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Sample records for gel immunodiffusion agid

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

    Directory of Open Access Journals (Sweden)

    Malovrh Tadej

    2005-01-01

    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.

  2. Eradication of bovine leukemia virus infection in commercial dairy herds using the agar gel immunodiffusion test.

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    Shettigara, P. T.; Samagh, B S; Lobinowich, E M

    1986-01-01

    Demands for bovine leukemia virus test negative breeding cattle and for semen from bovine leukemia virus test negative bulls by several countries have encouraged the eradication of bovine leukemia virus infection from selected herds in Canada. This project was undertaken to evaluate the suitability of the agar gel immunodiffusion test, standardized to detect anti-bovine leukemia virus glycoprotein antibodies, for eradication of bovine leukemia virus from commercial dairy herds. Of nine partic...

  3. Control of bovine leukemia virus infection in dairy herds by agar gel immunodiffusion test and segregation of reactors.

    OpenAIRE

    Shettigara, P. T.; Samagh, B S; Lobinowich, E M

    1989-01-01

    Canadian cattle intended for export, in future, may have to originate from herds which are serologically negative for bovine leukemia virus, in addition to being negative individually by the agar gel immunodiffusion test as currently required. In this study, agar gel immunodiffusion testing of herds and segregation of reactors were examined. The results demonstrated that bovine leukemia virus infection could be controlled when three groups: 1) bovine leukemia virus-positive, 2) bovine leukemi...

  4. Comparison of an agar-gel immunodiffusion test with other serological methods for differentiating Brucella infected from vaccinated cattle.

    OpenAIRE

    Mcmahon, K. J.

    1983-01-01

    An agar-gel immunodiffusion test was compared with other serological tests for detection of antibodies in the sera of 48 cattle vaccinated with Brucella abortus strain 19. Two hundred forty-two sera were tested over a 12 month period, and addition of positive reactions for each test resulted in totals of 170 for the card test, 74 for the standard tube-agglutination test, 71 for the 2-mercaptoethanol test, 64 for the dithiothreitol test and 22 for the agar-gel immunodiffusion test.

  5. Improvements to the hemagglutination inhibition test for serological assessment of recombinant fowlpox-H5-avian-influenza vaccination in chickens and its use along with an agar gel immunodiffusion test for differentiating infected from noninfected vaccinated animals.

    Science.gov (United States)

    Swayne, David E; Avellaneda, Gloria; Mickle, Thomas R; Pritchard, Nikki; Cruz, Julio; Bublot, Michel

    2007-09-01

    In general, avian influenza (AI) vaccines protect chickens from morbidity and mortality and reduce, but do not completely prevent, replication of wild AI viruses in the respiratory and intestinal tracts of vaccinated chickens. Therefore, surveillance programs based on serological testing must be developed to differentiate vaccinated flocks infected with wild strains of AI virus from noninfected vaccinated flocks in order to evaluate the success of vaccination in a control program and allow continuation of national and international commerce of poultry and poultry products. In this study, chickens were immunized with a commercial recombinant fowlpox virus vaccine containing an H5 hemagglutinin gene from A/turkey/Ireland/83 (H5N8) avian influenza (AI) virus (rFP-H5) and evaluated for correlation of immunological response by hemagglutination inhibition (HI) or agar gel immunodiffusion (AGID) tests and determination of protection following challenge with a high pathogenicity AI (HPAI) virus. In two different trials, chickens immunized with the rFP-H5 vaccine did not develop AGID antibodies because the vaccine lacks AI nucleoprotein and matrix genes, but 0%-100% had HI antibodies, depending on the AI virus strain used in the HI test, the HI antigen inactivation procedure, and whether the birds had been preimmunized against fowlpox virus. The most consistent and highest HI titers were observed when using A/turkey/Ireland/83 (H5N8) HPAI virus strain as the beta-propiolactone (BPL)-inactivated HI test antigen, which matched the hemagglutinin gene insert in the rFP-H5 vaccine. In addition, higher HI titers were observed if ether or a combination of ether and BPL-inactivated virus was used in place of the BPL-inactivated virus. The rFP-H5 vaccinated chickens survived HPAI challenge and antibodies were detected by both AGID and HI tests. In conclusion, we demonstrated that the rFP-H5 vaccine allowed easy serological differentiation of infected from noninfected birds in vaccinated populations of chickens when using standard AGID and HI tests. PMID:17992929

  6. Development of a polymerase chain reaction and its comparison with agar gel immunodiffusion test in the detection of bovine leukemia virus infection / Desenvolvimento de uma reação em cadeia pela polimerase e comparação com a imunodifusão em gel de agar na detecção de infecções pelo vírus da leucemia bovina

    Scientific Electronic Library Online (English)

    Marcelo Fernandes, Camargos; Daniel, Stancek; Leandro Moreira, Lessa; Jenner Karlisson Pimenta, Reis; Maurílio Andrade, Rocha; Rômulo Cerqueira, Leite.

    Full Text Available A reação em cadeia pela polimerase (PCR) foi utilizada para a detecção do vírus da leucemia bovina (VLB) em leucócitos periféricos de bovinos infectados. Os iniciadores utilizados foram construídos para amplificar uma parte do gene env do VLB. Os produtos da PCR foram analisados por eletroforese em [...] gel de agarose corados por brometo de etídeo. A especificidade analítica da PCR foi confirmada por restrição enzimática dos produtos da reação com Bam HI e também pela análise da seqüência de três amostras. Sessenta e cinco animais foram testados para a presença de anticorpos anti-VLB, pela imunodifusão em gel de agar (IDGA) e pela PCR, para detecção direta do VLB. Houve 73,80% de concordância entre os dois testes. Quatro animais positivos na IDGA foram PCR negativos, enquanto 13 animais negativos na IDGA foram positivos na PCR. A sensibilidade diagnóstica obtida foi de 0,87 e a especificidade diagnóstica 0,62. A PCR desenvolvida pode ser uma ferramenta complementar no diagnóstico de infecções causadas pelo VLB, mas deve ter sua sensibilidade diagnóstica melhorada. Abstract in english Polymerase chain reaction (PCR) was used for bovine leukemia virus (BLV) detection in the peripheral leukocytes of the infected bovines. The primers used were designed to amplify a part of env gene of BLV. PCR products were analyzed by agarose gel electrophoresis stained by ethidium bromide. The ana [...] lytical specificity of PCR was confirmed by enzymatic restriction analysis of the PCR product with Bam HI and also by nucleotide sequence analysis of three PCR samples. Sixty five animals were tested for anti-BLV antibody, by agar gel-immunodiffusion test (AGID) and for direct BLV detection by PCR. There was a 73.80% concordance rate between the two tests. Four animals positive in AGID were PCR negative, while 13 AGID negative animals were found PCR positive. PCR got a 0.87 diagnosis sensitivity and 0.62 specificity. The developed PCR may be complementary tool in the diagnosis of BLV infection, but should have it diagnosis sensitivity improved.

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

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    A. Manicavasaka Dinakaran

    2010-10-01

    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

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

    OpenAIRE

    A. Manicavasaka Dinakaran; G. Selvaraju; K. Jayalakshmi; T.R. Gopalakrishna Murthy; M. Geetha and S. Saravanan

    2010-01-01

    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 subjec...

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

    Scientific Electronic Library Online (English)

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

    2012-06-01

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

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

    Scientific Electronic Library Online (English)

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

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

  11. Evaluation of the Double Agar Gel Immunodiffusion Test and of the Enzyme-Linked Immunosorbent Assay in the Diagnosis and Follow-Up of Patients with Chronic Pulmonary Aspergillosis

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    de Azevedo, Priscila Zacarias; Sylvestre, Tatiane Fernanda; Cavalcante, Ricardo de Souza; de Carvalho, Lídia Raquel; Moris, Daniela Vanessa; de Oliveira, Maria Luiza Cotrim Sartor; Mendes, Rinaldo Poncio

    2015-01-01

    The diagnosis of chronic pulmonary aspergillosis (CPA) depends on the radiologic image and the identification of specific antibodies. The present study aimed to evaluate accuracy parameters of enzyme-linked immunosorbent assay (ELISA) and of the determination of serum galactomannan level in the diagnosis of patients with CPA, comparing these results with the double agar gel immunodiffusion (DID) test. In addition, the prevalence of cross-reactivity and the serological progression after treatment were evaluated by comparing DID and ELISA. Six study groups were formed: G1: 22 patients with CPA, 17 of whom had Aspergillus fungus ball, one chronic cavitary pulmonary aspergillosis (CCPA) and four chronic fibrosing pulmonary aspergillosis (CFPA); G2: 28 patients with pulmonary tuberculosis (TB); G3: 23 patients with histoplasmosis (HST); G4: 50 patients with paracoccidioidomycosis (PCM); G5: 20 patients with cryptococcosis (CRC); and G6: 200 healthy controls. Serum antibodies were measured by DID and ELISA, with two antigen preparations—Aspergillus fumigatus (DID1, ELISA1) and a pool of A. fumigatus, A. flavus and A. niger antigens (DID2, ELISA2). The Platélia Aspergillus Enzyme Immunoassay (EIA) kit was used to measure galactomannan. The cut-off points of ELISA were determined for each antigen preparation and for the 95% and 99% confidence intervals. Despite the low sensitivity, DID was the technique of choice due to its specificity, positive and negative predictive values and positive likelihood ratio–especially with the antigen pool and due to the low frequency of cross-reactivity. ELISA1 and a 0.090 cut-off showed high sensitivity, specificity and negative predictive value, but a high frequency of cross-reactivity with CRC. The best degree of agreement was observed between ELISA1 and ELISA2. The detection of serum galactomannan showed high sensitivity, comparable to ELISA2. The immunodiffusion test showed an excellent relationship with the progression after treatment, which made it the reaction of choice for patient follow-up. PMID:26271000

  12. Immunodiffusion test for serodiagnosing subcutaneous zygomycosis.

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

    1990-01-01

    Culture filtrate antigens of Basidiobolus ranarum and Conidiobolus coronatus were analyzed by immunodiffusion (ID) with homologous rabbit antisera. B. ranarum and C. coronatus were each found to have five specific antigens. Results of tests with heterologous antisera indicated that all of the species shared at least one antigen. ID tests incorporating the specific precipitin bands as references were developed for detection of basidiobolomycosis and conidiobolomycosis. These tests were perform...

  13. 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

    Scientific Electronic Library Online (English)

    R, Felmer; J, Zúñiga; M, Recabal.

    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. 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.

  14. Immunodiffusion test for serodiagnosing subcutaneous zygomycosis.

    Science.gov (United States)

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

    1990-01-01

    Culture filtrate antigens of Basidiobolus ranarum and Conidiobolus coronatus were analyzed by immunodiffusion (ID) with homologous rabbit antisera. B. ranarum and C. coronatus were each found to have five specific antigens. Results of tests with heterologous antisera indicated that all of the species shared at least one antigen. ID tests incorporating the specific precipitin bands as references were developed for detection of basidiobolomycosis and conidiobolomycosis. These tests were performed with sera from humans and horses with proven basidiobolomycosis and conidiobolomycosis as well as with control sera from humans and animals with and without heterologous mycotic and oomycotic infections. Only sera from cases of basidiobolomycosis and conidiobolomycosis produced lines of identity with the reference precipitates of B. ranarum and C. coronatus, respectively. The ID tests were found to be completely sensitive and specific for determining the etiology of zygomycosis caused by these two species. In addition they appeared useful for monitoring resolution of the infections. Images PMID:2121787

  15. Use of monoclonal antibodies against avian retroviral protein p19 for competitive radioimmunoassay and immunodiffusion

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    Polakova, K. (Slovenska Akademia Vied, Bratislava (Czechoslovakia). Vyskumny Ustav Onkologicky); Russ, G.; Styk, B. (Institute of Virology, Slovak Academy of Sciences, Bratislava (Czechoslovakia))

    1983-01-01

    Monoclonal antibodies were used in competitive binding assays to investigate the arrangement of three epitopes on protein p19 of the avian myeloblastosis virus (AMV). It is reasoned that if the epitopes recognized by two monoclonal antibodies are physically close, the binding of one antibody will sterically block the binding of the other; conversely no blocking will occur if the epitopes are sufficiently distant. The results of these competitive binding assays demonstrated the presence of two distinct antigenic sites on protein p19. The monoclonal antibodies against protein p19 of AMV were also tested in gel double immunodiffusion. Since p19 protein shows strong tendency to aggregate, it was not surprising that clear precipitin lines with these monoclonal antibodies were obtained.

  16. Detection of BLV infection by ELISA and PCR

    International Nuclear Information System (INIS)

    The aim of the present study was the detection of bovine leukemia virus (BLV) infection by the serological test (ELISA, agar gel immunodiffusion (AGID)) and direct detection of proviral DNA in peripheral blood mononuclear cells (PCR test). Sixty cows from a herd naturally infected with BLV and 24 animals from a healthy herd were selected for this study

  17. The coccidioidal complement fixation and immunodiffusion-complement fixation antigen is a chitinase.

    OpenAIRE

    Johnson, S M; Pappagianis, D.

    1992-01-01

    Culture filtrates and autolysates of Coccidioides immitis have provided suitable crude antigens for the serodiagnosis and prognosis of coccidioidomycosis. One of these, a heat-labile antigen which participates in the immunodiffusion reaction corresponding to the complement fixation reaction (IDCF), has been characterized as a 110-kDa native protein that, when subjected to reducing conditions and heat, yields a 48-kDa component. The present report provides serologic and biochemical evidence th...

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

    OpenAIRE

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

    1982-01-01

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

  19. Isolation of caprine arthritis encephalitis virus from goats in Mexico.

    OpenAIRE

    Daltabuit Test, M; de la Concha-Bermejillo, A.; Espinosa, L E; Loza Rubio, E; Aguilar Setién, A

    1999-01-01

    A lentivirus was isolated from 2 goats in Mexico that were seropositive to caprine arthritis encephalitis virus (CAEV) by the agar gel immunodiffusion (AGID) test. The lentivirus was identified as CAEV by the observation of giant multinucleated cells (syncytia) in goat synovial membrane (GSM) monolayers co-cultivated with blood mononuclear (BMN) cells from the seropositive goats, and by amplifying a DNA segment of the CAEV gag gene using the polymerase chain reaction (PCR) technique. Subseque...

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

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    O. Yapkic

    2007-05-01

    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.

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

    OpenAIRE

    Luz Elena Cano; Angela Restrepo

    1987-01-01

    A serologic study was undertaken in a group of 43 patients with active paracoccidioidomycosis who were treated in the same form (ketoconazole), for identical periods of time (6 months), and folio wed-up for various periods posttherapy. The tests employed were agar gel immunodiffusion (AGID) and complement fixation (FC). Also studied were 50 sera from patients with proven histoplasmosis and pulmonary aspergilloma, 30 patients with culturaly proven tuberculosis as well as 92 specimens from heal...

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

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    MICELI Graciela S.

    2000-01-01

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

  3. Development and Evaluation of an Immunodiffusion Test for Diagnosis of Systemic Zygomycosis (Mucormycosis): Preliminary Report

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    Jones, Kenneth W.; Kaufman, Leo

    1978-01-01

    An antigen analysis with filtrate and homogenate precipitinogens of single isolates of the zygomycetes Absidia corymbifera, Mucor pusillus, Rhizopus arrhizus, and Rhizopus oryzae demonstrated the presence of common antigens among the three genera as well as antigens which permit their differentiation. Selected homogenate antigens were valuable in developing a diagnostic immunodiffusion (ID) test for systemic zygomycosis. When sera from 43 patients with various proven mycoses other than zygomycosis were tested against each of the antigens, none formed precipitin bands identical to those formed by A. cormybifera, M. pusillus, and the Rhizopus spp. rabbit reference antisera. Sera from 23 normal persons and 25 diabetics did not react with any of the antigens. Homogenate antigens detected antibody in 8 of the 11 sera (73%) from suspected or proven cases of zygomycosis, whereas ID tests with filtrate antigens detected antibody in only 2 of the 11 sera (18%). Of the eight sera that reacted with the homogenate antigens, five only reacted with a specific Rhizopus sp. antigen, two only reacted with a specific M. pusillus antigen, and one only reacted with a specific A. corymbifera antigen. Study results show the ID test with homogenate antigens to be more specific and sensitive than the ID test with filtrate antigens and indicate that the former is a promising technique for diagnosing human zygomycosis. Images PMID:75212

  4. Electroimmunoassay, radioimmunoassay, and radial immunodiffusion assay evaluated for quantification of human apolipoprotein B

    International Nuclear Information System (INIS)

    We examined three immunoassay techniques for measuring apolipoprotein B in serum and major lipoprotein density fractions from normolipidemic and hyperlipoproteinemic persons, comparing values by electroimmunoassay, radioimmunoassay, and radial immunodiffusion assay with those determined gravimetrically. Electroimmunoassay is faster and simpler than radioimmunoassay, and equally precise (within- and between-assay coefficients of variation for both were 5 and 7%, respectively). All the immunoassays gave results that agreed with those by gravimetry for normolipidemic sera and the corresponding lipoprotein density fractions, but only electroimmunoassay results agreed with those by gravimetry for apolipoprotein B in lipoproteins of d < 1.019 g/ml isolated from hypertriglyceridemic patients. Concentrations of apolipoprotein B in plasma, determined by electroimmunoassay in a population of normal persons and patients with primary hyperlipoproteinemias, were: normals, 980 +- 200; type 1, 700 +- 160; type IIa, 2000 +- 260; type IIb, 2180 +- 300; type III, 1300 +- 340; type IV, 1470 +- 400; and type V, 1550 +- 390 mg/liter (mean +- SD). Lipoprotein density fractions from the hyperlipoproteinemic patients each had a characteristic distribution of free and associated forms of lipoprotein family B. The absolute concentration and distribution of apolipoprotein B between the free and associated forms of lipoprotein B may represent a useful indicator of the underlying biochemical defect

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

    International Nuclear Information System (INIS)

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

  6. Evaluation of western blotting for the diagnosis of enzootic bovine leukemia

    Directory of Open Access Journals (Sweden)

    Gonzalez E.T.

    1999-01-01

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

  7. 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

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

    Science.gov (United States)

    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

    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.

  9. 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)

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

    2010-02-01

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

  10. Fundamentals of gel dosimeters

    International Nuclear Information System (INIS)

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

  11. 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

    OpenAIRE

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

    2000-01-01

    The RID assay is one of the in vitro methods used for in-process control in the production of rabies vaccines for veterinary use. It has been shown to be very useful for determining antigen concentration in the final bulk product. The work presented in this paper, including the production and standardization of candidate standard reagents for use in the Radial Immunodiffusion Assay (RID) was carried out at the Pan American Institute for Food Protection and Zoonoses (INPPAZ/PAHO/WHO). The stud...

  12. Functional molecular gels

    CERN Document Server

    Miravet, Juan F; Butt, Hans-Jurgen

    2013-01-01

    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, t

  13. Sol-Gel Glasses

    Science.gov (United States)

    Mukherjee, S. P.

    1985-01-01

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

  14. CONFORMANCE IMPROVEMENT USING GELS

    Energy Technology Data Exchange (ETDEWEB)

    Randall S. Seright

    2003-09-01

    This report describes work performed during the second year of the project, ''Conformance Improvement Using Gels.'' The project has two objectives. The first objective is to identify gel compositions and conditions that substantially reduce flow through fractures that allow direct channeling between wells, while leaving secondary fractures open so that high fluid injection and production rates can be maintained. The second objective is to optimize treatments in fractured production wells, where the gel must reduce permeability to water much more than that to oil. Pore-level images from X-ray computed microtomography were re-examined for Berea sandstone and porous polyethylene. This 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.

  15. Seroepidemiology of Paracoccidioides brasiliensis infection in horses from Rio Grande do Sul, Brazil

    Scientific Electronic Library Online (English)

    Ana Paula Neuschrank, Albano; Gabriel Baracy, Klafke; Tchana Martinez, Brandolt; Vanusa Pousada, Da Hora; Carlos Eduardo Wayne, Nogueira; Melissa Orzechowski, Xavier; Mário Carlos Araújo, Meireles.

    2015-06-01

    Full Text Available Paracoccidioides brasiliensis is the etiological agent of the major systemic mycosis in Brazil, called paracoccidioidomycosis. Although the Rio Grande do Sul is considered an endemic area of the disease, there are few studies on the ecology of P. brasiliensis in the state. Therefore, this study aime [...] d to evaluate the infection of P. brasiliensis in horses from the mesoregion of Southwest Riograndense, using these animals as sentinels. Serological techniques, such as double immunodiffusion in agar gel (AGID) and indirect ELISA, were performed to detect the anti-gp43 P. brasiliensis antibody in horses from five different farms in the region of Bagé, RS, Brazil. Serology was performed in 200 Pure Blood English horses up to two years of age that were born and raised exclusively at the farms. Of these horses, 12% had anti-gp43 antibodies according to the ELISA results, with rates ranging from 0 to 30% according to the farm of origin (p

  16. Preparation of chitosan gel

    Directory of Open Access Journals (Sweden)

    Lagerge S.

    2012-06-01

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

  17. Mechanochromic photonic gels.

    Science.gov (United States)

    Chan, Edwin P; Walish, Joseph J; Urbas, Augustine M; Thomas, Edwin L

    2013-08-01

    Polymer gels are remarkable materials with physical structures that can adapt significantly and quite rapidly with changes in the local environment, such as temperature, light intensity, electrochemistry, and mechanical force. An interesting phenomenon observed in certain polymer gel systems is mechanochromism - a change in color due to a mechanical deformation. Mechanochromic photonic gels are periodically structured gels engineered with a photonic stopband that can be tuned by mechanical forces to reflect specific colors. These materials have potential as mechanochromic sensors because both the mechanical and optical properties are highly tailorable via incorporation of diluents, solvents, nanoparticles, or polymers, or the application of stimuli such as temperature, pH, or electric or strain fields. Recent advances in photonic gels that display strain-dependent optical properties are discussed. In particular, this discussion focuses primarily on polymer-based photonic gels that are directly or indirectly fabricated via self-assembly, as these materials are promising soft material platforms for scalable mechanochromic sensors. PMID:23754505

  18. Polymer gel dosimetry

    International Nuclear Information System (INIS)

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

  19. CONFORMANCE IMPROVEMENT USING GELS

    Energy Technology Data Exchange (ETDEWEB)

    Randall S. Seright

    2004-09-30

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

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

    Scientific Electronic Library Online (English)

    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

    Full Text Available 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.

  1. Structure of mineral gels

    International Nuclear Information System (INIS)

    Small Angle Neutron Scattering (SANS) measurements have been performed to investigate the nanoscale structure of materials of the systems xTiO2-(1-x)SiO2 and xZrO2-(1-x)SiO2 with x ? 10 mol % at different processing stages. The materials were prepared by sol-gel using the alkoxides method, in strong acidic conditions. Samples were studied as xerogels heat-treated at 120 and 850 deg. C and as wet gels at gel point and after aging. All samples showed identical microstructure at gel point, extended linear chains ?10 nm long. The aged gel has a mass fractal structure with fractal dimension of 1.7 - 1.9. The 120 deg. C heat-treated xerogels show homogeneous oxide regions with mass fractal structure. For the 850 deg. C heat-treated xerogel the oxide regions average size has reduced and it has densified as compared to 120 deg. C heat-treated sample. (author)

  2. Spatially resolved multicomponent gels.

    Science.gov (United States)

    Draper, Emily R; Eden, Edward G B; McDonald, Tom O; Adams, Dave J

    2015-10-01

    Multicomponent supramolecular systems could be used to prepare exciting new functional materials, but it is often challenging to control the assembly across multiple length scales. Here we report a simple approach to forming patterned, spatially resolved multicomponent supramolecular hydrogels. A multicomponent gel is first formed from two low-molecular-weight gelators and consists of two types of fibre, each formed by only one gelator. One type of fibre in this 'self-sorted network' is then removed selectively by a light-triggered gel-to-sol transition. We show that the remaining network has the same mechanical properties as it would have done if it initially formed alone. The selective irradiation of sections of the gel through a mask leads to the formation of patterned multicomponent networks, in which either one or two networks can be present at a particular position with a high degree of spatial control. PMID:26391086

  3. Active Polymer Gel Actuators

    Directory of Open Access Journals (Sweden)

    Shuji Hashimoto

    2010-01-01

    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.

  4. Evaluation of an enzyme immunoassay for antibodies to a recombinant Blastomyces adhesin-1 repeat antigen as an aid in the diagnosis of blastomycosis in dogs.

    Science.gov (United States)

    Mourning, Alyssa C; Patterson, Edward E; Kirsch, Emily J; Renschler, Janelle S; Wolf, Linda A; Paris, Jasmin K; Durkin, Michelle M; Wheat, Lawrence J

    2015-11-15

    Objective-To evaluate the sensitivity and specificity of an enzyme immunoassay (EIA) for antibodies to a recombinant Blastomyces adhesin-1 repeat antigen (rBAD-1) to aid in the diagnosis of blastomycosis in dogs and compare the findings with results from other tests used for this purpose. Design-Prospective analytic study. Sample-Serum and urine from 70 dogs with and without blastomycosis. Procedures-Serum and urine samples were collected from dogs with blastomycosis (n = 21), histoplasmosis (8), or nonfungal pulmonary disease (21) and from healthy control dogs living in a blastomycosis-endemic area (20). Serum was tested for antibodies against Blastomyces dermatitidis with the rBAD-1 antibody EIA and an A-antigen antibody agar gel immunodiffusion (AGID) assay. Serum and urine were tested for B dermatitidis antigen with a quantitative EIA. Results-Sensitivity of the quantitative antigen EIA was 100% in serum and urine samples from dogs with blastomycosis, with specificity of 95% in urine samples from dogs with nonfungal pulmonary disease and 100% in urine samples from healthy dogs. Sensitivity of the rBAD-1 antibody EIA (95%) was significantly greater than that of the A-antigen antibody AGID assay (65%). Specificity of the antibody EIA was 88% in dogs with histoplasmosis, 95% in healthy dogs, and 100% in dogs with nonfungal pulmonary disease. Conclusions and Clinical Relevance-The rBAD-1 antibody EIA had greater sensitivity than the A-antigen antibody AGID assay in dogs with blastomycosis. This antibody EIA may assist in distinguishing histoplasmosis from blastomycosis. Further evaluation in a larger prospective study is needed to verify these results. PMID:26517616

  5. Electroblotting from Polyacrylamide Gels.

    Science.gov (United States)

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

    2015-01-01

    Transferring proteins from polyacrylamide gels onto retentive membranes is now primarily used for immunoblotting. A second application that was quite common up to about a decade ago was electroblotting of proteins for N-terminal and internal sequencing using Edman chemistry. This unit contains procedures for electroblotting proteins from polyacrylamide gels onto a variety of membranes, including polyvinylidene difluoride (PVDF) and nitrocellulose. In addition to the commonly used tank or wet transfer system, protocols are provided for electroblotting using semidry and dry systems. This unit also describes procedures for eluting proteins from membranes using detergents or acidic extraction with organic solvents for specialized applications. © 2015 by John Wiley & Sons, Inc. PMID:26521711

  6. Rheology of Active Gels

    Science.gov (United States)

    Chen, Daniel

    2015-03-01

    Active networks drive a diverse range of critical processes ranging from motility to division in living cells, yet a full picture of their rheological capabilities in non-cellular contexts is still emerging, e.g., How does the rheological response of a network capable of remodeling under internally-generated stresses differ from that of a passive biopolymer network? In order to address this and other basic questions, we have engineered an active gel composed of microtubules, bidirectional kinesin motors, and molecular depletant that self-organizes into a highly dynamic network of active bundles. The network continually remodels itself under ATP-tunable cycles of extension, buckling, fracturing, and self-healing. Using confocal rheometry we have simultaneously characterized the network's linear and non-linear rheological responses to shear deformation along with its dynamic morphology. We find several surprising and unique material properties for these active gels; most notably, rheological cloaking, the ability of the active gel to drive large-scale fluid mixing over several orders of flow magnitude while maintaining an invariant, solid-like rheological profile and spontaneous flow under confinement, the ability to exert micro-Newton forces to drive persistent directed motion of the rheometer tool. Taken together, these results and others to be discussed highlight the rich stress-structure-dynamics relationships in this class of biologically-derived active gels.

  7. Phase behaviors of agarose gel

    Science.gov (United States)

    Morita, Takaharu; Narita, Takayuki; Mukai, Sada-atsu; Yanagisawa, Miho; Tokita, Masayuki

    2013-04-01

    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.

  8. Seroprevalence for brucellosis and leptospirosis in dogs from Belém and Castanhal, State of Pará, Brazil / Soroprevalência para brucelose e leptospirose em cães de Belém e Castanhal, Pará, Brasil

    Scientific Electronic Library Online (English)

    Giselle Souza da, PAZ; Katarine de Souza, ROCHA; Michele de Souza, LIMA; Ediene Moura, JORGE; José Carlos Figueiredo, PANTOJA; Carla Cristina Guimarães de, MORAES; Helio, LANGONI.

    2015-09-01

    Full Text Available Brucelose e leptospirose são enfermidades bacterianas amplamente disseminadas e o cão é importante fonte de infecção e reservatório para ambas, podendo eliminar o agente no meio ambiente, e transmiti-lo para humanos e/ou outros animais. O presente estudo teve como objetivo pesquisar a ocorrência de [...] cães reagentes para anticorpos contra Leptospira spp., Brucella canis e B. abortus em Belém e Castanhal, Pará, Amazônia, Brasil. Foram colhidas de forma aleatória 156 amostras no município de Belém e 158 amostras em Castanhal. A pesquisa de anticorpos anti-B. canis foi realizada pela técnica de Imunodifusão em Gel de Ágar (IDGA) com e sem tratamento do soro com 2-mercaptoetanol (IDGA-2ME) e para pesquisa de anticorpos anti-B. abortus foi utilizada a técnica de Soroaglutinação Rápida com antígeno acidificado tamponado (AAT). Para pesquisa de anticorpos contra-Leptospira spp. utilizou-se a Técnica de Aglutinação Microscópica (MAT). Nenhum animal reagiu para Brucella abortus e um animal foi reagente para B. canis na IDGA, porém foi negativo na IDGA-2ME. Dezessete por cento dos cães (47/274) apresentaram anticorpos contra-Leptospira spp., com predominância do sorovar Canicola. Os cães de Belém e Castanhal não são fontes de infecção para B. abortus e B. canis, no entanto são reservatórios de diferentes sorovares de Leptospira spp. Abstract in english Brucellosis and leptospirosis are widely spread bacterial infections and dogs are the most important source of infection and reservoir for diseases. Dogs can disseminate the agents in the environment and transmit them to humans and/or other animals. The objective of this study was assess the occurre [...] nce of reactive to antibodies anti-Leptospira spp., Brucella canis and B. abortus in Belém and Castanhal, State of Pará, Amazon, Brazil. A total of 156 samples were randomly collected in the city of Belém and 158 samples in Castanhal. The anti-B. canis antibodies research was performed by Agar Gel Immunodiffusion (AGID) with and without 2-mercaptoethanol serum treatment (AGID-2ME). To assess the anti-B. abortus antibodies, the technique of Fast Seroagglutination with buffered acidified plate antigen (BAPAT) was used. For anti-Leptospira spp. antibodies research, the Microscopic Agglutination Technique (MAT) was used. No animal reacted to Brucella abortus and one animal was reactive to B. canis at the AGID, but it was negative to the AGID-2ME test. Seventeen percent of dogs (47/274) presented anti-Leptospira spp. antibodies, with prevalence of serovar Canicola. The dogs from Belém and Castanhal are not source of infection for B. abortus and B. canis, however, they are reservoirs for different serovars of Leptospira spp.

  9. 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)

  10. Gel Polymer Electrolytes.

    Czech Academy of Sciences Publication Activity Database

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

    Brno : University of Technology Brno, 2002, s. 42-1-42-2. ISBN 80-214-2082-0. [Advanced Batteries and Accumulators /3./. Brno (CZ), 16.06.2002-20.06.2002] R&D Projects: GA AV ?R IAA4032002; GA ?R GA104/02/0731 Institutional research plan: CEZ:AV0Z4032918 Keywords : gel polymer * electrolytes * polymer ization Subject RIV: CA - Inorganic Chemistry

  11. Gel Polymer Electrolytes.

    Czech Academy of Sciences Publication Activity Database

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

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

  12. Aprotic gel polymer electrolytes.

    Czech Academy of Sciences Publication Activity Database

    Vondrák, Ji?í; Sedla?íková, M.; Krejza, O.

    Brno : University of Technology Brno, 2008, s. 71-72. ISBN 978-80-214-3659-6. [International Conference Advanced Batteries and Accumulators /9./. Brno (CZ), 29.06.2008-03.07.2008] R&D Projects: GA ?R(CZ) GA104/06/1471; GA AV ?R(CZ) KJB208130604 Institutional research plan: CEZ:AV0Z40320502 Keywords : gel polymer electrolytes Subject RIV: CA - Inorganic Chemistry

  13. Active Polymer Gel Actuators

    OpenAIRE

    Shuji Hashimoto; Ryo Yoshida; Yusuke Hara; Shingo Maeda

    2010-01-01

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

  14. Hydrodynamics of active permeating gels

    Energy Technology Data Exchange (ETDEWEB)

    Callan-Jones, A C [Laboratoire Charles Coulomb, UMR 5521 CNRS-UM2, Universite Montpellier II, 34095 Montpellier Cedex 5 (France); Juelicher, F, E-mail: andrew.callan-jones@univ-montp2.fr [Max-Planck-Institut fuer Physik komplexer Systeme, Noethnitzerstrasse 38, 01187 Dresden (Germany)

    2011-09-15

    We develop a hydrodynamic theory of active permeating gels with viscoelasticity in which a polymer network is embedded in a background fluid. This situation is motivated by active processes in the cell cytoskeleton in which motor molecules generate elastic stresses in the network, which can drive permeation flows of the cytosol. Our approach differs from earlier ones by considering the elastic strain in the polymer network as a slowly relaxing dynamical variable. We first present the general ideas for the case of a passive, isotropic gel and then extend this description to a polar, active gel. We discuss two specific cases to illustrate the role of permeation in active gels: self-propulsion of a thin slab of gel relative to a substrate driven by filament polymerization and depolymerization; and non-equilibrium deswelling of a gel driven by molecular motors.

