alessandro [Department of Biology and Evolution, LT Terra and Acqua Tech UR7, University of Ferrara, Ferrara (Italy); Cortesi, Rita [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy)

2013-01-01

372

Polyacrylamide gels synthesized in the presence of surfactants  

Science.gov (United States)

The polymerization of acrylamide monomers in the presence of surfactant self-assemblies produces gels with variable pore architecture. Polyacrylamide gels were formed by polymerizing acrylamide plus a cross-linker in the presence of surfactants, which were then removed by soaking in distilled water. Gels formed in the presence of over 28% surfactant (by weight) formed clear, but became opaque upon removal of the surfactants. Other gels formed and remained clear. Several analytical techniques such as X-ray Scattering, Dynamic Rheology measurements, Optical Polarized Microscopy, and Atomic Force Microscopy (AFM) have been used to characterize the formation and the resulting gel structure. The surface morphology as imaged by AFM was studied by numerical scaling analysis. The surface morphology of the gels was studied by several one- and two-dimensional numerical scaling methods. The structure of the final gels were highly dependent on the amount of surfactant present during the formation of gels. At low surfactant concentrations (micelles are randomly distributed throughout the gel matrix. The average spacing between individual micelles is about 10 nm as indicated by X-ray scattering experiments. When the TTAB concentration is increased to moderate levels (25--28%), though the surfactant micelles are randomly distributed, a few surfactant-rich regions may form in the gel matrix. At high TTAB concentrations, phase separation of TTAB from the polymer leads to the formation of many surfactant-rich domains. A model for the gel structure based on symmetry and packing considerations for lattices of spheres of different concentrations was developed. This model was successfully used to interpret the physical observations, the experimental results, and the results from the scaling analysis. Highly porous gel networks with a high degree of mechanical strength have thus been synthesized. The controlled modification of gel structure provides new opportunities in the development of novel materials. A few areas of application include enzyme fixation for building biosensors, controlled release systems for drug delivery, support matrices for bio-molecule separation. The process of gel formation in the presence of unreactive surfactants can also be extended to alter the structure of other polymer materials.

Chakrapani, Mukundan

373

Characterization of a humic gel synthesized from an activated epoxy silica gel  

International Nuclear Information System (INIS)

Purified humic acid has been covalently bound on activated epoxy silica gel particles. Determination of physical properties and chemical properties was conducted in order to characterize the material at different stages of the preparation. FTIR spectra and the PEC of the surface bound humic acid is very similar to that of humic acid starting material. This shows that the humic acid was not deteriorated during the surface binding process. This humic gel can be used as an analogue for sediment associated humic acid, with the advantage that covalently bound humic acid does not desorb, and thus allows for simple species separation between non-complexed and humic bound metal ions in batch and column experiments

374

Modelling of erosion of bentonite gel by gel/sol flow  

International Nuclear Information System (INIS)

Bentonite intrusion into a fracture intersecting the canister deposition hole is modelled. The model describes the expansion of the bentonite within the fracture. It accounts for the repulsive electrostatic double-layer forces, the attractive van der Waals forces and friction forces between the particles and the water. The model also takes into account the diffusion of the colloid particles in the smectite sol. Diffusion of a counterion, sodium, is accounted for as this strongly influences the double layer force and the viscosity of the gel/sol. The gel/sol is considered to be a fluid with a varying viscosity that is strongly dependent on the bentonite volume fraction in the gel and the sodium concentration in the water. Two different geometries were modelled; a rectangular and a cylindrical. The rectangular geometry was used to gain experience with the processes and mechanisms and how they interact since the cylindrical geometry was somewhat less stable numerically and more time consuming. In the rectangular geometry a fracture 1 metre long in the flow direction was modelled. In both geometries the fracture size was selected sufficiently large to ensure that the water velocity, near the distant border was nearly the same as the approaching water velocity and that the smectite concentration there was vanishingly small. It was found that the velocity of the fluid drops considerably where the bentonite volume fraction is larger than 1-2%. This is due to the strong increase in viscosity with increasing bentonite volume fraction. The loss of smectite by the slowly flowing fluid was found to be proportional to the square root of the seeping water velocity for the rectangular geometry. For the cylindrical geometry, the dependence is somewhat lower (exponent about 0.4) since the length of the gel/water interface decreases with increasing water flow rate. The penetration depth of the gel/water interface decreases with increasing water flow rate. For water velocity of the order of a metre per year the gel may penetrate several metres into the fracture when steady state is reached. The simulations were made with only sodium as counterion. Most simulations had sodium concentrations below the critical coagulation concentration, CCC. In the compacted bentonite at the fracture mouth it was 10 mM and 0.1 mM in the approaching water. At these concentrations the gel is expansive and can turn into a sol releasing colloidal particles. The low ion concentration has a strong impact on the fluid viscosity, which increases with decreasing ionic strength. At the same time, however the repulsion forces between the smectite particles increase causing a quicker expansion. Simulations with higher sodium concentrations had a marginal influence on the erosion rate. For the highest water flow rates the smectite loss could be up to 0.3 kg per year for one canister. This is more than one order of magnitude larger than what could be reached by smectite particle diffusion alone if fluid flow was neglected. In experiments in downward facing slits (fractures) it has been found that bentonite releases gel agglomerates much faster than expected. These are released and sediment also under conditions where it is expected that the smectite particles should have separated into individual smectite sheets, which would not noticeably be influenced by gravity. The reasons for this behaviour are not understood. In the modelling it is assumed that there are no other larger non-smectite particles that would be left behind to gradually build up a bed of particles that could act as filter, slowing down or even straining further smectite penetration into the fracture. The modelling results could therefore be highly pessimistic because bentonites contain tens of percent of accessory minerals that do not form colloids and the presence of which may cause the expansion to be slowed down by friction against the fracture walls

375

Modelling of erosion of bentonite gel by gel/sol flow  

Energy Technology Data Exchange (ETDEWEB)

