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Sample records for ph curing time

  1. Effect of curing Helicobacter pylori infection on intragastric pH during treatment with omeprazole.

    PubMed Central

    Verdú, E F; Armstrong, D; Idström, J P; Labenz, J; Stolte, M; Dorta, G; Börsch, G; Blum, A L

    1995-01-01

    It has been shown that omeprazole treatment produces higher intragastric pH values in Helicobacter pylori positive subjects than in H pylori negative subjects. This study aimed to investigate the effect of curing H pylori on the intragastric pH in both the presence and absence of omeprazole therapy. Twenty four hour intragastric pH recordings were performed before and after a one week course of omeprazole (20 mg once daily) in 18 H pylori positive subjects and were repeated after the infection had been cured. In the absence of omeprazole, the total 24 hour pH values before cure did not differ from those afterwards. During omeprazole treatment the 24 hour pH values were much higher before (median (95% CI) 5.4: 4.3, 6.0), than after cure of infection (3.6: 2.1, 4.4; p < 0.001). The omeprazole induced fall in H+ activity before cure of H pylori did not, however, differ from that afterwards. It is concluded that the apparently greater antisecretory effect of omeprazole during H pylori infection may be a result of the production of acid neutralising compounds by the H pylori. Although a direct interaction between H pylori and omeprazole cannot be excluded, it seems unlikely. PMID:8537042

  2. Temperature and curing time affect composite sorption and solubility

    PubMed Central

    de CASTRO, Fabrício Luscino Alves; CAMPOS, Bruno Barbosa; BRUNO, Kely Firmino; REGES, Rogério Vieira

    2013-01-01

    Objective: This study evaluated the effect of temperature and curing time on composite sorption and solubility. Material and Methods: Seventy five specimens (8x2 mm) were prepared using a commercial composite resin (ICE, SDI). Three temperatures (10º C, 25º C and 60º C) and five curing times (5 s, 10 s, 20 s, 40 s and 60 s) were evaluated. The specimens were weighed on an analytical balance three times: A: before storage (M1); B: 7 days after storage (M2); C: 7 days after storage plus 1 day of drying (M3). The storage solution consisted of 75% alcohol/25% water. Sorption and solubility were calculated using these three weights and specimen dimensions. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U Tests (α=5%). Results: The results showed that time, temperature and their interaction influenced the sorption and solubility of the composite (p<0.05). At 60º C, the composite sorption showed an inverse relationship with the curing time (p<0.05). The composite cured for 5 s showed higher sorption for the 40 s or 60 s curing times when compared with all temperatures (p<0.05). Curing times of 20 s and 40 s showed similar sorption data for all temperatures (p>0.05). The 60º C composite temperature led to lower values of sorption for all curing times when compared with the 10º C temperature (p<0.05). The same results were found when comparing 10º C and 25º C (p<0.05), except that the 20 s and 40 s curing times behaved similarly (p>0.05). Solubility was similar at 40 s and 60 s for all temperatures (p>0.05), but was higher at 10º C than at 60º C for all curing times (p<0.05). When the composite was cured at 25º C, similar solubility values were found when comparing the 5 s and 10 s or 20 s and 40 s curing times (p>0.05). Conclusion: In conclusion, higher temperatures or longer curing times led to lower sorption and solubility values for the composite tested; however, this trend was only significant in specific combinations of temperature and

  3. SureCure ®-A new material to reduces curing time and improve curing reproducibility of lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Boden, David P.; Loosemore, Daniel V.; Botts, G. Dean

    This paper introduces a technology that considerably reduces the time to cure the positive plates of lead-acid batteries. In each of several full-scale trials at automotive and industrial battery manufacturers, the simple replacement of 1 wt.% of leady oxide with finely-divided tetrabasic lead sulfate (SureCure™ by Hammond Group Inc.) is shown to accelerate significantly the conversion of tribasic lead sulfate (3BS) to tetrabasic lead sulfate (4BS) in the curing process while improving crystal structure and reproducibility. Shorter curing times result in reduced labour and energy costs, as well as reduced fixed (curing chambers and plant footprint) and working (plate inventory) capital investment.

  4. Time course of isocyanate emission from curing polyurethane adhesives

    NASA Astrophysics Data System (ADS)

    Wirts, M.; Grunwald, D.; Schulze, D.; Uhde, E.; Salthammer, T.

    The time course of isocyanate emission from curing polyurethane (PUR) resins and adhesives was studied in two different emission test chambers. The measured emissions were strongly dependent on the type of experiment. The adhesives under investigation contained different types of diisocyanates and are used for different applications, e.g. for fixing of textile floor coverings. The influence of the curing mechanism on emission was studied by comparing the emission curves of one-component adhesives (OCA) and two-component adhesives (TCA). For TCA, the decrease in isocyanate emission was found to follow a two-step process during curing. In the first step, the emission is dominated by surface evaporation, and the decay of emission is mainly caused by the decrease in monomer content due to reaction. In the second step, the release is limited by internal diffusion. The influence of monomer reactivity on the emission profile could be demonstrated for 2,4'- and 4,4'-MDI. The less-reactive 2,4'-MDI caused prolonged emission. A strong dependence of emission rates on temperature and adhesive viscosity was also obvious. The evaluation of emission rates of different commercially available PUR adhesives showed the highest emission from systems that are applied at high temperatures. The high reactivity of diisocyanates requires special techniques for sampling and analysis. Therefore, an analytical method using HPLC-MS/MS was developed that enables limits of quantitation of <5 ng/m 3 with a sampling volume of 100 l.

  5. Effects of Ph gene-associated versus induced resistance to tobacco cyst nematode in flue-cured tobacco.

    PubMed

    Parkunan, Venkatesan; Johnson, Charles S; Eisenback, Jon D

    2009-12-01

    Effects of the systemic acquired resistance (SAR)-inducing compound acibenzolar-S-methyl (ASM) and the plant-growth promoting rhizobacterial mixture Bacillus subtilis A13 and B. amyloliquefaciens IN937a (GB99+GB122) were assessed on the reproduction of a tobacco cyst nematode (TCN- Globodera tabacum solanacearum) under greenhouse conditions. Two sets of two independent experiments were conducted, each involving soil or root sampling. Soil sample experiments included flue-cured tobacco cultivars with (Ph(p)+: NC71 and NC102) and without (Ph(p)-: K326 and K346) a gene (Ph(p)) suppressing TCN parasitism. Root sample experiments examined TCN root parasitism of NC71 and K326. Cultivars possessing the Ph(p) gene (Ph(p)+) were compared with Ph(p)- cultivars to assess the effects of resistance mediated via Ph(p) gene vs. induced resistance to TCN. GB99+GB122 consistently reduced nematode reproductive ratio on both Ph(p)+ and Ph(p)- cultivars, but similar effects of ASM across Ph(p)- cultivars were less consistent. In addition, ASM application resulted in leaf yellowing and reduced root weight. GB99+GB122 consistently reduced nematode development in roots of both Ph(p)+ and Ph(p)- cultivars, while similar effects of ASM were frequently less consistent. The results of this study indicate that GB99+GB122 consistently reduced TCN reproduction in all flue-cured tobacco cultivars tested, while the effects of ASM were only consistent in Ph(p)+ cultivars. Under most circumstances, GB99+GB122 suppressed nematode reproduction more consistently than ASM compared to the untreated control. PMID:22736824

  6. Whisker-reinforced heat-cured dental resin composites: effects of filler level and heat-cure temperature and time.

    PubMed

    Xu, H H

    2000-06-01

    Currently available dental resin composites are inadequate for use in large stress-bearing crown and multiple-unit restorations. The aim of this study was to reinforce heat-cured composites with ceramic whiskers. It was hypothesized that whiskers substantially strengthen heat-cured composites. It was further hypothesized that whisker filler level and heat-cure temperature and time significantly influence composite properties. Silica particles were fused onto the whiskers to facilitate silanization and to roughen the whiskers for improved retention in the matrix. The whisker filler mass fraction was varied from 0% to 79%, the heat-cure temperature from 80 degrees C to 180 degrees C, and cure time from 10 min to 24 hrs. Flexural strength, work-of-fracture, and fracture toughness of the composites were measured, and specimen fracture surfaces were examined with scanning electron microscopy. Filler level had a significant effect on composite properties. The whisker composite with 70% filler level had a flexural strength in MPa (mean +/- SD; n = 6) of 248 +/- 23, significantly higher than 120 +/- 16 of an inlay/onlay composite control and 123 +/- 21 of a prosthetic composite control (Tukey's multiple comparison test; family confidence coefficient = 0.95). Heat-cure time also played a significant role. At 120 degrees C, the strength of composite cured for 10 min was 178 +/- 17, lower than 236 +/- 14 of composite cured for 3 hrs. The strength of whisker composite did not degrade after water-aging for 100 d. In conclusion, heat-cured composites were substantially reinforced with whiskers. The reinforcement mechanisms appeared to be whiskers bridging and resisting cracks. The strength and fracture toughness of whisker composite were nearly twice those of currently available inlay/onlay and prosthetic composites. PMID:10890718

  7. Effects of pH, sodium chloride, and curing salt on the infectivity of Toxoplasma gondii tissue cysts.

    PubMed

    Pott, S; Koethe, M; Bangoura, B; Zöller, B; Daugschies, A; Straubinger, R K; Fehlhaber, K; Ludewig, M

    2013-06-01

    Toxoplasma gondii is one of the most common zoonotic parasites in the world. The parasite causes no or mild symptoms in immunocompetent humans. However, a high potential hazard exists for seronegative pregnant women and immunocompromised patients. The consumption of meat containing tissue cysts or oocyst-contaminated vegetables and fruits or the handling of cat feces poses a high risk of infection with T. gondii. It is known that raw minced meat, raw fresh sausages, and locally produced raw meat products are possible causes of T. gondii infection. The infectivity of T. gondii tissue cysts in meat products depends, among other factors, on the pH and the salt concentration. Therefore, the impact of these two factors on the tissue cysts was examined. For this purpose, dissected musculature and brain from experimentally infected mice (donor mice) were placed in a cell culture medium (RPMI 1640). The medium was adjusted to different pH values (pH 5, 6, and 7) with lactic acid and to different salt concentrations (2.0, 2.5, and 3.0%) with sodium chloride (NaCl) or nitrite-enriched curing salt (NCS) for the various tests. After storage at 4°C for different time periods, the materials were fed to bioassay mice. Later, the brains were examined for presence of T. gondii to assess the infectivity. The data show that T. gondii tissue cysts have a high pH tolerance. Cysts were infectious in the muscle for up to 26 days (pH 5). In contrast to their tolerance to pH, cysts were very sensitive to salt. Muscle cysts survived at an NaCl concentration of up to 2.0% only, and for no longer than 8 days. At NaCl concentrations of 2.5 and 3.0%, the cysts lost their infectivity after 1 day. When NCS instead of NaCl was used under the same conditions, T. gondii muscle cysts retained infectivity for only 4 days at 2.0%. Consequently, NCS (NaCl plus 0.5% nitrite) has a stronger effect on T. gondii cysts than does common table salt. Sausages produced with low NaCl concentration and short

  8. Microhardness of composite resin cured through different primary tooth thicknesses with different light intensities and curing times: In vitro study

    PubMed Central

    Mazhari, Fatemeh; Ajami, Behjatolmolok; Moazzami, Saied Mostafa; Baghaee, Bahareh; Hafez, Bahareh

    2016-01-01

    Objective: The aim of this study was to evaluate the effect of increased exposure time and light intensity on microhardness of cured composite through different thicknesses of tooth structure in primary teeth. Materials and Methods: One hundred and seventy cylindrical resin composite specimens were prepared. All specimens were divided into 17 experimental and control groups. “Light-emitting diode” light curing unit (LCU) applied directly or through 1, 2, and 3 mm thicknesses tooth slices for experimental groups. The irradiation protocols were 25 and 50 s at 650 mW/cm2 and 15 and 30 s at 1100 mW/cm2. The “quartz-tungsten-halogen” LCU (400 mW/cm2) for 40 s was used in control group. Microhardness was measured by the Vickers hardness test. Results: Indirectly cured specimens and those cured through a 1 mm thick tooth structure, an increase in intensity caused hardness drop. In the specimens cured through 2 and 3 mm thick tooth structures, increased intensity and/or exposure time did not show any appropriate changes on microhardness. Conclusion: Irradiation through a 1.0 mm thick tooth slice resulted in reduced microhardness although it was still within the clinically acceptable level. The hardness values of the specimens cured through 2 or 3 mm thick tooth slices fell below the clinically acceptable level even after doubling the exposure time and/or light intensity. PMID:27095897

  9. A cure for AIDS: a matter of timing?

    PubMed

    Shytaj, Iart Luca; Savarino, Andrea

    2013-01-01

    Despite the huge clinical success of antiretroviral therapy, several factors such as side effects, requirement of life-long adherence, high cost, incomplete access to therapies and development of drug resistance make the quest for an ultimate cure of HIV/AIDS a worldwide priority of biomedical research. In this respect, several sterilizing or functional cures have been reported in the last years in both non-human primates and humans. This review provides a summary of the main results achieved so far, outlining their strengths as well as their limitations. A synthetic interpretation of these results could be pivotal in order to develop an effective and widely available cure. PMID:24267982

  10. The pH effect of solvent in silanization on fluoride released and mechanical properties of heat-cured acrylic resin containing fluoride-releasing filler.

    PubMed

    Nakornchai, Natha; Arksornnukit, Mansuang; Kamonkhantikul, Krid; Takahashi, Hidekazu

    2016-01-01

    This study aimed to evaluate the effect of an acidic-adjusted pH of solvent in silanization on the amount of fluoride released and mechanical properties of heat-cured acrylic resin containing a silanized fluoride-releasing filler. The experimental groups were divided into 4 groups; non-silanized, acidic-adjusted pH, non-adjusted pH, and no filler as control. For fluoride measurement, each specimen was placed in deionized water which was changed every day for 7 days, every week for 7 weeks and measured. The flexural strength and flexural modulus were evaluated after aging for 48 h, 1, and 2 months. Two-way ANOVA indicated significant differences among groups, storage times, and its interaction in fluoride measurement and flexural modulus. For flexural strength, there was significant difference only among groups. Acidic-adjusted pH of solvent in silanization enhanced the amount of fluoride released from acrylic resin, while non-adjusted pH of solvent exhibited better flexural strength of acrylic resin. PMID:27252000

  11. Optical and Thermal Analysis of the Time Evolution of Curing in Resins by Photothermal Techniques

    NASA Astrophysics Data System (ADS)

    Martínez-Torres, P.; Zambrano-Arjona, M.; Aguilar, G.; Alvarado-Gil, J. J.

    2012-11-01

    Four shades of a commercial visible-light curing dental resin are analyzed using photothermal techniques. The thermal effusivities of the dental resin shades before curing are measured using a variant of the conventional photoacoustic technique. The thermal diffusivities before and after curing are measured using infrared photothermal radiometry in the forward emission configuration. The time evolution process of the photocuring resin is monitored by photothermal radiometry in the forward and backward emission configurations. Inversion of the time evolution signal of the different configurations used permits one to obtain the time evolution of the thermal and optical properties during the photocuring. The thermal effusivity and thermal diffusivity exhibit exponential growth, while the optical absorption decreases exponentially due to the curing process. The relationship of these phenomena with the decrease of monomer concentration induced by the curing is discussed.

  12. Effect of post cure time and temperature on the properties of two phenolic-fiber composites

    NASA Technical Reports Server (NTRS)

    Lucy, M. H.; Price, H. L.

    1975-01-01

    Some effects of post-cure time and temperature on the physicomechanical properties of a phenolic-asbestos and a phenolic-glass composite are studied. The molding and post-curing procedures are discussed along with physical and mechanical test results. It is found that the specific gravity of the panels tested decreased slightly but the hardness always increased with post cure, and that the mechanical properties had different patterns of response to increasing post-cure time and temperature. For tensile properties, strength decreased, modulus increased, and elongation at break exhibited little change. In general, the phenolic-asbestos showed more positive response to post cure than did the phenolic-glass. Mold venting is found to impart better properties to the composites concerned.

  13. Effect of pH on the rate of curing and bioadhesive properties of dopamine functionalized poly(ethylene glycol) hydrogels.

    PubMed

    Cencer, Morgan; Liu, Yuan; Winter, Audra; Murley, Meridith; Meng, Hao; Lee, Bruce P

    2014-08-11

    The remarkable underwater adhesion strategy employed by mussels has inspired bioadhesives that have demonstrated promise in connective tissue repair, wound closure, and local delivery of therapeutic cells and drugs. While the pH of oxygenated blood and internal tissues is typically around 7.4, skin and tumor tissues are significantly more acidic. Additionally, blood loss during surgery and ischemia can lead to dysoxia, which lowers pH levels of internal tissues and organs. Using 4-armed PEG end-capped with dopamine (PEG-D) as a model adhesive polymer, the effect of pH on the rate of intermolecular cross-linking and adhesion to biological substrates of catechol-containing adhesives was determined. Adhesive formulated at an acidic pH (pH 5.7-6.7) demonstrated reduced curing rate, mechanical properties, and adhesive performance to pericardium tissues. Although a faster curing rate was observed at pH 8, these adhesives also demonstrated reduced mechanical and bioadhesive properties when compared to adhesives buffered at pH 7.4. Adhesives formulated at pH 7.4 demonstrated a good balance of fast curing rate, elevated mechanical properties and interfacial binding ability. UV-vis spectroscopy evaluation revealed that the stability of the transient oxidation intermediate of dopamine was increased under acidic conditions, which likely reduced the rate of intermolecular cross-linking and bulk cohesive properties for hydrogels formulated at these pH levels. At pH 8, competing cross-linking reaction mechanisms and reduced concentration of dopamine catechol due to auto-oxidation likely reduced the degree of dopamine polymerization and adhesive strength for these hydrogels. pH plays an important role in the adhesive performance of mussel-inspired bioadhesives and the pH of the adhesive formulation needs to be adjusted for the intended application. PMID:25010812

  14. Stability of α-tocotrienol and α-tocopherol in salami-type sausages and curing brine depending on nitrite and pH.

    PubMed

    Gerling, Eva-Maria; Ternes, Waldemar

    2014-12-01

    We studied the stability of the valuable vitamer nutrients α-tocotrienol and α-tocopherol and options for their protection in salami-type sausages (blended with α-tocotrienol-rich barley oil) and curing brine. Four different sausage formulations were produced containing nitrite curing salt; nitrite curing salt and ascorbic acid (300mg/kg); nitrite curing salt and carnosic acid (45mg/kg); or sodium chloride. Initial vitamer contents (100mg/kg) did not decrease significantly during ripening and decreased only slightly during storage. Ascorbic acid and carnosic acid were found to be effective in preserving the vitamers in fresh sausages. Freeze-drying of sausages resulted in a significant loss of vitamers (97%), particularly after 14-day storage at room temperature, even in the presence of shielding gases. The vitamer content in the curing brine decreased with decreasing pH in the presence of nitrite. A nitrite concentration of 136mg/L at pH4 resulted in significant loss (90%) of the vitamers. Sufficient stability of the vitamers in salami-type sausage and curing brine can be achieved by processing, formulation, and storage conditions. PMID:25089791

  15. Racial and Ethnic Disparities in Time to Cure of Incontinence Present at Nursing Home Admission

    PubMed Central

    Bliss, Donna Z.; Gurvich, Olga; Savik, Kay; Eberly, Lynn E.; Harms, Susan; Wyman, Jean F.

    2015-01-01

    As many as half of older people that are admitted to nursing homes (NHs) are incontinent of urine and/or feces. Not much is known about the rate of cure of incontinence present at NH admission, but available reports suggest the rate is low. There have been racial and ethnic disparities in incontinence treatment, but the role of disparities in the cure of incontinence is understudied. Using the Peters-Belson method and multilevel predictors, our findings showed that there were disparities in the time to cure of incontinence for Hispanic NH admissions. A significantly smaller proportion of older Hispanic admissions were observed to have their incontinence cured and cured later than expected had they been White. Reducing disparities in incontinence cure will improve health outcomes of Hispanic NH admissions. Significant predictors in our model suggest strategies to reduce the disparity including attention to managing fecal incontinence and incontinence in those with cognitive impairment, improving residents’ functional status, and increasing resources to NHs admitting older Hispanics with incontinence to develop innovative and cost effective ways to provide equitable quality care. PMID:26295010

  16. Compressive strength development of concrete with different curing time and temperature

    SciTech Connect

    Kim, J.K.; Moon, Y.H.; Eo, S.H.

    1998-12-01

    In this experimental and analytic research, the strength development for various curing histories was investigated with particular regard to the influences of curing time points with given temperatures. For this purpose, four different points of curing time were considered with an individual interval of 24 h. Two different temperatures of 5 C and 40 C were applied for the selective intervals, whereas the rest period days were under the reference curing condition of 20 C. A new model for the strength prediction was suggested based on the rate constant model. In this model, the equivalent ages introduced in the Saul and Arrhenius models were modified to show the effects of curing temperature at different ages. Test results show that the concrete subjected to a high temperature at an early age attains higher early-age strength but eventually attains lower later-age strength. The concrete subjected to a low temperature at an early age leads to lower early-age strength but almost the same later-age strength. Moreover, the proposed model showed better agreement with the test results than the existing models.

  17. Shear bond strength of orthodontic color-change adhesives with different light-curing times

    PubMed Central

    Bayani, Shahin; Ghassemi, Amirreza; Manafi, Safa; Delavarian, Mohadeseh

    2015-01-01

    Background: The purpose of this study was to evaluate the effect of light-curing time on the shear bond strength (SBS) of two orthodontic color-change adhesives (CCAs). Materials and Methods: A total of 72 extracted premolars were randomly assigned into 6 groups of 12 teeth each. Subsequent to primer application, a metal bracket was bonded to the buccal surface using an orthodontic adhesive. Two CCAs (Greengloo and Transbond Plus) were tested and one conventional light-cured adhesive (Resilience) served as control. For each adhesive, the specimens were light-cured for two different times of 20 and 40 s. All the specimens underwent mechanical testing using a universal testing machine to measure the SBS. Adhesive remnant index (ARI) was used to assess the remnant adhesive material on the tooth surface. All statistical analyses were performed using SPSS software. The significance level for all statistical tests was set at P ≤ 0.05. Results: The SBSs of the tested groups were in the range of 14.05-31.25 MPa. Greengloo adhesive showed the highest SBS values when light-cured for 40 s, and Transbond Plus adhesive showed the lowest values when light-cured for 20 s. ARI scores of Transbond Plus adhesive were significantly higher than those of controls, while other differences in ARI values were not significant. Conclusion: Within the limitations of his study, decreasing the light-curing time from 40 to 20 s decreased the SBS of the tested adhesives; however, this decline in SBS was statistically significant only in Transbond Plus adhesive PMID:26005468

  18. More Part-Time Work as a Cure for Unemployment? Results of an International Comparison.

    ERIC Educational Resources Information Center

    Walwei, Ulrich; Werner, Heinz

    1996-01-01

    The feasibility of policies encouraging more part-time employment as a cure for unemployment in Germany was examined through a comparison of the employment policies and labor markets of selected Organization for Economic Development (OECD) countries and the United States. OECD labor force statistics for the years 1972-1992 were analyzed to…

  19. Effects of Light Curing Method and Exposure Time on Mechanical Properties of Resin Based Dental Materials

    PubMed Central

    Alpöz, A. Riza; Ertuḡrul, Fahinur; Cogulu, Dilsah; Ak, Asli Topaloḡlu; Tanoḡlu, Metin; Kaya, Elçin

    2008-01-01

    Objectives The aim of this study was to investigate microhardness and compressive strength of composite resin (Tetric-Ceram, Ivoclar Vivadent), compomer (Compoglass, Ivoclar, Vivadent), and resin modified glass ionomer cement (Fuji II LC, GC Corp) polymerized using halogen light (Optilux 501, Demetron, Kerr) and LED (Bluephase C5, Ivoclar Vivadent) for different curing times. Methods Samples were placed in disc shaped plastic molds with uniform size of 5 mm diameter and 2 mm in thickness for surface microhardness test and placed in a diameter of 4 mm and a length of 2 mm teflon cylinders for compressive strength test. For each subgroup, 20 samples for microhardness (n=180) and 5 samples for compressive strength were prepared (n=45). In group 1, samples were polymerized using halogen light source for 40 seconds; in group 2 and 3 samples were polymerized using LED light source for 20 seconds and 40 seconds respectively. All data were analyzed by two way analysis of ANOVA and Tukey’s post-hoc tests. Results Same exposure time of 40 seconds with a low intensity LED was found similar or more efficient than a high intensity halogen light unit (P>.05), however application of LED for 20 seconds was found less efficient than 40 seconds curing time (P=.03). Conclusions It is important to increase the light curing time and use appropriate light curing devices to polymerize resin composite in deep cavities to maximize the hardness and compressive strength of restorative materials. PMID:19212507

  20. Titin-derived peptides as processing time markers in dry-cured ham.

    PubMed

    Gallego, Marta; Mora, Leticia; Aristoy, M Concepción; Toldrá, Fidel

    2015-01-15

    The complex proteolysis in Spanish dry-cured ham processing generates large amounts of small peptides and free amino acids which are responsible for the characteristic texture and flavour of this traditional product. The aim of this work was to study the degradation of the giant protein titin throughout the dry-curing process (2, 3.5, 5, 6.5, and 9 months) through the use of proteomic tools. A total of 320 peptides have been identified by nanoliquid chromatography coupled to tandem mass spectrometry, being some of them identified only at 9 months of processing. In order to confirm the absence of these peptides at other times of processing, MALDI-TOF MS was also employed as a fast and easier technique. Only four peptides, KDEAAKPKGPIKGVAKK, KKLRPGSGGEK, KNTDKWSECAR and ISIDEGKVL, were exclusively identified at 9 months of curing by using both methodologies so that these peptides could be used as potential biomarkers of dry-cured ham processing time. PMID:25148995

  1. [Methods Used for Monitoring Cure Reactions in Real-time in an Autoclave

    NASA Technical Reports Server (NTRS)

    Cooper, John B.; Wise, Kent L.; Jensen, Brian J. (Technical Monitor)

    2000-01-01

    The goal of the research was to investigate methods for monitoring cure reactions in real-time in an autoclave. This is of particular importance to NASA Langley Research Center because polyimides were proposed for use in the High Speed Civil Transport (HSCT) program. Understanding the cure chemistry behind the polyimides would allow for intelligent processing of the composites made from their use. This work has led to two publications in peer-reviewed journals and a patent. The journal articles are listed as Appendix A which is on the instrument design of the research and Appendix B which is on the cure chemistry. Also, a patent has been awarded for the instrumental design developed under this grant which is given as Appendix C. There has been a significant amount of research directed at developing methods for monitoring cure reactions in real-time within the autoclave. The various research efforts can be categorized as methods providing either direct chemical bonding information or methods that provide indirect chemical bonding information. Methods falling into the latter category are fluorescence, dielectric loss, ultrasonic and similar type methods. Correlation of such measurements with the underlying chemistry is often quite difficult since these techniques do not allow monitoring of the curing chemistry which is ultimately responsible for material properties. Direct methods such as vibrational spectroscopy, however, can often be easily correlated with the underlying chemistry of a reaction. Such methods include Raman spectroscopy, mid-IR absorbance, and near-IR absorbance. With the recent advances in fiber-optics, these spectroscopic techniques can be applied to remote on-line monitoring.

  2. Effect of UV curing time on physical and electrical properties and reliability of low dielectric constant materials

    SciTech Connect

    Kao, Kai-Chieh; Cheng, Yi-Lung; Chang, Wei-Yuan; Chang, Yu-Min; Leu, Jihperng

    2014-11-01

    This study comprehensively investigates the effect of ultraviolet (UV) curing time on the physical, electrical, and reliability characteristics of porous low-k materials. Following UV irradiation for various periods, the depth profiles of the chemical composition in the low-k dielectrics were homogeneous. Initially, the UV curing process preferentially removed porogen-related CH{sub x} groups and then modified Si-CH{sub 3} and cage Si-O bonds to form network Si-O bonds. The lowest dielectric constant (k value) was thus obtained at a UV curing time of 300 s. Additionally, UV irradiation made porogen-based low-k materials hydrophobic and to an extent that increased with UV curing time. With a short curing time (<300 s), porogen was not completely removed and the residues degraded reliability performance. A long curing time (>300 s) was associated with improved mechanical strength, electrical performance, and reliability of the low-k materials, but none of these increased linearly with UV curing time. Therefore, UV curing is necessary, but the process time must be optimized for porous low-k materials on back-end of line integration in 45 nm or below technology nodes.

  3. Ballistics ordnance gelatine - How different concentrations, temperatures and curing times affect calibration results.

    PubMed

    Maiden, Nicholas R; Fisk, Wesley; Wachsberger, Christian; Byard, Roger W

    2015-08-01

    A study was undertaken to determine whether different concentrations of ordnance gelatine, water types, temperatures and curing times would have an effect on projectile penetration of a gelatine tissue surrogate. Both Federal Bureau of Investigation (FBI) and North Atlantic Treaty Organization (NATO) specified gelatines were compared against the FBI calibration standard. 10% w/w and 20% w/w concentrations of gelatine with Bloom numbers of 250 and 285 were prepared and cured at variable temperatures (3-20°C) for 21 hours-3 weeks. Each block was shot on four occasions on the same range using steel calibre 4.5 mm BBs fired from a Daisy(®) air rifle at the required standard velocity of 180 ± 4.5 m/s, to ascertain the mean penetration depth. The results showed no significant difference in mean penetration depth using the three different water types (p > 0.05). Temperature changes and curing times did affect penetration depth. At 10°C, mean penetration depth with 20% gelatine 285 Bloom for the two water types tested was 49.7 ± 1.5 mm after 21 h curing time, whereas the same formulation at 20°C using two different water types was 79.1 ± 2.1 mm after 100 h curing time (p < 0.001). Neither of the NATO 20% concentrations of gelatine at 10°C or a 20% concentration of 285 Bloom gelatine at 10°C met the same calibration standard as the FBI recommended 10% formulation at 4°C. A 20% concentration of 285 Bloom at 20°C met the same calibration/penetration criteria as a 10% concentration of 250 Bloom at 4 °C after 100 h of curing, therefore matching the FBI calibration standard for a soft tissue simulant for wound ballistics research. These results demonstrate significant variability in simulant properties. Failure to standardise ballistic simulants may invalidate experimental results. PMID:26165674

  4. Ultraviolet blood irradiation: Is it time to remember "the cure that time forgot"?

    PubMed

    Wu, Ximing; Hu, Xiaoqing; Hamblin, Michael R

    2016-04-01

    Ultraviolet blood irradiation (UBI) was extensively used in the 1940s and 1950s to treat many diseases including septicemia, pneumonia, tuberculosis, arthritis, asthma, and even poliomyelitis. The early studies were carried out by several physicians in USA and published in the American Journal of Surgery. However, with the development of antibiotics, the use of UBI declined and it has now been called "the cure that time forgot." Later studies were mostly performed by Russian workers, and in other Eastern countries, and the modern view in Western countries is that UBI remains highly controversial. This review discusses the potential of UBI as an alternative approach to current methods used to treat infections, as an immune-modulating therapy and as a method for normalizing blood parameters. Low and mild doses of UV kill microorganisms by damaging the DNA, while any DNA damage in host cells can be rapidly repaired by DNA repair enzymes. However, the use of UBI to treat septicemia cannot be solely due to UV-mediated killing of bacteria in the bloodstream, as only 5-7% of blood volume needs to be treated with UV to produce the optimum benefit, and higher doses can be damaging. There may be some similarities to extracorporeal photopheresis (ECP) using psoralens and UVA irradiation. However, there are differences between UBI and ECP in that UBI tends to stimulate the immune system, while ECP tends to be immunosuppressive. With the recent emergence of bacteria that are resistant to all known antibiotics, UBI should be more investigated as an alternative approach to infections, and as an immune-modulating therapy. PMID:26894849

  5. Sample size calculation for the proportional hazards cure model.

    PubMed

    Wang, Songfeng; Zhang, Jiajia; Lu, Wenbin

    2012-12-20

    In clinical trials with time-to-event endpoints, it is not uncommon to see a significant proportion of patients being cured (or long-term survivors), such as trials for the non-Hodgkins lymphoma disease. The popularly used sample size formula derived under the proportional hazards (PH) model may not be proper to design a survival trial with a cure fraction, because the PH model assumption may be violated. To account for a cure fraction, the PH cure model is widely used in practice, where a PH model is used for survival times of uncured patients and a logistic distribution is used for the probability of patients being cured. In this paper, we develop a sample size formula on the basis of the PH cure model by investigating the asymptotic distributions of the standard weighted log-rank statistics under the null and local alternative hypotheses. The derived sample size formula under the PH cure model is more flexible because it can be used to test the differences in the short-term survival and/or cure fraction. Furthermore, we also investigate as numerical examples the impacts of accrual methods and durations of accrual and follow-up periods on sample size calculation. The results show that ignoring the cure rate in sample size calculation can lead to either underpowered or overpowered studies. We evaluate the performance of the proposed formula by simulation studies and provide an example to illustrate its application with the use of data from a melanoma trial. PMID:22786805

  6. Time course of pH change in plant epidermis using microscopic pH imaging system

    NASA Astrophysics Data System (ADS)

    Dan, Risako; Shimizu, Megumi; Kazama, Haruko; Sakaue, Hirotaka

    2010-11-01

    We established a microscopic pH imaging system to track the time course of pH change in plant epidermis in vivo. In the previous research, we have found out that anthocyanin containing cells have higher pH. However, it was not clear whether the anthocyanin increased the pH or anthocyanin was synthesized result from the higher pH. Therefore, we further investigated the relationship between anthocyanin and pH change. To track the time course of pH change in plant epidermis, we established a system using luminescent imaging technique. We used HPTS (8-Hydroxypyrene-1,3,6-Trisulfonate) as pH indicator and applied excitation ratio imaging method. Luminescent image was converted to a pH distribution by obtained in vitro calibration using known pH solution. Cellular level observation was enabled by merging microscopic color picture of the same region to the pH change image. The established system was applied to epidermal cells of red-tip leaf lettuce, Lactuca Sativa L. and the time course was tracked in the growth process. We would discuss about the relationship between anthocyanin and pH change in plant epidermis.