  15. Purification of Titania Gels.

    Czech Academy of Sciences Publication Activity Database

    Mat?jová, Lenka; Cajthaml, Tomáš; Kluso?, P.; Benada, Old?ich; Mat?j, Z.; Šolcová, Olga

    Bratislava : Slovak Society of Chemical Engineering , 2008 - (Markoš, J.), s. 166 ISBN 978-80-227-2903-1. [35th International Conference of Slovak Society of Chemical Engineering . Tatranské Matliare (SK), 26.05.2008-30.05.2008] R&D Projects: GA AV ?R KAN400720701; GA AV ?R IAA4072404 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z50200510 Keywords : sol-gel * TiO2 powder * supercritic fluid extraction Subject RIV: CF - Physical ; Theoretical Chemistry

  16. THE PROPERTIES OF CARRAGEENAN GELS

    Directory of Open Access Journals (Sweden)

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

    2012-04-01

    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.

  17. PREPARATION AND CHARACTERIZATION OFCHITOSAN GELS

    OpenAIRE

    MARCOS FERNÁNDEZ; CARLOS VON PLESSING; GALO CÁRDENAS

    2006-01-01

    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 ...

  18. Phase behaviors of agarose gel

    OpenAIRE

    Takaharu Morita; Takayuki Narita; Sada-atsu Mukai; Miho Yanagisawa; Masayuki Tokita

    2013-01-01

    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. W...

  19. Thoria sol-gel processes

    International Nuclear Information System (INIS)

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

  20. Gel polymer electrolytes for batteries

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-18

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

  1. Colloidal thermoresponsive gel forming hybrids.

    Science.gov (United States)

    Liu, Ruixue; Tirelli, Nicola; Cellesi, Francesco; Saunders, Brian R

    2010-09-15

    Colloidal hybrids comprise organic and inorganic components and are attracting considerable attention in the literature. Recently, we reported hybrid anisotropic microsheets that formed thermoresponsive gels in polymer solutions [Liu et al., Langmuir, 25, 490, 2009]. Here, we investigate the composition and properties of these hybrid colloids themselves in detail for the first time. Three different cationic PNIPAm (N-isopropylacrylamide) graft copolymers and two inorganic nanoparticle types (laponite and Ludox silica) were used to prepare a range of hybrids. Anisotropic microsheets only formed when laponite particles were added to the copolymer implying directed self-assembly. Aqueous dispersions of the microsheets spontaneously formed gels at room temperature and these gels were thermoresponsive. They represent a new class of gel forming colloid and are termed thermoresponsive gel forming hybrids. The compositions of the hybrids were determined from thermogravimetric analysis and those that gave gel forming behaviour identified. Variable-temperature rheology experiments showed that the elasticity of the gels increased linearly with temperature. The reversibility of the thermally-triggered changes in gel elasticity was investigated. The concentration dependence of the rheology data was well described by elastic percolation scaling theory and the data could be collapsed onto a master curve. The concentration exponent for the elastic modulus was 2.5. The strong attractive interactions that exist between the dispersed gel forming hybrids was demonstrated by the formation of stable thermoresponsive hybrid hydrogels through casting of hybrid dispersions. PMID:20561633

  2. Phase behaviors of agarose gel

    Directory of Open Access Journals (Sweden)

    Takaharu Morita

    2013-04-01

    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.

  3. Nanocrystal/sol-gel nanocomposites

    Science.gov (United States)

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

    2012-06-12

    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

  4. Vanadium pentoxide gels

    International Nuclear Information System (INIS)

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

  5. Radiotherapy gel dosimetry

    International Nuclear Information System (INIS)

    In radiotherapy, the primary objective is to deliver a prescribed dose of radiation to a tumour or lesion within a patient while minimising the dose delivered to the surrounding healthy tissue. Traditional radiotherapy treatments usually involve simple external or internal irradiations of a tumour. External irradiations are normally achieved in the clinic with photon or electron beams produced by high energy linear accelerators. The photon or electron beams are collimated into regular shapes as they emerge from the treatment head of the unit which is supported by a gantry that can be rotated isocentrically to any position. A discrete number of photon or electron beams with different angles of incidence that intersect at the iso-centre are used to produce a region of high dose around the tumour volume (positioned at the iso-centre). Internal irradiations are normally achieved in the clinic by implanting radioactive sources in and around the tumour or lesion. Such irradiations are characterised by very high doses local to the tumour. Radioactive sources are also used to prevent post-angioplasty restenosis by inserting sources into arteries. Usually when treating a tumour, a compromise is made between tumour control and complications arising from normal tissue damage. One measure of this compromise, the therapeutic ratio, is defined as the radiation dose producing complications in 50% of patients divided by the dose providing tumour control in 50% of the patients. The therapeutic ratio depends on the radiobiological characteristics of the cancerous tissue and surrounding healthy tissues and on the radiation dose distribution achieved by the radiotherapy treatment. It is generally believed that the therapeutic ratio can be minimised by optimising the conformation of the radiation dose distribution to the target volume. This is difficult with traditional radiotherapy techniques since they do not produce dose distributions that adequately cover tumour volumes of complex shapes and sizes while sparing normal tissue. The situation is further complicated if the normal tissues are critical organs or are particularly sensitive to radiation. Radiotherapy techniques employed to obtain a closer conformation of the dose distribution to the tumour volume are referred to as conformal radiotherapy techniques. The clinical implementation of conformal therapy has been delayed by limitations in the verification of conformal dose distributions calculated by treatment planning systems prior to the irradiation of the patient and the verification of complex treatments during its delivery to the patient. There are several aspects of conformal therapy that complicate dose verification. To achieve the dose distributions conforming to complex 3D volumes, high dose gradients arise in the treatment volume. Further, overdose or underdose regions can exist when separate radiation fields are used to deliver additional radiation. These aspects require that practical dose measurement (dosimetry) techniques be able to integrate dose over time and easily measure dose distributions in 3D with high spatial resolution. Traditional dosimeters, such as ion chambers, thermoluminescent dosimeters and radiographic film do not fulfil these requirements. Novel gel dosimetry techniques are being developed in which dose distributions can potentially be determined in vitro in 3D using anthropomorphic phantoms to simulate a clinically irradiated situation. As long ago as the 1950's, radiation-induced colour change in dyes was used to investigate radiation doses in gels. It was subsequently shown that radiation induced changes in nuclear magnetic resonance (NMR) relaxation properties of gels infused with conventional Fricke dosimetry solutions could be measured using magnetic resonance imaging (MRI). In Fricke gels, Fe2+ ions in ferrous sulphate solutions are usually dispersed throughout a gelatin, agarose or PVA matrix. Radiation-induced changes in the dosimeters are considered to be either through direct absorption of ionising radiation or via intermediate water free rad

  6. Adhesive, elastomeric gel impregnating composition

    Science.gov (United States)

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

    2002-01-01

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

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

    OpenAIRE

    Chen J; Shen Q; Luo M

    2011-01-01

    Maofu Luo1,2, Qi Shen1, Jinjin Chen11School of Pharmacy, Shanghai Jiao Tong University, Shanghai, 2Jiangxi University of Traditional Chinese Medicine, Nanchang, People’s Republic of ChinaBackground: The aim of this study was to develop new systems for transdermal delivery of paeonol, in particular microemulsion gel and cubic gel formulations.Methods: Various microemulsion vehicles were prepared using isopropyl myristate as an oil phase, polyoxyethylated castor oil (Cremophor®...

  8. One-step casting of Laemmli discontinued sodium dodecyl sulfate-polyacrylamide gel electrophoresis gel.

    Science.gov (United States)

    Wu, Xiaoqiang; Koiwa, Hisashi

    2012-02-01

    A modified Laemmli sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) protocol is described. The new method saves 30 min for gel casting without loss of the resolution power of Laemmli gel. In this method, both the upper and lower gels can be cast at the same time because the lower gel contains 10% glycerol, which generates higher density in the lower gel than in the upper gel. PMID:22037291

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

    Scientific Electronic Library Online (English)

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

    1994-12-01

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

  10. 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 to the analysis of human, pig, cattle, dog and rodent intestinal populations

  11. by sol-gel method

    Directory of Open Access Journals (Sweden)

    Jorge Medina-Valtierra

    2006-01-01

    Full Text Available Se ha usado la inmersión de substratos en un sol-gel hecho de un composito para preparar películas delgadas de TiO2 ya sean lisas o rugosas sobre fibra de vidrio. La deposición de películas se hizo desde una solución de isopropóxido de titanio (IV como precursor del sol-gel y bromuro de cetil-trimetil-amonio como surfactante. Las muestras fueron caracterizadas usando las técnicas de espectroscopia Raman y Uv-visible, así como la microscopia electrónica de barrido y de fuerza atómica. En casos especiales, la deposición de película consiste en un gel precursor de titanio que encapsula micelas de surfactante. La película de gel es convertida a la fase anatasa por calcinación a 500 °C, las películas lisas de TiO2 pueden tener propiedades ópticas y protectoras y la rugosidad de las películas de TiO2 puede aumentar su inherente actividad foto catalítica.

  12. PREPARATION AND CHARACTERIZATION OFCHITOSAN GELS

    Directory of Open Access Journals (Sweden)

    MARCOS FERNÁNDEZ

    2006-12-01

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

  13. PREPARATION AND CHARACTERIZATION OFCHITOSAN GELS

    Scientific Electronic Library Online (English)

    MARCOS, FERNÁNDEZ; CARLOS, VON PLESSING; GALO, CÁRDENAS.

    2006-12-01

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

  14. Topical Review: Polymer gel dosimetry

    OpenAIRE

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

    2010-01-01

    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 ...

  15. Tracer diffusion in colloidal gels

    OpenAIRE

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

    2007-01-01

    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...

  16. Silica reinforced triblock copolymer gels

    DEFF Research Database (Denmark)

    Theunissen, E.; Overbergh, N.

    2004-01-01

    The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order to evaluate the influence of the compatibility between gel and filler. Time-resolved SANS and small-angle X-ray scattering (SAXS) shows that the presence of silica particles affects the ordering of the polystyrene domains during gelsetting. The scattering pattern of silica-reinforced gels reveals strong scattering at very low q, but no structure and formfactor information. However, on heating above the viscoelastic to plastic transition, the 'typical' scattering pattern of the copolymer gel builds-up. All reinforced gels are strengthened by the addition of the reinforcing agent. The transitions from a viscoclastic rubber to a plastic fluid and from a plastic fluid to a viscoelastic liquid are shifted to more elevated temperatures when silica is added to the triblock copolymer gel. (C) 2004 Elsevier Ltd. All rights reserved.

  17. 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)

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

    2000-06-01

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

  18. Thixotropic gel for vadose zone remediation

    Science.gov (United States)

    Riha, Brian D.

    2012-07-03

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

  19. Thixotropic gel for vadose zone remediation

    Energy Technology Data Exchange (ETDEWEB)

    Riha, Brian D.; Looney, Brian B.

    2015-10-27

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

  20. Rheology and structure of milk protein gels

    OpenAIRE

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

    2004-01-01

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

  1. Capillary fracture of soft gels

    CERN Document Server

    Bostwick, Joshua B

    2013-01-01

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

  2. Synthesis and Application of Modulated Polymer Gels

    Science.gov (United States)

    Hu, Zhibing; Zhang, Xiaomin; Li, Yong

    1995-07-01

    A class of environmentally responsive materials based on the spatial modulation of the chemical nature of gels is proposed and demonstrated here. The modulation was achieved by limiting the interpenetration of part of one gel network with another gel network. The gels so produced have an internally heterogeneous or modulated structure. Three simple applications based on the modulated gels are described here: a bigel strip, a shape memory gel, and a gel "hand." The bigel strip bends almost to a circle in response to a temperature increase or an increase in solvent concentration. The shape memory gel changes its shape from a straight line to a pentagon to a quadrangle as the temperature increases. These transitions from one shape to another are reversible. The gel "hand" in water can grasp or release an object simply by an adjustment of the temperature.

  3. Sol-gel derived sorbents

    Science.gov (United States)

    Sigman, Michael E.; Dindal, Amy B.

    2003-11-11

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

  4. Deformation of Unentangled Swollen Gels

    Science.gov (United States)

    Sariyer, Ozan; Panyukov, Sergey; Rubinstein, Michael

    2014-03-01

    We study the deformation characteristics (Poisson's ratios and stress-strain relations) of unentangled gels swollen and uniaxially or biaxially deformed in excess solvent by considering the balance of osmotic pressure and elastic stress in unconstrained dimensions. Our scaling theory predicts a crossover from theta solvent behavior to marginal solvent behavior upon stretching gels that are in concentrated regime at swelling equilibrium - a phenomenon that was experimentally observed long ago, but not understood theoretically. For gels that are in the semidilute good solvent regime at swelling equilibrium, we predict a crossover to theta solvent behavior upon compression and a crossover to marginal solvent behavior upon stretching. Our theory reproduces the previously known results for equilibrium swelling degree as well as known deformation characteristics in theta and athermal solvents.

  5. Copolymers For Capillary Gel Electrophoresis

    Science.gov (United States)

    Liu, Changsheng (State College, PA); Li, Qingbo (State College, PA)

    2005-08-09

    This invention relates to an electrophoresis separation medium having a gel matrix of at least one random, linear copolymer comprising a primary comonomer and at least one secondary comonomer, wherein the comonomers are randomly distributed along the copolymer chain. The primary comonomer is an acrylamide or an acrylamide derivative that provides the primary physical, chemical, and sieving properties of the gel matrix. The at least one secondary comonomer imparts an inherent physical, chemical, or sieving property to the copolymer chain. The primary and secondary comonomers are present in a ratio sufficient to induce desired properties that optimize electrophoresis performance. The invention also relates to a method of separating a mixture of biological molecules using this gel matrix, a method of preparing the novel electrophoresis separation medium, and a capillary tube filled with the electrophoresis separation medium.

  6. Heterogeneous diffusion in a reversible gel

    CERN Document Server

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

    2007-01-01

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

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

    DEFF Research Database (Denmark)

    Liu, Chao; Thormann, Esben

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Jordana Almeida Santana

    2013-12-01

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

  9. Regenerative medicine: Noodle gels for cells

    Science.gov (United States)

    Deming, Timothy J.

    2010-07-01

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

  10. Preparation of thin fibrin gels.

    Czech Academy of Sciences Publication Activity Database

    Riedel, Tomáš; Brynda, Eduard; Dyr, J. E.

    Viareggio : University of Siena/Interuniversity Research Centre for Advanced Medical Systems, 2007. s. 73. [International Congress on Biohydrogels. 14.11.2007-18.11.2007, Viareggio] R&D Projects: GA AV ?R KAN200670701 Institutional research plan: CEZ:AV0Z40500505 Keywords : fibrinogen * fibrin gels * coagulation Subject RIV: CD - Macromolecular Chemistry

  11. News concerning gel polymer electrolytes.

    Czech Academy of Sciences Publication Activity Database

    Sedla?íková, M.; Vondrák, Ji?í; Macalík, M.

    Brno : University of technology Brno, 2009, s. 46-48. ISBN 978-80-214-3943-6. [International Conference Advanced Batteries, Accumulators and Fuel Cells /10./. Brno (CZ), 30.08.2009-02.10.2009] Institutional research plan: CEZ:AV0Z40320502 Keywords : gel polymer electrolytes Subject RIV: CG - Electrochemistry

  12. Screening effect on nanostructure of charged gel

    DEFF Research Database (Denmark)

    Sugiyama, M; Annaka, M; Hino, M; Fukonaga, T; Vigild, Martin Etchells; Hara, K

    2004-01-01

    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 nanostructur...

  13. FTIR thermal analysis on organofunctionalized silica gel

    OpenAIRE

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

    2001-01-01

    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...

  14. 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)

    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

    Full Text Available 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.

  15. Epidemiologia da infecção pelo vírus da Leucose Enzoótica Bovina (LEB) / Epidemiology of Enzootic Bovine Leukemia (BLV) virus infection

    Scientific Electronic Library Online (English)

    José Wilton, Pinheiro Junior; Maria Evódia de, Souza; Wagnner José Nascimento, Porto; Nair Silva Cavalcanti, Lira; Rinaldo Aparecido, Mota.

    2013-06-01

    Full Text Available Objetivou-se com este trabalho investigar a presença de anticorpos anti-vírus da leucose enzoótica além de identificar a associação entre variáveis de manejo e soropositividade para essa infecção em bovinos no Estado de Alagoas, Brasil. Foram examinados 17 rebanhos, perfazendo um total de 341 animai [...] s, distribuídos em oito municípios. A pesquisa de anticorpos foi efetuada pela técnica de Imunodifusão em Gel de Ágar (IDGA), utilizando-se o antígeno constituído por lipopolissacarídeos e proteínas do vírus da leucose bovina. Das 341 amostras analisadas, 95 (27,8%) foram positivas e o número de focos constatados foi de 12 (70,6%). Foram observadas diferenças significativas para as variáveis: assistência técnica (p Abstract in english The purpose of this study was to investigate the presence of anti-enzootic leucosis virus antibodies and also to identify the association between seropositivity and management variables for this infection in cattle in the State of Alagoas, Brazil. A total of 17 herds were examined, totaling 341 anim [...] als, distributed in eight counties. The antibody detection was performed by the technique of agar gel immunodiffusion (AGID), using the antigen constituted of lipids and proteins from bovine leukosis virus. From the 341 samples analyzed, 95 (27.8%) were positive and the number of outbreaks was 12 (70.6%). Significant differences were observed for the variables: technical assistance (p

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

    Science.gov (United States)

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

    2007-04-01

    Topical therapy for rosacea aims to reduce inflammatory lesions and decrease erythema but can carry side effects such as stinging, pruritus, and burning. Metronidazole and azelaic acid gel 15% are U.S. Food and Drug Administration-approved for the treatment of rosacea. The current study was conducted to assess the cumulative irritation potential of 2 formulations of metronidazole 0.75% gel and 1% gel--and azelaic acid gel 15% over 21 days (N=36). Results of this study demonstrated a significantly greater poten tial for irritation from azelaic acid compared with metronidazole gel 0.75% (P < .0001), which had significantly greater potential for irritation compared with metronidazole gel 1% (P = .0054). Metronidazole gel 1% had a similar profile to white petrolatum. PMID:17500380

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    Responsive biomaterial hydrogels attract significant attention due to their biocompatibility and degradability. In order to make chitosan based gels, we first graft one layer of chitosan to silica, and then build a chitosan/poly(acrylic acid) multilayer using the layer-by-layer approach. After cross-linking the chitosan present in the polyelectrolyte multilayer, poly(acrylic acid) is partly removed by exposing the multilayer structure to a concentrated carbonate buffer solution at a high pH, lea...

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

    OpenAIRE

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

    2006-01-01

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

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

    OpenAIRE

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

    2010-01-01

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

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

    Scientific Electronic Library Online (English)

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

    2014-04-01

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

  1. Anisotropic elasticity of magnetically ordered agarose gel

    International Nuclear Information System (INIS)

    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

  2. Gel dosimetry for conformal radiotherapy

    International Nuclear Information System (INIS)

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

  3. Gel dosimetry for conformal radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-07-01

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

  4. The Sol-Gel Process

    Directory of Open Access Journals (Sweden)

    Khalid Suliman Aboodh

    2015-02-01

    Full Text Available Abstract An increasingly important application of liquid jets is the disintegration of the jet to form droplets of liquid containing nuclear fuel. These droplets are then dried and sintered to form ceramic micro spheres for use in fuel elements in nuclear reactors. The total operations required to form the droplets convert them to solids and fire them to ceramic bodies comprise what are known as Sol-Gel processes Reference 13.

  5. Birefringence Modulated Scattering in Gels

    OpenAIRE

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

    1995-01-01

    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 mag...

  6. 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)

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

    Directory of Open Access Journals (Sweden)

    Ghluam Hussain Jaffar

    2010-02-01

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

  8. PEMANFAATAN LIMBAH SEKAM PADI MENJADI SILIKA GEL

    Directory of Open Access Journals (Sweden)

    Prima Astuti Handayani

    2014-12-01

    Full Text Available Sekam padi merupakan salah satu sumber penghasil silika terbesar, berpotensi sebagai bahan pembuatan silika gel. Abu sekam padi mengandung silika sebanyak 87%-97% berat kering. Sintesis silika gel dari abu sekam padi dilakukan dengan mereaksikan abu sekam padi menggunakan larutan NaOH 1N pada suhu 800C selama 1 jam dan dilanjutkan dengan penambahan larutan asam hingga pH=7. Gel yang dihasilkan selanjutnya didiamkan selama 18 jam kemudian dikeringkan pada suhu dikeringkan menggunakan oven pada suhu 800C hingga beratnya konstan. Hasil percobaan diperoleh bahwa silika gel dengan penambahan CH3COOH menghasilkan yield yang lebih besar dibandingkan penambahan HCl. Berdasarkan analisis FT-IR silika gel yang diperoleh memiliki gugus Si-O-Si dan gugus Si-OH. Silika gel dengan penambahan HCl memiliki surface area sebesar 65,558 m2/g, total pore volume 0,1935 cc/g, dan average pore size sebesar 59,0196 Å. Sedangkan silika gel dengan penambahan CH3COOH memiliki surface area sebesar 9,685 m2/g, total pore volume 0,02118 cc/g, dan average pore size sebesar 43,7357Å. Silika gel dengan penambahanCH3COOH memiliki kemampuan menyerap kelembaban udara yang lebih baik dibanding silika gel dengan penambahan HCl. Rice hull ash (RHA is one of the biggest source of silica, potential for sintesis silica gel. RHA contains silica as many as 87 % -97 %. Synthesis of silica gel from rice hull ash was done by reaction using NaOH solution at temperature 800C for 1 hour and followed by the addition of an acid solution until pH=7. The gel were rested with time aging 18 hour, and then dried using oven at temperature 800C until constant weigh. The results obtained that the silica gel with the addition of CH3COOH produce higher yields than the addition of HCl. Based on FT-IR analysis, silica gel has a group of silanol (Si-`OH and siloxan (Si-O-Si group. Silica gel with the addition of HCl has a surface area 65,558 m2/g, a total pore volume 0,1935 cc/g, and average pore size 59,0196 Å. While the silica gel with the addition of CH3COOH has a surface area 9.685 m2/g, a total pore volume 0,02118 cc/g, and average pore size 43,7357 Å. Silica gel with the addition of CH3COOHhas the ability to absorb humidity better than silica gel with the addition of HCl.

  9. Metal-silica sol-gel materials

    Science.gov (United States)

    Stiegman, Albert E. (Inventor)

    2002-01-01

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

  10. Tailoring the properties of supramolecular gels

    Science.gov (United States)

    Buerkle, Lauren

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

  11. Gel barrier formation in unsaturated porous media

    Science.gov (United States)

    Kim, Meejeong; Corapcioglu, M. Yavuz

    2002-05-01

    The gel barrier formation by a gelling liquid (Colloidal Silica) injection in an unsaturated porous medium is investigated by developing a mathematical model and conducting numerical simulations. Gelation process is initiated by adding electrolytes such as NaCl, and the gel phase consisting of cross-linked colloidal silica particles grows as the gelation process proceeds. The mathematical model describing the transport and gelation of Colloidal Silica (CS) is based on coupled mass balance equations for the gel mixture (the sol phase plus the gel phase), gel phase (cross-linked colloidal silica particles plus water captured between cross-linked particles), and colloidal silica particles (discrete and cross-linked) and NaCl in the sol (suspension of discrete colloidal silica particles in water) and gel phases. The solutions in terms of volumetric fraction of the gel phase yield the gel mixture viscosity via the dependency on the volumetric fraction of gel phase. This dependency is determined from a kinetic gelation model with time-normalized viscosity curves. The proposed model is verified by comparing experimentally and numerically determined hydraulic conductivities of gel-treated soil columns at different CS injection volumes. The numerical experiments indicate that an impermeable gel layer is formed within the time period twice the gel-point in a one-dimensional flow system. At the same normalized time corresponding to twice the gel-point, the CS solutions with lower NaCl concentrations result in further migration and poor performance in plugging the pore space. The viscosity computation proposed in this study is compared with another method available in the literature. It is observed that the other method estimates the viscosity at the mixing zone higher than the one proposed by the authors. The proposed model can simulate realistic injection scenarios with various combinations of operating parameters such as NaCl concentration and NaCl mixing time, and thus providing guidelines in performing this technology on site.

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

    Directory of Open Access Journals (Sweden)

    Sirima Chinnasarn

    2006-01-01

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

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

    International Nuclear Information System (INIS)

    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. - highlights: • 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

  14. GEM printer: 3D gel printer for free shaping of functional gel engineering materials

    Science.gov (United States)

    Furukawa, Hidemitsu; Muroi, Hisato; Yamamoto, Kouki; Serizawa, Ryo; Gong, Jin

    2013-04-01

    In the past decade, several high-strength gels have been developed. These gels are expected to use as a kind of new engineering materials in the fields of industry and medical as substitutes to polyester fibers, which are materials of artificial blood vessels. The gels have both low surface friction and well permeability due to a large amount of water absorbed in the gels, which are superiority of the gels compering to the polyester fibers. It is, however, difficult for gels to be forked structure or cavity structure by using cutting or mold. Consequently, it is necessary to develop the additive manufacturing device to synthesize and mode freely gels at the same time. Here we try to develop an optical 3D gel printer that enables gels to be shaped precisely and freely. For the free forming of high-strength gels, the 1st gels are ground to particles and mixed with 2nd pregel solution, and the mixed solution is gelled by the irradiation of UV laser beam through an optical fiber. The use of the optical fiber makes one-point UV irradiation possible. Since the optical fiber is controlled by 3D-CAD, the precise and free molding in XYZ directions is easily realized. We successfully synthesized tough gels using the gel printer.

  15. Active Gel Model of Amoeboid Cell Motility

    CERN Document Server

    Callan-Jones, A C

    2013-01-01

    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.

  16. Microwave densification of porous silica gel

    International Nuclear Information System (INIS)

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

  17. Sol-gel electrochromic device

    OpenAIRE

    Macedo, Marcelo A.; Aegerter, Michel A.

    1994-01-01

    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...

  18. Motility initiation in active gels

    CERN Document Server

    Recho, Pierre; Truskinovsky, Lev

    2015-01-01

    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.

  19. Gel Electrophoresis at High Fields

    International Nuclear Information System (INIS)

    We investigate the band velocity v and the diffusion coefficient D of DNA in gel for the geometration mechanism. Here we treat the geometration as a one-step process. The velocity dispersion shows a maximum for some small number of hookings. This allows to expect that the diffusion constant behaves in a similar way. On the other hand, the average number of hookings should increase with the molecule length. Summarizing, the diffusion constant should decrease for very long molecules. However, we do not find this effect in experimental data. This contradiction can be resolved by a conclusion that multiple hookings do not occur. (author)

  20. 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)

  1. Normal force controlled rheology for thermoreversible gels

    OpenAIRE

    Mao, Bosi; Divoux, Thibaut; Snabre, Patrick

    2015-01-01

    A wide range of thermoreversible gels are prepared by cooling down to ambient temperature hot aqueous solutions of polymers. During the sol-gel transition, such soft solids may experience a volume contraction leading to experimental issues regarding rheological measurements such as the stress-induced release of solvent, and the partial loss of contact between the sample and the shear cell. In this article, we revisit the formation of thermoreversible gels through a series of...

  2. Low-Reynolds number swimming in gels

    OpenAIRE

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

    2010-01-01

    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...

  3. FORMULATION AND EVALUATION OF CELECOXIB GEL

    OpenAIRE

    Preeti Karade

    2012-01-01

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

  4. Polymer gel electrolytes for lithium batteries

    International Nuclear Information System (INIS)

    The data on the most promising polymer gel electrolytes for lithium batteries published in the past decade are surveyed and described systematically. Gel electrolytes with matrices of polyethylene oxide, poly(vinylidene fluoride) and its copolymer with hexafluoropropylene, poly(methyl methacrylate), polyacrylonitrile, poly(vinyl chloride) and polyacrylates are discussed. A special section is devoted to gel electrolytes with ionic liquids as the solvents. The bibliography includes 160 references.

  5. 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

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

    Directory of Open Access Journals (Sweden)

    Julio A. Mesquita

    1972-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Heng See

    2009-01-01

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

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

    OpenAIRE

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

    1993-01-01

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

  9. 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)

  10. EPIDEMIOLOGIA DA INFECÇÃO PELO VÍRUS DA LEUCOSE ENZOÓTICA BOVINA (LEB

    Directory of Open Access Journals (Sweden)

    José Wilton Pinheiro Junior

    2013-06-01

    Full Text Available The purpose of this study was to investigate the presence of anti-enzootic leucosis virus antibodies and also to identify the association between seropositivity and management variables for this infection in cattle in the State of Alagoas, Brazil. A total of 17 herds were examined, totaling 341 animals, distributed in eight counties. The antibody detection was performed by the technique of agar gel immunodiffusion (AGID, using the antigen constituted of lipids and proteins from bovine leukosis virus. From the 341 samples analyzed, 95 (27.8% were positive and the number of outbreaks was 12 (70.6%. Significant differences were observed for the variables: technical assistance (p<0.000, recent acquisition of animals (p=0.003, existence of maternity paddocks (p<0.000, and colostrum management (p<0.000. The enzootic bovine leukosis virus infection is present in the region studied and strict sanitary matters must be implemented to prevent spread of the virus, which will avoid losses in the cattle production chain.

  11. A Short-Duration Gel Diffusion Experiment.

    Science.gov (United States)

    Mulcahy, D. E.

    1980-01-01

    Described is a gel diffusion experiment that permits the completion of duplicate diffusion runs within a three-hour laboratory session. Information included for the short-duration gel diffusion experiment is the diffusion cell, the experiment, data treatment, and the expected results of the experiment. (Author/DS)

  12. Cracking silica gels for surface decontamination

    International Nuclear Information System (INIS)

    Two types of silica based gels, oxidising and non-oxidising, have been developed and investigated for decontamination of fixed ?, ?, and ? contamination from contaminated surfaces of glove boxes, PVC floors, fume hood glass doors. Ceric ammonium nitrate dissolved in nitric acid was used as oxidant in oxidising gel. In non-oxidising gel, water soluble reagent; tetra ethyl diglycolamide (TEDGA) in nitric acid was used as complexing agent. Silica gel and PEG-400 was base material in both the cases. The gels were brushed on a stainless steel surface, on drying; these gels crack to yield flakes that were easily scrubbed from the surfaces. The flakes, concentrated in activity, was immobilised in cement for storage. Studies were carried out to investigate the effect of concentrations of oxidant, TEDGA and nitric acid for effective decontamination. Oxidising gels with 0.75 M Ce (IV) and 1 M Nitric acid have shown a maximum DF of 90 for fixed Pu contaminated SS surface. Non-oxidising gel showed a DF of 7 for similar surfaces with 0.075 M TEDGA, 1 M nitric acid and 1 M phosphoric acid. (author)

  13. Structure and Frictional Properties of Colloid Gel

    Directory of Open Access Journals (Sweden)

    Masayuki Tokita

    2014-03-01

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

  14. A Simple Vertical Slab Gel Electrophoresis Apparatus.

    Science.gov (United States)

    Carter, J. B.; And Others

    1983-01-01

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

  15. Thermotropic nanostructured "gel in gel" systems for improved oil recovery and water shutoff

    Science.gov (United States)

    Altunina, L. K.; Kuvshinov, V. A.; Stasyeva, L. A.

    2015-10-01

    Thermotropic nanostructured system with two gel-forming components has been created based on inorganic hydroxypolymer and organic polymer with a lower critical solution temperature of "aluminum salt-cellulose ether-carbamide-water", forming at heating a bound-dispersed nano-sized "gel in gel" structure. The studies on the kinetics of gelation and rheological properties of solutions and gels in this system have shown that the gels have a higher viscosity and elasticity and thereby are promising for creating deflecting screens in oil reservoirs, redistribution of filtration flows, improved oil recovery and for water shutoff.

  16. A new polymer gel dosimeter composed of methacrylic acid, agarose gel and THPC with gelatin

    International Nuclear Information System (INIS)

    In this paper, a new type of methacrylic acid based gel dosimeter is presented. This gel contains both agarose and gelatin with deferent roles respectively. The agarose conducts itself as a gelling agent, while the gelatin relates to the graft reaction of methacrylic acid. This new type of gel excels in the long-term stability of R2 after irradiation. The characteristics of this gel were studied by the measurements of R2 with MRI and the direct measurements of temperature in the gel during the irradiation.

  17. Generation of inkjet drop of particulate gel

    Science.gov (United States)

    Yoo, Hansol; Kim, Chongyoup

    2015-08-01

    The generation of inkjet drops of colloidal gels is studied experimentally. Particle suspensions are prepared by dispersing spherical polystyrene particles of 620 nm in the 1:1 mixture of deionized water and ethylene glycol. The gels are prepared by adding polyethylene oxide to the suspensions by inducing the depletion interaction between particles. It is demonstrated that inkjet drops can be generated by using the colloidal gels. It is found that the ligament extended from the inkjet nozzle is stabilized so that the drop can be generated without satellite droplets behind the main drop and the velocity of the gel drop is faster than that of the polymer solution at the same concentration. The gel drop generation characteristics are found to be sensitive to input voltage.

