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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  

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

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

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

2014-06-01

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Enzyme-linked immunosorbent assay for the diagnosis of bovine leukosis: comparison with the agar gel immunodiffusion test approved by the Canadian Food Inspection Agency.  

OpenAIRE

Four commercially available bovine leukemia virus (BLV)-ELISA kits from Europe or the United States were compared to the agar gel immunodiffusion (AGID) test officially approved by the Canadian Food Inspection Agency (CFIA). A total of 1200 cattle serum samples were used. Three ELISA kits based on the envelope glycoprotein (gp51) gave an excellent correlation with the AGID test. The kappa values were 0.998, 0.984, and 0.986 for the ELISA kits #1, #2, and #3, respectively. The ELISA kit based ...

Simard, C.; Richardson, S.; Dixon, P.; Be?langer, C.; Maxwell, P.

2000-01-01

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Enzyme-linked immunosorbent assay for the diagnosis of bovine leukosis: comparison with the agar gel immunodiffusion test approved by the Canadian Food Inspection Agency.  

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Four commercially available bovine leukemia virus (BLV)-ELISA kits from Europe or the United States were compared to the agar gel immunodiffusion (AGID) test officially approved by the Canadian Food Inspection Agency (CFIA). A total of 1200 cattle serum samples were used. Three ELISA kits based on the envelope glycoprotein (gp51) gave an excellent correlation with the AGID test. The kappa values were 0.998, 0.984, and 0.986 for the ELISA kits #1, #2, and #3, respectively. The ELISA kit based on the p24 core protein was found to be less sensitive than the officially approved AGID test and detected 5.13% of false negatives. Forty BLV AGID strongly positive serum samples were diluted. Based on the dilution experiment, the gp51 ELISA kits were found to be more sensitive than the AGID test kits. They were capable of detecting antibodies in samples diluted up to 1/5000 (kit #1), 1/20 800 (kit #2) and 1/4000 (kit #3), whereas the AGID kit was only capable of detecting antibodies in samples diluted up to 1/100. Based on these observations, the gp51 BLV-ELISA was recognized as an official test method for the serodiagnosis of bovine leukosis in Canada. PMID:10805248

Simard, C; Richardson, S; Dixon, P; Bélanger, C; Maxwell, P

2000-04-01

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Recombinant envelope protein (rgp90) ELISA for equine infectious anemia virus provides comparable results to the agar gel immunodiffusion.  

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Equine infectious anemia (EIA) is an important viral infection affecting horses worldwide. The course of infection is accompanied generally by three characteristic stages: acute, chronic and inapparent. There is no effective EIA vaccine or treatment, and the control of the disease is based currently on identification of EIAV inapparent carriers by laboratory tests. Recombinant envelope protein (rgp90) was expressed in Escherichia coli and evaluated via enzyme-linked immunosorbent assay (ELISA). There was an excellent agreement (95.42%) between the ELISA results using rgp90 and agar gel immunodiffusion test results. AGID is considered the "gold-standard" serologic test for equine infectious anemia (EIA). After 1160 serum samples were tested, the relative sensitivity and specificity of the ELISA were 96.1% and 96.4%, respectively. Moreover, analysis diagnostic accuracy of the ELISA was performed. The ELISA proved robust. Furthermore, good reproducibility was observed for the negative controls and, positive controls for all plates tested. PMID:22227617

Reis, Jenner K P; Diniz, Rejane S; Haddad, João P A; Ferraz, Isabella B F; Carvalho, Alex F; Kroon, Erna G; Ferreira, Paulo C P; Leite, Rômulo C

2012-03-01

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Investigation on the status of Johne's disease based on agar gel immunodiffusion, ziehl-neelsen staining and nested PCR approach in two cattle farm  

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Full Text Available Background and Methods: Paratuberculosis is a chronic disease of ruminant, caused by Mycobacterium avium subsp. paratuberculosis (Map, clinically infected animals produce high level of antibodies in blood and shed detectable amount of Map organisms in feces. Several serological and molecular tests are utilized for detection of antibodies or DNA of the organism in clinical samples. Present study indicates the status of paratuberculosis in two distinct cattle farms with different organizational set-ups viz. organized and unorganized. We used agar gel immunodiffusion (AGID assay for the detection of antibodies in blood. Ziehl-Neelsen (ZN staining of fecal smears was done to observe acid-fast bacilli and Nested PCR targeted to IS900 and f57 sequences, was performed to confirm the pathogen.Results: Sera samples of cattle, from organized farm, did not show any visible precipitating band with AGID assay. However, fecal smears of few cattle (3.57% were positive for acid-fast bacilli. When confirmed with nested PCR, only one fecal sample (0.71% was found positive for Map. In case of unorganized farm, a large number of cattle (38.75% showed precipitating antibodies with AGID assay and the percentage of fecal smears that showed acid-fast bacilli was 26.62%. Nevertheless, fecal samples containing Map DNA was confirmed in 14.37% of fecal sample by nested PCR.Conclusions: An organized farm, with better hygiene and management practices, showed lesser occurrence of paratuberculosis in cattle in comparison to unorganized farm. Not all AGID assays positive cattle might be an efficient shedder of Map and mare detection of acid-fast bacilli in fecal smears did not always indicate the presence of Map organism. Cattle infected with JD were mostly in the age group of six years and above.

Anand Mohan,

2013-08-01

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

OpenAIRE

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

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

1983-01-01

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Comparative efficacy of standard AGID, CCIE and competitive ELISA for detecting bluetongue virus antibodies in indigenous breeds of sheep and goats in Rajasthan, India.  

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The sero-prevalence of antibodies against blue tongue virus (BTV) in 408 local breeds of sheep in Rajasthan state in India was investigated using standard agar gel immunodiffusion (AGID) test. Maximum seropositivities of 11.3% (13/115), 10.7% (13/121), 7.1% (11/155) and 5.9% (1/17) were recorded in the Chokla, Magra, Nali and Pugal breeds, respectively. Out of 107 goat serum samples, 6 (5.6%) were AGID positive. The performance of the standard AGID, counter current immuno-electrophoresis (CCIE) and the competitive enzyme-linked immunosorbent assay (cELISA) for the detection of serum antibody against BTV in indigenous breeds of sheep were compared. Out of 178 sheep serum samples tested, 17 (9.5%), 22 (12.3%) and 54 (30.3%) were positive for group-specific bluetongue antibodies by AGID, CCIE and cELISA, respectively. There was appreciable difference in the seroprevalence detected by AGID, CCIE and cELISA in clinically healthy and diseased sheep with regard to relative sensitivities and specificities of the tests with cELISA being highly sensitive and specific followed by CCIE and AGID test. It was concluded that these indigenous breeds of sheep may be a potential reservoir of BTV infection and cELISA should be routinely used for the detection of antibodies against BTV in these local breeds of sheep. PMID:15785128

Shringi, Smriti; Shringi, B N

2005-03-01

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Comparision of Polymerase Chain Reaction and Agar Gel Immunodiffusion test in Detection of MarekAND#8217;s Disease Virus  

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Full Text Available A study was undertaken to identify Marek’s disease virus (MDV antigen by PCR and AGID and to test the significance of PCR and AGID by McNemar’s test in detection of MDV antigen in outbreak in layer flocks. A total of twelve different MD outbreak flocks with varying flock size were selected in this study. Feather follicles were collected from 10 apparently healthy birds, 10 clinically affected birds and 10 dead birds separately in each outbreak. All the samples were subjected to PCR and AGID. In PCR, 42 (35.00%, 68 (56.67% and 106 (88.33% samples were positive to MDV in apparently healthy birds, clinically affected birds and dead birds respectively and in AGID 28 (23.33%, 56 (46.67% and 98 (81.67% samples were positive to MDV in apparently healthy birds, clinically affected birds and dead birds respectively. In testing the significance of PCR and AGID in detecting MDV, significant difference existed between the two tests in feather tips of apparently healthy birds (P < 0.05, whereas there was no significant difference between PCR and AGID in detection of MDV in feather tips of clinically affected and dead birds (P > 0.05. Hence, PCR can be used to screen MDV in apparently healthy birds and AGID can be used to screen MDV in clinically affected and dead birds keeping feasibility and economic consideration. [Vet. World 2010; 3(5.000: 212-214

A. Manicavasaka Dinakaran

2010-10-01

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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  

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Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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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Immunodiffusion method for detection of type A Clostridium botulinum.  

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

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

1981-01-01

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

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

R, Felmer; J, Zúñiga; M, Recabal.

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

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

R Felmer

2006-01-01

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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 [...

M.N., Xavier; F.M., Sant' Anna; T.M.A., Silva; E.A., Costa; V.S., Moustacas; F.A., Merlo; C.A., Carvalho Júnior; M.G., Dasso; L.A., Mathias; A.M.G., Gouveia; A.P., Lage; R.L., Santos.

1016-10-01

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Comparison of radial immunodiffusion and laser nephelometry for quantitating some serum proteins.  

Science.gov (United States)

After quantitating immunoglobulins G, A, and M and complement C3c and C4 in serum by using a laser nephelometer coupled with a data processor, I compared these results with values obtained by an early-readout radial immunodiffusion method. Day-to-day precision was better for nephelometry than for radial immunodiffusion for all proteins analyzed. The average coefficient of variation was 6.0% for nephelometry and 9.9% for radial immunodiffusion. Comparison of these methods gave ranked correlation coefficients of 0.945, 0.981, 0.932, 0.803, and 0.792 for IgG, IgA, IgM, C3c, and C4, respectively. Nephelometry gave significantly higher values than radial immunodiffusion for IgG, IgA, IgM, and C3c, and significantly lower values for C4 (p less than 0.001). Part of this bias was found to be due to the equation programmed in the data processor for calculating the standard curves. Within 95% limits, nephelometry gave higher normal ranges than radial immunodiffusion for IgG, IgA, and IgM. Other possible factors that can produce this bias are discussed. PMID:6766362

Alexander, R L

1980-02-01

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

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

Madelayne Cortez-Moreira

2005-03-01

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

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Full Text Available SciELO Brazil | Language: English Abstract in portuguese Soros de 562 caprinos foram submetidos à pesquisa de Artrite-encefalite caprina através dos testes de imunodifusão em gel de agarose (AGID) de teste imunoenzimático (ELISA). Das amostras testadas, 79 (14,1%) foram reativas em ambos os testes, mas 141 (25,1%) foram positivos apenas no ELISA. Assim, a [...] sensibilidade do ELISA em relação ao AGID foi de 100% e a especificidade de 70,8%. Abstract in english 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, pre [...] sented 100% sensitivity and 70.8% specificity.

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

2005-03-01

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Immunodiffusion assay of C1 inhibitor function in serum: prospective analysis in angioedema-urticaria.  

Science.gov (United States)

An immunodiffusion assay for detecting C1 inhibitor function in human serum was described recently by Ziccardi and Cooper. In our present study, the applicability of this assay for C1 inhibitor deficiency or C1 inhibitor dysfunction was evaluated. Of the 39 patients evaluated, all eight patients with the common (C1 inhibitor deficiency) form of hereditary angioedema and all three patients with the variant (dysfunctional C1 inhibitor) form of hereditary angioedema were identified correctly. Treatment of patients with hereditary angioedema with stanozolol or danocrine increased their serum C1 inhibitor concentrations and normalized the immunodiffusion assay for C1 inhibitor function. In addition, the assay allowed the correct identification of three patients with the acquired form of C1 inhibitor deficiency, because the sera of these patients exhibited a distinctive pattern. The 25 samples from patients (chronic angioedema, chronic urticaria, or hypocomplementemic vasculitis) without C1 inhibitor deficiency had normal assays. PMID:6410904

Yelvington, M; Prograis, L J; Pizzo, C J; Curd, J G

1983-09-01

22

Comparison of immunodiffusion and enzyme linked immunosorbent assay for antibodies to four Aspergillus species.  

OpenAIRE

Antigenic extracts were prepared from Aspergillus fumigatus, A niger, A flavus and A terreus for use in enzyme linked immunosorbent assay (ELISA) and immunodiffusion (ID) tests for Aspergillus antibodies to determine whether the use of antigenic extracts from species other than A fumigatus increased the sensitivity of the ELISA. ELISA titres correlated well with positive ID tests. Patient titres by ELISA were significantly higher than control titres for all species. Patient titres to A niger ...

Froudist, J. H.; Harnett, G. B.; Mcaleer, R.

1989-01-01

23

Does the degree of polymerization of haptoglobin influence the results of the radial immunodiffusion assay?  

OpenAIRE

The degree of polymerization of haptoglobin (Hp) phenotypes 2-1 and 2-2 was studied. In individual samples the degree of polymerization tends to be positively correlated with the Hp concentration as determined by the radial immunodiffusion technique (RID), while an inverse relationship between the size of Hp polymers and the Hp concentration in RID was expected. After reductive cleavage of Hp, the apparent Hp concentration became higher in individual samples with different degrees of poly...

Rijn, H. J. M.; Wisman, J. P. W.; Meyling, F. G.

1987-01-01

24

Determination of immunoglobulin A in saliva by immunobead enzyme-linked immunosorbent assay: comparison with single radial immunodiffusion.  

OpenAIRE

For the quantitative measurement of immunoglobulin A in human saliva, an immunobead enzyme-linked immunosorbent assay was investigated in detail. The method proved to be fast and sensitive, and it gave reproducible results. There was a strong correlation with results obtained by a single radial immunodiffusion method. The immunobead method gave 1.8 times higher values than the single radial immunodiffusion method with a lower correction factor for low-immunoglobulin A saliva and a higher fact...

Bratthall, D.; Ellen, R. P.

1982-01-01

25

Comparison of enzyme immunoassay and immunodiffusion for the detection of canine blastomycosis.  

Science.gov (United States)

Two Blastomyces dermatitidis commercial immunodiffusion antigens, Meridian Diagnostics and Nolan-Scott Laboratories, and two B. dermatitidis yeast phase lysate antigens, T-58 and K-Le, prepared in our laboratory were utilized in an enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies in 61 serum specimens from dogs with blastomycosis. All antigens used in the ELISA were diluted to 50 ng of protein ml-1. Immunodiffusion (ID) tests were also performed on the sera using a Nolan-Scott ID antigen. Greater reactivity, based on the ELISA index value, was evidenced with the two yeast phase lysate antigens over the two commercial reagents in the ELISA. In addition the sensitivity of the ELISA with the T-58, K-Le and Meridian antigens was considerably greater than that of the ID test. The Nolan-Scott antigen, however, was able to detect more positive specimens when used in the ID procedure than in the ELISA. Therefore encouraging results were obtained with respect to the continued development and optimization of the ELISA using B. dermatitidis cell lysate antigens for the diagnosis of blastomycosis. PMID:2128645

Seawell, B W; Scalarone, G M

1990-01-01

26

Prevalence of maedi-visna infection in culled ewes in Alberta  

OpenAIRE

Maedi-visna (MV) is a relatively common chronic infection of sheep in North America resulting in economic loss to the sheep industry. The objectives of this study were to: 1) measure the prevalence of MV infection in culled ewes in Alberta, by histologic examination (lungs and udder) and serologic testing using an agar gel immunodiffusion (AGID) test, 2) examine any geographic differences in its prevalence in the province, 3) evaluate the level of agreement between histopathologic examination...

Fournier, Dominique; Campbell, John R.; Middleton, Dorothy M.

2006-01-01

27

Development of a Fluorescence Polarization-Based Diagnostic Assay for Equine Infectious Anemia Virus  

OpenAIRE

The control of equine infectious anemia virus (EIAV) infections of horses has been over the past 20 years based primarily on the identification and elimination of seropositive horses, predominantly by a standardized agar gel immunodiffusion (AGID) assay in centralized reference laboratories. This screening for EIAV-seropositive horses has been to date hindered by the lack of a rapid diagnostic format that can be easily employed in the field. We describe here the development of a rapid solutio...

Tencza, Sarah Burroughs; Islam, Kazi R.; Kalia, Vandana; Nasir, Mohammad S.; Jolley, Michael E.; Montelaro, Ronald C.

2000-01-01

28

Sero-Survey of Equine Infectious Anemia in the Sultanate of Oman during 2007-2009  

OpenAIRE

Equine infectious anemia (EIA) is a fatal and relapsing infectious disease of equines caused by the lentivirus of Retroviridae family which occurs world-wide. It tends to become an inapparent infection if death does not result from the acute clinical attack. The virus persists in infected animals for life and can be detected by serological tests like enzyme-linked immunosorbent assay (ELISA) and agar gel immunodiffusion (AGID) tests. Keeping in view the importance of EIA, a sero-survey and pa...

Mohammed Body, Abdulmajeed Al-rawahi

2011-01-01

29

An investigation of equine infectious anaemia infection in the Central Anatolia region of Turkey  

OpenAIRE

In this study, 162 horses, 80 donkeys and 51 mule serum samples were collected in Konya city. Additionally, 64 horse serum samples from Ankara and 49 samples from Kayseri city were included in the study. A total of 406 serum samples were examined by agar gel immunodiffusion (AGID) and enzyme-linked immunosorbent assay (ELISA) for antibody to equine infectious anaemia virus (EIAV) and no positive result was detected.

Sahna, K. C.; Simsek, A.; Bulut, O.; Kale, M.; Yavru, S.; Yapkic, O.

2012-01-01

30

An investigation of equine infectious anaemia infection in the Central Anatolia region of Turkey  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, 162 horses, 80 donkeys and 51 mule serum samples were collected in Konya city. Additionally, 64 horse serum samples from Ankara and 49 samples from Kayseri city were included in the study. A total of 406 serum samples were examined by agar gel immunodiffusion (AGID and enzyme-linked immunosorbent assay (ELISA for antibody to equine infectious anaemia virus (EIAV and no positive result was detected.

K.C. Sahna

2012-05-01

31

An evaluation of selected screening tests for bovine paratuberculosis.  

OpenAIRE

The objective of this study was to evaluate the performance of the lipoarabinomannan antigen enzyme-linked immunosorbent assay (LAM-ELISA), carbohydrate antigen complement fixation (CH-CFT), and protein D antigen agar gel immunodiffusion (D-AGID) tests for bovine paratuberculosis, relative to histopathology, and to culture and isolation of Mycobacterium paratuberculosis from tissues and feces. Samples for test evaluation were collected from four sources including blood and tissues from 400 cu...

Mcnab, W. B.; Meek, A. H.; Duncan, J. R.; Brooks, B. W.; Dreumel, A. A.; Martin, S. W.; Nielsen, K. H.; Sugden, E. A.; Turcotte, C.

1991-01-01

32

Characterization of a soluble protein of Coccidiodes immitis with activity as an immunodiffusion-complement fixation antigen.  

OpenAIRE

A 48-kilodalton (kDa) electrophoretically distinct antigen from Coccidioides immitis mycelial- and spherule-endospore-phase filtrates was previously associated by immunoblotting with the immunodiffusion band that corresponds to complement-fixing activity (ID-CF). To characterize this antigen and its precursor, both mycelial- and spherule-endospore-phase filtrates were fractionated by size exclusion chromatography, lectin affinity chromatography, and nondenaturing electrophoresis. By size excl...

Zimmer, B. L.; Pappagianis, D.

1988-01-01

33

Comparison of continuous and discontinuous counterimmunoelectrophoresis with immunodiffusion in identification of candida antibody using HS antigen.  

Science.gov (United States)

We have compared continuous counterimmunoelectrophoresis (CCIE) and discontinuous counterimmunoelectrophoresis (DCIE) with immunodiffusion (ID) in the identification of Candida albicans antibody using HS antigen. Eighteen sera with a titer of 1/1 to 1/32 1/32 by CCIE were titered by CCIE and ID. Fewer were positive by CCIE and ID (13 of 18 and 9 of 18, respectively). Furthermore, the titers were lower when measured by these two methods in comparison to DCIE (4 of 18 and 3 of 18 sera had titers greather than or equal to 1/8 in comparison with 7 of 18 greater than or equal to 1/8 by DCIE). Finally, DCIE was found to be much faster than CCIE and ID. After 20 min of electrophoresis, 17 of 21 sera were positive by DCIE, whereas none were positive by CCIE. Even after 90 min, only 10 of 21 were positive by CCIE, whereas 4 of 21 were positive by ID. The increased sensitivity and speed of DCIE over CCIE and ID suggest that DCIE is preferable to these other methods in the measurement of candida antibody using HS antigen. PMID:97308

Marier, R; Andriole, V T

1978-07-01

34

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

35

Determination of thyroxine-binding globulin in human serum by single radial immunodiffusion and radioimmunoassay. [/sup 125/I tracer technique  

Energy Technology Data Exchange (ETDEWEB)

Two immunochemical methods for determination of thyroxine-binding globulin in human serum were developed, in which the purified globulin and monospecific antiserum to it are used. One method, based on radial immunodiffusion, has good precision and values for analytical recovery. Reference values obtained for men were 9.8 to 17.8 mg/liter and for women 11.3 to 20.5 mg/liter. The sex-related difference was significant. The other method is based on radioimmunoassay, with use of an iodinated acylating agent for the labeling of thyroxine-binding globulin. The relative merits of the two methods are discussed.

Kagedal, B.; Kallberg, M.

1977-09-01

36

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

37

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.)

38

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

39

Amperometric immunosensor for diagnosis of BLV infection.  

Science.gov (United States)

A new amperometric immunosensor for detection of antibodies against bovine leukemia protein (gp51) was designed. The detection of antibody-antigen complex formation was based on application of secondary antibodies labeled with horseradish peroxidase (HRP). Ferrocenecarboxylic acid (FCA) and N,N,N',N'-tetramethylbenzidine (TMB) were selected as suitable mediators for this immunosensor. Optimal conditions for amperometric detection were found. Sensitivity of created system was compared with the results of enzyme-linked immunosorbent assay (ELISA) and agar gel immunodiffusion (AGID) reaction, and was sufficient for detection of usual anti-gp51 antibody concentration present in the blood serum of BLV-infected cattle. PMID:18294837

Kurtinaitiene, Bogumila; Ambrozaite, Dovile; Laurinavicius, Valdas; Ramanaviciene, Almira; Ramanavicius, Arunas

2008-05-15

40

Seroprevalence of infectious bursal disease virus in local chickens in Udu Local Government Area of Delta State, South East Nigeria.  

Science.gov (United States)

Infectious Bursal Disease Virus (IBDV) poses a great global threat to the poultry industry. Knowledge of the occurrence of the disease is important in the design and implementation of a control program, therefore this study determines the seroprevalence of IBDV in local chickens in Udu Local Government Area of Delta State. 250 chickens were bled by exsanguination and sera obtained were screened using Agar Gel Immunodiffusion (AGID) test. The seropositivity was 51.6%, which is indicates endemicity of the disease. Biosecurity and good sanitary measures are recommended. Molecular characterization of the strains should be carried out for inclusion in generic vaccines. PMID:25331185

Abraham-Oyiguh, J; Adewumi, M O; Onoja, A B; Suleiman, I; Sulaiman, L K; Ahmed, S J; Jagboro, S T

2015-01-01

41

Investigation on the status of Johne's disease based on agar gel immunodiffusion, ziehl-neelsen staining and nested PCR approach in two cattle farm  

OpenAIRE

Background and Methods: Paratuberculosis is a chronic disease of ruminant, caused by Mycobacterium avium subsp. paratuberculosis (Map), clinically infected animals produce high level of antibodies in blood and shed detectable amount of Map organisms in feces. Several serological and molecular tests are utilized for detection of antibodies or DNA of the organism in clinical samples. Present study indicates the status of paratuberculosis in two distinct cattle farms with different organizationa...

Anand Mohan,; Pranabananda Das,; Neelam Kushwaha,; Kaliaperumal Karthik; Ankush Kiran Niranjan

2013-01-01

42

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

Scientific Electronic Library Online (English)

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

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

1988-09-01

43

Aerosol gels  

Science.gov (United States)

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

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

2010-01-01

44

Prevalence of antibodies to type A influenza virus in wild avian species using two serologic assays  

Science.gov (United States)

Serologic testing to detect antibodies to avian influenza (AI) virus has been an underused tool for the study of these viruses in wild bird populations, which traditionally has relied on virus isolation and reverse transcriptase-polymerase chain reaction (RT-PCR). In a preliminary study, a recently developed commercial blocking enzyme-linked immunosorbent assay (bELISA) had sensitivity and specificity estimates of 82% and 100%, respectively, for detection of antibodies to AI virus in multiple wild bird species after experimental infection. To further evaluate the efficacy of this commercial bELISA and the agar gel immunodiffusion (AGID) test for AI virus antibody detection in wild birds, we tested 2,249 serum samples collected from 62 wild bird species, representing 10 taxonomic orders. Overall, the bELISA detected 25.4% positive samples, whereas the AGID test detected 14.8%. At the species level, the bELISA detected as many or more positive serum samples than the AGID in all 62 avian species. The majority of positive samples, detected by both assays, were from species that use aquatic habitats, with the highest prevalence from species in the orders Anseriformes and Charadriiformes. Conversely, antibodies to AI virus were rarely detected in the terrestrial species. The serologic data yielded by both assays are consistent with the known epidemiology of AI virus in wild birds and published reports of host range based on virus isolation and RT-PCR. The results of this research are also consistent with the aforementioned study, which evaluated the performance of the bELISA and AGID test on experimental samples. Collectively, the data from these two studies indicate that the bELISA is a more sensitive serologic assay than the AGID test for detecting prior exposure to AI virus in wild birds. Based on these results, the bELISA is a reliable species-independent assay with potentially valuable applications for wild bird AI surveillance.