  7. Dependence of curing time, peak temperature, and mechanical properties on the composition of bone cement.

    PubMed

    Brauer, G M; Steinberger, D R; Stansbury, J W

    1986-01-01

    Commercial bone cements usually contain hydroquinone as the polymerization inhibitor and N,N-dimethyl-p-toluidine as the accelerator in the benzoyl peroxide-initiated redox polymerization. The former compounds have certain shortcomings in their biocompatibility profile. Measurements of the setting times, polymerization exotherms, and postpolymerization strengths of the cured monomer-polymer compositions show that the hydroquinone can be replaced by food grade di-tert-butyl-p-cresol (BHT). The more reactive 4-N,N-(dimethylamino)phenethanol can replace 4-N,N-dimethyl-p-toluidine, yielding cements with shorter setting times and increased strengths. Excessive heat liberated on polymerization can be reduced by partial substitution of higher-molecular-weight methacrylates, e.g., dicyclopentenyloxyethyl methacrylate for methyl methacrylate, but there is a decrease in strength of the resulting polymer. More successful has been the addition to the monomer of 1% or 2% of the chain transfer agent pentaerythritol tetra(3-mercaptopropionate), which lowers the peak temperature without changing the physical properties of the cement. Compositions with short curing times, lower exotherms, and mechanical properties that exceed those of a commercial material have been formulated. PMID:3722218

  8. Effects of curing time and frequency on ultrasonic wave velocity in grouted rock bolts

    NASA Astrophysics Data System (ADS)

    Madenga, V.; Zou, D. H.; Zhang, C.

    2006-05-01

    Grouted rock bolts are widely used to reinforce excavated ground in mining and civil engineering structures. To date, opportunities for testing the quality of the grout in grouted rock bolts have been limited to the pull-out tests and the over-coring methods. Both these methods are destructive, time-consuming and costly. These deficiencies have fueled research into the use of ultrasonic methods for testing the quality of the grout in rock bolts. However, only partial success has been achieved in these efforts chiefly due to inadequate knowledge of the ultrasonic wave characteristics such as wave velocity in grouted rock bolts. This paper presents results of an experimental study into the effects of curing time and testing frequency on the velocity of ultrasonic waves propagating along rock bolts grouted in concrete. A substantial wave velocity decrease, as much as 47.7% at certain frequencies, was recorded in rock bolts grouted in fully cured concrete in comparison to non-grouted bolts. The results demonstrate the importance of optimizing the selection of test frequencies as well as suggesting the possibility of a new approach based on wave velocity decrease for testing the grout quality of rock bolts.

  9. Temperature Rise Induced by Light Curing Unit Can Shorten Enamel Acid-Etching Time

    PubMed Central

    Najafi Abrandabadi, Ahmad; Sheikh-Al-Eslamian, Seyedeh Mahsa; Panahandeh, Narges

    2015-01-01

    Objectives: The aim of this in-vitro study was to assess the thermal effect of light emitting diode (LED) light curing unit on the enamel etching time. Materials and Methods: Three treatment groups with 15 enamel specimens each were used in this study: G1: Fifteen seconds of etching, G2: Five seconds of etching, G3: Five seconds of etching plus LED light irradiation (simultaneously). The micro shear bond strength (μSBS) of composite resin to enamel was measured. Results: The mean μSBS values ± standard deviation were 51.28±2.35, 40.47±2.75 and 50.00±2.59 MPa in groups 1, 2 and 3, respectively. There was a significant difference between groups 1 and 2 (P=0.013) and between groups 2 and 3 (P=0.032) in this respect, while there was no difference between groups 1 and 3 (P=0.932). Conclusion: Simultaneous application of phosphoric acid gel over enamel surface and light irradiation using a LED light curing unit decreased enamel etching time to five seconds without compromising the μSBS. PMID:27559352

  10. Effect of curing time on the bond strength of a bracket-bonding system cured with a light-emitting diode or plasma arc light.

    PubMed

    Dall'Igna, Carine Maccarini; Marchioro, Ernani Menezes; Spohr, Ana Maria; Mota, Eduardo Gonçalves

    2011-02-01

    The purpose of this study was to assess the influence of two light units, a light-emitting diode (LED) and a plasma arc light (PAC), on the shear bond strength (SBS) of brackets bonded to enamel. Ninety bovine teeth were divided into six groups, according to the light-curing unit and exposure times used. In the LED (Ortholux; 3M-Unitek) group, the specimens were light cured for 5, 10, and 15 seconds. In the PAC (Apollo 95E; DenMed Technologies) group, the specimens were light cured for 3, 6, and 9 seconds. The brackets were bonded with Transbond XT (3M-Unitek), stored in distilled water at 37 °C for 24 hours and then submitted to SBS testing in a universal testing machine. The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the teeth. According to analysis of variance and Tukey multiple comparisons test, the highest mean SBS was obtained with the LED at 15 seconds (16.68 MPa), which did not significantly differ from the LED 10 (14.76 MPa) or 5 (13.92 MPa) second groups (P > 0.05). The LED 10 and 5 second groups were not significantly different from the PAC 9 second group (12.66 MPa) or from the PAC 6 second group (9.96 MPa). The lowest mean SBS was obtained with the PAC 3 second group (8.29 MPa), which did not differ significantly from the PAC 6 second group. The method of light curing did not influence the ARI, with score 3 predominant. The LED at 5 seconds and the PAC at 3 seconds provided sufficient mean SBS to resist either orthodontic or masticatory forces. PMID:20558589

  11. Susceptible-infected-susceptible epidemics on networks with general infection and cure times

    NASA Astrophysics Data System (ADS)

    Cator, E.; van de Bovenkamp, R.; Van Mieghem, P.

    2013-06-01

    The classical, continuous-time susceptible-infected-susceptible (SIS) Markov epidemic model on an arbitrary network is extended to incorporate infection and curing or recovery times each characterized by a general distribution (rather than an exponential distribution as in Markov processes). This extension, called the generalized SIS (GSIS) model, is believed to have a much larger applicability to real-world epidemics (such as information spread in online social networks, real diseases, malware spread in computer networks, etc.) that likely do not feature exponential times. While the exact governing equations for the GSIS model are difficult to deduce due to their non-Markovian nature, accurate mean-field equations are derived that resemble our previous N-intertwined mean-field approximation (NIMFA) and so allow us to transfer the whole analytic machinery of the NIMFA to the GSIS model. In particular, we establish the criterion to compute the epidemic threshold in the GSIS model. Moreover, we show that the average number of infection attempts during a recovery time is the more natural key parameter, instead of the effective infection rate in the classical, continuous-time SIS Markov model. The relative simplicity of our mean-field results enables us to treat more general types of SIS epidemics, while offering an easier key parameter to measure the average activity of those general viral agents.

  12. Susceptible-infected-susceptible epidemics on networks with general infection and cure times.

    PubMed

    Cator, E; van de Bovenkamp, R; Van Mieghem, P

    2013-06-01

    The classical, continuous-time susceptible-infected-susceptible (SIS) Markov epidemic model on an arbitrary network is extended to incorporate infection and curing or recovery times each characterized by a general distribution (rather than an exponential distribution as in Markov processes). This extension, called the generalized SIS (GSIS) model, is believed to have a much larger applicability to real-world epidemics (such as information spread in online social networks, real diseases, malware spread in computer networks, etc.) that likely do not feature exponential times. While the exact governing equations for the GSIS model are difficult to deduce due to their non-Markovian nature, accurate mean-field equations are derived that resemble our previous N-intertwined mean-field approximation (NIMFA) and so allow us to transfer the whole analytic machinery of the NIMFA to the GSIS model. In particular, we establish the criterion to compute the epidemic threshold in the GSIS model. Moreover, we show that the average number of infection attempts during a recovery time is the more natural key parameter, instead of the effective infection rate in the classical, continuous-time SIS Markov model. The relative simplicity of our mean-field results enables us to treat more general types of SIS epidemics, while offering an easier key parameter to measure the average activity of those general viral agents. PMID:23848738

  13. Curing time effect on the fraction of {sup 137}Cs from cement-ion exchange resins-bentonite clay composition

    SciTech Connect

    Plecas, Ilija; Dimovic, Slavko

    2007-07-01

    To assess the safety of disposal of radioactive waste material in cement, curing conditions and time of leaching radionuclides {sup 137}Cs have been studied. Leaching tests in cement-ion exchange resins-bentonite matrix, were carried out in accordance with a method recommended by IAEA. Curing conditions and curing time prior to commencing the leaching test are critically important in leach studies since the extent of hydration of the cement materials determines how much hydration product develops and whether it is available to block the pore network, thereby reducing leaching. Incremental leaching rates R{sub n}(cm/d) of {sup 137}Cs from cement ion exchange resins-bentonite matrix after 180 days were measured. The results presented in this paper are examples of results obtained in a 20-year concrete testing project which will influence the design of the engineer trenches system for future central Serbian radioactive waste storing center. (authors)

  14. Effect of resin thickness, and curing time on the micro-hardness of bulk-fill resin composites

    PubMed Central

    Nagi, Shaymaa M.; Moharam, Lamiaa M.; Zaazou, Mohamed H.

    2015-01-01

    Background Bulk-fill resin composite has been introduced, their manufacturers claimed that they can be applied in bulks of 4mm, without necessitating a prolonged curing time, or a light curing unit with increased irradiance. Thus this study was conducted to evaluate the effect of resin thickness, and curing time on the micro-hardness of two bulk -fill resin composites; Tetric Evo-Ceram [TE], and X-trafil [XF]. Material and Methods 120 cylindrical specimens were prepared, and divided into 24 groups (n=5/group), representing the two bulk-fill resin composites, three different material thicknesses (2, 3 and 4 mm) and the four curing times used in the study (10, 20, 40, and 60 seconds). The specimens were light-cured from the top surface only. Specimens were stored in light proof containers in complete darkness at 37°C for 24 hours. Micro-hardness test was conducted on both top and bottom surfaces using Vickers micro-hardness tester with 500 g load and a dwell time of 15 seconds. Data were statistically analyzed by Four-way ANOVA of Variance. The significance level was set at P ≤ 0.05. Pearson Correlation used to determine significant correlations between mean micro-hardness (top) and (bottom) surfaces. Results Four way-ANOVA shows that different tested materials produce a statistically significant effect on mean micro-hardness (VHN) at p≤0.001, while thickness, curing time, and surface revealed statistically non significant effect on mean micro-hardness (VHN) at p≥0.05. [XF] (92.01±3.15 VHN) showed statistically significant higher mean micro-hardness than [TE] (54.13±4.96 VHN). Pearson Correlation revealed that there was a significant direct correlation between micro-hardness (bottom) and mean micro-hardness (top) (mm), r = 0.985, p (2-tailed) ≤0.001. Conclusions Within the limitations of this study, the bulk-fill resin composites used in this study can be placed and cured properly in the 4 mm bulk. Key words:Bulk-fill resin composite, micro

  15. Light-curing time and aging effects on the nanomechanical properties of methacrylate- and silorane-based restorations.

    PubMed

    Catelan, A; Pollard, T; Bedran-Russo, Ak; Santos, Ph Dos; Ambrosano, Gmb; Aguiar, Fhb

    2014-01-01

    SUMMARY The aim of this study was to assess the influence of light-curing time on the nanohardness (H) and reduced elastic modulus (Er) of components (underlying dentin, hybrid layer, adhesive, and composite) of methacrylate- and silorane-based restorations after 24 hours and six months of storage. Class II slot preparations were carried out in human molars (n=3) and restored with methacrylate (Clearfil SE Bond [Kuraray] + Filtek Z250 [3M ESPE]) or silorane (LS restorative system [3M ESPE]) restorative systems and light-cured using light-emitting diode at 1390 mW/cm(2) for the recommended manufacturers' time or double time. Restorations were sectioned, and bonded dentin-resin interfaces were embedded in epoxy resin and polished for evaluation with a Berkovich fluid cell tip (TI 700 Ubi-1 nanoindenter, Hysitron). Data were statistically analyzed by analysis of variance and Tukey's test (alpha=0.05). Overall, the H and Er values were higher for methacrylate-based restorations than for silorane materials (p≤0.05), an increase in curing time did not improve the H and Er of the bonded interface components of either material (p>0.05), and aging significantly decreased the mechanical properties of interface components of both resin-based restorative systems (p≤0.05). In general, nanomechanical properties decreased after six months of storage, the methacrylate restorative system exhibited higher H and Er than silorane, and light-curing time did not influence the properties tested. PMID:24967984

  16. The Impact of Ripening Time on Technological Quality Traits, Chemical Change and Sensory Characteristics of Dry-cured Loin

    PubMed Central

    Seong, Pil Nam; Park, Kyoung Mi; Kang, Geun Ho; Cho, Soo Hyun; Park, Beom Young; Van Ba, Hoa

    2015-01-01

    The effect of ripening time on the technological quality traits, fatty acid compositions and sensory characteristics of dry-cured loin was studied. Pork loins (n = 102) at 24 h post-mortem were used to produce dry-cured loins. The dry-cured loins were assessed at 30, 60, and 90 days of ripening for the aforementioned characteristics. Our results showed that the water activity (aw) decreased (p<0.05) up to 60 days and did not change thereafter. The lipid oxidation and weight loss levels significantly (p<0.05) increased with increased ripening time. The Commission Internationale de l’Eclairage (CIE) L* decreased for 90 days while CIE a* increased for 60 days and did not increase thereafter. More noticeably, the levels of most of unsaturated fatty acids and total polyunsaturated fatty acids significantly decreased as increasing ripening time up to 90 days. The 30 days-ripened loins had lower (p<0.05) color, flavor and overall acceptability scores than the loins ripened for 60 and 90 days, however, no differences in sensory traits occurred between the 60 and 90 day-ripened samples. Based on the results obtained in the present study, it is suggested that the ripening duration between 30 and 60 days could be more appropriate for producing dry-cured loin product with higher quality and economic benefits. PMID:25715685

  17. Optimization of the Temperature-Time Curve for the Curing Process of Thermoset Matrix Composites

    NASA Astrophysics Data System (ADS)

    Aleksendrić, Dragan; Carlone, Pierpaolo; Ćirović, Velimir

    2016-05-01

    An intelligent optimization model aiming at off-line or pre-series optimization of the thermal curing cycle of polymer matrix composites is proposed and discussed. The computational procedure is based on the coupling of a finite element thermochemical process model, dynamic artificial neural networks and genetic algorithms. Objective of the optimization routine is the maximization of the composite degree of cure by the definition of the autoclave temperature. Obtained outcomes evidenced the capability of the method as well as its efficiency with respect to hard computing or experimental procedures.

  18. Comparison of variation in the light curing cycle with a time gap and its effect on polymerization shrinkage, degree of conversion and microhardness of a nanohybrid composite

    PubMed Central

    Subbiya, Arunajatesan; Pearlin Mary, Newbegin Selvakumar Gold; Suresh, Malathi; Vivekanandhan, Paramasivam; Dhakshinamoorthy, Malarvizhi; Sukumaran, Vridhachalam Ganapathy

    2015-01-01

    Background: Giving a time gap and distance during curing can decrease the polymerization shrinkage. Aim: To evaluate the effect of time gap and distance between the curing tip and restoration on the polymerization shrinkage, degree of monomer conversion (DOC), and microhardness of a nanohybrid composite. Materials and Methods: A total of 50 standardized cylindrical specimens (Z350, 3M ESPE) were fabricated using a brass mould. The curing was done in contact with the sample surface for 20 seconds in the control group. In the four experimental groups, curing was initiated at 1-cm distance, followed by variation in the time gap and the curing cycle. The polymerization shrinkage, DOC, microhardness was calculated. Statistical Analysis: One-way analysis of variance (ANOVA) and post hoc-Dunnett test were used to analyze the data. Results: Curing at 1-cm distance for 10 seconds with a gap of 10 seconds and finishing the curing cycle with 20 seconds at 0 cm proved to be an appropriate technique to reduce the polymerization shrinkage without significantly affecting the DOC and microhardness. Conclusion: A simple innovative modification of varying the distance of curing and a time gap in the curing cycle can decrease the polymerization shrinkage without affecting the DOC and microhardness. PMID:25829697

  19. The effect of UV intensities and curing time on polymer dispersed liquid crystal (PDLC) display: A detailed analysis study

    NASA Astrophysics Data System (ADS)

    Ahmad, Farzana; Jamil, Muhammad; Lee, Jin Woo; Kim, Seo Rok; Jeon, Young Jae

    2016-08-01

    In current study polymer dispersed liquid crystal (PDLC) films whose composition based on nematic liquid crystal (LC) E7 and prepolymeric NOA65 were formed via the photo induced phase separation method, in a wide intensity range of the UV light (I = 0.33-1.8 mW/cm2) and curing duration (t = 120-600 sec). The PDLC characteristics were monitored by surface morphology, electro optical studies, as well as by phase separation process through measuring the FTIR absorption of the composite layers. Increase of curing light intensity accelerates the phase separation and drastically influences the final morphology of LC droplets inside PDLCs. Likewise by widening the curing duration the enhancement in phase separation was observed. Increase of light intensity from 0.89 mW/cm2 and duration t = 120-240 sec resulted into transition from large LC domains of irregular shape (due to aggregation of droplets) to fine mono dispersed LC droplets. This morphology caused increase in optical scattering on zero voltage and high driving voltage. However unexpectedly, this response was not directly related with the curing conditions (intensity and time). These findings extend the potential applications of thiol-ene based PDLCs. [Figure not available: see fulltext.

  20. Effects of light-curing time on the cytotoxicity of a restorative composite resin on odontoblastlike cells

    PubMed Central

    ARANHA, Andreza Maria Fábio; GIRO, Elisa Maria Aparecida; HEBLING, Josimeri; LESSA, Fernanda Campos Rosetti; COSTA, Carlos Alberto de Souza

    2010-01-01

    This in vitro study evaluated the cytotoxicity of an experimental restorative composite resin subjected to different light-curing regimens. Methods Forty round-shaped specimens were prepared and randomly assigned to four experimental groups (n=10), as follows: in Group 1, no light-curing; in Groups 2, 3 and 4, the composite resin specimens were light-cured for 20, 40 or 60 s, respectively. In Group 5, filter paper discs soaked in 5 μL PBS were used as negative controls. The resin specimens and paper discs were placed in wells of 24-well plates in which the odontoblast-like cells MDPC-23 (30,000 cells/cm2) were plated and incubated in a humidified incubator with 5% CO2 and 95% air at 37ºC for 72 h. The cytotoxicity was evaluated by the cell metabolism (MTT assay) and cell morphology (SEM). The data were analyzed statistically by Kruskal-Wallis and Mann- Whitney tests (p<0.05). Results In G1, cell metabolism decreased by 86.2%, indicating a severe cytotoxicity of the non-light-cured composite resin. On the other hand, cell metabolism decreased by only 13.3% and 13.5% in G2 and G3, respectively. No cytotoxic effects were observed in G4 and G5. In G1, only a few round-shaped cells with short processes on their cytoplasmic membrane were observed. In the other experimental groups as well as in control group, a number of spindle-shaped cells with long cytoplasmic processes were found. Conclusion Regardless of the photoactivation time used in the present investigation, the experimental composite resin presented mild to no toxic effects to the odontoblast-like MDPC-23 cells. However, intense cytotoxic effects occurred when no light-curing was performed. PMID:21085801

  1. Experimental and Numerical Analysis of the Effects of Curing Time on Tensile Mechanical Properties of Thin Spray-on Liners

    NASA Astrophysics Data System (ADS)

    Guner, D.; Ozturk, H.

    2016-08-01

    The effects of curing time on tensile elastic material properties of thin spray-on liners (TSLs) were investigated in this study. Two different TSL products supplied by two manufacturers were tested comparatively. The "dogbone" tensile test samples that were prepared in laboratory conditions with different curing times (1, 7, 14, 21, and 28 days) were tested based on ASTM standards. It was concluded that longer curing times improves the tensile strength and the Young's Modulus of the TSLs but decreases their elongation at break. Moreover, as an additional conclusion of the testing procedure, it was observed that during the tensile tests, the common malpractice of measuring sample displacement from the grips of the loading machine with a linear variable displacement transducer versus the sample's gauge length had a major impact on modulus and deformation determination of TSLs. To our knowledge, true stress-strain curves were generated for the first time in TSL literature within this study. Numerical analyses of the laboratory tests were also conducted using Particle Flow Code in 2 Dimensions (PFC2D) in an attempt to guide TSL researchers throughout the rigorous PFC simulation process to model support behaviour of TSLs. A scaling coefficient between macro- and micro-properties of PFC was calculated which will help future TSL PFC modellers mimic their TSL behaviours for various tensile loading support scenarios.

  2. Embedded piezoelectric sensor-based real-time strength monitoring during curing process of concrete

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Jin; Lee, Changgil; Chang, Hajoo; Park, Seunghee

    2011-04-01

    Recently, novel methods to monitor the strength development of concrete during curing process have been reported based on electro-mechanical impedance measurement using piezoelectric sensors. However, the previous research works could not provide the information about the absolute strength of concrete. In order to estimate the absolute strength directly, an embedded piezoelectric sensor system based strength monitoring technique was proposed in this study. To avoid the degradation of a piezoelectric sensor due to external and internal impacts and/or environmental variations, the piezoelectric sensor soldered with a lead wire is inserted into a small concrete block and then this block is embedded in larger concrete specimen. While the concrete is cured, the electro-mechanical impedance and guided wave signals, self-measured from the embedded piezoelectric sensor, would be changed because those are related to the material properties of the concrete such as the strength and the stiffness. Hence, the strength of concrete can be monitored by analyzing the root-mean-square-deviation (RMSD) of the impedance signals and the amplitude variation of the guided wave signals. Specific equations to estimate the strength of the concrete are derived using a regression analysis based on the features extracted from the signal variations. Finally, to verify the effectiveness of the proposed approach, a series of experimental studies using miscellaneous concrete specimens are conducted and further research issues will be discussed for real-world implementation of the proposed approach.

  3. Influence of the light-curing unit, storage time and shade of a dental composite resin on the fluorescence

    NASA Astrophysics Data System (ADS)

    Queiroz, R. S.; Bandéca, M. C.; Calixto, L. R.; Gaiao, U.; Cuin, A.; Porto-Neto, S. T.

    2010-07-01

    The aim of this study was to determine the influence of three light-curing units, storage times and colors of the dental composite resin on the fluorescence. The specimens (diameter 10.0 ± 0.1 mm, thickness 1.0 ± 0.1 mm) were made using a stainless steel mold. The mold was filled with the microhybrid composite resin and a polyethylene film covered each side of the mold. After this, a glass slide was placed on the top of the mold. To standardize the top surface of the specimens a circular weight (1 kg) with an orifice to pass the light tip of the LCU was placed on the top surface and photo-activated during 40 s. Five specimens were made for each group. The groups were divided into 9 groups following the LCUs (one QTH and two LEDs), storage times (immediately after curing, 24 hours, 7 and 30 days) and colors (shades: A2E, A2D, and TC) of the composite resin. After photo-activation, the specimens were storage in artificial saliva during the storage times proposed to each group at 37°C and 100% humidity. The analysis of variance (ANOVA) and Tukey’s posthoc tests showed no significant difference between storage times (immediately, 24 hours and 30 days) ( P > 0.05). The means of fluorescence had difference significant to color and light-curing unit used to all period of storage ( P < 0.05). The colors had difference significant between them (shades: A2D < A2E < TC) ( P < 0.05). The Ultraled (LED) and Ultralux (QTH) when used the TC shade showed higher than Radii (LED), however to A2E shade and A2D shade any difference were found ( P > 0.05).

  4. Effect of curing time and concentration for a chemical treatment that improves surface gliding for extrasynovial tendon grafts in vitro

    PubMed Central

    Tanaka, Toshikazu; Sun, Yu-Long; Zhao, Chunfeng; Zobitz, Mark E.; An, Kai-Nan; Amadio, Peter C.

    2013-01-01

    The purpose of this study was to evaluate whether treatment time and concentration of these reagents have an effect on the resulting gliding resistance. Forty peroneus longus (PL) tendons were used, from 20 adult mongrel dogs, along with the A2 pulley obtained from the ipsilateral hind paw. After the baseline gliding resistance was measured, the PL tendons were treated with one of three concentrations of hyaluronic acid (HA) and 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC) or N-hydroxysuccinimide (NHS) mixed with 10% gelatin for various times (5, 30, and 60 min). Tendon friction was measured over 1000 cycles of simulated flexion/extension motion. Gliding resistance of the untreated PL tendons had no significant difference among the groups. After surface treatment with low concentration of HA and EDC/NHS for 5-min cure, the gliding resistance was similar to that of the untreated PL tendon and significantly higher than its 30- and 60-min treatment. For the rest of high concentration of HA and EDC/NHS groups, the gliding resistance was lower than that of untreated PL tendon. However, there was no significant difference among the timing points. It is possible to optimize the effect of surface treatment on friction and durability by regulating cure time and concentration of reagents in a canine extrasynovial tendon in vitro. PMID:16752399

  5. Supporting Quality Timely PhD Completions: Delivering Research Outcomes

    ERIC Educational Resources Information Center

    Gasson, Susan

    2015-01-01

    The case study used a three-phase organising process to explain how design and implementation of an accessible and interactive electronic thesis submission form streamlined quality assurance of theses and their timely dissemination via an online thesis repository. The quality of the theses submitted is assured by key academics in their final sign…

  6. Prediction of the curing time to achieve maturity of the nano-cement based concrete using the Weibull distribution model: A complementary data set

    PubMed Central

    Jo, Byung Wan; Chakraborty, Sumit; Kim, Heon

    2015-01-01

    This data article provides a comparison data for nano-cement based concrete (NCC) and ordinary Portland cement based concrete (OPCC). Concrete samples (OPCC) were fabricated using ten different mix design and their characterization data is provided here. Optimization of curing time using the Weibull distribution model was done by analyzing the rate of change of compressive strength of the OPCC. Initially, the compressive strength of the OPCC samples was measured after completion of four desired curing times. Thereafter, the required curing time to achieve a particular rate of change of the compressive strength has been predicted utilizing the equation derived from the variation of the rate of change of compressive strength with the curing time, prior to the optimization of the curing time (at the 99.99% confidence level) using the Weibull distribution model. This data article complements the research article entitled “Prediction of the curing time to achieve maturity of the nano-cement based concrete using the Weibull distribution model” [1]. PMID:26217804

  7. Prediction of the curing time to achieve maturity of the nano-cement based concrete using the Weibull distribution model: A complementary data set.

    PubMed

    Jo, Byung Wan; Chakraborty, Sumit; Kim, Heon

    2015-09-01

    This data article provides a comparison data for nano-cement based concrete (NCC) and ordinary Portland cement based concrete (OPCC). Concrete samples (OPCC) were fabricated using ten different mix design and their characterization data is provided here. Optimization of curing time using the Weibull distribution model was done by analyzing the rate of change of compressive strength of the OPCC. Initially, the compressive strength of the OPCC samples was measured after completion of four desired curing times. Thereafter, the required curing time to achieve a particular rate of change of the compressive strength has been predicted utilizing the equation derived from the variation of the rate of change of compressive strength with the curing time, prior to the optimization of the curing time (at the 99.99% confidence level) using the Weibull distribution model. This data article complements the research article entitled "Prediction of the curing time to achieve maturity of the nano-cement based concrete using the Weibull distribution model" [1]. PMID:26217804

  8. Slide Rule For Calculating Curing Schedules

    NASA Technical Reports Server (NTRS)

    Heater, Don

    1995-01-01

    Special-purpose slide rule devised for calculating schedules for storing and curing adhesives, sealants, and other materials characterized by known curing times and shelf lives. Prevents mistakes commonly made in determining storage and curing schedules.

  9. Reporting the sensory properties of dry-cured ham using a new language: Time intensity (TI) and temporal dominance of sensations (TDS).

    PubMed

    Lorido, Laura; Hort, Joanne; Estévez, Mario; Ventanas, Sonia

    2016-11-01

    The present study aimed to evaluate the influence of salt content (normal and reduced) and feeding system (montanera and concentrate) on the dynamic sensory characteristics of dry-cured hams using time-intensity (TI) and Temporal Dominance of Sensations (TDS) techniques. Differences in the temporal sensory information given by the two different techniques were found. Significant differences in the temporal perception of flavour and texture were detected between normal and reduced salt content dry-cured hams which are a Spanish pricy meat product very appreciated by consumers due to its particular sensory characteristics. The effect of the feeding system was mainly observed on flavour attributes such as saltiness and cured flavour and texture attributes such as juiciness. The application of TDS technique to study temporal sensory attributes of dry-cured ham is reported for the first time in the present article. PMID:27322593

  10. Effect of Curing Time on the Physicochemical and Sensory Properties of Beef Jerky Replaced Salt with Soy Sauce, Red Pepper Paste and Soybean Paste

    PubMed Central

    Lim, H. J.; Kim, G. D.; Jung, E. Y.; Seo, H. W.; Joo, S. T.; Jin, S. K.; Yang, H. S.

    2014-01-01

    This study was done to investigate the quality properties of beef jerky with soy sauce, red pepper paste, and soybean paste replacing salt. Sliced beef samples were cured in salt (control), soy sauce, red pepper paste, and soybean paste for 24 or 48 h and then dried at 70°C for 8 h. Treatments showed higher final moisture content and lower Na+ concentration than the control after drying for 8 h. The lightness and shear force values were lower in all treatment samples than in the control during 48 h of curing time. In particular, lower lipid oxidation was found in the jerky cured with red pepper paste than in the control. Sensory evaluation showed that color, flavor, and tenderness of jerky samples were improved by replacing salt with soy sauce, red pepper paste and soybean paste, and higher likeability scores of the beef jerky were obtained among those treatments after 48 h of curing time. PMID:25083112

  11. Curing time effect on the fraction of {sup 137}Cs from immobilized radioactive evaporator sludge by cement

    SciTech Connect

    Dimovic, Slavko; Plecas, Ilija

    2007-07-01

    Available in abstract form only. Full text of publication follows: Traditional methods of processing evaporator concentrates from NPP are evaporation and cementation. These methods allow to transform a liquid radioactive waste into the rather inert form, suitable for a final disposal. To assess the safety for disposal of radioactive mortar-waste composition, the leaching of {sup 137}Cs from immobilized radioactive evaporator concentrate into a surrounding fluid has been studied. Leaching tests were carried out in accordance with a method recommended by IAEA. Curing conditions and curing time prior to commencing the leaching test are critically important in leach studies since the extent of hydration of the cement materials determines how much hydration product develops and whether it is available to block the pore network, thereby reducing leaching. Incremental leaching rates Rn(cm/d) of {sup 137}Cs from evaporator concentrates after 180 days were measured. The results presented in this paper are examples of results obtained in a 20-year concrete testing project which will influence the design of the engineer trenches system for future central Serbian radioactive waste storing center. (authors)

  12. Cure SMA

    MedlinePlus

    ... real progress toward a treatment and a cure. Latest News August 29, 2016 2016 SMA Researcher Meeting ... Fundraisers Connect with Us Sign up for the latest SMA information Let us help you connect to ...