  18. FTIR thermal analysis on organofunctionalized silica gel

    Directory of Open Access Journals (Sweden)

    Foschiera José L.

    2001-01-01

    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.

  19. Chitosan: Gels and Interfacial Properties

    Directory of Open Access Journals (Sweden)

    Julie Nilsen-Nygaard

    2015-03-01

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

  20. Silver nanowires embedded gel electrodes

    Science.gov (United States)

    Abe, Yuta; Gong, Jin; Furukawa, Hidemitsu

    2013-04-01

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

  1. Sol-Gel Manufactured Energetic Materials

    Science.gov (United States)

    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

    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.

  2. FTIR thermal analysis on organofunctionalized silica gel

    Scientific Electronic Library Online (English)

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

    2001-04-01

    Full Text Available 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.

  3. Sol-gel coatings for electrochromic devices

    OpenAIRE

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

    1992-01-01

    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...

  4. Muscular Contraction Mimiced by Magnetic Gels

    Science.gov (United States)

    Zrínyi, Miklós; Szabó, Dénes

    The ability of magnetic-field-sensitive gels to undergo a quick controllable change of shape can be used to create an artificially designed system possessing sensor- and actuator functions internally in the gel itself. The peculiar magneto-elastic properties may be used to create a wide range of motion and to control the shape change and movement, that are smooth and gentle similar to that observed in muscle. Magnetic field sensitive gels provide attractive means of actuation as artificial muscle for biomechanics and biomimetic applications.

  5. Pulsed field gel electrophoresis a practical guide

    CERN Document Server

    Birren, Bruce

    2012-01-01

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

  6. Composite sol-gel ceramics

    Science.gov (United States)

    Yang, Quanzu

    1999-11-01

    The fundamental goal of the present study was to develop an understanding of the mechanisms of dispersion, gelation, drying, interfacial bonding and densification of composite sol-gel (CSG) ceramics. The general applied objective was to fabricate high performance CSG ceramics and to produce novel, non-permeable, adherent CSG coatings on stainless steel substrates for high temperature corrosion and wear protection. The properties of the alumina sols and CSG were studied by measuring viscosity, conductivity, ionic strength, and pH of the sol. The dispersion and stability of ceramic particles in alumina sols were investigated by measuring particle size distributions, measuring zeta potentials, and calculating the interaction energy according to DLVO theory. The CSG technology has been developed to fabricate high performance engineering composite ceramics and coatings through dispersing ceramic fillers (alumina, zirconia, SiC) into alumina sols, gelcasting, drying, and pressureless sintering. A sintering model for CSG was developed and validated by experiment results. The model was then used successfully to predict sinterability and to optimize the processing technologies of CSG. The research results indicate that hydrated alumina sols can be used as a sintering and dispersion additive for alumina-based ceramics. The sol-gel matrix provides fast diffusion paths for mass transport during sintering CSG. Dispersion of alumina and SiC particles is substantially improved in alumina sols, as compared to pure water of similar acidity, e.g. the average agglomerate size is decreased by at least 50%. For alumina/alumina CSG ceramics sintered at 1400°C, the microhardness is 20 GPa and porosity is less than 1 vol%. The CSG composite with composition of 50vol%SiC-50vol%Al2O 3 has been sintered successfully to full densification and microhardness of 22.9 GPa. A novel process for ceramic coatings on the metallic substrates has been developed successfully by combining chemical bonding and CSG technologies. Non-permeable, crack-free, thick ceramic coatings (2--600 mum) on the substrates were fabricated by spraying and dipping, followed by low temperature (500--600°C) sintering. The correlations between the processing methods, microstructure, and mechanical properties of CSG coatings were investigated by varying the preparation methods, studying morphology, and measuring mechanical properties of the ceramics. The chemically bonded CSG coatings have the best performance. The bonding strength between the substrates and coatings is about 42 MPa, and the surface microhardness of the coatings is about 6.5 GPa.

  7. Manual control of catalytic reactions: Reactions by an apoenzyme gel and a cofactor gel

    Science.gov (United States)

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

    2015-11-01

    Enzymes play a vital role in catalysing almost all chemical reactions that occur in biological systems. Some enzymes must form complexes with non-protein molecules called cofactors to express catalytic activities. Although the control of catalytic reactions via apoenzyme–cofactor complexes has attracted significant attention, the reports have been limited to the microscale. Here, we report a system to express catalytic activity by adhesion of an apoenzyme gel and a cofactor gel. The apoenzyme and cofactor gels act as catalysts when they form a gel assembly, but they lose catalytic ability upon manual dissociation. We successfully construct a system with switchable catalytic activity via adhesion and separation of the apoenzyme gel with the cofactor gel. We expect that this methodology can be applied to regulate the functional activities of enzymes that bear cofactors in their active sites, such as the oxygen transport of haemoglobin or myoglobin and the electron transport of cytochromes.

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

    International Nuclear Information System (INIS)

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

  9. 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 current formulations so as to provide a feasible gel for clinical applications of x-ray CT polymer gel dosimetry.

  10. Sol-gel antireflective coating on plastics

    Science.gov (United States)

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

    1990-01-01

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

  11. Equipment development for sol-gel process

    International Nuclear Information System (INIS)

    Sol-gel processes have been developed for the production of microspheres of oxide, carbide and nitrides of urania, plutonia, thoria and their mixtures of controlled composition and size for making nuclear fuels

  12. Maize Arabinoxylan Gels as Protein Delivery Matrices

    Directory of Open Access Journals (Sweden)

    Ana Luisa Martínez-López

    2009-04-01

    Full Text Available The laccase induced gelation of maize bran arabinoxylans at 2.5% (w/v in the presence of insulin or ?-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.

  13. [Formulation of benzethonium chloride into gels].

    Science.gov (United States)

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

    2014-06-01

    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

  14. 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)

  15. 2-DE Gel Analysis: The Spot Detection.

    Science.gov (United States)

    Martinotti, Simona; Ranzato, Elia

    2016-01-01

    The abundance of different proteins on a 2-DE gel is reflected by the shape, size, and intensity of the corresponding spots. Protein quantitation requires the conversion of an analog gel image into digital data, resulting into a catalog of individual spots listed as x, y positions, shape parameters, and quantitative values. So, it is possible to carry out objective comparisons of equivalent spots on different gels, determining whether a particular protein is more or less abundant in one sample compared with another.Unfortunately, spots on protein gels are not uniform in shape, size, or density, and detection, quantitation, and comparison can be challenging without intervention.Once a processed image is available, a number of different algorithms can be applied to detect and quantitate individual spots. PMID:26611414

  16. K-Basin gel formation studies

    International Nuclear Information System (INIS)

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

  17. Oxygen-17 relaxation in aqueous agarose gels

    International Nuclear Information System (INIS)

    Nuclear magnetic relaxation of oxygen-17 in H217O enriched agarose gels shows that existing explanations of water behaviour are oversimplified. Satisfactory models must include at least three proton phases, two of which involve water molecules. (Auth.)

  18. Thixotropic corrosive gels for nuclear decontamination

    International Nuclear Information System (INIS)

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

  19. Sample collection system for gel electrophoresis

    Science.gov (United States)

    Olivares, Jose A.; Stark, Peter C.; Dunbar, John M.; Hill, Karen K.; Kuske, Cheryl R.; Roybal, Gustavo

    2004-09-21

    An automatic sample collection system for use with an electrophoretic slab gel system is presented. The collection system can be used with a slab gel have one or more lanes. A detector is used to detect particle bands on the slab gel within a detection zone. Such detectors may use a laser to excite fluorescently labeled particles. The fluorescent light emitted from the excited particles is transmitted to low-level light detection electronics. Upon the detection of a particle of interest within the detection zone, a syringe pump is activated, sending a stream of buffer solution across the lane of the slab gel. The buffer solution collects the sample of interest and carries it through a collection port into a sample collection vial.

  20. Conducting Polymer Electrodes for Gel Electrophoresis

    OpenAIRE

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

    2014-01-01

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

  1. Serum release boosts sweetness intensity in gels

    OpenAIRE

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

    2010-01-01

    This paper describes the effect of serum release on sweetness intensity in mixed whey protein isolate/gellan gum gels. The impact of gellan gum and sugar concentration on microstructure, permeability, serum release and large deformation properties of the gels was determined. With increasing gellan gum concentration the size of the pores present in the protein network, the permeability and the serum release increased, as well as the Young's modulus, the fracture stress and the fracture strain....

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

    OpenAIRE

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

    2002-01-01

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

  3. Preparation of continuous alumina gel fibres by aqueous sol–gel process

    Indian Academy of Sciences (India)

    Hongbin Tan; Xiaoling Ma; Mingxing Fu

    2013-02-01

    Continuous alumina gel fibres were prepared by sol–gel method. The spinning sol was prepared by mixing aluminum nitrate, lactic acid and polyvinylpyrrolidone with a mass ratio of 10:3:1.5. Thermogravimetry–differential scanning calorimetry (TG–DSC), Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to characterize the properties of the gel and ceramic fibres. The Al2O3 fibres with a uniform diameter can be obtained by sintering gel fibres at 1200 °C.

  4. 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.)

  5. 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)

  6. Basic investigations on LCV micelle gel

    International Nuclear Information System (INIS)

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

  7. Treatment of osteochondral injuries with platelet gel

    Scientific Electronic Library Online (English)

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

    2014-12-01

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

  8. Swelling instabilities in patterned, microscale gels

    Science.gov (United States)

    Toomey, Ryan; Dupont, Samuel

    2012-02-01

    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.

  9. Basic investigations on LCV micelle gel

    Science.gov (United States)

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

    2013-06-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Ricol, S.

    1995-10-05

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

  11. Actuator device utilizing a conductive polymer gel

    Science.gov (United States)

    Chinn, Douglas A.; Irvin, David J.

    2004-02-03

    A valve actuator based on a conductive polymer gel is disclosed. A nonconductive housing is provided having two separate chambers separated by a porous frit. The conductive polymer is held in one chamber and an electrolyte solution, used as a source of charged ions, is held in the second chamber. The ends of the housing a sealed with a flexible elastomer. The polymer gel is further provide with electrodes with which to apply an electrical potential across the gel in order to initiate an oxidation reaction which in turn drives anions across the porous frit and into the polymer gel, swelling the volume of the gel and simultaneously contracting the volume of the electrolyte solution. Because the two end chambers are sealed the flexible elastomer expands or contracts with the chamber volume change. By manipulating the potential across the gel the motion of the elastomer can be controlled to act as a "gate" to open or close a fluid channel and thereby control flow through that channel.

  12. 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)

  13. Bradyrhizobium japonicum Survival in and Soybean Inoculation with Fluid Gels

    OpenAIRE

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

    1989-01-01

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

  14. Uncertainty in 3D gel dosimetry

    Science.gov (United States)

    De Deene, Yves; Jirasek, Andrew

    2015-01-01

    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.

  15. Calcium Impact on Milk Gels Formation

    DEFF Research Database (Denmark)

    Koutina, Glykeria

    2015-01-01

    Calcium is one of the several elements that can be found in milk distributed between the micellar and the serum milk phase. Calcium is important from a nutritional point of view, but its contribution to the functional and structural properties of dairy products has only recently been acknowledgement. The presence of calcium in a dynamic equilibrium between the serum and the micellar milk phase make the distribution susceptible to certain physicochemical conditions and to technological treatments of milk resulting in fluctuations in pH and temperature and also sensitive to addition of calcium salts. The perturbation of calcium equilibria by these factors will affect the final properties of acid, calcium and rennet milk gels. By decreasing the pH from 6.0 to 5.2 (acid gels), the calcium equilibrium was significantly affected by temperature (4, 20, 30, 40 oC), and different combinations of temperature and pH may result in different final structure properties in dairy products such as cheese. A significant amount of calcium remained in the micelles between pH 4.8 and 4.6, this can contribute to the final strength of acid milk gels, such as in yogurt or in cream cheeses. After the gelation point, a sudden solubilization of micellar calcium was observed at 50 oC and 60 oC, which revealed an interesting role of calcium during acidification at elevated temperatures. After enrichment of milk with calcium D-lactobionate, the added calcium was distributed between the micellar and serum milk phase at pH 6.6-6.0, but at pH 5.7-5.4 the added calcium remained mainly in the serum milk phase. The importance of pH for the distribution of the added calcium between the micellar and serum milk phase may affect bioavailability from enriched products and the distribution should be taken into consideration when designing new enriched dairy products. Calcium gels can be produced by addition of a calcium salt and heat treatment at temperatures higher than 70 oC for several minutes. The combination of heat treatment and calcium addition to milk with pH values between 6.6 and 5.6, will produce calcium milk gels with unique and dense gel structure and with little seperation of whey due to participation of calcium to the final gel structure. On the other hand, the combination of heat treatment and calcium addition to milk with pH values lower than 5.6 will still produce gel structures which are dominated by the decrease of pH and not by the addition of calcium. For rennet gels, different gels were produced with different amount of micellar calcium, as colloidal calcium phosphate (CCP), while keeping the pH and the ionic environment of the milk constant. A lower amount of micellar calcium was correlated with less time for the rennet gels to be formed. In addition the low amount of micellar calcium caused a more compact gel structure with many protein aggregates. The results of this study highlighted the importance of calcium for the formation of acid, calcium and rennet gels. The content and the interactions of calcium with proteins during milk processing are crucial for final texture and structure of different milk gels. The results of this study should be useful for improvements of existing dairy products and for design of novel dairy products with unique structure and texture and mineral bioavailability

  16. Mechanical stability of fractal colloidal gels

    Science.gov (United States)

    Manley, Suliana

    Colloidal particles with attraction diffuse and stick to form highly disordered aggregates whose structures are well-described as mass fractals. Thus, even at low particle volume fractions, ?, aggregates grow to fill space and form an elastic network. In this study, we focus on understanding the mechanical properties of colloid gels. In the process, we explore the limits to gelation and gel stability. In Chapter 2, we discuss the limits to gelation at low-?. We show that the dynamics of large fractal colloid aggregates are well described by a combination of translational and rotational diffusion and internal elastic fluctuations, allowing both the aggregate size and internal elasticity to be determined by dynamic light scattering. We find that gravitational stress limits the cluster growth on earth, even under near buoyancy-matched conditions, whereas thermal fluctuations limit the growth of fractal structures in the absence of gravity. In Chapter 3, we study the mechanical properties of gels formed from strongly aggregating silica colloids. Surprisingly, we find that their elastic moduli, G', continue to increase long after network formation, leading to an increase in elasticity of several orders of magnitude over a few hours. We present a model based on the sintering of the particles which accounts for the observed time dependence. In Chapter 4, we examine the collapse of silica colloidal gels; this occurs when the gravitational stress exerted on the lower part of a sample is greater than its yield stress. We show that the collapse dynamics are related to the rheological properties of the gel as it yields. In Chapter 5, we study the effects of surfactant concentration on a model concentrated emulsion. Surfactant concentration helps to set droplet sizes; thus, it plays an important role in determining the mechanical properties and stability of these kinds of gels. Gel networks are generally out-of-equilibrium systems; similar to glasses, they undergo aging. In Chapter 6, we discuss preliminary work on aging as it depends on attraction and ?.

  17. Recycling of superfine resolution agarose gel.

    Science.gov (United States)

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

    2013-01-01

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

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

    Science.gov (United States)

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

    2006-10-10

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

  19. Swelling and instability of a gel annulus

    Science.gov (United States)

    Chen, Xiaoyi; Dai, Hui-Hui

    2015-09-01

    We study the swelling of a gel annulus attached to a rigid core when it is immersed in a solvent. For equilibrium states, the free-energy function of the gel can be converted into a strain energy function, and as a result the gel can be treated as a compressible hyperelastic material. Asymptotic methods are used to study the inhomogeneous swelling in order to obtain the leading-order solution. Some analytical insights are then deduced. Because of the compressive hoop stress in this state, at some stage instability can occur, leading to wrinkles in the gel. An incremental deformation theory in nonlinear elasticity is used to conduct a linear bifurcation analysis for understanding such instability. More specifically, the critical loading for the onset of a wrinkled state is obtained. Detailed discussions on the behaviors of various physical quantities in this critical state are given. It is found that the critical mode number, while insensitive to the material parameters, is greatly influenced by the ratio of the inner and outer radii of the gel. Also, an interesting finding is that the critical swelling ratio is an increasing function of this geometrical parameter, which implies that a thin annulus is more likely to be unstable than a thick one.

  20. PRONIOSOMAL GEL OF FLURBIPROFEN: FORMULATION AND EVALUATION

    Directory of Open Access Journals (Sweden)

    Sunil Kumar

    2012-01-01

    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.

  1. Effectiveness of Gel Repellents on Feral Pigeons

    Directory of Open Access Journals (Sweden)

    Birte Stock

    2013-12-01

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

  2. DNA DAMAGE QUANTITATION BY ALKALINE GEL ELECTROPHORESIS.

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-03-24

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

  3. Effect of Drug modification on properties of Ketoprofen Transdermal Gel

    Directory of Open Access Journals (Sweden)

    Samy Ahmed

    2013-03-01

    Full Text Available The aim of this study was to develop Ketoprofen (KPF gel for tansdermal delivery that could enhance dissolution and permeability of KPFand to study the change in release and permeation of transdermal gel after formulating KPF as niosomes and solid dispersions. KPF gels were prepared using Carboxy methyl cellulose (CMC, hydroxyl propyl methyl cellulose (HPMC and methyl cellulose (MC with and without permeation enhancers (Tween 80 and Oleic acid. The effect of the polymers and permeation enhancers on the in vitro release and permeation was tested. The best formula was formulated as niosomal and solid dispersion gels. The effect of drug modification on the properties of KPF gel was examined. The results showed that both polymers and permeation enhancers affect release and permeation of KPF transdermal gel. The release and permeation from the niosomal gel were highly prolonged when compared to conventional gel .On the other hand, they were enhanced from the solid dispersion gel.

  4. 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)

    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

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

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

    Scientific Electronic Library Online (English)

    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.

    2013-12-01

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

  6. Low-Reynolds number swimming in gels

    CERN Document Server

    Fu, Henry C; Powers, Thomas R

    2010-01-01

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

  7. Writing in the granular gel medium

    Science.gov (United States)

    Bhattacharjee, Tapomoy; Zehnder, Steven M.; Rowe, Kyle G.; Jain, Suhani; Nixon, Ryan M.; Sawyer, W. Gregory; Angelini, Thomas E.

    2015-01-01

    Gels made from soft microscale particles smoothly transition between the fluid and solid states, making them an ideal medium in which to create macroscopic structures with microscopic precision. While tracing out spatial paths with an injection tip, the granular gel fluidizes at the point of injection and then rapidly solidifies, trapping injected material in place. This physical approach to creating three-dimensional (3D) structures negates the effects of surface tension, gravity, and particle diffusion, allowing a limitless breadth of materials to be written. With this method, we used silicones, hydrogels, colloids, and living cells to create complex large aspect ratio 3D objects, thin closed shells, and hierarchically branched tubular networks. We crosslinked polymeric materials and removed them from the granular gel, whereas uncrosslinked particulate systems were left supported within the medium for long times. This approach can be immediately used in diverse areas, contributing to tissue engineering, flexible electronics, particle engineering, smart materials, and encapsulation technologies. PMID:26601274

  8. Density mode microrheology in polyacrylamide gels

    Science.gov (United States)

    Burrola Gabilondo, Beatriz; Sisan, Daniel; Landy, Jonathan; Levine, Alex; Urbach, Jeffrey

    2012-02-01

    In passive microrheology the viscoelastic properties of soft materials are deduced by observing thermal fluctuations of tracer particles embedded within the material, and the response function obtained from the spectrum of thermally excited modes is then related to the viscoelastic shear modulus. This approach is valid for single-component, isotropic, incompressible materials. However, for heterogeneous materials, such as hydrogels, a more comprehensive approach is needed. We measure the equilibrium density fluctuations of a cross-linked polymer gel swollen in a solvent and compare them to the predictions of the `two--fluid' model of the dynamics of polymer gels. We will describe a direct method of extracting the longitudinal response function of a soft material based on the temporal and spatial correlations of density fluctuations of fluorescent markers, called density mode microrheology (DMM). We will also present results of applying DMM to fluorescent polyacrylamide gels in an aqueous solvent of varying viscosity and comparing them with parameters obtained from conventional macrorheology.

  9. 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)

  10. Superconductive ceramics obtained with sol gel method

    International Nuclear Information System (INIS)

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

  11. Carbon gels derived from natural resources

    Directory of Open Access Journals (Sweden)

    A. Celzard

    2012-12-01

    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.

  12. Sol gel process for nuclear fuels

    International Nuclear Information System (INIS)

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

  13. 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 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)

  14. Sol-gel additive for systems with inorganic binders

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Annaka, M.; Motokawa, R.; Nakahira, T. [Department of Materials Technology, Chiba University, Chiba 263-8522 (Japan); Sugiyama, M. [Department of Physics, Kyushu University, Fukuoka 812-8581 (Japan); Hara, K. [Institute of Environmental Systems, Kyushu University, Fukuoka 812-8581 (Japan); Matsuura, T. [Department of Ophtalmology, Nava Medical University, Nava 634-8522 (Japan)

    2002-07-01

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

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

    Directory of Open Access Journals (Sweden)

    Chanokphat Phadungath

    2005-03-01

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

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

    CERN Document Server

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

    2002-01-01

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

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

    International Nuclear Information System (INIS)

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

  19. Neutron detector using sol-gel absorber

    Science.gov (United States)

    Hiller, John M. (Oak Ridge, TN); Wallace, Steven A. (Oak Ridge, TN); Dai, Sheng (Knoxville, TN)

    1999-01-01

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

  20. Hybrid sol-gel optical materials

    Science.gov (United States)

    Zeigler, John M. (Albuquerque, NM)

    1993-01-01

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

  1. Aggregation-structure-elasticity relationship of gels

    Science.gov (United States)

    Ma, Hang-Shing

    Aerogel is a mesoporous, low-density material which is desirable for applications like thermal insulation and low-k interlayer dielectric. However, its lack of mechanical integrity hinders its development. Experiments have shown that aerogels exhibit a scaling relationship E ? rho m between modulus E and density rho, with the exponent m usually between 3 and 4. The objective of the dissertation is to use computer modeling to understand how the random aggregation process accounts for the fractal structure and the compliant nature of aerogels. Model gels were created by the diffusion-limited cluster-cluster aggregation (DLCA), which simulates random aggregation leading to the sol-gel transition. Then each resulting structure was modeled as an elastic beam network and numerically compressed using the finite element method (FEM). Analyses showed that the DLCA gels reproduced the scaling relationship after trimming the non-contributive dangling branches from the mechanically efficient looped networks. The dangling bond deflection (DEF) model was therefore developed to model the random rotational movement of the dangling branches and the subsequent loop structure formation. Model gels with extensive loops and negligible dangling branches were simulated by combining the DLCA and DEF models. Representation of the aerogel networks by the DLCADEF models was validated for the resemblance of the fractal geometry and elastic behavior. The lack of mechanical integrity in aerogels is a natural consequence of the random aggregation and the resulting fractal structure. Fractal clusters are created in the early stage of aggregation, each of which is characterized by a dense core and sparse perimeter. These clusters grow in size until they percolate at the gel point by knitting together at the perimeters. The gel structure possesses a "blob-and-link" architecture, with the blobs representing the rigid cores of the fractal clusters, and the links corresponding to the tenuous chains formed between the clusters at percolation. Finite element analysis illustrates that the strain energy always localizes at the links in the DLCADEF gels. Therefore the stiffness of an aerogel is reduced by the presence of these compliant links. The key to synthesizing stiffer gels is to homogenize the distribution and cross-linking of mass during the formation of the network.

  2. Sol-gel synthesis of lithium aluminate

    International Nuclear Information System (INIS)

    LiAlO2 was prepared by two sol-gel methods using simultaneous hydrolysis of the reagents: aluminum sec-butoxide/lithium methoxide and aluminum sec-butoxide/LiOH. The resulting ceramic powders were compared with those prepared by two conventional methods (i.e., solid-state fusion and peroxide). The sol-gel method provided powders with a very high ?-LiAlO2 content after calcining at temperatures as low as 700 C when LiOH was used. The solids were characterized by AAS, DTA, TGA, XRD, and SEM

  3. Development of Stable Restructured Mango Gel

    OpenAIRE

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

    2007-01-01

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

  4. Aggregation of model gels with directional interactions

    International Nuclear Information System (INIS)

    We analyze connectivity and space-filling properties of colloidal gels obtained in a model with directional interactions. We compare gels formed upon slow cooling with the ones produced via quenching. The aggregation process is qualitatively different upon quenching: the cluster size distribution shows a percolation type of behavior but not the fully connected network achieved upon slow cooling. Because quenching favors the formation of defects, differently from systems where quenching tends to produce lower local connectivity and more open structures, here it favors instead more connected, but less space-filling, structures.

  5. Benzoyl peroxide stability in pharmaceutical gel preparations.

    Science.gov (United States)

    Bollinger, J N; Lewis, D; Mendez, V M

    1977-05-01

    The storage stability of benzoyl peroxide in the presence of both individual and combined pharmaceutical gel ingredients was investigated. Benzoyl peroxide was quite unstable in the presence of nucleophilic agents and certain acidic substances. At both 30 and 40 degrees storage temperatures, benzoyl peroxide was destroyed rapidly (within 1 month) in the presence of ethanol and acidic chelating agents. The substitution of acetone for ethanol, the elimination of chelating agents, and the addition of sodium hydroxide to gel preparations markedly reduced degradation. PMID:874757

  6. Dynamic Light Scattering From Colloidal Gels

    Science.gov (United States)

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

    1996-01-01

    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.

  7. Process for encapsulating active agents in gels

    OpenAIRE

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

    2001-01-01

    The present invention relates to a process for encapsulating an active agent in a biopolymer in the form of a gel, comprising the steps of: a) forming a dispersion or solution of the biopolymer in water; and b) adding the active agent to the dispersion or solution obtained in step a); wherein the biopolymer is at least partially dissolved before and/or after addition of the active agent. The gels obtained with the present invention are particularly suitable for coating or impregnating packagi...

  8. Free forming of the gel by 3D gel printer SWIM-ER

    Science.gov (United States)

    Okada, Koji; Tase, Taishi; Saito, Azusa; Makino, Masato; Gong, Jin; Kawakami, Masaru; Furukawa, Hidemitsu

    2015-04-01

    Gels, soft and wet materials, have unique properties such as material permeability, biocompatibility and low friction, which are hardly found in hard and dry materials. These superior characteristics of hydrogels promise to expand the medical applications. In recent years, the optical 3D gel printer named SWIM-ER (Soft and Wet Industrial - Easy Realizer) was developed by our team in order to fabricate tough gels with free form. We are aiming to create artificial blood vessel of the gel material by 3D gel printer. Artificial blood vessel is expected to be used for vascular surgery practice. The artificial blood vessel made by 3D gel printer can be create to free form on the basis of the biological data of the patient. Therefore, we believe it is possible to contribute to increasing the success rate and safety of vascular surgery by creating artificial blood vessel with 3D gel printer. The modeling method of SWIM-ER is as follow. Pregel solution is polymerized by one-point UV irradiation with optical fiber. The irradiation area is controlled by computer program, so that exact 3D free forming is realized. In this study, synthesis conditions are re-examined in order to improve the degree of freedom of fabrication. The dimensional accuracy in height direction is improved by increasing the cross linker concentration. We examined the relationship of resolution to the pitch and UV irradiation time in order to improve the modeling accuracy.

  9. 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 treatment planning system and the film measurement

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

    Science.gov (United States)

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

    2012-05-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  13. 3D gel printing for soft-matter systems innovation

    Science.gov (United States)

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

    2015-04-01

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

  14. 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)

    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

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

  15. Accumulation of humic acid in DET/DGT gels

    Digital Repository Service at National Institute of Oceanography (India)

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

    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...

  16. Multicomponent gels: Remote control for self-assembly

    Science.gov (United States)

    Kar, Haridas; Ghosh, Suhrit

    2015-10-01

    A patterned, spatially resolved gel has now been devised. The two-component gel is formed by sequential assembly of two independent networks of fibres, and the subsequent selective removal of one network by irradiation.

  17. Radiation induced synthesis of fast response stimuli responsive gels

    International Nuclear Information System (INIS)

    EB irradiation offers a unique method of synthesizing extremely fast-response temperature sensitive gels due to heterogeneous network structure produced during irradiation. These gels can be used as very efficient recyclable absorbents for many industrial applications

  18. Sol-Gel Synthesis Of Aluminoborosilicate Powders

    Science.gov (United States)

    Bull, Jeffrey; Leiser, Daniel; Selvaduray, Guna

    1992-01-01

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

  19. Sol-Gel Derived Hafnia Coatings

    Science.gov (United States)

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

    2002-01-01

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

  20. Gels and microgels for nanotechnological applications.

    Science.gov (United States)

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

    2009-01-01

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

  1. Non-diffusing radiochromic micelle gel

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-11-01

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

  2. Non-diffusing radiochromic micelle gel

    International Nuclear Information System (INIS)

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

  3. The charge transport in polymeric gel electrolytes

    International Nuclear Information System (INIS)

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

  4. Simple Cloud Chambers Using Gel Ice Packs

    Science.gov (United States)

    Kamata, Masahiro; Kubota, Miki

    2012-01-01

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

  5. Gel bead composition for metal adsorption

    International Nuclear Information System (INIS)

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

  6. Sol-gel Application in the Environment.

    Czech Academy of Sciences Publication Activity Database

    Kaštánek, František; Šolcová, Olga; Maléterová, Ywetta

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

  7. Bioluminescent Bioreporters Encapsulated in Silica Gel.

    Czech Academy of Sciences Publication Activity Database

    Kuncová, Gabriela; Trögl, J.; Demnerová, K.; Ripp, S.; Sayler, G. S.

    - : -, 2008, O08-2 - 1-O08-2 - 4. [XVI International Conference on Bioencapsulation. Dublin (IE), 04.09.2008-06.09.2008] Institutional research plan: CEZ:AV0Z40720504 Keywords : bioluminescent bioreporter * silica gel * biosensor Subject RIV: CE - Biochemistry

  8. The repton model of gel electrophoresis

    OpenAIRE

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

    1996-01-01

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

  9. Disulfide-Functionalized Diblock Copolymer Worm Gels.

    Science.gov (United States)

    Warren, Nicholas J; Rosselgong, Julien; Madsen, Jeppe; Armes, Steven P

    2015-08-10

    Two strategies for introducing disulfide groups at the outer surface of RAFT-synthesized poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) (PGMA-PHPMA, or Gx-Hy for brevity) diblock copolymer worms are investigated. The first approach involved statistical copolymerization of GMA with a small amount of disulfide dimethacrylate (DSDMA, or D) comonomer to afford a G54-D0.50 macromolecular chain transfer agent (macro-CTA); this synthesis was conducted in relatively dilute solution in order to ensure mainly intramolecular cyclization and hence the formation of linear chains. Alternatively, a new disulfide-based bifunctional RAFT agent (DSDB) was used to prepare a G45-S-S-G45 (or (G45-S)2) macro-CTA. A binary mixture of a non-functionalized G55 macro-CTA was utilized with each of these two disulfide-based macro-CTAs in turn for the RAFT aqueous dispersion polymerization of 2-hydroxypropyl methacrylate (HPMA). By targeting a PHPMA DP of 130 and systematically varying the molar ratio of the two macro-CTAs, a series of disulfide-functionalized diblock copolymer worm gels were obtained. For both formulations, oscillatory rheology studies confirmed that higher disulfide contents led to stronger gels, presumably as a result of inter-worm covalent bond formation via disulfide/thiol exchange. Using the DSDB-based macro-CTA led to the strongest worm gels, and this formulation also proved to be more effective in suppressing the thermosensitive behavior that is observed for the nondisulfide-functionalized control worm gel. However, macroscopic precipitation occurred when the proportion of DSDB-based macro-CTA was increased to 50 mol %, whereas the DSDMA-based macro-CTA could be utilized at up to 80 mol %. Finally, the worm gel modulus could be reduced to that of a nondisulfide-containing worm gel by reductive cleavage of the inter-worm disulfide bonds using excess tris(2-carboxyethyl)phosphine (TCEP) to yield thiol groups. These new biomimetic worm gels are expected to exhibit enhanced muco-adhesion. PMID:26168078

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

    Science.gov (United States)

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

    1998-01-01

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

  11. Automatic DNA sequencing for electrophoresis gels using image processing algorithms

    OpenAIRE

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

    2011-01-01

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

  12. Preparation of silica by sol-gel method using formamide

    OpenAIRE

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

    2001-01-01

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

  13. Photochromic properties of spirooxazine dyes in ormocer gels and coatings

    OpenAIRE

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

    1992-01-01

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

  14. Gel-forming reagents and uses thereof for preparing microarrays

    Science.gov (United States)

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

    2010-11-09

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

  15. Interaction between Crosslinked Polyelectrolyte Gels and Oppositely Charged Surfactants

    OpenAIRE

    Nilsson, Peter

    2007-01-01

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

  16. Methods of Manufacturing Bioactive Gels from Extracellular Matrix Material

    Science.gov (United States)

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

    2015-01-01

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

  17. Ultraviolet absorption detection of DNA in gels

    International Nuclear Information System (INIS)

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

  18. Diffusion measurement in ferrous infused gel dosimeters

    International Nuclear Information System (INIS)

    Background: The compositions of Ferrous sulphate, Agarose and Xylenol orange dye and Ferrous sulphate, Gelatin and Xylenol orange dye in solution of distilled water and sulphuric acid are two tissue-equivalent gel dosimeters. Ionizing radiation causes oxidation of Fe2+ ion to Fe3+ ions which diffuse through the gel matrix and blur the image of absorbed dose over a period of hours after irradiation. Materials and methods: 25 m M sulphuric acid, 0.4 mm ferrous ammonium sulphate, 0.2 mm xylenol orange dye and 1% by weight agarose in distilled water named Agarose and Xylenol orange dye and 0.1 mm ferrous ammonium sulphate, 0.1 mm xylenol orange dye, 50 mm sulphuric acid and 5% by weight gelatin in distilled water named Gelatin and Xylenol orange dye are used as two gel dosimeters. All chemicals were supplied by Sigma Ald ridge Company, Germany. The gels were poured in Perspex casts and were irradiated to a beam of X ray from linear accelerators or X ray machine. Results: In this study diffusion coefficients of Agarose and Xylenol orange dye and Gelatin and Xylenol orange dye dosimeters have been measured through a computer program for different temperature. The ferric ion diffusion coefficient (D) for the Agarose and Xylenol orange dye and Gelatin and Xylenol orange dye dosimeters were measured as (1.19.±0.03) x 10-2 cm2.hr -1 and (0.83±0.03) x 10-2 cm2.hr-1 respectively at room temperature. Conclusion: For both dosimeters the diffusion coefficients decreased with gel storage temperatures down to 6 digC. Gelatin and Xylenol orange dye dosimeters have advantage of lower diffusion coefficient for a specified temperature

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

    Scientific Electronic Library Online (English)

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

    1999-08-01

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

  20. Gel polymer electrolytes based on PMMA III. PMMA gels containing cadmium.

    Czech Academy of Sciences Publication Activity Database

    Vondrák, Ji?í; Sedla?íková, M.; Velická, Jana; Klápšt?, B?etislav; Novák, V.; Reiter, Jakub

    2003-01-01

    Ro?. 48, ?. 8 (2003), s. 1001-1004. ISSN 0013-4686 R&D Projects: GA AV ?R IAA4032002; GA ?R GA104/02/0731; GA MŠk ME 216 Institutional research plan: CEZ:AV0Z4032918; CEZ:MSM 262200010 Keywords : gel polymer electrolytes * polymethylmethacrylate * cadmium gel electrolyte Subject RIV: CA - Inorganic Chemistry Impact factor: 1.996, year: 2003

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

    OpenAIRE

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

    2013-01-01

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

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

    OpenAIRE

    Hongbin Tan; Jianhua Zhang; Haiwa Bo

    2011-01-01

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

  3. Formulation and method for preparing gels comprising hydrous cerium oxide

    Science.gov (United States)

    Collins, Jack L; Chi, Anthony

    2013-05-07

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

  4. Nanoscale Silicon Dioxide Prepared by Sol-Gel Process

    OpenAIRE

    Hui Gao; Junling Yang

    2010-01-01

    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.