Bentonite intrusion into a fracture intersecting the canister deposition hole is modelled. The model describes the expansion of the bentonite within the fracture. It accounts for the repulsive electrostatic double-layer forces, the attractive van der Waals forces and friction forces between the particles and the water. The model also takes into account the diffusion of the colloid particles in the smectite sol. Diffusion of a counterion, sodium, is accounted for as this strongly influences the double layer force and the viscosity of the gel/sol. The gel/sol is considered to be a fluid with a varying viscosity that is strongly dependent on the bentonite volume fraction in the gel and the sodium concentration in the water. Two different geometries were modelled; a rectangular and a cylindrical. The rectangular geometry was used to gain experience with the processes and mechanisms and how they interact since the cylindrical geometry was somewhat less stable numerically and more time consuming. In the rectangular geometry a fracture 1 metre long in the flow direction was modelled. In both geometries the fracture size was selected sufficiently large to ensure that the water velocity, near the distant border was nearly the same as the approaching water velocity and that the smectite concentration there was vanishingly small. It was found that the velocity of the fluid drops considerably where the bentonite volume fraction is larger than 1-2%. This is due to the strong increase in viscosity with increasing bentonite volume fraction. The loss of smectite by the slowly flowing fluid was found to be proportional to the square root of the seeping water velocity for the rectangular geometry. For the cylindrical geometry, the dependence is somewhat lower (exponent about 0.4) since the length of the gel/water interface decreases with increasing water flow rate. The penetration depth of the gel/water interface decreases with increasing water flow rate. For water velocity of the order of a metre per year the gel may penetrate several metres into the fracture when steady state is reached. The simulations were made with only sodium as counterion. Most simulations had sodium concentrations below the critical coagulation concentration, CCC. In the compacted bentonite at the fracture mouth it was 10 mM and 0.1 mM in the approaching water. At these concentrations the gel is expansive and can turn into a sol releasing colloidal particles. The low ion concentration has a strong impact on the fluid viscosity, which increases with decreasing ionic strength. At the same time, however the repulsion forces between the smectite particles increase causing a quicker expansion. Simulations with higher sodium concentrations had a marginal influence on the erosion rate. For the highest water flow rates the smectite loss could be up to 0.3 kg per year for one canister. This is more than one order of magnitude larger than what could be reached by smectite particle diffusion alone if fluid flow was neglected. In experiments in downward facing slits (fractures) it has been found that bentonite releases gel agglomerates much faster than expected. These are released and sediment also under conditions where it is expected that the smectite particles should have separated into individual smectite sheets, which would not noticeably be influenced by gravity. The reasons for this behaviour are not understood. In the modelling it is assumed that there are no other larger non-smectite particles that would be left behind to gradually build up a bed of particles that could act as filter, slowing down or even straining further smectite penetration into the fracture. The modelling results could therefore be highly pessimistic because bentonites contain tens of percent of accessory minerals that do not form colloids and the presence of which may cause the expansion to be slowed down by friction against the fracture walls

Moreno, Luis; Neretnieks, Ivars; Longcheng Liu (Chemical Engineering and Technology, School of Chemical Science and Engineering, Royal Institute of Technology, Stockholm (Sweden))

2010-11-15

376

Characterization of a humic gel synthesized from an activated epoxy silica gel  

Energy Technology Data Exchange (ETDEWEB)

Purified humic acid has been covalently bound on activated epoxy silica gel particles. Determination of physical properties and chemical properties was conducted in order to characterize the material at different stages of the preparation. FTIR spectra and the PEC of the surface bound humic acid is very similar to that of humic acid starting material. This shows that the humic acid was not deteriorated during the surface binding process. This humic gel can be used as an analogue for sediment associated humic acid, with the advantage that covalently bound humic acid does not desorb, and thus allows for simple species separation between non-complexed and humic bound metal ions in batch and column experiments.

Barbot, C.; Pieri, J.; Durand, J.P.; Goudard, F. [Nantex Univ. (France). Lab. de Biochimie et Radiobiochimie; Czerwinski, K.; Vial, M. [Massachusetts Inst. of Technology, Cambridge, MA (United States). Nuclear Engineering Dept.; Buckau, G.; Kim, J.I. [Forschungszentrum Karlsruhe Umwelt und Technik GmbH (Germany). Inst. fuer Nukleare Entsorgung; Moulin, V. [CEA, Gif-sur-Yvette (France). Nuclear Energy Div.

2002-07-01

377

Opportunities for sol-gel materials in fuel cells  

International Nuclear Information System (INIS)

Fuel cells are electrochemical devices that convert the chemical energy of a fuel and oxidant directly to electrical energy. Three types of fuel cells are (a) proton-exchange membrane fuel cells (PEMFC), (b) molten carbonate fuel cells (MCFC) and (c) solid oxide fuel cells (SOFC). In each case, there is a role for sol-gel processing. In the case of PEMFC, sol-gel modifications to the membrane are designed to increase the operating temperature. In the case of MCFC, sol-gel corrosion barriers extend the lifetime of the current collector. Finally, sol-gel processing is being used to assemble the electrolyte and electrode layers in SOFC and related oxygen generating devices. Examples are given for the application of sol-gel processing in each system, pointing out the derived benefits and areas for further development. (author)

378

Microscopic Picture of Cooperative Processes in Restructuring Gel Networks  

Science.gov (United States)

Colloidal gel networks are disordered elastic solids that can form even in extremely dilute particle suspensions. With interaction strengths comparable to the thermal energy, their stress-bearing network can locally restructure via breaking and reforming interparticle bonds. This allows for yielding, self-healing, and adaptive mechanics under deformation. Designing such features requires controlling stress transmission through the complex structure of the gel and this is challenging because the link between local restructuring and overall response of the network is still missing. Here, we use a space resolved analysis of dynamical processes and numerical simulations of a model gel to gain insight into this link. We show that consequences of local bond breaking propagate along the gel network over distances larger than the average mesh size. This provides the missing microscopic explanation for why nonlocal constitutive relations are necessary to rationalize the nontrivial mechanical response of colloidal gels.

Colombo, Jader; Widmer-Cooper, Asaph; Del Gado, Emanuela

2013-05-01

379

Foam and gel methods for the decontamination of metallic surfaces  

Science.gov (United States)

Decontamination of nuclear facilities is necessary to reduce the radiation field during normal operations and decommissioning of complex equipment. In this invention, we discuss gel and foam based diphosphonic acid (HEDPA) chemical solutions that are unique in that these solutions can be applied at room temperature; provide protection to the base metal for continued applications of the equipment; and reduce the final waste form production to one step. The HEDPA gels and foams are formulated with benign chemicals, including various solvents, such as ionic liquids and reducing and complexing agents such as hydroxamic acids, and formaldehyde sulfoxylate. Gel and foam based HEDPA processes allow for decontamination of difficult to reach surfaces that are unmanageable with traditional aqueous process methods. Also, the gel and foam components are optimized to maximize the dissolution rate and assist in the chemical transformation of the gel and foam to a stable waste form.

Nunez, Luis; Kaminski, Michael Donald

2007-01-23

380

Molecular Gels Materials with Self-Assembled Fibrillar Networks  

CERN Document Server

Molecular gels and fibrillar networks – a comprehensive guide to experiment and theory Molecular Gels: Materials with Self-Assembled Fibrillar Networks provides a comprehensive treatise on gelators, especially low molecular-mass gelators (LMOGs), and the properties of their gels. The structures and modes of formation of the self-assembled fibrillar networks (SAFINs) that immobilize the liquid components of the gels are discussed experimentally and theoretically. The spectroscopic, rheological, and structural features of the different classes of LMOGs are also presented. Many examples of the application of the principal analytical techniques for investigation of molecular gels (including SANS, SAXS, WAXS, UV-vis absorption, fluorescence and CD spectroscopies, scanning electron, transmission electron and optical microscopies, and molecular modeling) are presented didactically and in-depth, as are several of the theories of the stages of aggregation of individual LMOG molecules leading to SAFINs. Several actua...