  13. pH Dependence of the Photoactive Yellow Protein Photocycle Investigated by Time-Resolved Crystallography

    SciTech Connect

    Tripathi, Shailesh; Šrajer, Vukica; Purwar, Namrta; Henning, Robert; Schmidt, Marius

    2012-05-24

    Visualizing the three-dimensional structures of a protein during its biological activity is key to understanding its mechanism. In general, protein structure and function are pH-dependent. Changing the pH provides new insights into the mechanisms that are involved in protein activity. Photoactive yellow protein (PYP) is a signaling protein that serves as an ideal model for time-dependent studies on light-activated proteins. Its photocycle is studied extensively under different pH conditions. However, the structures of the intermediates remain unknown until time-resolved crystallography is employed. With the newest beamline developments, a comprehensive time series of Laue data can now be collected from a single protein crystal. This allows us to vary the pH. Here we present the first structure, to our knowledge, of a short-lived protein-inhibitor complex formed in the pB state of the PYP photocycle at pH 4. A water molecule that is transiently stabilized in the chromophore active site prevents the relaxation of the chromophore back to the trans configuration. As a result, the dark-state recovery is slowed down dramatically. At pH 9, PYP stops cycling through the pB state altogether. The electrostatic environment in the chromophore-binding site is the likely reason for this altered kinetics at different pH values.

  14. pH Dependence of the Photoactive Yellow Protein Photocycle Investigated by Time-Resolved Crystallography

    PubMed Central

    Tripathi, Shailesh; Šrajer, Vukica; Purwar, Namrta; Henning, Robert; Schmidt, Marius

    2012-01-01

    Visualizing the three-dimensional structures of a protein during its biological activity is key to understanding its mechanism. In general, protein structure and function are pH-dependent. Changing the pH provides new insights into the mechanisms that are involved in protein activity. Photoactive yellow protein (PYP) is a signaling protein that serves as an ideal model for time-dependent studies on light-activated proteins. Its photocycle is studied extensively under different pH conditions. However, the structures of the intermediates remain unknown until time-resolved crystallography is employed. With the newest beamline developments, a comprehensive time series of Laue data can now be collected from a single protein crystal. This allows us to vary the pH. Here we present the first structure, to our knowledge, of a short-lived protein-inhibitor complex formed in the pB state of the PYP photocycle at pH 4. A water molecule that is transiently stabilized in the chromophore active site prevents the relaxation of the chromophore back to the trans configuration. As a result, the dark-state recovery is slowed down dramatically. At pH 9, PYP stops cycling through the pB state altogether. The electrostatic environment in the chromophore-binding site is the likely reason for this altered kinetics at different pH values. PMID:22339869

  15. Defining cure.

    PubMed

    Hilton, Paul; Robinson, Dudley

    2011-06-01

    This paper is a summary of the presentations made as Proposal 2-"Defining cure" to the 2nd Annual meeting of the ICI-Research Society, in Bristol, 16th June 2010. It reviews definitions of 'cure' and 'outcome', and considers the impact that varying definition may have on prevalence studies and cure rates. The difference between subjective and objective outcomes is considered, and the significance that these different outcomes may have for different stakeholders (e.g. clinicians, patients, carers, industry etc.) is discussed. The development of patient reported outcome measures and patient defined goals is reviewed, and consideration given to the use of composite end-points. A series of proposals are made by authors and discussants as to how currently validated outcomes should be applied, and where our future research activity in this area might be directed. PMID:21661023

  16. Influence of 2% chlorhexidine on pH, calcium release and setting time of a resinous MTA-based root-end filling material.

    PubMed

    Jacinto, Rogério Castilho; Linhares-Farina, Giane; Sposito, Otávio da Silva; Zanchi, César Henrique; Cenci, Maximiliano Sérgio

    2015-01-01

    The addition of chlorhexidine (CHX) to a resinous experimental Mineral Trioxide Aggregate (E-MTA) based root-end filling material is an alternative to boost its antimicrobial activity. However, the influence of chlorhexidine on the properties of this material is unclear. The aim of this study was to evaluate the influence of 2% chlorhexidine on the pH, calcium ion release and setting time of a Bisphenol A Ethoxylate Dimethacrylate/Mineral Trioxide Aggregate (Bis-EMA/MTA) based dual-cure experimental root-end filling material (E-MTA), in comparison with E-MTA without the addition of CHX and with conventional white MTA (W-MTA). The materials were placed in polyethylene tubes, and immersed in deionized water to determine pH (digital pH meter) and calcium ion release (atomic absorption spectrometry technique). The setting time of each material was analyzed using Gilmore needles. The data were statistically analyzed at a significance level of 5%. E-MTA + CHX showed an alkaline pH in the 3 h period of evaluation, the alkalinity of which decreased but remained as such for 15 days. The pH of E-MTA + CHX was higher than the other two materials after 7 days, and lower after 30 days (p < 0.05). All of the materials were found to release calcium ions throughout the 30 days of the study. The addition of CHX increased the calcium ion release of E-MTA to levels statistically similar to W-MTA. E-MTA showed shorter initial and final setting time, compared with W-MTA (p < 0.05). The addition of 2% CHX to MTA prevented setting of the material. The addition of CHX to E-MTA increased its pH and calcium ion release. However, it also prevented setting of the material. PMID:25715035

  17. Assessment of Tandem Measurements of pH and Total Gut Transit Time in Healthy Volunteers

    PubMed Central

    Mikolajczyk, Adam E; Watson, Sydeaka; Surma, Bonnie L; Rubin, David T

    2015-01-01

    Objectives: The variation of luminal pH and transit time in an individual is unknown, yet is necessary to interpret single measurements. This study aimed to assess the intrasubject variability of gut pH and transit time in healthy volunteers using SmartPill devices (Covidien, Minneapolis, MN). Methods: Each subject (n=10) ingested two SmartPill devices separated by 24 h. Mean pH values were calculated for 30 min after gastric emptying (AGE), before the ileocecal (BIC) valve, after the ileocecal (AIC) valve, and before body exit (BBE). Intrasubject variability was determined by comparing mean values from both ingestions for an individual subject using standard deviations, 95% limits of agreement, and Bland-Altman plots. Results: Tandem device ingestion occurred without complication. The median (full range) intrasubject standard deviations for pH were 0.02 (0.0002–0.2048) for AGE, 0.06 (0.0002–0.3445) for BIC, 0.14 (0.0018–0.3042) for AIC, and 0.08 (0.0098–0.5202) for BBE. There was a significant change in pH for AIC (mean difference: −0.45±0.31, P=0.0015) observed across all subjects. The mean coefficients of variation for transit time were 12.0±7.4% and 25.8±15.8% for small and large bowels, respectively (P=0.01). Conclusions: This study demonstrates the safety and feasibility of tandem gut transit and pH assessments using the SmartPill device. In healthy individuals and over 24 h, the gut pH profile does not markedly fluctuate in a given region with more variation seen in the colon compared with the small bowel, which has important implications for future physiology and drug delivery studies. PMID:26158610

  18. What motivates participation in HIV cure trials? A call for real-time assessment to improve informed consent

    PubMed Central

    Peay, Holly L; Henderson, Gail E

    2015-01-01

    HIV cure research, a diverse set of studies aimed at eradicating or greatly reducing HIV in latent reservoirs, has become a strategic priority for global AIDS research. However, in early-phase HIV cure research there are ethical challenges related to the uncertainty around potential risks and the risk–benefit balance. Similar to clinical trials in other disease areas, these concerns may impact clinical trial participants' comprehension and decision making. Here we suggest attention to the terminology used to describe HIV cure research that may promote therapeutic misconception, and exploration of the decision-making influences and processes of those who accept and decline participation in HIV cure trials. These data will facilitate efforts to improve protocols and informed consent based on an understanding of participant preferences and needs. PMID:25866844

  19. 25 CFR 162.592 - What will BIA do if a lessee does not cure a violation of a WSR lease on time?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 25 Indians 1 2013-04-01 2013-04-01 false What will BIA do if a lessee does not cure a violation of a WSR lease on time? 162.592 Section 162.592 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER LEASES AND PERMITS Wind and Solar Resource Leases Wsr Lease...

  20. 25 CFR 162.592 - What will BIA do if a lessee does not cure a violation of a WSR lease on time?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 25 Indians 1 2014-04-01 2014-04-01 false What will BIA do if a lessee does not cure a violation of a WSR lease on time? 162.592 Section 162.592 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER LEASES AND PERMITS Wind and Solar Resource Leases Wsr Lease...

  1. Effect of Packaging Method and Storage Time on Physicochemical Characteristics of Dry-Cured Pork Neck Products at 10°C

    PubMed Central

    Kim, Il-Suk; Jin, Sang-Keun; Yang, Mi-Ra; Ahn, Dong Uk; Park, Jae-Hong; Kang, Suk-Nam

    2014-01-01

    Dry-cured pork neck samples were stored at 10°C for 90 days under vacuum packaging (VP) or modified atmosphere packaging (MAP; 25% CO2+75% N2) conditions. The pH, moisture, water activity, total aerobic bacteria, and Enterobacteriaceae counts of dry-cured pork neck products with MAP were significantly lower than those with VP (p<0.05) after 90 days of storage. However, CIE b* and 2-thiobarbituric acid reacted substance (TBARS) values of the pork product with MAP were significantly higher (p<0.05) than those with VP. Total aerobic bacterial counts and Enterobacteriaceae counts of samples with MAP were lower than those with VP after 30 days of storage. Sensory results indicated that aroma, flavor and tenderness scores of the samples with both VP and MAP decreased during storage and the scores after >60 days of storage were lower than those at Day 1. In conclusion, despite presenting higher lipid oxidation, the samples stored in packages containing 25% CO2 for 90 days at 10°C have lower bacterial counts than vacuum-packed samples. Therefore, further studies should be performed on the packaging of dry-cured meat at adjusted concentrations of CO2. PMID:25358323

  2. Rapid characterization of dry cured ham produced following different PDOs by proton transfer reaction time of flight mass spectrometry (PTR-ToF-MS).

    PubMed

    Del Pulgar, José Sánchez; Soukoulis, Christos; Biasioli, Franco; Cappellin, Luca; García, Carmen; Gasperi, Flavia; Granitto, Pablo; Märk, Tilmann D; Piasentier, Edi; Schuhfried, Erna

    2011-07-15

    In the present study, the recently developed proton transfer reaction time of flight mass spectrometry (PTR-ToF-MS) technique was used for the rapid characterization of dry cured hams produced according to 4 of the most important Protected Designations of Origin (PDOs): an Iberian one (Dehesa de Extremadura) and three Italian ones (Prosciutto di San Daniele, Prosciutto di Parma and Prosciutto Toscano). In total, the headspace composition and respective concentration for nine Spanish and 37 Italian dry cured ham samples were analyzed by direct injection without any pre-treatment or pre-concentration. Firstly, we show that the rapid PTR-ToF-MS fingerprinting in conjunction with chemometrics (Principal Components Analysis) indicates a good separation of the dry cured ham samples according to their production process and that it is possible to set up, using data mining methods, classification models with a high success rate in cross validation. Secondly, we exploited the higher mass resolution of the new PTR-ToF-MS, as compared with standard quadrupole based versions, for the identification of the exact sum formula of the mass spectrometric peaks providing analytical information on the observed differences. The work indicates that PTR-ToF-MS can be used as a rapid method for the identification of differences among dry cured hams produced following the indications of different PDOs and that it provides information on some of the major volatile compounds and their link with the implemented manufacturing practices such as rearing system, salting and curing process, manufacturing practices that seem to strongly affect the final volatile organic profile and thus the perceived quality of dry cured ham. PMID:21645714

  3. In Site Analysis of a High Temperature Cure Reaction in Real Time Using Modulated Fiber-Optic FT-Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Cooper, John; Aust, Jeffrey F.; Wise, Kent L.; Jensen, Brian J.

    1999-01-01

    The vibrational spectrum of a high temperature (330 C) polymerization reaction was successfully monitored in real time using a modulated fiber-optic FT-Raman spectrometer. A phenylethynyl terminated monomer was cured, and spectral evidence for two different reaction products was acquired. The products are a conjugated polyene chain and a cyclized trimer. This is the first report describing the use of FT-Raman spectroscopy to monitor a high temperature (greater than 250 C) reaction in real time.

  4. Time to the Doctorate and Labor Demand for New PhD Recipients

    ERIC Educational Resources Information Center

    Groen, Jeffrey A.

    2012-01-01

    This paper considers the influence of labor demand for new PhD recipients on time to the doctorate. I use student-level data on all doctorates awarded by U.S. universities in seven humanities and social science fields together with the annual number of job listings by field from 1975 to 2005. An increase in the number of job listings in a field…

  5. Comparative static curing versus dynamic curing on tablet coating structures.

    PubMed

    Gendre, Claire; Genty, Muriel; Fayard, Barbara; Tfayli, Ali; Boiret, Mathieu; Lecoq, Olivier; Baron, Michel; Chaminade, Pierre; Péan, Jean Manuel

    2013-09-10

    Curing is generally required to stabilize film coating from aqueous polymer dispersion. This post-coating drying step is traditionally carried out in static conditions, requiring the transfer of solid dosage forms to an oven. But, curing operation performed directly inside the coating equipment stands for an attractive industrial application. Recently, the use of various advanced physico-chemical characterization techniques i.e., X-ray micro-computed tomography, vibrational spectroscopies (near infrared and Raman) and X-ray microdiffraction, allowed new insights into the film-coating structures of dynamically cured tablets. Dynamic curing end-point was efficiently determined after 4h. The aim of the present work was to elucidate the influence of curing conditions on film-coating structures. Results demonstrated that 24h of static curing and 4h of dynamic curing, both performed at 60°C and ambient relative humidity, led to similar coating layers in terms of drug release properties, porosity, water content, structural rearrangement of polymer chains and crystalline distribution. Furthermore, X-ray microdiffraction measurements pointed out different crystalline coating compositions depending on sample storage time. An aging mechanism might have occur during storage, resulting in the crystallization and the upward migration of cetyl alcohol, coupled to the downward migration of crystalline sodium lauryl sulfate within the coating layer. Interestingly, this new study clearly provided further knowledge into film-coating structures after a curing step and confirmed that curing operation could be performed in dynamic conditions. PMID:23792043

  6. In Situ Analysis of a High-Temperature Cure Reaction in Real Time Using Modulated Fiber-Optic FT-Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Aust, Jeffrey F.; Cooper, John B.; Wise, Kent L.; Jensen, Brian J.

    1999-01-01

    The vibrational spectrum of a high-temperature (330 C) polymerization reaction was successfully monitored in real time with the use of a modulated fiber-optic Fourier transform (FT)-Raman spectrometer. A phenylethynyl-terminated monomer was cured, and spectral evidence for two different reaction products was acquired. The products are a conjugated polyene chain and a cyclized trimer. This is the first report describing the use of FT-Raman spectroscopy to monitor a high temperature (greater than 250 C) reaction in real time.

  7. Real-Time Drug Release Analysis of Enzyme and pH Responsive Polysaccharide Nanovesicles.

    PubMed

    Pramod, Poothayil Subash; Deshpande, Nilesh Umakant; Jayakannan, Manickam

    2015-08-20

    The accurate estimation of drug release kinetics of polymeric vehicles is an indispensable prerequisite for the developments of successful drug carriers for cancer therapy. The present investigation reports the development of time-resolved fluorescence spectroscopic approach for the real-time release kinetics of fluorophore loaded polysaccharide vesicles that are potential vectors in cancer treatment. The polysaccharide vesicles were custom designed with appropriate enzyme and pH responsiveness and loaded with water-soluble biocompatible fluorophore Rhodamine B (Rh-B). The semipermeable membrane dialysis method along with steady state absorbance spectroscopic technique was found to be inaccurate for the estimation of drug release. Time correlated single photon counting (TCSPC) technique was found to exhibit significant difference in excited state decay profiles and fluorescent lifetime of Rh-B in the free and polymer bound states. This enabled the establishment of real-time drug release protocols by TCSPC method for polysaccharide vesicles that are responsible to pH and enzyme with respect to intracellular compartments. Real-time analysis predicted the release kinetics 20-25% higher accuracy when compared to the dialysis method under in vitro conditions. Moreover, the ability of enzyme to cleave the polysaccharide vesicles was further validated by docking studies. The positioning of the molecules in active site of enzyme and the binding energy data were generated using AUTODOCK program to study the rupture of polysaccharide vesicles. This new TCSPC technique could be very useful for studying the drug release pattern of synthetic polymer vesicles loaded with Rh-B fluorophore. PMID:26237375

  8. Nano-chemo-mechanical signature of conventional oil-well cement systems: Effects of elevated temperature and curing time

    SciTech Connect

    Krakowiak, Konrad J.; Thomas, Jeffrey J.; Musso, Simone; James, Simon; Akono, Ange-Therese; Ulm, Franz-Josef

    2015-01-15

    With ever more challenging (T,p) environments for cementing applications in oil and gas wells, there is a need to identify the fundamental mechanisms of fracture resistant oil well cements. We report results from a multi-technique investigation of behavior and properties of API class G cement and silica-enriched cement systems subjected to hydrothermal curing from 30 °C to 200 °C; including electron probe microanalysis, X-ray diffraction, thermogravimetry analysis, electron microscopy, neutron scattering (SANS), and fracture scratch testing. The results provide a new insight into the link between system chemistry, micro-texture and micro-fracture toughness. We suggest that the strong correlation found between chemically modulated specific surface and fracture resistance can explain the drop in fracture properties of neat oil-well cements at elevated temperatures; the fracture property enhancement in silica-rich cement systems, between 110° and 175 °C; and the drop in fracture properties of such systems through prolonged curing over 1 year at 200 °C.

  9. Revisiting the Posttherapeutic Cure Criterion in Chagas Disease: Time for New Methods, More Questions, Doubts, and Polemics or Time to Change Old Concepts?

    PubMed Central

    de Lana, Marta; Martins-Filho, Olindo Assis

    2015-01-01

    One of the most relevant issues beyond the effectiveness of etiological treatment of Chagas disease is the lack of consensual/feasible tools to identify and certify the definitive parasitological cure. Several methods of distinct natures (parasitological, serological, and molecular) have been continuously proposed and novel perspectives are currently under investigation. Although the simultaneous use of distinct tests may offer better contributions and advances, it also leads to controversies of interpretation, with lack of mutual consent of cure criterion amongst researchers and physicians. In fact, when distinct host compartments (blood/tissues) are evaluated and explored, novel questions may arise due to the nature and sensitivity limit of each test. This short analytical review intends to present a chronological and critical overview and discuss the state-of-the-art distinct devices available for posttherapeutic cure assessment in Chagas disease, their contributions, meanings, and interpretation, aiming to point out the major gaps and propose novel insight for future perspectives of posttherapeutic management of Chagas disease patients. PMID:26583124

  10. Time-to-Fatigue and Intramuscular pH measured via NIRS during Handgrip Exercise in Trained and Sedentary Individuals

    NASA Technical Reports Server (NTRS)

    Everett, M. E.; Lee, S. M. C.; Stroud, L.; Scott, P.; Hagan, R. D.; Soller, B.R.

    2009-01-01

    In exercising muscles force production and muscular endurance are impaired by a decrease in intramuscular pH. The effects of aerobic training (AT) on preventing acidosis and prolonging exercise time in muscles not specifically targeted by the training are unknown. Purpose: To compare interstitial pH, measured non-invasively with near infrared spectroscopy (NIRS), in the flexor digitorum profundus (FDP) during rhythmic handgrip exercise in sedentary subjects and those who participate in AT activities that target the lower body. Methods: Maximal isometric force (MIF) was measured on three separate days in AT (n=5) and sedentary (n=8) subjects using a handgrip dynamometer (HGD). Isometric muscular endurance (IME) was measured during five trials, each separated by at least 48 hrs. For each IME trial subjects rhythmically squeezed (4 sec at 40% of MVC) and relaxed (2 sec) to fatigue or failure to reach the target force in three consecutive contractions or four non-consecutive contractions. Interstitial pH was derived from spectra collected using a NIRS sensor adhered to the skin over the FDP. The first four IME trials served to familiarize subjects with the protocol; the fifth trial was used for analysis. NIRS-derived pH was averaged in 30 sec increments. Between group differences in MIF and exercise time were tested using paired t-tests. A repeated measures ANOVA was used to analyze effects of AT and exercise time on pH. Results: MIF was not different between groups (mean SD; aerobic=415.6 95.4 N vs. sedentary =505.1 107.4 N). Time to fatigue was greater in the AT than in the sedentary group (mean SD: 611 173 sec vs. 377 162 sec, p<0.05). pH was not different between groups at any time point. Average pH decreased (p<0.05) in both groups from rest (pH=7.4) through 90 sec of exercise (pH=6.9), but did not decrease further throughout the remainder of exercise. Conclusion: Although between group differences in pH were not detected, differences during the onset of exercise

  11. Effect of curing conditions on the dimensional and thermal stability of calcium phosphate cement for elevated temperature applications

    SciTech Connect

    Blom, Johan; Rahier, Hubert; Wastiels, Jan

    2014-12-15

    Calcium phosphate cements (CPCs) are attractive materials for elevated temperature applications, like moulds to process thermoplastics up to 300 °C. The CPC resulting from the reaction of wollastonite with phosphoric acid cured at room temperature however contains hydrated phases like brushite, and is thus not stable when exposed to temperatures above 200 °C. A non-contact method based on digital image correlation demonstrated that isothermal curing at 60 °C reduces the thermal shrinkage up to 300 °C by 25%. This curing method results in the direct formation of the more stable monetite in a shorter curing time. The correlated results of TGA, pH of the filtration water, and DSC analysis on partially cured material indicate this. XRD diffractograms and SEM images in combination with EDX show the evolution of the transformation of wollastonite into monetite, and the structure and morphology of the formed material.

  12. Microbiological and physicochemical characterization of dry-cured Halal goat meat. Effect of salting time and addition of olive oil and paprika covering.

    PubMed

    Cherroud, Sanâa; Cachaldora, Aida; Fonseca, Sonia; Laglaoui, Amin; Carballo, Javier; Franco, Inmaculada

    2014-10-01

    The objective of this work was to define a simple technological process for dry-cured Halal goat meat elaboration. The aims of this study were to analyze physicochemical parameters and to enumerate the microbial population at the end of the different manufacturing processes (two salting times and the addition of olive oil and paprika covering) on 36 units of meat product. A total of 532 strains were isolated from several selective culture media and then identified using classical and molecular methods. In general, salt effect and the addition of olive oil and paprika were significant for all the studied microbial groups as well as on NaCl content and water activity. Molecular analysis proves that staphylococci, especially Staphylococcus xylosus and Staphylococcus equorum, were the most common naturally occurring microbiota. The best manufacturing process would be obtained with a longer salting time and the addition of the olive oil and paprika covering. PMID:24950081

  13. Wide range pH measurements using a single H(+)-selective chromoionophore and a time-based flow method.

    PubMed

    Safavi, Afsaneh; Rostamzadeh, Abolfazl; Maesum, Saeed

    2006-02-28

    A hydrophilic transparent triacetyl cellulose membrane was adopted as a pH optode by immobilizing highly selective and sensitive Nile blue indicator on the membrane. Contrary to the common procedure for determinations using optodes, in which a steady state response is measured, a new approach is introduced in which the dynamic response of the optode is used as the analytical signal. While in common procedures, pH optodes exhibit limited linear dynamic range (often 2-4 pH units only), it is shown that in a time-based flow method, an optode with only one acid-base indicator can be used for measurement in the pH range of 0-10. The procedure is simple, inexpensive and rapid. PMID:18970487

  14. Influence of the salting time on volatile compounds during the manufacture of dry-cured pork shoulder "lacón".

    PubMed

    Purriños, Laura; Franco, Daniel; Carballo, Javier; Lorenzo, José M

    2012-12-01

    The effect of the length of salting time on volatile compounds throughout the manufacture of dry-cured "lacón" was studied using a purge-and-trap extraction and GC/MS analysis. For this study, six treatments of "lacón" were salted with different amounts of salt (LS (3 days of salting), MS (4 days of salting) and HS (5 days of salting)). The total area of volatile compounds increased significantly (P<0.001) as the length of salting time increased. Significant differences were found for the total area of all aldehydes for each salting time at the end of process. Hexanal presented the most relative abundance, showing highest content in HS treatments while LS treatments showed the lowest one at the end of salting, post-salting and drying-ripening stage. The influence of salting time on the content of 3-Octen-2-one was significant on salting stage (P<0.001) and drying-ripening stage (P<0.01). The salting time affected (P<0.001) the relative abundance of esters at the end of salting and at the end of drying-ripening stage. The salting time affected significantly (P<0.001) on alcohols content at the end of drying-ripening process. However, no significant effect of salt level (P>0.05) was detected on total hydrocarbons and total furans at the end of process. PMID:22749430

  15. Time variability of the north-western Mediterranean Sea pH over 1995-2011.

    PubMed

    Marcellin Yao, Koffi; Marcou, Olivier; Goyet, Catherine; Guglielmi, Véronique; Touratier, Franck; Savy, Jean-Philippe

    2016-05-01

    Factors controlling ocean acidification and its temporal variations were studied over the 1995-2011 period at the Dyfamed site at 10 m depth, in the North Mediterranean Sea. The results indicated a mean annual decrease of 0.003 ± 0.001 pH units on the seawater scale. The seasonal variability was characterized by a pH decrease during springtime and a strong pH increase in late fall. Anthropogenic CO2 (CANT) absorption by the ocean was the key driver of seawater acidification in this region, accounting for about 70% of the observed drop in pH, followed by water temperature (about 30%). The total inorganic carbon (CT) data showed a CT increase of 30.0 ± 1.0 μmol kg(-1) per decade. This decadal increase is mainly due to the CANT penetration (43.2 μmol kg(-1) per decade) in surface waters, which is mitigated for by relatively small opposing changes in CT due to physical and biological processes. PMID:26994464

  16. A Time-Accurate Upwind Unstructured Finite Volume Method for Compressible Flow with Cure of Pathological Behaviors

    NASA Technical Reports Server (NTRS)

    Loh, Ching Y.; Jorgenson, Philip C. E.

    2007-01-01

    A time-accurate, upwind, finite volume method for computing compressible flows on unstructured grids is presented. The method is second order accurate in space and time and yields high resolution in the presence of discontinuities. For efficiency, the Roe approximate Riemann solver with an entropy correction is employed. In the basic Euler/Navier-Stokes scheme, many concepts of high order upwind schemes are adopted: the surface flux integrals are carefully treated, a Cauchy-Kowalewski time-stepping scheme is used in the time-marching stage, and a multidimensional limiter is applied in the reconstruction stage. However even with these up-to-date improvements, the basic upwind scheme is still plagued by the so-called "pathological behaviors," e.g., the carbuncle phenomenon, the expansion shock, etc. A solution to these limitations is presented which uses a very simple dissipation model while still preserving second order accuracy. This scheme is referred to as the enhanced time-accurate upwind (ETAU) scheme in this paper. The unstructured grid capability renders flexibility for use in complex geometry; and the present ETAU Euler/Navier-Stokes scheme is capable of handling a broad spectrum of flow regimes from high supersonic to subsonic at very low Mach number, appropriate for both CFD (computational fluid dynamics) and CAA (computational aeroacoustics). Numerous examples are included to demonstrate the robustness of the methods.

  17. Modeling HIV Cure

    NASA Astrophysics Data System (ADS)

    Perelson, Alan; Conway, Jessica; Cao, Youfang

    A large effort is being made to find a means to cure HIV infection. I will present a dynamical model of post-treatment control (PTC) or ``functional cure'' of HIV-infection. Some patients treated with suppressive antiviral therapy have been taken off of therapy and then spontaneously control HIV infection such that the amount of virus in the circulation is maintained undetectable by clinical assays for years. The model explains PTC occurring in some patients by having a parameter regime in which the model exhibits bistability, with both a low and high steady state viral load being stable. The model makes a number of predictions about how to attain the low PTC steady state. Bistability in this model depends upon the immune response becoming exhausted when over stimulated. I will also present a generalization of the model in which immunotherapy can be used to reverse immune exhaustion and compare model predictions with experiments in SIV infected macaques given immunotherapy and then taken off of antiretroviral therapy. Lastly, if time permits, I will discuss one of the hurdles to true HIV eradication, latently infected cells, and present clinical trial data and a new model addressing pharmacological means of flushing out the latent reservoir. Supported by NIH Grants AI028433 and OD011095.

  18. Heteroscedastic transformation cure regression models.

    PubMed

    Chen, Chyong-Mei; Chen, Chen-Hsin

    2016-06-30

    Cure models have been applied to analyze clinical trials with cures and age-at-onset studies with nonsusceptibility. Lu and Ying (On semiparametric transformation cure model. Biometrika 2004; 91:331?-343. DOI: 10.1093/biomet/91.2.331) developed a general class of semiparametric transformation cure models, which assumes that the failure times of uncured subjects, after an unknown monotone transformation, follow a regression model with homoscedastic residuals. However, it cannot deal with frequently encountered heteroscedasticity, which may result from dispersed ranges of failure time span among uncured subjects' strata. To tackle the phenomenon, this article presents semiparametric heteroscedastic transformation cure models. The cure status and the failure time of an uncured subject are fitted by a logistic regression model and a heteroscedastic transformation model, respectively. Unlike the approach of Lu and Ying, we derive score equations from the full likelihood for estimating the regression parameters in the proposed model. The similar martingale difference function to their proposal is used to estimate the infinite-dimensional transformation function. Our proposed estimating approach is intuitively applicable and can be conveniently extended to other complicated models when the maximization of the likelihood may be too tedious to be implemented. We conduct simulation studies to validate large-sample properties of the proposed estimators and to compare with the approach of Lu and Ying via the relative efficiency. The estimating method and the two relevant goodness-of-fit graphical procedures are illustrated by using breast cancer data and melanoma data. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26887342

  19. A New Kind of Curing

    NASA Technical Reports Server (NTRS)

    2001-01-01

    A new curing method using automated tape placement (ATP) with electron beam (EB), or e-beam, produces a combination known as in situ e-beam curing. Through a Small Business Innovation Research (SBIR) contract from NASA's Marshall Space Flight Center, Science Research Laboratory, Inc., created the in situ e-beam curing technique, which uses a low-energy electron beam gun to cure various composite materials. One important benefit is the technique's utilization of room temperature curing, which lessens the chance of mismatching the thermal expansion coefficients of different materials. For instance, metals and composites will expand at different rates when heated, but the low-energy e-beam gun reduces the expansion differential. Using a low-energy gun also results in less x-ray shielding, significantly reduced capital costs, reduced facility space, and increased processing capabilities for larger parts. However, using a low-energy gun also means that each tape layer is treated individually because the gun can penetrate only one layer at a time. The e-beam gun emits lower energy x-rays, which are more easily shielded than those emitted by previous guns. The low-energy system is relatively portable due to its light weight and small size. The gun weighs about 70 pounds and can be easily mounted on a robotic arm or an ATP head.

  20. Continuous Glucose Monitors and the Burden of Tight Glycemic Control in Critical Care: Can They Cure the Time Cost?

    PubMed Central

    Signal, Matthew; Pretty, Christopher G.; Chase, J. Geoffrey; Le Compte, Aaron; Shaw, Geoffrey M.