  5. Formulation and method for preparing gels comprising hydrous hafnium oxide

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-08-06

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

  6. 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

  7. On the scattering properties of polyelectrolyte gels

    Science.gov (United States)

    Barrat, Jean-Louis; Joanny, Jean-François; Pincus, Phil

    1992-08-01

    We present a simple model for scattering properties of polyelectrolyte gels at swelling equilibrium. In the weak screening limit where the Debye-Hückel screening length is larger than the mesh size of the gel, the direct electrostatic interactions are negligible and the swelling is driven by the osmotic pressure of the counterions. The tension created by this pressure is transmitted through the crosslinks to the elastic chains which behave as isolated chains with an applied force at their end points. The structure factor of the gel can be split into a frozen component due to the average concentration heterogeneities and a thermodynamic component due to concentration fluctuations. The frozen component has a peak at a wavevector of the order of the mesh size of the gel, the thermodynamic component has a peak at a higher wavevector of the order of the inverse transverse radius of the chains. At infinite times the dynamic structure factor relaxes towards the frozen component of the static structure factor. In the limit of small wavevectors the relaxation is diffusive with a diffusion constant equal to the Stokes diffusion constant of the Pincus blobs of the stretched chains. The diffusion constant shows a minimum at a wavevector of the order of the inverse transverse radius of the chains. Nous présentons un modèle simple pour étudier la diffusion de rayonnement par des gels polylectrolytes à l'équilibre de gonflement. Dans la limite d'écrantage faible où la longueur d'écran de Debye-Hückel est plus grande que la maille du gel, les interactions électrostatiques directes sont négligeables et le gonflement est dû à la pression osmotique des contreions. La tension créée par cette pression est transmise par les noeuds du gel aux chaines élastiques qui se comportent comme des chaines isolées avec une force extérieure appliquée aux extrémités. Le facteur de structure du gel est la somme d'une composante gelée due aux hétérogénéités de concentration figées et d'une composante thermodynamique due aux fluctuations de concentration. la composante gelée a un maximum pour un vecteur d'onde de l'ordre de l'inverse de la maille du gel et la composante thermodynamique a un maximum pour un vecteur d'onde beaucoup plus grand de l'ordre de l'inverse du rayon transverse des chaines. A temps longs, le facteur de structure dynamique relaxe vers la composante gelée du facteur de structure statique. A faible vecteur d'onde, la relaxation est diffusive avec un coefficient de diffusion de l'ordre du coefficient de diffusion de Stokes des blobs de Pincus des chaines étirées. Le coefficient de diffusion est minimal pour un vecteur d'onde de l'ordre de l'inverse du rayon transverse des chaines.

  8. 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

  9. 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 gel

  10. Modelling of the inhomogeneous interior of polymer gels

    Energy Technology Data Exchange (ETDEWEB)

    Shew, C-Y [Center for Engineered Polymeric Materials (CEPM), Department of Chemistry and Graduate Center, City University of New York, College of Staten Island, 2800 Victory Boulevard, NY 10314 (United States); Iwaki, Takafumi [Okayama Institute for Quantum Physics, 1-9-1 Kyoyama, Okayama 700-0015 (Japan)

    2006-04-19

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

  11. 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

  12. Laser-scanned Agarose Gel Sections for Radiation Field Mapping

    International Nuclear Information System (INIS)

    Purpose: A dedicated laser scanning system has been applied to the measurement of optical density change in ferrous sulphate-xylenol orange dye-agarose gel mixtures for applications in radiation field mapping. Methods and Materials: The gels were poured, irradiated, and optically scanned in Lucite casts providing a uniform gel section thickness of 1 cm. The gel sections were optically scanned both pre- and postirradiation to determine the optical density change in the gel and consequently the absorbed dose. Irradiations of the gel sections were performed with an orthovoltage unit and a linear accelerator. Results: For linear dose response up to 10 Gy, an appropriate gel mixture was found to be 0.4 mM Fe2+, 0.2 mM xylenol orange dye, 25 mM sulphuric acid, and 1% by weight agarose gel with a mixing temperature of 60 deg. C. In dosimetry of a 20 x 10 cm 6 MV wedged x-ray field, good agreement in terms of relative dose was found between the gel values and ionization chamber readings. However, in repeated experiments with the gel dosimeter involving calculation of absolute dose at various points in the wedged field, variations in absolute dose measurements of up to ± 5% were observed. Conclusion: The dosimetry technique involving laser scanning of agarose gel sections has potential for further applications in radiotherapy dosimetry

  13. G-Quadruplex Guanosine Gels and Single Walled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yuehua Yu

    2013-12-01

    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.

  14. Ordering phenomena in ABA triblock copolymer gels

    International Nuclear Information System (INIS)

    Temperature and concentration dependencies of the degree of order in ABA triblock copolymer gels are discussed. Two factors can influence the ordering phenomena: the conformation of the midblocks (links of the network) and the polydispersity of the endblock domains (nodes of the network). The latter is defined by the scattering density profile (polymer chain packing) at the domain boundary: a sharp boundary corresponds to less polydisperse domains and to increased order in the arrangement of the network nodes. The structure of the network can be described in terms of a highly distorted crystalline lattice with close-packed spheres or with cubic (presumably BCC) equilibrium morphology. The appearance of the latter is never detected in the gels with a stretched conformation of the midblock. (orig.)

  15. 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)

  16. 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)

  17. Advanced ceramics by sol-gel processing

    International Nuclear Information System (INIS)

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

  18. The Microrheology of Sickle Hemoglobin Gels

    OpenAIRE

    Zakharov, Mikhail N.; Aprelev, Alexey; Turner, Matthew S; Ferrone, Frank A

    2010-01-01

    Sickle cell disease is a rheological disease, yet no quantitative rheological data exist on microscopic samples at physiological concentrations. We have developed a novel method for measuring the microrheology of sickle hemoglobin gels, based on magnetically driven compression of 5- to 8-?m-thick emulsions containing hemoglobin droplets ?80 ?m in diameter. Using our method, by observing the expansion of the droplet area as the emulsion is compressed, we were able to resolve changes in thickne...

  19. Ring-Resonator/Sol-Gel Interferometric Immunosensor

    Science.gov (United States)

    Bearman, Gregory; Cohen, David

    2007-01-01

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

  20. Artificial fibrin gels for blood vessel engineering.

    Czech Academy of Sciences Publication Activity Database

    Riedel, Tomáš; Brynda, Eduard; Chlupá?, Jaroslav; Filová, Elena; Ba?áková, Lucie; Dyr, J. E.

    Praha : Institute of Macromolecular Chemistry, 2009. s. 64. ISBN 978-80-85009-59-0. [Prague Meetings on Macromolecules /73./ New Frontiers in Macromolecular Science: From Macromolecular Concepts of Living Matter to Polymers for Better Quality of Life. 05.07.2009-09.07.2009, Prague] Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z50110509 Keywords : artificial fibrin gels * polyethylene terephthalate Subject RIV: CD - Macromolecular Chemistry

  1. Films by sol-gel processes

    OpenAIRE

    Schmidt, Helmut K.

    1988-01-01

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

  2. Gel Evolution in Oil Based Drilling Fluids

    OpenAIRE

    Sandvold, Ida

    2012-01-01

    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...

  3. Sol-gel method for encapsulating molecules

    Science.gov (United States)

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

    2002-01-01

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

  4. Sol–gel processing of carbidic glasses

    Indian Academy of Sciences (India)

    L M Manocha; E Yasuda; Y Tanabe; S Manocha; D Vashistha

    2000-02-01

    Carbon incorporation into the silicate network results in the formation of rigid carbidic glasses with improved physical, mechanical and thermal properties. This generated great interest in the development of these heteroatom structured materials through different processing routes. In the present studies, sol–gel processing has been used to prepare silicon based glasses, especially oxycarbides through organic–inorganic hybrid gels by hydrolysis–condensation reactions in silicon alkoxides, 1,4-butanediol and furfuryl alcohol with an aim to introduce Si–C linkages in the precursors at sol level. The incorporation of these linkages has been studied using IR and NMR spectroscopy. These bonds, so introduced, are maintained throughout the processing, especially during pyrolysis to high temperatures. In FFA–TEOS system, copolymerization with optimized mol ratio of the two results in resinous mass. This precursor on pyrolysis to 1000°C results in Si–O–C type amorphous solid black mass. XRD studies on the materials heated to 1400°C exhibit presence of crystalline Si–C and cristobalites in amorphous Si–O–C mass. In organic–inorganic gel system, the pyrolysed mass exhibits phase stability up to much higher temperatures. The carbidic materials so produced have been found to exhibit good resistance against oxidation at 1000°C.

  5. PRONIOSOMAL GEL OF FLURBIPROFEN: FORMULATION AND EVALUATION

    Directory of Open Access Journals (Sweden)

    Prajapati SK

    2012-01-01

    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.

  6. Gel Electrophoresis of Gold-DNA Nanoconjugates

    Directory of Open Access Journals (Sweden)

    W. J. Parak

    2008-03-01

    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.

  7. Sterilizable gels from thermoresponsive block copolymer worms.

    Science.gov (United States)

    Blanazs, Adam; Verber, Robert; Mykhaylyk, Oleksandr O; Ryan, Anthony J; Heath, Jason Z; Douglas, C W Ian; Armes, Steven P

    2012-06-13

    Biocompatible hydrogels have many applications, ranging from contact lenses to tissue engineering scaffolds. In most cases, rigorous sterilization is essential. Herein we show that a biocompatible diblock copolymer forms wormlike micelles via polymerization-induced self-assembly in aqueous solution. At a copolymer concentration of 10.0 w/w %, interworm entanglements lead to the formation of a free-standing physical hydrogel at 21 °C. Gel dissolution occurs on cooling to 4 °C due to an unusual worm-to-sphere order-order transition, as confirmed by rheology, electron microscopy, variable temperature (1)H NMR spectroscopy, and scattering studies. Moreover, this thermo-reversible behavior allows the facile preparation of sterile gels, since ultrafiltration of the diblock copolymer nanoparticles in their low-viscosity spherical form at 4 °C efficiently removes micrometer-sized bacteria; regelation occurs at 21 °C as the copolymer chains regain their wormlike morphology. Biocompatibility tests indicate good cell viabilities for these worm gels, which suggest potential biomedical applications. PMID:22582795

  8. Decontamination using chemical gels, electrolytical swab, abrasives

    International Nuclear Information System (INIS)

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

  9. Different Applications of Rheological Techniques in Studies of Physical Gels

    DEFF Research Database (Denmark)

    Hvidt, SØren

    Physical gels are of both great scientific and practical interest. The cytoplasm of cells, which consists of a complex physical gel of protein filaments, is important for most of the cellular processes including cell division and cell motility. Nature has developed this complex system of associating protein filaments with the characteristic function of individual filaments. The proteins enable the cell to regulate the mechanical properties of the cell by sol-gel transition and a variety of crosslinking reactions. In the food industry texture of products are regulated by addition of gel-forming biopolymers. Physical gels are also used in the paint industry to minimize sedimentation. Delayed and controlled drug release is of importance in the pharmaceutical industry, and one way to obtain this control is to hide active components in physical gels. Two excellent reviews cover many aspects of biopolymer and physical gels [1,2]. The nature of physical gels has been debated for many years. In contrast to chemicallycrosslinked gels physical gels are often thermoreversible and small changes in e.g. temperature, pH or ionic strength may shift the system from a gel state to a sol state. Ole Kramer [3] pointed out the importance of time scales for physical gels. According to him the characteristic property of a gel is the presence of two components and a constant elastic storage modulus on time scales of 1 s or frequencies of 1 rad/s. His definition of gels relies on their rheological properties. Rheological techniques are used extensively in studies of physical gels and gelation. In the lecture some of the common techniques used in studies of gels will be addressed. Small amplitude oscillatory measurements are the most common type of measurement performed, and such measurements allow a determination of the elastic storage modulus, G’, and loss modulus, G”, as a function of e.g. frequency, temperature, or time. Two other techniques, which can be very useful for studies of gels, are creep and relaxation measurements. These techniques, which allow determinations of the compliance and the relaxation modulus, respectively, are particularly useful for investigating slow motions in gels and long-time properties. An example of how these different techniques have been used to investigate the rheological properties of sputum [4] will be discussed. The results demonstrate that sputum is a viscoelastic material and that both nucleic acids and actin filaments contribute to the viscoelastic properties of sputum from cystic fibrosis patients. Many simple methods have been developed over the years in industry to characterize products. The SAG test is widely used in the food industry to grade pectin samples and their ability to form gels. The test, which consists of a SAG measurement due to gravity of gels with a very precisely defined shape, is highly reproducible. However, it does not give any information about fundamental rheological properties of the pectin gels. Our attempt to understand more fundamental aspects of this test combined creep and oscillatory measurements together with finite element simulation. The results show [5] that pectin gels can be modeled as nearly ideal incompressible elastic materials, and equations connecting SAG number and the elastic storage modulus have been obtained. Solutions of tri-block copolymers of ethylene oxide and propylene oxide form micelles in water with increasing temperature due to the hydrophobic nature of poly(propylene oxide) at higher temperatures. At high concentration micelles pack in bcc structures and various other gel structures are also formed. The gel properties are dominated by repulsive interactions between micelles, and oscillatory measurements allow a determination of the repulsive potential between micelles. Oscillatory bulk modulus measurements have been used to determine the dynamics of unimer-micelle motions. The strain properties of physical gels are of major importance in many applications. When a gel is deformed with increasing strain or strain amplitudes most gels eventually

  10. Dynamics around the sol-gel transition in thermoreversible polymer gels

    Science.gov (United States)

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

    2004-03-01

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

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

    International Nuclear Information System (INIS)

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

  12. Responsive Gel-Gel Phase Transitions in Artificially Engineered Protein Hydrogels

    Science.gov (United States)

    Olsen, B. D.

    2012-02-01

    Artificially engineered protein hydrogels provide an attractive platform for biomedical materials due to their similarity to components of the native extracellular matrix. Engineering responsive transitions between shear-thinning and tough gel phases in these materials could potentially enable gels that are both shear-thinning and tough to be produced as novel injectable biomaterials. To engineer a gel with such transitions, a triblock copolymer with thermoresponsive polymer endblocks and an artificially engineered protein gel midblock is designed. Temperature is used to trigger a transition from a single network protein hydrogel phase to a double network phase with both protein and block copolymer networks present at different length scales. The thermodynamics of network formation and resulting structural changes are established using small-angle scattering, birefringence, and dynamic scanning calorimetry. The formation of the second network is shown to produce a large, nonlinear increase in the elastic modulus as well as enhancements in creep compliance and toughness. Although the gels show yielding behavior in both the single and double network regimes, a qualitative change in the deformation mechanism is observed due to the structural changes.

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

    Science.gov (United States)

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

    2010-03-01

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

  14. Ionogel Electrolytes through Sol-Gel Processing

    Science.gov (United States)

    Horowitz, Ariel I.

    Electrical energy needs have intensified due to the ubiquity of personal electronics, the decarbonization of energy services through electrification, and the use of intermittent renewable energy sources. Despite developments in mechanical and thermal methods, electrochemical technologies are the most convenient and effective means of storing electrical energy. These technologies include both electrochemical cells, commonly called batteries, and electrochemical double-layer capacitors, or "supercapacitors", which store energy electrostatically. Both device types require an ion-conducting electrolyte. Current devices use solutions of complex salts in organic solvents, leading to both toxicity and flammability concerns. These drawbacks can be avoided by replacing conventional electrolytes with room-temperature molten salts, known as ionic liquids (ILs). ILs are non-volatile, non-flammable, and offer high conductivity and good electrochemical stability. Device mass can be reduced by combining ILs with a solid scaffold material to form an "ionogel," further improving performance metrics. In this work, sol-gel chemistry is explored as a means of forming ionogel electrolytes. Sol-gel chemistry is a solution-based, industrially-relevant, well-studied technique by which solids such as silica can be formed in situ. Previous works used a simple acid-catalyzed sol-gel reaction to create brittle, glassy ionogels. Here, both the range of products that can be accomplished through sol-gel processing and the understanding of interactions between ILs and the sol-gel reaction network are greatly expanded. This work introduces novel ionogel materials, including soft and compliant silica-supported ionogels and PDMS-supported ionogels. The impacts of the reactive formulation, IL identity, and casting time are detailed. It is demonstrated that variations in formulation can lead to rapid gelation and open pore structures in the silica scaffold or slow gelation and more dense silica morphologies. The IL identity is shown to have an impact on the apparent strength of the acid catalyst, leading to significant shifts in gelation time. Delayed casting is proven to be an optimal technique for avoiding pore blockage when combining ionogels with high surface area electrodes for supercapacitor applications. Finally, a simple recycling process is proposed, establishing that ILs can be easily reclaimed from silica-supported ionogels and reused, thereby validating the reputation of ILs as "green" materials.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P., E-mail: michelledunin@yahoo.com.b [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)

    2010-07-01

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

  16. Deuterium isotope effect on swelling process in aqueous polymer gels

    International Nuclear Information System (INIS)

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

  17. Vaginal deployment and tenofovir delivery by microbicide gels.

    Science.gov (United States)

    Gao, Y; Yuan, A; Chuchuen, O; Ham, A; Yang, K H; Katz, D F

    2015-06-01

    Gels are one of the soft material platforms being evaluated to deliver topically acting anti-HIV drugs (microbicides) to the vaginal environment. For each drug, its loaded concentration, gel properties and applied volume, and frequency of dosing can be designed to optimize PK and, thence, PD. These factors also impact user sensory perceptions and acceptability. Deterministic compartmental modeling of vaginal deployment and drug delivery achieved by test gels can help delineate how multiple parameters characterizing drug, vehicle, vaginal environment, and dosing govern details of PK and PD and also gel leakage from the canal. Such microbicide delivery is a transport process combining convection, e.g., from gel spreading along the vaginal canal, with drug diffusion in multiple compartments, including gel, mucosal epithelium, and stroma. The present work builds upon prior models of gel coating flows and drug diffusion (without convection) in the vaginal environment. It combines and extends these initial approaches in several key ways, including: (1) linking convective drug transport due to gel spreading with drug diffusion and (2) accounting for natural variations in dimensions of the canal and the site of gel placement therein. Results are obtained for a leading microbicide drug, tenofovir, delivered by three prototype microbicide gels, with a range of rheological properties. The model includes phosphorylation of tenofovir to tenofovir diphosphate (which manifests reverse transcriptase activity in host cells), the stromal concentration distributions of which are related to reference prophylactic values against HIV. This yields a computed summary measure related to gel protection ("percent protected"). Analyses illustrate tradeoffs amongst gel properties, drug loading, volume and site of placement, and vaginal dimensions, in the time and space history of gel distribution and tenofovir transport to sites of its anti-HIV action and concentrations and potential prophylactic actions of tenofovir diphosphate therein. PMID:25874971

  18. Analysis of variations in band positions for normalization in across-gel denaturing gradient gel electrophoresis.

    Science.gov (United States)

    Matsushita, Yuko; Yamamura, Kohji; Morimoto, Sho; Bao, Zhihua; Kurose, Daisuke; Sato, Ikuo; Yoshida, Shigenobu; Tsushima, Seiya

    2015-05-01

    Variation in band position between gels is a well-known problem in denaturing gradient gel electrophoresis (DGGE). However, few reports have evaluated the degree of variation in detail. In this study, we investigated the variation in band positions of DNA samples extracted from soil, normalized using reference positions within marker lanes for DGGE in three organismal (bacterial, fungal, and nematode) conditions. For sample lanes, marker DNA (as a control) and sample DNA were used. The test for normality of distribution showed that the position data of a large percentage of bands were normally distributed but not for certain bands. For the normally-distributed data, their variations [standard deviation of marker bands (SDM) and standard deviation of sample bands (SDS), respectively] were assessed. For all organismal conditions, the degree of within-gel variation were similar between SDMs and SDSs, while between-gel variations in SDSs were larger than those in SDMs. Due to the large effect of between-gel variations, the total variations in SDSs were more varied between sample bands, and the mean variations of all sample bands were higher than those in the markers. We found that the total variation in the fungal and nematode SDSs decreased when the intervals between marker bands were narrowed, suggesting that band interval is important for reducing total variation in normalized band positions. For the non-normally distributed data, the distribution was examined in detail. This study provided detailed information on the variation of band positions, which could help to optimize markers for reducing band position variation, and could aid in the accurate identification of bands in across-gel DGGE analyses. PMID:25725304

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2002-01-01

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

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

    OpenAIRE

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

    1983-01-01

    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...

  2. 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

  3. A simple gel electrophoresis method for separating polyhedral gold nanoparticles

    Science.gov (United States)

    Kim, Suhee; Lee, Hye Jin

    2015-07-01

    In this paper, a simple approach to separate differently shaped and sized polyhedral gold nanoparticles (NPs) within colloidal solutions via gel electrophoresis is described. Gel running parameters for separating efficiently gold NPs including gel composition, added surfactant types and applied voltage were investigated. The plasmonic properties and physical structure of the separated NPs extracted from the gel matrix were then investigated using transmission electron microscopy (TEM) and UV-vis spectrophotometry respectively. Data analysis revealed that gel electrophoresis conditions of a 1.5 % agarose gel with 0.1 % sodium dodecyl sulfate (SDS) surfactant under an applied voltage of 100 V resulted in the selective isolation of ~ 50 nm polyhedral shaped gold nanoparticles. Further efforts are underway to apply the method to purify biomolecule-conjugated polyhedral Au NPs that can be readily used for NP-enhanced biosensing platforms.

  4. Fabrication of nanocrystalline cobalt oxide via sol-gel coating

    International Nuclear Information System (INIS)

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

  5. Fabrication of nanocrystalline cobalt oxide via sol-gel coating

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-11-25

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

  6. A NOVEL OPHTHALMIC DRUG DELIVERY SYSTEM: IN-SITU GEL

    Directory of Open Access Journals (Sweden)

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

    2012-09-01

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

  7. FORMULATION AND EVALUATION OF POLYHERBAL GEL FOR ANTI - INFLAMMATORY ACTIVITY

    Directory of Open Access Journals (Sweden)

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

    2013-03-01

    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.

  8. Introduction and overview of problems related to the gel

    International Nuclear Information System (INIS)

    During alteration of most nuclear glasses in aqueous media, an alteration film or gel forms on the glass surface. This gel is characterized by 2 significant properties: -1) Its role as a diffusion barrier, the apparent silicon diffusion coefficients in the interstitial water of the gel, derived by fitting the curves for R7T7 glass leaching experiments, are very low: in the order of 10-16 m2.s-1 at 90 Celsius degrees. These values assume very small gel pore dimension (a few nanometers) and strong silicon adsorption on the gel. -2) Its significant retention capacity for some radionuclides such as rare earth elements and actinides, which significantly diminishes the flow of radioelements released from the glass package. A lot of experimental and more theoretical studies are needed to understand nuclear gels as material in order to model them and estimate their evolution over long periods of time. (A.C.)

  9. Polyacrylamide gel with switchable trypsin activity for analysis of proteins.

    Science.gov (United States)

    Liu, Fangjie; Ye, Mingliang; Wang, Chunli; Hu, Zhengyan; Zhang, Yi; Qin, Hongqiang; Cheng, Kai; Zou, Hanfa

    2013-08-01

    Trypsin was immobilized on a variety of materials to improve digestion efficiency. However, because the immobilized trypsin will digest proteins during electrophoresis, direct immobilization of active trypsin in polyacrylamide gel will compromise the protein separation. To overcome this problem, here we report a novel polyacrylamide gel with switchable trypsin activity. It was prepared by copolymerization of the PEG-trypsin-aprotinin complex during the gel-casting step. Because the inhibitor aprotinin binds strongly with trypsin at alkaline pH, this novel gel does not display hydrolytic activity during electrophoresis. After electrophoresis, the activity of trypsin embedded in gel could be recovered by simply washing away the bound inhibitor at a low pH. It was demonstrated that this unique switchable activity design allowed high resolution of the complex protein mixture during electrophoresis and highly efficient digestion of the separated proteins in situ in the gel after electrophoresis. PMID:23855779

  10. Sol-gel chromogenic materials and devices

    OpenAIRE

    Aegerter, Michel A.

    1996-01-01

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

  11. Stimuli responsive polymer gels for sensing applications

    OpenAIRE

    Kavanagh, Andrew

    2012-01-01

    This chapter (3) is based on simplifying the design template of an optical sensor through the multifunctionality imparted on it by an IL. The IL simplified polymer gel is termed an optode within this chapter as (a) it is prepared the same manner as optodes, (b) the IL performs many of the same functions as previous materials used in optode design and (c) the analyte or ion movement between the aqueous and organic phases follows the same convention for optodes. The 2-component optode membr...

  12. Alignment and Nonlinear Elasticity in Biopolymer Gels

    CERN Document Server

    Feng, Jingchen; Sander, Leonard M

    2014-01-01

    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.

  13. Repton model of gel electrophoresis and diffusion

    OpenAIRE

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

    1991-01-01

    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...

  14. Screening of mucoadhesive vaginal gel formulations

    Scientific Electronic Library Online (English)

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

    2014-12-01

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

  15. Hybrid slab-microchannel gel electrophoresis system

    Science.gov (United States)

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

    1998-01-01

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

  16. Cervical ripening with prostaglandin gel and hygroscopic dilators.

    OpenAIRE

    Hibbard, J U; Shashoua, A; Adamczyk, C; M. Ismail

    1998-01-01

    OBJECTIVE: To study the effectiveness and morbidity of adding hygroscopic cervical dilators to prostaglandin gel for cervical ripening and labor induction. STUDY DESIGN: Patients of at least 34 weeks' gestation with a medical indication for induction of labor and with a modified Bishop score of 5 or less were randomized to receive either prostaglandin gel or prostaglandin gel with hygroscopic cervical dilators. Primary outcomes were time to delivery, change in cervical score, and infection. S...

  17. Preparation of biomolecule gel matrices for electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-03-15

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

  18. Guidelines for reporting the use of gel electrophoresis in proteomics.

    OpenAIRE

    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

    2008-01-01

    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...

  19. Controlled Release Gel Formulations for Mucosal Drug Delivery

    OpenAIRE

    Paulsson, Mattias

    2001-01-01

    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 propertie...

  20. Progress on sol-gel sphere-pac development

    International Nuclear Information System (INIS)

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

  1. Solid phase technology improves coupled gel shift/footprinting analysis.

    OpenAIRE

    Ragnhildstveit, E.; Fjose, A; Becker, P B; Quivy, J P

    1997-01-01

    For the analysis of protein-DNA interactions by coupled gel-shift/footprinting, DNA fragments need to be extracted from polyacrylamide gels and subsequently separated on high resolution gels. Due to impurities in the extracted DNA, single nucleotide resolution is frequently not achieved. We now describe an improved experimental strategy that employs transient coupling of DNA fragments to a solid support in order to extract DNA of high purity quantitatively, rapidly and reliably. As an example...

  2. In Vitro Models of Angiogenesis and Vasculogenesis in Fibrin Gel

    OpenAIRE

    Morin, Kristen T.; Tranquillo, Robert T

    2013-01-01

    In vitro models of endothelial assembly into microvessels are useful for the study of angiogenesis and vasculogenesis. In addition, such models may be used to provide the microvasculature required to sustain engineered tissues. A large range of in vitro models of both angiogenesis and vasculogenesis have utilized fibrin gel as a scaffold. Although fibrin gel is conducive to endothelial assembly, its ultrastructure varies substantially based on the gel formulation and gelation conditions, maki...

  3. Electrophoretic properties of the scrapie agent in agarose gels.

    OpenAIRE

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

    1980-01-01

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

  4. Engineering new supramolecular gels: From catalysis to drug delivery

    OpenAIRE

    Bachl, Jürgen

    2015-01-01

    The present dissertation evaluates the design, characterization and potential applications of functional supramolecular gel-materials. Gels have attracted tremendous scientific interest as they can be obtained from natural sources or derive from readily available building blocks by facile preparation methods. They have conquered our daily life appearing as constituents of commercial products in the fields of biomedicine, agriculture, cosmetics, food thickeners and many more. Gel-materials exh...

  5. Stimuli responsive smart-gels realized via modular protein design

    OpenAIRE

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

    2010-01-01

    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 ...

  6. Effect of heat on the adsorption properties of silica gel

    OpenAIRE

    Christy, Alfred A.

    2012-01-01

    Adsorption properties of silica gel have been attributed to the surface hydroxyl groups of silica gel. Some hydroxyl groups are free standing and called free silanol groups. Some are hydrogen bonded to neighbouring silanol groups. Christy has shown that a high silanol number and a balanced concentration proportionality between these two different types of hydroxyl groups is necessary for effective adsorption of water molecules. Thermal treatment of silica gel samples alters the proportions of...

  7. formulation and evaluation of topical gel of aceclofenac

    OpenAIRE

    tarun kumar guleri

    2013-01-01

    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 cell...

  8. Different Applications of Rheological Techniques in Studies of Physical Gels

    DEFF Research Database (Denmark)

    Hvidt, Søren

    2006-01-01

    Physical gels are of both great scientific and practical interest. The cytoplasm of cells, which consists of a complex physical gel of protein filaments, is important for most of the cellular processes including cell division and cell motility. Nature has developed this complex system of associating protein filaments with the characteristic function of individual filaments. The proteins enable the cell to regulate the mechanical properties of the cell by sol-gel transition and a variety of cross...

  9. Zirconium molybdate gel as a generator for technetium-99m

    International Nuclear Information System (INIS)

    A new sup(99m)Tc generator based on zirconium molybdate gel is described. Essentially the gel is a cation ion exchanger which permits the elution of the pertechnetate ion. The high molybdenum content of this gel, its stability under self-irradiation, and the absence of organic materials during preparation provide a generator concept that eliminates high processing costs, active waste storage costs and stability problems in other types of generator

  10. Size Effects on Diffusion Processes within Agarose Gels

    OpenAIRE

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

    2004-01-01

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

  11. The Substitute Brain and the Potential of the Gel Model

    OpenAIRE

    Pomfret, Roland; Miranpuri, Gurwattan; Sillay, Karl

    2013-01-01

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

  12. Antimicrobial activity and the mechanism of silver nanoparticle thermosensitive gel

    Directory of Open Access Journals (Sweden)

    Chen M

    2011-11-01

    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

  13. 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)

  14. Production of silica gel from residual rice husk ash

    OpenAIRE

    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

    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...

  15. FORMULATION AND EVALUATION OF POLYHERBAL GEL FOR ANTI - INFLAMMATORY ACTIVITY

    OpenAIRE

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

    2013-01-01

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

  16. Leading-edge-gel coupling in lamellipodium motion

    OpenAIRE

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

    2010-01-01

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

  17. 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)

    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

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

  18. Inclusion type radiochromic gel dosimeter for threedimensional dose verification

    Science.gov (United States)

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

    2015-01-01

    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.

  19. Electrophoretic separation of DNA in gels and nanostructures.

    Science.gov (United States)

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

    2009-09-01

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

  20. High Impulse Nanoparticulate-Based Gel Propellants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposed Small Business Innovative Research (SBIR) Phase I addresses the development of advanced gel propellants and determination of their suitability for...