Brown, Justin D.; Luttrell, M. Page; Berghaus, Roy D.; Kistler, Whitney; Keeler, Shamus P.; Howey, Andrea; Wilcox, Benjamin; Hall, Jeffrey; Niles, Larry; Dey, Amanda; Knutsen, Gregory; Fritz, Kristen; Stallknecht, David E.

2010-01-01

45

Sero-Survey of Equine Infectious Anemia in the Sultanate of Oman during 2007-2009  

Directory of Open Access Journals (Sweden)

Full Text Available Equine infectious anemia (EIA is a fatal and relapsing infectious disease of equines caused by the lentivirus of Retroviridae family which occurs world-wide. It tends to become an inapparent infection if death does not result from the acute clinical attack. The virus persists in infected animals for life and can be detected by serological tests like enzyme-linked immunosorbent assay (ELISA and agar gel immunodiffusion (AGID tests. Keeping in view the importance of EIA, a sero-survey and passive surveillance was designed to establish the status of EIA in Oman. For the current study, ELISA was carried out on 331 random horse serum samples collected from all over Oman and 262 serum samples submitted from race horses. Four (0.67% out of total 593 serum samples were found positive on ELISA. These samples were further tested by agar gel immunodiffusion (AGID test for the confirmation and were found negative. Based on the analysis of the samples, it can be assumed that the horse population in the Sultanate was free of the disease during the study period (2007-2009.

Mohammed Body, Abdulmajeed Al-Rawahi, M. Hammad Hussain*, Khalisa Al-Lamki, Saif Al-Habsy, Mahir Almaawali and Qais Abdullah Alrawahi

2011-06-01

46

Buckling of swelling gels  

OpenAIRE

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...

Mora, Thierry; Boudaoud, Arezki

2006-01-01

47

Temperature responsive gel displays  

Science.gov (United States)

Synthesis and application of engineered surface patterns on environmentally responsive polymer gels are reported here. N-isopropylacrylamide (NIPA) gel was deposited on the masked-surface of an acrylamide gel using photo-initiated polymerization method. The pattern of the NIPA deposited area can be either visible or invisible by simply switching temperature above or below the low critical solution temperature (LCST) of the NIPA gel. Such gels can be used as displays.

Zheng, Yindong; Wang, Changjie; Hu, Zhibing; Li, Yong

1999-10-01

48

Transmission of equine infectious anemia virus from horses without clinical signs of disease.  

Science.gov (United States)

Twenty seven adult horses positive to the agar gel immunodiffusion (AGID) test for equine infectious anemia (EIA), but with no history of clinical EIA, were used in transfusion studies to determine whether infectious EIA virus was present in 1 to 5 ml of their blood. Of 27 recipients, 21 (78%) became AGID test-positive at an average of 24 days after inoculation. Two horses that were initially negative when screened were retested and found to carry infectious virus in 5-300 ml of whole blood; the other 4 horses were not retested. Horse flies (Tabanus fuscicostatus Hine) were unable to transmit EIA virus from 10 AGID test-positive donors with no history of clinical EIA, but virus was transmitted from a pony with artificially induced acute EIA and from a horse that had recovered from a clinical attack of EIA 9 months earlier. Histopathologic changes indicative of EIA were noted in all test-positive recipients. The most consistent lesion was paracortical lymphoid hyperplasia in the splenic lymph node. PMID:6276353

Issel, C J; Adams, W V; Meek, L; Ochoa, R

1982-02-01

49

Detection of Brucella ovis in ovine from Paraíba State, in the Northeast region of Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english To determine the presence of Brucella ovis in ovine from Paraíba State, in the Northeast region of Brazil, 80 animals slaughtered in the public slaughterhouse of Patos city were used. Before slaughter, blood samples were collected by jugular venopuncture from each animal, and after slaughter, testic [...] les, epidydimus and uterus were aseptically collected. For the serological diagnosis of B. ovis and B. abortus infections, the agar gel immunodiffusion (AGID) and Rose Bengal (RBT) tests were carried out, respectively. In addition, microbiological culture and polymerase chain reaction (PCR) were performed on testicle, epidydimus and uterus samples. Six animals (7.5%) tested positive for the presence of B. ovis antibodies and all animals tested negative for the presence of B. abortus antibodies. One AGID-positive animal tested positive at uterine swab culture. PCR was able to amplify DNA of Brucella spp. from the pool of testicle, epidydimus and uterus samples from AGID-positive animals. This is the first report of isolation and detection of B. ovis DNA by PCR in ovine from the Northeast region of Brazil.

Clebert José, Alves; Salomão Moreira de, Figueiredo; Sérgio Santos de, Azevedo; Inácio José, Clementino; Lara Borges, Keid; Sílvio Arruda, Vasconcellos; Carolina de Sousa Américo, Batista; Vivianne Cambuí Mesquita, Rocha; Severino Silvano, Higino.

2010-06-01

50

Development of single-chain Fv against the nucleoprotein of type A influenza virus and its use in ELISA.  

Science.gov (United States)

Single chain fragment variable (ScFv) antibodies specific to the nucleoprotein (NP) of avian influenza virus (AIV) were developed using a phage display system. The variable heavy (VH) and the variable light (VL) chain gene fragments were derived from spleen cells of Balb/c mouse immunized with a recombinant NP (rNP) antigen (?63 kDa) of H5N1 influenza virus. The VH and the VL DNA fragments were assembled through a flexible linker DNA to generate ScFv DNA that was cloned subsequently in a phagemid to express ScFv protein in Escherichia coli cells. The specific reactivity of the ScFv with the rNP antigen and viral antigen (H5N1) was confirmed by Western blot and ELISA. A competitive inhibition ELISA (CI-ELISA) was developed using the rNP and the anti-NP ScFv for detection of type-specific antibodies to AIV in chicken sera. The ScFv based CI-ELISA was compared with hemagglutination inhibition (HI) test and agar gel immunodiffusion (AGID) test over 850 sera. Sensitivity of the CI-ELISA was 100% with HI and AGID and specificity was 98.7% with HI and 100% with AGID. PMID:25152529

Sengupta, Devyani; Shaikh, Asma; Bhatia, S; Pateriya, A K; Khandia, R; Sood, R; Prakash, A; Pattnaik, B; Pradhan, H K

2014-11-01

51

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 SciELO Argentina | Language: English Abstract in spanish 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

52

Removing water from gels  

International Nuclear Information System (INIS)

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

53

Removing water from gels  

International Nuclear Information System (INIS)

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

54

Radiotherapy gel dosimetry  

International Nuclear Information System (INIS)

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

55

Evaluation of efficacy of saponin and freund's incomplete adjuvanted paratuberculosis vaccine in murine model  

Directory of Open Access Journals (Sweden)

Full Text Available Aim: To compare the efficacy between saponin adjuvanted paratuberculosis killed vaccine and Freund's incomplete (FIC adjuvanted paratuberculosis vaccine in mice model. Materials and Methods: The study was conducted for a period of 11 months using 80 Swiss albino mice by dividing into four groups (Group I-mice vaccinated with killed Mycobacterium avium subspp. paratuberculosis (MAP adjuvanted with saponin, Group II- for FIC, Group III- Saponin control and Gr IV- FIC control. Faecal shedding, changes in body weight, presence of local reactions and clinical symptoms, were evaluated. Serological assays for humoral and cell mediated immune response were determined by agar gel immunodiffusion (AGID and nitric oxide test (NO respectively. A total of 76 serum samples, 52 faecal samples and 20 tissue samples were collected at different intervals during the study period. ZN staining; AGID test and nitric oxide test were employed for analysis of samples. Results: A total of 38 samples (37 faecal and 1 tissue sample and 18 serum samples were recorded as positive by ZN staining and AGID test respectively from all four groups of mice. Significant decrease in faecal shedding of organisms was observed in Group I mice vaccinated with saponin adjuvanted vaccine in comparison to Group II. Gain in body weight of Group I mice was recorded as higher than Group II. NO test revealed increase in the concentration of NO level in both vaccinated group but more significant in Group I. Conclusion: The tests results obtained revealed that killed MAP vaccine adjuvanted with saponin have higher protective efficacy in terms of reduced faecal shedding, gain in body weight, less side effects, absence of attributable specific symptoms of Johne's disease, etc. in comparison to killed MAP vaccine adjuvanted with FIC. The present study also reveals that AGID and NO estimation tests are specific tests which can be employed for diagnosis and comparison of efficacy of paratuberculosis vaccine.

Jubeda Begum

2014-07-01

56

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)

57

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

58

Nematic Nanotube Gels  

Science.gov (United States)

We report the creation of nematic nanotube gels containing large domains of isolated, oriented, half-micron-long, single-wall carbon nanotubes (SWNTs). We make them by homogeneously dispersing surfactant coated SWNTs at low concentration in an N-isopropyl acrylamide gel and then inducing a volume-compression transition. These gels exhibit hallmark properties of a nematic: birefrigence, anisotropy in optical absorption, and disclination defects. We also investigate the isotropic-to-nematic transition of these gels, and we describe the physical properties of their ensuing nematic state, including a novel buckling of sample walls. Finally, we provide a simple model to explain our observations.

Islam, M. F.; Alsayed, A. M.; Dogic, Z.; Zhang, J.; Lubensky, T. C.; Yodh, A. G.

2004-02-01

59

CONFORMANCE IMPROVEMENT USING GELS  

Energy Technology Data Exchange (ETDEWEB)

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

Randall S. Seright

2003-09-01

60

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 (< 30%). 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

61

Polymer gel; Kobunshi geru  

Energy Technology Data Exchange (ETDEWEB)

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

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

2000-02-05

62

Crystallization from Gels  

Science.gov (United States)

Among the various crystallization techniques, crystallization in gels has found wide applications in the fields of biomineralization and macromolecular crystallization in addition to crystallizing materials having nonlinear optical, ferroelectric, ferromagnetic, and other properties. Furthermore, by using this method it is possible to grow single crystals with very high perfection that are difficult to grow by other techniques. The gel method of crystallization provides an ideal technique to study crystal deposition diseases, which could lead to better understanding of their etiology. This chapter focuses on crystallization in gels of compounds that are responsible for crystal deposition diseases. The introduction is followed by a description of the various gels used, the mechanism of gelling, and the fascinating phenomenon of Liesegang ring formation, along with various gel growth techniques. The importance and scope of study on crystal deposition diseases and the need for crystal growth experiments using gel media are stressed. The various crystal deposition diseases, viz. (1) urolithiasis, (2) gout or arthritis, (3) cholelithiasis and atherosclerosis, and (4) pancreatitis and details regarding the constituents of the crystal deposits responsible for the pathological mineralization are discussed. Brief accounts of the theories of the formation of urinary stones and gallstones and the role of trace elements in urinary stone formation are also given. The crystallization in gels of (1) the urinary stone constituents, viz. calcium oxalate, calcium phosphates, uric acid, cystine, etc., (2) the constituents of the gallstones, viz. cholesterol, calcium carbonate, etc., (3) the major constituent of the pancreatic calculi, viz., calcium carbonate, and (4) cholic acid, a steroidal hormone are presented. The effect of various organic and inorganic ions, trace elements, and extracts from cereals, herbs, and fruits on the crystallization of major urinary stone and gallstone constituents are described. In addition, tables of gel-grown organic and inorganic crystals are provided.

Narayana Kalkura, S.; Natarajan, Subramanian

63

Conformance Improvement Using Gels  

Energy Technology Data Exchange (ETDEWEB)

This research project had two objectives. The first objective was to identify gel compositions and conditions that substantially reduce flow through fractures that allow direct channeling between wells, while leaving secondary fractures open so that high fluid injection and production rates can be maintained. The second objective was to optimize treatments in fractured production wells, where the gel must reduce permeability to water much more than that to oil.

Seright, Randall S.; Schrader, Richard; II Hagstrom, John; Wang, Ying; Al-Dahfeeri, Abdullah; Gary, Raven; Marin; Amaury; Lindquist, Brent

2002-09-26

64

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. PMID:20150687

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

2010-03-01

65

Rapid solid-phase radioimmunoassay for detection of equine infectious anemia viral antigen and antibodies: parameters involved in standardization  

International Nuclear Information System (INIS)

Solid-phase radioimmunoassays (SPRIA) are described for the detection of equine infectious anemia (EIA) viral antigen and antibodies. Protein-antigen P29 currently used in the agar-gel immunodiffusion (AGID) test was used as antigen in the SPRIA. The specificity of the reaction was assessed by inhibition with the antigen. The reaction of immune serum against EIA-virus antigen adsorbed to the wells, was completely inhibited by the antigen in solution. This property was applied in an indirect competitive SPRIA for the detection of viral protein P29. The detection threshold of the SPRIA for EIA virus protein was about 5 ng and about 1 ng of antibody can be detected. The assay is rapid, specific and sensitive and allows the testing of multiple serum samples with the advantage of employing a single secondary labelled antibody. (orig.)

66

Active Polymer Gel Actuators  

Directory of Open Access Journals (Sweden)

Full Text Available 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 heart muscles. Here we show a novel biomimetic gel actuator that can walk spontaneously with a wormlike motion without switching of external stimuli. The self-oscillating motion is produced by dissipating chemical energy of oscillating reaction. Although the gel is completely composed of synthetic polymer, it shows autonomous motion as if it were alive.

Shuji Hashimoto

2010-01-01

67

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

68

Calcium tartrate gel.  

Science.gov (United States)

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

Akhrem, A A; Drozhdenyuk, A P

1989-05-15

69

Immunochromatographic lateral flow test for detection of antibodies to Equine infectious anemia virus.  

Science.gov (United States)

The purpose of this study was to develop and evaluate a simple immunochromatographic lateral flow (ICLF) test for specific detection of Equine infectious anemia virus (EIAV) antibodies in equine sera. Viral recombinant p26 capsid protein (rp26) was used as the capture protein in the test line and as the detector reagent conjugated to colloidal gold. The performance of rp26-ICLF was evaluated, and the results obtained were compared with a commercially available agar gel immunodiffusion (AGID) test used as a standard of comparison according to international guidelines. The values obtained for comparative diagnostic sensitivity (98.3%), diagnostic specificity (87.4%) and concordance (92.4%) were similar to those reported for other ICLF tests for animal infectious diseases. Very good repeatability and reproducibility, as well as a total agreement with blind previous results from three proficiency test panels, were obtained, thus indicating that rp26-ICLF is a precise test. The end point of the twofold serial dilution of serum samples was the same as, and even better than, the AGID test, thus demonstrating the same analytical sensitivity as that of the reference method for EIA diagnosis. No cross-reactivity was observed when serum samples from horses with other infectious diseases were analyzed. rp26-ICLF proved to be a precise and rapid test suitable for field screening in veterinary practice, since minimal equipment and operator expertise are required. However, further research should be carried out to increase the level of sensitivity. PMID:20362005

Alvarez, I; Gutierrez, G; Barrandeguy, M; Trono, K

2010-08-01

70

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

71

Duration of passive immunity to small ruminant lentiviruses in lambs  

Directory of Open Access Journals (Sweden)

Full Text Available In order to evaluate the passive immunity against small ruminant lentiviruses (SRLV in lambs, this study was conducted from two experimental groups. The first one (G1 was established by nine lambs subjected to artificial feeding of colostrum of goats positive for SRLV. The second one (G2 was the control group, consisting of ten lambs subjected to suckling of colostrum from their negative mothers. Blood samples were obtained before the first feeding, after 24 hours of birth and at 7, 15, 30, 50, 70, 90 and 120 days of age. The concentrations of total serum protein (TSP, albumin (ALB, globulin (GLOB and immunoglobulin G (IgG were determined and antibodies to SRLV were surveyed from the techniques of agar gel immunodiffusion (AGID, enzyme linked immunosorbent assay (Elisa and immunoblotting (IB. In both groups, the lowest averages of TSP, GLOB and IgG were observed at birth and the highest averages were observed at 24 hours of life, due to absorption of colostral immunoglobulins. For G1, transfer of immunity could also be detected by immunodiagnostic tests. At birth, the animals were seronegative. After 24 hours, all animals were positive in three serological tests. Negative results began to be observed after 15 days of age by the AGID test. As for Elisa testing, all animals remained reagent until 50 days old. Only IB was able to detect anti-SRLV at 70 days. Regarding G2, all animals tested negative in AGID and IB, from birth until 120 days of age. However, false-positive results were observed until day 15 in Elisa, due to nonspecific reactions. These data are consistent with the sensitivity and specificity of serological tests and show that starting at 90 days of age, colostral antibodies to SRLV are no longer detected in the serum of lambs.

Thiago Sampaio de Souza

2014-02-01

72

The Gel Generator option  

International Nuclear Information System (INIS)

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

73

Staining Proteins in Gels  

OpenAIRE

Following separation by electrophoretic methods, proteins in a gel can be detected by several staining methods. This unit describes protocols for detecting proteins by four popular methods. Coomassie blue staining is an easy and rapid method. Silver staining, while more time consuming, is considerably more sensitive and can thus be used to detect smaller amounts of protein. Fluorescent staining is a popular alternative to traditional staining procedures, mainly because it is more sensitive th...

Gallagher, Sean; Chakavarti, Deb

2008-01-01

74

MAGIC Gel Dosimetry  

Science.gov (United States)

Proton therapy has proven a very successful tool in treating certain tumors, but a three dimensional view of this fact has not yet been clearly demonstrated. In this experiment we have used MAGIC (Methacrylic and Ascorbic Acid in Gelatin Initiated by Copper) gel to represent brain tissue and gone through normal treatment planning for an Acoustic Neuroma to show the three dimensional dose distributions associated with such a tumor.

Mifflin, Rachel; Shahnazi, Kambiz; Jesseph, Rick

2008-10-01

75

Piezoelectric property of sol-gel-derived composite gels  

Science.gov (United States)

Low-density piezoelectric aluminosilicate ceramics were prepared by sol-gel technology. In order to reinforce the fragile aluminosilicate aerogels, the inorganic component was mixed with organic polymers (polyacrylic acid, polyvinyl acetate, polydimethylsiloxane) during the gelling process. The strength of the composite gels increases two- or threefold, the piezoelectricity of the composite gels changes variously depending on the organic polymers. The aerogel containing polyvinyl acetate shows negligible piezoelectricity. The use of polydimethylsiloxane decreases the piezoelectricity by 50%; polyacrylic acid increases it by 100%. The structure and the Al incorporation have strong effects on the piezoelectricity. The chemical structures of the composite gels were investigated by means of 27Al and 29Si MAS NMR. Except for the gel samples with PDMS, the porosity of hybrid gels diminishes.

Sinko, Katalin; Fel, Kornel; Rohonczy, Janos; Huesing, Nicola

2001-07-01

76

Clarification Procedure for Gels  

Science.gov (United States)

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

Barber, Patrick G.; Simpson, Norman R.

1987-01-01

77

Staining proteins in gels.  

Science.gov (United States)

Following separation by electrophoretic methods, proteins in a gel can be detected by several staining methods. This unit describes protocols for detecting proteins by four popular methods. Coomassie blue staining is an easy and rapid method. Silver staining, while more time consuming, is considerably more sensitive and can thus be used to detect smaller amounts of protein. Fluorescent staining is a popular alternative to traditional staining procedures, mainly because it is more sensitive than Coomassie staining, and is often as sensitive as silver staining. Staining of proteins with SYPRO Orange and SYPRO Ruby are also demonstrated here. PMID:19066521

Gallagher, Sean; Chakavarti, Deb

2008-01-01

78

High transparent shape memory gel  

Science.gov (United States)

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

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

2014-03-01

79

Designing biomimetic reactive polymer gels  

Directory of Open Access Journals (Sweden)

Full Text Available Materials of the future will exhibit bio-inspired behavior that enables a range of novel applications. We review computational studies on reactive gels that reveal how to tailor the gels and external stimuli to impart this biomimetic functionality. For example, photo-responsive gels can be ‘molded’ by light into various three-dimensional shapes, permitting a single sample to have multiple uses. Reactive gels undergoing the Belousov–Zhabotinsky (BZ reaction ‘communicate’ to form self-rotating gears, which could perform autonomous work. Finally, nanorod-filled reactive gels effectively regenerate the gel matrix when a layer of the material is sliced-off and thus, dramatically extend the material's life time.

Olga Kuksenok

2014-12-01

80

Polyoxometalate-based Supramolecular Gel  

OpenAIRE

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

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

2013-01-01

81

THE PROPERTIES OF CARRAGEENAN GELS  

Directory of Open Access Journals (Sweden)

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

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

2012-04-01

82

Preparation of porous silica gel  

International Nuclear Information System (INIS)

Preparation of porous spherical silica gel beads by suspension gelation is described. Silica sol prepared from sodium silicate and dilute hydrochloric acid at pH 4-5 dispersed various organic solvents. Sol droplets gelled to hydrogel which upon drying yields porous silica gel beads. Porosity of silica gel beads was varied by treatment of air dried hydrogel with ammonia and hydrothermal treatment. Silica beads prepared from an aged sol and hexamethylene tetramine had the highest pore volume and surface area. (author)

83

Supramolecular gels: functions and uses.  

Science.gov (United States)

In recent years there has been immense interest in studying gels derived from low molecular mass gelators (supramolecular, or simply molecular gels). The motivation for this is not only to understand the fundamental aggregate structures in the gels at different length scales, but also to explore their potential for futuristic technological applications. Gels have been made sensitive to external stimuli like light and chemical entities by incorporating a spectroscopically active or a receptor unit as part of the gelator molecule. This makes them suitable for applications such as sensing and actuating. The diversity of gel structural architectures has allowed them to be utilized as templates to prepare novel inorganic superstructures for possible applications in catalysis and separation. Gels derived from liquid crystals (anisotropy gels) that can act as dynamically functional materials have been prepared, for example, for (re-writable) information recording. Supramolecular gels can be important in controlled release applications, in oil recovery, for gelling cryogenic fuels etc. They can also serve as media for a range of applications. This tutorial review highlights some of the instructive work done by various groups to develop smart and functional gels, and covers a wide spectrum of scientific interest ranging from medicine to materials science. PMID:16172672

Sangeetha, Neralagatta M; Maitra, Uday

2005-10-01

84

Gel polymer electrolytes for batteries  

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-11-18

85

Phase behaviors of agarose gel  

Directory of Open Access Journals (Sweden)

Full Text Available We present evidence for the existence of phase separation in the gel state of agarose having the mixture of water and methanol as the gel solvent. Firstly, the sol-gel transition line and the cloud point line are determined independently as a function of the concentration of agarose as well as the concentration of methanol in the mixed solvent by the quasi-equilibrium cooling of the solutions. Then the spinodal line is determined by quenching the solutions below the sol-gel transition line. We find that the spinodal line appears below the cloud point line and both lines are entirely buried below the sol-gel transition line in the aqueous agarose system. The concentration fluctuations are, therefore, frozen into the polymer network of agarose gel that promotes the opacity of the resultant gel. The structure of agarose gel is observed by the confocal laser scanning microscope (CLSM imaging technique that reveals that the density fluctuations are grown up to micrometer scale in space. The phase separation boundary is found to shift to the higher temperature region than the sol-gel transition line when the concentration of methanol in the mixed solvent is increased. The results indicate that the position of the phase separation boundary in relative to the sol-gel transition line varies with the quality of solvent. These results are in agreement with the theory of the sol-gel transition in which both the divergence of the connectivity and the thermodynamic instability are taken into account.

Takaharu Morita

2013-04-01

86

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

87

Crystallization of steroids in gels  

Science.gov (United States)

The crystal growth and characterization of certain steriods, viz., cholesterol, cholesteryl acetate, ?-sitosterol, progesterone and testosterone, in a silica gel medium is discussed. The present study shows that the single test tube diffusion method can be used to grow crystals of steroids in a silica gel medium by the reduction of steroid solubility.

Kalkura, S. Narayana; Devanarayanan, S.

1991-03-01

88

Pecan drying with silica gel  

Energy Technology Data Exchange (ETDEWEB)

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

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

1983-07-01

89

Electromechanical nonionic gels  

International Nuclear Information System (INIS)

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

90

sol-gel  

Directory of Open Access Journals (Sweden)

Full Text Available En este trabajo sintetizamos nanocilindros de dióxido de titanio de 30 a 400 nm por medio de ADN del plásmido pBR322 de 4,362 pares de bases y el uso de isopropóxido de titanio como precursor por medio del proceso sol-gel. Los geles resultantes fueron calcinados y los polvos caracterizados por medio de Microscopio Electrónico de Barrido (MEB, Espectroscopía de Energía Dispersiva, Microscopio Electrónico de Transmisión (MET y Difracción de Rayos X. Los resultados muestran que la síntesis in vitro de nanorods en presencia de ADN, puede ser activada. Muchas otras moléculas sintéticas pueden producirse por medio del uso de sistemas orgánicos, es así como reportamos la síntesis de híbridos hechos de ácidos nucleicos en materiales inorgánicos que pueden tener diversas aplicaciones en sistemas catalíticos, biomateriales y materiales nanoestructurados.

Humberto A. Monreal

2005-01-01

91

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

92

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

93

Chemical Gel for Surface Decontamination  

International Nuclear Information System (INIS)

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

94

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

95

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

96

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

97

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

98

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

99

Topical Review: Polymer gel dosimetry  

OpenAIRE

Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose ...