    2010-01-01

    Background Tight glycemic control (TGC) in critical care has shown distinct benefits but has also proven to be difficult to obtain. The risk of severe hypoglycemia (<40 mg/dl) raises significant concerns for safety. Added clinical burden has also been an issue. Continuous glucose monitors (CGMs) offer frequent automated measurement and thus the possibility of using them for early detection and intervention of hypoglycemic events. Additionally, regular measurement by CGM may also be able to reduce clinical burden. Aim An in silico study investigates the potential of CGM devices to reduce clinical effort in a published TGC protocol. Methods This study uses retrospective clinical data from the Specialized Relative Insulin Nutrition Titration (SPRINT) TGC study covering 20 patients from a benchmark cohort. Clinically validated metabolic system models are used to generate a blood glucose (BG) profile for each patient, resulting in 33 continuous, separate BG episodes (6881 patient hours). The in silico analysis is performed with three different stochastic noise models: two Gaussian and one first-order autoregressive. The noisy, virtual CGM BG values are filtered and used to drive the SPRINT TGC protocol. A simple threshold alarm is used to trigger glucose interventions to avert potential hypoglycemia. The Monte Carlo method was used to get robust results from the stochastic noise models. Results Using SPRINT with simulated CGM noise, the BG time in an 80–110 mg/dl band was reduced no more than 4.4% to 45.2% compared to glucometer sensors. Antihypoglycemic interventions had negligible effect on time in band but eliminated all recorded hypoglycemic episodes in these simulations. Assuming 4–6 calibration measurements per day, the nonautomated clinical measurements are reduced from an average of 16 per day to as low as 4. At 2.5 min per glucometer measurement, a daily saving of ∼25–30 min per patient could potentially be achieved. Conclusions This paper has analyzed

  1. Real-time optical pH measurement in a standard microfluidic cell culture system.

    PubMed

    Magnusson, Einar B; Halldorsson, Skarphedinn; Fleming, Ronan M T; Leosson, Kristjan

    2013-01-01

    The rapid growth of microfluidic cell culturing in biological and biomedical research and industry calls for fast, non-invasive and reliable methods of evaluating conditions such as pH inside a microfluidic system. We show that by careful calibration it is possible to measure pH within microfluidic chambers with high accuracy and precision, using a direct single-pass measurement of light absorption in a commercially available phenol-red-containing cell culture medium. The measurement is carried out using a standard laboratory microscope and, contrary to previously reported methods, requires no modification of the microfluidic device design. We demonstrate the validity of this method by measuring absorption of light transmitted through 30-micrometer thick microfluidic chambers, using an inverted microscope fitted with a scientific-grade digital camera and two bandpass filters. In the pH range of 7-8, our measurements have a standard deviation and absolute error below 0.05 for a measurement volume smaller than 4 nL. PMID:24049695

  2. Radiation curing of epoxies

    NASA Astrophysics Data System (ADS)

    Dickson, Lawrence W.; Singh, Ajit

    The literature on radiation polymerization of epoxy compounds has been reviewed to assess the potential use of radiation for curing these industrially important monomers. Chemical curing of epoxies may proceed by either cationic or anionic mechanisms depending on the nature of the curing agent, but most epoxies polymerize by cationic mechanisms under the influence of high-energy radiation. Radiation-induced cationic polymerization of epoxy compounds is inhibited by trace quantities of water because of proton transfer from the chain-propagating epoxy cation to water. Several different methods with potential for obtaining high molecular weight polymers by curing epoxies with high-energy radiation have been studied. Polymeric products with epoxy-like properties have been produced by radiation curing of epoxy oligomers with terminal acrylate groups and mixtures of epoxies with vinyl monomers. Both of these types of resin have good potential for industrial-scale curing by radiation treatment.

  3. RTEMIS: Real-time Tumoroid and Environment Monitoring Using Impedance Spectroscopy and pH Sensing

    NASA Astrophysics Data System (ADS)

    Alexander, Frank A., Jr.

    This research utilizes Electrical Impedance Spectroscopy, a technique classically used for electrochemical analysis and material characterization, as the basis for a non-destructive, label-free assay platform for three dimensional (3D) cellular spheroids. In this work, a linear array of microelectrodes is optimized to rapidly respond to changes located within a 3D multicellular model. In addition, this technique is coupled with an on chip micro-pH sensor for monitoring the environment around the cells. Finally, the responses of both impedance and pH are correlated with physical changes within the cellular model. The impedance analysis system realized through this work provides a foundation for the development of high-throughput drug screening systems that utilize multiple parallel sensing modalities including pH and impedance sensing in order to quickly assess the efficacy of specific drug candidates. The slow development of new drugs is mainly attributed to poor predictability of current chemosensitivity and resistivity assays, as well as genetic differences between the animal models used for tests and humans. In addition, monolayer cultures used in early experimentation are fundamentally different from the complex structure of organs in vivo. This requires the study of smaller 3D models (spheroids) that more efficiently replicate the conditions within the body. The main objective of this research was to develop a microfluidic system on a chip that is capable of deducing viability and morphology of 3D tumor spheroids by monitoring both the impedance of the cellular model and the pH of their local environment. This would provide a fast and reliable method for screening pharmaceutical compounds in a high-throughput system.

  4. It's time for a change in the way we educate physiology PhD candidates.

    PubMed

    Tallitsch, R B

    1996-12-01

    Graduate students in physiology programs today are faced with a job market that is significantly different from that which many of us faced 25, 10, or even 5 years ago. As a result, physiology educators need to change the content and style of their programs to prepare graduates for their futures. Programs must continue to prepare graduates for research postdoctoral positions, but they also should prepare them for employment at smaller institutions that have higher teaching demands and that encourage, but do not require, research. Changes are suggested in the way PhD candidates are taught and in the way professors mentor students seeking employment at smaller institutions. PMID:8997411

  5. Colon-targeted delivery of budesonide using dual pH- and time-dependent polymeric nanoparticles for colitis therapy

    PubMed Central

    Naeem, Muhammad; Choi, Moonjeong; Cao, Jiafu; Lee, Yujeong; Ikram, Muhammad; Yoon, Sik; Lee, Jaewon; Moon, Hyung Ryong; Kim, Min-Soo; Jung, Yunjin; Yoo, Jin-Wook

    2015-01-01

    Single pH-dependent drug delivery systems have been widely used for colon-targeted delivery, but their efficiency is often hampered by the variation in gut pH. To overcome the limitation of single pH-dependent delivery systems, in this study, we developed and evaluated the therapeutic potential of budesonide-loaded dual pH/time-dependent nanoparticles (NPs) for the treatment of colitis. Eudragit FS30D was used as a pH-dependent polymer, and Eudragit RS100 as a time-dependent controlled release polymer. Single pH-dependent NPs (pH_NPs), single time-dependent NPs (Time_NPs), and dual pH/time-dependent NPs (pH/Time_NPs) were prepared using the oil-in-water emulsion method. The physicochemical properties and drug release profiles of these NPs in gastrointestinal (GI) tract conditions were investigated. The therapeutic potential and in vivo distribution of the NPs were evaluated in a dextran sulfate sodium (DSS)-induced colitis mice model. The pH/Time_NPs prevented a burst drug release in acidic pH conditions and showed sustained release at a colonic pH. The in vivo distribution study in the mice GI tract demonstrated that pH/Time_NPs were more efficiently delivered to the inflamed colon than pH_NPs were. Compared to the single pH_NPs-treated group, the pH/Time_NPs-treated group showed increased body weight and colon length and markedly decreased disease activity index, colon weight/length ratios, histological damage, and inflammatory cell infiltration in colon tissue. Our results demonstrate that the dual pH/time-dependent NPs are an effective oral colon-targeted delivery system for colitis therapy. PMID:26229440

  6. Colon-targeted delivery of budesonide using dual pH- and time-dependent polymeric nanoparticles for colitis therapy.

    PubMed

    Naeem, Muhammad; Choi, Moonjeong; Cao, Jiafu; Lee, Yujeong; Ikram, Muhammad; Yoon, Sik; Lee, Jaewon; Moon, Hyung Ryong; Kim, Min-Soo; Jung, Yunjin; Yoo, Jin-Wook

    2015-01-01

    Single pH-dependent drug delivery systems have been widely used for colon-targeted delivery, but their efficiency is often hampered by the variation in gut pH. To overcome the limitation of single pH-dependent delivery systems, in this study, we developed and evaluated the therapeutic potential of budesonide-loaded dual pH/time-dependent nanoparticles (NPs) for the treatment of colitis. Eudragit FS30D was used as a pH-dependent polymer, and Eudragit RS100 as a time-dependent controlled release polymer. Single pH-dependent NPs (pH_NPs), single time-dependent NPs (Time_NPs), and dual pH/time-dependent NPs (pH/Time_NPs) were prepared using the oil-in-water emulsion method. The physicochemical properties and drug release profiles of these NPs in gastrointestinal (GI) tract conditions were investigated. The therapeutic potential and in vivo distribution of the NPs were evaluated in a dextran sulfate sodium (DSS)-induced colitis mice model. The pH/Time_NPs prevented a burst drug release in acidic pH conditions and showed sustained release at a colonic pH. The in vivo distribution study in the mice GI tract demonstrated that pH/Time_NPs were more efficiently delivered to the inflamed colon than pH_NPs were. Compared to the single pH_NPs-treated group, the pH/Time_NPs-treated group showed increased body weight and colon length and markedly decreased disease activity index, colon weight/length ratios, histological damage, and inflammatory cell infiltration in colon tissue. Our results demonstrate that the dual pH/time-dependent NPs are an effective oral colon-targeted delivery system for colitis therapy. PMID:26229440

  7. Predictors of full-time faculty appointment among MD–PhD program graduates: a national cohort study

    PubMed Central

    Andriole, Dorothy A.; Jeffe, Donna B.

    2016-01-01

    Purpose The authors sought to identify variables associated with MD–PhD program graduates’ academic medicine careers. Methods We analyzed data for a national cohort of MD–PhD program graduates from 2000 to 2005, using multivariable logistic regression to identify independent predictors of full-time academic medicine faculty appointment through 2013. Results Of 1,860 MD–PhD program graduates in 2000–2005, we included 1,846 (99.2%) who had completed residency training before 2014. Of these 1,846 graduates, 968 (52.4%) held full-time faculty appointments. Graduates who attended schools with Medical Scientist Training Program (MSTP) funding (vs. no MSTP funding; adjusted odds ratio [aOR], 1.41; 95% confidence interval [CI], 1.14–1.74) and participated in ≥1 year of research during residency (vs. no documented research year; aOR, 1.85; 95% CI, 1.50–2.28) were more likely to have held full-time faculty appointments. Asian/Pacific Islander (aOR, 0.74; 95% CI, 0.60–0.93) and under-represented minority (URM; aOR, 0.68; 95% CI, 0.48–0.98) graduates (each vs. white graduates), graduates who reported total debt of ≥$100,000 (vs. no debt) at graduation (aOR, 0.58; 95% CI, 0.39–0.88), and graduates in surgical practice (aOR, 0.64; 95% CI, 0.48–0.84) and other practice (aOR, 0.66, 95% CI, 0.54–0.81) specialties (each vs. ‘medicine, pediatrics, pathology, or neurology’) were less likely to have held full-time faculty appointments. Gender was not independently associated with likelihood of full-time faculty appointment. Conclusions Over half of all MD–PhD program graduates in our study had full-time faculty appointments. Our findings regarding variables independently associated with full-time faculty appointments can inform the design of strategies to promote academic medicine career choice among MD–PhD program graduates. Further research is warranted to identify other factors amenable to intervention, in addition to those included in our study

  8. Short communication: The effect of storage conditions over time on bovine colostral immunoglobulin G concentration, bacteria, and pH.

    PubMed

    Cummins, C; Lorenz, I; Kennedy, E

    2016-06-01

    The objective of the present study was to measure the effect of storing colostrum in different conditions for varying amounts of time on IgG concentration, bacteria, and pH. In experiment 1, colostrum from 12 Holstein-Friesian cows (6 primiparous and 6 multiparous) was collected within 3h of calving, and colostrum from another 12 multiparous cows was collected within 3h of calving (6 cows) and >9h postpartum (6 cows). Aliquots were refrigerated or stored at room temperature for up to 72h, depending on treatment. In experiment 2, colostrum was collected from 6 multiparous cows within 9h of calving, and aliquots were stored for up to 72h in temperature-controlled units set at 4, 13, and 20°C. All colostrum samples were analyzed for IgG concentration, total bacteria count, and pH after 0, 6, 12, 24, 36, 48, 60, and 72h of storage. Storage conditions did not affect the IgG concentration of colostrum. Bacterial growth was most rapid in the first 6h of storage, reducing thereafter, but bacteria multiplied at a significantly greater rate when stored in warmer conditions (i.e., >4°C). The pH of colostrum was not significantly altered when stored at temperatures <13°C, but when stored at 20°C the pH significantly decreased after 24h of storage. Storing colostrum in warmer conditions significantly alters both total bacteria count and pH; consequently, colostrum should be stored at ≤4°C. PMID:26995126

  9. Nonpost mold cure compound

    NASA Astrophysics Data System (ADS)

    Hirata, Akihiro

    1997-08-01

    The recent low price trend of electronic products has made IC manufacturing efficiency a top priority in the semiconductor industry. Post mold cure (PMC) process, which generally involves heating the packages in the oven at 175 C for 4 to 8 hours, takes up much longer time than most other assembly processes. If this PMC process can be reduced or eliminated, semiconductor makers will be rewarded with a much higher cost merit. We define the purpose of Non-PMC as 'to get high reliability with suitable physical and electrical properties without PMC'. We compared carious properties of molding compound before and after PMC. We found that curing reaction has almost complete through DSC and C-NMR measurement, but several properties have not stabilized yet, and that not all properties after PMC were better than before PMC. We developed new grade of molding compound considering these facts. And we found that main factors to accomplish non-PMC compound are curability and flowability, and more, increasing of fundamental properties. To accomplish non-PMC, at first, molding compound need to have very high curability. Generally speaking, too high curability causes low flowability, and causes incomplete filing, wire sweep, pad shift, and weak adhesion to inner parts of IC packages. To prevent these failures, various compound properties were studied, and we achieved in adding good flowability to very high curable molding compound. Finally, anti-popcorn property was improved by adding low moisture, high adhesion, high Tg, and high flexural strengths at high temperature. Through this study, we developed new compound grade for various package, especially large QFP using standard ECN resin.

  10. Dry-cured ham restructured with fibrin.

    PubMed

    Romero de Ávila, M D; Hoz, L; Ordóñez, J A; Cambero, M I

    2014-09-15

    The viability of a fibrinogen-thrombin system (FT) to bind fresh deboned hams for incorporation in the salting and ripening processes, to produce cured ham, was studied. The effects of the different processing variables (pH, NaCl concentration, temperature and gelation time) on FT, a meat emulsion mixed with FT, fresh pork portions and deboned hams restructured with FT were analyzed. The most stable and firmest fibrin gels were obtained after 6h of adding the FT, with less than 2% NaCl and pH 7-8.4. Scanning electron microscopy of the fibrin gel showed fibrillar structures with a high degree of cross-linking and a high density. Two structures were found in the binding area of restructured meat; one in the central part with similar characteristics to fibrin gels and, another in the area of contact between the meat surfaces, where a filamentous structure connected the fibrin gels with the muscle bundles. PMID:24767091

  11. Cationic cure kinetics of a polyoxometalate loaded epoxy nanocomposite

    SciTech Connect

    Anderson, Benjamin J.

    2012-08-06

    The reaction cure kinetics of a novel polyoxometalate (POM) loaded epoxy nanocomposite is described. The POM is dispersed in the epoxy resin up to volume fractions of 0.1. Differential scanning calorimetry measurements show the cure of the epoxy resin to be sensitive to the POM loading. A kinetics study of the cure exotherm confirms that POM acts as a catalyst promoting cationic homopolymerization of the epoxy resin. The cure reaction is shown to propagate through two cure regimes. A fast cure at short time is shown to be propagation by the activated chain end (ACE) mechanism. A slow cure at long time is shown to be propagation by the activated monomer (AM) mechanism. The activation energies for the fast and slow cure regimes agree well with other epoxy based systems that have been confirmed to propagate by the ACE and AM mechanisms.

  12. Improved cure method for single component silicone rubber

    NASA Technical Reports Server (NTRS)

    Lippitt, M. W.

    1969-01-01

    Water is incorporated in a carrier and then thoroughly mixed with the single component silicone rubber containing acetic anhydride as a curing agent. Because curing occurs with the water supplied internally, controlled curing is possible within a reasonable period of time, regardless of the thickness of the material.

  13. Silicone rubber curing by high intensity infrared radiation

    SciTech Connect

    Huang, T.; Tsai, J.; Cherng, C.; Chen, J.

    1994-08-10

    A high-intensity (12 kW) and compact (80 cm) infrared heating oven for fast curing (12 seconds) of tube-like silicone rubber curing studies is reported. Quality inspection by DSC and DMA and results from pilot-scale curing oven all suggest that infrared heating provides a better way of vulcanization regarding to curing time, quality, cost, and spacing over conventional hot air heating. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  14. Electron Beam Curing of Polymer Matrix Composites - CRADA Final Report

    SciTech Connect

    Janke, C. J.; Howell, Dave; Norris, Robert E.

    1997-05-01

    The major cost driver in manufacturing polymer matrix composite (PMC) parts and structures, and one of the elements having the greatest effect on their quality and performance, is the standard thermal cure process. Thermal curing of PMCs requires long cure times and high energy consumption, creates residual thermal stresses in the part, produces volatile toxic by-products, and requires expensive tooling that is tolerant of the high cure temperatures.

  15. Effect of light-cure initiation time on polymerization and orthodontic bond strength with a resin-modified glass-ionomer

    NASA Astrophysics Data System (ADS)

    Thomas, Jess

    Introduction: The polymerization and acid-base reactions in resin-modified glass-ionomers (RMGI) are thought to compete with and inhibit one another. The objective of this study was to examine the effect of visible light-cure (VLC) delay on the polymerization efficiency and orthodontic bond strength of a dual-cured RMGI. Methods: An RMGI light-cured immediately, 2.5, 5, or 10 minutes after mixing comprised the experimental groups. Isothermal and dynamic temperature scan differential scanning calorimetry (DSC) analysis of the RMGI was performed to determine extents of VLC polymerization and acid-base reaction exotherms. Human premolars (n = 18/group) were bonded with the RMGI. Shear bond strength and adhesive remnant index (ARI) scores were determined. Results: DSC results showed the 10 minute delay RMGI group experienced significantly (P <0.05) lower VLC polymerization compared to the other groups. Acid-base reaction exotherms were undetected in all groups except the 10 minute delay group. No significant differences (P >0.05) were noted among the groups for mean shear bond strength. A chi-square test showed no significant difference (P = 0.428) in ARI scores between groups. Conclusions: Delay in light-curing may reduce polymerization efficiency and alter the structure of the RMGI, but orthodontic shear bond strength does not appear to be compromised.

  16. A cure for dyslexia?

    PubMed

    2007-02-01

    A company is promoting behavioral exercises as a cure for dyslexia. Scientists worry that evaluation of the program is compromised by design flaws and conflicts of interest and that responses to critics restrict academic freedom. PMID:17259957

  17. Temporal Adjustment in Academic Labor Markets: Time to Ph.D. AIR Forum Paper 1978.

    ERIC Educational Resources Information Center

    Kuh, Charlotte V.

    A research project is described that concerns "temporal adjustment" as one form of a non-wage adjustment in the academic labor market. Receipt of the doctorate, the number and length of post-doctoral fellowships, and the achievement of tenure are temporal factors in academic careers. The change in timing of these factors is a form of adjustment to…

  18. Real time identification of large space structures. Ph.D. Thesis - MIT

    NASA Technical Reports Server (NTRS)

    Voss, Janice E.

    1987-01-01

    Identification of frequencies, damping ratios, and mode shapes of large space structures (LSSs) are examined in real time. Real time processing allows for quick updates of model processing after a reconfiguration of structural failure. Recursive lattice least squares (RLLS) was selected as the baseline algorithm for the identification. Simulation results on a one dimensional LSS demonstrated that it provides good estimates, was not ill-conditioned in the presence of under-excited modes, allowed activity by a supervisory control system which prevented damage to the LSS or excessive drift, and was capable of real-time processing for typical LSS models. A suboptimal version of RLLS, which is equivalent to simulated parallel processing, was derived. A NASTRAN model of the dual keel U.S. space station was used to demonstrate the input/identification algorithm package in a more realistic simulation. Because the first eight flexible modes were very close together, the identification was much more difficult than in the simple examples. Even so, the model was accurately identified in real time.

  19. Real-time intravital imaging of pH variation associated with osteoclast activity.

    PubMed

    Maeda, Hiroki; Kowada, Toshiyuki; Kikuta, Junichi; Furuya, Masayuki; Shirazaki, Mai; Mizukami, Shin; Ishii, Masaru; Kikuchi, Kazuya

    2016-08-01

    Intravital imaging by two-photon excitation microscopy (TPEM) has been widely used to visualize cell functions. However, small molecular probes (SMPs), commonly used for cell imaging, cannot be simply applied to intravital imaging because of the challenge of delivering them into target tissues, as well as their undesirable physicochemical properties for TPEM imaging. Here, we designed and developed a functional SMP with an active-targeting moiety, higher photostability, and a fluorescence switch and then imaged target cell activity by injecting the SMP into living mice. The combination of the rationally designed SMP with a fluorescent protein as a reporter of cell localization enabled quantitation of osteoclast activity and time-lapse imaging of its in vivo function associated with changes in cell deformation and membrane fluctuations. Real-time imaging revealed heterogenic behaviors of osteoclasts in vivo and provided insights into the mechanism of bone resorption. PMID:27272564

  20. Stability and Relative Stability of Linear Systems with Many Constant Time Delays. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Barker, Larry Keith

    1976-01-01

    A method of determining the stability of linear systems with many constant time delays is developed. This technique, an extension of the tau-decomposition method, is used to examine not only the stability but also the relative stability of retarded systems with many delays and a class of neutral equations with one delay. Analytical equations are derived for partitioning the delay space of a retarded system with two time delays. The stability of the system in each of the regions defined by the partitioning curves in the parameter plane is determined using the extended tau-decomposition method. In addition, relative stability boundaries are defined using the extended tau-decompositon method in association with parameter plane techniques. Several applications of the extended tau-decomposition method are presented and compared with stability results obtained from other analyses. In all cases the results obtained using the method outlined herein coincide with and extend those of previous investigations. The extended tau-decomposition method applied to systems with time delays requires less computational effort and yields more complete stability analyses than previous techniques.

  1. Time-dependent pH sensing phenomena using CdSe/ZnS quantum dots in EIS structure

    PubMed Central

    2014-01-01

    Time-dependent pH sensing phenomena of the core-shell CdSe/ZnS quantum dot (QD) sensors in EIS (electrolyte insulator semiconductor) structure have been investigated for the first time. The quantum dots are immobilized by chaperonin GroEL protein, which are observed by both atomic force microscope and scanning electron microscope. The diameter of one QD is approximately 6.5 nm. The QDs are not oxidized over a long time and core-shell CdSe/ZnS are confirmed by X-ray photon spectroscopy. The sensors are studied for sensing of hydrogen ions concentration in different buffer solutions at broad pH range of 2 to 12. The QD sensors show improved sensitivity (38 to 55 mV/pH) as compared to bare SiO2 sensor (36 to 23 mV/pH) with time period of 0 to 24 months, owing to the reduction of defects in the QDs. Therefore, the differential sensitivity of the QD sensors with respect to the bare SiO2 sensors is improved from 2 to 32 mV/pH for the time period of 0 to 24 months. After 24 months, the sensitivity of the QD sensors is close to ideal Nernstian response with good linearity of 99.96%. Stability and repeatability of the QD sensors show low drift (10 mV for 10 cycles) as well as small hysteresis characteristics (<10 mV). This QD sensor is very useful for future human disease diagnostics. PMID:24725352

  2. Time dependent deformation and stress in the lithosphere. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Yang, M.

    1980-01-01

    Efficient computer programs incorporating frontal solution and time stepping procedure were developed for the modelling of geodynamic problems. This scheme allows for investigating the quasi static phenomena including the effects of the rheological structure of a tectonically active region. From three dimensional models of strike slip earthquakes, it was found that lateral variation of viscosity affects the characteristics of surface deformations. The vertical deformation is especially informative about the viscosity structure in a strike slip fault zone. A three dimensional viscoelastic model of a thrust earthquake indicated that the transient disturbance on plate velocity due to a great plate boundary earthquake is significant at intermediate distances, but becomes barely measurable 1000 km away from the source.

  3. Rate and time dependent behavior of structural adhesives. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Renieri, M. P.; Herakovich, C. T.; Brinson, H. F.

    1976-01-01

    Studies on two adhesives (Metlbond 1113 and 1113-2) identified as having applications in the bonding of composite materials are presented. Constitutive equations capable of describing changes in material behavior with strain rate are derived from various theoretical approaches. It is shown that certain unique relationships exist between these approaches. It is also shown that the constitutive equation derived from mechanical models can be used for creep and relaxation loading. A creep to failure phenomenon is shown to exist and is correlated with a delayed yield equation proposed by Crochet. Loading-unloading results are presented and are shown to correlate well with the proposed form of the loading-unloading equations for the modified Bingham model. Experimental results obtained for relaxation tests above and below the glass transition temperature are presented. It is shown that the adhesives obey the time-temperature superposition principle.

  4. Psychophysical Models for Signal Detection with Time Varying Uncertainty. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Gai, E.

    1975-01-01

    Psychophysical models for the behavior of the human operator in detection tasks which include change in detectability, correlation between observations and deferred decisions are developed. Classical Signal Detection Theory (SDT) is discussed and its emphasis on the sensory processes is contrasted to decision strategies. The analysis of decision strategies utilizes detection tasks with time varying signal strength. The classical theory is modified to include such tasks and several optimal decision strategies are explored. Two methods of classifying strategies are suggested. The first method is similar to the analysis of ROC curves, while the second is based on the relation between the criterion level (CL) and the detectability. Experiments to verify the analysis of tasks with changes of signal strength are designed. The results show that subjects are aware of changes in detectability and tend to use strategies that involve changes in the CL's.

  5. Pharmacokinetics of colon-specific pH and time-dependent flurbiprofen tablets.

    PubMed

    Vemula, Sateesh Kumar; Veerareddy, Prabhakar Reddy; Devadasu, Venkat Ratnam

    2015-09-01

    Present research deals with the development of compression-coated flurbiprofen colon-targeted tablets to retard the drug release in the upper gastro intestinal system, but progressively release the drug in the colon. Flurbiprofen core tablets were prepared by direct compression method and were compression coated using sodium alginate and Eudragit S100. The formulation is optimized based on the in vitro drug release study and further evaluated by X-ray imaging and pharmacokinetic studies in healthy humans for colonic delivery. The optimized formulation showed negligible drug release (4.33 ± 0.06 %) in the initial lag period followed by progressive release (100.78 ± 0.64 %) for 24 h. The X-ray imaging in human volunteers showed that the tablets reached the colon without disintegrating in the upper gastrointestinal tract. The C max of colon-targeted tablets was 12,374.67 ng/ml at T max 10 h, where as in case of immediate release tablets the C max was 15,677.52 ng/ml at T max 3 h, that signifies the ability of compression-coated tablets to target the colon. Development of compression-coated tablets using combination of time-dependent and pH-sensitive approaches was suitable to target the flurbiprofen to colon. PMID:24916715

  6. What Cure Models Can Teach us About Genome-Wide Survival Analysis.

    PubMed

    Stringer, Sven; Denys, Damiaan; Kahn, René S; Derks, Eske M

    2016-03-01

    The aim of logistic regression is to estimate genetic effects on disease risk, while survival analysis aims to determine effects on age of onset. In practice, genetic variants may affect both types of outcomes. A cure survival model analyzes logistic and survival effects simultaneously. The aim of this simulation study is to assess the performance of logistic regression and traditional survival analysis under a cure model and to investigate the benefits of cure survival analysis. We simulated data under a cure model and varied the percentage of subjects at risk for disease (cure fraction), the logistic and survival effect sizes, and the contribution of genetic background risk factors. We then computed the error rates and estimation bias of logistic, Cox proportional hazards (PH), and cure PH analysis, respectively. The power of logistic and Cox PH analysis is sensitive to the cure fraction and background heritability. Our results show that traditional Cox PH analysis may erroneously detect age of onset effects if no such effects are present in the data. In the presence of genetic background risk even the cure model results in biased estimates of both the odds ratio and the hazard ratio. Cure survival analysis takes cure fractions into account and can be used to simultaneously estimate the effect of genetic variants on disease risk and age of onset. Since genome-wide cure survival analysis is not computationally feasible, we recommend this analysis for genetic variants that are significant in a traditional survival analysis. PMID:26552795

  7. Energy curable compositions having improved cure speeds

    DOEpatents

    Halm, L.W.

    1993-05-18

    The composition and method provide improved physical properties and cure speed of polyurethane precursors, with or without free radical polymerizable monomers or oligomers present, by use of a two component catalyst system. The resin blend can be activated with a latent organometallic catalyst combined with an organic peroxide which can be a hydroperoxide or an acyl peroxide to decrease the cure time while increasing the break energy and tangent modulus of the system.

  8. Energy curable compositions having improved cure speeds

    DOEpatents

    Halm, Leo W.

    1993-01-01

    A composition and method provide improved physical properties and cure speed of polyurethane precursors, with or without free radical polymerizable monomers or oligomers present, by use of a two component catalyst system. The resin blend can be activated with a latent organometallic catalyst combined with an organic peroxide which can be a hydroperoxide or an acyl peroxide to decrease the cure time while increasing the break energy and tangent modulus of the system.

  9. Tracking Polymer Cure Via Embedded Optical Fibers

    NASA Technical Reports Server (NTRS)

    Dean, David L.; Davidson, T. Fred

    1993-01-01

    Fourier-transform infrared spectroscopy applied in interior of specimen of material by bringing infrared light through specimen in optical fiber. Light interacts with material via evanescent-wave effect. Spectra obtained in this way at various times during curing process also combined with data from ultrasonic, thermographic, and dielectric-impedance monitoring, and other measurement techniques to obtain more complete characterization of progress of curing process.

  10. Development of a downhole tool measuring real-time concentration of ionic tracers and pH in geothermal reservoirs

    NASA Astrophysics Data System (ADS)

    Hess, Ryan F.; Boyle, Timothy J.; Limmer, Steven; Yelton, William G.; Bingham, Samuel; Stillman, Greg; Lindblom, Scott; Cieslewski, Grzegorz

    2014-06-01

    For enhanced or Engineered Geothermal Systems (EGS) geothermal brine is pumped to the surface via the production wells, the heat extracted to turn a turbine to generate electricity, and the spent brine re-injected via injection wells back underground. If designed properly, the subsurface rock formations will lead this water back to the extraction well as heated brine. Proper monitoring of these geothermal reservoirs is essential for developing and maintaining the necessary level of productivity of the field. Chemical tracers are commonly used to characterize the fracture network and determine the connectivity between the injection and production wells. Currently, most tracer experiments involve injecting the tracer at the injection well, manually collecting liquid samples at the wellhead of the production well, and sending the samples off for laboratory analysis. While this method provides accurate tracer concentration data at very low levels of detection, it does not provide information regarding the location of the fractures which were conducting the tracer between wellbores. Sandia is developing a high-temperature electrochemical sensor capable of measuring tracer concentrations and pH downhole on a wireline tool. The goal of this effort is to collect real-time pH and ionic tracer concentration data at temperatures up to 225 °C and pressures up to 3000 psi. In this paper, a prototype electrochemical sensor and the initial data obtained will be presented detailing the measurement of iodide tracer concentrations at high temperature and pressure in a newly developed laboratory scale autoclave.

  11. Mapping the pharyngeal and intestinal pH of Caenorhabditis elegans and real-time luminal pH oscillations using extended dynamic range pH-sensitive nanosensors.

    PubMed

    Chauhan, Veeren M; Orsi, Gianni; Brown, Alan; Pritchard, David I; Aylott, Jonathan W

    2013-06-25

    Extended dynamic range pH-sensitive ratiometric nanosensors, capable of accurately mapping the full physiological pH range, have been developed and used to characterize the pH of the pharyngeal and intestinal lumen of Caenorhabditis elegans in real-time. Nanosensors, 40 nm in diameter, were prepared by conjugating pH-sensitive fluorophores, carboxyfluorescein (FAM) and Oregon Green (OG) in a 1:1 ratio, and a reference fluorophore, 5-(and-6)-carboxytetramethylrhodamine (TAMRA) to an inert polyacrylamide matrix. Accurate ratiometric pH measurements were calculated through determination of the fluorescence ratio between the pH-sensitive and reference fluorophores. Nanosensors were calibrated with an automated image analysis system and validated to demonstrate a pH measurement resolution of ±0.17 pH units. The motility of C. elegans populations, as an indicator for viability, showed nematodes treated with nanosensors, for concentrations ranging from 50.00 to 3.13 mg/mL, were not statistically different to nematodes not challenged with nanosensors up to a period of 4 days (p < 0.05). The nanosensors were also found to remain in the C. elegans lumen >24 h after nanosensor challenge was removed. The pH of viable C. elegans lumen was found to range from 5.96 ± 0.31 in the anterior pharynx to 3.59 ± 0.09 in the posterior intestine. The pharyngeal pumping rate, which dictates the transfer of ingested material from the pharynx to the intestine, was found to be temperature dependent. Imaging C. elegans at 4 °C reduced the pharyngeal pumping rate to 7 contractions/min and enabled the reconstruction of rhythmic pH oscillations in the intestinal lumen in real-time with fluorescence microscopy. PMID:23668893

  12. Radiation curing: Science and technology

    SciTech Connect

    Pappas, S.P.

    1992-01-01

    The science and technology of radiation curing have progressed substantially within the last 20 years. Nevertheless, radiation-curable compositions typically command relatively small shares in many of their competitive markets. This situation signifies that potential advantages of radiation curing are not generally perceived to overcome their limitations. An important objective of this book is to address this issue, within the scope of the subjects offered, by providing the present state of knowledge and by identifying the directions and challenges for future studies. The first chapter introduces radiation curing. Chapter 2 offers the first systematic presentation of inorganic and organometallic photoinitiators. Chapters 3 and 4 present the analytical techniques of photocalorimetry and real-time infrared spectroscopy, respectively. Recent advances in resin technology are offered in Chapters 5 and 6, which constitute the first comprehensive accounts of (meth)acrylated silicones and vinyl ethers, respectively. Radiation-curable coatings, printing inks, and adhesives are discussed in Chapters 7-9, respectively. Chapter 10 offers a discussion on photopolymer imaging systems.