  1. Sol-gel materials for optofluidics - process and applications

    DEFF Research Database (Denmark)

    Mikkelsen, Morten Bo Lindholm

    2011-01-01

    This Ph.D. thesis is concerned with the use of sol-gel materials in optofluidic applications and the physics of DNA molecules in nanoconfinement. The bottom-up formation of solid material, which is provided by the sol-gel process, enables control of the chemical composition and porosity of the material. At early stages of gelation, thin gel coatings can be structured by nanoimprint lithography, and purely inorganic silica materials can be obtained by subsequent thermal annealing. The sol-gel pro...

  2. Time to first fracture affects sweetness of gels

    OpenAIRE

    Sala, G.; Stieger, M.A.

    2013-01-01

    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 ?F =...

  3. The entrance dynamics of polymers into a gel

    CERN Document Server

    Kob, W; Kob, Walter; Cugliandolo, Leticia F.

    2000-01-01

    We use computer simulations to study the (driven) dynamics of a charged polymer in a disordered medium, thus mimicking the setting used in gel electrophoresis. In agreement with experiments, we find that inside the gel the mobility of the polymer is only a weak function of its length N. In contrast to this, the mean entrance time into the gel, is a very strong function of N, \\propto N^1.3, and does not show any sign of saturation with increasing N. We rationalize this effect by means of a simple model and propose an experimental setup that should allow to increase the separation ability of gel electrophoresis significantly.

  4. Production of silica gel from residual rice husk ash

    Directory of Open Access Journals (Sweden)

    Samantha Pinheiro Buás de Lima

    2011-01-01

    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.

  5. 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

  6. Production of silica gel from residual rice husk ash

    Scientific Electronic Library Online (English)

    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.

    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 obta [...] ined 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.

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

    OpenAIRE

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

    2009-01-01

    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...

  8. Composite gel electrolyte for rechargeable lithium batteries

    Science.gov (United States)

    Slane, S.; Salomon, M.

    Composite polymer electrolyte films consisting of zeolite powders dispersed in poly(acrylonitrile) (PAN)-based gels with LiAsF 6 have been prepared and their electrochemical properties studied. Gel electrolytes prepared by adding LiAsF 6 in propylene carbonate (PC) and ethylene carbonate (EC) mixtures with PAN have demonstrated ionic conductivities greater than 10 -3 S/cm at room temperature and above. The addition of zeolite powders increased ionic conductivity at low temperatures due to the highly amorphous nature of the composite film. Impedance spectroscopy was performed to study the Li electrode/electrolyte interface and a reduction of the passivation kinetics was observed. Cyclic voltammetry showed that addition of PAN and zeolite powder to LiAsF 6, PC and EC mixtures did not change the stable electrochemical potential window. In {Li}/{LiCoO 2} cells, at 25 °C, these composite electrolytes demonstrated current densities as high as 0.5 mA/cm 2, with little voltage or capacity loss compared with cells with liquid electrolytes.

  9. Probing convection and diffusion in macromolecular gels

    Science.gov (United States)

    de Rosa, Enrica; Netti, Paolo Antonio

    2005-03-01

    Transport of molecules within three-dimensional biological tissue occurs by both diffusion and convection. While diffusion is relatively well studied in the literature, there is a paucity of data on convection parameters, even if is the most effective transport mechanism for large molecules. Pressure-driven flow through complex macromolecular gels can provide different probe velocity depending on the diffusant molecule and matrix interaction and so far no specific measurements have been performed. Furthermore the complexity or heterogeneity of the system may cause differences with the position in the convection properties of the sample. In this study both diffusion coefficient and velocity of several fluorescent probes in macromolecular gels have been measured with a high spatial resolution (100?m). The macromolecular velocity has been evaluated by adopting the video-FRAP technique, through an algorithm to separate the fluorescence recovery due to the brownian motion and that due to a bulk convection. Combination of the two transport process is very relevant in tissue engineering and drug delivery application.

  10. Brownian Dynamics simulations of aging colloidal gels

    CERN Document Server

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

    2002-01-01

    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...

  11. 13C-nuclear magnetic resonance study of benzene derivatives, ketones, and 1-hexene adsorbed on silica-gel, silver-silica-gel, and trimethylsilanized-silica-gel

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  13. A basic study of some normoxic polymer gel dosimeters

    International Nuclear Information System (INIS)

    Polymer gel dosimeters offer a wide range of potential applications in the three-dimensional verification of complex dose distribution such as in intensity-modulated radiotherapy (IMRT). Until now, however, polymer gel dosimeters have not been widely used in the clinic. One of the reasons is that they are difficult to manufacture. As the polymerization in polymer gels is inhibited by oxygen, all free oxygen has to be removed from the gels. For several years this was achieved by bubbling nitrogen through the gel solutions and by filling the phantoms in a glove box that is perfused with nitrogen. Recently another gel formulation was proposed in which oxygen is bound in a metallo-organic complex thus removing the problem of oxygen inhibition. The proposed gel consists of methacrylic acid, gelatin, ascorbic acid, hydroquinone and copper(II)sulphate and is given the acronym MAGIC gel dosimeter. These gels are fabricated under normal atmospheric conditions and are therefore called 'normoxic' gel dosimeters. In this study, a chemical analysis on the MAGIC gel was performed. The composition of the gel was varied and its radiation response was evaluated. The role of different chemicals and the reaction kinetics are discussed. It was found that ascorbic acid alone was able to bind the oxygen and can thus be used as an anti-oxidant in a polymer gel dosimeter. It was also found that the anti-oxidants N-acetyl-cysteine and tetrakis(hydroxymethyl)phosphonium were effective in scavenging the oxygen. However, the rate of oxygen scavenging is dependent on the anti-oxidant and its concentration with tetrakis(hydroxymethyl)phosphonium being the most reactive anti-oxidants. Potentiometric oxygen measurements in solution provide an easy way to get a first impression on the rate of oxygen scavenging. It is shown that cupper(II)sulphate operates as a catalyst in the oxidation of ascorbic acid. We, therefore, propose some new normoxic gel formulations that have a less complicated chemical formulation than the MAGIC gel. (author)

  14. Effect of Polymer Hydration State on In-Gel Immunoassays.

    Science.gov (United States)

    Vlassakis, Julea; Herr, Amy E

    2015-11-01

    Applications as diverse as drug delivery and immunoassays require hydrogels to house high concentration macromolecular solutions. Yet, thermodynamic partitioning acts to lower the equilibrium concentration of macromolecules in the hydrogel, as compared to the surrounding liquid phase. For immunoassays that utilize a target antigen immobilized in the hydrogel, partitioning hinders introduction of detection antibody into the gel and, consequently, reduces the in-gel concentration of detection antibody, adversely impacting assay sensitivity. Recently, we developed a single-cell targeted proteomic assay with polyacrylamide gel electrophoresis of single cell lysates followed by an in-gel immunoassay. In the present work, we overcome partitioning that both limits analytical sensitivity and increases consumption of costly detection antibody by performing the immunoassay step after dehydrating the antigen-containing polyacrylamide gel. Gels are rehydrated with a solution of detection antibody. We hypothesized that matching the volume of detection antibody solution with the hydrogel water volume fraction would ensure that, at equilibrium, the detection antibody mass resides in the gel and not in the liquid surrounding the gel. Using this approach, we observe (compared with antibody incubation of hydrated gels): (i) 4-11 fold higher concentration of antibody in the dehydrated gels and in the single-cell assay (ii) higher fluorescence immunoassay signal, with up to 5-fold increases in signal-to-noise-ratio and (iii) reduced detection antibody consumption. We also find that detection antibody signal may be less well-correlated with target protein levels (GFP) using this method, suggesting a trade-off between analytical sensitivity and variation in immunoprobe signal. Our volume-matching approach for introducing macromolecular solutions to hydrogels increases the local in-gel concentration of detection antibody without requiring modification of the hydrogel structure, and thus we anticipate broad applicability to hydrogel-based assays, diagnostics, and drug delivery. PMID:26457450

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

    Science.gov (United States)

    Sen, Swati; Kundagrami, Arindam

    2015-12-14

    The swelling kinetics of uncharged and charged polymer (polyelectrolyte) gels in salt-free conditions is studied in one dimension by solving the constitutive equation of motion (Newton's law for the elementary gel volume) of the displacement variable by two theoretical methods: one in which the classical definition of stress is used with the bulk modulus taken as a parameter, and the other in which a phenomenological expression of the osmotic stress as a function of polymer density and degree of ionization is taken as an input to the dynamics. The time-evolution profiles for spatially varying polymer density and stress, along with the location of the gel-solvent interface, are obtained from the two methods. We show that both the polymer density (volume fraction) and stress inside the gel follow expected behaviours of being maximum for the uniformly shrunken gel, and relaxing slowly to the lowest values as the gel approaches equilibrium. We further show that, by comparing the temporal profiles of the gel-solvent interface and other variables between the two methods, one may attempt to assign an effective bulk modulus to the polyelectrolyte gel as a function of the degree of ionization and other parameters of the gel such as hydrophobicity, cross-link density, and the temperature. The major result we get is that the effective bulk modulus of a polyelectrolyte gel increases monotonically with its degree of ionization. In the process of identifying the parameters for a monotonic swelling, we calculated using a well-known expression of the free energy the equilibrium results of two-phase co-existence and the critical point of a polyelectrolyte gel with a fixed degree of ionization. PMID:26671401

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

    Directory of Open Access Journals (Sweden)

    Ali S. Salmani

    2009-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Jovanovi? Milijan

    2005-01-01

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

  18. 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)

  19. Long-range forces extending from polymer-gel surfaces

    OpenAIRE

    Zheng, Jian-ming; Pollack, Gerald H

    2003-01-01

    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.

  20. Biocatalysis with Sol-Gel Encapsulated Acid Phosphatase

    Science.gov (United States)

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

    2010-01-01

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

  1. Colloidal particle-size determination by gel filtration

    International Nuclear Information System (INIS)

    The particle size of technetium-99m sulfur colloid and technetium-99m antimony sulfide colloid are determined by gel filtration. These results are compared with those obtained by electron microscopy and by ultrafiltration. It is shown that gel filtration is suitable for particle-size determination below 100 nm, whereas above this size ultrafiltration provides the most convenient method

  2. Yielding of colloidal gels under steady and oscillatory shear

    Science.gov (United States)

    Petekidis, George; Moghimi, Esmaeel; Koumakis, Nick; Forth Team

    2015-03-01

    The structural and rheological properties of intermediate volume fraction colloid polymer gels are examined during and after steady and oscillatory shear flow using rheometry, confocal microscopy, light scattering and Brownian Dynamics simulations. Our main objective is to rationalize the microscopic mechanisms through which one can tune the mechanical properties of such metastable colloidal gels by imposing different types of external shear and flow. Experimentally, the gels consist of model hard sphere particle dispersions of ? = 0.44 with the addition of non-adsorbing linear chains, while BD simulations are conducted for hard spheres with the superposition of an AO potential for depletion attractions. Structural analysis shows that variation of the applied shear rate produces strong changes in the structure of the gels both when under shear and during gel reformation at cessation. Larger rates are characterized by disperse particles and the total breakage of structures at rest, which after cessation evolve with time into strong solids with relatively homogeneous structures. However, smaller rates show large inhomogeneous structures under flow, which do not evolve after cessation and additionally exhibit reduced elasticity and as such are weaker solids. Furthermore oscillatory shear is far more efficient than steady shear creating gels with stronger differences in their elastic modulus. Thus by tuning the way a gel is sheared, one may vary the final strength and structure of the resulting gel. Work in collaboration with R. Besseling, W. C. K. Poon and J. F. Brady

  3. Microelectromechanics of ionic polymeric gels as synthetic robotic muscles

    Science.gov (United States)

    Shahinpoor, Mohsen

    1994-05-01

    An ionic polymeric gel is defined as a 3-D charged network of a cross-linked macromolecular polyelectrolyte capable of collapsing or swelling in an acidic or alkaline environment, respectively, purely due to pH changes. Fixed electrical charges reside at all cross-links in such macromolecular networks in the presence of wandering mobile charges that tend to change their spatial distribution within the gel network. In the presence of an electric field, the mobile ions redistribute themselves in the gel network and thus cause the network to deform accordingly. A microelectro-mechanical model is presented that takes into account such internal electric charge redistribution of fixed and mobile ions due to the presence of an electric field. Direct computer control of large expansions and contractions of ionic polymeric gels by means of a voltage gradient appears to be possible. A mechanism is presented for the reversible nonhomogeneous large deformations and in particular bending of strips of ionic polymeric gels in the presence of an electric field. Exact expressions are given relating the deformation characteristics of the gel to the electric field strength or voltage gradient, gel dimensions and other physical parameters. It is concluded that direct voltage control of such nonhomogeneous large deformations in ionic polymeric gels is possible.

  4. 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)

  5. Development of Satranidazole Mucoadhesive Gel for the Treatment of Periodontitis

    OpenAIRE

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

    2009-01-01

    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...

  6. Control of flow through porous media using polymer gels

    Science.gov (United States)

    Zitha, Pacelli L. J.; Botermans, C. Wouter; Hoek, Jeroen v. d.; Vermolen, Fred J.

    2002-07-01

    We examine the effect of a dynamic stress on the reduction of flow in porous media using polymer gels formed in situ. To develop the theory for the response of the gel, we consider three dominant factors: (a) compressive (elastic) deformation of the gel and porous medium, (b) microscopic flow in this system, and (c) gel displacement. The latter occurs when the stress p is larger than a certain critical value pc, satisfying pcR2=constant (R=effective pore radius), where the constant is an increasing function of elastic modulus of the gel and its cross-linking energy. The expulsion of the gel above pc is reminiscent of growing Saffman-Taylor instabilities. To derive analytic expressions for the macroscopic saturation profiles we use the formalism for fully miscible two-phase flow. The equation of evolution of the pressure, established by mass balance arguments, was solved analytically. For pc, the pressure obeys an exponential saturation function while for pc, it first increases, reaches a maximum value, and then decreases towards an asymptotic value. These theoretical predictions are supported by our experiments consisting of injecting (salt) water at a constant flow rate in porous samples containing a organically cross-linked polymer gel (co-polymer of acrylamide and t-butyl-acrylate cross-linked using poly-ethylene-imine). The data confirms further that the product pcR2 is constant and prove that both pc and the maximum pressures increase with intrinsic gel strength.

  7. Some radiation and photochemical studies in aqueous polysaccharide gel systems

    International Nuclear Information System (INIS)

    The radiation and photochemistry of aqueous polysaccharide gel matrices have been investigated with a view to prolonging the lifetime of transient species, prior to storage of photochemical events. Our results indicate that with gels of kappa carrageenan and agarose, the rigid macroscopic gel structure is not reflected in the microscopic structure and reactions resemble closely those that would take place in aqueous solution under comparable conditions. This shows that the interior of the gel structure is essentially very fluid. Fluorescence probes were used in agarose gel systems incorporating neutral and anionic surfactants. Under such circumstances, there is strong evidence showing that a micellar-type environment exists, and also a gel-surfactant complex is formed with both neutral and anionic surfactants. The gel-surfactant complex appears on the basis of fluorescence quenching and fluorescence polarization studies, to have a more mobile interior than the interior of an ordinary surfactant micelle in the absence of the agarose. Studies on the stoichiometry of the complex indicate a much lower critical micelle concentration for the surfactant sodium dodecyl sulphate (SDS) in the presence of agarose. The agarose gel structure does not aid the micellar catalysed charge separation that occurs on photolysis of pyrene. (author)

  8. Preparation and characterization of cellulose gels from corn cobs

    Science.gov (United States)

    Aqueous cellulose gels were prepared by extraction of ground corn cobs with hot aqueous sodium hydroxide/sodium hypochlorite and shearing. Initial shearing in a blender broke up cob tissue structure into individual cells and resulted in a gel. Subsequent shearing in a high pressure homogenizer incre...

  9. Inexpensive and Safe DNA Gel Electrophoresis Using Household Materials

    Science.gov (United States)

    Ens, S.; Olson, A. B.; Dudley, C.; Ross, N. D., III; Siddiqi, A. A.; Umoh, K. M.; Schneegurt, M. A.

    2012-01-01

    Gel electrophoresis is the single most important molecular biology technique and it is central to life sciences research, but it is often too expensive for the secondary science classroom or homeschoolers. A simple safe low-cost procedure is described here that uses household materials to construct and run DNA gel electrophoresis. Plastic…

  10. Gel Electrophoresis--The Easy Way for Students

    Science.gov (United States)

    VanRooy, Wilhelmina; Sultana, Khalida

    2010-01-01

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

  11. Separation of Protein Oligomers by Blue Native Gel Electrophoresis

    OpenAIRE

    Braz, Valerie A.; Howard, Kathryn J.

    2009-01-01

    Native gel electrophoresis is used as a tool to assess structural differences in proteins. This note presents an application to separate oligomeric forms of proteins, such as HIV-1 reverse transcriptase monomers and homodimers. Technical difficulties encountered with various native gel techniques and ways to circumvent them are described.

  12. Epoxy-silica hybrids by nonaqueous sol-gel process.

    Czech Academy of Sciences Publication Activity Database

    Ponyrko, Sergii; Kobera, Libor; Brus, Ji?í; Mat?jka, Libor

    2013-01-01

    Ro?. 54, ?. 23 (2013), s. 6271-6282. ISSN 0032-3861 R&D Projects: GA ?R GAP108/12/1459 Grant ostatní: AV ?R(CZ) M200500903 Institutional support: RVO:61389013 Keywords : epoxy- silica hybrid * nonaqueous sol- gel process * gel ation Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.766, year: 2013

  13. Use of chitosan gel for the purification of protein

    Scientific Electronic Library Online (English)

    ZhenXing, Tang; JunQing, Qian.

    2007-03-01

    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%.

  14. Microscopic Picture of Cooperative Processes in Restructuring Gel Networks

    Science.gov (United States)

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

    2013-05-01

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

  15. PC based automated sol-gel pilot plant

    International Nuclear Information System (INIS)

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

  16. Oscillatory and electrohydrodynamic instabilities in flow over a viscoelastic gel

    Indian Academy of Sciences (India)

    R M Thaokar

    2015-05-01

    The stability of oscillatory flows over compliant surfaces is studied analytically and numerically. The type of compliant surfaces studied is the incompressible viscoelastic gel model. The stability is determined using the Floquet analysis, where amplitude of perturbations at time intervals separated by one time period is examined to determine whether perturbations grow or decay. Oscillatory flows pas viscoelastic gels exhibit an instability in the limit of zero Reynolds number, and the transition amplitude of the oscillatory velocity increases with the frequency of oscillations. The transition amplitude has a minimum at a finite wavenumber for the viscoelastic gel model. The instability is found to depend strongly on the gel viscosity $\\eta_{g}$, and the effect of oscillations on the continuation of viscous modes at intermediate Reynolds number shows a complicated dependence on the oscillation frequency. Experimental studies are carried out on the stability of an oscillatory flow past a viscoelastic gel at zero Reynolds number, and these confirm the theoretical predictions.

  17. Keggin-type polyoxometalate-based ionic liquid gels.

    Science.gov (United States)

    Huang, Tianpei; Tian, Naiqin; Wu, Qingyin; Yan, Wenfu

    2015-06-14

    A series of reversible phase transformation ammonium- and phosphonium-based polyoxometalate ionic liquid (POM-IL) gels were synthesized and studied with a focus on the correlation between their physicochemical properties and their chemical structure. The products were successfully characterized by IR, UV, XRD and TG-DTA, and their ionic conductivities were measured. The Keggin-type heteropolyanion clusters decorated with long alkyl chains demonstrated a tendency to exhibit a gel state at room temperature, while all the gels transformed into liquids after heating and then recovered after cooling. With a decrease in the alkyl chain length, a significant improvement in the thermal stability and conductivity of the ammonium-based POM-IL gels can be achieved. Moreover, compared with the corresponding ammonium compound, phosphonium-based POM-IL gel was found to be more stable at high temperature and exhibited better conductivity. PMID:25947074

  18. 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)

  19. Molecular Gels Materials with Self-Assembled Fibrillar Networks

    CERN Document Server

    Weiss, Richard G

    2006-01-01

    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...

  20. Conductivity behaviour of polymer gel electrolytes: Role of polymer

    Indian Academy of Sciences (India)

    S S Sekhon

    2003-04-01

    Polymer is an important constituent of polymer gel electrolytes along with salt and solvent. The salt provides ions for conduction and the solvent helps in the dissolution of the salt and also provides the medium for ion conduction. Although the polymer added provides mechanical stability to the electrolytes yet its effect on the conductivity behaviour of gel electrolytes as well as the interaction of polymer with salt and solvent has not been conclusively established. The conductivity of lithium ion conducting polymer gel electrolytes decreases with the addition of polymer whereas in the case of proton conducting polymer gel electrolytes an increase in conductivity has been observed with polymer addition. This has been explained to be due to the role of polymer in increasing viscosity and carrier concentration in these gel electrolytes.

  1. 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)

  2. Laser CT evaluation on normoxic PAGAT 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 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.

  3. Foam and gel methods for the decontamination of metallic surfaces

    Science.gov (United States)

    Nunez, Luis; Kaminski, Michael Donald

    2007-01-23

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

  4. Viscoelastic nature of Au nanoparticle–PDMS nanocomposite gels

    Indian Academy of Sciences (India)

    Ritu Gupta; Hima K Nagamanasa; Rajesh Ganapathy; Giridhar U Kulkarni

    2015-08-01

    A stable gel of Au nanoparticles in polydimethylsiloxane (PDMS) nanocomposite is prepared by employing the curing agent of PDMS elastomer as a reducing agent for the formation of Au nanoparticles by an in-situ process. The viscoelastic nature of these gels is very sensitive to the Au nanoparticle loading and the synthetic temperature conditions. Even a very low Au content of 0.09 wt% is sufficient enough to bring in the transition from sponge state to gel state at room temperature. Higher synthetic temperature also forms sponge formation. Infrared and ultraviolet–visible spectroscopy measurements have provided insight into PDMS crosslinking and nanoparticle formation, respectively. The optimization of the gel properties can have direct influence on the processability of Au nanoparticle–PDMS nanocomposite gels, with interesting implications in electronic, optical and microfluidic devices.

  5. Photothermally reprogrammable buckling of nanocomposite gel sheets.

    Science.gov (United States)

    Hauser, Adam W; Evans, Arthur A; Na, Jun-Hee; Hayward, Ryan C

    2015-04-27

    Patterning deformation within the plane of thin elastic sheets represents a powerful tool for the definition of complex and stimuli-responsive 3D buckled shapes. Previous experimental methods, however, have focused on sheets that access a limited number of shapes pre-programmed into the sheet, restricting the degree of dynamic control. Here, we demonstrate on-demand reconfigurable buckling of poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM) hydrogel network films containing gold nanoparticles (AuNPs) by patterned photothermal deswelling. Predictable, easily controllable, and reversible transformations from a single flat gel sheet to numerous different three-dimensional forms are shown. Importantly, the response time is limited by poroelastic mass transport, rather than photochemical switching kinetics, enabling reconfiguration of shape on timescales of several seconds, with further increases in speed possible by reducing film thickness. PMID:25752941

  6. Nanostructured GGG powders via gel combustion

    Science.gov (United States)

    Li, Xianxue; Hu, Zhang-Gui; Li, Jiangtao

    2007-03-01

    Polycrystalline nano-sized gadolinium gallium garnet (Gd3Ga5O12, GGG) powders were synthesized via a gel combustion method from a mixed solution of Ga(NO3)3, Gd(NO3)3 and citric acid. The evolution of phase composition and micro-structure of the powders were characterized by X-ray powder diffraction, thermogravimetry/differential thermal analysis and scanning electron microscopy. Well-crystallized, single phase GGG nano-sized powders could be obtained at the calcining temperature as low as 750 °C for 2 h. No any intermediate phases formed during the calcining process. The resulting powders were well dispersed and had a relatively narrow size distribution with an average particle size of approximately 30-50 nm.

  7. Novel macroporous amphoteric gels: Preparation and characterization

    Directory of Open Access Journals (Sweden)

    S. Kudaibergenov

    2012-05-01

    Full Text Available Macroporous amphoteric gels based on allylamine, methacrylic acid and acrylamide crosslinked by N,N'-methylenebisacrylamide were synthesized by radical copolymerization of monomers in cryoconditions. The composition of cryogels was determined by combination of potentiometric and conductimetric titrations. The morphology of cryogels was evaluated by scanning electron microscope (SEM. Cryogels exhibited sponge-like porous structure with pore size ranging from 50 to 200 ?m. The values of the isoelectric points (IEPs determined from the swelling experiments arranged between 3.5 and 4.3. The high adsorption-desorption capacity of amphoteric cryogels with respect to mM and trace concentrations of copper, nickel, and cobalt ions was demonstrated. It was shown that the macroporous amphoteric cryogels are able to adsorb up to 99.9% of copper, nickel, and cobalt ions from 10–3 mol•L–1 aqueous solution.

  8. Polymer gel dosimeter based on itaconic acid.

    Science.gov (United States)

    Mattea, Facundo; Chacón, David; Vedelago, José; Valente, Mauro; Strumia, Miriam C

    2015-11-01

    A new polymeric dosimeter based on itaconic acid and N, N'-methylenebisacrylamide was studied. The preparation method, compositions of monomer and crosslinking agent and the presence of oxygen in the dosimetric system were analyzed. The resulting materials were irradiated with an X-ray tube at 158cGy/min, 226cGymin and 298cGy/min with doses up to 1000Gy. The dosimeters presented a linear response in the dose range 75-1000Gy, sensitivities of 0.037 1/Gyat 298cGy/min and an increase in the sensitivity with lower dose rates. One of the most relevant outcomes in this study was obtaining different monomer to crosslinker inclusion in the formed gel for the dosimeters where oxygen was purged during the preparation method. This effect has not been reported in other typical dosimeters and could be attributed to the large differences in the reactivity among these species. PMID:26275817

  9. Processing hexavalent uranium gels and their properties

    International Nuclear Information System (INIS)

    The properties of xerogels of ammonium polyuranate prepared by various drying procedures were studied. The individual drying procedures affect differently both the chemical structure of the material (its composition) and the physicochemical properties of the final product (specific surface area, porosity). In addition, the physicochemical properties of xerogels depend on the properties of the starting material, i.e., on the type of the initial gel. The physicochemical properties of xerogels, in particular their porosity, are in turn relevant for their subsequent high-temperature processing. The porous structure is essential for thermal treatment. The structure of xerogels obtained by distillation procedures is affected both by the conditions of azeotropic distillation and by the medium employed. By judicious selection of these two variables it is possible to prepare materials with different pore size distributions. (author)

  10. Modelling of erosion of bentonite gel by gel/sol flow

    Energy Technology Data Exchange (ETDEWEB)

    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

    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

  11. 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

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

    OpenAIRE

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

    2001-01-01

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

  13. Clotrimazole nanoparticle gel for mucosal administration

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-01

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

  14. Clotrimazole nanoparticle gel for mucosal administration

    International Nuclear Information System (INIS)

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

  15. A viscosity model of polyacrylamide gel electrophoresis.

    Science.gov (United States)

    Bode, H J

    1979-08-01

    In current theories of polyacrylamide gel electrophoresis, the idea prevails that molecular sieving relies on different accessibility of volume fractions and of cross-sectional area fractions (denoted "pores") to different-sized ions due to the effect of "geometric exclusion". This correlates with the assumption that all elements of a polyacrylamide network occupy fixed and unchangeable positions thus forcing colliding macro-ions to diffuse laterally in order to find an "accessible pore" and to resume motion in direction of the electrical field. However, the alternative conception would be equally well justified, i.e. the assumption that polyacrylamide chains represent smooth obstacles cleared aside under the electrokinetic pressure of a macro-ion. This explanation would even be preferable with respect to the molecular sieving effects occurring in solutions of "liquid polyacrylamide". Yet no theory exists as to describe such effects in quantitative terms. In the present article, a parameter is defined and discussed, which can be estimated by experiment, and which seems to be apt to characterize local resistivity of polymer structures against dislocation and deformation: the "fractional specific resistance". Definition of this parameter is based on the model of a "viscosity-emulsion" composed of two interpenetrating liquid compartments which are characterized by different levels of hydrodynamic friction and the spatial dimensions of which are inferred from Ogston's theory. This concept of "localized viscosity" may also serve as a link between theories of molecular sieving and of "macroscopic viscosity" of flexible polymers. The data of Morris, formerly taken as verifications of the "rigid-pore" concept, are now interpreted in terms of four factors responsible for sizediscrimination: collision frequency, duration of single contacts, size-dependent frictional force, and the extent of cooperation among fibres, due to crosslinking and to simultanous contacts of several fibres to a single macro-ion. Some functions relevant for problems of molecular weight determination by gel electrophoresis are discussed in relation to the suggested model. PMID:158893

  16. Phyllosilicates and Amorphous Gel in the Nakhlites

    Science.gov (United States)

    Hicks, L. J.; Bridges, J. C.; Gurman, S. J.

    2013-09-01

    Previous studies of the nakhlite martian meteorites have revealed hydrothermal minerals present within the fractures of the olivine minerals and the mesostasis. The olivine fractures of the Lafayette nakhlite reveal variations with initial deposits of siderite on the fracture walls, followed by crystalline phyllosilicates (smectite), and finishing with a rapidly cooled amorphous silicate gel within the central regions of the fractures. The mesostasis fractures of Lafayette also contain a crystalline phyllosilicate (serpentine). The amorphous gel is the most abundant secondary phase within the fractures of the other nakhlites [1, 2]. By studying nine nakhlite samples, including Lafayette, Governador Valadares, Nakhla, Y-000593, Y-000749, Miller-Range 03346, NWA 817, NWA 998, and NWA 5790, our aim is to constrain the identity of the phyllosilicate secondary phase minerals found throughout the nakhlite martian meteorites. This is achieved using methods including Electron Probe Micro-analysis (EPMA); X-ray Absorption Near-Edge Structure (Fe-K XANES) spectroscopy measured using Beamline I-18 at the Diamond Light Source synchrotron; and the use of Transmission Electron Microscopy (TEM) at the University of Leicester for High-Resolution (HR) imaging and Selected Area Electron Diffraction (SAED). BF studying nine nakhlite samples, including Lafayette, Governador Valadares, Nakhla, Y-000593, Y-000749, Miller-Range 03346, NWA 817, NWA 998, and NWA 5790, our aim is to constrain the identity of the phyllosilicate secondary phase minerals found throughout the nakhlite martian meteorites. This is achieved using methods including Electron Probe Micro-analysis (EPMA); X-ray Absorption Near-Edge Structure (Fe-K XANES) spectroscopy measured using Beamline I-18 at the Diamond Light Source synchrotron; and the use of Transmission Electron Microscopy (TEM) at the University of Leicester for High-Resolution (HR) imaging and Selected Area Electron Diffraction (SAED).

  17. 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 characteristic tactile length of less than about 5 ?m.

  18. How deeply cells feel: methods for thin gels

    Energy Technology Data Exchange (ETDEWEB)

    Buxboim, Amnon; Brown, Andre' E X [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Rajagopal, Karthikan; Discher, Dennis E [Nano/Bio Interface Center, University of Pennsylvania, Philadelphia, PA 19104 (United States)

    2010-05-19

    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 {approx} 1 kPa). Initial results show that cells increasingly respond to the rigidity of an underlying 'hidden' surface starting at about 10-20 {mu}m gel thickness with a characteristic tactile length of less than about 5 {mu}m.

  19. How deeply cells feel: methods for thin gels

    Science.gov (United States)

    Buxboim, Amnon; Rajagopal, Karthikan; Brown, Andre'E. X.; Discher, Dennis E.

    2010-05-01

    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 µm gel thickness with a characteristic tactile length of less than about 5 µm.

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

    OpenAIRE

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

    2012-01-01

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

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

    OpenAIRE

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

    1997-01-01

    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...

  2. Food gels filled with emulsion droplets : linking large deformation properties to sensory perception

    OpenAIRE

    Sala, G.

    2007-01-01

    Key words: polymer gels, particle gels, emulsion, large deformation, friction, sensory   This thesis reports studies on the large deformation and lubrication properties of emulsion-filled gels and the way these properties are related to the sensory perception of the gels. The design of the studies included polymer and particle gels containing oil droplets of which the interaction with the gel matrix was varied, resulting in droplets either bound or unbound to the matrix. The unique combinatio...

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

    OpenAIRE

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

    2007-01-01

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

  4. Strippable gel for decontamination of contaminated metallic surfaces

    International Nuclear Information System (INIS)

    Periodic decontamination of radioactive laboratories including fume hoods, glove boxes and all surfaces used for handling, processing and transporting radioactive materials is mandatory in all nuclear installations as this reduces spread of contamination and decreases total man rem exposure. Conventionally, chemical decontaminating agents or surfactant solutions are used for this purpose. However, this approach leads to generation of large volume of secondary radioactive waste. The use of strippable gel is an attractive alternative with low secondary waste generation particularly where removal of loose or weakly fixed contamination is necessary and also when the decontaminated material are to be reused, for e.g. decontamination of fume hoods, glove boxes, transport casks, spent fuel storage racks, control rod drive transport containers etc. Literature on gel formulations is scarce and mostly in the patent form. The sustained effort on gel formulation development has resulted in a basic gel formulation. The gel is a highly viscous water-based organic polymer, particularly suitable for application on vertical surfaces including difficult to reach metallic surfaces of complex geometry and not just limited to horizontal surfaces. The gel can be easily applied on contaminated surfaces by brushing or spraying. Curing of the gel is complete within 16-24 hours under ambient conditions and can then be removed by peeling as a dry sheet. While curing, the contaminants are trapped in gel either physically or chemically depending upon the nature of the contaminant. Salient features of cured gel include that it is water soluble and can be disposed off after immobilization in cement. Decontamination performance of the gel was initially evaluated by applying it on SS planchettes contaminated with known amount of radionuclides such as Cs(I), Co(II) and Ce(III). The measured decontamination factor was found to be in the range of 50-500, lowest for Ce(III) and highest for Co(II). Decontamination efficacy of the gel was confirmed by application on SS tray (42 x 81 cm) contaminated with 60Co. The gel could be easily peeled off as a single sheet and average decontamination efficiency of more than 99% was achieved. The amount of spent gel generated from application on the SS tray is about 25 g and can be held within a palm as can be seen in the paper. (author)

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

    Directory of Open Access Journals (Sweden)

    Gabriele Maria Callegaro Serafini

    2012-12-01

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

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

    Scientific Electronic Library Online (English)

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

    2012-12-01

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

  7. Influence of colloidal silicon dioxide on gel strength, robustness, and adhesive properties of diclofenac gel formulation for topical application.