Weiss, Richard G

2006-01-01

381

Study of the application of polymeric gels in porous media  

Energy Technology Data Exchange (ETDEWEB)

Crosslinking experiments with polyacrylamide and cellulosic polymers using chromium and aluminum as crosslinking cations have been performed in glass tubes as well as in Berea sandstone plugs. The dependence of gel strength on salinity, polymer concentration and concentration of the crosslinking agents was investigated to determine optimum conditions. For a given polymer concentration the gel strength was found to peak at optimum concentrations of the crosslinking agents and declined at higher concentrations. Comparisons of gel strengths between the tube and porous media measurements show that the concentrations of crosslinking agents required for maximum gel strength are considerably higher in Berea sandstone plugs than those in glass tube experiments. It was found that, at low polyacrylamide concentrations, gels did not form, yet mobility reduction still occurred. The basis for the reduction was determined to be due to the precipitation of the polymer from solution, which then plugged the porous medium. 19 refs.

Batycky, J.P.; Maini, B.B.; Milosz, G.

1982-01-01

382

Processing and characterization of Aloe vera gel for hydrogel preparation  

International Nuclear Information System (INIS)

This work describes the processing and characterization of Aloe vera gel for the preparation of hydrogels through gamma radiation from polymers and natural products in order to be used in biomedical applications. Processing was carried out immersing slices of aloe in distilled water for phenolic compound extraction. Through UV-VIS spectroscopy, 48 hours was determined as the optimal soaking time, at which organoleptic characteristics of the gel as well as its pH were acceptable. An increase of pH was observed on the gel that was stored at room temperature. The non processed gel showed a pink coloration. Results of gel yield values were not high. Microbiological tests showed a high bioburden. (author)

383

Optical CT evaluation on normoxic polymer gel dosimeter  

International Nuclear Information System (INIS)

Optical computed tomography has been shown to be a potentially useful imaging tool for the radiation therapy physicists. In radiation therapy, researchers have used optical CT for the readout of 3D dosimeters. The purpose of this paper is to explicate the initial evaluation of a newly fabricated laser CT scanner for '3D gel dosimetry' which works in the first generation principle. The normoxic PAGAT (Polyacrylamide Gelatin and Tetrakis) gel is used as a dosimeter for this analysis. When laser passes through this gel phantom, absorption and scattering of photon take place. The optical attenuation coefficient of the laser can be obtained by measuring its intensity after passing through the gel by a sensor.The scanner motion is controlled by the program written in Microsoft Visual C++. Reconstruction and data analysis on the irradiated gel phantom is performed by suitable algorithm using Matlab software. (author)

384

Laser CT evaluation on normoxic PAGAT gel dosimeter  

Science.gov (United States)

Optical computed tomography has been shown to be a potentially useful imaging tool for the radiation therapy physicists. In radiation therapy, researchers have used optical CT for the readout of 3D dosimeters. The purpose of this paper is to describe the initial evaluation of a newly fabricated laser CT scanner for 3D gel dosimetry which works using the first generation principle. A normoxic PAGAT (Polyacrylamide Gelatin and Tetrakis) gel is used as a dosimeter for this analysis. When a laser passes through the gel phantom, absorption and scattering of photon take place. The optical attenuation coefficient of the laser can be obtained by measuring its intensity after passing through the gel by a sensor. The scanner motion is controlled by a computer program written in Microsoft Visual C++. Reconstruction and data analysis on the irradiated gel phantom is performed by suitable algorithm using Matlab software.

Kumar, D. S.; Samuel, E. J. J.; Watanabe, Y.

2013-06-01

385

PC based automated sol-gel pilot plant  

International Nuclear Information System (INIS)

Sol-gel process offers an easy wet chemical route for preparation of fuel elements in the form of microspheres of desired size. The system is designed for preparation of dry gel particles of uranium oxide and uranium-plutonium oxide. Processes involved are pre mixing, feed dispersion, gel formation, washing and drying of gel particles. The sol-gel assembly with a production capacity of ?3 kg/day is housed in an eight module glove box. To execute different process sequences a PC based system has been developed. PC is the main system controller. Control of process involves control of liquid flow, solenoid valves, pneumatic valves, pumps, level control sequence, time based sequence, conductivity based sequence etc. Peripheral instruments associated with PC are level controllers, pressure indicator unit, power oscillator, conductivity meter, silicon oil heating unit and belt drying unit. (author). 4 refs., 1 fig

386

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 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.

2008-12-01

387

Theory of Sol-Gel Transition in Thermoreversible Gels with due Regard for Fundamental Role of Mesoscopic Cyclization Effects. I. Thermodynamic and Structural Characteristics of Gel Phase  

OpenAIRE

The sol-gel transition (SGT), upon which the infinite cluster (IC) of thermoreversibly bonded particles (gel fraction) appears against a background of a set of finite clusters (sol fraction), is first quantitatively considered with due regard for large and complicated (mesoscopic) cycles inevitably present in the IC. To this end we present a new approach based on a concept of the monomer identity breaking and density functional description. We strictly derive, via a proper c...

Erukhimovich, Igor; Thamm, Michael V.; Ermoshkin, Alexander V.

2001-01-01

388

Formulation of Niosomal Gel for Enhanced Transdermal Lopinavir Delivery and Its Comparative Evaluation with Ethosomal Gel  

OpenAIRE

The aim was to develop niosomal gel as a transdermal nanocarrier for improved systemic availability of lopinavir. Niosomes were prepared using thin-film hydration method and optimized for molar quantities of Span 40 and cholesterol to impart desirable characteristics. Comparative evaluation with ethosomes was performed using ex vivo skin permeation, fluorescence microscopy, and histopathology studies. Clinical utility via transdermal route was acknowledged using in vivo bioavailability study ...

Patel, Ketul K.; Kumar, Praveen; Thakkar, Hetal P.

2012-01-01

389

One step antiglare sol-gel coating for screens by sol-gel techniques  

OpenAIRE

Anti-reflection coatings on glass substrates were prepared by the application of sol-gel coatings of silica containing crystalline tin oxide particles. The sol was coated on commercially available float glass by dip-coating and spin-coating techniques. Increasing the surface roughness of the float glass (factor of 50) by a particulate coating material resulted in anti-reflection effects comparable to frosted glass. Haze and clarity, which are a measure for the contrast and definition of an op...

Schelle, Christian; Mennig, Martin; Krug, Herbert; Jonschker, Gerhard; Schmidt, Helmut K.

1997-01-01

390

Environmentally safe removal/disposal of Coomassie Brilliant Blue from gel destain and used gel stain.  