  13. Reflection-mode micro-spherical fiber-optic probes for in vitro real-time and single-cell level pH sensing

    PubMed Central

    Yang, Qingbo; Wang, Hanzheng; Lan, Xinwei; Cheng, Baokai; Chen, Sisi; Shi, Honglan; Xiao, Hai; Ma, Yinfa

    2014-01-01

    pH sensing at the single-cell level without negatively affecting living cells is very important but still a remaining issue in the biomedical studies. A 70 μm reflection-mode fiber-optic micro-pH sensor was designed and fabricated by dip-coating thin layer of organically modified aerogel onto a tapered spherical probe head. A pH sensitive fluorescent dye 2′, 7′-Bis (2-carbonylethyl)-5(6)-carboxyfluorescein (BCECF) was employed and covalently bonded within the aerogel networks. By tuning the alkoxide mixing ratio and adjusting hexamethyldisilazane (HMDS) priming procedure, the sensor can be optimized to have high stability and pH sensing ability. The in vitro real-time sensing capability was then demonstrated in a simple spectroscopic way, and showed linear measurement responses with a pH resolution up to an average of 0.049 pH unit within a narrow, but biological meaningful pH range of 6.12–7.81. Its novel characterizations of high spatial resolution, reflection mode operation, fast response and high stability, great linear response within biological meaningful pH range and high pH resolutions, make this novel pH probe a very cost-effective tool for chemical/biological sensing, especially within the single cell level research field. PMID:25530670

  14. Curing Metastatic Breast Cancer.

    PubMed

    Sledge, George W

    2016-01-01

    Metastatic breast cancer is generally considered incurable, and this colors doctor-patient interactions for patients with metastatic disease. Although true for most patients, there appear to be important exceptions, instances where long-term disease-free survival occurs. Although these instances are few in number, they suggest the possibility of cure. How will we move toward cure for a much larger population of patients with metastatic disease? This article outlines a potential research agenda that might move us toward that distant goal. PMID:26759458

  15. Alternative approach to modeling bacterial lag time, using logistic regression as a function of time, temperature, pH, and sodium chloride concentration.

    PubMed

    Koseki, Shige; Nonaka, Junko

    2012-09-01

    The objective of this study was to develop a probabilistic model to predict the end of lag time (λ) during the growth of Bacillus cereus vegetative cells as a function of temperature, pH, and salt concentration using logistic regression. The developed λ model was subsequently combined with a logistic differential equation to simulate bacterial numbers over time. To develop a novel model for λ, we determined whether bacterial growth had begun, i.e., whether λ had ended, at each time point during the growth kinetics. The growth of B. cereus was evaluated by optical density (OD) measurements in culture media for various pHs (5.5 ∼ 7.0) and salt concentrations (0.5 ∼ 2.0%) at static temperatures (10 ∼ 20°C). The probability of the end of λ was modeled using dichotomous judgments obtained at each OD measurement point concerning whether a significant increase had been observed. The probability of the end of λ was described as a function of time, temperature, pH, and salt concentration and showed a high goodness of fit. The λ model was validated with independent data sets of B. cereus growth in culture media and foods, indicating acceptable performance. Furthermore, the λ model, in combination with a logistic differential equation, enabled a simulation of the population of B. cereus in various foods over time at static and/or fluctuating temperatures with high accuracy. Thus, this newly developed modeling procedure enables the description of λ using observable environmental parameters without any conceptual assumptions and the simulation of bacterial numbers over time with the use of a logistic differential equation. PMID:22729541

  16. Alternative Approach To Modeling Bacterial Lag Time, Using Logistic Regression as a Function of Time, Temperature, pH, and Sodium Chloride Concentration

    PubMed Central

    Nonaka, Junko

    2012-01-01

    The objective of this study was to develop a probabilistic model to predict the end of lag time (λ) during the growth of Bacillus cereus vegetative cells as a function of temperature, pH, and salt concentration using logistic regression. The developed λ model was subsequently combined with a logistic differential equation to simulate bacterial numbers over time. To develop a novel model for λ, we determined whether bacterial growth had begun, i.e., whether λ had ended, at each time point during the growth kinetics. The growth of B. cereus was evaluated by optical density (OD) measurements in culture media for various pHs (5.5 ∼ 7.0) and salt concentrations (0.5 ∼ 2.0%) at static temperatures (10 ∼ 20°C). The probability of the end of λ was modeled using dichotomous judgments obtained at each OD measurement point concerning whether a significant increase had been observed. The probability of the end of λ was described as a function of time, temperature, pH, and salt concentration and showed a high goodness of fit. The λ model was validated with independent data sets of B. cereus growth in culture media and foods, indicating acceptable performance. Furthermore, the λ model, in combination with a logistic differential equation, enabled a simulation of the population of B. cereus in various foods over time at static and/or fluctuating temperatures with high accuracy. Thus, this newly developed modeling procedure enables the description of λ using observable environmental parameters without any conceptual assumptions and the simulation of bacterial numbers over time with the use of a logistic differential equation. PMID:22729541

  17. Curing Children's Cancer

    MedlinePlus

    ... ALL is a cancer of the white blood cells, which fight infection. It is the most common cancer in children, representing 23 percent of all cancers among those 15 or younger. Forty years ago, ALL was incurable. Today, in the United States, its cure rate is a major success story—as many ...

  18. New advanced shotcrete admixtures: Internal curing

    SciTech Connect

    Melbye, T.A.

    1995-12-31

    Tunnels and other underground construction projects have one of the worst curing conditions due to the ventilation that blows continuously dry (cold or hot) air into the tunnel. It can be compared with concrete exposed to a windy area. One would think that tunnels have ideal curing conditions with high humidity (water leakage), no wind and no sun exposure. However, this is not the case. MBT has developed a new system for more efficient and secure curing of wet shotcrete, repair mortars as well as concrete. Internal curing means that a special admixture is added to the concrete/mortar during batching as a normal admixture. This admixture produces an internal barrier in the shotcrete/concrete which secures safer hydration and better chemical resistance than the application of conventional curing agents. The benefits resulting from the new technology are impressive: The time consuming application and, in the case of various shotcrete layers, removal of curing agents are no longer necessary; curing is guaranteed from the very beginning of hydration; and there is no negative influence on bonding between layers. As a consequence of th is optimum curing effect, all other shotcrete characteristics are improved: density, final strengths, freeze/thaw and chemical resistances, watertightness, less cracking and shrinkage. In addition, MEYCO TCC 735 also improves pumpability and workability of shotcrete, even with low-grade aggregates. It particularly improves the pumpability of steel fiber reinforced shotcrete mixes. In combination with the MEYCO TCC system it contrives to even increase the beneficial effects of the slump killing system by further improving fiber orientation, reducing fiber rebound and thus raising toughness values.

  19. Fast Curing of Composite Wood Products

    SciTech Connect

    Dr. Arthur J. Ragauskas

    2006-04-26

    The overall objective of this program is to develop low temperature curing technologies for UF and PF resins. This will be accomplished by: • Identifying the rate limiting UF and PF curing reactions for current market resins; • Developing new catalysts to accelerate curing reactions at reduced press temperatures and times. In summary, these new curing technologies will improve the strength properties of the composite wood products and minimize the detrimental effects of wood extractives on the final product while significantly reducing energy costs for wood composites. This study is related to the accelerated curing of resins for wood composites such as medium density fiberboard (MDF), particle board (PB) and oriented strandboard (OSB). The latter is frequently manufactured with a phenol-formaldehyde resin whereas ureaformaldehyde (UF) resins are usually used in for the former two grades of composite wood products. One of the reasons that hinder wider use of these resins in the manufacturing of wood composites is the slow curing speed as well as inferior bondability of UF resin. The fast curing of UP and PF resins has been identified as an attractive process development that would allow wood to be bonded at higher moisture contents and at lower press temperatures that currently employed. Several differing additives have been developed to enhance cure rates of PF resins including the use of organic esters, lactones and organic carbonates. A model compound study by Conner, Lorenz and Hirth (2002) employed 2- and 4-hydroxymethylphenol with organic esters to examine the chemical basis for the reported enhanced reactivity. Their studies suggested that the enhance curing in the presence of esters could be due to enhanced quinone methide formation or enhanced intermolecular SN2 reactions. In either case the esters do not function as true catalysts as they are consumed in the reaction and were not found to be incorporated in the polymerized resin product. An

  20. An ultrasensitive method of real time pH monitoring with complementary metal oxide semiconductor image sensor.

    PubMed

    Devadhasan, Jasmine Pramila; Kim, Sanghyo

    2015-02-01

    CMOS sensors are becoming a powerful tool in the biological and chemical field. In this work, we introduce a new approach on quantifying various pH solutions with a CMOS image sensor. The CMOS image sensor based pH measurement produces high-accuracy analysis, making it a truly portable and user friendly system. pH indicator blended hydrogel matrix was fabricated as a thin film to the accurate color development. A distinct color change of red, green and blue (RGB) develops in the hydrogel film by applying various pH solutions (pH 1-14). The semi-quantitative pH evolution was acquired by visual read out. Further, CMOS image sensor absorbs the RGB color intensity of the film and hue value converted into digital numbers with the aid of an analog-to-digital converter (ADC) to determine the pH ranges of solutions. Chromaticity diagram and Euclidean distance represent the RGB color space and differentiation of pH ranges, respectively. This technique is applicable to sense the various toxic chemicals and chemical vapors by situ sensing. Ultimately, the entire approach can be integrated into smartphone and operable with the user friendly manner. PMID:25597802

  1. Argon Ion Laser Polymerized Acrylic Resin: A Comparative Analysis of Mechanical Properties of Laser Cured, Light Cured and Heat Cured Denture Base Resins

    PubMed Central

    Murthy, S Srinivasa; Murthy, Gargi S

    2015-01-01

    Background: Dentistry in general and prosthodontics in particular is evolving at greater pace, but the denture base resins poly methyl methacrylate. There has been vast development in modifying chemically and the polymerization techniques for better manipulation and enhancement of mechanical properties. One such invention was introduction of visible light cure (VLC) denture base resin. Argon ion lasers have been used extensively in dentistry, studies has shown that it can polymerize restorative composite resins. Since composite resin and VLC resin share the same photo initiator, Argon laser is tested as activator for polymerizing VLC resin. In the Phase 1 study, the VLC resin was evaluated for exposure time for optimum polymerization using argon ion laser and in Phase 2; flexural strength, impact strength, surface hardness and surface characteristics of laser cured resin was compared with light cure and conventional heat cure resin. Materials and Methods: Phase 1; In compliance with American Dental Association (ADA) specification no. 12, 80 samples were prepared with 10 each for different curing time using argon laser and evaluated for flexural strength on three point bend test. Results were compared to established performance requirement specified. Phase 2, 10 specimen for each of the mechanical properties (30 specimen) were polymerized using laser, visible light and heat and compared. Surface and fractured surface of laser, light and heat cured resins were examined under scanning electron microscope (SEM). Results: In Phase 1, the specimen cured for 7, 8, 9 and 10 min fulfilled ADA requirement. 8 min was taken as suitable curing time for laser curing. Phase 2 the values of mechanical properties were computed and subjected to statistical analysis using one-way ANOVA and Tukey post-hoc test. The means of three independent groups showed significant differences between any two groups (P < 0.001). Conclusion: Triad VLC resin can be polymerized by argon ion laser with

  2. The Effect of pH and Time on the Extractability and Speciation of Uranium(VI) Sorbed to SiO2

    SciTech Connect

    Ilton, Eugene S.; Wang, Zheming; Boily, Jean F.; Qafoku, Odeta; Rosso, Kevin M.; Smith, Steven C.

    2012-05-22

    The effect of pH and contact time on uranium extractability from quartz surfaces was investigated using either acidic or carbonate (CARB) extraction solutions, time-delayed spikes of different U isotopes (i.e., 238U and 233U), and liquid helium temperature time-resolved laser-induced fluorescence spectroscopy (LHeT TRLFS). Quartz powders were reacted with 238U(VI) bearing solutions that were equilibrated with atmospheric CO2 at pH 6, 7, and 8. After a 42 day equilibration period with 238U(VI), the suspensions were spiked with 233U(VI) and reacted for an additional 7 days. Sorbed U was then extracted with either dilute nitric acid or CARB. For the CARB extraction there was a systematic decrease in extraction efficiency for both isotopes from pH 6 to 8. This was mimicked by less desorption of 238U, after the 233U spike, from pH 6 to 8. Further, the efficiency of 233U extraction was consistently greater than that of 238U, indicating a strong temporal component to the strength of U association with the surface that was accentuated with increasing pH. LHeT TRLFS revealed a strong correlation between carbonate extraction efficiency and differences in sorbed U speciation as a function of pH. In contrast, the acid extraction was consistently more efficient than the CARB extraction, with a smaller dependence on both pH and aging time. Collectively, the observations show that aging and pH are critical factors in determining the form and strength of uranium-silica interactions.

  3. Process for curing bismaleimide resins

    NASA Technical Reports Server (NTRS)

    Parker, John A. (Inventor); OTHY S.imides alone. (Inventor)

    1986-01-01

    This invention relates to vinyl pyridine group containing compounds and oligomers, their advantageous copolymerization with bismaleimide resins, and the formation of reinforced composites based on these copolymers. When vinyl pyridines including vinyl stilbazole materials and vinyl styrylpyridine oligomer materials are admixed with bismaleimides and cured to form copolymers the cure temperatures of the copolymers are substantially below the cure temperatures of the bismaleimides alone.

  4. New addition curing polyimides

    NASA Technical Reports Server (NTRS)

    Frimer, Aryeh A.; Cavano, Paul

    1991-01-01

    In an attempt to improve the thermal-oxidative stability (TOS) of PMR-type polymers, the use of 1,4-phenylenebis (phenylmaleic anhydride) PPMA, was evaluated. Two series of nadic end-capped addition curing polyimides were prepared by imidizing PPMA with either 4,4'-methylene dianiline or p-phenylenediamine. The first resulted in improved solubility and increased resin flow while the latter yielded a compression molded neat resin sample with a T(sub g) of 408 C, close to 70 C higher than PME-15. The performance of these materials in long term weight loss studies was below that of PMR-15, independent of post-cure conditions. These results can be rationalized in terms of the thermal lability of the pendant phenyl groups and the incomplete imidization of the sterically congested PPMA. The preparation of model compounds as well as future research directions are discussed.

  5. Effect of adhesive hydrophilicity and curing-time on the permeability of resins bonded to water vs. ethanol-saturated acid-etched dentin

    PubMed Central

    Cadenaro, Milena; Breschi, Lorenzo; Rueggeberg, Frederick A.; Agee, Kelli; Di Lenarda, Roberto; Carrilho, Marcela; Tay, Franklin R.; Pashley, David H.

    2009-01-01

    Objective This study examined the ability of five comonomer blends (R1-R5) of methacrylate-based experimental dental adhesives solvated with 10 mass% ethanol, at reducing the permeability of acid-etched dentin. The resins were light-cured for 20, 40 or 60 s. The acid-etched dentin was saturated with water or 100% ethanol. Method Human unerupted third molars were converted into crown segments by removing the occlusal enamel and roots. The resulting crown segments were attached to plastic plates connected to a fluid-filled system for quantifying fluid flow across smear layer-covered dentin, acid-etched dentin and resin-bonded dentin. The degree of conversion of the resins was measured using Fourier transform infrared spectroscopy. Result Application of the most hydrophobic comonomer blend (R1) to water-saturated dentin produced the smallest reductions in dentin permeability (31.9, 44.1 and 61.1% after light-curing for 20, 40 or 60 s respectively). Application of the same blend to ethanol-saturated dentin reduced permeability of 74.1, 78.4 and 81.2%, respectively (p<0.05). Although more hydrophilic resins produced larger reductions in permeability, the same trend of significantly greater reductions in ethanol-saturated dentin over that of water-saturated dentin remained. This result can be explained by the higher solubility of resins in ethanol vs. water. Significance The largest reductions in permeability produced by resins were equivalent but not superior, to those produced by smear layers. Resin sealing of dentin remains a technique-sensitive step in bonding etch-and-rinse adhesives to dentin. PMID:18571228

  6. Interaction of quinine sulfate with anionic micelles of sodium dodecylsulfate: A time-resolved fluorescence spectroscopy at different pH

    NASA Astrophysics Data System (ADS)

    Joshi, Sunita; Pant, Debi D.

    2015-09-01

    Photophysical behavior and rotational relaxation dynamics of quinine sulfate (QS) in anionic surfactant, sodium dodecylsulfate (SDS) at different pH have been studied using steady state and time resolved fluorescence spectroscopy. It has been observed that the cationic form of quinine sulfate (at pH 2) forms a fluorescent ion pair complex with the surfactant molecules at lower concentrations of surfactant. However, for higher concentrations of SDS, the probe molecules bind strongly with the micelles and reside at the water-micelle interface. At pH 7, QS is singly protonated in bulk aqueous solution. At lower concentrations of SDS aggregation between probe and surfactant molecules has been observed. However, for higher concentrations of SDS, an additional fluorescence peak corresponding to dicationic form of QS appears and this has been attributed to double protonation of the QS molecule in micellar solution. At pH 7, in the presence of SDS micelles, the photophysical properties of QS showed substantial changes compared to that in the bulk water solution. At pH 12, an increase in fluorescence intensity and lifetime has been observed and this has been attributed to the increase in radiative rate due to the incorporation of QS at the micelle-water interface. The local pH at micellar surface has been found different from the pH of bulk solution.

  7. Interaction of quinine sulfate with anionic micelles of sodium dodecylsulfate: A time-resolved fluorescence spectroscopy at different pH.

    PubMed

    Joshi, Sunita; Pant, Debi D

    2015-09-01

    Photophysical behavior and rotational relaxation dynamics of quinine sulfate (QS) in anionic surfactant, sodium dodecylsulfate (SDS) at different pH have been studied using steady state and time resolved fluorescence spectroscopy. It has been observed that the cationic form of quinine sulfate (at pH 2) forms a fluorescent ion pair complex with the surfactant molecules at lower concentrations of surfactant. However, for higher concentrations of SDS, the probe molecules bind strongly with the micelles and reside at the water-micelle interface. At pH 7, QS is singly protonated in bulk aqueous solution. At lower concentrations of SDS aggregation between probe and surfactant molecules has been observed. However, for higher concentrations of SDS, an additional fluorescence peak corresponding to dicationic form of QS appears and this has been attributed to double protonation of the QS molecule in micellar solution. At pH 7, in the presence of SDS micelles, the photophysical properties of QS showed substantial changes compared to that in the bulk water solution. At pH 12, an increase in fluorescence intensity and lifetime has been observed and this has been attributed to the increase in radiative rate due to the incorporation of QS at the micelle-water interface. The local pH at micellar surface has been found different from the pH of bulk solution. PMID:25863459

  8. Influence of potential, chlorides, pH, and precharging time on embrittlement of cathodically polarized prestressing steel

    SciTech Connect

    Hartt, W.H.; Kumria, C.C. ); Kessler, R.J. )

    1993-05-01

    Corrosion of prestressing steel in concrete has become a major technological problem in highways, buildings, and pipeline structures. While cathodic protection is recognized as an appropriate technique to mitigate corrosion of reinforcing steel in concrete, the possibility of environmental cracking (hydrogen embrittlement) in the case of prestressing tendon has limited application to this usage. To establish the appropriateness of cathodic protection for prestressing steel, constant extension rate testing was performed on smooth and notched wire specimens in deaerated Ca(OH)[sub 2] solutions as a function of potential, [Cl-], pH, and precharging time. Results indicated potential is the most important of these variables, and a threshold value of [minus]0.90 V[sub SCE] was identified below which embrittlement is enhanced. Notched specimens, which may best simulate the geometry of corroded tendon, particularly were susceptible when compared to smooth tendon. Failure of some tendons in this condition could occur upon application of cathodic protection, even when potential is positive to [minus]0.90 V[sub SCE]. Other aspects of cathodic protection utility for prestressed concrete are reviewed.

  9. A comparison of ultraviolet-curing and self-curing polymers in preventive, restorative and orthodontic dentistry.

    PubMed

    Lee, H L; Orlowski, J A; Rogers, B J

    1976-06-01

    Both self-cured and UV-cured resin-base dental materials are used in preventive, restorative, and orthodontic dentistry. Polymerization is initiated in both systems by free radicals. Self-curing materials generate free radicals by means of chemical compounds included in their formulation. UV-curing systems rely upon externally-supplied, long wavelength, ultraviolet radiation to produce free radicals within the material. Therefore, although the major chemical components of both systems are similar in many respects, each system has particular advantages and disadvantages over the other, which must be recognized by the practitioner. Substantial differences exist, for example, in the color stability of these two types of materials, because of the fact that the UV-cured system cannot include UV absorbers, which protect the self-cured systems from discoloration after exposure to sunlight. UV-cured systems require a limitation on the maximum depth of filled restorative that can be cured at one time, since the filler particles attenuate UV radiation. The limit-layer is generally established as 1-1-5 mm maximum thickness. Therefore, UV-cured filled systems are more time-consuming in restorations of deeper cavities. This liability is also in evidence as it affects the degree of polymerization of UV-cured filled systems. The uncertainty of complete polymerization is apparently responsible for highly erratic compressive strength data found with UV-cured restoratives. Normally, the amount of unpolymerized monomer is much less predictable in UV-cured systems, over that which is obtained in self-cured materials. The presence of a larger fraction of unpolymerized monomer creates a greater potential for pulpal injury from UV-cured restorative materials. The catalyst used in several UV-cured systems is benzoin methyl ether, a compound of rather high toxicity (LD50:300 mg/kg). The safety of using UV radiation in the vicinity of oral mucosa has not been firmly established. The design

  10. Characterization of the relationship of the cure cycle chemistry to cure cycle processing properties

    NASA Technical Reports Server (NTRS)

    Kranbuehl, D. E.

    1985-01-01

    Dynamic dielectric analysis (DDA) is used to study curing polymer systems and thermoplastics. Measurements are made over a frequency range of six decades. This wide range of frequencies increases the amount of information which can be obtained. The data is analyzed in terms of the frequency dependence of the complex permittivity epsilon sup *, specific conductivity sigma (ohm/cm) and the relaxation time tau, parameters which are characteristic of the cure state of the material and independent of the size of the sample.

  11. Relaxed Poisson cure rate models.

    PubMed

    Rodrigues, Josemar; Cordeiro, Gauss M; Cancho, Vicente G; Balakrishnan, N

    2016-03-01

    The purpose of this article is to make the standard promotion cure rate model (Yakovlev and Tsodikov, ) more flexible by assuming that the number of lesions or altered cells after a treatment follows a fractional Poisson distribution (Laskin, ). It is proved that the well-known Mittag-Leffler relaxation function (Berberan-Santos, ) is a simple way to obtain a new cure rate model that is a compromise between the promotion and geometric cure rate models allowing for superdispersion. So, the relaxed cure rate model developed here can be considered as a natural and less restrictive extension of the popular Poisson cure rate model at the cost of an additional parameter, but a competitor to negative-binomial cure rate models (Rodrigues et al., ). Some mathematical properties of a proper relaxed Poisson density are explored. A simulation study and an illustration of the proposed cure rate model from the Bayesian point of view are finally presented. PMID:26686485

  12. Time esophageal pH < 4 overestimates the prevalence of pathologic esophageal reflux in subjects with gastroesophageal reflux disease treated with proton pump inhibitors

    PubMed Central

    Gerson, Lauren B; Triadafilopoulos, George; Sahbaie, Peyman; Young, Winston; Sloan, Sheldon; Robinson, Malcolm; Miner, Philip B; Gardner, Jerry D

    2008-01-01

    Background A Stanford University study reported that in asymptomatic GERD patients who were being treated with a proton pump inhibitor (PPI), 50% had pathologic esophageal acid exposure. Aim We considered the possibility that the high prevalence of pathologic esophageal reflux might simply have resulted from calculating acidity as time pH < 4. Methods We calculated integrated acidity and time pH < 4 from the 49 recordings of 24-hour gastric and esophageal pH from the Stanford study as well as from another study of 57 GERD subjects, 26 of whom were treated for 8 days with 20 mg omeprazole or 20 mg rabeprazole in a 2-way crossover fashion. Results The prevalence of pathologic 24-hour esophageal reflux in both studies was significantly higher when measured as time pH < 4 than when measured as integrated acidity. This difference was entirely attributable to a difference between the two measures during the nocturnal period. Nocturnal gastric acid breakthrough was not a useful predictor of pathologic nocturnal esophageal reflux. Conclusion In GERD subjects treated with a PPI, measuring time esophageal pH < 4 will significantly overestimate the prevalence of pathologic esophageal acid exposure over 24 hours and during the nocturnal period. PMID:18498663

  13. Picosecond time-resolved fluorescence of ribonuclease T1. A pH and substrate analogue binding study.

    PubMed Central

    Chen, L X; Longworth, J W; Fleming, G R

    1987-01-01

    The tryptophyl fluorescence of ribonuclease T1 decays monoexponentially at pH 5.5, tau = 4.04 ns but on increasing pH, a second short-lived component of 1.5 ns appears with a midpoint between pH 6.5 and 7.0. Both components have the same fluorescence spectrum. Acrylamide quenches both fluorescence components, and the short-lived component is quenched fivefold faster than the predominant long component. Binding of the substrate analogue 2'-guanylic acid at pH 5.5 quenches the fluorescence by 20% and introduces a second decay component, tau = 1.16 ns. Acrylamide quenches both tryptophyl decay components, with similar quenching rates. The fluorescence anisotropy decay of ribonuclease T1 was consistent with a molecule the size of ribonuclease T1 surrounded by a single layer of water at pH 7.4, even though the anisotropy decay at pH 5.5 deviated from Stokes-Einstein behavior. The fluorescence data were interpreted with a model where the tryptophyl residue exists in two conformations, remaining in a hydrophobic pocket. The acrylamide quenching is interpreted with electron transfer theory and suggests that one conformer has the nearest atom approximately 3 A from the protein surface, and the other, approximately 2 A. PMID:3038204

  14. Extracellular amylases of starch-fermenting yeast: pH effect on export and residence time in the periplasm

    SciTech Connect

    Calleja, G.B.; Levy-Rick, S.R.; Nasim, A.; Lusena, C.V.

    1987-01-01

    Aerobic cultures of S. alluvius in Wickerham's yeast-nitrogen-base medium with starch as sole carbon source become strongly acidic and contain no detectable extra-cellular amylolytic activity during stationary phase, when the activity in buffered cultures is maximal. The extracellular amylases are irreversibly inactivated at the low pH value (less than 3.5) attained by the cultures. When adequately buffered, the medium yields maximal extracellular amylolytic activity. About 0.2 M phosphate buffer is adequate for substrate concentrations of up to 0.5% starch; higher starch concentrations require more buffer. Unbuffered cultures that are adjusted once with alkali to pH 5.5 also allow maximal extracellular amylolytic activity, provided the adjustment is made prior to the end of exponential growth. Automatic pH control allows use of high starch concentrations of up to 4%. Export is optimal at pH values higher than the optima for enzyme activity and stability and for population growth. The need for pH adjustment prior to the appearance of amylolytic activity in the medium suggests pH dependence of the export process itself and/or acid inactivation of enzymes transiently resident in the periplasm. (Refs. 23).

  15. Effect of Curing Profile on Kaolin-based Geopolymers

    NASA Astrophysics Data System (ADS)

    Heah, C. Y.; Kamarudin, H.; Bakri, A. M. Mustafa Al; Binhussain, M.; Luqman, M.; Nizar, I. Khairul; Ruzaidi, C. M.; Liew, Y. M.

    Depending on the processing conditions, geopolymers can exhibit a wide variety of properties and characteristics. Curing profile serves as a crucial parameter in synthesis of geopolymers. In this paper, the influence of curing temperature and curing time on the properties of kaolin-based geopolymer was studied. The samples were separated into several curing conditions; including curing at ambient temperature, 40 °C, 60 °C, 80 °C and 100 °C for 1 day, and up to 3 days. The compressive strength and SEM analysis of geopolymer products were evaluated. Results showed that curing condition has a significant effect on the mechanical properties of kaolin-based geopolymer. Generally, curing at ambient temperature was not feasible, while increase in temperature favored the strength development. In addition, prolonged curing time improved the geopolymerization process, and led to higher strength gain. However, curing at high temperature for a long period of time caused failure of the sample at a later age.

  16. The Lourdes Medical Cures Revisited†

    PubMed Central

    François, Bernard; Sternberg, Esther M.; Fee, Elizabeth

    2014-01-01

    This article examines the cures recorded in Lourdes, France, between 1858, the year of the Visions, and 1976, the date of the last certified cure of the twentieth century. Initially, the records of cures were crude or nonexistent, and allegations of cures were accepted without question. A Medical Bureau was established in 1883 to examine and certify the cures, and the medical methodology improved steadily in the subsequent years. We discuss the clinical criteria of the cures and the reliability of medical records. Some 1,200 cures were said to have been observed between 1858 and 1889, and about one hundred more each year during the “Golden Age” of Lourdes, 1890–1914. We studied 411 patients cured in 1909–14 and thoroughly reviewed the twenty-five cures acknowledged between 1947 and 1976. No cure has been certified from 1976 through 2006. The Lourdes phenomenon, extraordinary in many respects, still awaits scientific explanation. Lourdes concerns science as well as religion. PMID:22843835

  17. Cytosolic pH gradients in cultured neuronal cell lines studied by laser scanning confocal microscopy, real-time confocal microscopy, and spectral imaging microscopy

    NASA Astrophysics Data System (ADS)

    Sanchez-Armass, Sergio; Sennoune, Souad; Martinez, Gloria M.; Ortega, Filiberta; Martinez-Zaguilan, Raul

    2002-06-01

    Changes in intracellular pH are important for the regulation of many physiological processes including: cell growth and differentiation, exocytosis, synaptic transmission, cell motility and invasion, to name a few. In pathological states such as cancer and diabetes, pH regulation is known to be altered. Nevertheless the physiological and pathological significance of this ion, there are still many gaps in our knowledge. The advent of fluorescent pH probes to monitor this ion, has substantially accelerated its study. New advances in the methods of detection of this ion by fluorescence-based approaches have also helped us to understand more about the regulation of cytosolic pH. This study evaluates the usefulness of real time confocal imaging microscopy, laser scanning confocal microscopy, and spectral imaging microscopy to the study of pH. These approaches exhibit unsurpassed temporal, spatial, and spectral resolution and are complementary. We employed cell lines derived from the brain exhibiting soma and dendrites. The existence of cell polarity suggests that the different protein composition/micro environment in discrete subcellular domains may affect the properties of fluorescent ion indicators. We performed in situ calibration of pH probes in discrete cellular regions of the neuronal cell lines to eliminate any bias in data interpretation because of differences in cell thickness/micro environment. We show that there are distinct in situ calibration parameters in different cellular domains. These indicate that in situ titrations in discrete cellular domains are needed to assign pH values. We concluded that there are distinct pH micro domains in discrete cellular regions of neuronal cell lines.

  18. Annealing time dependence of the physical, electrical and pH response characteristics of spin coated TiO2 thin films

    NASA Astrophysics Data System (ADS)

    Zulkefle, M. A.; Rahman, R. A.; Yusoff, K. A.; Abdullah, W. F. H.; Rusop, M.; Herman, S. H.

    2015-11-01

    Titanium dioxide (TiO2) thin film was deposited on indium tin oxide (ITO) substrate and used as sensing membrane of EGFET pH sensor. The thin film was fabricated using sol- gel spin coating method. All samples were annealed at 400 °C but the annealing time was varied. This is done to study the effects of annealing time on physical and electrical properties of titanium dioxide thin film. The sensitivity of each sample towards H+ ion was measured and result shows that sample annealed for 45 minutes has the highest sensitivity (52.6 mV/pH). It is found that increasing annealing duration will increase the pH sensitivity but a limit will be reached at certain point. Longer annealing processes done beyond this point will results in lower pH sensitivity.

  19. Prevent and cure disuse bone loss

    NASA Technical Reports Server (NTRS)

    Jee, Webster S. S.

    1994-01-01

    Anabolic agents like parathyroid hormone and postagladin E-like substances were studied in dogs and rats to determine their effectiveness in the prevention and cure of bone loss due to immobilization. It was determined that postagladin E2 administration prevented immobilization while at the same time it added extra bone in a dose responsive manner. Although bone mass returns, poor trabecular architecture remains after normal ambulation recovery from immobilization. Disuse related bone loss and poor trabecular architecture were cured by post-immobilization postagladin E2 treatment.