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

2010-01-01

100

Radiotherapy Gel Dosimetry: Development and Application of Normoxic Polymer Gels  

International Nuclear Information System (INIS)

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

101

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. PMID:20150687

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

2010-01-01

102

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

Science.gov (United States)

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. PMID:25006685

Liu, Chao; Thormann, Esben; Claesson, Per M; Tyrode, Eric

2014-07-29

103

Rheology and structure of milk protein gels  

OpenAIRE

Recent studies on gel formation and rheology of milk gels are reviewed. A distinction is made between gels formed by aggregated casein, gels of `pure` whey proteins and gels in which both casein and whey proteins contribute to their properties. For casein' whey protein mixtures, it has been shown that both the fraction whey protein aggregated with the casein particles and whey protein aggregates dispersed in the continuous phase have a large impact on the structural and mechanical properties ...

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

2004-01-01

104

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

Scientific Electronic Library Online (English)

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

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

2008-06-01

105

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

106

Relación entre la prueba intradermica de histoplasmina y los niveles de anticuerpos detectables por ELISA e immunodifusion Relationship between histoplasmin skin test and Histoplasma capsulatum antibody levels detected by ELISA and immunodiffusion tests  

Directory of Open Access Journals (Sweden)

Full Text Available Se realizó un estudio prospectivo en 40 trabajadores de una granja avícola (grupo 1 considerados con riesgo de exposición a Histoplasma capsulatum, agente etiológico de la histoplasmosis, y en 16 individuos sin riesgo profesional de exposición a dicho agente (grupo 2. En ambos grupos se aplicó la prueba intradérmica de histoplasmina y se obtuvo el suero antes de su aplicación y a los 30 y 180 días después de realizada dicha prueba. Se determinó el nivel de anticuerpos anti-H. capsulatum mediante las técnicas de ELISA e inmunodifusión doble. En los dos grupos de población estudiados la aplicación intradérmica de histoplasmina, aún en los casos en que la respuesta fue positiva, no constituyó un estímulo antigénico suficiente para provocar un aumento en los niveles de anticuerpos anti-H. capsulation detectables por las técnicas serológicas empleadas. Los resultados obtenidos contribuyen a la mejor interpretación de la prueba de ELISA en el diagnóstico de la histoplasmosis.A prospective study was carried out in two groups of individuals: a group 1 (n=40 included workers from a poultry farm, with potencial occupational risk of exposure to Histoplasma capsulatum, ethiologic agent of histoplasmosis, and a group 2 (n=16, persons without occupational risk of exposure to the agent. Histoplasmin skin test was performed in both groups, and three sera were obtained from each individual: 1 before skin test was done, 2 30 days after, and 3 180 days after it. In both groups the histoplasmin skin test, even when the test was positive, was not a sufficient antigenic booster to provoque an increase in the H. capsulatum antibody levels capable to be detected by the Serologic tests used (ELISA and Double Immunodiffusion. These results contribute to improve the interpretation of ELISA test values in the diagnosis of histoplasmosis.

Carlos M. Fernandez-Andreu

1994-02-01

107

Relación entre la prueba intradermica de histoplasmina y los niveles de anticuerpos detectables por ELISA e immunodifusion / Relationship between histoplasmin skin test and Histoplasma capsulatum antibody levels detected by ELISA and immunodiffusion tests  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Spanish Abstract in spanish Se realizó un estudio prospectivo en 40 trabajadores de una granja avícola (grupo 1) considerados con riesgo de exposición a Histoplasma capsulatum, agente etiológico de la histoplasmosis, y en 16 individuos sin riesgo profesional de exposición a dicho agente (grupo 2). En ambos grupos se aplicó la [...] prueba intradérmica de histoplasmina y se obtuvo el suero antes de su aplicación y a los 30 y 180 días después de realizada dicha prueba. Se determinó el nivel de anticuerpos anti-H. capsulatum mediante las técnicas de ELISA e inmunodifusión doble. En los dos grupos de población estudiados la aplicación intradérmica de histoplasmina, aún en los casos en que la respuesta fue positiva, no constituyó un estímulo antigénico suficiente para provocar un aumento en los niveles de anticuerpos anti-H. capsulation detectables por las técnicas serológicas empleadas. Los resultados obtenidos contribuyen a la mejor interpretación de la prueba de ELISA en el diagnóstico de la histoplasmosis. Abstract in english A prospective study was carried out in two groups of individuals: a group 1 (n=40) included workers from a poultry farm, with potencial occupational risk of exposure to Histoplasma capsulatum, ethiologic agent of histoplasmosis, and a group 2 (n=16), persons without occupational risk of exposure to [...] the agent. Histoplasmin skin test was performed in both groups, and three sera were obtained from each individual: 1) before skin test was done, 2) 30 days after, and 3) 180 days after it. In both groups the histoplasmin skin test, even when the test was positive, was not a sufficient antigenic booster to provoque an increase in the H. capsulatum antibody levels capable to be detected by the Serologic tests used (ELISA and Double Immunodiffusion). These results contribute to improve the interpretation of ELISA test values in the diagnosis of histoplasmosis.

Carlos M., Fernandez-Andreu; Ana Margarita, Cadre-Raton; Gerardo, Martinez Machin; Alina Llop, Hernandez; Miguel, Suarez Hernandez.

1994-02-01

108

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

109

Transport properties of incipient gels  

CERN Document Server

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

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

2003-01-01

110

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)

111

Screening effect on nanostructure of charged gel  

Energy Technology Data Exchange (ETDEWEB)

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

Sugiyama, Masaaki; Annaka, Masahiko; Hino, Masahiro; Fukunaga, Toshiharu; Vigild, Martin E.; Hara, Kazuhiro

2004-07-15

112

Screening effect on nanostructure of charged gel  

Science.gov (United States)

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

Sugiyama, Masaaki; Annaka, Masahiko; Hino, Masahiro; Fukunaga, Toshiharu; E. Vigild, Martin; Hara, Kazuhiro

2004-07-01

113

Screening effect on nanostructure of charged gel  

DEFF Research Database (Denmark)

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

Sugiyama, M; Annaka, M

2004-01-01

114

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

115

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

116

Gel catalysts that switch on and off  

OpenAIRE

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

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

2000-01-01

117

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

118

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

119

Sol-gel routes to superconducting ceramics  

International Nuclear Information System (INIS)

Potential processing advantages of sol-gel techniques for fabricating ceramic end products are discussed with reference to some typical sol-gel approaches outlined in the literature for producing high temperature ceramic superconducting materials. The author's sol-gel research is reported with reference to synthesis of metallo- organic precursor materials, sol-gel processing with those precursor materials, and characterization of high temperature superconducting materials in the BaO-Y2O3-CuO system

120

Active Gel Model of Amoeboid Cell Motility  

OpenAIRE

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 contai...

Callan-jones, A. C.; Voituriez, R.

2013-01-01

121

A clarified gel for crystal growth  

Science.gov (United States)

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

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

1985-01-01

122

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.)

123

Anisotropic elasticity of magnetically ordered agarose gel  

Directory of Open Access Journals (Sweden)

Full Text Available The physical properties of agarose gel prepared under strong magnetic fields were investigated. The storage modulus was measured by the reflection method with an ultrasonic pulse. The measurement results of the gel's elasticity indicate that agarose gel has anisotropic properties. The elasticity and its anisotropy depend on the concentration of the gel and the magnetic field to which it is exposed. The experimental results indicate that the anisotropic network structure of the gel is induced by the exposure to the magnetic field during gelation. The gelation mechanism under a magnetic field is discussed

Isao Yamamoto et al

2008-01-01

124

Birefringence Modulated Scattering in Gels  

OpenAIRE

We describe a novel effect that arises when a monochromatic light beam passes through a deswollen rigid-rod gel. When viewed perpendicular to the direction of propagation, under suitable conditions of polarisation, a pattern of fringes is observed. The phenomenon is a simple geometrical optical effect caused by the birefringence of the sample. For a given wavelength ? of incident light, observation of the spatial frequency of the fringes, ?n/?, offers an inexpensive means of measuring the ...

Rochas, Cyrille; Hecht, Anne-marie; Geissler, Erik

1995-01-01

125

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

126

Symmetries and Elasticity of Nematic Gels  

CERN Document Server

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

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

2002-01-01

127

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)

128

Effects of infection with caprine arthritis-encephalitis virus on milk production in goats.  

Science.gov (United States)

A recently assembled commercial herd of Alpine goats was studied. Milk production criteria--305-day milk production (M), butter fat content (BF), and solids nonfat content (SNF)--and somatic cell counts (linear score) were monitored by Dairy Herd Improvement Association test records. Milk samples from all milking goats in the herd were obtained for bacteriologic culture for mastitis organisms on 2 occasions; the infection rate ascribed to major pathogens was 3%. In November 1985, serum specimens were obtained from 154 does in first lactation. Of these, 56 (36%) were seropositive for caprine arthritis-encephalitis (CAE) antibodies by agar gel immunodiffusion (AGID), 91 (59%) were seronegative, and serotest results for 7 (5%) were inconclusive. In December, 80 seronegative and 48 seropositive goats remained in the herd and had 305-day projections available. The median production values for seronegative goats (1,539.5 lb of M, 52 lb of BF, 46 lb of SNF) were higher than those for seropositive goats (1,446 lb of M, 45 lb of BF, 44.5 lb of SNF), but this difference was only significant (t test, P less than 0.05) for BF. Does were ranked by a formula that combined M, BF, and SNF, with a desired minimal daily herd average of 5 lb of M, 3% BF, and 3% SNF. A decision was made not to keep offspring from does of the lowest quartile before CAE test results were obtained. This group consisted of 13 of the 80 (16%) seronegative goats and 18 of the 48 (38%) seropositive goats. Thus, a positive CAE test result by AGID was associated (chi 2, P less than 0.01) with poor production.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2843492

Smith, M C; Cutlip, R

1988-07-01

129

Soroepidemiologia da leucemia bovina (LB) em bovinos curraleiros dos estados de Goiás e Tocantins, Brasil / Seroepidemiology of bovine leukaemia (LB) in curraleiro cattle breed from Goiás and Tocantins states  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Com o objetivo de verificar a ocorrência da leucose enzoótica (LB) em bovinos Curraleiros, foram amostrados soros sanguíneos de um total de 1051 animais pertencentes a 11 rebanhos localizados nos Estados de Goiás e 12 em Tocantins. O diagnóstico sorológico de LB foi realizado pelo método de imunodif [...] usão em gel de ágar (IDGA). A taxa total de sororeagentes foi 21,1% (222/1051). Em Tocantins foram encontrados 27,8% (136/489) de sororreagentes, número significativamente maior que em Goiás, onde foram encontrados 15,3% (86/562). A sororreatividade foi maior em fêmeas que em machos, 23,3% (198/852) e 11,8% (23/195), respectivamente, e em animais com idade superior a 48 meses. Abstract in english Aiming to verify bovine leukaemia (BL) occurrence in Curraleiro cattle breed, sera of 1051 animals were sampled from Goias (n=11) and Tocantins (n=12) states. BL serological diagnosis was performed by agar gel immunodiffusion method (AGID). The total occurrence rate was 21.1% (222/1051). In Tocantin [...] s it was 27.8% (136/489) occurrence was observed, higher value than in Goias, where 15.3% (86/562) occurrence was found. The serum reactivity was higher in females than in males, 23.3% (198/852) and 11.8% (23/195), respectively, and in animals older than 48 months old.

Raquel Soares, Juliano; Maria Clorinda Soares, Fioravanti; Wilia Marta Elsner Diederichsen de, Brito; Urbano Gomes Pinto de, Abreu; Saura Nayane de, Souza.

2014-09-01

130

Prevalencia de brucelosis canina en dos distritos de la Provincia Constitucional del Callao  

Scientific Electronic Library Online (English)

Full Text Available SciELO Peru | Language: Spanish Abstract in spanish El objetivo del presente estudio fue determinar la prevalencia de brucelosis canina (Brucella canis) en dos distritos de la Provincia Constitucional del Callao. Se recolectaron 456 sueros de perros sin distinción de sexo, raza y edad, que se analizaron mediante la prueba de Inmunodifusión en Gel de [...] Agar (IDGA) con antígeno de B. ovis. Se encontró una prevalencia de 15.6 ± 33% (71/456). No se encontró diferencia estadística significativa entre las variables distrito, sexo, raza o grupo etáreo, pero se encontró diferencia estadística significativa (p Abstract in english The objective of this study was to determine the prevalence of canine brucellosis (Brucella canis) in two districts of the province of Callao. A total of 456 sera were collected from dogs without distinction of breed, sex and age. Samples were analyzed by the Agar Gel Immunodiffusion (AGID) test usi [...] ng B. ovis antigen. The results indicated that 15.6 ± 3.3 (71/456) of sampled animals were positive. No statistical differences were found due to district, breed, sex or age; however, differences were found (p

Hernán, Ramírez L; Sonia, Calle E.; Luisa, Echevarría C.; Siever, Morales C..

2006-01-01

131

Generative force of self-oscillating gel.  

Science.gov (United States)

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

Hara, Yusuke; Mayama, Hiroyuki; Morishima, Keisuke

2014-03-01

132

Metal-silica sol-gel materials  

Science.gov (United States)

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

Stiegman, Albert E. (Inventor)

2002-01-01

133

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

134

Graphical analysis for gel morphology. III. Gel size and temperature effects on the volume phase transition of gels.  

Science.gov (United States)

Just after poly(N-isopropylacrylamide) (PNIPA) gels are immersed into hot water over the critical temperature, they undergo a two- or three-step shrinking accompanied with the whitening. The size of gels and the destination temperature were changed and their effects on the shrinking process of PNIPA gels were studied. The following important knowledge in the volume phase transition process of PNIPA gels was obtained. The first is the fact that the fraction of first shrinking is determined by the shrinking rate in the first shrinking stage. The second is the fact that PNIPA gels are divided into small parts by the pinning of density fluctuation in the final stage of the first shrinking and that the shrinking process of each small part undergoes in the secondary shrinking stage. The volume phase transition process of PNIPA gels is briefly discussed from the viewpoint of the scaling theory. PMID:16460208

Hashimoto, Chihiro; Ushiki, Hideharu

2006-01-28

135

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 SciELO Brazil | Language: English Abstract in portuguese 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

136

Motility initiation in active gels  

CERN Document Server

Motility initiation in crawling cells requires a symmetry breaking mechanism which transforms a symmetric state into a polarized state. Experiments on keratocytes suggest that polarization is triggered by increased contractility of motor proteins. In this paper we argue that contraction can be responsible not only for the symmetry breaking transition but also for the incipient translocation of the segment of an active gel mimicking the crawling cell. Our model suggests that when the contractility increases sufficiently far beyond the motility initiation threshold, the cell can stop and re-symmetrizes. The proposed theory reproduces the motility initiation pattern in fish keratocytes and the behavior of keratocytes prior to cell division.

Recho, Pierre; Truskinovsky, Lev

2015-01-01

137

Thermally stable mixed oxide gels  

International Nuclear Information System (INIS)

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

138

Sol-gel electrochromic device  

OpenAIRE

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

Macedo, Marcelo A.; Aegerter, Michel A.

1994-01-01

139

Characteristics of polyacrylamide gel with THPC and Turnbull Blue gel dosimeters evaluated using optical tomography  

Science.gov (United States)

The purpose of this study was to compare characteristics of radiochromic gel - Turnbull Blue gel (TB gel) with polymer gel - polyacrylamide gel and tetrakis hydroxymethyl phosphonium chloride (PAGAT) using optical tomography. Both types of gels were examined in terms of dose sensitivity, dose response linearity and background value of spectrophotometric absorbance. The calibration curve was obtained for 60Co irradiation performed on Gammacell 220 at predefined gamma dose levels between 0 and 140 Gy for TBG and 0-15 Gy for PAGAT. To measure relative dose distributions from stereotactic irradiation, dosimeters were irradiated on Leksell Gamma Knife Perfexion. The cylindrical glass housings filled with gel were attached to the stereotactic frame. They were exposed with single shot and 16 mm collimator by 65 Gy to a 50% prescription isodose for TB gel and 4 Gy to a 50% prescription isodose for PAGAT. Evaluations of dosimeters were performed on an UV-vis Spectrophotometer Helios ? and an optical cone beam homemade tomography scanner with a 16-bit astronomy CCD camera with a set of color filters. The advantages and potential disadvantages for both types of gel dosimeters were summarized. Dose distribution in central slice and measured profiles of 16 mm shot shows excellent correspondence with treatment planning system Leksell GammaPlan® for both PAGAT and Turnbull Blue gels. Gel dosimeters are suitable for steep dose gradient verification. An optical tomography evaluation method is successful. Dose response characteristics of TB gel and PAGAT gel are presented.

Pila?ová (Vávr?), Kate?ina; Kozubíková, Petra; Šolc, Jaroslav; Sp?vá?ek, Václav

2014-11-01

140

Automated apparatus for producing gradient gels  

Science.gov (United States)

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

Anderson, N.L.

1983-11-10

141

Automated apparatus for producing gradient gels  

Science.gov (United States)

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

Anderson, Norman L. (Clarendon Hills, IL)

1986-01-01

142

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

143

Low-Reynolds number swimming in gels  

OpenAIRE

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 nonline...

Fu, Henry C.; Shenoy, Vivek B.; Powers, Thomas R.

2010-01-01

144

FTIR thermal analysis on organofunctionalized silica gel  

OpenAIRE

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 ge...

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

2001-01-01

145

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)

146

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)

147

Gel nano-particulates against radioactivity  

International Nuclear Information System (INIS)

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

148

Gel catalysts that switch on and off.  

Science.gov (United States)

We report development of a polymer gel with a catalytic activity that can be switched on and off when the solvent composition is changed. The gel consists of two species of monomers. The major component, N-isopropylacrylamide, makes the gel swell and shrink in response to a change in composition of ethanol/water mixtures. The minor component, vinylimidazole, which is capable of catalysis, is copolymerized into the gel network. The reaction rate for catalytic hydrolysis of p-nitrophenyl caprylate was small when the gel was swollen. In contrast, when the gel was shrunken, the reaction rate increased 5 times. The activity changes discontinuously as a function of solvent composition, thus the catalysis can be switched on and off by an infinitesimal change in solvent composition. The kinetics of catalysis by the gel in the shrunken state is well described by the Michaelis-Menten formula, indicating that the absorption of the substrate by the hydrophobic environment created by the N-isopropylacrylamide polymer in the shrunken gel is responsible for enhancement of catalytic activity. In the swollen state, the rate vs. active site concentration is linear, indicating that the substrate absorption is not a primary factor determining the kinetics. Catalytic activity of the gel is studied for substrates with various alkyl chain lengths; of those studied the switching effect is most pronounced for p-nitrophenyl caprylate. PMID:10954747

Wang, G; Kuroda, K; Enoki, T; Grosberg, A; Masamune, S; Oya, T; Takeoka, Y; Tanaka, T

2000-08-29

149

Functional behavior of isotropic magnetorheological gels  

Science.gov (United States)

Magnetorheological (MR) gels are a new class of soft polymers whose properties can be controlled using a magnetic field. The functional effectiveness of these gels depends on their magnetic controllability. In this paper, an experimental investigation on the functional behavior of a particular type of magnetorheological gels under dynamic and static shear conditions in the presence of a magnetic field is studied. MR gels are prepared with micron sized polarizable carbonyl iron particles interspersed in a polymer matrix gel. The compliance of this magnetic gel can be varied under the influence of an external magnetic field. Since dynamical mechanical analysis tests are difficult to conduct in the presence of large deformations of the order of 50% and strong magnetic fields, a free decay test apparatus is designed and fabricated for obtaining the magnetic field dependent shearing response under dynamic conditions at room temperature. It is observed that a significant change in the elastic modulus occurs in the gels under a magnetic field in the range of 0.1-0.4 T. However, no significant change in the damping ratio is observed under various magnitudes of magnetic field. It is shown that the increase in shear modulus of this kind of magnetic composite gel could be as high as 59% of the zero field value for a gel prepared with 50% by weight of carbonyl iron particles.

Venkateswara Rao, P.; Maniprakash, S.; Srinivasan, S. M.; Srinivasa, A. R.

2010-08-01

150

Functional behavior of isotropic magnetorheological gels  

International Nuclear Information System (INIS)

Magnetorheological (MR) gels are a new class of soft polymers whose properties can be controlled using a magnetic field. The functional effectiveness of these gels depends on their magnetic controllability. In this paper, an experimental investigation on the functional behavior of a particular type of magnetorheological gels under dynamic and static shear conditions in the presence of a magnetic field is studied. MR gels are prepared with micron sized polarizable carbonyl iron particles interspersed in a polymer matrix gel. The compliance of this magnetic gel can be varied under the influence of an external magnetic field. Since dynamical mechanical analysis tests are difficult to conduct in the presence of large deformations of the order of 50% and strong magnetic fields, a free decay test apparatus is designed and fabricated for obtaining the magnetic field dependent shearing response under dynamic conditions at room temperature. It is observed that a significant change in the elastic modulus occurs in the gels under a magnetic field in the range of 0.1–0.4 T. However, no significant change in the damping ratio is observed under various magnitudes of magnetic field. It is shown that the increase in shear modulus of this kind of magnetic composite gel could be as high as 59% of the zero field value for a gel prepared with 50% by weight of carbonyl iron particles

151

Tissue simulating gel for medical research  

Science.gov (United States)

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

Companion, John A. (Inventor)

1991-01-01

152

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.

153

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

154

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

OpenAIRE

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

1987-01-01

155

Structure of acid casein gels - A study of gels formed after acidification in the cold.  

OpenAIRE

The structure of acid casein gels was studied by rheology, permeametry, electron microscopy and pulse NMR. Gels were mainly formed by heating at rest of casein solutions acidified in the cold (0- 2 °C). The structure of such gels involves both the spatial distribution of the structural elements and the interaction forces between them. An acid casein gel has an irregular particulate structure. Gelation results from the aggregation of casein particles, which themselves have a complex internal ...

Roefs, S. P. F. M.

1986-01-01

156

Terpolymer smart gels: synthesis and characterizations  

Science.gov (United States)

Two smart terpolymer gels, MS-1 and MS-2, were synthesized such that the same gel can respond to more than one external environmental condition, such as pH, temperature, solvent composition, electric field. So two terpolymers gels of vinyl monomers such as sodium acrylate, acrylamide and N-isopropyl acrylamide were synthesized by using ammonium persulfate (APS) as an initiator, N,N,N',N'-tetramethyl ethylene diamine (TMEDA) as an accelerator and methylene bisacrylamide as a cross-linker. These terpolymers were characterized by elemental and Fourier transform infrared analysis. The swelling behavior of these terpolymer smart gels was evaluated by changing the pH, temperature and solvent composition. The variation of the swelling behavior with time was evaluated in an aqueous medium at room temperature. The time taken for maximum swelling (tm) was about 20 min for the gel MS-2. However the tm value for the gel MS-1 is higher than that of MS-2. The swelling behavior remains almost unchanged over a temperature range of 22-50 °C for both the gels. The discontinuous volume transitions were observed at pH 7.6 and 8.2 for the two gels, MS-1 and MS-2, respectively. The gel MS-1 suddenly shrinks below and swells above pH 7.6. Correspondingly, the pH is 8.2 for the case of MS-2. Volume transitions in an acetone-water mixture were also observed for these gels. The swelling behaviors of these two smart gels are almost parallel above the 40% acetone concentration.

Bag, Dibyendu S.; Alam, Sarfaraz; Mathur, G. N.

2004-10-01

157

Chain Release Behavior of Gellan Gels  

Science.gov (United States)

The chain release behavior from gellan gels was studied by immersing the gel into water and monitoring the mass loss as a function of time. Concentration of released gellan in the external solution was determined for gels of different sizes using phenol-sulfuric acid method. The chain release process became faster with increasing total surface area and volume. However the concentration of released chain normalized by surface area and volume suggests that the chain release itself is governed not only by the ionic effect and the amount of unassociated chains in gel but other factors such as osmotic pressure may play an important role on the chain release from the gels. The diffusion coefficient was estimated from the chain release process which is in the same order of magnitude reported for an isolated gellan chain by light scattering. Rheological measurements also suggest that the unassociated gellan chains are released out when immersed in pure water while unassociated chains are restricted to release out when immersed in salt solution due to the intrusion of cations which is responsible for further association of the unassociated gellan chains being in agreement with the previously published results. The elastic modulus of gels was increased by immersion of gels in water and in salt solutions, which can be attributed as the stiffening of network chains due to gel swelling and the conversion from free and unassociated chains into network chains, respectively, leading to an increase in elastic modulus with time.

Hossain, Khandker S.; Nishinari, Katsuyoshi

158

Acoustic images of gel dosimetry phantoms  

Science.gov (United States)

This work presents Vibro-acoustography (VA) as a tool to visualize absorbed dose in a polymer gel dosimetry phantom. VA relies on the mechanical excitation introduced by the acoustic radiation force of focused modulated ultrasound in a small region of the object. A hydrophone or microphone is used to measure the sound emitted from the object in response to the excitation, and by using the amplitude or phase of this signal, an image of the object can be generated. To study the phenomena of dose distribution in a gel dosimetry phantom, continuous wave (CW), tone burst and multi-frequency VA were used to image this phantom. The phantom was designed using 'MAGIC' gel polymer with addition of glass microspheres at 2% w/w having an average diameter range between 40-75 ?m. The gel was irradiated using conventional 10 MeV X-rays from a linear accelerator. The field size in the surface of the phantom was 1.0×1.0 cm2 and a source-surface distance (SSD) of 100 cm. The irradiated volume corresponds to an approximately 8.0 cm3, where a dose of 50 gray was delivered to the gel. Polymer gel dosimeters are sensitive to radiation-induced chemical changes that occur in the irradiated polymer. VA images of the gel dosimeter showed the irradiate area. It is concluded that VA imaging has potential to visualize dose distribution in a polymer gel dosimeter.