Science.gov (United States)

Gel destaining following Coomassie Brilliant Blue (CBB) staining involves the use of toxic reagents. Here we demonstrate the efficacy of various paper adsorbents in adsorbing CBB. Kimwipes adsorbed the best, followed by Teri towels, multifold towels, and Whatman numbers 1 and 3 filter papers. Three Kimwipes completely adsorbed the dye released from a CBB-stained mini-gel. Nonradioactive destain solution can, therefore, be recycled for destaining CBB-stained gels. Stain removal with Kimwipes helps in reducing destain use and in reducing organic liquid waste, and it is 7.5-fold cheaper compared with an available method for CBB disposal. Following this, we determined the suitability of this procedure to remove the dye from a used CBB staining solution awaiting proper disposal by our Institutional Safety Office. The dye from a 0.05% CBB staining solution could be removed in 5 to 10 min using 75 Kimwipes. The CBB-adsorbed Kimwipes did not release the stain when squeezed dry even after incubation in various salts over 1week and in water for 5 weeks. The CBB removed allows its easy disposal as solid waste and will not leach out from solid landfills. Thus, stain removal with Kimwipes helps in disposing CBB in an environmentally friendly manner and allows recycling of destaining solution. PMID:20507825

Dorri, Yaser; Kurien, Biji T

2010-09-15

391

Ferric hydroxide gel, goethite and humic acid gel as solid phase absorbents for uranium and their thermoanalytical studies  

International Nuclear Information System (INIS)

Radioactive sand stone samples of sedimentary rocks constitute fine particles like clays, hydrous iron oxides (goethite) and humic acid. All these colloidal particles have the property of sorption, ion-exchange etc. under suitable conditions. Hence the ability of these fine particles for uranium sorption and retention has been investigated in detail individually on ferric hydroxide gel, goethite and humic acid gel and the thermoanalytical studies were also carried out. Freshly precipitated ferric hydroxide gel exhibited uranyl sorption upto 9%. Natural and synthetic goethite showed upto 2.8%, and humic acid upto 6% under optimum conditions of pH and uranyl concentration. Differential thermal analysis was carried out to characterise ferric hydroxide gel, natural and synthetic goethite and humic acid gel. (author)

392

Oil droplet release from emulsion-filled gels in relation to sensory perception  

OpenAIRE

Oil droplet release upon shearing was studied in emulsion-filled gels containing oil droplets either bound or unbound to the gel matrix. At 20 °C no release was observed for gels containing droplets bound to the matrix, whereas the release measured for gels with unbound droplets related to the fat content and the size of the gel particles obtained after shearing. For gels with bound droplets and melting at the oral processing temperature, increasing the temperature of the determination to 37...

Sala, G.; Velde, F.; Cohen Stuart, M. A.; Aken, G. A.

2007-01-01

393

Agarose gel electrophoresis for the separation of DNA fragments.  

Science.gov (United States)

Agarose gel electrophoresis is the most effective way of separating DNA fragments of varying sizes ranging from 100 bp to 25 kb(1). Agarose is isolated from the seaweed genera Gelidium and Gracilaria, and consists of repeated agarobiose (L- and D-galactose) subunits(2). During gelation, agarose polymers associate non-covalently and form a network of bundles whose pore sizes determine a gel's molecular sieving properties. The use of agarose gel electrophoresis revolutionized the separation of DNA. Prior to the adoption of agarose gels, DNA was primarily separated using sucrose density gradient centrifugation, which only provided an approximation of size. To separate DNA using agarose gel electrophoresis, the DNA is loaded into pre-cast wells in the gel and a current applied. The phosphate backbone of the DNA (and RNA) molecule is negatively charged, therefore when placed in an electric field, DNA fragments will migrate to the positively charged anode. Because DNA has a uniform mass/charge ratio, DNA molecules are separated by size within an agarose gel in a pattern such that the distance traveled is inversely proportional to the log of its molecular weight(3). The leading model for DNA movement through an agarose gel is "biased reptation", whereby the leading edge moves forward and pulls the rest of the molecule along(4). The rate of migration of a DNA molecule through a gel is determined by the following: 1) size of DNA molecule; 2) agarose concentration; 3) DNA conformation(5); 4) voltage applied, 5) presence of ethidium bromide, 6) type of agarose and 7) electrophoresis buffer. After separation, the DNA molecules can be visualized under uv light after staining with an appropriate dye. By following this protocol, students should be able to: Understand the mechanism by which DNA fragments are separated within a gel matrix Understand how conformation of the DNA molecule will determine its mobility through a gel matrix Identify an agarose solution of appropriate concentration for their needs Prepare an agarose gel for electrophoresis of DNA samples Set up the gel electrophoresis apparatus and power supply Select an appropriate voltage for the separation of DNA fragments Understand the mechanism by which ethidium bromide allows for the visualization of DNA bands Determine the sizes of separated DNA fragments. PMID:22546956

Lee, Pei Yun; Costumbrado, John; Hsu, Chih-Yuan; Kim, Yong Hoon

2012-01-01

394

Açúcar granulado ou em gel no tratamento de feridas em cães / Granulated sugar and sugar gel in treating canine wounds  

Scientific Electronic Library Online (English)

Full Text Available O açúcar é um dos produtos mais utilizados para tratamento de feridas em medicina veterinária. Sua principal vantagem é o efeito higroscópico nos tecidos e morte das bactérias por plasmólise, tornando-o um bactericida pelo efeito físico realizado, sem levar à resistência bacteriana. O objetivo deste [...] experimento foi comparar a evolução cicatricial de feridas cutâneas com o uso tópico de açúcar na forma granulada e na forma de gel. Foram tratadas 16 feridas de cães, das quais oito receberam tratamento com açúcar granulado (grupo A) e oito com gel de açúcar (grupo G). O tempo de tratamento, independente do grupo, levou, no mínimo, sete dias e, no máximo, 14. Quanto à aplicabilidade, o gel demonstrou melhor adesão nas feridas e preenchimento do produto no subcutâneo de forma mais efetiva que o açúcar granulado. Conclui-se que tanto o gel quanto o açúcar foram efetivos na cicatrização das feridas dos animais deste experimento, sendo que o gel demonstrou precocidade na retração cicatricial nos primeiros sete dias. Abstract in english Sugar is one of the most widely used products in the treatment of wounds in veterinary medicine. Its main advantage is the hygroscopic effect on tissues and the bacterial death by plasmolysis, making it a bactericidal agent due to the physical effect observed, without leading to bacterial resistance [...] . The aim of this experiment was to compare cicatricial evolution of cutaneous wounds with the topical use of sugar either granulated or as gel. Sixteen canine wounds were treated: eight with granulated sugar (group A) and eight with sugar gel (group G). Treatment time, independent of the group, took at least seven days and a maximum of 14. Concerning applicability, gel sugar showed better adhesion to wounds and subcutaneous filling more effectively that granulated sugar. It is concluded that both granulated and gel sugar were effective in healing skin wounds, the gel being precocious in cicatricial retraction within the first seven days of treatment.

Gabriele Maria Callegaro, Serafini; João Eduardo Wallau, Schossler; Anne Santos do, Amaral; Luciana Hermes, Dutra; Angela Piantá, Dibi; Priscila, Drogemoller; Cristiane de Lima, Athayde.