    Science.gov (United States)

    Lu, Zheng; Fassihi, Reza

    2015-06-01

    The objective of this study is to identify the extent of stiffness, adhesiveness, and thixotropic character of a three-dimensional gel network of a 1% diclofenac sodium topical gel formulation in the presence and absence of colloidal silicon dioxide (CSD) and assess its ease of application and adhesiveness using both objective and subjective analysis. The 1% diclofenac gel was mixed with different amounts of CSD (e.g., 0.5, 1, 2, 3, and 5% w/w) and allowed to equilibrate prior to testing. The texture analyzer in combination with a cone-cap assembly was used to objectively investigate the changes in spreadability and adhesiveness of the gel system before and after addition of CSD. Results indicate that an increase in pliability and adhesiveness at levels ?2 to ?5% w/w of CSD dispersed in the gel ensues. For subjective analysis, gels with (2% w/w) CSD and in the absence of CSD were uniformly applied to a 20-cm(2) (5 cm?×?4 cm) surface area on the forearms of healthy volunteers and vehicle preferences by the volunteers regarding ease of application, durability on the skin, compliance, and feelings concerning its textural properties were assessed. It appears that changes in the gel formulation with the addition of CSD enhance gel viscosity and bonding to the skin. Results further show that changes in physical and rheological characteristics of gel containing 2% w/w CSD did not significantly change subject preferences for the gel preparations. These findings may help formulators to have additional options to develop more robust and cost-effective formulations. PMID:25501873

  8. Development of mucoadhesive sprayable gellan gum fluid gels.

    Science.gov (United States)

    Mahdi, Mohammed H; Conway, Barbara R; Smith, Alan M

    2015-07-01

    The nasal mucosa provides a potentially good route for local and systemic drug delivery. However, the protective feature of the nasal cavity make intranasal delivery challenging. The application of mucoadhesive polymers in nasal drug delivery systems enhances the retention of the dosage form in the nasal cavity. Several groups have investigated using low acyl gellan as a drug delivery vehicle but only limited research however, has been performed on high acyl gellan for this purpose, despite its properties being more conducive to mucoadhesion. High acyl gellan produces highly elastic gels below 60°C which make it difficult to spray using a mechanical spray device. Therefore, in this study we have tried to address this problem by making fluid gels by introducing a shear force during gelation of the gellan polymer. These fluid gel systems contain gelled micro-particles suspended in a solution of un-gelled polymer. These systems can therefore behave as pourable viscoelastic fluids. In this study we have investigated the rheological behavior and mucoadhesion of fluid gels of two different types of gellan (high and low acyl) and fluid gels prepared from blends of high and low acyl gellan at a 50:50 ratio. The results demonstrated that by preparing fluid gels of high acyl gellan, the rheological properties were sufficient to spray through a standard nasal spray device. Moreover fluid gels also significantly enhance both high acyl and low acyl gellan mucoadhesion properties. PMID:25863119

  9. Western Blot of Stained Proteins from Dried Polyacrylamide Gels

    Science.gov (United States)

    Gruber, Claudia; Stan-Lotter, Helga

    1996-01-01

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

  10. Probe diffusion in phase-separated bicontinuous biopolymer gels.

    Science.gov (United States)

    Wassén, Sophia; Bordes, Romain; Gebäck, Tobias; Bernin, Diana; Schuster, Erich; Lorén, Niklas; Hermansson, Anne-Marie

    2014-11-01

    Probe diffusion was determined in phase separated bicontinuous gels prepared by acid-induced gelation of the whey protein isolate-gellan gum system. The topological characterization of the phase-separated gel systems is achieved by confocal microscopy and the diffusion measurements are performed using pulsed field gradient (PFG) NMR and fluorescence recovery after photo-bleaching (FRAP). These two techniques gave complementary information about the mass transport at different time- and length scales, PFG NMR provided global diffusion rates in the gel systems, while FRAP enabled the measurements of diffusion in different phases of the phase-separated gels. The results revealed that the phase-separated gel with the largest characteristic wavelength had the fastest diffusion coefficient, while the gel with smaller microstructures had a slower probe diffusion rate. By using the diffusion data obtained by FRAP and the structural data from confocal microscopy, modelling through the lattice-Boltzmann framework was carried out to simulate the global diffusion and verify the validity of the experimental measurements. With this approach it was found that discrepancies between the two experimental techniques can be rationalized in terms of probe distribution between the different phases of the system. The combination of different techniques allowed the determination of diffusion in a phase-separated biopolymer gel and gave a clearer picture of this complex system. We also illustrate the difficulties that can arise if precautions are not taken to understand the system-probe interactions. PMID:25189146

  11. Creating coordination-based cavities in a multiresponsive supramolecular gel.

    Science.gov (United States)

    Wei, Shi-Chao; Pan, Mei; Fan, Yuan-Zhong; Liu, Haoliang; Zhang, Jianyong; Su, Cheng-Yong

    2015-05-11

    Creating cavities in varying levels, from molecular containers to macroscopic materials of porosity, have long been motivated for biomimetic or practical applications. Herein, we report an assembly approach to multiresponsive supramolecular gels by integrating photochromic metal-organic cages as predefined building units into the supramolecular gel skeleton, providing a new approach to create cavities in gels. Formation of discrete O-Pd2 L4 cages is driven by coordination between Pd(2+) and a photochromic dithienylethene bispyridine ligand (O-PyFDTE). In the presence of suitable solvents (DMSO or MeCN/DMSO), the O-Pd2 L4 cage molecules aggregate to form nanoparticles, which are further interconnected through supramolecular interactions to form a three-dimensional (3D) gel matrix to trap a large amount of solvent molecules. Light-induced phase and structural transformations readily occur owing to the reversible photochromic open-ring/closed-ring isomeric conversion of the cage units upon UV/visible light radiation. Furthermore, such Pd2 L4 cage-based gels show multiple reversible gel-solution transitions when thermal-, photo-, or mechanical stimuli are applied. Such supramolecular gels consisting of porous molecules may be developed as a new type of porous materials with different features from porous solids. PMID:25876958

  12. Development of strippable gel for surface decontamination applications

    International Nuclear Information System (INIS)

    Strippable gels are an attractive option for decontamination of surfaces particularly when materials are to be reused after decontamination. The process in general results in good decontamination performance with minimal secondary waste generation. This paper reports on development of strippable gel formulation using polyvinyl alcohol as the gel former. Peeling behavior of the gel film improved when glycerol was used as plasticizer. Incorporation of decontaminating agents is essential for the gel to be effective, so a number of decontaminating agents were screened based on their miscibility with the gel, smooth peeling, and good decontamination performance. Based on this study, a strippable gel, ‘INDIGEL’ was formulated as a potential candidate for surface decontamination applications. Extensive trials on evaluation of decontamination performance of Indigel were done on simulated surfaces like stainless steel tray, stainless steel fume hood, PVC floor, granite and ceramic table tops. Results show that Indigel is highly effective for decontamination of surfaces contaminated with all types of radionuclides. Simplicity of its use coupled with good decontamination ability will find application in nuclear and other chemical industries. (author)

  13. Two-dimensional gel electrophoresis: vertical isoelectric focusing.

    Science.gov (United States)

    Dorri, Yaser

    2012-01-01

    Two-dimensional gel electrophoresis (2-DE) is one of the most powerful tools for separating proteins based on their size and charge. 2-DE is very useful to separate two proteins with identical molecular weights but different charges, which cannot be achieved with just sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Here, a simpler and easier version of 2-DE is presented which is also faster than all the currently available techniques. In this modified version of 2-DE, isoelectric focusing is carried out in the first dimension using a vertical SDS-PAGE apparatus. Following the first-dimensional IEF, each individual lane is excised from the IEF gel and, after a 90° rotation, is inserted into a second-dimensional SDS-PAGE, which can be stained with Coomassie Brilliant Blue for protein analysis or immunoblotted for further analysis. This version of IEF can be run in less than 2 h compared to the overnight run required by O'Farrell's method. Difficult tube gel casting and gel extrusion as well as tube gel distortion are eliminated in our method. This method is simpler, faster, and inexpensive. Both dimensions can be done on the same SDS-PAGE apparatus, and up to ten samples can be run simultaneously using one gel. PMID:22585490

  14. Implementation of MRI gel dosimetry in radiation therapy

    International Nuclear Information System (INIS)

    Gel dosimetry was used together with magnetic resonance imaging (MRI) to measure three-dimensional absorbed dose distributions in radiation therapy. Two different dosimeters were studied: ferrous- and monomer gel, based on the principles of radiation-induced oxidation and polymerisation, respectively. Single clinical electron and photon beams were evaluated and gel dose distributions were mainly within 2% of conventional detector results. The ferrous-gel was also used for clinical proton beams. A decrease in signal per absorbed dose was found close to the end of the range of the protons (15-20%). This effect was explained as a linear energy transfer dependence, further supported with Monte Carlo simulations. A method for analysing and comparing data from treatment planning system (TPS) and gel measurements was developed. The method enables a new pixel by pixel evaluation, isodose comparison and dose volume histogram verification. Two standard clinical radiation therapy procedures were examined using the developed TPS verification method. The treatment regimes included several beams of different radiation qualities. The TPS calculated data were in very good agreement with the dose distribution measured by the ferrous-gel. However, in a beam abutment region, larger dose difference was found. Beam adjustment errors and a minor TPS underestimation of the lateral scatter contribution outside the primary electron beam may explain the discrepancy. The overall uncertainty in the ferrous-gel dose determination was considerably reduced using an optimised MRI acquisition protocol and a new MRI scanner. The relative dose uncertainty was found to be better than 3.3% for all dose levels (95% confidence level). Using the method developed for comparing measured gel data with calculated treatment plans, the gel dosimetry method was proven to be a useful tool for radiation treatment planning verification

  15. Implementation of MRI gel dosimetry in radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Baeck, S.Aa.J

    1998-12-01

    Gel dosimetry was used together with magnetic resonance imaging (MRI) to measure three-dimensional absorbed dose distributions in radiation therapy. Two different dosimeters were studied: ferrous- and monomer gel, based on the principles of radiation-induced oxidation and polymerisation, respectively. Single clinical electron and photon beams were evaluated and gel dose distributions were mainly within 2% of conventional detector results. The ferrous-gel was also used for clinical proton beams. A decrease in signal per absorbed dose was found close to the end of the range of the protons (15-20%). This effect was explained as a linear energy transfer dependence, further supported with Monte Carlo simulations. A method for analysing and comparing data from treatment planning system (TPS) and gel measurements was developed. The method enables a new pixel by pixel evaluation, isodose comparison and dose volume histogram verification. Two standard clinical radiation therapy procedures were examined using the developed TPS verification method. The treatment regimes included several beams of different radiation qualities. The TPS calculated data were in very good agreement with the dose distribution measured by the ferrous-gel. However, in a beam abutment region, larger dose difference was found. Beam adjustment errors and a minor TPS underestimation of the lateral scatter contribution outside the primary electron beam may explain the discrepancy. The overall uncertainty in the ferrous-gel dose determination was considerably reduced using an optimised MRI acquisition protocol and a new MRI scanner. The relative dose uncertainty was found to be better than 3.3% for all dose levels (95% confidence level). Using the method developed for comparing measured gel data with calculated treatment plans, the gel dosimetry method was proven to be a useful tool for radiation treatment planning verification 103 refs, 20 figs, 6 tabs

  16. Structures of high strength polymer gels revealed by small-angle neutron scattering

    International Nuclear Information System (INIS)

    Various types of tough polymer gels capable of high recoverable deformability and/or with high shear/compressive moduli are investigated by small-angle neutron scattering (SANS) and mechanical measurements. These gels have unique structures, such as sliding cross-links (slide-ring gels), plane cross-links by clay platelets (nanocomposite gels; NC gels), and tetrahedral networks (tetra-PEG gels). One of the common features of these gels is that frozen inhomogeneities inherent in polymer gels are negligible. This fact, observed by SANS measurements, indicates that cross-links are introduced very effectively. Hence, the mechanical properties of these gels are expected to be well predicted by the theories of rubber elasticity. In this review, we discuss the relationship between the structure and mechanical properties of tough polymer gels. Furthermore, we address the necessary conditions for high-performance polymer gels in the analogy of rubber. (author)

  17. Structural investigation of supertough polymer gels by small-angle neutron scattering measurement

    International Nuclear Information System (INIS)

    Various types of supertough polymer gels capable of high recoverable deformability and/or with high shear/compressive moduli are investigated by small-angle neutron scattering (SANS) and mechanical measurements. These gels have unique structures, such as sliding cross-links (slide-ring gels), plane cross-links by clay platelets (nanocomposite gels; NC gels), and tetrahedral networks (tetra-PEG gels). One of the common features of these gels is that frozen inhomogeneities inherent to polymer gels are negligible. This fact, observed by SANS measurements, indicates that cross-links are introduced very effectively. Hence, the mechanical properties of these gels are expected to be well predicted by the theories of rubber elasticity. In this review, we discuss the relationship between the structure and mechanical properties of supertough polymer gels. Furthermore, we address the necessary conditions for high-performance polymer gels in the analogy of rubber. (author)

  18. Structural Investigation of Supertough Polymer Gels by Small-Angle Neutron Scattering Measurement

    Science.gov (United States)

    Shibayama, Mitsuhiro

    2009-04-01

    Various types of supertough polymer gels capable of high recoverable deformability and/or with high shear/compressive moduli are investigated by small-angle neutron scattering (SANS) and mechanical measurements. These gels have unique structures, such as sliding cross-links (slide-ring gels), plane cross-links by clay platelets (nanocomposite gels; NC gels), and tetrahedral networks (tetra-PEG gels). One of the common features of these gels is that frozen inhomogeneities inherent to polymer gels are negligible. This fact, observed by SANS measurements, indicates that cross-links are introduced very effectively. Hence, the mechanical properties of these gels are expected to be well predicted by the theories of rubber elasticity. In this review, we discuss the relationship between the structure and mechanical properties of supertough polymer gels. Furthermore, we address the necessary conditions for high-performance polymer gels in the analogy of rubber.

  19. Sol-gel-state of hydrated zirconium dioxide

    International Nuclear Information System (INIS)

    The change in viscosity and density of a system in the course of sol-gel-xerogel has been traced. The size and molecular mass of particles in sol have been determined. Initial sol is practically a monodisperse system. Gel is a spatial net of similar particles. Reversible character of sol-gel transition with a change in water content in the system suggests instability of the bond between the particles in the structure of the solid state body formed. 11 refs.; 4 figs

  20. Sol-gel processing with inorganic metal salt precursors

    Science.gov (United States)

    Hu, Zhong-Cheng

    2004-10-19

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

  1. Interaktion mellem warfarin og oral miconazol-gel

    DEFF Research Database (Denmark)

    Ogard, C G; Vestergaard, Henrik

    2000-01-01

    We report a case of a 76 year-old woman who had been taking warfarin for seven years because of relapsing deep venous thrombosis. Her daily maintenance dose was 5 mg. Monthly measurements of international normalised ratio (INR) were stable between 2-3. She developed oral candidiasis and miconazole gel was prescribed. One week later she developed bleeding gums. Eight days later she was admitted to the hospital with haematuria. INR was > 10. Warfarin and the miconazole gel were withdrawn. She was treated with phytonadione. INR normalised after four days and she continued warfarin treatment. Caution should be exercised whenever the combination of warfarin and miconazole gel are prescribed.

  2. COMPARATIVE STUDIES ON POVIDONE-IODINE OINTMENT AND GEL

    Directory of Open Access Journals (Sweden)

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

    2012-11-01

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

  3. Structural investigations of sol-gel glasses using optical probes

    OpenAIRE

    Ennis, Gerard Joseph

    1992-01-01

    The optical spectroscopy of the europium ion has been used as a probe of the structural changes occurring as a function of processing temperature in sol-gel derived glasses. The fluorescence and fluorescence decay times of the EuJ' ion were observed and changes in the emission spectra and decay measurements were interpreted in terms of the changes taking place within the sol-gel matrix. Measurements of the fluorescence decay time indicate abnormally short lifetime measurements for sol-gel der...

  4. Improving gel properties of hairtail surimi by electron irradiation

    Science.gov (United States)

    Lin, Xianping; Yang, Wenge; Xu, Dalun; Jie, Zhen; Liu, Wen

    2015-05-01

    Hairtail surimi was subjected to electron irradiation for doses up to 9 kGy. At 7 kGy highest gel strength was achieved. The irradiation also increased lightness and expressible water amount. Scanning electron micrographs showed that 7 kGy irradiation made the surimi protein gel network more compact. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the degradation of myosin heavy chain (MHC) as the irradiation dose increased, particularly at the 7 and 9 kGy doses. Radiation processing may become a new effective tool in surimi production.

  5. Electron beam sterilization of the agarose gel used for electrophoresis

    International Nuclear Information System (INIS)

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

  6. Observation of Individual DNA Molecules Undergoing Gel Electrophoresis

    Science.gov (United States)

    Smith, Steven B.; Aldridge, Paul K.; Callis, James B.

    1989-01-01

    Individual DNA molecules undergoing agarose gel electrophoresis were viewed with the aid of a fluorescence microscope. Molecular shape and orientation were studied in both steady and pulsed electric fields. It was observed that (i) DNA macromolecules advanced lengthwise through the gel in an extended configuration, (ii) the molecules alternately contracted and lengthened as they moved, (iii) the molecules often became hooked around obstacles in a U-shape for extended periods, and (iv) the molecules displayed elasticity as they extended from both ends at once. A computer model has been developed that simulates the migration of the molecules in a rotating-field gel electrophoresis experiment.

  7. Helicoidal precipitation patterns in silica and agarose gels

    Science.gov (United States)

    Thomas, Shibi; Varghese, George; Bárdfalvy, Dóra; Lagzi, István; Rácz, Zoltán

    2014-04-01

    Helicoidal patterns grown in agarose and silica gels were studied using reaction-diffusion-precipitation processes with components CuCl2/K2CrO4. We measured the probability PH of the emergence of helicoids as the internal surface area of the gels was varied by changing the concentration for agarose and by modifying pH for silica. In addition, the effects of mixing the two gels were also investigated. Our main result is that the surface area effects parallel the effects of noise, namely increasing the surface area initially enhances the formation of helicoids but further increase leads to downturn in PH due to proliferation of random patterns.

  8. Blinking suppression of single quantum dots in agarose gel

    International Nuclear Information System (INIS)

    Fluorescence blinking is commonly observed in single molecule/particle spectroscopy, but it is an undesirable feature in many applications. We demonstrated that single CdSe/ZnS quantum dots in agarose gel exhibited suppressed blinking behavior. In addition, the long-time exponential bending tail of the power-law blinking statistics was found to be influenced by agarose gel concentration. We suggest that electron transfer from the light state to the dark state might be blocked due to electrostatic surrounding of gel with inherent negatively charged fibers.

  9. Drying and shrinkage of polymer gels

    Scientific Electronic Library Online (English)

    S. S., Waje; M. W., Meshram; V., Chaudhary; R., Pandey; P. A., Mahanawar; B. N., Thorat.

    2005-06-01

    Full Text Available The polymer hydrogel was synthesized by photo-polymerization process (UV light, 60 ºC) in presence of Photo-initiator (IrgacureR) and Cross-linker (NN'-methylene bisacrylamide; MBAM). In the present work, the drying of polymer hydrogel was carried out to study the effect of temperature, gel-sheet th [...] ickness, monomer ratio of acryl acid to acrylamide (AA/AM), concentration of MBAM and quantity of monomers. A correlation has been developed for modified sheet thickness as a function of contraction coefficient and degree of drying. Effective diffusivity was estimated from Fickian-diffusive model considering modified sheet thickness and was found to be in the range of 1.1 ´ 10-10-5.93 ´ 10-10 m²/s. The activation energy obtained using Arrhenius type equation was found to be in the range of 2979-10737 kJ/kmol H2O. The drying behavior shows an initial shoot-up in drying rate followed by constant rate and two falling rate periods.

  10. Drying and shrinkage of polymer gels

    Directory of Open Access Journals (Sweden)

    S. S. Waje

    2005-06-01

    Full Text Available The polymer hydrogel was synthesized by photo-polymerization process (UV light, 60 ºC in presence of Photo-initiator (IrgacureR and Cross-linker (NN'-methylene bisacrylamide; MBAM. In the present work, the drying of polymer hydrogel was carried out to study the effect of temperature, gel-sheet thickness, monomer ratio of acryl acid to acrylamide (AA/AM, concentration of MBAM and quantity of monomers. A correlation has been developed for modified sheet thickness as a function of contraction coefficient and degree of drying. Effective diffusivity was estimated from Fickian-diffusive model considering modified sheet thickness and was found to be in the range of 1.1 ´ 10-10-5.93 ´ 10-10 m²/s. The activation energy obtained using Arrhenius type equation was found to be in the range of 2979-10737 kJ/kmol H2O. The drying behavior shows an initial shoot-up in drying rate followed by constant rate and two falling rate periods.

  11. Effect of superparamagnetic particles in agarose gels

    International Nuclear Information System (INIS)

    The effect of different preparations of superparamagnetic particles, designed as potential MR contrast media for the gastrointestinal tract (oral magnetic particles, OMP, diameter of 3.5 ?m, iron content 20% by weight) and for the reticuloendothelial system (intravenous magnetic particles, IMP, mean diameter of 0.3 ?m, iron content 30% by weight), were evaluated in agarose gels in vitro, using a 0.5 T whole body MR system. The iron content ranged from 2.1x 104 to 2.1x101 mg Fe/ml in both preparations. Both preparations reduced the signal intensities substantially over a range of concentrations in spin echo sequences. Generally, the signal intensity decreased monotonously with concentration, except for IMP at low concentrations, at which a minor signal intensity increase was observed on T1 and proton density weighted images. The reduction of the signal intensity was stronger in gradient echo and phase contrast sequences, as compared to corresponding spin echo sequences with similar timing. Both IMP and OMP had a pronounced T2 effect, the effect of IMP being stronger than that of OMP. IMP had a relatively smaller T1 effect, whereas T1 was almost unaffected by OMP. Susceptibility artifacts occurred at higher concentrations of both OMP and IMP, in all sequences used. Thus, OMP reduced the signal intensity, without causing significant artifacts, on both T1 and T2 weighted images over a relatively wide range of concentrations. (orig.)

  12. Laser microbeam CT scanning of dosimetry gels

    Science.gov (United States)

    Maryanski, Marek J.; Ranade, Manisha K.

    2001-06-01

    A novel design of an optical tomographic scanner is described that can be used for 3D mapping of optical attenuation coefficient within translucent cylindrical objects with spatial resolution on the order of 100 microns. Our scanner design utilizes the cylindrical geometry of the imaged object to obtain the desired paths of the scanning light rays. A rotating mirror and a photodetector are placed at two opposite foci of the translucent cylinder that acts as a cylindrical lens. A He-Ne laser beam passes first through a focusing lens and then is reflected by the rotating mirror, so as to scan the interior of the cylinder with focused and parallel paraxial rays that are subsequently collected by the photodetector to produce the projection data, as the cylinder rotates in small angle increments between projections. Filtered backprojection is then used to reconstruct planar distributions of optical attenuation coefficient in the cylinder. Multiplanar scans are used to obtain a complete 3D tomographic reconstruction. Among other applications, the scanner can be used in radiation therapy dosimetry and quality assurance for mapping 3D radiation dose distributions in various types of tissue-equivalent gel phantoms that change their optical attenuation coefficients in proportion to the absorbed radiation dose.

  13. Casting AISI 316 steel by gel cast

    International Nuclear Information System (INIS)

    The feasibility of producing AISI 316 steel components from their powders and avoiding their compaction is analyzed. A casting technique is tested that is similar to gel casting, used for ceramic materials. In the initial stage, the process consists of the formulation of a concentrated barbotine of powdered metal in a solution of water soluble organic monomers, which is cast in a mold and polymerized in situ to form a raw piece in the shape of the cavity. The process can be performed under controlled conditions using barbotines with a high monomer content from the acrylimide family. Then, the molded piece is slowly heated until the polymer is eliminated, and it is sintered at temperatures of 1160oC to 1300oC under a dry hydrogen atmosphere, until the desired densities are attained. The density and micro structure of the materials obtained are compared with those for the materials compacted and synthesized by the conventional processes. The preliminary results show the feasibility of the process for the production of certain kinds of structural components (CW)

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

    OpenAIRE

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

    2012-01-01

    This study assessed acceptability of the candidate microbicide VivaGel® and two placebo gels among 61 sexually active young US and Puerto Rican women at three sites. Participants were randomly assigned to use one of the gels twice per day for 14 days. At trial completion, 59% of the women in the VivaGel® group reported being likely to use the gel in the future, whereas 23% were unlikely to use it and 18% were undecided. Participants reported problems with all three gels, including the “univer...

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

    Czech Academy of Sciences Publication Activity Database

    Rubešová, K.; Hlásek, T.; Jakeš, V.; Sedmidubský, D.; Hejtmánek, Ji?í

    2012-01-01

    Ro?. 30, ?. 1 (2012), 1-5. ISSN 1757-8981. [Fall Meeting of the European-Materials-Research-Society (E-MRS)/Symposium K - Solution-Derived Electronic-Oxide Films, Nanostructures and Patterning, from Materials to Devices. Warsaw, 19.09.2011-23.09.2011] R&D Projects: GA ?R GA203/09/1036 Institutional research plan: CEZ:AV0Z10100521 Keywords : BiSrCoO * thermoelectrics * sol–gel Subject RIV: BM - Solid Matter Physics ; Magnetism

  16. Inhibition of collagenase and metalloproteinases by aloins and aloe gel.

    Science.gov (United States)

    Barrantes, Esther; Guinea, María

    2003-01-01

    The effects of Aloe barbadensis gel and aloe gel constituents on the activity of microbial and human metalloproteinases have been investigated. Clostridium histolyticum collagenase (ChC) results dose-dependently inhibited by aloe gel and the activity-guided fractionation led to an active fraction enriched in phenolics and aloins. Aloins have been shown to be able to bind and to inhibit ChC reversibly and non-competitively. Aloe gel and aloins are also effective inhibitors of stimulated granulocyte matrix metalloproteinases (MMPs). The remarkable structural resemblances between aloins and the pharmacophore structure of inhibitory tetracyclines, suggest that the inhibitory effects of aloins are via an interaction between the carbonyl group at C(9) and an adjacent hydroxyl group of anthrone (C(1) or C(8)) at the secondary binding site of enzyme, destabilizing the structure of granulocyte MMPs. PMID:12479983

  17. Reproducibility study of normoxic polyacrylamide gel (nPAG) dosimeters

    International Nuclear Information System (INIS)

    In this study, the overall accuracy of normoxic polyacrylamide gel (nPAG) dosimeters is considered. Different badges of nPAG are fabricated, poured in containers of glass and Barex and irradiated with a 6MV square photon beam. The polymer gel dosimeters were read out using MRI. The overall reproducibility and accuracy of nPAG gel dosimeters was determined by comparison with depth-dose profiles acquired with a Pin Point ionization chamber. Additionally, the effect of the container wall on the depth-dose profile and the effect of temperature changes before and after irradiation on the R2-dose response have been investigated. The average standard deviation and maximum deviation between 8 gel-measured depth-dose profiles and a depth-dose profile measured with an ionization chamber amounted to 0.543 Gy (2.5%) and 2.579 Gy (11.7%) respectively.

  18. Sol-gel optical coatings for lasers: Part 1

    International Nuclear Information System (INIS)

    Many manufacturers and users claim that optical coatings are best prepared by physical vapor deposition technology. Others believe that sol-gel technology is an effective and competitive alternative. This article, the first of three, emphasizes sol-gel thin-film history and relates it to high-power laser technology, chemistry of the sol-gel process, production of optical coatings and deposition techniques. The second and third articles describe the preparation and performance of antireflective and highly reflective sol-gel optical coatings, respectively, that have been developed for the 1.8-MJ/500-TW (351-nm) pulsed neodymium-glass laser. This powerful laser is to be used in France's Inertial Confinement Fusion (ICF) program. It will demonstrate, at the laboratory scale, ignition of deuterium-tritium fusion fuel

  19. Electrochemical mechanism of ion current rectification of polyelectrolyte gel diodes

    Science.gov (United States)

    Yamamoto, Tetsuya; Doi, Masao

    2014-06-01

    Polyelectrolyte gel diodes that are double layers of two oppositely charged polyelectrolyte gels, sandwiched by two symmetric electrodes, are emergent ionic devices. These diodes are designed to rectify ion currents with a physical mechanism that is analogous to conventional semiconductor diodes—the asymmetry in the permeability of ions across the interfaces between the two oppositely charged gels. Here we show that polyelectrolyte gel diodes indeed rectify steady currents with a physical mechanism that is very different from conventional diodes by using a simple electrochemical model; electric currents are limited by electrochemical reactions that are driven by potential drops at electrodes and these potential drops markedly change with changing the direction of applied voltages due to the redistribution of non-reactive counterions, leading to rectified ion currents. This concept is relatively generic and thus may provide insight in the physics of analogous ionic and biomimetic systems that show electrochemical reactions.

  20. Sol-gel processing for conventional and alternative energy

    CERN Document Server

    2012-01-01

    This book offers comprehensive information on the use of sol-gel processing in materials in energy systems, conversion, storage, and generation. The book focuses on processing, and covers related topics such as carbon sequestration, clean energy, and biofuels.

  1. Preparation and evaluation of soft gellan gum gel containing paracetamol

    Directory of Open Access Journals (Sweden)

    Gohel M

    2009-01-01

    Full Text Available The objective of this study was to develop soft paracetamol gel using gellan gum as a gelling agent and sodium citrate as a source of cation. Different batches were prepared using three different concentrations of gellan gum (0.1, 0.3, and 0.5%, each with two different sodium citrate concentrations (0.3 and 0.5%. The consistency of the paracetamol gel was dependent on the concentration of gellan gum, sodium citrate and co-solute. The results of dissolution study of soft gel containing 0.3% gellan gum and 0.3% sodium citrate revealed that paracetamol was completely released in 30 min. Polyethylene glycol 400 worked as a solubilizer for paracetamol. All the gels possessed acceptable sensory characteristics when evaluated by human volunteers. Short term stability study carried out for four weeks at different temperatures revealed no considerable changes in performance characteristics of developed optimized formulation.

  2. Formulation and in-vitro evaluation of chrysophanol topical gel

    Directory of Open Access Journals (Sweden)

    Deepa T Vasudevan

    2011-01-01

    Full Text Available This study describes the formulation and characterization of topical gel of chrysophanol containing carbopol as gel base. The partition of drug between skin and the hydrogel matrix was considered to play an important role in the permeation process. The effect of three levels of carbopol and three different permeation enhancers on chrysophanol permeability was determined in vitro. Each formulation was characterized in terms of viscosity, pH, extrudability, spreadability, homogenicity, drug content, skin irritation, stability, and drug release studies. The gel consisting of 1% carbopol as gel base and 15% dimethylsulfoxide showed superior physicochemical and permeability properties and it was ranked best. Reports of pharmacokinetic parameters showed that the drug release is controlled by both diffusion and relaxation processes.

  3. Dehydration and crystallization kinetics of zirconia-yttria gels

    International Nuclear Information System (INIS)

    Zirconia and zirconia-yttria gels containing 4 and 8 mol% yttria were obtained by coprecipitation and drying at 373 K. The dehydration and crystallization behavior of the dried gels was studied by DSC, TG, and XRD. The gels undergo elimination of water over a wide temperature range of 373--673 K. The peak temperature of the endotherm corresponding to dehydration and the kinetic constants for the process were not influenced by the yttria content of the gel. The enthalpy of dehydration observed was in good agreement with the heat of vaporization data. The dehydration was followed by a sharp exothermic crystallization process. The peak temperature of the exotherm and the activation energy of the process increased with an increase in yttria content, while the enthalpy of crystallization showed a decrease. The ''glow effect'' reduced with increasing yttria content. Pure zirconia crystallizes in the tetragonal form while the zirconia containing 4 and 8 mol% yttria appears to crystallize in the cubic form

  4. formulation and evaluation of topical gel of aceclofenac

    Directory of Open Access Journals (Sweden)

    tarun kumar guleri

    2013-11-01

    Full Text Available 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 cellophane membrane with phosphate buffer pH 7.4 as the receptor medium. The release rate of the gel was found to obey Higuchi model. The percentage of drug release follow following order Poloxamer-407> HPMC> Carbopol-940>Carbopol-934.

  5. Investigations of rheological properties of diclofenac sodium gel preparation

    Directory of Open Access Journals (Sweden)

    Firuza Maksudova

    2013-04-01

    Full Text Available It is well-known that the majority of non-steroidal anti-inflammatory drugs (NSAIDs are ulcerogenic. Gel or ointment preparations of NSAIDs are free from this side-effect, which is a prerequisite for the increase of aforementioned forms of NSAIDs. A major quality indicator of gels and ointments are rheological properties. Along with determining the quality of preparation, they influence manufacturing, expiration date and terms of storage. This article demonstrates the results of investigation of rheological indices of 3% gel preparation of diclofenac sodium such as plasticity, structural viscosity, and thixotropy. Obtained results confirm that the developed gel preparation has thixotropy, plasticity and is classified as a Bingham system.