Vieira, Silvio L.; Baggio, André; Kinnick, Randall R.; Fatemi, M.; Carneiro, Antonio Adilton O.

2010-01-01

159

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

160

Sorptive diffusion in clay gels  

International Nuclear Information System (INIS)

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

161

Topological characteristics of model gels  

International Nuclear Information System (INIS)

The Euler characteristic of an object is a topological invariant determined by the number of handles and holes that it contains. Here, we use the Euler characteristic to profile the topology of model three-dimensional gel-forming fluids as a function of increasing length scale. These profiles act as a 'topological fingerprint' of the structure, and can be interpreted in terms of three types of topological events. As model fluids we have considered a system of dipolar dumbbells, and suspensions of adhesive hard spheres with isotropic and patchy interactions in turn. The correlation between the percolation threshold and the length scale on which the Euler characteristic passes through zero is examined and found to be system-dependent. A scheme for the efficient calculation of the Euler characteristic with and without periodic boundary conditions is described.

162

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

163

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

164

Controlling the Morphology of Carbon Gels  

Directory of Open Access Journals (Sweden)

Full Text Available Carbon gels are unique porous carbons, which aretypically obtained through the carbonization ofresorcinol-formaldehyde gels. This material ispractically an aggregate of nanometer-sized carbonparticles. Nanopores, mostly in the size range ofmesopores, exist between the particles. Smallerpores, micropores being the majority, also exist withinthe particles. Therefore, this material has ahierarchical pore system in which short microporesare directly connected to mesopores.The precursor of carbon gels can be obtained throughsol-gel transition. Therefore there is a high possibilitythat the morphology of the resulting carbon can beeasily controlled using various molding methods.We have actually challenged the controlling of themorphology of carbon gels, and have succeeded inobtaining them in the form of disks, microspheresand microhoneycombs. Details of such carbon gelswill be reported.

S. R. Mukai

2012-12-01

165

Dewatering fine coal slurries by gel extraction  

Energy Technology Data Exchange (ETDEWEB)

A new technology called gel extraction has been evaluated to determine its economic viability in dewatering the fine and ultrafine coal slurries generated upon separation of sulfur and ash from clean coal during the physical coal cleaning process. Water must be removed from such slurries prior to transportation and combustion but the dewatering costs are substantial, especially for the fine particles below 28 mesh (0.6 mm). Gel extraction is a potential breakthrough in slurry dewatering technology. The goal of this project was to acquire the qualitative and quantitative data needed to estimate the potential of gel extraction for dewatering coal slurries. The specific objectives were to determine the maximum extents of dewatering (minimum surface moisture in the coal product), the clarity of the water removed (minimum solids content), the speed of the dewatering cycles, the service lifetime of the gels, and the factors which influence all of these. With the results obtained, an economic analysis of Ohio coal cleaning plant dewatering technologies was carried out. The polymer gel at the heart of this project, poly (N-isopropylacrylamide) (PNIPA), can swell several times its shrunken weight at 32[degrees]C by absorbing water at 25[degrees]C. In gel extraction, a shrunken NIPA gel is contacted with a slurry at ambient temperature or cooler; the gel swells by absorbing water from the slurry. The gel is then removed from the dewatered slurry and warmed above its critical temperature of 33[degrees]C, which returns it to the shrunken state by releasing the absorbed water. The facts that the gel is reusable and the process is simple and driven by low-grade energy (warm temperatures), and not inherently limited by particle size, made the process an attractive possible alternative to centrifugation, screening, filtration, etc. for slurry dewatering.

Gehrke, S.H.; Lyu, Lii-Hurng.

1990-01-01

166

21 CFR 520.1453 - Moxidectin and praziquantel gel.  

Science.gov (United States)

...2010-04-01 false Moxidectin and praziquantel gel. 520.1453 Section 520.1453 Food and... § 520.1453 Moxidectin and praziquantel gel. (a) Specifications . Each milliliter of gel contains 20 milligrams (mg) (2.0...

2010-04-01

167

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

168

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

169

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

170

Chemical waves in self-oscillating gels  

Science.gov (United States)

The behaviors of a poly(N-isopropyl acrylamide) (PNIPA) gel coupled with the Belousov-Zhabotinsky (BZ) reaction has been investigated as a function of temperature and catalyst concentration. In this type of gel, the chemical oscillation in the BZ reaction induces periodic and autonomous swelling-shrinking volume changes of the gel, and conversely a volume change of the PNIPA gel affects the propagation of the chemical wave. Our attention was focused on the effects of mechanical changes on the chemical wave by utilizing the thermally driven volume phase transition of the gel. Both the velocity and the frequency of the chemical wave increased with increasing temperature, and abruptly decreased at the volume transition temperature of the gel, Tc. The diffusion of HBrO2, which is essential for wave propagation, was hindered with increasing temperature. The diffusion of HBrO2 through the gel network in the low temperature region was explained in the same way as a simple diffusion of inactive molecules through a restricted environment.

Miyakawa, Kenji; Sakamoto, Fumitaka; Yoshida, Ryo; Kokufuta, Etsuo; Yamaguchi, Tomohiko

2000-07-01

171

Electroacoustics of Particles Dispersed in Polymer Gel  

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-06-27

172

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

173

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

174

Sol-gel coatings for electrochromic devices  

OpenAIRE

Electrochromic devices have potential applications in architectural and automotive fields to regulate the transmission and reflection of the radiant energy. Preliminary characteristics of an all sol-gel window with the configuration glassITOWO3TiO2TiO2-CeO2ITOglass is presented, and compared with another window where WO3 was deposited by evaporation. We also present preliminary data of a sol-gel Nb2O5 electrochromic layer as well as a thorough evaluation of the properties of a sol-gel TiO2-Ce...

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

1992-01-01

175

Acoustic evaluation of polymer gel dosimeters  

International Nuclear Information System (INIS)

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

176

Pulsed field gel electrophoresis a practical guide  

CERN Document Server

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

Birren, Bruce

2012-01-01

177

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

178

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)

179

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

Directory of Open Access Journals (Sweden)

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

A.S. Ali

2004-01-01

180

Buckling instability in liquid crystalline physical gels.  

Science.gov (United States)

In a nematic gel we observe a low-energy buckling deformation arising from soft and semisoft elastic modes. We prepare the self-assembled gel by dissolving a coil-side-group liquid-crystalline polymer-coil copolymer in a nematic liquid crystal. The gel has long network strands and a precisely tailored structure, making it ideal for studying nematic rubber elasticity. Under polarized optical microscopy we observe a striped texture that forms when gels uniformly aligned at 35 degrees C are cooled to room temperature. We model the instability using the molecular theory of nematic rubber elasticity, and the theory correctly captures the change in pitch length with sample thickness and polymer concentration. This buckling instability is a clear example of a low-energy deformation that arises in materials where polymer network strains are coupled to the director orientation. PMID:16712123

Verduzco, Rafael; Meng, Guangnan; Kornfield, Julia A; Meyer, Robert B

2006-04-14

181

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)

182

[Formulation of benzethonium chloride into gels].  

Science.gov (United States)

This study is focused on the preparation of gels with antimicrobial effects. A quaternary ammonium salt, benzethonium chloride, in a concentration of 0.01-0.5% (w/w) was employed as the drug. The humectant employed was propylene glycol in concentrations of 5% and 10% (w/w). Two types of polymers, chitosan and hydroxyethyl cellulose, in the same concentrations of 2.5% (w/w), were used for gel preparation. Finally the flow properties, rheological parameters and pH values of the gels were evaluated. Based on the obtained results, the samples of the gels prepared on the basis of chitosan and hydroxyethyl cellulose, which have the following optimum composition shown below, were found: 2,5% (w/w) CHIT + 0,5% (w/w) BZCl + 10% (w/w) PG; 2,5% (w/w) HEC + 0,5% (w/w) BZCl + 5% (w/w) PG. PMID:25115665

Cižmárik, Jozef; Vitková, Zuzana; Herdová, Petra; Kodadová, Alexandra; Vími, Daniel

2014-06-01

183

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

184

Procedure to prepare transparent silica gels  

Science.gov (United States)

This invention relates to the production of silica gels and in particular to a process for the preparation of silica gels which can be used as a crystal growth medium that simulates the convectionless environment of space to produce structurally perfect crystals. Modern utilizations of substances in electronics, such as radio transmitters and high frequency microphones, often require single crystals with controlled purity and structural perfection. The near convectionless environment of silica gel suppresses nucleation, thereby reducing the competitive nature of crystal growth. This competition limits the size and perfection of the crystal; and it is obviously desirable to suppress nucleation until, ideally, only one crystal grows in a predetermined location. A silica gel is not a completely convectionless environment like outer space, but is the closest known environment to that of outer space that can be created on Earth.

Barber, Patrick G. (inventor); Simpson, Norman R. (inventor)

1987-01-01

185

Radiation protection on polysaccharide solutions and gels  

Energy Technology Data Exchange (ETDEWEB)

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

Bazafkan, Sedighealsharieh

1996-12-31

186

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

187

Magnetic Hyperthermia in ferrofluid-gel composites  

Science.gov (United States)

Magnetic hyperthermia is the generation of heat by an external magnetic field using superparamagnetic nanoparticles. However, there are still questions concerning magnetic hyperthermia in tissue; in particular the confinement of the nanoparticles at mesoscopic scales. We used Agarose and Alginate gels as models for human tissue and embedded magnetic nanoparticles in them. We report the synthesis and characterization of dextran coated iron oxide (Fe3O4) nanoparticles. Characterization of these nanoparticles was done using X-ray diffraction, transmission electron microscopy, magnetometry, and hyperthermia measurements. Temperature dependent susceptibility measurements reveal a sharp anomaly in the ferrofluid sample at the freezing temperature. This is conspicuously absent in the ferrofluid-gel composites. Heat generation studies on these superparamagnetic gel-composites revealed a larger heat production in the ferrofluids(˜4W/g) as compared to the gels(˜1W/g), which we attribute to a reduction in Brownian relaxation for the nanoparticles embedded in Agarose and Alginate.

Nemala, Humeshkar; Wadehra, Anshu; Dixit, Ambesh; Regmi, Rajesh; Vaishnava, Prem; Lawes, Gavin; Naik, Ratna

2012-02-01

188

Pressure dependent phase behavior of polymer gels  

Energy Technology Data Exchange (ETDEWEB)

The structure of temperature- and pressure-sensitive poly(N-isopropylacrylamide) (PNIPA) and poly(N-isopropylacrylamide-co-acrylic acid) (PNIPA/AAc) gels has been investigated by small-angle neutron scattering as a function of temperature, T, and hydrostatic pressure, P. At low temperatures below the LCST of PNIPA in water and at atmospheric pressure, the structure of gels was described by an Ornstein-Zernike (Lorentz) function. However, by increasing P, a squared-Lorentz component appeared and became dominant, indicating an increase of inhomogeneities. At 45 .deg. C, the inhomogeneities in PNIPA gel became la rgest at P 100 MPa. PNIPA/AAc gels, on the other hand, exhibited a re-entrant scattering peak at P 100 MPa. These reentrant behaviors are explained with pressure-dependence hydrophobic interaction of PNIPA in water.

Shibayama, Mitsuhiro [Institute for Solid State Physics, The University of Tokyo, Tokai (Japan)

2005-07-01

189

Pressure dependent phase behavior of polymer gels  

International Nuclear Information System (INIS)

The structure of temperature- and pressure-sensitive poly(N-isopropylacrylamide) (PNIPA) and poly(N-isopropylacrylamide-co-acrylic acid) (PNIPA/AAc) gels has been investigated by small-angle neutron scattering as a function of temperature, T, and hydrostatic pressure, P. At low temperatures below the LCST of PNIPA in water and at atmospheric pressure, the structure of gels was described by an Ornstein-Zernike (Lorentz) function. However, by increasing P, a squared-Lorentz component appeared and became dominant, indicating an increase of inhomogeneities. At 45 .deg. C, the inhomogeneities in PNIPA gel became la rgest at P 100 MPa. PNIPA/AAc gels, on the other hand, exhibited a re-entrant scattering peak at P 100 MPa. These reentrant behaviors are explained with pressure-dependence hydrophobic interaction of PNIPA in water

190

Colloidal gels under shear: Strain rate effects  

Science.gov (United States)

Attractive colloidal particles are trapped in metastable states such as colloidal gels at high attraction strengths and attractive glasses and high volume fractions. Under shear such states flow via a two step yielding process that relates to bond and cluster or cage breaking. We discuss the way the structural properties and related stress response are affected by the shear rate. At low rates colloidal gels yield during start-up shear essentially in a single step, exhibiting a single stress overshoot due to creation of compact flowing clusters. With increasing shear rate a second stress overshoot, linked with further cluster breaking up to individual particles, is becoming more pronounced. We further present the age dependence of the two step yielding and wall slip effects often taking place during rheological experiments of colloidal gels. The latter is related both with the shear rate dependent gel structure as well as the time evolution of the near wall structure.

Koumakis, N.; Ballesta, P.; Besseling, R.; Poon, W. C. K.; Brady, J. F.; Petekidis, G.

2013-02-01

191

Preparation of zirconium molybdate gel generator  

International Nuclear Information System (INIS)

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

192

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

International Nuclear Information System (INIS)

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

193

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-10-15

194

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

International Nuclear Information System (INIS)

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 currd 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.

195

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

196

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

197

Tissue-Simulating Gel For Medical Research  

Science.gov (United States)

Nonhardening, translucent gel more nearly simulates soft human or animal tissue. Modified to be softer or harder by altering proportions of ingredients. Fillers added to change electrical, mechanical, heat-conducting, or sound-conducting/scattering properties. Molded to any desired shape and has sufficient mechanical strength to maintain shape without supporting shell. Because of its thermal stability, gel especially useful for investigation of hyperthermia as treatment for cancer.

Companion, John A.

1992-01-01

198

Brillouin scattering from cross-linked gels  

OpenAIRE

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

Mallamace, Francesco; Micali, Norberto; Vasi, Cirino; Bansil, Rama; Pajevic, Sinisa; Sciortino, Francesco

1992-01-01

199

Dynamic Scaling of Polymer Gels Comprising Nanoparticles  

OpenAIRE

We present dynamic light scattering (DLS) measurements of soft polymethyl-methacrylate (PMMA) and polyacrylamide(PA) polymer gels prepared with trapped bodies (latex spheres or maghemite nanoparticles). We show that the anomalous diffusivity of the trapped particles can be analyzed in terms of a fractal Gaussian network gel model for the entire time range probed by DLS technique. This model is a generalization of the Rouse model for linear chains extended for structures with...

Teixeira, Alvaro V. N. C.; Geissler, Erik; Licinio, Pedro

2014-01-01

200

Method of manufacturino spherical gel particles  

International Nuclear Information System (INIS)

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

201

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

202

Controlling the Morphology of Carbon Gels  

OpenAIRE

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

Mukai, R. S.

2012-01-01

203

Conducting Polymer Electrodes for Gel Electrophoresis  

OpenAIRE

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

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

2014-01-01

204

Thermodynamics and hydrodynamics of chemical gels  

OpenAIRE

We have developed a framework of thermodynamics and hydrodynamics of chemically crosslinked gels. Our framework of thermodynamics is analogous to that of binary fluid mixtures, except that the former includes a variable describing the deformation of the solid portion (network) of gels. The framework of the hydrodynamics is based on the theory of hydrodynamics of systems with broken symmetry and on the assumption of local equilibrium. In the present framework we assume that there is no plastic...

Sekimoto, K.

1991-01-01

205

Nanocrystalline Pentaerythritoltetranitrate using Sol-Gel Process  

OpenAIRE

The secondary explosives developed with reduced particle size tend to be more insensitive for mechanical stimuli and may release energy with faster rate and gaining more importance nowadays. Therefore, aiming to reduce the particle size of one of the popular explosives, viz., pentaerythritoltetranitrate (PETN) to the nanometer range, a method for preparation of nanocrystalline PETN in the silica (SiO2) gel matrix using sol-gel process has been demonstrated. The PETN-SiO2 xerogels were prepare...

Ingale, S. V.; Wagh, P. B.; Sastry, P. U.; Patra, A. K.; Tewari, R.; Singh, I. K.; Phapale, S. B.; Wasnik, R. D.; Subhananda Rao, A.; Gupta, Satish C.

2011-01-01

206

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

Energy Technology Data Exchange (ETDEWEB)

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

Deroin, Ph

2004-11-01

207

Gel displays based on the transparent to cloudy transition in polymer gels  

Science.gov (United States)

Gel displays based on transparent to cloudy transition in polymer gels have been synthesized. The central idea is to precisely control the local properties of the one gel surface by incorporating different materials onto the given areas selected with a mask. Specifically, a N-isopropylacylamide gel has been deposited on the surface of an acrylamide gel. The acrylamide gel has no transparent to cloudy transition in the range from room temperature to 50 ^0C, while the NIPA gel has such a transition at 34 ^0C. As a result, the pattern of the NIPA deposited area can be either visible or invisible by simply switching temperature above or below the low critical solution temperature (LCST) of the NIPA gel. Preliminary results of electric-current-controlled transparent to cloudy transition in the NIPA gel will be also presented. set of curly braces; then put the associated URL in the set. The command may go anywhere in the abstract. the text in the first curly braces will show the printed version.

Zheng, Yindong; Wang, Changjie; Hu, Zhibing

1998-10-01

208

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

Scientific Electronic Library Online (English)

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

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

209

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

210

GelClust: a software tool for gel electrophoresis images analysis and dendrogram generation.  

Science.gov (United States)

This paper presents GelClust, a new software that is designed for processing gel electrophoresis images and generating the corresponding phylogenetic trees. Unlike the most of commercial and non-commercial related softwares, we found that GelClust is very user-friendly and guides the user from image toward dendrogram through seven simple steps. Furthermore, the software, which is implemented in C# programming language under Windows operating system, is more accurate than similar software regarding image processing and is the only software able to detect and correct gel 'smile' effects completely automatically. These claims are supported with experiments. PMID:23727299

Khakabimamaghani, Sahand; Najafi, Ali; Ranjbar, Reza; Raam, Monireh

2013-08-01

211

The fundamental radiation properties of normoxic polymer gel dosimeters: a comparison between a methacrylic acid based gel and acrylamide based gels  

Energy Technology Data Exchange (ETDEWEB)

Polymer gel dosimeters offer a wide range of applications in the three-dimensional verification of complex dose distributions such as in intensity-modulated radiotherapy. One of the major difficulties with polymer gel dosimeters is their sensitivity to oxygen, as oxygen inhibits the radiation-induced polymerization reaction. For several years, oxygen was removed from the gels by bubbling the sol with inert gases for several hours during the gel fabrication. Also, the gel had to be poured in containers with low oxygen permeability and solubility. Recently, it was found that these technical difficulties can easily be solved by adding an antioxidant to the gel. These gels are called 'normoxic' gels as they can be produced under normal atmospheric conditions. In this study several properties of polymer gel dosimeters have been investigated: the dose sensitivity, the temporal and spatial stability of the gel, the sensitivity of the dose response to temperature during irradiation and during MR imaging, the energy dependence and the dose-rate dependence. This study reveals that the normoxic polymer gel dosimeter based on methacrylic acid (nMAG) studied in this work has inferior radiation properties as compared to the polyacrylamide gelatine (PAG) gel dosimeters. It is shown that from the three different gel dosimeters investigated in this study, the nPAG gel dosimeter results in a less sensitive gel dosimeter but with superior radiation properties as compared to the nMAG gel dosimeter. The importance of investigating relevant radiation properties of gel dosimeters apart from the radiation sensitivity-prior to their use for dosimetric validation experiments-is illustrated and emphasized throughout this study. Other combinations of monomer and gelling agent may result in more reliable normoxic polymer gel dosimeters.

Deene, Y de [Radiotherapy and Nuclear Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Gent (Belgium); MR Department, Ghent University Hospital, De Pintelaan 185, 9000 Gent (Belgium); Vergote, K [Radiotherapy and Nuclear Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Gent (Belgium); Claeys, C [Radiotherapy and Nuclear Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Gent (Belgium); Wagter, C De [Radiotherapy and Nuclear Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Gent (Belgium)

2006-02-07

212

Swelling instabilities in patterned, microscale gels  

Science.gov (United States)

Hydrogels facilitate reconfigurable structures with response integrated at the material level. Response is engendered by a competing mechanism: the elasticity of the network ounterbalances expansion by the solvent. If the strength of expansion can be controlled by an environmental cue, the hydrogel can be adjusted in situ. The equilibrium state occurs when the osmotic stress exerted by the solvent in the gel equals the osmotic pressure of the solvent outside the gel. For a free structure, the equilibrium state corresponds to homogenous swelling. If a free surface of the gel is mechanically constrained, however, the dimensions available for the relief of the osmotic stress are reduced, resulting in non-uniform or inhomogeneous swelling. In this study, we demonstrate how mechanical constraints impose differential gel swelling and buckling in patterned gels. Depending on the initial geometry of the constrained gel, three general modes of swelling-induced deformation can be observed: lateral differential swelling, bulk sinusoidal buckling, and surface wrinkling. Through confocal microscopy and 3D image rendering, the mechanics of swelling has been evaluated in the context of linear elasticity theory.

Toomey, Ryan; Dupont, Samuel

2012-02-01

213

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

Energy Technology Data Exchange (ETDEWEB)

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

Ricol, S.

1995-10-05

214

Optimized MR imaging for polyacrylamide gel dosimetry  

International Nuclear Information System (INIS)

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

215

Treatment of osteochondral injuries with platelet gel  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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

216

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)

217

Fricke xylenol gel energy dependence  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-01

218

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.)

219

Uncertainty in 3D gel dosimetry  

Science.gov (United States)

Three-dimensional (3D) gel dosimetry has a unique role to play in safeguarding conformal radiotherapy treatments as the technique can cover the full treatment chain and provides the radiation oncologist with the integrated dose distribution in 3D. It can also be applied to benchmark new treatment strategies such as image guided and tracking radiotherapy techniques. A major obstacle that has hindered the wider dissemination of gel dosimetry in radiotherapy centres is a lack of confidence in the reliability of the measured dose distribution. Uncertainties in 3D dosimeters are attributed to both dosimeter properties and scanning performance. In polymer gel dosimetry with MRI readout, discrepancies in dose response of large polymer gel dosimeters versus small calibration phantoms have been reported which can lead to significant inaccuracies in the dose maps. The sources of error in polymer gel dosimetry with MRI readout are well understood and it has been demonstrated that with a carefully designed scanning protocol, the overall uncertainty in absolute dose that can currently be obtained falls within 5% on an individual voxel basis, for a minimum voxel size of 5 mm3. However, several research groups have chosen to use polymer gel dosimetry in a relative manner by normalizing the dose distribution towards an internal reference dose within the gel dosimeter phantom. 3D dosimetry with optical scanning has also been mostly applied in a relative way, although in principle absolute calibration is possible. As the optical absorption in 3D dosimeters is less dependent on temperature it can be expected that the achievable accuracy is higher with optical CT. The precision in optical scanning of 3D dosimeters depends to a large extend on the performance of the detector. 3D dosimetry with X-ray CT readout is a low contrast imaging modality for polymer gel dosimetry. Sources of error in x-ray CT polymer gel dosimetry (XCT) are currently under investigation and include inherent limitations in dosimeter homogeneity, imaging performance, and errors induced through post-acquisition processing. This overview highlights a number of aspects relating to uncertainties in polymer gel dosimetry.

De Deene, Yves; Jirasek, Andrew

2015-01-01

220

Measuring Dilution of Microbicide Gels with Optical Imaging  

OpenAIRE

We present a novel approach for measuring topical microbicide gel dilution using optical imaging. The approach compares gel thickness measurements from fluorimetry and multiplexed low coherence interferometry in order to calculate dilution of a gel. As a microbicide gel becomes diluted at fixed thickness, its mLCI thickness measurement remains constant, while the fluorimetry signal decreases in intensity. The difference between the two measurements is related to the extent of gel dilution. Th...

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

2013-01-01

221

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

222

Carbonate hydroxyapatite gel monolith formation and drying.  