2213-22-01

395

Açúcar granulado ou em gel no tratamento de feridas em cães Granulated sugar and sugar gel in treating canine wounds  

Directory of Open Access Journals (Sweden)

Full Text Available O açúcar é um dos produtos mais utilizados para tratamento de feridas em medicina veterinária. Sua principal vantagem é o efeito higroscópico nos tecidos e morte das bactérias por plasmólise, tornando-o um bactericida pelo efeito físico realizado, sem levar à resistência bacteriana. O objetivo deste experimento foi comparar a evolução cicatricial de feridas cutâneas com o uso tópico de açúcar na forma granulada e na forma de gel. Foram tratadas 16 feridas de cães, das quais oito receberam tratamento com açúcar granulado (grupo A e oito com gel de açúcar (grupo G. O tempo de tratamento, independente do grupo, levou, no mínimo, sete dias e, no máximo, 14. Quanto à aplicabilidade, o gel demonstrou melhor adesão nas feridas e preenchimento do produto no subcutâneo de forma mais efetiva que o açúcar granulado. Conclui-se que tanto o gel quanto o açúcar foram efetivos na cicatrização das feridas dos animais deste experimento, sendo que o gel demonstrou precocidade na retração cicatricial nos primeiros sete dias.Sugar is one of the most widely used products in the treatment of wounds in veterinary medicine. Its main advantage is the hygroscopic effect on tissues and the bacterial death by plasmolysis, making it a bactericidal agent due to the physical effect observed, without leading to bacterial resistance. The aim of this experiment was to compare cicatricial evolution of cutaneous wounds with the topical use of sugar either granulated or as gel. Sixteen canine wounds were treated: eight with granulated sugar (group A and eight with sugar gel (group G. Treatment time, independent of the group, took at least seven days and a maximum of 14. Concerning applicability, gel sugar showed better adhesion to wounds and subcutaneous filling more effectively that granulated sugar. It is concluded that both granulated and gel sugar were effective in healing skin wounds, the gel being precocious in cicatricial retraction within the first seven days of treatment.

Gabriele Maria Callegaro Serafini

2012-12-01

396

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

397

COMPARATIVE EFFICACY OF PESTE DES PETITS RUMINANTS (PPR VACCINES AVAILABLE IN PAKISTAN IN SHEEP AND GOATS  

Directory of Open Access Journals (Sweden)

Full Text Available The efficiency of Peste des petits ruminants virus (PPRV vaccines available in Pakistan was evaluated on the basis of the humoral immune response measured by haemagglutination inhibition (HI and agar gel immunodiffusion (AGID tests in sheep (n=60 and goats (n=60. The effect of storage temperature on HA activity of vaccine virus was measured by holding the vaccine at -20, 4, 27 and 40°C for 24 hours. The titer of freshly prepared vaccine was 1:16 and remained unchanged for 24 hours in the vaccines stored at -20 and 4°C. However, drop in titer (1:2 HA was recorded in the vaccine kept at 40°C for 24 hours. The haemagglutination activity of PPR virus constituted in buffer with pH 6.8 and 7.0 was recorded as highest when assay was performed with chicken and human blood group’O’ erythrocytes (1%. The lowest titer was recorded when vaccine was reconstituted in buffer at pH 8.0. After 14th day post vaccination, there was a gradual increase in the antibody titer till 56th day. Geometric mean titer (GMT of antibodies against locally manufactured PPRV vaccine was higher (207.9 in comparison with Pestivec (73.3, a vaccine imported from Jordan at 63rd day post vaccination in sheep; the corresponding values in goats were 147.0 and 48.5, respectively. All animals of control group were negative for antibodies by both of the diagnostic tests.

M. INTIZAR, M. D. AHMAD, A. A. ANJUM AND A. HANIF

2009-10-01

398

Dynamical arrest: interplay of glass and gel transitions.  

Science.gov (United States)

The structural arrest of a polymeric suspension might be driven by an increase of the cross-linker concentration, which drives the gel transition, as well as by an increase of the polymer density, which induces a glass transition. These dynamical continuous (gel) and discontinuous (glass) transitions might interfere, since the glass transition might occur within the gel phase, and the gel transition might be induced in a polymer suspension with glassy features. Here we study the interplay of these transitions by investigating via event-driven molecular dynamics simulation the relaxation dynamics of a polymeric suspension as a function of the cross-linker concentration and the monomer volume fraction. We show that the slow dynamics within the gel phase is characterized by a long sub-diffusive regime, which is due both to the crowding as well as to the presence of a percolating cluster. In this regime, the transition of structural arrest is found to occur either along the gel or along the glass line, depending on the length scale at which the dynamics is probed. Where the two lines meet there is no apparent sign of higher order dynamical singularity. Logarithmic behavior typical of A3 singularity appears inside the gel phase along the glass transition line. These findings seem to be related to the results of the mode coupling theory for the F13 schematic model. PMID:24828914

Khalil, Nagi; de Candia, Antonio; Fierro, Annalisa; Ciamarra, Massimo Pica; Coniglio, Antonio

2014-07-21

399

Development of an injectable chitosan/marine collagen composite gel  

International Nuclear Information System (INIS)

A chitosan/marine-originated collagen composite has been developed. This composite gel was characterized and its biocompatibility, as well as an inflammatory reaction, was observed. The chitosan gel including N-3-carboxypropanoil-6-O-(carboxymethyl) chitosan of 3 mol%, 6-O-(carboxymethyl) chitosan of 62 mol% and 6-O-(carboxymethyl) chitin of 35 mol% was prepared and compounded with the salmon atelocollagen (SA) gel at different mixture ratios. The composite gels were injected subcutaneously in to the back of rats. The specimens were harvested for a histological survey as well as a tumor necrosis factor-alpha (TNF-?) assay by ELISA. The inflammatory cell infiltration and release of TNF-? were successively controlled low with the ratio of SA to chitosan at 10:90 or 20:80. The SA gel first, within 2 weeks, and then chitosan in the composite gel were slowly absorbed after implantation, followed by soft tissue formation. It is expected that this composite gel will be available as a carrier for tissue filler and drug delivery systems.

400

Weak alignment of membrane proteins in stressed polyacrylamide gels  

Science.gov (United States)

Residual dipolar couplings are important as angular constraints for the structure determination of membrane proteins in micelles. Strained polyacrylamide gels are one of the few available mechanisms available for inducing the requisite weak alignment for these samples. However, their use is frequently limited by the ability to incorporate proteins and buffer solutions into the gel matrix. The implementation of several methods of incorporating membrane proteins into gels are described. Conditions for copolymerizing the protein in the absence of a change in pH are detailed. Electrophoresis is also shown to be a useful method to incorporate proteins. Weak alignment of the protein-micelle complex in the gel matrix is subsequently achieved using either vertical or radial compression. The magnitude of alignment can be controlled by altering the gel concentration, the acrylamide/bisacrylamide ratio, and the compression ratio. The alignment tensor can be altered relative to uncharged polyacrylamide gels by copolymerizing samples with acrylamide/acrylic acid to incorporate negative charges in the strained polyacrylamide gel to provide an alternate orientation

Jones, David H.; Opella, Stanley J.

2004-12-01

401

Collagen gel anisotropy measured by 2-D laser trap microrheometry.  