  6. Thermally reversible gels in electrophoresis. I - Matrix characterization

    Science.gov (United States)

    Righetti, Pier Giorgio; Snyder, Robert S.

    1988-01-01

    Two series of thermally reversible hydrogen-bonded gels have been characterized: (5 pct) PVA-(4 pct) PEG and (5 pct) PVA-(0.04 pct) borate gels. They both have extremely low melting points (16-17 C) and could be of potential interest for recovery of proteins after preparative electrophoresis. The PVA-borate gels can be exploited in the pH range 7-11 by progressively increasing the borate content in the pH interval 8 to 7 and concomitantly decreasing the borate levels in the pH zone 8 to 11. It is hypothesized that the low melting point of these gels is due to the fact that they are sparingly and sparsely hydrogen bonded along the PVA chain: on the average, 1 OH group out of 3 or 4 OH groups in the PVA polymer should be engaged in H-bond formation.

  7. Using Gel Electrophoresis To Illustrate Protein Diversity and Isoelectric Point.

    Science.gov (United States)

    Browning, Mark; Vanable, Joseph

    2002-01-01

    Demonstrates the differences in protein structures by focusing on isoelectric point with an experiment that is observable under certain pH levels in gel electrophoresis. Explains the electrophoresis procedure and reports results of the experiments. (YDS)

  8. Creep and Fracture of a Protein Gel under Stress

    Science.gov (United States)

    Leocmach, Mathieu; Perge, Christophe; Divoux, Thibaut; Manneville, Sébastien

    2014-07-01

    Biomaterials such as protein or polysaccharide gels are known to behave qualitatively as soft solids and to rupture under an external load. Combining optical and ultrasonic imaging to shear rheology we show that the failure scenario of a protein gel is reminiscent of brittle solids: after a primary creep regime characterized by a power-law behavior whose exponent is fully accounted for by linear viscoelasticity, fractures nucleate and grow logarithmically perpendicularly to shear, up to the sudden rupture of the gel. A single equation accounting for those two successive processes nicely captures the full rheological response. The failure time follows a decreasing power law with the applied shear stress, similar to the Basquin law of fatigue for solids. These results are in excellent agreement with recent fiber-bundle models that include damage accumulation on elastic fibers and exemplify protein gels as model, brittlelike soft solids.

  9. Composition and applications of Aloe vera leaf gel.

    Science.gov (United States)

    Hamman, Josias H

    2008-01-01

    Many of the health benefits associated with Aloe vera have been attributed to the polysaccharides contained in the gel of the leaves. These biological activities include promotion of wound healing, antifungal activity, hypoglycemic or antidiabetic effects antiinflammatory, anticancer, immunomodulatory and gastroprotective properties. While the known biological activities of A. vera will be briefly discussed, it is the aim of this review to further highlight recently discovered effects and applications of the leaf gel. These effects include the potential of whole leaf or inner fillet gel liquid preparations of A. vera to enhance the intestinal absorption and bioavailability of co-administered compounds as well as enhancement of skin permeation. In addition, important pharmaceutical applications such as the use of the dried A. vera gel powder as an excipient in sustained release pharmaceutical dosage forms will be outlined. PMID:18794775

  10. Composition and Applications of Aloe vera Leaf Gel

    Directory of Open Access Journals (Sweden)

    Josias H. Hamman

    2008-08-01

    Full Text Available Many of the health benefits associated with Aloe vera have been attributed to the polysaccharides contained in the gel of the leaves. These biological activities include promotion of wound healing, antifungal activity, hypoglycemic or antidiabetic effects antiinflammatory, anticancer, immunomodulatory and gastroprotective properties. While the known biological activities of A. vera will be briefly discussed, it is the aim of this review to further highlight recently discovered effects and applications of the leaf gel. These effects include the potential of whole leaf or inner fillet gel liquid preparations of A. vera to enhance the intestinal absorption and bioavailability of co-administered compounds as well as enhancement of skin permeation. In addition, important pharmaceutical applications such as the use of the dried A. vera gel powder as an excipient in sustained release pharmaceutical dosage forms will be outlined.

  11. Studies on supramolecular gel formation using DOSY NMR.

    Czech Academy of Sciences Publication Activity Database

    Nonappa, N.; Šaman, David; Kolehmainen, E.

    2015-01-01

    Ro?. 53, ?. 4 (2015), s. 256-260. ISSN 0749-1581 Institutional support: RVO:61388963 Keywords : DOSY * VT NMR * gel * diffusion coefficients Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.179, year: 2014

  12. Potentiometric estimation of ionic mobilities in PMMA gel electrolytes.

    Czech Academy of Sciences Publication Activity Database

    Sedla?íková, M.; Vondrák, Ji?í; Reiter, Jakub; Velická, Jana; Jirák, T.

    Banff : USEB, 2007, s. 4. ISBN N. [International Society of Electrochemistry /58./. Banff (CA), 09.09.2007-14.09.2007] Institutional research plan: CEZ:AV0Z40320502 Keywords : gel electrolytes Subject RIV: CA - Inorganic Chemistry

  13. Complement monitoring of Pluronic 127 gel and micelles

    DEFF Research Database (Denmark)

    Hamad, Islam; Hunter, A Christy; Moghimi, Seyed Moien

    2013-01-01

    Poloxamer 407 is a non-ionic polyethylene oxide (PEO)/polypropylene oxide (PPO) block copolymer, which exhibits reversible thermogelation properties. Poloxamer gel has attracted many applications for controlled release of therapeutic agents as well as in surgical interventions such as controlled vascular occlusion. We show that poloxamer gel can trigger the complement system, which is an integral part of innate immunity and its inadvertent activation can induce clinically significant anaphylaxis...

  14. Washing liquid effect on surimi gel rheological properties

    Directory of Open Access Journals (Sweden)

    Vinnov Alexey Sergeevich

    2013-04-01

    Full Text Available The purpose of this research was to compare the rheological properties of the modori and su-wari gels, obtained from minced carp washed with water and electro-activated by water systems. The results of comparative analysis of rheological properties of suwari and modori gels from minced carp, washed with tap water, catholyte and anolyte are presented. Effective viscosity in all cases is reversibly reduced with increasing shear rate and is stabilized for all considered soft gel samples at strain rate of 15–20 s-1. The effective viscosity maximum at small shear stress is ob-served for suwari from minced carp washed with catholyte with sodium chloride addition. This gel type is capable for effective viscosity intense reduction, under external mechanical effect. Under the sodium chloride influence, destruction intensity of gel structure for minced meat, washed with water, increases by 4,5 times, and for suwari from minced meat, washed by electroactivated sys-tems, this value is changing only by 1,4–0,73 times. The flow final segment analysis shows that the crystalline sodium chloride addition reduces the destruction intensity of suwari structure washed with water by 2, and with anolyte – by 4. The suvari and madory gels statistical critical shear stress values comparative research showed, that catholyte washed minced carp provide the largest values, taking into account moisture content in the product. The plastic flow of the soft gels from minced meat, washed by electro-activated systems begins at 1 700 Pa and it exceeds the yield strength of suwari washed with water almost twice. It is clear, that catholyte and anolyte application for obtaining washed carp minced meat provides obtaining suwari and modori gels with higher rheological properties than if it is washed with water.

  15. Optical materials by a modified sol-gel nanoparticle process

    OpenAIRE

    Schmidt, Helmut K.; Mennig, Martin

    2000-01-01

    The use of sol-gel derived nanoparticles leads to interesting new materials and systems for optics. The basic principle, to combine transparent matrices with nanoparticles in sizes below remarkable scattering losses opens up new material technologies. The processing is almost as simple as sol-gel processing, and the use of polymerizable nanoparticle even leads to high performance coatings by using simple polymer techniques.

  16. Chemistry of material preparation by the sol-gel process

    OpenAIRE

    Schmidt, Helmut K.

    1988-01-01

    A survey over the role of chemistry in sol-gel processing is given. The basic chemistry of the sol-gel process is complex due to the different reactivities of the network forming and the network modifying components and the wide variety of reaction parameters. Despite the important progress in the investigations of the mechanisms of hydrolysis and condensation, a direct relation of reaction parameters to material properties is still very difficult.

  17. DNA Gel Particles: Particle Preparation and Release Characteristics

    OpenAIRE

    Morán, M. Carmen; Miguel, M. Graça; Lindman, Björn, 1942-

    2007-01-01

    Aqueous mixtures of oppositely charged polyelectrolytes undergo associative phase separation, resulting in coacervation, gelation, or precipitation. This phenomenon has been exploited here to form DNA gel particles by interfacial diffusion. We report the formation of DNA gel particles by mixing solutions of DNA (either single-stranded (ssDNA) or double-stranded (dsDNA)) with solutions of cationic surfactant CTAB and solutions of the protein lysozyme. Swelling, surface morphology, and DNA rele...

  18. Gel del Vimang con actividad antifotoenvejecimiento: estudio histopatológico preliminar

    Directory of Open Access Journals (Sweden)

    Angel R. Concepción

    2003-03-01

    Full Text Available Se realizaron estudios de una nueva formulación (gel del Vimang, para evaluar en este caso parámetros histopatológicos, de un modelo in vivo; partiendo del antecedente que por resultados in vitro se sabe que el Vimang posee propiedades antioxidantes.Studies of a new formulation (Vimang's gel were conducted to evaluate, in this case, histopathological parameters of a model in vivo, starting from the antecedent that, according to results in vitro, Vimang has antioxidant properties.

  19. Highlights on the capacities of "Gel-based" proteomics

    OpenAIRE

    Chevalier François

    2010-01-01

    Abstract Gel-based proteomic is the most popular and versatile method of global protein separation and quantification. This is a mature approach to screen the protein expression at the large scale, and a cheaper approach as compared with gel-free proteomics. Based on two independent biochemical characteristics of proteins, two-dimensional electrophoresis combines isoelectric focusing, which separates proteins according to their isoelectric point, and SDS-PAGE, which separates them further acc...

  20. Synthesis of organically modified glasses by sol-gel techniques

    OpenAIRE

    Schmidt, Helmut K.

    1992-01-01

    Sol-gel derived inorganic-organic composites can be prepared in homogeneities sufficient for optical applications. Therefore, it is necessary to control structure formation, especially with respect to the distribution or aggregation of inorganic network forming units and organics. Inorganic components can be kept on a nano level by growth control using stabilazors interacting with the surface of colloidal particles formed by sol-gel or precipitation reactions. Thus, colloidal particles < 10 n...

  1. Silica Sol-Gel Coatings on Metals Produced by EPD

    OpenAIRE

    Castro, Y.; Ferrari, B; Moreno, R; A Durán

    2003-01-01

    The objective of this work has been to combine the sol-gel method and the electrophoretic deposition (EPD) process to prepare thick coatings onto metallic substrates. Two different routes were used for preparing the sol-gel silica suspensions. On one hand, silica particulate sols were obtained by basic catalysis of alkoxides and alkylalkoxides. On the other, silica suspensions were prepared by adding a commercial colloidal silica sol to an organic-inorganic acid catalysed silica s...

  2. Luminescent hybrid porphyrinosilica obtained by sol gel chemistry

    OpenAIRE

    Neri Cláudio Roberto; Calefi Paulo Sergio; Iamamoto Yassuko; Serra Osvaldo Antonio

    2003-01-01

    The sol-gel process is a methodology used to obtain organic-inorganic hybrid solids, which open new possibilities in the field of material science. The sol-gel technique offers a low temperature attractive approach for introducing organic molecules into amorphous materials. In order to introduce tetrakis (2-hydroxy-5-nitrophenyl)porphyrin covalently bounded to a silicate matrix, the inorganic precursor 3-isocyanatopropyltriethoxysilane was added (molar ratio 2:1) to the porphyrin solution in ...

  3. Silver-YBCO composite through citrate gel decomposition

    International Nuclear Information System (INIS)

    Silver-YBCO composite containing upto 75% silver has been prepared by thermal decomposition of citrate gel. In this paper the morphological and structural changes taking place during the decomposition of the gel in the range 100--900 degrees C are presented. Heat treatment at 915 degrees C of the composite powder containing Ag2O above a critical limit has been found to impart superconductivity without any external oxygen annealing. The mechanical and microstructural features of the sintered composite are presented

  4. Antifungal activity of aloe vera gel against plant pathogenic fungi

    International Nuclear Information System (INIS)

    Aloe vera gel extracted from the Aloe vera leaves was evaluated for their antifungal activity at the rate of 0.15%, 0.25% and 0.35% concentration against five plants pathogenic fungi viz., Aspergillus niger, Aspergillus flavus, Alternaria alternata, Drechslera hawaiensis and Penicillum digitatum 0.35% concentration Aloe vera gel completely inhibited the growth of Drechslera hawaiensis and Alternaria alternata. (author)

  5. Gel del Vimang con actividad antifotoenvejecimiento: estudio histopatológico preliminar

    Scientific Electronic Library Online (English)

    Angel R., Concepción; Roberto, de la Peña; Lucía, Fariñas.

    2003-03-01

    Full Text Available Se realizaron estudios de una nueva formulación (gel del Vimang), para evaluar en este caso parámetros histopatológicos, de un modelo in vivo; partiendo del antecedente que por resultados in vitro se sabe que el Vimang posee propiedades antioxidantes. [...] Abstract in english Studies of a new formulation (Vimang's gel) were conducted to evaluate, in this case, histopathological parameters of a model in vivo, starting from the antecedent that, according to results in vitro, Vimang has antioxidant properties. [...

  6. FORMULATION AND EVALUATION OF HERBAL GEL OF MAGNIFERA INDICA LINN

    OpenAIRE

    Gaikwad D. D.; Banerjee S.K.

    2012-01-01

    To formulate Magnifera indica Linn bark extract in to a gel. Ethanolic extract of dried bark of Magnifera indica Linn were subjected to priliminery phytochemical evaluation studies. Different gel formulations of ethanolic extract of Magnifera indica linn (2% w/v) were prepared using polymers carbopol 934 & HPMC by varying their concentration. These formulation were evaluated for physical parameters, drug contains, Ph, viscosity, Extrudability, Spread ability, primary skin irritation, study....

  7. Nanoparticles laden in situ gel for sustained ocular drug delivery

    OpenAIRE

    Gupta, Himanshu; Aqil, Mohammed; Khar, Roop K.; Ali, Asgar; Bhatnagar, Aseem; Mittal, Gaurav

    2013-01-01

    Proper availability of drug on to corneal surface is a challenging task. However, due to ocular physiological barriers, conventional eye drops display poor ocular bioavailability of drugs (< 1%). To improve precorneal residence time and ocular penetration, earlier our group developed and evaluated in situ gel and nanoparticles for ocular delivery. In interest to evaluate the combined effect of in situ gel and nanoparticles on ocular retention, we combined them. We are the first to term this c...

  8. Sol-gel nanocomposites as functional optical materials

    OpenAIRE

    Schmidt, Helmut K.

    1992-01-01

    Small particle processing opens a variety of interesting aspects for optical applications. For the utilization, the sol-gel process offers a variety of routes, like colloid synthesis, incorporating into sol-gel derived matrices and in combination with photopolyermizabel components patterning processes based on photolithography. In this paper, a summary over a new conception of colloid stabilization and colloid processing by multifunctional ligands and further processing routes for optical app...

  9. Development of Radiation Curable polymeric Gel Electrolyte Formulation

    International Nuclear Information System (INIS)

    The result of this study, the free lithium ions of polymer gel electrolyte containing hydroxyproply Cellulose 1% is the most excellent due to irradiate of strong energy over quick time, although curing reaction of EB system is a very fast, polymer gel electrolyte containing hydroxypropyl Cellulose Fabricated by UV system is excellent curing reaction and ionic conductivity and mechanical properties and thermal stability than EB system

  10. Simultaneous Immunofluorescent Detection of Coentrapped Cells in Gel Beads

    OpenAIRE

    Prioult, Guenolee; Lacroix, Christophe; Turcotte, Carl; Fliss, Ismaïl

    2000-01-01

    An immunofluorescent method involving double color labeling and confocal microscopy was reported to specifically detect lactic acid bacteria and probiotic cells coimmobilized in gels beads. The method described is rapid (4 h) and sensitive and may be useful for studying cell dynamics during mixed-culture starter production using immobilized cells in gel beads. Microscopic observations were perfectly correlated to cell counts obtained using a sandwich enzyme-linked immunosorbent assay.

  11. Rheological properties of soybean protein isolate gels containing emulsion droplets

    OpenAIRE

    Kim, K.H.; Renkema, J.M.S.; Vliet, T.

    2001-01-01

    Rheological properties of soybean protein gels containing various volume fractions oil droplets have been studied at small and large deformations. Dynamic viscoelastic properties of soybean protein isolate gels were determined as a function of the volume fraction of oil droplets stabilised by the same protein, both in absence and presence of 0.2 M sodium chloride (NaCl). The storage and loss moduli were higher if NaCl was added. For both conditions, they increased with increasing oil volume f...

  12. Thermosensitive gels for the topical administration of diltiazem

    OpenAIRE

    Trotta, Michele; CARLOTTI, Maria Eugenia; GALLARATE, Marina; PEIRA, Elena; CHIRIO, Daniela

    2011-01-01

    In the present work thermosensitive systems were prepared, characterized and proposed for diltiazem administration in the topical treatment of anal fissures. Methylcellulose and Pluronic®F127 were used as gelling polymers. Some low toxicity-molecules as sodium glycocholate, citric acid and lactic acid were added to gel formulations as counterions to enhance diltiazem lipophilicity. The systems were characterized by sol-gel transition temperature, viscosity and rheological studies. The res...

  13. Deformation and fracture of cross-linked polymer gels

    Science.gov (United States)

    Lin, Wei-Chun

    Because soft materials, particularly polymer gels, are playing a greater role in industrial and biotechnological applications today, the exploration of their mechanical behavior over a range of deformations is becoming more relevant in our daily lives. Understanding these properties is therefore necessary as a means to predict their response for specific applications. To address these concerns, this dissertation presents a set of analytic tools based on flat punch probe indentation tests to predict the response of polymer gels from a mechanical perspective over a large range of stresses and at failure. At small strains, a novel technique is developed to determine the transport properties of gels based on their measured mechanical behavior. Assuming that a polymer gel behaves in a similar manner as a porous structure, the differentiation of solvent flow from viscoelasticity of a gel network is shown to be possible utilizing a flat, circular punch and a flat, rectangular punch under oscillatory conditions. Use of the technique is demonstrated with a poly(N-isopropyl acrylamide) (pNIPAM) hydrogel. Our results indicate that solvent flow is inhibited at temperatures above the critical solution temperature of 35°C. At high stresses and fracture, the flat probe punch indentation geometry is used to understand how the structure and geometry of silicone based gels affect their mechanical properties. A delayed failure response of the gels is observed and the modes of failure are found to be dependent on the geometry of the system. The addition of a sol fraction in these gels was found to toughen the network and play an important role at these large deformations. Potential mechanisms of fracture resistance are discussed, as is the effect of geometric confinement as it relates to large scale deformation and fracture. These results lay the groundwork for understanding the mechanical response of other highly, deformable material systems utilizing this particular geometry.

  14. Investigations of rheological properties of diclofenac sodium gel preparation

    OpenAIRE

    Firuza Maksudova; Ekut Karieva

    2013-01-01

    It is well-known that the majority of non-steroidal anti-inflammatory drugs (NSAIDs) are ulcerogenic. Gel or ointment preparations of NSAIDs are free from this side-effect, which is a prerequisite for the increase of aforementioned forms of NSAIDs. A major quality indicator of gels and ointments are rheological properties. Along with determining the quality of preparation, they influence manufacturing, expiration date and terms of storage. This article demonstrates the results of investiga...

  15. Uptake and Recovery of Lead by Agarose Gel Polymers

    OpenAIRE

    Anurag Pandey; Anupam Shukla; Lalitagauri Ray

    2009-01-01

    Problem statement: The uptake and recovery of lead ions were investigated by using agarose gel polymers. Approach: The experimental results showed that the agarose gel were effective in removing Pb (II) from solution. Biosorption equilibrium was approached within 4 h. Pseudo second-order was applicable to all the sorption data over the entire time range. Results: The sorption data conformed well to both the Langmuir and the Freundlich isotherm model. The ma...

  16. Formation, structure and rheological properties of soy protein gels.

    OpenAIRE

    Renkema, J.M.S.

    2001-01-01

    Keywords: soy protein isolate, glycinin,?-conglycinin, heat denaturation, gelation, network structure, rheology, permeability measurements, microscopy, pH, ionic strength, emulsified oil dropletsThis study was performed to understand the factors determining heat-induced formation and properties of soy protein gels the relations between gel properties and network structure in order to support application of soy proteins in food products. Three soy protein preparations were used: soy protein is...

  17. Field inversion gel electrophoresis with different pulse time ramps.

    OpenAIRE

    Heller, C.; Pohl, F M

    1990-01-01

    The influence of different pulse time ramps on the separation of yeast chromosomes with field inversion gel electrophoresis (FIGE) was investigated by the means of two dimensional gel electrophoresis. The problem of band inversion, which makes it difficult to distinguish DNA molecules of different size, has been solved by using double randomized pulse times. A major disadvantage of the field inversion technique is thereby overcome, making this system comparable to other pulsed field techniques.

  18. Creep and Fracture of a Protein Gel under Stress

    OpenAIRE

    Leocmach, Mathieu; Perge, Christophe; Divoux, Thibaut; Manneville, Sébastien

    2014-01-01

    Biomaterials such as protein or polysaccharide gels are known to behave qualitatively as soft solids and to rupture under an external load. Combining optical and ultrasonic imaging to shear rheology we show that the failure scenario of a protein gel is reminiscent of brittle solids: after a primary creep regime characterized by a power-law behavior which exponent is fully accounted for by linear viscoelasticity, fractures nucleate and grow logarithmically perpendicularly to ...

  19. Constitutive modelling of cork-polyurethane gel composites

    OpenAIRE

    Antunes, Paulo Jorge da Rocha Soares

    2009-01-01

    O CPGC - Cork-Polyurethane Gel Composite é um material rubber-like produzido em Portugal pela ACC-Amorim Cork Composites. A combinação não convencional de cortiça com gel de poliuretano traduz-se na obtenção de um material compósito com características mecânicas particulares. Estas características devem ser estudadas e compreendidas de forma a potenciar novas aplicações em CPGC ou a optimização do desempenho mecânico de componentes já produzidos em CPGC. A aplicação de CPGC em produtos tais c...

  20. FORMULATION AND EVALUATION OF CANDESARTAN CILEXETIL TRANSDERMAL PRONIOSOMAL GEL

    OpenAIRE

    archana pinnika

    2014-01-01

    The present work deals with the preparation of candesartan cilexetil proniosomal gel by coaservation phase separation method by using different surfactants, cholesterol and soya lecithin in 9:1:9 and 9:2:9 ratios. The prepared proniosomal gel formulations were evaluated for vesicle size analysis, surface morphological studies, encapsulation efficiency, In vitro drug release, ex vivo skin permeation studies and vesicular stability at different storage conditions. The results showed that candes...

  1. 2D Electrophoresis Gel Image and Diagnosis of a Disease

    OpenAIRE

    Kim, Gene; Kim, Myungho

    2003-01-01

    The process of diagnosing a disease from the 2D gel electrophoresis image is a challenging problem. This is due to technical difficulties of generating reproducible images with a normalized form and the effect of negative stain. In this paper, we will discuss a new concept of interpreting the 2D images and overcoming the aforementioned technical difficulties using mathematical transformation. The method makes use of 2D gel images of proteins in serums and we explain a way of...

  2. Epoxy-silica nanocomposite by nonaqueous sol-gel process.

    Czech Academy of Sciences Publication Activity Database

    Ponyrko, Sergii; Mat?jka, Libor

    Ljubljana : Center for Experimental Mechanics, Faculty of Mechanical Engineering, University of Ljubljana, Institute for Sustainable Innovative Technologies, 2014. s. 55. [International Conference on Modification, Degradation and Stabilization of Polymers /8./ - MoDeSt 2014. 31.08.2014-04.09.2014, Portorož] R&D Projects: GA ?R GAP108/12/1459 Institutional support: RVO:61389013 Keywords : epoxy- silica hybrid * nonaqueous sol- gel process * gel ation Subject RIV: CD - Macromolecular Chemistry

  3. Structural Relaxation of a Gel Modeled by Three Body Interactions

    OpenAIRE

    Saw, Shibu; Ellegaard, Niels L.; Kob, Walter; Sastry, Srikanth

    2009-01-01

    We report a molecular dynamics simulation study of a model gel whose interaction potential is obtained by modifying the three body Stillinger-Weber model potential for silicon. The modification reduces the average coordination number, and suppresses the liquid-gas phase coexistence curve. The low density, low temperature equilibrium gel that can thus form exhibits interesting dynamical behavior, including compressed exponential relaxation of density correlations. We show tha...

  4. Gel-based biochip for the detection of airborne contaminants

    OpenAIRE

    Schmitt, K; Sulz, G.; Klockenbring, T; Seidel, B.; Holländer, A.

    2010-01-01

    The fast and direct identification of possibly pathogenic microorganisms in air is gaining increasing interest due to their threat for public health, e.g. in clinical environments or in clean rooms of food or pharmaceutical industries. We present a new detection method allowing the direct recognition of relevant germs or bacteria via fluorescence-labeled antibodies in a gel-based biochip within less than 1 h. In detail, the microorganisms are collected on a gel-based substrate containing fluo...

  5. Sulfur-Containing Organic-Inorganic Hybrid Gel Compositions and Aerogels

    Science.gov (United States)

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

    2015-01-01

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

  6. Rheological Properties of N-(isopropylacrylamide)-Clay based Nanocomposite gels

    Science.gov (United States)

    Bhatnagar, Divya; Lombardi, Jack; Rafailovich, Miriam

    2010-03-01

    Polymer -Clay nanocomposite gels (NC gels) consisting of N-(Isopropylacrylamide) (NIPA) and exfoliated inorganic clay (hectorite) were investigated in terms of their rheological properties. Depending on the clay concentration (Cclay), NC gels exhibit unique changes in their mechanical strength. To investigate their mechanical properties NC1-NC25 gels were subjected to oscillatory shear rheometry and Oscialltory stress, frequency and temperature sweep was conducted to evaluate the respective G's with varying shear stress, frequency and temperature. The results from stress sweep indicated the clear dependence of G' on Cclay. G' increased with an increase in clay content making NC25 the stiffest and NC1 the softest. Frequency sweep also suggested the formation of a stable polymer-clay platelet system. Results from temperature sweep suggested the stability of the polymer-clay network over a range of temperatures where a slight drop was seen in G' for gels NC1-NC8. From NC10-NC25, temperature had no effect on their respective G's. Glucose was added into the NC3 and NC5 polymer-clay system and Oscillatory stress and frequency sweep were conducted. The glycated NC3 gel collapsed when the glucose concentration was increased to 0.5-1%(w/v) although glycated NC5 did not register much noticeable results.

  7. Sol-gel Technology and Advanced Electrochemical Energy Storage Materials

    Science.gov (United States)

    Chu, Chung-tse; Zheng, Haixing

    1996-01-01

    Advanced materials play an important role in the development of electrochemical energy devices such as batteries, fuel cells, and electrochemical capacitors. The sol-gel process is a versatile solution for use in the fabrication of ceramic materials with tailored stoichiometry, microstructure, and properties. This processing technique is particularly useful in producing porous materials with high surface area and low density, two of the most desirable characteristics for electrode materials. In addition,the porous surface of gels can be modified chemically to create tailored surface properties, and inorganic/organic micro-composites can be prepared for improved material performance device fabrication. Applications of several sol-gel derived electrode materials in different energy storage devices are illustrated in this paper. V2O5 gels are shown to be a promising cathode material for solid state lithium batteries. Carbon aerogels, amorphous RuO2 gels and sol-gel derived hafnium compounds have been studied as electrode materials for high energy density and high power density electrochemical capacitors.

  8. Low-cost two-dimensional gel densitometry

    International Nuclear Information System (INIS)

    A major obstacle to full utilization of the powerful technique of two-dimensional (2-D) gel electrophoresis is the expense and complexity of quantifying the results. Using an analog-to-digital converter already present in the widely available Commodore 64 or Commodore 128 microcomputer, the authors have developed a 2-D gel densitometer (GELSCAN) which adds only $20.00 to the cost of the Commodore system (currently around $700.00). The system is designed to work with autoradiograms of 2-D gels. Spots of interest are identified visually and then positioned manually over a light source. A pinhole photoelectric sensor mounted in a hand-held, Plexiglas holder, or mouse, is briefly rubbed over each spot. Maximum density of the spot is determined and its value is converted to counts per minute via an internal calibration curve which corrects for the nonlinear response of film to radiation. Local spot backgrounds can be subtracted and values can be normalized between gels to adjust for variation in amount of radioactivity applied or in exposure time. Reproducibility is excellent and the technique has some practical as well as theoretical advantages over other more complicated approaches to 2-D gel densitometry. In addition, the GELSCAN system can also be used for scanning individual bands in 1-D gels, quantitation of dot-blot autoradiograms and other tasks involving transmission densitometry

  9. Characterization of Hybrid Sol-gel Coatings Applied over Tinplate

    Scientific Electronic Library Online (English)

    D., Álvarez; A., Collazo; C., Pérez.

    2013-10-08

    Full Text Available The present work studies the behavior of hybrid sol-gel films based on tetraethyl orthosilicate (TEOS) and vinyltrimethylsiloxane (VTMS) precursors applied over commercial tinplate. In previous works VTMS films obtained by the sol-gel technology were tested to verify their good corrosion performance [...] over short immersion times in a citric acid/sodium citrate buffer solution. However, at longer exposure times the high porosity inherent to organic sol-gel films allows the aggressive media to reach the metallic substrate and start the corrosion process. In order to overcome these limitations, hybrid organic-inorganic sol-gel coatings were obtained using the dip- coating method. This work also studies the influence of the ageing time of the hybrid sol-gel in the formation of a uniform and continuous film. The obtained layers were characterized using a Scanning Electron Microscopy (SEM) and mechanical profilometry. The corrosion performance in organic acid media was tested using polarization curves and Electrochemical Impedance Spectroscopy (EIS) with a 0.1M citric/citrate buffer solution as electrolyte. The results obtained suggest that a minimum ageing time of 10 days is needed to obtain uniform films. The electrochemical measurements indicate a clear improvement on the barrier properties on the hybrid sol-gel compared to the organic ones. A major decrease in the impedance values after 24 hours of immersion indicates that it is necessary to improve the long-term barrier properties to achieve an industrial application.

  10. Synthesis of polysaccharide chemical gels by gamma-irradiation

    International Nuclear Information System (INIS)

    Recently many biodegradable hydrogel systems have been developed in the area of controlled drug delivery. In previous studies, the authors prepared biodegradable hydrogels by crosslinking natural polymers, such as albumin and dextran, using gamma-irradiation. Natural polymers were functionalized by introducing double bonds through reaction with glycidyl acrylate. The functionalized polymers were then crosslinked to form chemical gels by exposure to gamma-irradiation. In this study, they examined the ability of various polysaccharides to form chemical gels by gamma-irradiation. Dextran, alginic acid, hyaluronic acid, benzyl esters of hyaluronic acid, and gellan were functionalized. The effects of the polymer concentration and the gamma-irradiation dose on the hydrogel formation were examined. All the polysaccharides used formed chemical gels, although the extent of gel formation was different. For alginic acid, hyaluronic acid, and benzyl ester of hyaluronic acid at 25% of esterification degree, the chemical gels were formed at lower polymer concentration and at lower gamma-irradiation dose, if the solution was acidified to pH 3. The ability to form chemical gels with various natural polymers would be useful in the development of controlled drug delivery systems

  11. Nickel-doped agarose gel phantoms in MR imaging

    International Nuclear Information System (INIS)

    A method for the production of a tissue-mimicking phantom material for MR imaging is described. The material consists of a nickel-doped agarose gel. The T1 and T2 values of the gel can be varied independently by changing the relative amounts of nickel and agarose. Practically any T1 and T2 combination of clinical interest can be obtained. The long-term stability was studied and found to be good. The relaxation times were estimated using an MR analyzer. The accuracy and the reproducibility of these measurements were evaluated and found to be reassuring. Gel phantoms were also scanned in an MR unit. The signal strength of an inversion recovery sequence was evaluated using the gel phantoms in order to verify their usefulness. These measurements were compared to theory with good agreement. Furthermore, tissue-equivalent phantoms were made. Gels resembling gray matter, white matter, and CSF were scanned. Comparisons with clinical in vivo scans, as well as calculated levels are made. It is anticipated that the gel phantoms described here will be useful in quality assurance as well as in pulse sequence optimization. (orig.)

  12. Energy-Efficient Bioalcohol Recovery by Gel Stripping

    Science.gov (United States)

    Godbole, Rutvik; Ma, Lan; Hedden, Ronald

    2014-03-01

    Design of energy-efficient processes for recovering butanol and ethanol from dilute fermentations is a key challenge facing the biofuels industry due to the high energy consumption of traditional multi-stage distillation processes. Gel stripping is an alternative purification process by which a dilute alcohol is stripped from the fermentation product by passing it through a packed bed containing particles of a selectively absorbent polymeric gel material. The gel must be selective for the alcohol, while swelling to a reasonable degree in dilute alcohol-water mixtures. To accelerate materials optimization, a combinatorial approach is taken to screen a matrix of copolymer gels having orthogonal gradients in crosslinker concentration and hydrophilicity. Using a combination of swelling in pure solvents, the selectivity and distribution coefficients of alcohols in the gels can be predicted based upon multi-component extensions of Flory-Rehner theory. Predictions can be validated by measuring swelling in water/alcohol mixtures and conducting h HPLC analysis of the external liquid. 95% + removal of butanol from dilute aqueous solutions has been demonstrated, and a mathematical model of the unsteady-state gel stripping process has been developed. NSF CMMI Award 1335082.