Science.gov (United States)

The effect of carbonate in reducing the crystal size of precipitated hydroxyapatite by approximately an order of magnitude has not been used previously in the preparation of gel monoliths for the fabrication of carbonate hydroxyapatite ceramics. The aim of this study was to devise a method whereby gel monoliths of carbonate hydroxyapatite could be repeatably produced without cracking. A precipitation reaction was used for the preparation of carbonate hydroxyapatities with carbonate contents of 5.8 and 7.8 wt%. Biaxial vacuum filtration was used to form disc shaped monoliths. The rate of filtration of a 7.8 wt% carbonate hydroxyapatite sol was measured throughout the gelation process. Gel monoliths were dried slowly in air and the mass and dimensions of the gel were recorded once approximately every 24 hours. Using this data, the permeability, water volume fraction with time, rate of water loss, gelation point and gel density were determined. The pore size distribution was measured using mercury porosimetry for a carbonate apatite gel and a pressed powder pellet of a commercial hydroxyapatite. In tact monoliths were formed with masses up to 9.9 g. It was found that gelation behaviour was independent of monolith size and carbonate content and the final green density of all monoliths was 37%. Gelation was found to occur at 50-55 vol% water. Gel monoliths were found to have a monomodal pore size distribution with a mean pore size of 9.1 nm, whereas a pressed pellet of hydroxyapatite had a bimodal pore size distribution. PMID:8761520

Barralet, J E; Best, S M; Bonfield, W

1996-01-01

223

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

Science.gov (United States)

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

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

2013-06-01

224

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

225

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)

226

Missing values in gel-based proteomics.  

Science.gov (United States)

Gel-based proteomics is a widely applied technique to measure abundances of proteins in various biological systems. Comparison of two or more biological groups involves matching of 2-D gels. Depending on the software, this can result in spots showing missing values on several gels. Most studies ignore this fact or substitute all missing data by zero. Since a couple of years, scientists have realized that this is not the optimal way of analyzing their data and several studies were published presenting methods of imputing missing proteomics data. Most of these methods have already been applied to microarray data before; the phenomenon of missing data is well known in this field, too. With this review, we intend to further raise awareness of the problem of missing values in gel-based proteomics. We summarize reasons for missing values and explore their distribution in data sets. We also provide a comparison and evaluation of hitherto proposed imputation methods for gel-based proteomics data. PMID:20077407

Albrecht, Daniela; Kniemeyer, Olaf; Brakhage, Axel A; Guthke, Reinhard

2010-03-01

227

PRONIOSOMAL GEL OF FLURBIPROFEN: FORMULATION AND EVALUATION  

Directory of Open Access Journals (Sweden)

Full Text Available 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 transparent, translucent or white semisolid gel texture. Due to the limited solvent system present, the proniosomes formed were the mixture of many phases of liquid crystal, viz. lamellar, hexagonal and cubic phase liquid crystals. The potential of proniosomes as a transdermal drug delivery system for flurbiprofen was investigated by encapsulating the drug in various formulations of proniosomal gel composed of various ratios of sorbitan fatty acid esters, cholesterol, prepared by coacervation-phase separation method. The formulated systems were characterized in vitro for size, vesicle count, drug entrapment, drug release profiles and vesicular stability at different storage conditions. Stability studies for proniosomal gel were carried out for 4 weeks. The method of proniosome loading resulted in an encapsulation yield of 30.6 – 75.4%. Proniosomes were characterised by transmission electron microscopy. In vitro studies showed prolonged release of entrapped flurbiprofen. At refrigerated conditions, higher drug retention was observed. It is evident from this study that proniosomes are a promising prolonged delivery system for captopril and have reasonably good stability characteristics.

Sunil Kumar

2012-01-01

228

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

229

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)

230

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

231

Sol-gel based biofuel cell architectures  

Science.gov (United States)

Sol-gel based biofuel cell architectures were investigated and quantified for electrochemical performance. The flexible solution chemistry of the sol-gel process has been used to synthesize bio-hybrid materials in which a wide variety of biomolecules are encapsulated in a transparent, inorganic matrix. These biomolecules retain their characteristic reactivities and spectroscopic properties despite being immobilized in the pores of the inorganic matrix. Stability of the biomolecules is also improved because of the confinement in the rigid inorganic network. Sol-gel immobilization serves as the basis for the electrode architecture used in enzymatic biofuel cells. In this dissertation, the fabrication and characterization of an enzymatic glucoseoxygen biofuel cell that incorporates nanostructured silica sol-gel/carbon nanotube composite electrodes was evaluated. These novel electrodes combine the benefits of sol-gel encapsulation with the use of carbon nanotubes which provide enhanced electronic conduction pathways and increase the effective surface area of the electrode. With this immobilization approach, the silica sol-gel is sufficiently porous that both glucose and oxygen have access to enzymes and yet provide a protective cage that preserves biological structure and function, offers long-term stability and perhaps enables operation at elevated temperatures. In addition, direct electron transfer was exhibited by a nanostructured cathode. More notably, these nanostructured composites were developed for power generation. Analysis of electron transfer rates and enzyme kinetics were used to quantify encapsulation properties and explore potential opportunities for optimization. Another topic for biofuel cells is miniaturization. Through miniaturization, biofuel cell design and integration are major considerations for increasing power density and performance.

Lim, James Robert

232

Radiochromic gel dosemeter for three dimensional dosimetry  

International Nuclear Information System (INIS)

Conformal radiotherapy treatments require highly accurate three dimensional dose predictions for very intricate irradiation beam patterns applied to a complex target geometry, and there is a clear need for validating such dose computations over a range of typical geometries. Hence a dosimetric technique capable of accurate measurement of the spatial distribution, in three dimensions, of radiation dose in tissue equivalent materials is required. For this purpose several research groups have developed polymer gels with some success. However these materials are difficult to prepare and require relatively expensive and slow MRI or laser-based readout systems. These difficulties inspired the development of a simpler, more practical, dosemeter material suitable for three- dimensional dose measurements. This new dosemeter formulation is essentially a variant of the classic Fricke dosemeter and consists of ferrous ions in an acid environment plus a xylenol orange ion-indicator. Upon irradiation ferrous ions change to ferric by oxidation which causes the xylenol orange to turn purple. These changes in the optical density are spatially stabilised by means of a transparent gelatin gel. The optimal formulation of the ferrous xylenol gelatin (FXG) gel system for conformal radiotherapy planning has been established. The FXG dosemeter was characterised by comparison with both the standard Fricke solution and the older MRI Fricke gel method. Its dose response is linear over the rangeIts dose response is linear over the range 0.1-30 Gy and its radiation chemical yield is an order of magnitude higher than the G-value of the standard Fricke dosemeter, and about three times higher than that of a ferrous xylenol solution. The stability and reproducibility were also studied and found to be adequate for the application envisaged. In addition, the new gel proved to be much simpler, quicker, and cheaper to prepare than polymer gels using normal laboratory facilities. FXG is highly transparent over optical wavelengths and can be rapidly read out using a broad beam optical tomographic imaging technique. (author)

233

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)

234

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

OpenAIRE

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

Malyavskiy Nikolay Ivanovich; Pokidko Boris Vladimirovich

2012-01-01

235

Dynamic Light Scattering From Colloidal Gels  

Science.gov (United States)

We present a brief, preliminary account of the interpretation of dynamic light scattering from fractal colloidal gels. For small scattering angles, and for high initial colloid particle volume fractions, the correlation functions exhibit arrested decay, reflecting the non-ergodic nature of these systems and allowing us to directly determine the elastic modulus of the gels. For smaller initial volume fractions, the correlation functions decay completely. In all cases, the initial decay is not exponential, but is instead described by a stretched exponential. We summarize the principles of a model that accounts for these data and discuss the scaling behavior of the measured parameters.

Krall, A. H.; Weitz, David A.

1996-01-01

236

Elasticity of entangled polymer loops: Olympic gels  

OpenAIRE

In this note we present a scaling theory for the elasticity of olympic gels, i.e., gels where the elasticity is a consequence of topology only. It is shown that two deformation regimes exist. The first is the non affine deformation regime where the free energy scales linear with the deformation. In the large (affine) deformation regime the free energy is shown to scale as $F \\propto \\lambda^{5/2}$ where $\\lambda$ is the deformation ratio. Thus a highly non Hookian stress - s...

Vilgis, T. A.; Otto, M.

1997-01-01

237

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

238

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

239

Multiple-phase behavior and memory effect of polymer gel  

International Nuclear Information System (INIS)

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.)

240

Iron(II)- or vanadium(IV)-containing siliceous gels  

OpenAIRE

Iron(II)-containing SiO2 gels can be prepared by the hydrolysis and condensation of tetramethoxysilane in methanolic solutions of iron(II) chloride. These gels show an absorption at 1000 nm indicating the presence of iron(II). In opposition to that, iron(II) cannot be introduced into organically modified gels of the 3-glycidyloxypropyltrimethoxysilane type. Vanadium(IV) can be incorporated into both gels. Unlike the SiO2 gels, the organically modified gels are compact and elastic. The spectra...

Hutter, Frank; Schmidt, Helmut K.; Scholze, Horst

1986-01-01

241

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

242

Sol-gel additive for systems with inorganic binders  

Energy Technology Data Exchange (ETDEWEB)

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

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

1996-05-17

243

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

Energy Technology Data Exchange (ETDEWEB)

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.

Bosi, Stephen [Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006 (Australia); Naseri, Pourandokht [Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006 (Australia); Puran, Alicia [Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006 (Australia); Davies, Justin [Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006 (Australia); Baldock, Clive [Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006 (Australia)

2007-05-21

244

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

International Nuclear Information System (INIS)

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

245

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

246

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

247

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

248

Electrophoretic Porosimetry of Sol-Gels  

Science.gov (United States)

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

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

2000-01-01

249

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

250

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

251

Thermal Decomposition Characteristics of ADU Gel Spheres  

Energy Technology Data Exchange (ETDEWEB)

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 UO{sub 2} 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 (UO{sub 2} 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.

Jeong, Kyung Chai; Eom, Sung Ho; Kim, Yeon Ku; Kim, Young Min; Kim, Woong Ki; Kim, Bong Ku; Lee, Young Woo; Cho, Moon Seoung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-10-15

252

Electrochemical Growth Of Crystals In Gels  

Science.gov (United States)

Nucleation and growth rates readily controlled. Technique developed to grow crystals by controlling rate of transfer of one component into crystallization volume. Method involves electrochemically controlled generation of one of precipitation species, coupled with diffusion barrier. New procedure, developed in connection with formation of lead tin telluride by reaction in gels of metal ions with telluride ions.

Barber, Patrick G.; Coleman, James

1988-01-01

253

Kinetics of shear-induced gel deswelling/solvent release.  

Science.gov (United States)

The kinetics of shear-induced deswelling of gel particles based on synthetic (sodium polyacrylate) and natural (alginate) polymers was studied by rheo-optical technique. A swollen spherical gel particle of 100+/-50 microm diameter was placed in silicone oil and the evolution of the gel size as a function of time and shear rate was monitored. Different aqueous polymer solutions were used as synthetic gel solvent: polyvinylpyrrolidone, hydroxypropyl cellulose and glucose-based polymer. The interfacial tension (gel solvent)/(silicone oil), gel degree of swelling, solvent quality and viscosity are the main parameters influencing the kinetics of shear-induced gel deswelling. The kinetics of gel volume loss was approximated by a modified Weibull equation. PMID:16126296

Zeo, Undina; Tarabukina, Elena; Budtova, Tatiana

2005-11-01

254

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

255

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

Science.gov (United States)

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.

2011-10-01

256

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.

257

Effects of Gel Thickness on Microscopic Indentation Measurements of Gel Modulus  

OpenAIRE

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

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

2011-01-01

258

Polymer gel: Kinetic, dynamic studies and its applications as biomaterials  

Science.gov (United States)

The polymer gels especially hydrogels have a very special structure and useful features such as unusual volume phase transition, compatibility with biological systems, and sensitivity to environmental stimuli (temperature, pH value, electric field, light and more), which lead to many potential applications in physical and biochemical fields. This research includes: (1) the theoretical and experimental studies of polymer gels on swelling kinetics, spinodal decomposition, and solution convection in gel matrix; (2) applications of polymer gels in wound dressing, tissue-simulating optical phantom and gel display. The kinetics of gel swelling has been theoretically analyzed by considering coupled motions of both solvent and polymer network. Analytical solutions of the solvent and the network movement are derived from collective diffusion equations for a long cylindrical and a large disk gel. Kinetics of spinodal decomposition of N-isopropylacrylamide (NIPA) polymer gel is investigated using turbidity and ultrasonic techniques. By probing movement of domains, a possible time-dependent gel structure in the spinodal decomposition region is presented. Theoretical studies of solution convection in gel matrix have been done and more analysis on dimensionless parameters is provided. To enhance the drug uptake and release capacity of silicone rubber (SR), NIPA hydrogel particles have been incorporated into a SR membrane. This SR/NIPA composite gel has promising attributes for wound dressing and other uses. Tissue-simulating optical phantom has been synthesized and studied using NIPA solution trapped inside a hydrogel. Polymer gels with engineered surface patterns were implemented. NIPA gel deposited on the surface of an acrylamide gel can be used as responsive gel display. A dynamically measurement technique of local shear modulus and swelling ratio of gel is presented based on an engineered periodic surface pattern as square array.

Wang, Changjie

259

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

260

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

261

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

262

Effect of Electron beam on Prepared HAP-Gel Composition  

OpenAIRE

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 H...

Naima A El Gendy, Tawfik M. S.

2014-01-01

263

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

Scientific Electronic Library Online (English)

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

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

2191-21-01

264

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

Scientific Electronic Library Online (English)

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

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

265

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

International Nuclear Information System (INIS)

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

266

Formulation and method for preparing gels comprising hydrous cerium oxide  

Energy Technology Data Exchange (ETDEWEB)

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

267

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

268

21 CFR 520.1242f - Levamisole hydrochloride gel.  

Science.gov (United States)

...2010-04-01 false Levamisole hydrochloride gel. 520.1242f Section 520.1242f Food and...DRUGS § 520.1242f Levamisole hydrochloride gel. (a) Specifications. The drug is a gel containing 11.5 percent levamisole...

2010-04-01

269

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

270

i-Gel Supraglottic Airway for Inexperienced Anesthesia Residents  

OpenAIRE

i-gel (Intersurgical Ltd., Wokingham, UK) is a new supraglottic airway device with a cuff made of thermoplastic elastomer gel. We retrospectively studied easiness of insertion and troubles in ventilation when this device was used by less experienced anesthesiologists. Consecutive eleven cases undergoing surgery under general anesthesia were studied. i-gel ...

Hiroyuki Kobinata; Koshi Makita; Koichi Nakazawa; Tokujiro Uchida; Mariko Senda

2013-01-01

271

AMP-trapped alumina gel spheres for caesium separation  

International Nuclear Information System (INIS)

Gel Entrapment Technique (GET) was used to trap ammonium molybdo phosphate (AMP) in spherical alumina gel particles. The gel spheres prepared from a slurry of aluminium nitrate, AMP, hexamethylene tetramine (HMTA) and urea, were suitably processed. The distribution ratios of Cs+ on this material at various HNO3 concentrations were determined and absorption and elution characteristics were studied. (author)

272

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 ha...

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

2010-01-01

273

Nanoscale Silicon Dioxide Prepared by Sol-Gel Process  

Directory of Open Access Journals (Sweden)

Full Text Available Nanoscale silicon dioxide has been prepared with tetraethyl orthosilicate (TEOS by sol-gel process. The optimum process conditions have been obtained by investigating the effect of formulation, temperature, catalyst and etc. on its gel morphology, gel time, and particle size.

Hui Gao

2010-08-01

274

Nanoscale Silicon Dioxide Prepared by Sol-Gel Process  

OpenAIRE

Nanoscale silicon dioxide has been prepared with tetraethyl orthosilicate (TEOS) by sol-gel process. The optimum process conditions have been obtained by investigating the effect of formulation, temperature, catalyst and etc. on its gel morphology, gel time, and particle size.

Hui Gao; Junling Yang

2010-01-01

275

Selecting and Effectively Using Sports Drinks, Carbohydrate Gels and Energy Bars  

Science.gov (United States)

... important factor in maintaining proper hydration levels. CARBOHYDRATE GELS Carbohydrate gels come in small, single- A COMPLETE ... in those not accustomed to this stimulant. CARBOHYDRATE GEL CONSIDERATIONS: • Most carb gel packs contain 100 calories, ...

276

77 FR 26556 - Determination of Regulatory Review Period for Purposes of Patent Extension; EQUIDONE GEL  

Science.gov (United States)

...Purposes of Patent Extension; EQUIDONE GEL AGENCY: Food and Drug Administration...the regulatory review period for EQUIDONE GEL and is publishing this notice of that determination...marketing the animal drug product EQUIDONE GEL (domperidone). EQUIDONE GEL is...

2012-05-04

277

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)

278

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)

279

Ultrasound evaluation of polymer gel dosimeters  

International Nuclear Information System (INIS)

A new method for the evaluation of radiotherapy 3D polymer gel dosimeters has been developed using ultrasound to assess the significant structural changes that occur following irradiation of the dosimeters. The ultrasonic parameters of acoustic speed of propagation, attenuation and transmitted signal intensity were measured as a function of absorbed radiation dose. The dose sensitivities for each parameter were determined as 1.8x10-'4 s m-1 Gy-1, 3.9 dB m-1 Gy-1 and 3.2 V-1 Gy-1 respectively. All parameters displayed a strong variation with absorbed dose that continued beyond absorbed doses of 15 Gy. The ultrasonic measurements demonstrated a significantly larger dynamic range in dose response curves than that achieved with previously published magnetic resonance imaging (MRI) dose response data. It is concluded that ultrasound shows great potential as a technique for the evaluation of polymer gel dosimeters. (author)

280

Instabilities in droplets spreading on gels  

CERN Document Server

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

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

2006-01-01

281

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

282

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.)

283

Switching friction with thermal- responsive gels.  

Science.gov (United States)

The thermosensitive graphene oxide (GO)/poly(N-isopropyl acrylamide) (pNIPAM) composite hydrogels are prepared, and their tribological properties in response to external stimuli are evaluated. The frictional coefficient of the hydrogels is closely related to the gel composition and ambient temperature. When the gel is in swelling state below the low critical solution temperature (LCST), it shows ultra-low friction and exhibits high friction at a shrunk state above the LCST. The huge difference of frictional coefficient under two states can be reversibly switched many times by altering the temperature. The incorporation of a nonthermal sensitive monomer into pNIPAM could change the LCST and thus the transformation point of frictional coefficient can be altered. These reversible and tunable frictional hydrogels have potential application in the design of intelligent control equipment. PMID:24249089

Wu, Yang; Cai, Meirong; Pei, Xiaowei; Liang, Yongmin; Zhou, Feng

2013-11-01

284

Ceramica 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 GmbH assisted by Kraftwerk Union A.G., both West Germany, to NUCLEBRAS, where it was jointly adapted to produce microspheres suitable for pressing. As a result, there are now available various possibilities to produce ceramic spheres with different characteristics that can be used in different applications. Examples of these characteristics are the range of gel sphere diameters (200 to 5000 ?mm) and the value of the specific surface (about 50m2/g for calcined (Th, U)O2 and potentially higher than m2/g for other ceramic materials) (Author)

285

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

286

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

287

3D dosimetry fundamentals: gels and plastics  

International Nuclear Information System (INIS)

Many different materials have been developed for 3D radiation dosimetry since the Fricke gel dosimeter was first proposed in 1984. This paper is intended as an entry point into these materials where we provide an overview of the basic principles for the most explored materials. References to appropriate sources are provided such that the reader interested in more details can quickly find relevant information.

288

Compressive consolidation of strongly aggregated particle gels  

OpenAIRE

The compressive yield stress of particle gels shows a highly nonlinear dependence on the packing fraction. We have studied continuous compression processes, and discussed the packing fraction dependence with the particle scale rearrangements. The 2D simulation of uniaxial compression was applied to fractal networks, and the required compressive stresses were evaluated for a wide range of packing fractions that approached close packing. The compression acts to reduce the size...

Seto, Ryohei; Botet, Robert; Meireles, Martine; Auernhammer, Gu?nter K.; Cabane, Bernard

2013-01-01

289

Simple lattice model for biological gels  

OpenAIRE

We construct a three-dimensional lattice model for biological gels in which straight lines of bonds correspond to filamentous semi-flexible polymers and lattice sites, which are exactly four-fold coordinated, to crosslinks. With only stretching central forces between nearest neighbors, this lattice is sub-isostatic with an extensive number of zero modes; but all of its elastic constants are nonzero, and its elastic response is affine. Removal of bonds with probability $1-p$ ...

Stenull, Olaf; Lubensky, T. C.

2011-01-01

290

Silver Staining of 2D Electrophoresis Gels  

OpenAIRE

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

Rabilloud, Thierry

2012-01-01

291

Ring-Resonator/Sol-Gel Interferometric Immunosensor  

Science.gov (United States)

A proposed biosensing system would be based on a combination of (1) a sensing volume containing antibodies immobilized in a sol-gel matrix and (2) an optical interferometer having a ring resonator configuration. The antibodies would be specific to an antigen species that one seeks to detect. In the ring resonator of the proposed system, light would make multiple passes through the sensing volume, affording greater interaction length and, hence, greater antibody- detection sensitivity.

Bearman, Gregory; Cohen, David

2007-01-01

292

Scaling Behaviors and Mechanical Properties of Polymer Gels  

Science.gov (United States)

Polymer gels undergo a volume phase transition in solvent in response to an infinitesimal environmental change. This remarkable phenomenon has resulted in many potential applications of polymer gels. The understanding of its mechanical properties has both scientific and technological importance. For this purpose, we have developed a novel method for measuring Poisson's ratio, which is one of the most important parameters determining the mechanical property of gels. Using this method, Poisson's ratio in N-isopropyacryl -amide (NIPA) and polyacrylamide (PAAM) gels has been studied. We obtained that Poisson's ratio goes through a negative dip in both neutral and ionic NIPA gels, but positive in the PAAM gels. It was found that the scaling exponent delta depends on the details of chemical ingredients and polymerization process. In the salt solution, the delta depends on both the network ionization and the solvent salt concentration. The study of acoustic attenuation and velocity of NIPA gels reveals the dynamic scaling behavior of NIPA gels near the transition point. It has been found that there are four different pattern regions on the surface of constrained gel films depending on the temperature (or acetone concentration) and ionic strength of the sample, these patterns are associated with the mechanical instability of gel surface. The work presented in this dissertation will help ones both in the theoretical understanding and practical application of the gel system.

Li, Chunfang

293

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

294

Luminescence decay analysis of doped sol-gel films  

Science.gov (United States)

Fluorescence decay of the well-known fluorophore, ruthenium (II) 4,7-diphenyl-1,10-phenanthroline perchlorate, has been studied in a series of sol-gel matrices, including non-polar methyltrimethoxysilane (MTMS) and highly polar tetraethylorthosilicate (TEOS)-based gels. Systematic changes in composition and processing techniques have been fabricated to examine the structural properties of sol-gel silicates for possible oxygen sensor supports. Measurements were performed using both brush-coated and spin-coated sol- gel thin films as well as sol-gel monoliths. Gel compositions consisted of either 100% MTMS, 100% TEOS, or a 1:1 molar ratio of MTMS to TEOS. Quenching behavior was analyzed as a function of varying sol-gel composition, processing technique (spin-coated, brush-coated, etc.), and fluorophore concentration. The use of modeling techniques were employed to enable determination of possible singe or multi-exponential decay behavior in different sol-gel samples. Causes for the variations in quenching properties as a function of gel composition and processing technique were explained by a two-domain model. In addition, phase fluorimetric analysis was conducted on all doped sol-gel samples to determine the change in phase between the quenched and unquenched states of the films. Direct experimental phase data was compared to phase results calculated from the experimental lifetime data in order to examine the accuracy of the luminescence decay times. Possible design of sol-gel supports for oxygen sensors was also discussed.

Murtagh, Michael T.; Krihak, Michael; Kwon, Hyeog-Chan; Shahriari, Mahmoud R.

1996-12-01

295

Fabrication, modeling and optimization of an ionic polymer gel actuator  

International Nuclear Information System (INIS)

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

296

G-Quadruplex Guanosine Gels and Single Walled Carbon Nanotubes  

Directory of Open Access Journals (Sweden)

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

Yuehua Yu

2013-12-01

297

Dynamics of sodium dodecyl sulfate micelles in polyacrylamide gels  

Science.gov (United States)

Hydrophilic polyacrylamide gels exhibit interesting elastic properties which can be probed by dynamic light scattering. The dynamic structure factors of such gels and of gels which were polymerized in the presence of high concentrations of sodium dodecyl sulfate (SDS) micelles were measured. It was found that the gels containing SDS decay initially according to a stretched exponential, followed by a long time simple exponential decay, whereas the pure gel decay is single exponential at all times. Furthermore, the initial decays of all SDS/gel systems are nearly identical, while the long-time decays are clearly a function of SDS concentration. We interpret the initial decay as associated with local polyacrylamide elasticity unaffected by the presence of the micelles and the long time decays as characteristic of gel modes slowed by the various densities of SDS micelles.

Reyna, A.; Liu, Yingjie; van Winkle, David H.