Science.gov (United States)

Collagen gels can serve as biomaterials ideal for tissue equivalents, especially if they are remodeled to have fibril anisotropy mimicking native tissue. Type I collagen gel remodeling was studied microscopically to investigate the changes caused by fibroblasts in collagen gel structures, with and without the growth factors PDGF-BB and TGF-beta1. A bidirectional laser trap microrheometry technique was developed that revealed a high degree of local heterogeneity and anisotropy in the structure of the collagen gels during active fibroblast contraction. The use of the growth factors increased not only the gel anisotropy, but the heterogeneity as well, indicating further changes in the collagen fibril orientations. This work shows the ability to influence the remodeling capabilities of fibroblasts by using growth factors in order to begin to elucidate the changes in the local mechanical environment of contracting collagen gels. We present this experimental technique as a method for probing changes in the fibroblast-driven anisotropy of collagen gels as a basis for understanding microstructural tissue organization important in the development of collagen-based tissue equivalents. PMID:17380393

Parekh, Aron; Velegol, Darrell

2007-07-01

402

Chemotaxis of active, self-oscillating polymer gels in solution  

Science.gov (United States)

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

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

2012-02-01

403

Gel adsorption processing for waste solidification in NZP ceramics  

International Nuclear Information System (INIS)

Simulated PW-4b waste solution along with Na additive was mixed with Zr-P-O gel, dried and then fired to form the desired sodium zirconium phosphate, NaZr2 (PO4)3 [NZP] ceramic. NZP and monazite were the only phases produced upon firing at 9000C with 10 to 40% of PW-4b mixed with the gel. CsZr2 (PO4)3 which is isostructural with NZP was also identified when fired under reducing conditions. The -200 mesh powders of these waste forms prepared under reducing conditions showed excellent leach resistance under hydro-thermal conditions. Alternatively, PW-4b and Three Mile Island (TMI) wastes were adsorbed on Zr-P-O gel in a column. The gel was dried, pelletized and fired to form the desired [NZP] ceramic. Cesium was found to be selective on the Zr-P-O gel because no breakthrough of Cs was detected up to 38 column volumes of TMI waste. Thus, it is possible to use a tailored gel to sorb Cs and/or Sr from accident waste water and then fire the bed to form the [NZP] ceramic below 10000C. The main advantages of the gel adsorption process are its simplicity and its enormous compositional flexibility. 12 references, 2 figures, 4 tables

404

Soft magnetorheological polymer gels with controllable rheological properties  

International Nuclear Information System (INIS)

A series of magnetorheological (MR) gels consisting of plastic polyurethane matrix swollen by nonvolatile solvent in different weight fractions and carbonyl iron particles were prepared. Their magnetorheological properties, both under oscillatory and rotational shear rheometry, were systematically tested. The results demonstrate that except for the significant influence on the magnetorheological performance, the state of these MR gels can also be easily switched from solid-like (the solvent content is less than 10 wt%) to liquid-like (the solvent content exceeds 25 wt%) by adjusting the solvent content. The huge differences in magnetorheological properties of different MR gels (for example, the G? of MR gels without solvent is three orders of magnitude larger than that of MR gels with 45 wt% of solvent in the absence of a magnetic field) and movements of iron particles in the presence of a magnetic field were analyzed, which are helpful in thoroughly understanding the mechanical–magnetic coupling mechanism between the magnetic particles and the polymer matrix and promoting the application of MR polymer gels. In addition, the stability of MR gels was also investigated. A gravity yield parameter was introduced to quantitatively describe the relationship between particle sedimentation and material characteristics. When the solvent content is lower than 25 wt% or the gravity yield parameter is larger than 0.865, the particle settling phenomenon can be effectively avoiing phenomenon can be effectively avoided. (paper)

405

Western Blot of Stained Proteins from Dried Polyacrylamide Gels  

Science.gov (United States)

Western blotting of proteins is customarily performed following their separation on polyacrylamide gels, either prior to staining (1) or, as recently reported, following staining (2). We describe here Western blotting with stained gels, which had been dried and some of which had been stored for years. This procedure permits immunological analysis of proteins, to which antisera may have become available only later, or where the application of newly developed sensitive detection methods is desired. Once rehydration of the gels is achieved, proteins can be-transferred to blotting membranes by any appropriate protocol. Proteins stained with Coomassie Blue have to be detected with a non-chromogenic method, such as the film-based enhanced chemiluminescence (ECL)2) procedure (3). Silver stained proteins, which transfer in the colorless form, may be visualized by any detection method, although, because of the usually very low amounts of proteins, detection by ECL is preferable. Blotting of stained proteins from rehydrated gels is as rapid and as quantitative as from freshly prepared gels, in contrast to blotting from wet stained gels, which requires extensive washing and results in low transfer efficiency (2). Together with a photographic record of the gel pattern, unambiguous identification of immunoreactive proteins from complex mixtures is possible. Some further applications of this work are discussed.

Gruber, Claudia; Stan-Lotter, Helga

1996-01-01

406

Size effects on diffusion processes within agarose gels.  

Science.gov (United States)

To investigate diffusion processes in agarose gel, nanoparticles with sizes in the range between 1 and 140 nm have been tested by means of fluorescence correlation spectroscopy. Understanding the diffusion properties in agarose gels is interesting, because such gels are good models for microbial biofilms and cells cytoplasm. The fluorescence correlation spectroscopy technique is very useful for such investigations due to its high sensitivity and selectivity, its excellent spatial resolution compared to the pore size of the gel, and its ability to probe a wide range of sizes of diffusing nanoparticles. The largest hydrodynamic radius (R(c)) of trapped particles that displayed local mobility was estimated to be 70 nm for a 1.5% agarose gel. The results showed that diffusion of particles in agarose gel is anomalous, with a diverging fractal dimension of diffusion when the large particles become entrapped in the pores of the gel. The latter situation occurs when the reduced size (R(A)/R(c)) of the diffusing particle, A, is >0.4. Variations of the fractal exponent of diffusion (d(w)) with the reduced particle size were in agreement with three-dimensional Monte Carlo simulations in porous media. Nonetheless, a systematic offset of d(w) was observed in real systems and was attributed to weak nonelastic interactions between the diffusing particles and polymer fibers, which was not considered in the Monte Carlo simulations. PMID:15111390

Fatin-Rouge, Nicolas; Starchev, Konstantin; Buffle, Jacques

2004-05-01

407

[Insecticidal gels--a promising form for using pyrethroids].  

Science.gov (United States)

Insecticidal gels containing the following agents as active ingredients: permethrin (0.4%), cipermethrin (0.1%), fenvalerate (0.5%), alpha-methrin (0.2%) were designed and studied under laboratory and field conditions. When applied to various surface types, the designed formulations of the gels caused 100% death of cockroaches, domestic flies, bed-bugs and fleas. The application rate is 2.5-10.0 g/m2 depending on the species of insects. The residual insecticidal action of gels on the surfaces is as long as 3 months. The designed formulations are approved by the Ministry of Health of Russia for their manufacture and application. PMID:7770016

Terekhova, Z A

1995-01-01

408

COMPARATIVE STUDIES ON POVIDONE-IODINE OINTMENT AND GEL  

Directory of Open Access Journals (Sweden)

Full Text Available Povidone-Iodine Ointment was prepared using polyethylene glycol base by fusion method and the gel was prepared using Poloxamer 407 as a gelling agent by cold process. The different characteristics of povidone-iodine ointment and gel were compared from the results obtained for assay and total, available and complex iodine contents. These values were comparable with marketed formulations. The formulations were tested for wound healing and antimicrobial activity. Wound healing studies show that the time taken for complete wound healing was slightly less for prepared povidone-iodine ointment and gel than the marketed preparations. Antimicrobial activity also found to be almost equal for the different formulations.