  20. Lower-curing-temperature PMR polyimides

    NASA Technical Reports Server (NTRS)

    Serafini, T. T.; Delvigs, P.; Vannucci, R. D.

    1981-01-01

    Studies were performed to achieve a lower-curing-temperature PMR polyimide. The use of m-aminostyrene as the end-cap instead of the monoalkyl ester of 5-normbornene-2,3 dicarboxylic acid was investigated in typical PMR formulations. Model compound studies were also performed. Differential scanning calorimetry studies were performed on model compounds and neat resins to establish their melting and curing characteristics. The elevated temperature weight loss characteristics of neat resins and graphite fiber composites were determined. The room temperature and short-time 260 C (500 F) mechanical properties of the composites were also determined. The use of m-aminostyrene end-caps reduced the final cure temperature of PMR resins by about 55 C (100 F), but the composites prepared with these resins are limited to use temperatures of about 260 C (500 F).

  1. Adhesive curing through low-voltage activation

    PubMed Central

    Ping, Jianfeng; Gao, Feng; Chen, Jian Lin; Webster, Richard D.; Steele, Terry W. J.

    2015-01-01

    Instant curing adhesives typically fall within three categories, being activated by either light (photocuring), heat (thermocuring) or chemical means. These curing strategies limit applications to specific substrates and can only be activated under certain conditions. Here we present the development of an instant curing adhesive through low-voltage activation. The electrocuring adhesive is synthesized by grafting carbene precursors on polyamidoamine dendrimers and dissolving in aqueous solvents to form viscous gels. The electrocuring adhesives are activated at −2 V versus Ag/AgCl, allowing tunable crosslinking within the dendrimer matrix and on both electrode surfaces. As the applied voltage discontinued, crosslinking immediately terminated. Thus, crosslinking initiation and propagation are observed to be voltage and time dependent, enabling tuning of both material properties and adhesive strength. The electrocuring adhesive has immediate implications in manufacturing and development of implantable bioadhesives. PMID:26282730

  2. Effects of pH and storage time on the adhesive and rheological properties of cottonseed meal-based products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adhesive bonding is a key factor for efficiently utilizing timber and other lignocellulosic resources. To increase the basic knowledge of cottonseed meal-based adhesives and optimize the operational parameters for practical applications, in this study, we investigated the effects of pH and storage t...

  3. Over Time, How Do Post-Ph.D. Scientists Locate Teaching and Supervision within Their Academic Practice?

    ERIC Educational Resources Information Center

    McAlpine, Lynn

    2014-01-01

    While building a strong research profile is usually seen as key for those seeking a traditional academic position, teaching is also understood as central to academic practice. Still, we know little of how post-Ph.D. researchers seeking academic posts locate teaching and supervision in their academic practice, nor how their views may shift as they…

  4. Dielectric cure monitoring: Preliminary studies

    NASA Technical Reports Server (NTRS)

    Goldberg, B. E.; Semmel, M. L.

    1984-01-01

    Preliminary studies have been conducted on two types of dielectric cure monitoring systems employing both epoxy resins and phenolic composites. An Audrey System was used for 23 cure monitoring runs with very limited success. Nine complete cure monitoring runs have been investigated using a Micromet System. Two additional measurements were performed to investigate the Micromet's sensitivity to water absorption in a post-cure carbon-phenolic material. While further work is needed to determine data significance, the Micromet system appears to show promise as a feedback control device during processing.

  5. Critical parameters for electron beam curing of cationic epoxies and property comparison of electron beam cured cationic epoxies versus thermal cured resins and composites

    SciTech Connect

    Janke, C.J.; Norris, R.E.; Yarborough, K.; Havens, S.J.; Lopata, V.J.

    1997-01-16

    Electron beam curing of composites is a nonthermal, nonautoclave curing process offering the following advantages compared to conventional thermal curing: substantially reduced manufacturing costs and curing times; improvements in part quality and performance; reduced environmental and health concerns; and improvements in material handling. In 1994 a Cooperative Research and Development Agreement (CRADA), sponsored by the Department of Energy Defense Programs and 10 industrial partners, was established to advance electron beam curing of composites. The CRADA has successfully developed hundreds of new toughened and untoughened resins, offering unlimited formulation and processing flexibility. Several patent applications have been filed for this work. Composites made from these easily processable, low shrinkage material match the performance of thermal cured composites and exhibit: low void contents comparable to autoclave cured composites (less than 1%); superb low water absorption values in the same range as cyanate esters (less than 1%); glass transition temperatures rivaling those of polyimides (greater than 390 C); mechanical properties comparable to high performance, autoclave cured composites; and excellent property retention after cryogenic and thermal cycling. These materials have been used to manufacture many composite parts using various fabrication processes including hand lay-up, tow placement, filament winding, resin transfer molding and vacuum assisted resin transfer molding.

  6. Delayed cure bismaleimide resins

    DOEpatents

    Adams, Johnnie E.; Jamieson, Donald R.

    1984-08-07

    Polybismaleimides prepared by delayed curing of bis-imides having the formula ##STR1## wherein R.sub.1 and R.sub.2 each independently is H, C.sub.1-4 -alkyl, C.sub.1-4 -alkoxy, Cl or Br, or R.sub.1 and R.sub.2 together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R.sub.1 and R.sub.2 are not t-butyl or t-butoxy; X is O, S or Se; n is 1-3; and the --(CH.sub.2).sub.n -- group, optionally, is substituted by 1-3 methyl groups or by fluorine.

  7. Is the soft-start polymerisation concept still relevant for modern curing units?

    PubMed

    Ilie, Nicoleta; Jelen, Esther; Hickel, Reinhard

    2011-02-01

    Shrinkage stress, degree of cure and mechanical properties are contradicting properties, forcing to a compromise between an adequate curing and low stress at the interface tooth-restoration. The purpose of this study was to quantify this relations for a micro-hybrid composite, by analysing in real time the development of degree of cure at depths of 2 and 6 mm, shrinkage stress and curing time until gelation, as well as the variation of micro-mechanical properties with depth, after curing with 13 regimes of one halogen and two light-emitting diode (LED) curing units. A nano-dynamic mechanical test was additionally performed on selected regimes (Ramp, Pulse and Fast Cure) of the same curing unit. The present study showed that the soft-start polymerization concept is still valid for less deep cavities (2 mm), even by curing with high-power LED curing units, since a soft-cure polymerization resulted in a delayed gel point and a lower shrinkage stress, keeping simultaneously the degree of cure and mechanical properties constant. At 6 mm depth, curing with soft-start regimes resulted in a significant decrease in degree of cure, although this decrease was less than 10%, while the mechanical properties were maintained. PMID:19937074

  8. Effect of Annealing Time Process on the pH Sensitivity of Spin-coated TiO2/ ZnO Bilayer Film

    NASA Astrophysics Data System (ADS)

    Rahman, R. A.; Zulkefle, M. A.; Yusof, K. A.; Abdullah, W. F. H.; Rusop, M.; Herman, S. H.

    2015-11-01

    This paper presents an investigation on titanium dioxide (TiO2) and zinc oxide (ZnO) bilayer film, which is used as sensing membrane for extended-gate field effect transistor (EGFET) for pH sensing application. TiO2/ZnO thin films were deposited using sol-gel spin coating method on indium tin oxide (ITO) substrates. After the deposition, the bilayer films were annealed at constant temperatures which is 400 °C for 15, 30, 40 and 60 minutes. The sensitivity of the TiO2 thin film towards pH buffer solution was measured by dipping the sensing membrane in pH4, pH7 and pH10 buffer solution. By varying the annealing time, we found that the TiO2/ZnO thin film annealed at 400°C for 15 minutes gave the highest sensitivity compared to other annealing conditions, with the value of 64.87 mV/pH.

  9. Influence of drug incorporation, temperature and storage time on the pH, textural and rheological properties of different poloxamer hydrogels.

    PubMed

    Almeida, Hugo; Amaral, Maria Helena; Lobão, Paulo; Lobo, José Manuel Sousa

    2013-12-01

    In recent years, Poloxamers had attracted a particular interest in the design of dermal and transdermal delivery systems in order to improve or retard drug permeation through the skin. In the present study, the influence of different parameters, such as, temperature, storage time, type of polymer (Lutrol(®) F-127 and Lutrol(®) F-108) and the addition of two types of drugs (ibuprofen and hydrocortisone) in the pH, texture and rheological behavior of topical pharmaceutical formulations containing poloxamers was assessed. In fact, the type of polymer used in the preparation of the hydrogels, the type of drug incorporated, the temperature and the storage time caused changes in the pH, texture and rheological behavior of topical formulations containing Lutrol(®) F-127 and Lutrol(®) F-108. Lutrol(®) F-127 hydrogels showed higher values of pH, firmness, adhesiveness and viscosity than Lutrol(®) F-108 hydrogels. The chemical nature of the drugs incorporated in these poloxamer hydrogels influence the pH of the preparations. Low percentages of drug incorporated into both types of hydrogels didn't affect significantly their textural and rheological characteristics. The hydrogels prepared with Lutrol(®) F- 127 proved to be more resistant to temperature variations, maintaining their rheological behavior over time. PMID:23886320

  10. Simultaneous removal of As, Cd, Cr, Cu, Ni and Zn from stormwater using high-efficiency industrial sorbents: Effect of pH, contact time and humic acid.

    PubMed

    Genç-Fuhrman, Hülya; Mikkelsen, Peter S; Ledin, Anna

    2016-10-01

    The effect of contact time, solution pH, and the presence of humic acid (HA) on the combined removal of As, Cd, Cr, Cu, Ni and Zn is investigated in batch tests using alumina, granulated activated carbon (GAC), and bauxsol coated sand (BCS) as sorbents. It is found that the equilibrium time for Cd, Cu, Ni and Zn is about 4h, while no clear equilibrium is observed for As and Cr. It is also found that increasing the pH until pH~8 enhanced Cd, Cu, Ni and Zn removal, but increasing the pH above this point had no major effect. In the cases of As and Cr, higher pH values (i.e. >7) decreased their removal. The presence of both 20 and 100mg/L HA suppressed the heavy metal removal except for Cr, and the suppression was higher at the higher HA concentration. Geochemical simulations suggest that this is due to the formation of dissolved HA-metal complexes preventing effective metal sorption. In the case of Cr, the presence of HA increased the removal when using alumina or BCS, while hindering the removal when using GAC. The findings show that the pH-value of the stormwater to be treated must be in the range of 6-7 in order to achieve removal of the full spectrum of metals. The results also show that natural organic matter may severely influence the removal efficiency, such that, for most metals the removal was reduced to the half, while for Cr it was increased to the double for alumina and BCS. Consequently, a properly working filter set up may not work properly anymore when receiving high loads of natural organic acids during the pollen season in spring or during defoliation in autumn and early winter, and during mixing of runoff with snowmelt having a low pH. PMID:27213673

  11. Early warning smartphone diagnostics for water security and analysis using real-time pH mapping

    NASA Astrophysics Data System (ADS)

    Hossain, Md. Arafat; Canning, John; Ast, Sandra; Rutledge, Peter J.; Jamalipour, Abbas

    2015-12-01

    Early detection of environmental disruption, unintentional or otherwise, is increasingly desired to ensure hazard minimization in many settings. Here, using a field-portable, smartphone fluorimeter to assess water quality based on the pH response of a designer probe, a map of pH of public tap water sites has been obtained. A custom designed Android application digitally processed and mapped the results utilizing the global positioning system (GPS) service of the smartphone. The map generated indicates no disruption in pH for all sites measured, and all the data are assessed to fall inside the upper limit of local government regulations, consistent with authority reported measurements. This implementation demonstrates a new security concept: network environmental forensics utilizing the potential of novel smartgrid analysis with wireless sensors for the detection of potential disruption to water quality at any point in the city. This concept is applicable across all smartgrid strategies within the next generation of the Internet of Things and can be extended on national and global scales to address a range of target analytes, both chemical and biological.

  12. Infiltration/cure modeling of resin transfer molded composite materials using advanced fiber architectures

    NASA Technical Reports Server (NTRS)

    Loos, Alfred C.; Weideman, Mark H.; Long, Edward R., Jr.; Kranbuehl, David E.; Kinsley, Philip J.; Hart, Sean M.

    1991-01-01

    A model was developed which can be used to simulate infiltration and cure of textile composites by resin transfer molding. Fabric preforms were resin infiltrated and cured using model generated optimized one-step infiltration/cure protocols. Frequency dependent electromagnetic sensing (FDEMS) was used to monitor in situ resin infiltration and cure during processing. FDEMS measurements of infiltration time, resin viscosity, and resin degree of cure agreed well with values predicted by the simulation model. Textile composites fabricated using a one-step infiltration/cure procedure were uniformly resin impregnated and void free. Fiber volume fraction measurements by the resin digestion method compared well with values predicted using the model.

  13. Ambient curing fire resistant foams

    NASA Technical Reports Server (NTRS)

    Hamermesh, C. L.; Hogenson, P. A.; Tung, C. Y.; Sawko, P. M.; Riccitiello, S. R.

    1979-01-01

    The feasibility of development of an ambient curing foam is described. The thermal stability and flame spread index of the foams were found to be comparable to those of the high-temperature cured polyimide foams by Monsanto two-foot tunnel test and NASA T-3 Fire test. Adaptation of the material to spray in place applications is described

  14. Effects of pH and sugar concentration in Zygosaccharomyces rouxii growth and time for spoilage in concentrated grape juice at isothermal and non-isothermal conditions.

    PubMed

    Rojo, M C; Arroyo López, F N; Lerena, M C; Mercado, L; Torres, A; Combina, M

    2014-04-01

    The effect of pH (1.7-3.2) and sugar concentration (64-68 °Brix) on the growth of Zygosaccharomyces rouxii MC9 using response surface methodology was studied. Experiments were carried out in concentrated grape juice inoculated with Z. rouxii at isothermal conditions (23 °C) for 60 days. pH was the variable with the highest effect on growth parameters (potential maximum growth rate and lag phase duration), although the effect of sugar concentration were also significant. In a second experiment, the time for spoilage by this microorganism in concentrated grape juice was evaluated at isothermal (23 °C) and non-isothermal conditions, in an effort to reproduce standard storage and overseas shipping temperature conditions, respectively. Results show that pH was again the environmental factor with the highest impact on delaying the spoilage of the product. Thereby, a pH value below 2.0 was enough to increase the shelf life of the product for more than 60 days in both isothermal and non-isothermal conditions. The information obtained in the present work could be used by producers and buyers to predict the growth and time for spoilage of Z. rouxii in concentrated grape juice. PMID:24290637

  15. Gastrointestinal pH and Transit Time Profiling in Healthy Volunteers Using the IntelliCap System Confirms Ileo-Colonic Release of ColoPulse Tablets

    PubMed Central

    Maurer, Jacoba M.; Schellekens, Reinout C. A.; van Rieke, Hèlen M.; Wanke, Christoph; Iordanov, Ventzeslav; Stellaard, Frans; Wutzke, Klaus D.; Dijkstra, Gerard; van der Zee, Margot; Woerdenbag, Herman J.; Frijlink, Henderik W.; Kosterink, Jos G. W.

    2015-01-01

    Introduction ColoPulse tablets are an innovative development in the field of oral dosage forms characterized by a distal ileum and colon-specific release. Previous studies in humans showed release in the ileo-colonic region, but the relationship between gastrointestinal pH and release was not experimentally proven in vivo. This information will complete the in vivo release-profile of ColoPulse tablets. Materials and Methods Release from ColoPulse tablets was studied in 16 healthy volunteers using the dual label isotope strategy. To determine gastrointestinal pH profiles and transit times the IntelliCap system was used. A ColoPulse tablet containing 13C-urea and an uncoated, immediate release tablet containing 15N2-urea were taken simultaneously followed by a standardized breakfast after three hours. Five minutes after intake of the tablets the IntelliCap capsule was swallowed and pH was measured until excretion in the feces. Breath and urine samples were collected for isotope analysis. Results Full analysis could be performed in 12 subjects. Median bioavailability of 13C -urea was 82% (95% CI 74–94%, range 61–114%). The median lag time (5% release of 13C) was 5:42 h (95% CI 5:18–6:18 h, range 2:36–6:36 h,) There was no statistically significant difference between lag time based on isotope signal and colon arrival time (CAT) based on pH (median 5:42 vs 5:31 h p = 0.903). In all subjects an intestinal pH value of 7.0 was reached before release of 13C from the ColoPulse tablet occurred. Discussion and Conclusions From the combined data from the IntelliCap system and the 13C -isotope signal it can be concluded that release from a ColoPulse tablet in vivo is not related to transit times but occurs in the ileo-colonic region after pH 7.0 is reached. This supports our earlier findings and confirms that the ColoPulse system is a promising delivery system for targeting the distal ileum and colon. Trial Registration ISRCTN Registry 18301880 PMID:26177019

  16. Adhesive curing options for photonic packaging

    NASA Astrophysics Data System (ADS)

    Martin, Steven C.; Hubert, Manfred; Tam, Robin

    2002-06-01

    Varying the intensity of illumination used to cure photoactivated adhesives has been applied in medical and dental applications to improve the performance of polymer materials. For example, it has been observed that dental polymer composite materials express reduced shrinkage, important for durability of non-amalgam restorations, by introducing a phased time-intensity cure schedule. This work identified that curing conditions could influence the final properties of materials, and suggested the possibility of extending the characteristics that could be influenced beyond shrinkage to humidity resistance, Tg, outgassing and other important material properties. Obviously, these results have important ramifications for the photonic industry, with current efforts focused on improved manufacturing techniques. Improvement in low cost packaging solutions, including adhesives, will have to be made to bring the component cost down to address the needs of Metro and similar markets. However, there are perceived problems with the widespread use of adhesives, the most prevalent of these involving long term durability of the bond. Devices are typically aligned to sub-micron precision using active feedback and then must be locked in position to maintain performance. In contrast to traditional fastening methods, adhesive bonding is a highly attractive option due to the ease of deployment, lower equipment costs, and improved flexibility. Moreover, using methods analogous to those employed in dental applications, materials properties of photonic adhesives may be tailored using a programmed cure approach.

  17. Large natural pH, CO2 and O2 fluctuations in a temperate tidal salt marsh on diel, seasonal, and interannual time scales

    USGS Publications Warehouse

    Baumann, Hannes; Wallace, Ryan; Tagliaferri, Tristen N.; Gobler, Christopher J.

    2014-01-01

    Coastal marine organisms experience dynamic pH and dissolved oxygen (DO) conditions in their natural habitats, which may impact their susceptibility to long-term anthropogenic changes. Robust characterizations of all temporal scales of natural pH and DO fluctuations in different marine habitats are needed; however, appropriate time series of pH and DO are still scarce. We used multiyear (2008–2012), high-frequency (6 min) monitoring data to quantify diel, seasonal, and interannual scales of pH and DO variability in a productive, temperate tidal salt marsh (Flax Pond, Long Island, US). pHNBS and DO showed strong and similar seasonal patterns, with average (minimum) conditions declining from 8.2 (8.1) and 12.5 (11.4) mg l−1 at the end of winter to 7.6 (7.2) and 6.3 (2.8) mg l−1 in late summer, respectively. Concomitantly, average diel fluctuations increased from 0.22 and 2.2 mg l−1 (February) to 0.74 and 6.5 mg l−1 (August), respectively. Diel patterns were modulated by tides and time of day, eliciting the most extreme minima when low tides aligned with the end of the night. Simultaneous in situ pCO2 measurements showed striking fluctuations between ∼330 and ∼1,200 (early May), ∼2,200 (mid June), and ∼4,000 μatm (end of July) within single tidal cycles. These patterns also indicate that the marsh’s strong net heterotrophy influences its adjacent estuary by ‘outwelling’ acidified and hypoxic water during ebb tides. Our analyses emphasize the coupled and fluctuating nature of pH and DO conditions in productive coastal and estuarine environments, which have yet to be adequately represented by experiments.

  18. Fiber-optic epoxy composite cure sensor. II. Performance characteristics

    NASA Astrophysics Data System (ADS)

    Lam, Kai-Yuen; Afromowitz, Martin A.

    1995-09-01

    The performance of a fiber-optic epoxy composite cure sensor, as previously proposed, depends on the optical properties and the reaction kinetics of the epoxy. The reaction kinetics of a typical epoxy system are presented. It is a third-order autocatalytic reaction with a peak observed in each isothermal reaction-rate curve. A model is derived to describe the performance characteristics of the epoxy cure sensor. If a composite coupon is cured at an isothermal temperature, the sensor signal can be used to predict the time when the gel point occurs and to monitor the cure process. The sensor is also shown to perform well in nonstoichiometric epoxy matrices. In addition the sensor can detect the end of the cure without calibration.

  19. Effect of rapid curing procedures on polymer implant materials.

    PubMed

    Gettleman, L; Nathanson, D; Myerson, R L

    1977-01-01

    This investigation of standard curing methods for PMMA implants has demonstrated that alternate means of using the air oven may produce good strength properties along with a considerable degree of porosity, when desired, in a relatively short period of time. Curing of polymers in a pressure pot offers few advantages owing to the length of time required to produce, at best, equivalent strength for the porous materials. The method also poses dangers inherent in the use of superheated salt solution or hot glycerin. The autoclave is widely used in dental offices for sterilizing and will fully and consistently cure polymers within 30 minutes. The best properties for the PMMA resin were achieved with this method (61 MPa or 9,130 p.s.i., tensile strength). The microwave oven has become relatively inexpensive in recent years, and it offers time savings of up to 90 per cent which would be beneficial in implant dentistry or in dental laboratory procedures in general. The exact condition for curing particular polymers must be carefully determined to adjust the time of irradiation in order not to under- or overcure the polymer object. Curing polymers which contain intrinsic foaming agents under pressure conditions slightly reduced the total pore volume. But, pore volume and pore diameter in the large-bead polymers are determined predominantly by packing conditions, not curing conditions. Biologic tolerance to materials cured by these methods in primates is presently being evaluated. PMID:264323

  20. Towards a 'cure' for IBD.

    PubMed

    Fiocchi, Claudio

    2012-01-01

    To discuss a cure for IBD, one should first define the concept 'a cure'. If it is intended as the general restoration of health, this is already possible, as many current therapies do a good job in inducing long periods of remission in Crohn's disease, and colectomy can technically cure ulcerative colitis. If it is more strictly defined as the complete and permanent elimination of the cause, predisposing and permissive factors, reinstatement of normal microbial ecology and restoration of mucosal immune homeostasis, then a cure for IBD is out of reach, at least for now. Regardless of the definition, major strides have been made in attempting to cure IBD by addressing the key components of its pathogenesis: the environment (exposome), the genetic makeup (genome), the gut microbiota (microbiome) and the immune system (immunome). However, the isolated modulation of each component is insufficient to provide a cure, and different requirements may be needed depending on the stage of the disease and each patient subset. To achieve a cure, one key approach is currently missing: the integration of knowledge from all the pathogenic components. We continue to learn more and more about each component using traditional 'canonical' systems, which allow the accumulation of data without taking into consideration the other components. We are still not studying the 'omes' of IBD, we should be using 'omics' technologies that can generate a more global vision of IBD pathogenesis on which to base novel, multiple pathway-integrated therapies. PMID:22796811

  1. Bioaccumulation of metals by lichens: Uptake of aqueous uranium by Peltigera membranacea as a function of time and pH

    SciTech Connect

    Haas, J.R.; Bailey, E.H.; Purvis, O.W.

    1998-11-01

    Uranium sorption experiments were carried out at {approximately}25 C using natural samples of the lichen Peltigera membranacea. Thalli were incubated in solutions containing 100 ppm U for up to 24 h at pH values from 2 to 10. Equilibrium sorption was not observed at less than {approximately}6 h under any pH condition. U sorption was strongest in the pH range 4--5, with maximum sorption occurring at a pH of 4.5 and an incubation time of 24 h. Maximum U uptake by P. membranacea averaged {approximately}42,000 ppm, or {approximately}4.2 wt% U. This appears to represent the highest concentration of biosorbed U, relative to solution U activity, of any lichen reported to date. Investigation of post-experimental lichen tissues using electron probe microanalysis (EPM) reveals that U uptake is spatially heterogeneous within the lichen body, and that U attains very high local concentrations on scattered areas of the upper cortex. Energy dispersive spectroscopic (EDS) analysis reveals that strong U uptake correlates with P signal intensity, suggesting involvement of biomass-derived phosphate ligands or surface functional groups in the uptake process.

  2. Accelerated Cure Project for Multiple Sclerosis

    MedlinePlus

    ... tweets Tweets by @AcceleratedCure Front The Accelerated Cure Project for MS is a non-profit, 501(c)( ... determines its causes and mechanisms. © 2016 Accelerated Cure Project. All rights reserved. Site Map Contact Us Privacy ...

  3. Mathematical Model Of Curing Behavior Of A Polymer

    NASA Technical Reports Server (NTRS)

    Loomis, Willard C.; Beyer, Rodney B.; Liu, Edmund K. S.

    1995-01-01

    Mathematical model predicts selected aspects of chemical, thermal and mechanical responses of polymeric liner and propellant materials during curing process. Predictions made both prior to processing and during process in quasi-real time. Developed specifically for use in designing and analyzing process in which bondline materials (including polymeric liners) and propellant cast and cured in rocket motor. With modifications, model applicable to curing of other polymeric materials. Further development may provide direct "in-line" program for calculations, including comparisons, in real time. This will constitute basis for more sophisticated control of process.

  4. Curing HIV: Moving Forward Faster.

    PubMed

    Flores, Marcella; Johnston, Rowena

    2016-02-01

    There is enormous enthusiasm in the scientific community for finding a cure for HIV. Although much remains to be discovered regarding the mechanisms of viral persistence and how it may be disrupted, some assumptions regarding the goals of a cure, applicability to target populations, and what is required of the assays we employ, may lead to missed opportunities and discoveries and hamper the discovery of a product that will safely cure tens of millions of HIV-infected people around the world. The field will benefit from an awareness and critical interrogation of assumptions that may be implicit in their scientific pursuits. PMID:26862662

  5. 34 CFR Appendix C to Part 682 - Procedures for Curing Violations of the Due Diligence in Collection and Timely Filing of Claims...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... timely filing requirements in 34 CFR 682.511. c. Borrower Deemed in Default Under Certain Circumstances... loans. Public Law 99-272 established new default periods of 180 and 240 days (as set out in 34 CFR 682... overbillings made on loans evidencing such violations. See 34 CFR 682.507, 682.511.1 These procedures allow...

  6. Characterization of the relationship of the cure cycle chemistry to cure cycle processing properties

    NASA Technical Reports Server (NTRS)

    Kranbuehl, D. E.

    1986-01-01

    Dynamic Dielectric measurements made over a wide range of frequency provide a sensitive and convenient means for monitoring the cure process in thermosets and thermoplastics. The measurement of dielectric relaxation is one of only a few instrumental techniques available for studying molecular properties in both the liquid and solid states. Furthermore, it is probably the only convenient experimental technique for studying the polymerization process of going from a monomeric liquid of varying viscosity to a crosslinked, insoluble, high temperature solid. The objective of the research is to develop on-line dielectric instrumentation for quantitative nondestructive material evaluation and closed loop smart cure cycle control. The key is to relate the chemistry of the cure cycle process to the dielectric properties of the polymer system by correlating the time, temperature, and frequency dependent dielectric measurements with chemical characterization measurements. Measurement of the wide variation in magnitude of the complex permittivity with both frequency and state of cure, coupled with chemical characterization work, have been shown in the laboratory to have the potential to determine: resin quality, composition and age; cure cycle window boundaries; onset of flow and point of maximum flow; extent of and completion of reaction; evolution of volatiles; T sub g; and, crosslinking and molecular weight buildup.

  7. Effect of three types of light-curing units on 5-year colour changes of light-cured composite.

    PubMed

    Tak, Onjen; Altintas, Subutay Han; Ozturk, Nilgun; Usumez, Aslihan

    2009-03-01

    The purpose of this study was to determine colour changes in a composite cured with tungsten-halogen, light-emitting diode (LED) or a plasma arc after 5 years. Five specimens 10 mm in diameter and 2 mm in height were prepared using Hybrid (Clearfil AP-X) composite for each test group. The corresponding specimens were cured with a tungsten-halogen curing light, a LED unit or with a plasma arc. Specimens were stored in light-proof boxes for 5 years after the curing procedure to avoid further exposure to light and stored in 37 degrees C in 100% humidity. Colorimetric values of the specimens immediately after curing and after 5 years were measured using colorimeter. The DeltaE*( ab ) values varied significantly depending on the curing unit used (p < 0.001). Curing time did not affect the colour changes of the specimens (p = 0.4). The results of this study suggest that composite materials undergo measurable changes due to the curing unit exposure. PMID:18769947

  8. Variation of Resin Properties Through the Thickness of Cured Samples

    NASA Technical Reports Server (NTRS)

    1984-01-01

    It is the purpose of this work to gain knowledge of the glassy materials used as matrices in composites and to study the homogeneity resulting from the curing process. An attempt is made to link the glass transition quantitatively with the presence of a given material. Expoxy resins containing various amounts of hardener (TGDDM/DDS system) were cured in a muffle furnace at 473 K for seven hours. The glass transition temperature, T sub g versus weight minus percent of hardener in the epoxy resin were measured. A limit was rapidly reached in T sub g at only two percent hardener. Thus, the glass transition of the fully cured epoxy-amine matrix seems not much different from the epoxide-epoxide cure. The T sub g versus cure-time for the epoxide-epoxide reaction was also studied. My 720 was cured by itself in an oil bath at 473 K for different lengths of time. The T sub g was found to increase exponentially with the cure time, and a maximum T sub g of about 450 K was reached after eleven hours. The reaction was found to be inhibited by running the sample under argon.

  9. Antibiotics Cure Anthrax in Animal Models▿

    PubMed Central

    Weiss, Shay; Kobiler, David; Levy, Haim; Pass, Avi; Ophir, Yakir; Rothschild, Nili; Tal, Arnon; Schlomovitz, Josef; Altboum, Zeev

    2011-01-01

    Respiratory anthrax, in the absence of early antibiotic treatment, is a fatal disease. This study aimed to test the efficiency of antibiotic therapy in curing infected animals and those sick with anthrax. Postexposure prophylaxis (24 h postinfection [p.i.]) of guinea pigs infected intranasally with Bacillus anthracis Vollum spores with doxycycline, ofloxacin, imipenem, and gentamicin conferred protection. However, upon termination of treatment, the animals died from respiratory anthrax. Combined treatment with antibiotics and active vaccination with a protective antigen-based vaccine leads to full protection even after cessation of treatment. Delaying the initiation of antibiotic administration to over 24 h p.i. resulted in treatment of animals with anthrax exhibiting various degrees of bacteremia and toxemia. Treatment with doxycycline or ciprofloxacin cured sick guinea pigs and rabbits exhibiting bacteremia levels up to 105 CFU/ml. Addition of anti-protective antigen (PA) antibodies augmented the efficiency of protection, allowing the cure of guinea pigs and rabbits with 10- to 20-fold-higher bacteremia levels, up to 7 × 105 CFU/ml and 2 × 106 CFU/ml, respectively. Treatment with ciprofloxacin and a monoclonal anti-PA antibody rescued rabbits with bacteremia levels up to 4 × 106 CFU/ml. During antibiotic administration, all surviving animals developed a protective immune response against development of a fatal disease and subcutaneous challenge with Vollum spores. In conclusion, these results demonstrate that antibiotic treatment can prevent the development of fatal disease in respiratory-anthrax-infected animals and can cure animals after disease establishment. A therapeutic time window of 40 h to 48 h from infection to initiation of efficient antibiotic-mediated cure was observed. PMID:21263056

  10. [Little histories of magnetic cures].

    PubMed

    Pinet, Patrice

    2009-02-01

    Men were very early fascinated by magnetism because of its manifest and particular working at distance, which looked different of gravity. It was tryed to be explained by mecanism, for exemple Descartes and Boyle. Paracelse valued the therapeutics with magnets and conceived medicines as working by a magnetic virtue. Gilbert limited the medicinal properties of magnet but helded it to be animated. Many authors praised remedies that work at distance of the evil as Bacon, Van Helmont, Croll, Porta, Goclenius, Digby. Such a belief related to magic ideas of this time. In the Bacon's way Boyle collected facts of magnetic cures, and his actual testing of the divisibility of bodies led him to conceive imponderable corpuscles. Newton supposed a subtil and universel fluid going through every solid body. Mesmer misappropriated this idea by founding the animal magnetism of which physical working was only proceeding from the inside of the patient by an effect of suggestion (psychosomatic). Homeopathy took again the notion of remedies having an infinite or a magnetic virtue, which partly issued from Paracelse's and Mesmer's doctrines, which were extolled in Germany at the time of Hahnemann. The latter decided in favour of a spiritualist and not corpuscular interpretation of the working of his homeopathic medicines. PMID:19579649

  11. Diamine curing agents for polyurethanes

    NASA Technical Reports Server (NTRS)

    Bell, V. L.; St. Clair, T. L.