1998-03-01

298

An MRI phantom using carrageenan gel  

Energy Technology Data Exchange (ETDEWEB)

We have developed a new solid type carrageenan gel phantom. The ingredients of the new gel are carrageenan, manganese chloride, sodium chloride, sodium azide, and water. The gel phantom has sufficient strength to form a torso without the use of a reinforcing agent. A phantom of a desired shape can be created by pouring a hot solution of carrageenan into a mold. The phantom can then be cut easily with a knife and trimmed into the desired shape. The recommended concentrations of the ingredients are; 5 wt% carrageenan, 0.2 mM MnCl{sub 2}, 0.19 wt% NaCl, 0.1 wt% NaN{sub 3}, with the remainder being water. T{sub 2} and T{sub 1} of this phantom at 1.5 T are 84.9 ms and 429 ms respectively. The conductivity and relative dielectric constant at 63.8 MHz are 0.769 S/m and 81.4 respectively. (author)

Kato, Hirokazu; Kuroda, Masahiro; Yoshimura, Koichi; Kawasaki, Shoji; Yamamoto, Naotake; Tanaka, Akio; Hiraki, Yoshio [Okayama Univ. (Japan). School of Medicine; Uchida, Nobue; Sugimura, Kazuro

2000-12-01

299

Relaxation Behavior of Acrylic Triblock Copolymer Gels  

Science.gov (United States)

When dissolved in alcohol, poly(methyl methacrylate)-poly(n-butyl actylate)-poly(methyl methacrylate) triblock copolymers form physical gels by the aggregation of the PMMA blocks into sperhical domains. Shear rheometry was used to study the relaxation behavior of gels formed in 2-ethylhexanol with different block lengths and polymer concentrations. Master curves were used to determine relaxation times at different temperatures. The relaxation time given by zero shear viscosity divided by the plateau modulus were in good agreement with the low frequency limit for a system with a single relaxation time. By increasing the PMMA block length from 9k to 25k or increasing polymer concentration from 5 to 30 vol. percent, the relaxation time increases by five orders of magnitude at a given temperature. The effect of block length and concentration on the aggregation number of the PMMA domains was determined by small angle X-ray scattering. Relaxation behavior is of practical importance because these gels are used for thermoreversible gelcasting of ceramics.

Seitz, Michelle; Shull, Kenneth; Burghardt, Wesley

2006-03-01

300

Magnetization transfer imaging for polymer gel dosimetry  

International Nuclear Information System (INIS)

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)

301

Theory of capillary formation in alginate gels  

Science.gov (United States)

The formation of capillaries in alginate gel is a dissipative process coupled with hydrodynamic flow in the immediate neighborhood of the front of gel formation. The hydrodynamic flow is due to the contraction of the alginate chains resulting from the crosslinking reaction. As shown earlier, capillary formation only occurs above a critical value of the contraction velocity. In this paper a complete theoretical model of the ratio of the actual to the critical contraction velocity is presented. The theoretical predictions are compared with experimental data for the formation of copper alginate gel from solutions of sodium alginate and copper dichloride. The ratio of the actual to the critical contraction velocity is described as a function of the bulk concentrations, the diffusion coefficients, the properties of the alginate molecules and the rate constant of copper alginate complex formation. For capillary formation to occur, the rate constant must be neither too small nor too large. In agreement with experimental data the model predicts that capillary formation is restricted to a finite time interval and will not take place if the copper concentration is too low or the alginate concentration is too high.

Treml, H.; Woelki, S.; Kohler, H.-H.

2003-09-01

302

Micro-size polyacrylamide gel electrophoresis system  

Science.gov (United States)

The development and characterization of a micro-size two-dimensional polyacrylamide gel electrophoresis system is described. Some of the techniques which have evolved with use of the system are also discussed. This apparatus has unique features which provide advantages over other small scale units. Up to ten first- and second-dimension gels can be processed simultaneously with excellent resolution of protein regions. Consistent reproducibility is possible from protein samples as small as 400 ng and individual protein regions as small as 1 pg can be visualized by silver staining of the two-dimensional gels. Similar sensitivities are achieved in autoradiographs of 3H-labeled proteins extracted from the nuclei of cultured cells. The application of this system in conjunction with flow cytometric examination of nuclear DNA and electrostatic cell sorting of specific cell nuclei to provide homogeneous sample populations, allows subtle variations in isotope incorporation in proteins to be detected; whereas many times in generalized tissue samples these changes are masked. Also, these techniques elucidate the effects of external stimuli (chemicals, drugs, or environment) on protein synthesis and phosphorylation for analyses and comparison. Fabrication drawings are available upon request.

Hinson, W. G.; Pipkin, J. L.; Anson, J. F.; Casciano, D. A.; Burns, E. R.

1987-09-01

303

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

304

PRONIOSOMAL GEL OF FLURBIPROFEN: FORMULATION AND EVALUATION  

Directory of Open Access Journals (Sweden)

Full Text Available 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. Due to the limited solvent system present, the proniosomes formed were the mixture of many phases of liquid crystal, viz. lamellar, hexagonal and cubic phase liquid crystals. The potential of proniosomes as a transdermal drug delivery system of flurbiprofen was investigated by encapsulating the drug in various formulations of proniosomal gel composed of various ratios of sorbitan fatty acid esters, cholesterol, prepared by coacervation-phase separation method. The formulated systems were characterized in vitro for size, vesicle count, drug entrapment, drug release profiles and vesicular stability at different storage conditions. Stability studies for proniosomal gel were carried out for 4 weeks. The method of proniosome loading resulted in an encapsulation yield of 30.6 – 75.4%. Invitro studies showed prolonged release of entrapped flurbiprofen. At refrigerated conditions, higher drug retention was observed. It is evident from this study that proniosomes are a promising prolonged delivery system for flurbiprofen and have reasonably good stability characteristics.

Prajapati SK

2012-01-01

305

Decontamination using chemical gels, electrolytical swab, abrasives  

International Nuclear Information System (INIS)

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

306

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

307

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

308

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese As Lentiviroses de Pequenos Ruminantes (LVPR) incluem a Maedi-Visna (MV) em ovinos e a Artrite Encefalite Caprina (CAE). Essas enfermidades estão difundidas no mundo e são responsáveis por grandes perdas na produtividade destes animais. Os LVPR são vírus RNA da 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

309

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

310

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

311

Intercorrência entre leucose enzoótica e brucelose em búfalos (Bubalus bubalis em sistema de produção extensivo Intercurrence of enzootic leucosis and brucellosis in buffaloes (Bubalus bubalis in extensive production system  

Directory of Open Access Journals (Sweden)

Full Text Available Objetivou-se com este estudo avaliar a intercorrência entre leucose enzoótica e brucelose em búfalos (Bubalus bubalis em sistema de produção extensivo, pelo estabelecimento da prevalência de bubalinos reagentes às provas diagnósticas específicas. Foram analisados sorologicamente 232 animais, pela técnica de imunodifusão dupla em gel de agarose para diagnóstico de leucose enzoótica e o teste do antígeno acidificado tamponado, seguida pelos testes confirmatórios 2-mercaptoetanol e soroaglutinação lenta em tubos para diagnóstico de brucelose. As prevalências de búfalos que apresentaram positividade para leucose e brucelose foram 4,21% (10/232 e 5,18% (12/232, respectivamente. Os resultados obtidos nesta pesquisa permitiram concluir que as infecções estudadas encontram-se presentes na população avaliada, entretanto, com baixa prevalência e sem dependência de ocorrência entre ambas.This study was carried out to evaluate the intercurrence of brucellosis and enzootic leucosis in buffaloes in extensive production system by establishing the prevalence of reagent buffaloes for specific diagnostic tests. We analyzed 232 animals serologically by the technique of double immunodiffusion in agarose gel (AGID for diagnostic of leucosis and the tampon acidified antigen (TAA test, followed by confirmatory tests of 2-mercaptoethanol (2-ME and slow serum agglutination (SSA in tubes for diagnostic of brucellosis. The prevalence of buffaloes that were positive for leucosis and brucellosis tests were 4.21% (10/232 and 5.18%(12/232 respectively. The results of this investigation indicated that the diseases occur in the population studied, however, with low prevalence and without depending on the occurrence of both.

Nancyleni P Chaves

2012-02-01

312

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

313

Comparative study of sol-gel-hydrothermal and sol-gel synthesis of titania-silica composite nanoparticles  

International Nuclear Information System (INIS)

Titania-silica composite nanoparticles were prepared by sol-gel-hydrothermal and sol-gel routes, respectively, and their physico-chemical and photocatalytic properties were compared. The results of XRD, TEM and BET surface areas showed that sol-gel-hydrothermal route led to anatase titania-silica composite nanoparticles with large specific surface area, but the sol-gel route tended to form mixture of anatase and rutile. The composite nanoparticles prepared by sol-gel-hydrothermal route had better thermal stability against phase transformation from anatase to rutile, agglomeration and particle growth than those prepared by sol-gel route. On the basis of XRD, FT-IR, XPS and 29Si MAS-NMR, a strong interaction was found between SiO2 and TiO2, and Ti-O-Si bonds formed during both the two routes. But more Ti-O-Si bonds formed in the composite nanoparticles prepared by sol-gel-hydrothermal route than those prepared by sol-gel route. As a result, the titania-silica composite nanoparticles prepared by sol-gel-hydrothermal route exhibited higher photocatalytic activity in decomposition of methylene blue than that prepared by sol-gel route, and it had excellent photocatalytic activity even after calcined at 1000 deg. C

314

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

315

Repton model of gel electrophoresis and diffusion  

OpenAIRE

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

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

1991-01-01

316

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

317

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

318

Characterization of sol-gel-prepared nanoferrites  

International Nuclear Information System (INIS)

Spinel Co1-xMnxFe2O4 nanoparticles were prepared by the sol-gel combustion technique. X-ray diffraction (XRD), atomic force microscopy (AFM) and vibration sample magnetometer (VSM) studies have been carried out in order to understand the temperature dependence of their properties. It is observed that the high concentration of Mn2+ substituted into CoFe2O4 tends to reduce the particle size. Furthermore, the influence of Mn on the magnetic and thermal characteristics of Co1-xMnxFe2O4 nanoparticles has been investigated in detail

319

Dynamical heterogeneities: from glasses to gels  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-12-10

320

Dynamical heterogeneities: from glasses to gels  

International Nuclear Information System (INIS)

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

321

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

322

Structural and micromechanical characterization of type I collagen gels.  

Science.gov (United States)

In this paper we report a study where we use a novel optical tweezers technique to measure the local viscoelastic properties of type I collagen solutions spanning the sol-to-gel transition. We use phase contrast optical microscopy to reveal dense and sparse regions of the rigid fibril networks, and find that the spatial variations in the mechanical properties of the collagen gels closely follow the structural properties. Within the dense phase of the connected network in the gel samples, there are regions that exhibit drastically different viscoelastic properties. Within the sparse regions of the gel samples, no evidence of elasticity is found. In type I collagen gels, we find a high degree of structural inhomogeneity. The inhomogeneity in the structural properties of collagen gels and the corresponding viscoelastic properties provide benchmark measurements for the behavior of desirable biological materials, or tissue equivalents. PMID:19880123

Latinovic, Olga; Hough, Lawrence A; Daniel Ou-Yang, H

2010-02-10

323

Structural colored gels for tunable soft photonic crystals.  

Science.gov (United States)

A periodically ordered interconnecting porous structure can be embodied in chemical gels by using closest-packed colloidal crystals as templates. The interconnecting porosity not only provides a quick response but also endows the porous gels with structural color arising from coherent Bragg optical diffraction. The structural colors revealed by porous gels can be regulated by several techniques, and thus, it is feasible to obtain desirable, smart, soft materials. A well-known thermosensitive monomer, N-isopropylacrylamide (NIPA), and other minor monomers were used to fabricate various structural colored gels. The selection of minor monomers depended on the targeted properties. This review focuses on the synthesis of templates, structural colored porous gels, and the applications of structural colored gel as smart soft materials for tunable photonic crystals. PMID:19306332

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

2009-01-01

324

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

325

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.

326

FORMULATION AND EVALUATION OF POLYHERBAL GEL FOR ANTI - INFLAMMATORY ACTIVITY  

Directory of Open Access Journals (Sweden)

Full Text Available 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. Assessment of Anti-inflammatory activity was done by carrageenan induced rat paw edema and formalin- induced rat paw edema. Individual and polyherbal gel of Cassia alata Linn,Cassia tora Linn. and Cynodon dactylon (L. Pers were found to possess anti-inflammatory effect in acute and chronic models. Polyherbal gel also showed synergistic effect as compared to individual gels which can be useful for the treatment of local inflammation.

Gouri Dixit*, Ganesh Misal, Vijay Gulkari and Kanchan Upadhye

2013-03-01

327

Computational methods for analysis of two-dimensional gels.  

Science.gov (United States)

Two-dimensional gel electrophoresis (2D gels) is an essential quantitative proteomics technique that is frequently used to study differences between samples of clinical relevance. Although considered to have a low throughput, 2D gels can separate thousands of proteins in one gel, making it a good complementary method to MS-based protein quantification. The main drawback of the technique is the tendency of large and hydrophobic proteins such as membrane proteins to precipitate in the isoelectric focusing step. Furthermore, tests using different programs with distinct algorithms for 2D-gel analysis have shown inconsistent ratio values. The aim here is therefore to provide a discussion of algorithms described for the analysis of 2D gels. PMID:19957153

Lasso, Gorka; Matthiesen, Rune

2010-01-01

328

Biochemical Identification of the Two Races of Radopholus similis by Polyacrylamide Gel Electrophoresis  

OpenAIRE

Analysis of proteins of the banana and citrus race of Radopholus similis was carried out by several different types of polyacrylamide gel electrophoresis. These included standard slab gel, SDS slab gel, gradient slab gel, and two-ditnensional slab gel electrophoresis. A major band difference was detected between the two races by slab gel electrophoresis. However, several other poorly resolved but consistent hands of high molecular weight proteins near the gel origin also were considered as di...

Huettel, R. N.; Dickson, D. W.; Kaplan, D. T.

1983-01-01

329

Role and properties of the gel formed during nuclear glass alteration: importance of gel formation conditions  

International Nuclear Information System (INIS)

A French SON 68 nuclear glass sample was experimentally altered to assess the mechanisms limiting the glass alteration kinetics, especially during the transition phase between the initial rate r0 and the final rate under silicon saturation conditions. A glass specimen was altered at the initial rate for one week to form a silicon-depleted non-protective gel; the specimen was then leached under static conditions at a glass-surface-to-solution-volume (S/V) ratio of 500 m-1 and the alteration kinetics were compared with those of a pristine glass specimen altered under the same conditions. Unexpectedly, after static leaching the previously leached glass was 2.7 times as altered as the pristine specimen, and the steady-state silicon concentration was twice as high for the previously leached specimen. STEM characterization of the alteration films showed that the initial non-protective gel constituted a silicon pump with respect to the glass, and that the glass alteration kinetics were limited only when a fraction of the gel became saturated with silicon, and exhibited protective properties. This work also shows that silicon recondensation was uniform at micrometer scale: the silicon hydrolyzed at the reaction interface then diffused before recondensing over a length comparable to the gel thickness. In addition to these findings, this investigation suggests a reinterpretation of the effect of the S/V ratio on the glass alteration kinetics and on the stee glass alteration kinetics and on the steady-state dissolved silicon concentration

330

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 testoste...

Anisha Patel; Rivkees, Scott A.

2010-01-01

331

UV photoannealing and RTP of thin sol-gel films  

International Nuclear Information System (INIS)

Various annealing methods for sol-gel films have been investigated. Thermal, photothermal, RTP and excimer laser annealing have been used to convert sol-gel precursor films into oxidic films. RTP annealing of sol-gel films yields better results than classical thermal annealing or excimer laser irradiation. Photochemical effects during RTP annealing contribute to obtain high-quality oxide films. The various annealing methods are illustrated by the annealing of alkoxide precursor films of tantalum, iron, nickel and yttrium

332

A fundamental study of tethered polymer chains in gel systems  

OpenAIRE

Two types of tethered polymers in the gel system were studied in this work. One involved polymer Chains grafted on the gel surface, while the other Consisted of the gel itself where mesh chains were tethered on each other through their chain ends. ^ Surface-tethered polymer chains were studied both theoretically and experimentally with the consideration of their application as adhesion promoters for the hydrogel mucoadhesion. On the theoretical side, the mucous layer was modeled as a highly...

Huang, Yanbin

2001-01-01

333

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

334

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)

335

Controlled Release Gel Formulations for Mucosal Drug Delivery  

OpenAIRE

Drug delivery to nasal or ocular mucosa for either local or systemic action faces many obstacles – these routes are protected by effective mechanisms. Gel formulations with suitable rheological and mucoadhesive properties increase the contact time at the site of absorption. However, drug release from the gel must be sustained if benefits are to be gained from the prolonged contact time. The work presented here is the characterization of gels and the determination of the mucoadhesive propert...

Paulsson, Mattias

2001-01-01

336

Rheologische Eigenschaften von Gel-Treibstoffen in Abhängigkeit der Temperatur  

OpenAIRE

Gel propellants provide rocket propulsion systems of high specific impulse, low sensitivity and low vulnerability in combination with the capability to control the thrust, i.e., variation of thrust and thrust cut off. The rheological characterisation is essential for the development of adequate gel propellant formulations and thus for the design of an applicable propulsion system. In this contribution, the rheological behaviour of a gel propellant consisting of nitromethane as fuel and nanopa...

Fo?rter-barth, U.; Teipel, U.

2003-01-01

337

Buckling transition of nematic gels in confined geometry  

OpenAIRE

A spontaneous buckling transition in thin layers of monodomain nematic liquid crystalline gel was observed by polarized light microscopy. The coupling between the orientational ordering of liquid crystalline solvent and the translational ordering of crosslinked polymer backbones inside the nematic gel contributes to such buckling transition. As the nematic mesogens become more ordered when the gel is cooled down from a higher gelation temperature, the polymeric backbones ten...

Meng, Guangnan; Meyer, Robert B.

2009-01-01

338

Film preparation by inorganic-organic sol-gel synthesis  

OpenAIRE

Film formation by sol-gel techniques is an advantageous method to obtain inorganic coatings. The sol-gel process allows the preparation of prepolymers with suitable viscosities to use various coating techniques like dipping, spraying and spin-on coating. The main disadvantage is the shrinkage of the gel layer during drying or sintering which leads to cracks with layer thicknesses more than some micrometers. The introduction of organics, causing a decrease of the network connectivity and incre...

Schmidt, Helmut K.; Rinn, Gu?nter; Nass, Ru?diger; Sporn, Dieter

1988-01-01

339

formulation and evaluation of topical gel of aceclofenac  

OpenAIRE

Topical gel formulations of Aceclofenac were prepared using these polymers such as Carbopol?934, Carbopol?941, HPMC, Poloxamer 407 in different concentration for the treatment of rheumatoid arthritis. The gels were evaluated for various parameters such as homogeneity, grittiness, skin irritancy, extrudability, in vitro drug release, viscosity(Brooke field viscometer), pH, drug content, stability studies. The in vitro release rate of gel was evaluated using Franz diffusion cell containing ...

tarun kumar guleri

2013-01-01

340

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

341

Continuum Model of Heterogeneous Gels: Formation and Elastic Properties  

OpenAIRE

A kinetic model of heterogeneous gel formation and a method to calculate gel stiffness are proposed, with application to the elastic properties of polyacrylamide gels. The model is based on assumptions about nucleation and growth of dense regions, governed by the concentration of monomer units (p0) crosslink agent (c0) and rate constants for chain propagation and curing. It is shown that at low c0 the polymer and crosslink densities inside and outside an inclusion are almost the same and that...

Oshmian, V.; Benguigui, L.

1996-01-01

342

G-Quadruplex Guanosine Gels and Single Walled Carbon Nanotubes  

OpenAIRE

Solubilization of single walled carbon nanotubes (SWNTs) in aqueous gel phases formed by reversible, G-quadruplex self-assembly of guanosine monophosphate (GMP) alone or with guanosine (Guo) is described. Unlike other media and methods for aqueous solubilization of SWNTs, the guanosine gels (“G-gels”) are found to readily disperse high (>mg/mL) concentrations of individual rather than bundled SWNTs. SWNT dispersions in GMP alone precipitate in several hours and re-form upon shaking; ho...

Yuehua Yu; Pushparaj, Victor L.; Omkaram Nalamasu; Mcgown, Linda B.

2013-01-01

343

A reproducible, high throughput method for fabricating fibrin gels  

OpenAIRE

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

Murphy Kaitlin C; Leach J

2012-01-01

344

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

345

Guidelines for reporting the use of gel electrophoresis in proteomics  

OpenAIRE

the MIAPE Gel Electrophoresis (MIAPE-GE) guidelines specify the minimum information that should be provided when reporting the use of n-dimensional gel electrophoresis in a proteomics experiment. Developed through a joint effort between the gel-based analysis working group of the Human Proteome Organisation's Proteomics Standards Initiative (HUPO-PSI; http://www.psidev.info/) and the wider proteomics community, they constitute one part of the overall Minimum Information abou...

Gibson, Frank; Anderson, Leigh; Babnigg, Gyorgy; Baker, Mark; Berth, Matthias; Binz, Pierre-alain; Borthwick, Andy; Cash, Phil; Day, Billy W.; Friedman, David B.; Garland, Donita; Gutstein, Howard B.; Hoogland, Christine; Jones, Neil A.; Khan, Alamgir

2009-01-01

346

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

347

Substrate Compliance versus Ligand Density in Cell on Gel Responses  

OpenAIRE

Substrate stiffness is emerging as an important physical factor in the response of many cell types. In agreement with findings on other anchorage-dependent cell lineages, aortic smooth muscle cells are found to spread and organize their cytoskeleton and focal adhesions much more so on “rigid” glass or “stiff” gels than on “soft” gels. Whereas these cells generally show maximal spreading on intermediate collagen densities, the limited spreading on soft gels is surprisingly insensit...

Engler, Adam; Bacakova, Lucie; Newman, Cynthia; Hategan, Alina; Griffin, Maureen; Discher, Dennis

2004-01-01

348

Applications and Nonlinear Mechanical Properties of Thermoreversible Triblock Copolymer Gels  

Science.gov (United States)

Thermoreversible triblock copolymer gels display a wide variation in mechanical behavior over a temperature range that is experimentally accessible. At elevated temperatures these gels behave as freely flowing solutions, exhibiting fast relaxation behavior. The relaxation time increases dramatically as temperature is reduced, such that at room temperature the gels become strong elastic materials. The nonlinear mechanical properties of triblock copolymer gels are ultimately dependent on the structure of the underlying physically associating network of triblock copolymer molecules and how this structure evolves during deformation and aging. The aim of this research is to characterize the structure-property relationships of triblock copolymer gels utilizing shear rheometry over a wide range of temperature and deformation rates. Behavior of the gels in the nonlinear regime -- i.e., the stress response during deformation to large strain or strain rate -- is of particular interest. Triblock copolymer gels were successfully applied as model systems for a variety of engineering and biophysical applications. The thermoreversible nature and mechanical strength of the gels was found to be advantageous in a low-temperature casting process for titanium foams of complex shape. The gels were also demonstrated to be excellent synthetic model systems for strain-stiffening biological materials. Additionally, evidence of flow inhomogeneities in the triblock copolymer gels coupled with the well-defined structure of the gels and the wide range of accessible relaxation times makes these gels ideal model systems for future studies of deformation-induced failure in physically associating solutions and complex fluids. The foundation is also being laid for the rheological investigation of two-dimensional layers of self-assembled triblock copolymer molecules with the hope of establishing these physically associating networks as synthetic model systems for biological membranes and thin films.

Erk, Kendra A.

349

NASAL IN SITU GEL: A NOVEL DRUG DELIVERY SYSTEM  

OpenAIRE

Over the past few decades, advances in the in situ gel technologies have spurred development in manymedical and biomedical applications including controlled drug delivery. Many novel in situ gel baseddelivery matrices have been designed and fabricated to fulfill the ever increasing needs of thepharmaceutical and medical fields. In situ gelling systems are liquid at room temperature but undergogelation when in contact with body fluids or change in pH. In situ gel forming drug delivery is a typ...

Dhrupesh panchal; Dr.Upendra patel; Bhavin bhimani; Dhiren daslaniya; Ghanshyam patel

2012-01-01

350

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

351

Pacman percolation: a model for enzyme gel degradation  

CERN Document Server

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

Abete, T; Lairez, D; Coniglio, A

2004-01-01

352

Highly porous thin films obtained by spray-gel technique  

Science.gov (United States)

Combining the spray pyrolysis and the sol-gel techniques (spray-gel) gives the possibility to produce very rough and highly diffuse films. This technique is suitable for producing multifunctional metal oxides for gas-sensing, electrochromism, microbattery, and photocatalysis applications; due to the fact that it yields a large interface between a solid and a gaseous/liquid medium. The process basically consists in producing an aerosol from a gel, which is sprayed over a hot substrate, where the film is going to grow. In this work we present the results on highly porous SnO2, WO3, and phosphotungstic acid (PWA) thin films obtained by spray-gel.

Solis, J. L.; Rodriguez, J.; Estrada, W.

2004-08-01

353

Synthesis of surface patterns on the gel surface  

Science.gov (United States)

The surface structures of hydrogels play important roles for many potential applications in physical, chemical and biomedical fields. Our idea is to precisely control the local properties of the one gel surface by incorporating different materials onto the given areas selected with a mask. We have successfully deposited NIPA polymer gel on the controlled area of the surface of an agarose gel. The pattern of the NIPA deposited area can be either visible or invisible by simply switching temperature above or below the low critical solution temperature (LCST) of the NIPA gel.

Zheng, Yindong; Wang, Changjie; Hu, Zhibing; Li, Yong

1997-10-01

354

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

355

A NOVEL OPHTHALMIC DRUG DELIVERY SYSTEM: IN-SITU GEL  

OpenAIRE

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...