T. Mangilal*, K. S. K. Rao Patnaik , R. Sivakumar , Y. Sudhakar and S. K. Basu

2012-11-01

409

Cross-linked hydrophilic gels from ABA block copolymeric surfactants  

International Nuclear Information System (INIS)

Gelation of aqueous solutions of poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) block co-polymeric non-ionic surfactants (Pluronics or poloxamers) by the action of ?-rays is reported. Poloxamers with ethylene oxide content below 70% do not gel under the conditions studied, but appear to undergo chain scission, as there is a decrease in cloud point and an increase in hydrodynamic radius which is most likely to be due to decreased association of the more hydrophobic polymer. The gels obtained from poloxamers with ethylene oxide content over 70% have a high water uptake capacity. The possibility of using these gels as sustained release drug delivery systems is discussed. (Auth.)

410

Effect of Electron beam on Prepared HAP-Gel Composition  

Directory of Open Access Journals (Sweden)

Full Text Available Background: Polyvinyl alcohol liquid PVAl was used as the organic carrier for Hydroxylapatite-gel (Hap-gel composite. PVAl has the ability to form a nano- hydroxylapatite polyvinyl alcohol composite gel which has a wide range of uses in different environmental and medical applications. Prepared Hap-gel is known to have a very similar composition to human bone and is used as a substitute for bones in compound fractures and artificial dentures. Matreia and Methods: In this work prepared HAP- gel was exposed to a high ionizing radiation electron beam (5 kilo Gray and an aqueous solution containing aluminum ions (Al+. Some investigations were done to illustrate the effect of radiation exposure and aluminum contamination on prepared Hap-gel. Results: Energy dispersive X-ray analysis (EDx showed that the electron beam used caused an obvious increase in the calcium ions (Ca++ content of the prepared Hap-gel from 60% to 65.69 % with a prominent decrease in phosphorus ions (P + content from 40 % to 34.31 % in addition to an increase in the Ca/P ratio from 1.5 to 1.91. Exposure of the pre-irradiated Hap-gel samples to aluminium ions (Al+ resulted in a noticeable decrease in Ca++ content from 65.69 atomic % to 32.14 % atomic % and a further noticeable decrease in P+ content from 34.31 % atomic % to 13 atomic % as well as an increase in the Ca/P ratio from 1.91 to 2.47. The levels for the original prepared Hap-gel were Ca++; 60 atomic % and P+; 40 atomic %. It was deduced that exposure of the Hap-gel to Al+ had a further damaging effect on the pre-irradiated Hap-gel composition in addition to the damaging effect that the electron beam used induced on the samples. Conclusions: it could be concluded that electron beams and Al+ have an injurious effect on human bone tissue taking into consideration the similarity in composition between Hap-gel and bones. Therefore, this study could be beneficial in the field of osteoporosis research and assist the understanding of the effects of radiation such as that of electron beams and some pollutants such as aluminium present in running water on the health of human bone tissue.

Naima A. El Gendy*,Tawfik M. S.**, and Asma M. Nour

2014-04-01

411

Actin purification from a gel of rat brain extracts.  

Science.gov (United States)

Actin, 99% pure, has been recovered from rat brain with a high yield (greater than 15 mg/100 g brain). We have shown that: 1. a low ionic strength extract from rat brain tissue is capable of giving rise to a gel; 2. actin is the main gel component and its proportion is one order of magnitude higher than in the original extract; 3. actin can be isolated from this extract by a three-step procedure involving gelation, dissociation of the gel in 0.6 M KCl, followed by one or two depolymerization-polymerization cycles. PMID:6529588

Levilliers, N; Peron-Renner, M; Coffe, G; Pudles, J

1984-01-01

412

Application and production of sol-gel process  

International Nuclear Information System (INIS)

This book consists of eight chapters, which are deals with new chemistry of sol-gel process, creation of functional materials such as optical glass for laser, grin lens, nuclear fuel and ceramic, new complex materials by structure control such as intercalation and ORMOCERs, functional design, application and advance of analysis technology application of special technology on sol-gel process like supercritical dry and electrophoresis assay, development situation in Japan and development on sol-gel process about the accumulation of technology for present, and future.

413

FREEZE DRYING OF SILICA GELS PREPARED FROM SILICIUMETHOXID  

OpenAIRE

The freeze dried gels were prepared by acid catalysed hydrolysis of Si(OEt)4 diluted by ButOH. The acids used include H3PO4 and oxalic acid. Oxalic acid has DCCA-properties. Freeze drying without prior solvent exchange results in disintegration of the gels into mm size flakes. The fracturing of the gels becomes less severe as the concentration of EtOH in the liquid phase is reduced by solvent exchange. Pure ButOH shows only a very small volume change upon crystallization, but air saturated Bu...

Degn Egeberg, E.; Engell, J.

1989-01-01

414

Molecular host sol-gel films for chemical sensing applications  

Energy Technology Data Exchange (ETDEWEB)

Sol-gel cyclodextrin coatings on surface acoustic wave (SAW) device as VOC sensors have been studied. The sol-gel approach to thin films efficiently yields uniform coatings on SAW devices. The films were characterized by ATR-FT-IR, ellipsometry and SEM. The incorporation of molecular host reagents (cyclodextins and their derivatives) into thin films greatly enhance the sensitivity and selectivity of SAW sensors. It is believed that molecular recognition (selective sorption) occurs at the gas-solid interface. From the SAW data, it is possible to calculate the binding constants of sol-gel films towards a variety VOCs. The identification of VOCs based on SAW sensor arrays is discussed.

Shi, J.; Johnson, S.; Yang, X.; Swanson, B. [Los Alamos National Lab., NM (United States)

1997-12-31

415

Heat Induced Gels from Coconut Press Cake Proteins  

OpenAIRE

Freeze-dried coconut press cake powder (CPP), 43% w/w protein, was used to investigate the heat-induced gelation by heating in rheometer to 75? in a wide range of pH values, from 4 to 9. Low strain oscillatory method applied the measure visco-elastic propertieson 15% w/w CPP. The gel strength was also assessed by a texture analyzer. SDS-PAGE electrophoresis was conducted to identify the proteins evolved in the gel network structure and the gel micro-structure was a...

Borges Chambal; Björn Bergenståh; Petr Dejmek

2014-01-01

416

Sol-gel processing with inorganic metal salt precursors  

Science.gov (United States)

Methods for sol-gel processing that generally involve mixing together an inorganic metal salt, water, and a water miscible alcohol or other organic solvent, at room temperature with a macromolecular dispersant material, such as hydroxypropyl cellulose (HPC) added. The resulting homogenous solution is incubated at a desired temperature and time to result in a desired product. The methods enable production of high quality sols and gels at lower temperatures than standard methods. The methods enable production of nanosize sols from inorganic metal salts. The methods offer sol-gel processing from inorganic metal salts.

Hu, Zhong-Cheng

2004-10-19

417

Cholesteric liquid crystal gels with a graded mechanical stress  

Science.gov (United States)

In cholesteric liquid-crystalline gels, the mechanical role of the polymer network over the structure of the whole gel has been ignored. We show that it is the stress gradient exerted by the network over the helical structure that drives the broadening of the optical band gap, as evidenced by the absence of a gradient in chiral species. Model calculations and finite-difference time-domain simulations show that the network acts as a spring with a stiffness gradient. The present results indicate a revision to the common understanding of the physical properties of liquid-crystalline gels is necessary when a concentration gradient in a polymer network is present.