    1975-01-01

    Three aromatic diamines have properties that make them promising candidates as curing agents for converting isocyanates to polyurethanes with higher adhesive strengths, higher softening temperatures, better toughness, and improved abrasion resistance.

  12. Start up partial nitrification at low temperature with a real-time control strategy based on blower frequency and pH.

    PubMed

    Gu, Shengbo; Wang, Shuying; Yang, Qing; Yang, Pei; Peng, Yongzhen

    2012-05-01

    In this study, the performance of partial nitrification via nitrite at low temperature was investigated in a pilot-scale sequencing batch reactor (SBR) with a working volume of 7.0m(3). A novel real-time control strategy, based on blower frequency (BF) and pH, was designed and evaluated. The nitrogen break point (NBP) in the BF curve and the nitrate/nitrite apex point (NAP) in the pH curve were used to identify the endpoint of the aerobic and anoxic phases, respectively. The nitrite accumulation rate (NAR) rapidly increased from 19.8% to 90%. Partial nitrification was achieved at low temperature (11-16°C) in 40 days and was stably maintained for as long as 140 days by applying a real-time control strategy based on pH and BF. Fluorescence in situ hybirdization (FISH) results demonstrated that ammonia oxidation bacteria (AOB) had developed into the dominant nitrifying bacteria compared to nitrite oxidation bacteria (NOB) in the system. PMID:22414573

  13. (31)P-MRS of healthy human brain: ATP synthesis, metabolite concentrations, pH, and T1 relaxation times.

    PubMed

    Ren, Jimin; Sherry, A Dean; Malloy, Craig R

    2015-11-01

    The conventional method for measuring brain ATP synthesis is (31)P saturation transfer (ST), a technique typically dependent on prolonged pre-saturation with γ-ATP. In this study, ATP synthesis rate in resting human brain is evaluated using EBIT (exchange kinetics by band inversion transfer), a technique based on slow recovery of γ-ATP magnetization in the absence of B1 field following co-inversion of PCr and ATP resonances with a short adiabatic pulse. The unidirectional rate constant for the Pi → γ-ATP reaction is 0.21 ± 0.04 s(-1) and the ATP synthesis rate is 9.9 ± 2.1 mmol min(-1)  kg(-1) in human brain (n = 12 subjects), consistent with the results by ST. Therefore, EBIT could be a useful alternative to ST in studying brain energy metabolism in normal physiology and under pathological conditions. In addition to ATP synthesis, all detectable (31)P signals are analyzed to determine the brain concentration of phosphorus metabolites, including UDPG at around 10 ppm, a previously reported resonance in liver tissues and now confirmed in human brain. Inversion recovery measurements indicate that UDPG, like its diphosphate analogue NAD, has apparent T1 shorter than that of monophosphates (Pi, PMEs, and PDEs) but longer than that of triphosphate ATP, highlighting the significance of the (31)P-(31)P dipolar mechanism in T1 relaxation of polyphosphates. Another interesting finding is the observation of approximately 40% shorter T1 for intracellular Pi relative to extracellular Pi, attributed to the modulation by the intracellular phosphoryl exchange reaction Pi ↔ γ-ATP. The sufficiently separated intra- and extracellular Pi signals also permit the distinction of pH between intra- and extracellular environments (pH 7.0 versus pH 7.4). In summary, quantitative (31)P MRS in combination with ATP synthesis, pH, and T1 relaxation measurements may offer a promising tool to detect biochemical alterations at early stages of brain dysfunctions and diseases

  14. Photothermal Monitoring Of Curing Of Polymers

    NASA Technical Reports Server (NTRS)

    Rooney, Michael

    1993-01-01

    Time-resolved infrared radiometry (TRIR) adapted to monitoring curing of some polymers in production. Proposal part of continuing effort to perfect production of hydroxy-terminated polybutadiene for use in liners of solid-fuel rocket motors. Applicable to monitoring changing states of many other materials in process. TRIR, non-contact technique implemented with remotely situated equipment and better suited to use in production.

  15. Fulvic acid sorption on muscovite mica as a function of pH and time using in situ X-ray reflectivity.

    PubMed

    Lee, Sang Soo; Fenter, Paul; Park, Changyong; Nagy, Kathryn L

    2008-08-01

    Interfacial structures of the basal surface of muscovite mica in 100 mg kg (-1) Elliott Soil Fulvic Acid II solutions were investigated using in situ X-ray reflectivity. Molecular-scale variations in the thickness and internal structure of the fulvic acid (FA) film were observed and quantified as a function of pH (2-12) and reaction time (3-500 h at pH 3.7). At pH < or =6, the electron-density profile of the FA layer sorbed on the muscovite surface was composed of one near-surface peak followed by a broad peak that diminished in electron density with distance from the surface. The presence of the near-surface peak is attributed to condensation of FA molecules during sorption. The apparent thickness of the FA layer decreased from 12.3 to 7.2 to 6.4 A as pH increased from 2 to 3.7 to 6, respectively. At pH > or =8.5, a distinct interfacial structure was observed, consisting of sharper peaks similar to those previously observed for muscovite in the absence of FA. These peaks are most likely composed of smaller aqueous species, such as H 2O molecules, metal ion impurities from FA, and Na (+) from NaOH. The FA sorbed on the muscovite surface at pH 3.7 maintained a relatively constant thickness after 3 hours. However, the electron density of the near-surface FA peak increased by about 24% from 3 to 12 hours, and remained relatively constant from 12 to 500 hours. The electron density of the more distant part of the sorbed FA layer increased slightly after 12-50 hours of reaction but then decreased, and the broad peak flattened by 500 hours. Internal structural changes are possibly due to the slow sorption rate of FA molecules, or a fractionation effect, i.e., continuous subsitution of smaller FA molecules by larger FA molecules. PMID:18616301

  16. Comprehensive study of dynamic curing effect on tablet coating structure.

    PubMed

    Gendre, Claire; Genty, Muriel; da Silva, Julio César; Tfayli, Ali; Boiret, Mathieu; Lecoq, Olivier; Baron, Michel; Chaminade, Pierre; Péan, Jean Manuel

    2012-08-01

    The dissolution method is still widely used to determine curing end-points to ensure long-term stability of film coatings. Nevertheless, the process of curing has not yet been fully investigated. For the first time, joint techniques were used to elucidate the mechanisms of dynamic curing over time from ethylcellulose (Aquacoat)-based coated tablets. X-ray micro-computed tomography (XμCT), Near Infrared (NIR), and Raman spectroscopies as well as X-ray microdiffraction were employed as non-destructive techniques to perform direct measurements on tablets. All techniques indicated that after a dynamic curing period of 4h, reproducible drug release can be achieved and no changes in the microstructure of the coating were any longer detected. XμCT analysis highlighted the reduced internal porosity, while both NIR and Raman measurements showed that spectral information remained unaltered after further curing. X-ray microdiffraction revealed densification of the coating layer with a decrease in the overall coating thickness of about 10 μm as a result of curing. In addition, coating heterogeneity attributed to cetyl alcohol was observed from microscopic images and Raman analysis. This observation was confirmed by X-ray microdiffraction that showed that crystalline cetyl alcohol melted and spread over the coating surface with curing. Prior to curing, X-ray microdiffraction also revealed the existence of two coating zones differing in crystalline cetyl alcohol and sodium lauryl sulfate concentrations which could be explained by migration of these constituents within the coating layer. Therefore, the use of non-destructive techniques allowed new insights into tablet coating structures and provided precise determination of the curing end-point compared to traditional dissolution testing. This thorough study may open up new possibilities for process and formulation control. PMID:22561957

  17. Arterial pH and Blood Lactate Levels of Anesthetized Mongolian Khulan ( Equus hemionus hemionus) in the Mongolian Gobi Correlate with Induction Time.

    PubMed

    Gerritsmann, Hanno; Stalder, Gabrielle L; Kaczensky, Petra; Buuveibaatar, Bayarbaatar; Payne, John; Boldbaatar, Sukhbaatar; Walzer, Chris

    2016-07-01

    Research and conservation of wide-ranging wild equids in most cases necessitate capture and handling of individuals. For free-roaming Mongolian khulan ( Equus hemionus hemionus), also known as the khulan, capture involves a strenuous, high-speed chase, and physiologic responses have yet to be elucidated. We analyzed sequential arterial blood gas (ABG) samples as a proxy for respiratory and metabolic status of khulan during capture-related anesthesia. We recorded precise chase and induction times and monitored vital parameters and ABG from free-ranging khulan during anesthesia performed for GPS collaring. At the initiation of anesthesia, animals had ABG values similar to those recorded for thoroughbred horses ( Equus caballus ) after maximal exercise. Longer induction times resulted in higher arterial pH (P<0.001) and lower blood lactate (P<0.002). This trend of improvement continued over the course of anesthesia. The most important factor explaining pH and lactate was the time that elapsed between cessation of the chase and obtaining the first ABG sample, which, under field conditions, is tightly linked to induction time. All animals recovered uneventfully. Our data show that khulan recover and shift their metabolic status back toward expected normal values during opioid-based field anesthesia. PMID:27243152

  18. Contactless optoelectronic technique for monitoring epoxy cure.

    PubMed

    Cusano, A; Buonocore, V; Breglio, G; Calabrò, A; Giordano, M; Cutolo, A; Nicolais, L

    2000-03-01

    We describe a novel noninvasive optical technique to monitor the refractive-index variation in an epoxy-based resin that is due to the polymerization process. This kind of resin is widely used in polymer matrix composites. It is well known that the process of fabricating a thermoset-based composite involves mass and heat transfer coupled with irreversible chemical reactions that induce physical changes. To improve the quality and the reliability of these materials, monitoring the cure and optimization of the manufacturing process are of key importance. We discuss the basic operating principles of an optical system based on angle deflection measurements and present typical cure-monitoring results obtained from optical characterization. The method provides a flexible, high-sensitivity, material-independent, low-cost, noninvasive tool for monitoring real-time refractive-index variation. PMID:18337994

  19. What Will It Take to Cure HIV?

    PubMed

    Ananworanich, Jintanat

    2015-01-01

    Investigational strategies to attempt HIV cure or remission include very early initiation of antiretroviral therapy to limit the latent HIV reservoir and preinfection vaccination. In the setting of viral suppression, strategies include reactivation of latently infected cells (eg, through "shock" therapy with histone deacetylase inhibitors or other agents); use of broadly neutralizing antibodies, therapeutic vaccines, immunotoxins, or other immune-based therapies to kill latently infected cells; and gene editing to induce target cell resistance (eg, by eliminating the CC chemokine receptor 5 [CCR5] coreceptor). Improved ability to detect and quantify very low levels of virus is needed. This article summarizes a presentation by Jintanat Ananworanich, MD, PhD, at the IAS-USA continuing education program held in New York, New York, in October 2014. PMID:26200707

  20. Electron Beam Cured Epoxy Resin Composites for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Janke, Christopher J.; Dorsey, George F.; Havens, Stephen J.; Lopata, Vincent J.; Meador, Michael A.

    1997-01-01

    Electron beam curing of Polymer Matrix Composites (PMC's) is a nonthermal, nonautoclave curing process that has been demonstrated to be a cost effective and advantageous alternative to conventional thermal curing. Advantages of electron beam curing include: reduced manufacturing costs; significantly reduced curing times; improvements in part quality and performance; reduced environmental and health concerns; and improvement in material handling. In 1994 a Cooperative Research and Development Agreement (CRADA), sponsored by the Department of Energy Defense Programs and 10 industrial partners, was established to advance the electron beam curing of PMC technology. Over the last several years a significant amount of effort within the CRADA has been devoted to the development and optimization of resin systems and PMCs that match the performance of thermal cured composites. This highly successful materials development effort has resulted in a board family of high performance, electron beam curable cationic epoxy resin systems possessing a wide range of excellent processing and property profiles. Hundreds of resin systems, both toughened and untoughened, offering unlimited formulation and processing flexibility have been developed and evaluated in the CRADA program.

  1. Factors affecting dry-cured ham consumer acceptability.

    PubMed

    Morales, R; Guerrero, L; Aguiar, A P S; Guàrdia, M D; Gou, P

    2013-11-01

    The objectives of the present study were (1) to compare the relative importance of price, processing time, texture and intramuscular fat in purchase intention of dry-cured ham through conjoint analysis, (2) to evaluate the effect of dry-cured ham appearance on consumer expectations, and (3) to describe the consumer sensory preferences of dry-cured ham using external preference mapping. Texture and processing time influenced the consumer preferences in conjoint analysis. Red colour intensity, colour uniformity, external fat and white film presence/absence influenced consumer expectations. The consumer disliked hams with bitter and metallic flavour and with excessive saltiness and piquantness. Differences between expected and experienced acceptability were found, which indicates that the visual preference of consumers does not allow them to select a dry-cured ham that satisfies their sensory preferences of flavour and texture. PMID:23816516

  2. DBP formation in hot and cold water across a simulated distribution system: effect of incubation time, heating time, pH, chlorine dose, and incubation temperature.

    PubMed

    Liu, Boning; Reckhow, David A

    2013-10-15

    This paper demonstrates that disinfection byproducts (DBP) concentration profiles in heated water were quite different from the DBP concentrations in the cold tap water. Chloroform concentrations in the heated water remained constant or even decreased slightly with increasing distribution system water age. The amount of dichloroacetic acid (DCAA) was much higher in the heated water than in the cold water; however, the maximum levels in heated water with different distribution system water ages did not differ substantially. The levels of trichloroacetic acid (TCAA) in the heated water were similar to the TCAA levels in the tap water, and a slight reduction was observed after the tap water was heated for 24 h. Regardless of water age, significant reductions of nonregulated DBPs were observed after the tap water was heated for 24 h. For tap water with lower water ages, there were significant increases in dichloroacetonitrile (DCAN), chloropicrin (CP), and 1,1-dichloropropane (1,1-DCP) after a short period of heating. Heating of the tap water with low pH led to a more significant increase of chloroform and a more significant short-term increase of DCAN. High pH accelerated the loss of the nonregulated DBPs in the heated water. The results indicated that as the chlorine doses increased, levels of chloroform and DCAA in the heated water increased significantly. However, for TCAA, the thermally induced increase in concentration was only notable for the chlorinated water with very high chlorine dose. Finally, heating may lead to higher DBP concentrations in chlorinated water with lower distribution system temperatures. PMID:24044418

  3. Curing Behavior and Viscoelasticity of Dual-Curable Adhesives Based on High-Reactivity Azo Initiator

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Gyu; Shim, Gyu-Seong; Park, Ji-Won; Kim, Hyun-Joong; Moon, Sang-Eun; Kim, Young-Kwan; No, Dong-Hun; Kim, Jong-Hwan; Han, Kwan-Young

    2016-04-01

    We have investigated the curing behavior of dual-curable acrylic resin to solve problems associated with curing of adhesives in shaded areas during display manufacture. A low-temperature curing-type thermal initiator, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), with a 30°C half-life decomposition temperature was used in the investigation. Dual-curable adhesives were prepared according to the thermal initiator content and ultraviolet (UV) radiation dose. The effects of thermal initiator and UV irradiation on the curing behavior and viscoelasticity were investigated. Using Fourier-transform infrared spectroscopy and gel-fraction analysis, an evaluation was carried out to determine the degree of curing after dual UV/thermal curing. In addition, the real-time curing behavior was evaluated using thermogravimetric analysis, differential scanning calorimetry, and a UV/advanced rheometric expansion system. A lift-off test was carried out to verify the effects of dual curing on adhesion performance. Application of UV irradiation before thermal curing suppressed the thermal curing efficiency. Also, the network structure formed after dual curing with low UV dose showed higher crosslinking density. Therefore, the thermal initiator radical effectively influenced uncured areas with low curing temperature and initiator content without causing problems in UV-curable zones.

  4. Curing Behavior and Viscoelasticity of Dual-Curable Adhesives Based on High-Reactivity Azo Initiator

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Gyu; Shim, Gyu-Seong; Park, Ji-Won; Kim, Hyun-Joong; Moon, Sang-Eun; Kim, Young-Kwan; No, Dong-Hun; Kim, Jong-Hwan; Han, Kwan-Young

    2016-07-01

    We have investigated the curing behavior of dual-curable acrylic resin to solve problems associated with curing of adhesives in shaded areas during display manufacture. A low-temperature curing-type thermal initiator, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), with a 30°C half-life decomposition temperature was used in the investigation. Dual-curable adhesives were prepared according to the thermal initiator content and ultraviolet (UV) radiation dose. The effects of thermal initiator and UV irradiation on the curing behavior and viscoelasticity were investigated. Using Fourier-transform infrared spectroscopy and gel-fraction analysis, an evaluation was carried out to determine the degree of curing after dual UV/thermal curing. In addition, the real-time curing behavior was evaluated using thermogravimetric analysis, differential scanning calorimetry, and a UV/advanced rheometric expansion system. A lift-off test was carried out to verify the effects of dual curing on adhesion performance. Application of UV irradiation before thermal curing suppressed the thermal curing efficiency. Also, the network structure formed after dual curing with low UV dose showed higher crosslinking density. Therefore, the thermal initiator radical effectively influenced uncured areas with low curing temperature and initiator content without causing problems in UV-curable zones.

  5. Shear Bond Strength of Acidic Primer, Light-Cure Glass Ionomer, Light-Cure and Self Cure Composite Adhesive Systems - An In Vitro Study

    PubMed Central

    D, Krishnakanth Reddy; V, Kishore M S; Safeena, Safeena

    2013-01-01

    Background: The purpose of this study was to determine shear bond strength and the effect on the bracket/ adhesive failure mode when an acidic primer and other etchants were used to condition the enamel surface before bonding. Materials & Methods: Group I: Brackets bonded with Ultimate cure-on-light Light-cure composite adhesive system. Group II: Brackets bonded with Ortho-one no-mix. Self-cure composite adhesive system. Group III: Brackets bonded with Light-cure glass ionomer adhesive system. Group IV: Brackets bonded with Transbond plus self etching primer. Results: The results of this study indicated that the shear bond strength when using Transbond plus self etching primer showed the highest bond strength Group- IV(8.69 2.54 MPa) followed by Ultimate cure-on-light Group-I (8.62 1.84 MPa), Ortho-one no-mix (Bisco Inc. USA)Group-II (8.07 1.72 MPa), and least bond strength was seen in G.C. Fuji Ortho L.C. Group-III (6.01 1.6) MPa Conclusion: Use of self etching primer saves chairside time and satisfactory high bond strength was obtained. Care should be taken during debonding of ceramic brackets How to cite this article: Reddy K D, Kishore M S V, Safeena S. Shear Bond Strength of Acidic Primer, Light-Cure Glass Ionomer, Light-Cure and Self Cure Composite Adhesive Systems - An In Vitro Study. J Int Oral Health 2013; 5(3):73-78. PMID:24155606

  6. Effects of the Treating Time on Microstructure and Erosion Corrosion Behavior of Salt-Bath-Nitrided 17-4PH Stainless Steel

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Lin, Yuanhua; Li, Mingxing; Fan, Hongyuan; Zeng, Dezhi; Xiong, Ji

    2013-08-01

    The effects of salt-bath nitriding time on the microstructure, microhardness, and erosion-corrosion behavior of nitrided 17-4PH stainless steel at 703 K (430 °C) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and erosion-corrosion testing. The experimental results revealed that the microstructure and phase constituents of the nitrided surface alloy are highly process condition dependent. When 17-4PH stainless steel was subjected to complex salt-bathing nitriding, the main phase of the nitrided layer was expanded martensite ( α`), expanded austenite (S), CrN, Fe4N, and Fe2N. The thickness of nitrided layers increased with the treating time. The salt-bath nitriding improves effectively the surface hardness. The maximum values measured from the treated surface are observed to be 1100 HV0.1 for 40 hours approximately, which is about 3.5 times as hard as the untreated material (309 HV0.1). Low-temperature nitriding can improve the erosion-corrosion resistance against two-phase flow. The sample nitrided for 4 hours has the best corrosion resistance.

  7. Electron beam curing of epoxy resins by cationic polymerization

    SciTech Connect

    Janke, C.J.; Dorsey, G.F.; Havens, S.J.

    1996-12-31

    A Cooperative Research and Development Agreement (CRADA) sponsored by the Department of Energy Defense Programs and 10 industrial partners has been established to develop high performance Electron Beam (EB) curable polymer matrix composites. EB curing of composites has a number of advantages over conventional thermal curing. Composites cured by EB have much shorter cure times, lower overall energy requirements, and reduced thermal stresses in the cured part. Furthermore, less expensive tooling can be used since the process occurs at lower temperatures. Preliminary investigations have determined that conventional epoxy resins can be cured at selectable temperatures with high glass transition temperatures (essentially the same as with thermal curing), while still exhibiting equivalent or comparable mechanical properties. A cationic photoinitiator at a concentration of 1-3 parts per hundred of the epoxy resin is required for this process. Gamma cell screening of cationic photoinitiators with bisphenol A, bisphenol F, and cycloaliphatic epoxies demonstrated that diaryliodonium salts of weakly nucleophilic anions such as hexafluoroantimonate are most effective. Diaryliodonium salts were also found to be the most effective initiators for the cationic polymerization of epoxy resins when a high energy/power electron beam accelerator was used as the source of ionizing radiation. For example Dow Tactix 123 (bisphenol A epoxy) containing 3 phr (4-octyloxyphenyl) phenyliodonium hexafluoroantimonate was irradiated at a total dosage of 100 kGy. Glass transition temperature (tan delta) of the cured material as determined by dynamic mechanical analysis was 182{degrees}C as compared to 165{degrees}C for the thermally cured material.

  8. [Mineral water as a cure].

    PubMed

    Nocco, Priska Binz

    2008-01-01

    The treatment of diseases with mineral spring water belongs to the oldest medical therapies. The "remedy" mineral water is therefore of importance also within the pharmacy. The present pharmacy historical work examines the impact of the use of mineral waters, as well as of their dried components, as therapeutic agents in the 19th and early 20th centuries, i.e. from approx. 1810 to 1930, as well as the contributions given by pharmacists in the development and analysis of mineral water springs. Beside these aspects, the aim here is also to describe the role played by pharmacists in the production of artificial mineral water as well as in the sale and wholesale of natural and artificial mineral water. In the first part of this work the situation in Switzerland and its surrounding countries, such as Germany, France, Italy and Austria, is discussed. The second part contains a case-study of the particular situation in the Canton Tessin. It is known from the scientific literature published at that time that information on mineral water was frequently reported. Starting from the beginning of the 19th century the number of such publications increased tremendously. The major part of them were publications in scientific journals or contributions to medical and pharmaceutical manuals and reference books. In particular the spa-related literature, such as spa-guides, was of growing interest to a broad public. The inclusion of monographs into the Swiss, the Cantonal as well the foreign pharmacopoeias granted a legal frame for the mineral waters and their dried components. These works are of major importance from a pharmacy historical standpoint and represent a unique proof of historical evidence of the old medicinal drug heritage. The most frequently used therapies based on mineral waters were drinking and bath cures. Several diseases, particularly those of a chronic character, were treated with mineral waters. The positive influence of these cures on the recovery of the patients

  9. Measurement of surface stay times for physical adsorption of gases. Ph.D. Thesis - Va. Univ.; [using molecular beam time of flight technique

    NASA Technical Reports Server (NTRS)

    Wilmoth, R. G.

    1973-01-01

    A molecular beam time-of-flight technique is studied as a means of determining surface stay times for physical adsorption. The experimental approach consists of pulsing a molecular beam, allowing the pulse to strike an adsorbing surface and detecting the molecular pulse after it has subsequently desorbed. The technique is also found to be useful for general studies of adsorption under nonequilibrium conditions including the study of adsorbate-adsorbate interactions. The shape of the detected pulse is analyzed in detail for a first-order desorption process. For mean stay times, tau, less than the mean molecular transit times involved, the peak of the detected pulse is delayed by an amount approximately equal to tau. For tau much greater than these transit times, the detected pulse should decay as exp(-t/tau). However, for stay times of the order of the transit times, both the molecular speed distributions and the incident pulse duration time must be taken into account.

  10. Time-domain finite elements in optimal control with application to launch-vehicle guidance. PhD. Thesis

    NASA Technical Reports Server (NTRS)

    Bless, Robert R.

    1991-01-01

    A time-domain finite element method is developed for optimal control problems. The theory derived is general enough to handle a large class of problems including optimal control problems that are continuous in the states and controls, problems with discontinuities in the states and/or system equations, problems with control inequality constraints, problems with state inequality constraints, or problems involving any combination of the above. The theory is developed in such a way that no numerical quadrature is necessary regardless of the degree of nonlinearity in the equations. Also, the same shape functions may be employed for every problem because all strong boundary conditions are transformed into natural or weak boundary conditions. In addition, the resulting nonlinear algebraic equations are very sparse. Use of sparse matrix solvers allows for the rapid and accurate solution of very difficult optimization problems. The formulation is applied to launch-vehicle trajectory optimization problems, and results show that real-time optimal guidance is realizable with this method. Finally, a general problem solving environment is created for solving a large class of optimal control problems. The algorithm uses both FORTRAN and a symbolic computation program to solve problems with a minimum of user interaction. The use of symbolic computation eliminates the need for user-written subroutines which greatly reduces the setup time for solving problems.

  11. Challenging Roadblocks to Cancer Cure.

    PubMed

    Loda, Massimo

    2016-09-01

    The Pezcoller Symposium in Trento, Italy, June 2015, focused entirely on the question of why advanced cancer cure is so uncommon despite the extraordinarily rapid growth of invaluable therapeutic information. Participants were asked to define and to critically evaluate real and potential obstacles to permanent disease eradication. High-level concepts on potential road blocks to cures as well as opportunities for intervention in diverse areas of investigation ranging from genomic alterations to metabolism, microenvironment, immunity, and mechanotransduction were discussed. Provocative concepts and novel therapeutic avenues were proposed. What follows is a critical analysis of the highlights of this meeting. Cancer Res; 76(17); 4924-30. ©2016 AACR. PMID:27520451

  12. Dynamically cured thermoplastic olefin polymers

    SciTech Connect

    Hazelton, D.R.; Puydak, R.C.; Booth, D.A.

    1986-08-19

    A thermoplastic composition is described comprising a polyolefin resin, a first rubber component selected from the group consisting of polyisobutylene, and ethylene propylene copolymer (EPM) and EPDM and a second rubber component selected from the group consisting of halogenated butyl rubber and polychoroprene, the second rubber component being cured utilizing a curative other than a peroxide, which is a vulcanizing agent for the second rubber but not for the first rubber, the second rubber being cured to a fully vulcanized state by dynamic vulcanization in the presence of the polyolefin resin and first rubber compound.

  13. The viscoelasticity of curing thermosets

    SciTech Connect

    Adolf, D.; Martin, J.E.

    1990-01-01

    As a crosslinking polymer cures, dramatic changes in molecular architecture occur. These structural changes in turn affect the viscoelastic behavior of the material. At a critical extent of reaction (the gel point), the polymer undergoes a transition from a viscous liquid to an elastic solid. We have monitored the evolution of structure and viscoelasticity in an epoxy encapsulant used at Sandia, the diglycidyl ether of Bisphenol A (BADGE) cured with diethanolamine (DEA). The structure evolves according to percolation theory, and the viscoelasticity evolves according to out dynamic scaling theory for branched polymers. 7 refs., 4 figs.

  14. Advances in light curing adhesives

    NASA Astrophysics Data System (ADS)

    Bachmann, Andy

    2001-11-01

    This paper describes the development of a new family of light curing adhesives containing a new reactive additive previously not used in optical grade light curing adhesives are obtained with the addition of functionalized cellulositics. Outgassing as low as 10-6 grams/gram has been observed based on headspace sampling. Other additives have lowered the shrinkage rates of positioning adhesives from near 1 percent to less than 0.1 percent with fractional, percentage movements over thermal range of -40 degrees C to +200 degrees C.

  15. Real-time detection and data acquisition system for the left ventricular outline. Ph.D. Thesis - Stanford Univ.

    NASA Technical Reports Server (NTRS)

    Reiber, J. H. C.

    1976-01-01

    To automate the data acquisition procedure, a real-time contour detection and data acquisition system for the left ventricular outline was developed using video techniques. The X-ray image of the contrast-filled left ventricle is stored for subsequent processing on film (cineangiogram), video tape or disc. The cineangiogram is converted into video format using a television camera. The video signal from either the TV camera, video tape or disc is the input signal to the system. The contour detection is based on a dynamic thresholding technique. Since the left ventricular outline is a smooth continuous function, for each contour side a narrow expectation window is defined in which the next borderpoint will be detected. A computer interface was designed and built for the online acquisition of the coordinates using a PDP-12 computer. The advantage of this system over other available systems is its potential for online, real-time acquisition of the left ventricular size and shape during angiocardiography.

  16. Transformation of deoxynivalenol and its acetylated derivatives in Chinese steamed bread making, as affected by pH, yeast, and steaming time.

    PubMed

    Wu, Li; Wang, Bujun

    2016-07-01

    We hereby report the transformation of deoxynivalenol (DON) and its acetylated derivatives (3-ADON and 15-ADON) by spiking targeted mycotoxins to Fusarium mycotoxin-free flour in the process of making Chinese steamed bread (CSB). The impacts of pH, yeast level, and steaming time on the transformation of 3-ADON to DON were investigated. DON, 3-ADON, and 15-ADON were analyzed by UPLC-MS/MS. Spiked DON was stable throughout the CSB making process. Spiked 3-ADON and 15-ADON were partially deacetylated and transformed to DON during kneading (54.1-60.0% and 59.3-77.5%, respectively), fermentation (64.0-76.9% and 78.2-91.6%, respectively), and steaming (47.2-52.7% and 52.4-61.9%, respectively). The ADONs level increased after steaming compared with their level in the previous step. The pH level and steaming duration significantly (P<0.05) affected the conversion of 3-ADON during the CSB making process. Briefly, alkaline conditions and short steaming times favored the deacetylation of 3-ADON. The level of yeast did not remarkably (P<0.05) alter the transformation between ADONs and DON. PMID:26920279

  17. Delayed cure bismaleimide resins

    DOEpatents

    Not Available

    1982-08-12

    Prior art polybismaleimides begin to polymerize at or just above the melting point of the monomer. This patent describes new bismaleimide resins which have an increased pot life and provide longer time periods in which the monomer remains fluid. The resins can be polymerized into molded articles with a high uniformity of properties. (DLC)

  18. Cure characterization of thick polyester composite structures using dielectric and finite difference analysis

    SciTech Connect

    Day, D.R.

    1993-12-31

    Disposable and permanently mounted dielectric sensors were used to characterize the cure in polyester sheet molding compound (SMC) at various locations through the thickness of the part in a simulated molding environment. Using established techniques, the dielectric and temperature information were combined to yield local cure state information for each sensor. Parts under five millimeters thick were found to cure rather uniformly while parts greater than this had increasing degrees of nonuniformity in cure behavior through the thickness. These observed cure state data were compared to finite difference model predictions. The model predictions, which were confirmed by the sensor cure data, may be used to optimize part design and production by predicting the curing behavior and molding cycle time required for new structures.

  19. Better than a cure.

    PubMed

    Adshead, Fiona; Thorpe, Allison

    2006-11-01

    A brief glance through the national papers and medical press shows the depth of concern with the cost of delivering high quality, free at the point of access healthcare to the population. However, at a time of increasingly greater demands being placed on public health systems across the globe, the question of how we can make health and healthcare both accessible to everyone and sustainable in the long term is being posed. In this paper we provide an insight into how England is responding to these challenges. PMID:17034824

  20. Electron Beam-Cure Polymer Matrix Composites: Processing and Properties

    NASA Technical Reports Server (NTRS)

    Wrenn, G.; Frame, B.; Jensen, B.; Nettles, A.

    2001-01-01

    Researchers from NASA and Oak Ridge National Laboratory are evaluating a series of electron beam curable composites for application in reusable launch vehicle airframe and propulsion systems. Objectives are to develop electron beam curable composites that are useful at cryogenic to elevated temperatures (-217 C to 200 C), validate key mechanical properties of these composites, and demonstrate cost-saving fabrication methods at the subcomponent level. Electron beam curing of polymer matrix composites is an enabling capability for production of aerospace structures in a non-autoclave process. Payoffs of this technology will be fabrication of composite structures at room temperature, reduced tooling cost and cure time, and improvements in component durability. This presentation covers the results of material property evaluations for electron beam-cured composites made with either unidirectional tape or woven fabric architectures. Resin systems have been evaluated for performance in ambient, cryogenic, and elevated temperature conditions. Results for electron beam composites and similar composites cured in conventional processes are reviewed for comparison. Fabrication demonstrations were also performed for electron beam-cured composite airframe and propulsion piping subcomponents. These parts have been built to validate manufacturing methods with electron beam composite materials, to evaluate electron beam curing processing parameters, and to demonstrate lightweight, low-cost tooling options.