A P Patil, A. A. Tagalpallewar

2012-01-01

356

Production of silica gel from residual rice husk ash  

Directory of Open Access Journals (Sweden)

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

Samantha Pinheiro Buás de Lima

2011-01-01

357

Silica scintillating materials prepared by sol-gel methods  

International Nuclear Information System (INIS)

Silica was investigated as a rad-hard alternative to organic polymer hosts for organic scintillators. Silica sol-gels were prepared by hydrolysis of tetramethoxysilane in alcohol solutions. organic dyes were incorporated into the gels by dissolving in methanol at the sol stage of gel formation. The silica sol-gel matrix is very rad-hard. The radiation stability of silica scintillators prepared by this method is dye-limited. Transient radioluminescence was measured following excitation with 30 ps pulses of 20 MeV electrons

358

Application of CMPO containing gels to metal extraction  

International Nuclear Information System (INIS)

Immersed in solubility-consistent organic solvents, high polymers can swell and form gels. Choosing the organic solvent among metal extracting solvents, metal extracting gels can be prepared. The advantages of the liquid-gel extraction process, in comparison with the liquid-liquid one, are to allow the extraction of metal cations from diluted aqueous solutions by using high aqueous-organic volume ratios (metal concentration in a few stages) with easy phase separations. Various CMPO (Octyl (phenyl) -N,N-diisobutylcarbamoylmethylphosphine oxide) containing gels have been prepared, and the extraction of europium (and related actinides) has been studied

359

The isotropic-cholesteric transition in liquid-crystalline gels  

OpenAIRE

In a nematic gel, the appearance of nematic order is accompanied by a spontaneous elongation of the gel parallel to the nematic director. If such a gel is made chiral, it has a tendency to form a cholesteric helical texture, in which local elongation of the gel parallel to the nematic director is suppressed due to the requirement of elastic compatibility. We show that a conical helix in which the director makes an oblique angle with respect to the helix axis serves as an ene...

Pelcovits, Robert A.; Meyer, Robert B.

2002-01-01

360

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

361

Time to first fracture affects sweetness of gels  

OpenAIRE

The aim of this study was to investigate the influence of the breakdown behaviour on sweetness intensity of gelled model foods. Emulsion-filled gelatine/agar gels varying mainly in fracture strain (?F) were used. The fracture strain was modified by changing either the ratio between gelatine and agar concentration or the size of the oil droplets embedded in the gel matrix. The sugar content of all gels was kept constant at 6 wt%. The fracture strain of the gels varied between ?F = 37% and ?...

Sala, G.; Stieger, M. A.

2013-01-01

362

Sol-gel Characteristics for Corrosion Resistance of Anodised Aluminium  

OpenAIRE

Conventional anodising electrolytes based on sulphuric acid, oxalic acid and phosphoric acid have been used to form nanoporous layers on AA3003-H14 and sealed with silane based sol-gel sealers. It is shown that the sol-gel chemistries have varying levels of pore penetration depending on the synthesis conditions. The extent of sol-gel penetration and pore sealing is analysed by electron microscopy and energy dispersive x-ray spectroscopy. To describe the sealing phenomena observed a sol-gel pe...

Whelan, Michael; Cassidy, John F.; Duffy, Brendan

2013-01-01

363

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.

364

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

365

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

International Nuclear Information System (INIS)

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

366

Trial participation disclosure and gel use behavior in the CAPRISA 004 tenofovir gel trial  

Science.gov (United States)

Disclosure, or open communication, by female microbicide trial participants of their trial participation and use of an investigational HIV prevention drug to a sexual partner may affect participants' trial product usage behavior and contribute to poor adherence. With mixed results from recent microbicide clinical trials being linked to differing participant adherence, insights into the communication dynamics between trial participants and their sexual partners are particularly important. We examined the quantitative association between (1) communication of trial participation to a partner and participant adherence to gel and (2) communication of trial participation to a partner and participant HIV status. An in-depth adherence and product acceptability assessment was administered to the women participating in the CAPRISA 004 trial. Additionally, we collected qualitative data related to communication of trial participation and gel use. Qualitatively, among 165 women who had reported that they had discussed trial participation with others, most (68%) stated that they communicated participation to their sexual partner. Most of the women who had communicated study participation with their partners had received a positive/neutral response from their partner. Some of these women stated that gel use was easy; only a small number said that gel use was difficult. Among women who did not communicate their study participation to their partners, difficulty with gel use was more common and some women stated that they feared communicating their participation. Quantitatively, there was no statistically significant difference in the proportions of women who had communicated study participation to a partner across different adherence levels or HIV status. A deeper knowledge of the dynamics surrounding trial participation communication to male partners will be critical to understanding the spectrum of trial product usage behavior, and ultimately to designing tailored strategies to assist trial participants with product adherence. PMID:25285564

Succop, Stacey M.; MacQueen, Kathleen M.; van Loggerenberg, Francois; Majola, Nelisile; Karim, Quarraisha Abdool; Karim, Salim S. Abdool

2014-01-01

367

Concentration fluctuations in polymer gel investigated by neutron scattering: Static inhomogeneity in swollen gel  

Science.gov (United States)

By using small-angle neutron scattering (SANS) and neutron spin echo (NSE), we have quantitatively investigated the static inhomogeneity in poly (N-isopropyl acrylamide) gel (PNIPA) in microscopic length scales of 0.015gel decays more slowly as compared to the PNIPA solution without crosslinks. According to our scenario that the slower decay found for the PNIPA gel is due to the static inhomogeneity coexisting in the swollen gel, small-angle scattering S(q) obtained by SANS has been quantitatively decomposed into thermal and static scattering components, respectively, Sth(q) and Sst(q). It was further revealed that (i) the q-region where Sst(q) becomes dominant is closely related to that for the abnormal butterfly scattering under stretching, and (ii) as the temperature increases toward the temperature for volume phase transition, Sst(q) of a squared Lorentzian shape increases more drastically than Sth(q) of a Lorentzian shape. These findings were quantitatively understood in the theoretical framework by Panyukov and Rabin [Macromolecules 29, 7960 (1996)] or by Onuki [J. Phys. II. France 2, 45 (1992)], taking into account stress-fluctuation coupling under coexistence of the inherent structural heterogeneity in the real gel. We further found that the static inhomogeneity showing Sst(q) seems to relate to the necklacelike microstructure, appearing after a shallow quench into the collapsed phase.

Koizumi, Satoshi; Monkenbusch, Michael; Richter, Dieter; Schwahn, Dietmar; Farago, Bela

2004-12-01

368

DEVELOPMENT OF MELOXICAM SODIUM TRANSDERMAL GEL  

Directory of Open Access Journals (Sweden)

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

Dr. Shashikant D. Barhate

2010-07-01

369

Brownian Dynamics simulations of aging colloidal gels  

CERN Document Server

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

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

2002-01-01

370

A gel polymer electrolyte of magnesium triflate  

Energy Technology Data Exchange (ETDEWEB)

Investigations leading to understanding and development of solid state rechargeable magnesium batteries are important in view of the fact that the Mg is free from hazards, it's stability is high and it's natural resources are abundant. A Mg{sup 2+} ion conducting gel polymer electrolyte (GPE) is investigated for a possible application in solid state rechargeable Mg battery. The GPE consists of polyacrylonitrile, propylene carbonate, ethylene carbonate and magnesium trifluoromethane sulfonate (magnesium triflate). The composition is optimized in view of the minimum liquid constituents required for the gel formation and the maximum specific conductivity ({sigma}). The {sigma} of the GPE follows Arrhenius behavior and the energy of activation for ionic conduction is in the range between 0.13 and 0.16 eV. The a.c. impedance data of Mg/GPE/Mg symmetrical cells are analyzed by fitting the data to an equivalent circuit. The values of interfacial resistance (R{sub i}) of the Mg/GPE, which is contributed by surface film resistance (R{sub f}) on the Mg and charge-transfer resistance (R{sub ct}) of the electrochemical reaction are evaluated. The R{sub i} decreases with an increase of cell temperature. On the other hand, it increases with the ageing time of the cell at ambient temperature.

Kumar, G.G.; Munichandraiah, N. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore (India)

2000-02-01

371

The magnesia-silica gel phase in slag cements: alkali (K, Cs) sorption potential of synthetic gels  

International Nuclear Information System (INIS)

Blends of Portland cement with blast furnace slag hydrate to yield two gel phases, one essentially a calcium silicate hydrate (C-S-H) composition, the other a magnesium silicate hydrate (M-S-H) composition: the two gel phases are essentially immiscible. Together, the gel phases comprise an important source of sorption potential for the alkalis present in ordinary cement and blending agents. M-S-H gels have been synthesised and their sorption potential measured for postassium (K) and cesium (Cs) at 25 deg. C by using fresh gels as well as gels previously aged at 85 deg. C for 6 months. The ability of slag-cement blends to lower pore fluid alkalinity generally, and in nuclear waste technology to incorporate Cs, is interpreted in terms of the sorption data

372

Influence of micro gel particles of sodium alginate on gel structure of calcium alginate gels used for controlled release of active substances  

International Nuclear Information System (INIS)

The properties of gel particles of calcium alginate with a chitosan membrane for controlled release of active substances, beside the conformation properties of the macromolecules of sodium alginate and chitosan in solution, depend on the internal structure of the gel which can be controlled or be modified by inducing micro gel structures in the pregel solution with addition of calcium ions. The quantity, dimension and the form of the micro gel structures are in direct relation with the molecular mass, dimension, flexibility, electrical properties, concentration and the mannuronic-to-guluronic ratio from the primary chain of sodium alginate macromolecules as well as temperature. Also, the final properties of controlled release are predetermined from the conditions of gel particle preparation (rate of dropping of sodium alginate solution in the gelling bath, speed of steering of the gelling bath and the time of setting of the gel particles). The research is realised by working with the methods of- gel-permeation chromatography, viscosimetry, static and dynamic light scattering, electric birefringence, spectrophotometry of the kinetics of release of the active substance and scanning electron microscopy.(Author)

373

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

374

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

Scientific Electronic Library Online (English)

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

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

1985-09-01

375

Rheological, mucoadhesive and release properties of pluronic F-127 gel and pluronic F-127/polycarbophil mixed gel systems.  

Science.gov (United States)

This study was designed to combine the mucoadhesive property of Noveon and the thermosensitive property of Pluronic F-127 into one gel system. A rheological study of Pluronic aqueous sols (10-35%), Noveon gels (0.5-2%) and of mixed gels containing Pluronic (10-17.5%) and polycarbophil (0.5-2.5%) was conducted at different temperatures (15-35 degrees C). The viscosity of Pluronic sols increased with an increase in temperature and the mixed gels had thermoreversible property. The viscosity of mixed gels was higher than that of the Pluronic sols containing only Pluronic because of the increase in total polymer concentration. No interaction was found between -COOH groups of Noveon and Pluronic molecules at the studied concentrations of polymers; the viscosity of mixed gels containing un-neutralized Noveon was lower than that of the neutralized mixed gels. The effect of Pluronic F-127 on the mucoadhesive property of Noveon was investigated. The mucoadhesive properties of Pluronic and Noveon gels were compared by a force of detachment test. It was found that Pluronic and Noveon gels showed approximately the same mucoadhesive strength. However, there were significant differences in the viscosity of Noveon and Pluronic gels. The adhesive force of the mixed gel was almost same as that of the Noveon gel. The Pluronic did not affect the adhesive power of Noveon and the increased viscosity did not affect the bioadhesive force of the mixed gels. In spite of increasing viscosity of the gel, the percentage of released model material (mannitol) increased with increasing temperature. This is based on the previously reported observation that the interaction between the Pluronic molecules squeezed mannitol molecules out of the polymer chains. The mannitol release obeyed zero-order kinetics and the flux values of mixed gels at 15 and 35 degrees C were very similar. The Noveon chains among Pluronic chains probably hindered the diffusion of mannitol molecules and the release was thus controlled by Noveon. The combination of a thermosensitive polymer like Pluronic and a bioadhesive polymer like Noveon appears promising from a pharmaceutical viewpoint. These gel systems may find use in the development of bioadhesive, thermosensitive and controlled release formulations. PMID:16076078

Tirnaksiz, F; Robinson, J R

2005-07-01

376

Preparation of ZnO nanoparticles in amphiphilic gel network  

International Nuclear Information System (INIS)

Nanosized zinc oxide (ZnO) particles were prepared in an amphiphilic N,N-dimethylacrylamide (DMAA) gel composed of a three-dimensional network with an effective pore size of the order of nanometers. The procedures consist of two major steps: (1) preparation of a precursor and (2) hydrolysis of the precursor to form nanoparticles. First, the plate-type dry gel was swollen in ethanol containing zinc acetate (ZnAc) in order to diffuse ZnAc molecules into the gel. Then, the ethanolic solution containing the gel was heated to ?80 deg. C to prepare the precursor. In the hydrolysis of the precursor, lithium hydroxide was added as the catalyst to the precursor solution containing the gel, and the solution was placed in an ultrasonic bath. Although the DMAA gel containing ZnO particles was completely transparent, it exhibited a yellow-green luminescence when irradiated with UV light. The ZnO nanoparticles stably dispersed in the gel network without growing, aggregating, or flowing out for over several months at a relatively high temperature of 50 deg. C. The particle size depended on the effective pore size of the gel network, which could be controlled by the synthesis composition of the gel, that is, by the concentrations of DMAA as the primary monomer and N,N'-methylenebisacrylamide (MBAA) as the cross-linker used for synthesizing the gel. This implies that the particle size can be controlled at the nanosized level by the synthesis composition of the gelomposition of the gel

377

Radiological properties of MAGIC normoxic polymer gel dosimetry  

International Nuclear Information System (INIS)

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 densn, 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.

378

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.

379

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.)

380

Enhanced local anesthetic action of mepivacaine from the bioadhesive gels.  

Science.gov (United States)

Mepivacaine, an amide-type local anesthetic, has been used to relieve local pain. Among the many drug delivery systems, transdermal drug delivery has some advantages, as it provides controlled drug delivery for an extended period of time. To develop new gel formulations that have suitable bioadhesion, the bioadhesive force of hydroxypropyl methylcellulose (HPMC) was assessed using an auto-peeling tester. The effect of drug concentration on drug release from 2% HPMC gel was studied using synthetic cellulose membrane at 37±0.5°C. The drug concentrations tested were 0.5, 1, 1.5, 2, and 2.5%. The effect of temperature on drug release from the 2% drug gel was evaluated at 27, 32, 37 and 42°C. To increase the skin permeation of mepivacaine from HPMC gel, enhancers such as saturated and unsaturated fatty acids, pyrrolidones, propylene glycol derivatives, glycerides, and non-ionic surfactants were incorporated into the mepivacaine-HPMC gels. The enhancing effect of the enhancer on drug permeation was then examined in the modified Keshary-Chien cell. For the efficacy study, the anesthetic action of the formulated mepivacaine gel containing enhancer and vasoconstrictor was evaluated with the tail-flick analgesimeter. Among the various kinds of HPMC, HPMC-K100M gel showed the highest viscosity and bioadhesive force. As the viscosity of the HPMC gels increased, the bioadhesive forces increased. Increasing the drug concentration or temperature increased the drug release rate. Among the enhancers used, polyoxyethylene 2-oleyl ether showed the greatest enhancement of permeation. Based on the area under the efficacy curve of the rat tail flick test curve, mepivacaine gel containing polyoxyethylene 2-oleyl ether and tetrahydrozoline showed prolonged and increased local anesthetic action compared to the control. For bioadhesive mepivacaine gels with enhanced local anesthetic action, mepivacaine gels containing penetration enhancer and vasoconstrictor could be developed with the bioadhesive polymer, HPMC. PMID:21190925

Cho, Cheong-Weon; Choi, Jun-Shik; Shin, Sang-Chul

2011-01-01

381

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

382

21 CFR 866.4800 - Radial immunodiffusion plate.  

Science.gov (United States)

21 Food and Drugs 8 2010-04-01... Section 866.4800 Food and Drugs FOOD AND DRUG ADMINISTRATION...As the reagents come in contact with each other, they...exempt from the premarket notification procedures in...

2010-04-01

383

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

Directory of Open Access Journals (Sweden)

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

384

Quantitative evaluation of polymer gel dosimeters by broadband ultrasound attenuation  

International Nuclear Information System (INIS)

Ultrasound has been examined previously as an alternative readout method for irradiated polymer gel dosimeters, with authors reporting varying dose response to ultrasound transmission measurements. In this current work we extend previous work to measure the broadband ultrasound attenuation (BUA) response of irradiated PAGAT gel dosimeters, using a novel ultrasound computed tomography system.

385

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

386

Investigation of natural and artificial Zr-silicate gels  

International Nuclear Information System (INIS)

Sample of natural Zr-silicate gel containing up to 13 wt.% U was characterized using scanning electron microscopy (SEM), X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and electron microprobe analysis (EPMA) method. It was found that gel matrix is amorphous in general; however, it contains non-identified nanocrystallites. No separated oxide phases of U, Zr or Si were observed in a gel matrix. After sintering in air at 1400 deg. C for 1 hour gel transformed largely into crystalline zircon, (Zr,U)SiO4. Uranium was not found in any other phases besides zircon. It was assumed that high chemical durability of natural Zr-P-U-Ti-silicate gel is caused by two competing processes which exist under self-irradiation conditions: 1) crystallization of the gel and 2) metamictization of the crystallized zircon and other phases. Synthetic samples of Zr-silicate gel doped with Ce, U, Pu and Am were obtained and studied in comparison with natural samples. It was suggested to use artificial solid Zr-silicate gels for durable fixation of actinides for the goal of long-term or intermediate storage. (author)

387

Development of satranidazole mucoadhesive gel for the treatment of periodontitis.  

Science.gov (United States)

The aim of the paper was to develop satranidazole-containing mucoadhesive gel for the treatment of periodontitis. Different mucoadhesive gels were prepared, using various gelling agents like sodium carboxymethylcellulose (SCMC), poloxamer 407, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and the mucoadhesive polymer carbopol 934P. The selected formulations (based on the mucoadhesive force) were studied for different mechanical properties, such as mucoadhesive strength, hardness, compressibility, adhesiveness, and cohesiveness through Texture Profile Analyzer. In vitro satranidazole release from the prepared formulations was also determined and compared with marketed preparation of metronidazole (Metrogyl gel). The formulation SC30 (containing SCMC 3% w/v) showed maximum mucoadhesive strength (167.72 +/- 3.76 g) and adhesiveness (-46.23 +/- 0.34 N mm), with low hardness (9.81 +/- 0.04 N) and compressibility (40.05 +/- 0.48 N mm) and moderate cohesiveness (0.87 +/- 0.01). SC30 formulation exhibited long-term release. Thus, SC30 gel was evaluated for its clinical effectiveness along with marketed metronidazole gel. At the end of the study (42 days of clinical studies), both formulations were found to significantly reduce the probing depth, plaque index, gingival index, calculus criteria, and bleeding index. However, the SC30 gel was more effective in reducing the above parameters than marketed metronidazole gel. This study confirmed the acceptability and effectiveness of satranidazole gel for treatment of periodontitis. PMID:19479385

Bansal, K; Rawat, M K; Jain, A; Rajput, A; Chaturvedi, T P; Singh, S

2009-01-01

388

Development of Satranidazole Mucoadhesive Gel for the Treatment of Periodontitis  

OpenAIRE

The aim of the paper was to develop satranidazole-containing mucoadhesive gel for the treatment of periodontitis. Different mucoadhesive gels were prepared, using various gelling agents like sodium carboxymethylcellulose (SCMC), poloxamer 407, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and the mucoadhesive polymer carbopol 934P. The selected formulations (based on the mucoadhesive force) were studied for different mechanical properties, such as mucoadhesive s...

Bansal, K.; Rawat, M. K.; Jain, A.; Rajput, A.; Chaturvedi, T. P.; Singh, S.

2009-01-01

389

Transfer printing of thermoreversible ion gels for flexible electronics.  

Science.gov (United States)

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

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

2013-10-01

390

Dose response characteristics in polymer gel for the composition ratio  

Energy Technology Data Exchange (ETDEWEB)

Although a gel dosimeter is not widely used, it has many potential merits for 3D dosimetry in the development of radiotherapy techniques. Because conventional gel dosimeters tend to sensitively polymerize with oxygen. A new polymer gel that solves these problems was introduced recently. The gel dosimeter contains anti-oxidants that eliminate oxygen chemically instead of using complicated facilities. The type and the concentration of the monomer affect the polymerization of the polymer gel dosimeter. Therefore, the polymerization of the normoxic polymer gel dosimeter is affected by anti-oxidant, the monomer, the constituent ratio, and the condition of the monomer, so many researchers have concentrated on the anti-oxidant, the type of monomer, and the constituent ratio. In this study, a normoxic polymer gel dosimeter was composed using anti-oxidants in a laboratory, and the dose response and sensitivity were measured. The results of this study are as follow the threshold R2 values were reduced, and the radio sensitivity was reduced with the increasing MAA ratio. Otherwise, the increase in the gelatin represented an increase and decrease in the threshold value of R2 values and the radio sensitivity, respectively. Therefore, in this study, 6 - 8 % MAA ratios and an 8 % gelatin ratio, considering the aging effect of the gel, were the optimal values.

Cho, Sam Ju; Shim, Su Jung [Eulji University, Seongnam (Korea, Republic of); Kim, Chul Yong; Sim, Jang Bo; Lee, Suk [Korea University, Seoul (Korea, Republic of); Lee, Sang Hoon [Kwandong University College of Medicine, Seoul (Korea, Republic of); Huh, Hyun Do [Inha University Hospital, Incheon (Korea, Republic of); Shin, Dong Oh [Kyung Hee University, Suwon (Korea, Republic of); Lee, Rena [Ewha Woman' s University, Seoul (Korea, Republic of)

2010-01-15

391

Tierexperimentelle Untersuchungen zur Adipogenese in Gel-Trägern als Weichgewebsersatz  

OpenAIRE

Ziel dieser Arbeit war die Entwicklung eines Weichgewebeersatzes auf der Basis von biokompatiblen Materialien in Verbindung mit autologen Präadipozyten. Hierzu wurden drei verschiedene Gel-Arten (Matrigel, Kollagengel, HYADD-3 Gel) hinsichtlich ihrer Potenz, differenziertes und reifes Fettgewebe zu erzeugen, untersucht. Die Implantation der unterschiedlichen Biohybride erfolgte in einer standardisierten Umgebung mittels Acetal Polymer Kammern an immuninkompetenten Nacktratten. Für die Evalu...

Piatkowski Grzymala, Andrzej

2005-01-01

392

Gel Electrophoresis--The Easy Way for Students  

Science.gov (United States)

This article describes a simple, inexpensive, easy to conduct gel-electrophoresis activity using food dyes. It is an alternative to the more expensive counterparts which require agarose gel, DNA samples, purchased chamber and Tris-borate-EDTA buffer. We suggest some learning activities for senior biology students along with comments on several…

VanRooy, Wilhelmina; Sultana, Khalida

2010-01-01

393

Quantitative characterization of developing collagen gels using optical coherence tomography  

Science.gov (United States)

Nondestructive optical imaging methods such as optical coherence tomography (OCT) have been proposed for characterizing engineered tissues such as collagen gels. In our study, OCT was used to image collagen gels with different seeding densities of smooth muscle cells (SMCs), including acellular gels, over a five-day period during which the gels contracted and became turbid with increased optical scattering. The gels were characterized quantitatively by their optical properties, specified by analysis of OCT data using a theoretical model. At 6 h, seeded cell density and scattering coefficient (?s) were correlated, with ?s equal to 10.8 cm-1/(106 cells/mL). Seeded cell density and the scattering anisotropy (g) were uncorrelated. Over five days, the reflectivity in SMC gels gradually doubled with little change in optical attenuation, which indicated a decrease in g that increased backscatter, but only a small drop in ?s. At five days, a subpopulation of sites on the gel showed substantially higher reflectivity (approximately a tenfold increase from the first 24 h). In summary, the increased turbidity of SMC gels that develops over time is due to a change in the structure of collagen, which affects g, and not simply due to a change in number density of collagen fibers due to contraction.

Levitz, David; Hinds, Monica T.; Choudhury, Niloy; Tran, Noi T.; Hanson, Stephen R.; Jacques, Steven L.

2010-03-01

394

A comparative study of new type polymer gel dosimeters  

International Nuclear Information System (INIS)

In this study we have investigated and evaluated some dosimetric properties of polymer gel dosimeter encountered when using gels in clinical radiation therapy environment. Four different compositions of polymer gel dosimeter were manufactured. Two compositions (A and D) represent widely recognized gels prepared following literature instructions. In case of MAGIC type dosimeter (D), gelatin weight fraction was decreased to 5%. During our previous research, we have experienced some substantial changes in behavior when lowering amount of sodium hydroxide and when potassium aluminum sulfate was added. Therefore another two gels were prepared (B and C). Gel dosimeters were evaluated using transversal relaxation rate R2. Details of the used acquisition sequence may be found in Spevacek V. et.al. (2001), only eight echo times were used for R2 calculation in this case. The following properties have been investigated for the four gel compositions: dose response; temperature dependence of dose response; short and long term stability; behavior of gels in a region of steep dose gradient; and uniformity of homogeneously irradiated region. (authors)

395

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

396

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

397

The Pozzolanic Activity of Calcined Clay – Silica Gel Composites  

Directory of Open Access Journals (Sweden)

Full Text Available The effect of silica gel additive on pozzolanic activity of burned clays was investigated on this study. It was determined that calcined (600 ºC – 730 ºC clay of Saltiskiai quarry has very low pozzolanic activity (104 mg – 55 mg CaO/g. It was observed that during calcination process the fluorine ions from silica gel were not combined to another compounds but directly passed to atmosphere. Moreover, silica gel additive significantly increases the mentioned clay activity, which depends on the quantity of the used additive. It was determined that 10 % of silica gel additive increases the pozzolanic activity of composite with clay of Saltiskiai quarry up to 109 mg CaO/g, meanwhile the 80 % – unto 257 mg CaO/g. The same effect of silica gel additive was observed in the samples with Dukstyna quarry clay. It was found that the pozzolanic activity of Dukstyna clay-silica gel composite with 10 % of silica gel additive, burned at 600 ºC for 1h, was 7 % higher (168 mgCaO than the activity of the clay samples (157 mgCaO/g, whereas 229 mgCaO/g pozzolanic activity was reached than 80 % additive of silica gel was used. Despite this fact, the pozzolanic activity decreases when the calcination at 700 ºC – 860 ºC temperature was carried out. DOI: http://dx.doi.org/10.5755/j01.ms.19.4.2300

Raimonda KUBILI?T?