Agez, Gonzague; Relaix, Sabrina; Mitov, Michel

2014-02-01

418

Sol-gel technology applied to glass and crystalline ceramics  

International Nuclear Information System (INIS)

Fixation of high level and transuranium radioactive waste in glass or alternative ceramic forms requires remotely operable processes and equipment, and sol-gel technology developed for reactor fuel refabrication appears to be applicable. Advantages of the sol-gel process are absence of dust, easy pneumatic transfer and sampling of either liquids or free-flowing solid microspheres, excellent sinterability, and equipment amenable to remote operation because of mechanical simplicity. Synthetic rock microspheres and pellets containing up to 25% simulated defense waste have been prepared by the sol-gel process. 26 refs

419

Structural transformations in natural gels according to resonance methods data  

International Nuclear Information System (INIS)

The natural gels of alumo-ferri-sulphate-phosphate composition were studied by means of the Moessbauer spectroscopy, EPR and NMR'H. The investigation of the temperature dependences of the obtained spectra allowed one to establish two intervals in which the structural transformations of gels take place: 213...233 K and 383...423 K. The structural changes depend on the iron content. With the increase of iron content, its role increases, too. In gels containing iron more than 30%, the ferrigels are formed, which transform to hematite after annealing of samples at 1270 K. 10 refs., 7 figs., 2 tabs

420

Electron beam sterilization of the agarose gel used for electrophoresis  

International Nuclear Information System (INIS)

The results obtained by electron beam (EB) sterilization of the plates with agarose gel used for human serum protein electrophoresis are presented. Also, the results obtained by human serum protein electrophoresis performed with agarose gel plates irradiated at different EB doses, from 4 kGy to 20 kGy, are presented. The microbiological results demonstrate that above 5 kGy the irradiated agarose plates are sterile. The EB irradiation of the agarose gel plates in the dose range of 7-9 kGy gives the best results for both, sterilization and protein fraction separation processes. (author)

421

Orientation of the agarose gel matrix in pulsed electric fields.  

OpenAIRE

The technique of transient electric birefringence was used to investigate the effect of pulsed electric fields on the orientation of the agarose gel matrix. Orientation of the gel was observed at all electric field strengths. Very slow, time-dependent effects were observed when pulses of 10-100 V/cm were applied to 1% gels for 0.5-2 seconds, indicating that domains of the matrix were being oriented by the electric field. The sign of the birefringence reversed when the direction of the applied...

Stellwagen, J.; Stellwagen, N. C.

1989-01-01

422

Gel Electrophoresis of Gold-DNA Nano-Conjugates  

Energy Technology Data Exchange (ETDEWEB)

Single stranded DNA of different lengths and different amounts was attached to colloidal phosphine stabilized Au nanoparticles. The resulting conjugates were investigated in detail by a gel electrophoresis study based on 1200 gels. We demonstrate how these experiments help to understand the binding of DNA to Au particles. In particular we compare specific attachment of DNA via gold-thiol bonds with nonspecific adsorption of DNA. The maximum number of DNA molecules that can be bound per particle was determined. We also compare several methods to used gel electrophoresis for investigating the effective diameter of DNA-Au conjugates, such as using a calibration curve of particles with known diameters and Ferguson plots.

Pellegrino, T.; Sperling, R.A.; Alivisatos, A.P.; Parak, W.J.

2006-01-10

423

Kinetic study on crystal growth in gels by radioisotopic labelling  

International Nuclear Information System (INIS)

A kinetic study of crystal growth in gelatin and agar gels, using a technique based on radioactive tracers is given. 204TlCl, 204TlBr, 204TlI, 60CoC2O4 and 60CoH4C4O6 crystals in gels have been obtained. The global kinetic process of appearance of crystals has been found to be made up of two distinct stages: diffusion of the ions in the gel and crystallization, having different rate constants. (author) 10 refs.; 1 fig.; 1 tab

424

Relaxation of entangled polymers at the classical gel point  

OpenAIRE

We examine the relaxation behaviour of an entangled cross-linked polymer gel as it approaches the gel point in mean field (Flory-Stockmayer) percolation. The calculation is based on a tube model for the topological interactions in which stress is lost via hierarchical fluctuation of the primitive paths between cross-links. The decay time of a segment is calculated via a recursion relation which has an analytic solution near the gel point. The startling conclusion is that all clusters relax in...

Rubinstein, M.; Zurek, S.; Mcleish, T. C. B.; Ball, R. C.

1990-01-01

425

Clotrimazole nanoparticle gel for mucosal administration.  

Science.gov (United States)

In this study a formulation suitable to be applied on oral and/or vaginal mucosa has been developed for the treatment of fungal infections. The aim of the research is a comparison between clotrimazole (CLO) containing semisolid formulations based on monoolein aqueous dispersion (MAD) or nanostructured lipid carrier (NLC). MAD and NLC have been characterized in terms of morphology and dimensional distribution by cryogenic Transmission Electron Microscopy (cryo-TEM) and Photon Correlation Spectroscopy (PCS). CLO was encapsulated with high entrapment efficiency both in MAD and in NLC, according to Sedimentation Field Flow Fractionation (SdFFF) combined with HPLC. CLO recovery in MAD and NLC has been investigated by time. In order to obtain formulations with suitable viscosity for mucosal application, MAD was diluted with a carbomer gel, while NLC was directly viscosized by the addition of poloxamer 407 in the dispersion. The rheological properties of MAD and NLC after viscosizing have been investigated. Franz cell has been employed to study CLO diffusion from the different vehicles, evidencing diffusion rates from MAD and NLC superimposable to that obtained using Canesten(®). An anticandidal activity study demonstrated that both CLO-MAD and CLO-NLC were more active against Candida albicans with respect to the pure drug. PMID:25428089

Esposito, Elisabetta; Ravani, Laura; Contado, Catia; Costenaro, Andrea; Drechsler, Markus; Rossi, Damiano; Menegatti, Enea; Grandini, Alessandro; Cortesi, Rita

2013-01-01

426

Gel formation in negative electron resists  

International Nuclear Information System (INIS)

Exposure characteristics of negative electron resists are described on the basis of Charlesby's theory on gel formation by a chain reaction. By use of the theory, the important resist parameters, contrast and sensitivity, can be related to the chemical properties of the resist materials. Applicability of the theory to exposure curves of Kodak thin film resist (KTFR), polymethylvinylsiloxane (PMVS), and epoxidized polybutadiene (EPB) is experimentally verified. The radiation yield for the reaction initiated directly by the electron irradiation and that for the over-all reaction propagated via radicals is separately estimated. It is found that the sensitivity of styrene-butadiene copolymers (SB) is increased by an introduction of ?-phenylmaleimide. This increase in sensitivity is also explained by the theory. The observed lowering in contrast associating the improvement in sensitivity by ?-phenylmaleimidation in SB, by epoxidation in polybutadiene, and by introduction of vinyl groups in polysiloxanes is in good agreement with the theoretical results. It is concluded that if a resist with higher contrast than 1.0 is required, the chain reaction must be inhibited so that the inhibition factor is larger than about 0.5