  13. Novel modification method of sol-gel thin films. Densification of silica gel films with electronic excitation

    International Nuclear Information System (INIS)

    Significant structural changes in silica gel films with synchrotron radiation (SR) and energetic He+ ions have been found. Irradiation with photons in the energy range higher than ?8 eV and 100-keV He+ ions induce an increase in refractive index and a decrease in thickness of silica gel films. Fourier transform infrared absorption spectra indicate that irradiation with the photons and the ions reduces the Si-OH content and the average Si-O-Si bridging angle. Electronic excitation with energetic photons is suggested to induce atomic rearrangement which causes densification of silica gel. Structural changes with He+ implantation is also tentatively ascribed to an electronic process. Electronic processes using SR and light ion implantation are anticipated to offer an alternative route to prepare dense thin films derived from sol-gel method. (author)

  14. Purification of monoterpenyl glycosides by gel-permeation and hydrophobic-interaction chromatography on polyacrylamide (Bio-Gel P-2).

    Science.gov (United States)

    Croteau, R; El-Hindawi, S; El-Bialy, H

    1984-03-01

    Hydrophobic interaction of the aglycone of monoterpenyl glycosides with the polyacrylamide matrix of Bio-Gel P-2 greatly retards the elution of these substances when chromatographed in dilute aqueous sodium chloride. This hydrophobic interaction is eliminated by inclusion of 15% acetonitrile in the eluant, thereby permitting conventional gel-permeation chromatography. Combination of these techniques by sequential chromatography on the same Bio-Gel column, in the hydrophobic interaction mode followed by the gel-permeation mode, provides a simple, yet mild and highly selective procedure for the purification of monoterpenyl glycosides from crude plant extracts. Examination of the chromatographic properties of beta-D-glucopyranosides and beta-D-galactopyranosides of a number of acyclic, monocyclic, and bicyclic monoterpenols indicates that the extent of hydrophobic interaction is of diagnostic value in determining the nature of the aglycone. PMID:6731821

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

    Science.gov (United States)

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

    2004-12-01

    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 0.015Sth(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.

  16. Energy dependence of radiochromic gels for low-energy photon radiation

    International Nuclear Information System (INIS)

    The contribution summarizes the results of measurement of energy dependence of two types of radiochromic gel dosimeters on low energy photon radiation between 14 and 145 keV. The energy dependence was determined for two different types of gels - a well-known Fricke infused xylenol orange ion indicator gel (FX gel) and a gel based on Turnbull blue dye (TB gel). Gel samples in PMMA cuvettes with a front wall replaced by a thin Mylar foil were irradiated at reference photon fields at the Czech Metrology Institute. Response of the irradiated gels was evaluated by UV-VIS spectrophotometry and by photographing with a 16-bit grayscale astronomical CCD camera. It was found out that the response of the TB gel is independent on photon energy down to at least 14 keV photons, while the FX gel is energy dependent for photons below roughly 50 keV (authors)

  17. Fabrication and Optimization of a PAGATA gel dosimeter: increasing the melting point of the PAGAT gel dosimeter with agarose additive

    International Nuclear Information System (INIS)

    The PAGAT polymer gel dosimeter melts at 30degreeC and even at room temperature during the summer, so it needs to be kept in a cool place such as a refrigerator. To increase the stability of the PAGAT gel, different amounts of agarose were added to the PAGAT gel composition and the PAGATA gel was manufactured. Material and Methods: The PAGATA gel vials were irradiated using a CO-60 machine. Then, the samples were evaluated using a 1.5 T Siemens MRI scanner. The ingredients of the PAGATA normoxic gel dosimeter were 4.5% N-N' methylen-bis-acrylamide, 4.5% acrylamide, 4.5% gelatine, 5 m M tetrakis (THPC), 0.01 mM hydroquinone, 0.5% agarose and 86% de-ionized water (HPLC). Results: Melting point and sensitivity of the PAGAT gel dosimeter with addition of 0.0, 0.3, 0.5, 1.0, 1.5 and 2.0% of agarose were measured, in which the melting points Were increased to 30, 82, 86, 88, 89 and 90degreeC and their sensitivities found to be 0.113, 0.1059, 0.125, 0.122, 0.115 and 0.2 S-1Gy-1 respectively. Discussion and Conclusions: Adding agarose increased the sensitivity and background R2 of the evaluated samples. The optimum amount of agarose was found to be 0.5% regarding these parameters and also the melting point of the gel dosimeter. A value of 0.5% agarose was found to be an optimum value considering the increase of sensitivity to 0.125 and melting point to 86degreeC but at the expense of increasing the background R2 to 4.530.

  18. Monoestolides Synthesis From Ricinoleic-Oleic Acids Using Silicotungstic Acid Sol-Gel Catalyst

    OpenAIRE

    Nor Asikin Mohamad Nordin; Nadia Farhana Adnan; Noraini Hamzah; Wan Nor Roslam Wan Isahak; Jumat Salimon; Mohd Ambar Yarmo

    2011-01-01

    Sol-gel silica-supported hydrated silicotungstic acid (STA sol-gel), prepared by incorporating hydrated silicotungstic acid (STA) into silica via sol-gel technique, was used as an efficient heterogeneous catalyst for condensation reaction of a mixture ricinoleic acid (RA) and oleic acid (OA). The activity and selectivity of STA sol-gel for the condensation reaction of a mixture RA and OA have been investigated and compared with unsupported STA and homogeneous perchloric acid. STA sol-gel and ...

  19. Deformation and fracture of emulsion-filled gels: Effect of oil content and deformation speed

    OpenAIRE

    Sala, G.; Vliet, T.; Cohen Stuart, M.A.; Aken, G.A., van; van de Velde, F.

    2009-01-01

    The large deformation properties of gelatine, ¿-carrageenan and whey protein isolate (WPI) gels filled with bound and unbound oil droplets were studied as a function of compression speed. The rheological properties of the gel matrices controlled the compression speed-dependency of the gels containing oil droplets. Polymer gels (gelatine and ¿-carrageenan gels) showed a predominantly elastic behaviour. Their Young's modulus was not affected by the compression speed. The increase of fracture st...

  20. "Tell Juliana": acceptability of the candidate microbicide VivaGel® and two placebo gels among ethnically diverse, sexually active young women participating in a phase 1 microbicide study.

    Science.gov (United States)

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

    2012-10-01

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

  1. Preliminary study on CT imaging of polymer gel radiation dosimetry

    International Nuclear Information System (INIS)

    Background: New radiotherapy techniques such as stereotactic radiotherapy (SRT) stereotactic radiosurgery (SRS), three dimensional conformal radiotherapy (3DCRT) and intensity modulated radiation therapy (IMRT) aim to deliver a high dose to the tumour while sparing the surrounding normal healthy tissues. As a result of these complicated treatment techniques there is a need for a 3-dimensional (3D) dose verification system. However, currently available dosimeters such as ion chambers, diodes, thermoluminescent dosimeters and films are limited to point (or) planar measurement. Multiple measurements are required to obtain the 3-dimensional dose distribution using the above dosimeters. Hence volumetric measurements are not feasible without multiple detectors (or) multiple measurements. Gel dosimetry attempts to meet the requirements of 3D radiation dose distribution. Gel dosimetry is tissue equivalent and it acts as a phantom as well as dosimeter so there is no need for dose perturbation correction. Aim: Radiation-induced polymerization in polymer gel dosimeters gives rise to a change in CT number which can be measured with X-ray computed tomography (CT). The aim of this study is to assess the feasibility of using the X-ray CT scanner for the evaluation of dose distribution in polymer gel dosimetry. Materials/Methods: Polymer gel called PAGAT (Polyacrylamide Gelatin and Tetrakis hydroxymethyl phosphonium) consisting of 3.5 % (w/w) BIS, 3.5 % (w/w) acrylamide, 5 % (w/ w) gelatin, 10 mM Tetrakis hydroxymethyl phosphonium (THP) and 88 % (w/w) water was manufactured in normal atmospheric conditions. The gel was irradiated using a Siemens Primus linear accelerator. The radiation-induced change in CT number was evaluated using a Siemens Somatom Emotion CT scanner. The percentage depth doses and profiles were deduced. The same study was carried out using radiation field analyzer RFA-200 with RK-ion chamber and film and compared with polymer gel measurements. Results: Polymer gel dosimetry measurement was in agreement with ion chamber and film measurements except for a slight deviation in the build-up region. Discrepancies found were due to analysis of image without image averaging and background subtraction. Conclusions: This preliminary study was conducted to evaluate the feasibility of using X-ray CT-based polymer gel dosimetry for clinical use. The results of this study encourage further use of X-ray CT in conjunction with polymer gel for 3D radiation dose measurements. (authors)

  2. The INET's progress of silica gel adsorption for zirconium

    International Nuclear Information System (INIS)

    A High Level Liquid Waste (HLLW) partition process, trialkyl phosphine oxides (TRPO) process has been developed by INET (Institute of Nuclear and new Energy Technology) of Tsinghua University in China to recover the Minor Actinides (MA) and Long-Lived Fission Products (LLFP) since 1980 s. The feasibility of TRPO process was proved by hot tests and Pilot-plant scale experiment. HLLW liquid waste arising from spent nuclear fuel reprocessing process contains zirconium, which will deteriorate MAs and LLFPs' recovery from HLLW. Therefore, as first step of the TRPO process, removal of Zr is studied. In INET, studies on the adsorption of silica gel for Zr have been carried out. In this paper the progress of silica gel adsorption is reviewed and a technical process is introduced. Purchased silica gel was used to study the adsorption behavior of Zr and other nuclides in HLLW. The result of static adsorption shows that the static capacity of Zr on silica gel is about 20 mg Zr/g in 1.0-4.0 mol/L HNO3 solution; the adsorption distribution coefficient of Pu(IV) is about 0.7-1.4 ml/g; U and Np are not adsorbed on silica gel; among all fission products, besides Zr only a part Mo is adsorbed on silica gel, while other fission products (Fe, Mn, Sr etc.) are not adsorbed. The result of dynamic adsorption shows that the effective capacity of silica gel column is 3.5 times of bed volume; a little Pu is adsorbed on silica gel together with Zr; the adsorbed Zr and Pu in column can be partly eluted by HNO3; 0.2 mol/L H2C2O4 can be used to elute Zr and Pu completely. In order to reduce the volume of waste silica gel, the regeneration and reuse of silica gel was studied. The 0.2 mol/L H2C2O4 eluted silica gel column can be reused at least six times and the dynamic adsorption property of Zr is almost the same each time. We also studied the measurement of Pu adsorbed on silica gel and found that the radioactivity specific activity of Pu remained on the silica gel after H2C2O4 elution is about 1x104 Bq/kg, which means the waste silica gel belongs to non-?-emitting waste. After the removal of Zr by the technical process introduced in this paper, HLLW can be treated with TRPO process. The final eluted Zr/Pu/H2C2O4 mixed solution can be solidified as medium radioactivity solid waste by cement solidification method. (author)

  3. Purification of Peptide Components including Melittin from Bee Venom using gel filtration chromatography and propionic acid/urea polyacrylamide gel electrophoresis

    OpenAIRE

    Young Chon Choi; Ki Rok, Kwon; Suk Ho, Choi

    2006-01-01

    Objectives : This study was conducted to carry out Purification of Melittin and other peptide components from Bee Venom using gel filtration chromatography and propionic acid/urea polyacrylamide gel electrophoresis Methods : Melittin and other peptide components were separated from bee venom by using gel filtration chromatography on Sephadex G-50 column in 0.05M ammonium acetate buffer. Results : Melittin and other peptide components were separated from bee venom by using gel filtration...

  4. Modelling the behaviour of the push-pull gel dosimeter

    International Nuclear Information System (INIS)

    Full text: Recent development of a gel dosimeter based on the radiobleaching pigment, genipin, allows development of a new 3D optically scanned gel dosimeter-the push-pullgel. This gel would contain two spectrally complementary pigments, one which darkens with dose and another (e.g. genipin) which bleaches. The two pigments deal separately with the high and low dose ends of the dosimeter's dynamic range. The bleaching pigment would be optimised for high sensitivity and the darkening pigment for low. Employing dual pigments, optimised independently, relaxes the need for compromise between sensitivity at low dose and accuracy at high dose. Such a gel, after exposure, would be read using two successive optical CT scans, at two different wavelengths. The reduction in sensitivity of the darkening pigment (allowed by the use of push-pull) would reduce the occurrence of regions of high optical attenuation which can generate optical CT artefacts. Simulated optical CT reconstructions of the optical density map (Fig. La) scanned at the darkening pigment wavelength of a hypothetical push-pull gel, confirms the reduction in susceptibility to artefacts. Fig. I b shows a profile through the map with no stray light added. The centre of the profile in Fig. I d shows a cupping artefact produced by 10 ppm of stray light. The similarity of Fig. Ic and b show that a 30% sensitivity reduction allowed by push-pull, renders the artefact negligible. This paper presents the results of' these simulations of a push-pull gel scanned using optical CT and also some results of experiments with genipin gel. (author)

  5. Silicone gel em cicatrizes de cirurgia plástica: estudo clínico prospectivo Silicone gel in plastic surgery scars: a prospective study

    Directory of Open Access Journals (Sweden)

    Henrique N Radwanski

    2010-09-01

    Full Text Available INTRODUÇÃO: O uso de gel de silicone em cicatrizes data do começo da década de 1980. Desde então, um grande número de trabalhos científicos, e dezenas de diferentes fórmulas do produto, vêm sendo publicados e experimentados, atestando os benefícios do gel de silicone na prevenção de cicatrizes hipertróficas e quelóides. Apesar do mecanismo exato de ação do silicone ainda ser desconhecido, a hipótese mais aceita é que o curativo oclusivo estimula os queratinócitos à maior secreção de fatores de crescimento localmente, influenciando consequentemente a regulação dos fibroblastos. MÉTODO: Com o objetivo de comprovar os benefícios do silicone gel na melhora clínica das cicatrizes de etiologia cirúrgica eletiva, foi realizado um estudo prospectivo, numa população miscigenada, no Serviço de Cirurgia Plástica na 38ª Enfermaria da Santa Casa da Misericórdia do Rio de Janeiro. RESULTADOS: O gel de silicone demonstrou ação favorável em cicatrizes pós-cirurgia plástica. CONCLUSÃO: O uso de silicone gel mostrou-se útil na melhora de cicatrizes recentes, melhorando parâmetros subjetivos e objetivos, como eritema, prurido e endurecimento.BACKGROUND: The use of silicone gel on surgical wounds began in the 1980's. Since then, a large number of scientific papers and dozens of different formulas have been published and experimented, attesting the benefits of this product in the prevention of hypertrophic scars and keloids. Although the exact mechanism of action of silicone gel has not yet been elucidated, the most widely accepted theory explains that the occlusive film stimulates the keratinocytes to increase the local secretion of growth factors, subsequently influencing the regulation of fibroblasts. METHODS: A prospective study was undertaken at the 38th Ward of the Santa Casa General Hospital, Rio de Janeiro, to evaluate the positive effects of silicone gel on surgical wounds, in a mixed race population. RESULTS: Silicone gel demonstrated a positive effect on surgical wounds following plastic surgery. CONCLUSION: Silicone gel is useful to enhance the quality of recent scars, in both subjective and objective parameters, such as erythema, pruritus and firmness.

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

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    González Ester Teresa

    1999-01-01

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

  7. Gel dosimetry - a laser based 3D scanner for gel samples - research in India

    International Nuclear Information System (INIS)

    A laser based 3D scanner is developed to take tomography images of partly transparent samples. The scanner is optimized to characterize gel samples from spatially resolved dosimetry measurements. The resulting device should be suitably designed to be constructed in India. This gave me valuable insight into the scientific and technological environment of the country and made me find my way through a quite different culture of research and commerce, within and beyond the scientific context of the university. The project was implemented during a nine months stay at the Vellore Institute of Technology University in Vellore, Tamil Nadu, India, in co-operation with the Christian Medical College, Vellore, in 2006/07. It was conducted within the framework of existing research activities of the host university.

  8. Osteoconducting bioglass synthesis via sol-gel process; Biovidro osteocondutor sintetizado pelo processo sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, R.V.; Aragones, A.; Barra, G.O.M.; Salmoria, G.V.; Fredel, M.C., E-mail: rafaelavpereira@gmail.com [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2012-07-01

    The presence of bioglasses in scaffolds has been studied as they promote the osteoconduction in bones. The scaffolds are developed in order to induce the repair and regeneration in bone tissue. An absorbable bioglass from SiO2-CaO-P2O5 system was synthesized by sol-gel process with the intent of producing these scaffolds. Bioglass 58S was define for these work once it presents ions (Ca and P) which assist at the carbonated apatite layer formation when released. The apatite layer presents an important role at the bone regeneration and metabolism, being involved at grow and mineralization of bones. FTIR was realized to characterize the synthesized bioglass on its chemical composition, XRD to analyze the crystalline structure, solubility test to observe the weight variance and SEM to observe the particles morphology. The obtained results confirmed the production of a bioglass with the desired composition to produce osteoconducting scaffolds. (author)

  9. Gel Generator Technology Viability for Small Scale Production - Indian Experience [Country report: India - GEL Gen.

    International Nuclear Information System (INIS)

    The radioisotope 99mTc is used in nearly 80% of all diagnostic imaging procedures in nuclear medicine and hence ensuring its uninterrupted availability is of prime importance to the nuclear medicine industry. Of the various options available for accessing 99mTc from its precursor 99Mo through a generator system, the 99mTc generator using a bed of acidic alumina column for column chromatographic separation of 99mTc from 99Mo remains the most popular procedure world over. The uninterrupted availability of high specific activity (n,f)99Mo, an essential requirement for the alumina column generators and produced by few large scale commercial suppliers, needs to be ensured to avoid frequent disruption in 99mTc supplies. Alternate technologies that could use (n,?)99Mo to meet partial/complete domestic demands are worth exploring to reduce import dependency/foster self-sufficiency particularly in countries having the necessary infrastructure in place. The Indian pursuit of gel generator technology for 99mTc was driven mainly by three considerations, namely, (i) reliable, well-established and ease of production of (n,?)99Mo in TBq quantities in the research reactors in Trombay/Mumbai, India, (ii) need for relatively low-cost alternate technology to replace the solvent (MEK) extraction generator system in use in India since 1970s and (iii) minimize dependency on weekly import of fission-produced 99Mo raw material required for alumina column generator. The development of column type 99mTc generator based on conversion of (n,?)99Mo as zirconium molybdate-99Mo (ZrM) gel matrix and subsequent separation of 99mTc by elution in normal saline was an important development in this direction, as this combines the advantages of using (n,?)99Mo and a column based separation technique. A considerable volume of work was carried out at the Board of Radiation and Isotope Technology (BRIT) both independently and as a part of IAEA’s CRP [4,9] for standardization of the process. After successful completion of feasibility studies and small scale production and supply of gel generators to local hospitals, development of technology for regular production and supply was undertaken. A multidisciplinary core team comprising of chemists and engineers working in close collaboration enabled successful completion of the project. The technology development entailed four major aspects: (i) adaptation of chemical process to automation, (ii) design and erection of a production facility with adequate shielding, (iii) design/fabrication/installation of operation specific gadgets, and (iv) design of a compact, portable, easy to assemble and reusable generator assembly. The production facility, having a capacity to produce up to 25 generators per batch in an 8 hour shift operation, has been operational since the past five years. We report here the salient aspects of technology development and operational experience of producing the gel generators thereby demonstrating the viability of the technology

  10. Gel―casting of Fine Zirconia Using DMAA Gel System

    Directory of Open Access Journals (Sweden)

    XU Hai-Xian, QIU Tai, YANG Jian, GUO Jian

    2011-10-01

    Full Text Available In order to reduce the toxicity of gelcasting with traditional AM/MBAM Gel system and Prepare high properties green bodies and ceramics. Gelation process of low―toxic DMAA /MBAM system as well as the effect of pH and NH4PMAA on rheological behaviors of slurries were studied. The perfect green bodies and ceramics were prepared using high solid loading slurries with low viscosity and low―toxicity. The solid loading of slurries can be up to 56vol%. The green bodies are surface―smooth without cracking or exfoliation and their bending strength can reach 30MPa. The pore size distribution of the green bodies is single peaked. The mean bending strength of sintered ceramics is 960MPa and the fracture toughness can reach 17.3MPa.m1/2. The zirconia ceramics have good homogeneity and well dense structure, consisting of more tetragonal ZrO2 phase.

  11. Gels from soft hairy nanoparticles in polymeric matrices

    Science.gov (United States)

    Vlassopoulos, Dimitris

    2013-03-01

    Hairy particles represent a huge class of soft colloids with tunable interactions and properties. Advances in synthetic chemistry have enabled obtaining well-characterized such systems for specific needs. In this talk we present two model hairy soft particles with diameters of the order of tens of nanometers, star polymers and polymerically grafted spherical particles. In particular, we discuss design strategies for dispersing them in polymeric matrices and eventually creating and breaking gels. Control parameters are the matrix molar mass, the grafting density (or functionality) and the size of the grafts (or arms). The linear viscoelastic properties and slow time evolution of the gels are examined in view of the existing knowledge from colloidal gels consisting of micron-sized particles, and compared. In the case of stars we start from a concentrated glassy suspension in molecular solvent and add homopolymer at increasing concentration, and as a result of the induced osmotic pressure the stars shrink and a depletion gel is formed. For the grafted colloidal particles, they are added at low concentration to a polymer matrix, and it has been shown that under certain conditions the anisotropy of interactions gives rise to network formation. We then focus on the nonlinear rheological response and in particular the effect of shear flow in inducing a solid to liquid transition. Our studies show that the yielding process is gradual and shares many common features with that of flocculated colloidal suspensions, irrespectively of the shape of the building block of the gel. Whereas shear can melt such a gel, it cannot break it into its constituent blocks and hence fully disperse the hairy nanoparticles. On the other hand, the hairy particles are intrinsically hybrid. We show how this important feature is reflected on the heating of the gels. In that case, the mismatch of thermal expansion coefficients of core and shell appears to play a role on the particle response as it imposes and internal strain on the particle, which in turn changes the shell conformation and under some conditions can lead to thermal melting of the gel. These alternative avenues for manipulating the gel-to-liquid transition have potential implications in directing the properties of hairy nanoparticles and their assemblies in viscoelastic matrices. Parts of this work reflect collaboration with D. Truzzolillo (FORTH), J. F. Moll and S. K.Kumar (Columbia). R. H. Colby (Penn State), M. Gauthier (Waterloo) and B. C. Benicewicz (Univ. South Carolina).

  12. To gel or not to gel: correlating molecular gelation with solvent parameters.

    Science.gov (United States)

    Lan, Y; Corradini, M G; Weiss, R G; Raghavan, S R; Rogers, M A

    2015-10-01

    Rational design of small molecular gelators is an elusive and herculean task, despite the rapidly growing body of literature devoted to such gels over the past decade. The process of self-assembly, in molecular gels, is intricate and must balance parameters influencing solubility and those contrasting forces that govern epitaxial growth into axially symmetric elongated aggregates. Although the gelator-gelator interactions are of paramount importance in understanding gelation, the solvent-gelator specific (i.e., H-bonding) and nonspecific (dipole-dipole, dipole-induced and instantaneous dipole induced forces) intermolecular interactions are equally important. Solvent properties mediate the self-assembly of molecular gelators into their self-assembled fibrillar networks. Herein, solubility parameters of solvents, ranging from partition coefficients (log?P), to Henry's law constants (HLC), to solvatochromic parameters (ET(30)), and Kamlet-Taft parameters (?, ? and ?), and to Hansen solubility parameters (?p, ?d, ?h), are correlated with the gelation ability of numerous classes of molecular gelators. Advanced solvent clustering techniques have led to the development of a priori tools that can identify the solvents that will be gelled and not gelled by molecular gelators. These tools will greatly aid in the development of novel gelators without solely relying on serendipitous discoveries. These tools illustrate that the quest for the universal gelator should be left in the hands of Don Quixote and as researchers we must focus on identifying gelators capable of gelling classes of solvents as there is likely no one gelator capable of gelling all solvents. PMID:25941907

  13. Performance Evaluation and Experimental Studies on Metallised Gel Propellants

    Directory of Open Access Journals (Sweden)

    T. L. Varghese

    1999-01-01

    Full Text Available Metallised gel propellants offer higher specific impulse and volumetric loading, reduced vaporisation loss, spillage and slosh problems and easy storage in comparison to the conventional liquid propellants. Theoretical performance analysis of gel propellant containing Al in unsymmetrical dimethyl hydrazine-dinitrogen tetroxide (UDMH-N/sub 2/O/sub 4} system shows peak Isp (vacuum condition of 316.7 s and 318.3 s at oxidiser/fuel (O/f ratios of 1.5 and 1.0, respectively for 30 per cent and 40 per cent UDMH-Al gel propellants, under standard conditions. The effect of other parameters like area ratio and chamber pressure on performance has been brought out in view of mission oriented applications. Aluminium has been found to be a better choice over magnesium in metallised gel propellants. Experimental studies on UDMH gellation using propellant grade (15 micrometerand pyrotechnic grade (1.5 micrometerAl in 500g batch level show that gellant(methyl cellulose concentration could be reduced by 50 percent using pyrotechnic grade Al. The pseudoplastic-thixotropic behaviour, flow rate through die holes, burst pressure tests and bulk density are studied. UDMH -25 to 30 per cent Al gels with both grades of Al are found to be stable, pseudoplastic (shear thinning and thixotropic (time-dependent shear thinning, but their flow pattern through die holes differ in nature.

  14. Antimicrobial effect of Melaleuca alternifolia dental gel in orthodontic patients.

    Science.gov (United States)

    Santamaria, Milton; Petermann, Klodyne Dayana; Vedovello, Silvia Amélia Scudeler; Degan, Viviane; Lucato, Adriana; Franzini, Cristina Maria

    2014-02-01

    The aim of this study was to evaluate the antimicrobial effect and sensorial analysis of the gel developed with the essential oil of Melaleuca alternifolia. Thirty-four volunteers, divided into 2 groups, were monitored for 4 weeks. Initially, clinical biofilm (plaque index) and saliva samples (bacteria count) were collected, from which the standard values for each patient were obtained. For 7 days, group 1 used the melaleuca gel (Petite Marie/All Chemistry, São Paulo, Brazil), and group 2 used Colgate Total (S.B. Campo, São Paulo, Brazil). After 7 days, the plaque index was performed again, as well as the bacteria count and the sensorial analysis (appearance, color, odor, brightness, viscosity, and first taste sensation). The volunteers were instructed to return to their usual dental hygiene habits for 15 days. After this, group 1 started using Colgate Total, and group 2 started using the melaleuca gel, with the same evaluation procedures as the first week. The data were analyzed statistically with a significance level of 5%. In the bacteria count and clinical disclosure, the melaleuca gel was more effective in decreasing the dental biofilm and the numbers of bacteria colonies. According to the data from the sensory evaluation, Colgate Total (the control) showed better results regarding flavor and first sensation (P melaleuca gel is efficient in bacteria control but needs improvement in taste and first sensation. PMID:24485734

  15. Comparative gel-based phosphoproteomics in response to signaling molecules

    KAUST Repository

    Marondedze, Claudius

    2013-09-03

    The gel-based proteomics approach is a valuable technique for studying the characteristics of proteins. This technique has diverse applications ranging from analysis of a single protein to the study of the total cellular proteins. Further, protein quality and to some extent distribution can be first assessed by means of one-dimensional gel electrophoresis and then more informatively, for comparative analysis, using the two-dimensional gel electrophoresis technique. Here, we describe how to take advantage of the availability of fluorescent dyes to stain for a selective class of proteins on the same gel for the detection of both phospho- and total proteomes. This enables the co-detection of phosphoproteins as well as total proteins from the same gel and is accomplished by utilizing two different fluorescent stains, the ProQ-Diamond, which stains only phosphorylated proteins, and Sypro Ruby, which stains the entire subset of proteins. This workflow can be applied to gain insights into the regulatory mechanisms induced by signaling molecules such as cyclic nucleotides through the quantification and subsequent identification of responsive phospho- and total proteins. © Springer Science+Business Media New York 2013.

  16. Preparation of silica by sol-gel method using formamide

    Directory of Open Access Journals (Sweden)

    Lenza R.F.S.

    2001-01-01

    Full Text Available In this work we obtained microporous and mesoporous silica gels by sol-gel processing. Tetraethylortosilicate (TEOS was used as precursor. Nitric acid and hydrofluoric acid were used as catalysts. In order to study the affect of formamide as drying additive, we used a molar ratio alkoxide/formamide of 1/1. The performance of formamide in obtaining crack-free gels was evaluated through monolithicity measurements. The structural evolution occurring in the interconnected network of the gels during thermal treatment was monitored by Fourier transform infrared spectroscopy (FTIR, shrinkage and density measurements and nitrogen gas sorption. We noted that in the presence of formamide, the Si-O-Si bonds are stronger and belong to a more cross-linked structure. The samples obtained in the presence of formamide have larger pore volume and its pore structure is in the range of mesoporosity. The samples obtained without additive are microporous. Formamide allowed the preparation of crack-free silica gels stabilized at high temperatures.

  17. Preparation of silica by sol-gel method using formamide

    Scientific Electronic Library Online (English)

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

    2001-07-01

    Full Text Available In this work we obtained microporous and mesoporous silica gels by sol-gel processing. Tetraethylortosilicate (TEOS) was used as precursor. Nitric acid and hydrofluoric acid were used as catalysts. In order to study the affect of formamide as drying additive, we used a molar ratio alkoxide/formamide [...] of 1/1. The performance of formamide in obtaining crack-free gels was evaluated through monolithicity measurements. The structural evolution occurring in the interconnected network of the gels during thermal treatment was monitored by Fourier transform infrared spectroscopy (FTIR), shrinkage and density measurements and nitrogen gas sorption. We noted that in the presence of formamide, the Si-O-Si bonds are stronger and belong to a more cross-linked structure. The samples obtained in the presence of formamide have larger pore volume and its pore structure is in the range of mesoporosity. The samples obtained without additive are microporous. Formamide allowed the preparation of crack-free silica gels stabilized at high temperatures.

  18. Uptake and Recovery of Lead by Agarose Gel Polymers

    Directory of Open Access Journals (Sweden)

    Anurag Pandey

    2009-01-01

    Full Text Available Problem statement: The uptake and recovery of lead ions were investigated by using agarose gel polymers. Approach: The experimental results showed that the agarose gel were effective in removing Pb (II from solution. Biosorption equilibrium was approached within 4 h. Pseudo second-order was applicable to all the sorption data over the entire time range. Results: The sorption data conformed well to both the Langmuir and the Freundlich isotherm model. The maximum adsorption capacity (qmax onto agarose gel was 115 mg g-1 for Pb (II. The maximum uptake of metal ions was obtained at pH 2.0. At temperature 35°C, the biosorption of metal ions was found to be highest, with increase or decrease in temperature resulted in a decrease in the metal ions uptake capacity. Conclusion: Elution experiments were carried out to remove Pb (II ions from loaded agarose gel and the bound metal ions could be eluted successfully using 0.1 M EDTA solution. The results suggest that agarose gel can be used as a biosorbent for an efficient removal of Pb(II ions from aqueous solution.

  19. Detection of ultraviolet radiation using tissue equivalent radiochromic gel materials

    International Nuclear Information System (INIS)

    Ferrous Xylenol-orange Gelatin gel (FXG) is known to be sensitive to ionising radiation such as ? and X-rays. The effect of ionising radiation is to produce an increase in the absorption over a wide region of the visible spectrum, which is proportional to the absorbed dose. This study demonstrates that FXG gel is sensitive to ultraviolet radiation and therefore it could functions as UV detector. Short exposure to UV radiation produces linear increase in absorption measured at 550nm, however high doses of UV cause the ion indicator colour to fad away in a manner proportional to the incident UV energy. Light absorbance increase at the rate of 1.1% per minute of irradiation was monitored. The exposure level at which the detector has linear response is comparable to the natural summer UV radiation. Evaluating the UV ability to pass through tissue equivalent gel materials shows that most of the UV gets absorbed in the first 5mm of the gel materials, which demonstrate the damaging effects of this radiation type on human skin and eyes. It was concluded that FXG gel dosimeter has the potential to offer a simple, passive ultraviolet radiation detector with sensitivity suitable to measure and visualises the natural sunlight UV exposure directly by watching the materials colour changes.

  20. A genipin-gelatin gel dosimeter for radiation processing

    International Nuclear Information System (INIS)

    Genipin, a fruit extract from Gardenia jasminoides Ellis, forms cross-links in solutions of gelatin, to form a blue hydrogel that bleaches quantitatively upon irradiation and the colour change can be measured with a spectrophotometer. With the addition of sulphuric acid this dosimeter is sufficiently sensitive for quality assurance of radiotherapy level dosimetry. Without sulphuric acid the gel has a reduced sensitivity and responds linearly with dose between 100 and 1000 Gy, making it potentially useful as a dosimeter for radiation processing applications such as the phytosanitary irradiation treatment of food. We investigated the dose response characteristics of this new formulation and found that the darker gels are more sensitive to dose and have a reduced uncertainty. - Highlights: ? Genipin is a cross-linker of gelatin, causing a change from colourless to blue. ? Gel bleaches upon irradiation and the colour change can be measured. ? Gel responds linearly with dose between 100 and 1000 Gy. ? Darker gels are more sensitive to dose and have a reduced uncertainty.