2013-12-01

398

Electrochemical behavior of ionically crosslinked polyampholytic gel electrolytes  

Energy Technology Data Exchange (ETDEWEB)

An ionic complex of anionic and cationic monomers was obtained by protonation of (N,N-diethylamino)ethylmethacrylate (DEA) with acrylic acid (AAc). Free radical copolymerization of the ionic complex and acrylamide (AAm), yielded the ionically crosslinked polyampholytic gel electrolytes [poly(AAc-DEA-AAm), designated as PADA] using two types of organic solvents containing a lithium salt. The PADA gel electrolyte exhibited good thermal stability shown by the DSC thermogram. The impedance analysis at temperatures ranging from -30 to 75 C indicated that the ionic conductivities of the PADA gel electrolytes were rather close to those of liquid electrolytes. The temperature dependence of the ionic conductivities was found to be in accord with the Arrhenius equation. Moreover, the ionic conductivities of PADA gel electrolytes increased with an increase of the molar ratios of cationic/anionic monomers. The ionic conductivities of PADA gels prepared in solvent mixtures of propylene carbonate, ethyl methyl ether and dioxolane (3:1:1, v/v) were higher than those of PADA gels prepared in propylene carbonate only. Significantly, the ionic conductivities of two kinds of PADA gel electrolytes were in the range of 10{sup -3} and 10{sup -4} S cm{sup -1} even at -30 C. The electrochemical windows of PADA gel electrolytes measured by cyclic voltammetry were in the range from -1 V to 4.5 V. (author)

Chen, Wanyu; Tang, Haitao; Ou, Ziwei; Wang, Hong; Yang, Yajiang [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China)

2007-12-31

399

Electrochemical behavior of ionically crosslinked polyampholytic gel electrolytes  

Energy Technology Data Exchange (ETDEWEB)

An ionic complex of anionic and cationic monomers was obtained by protonation of (N,N-diethylamino)ethylmethacrylate (DEA) with acrylic acid (AAc). Free radical copolymerization of the ionic complex and acrylamide (AAm), yielded the ionically crosslinked polyampholytic gel electrolytes [poly(AAc-DEA-AAm), designated as PADA] using two types of organic solvents containing a lithium salt. The PADA gel electrolyte exhibited good thermal stability shown by the DSC thermogram. The impedance analysis at temperatures ranging from -30 to 75 deg. C indicated that the ionic conductivities of the PADA gel electrolytes were rather close to those of liquid electrolytes. The temperature dependence of the ionic conductivities was found to be in accord with the Arrhenius equation. Moreover, the ionic conductivities of PADA gel electrolytes increased with an increase of the molar ratios of cationic/anionic monomers. The ionic conductivities of PADA gels prepared in solvent mixtures of propylene carbonate, ethyl methyl ether and dioxolane (3:1:1, v/v) were higher than those of PADA gels prepared in propylene carbonate only. Significantly, the ionic conductivities of two kinds of PADA gel electrolytes were in the range of 10{sup -3} and 10{sup -4} S cm{sup -1} even at -30 deg. C. The electrochemical windows of PADA gel electrolytes measured by cyclic voltammetry were in the range from -1 V to 4.5 V.

Chen Wanyu; Tang Haitao; Ou Ziwei; Wang Hong [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China); Yang Yajiang [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China)], E-mail: yjyang@mail.hust.edu.cn

2007-12-31

400

Gels as battery separators for soluble electrode cells  

Science.gov (United States)

Gels are formed from silica powders and hydrochloric acid. The gels are then impregnated into a polymeric foam and the resultant sheet material is then used in applications where the transport of chloride ions is desired. Specifically disclosed is the utilization of the sheet in electrically rechargeable redox flow cells which find application in bulk power storage systems.

Sheibley, D. W.; Gahn, R. F. (inventors)

1977-01-01

401

Effects of gel composition on the radiation induced density change in PAG polymer gel dosimeters: a model and experimental investigations  

International Nuclear Information System (INIS)

Due to a density change that occurs in irradiated polyacrylamide gel (PAG), x-ray computed tomography (CT) has emerged as a feasible method of performing polymer gel dosimetry. However, applicability of the technique is currently limited by low sensitivity of the density change to dose. This work investigates the effect of PAG composition on the radiation induced density change and provides direction for future work in improving the sensitivity of CT polymer gel dosimetry. A model is developed that describes the PAG density change (??gel) as a function of both polymer yield (%P) and an intrinsic density change, per unit polymer yield, that occurs on conversion of monomer to polymer (??polymer). %P is a function of the fraction of monomer consumed and the weight fraction of monomer in the unirradiated gel (%T). Applying the model to experimental CT and Raman spectroscopic data, two important fundamental properties of the response of PAG density to dose (??gel dose response) are discovered. The first property is that ??polymer depends on PAG %C (cross-linking fraction of total monomer) such that low and high %C PAGs exhibit a higher ??polymer than do more intermediate %C PAGs. This relationship is opposite to the relationship of polymer yield to %C and is explained by the effect of %C on the type of polymer formed. The second property is that the ??gel dose response is linearly dependent on %Tse is linearly dependent on %T. From the model, the inference is that, at least for %T?12%, monomer consumption and ??polymer depend solely on %C. In terms of optimizing CT polymer gel dosimetry for high sensitivity, these results indicate that ??polymer can be expected to vary with each polymer gel system and thus should be considered when choosing a polymer gel for CT gel dosimetry. However, ??polymer and %P cannot be maximized simultaneously and maximizing %P, by choosing gels with intermediate %C and high %T, is found to have the greatest impact on increasing the sensitivity of PAG density to dose. As such, future research into new gel formulations for high sensitivity CT polymer gel dosimetry should focus on gels that exhibit an intrinsic density change and maximizing polymer yield in these systems

402

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

403

KINETICS OF PITTING CORROSION IN GELS  

International Nuclear Information System (INIS)

An investigation has been carried out on stainless steel to determine the important parameters that related the changes in pH around pits to the current coming from the pits. Potentiodynamic measurements at 1 mV/s were made on Type 302 stainless steel in agar containing 1M NaCl and a wide range pH indicator. Many pits suddenly appeared at the pitting potential, as indicated by the red, low pH region around the pits. Simulations of the changes in pH were based on diffusion from a point current source. The results also were considered in terms of the effects of a minimum detectable thickness of pH change within the gel

404

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

Scientific Electronic Library Online (English)

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

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

2008-12-01

405

Nanocrystalline Pentaerythritoltetranitrate using Sol-Gel Process  

Directory of Open Access Journals (Sweden)

Full Text Available The secondary explosives developed with reduced particle size tend to be more insensitive for mechanical stimuli and may release energy with faster rate and gaining more importance nowadays. Therefore, aiming to reduce the particle size of one of the popular explosives, viz., pentaerythritoltetranitrate (PETN to the nanometer range, a method for preparation of nanocrystalline PETN in the silica (SiO2 gel matrix using sol-gel process has been demonstrated. The PETN-SiO2 xerogels were prepared containing PETN content ranging from 50 per cent to 90 per cent (w/w and the xerogels were characterised using different techniques. An exothermic peak at around 185 oC preceded by an endotherm in thermal analysis accompanied with weight loss in the temperature range from 150 oC to 200 oC   for the xerogel confirmed the presence of PETN in xerogel. Infrared spectra of xerogels showed peaks at around 1285 cm-1 and 1700 cm-1 assigned to O-NO2 and C-O bond representing PETN. Small angle x-ray scattering measurements on xerogels indicated that PETN entered in the pores of silica matrix. Transmission electron microscopy revealed that cystalline PETN    with particle size of around 15 nm dispersed in silica xerogel. The specific surface area for the PETN-SiO2 (90:10 xerogels was found to be 75 m2/g.Defence Science Journal, 2011, 61(6, pp.534-539, DOI:http://dx.doi.org/10.14429/dsj.61.594

Sanjay Vishwasrao Ingale

2011-10-01

406

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 (<25% by weight), the surfactant 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

407

Investigations in x-ray computed tomography polyacrylamide gel dosimetry  

International Nuclear Information System (INIS)

Polyacrylamide gels (PAGs) are radiosensitive materials currently under development for use as three-dimensional (3D) dosimeters in radiation therapy. Dose information is recorded in the gels and extracted through imaging. X-ray computed tomography (CT) has emerged as a promising gel imaging method due to a change in gel density that occurs upon irradiation. The accessibility of CT technology to cancer hospitals makes CT read out clinically attractive; however, the technique remains of limited clinical use due in part to poor dose resolution. This thesis investigates the use of CT for extracting dose information from PAGs with an overall goal of improving achievable dose resolution. Thesis results are divided into three studies: a gel-compositional study, a study of noise and dose resolution, and a digital filtering study. The first study investigates the effects of gel composition on PAG CT dose response and the underlying density change. Results indicate dramatic variation in CT dose response sensitivity and range with gel composition. A model is developed to describe gel density change with dose, revealing two fundamental properties of the density to dose response: the density change per unit polymer yield is highest for gels with low and high concentrations of crosslinking molecules, and dose response sensitivity is linearly dependent on the total concentration of monomers in the gel. The second study investigates strategies for minimizing noise in CT polymer gel es for minimizing noise in CT polymer gel dosimetry and assesses system performance. Specifically, the effects of phantom design, scanning technique, and voxel size on image noise are investigated and the effect of scanning protocol on imaging time is established. The dose resolution achievable with an optimized system is then calculated, given voxel size and imaging time constraints, and compared with published values for magnetic resonance imaging (MRI) and optical CT gel dosimetry. The third study investigates the potential of image filtering for improved dose resolution in CT gel dosimetry. CT image noise is characterized and appropriate filters are tested on a CT image of a PAG irradiated with a clinically relevant dose distribution. Filter performance is found to vary dramatically, with the best filters more than halving the dose resolution without significantly distorting the spatial distribution of dose. In summary, this thesis provides insight into the fundamental nature of PAG density to dose response, develops strategies for minimizing image noise, quantifies system performance, and demonstrates that digital image filtering is an effective tool to provide additional improvements to dose resolution

408

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

409

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

410

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

411

Self-oscillations in chemoresponsive gels: a theoretical approach.  

Science.gov (United States)

Some gels can swell or shrink in function of the concentration of the solutes contained in the solvent. We develop and discuss an algorithm based on Stefan-Maxwell equations to study the dynamics of a sphere of chemoresponsive gel immersed in a medium kept far from equilibrium. We show that the coupling of the reaction with these volume changes creates some feedback that can lead to chemomechanical instabilities. As a result, a reaction that is not oscillatory in homogeneous conditions or in a nonresponsive gel can induce self-oscillations of volume and concentrations in a responsive gel. We also show that chemical oscillations related to long range activation can be strongly modified in such gels, even when the changes of volume are small. PMID:16035893

Boissonade, J

2005-06-01

412

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

413

Tetracaine gel vs EMLA cream for percutaneous anaesthesia in children  

DEFF Research Database (Denmark)

We have evaluated the anaesthetic effect of tetracaine gel 1 g, applied for 45 min, compared with EMLA cream 2 g, applied for 60 min, in a randomized, double-blind study in 60 children aged 3-15 yr. Venous cannulation was performed 15 min after removal of the EMLA cream (n = 20) and tetracaine gel (n = 20). Cannulation was performed up to 215 min after removal of the tetracaine gel in another 20 patients. Significantly lower pain scores were recorded by the children treated with tetracaine gel compared with EMLA cream (P <0.02). Forty to 45% of children in the tetracaine groups reported no pain compared with only 10% in the EMLA group. Only minor adverse effects were observed. We conclude that tetracaine gel provided effective, rapid, long-lasting and safe local anaesthesia, and was significantly better than EMLA cream in reducing pain during venous cannulation in children using the recommended application periods for both formulations.

RØmsing, Janne; Henneberg, S W

1999-01-01

414

[Role of the i-gel in emergency airway management].  

Science.gov (United States)

The i-gel is a relatively new supraglottic airway, which has been shown to be useful during general anesthesia, and it may have a potential role during cardiopulmonary resuscitation. In a manikin study, we have found that, compared with laryngeal mask airways, the i-gel was significantly easier and faster to insert, due mainly to no-necessity of cuff inflation. One possible difficulty in using the i-gel during cardiopulmonary resuscitation is that the device cannot be fixed with the Thomas Tube Holder (Laerdal Medical Japan KK, Tokyo, Japan). A specially tailored device for cardiopulmonary resuscitation, recently has become available. The pack includes the i-gel O2 (which has a side port for oxygen delivery), a suction catheter, a sachet containing lubrication jelly, and a fixation strap. We describe the role of the i-gel during emergency airway management. PMID:24783621

Ueshima, Hironobu; Asai, Takashi

2014-04-01

415

Adsorption Characteristics of Silica Gels Treated with Fluorinated Silylation Agents  

Science.gov (United States)

Branched-chain polyfluorosilane (monochlorodimethyl[4,4-bis(trifluoromethyl)-5,5,6,6,7,7,7-heptafluoroheptyl)-bonded silica gels were prepared. The surface properties of the silica gels modified with various organic silanes were evaluated by the adsorption density of polar and nonpolar gases calculated from adsorption isotherms of nitrogen, carbon dioxide, and normal butane gases. The polyfluorocarbon-bonded silica gel surface was found to be both hydrophobic and oleophobic in nature, whereas the hydrocarbon-bonded silica gel surface was characterized only as hydrophobic. The trifunctional fluorinated silane provides the silica gel surface with a more hydrophilic nature than the monofunctional silane because of the formation of a denser polymeric coating layer with a larger number of silanols. PMID:9056313

Monde; Nakayama; Yano; Yoko; Konakahara

1997-01-01

416

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)

417

Fricke Gel Dosimeter Tissue-Equivalence a Monte Carlo Study  

Science.gov (United States)

Gel dosimetry has proved to be a valuable technique for absorbed dose distribution measurements in radiotherapy. FriXy-gel dosimeters consist of Fricke (ferrous sulphate) solution infused with xylenol orange. The solution is incorporated to a gel matrix in order to fix it to a solid structure allowing good spatial resolution and is imaged with a transportable optical system, measuring visible light transmittance before and after irradiation. This paper presents an evaluation of total photon mass attenuation coefficients at energies in the range of 50 keV-10MeV for the radiochromic FriXy gel dosimeter sensitive material. Mass attenuation coefficient estimations have been performed by means of Monte Carlo (PENELOPE) simulations. These calculations have been carried out for the FriXy gel sensitive material as well as for soft tissue (ICRU) and pure liquid water; a comparison of the obtained data shows good agreement between the different materials.

Valente, M.; Bartesaghi, G.; Gambarini, G.; Brusa, D.; Castellano, G.; Carrara, M.

2008-06-01

418

Use of chitosan gel for the purification of protein  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study was to optimize the preparation of chitosan gel and to use it for protein purification. The optimized preparation parameters were chitosan concentration 2.0%, glutaraldehyde concentration 0.6%, low cross-linking rate, NaOH concentration 1.6%, amount of NaBH4 0.4 g. In order to use the chitosan gel, the elution conditions were optimized as follows. NaCl concentration 0.05 mol/L in the tris-HCl (pH 9.05 at the flow rate of 2.03.0 mL/min. Particle size of chitosan gel was 120-140 µm. Neutral protease could be separated into four ingredients through chitosan gel column. The yield of enzyme was more than 90%. Albumin bovine serum could be separated into two ingredients through gel column and the total yield of albumin bovine serum was more than 70%.

ZhenXing Tang

2007-03-01

419

Surface coverage of polyaniline-coated silica gels  

International Nuclear Information System (INIS)

Silica gels of 15 ?m and 130 ?m mean sizes were covered by polyaniline hydrochloride nanofilms during polymerisation under different conditions. A surface coverage of the silica gel was determined from the C 1s or N 1s photoelectron spectra by two methods. The first one, the line shape analysis carried out by QUASES-Tougaard software, enables us to recognise also the surface morphology of the samples. The second method for the C 1s or N 1s peak area ratios originating from the polyaniline hydrochloride-coated silica gels an from the polyaniline hydrochloride standard. The results indicate that silica gel surfaces are not fully covered by the polyaniline hydrochloride film. The coverage values are consistent mutually, correlate well with polymerisation conditions and are in good agreement with a polyaniline hydrochloride content determined independently by burning the polyaniline hydrochloride-coated silica gel samples (Authors)

420

Formaldehyde increases MAGIC gel dosimeter melting point and sensitivity  

International Nuclear Information System (INIS)

Polymeric gel dosimeters are being used to verify three-dimensional (3D) dose distributions of different types of radiotherapy treatments, especially the most complexes ones. An important factor that can limit the wider use of this kind of dosimeter is temperature, as gel melting can destroy 3D information. This work shows that adding formaldehyde to the gel preparation increases the melting point, allowing its use in warmer environments, including up to body temperature. An addition of 3% in mass of the formaldehyde solution to a MAGIC type gel dosimeter increased its melting point from 25 to 69 deg. C. Also important were a 12.5% increase in gel sensitivity and an expressive decrease in relaxation rate R2 uncertainty. (note)

421

Formaldehyde increases MAGIC gel dosimeter melting point and sensitivity  

International Nuclear Information System (INIS)

Polymeric gel dosimeters are being used to verify three-dimensional (3D) dose distributions of different types of radiotherapy treatments, especially the most complexes ones. An important factor that can limit the wider use of this kind of dosimeter is temperature, as gel melting can destroy 3D information. This work shows that the addition of formaldehyde to the gel preparation increases the melting point, allowing its use in warmer environments, including up to body temperature. An addition of 3% in mass of the formaldehyde solution to a MAGIC type gel dosimeter increased its melting point from 25 to 69 deg. C. Also important were a 10.5% increase in gel sensitivity and an expressive decrease in relaxation rate R2 uncertainty that added to the agreement of the depth dose distribution measurement with the expected dosimetric data of the LINAC show the potential applicability of this new dosimeter for 3D dose verification.

422

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)

423

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

424

A rotating disk electrokinetic method for characterizing polyelectrolyte pharmaceutical gels.  

Science.gov (United States)

Charge groups in polyelectrolyte gels can affect the entrapment and release of ionic drugs as well as influencing the stability of colloidal and nanoparticulate drug delivery systems. An accurate knowledge of gel charge properties is therefore important to the understanding and design of such drug delivery systems. Existing rotating disk method for quantifying the surface potential of flat surfaces is based on the classical electrokinetic model that neglects the effect of surface conductivity and is therefore only applicable to ion-impenetrable hard surfaces. This classical electrokinetic model would be inaccurate for polyelectrolyte gel systems involving ion-penetrable charged layers or "soft" surfaces. In this study, we developed a new rotating disk model for characterizing charge properties of ion penetrable soft surfaces and tested it on polyvinyl alcohol (PVA)/polyacrylic acid (PAA), gelatin, and gelatin/PAA polyelectrolyte gels. In addition to classical electrokinetic parameters, the contribution of surface conductivity known to be very significant for soft and ion-penetrable gel surfaces has been taken into account in this new rotating disk model. Based on this new approach, two rotating gel disks of different radius but with identical gel composition and preparation procedures were employed for determining the gel surface potential and density of fixed charge groups. A comparison of the resulting data with that obtained from existing rotating disk model ignoring the surface conductivity reveals a significant underestimation of the gel surface potential and the density of fixed charge groups by the ion-impenetrable hard surface approach. Our results thus confirm that the contribution of surface conductivity is significant in the electrokinetic characterization of polyelectrolyte gels that can be evaluated with our new rotating disk model. PMID:22342387

Qu, Beibei; Lee, Ping I

2012-05-01

425

Improved gel electrophoresis matrix for hydrophobic protein separation and identification.  

Science.gov (United States)

We propose an improved acrylamide gel for the separation of hydrophobic proteins. The separation strategy is based on the incorporation of N-alkylated and N,N'-dialkylated acrylamide monomers in the gel composition in order to increase hydrophobic interactions between the gel matrix and the membrane proteins. Focusing on the most efficient monomer, N,N'-dimethylacrylamide, the potentiality of the new matrix was evaluated on membrane proteins of the human colon HCT-116 cell line. Protein analysis was performed using an adapted analytical strategy based on FT-ICR tandem mass spectrometry. As a result of this comparative study, including advanced reproducibility experiments, more hydrophobic proteins were identified in the new gel (average GRAVY: -0.085) than in the classical gel (average GRAVY: -0.411). Highly hydrophobic peptides were identified reaching a GRAVY value up to 1.450, therefore indicating their probable locations in the membrane. Focusing on predicted transmembrane domains, it can be pointed out that 27 proteins were identified in the hydrophobic gel containing up to 11 transmembrane domains; in the classical gel, only 5 proteins containing 1 transmembrane domain were successfully identified. For example, multiple ionic channels and receptors were characterized in the hydrophobic gel such as the sodium/potassium channel and the glutamate or the transferrin receptors whereas they are traditionally detected using specific enrichment techniques such as immunoprecipitation. In total, membrane proteins identified in the classical gel are well documented in the literature, while most of the membrane proteins only identified on the hydrophobic gel have rarely or never been described using a proteomic-based approach. PMID:21078288

Tokarski, Caroline; Fillet, Marianne; Rolando, Christian

2011-03-01

426

Dewatering fine coal slurries by gel extraction. Final report  

Energy Technology Data Exchange (ETDEWEB)

A new technology called gel extraction has been evaluated to determine its economic viability in dewatering the fine and ultrafine coal slurries generated upon separation of sulfur and ash from clean coal during the physical coal cleaning process. Water must be removed from such slurries prior to transportation and combustion but the dewatering costs are substantial, especially for the fine particles below 28 mesh (0.6 mm). Gel extraction is a potential breakthrough in slurry dewatering technology. The goal of this project was to acquire the qualitative and quantitative data needed to estimate the potential of gel extraction for dewatering coal slurries. The specific objectives were to determine the maximum extents of dewatering (minimum surface moisture in the coal product), the clarity of the water removed (minimum solids content), the speed of the dewatering cycles, the service lifetime of the gels, and the factors which influence all of these. With the results obtained, an economic analysis of Ohio coal cleaning plant dewatering technologies was carried out. The polymer gel at the heart of this project, poly (N-isopropylacrylamide) (PNIPA), can swell several times its shrunken weight at 32{degrees}C by absorbing water at 25{degrees}C. In gel extraction, a shrunken NIPA gel is contacted with a slurry at ambient temperature or cooler; the gel swells by absorbing water from the slurry. The gel is then removed from the dewatered slurry and warmed above its critical temperature of 33{degrees}C, which returns it to the shrunken state by releasing the absorbed water. The facts that the gel is reusable and the process is simple and driven by low-grade energy (warm temperatures), and not inherently limited by particle size, made the process an attractive possible alternative to centrifugation, screening, filtration, etc. for slurry dewatering.

Gehrke, S.H.; Lyu, Lii-Hurng

1990-12-31

427

Performance of external microwave applicators measured in Guy gel and agar-saline gel  

International Nuclear Information System (INIS)

Before any predictions can be made about temperature patterns from an external microwave applicator, it is necessary to know the specific absorption rate (SAR) distribution of the applicator in a medium. To do this, a sufficient forward power of 915 MHz microwaves was delivered and the temperature rise in the medium at various depths was recorded for the first 40 seconds after the power was turned on. This was repeated at 1 cm intervals along the two perpendicular axes of the applicator. SAR distributions of several commercially available applicators were compared in a muscle equivalent Guy gel and an agar-saline gel. Applicators with the same aperture size may have different SAR distributions due to different construction design. The SAR distribution measured in the two media did not differ significantly, suggesting that the agar gel may have some utility in characterizing microwave applicators. In addition, the agar-saline phantom can be used in a steady state phantom for the measurement of temperature distribution patterns. The steady state method allows a rapid and detailed field mapping of the microwave applicator

428

Tuning viscoelastic properties of supramolecular peptide gels via dynamic covalent crosslinking.  

Science.gov (United States)

A dynamic covalent crosslinking approach is used to crosslink supramolecular peptide gels. This novel approach facilitates tuning viscoelastic properties of the gel and enhances mechanical stability (storage modulus exceeding 10(5) Pa) of the peptide gels. PMID:25566850

Khalily, Mohammad Aref; Goktas, Melis; Guler, Mustafa O

2015-02-01

429