  1. Lower-curing-temperature PMR polyimides

    NASA Technical Reports Server (NTRS)

    Delvigs, P.

    1982-01-01

    Partial substitution of a p-aminostyrene end-cap for the monomethyl ester of 5-norbornene-2, 3-dicarboxylic acid lowered the final cure temperature of typical PMR resins from 600 F to 500 F. The weight loss characteristics of neat resins and graphite fiber composites prepared by using the mixed end-cap approach were determined at 600 F. The room temperature and short-time elevated temperature mechanical properties of the composites at 550 F and 600 F were determined. The mechanical property retention characteristics of the composites at 550 F and 600 F are discussed.

  2. Changes on physico-chemical, textural, lipolysis and volatile compounds during the manufacture of dry-cured foal "cecina".

    PubMed

    Lorenzo, José M

    2014-01-01

    The changes in the physico-chemical and textural properties, lipolysis and volatile compounds during the manufacture of dry-cured foal "cecina" were studied. The pH increased during the last stages of processing but gradually declined over the curing period. TBARS values, hardness and chewiness increased with processing time from 0.14, 2.74 and 0.83 to 3.49 mg malonaldehyde/kg, 20.33 kg and 5.05 kg∗mm, respectively. Ripening time also affected the colour parameters: lightness (L*), redness (a*) and yellowness (b*) (P<0.001). The total average content of free fatty acid (FFA) increased significantly from 433.7 mg/100 g of fat in the raw pieces to 2655.5 mg/100 g of fat at the end of the drying-ripening stage. The main FFA at the end of the manufacturing process was palmitic acid (C16:0), followed by oleic (C18:1cis9), stearic (C18:0) and linoleic (C18:2n-6). A total of fifty five volatile compounds were identified during the manufacture of dry-cured foal "cecina", including esters, aldehydes, aliphatic hydrocarbons, branched hydrocarbons, alcohols, aromatic hydrocarbons, furans, ketones. Aldehydes reached their maximum level at the end of the post-salting stage. In the final product, esters became the dominant chemical compounds. PMID:23916960

  3. Out-of-Autoclave Cure Composites

    NASA Technical Reports Server (NTRS)

    Hayes, Brian S.

    2015-01-01

    As the size of aerospace composite parts exceeds that of even the largest autoclaves, the development of new out-of-autoclave processes and materials is necessary to ensure quality and performance. Many out-of-autoclave prepreg systems can produce high-quality composites initially; however, due to long layup times, the resin advancement commonly causes high void content and variations in fiber volume. Applied Poleramic, Inc. (API), developed an aerospace-grade benzoxazine matrix composite prepreg material that offers more than a year out-time at ambient conditions and provides exceptionally low void content when out-of-autoclave cured. When compared with aerospace epoxy prepreg systems, API's innovation offers significant improvements in terms of out-time at ambient temperature and the corresponding tack retention. The carbon fiber composites developed with the optimized matrix technology have significantly better mechanical performance in terms of hot-wet retention and compression when compared with aerospace epoxy matrices. These composites also offer an excellent overall balance of properties. This matrix system imparts very low cure shrinkage, low coefficient of thermal expansion, and low density when compared with most aerospace epoxy prepreg materials.

  4. Effect of pH, ionic strength, dissolved organic carbon, time, and particle size on metals release from mine drainage impacted streambed sediments.

    PubMed

    Butler, Barbara A

    2009-03-01

    Acid-mine drainage (AMD) input to a stream typically results in the stream having a reduced pH, increased concentrations of metals and salts, and decreased biological productivity. Removal and/or treatment of these AMD sources is desired to return the impacted stream(s) to initial conditions, or at least to conditions suitable for restoration of the aquatic ecosystem. Some expected changes in the water chemistry of the stream following removal of AMD input include an increase in pH, a decrease in ionic strength, and an increase in dissolved organic carbon (DOC) concentrations from increased biological activity in the absence of toxic metals concentrations. These changes in water chemistry may cause the existing contaminated bed sediments to become a source of metals to the stream water. Streambed sediments, collected from North Fork Clear Creek (NFCC), Colorado, currently impacted by AMD, were assessed for the effects of pH, ionic strength, DOC concentration, time, and particle size on metals release using a factorial design. The design included two levels for each chemical parameter (ionic strength = 40 and 80% lower than ambient; pH = 6 and 8; and DOC = 1 and 3 mg/l higher than ambient), ten sampling times (from zero to 48 h), and two size fractions of sediments (63 microm < or = x < 2 mm and < 63 microm). Greater concentrations of metals were released from the smaller sized sediments compared with the larger, with the exception of Cu. A mild acid digestion (0.6M HCl) evaluated the amount of each metal that could be removed easily from each of the sediment size fractions. Release of all metals over all time points, treatments, and from both sediment sizes was less than 1% of the extractable concentrations, with the exception of Mn, which ranged from 4 to 7% from the smaller sized sediment. Greater percentages of the 0.6M HCl-extractable concentrations of Cu, Fe, and Zn were released from the larger sized sediment, while this was true for release of Cd and Mn from

  5. 7 CFR 30.10 - Cure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Cure. 30.10 Section 30.10 Agriculture Regulations of... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.10 Cure. To dry the sap from newly harvested tobacco by either natural or artificial process. Proper curing...

  6. 7 CFR 51.1412 - Well cured.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Well cured. 51.1412 Section 51.1412 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Pecans in the Shell 1 Definitions § 51.1412 Well cured. Well cured means that...

  7. 7 CFR 51.1412 - Well cured.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Well cured. 51.1412 Section 51.1412 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Pecans in the Shell 1 Definitions § 51.1412 Well cured. Well cured means that...

  8. Chromothriptic cure of WHIM syndrome.

    PubMed

    McDermott, David H; Gao, Ji-Liang; Liu, Qian; Siwicki, Marie; Martens, Craig; Jacobs, Paejonette; Velez, Daniel; Yim, Erin; Bryke, Christine R; Hsu, Nancy; Dai, Zunyan; Marquesen, Martha M; Stregevsky, Elina; Kwatemaa, Nana; Theobald, Narda; Long Priel, Debra A; Pittaluga, Stefania; Raffeld, Mark A; Calvo, Katherine R; Maric, Irina; Desmond, Ronan; Holmes, Kevin L; Kuhns, Douglas B; Balabanian, Karl; Bachelerie, Françoise; Porcella, Stephen F; Malech, Harry L; Murphy, Philip M

    2015-02-12

    Chromothripsis is a catastrophic cellular event recently described in cancer in which chromosomes undergo massive deletion and rearrangement. Here, we report a case in which chromothripsis spontaneously cured a patient with WHIM syndrome, an autosomal dominant combined immunodeficiency disease caused by gain-of-function mutation of the chemokine receptor CXCR4. In this patient, deletion of the disease allele, CXCR4(R334X), as well as 163 other genes from one copy of chromosome 2 occurred in a hematopoietic stem cell (HSC) that repopulated the myeloid but not the lymphoid lineage. In competitive mouse bone marrow (BM) transplantation experiments, Cxcr4 haploinsufficiency was sufficient to confer a strong long-term engraftment advantage of donor BM over BM from either wild-type or WHIM syndrome model mice, suggesting a potential mechanism for the patient's cure. Our findings suggest that partial inactivation of CXCR4 may have general utility as a strategy to promote HSC engraftment in transplantation. PMID:25662009

  9. HBV cure: why, how, when?

    PubMed

    Levrero, Massimo; Testoni, Barbara; Zoulim, Fabien

    2016-06-01

    Current HBV treatments control replication and liver disease progression in the vast majority of treated patients. However, HBV patients often require lifelong therapies due to the persistence of transcriptionally active viral cccDNA mini-chromosome in the nucleus, which is not directly targeted by current antiviral therapies. A true complete cure of HBV would require clearance of intranuclear cccDNA from all infected hepatocytes. An intermediate but still relevant step forward that would allow treatment cessation would be reaching a functional cure, equivalent to resolved acute infection, with a durable HBsAg loss±anti-HBs seroconversion, undetectable serum DNA and persistence of cccDNA in a transcriptionally inactive status. Recent advances in technologies and pharmaceutical sciences, including the cloning of the mayor HBV receptor (i.e. the NTCP transporter) and the development in vitro HBV infection models, have heralded a new horizon of innovative antiviral and immune-therapeutic approaches. PMID:27447092

  10. Influence of light-curing protocols on polymerization shrinkage and shrinkage force of a dual-cured core build-up resin composite.

    PubMed

    Tauböck, Tobias T; Bortolotto, Tissiana; Buchalla, Wolfgang; Attin, Thomas; Krejci, Ivo

    2010-08-01

    This study investigated the influence of time delay and duration of photo-activation on linear polymerization shrinkage, shrinkage force, and hardening of a dual-cured core build-up resin composite. The test material (Rebilda DC) was light-cured for 20 or 60 s either early (2 min) or late (7 min) after the start of mixing. Non-irradiated self-cured specimens served as controls. Linear shrinkage and shrinkage force were measured for 60 min using custom-made devices. Knoop hardness was determined at the end of the observation period. Self-cured controls, showing a linear shrinkage similar to that of specimens early light-cured for 20 s generated the lowest shrinkage force and hardness. A shorter light exposure time (20 s vs. 60 s) reduced linear shrinkage, shrinkage force, and hardness when early light-curing was performed, but did not affect the three properties in specimens light-cured late after the start of mixing. Late photo-activation increased linear shrinkage, irrespective of irradiation time, and resulted in a higher shrinkage force and hardness for short light exposure time. A moderate correlation was found between the two shrinkage properties studied (r(2) = 0.65). In conclusion, improvements in shrinkage behavior of the tested core build-up material were associated with inferior hardening, making it important to adapt curing protocols to the clinical situation. PMID:20662918

  11. Cure shrinkage of thermoset composites

    SciTech Connect

    Russell, J.D. )

    1993-01-01

    The shrinkage of thermoset composites during cure was studied using a volumetric dilatometer. The material systems studied were AS4 carbon fiber/Hercules' 3501-6 epoxy, IM7 carbon fiber/Hercules 8551-7A toughened epoxy and IM7 carbon fiber/BASF's 5250-4 bismaleimide. Shrinkage of the samples due to both polymerization and thermal expansion effects was seen. The volume changes of the materials during cure were then compared to results from dynamic mechanical analysis (DMA) and dielectric cure monitoring. Maximums in volume corresponded to minimums in storage and loss modulus from DMA and maximums in the dielectric loss factor. Resin shrinkage during the 177 deg C (350 F) hold corresponded to the onset of polymerization seen by the rapid increase in the storage modulus and the decrease in the dielectric loss factor response due to reduced ion mobility. These results show that volumetric dilatometry can be an effective tool in the development of materials processing strategies and can be useful in studying residual stresses in composites. 9 refs.

  12. High Flow Addition Curing Polyimides

    NASA Technical Reports Server (NTRS)

    Chuang, Kathy C.; Vannucci, Raymond D.; Ansari, Irfan; Cerny, Lawrence L.; Scheiman, Daniel A.

    1994-01-01

    A new series of high flow PMR-type addition curing polyimides was developed, which employed the substitution of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (BTDB) for p-phenylenediamine (p -PDA) in a PMR-IL formulation. These thermoset polyimides, designated as 12F resins, were prepared from BTDB and the dimethyl ester of 4,4'- (hexafluo- roisopropylidene) -diphthalic acid (HFDE) with either nadic ester (NE) or p-aminostyrene (PAS) as the endcaps for addition curing. The 12F prepolymers displayed lower melting temperatures in DSC analysis, and higher melt flow in rheological studies than the cor- responding PMR-11 polyimides. Long-term isothermal aging studies showed that BTDB- based 12F resins exhibited comparable thermo-oxidative stability to P-PDA based PMR-11 polyimides. The noncoplanar 2- and 2'-disubstituted biphenyldiamine (BTDB) not only lowered the melt viscosities of 12F prepolymers, but also retained reasonable thermal sta- bility of the cured resins. The 12F polyimide resin with p-aminostyrene endcaps showed the best promise for long-term, high-temperature application at 343 C (650 F).

  13. Freud's psychoanalysis: a moral cure.

    PubMed

    Eriksson, Johan

    2014-08-01

    That psychoanalytical treatment in its classical Freudian sense is primarily a moral or ethical cure is not a very controversial claim. However, it is far from obvious how we are to understand precisely the moral character of psychoanalysis. It has frequently been proposed that this designation is valid because psychoanalysis strives neither to cure psychological symptoms pharmaceutically, nor to superficially modify the behaviour of the analysand, but to lead the analysand through an interpretive process during which he gradually gains knowledge of the unconscious motives that determine his behaviour, a process that might ideally liberate him to obtain, in relation to his inner desires, the status of a moral agent. There resides something appealing in these claims. But it is the author's belief that there is an even deeper moral dimension applying to psychoanalytical theory and praxis. Freudian psychoanalysis is a moral cure due to its way of thematizing psychological suffering as moral suffering. And this means that the moral subject - the being that can experience moral suffering - is not primarily something that the psychoanalytical treatment strives to realize, but rather the presupposition for the way in which psychoanalysis theorizes psychological problems as such. PMID:24720632

  14. Peptidomics as a tool for quality control in dry-cured ham processing.

    PubMed

    Gallego, Marta; Mora, Leticia; Toldrá, Fidel

    2016-09-16

    Spanish dry-cured ham is a high quality product whose economic value is mainly given by its curing time. An intense proteolysis takes place throughout the dry-cured processing, which results in the generation of a high amount of peptides and free amino acids responsible for the final quality of dry-cured hams. In this work, a peptidomics approach has been used to study the evolution of peptides throughout the ham dry-curing process, identifying and quantifying the generated peptides in order to define potential quality biomarkers. For this purpose, dry-cured ham extracts at different processing times (0, 2, 3.5, 5, 6.5 and 9months) were fractionated by size-exclusion chromatography and analysed by nanoliquid chromatography coupled to tandem mass spectrometry. Differences obtained in the relative quantification of peptides by using a label-free methodology were useful to establish differences between processing times, being peptides generated by the degradation of myosin light chain 1 protein mainly responsible for the observed differences during the last stages of curing. In particular, APAPAPAPPKEEKI and PAPAPAPAPAPAPAPPKE, exclusively identified at 9months of curing, would be potential markers to control the time of curing and thus the final quality of dry-cured hams. Biological significance A peptidomics approach has been used to study the evolution of peptides throughout the ham dry-curing process, identifying peptides APAPAPAPPKEEKI and PAPAPAPAPAPAPAPPKE, which were only detected at 9months of process. So, they would constitute good potential markers to control the time of processing and thus the final quality of dry-cured hams. PMID:26926439

  15. Measurement of the degree of cure in epoxies with ultrasonic velocity

    NASA Technical Reports Server (NTRS)

    Winfree, W. P.; Parker, F. R.

    1986-01-01

    The use of ultrasonic longitudinal velocity values to measure the degree of cure (defined for an epoxide system as the concentration of epoxide/amine bonds divided by the initial epoxide concentration) in epoxy resins is investigated. The experimental setup used to measure the changes in longitudinal velocity with time is described, together with the technique used to calculate the degree of cure from the acoustic data, using the principle of additive module. Measurements were done with diglycidyl ether of bisphenol A epoxy resin cured with an amine adduct agent. Good qualitative agreement was shown between the time dependence of the acoustically measured degree of cure and the predicted rate of reaction.

  16. Resolving Early Stages of Homogeneous Iron(III) Oxyhydroxide Formation from Iron(III) Nitrate Solutions at pH 3 Using Time-Resolved SAXS

    PubMed Central

    2015-01-01

    Small angle X-ray scattering (SAXS) measurements coupled to a stopped-flow device has permitted the observation of the kinetics of Fe(III) oxyhydroxide (FeOx) formation and transformation from around 1 s to 30 min after initiation under environmentally relevant conditions at pH 3. The Unified Model approach was used to determine the evolution of multiple key parameters (particle scattering mass, mean particle volume, particle concentration, particle dimensionality, and particle size) for two separate structural levels as a function of time, with the results obtained enabling clarification of the mechanisms underlying FeOx formation and transformation under these conditions. Colloidal primary particles (radius of gyration 2–10 nm) that were observable by SAXS formed within 1 s of stopping the flow and subsequently grew over several minutes, first by cluster–cluster addition and then by a monomer-addition mechanism. Aggregation of these primary particles via a secondary cluster–cluster addition mechanism simultaneously resulted in a distinct population of larger (25–40 nm radius of gyration) secondary particles. The primary particles evolved into compact spheroidal forms with fractally rough surfaces, while the secondary particles were relatively open mass fractal structures. Comparison of the observed rates of these processes with those predicted for Fe polymerization indicates that kinetics of primary particle formation were likely controlled initially by rates of exchange between water molecules coordinated with Fe and those in the bulk solution. These findings provide new insights into the mechanisms underlying FeOx formation and transformation, and the kinetics of these mechanisms, at pH 3. PMID:24601665

  17. Plant Habitat (PH)

    NASA Technical Reports Server (NTRS)

    Onate, Bryan

    2016-01-01

    The International Space Station (ISS) will soon have a platform for conducting fundamental research of Large Plants. Plant Habitat (PH) is designed to be a fully controllable environment for high-quality plant physiological research. PH will control light quality, level, and timing, temperature, CO2, relative humidity, and irrigation, while scrubbing ethylene. Additional capabilities include leaf temperature and root zone moisture and oxygen sensing. The light cap will have red (630 nm), blue (450 nm), green (525 nm), far red (730 nm) and broad spectrum white LEDs. There will be several internal cameras (visible and IR) to monitor and record plant growth and operations.

  18. Photo-Curing: UV Radiation curing of polymers

    NASA Technical Reports Server (NTRS)

    Inman, Christina A.

    2004-01-01

    The Polymers Branch of the Materials Division is dedicated to the development of high-performance for a variety of applications. Areas of significant interest include high- temperature polymers, low density, and high strength insulating materials, conductive polymers, and high density polymer electrolytes. This summer our group is working diligently on a photo-curing project. There is interest in the medical community feel the need for a new and improved balloon that will be used for angioplasty (a form of heart surgery). This product should maintain flexibility but add many other properties. Like possibly further processability and resistance to infection. Our group intends on coming up with this product by using photo-enolization (or simply, photo-curing) by Diels-Alder trapping. The main objective was to synthesize a series of new polymers by Diels-Alder cycloaddition of photoenols with more elastomeric properties. Our group was responsible for performing the proper photo-curing techniques of the polymers with diacrylates and bismaleimides, synthesizing novel monomers, and evaluating experimental results. We attempted to use a diacrylate to synthesize the polymer because of previous research done within the Polymers Branch here at NASA. Most acrylates are commercially available, have more elastometric properties than a typical rigid aromatic structure has and they contain ethylene oxides in the middle of their structure that create extensive flexibility. The problem we encountered with the acrylates is that they photo chemically and thermally self polymerize and create diradicals at low temperatures; these constraints caused a lot of unnecessary side reactions. We want to promote solely, diketone polymerization because this type of polymerization has the ability to cause very elastic polymers. We chose to direct our attention towards the usage of maleimides because they are known for eliminating these unnecessary side reactions.

  19. HIV cure research in South Africa: a preliminary exploration of stakeholder perspectives.

    PubMed

    Moodley, Keymanthri; Staunton, Ciara; de Roubaix, Malcolm; Cotton, Mark

    2016-01-01

    Innovative strategies for HIV cure are in development and research studies are being designed and planned globally. South Africa is no exception. However, little is known about stakeholders' knowledge, understanding and expectations of future cure research. This study aimed to obtain in-depth qualitative insights into stakeholder perspectives at this formative stage of HIV cure research. Fifteen stakeholders were interviewed in an HIV research clinic in the Western Cape, South Africa with their consent. Interviews were transcribed verbatim and analysed using thematic content analysis. Broad themes that emerged included the meaning of cure, awareness of HIV cure research, risks and benefits of such research. General awareness and understanding of HIV cure research was lower than expected. Some participants expressed a fatalistic attitude to HIV and described it as an "end-time illness" with no prospect of cure. In general, HIV cure research was regarded as risky - biologically psychologically and socially. If study designs were to include treatment interruption, participants would comply only if success was guaranteed. Given these perceptions of HIV cure research, significant challenges to consent processes and participant recruitment can be anticipated. Authentic community engagement and intensive educational interventions will be necessary prior to future cure research in South Africa. PMID:26565595

  20. Effects of Temperature and Humidity on Wilethane 44 Cure

    SciTech Connect

    John C. Weigle

    2006-10-01

    Wilethane 44 is a polyurethane adhesive developed by the Materials Team within ESA-MEE at Los Alamos National Laboratory as a replacement for Hexcel Corporation Urethane 7200. Urethane 7200 is used in numerous weapon systems, but it was withdrawn from the market in 1989. The weapons complex requires a replacement material for use in the W76-1 LEP and the W88, as well as for assembly of JTAs for other warheads. All polyurethane systems are susceptible to moisture reacting with unreacted isocyanate groups. This side reaction competes with the curing reaction and results in CO{sub 2} formation. Therefore, a polyurethane adhesive can exhibit foaming if appropriate environmental controls are not in place while it cures. A designed experiment has been conducted at TA-16-304 to determine the effects of ambient conditions on the properties of cured Wilethane 44. Temperature was varied from 15 C to 30 C and relative humidity from 15% to 40%. The density, hardness at 24 hours, and butt tensile strength on aluminum substrates were measured and fitted to quadratic equations over the experimental space. Additionally, the loss and storage moduli during cure were monitored as a function of cure temperature. These experiments provide a stronger basis for establishing appropriate environmental conditions and cure times when using Wilethane 44. The current guidelines are a working time of 90 minutes, a cure time of 18 hours, and a relative humidity of less than 25%, regardless of ambient temperature. Viscosity measurements revealed that the working time is a strong function of temperature and can be as long as 130 minutes at 15 C or as short as 90 minutes at 30 C. The experiments also showed that the gel time is much longer than originally thought, as long as 13 hours at 15 C. Consequently, it may be necessary to extend the required cure time at temperatures below 20 C. Allowable humidity varies as a function of temperature from 34% at 15 C to 15% at 30 C.

  1. Dynamic cure measurement of dental polymer composites using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Tomlins, Peter H.; Palin, Will M.; Shortall, Adrian C.

    2008-02-01

    Dental amalgam is being increasingly replaced by Light-activated resin-based dental composites. However, these materials are limited by inefficient setting reactions as a function of depth, constraining the maximum extent of cure and reducing biocompatibility. In this paper we demonstrate a novel metrological tool for dynamic monitoring of refractive index and thickness change through curing resins using spectral-domain optical coherence tomography. We present real-time measurements from pre- to post-cure of a series of un-filled bisphenol-A diglycidyl ether dimethacrylate (bisGMA) and triethylene glycol dimethacrylate (TEGDMA) resins with different inhibitor concentrations. Our results demonstrate that refractive index measurements are sensitive to the extent of cure of such resins and that the inhibitor concentration strongly affects the cure dynamics and final extent of cure.

  2. Electron beam curing of EPDM

    SciTech Connect

    Vroomen, G.L.M.; Visser, G.W.; Gehring, J.

    1991-11-01

    Normally EPDM rubbers are vulcanized by systems based on sulphur, resin or peroxide. The common feature of these systems is that they all require activator energy in the form of heat. The (extremely) high temperatures (approximately 180C) have the disadvantage that the final properties of the finished product may be affected in one way or another by a variety of uncontrolled side reactions which may occur. Radiation curing, on the other hand, is a process which differs from those mentioned above in that the final curing is carried out at about 20C under closely controlled conditions (such as radiation dose, penetration depth, etc.), and this form of curing ultimately results in a more well-defined end product. In the rubber industry, this technique is used by large rubber processors (for example, in roof sheeting and cable production). Its widespread use is, however, impeded by the high investment costs. One way of avoiding these high costs is to arrange for the products to be irradiated by contractors. The optimum radiation dose for EPDM is determined by the required pattern of properties. From this study it may be concluded that the network is primarily built up at a radiation dose of up to approximately 100 kGy. The degree to which it is built up depends partly on the coactivator used and the EPDM type used. In choosing the coactivator, allowance has to be made for its solubility in EPDM. The type of oil chosen and any stabilizer additions will affect the crosslinking efficiency. Contrary to studies published earlier, in this study it was found that when EDMA is used as a coactivator, no difference can be detected between a DCPD type (4%) and an ENB type (4%), provided both have an identical molecular weight distribution. Increasing the ENB content has less effect on the final crosslink density than using a type having a broader molecular weight distribution.

  3. Segmental dynamics of the cytoplasmic domain of erythrocyte band 3 determined by time-resolved fluorescence anisotropy: sensitivity to pH and ligand binding.

    PubMed

    Thevenin, B J; Periasamy, N; Shohet, S B; Verkman, A S

    1994-03-01

    Interactions between the erythrocyte membrane and its skeleton are mediated primarily by binding of cytoskeletal components to a conformationally sensitive structure, the cytoplasmic domain of band 3 (cdb3). To examine the nanosecond segmental motions of cdb3, band 3 was labeled selectively by fluorescein maleimide at Cys-201 near the proposed hinge in cdb3 about which pH-dependent conformational changes occur. Time-resolved anisotropy of labeled cdb3 in isolated form and in stripped erythrocyte membranes was measured by parallel-acquisition frequency-domain microfluorimetry. Samples had a single-component fluorescein lifetime of approximately 4 ns. Multifrequency phase and modulation data (5-200 MHz) fitted well to a segmental motion model containing two correlation times (tau 1c and tau 2c) and two limiting anisotropies (r1infinity and r2infinity). Measurements in protease-cleaved and denatured samples indicated that tau 1c (100-150 ps) corresponded to rapid rotation of bound fluorescein and tau 2c (2-5 ns) corresponded to segmental motion of cdb3. Both motions were hindered as quantified by nonzero r1infinity and r2infinity. The strong pH dependence of segmental motion correlated with that of cdb3 conformation measured by intrinsic tryptophan fluorescence. Significant changes in cdb3 segmental motion occurred upon interactions with the small ligands 2,3-bisphosphoglycerate and calcium and several glycolytic enzymes known to bind to the N terminus of band 3. These time-resolved fluorescence measurements of the nanosecond segmental dynamics of a labeled membrane protein provide evidence for the sensitivity of cdb3 conformation to ligand binding and suggest long-range structural communication through cdb3. PMID:8127875

  4. Overexpression of PhEXPA1 increases cell size, modifies cell wall polymer composition and affects the timing of axillary meristem development in Petunia hybrida.

    PubMed

    Zenoni, Sara; Fasoli, Marianna; Tornielli, Giovanni Battista; Dal Santo, Silvia; Sanson, Andrea; de Groot, Peter; Sordo, Sara; Citterio, Sandra; Monti, Francesca; Pezzotti, Mario

    2011-08-01

    • Expansins are cell wall proteins required for cell enlargement and cell wall loosening during many developmental processes. The involvement of the Petunia hybrida expansin A1 (PhEXPA1) gene in cell expansion, the control of organ size and cell wall polysaccharide composition was investigated by overexpressing PhEXPA1 in petunia plants. • PhEXPA1 promoter activity was evaluated using a promoter-GUS assay and the protein's subcellular localization was established by expressing a PhEXPA1-GFP fusion protein. PhEXPA1 was overexpressed in transgenic plants using the cauliflower mosaic virus (CaMV) 35S promoter. Fourier transform infrared (FTIR) and chemical analysis were used for the quantitative analysis of cell wall polymers. • The GUS and GFP assays demonstrated that PhEXPA1 is present in the cell walls of expanding tissues. The constitutive overexpression of PhEXPA1 significantly affected expansin activity and organ size, leading to changes in the architecture of petunia plants by initiating premature axillary meristem outgrowth. Moreover, a significant change in cell wall polymer composition in the petal limbs of transgenic plants was observed. • These results support a role for expansins in the determination of organ shape, in lateral branching, and in the variation of cell wall polymer composition, probably reflecting a complex role in cell wall metabolism. PMID:21534969

  5. Synthesis of Nanocrystalline SnOx (x = 1–2) Thin Film Using a Chemical Bath Deposition Method with Improved Deposition Time, Temperature and pH

    PubMed Central

    Ebrahimiasl, Saeideh; Yunus, Wan Md. Zin Wan; Kassim, Anuar; Zainal, Zulkarnain

    2011-01-01

    Nanocrystalline SnOx (x = 1–2) thin films were prepared on glass substrates by a simple chemical bath deposition method. Triethanolamine was used as complexing agent to decrease time and temperature of deposition and shift the pH of the solution to the noncorrosive region. The films were characterized for composition, surface morphology, structure and optical properties. X-ray diffraction analysis confirms that SnOx thin films consist of a polycrystalline structure with an average grain size of 36 nm. Atomic force microscopy studies show a uniform grain distribution without pinholes. The elemental composition was evaluated by energy dispersive X-ray spectroscopy. The average O/Sn atomic percentage ratio is 1.72. Band gap energy and optical transition were determined from optical absorbance data. The film was found to exhibit direct and indirect transitions in the visible spectrum with band gap values of about 3.9 and 3.7 eV, respectively. The optical transmittance in the visible region is 82%. The SnOx nanocrystals exhibit an ultraviolet emission band centered at 392 nm in the vicinity of the band edge, which is attributed to the well-known exciton transition in SnOx. Photosensitivity was detected in the positive region under illumination with white light. PMID:22163690

  6. Urine pH, container composition, and exposure time influence adsorptive loss of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid.

    PubMed

    Jamerson, Matthew H; McCue, Joseph J; Klette, Kevin L

    2005-10-01

    11-nor-delta9-Tetrahydrocannabinol-9-carboxylic acid (11-nor-delta9-THC-COOH) is the primary cannabinoid present in the urine of individuals who have used marijuana and is the target analyte identified at forensic urinalysis drug testing laboratories. The preparation, storage, transport, and processing of control materials for gas chromatography-mass spectrometric (GC-MS) analysis of human urine specimens is critical to accurate compound identification and quantification. Previous studies have suggested that adsorptive loss of 11-nor-delta9-THC-COOH is influenced by container composition and storage temperature. In this study, urine solutions of 11-nor-delta9-THC-COOH (7.5, 15, 60, and 500 ng/mL) at three physiologically-relevant pHs (4.6, 6.5, and 8.4) were prepared and subjected to storage and processing in containers of different compositions (polypropylene and borosilicate glass). Analyte identification and quantification were achieved using tetramethylammonium hydroxide/iodomethane-based derivatization followed by GC separation and electron-impact MS. These analyses demonstrate that adsorptive loss of 11-nor-delta9-THC-COOH is a phenomenon found in acidic urine solutions and is relatively absent in urine solutions that are near-neutral or basic. Furthermore, the data indicate that the adsorptive loss of 11-nor-delta9-THC-COOH is dependent on solution-container exposure time and is similar between containers of two distinct compositions. These results suggest that for optimal analytical control performance, solution pH and control processing times are critical elements. PMID:16419391

  7. ASRM test report: Autoclave cure process development

    NASA Technical Reports Server (NTRS)

    Nachbar, D. L.; Mitchell, Suzanne

    1992-01-01

    ASRM insulated segments will be autoclave cured following insulation pre-form installation and strip wind operations. Following competitive bidding, Aerojet ASRM Division (AAD) Purchase Order 100142 was awarded to American Fuel Cell and Coated Fabrics Company, Inc. (Amfuel), Magnolia, AR, for subcontracted insulation autoclave cure process development. Autoclave cure process development test requirements were included in Task 3 of TM05514, Manufacturing Process Development Specification for Integrated Insulation Characterization and Stripwind Process Development. The test objective was to establish autoclave cure process parameters for ASRM insulated segments. Six tasks were completed to: (1) evaluate cure parameters that control acceptable vulcanization of ASRM Kevlar-filled EPDM insulation material; (2) identify first and second order impact parameters on the autoclave cure process; and (3) evaluate insulation material flow-out characteristics to support pre-form configuration design.

  8. Performance of concrete under different curing conditions

    SciTech Connect

    Tan, K.; Gjorv, O.E.

    1996-03-01

    The effect of curing conditions on strength and permeability of concrete was studied. Test results showed that after 3 and 7 days moist curing only the concretes with w/c ratios equal to or less than 0.4 were accepted, while after 28 days of moist curing however, even the concrete with w/c of 0.6 could be accepted. Silica fume has a significant effect on the resistance to water penetration. For the concretes both with and without silica fume and with w/c + s of 0.5, the 28-day compressive strengths of 3 and 7 days moist curing were higher than those of 28 days moist curing, and the silica fume concrete seemed to be less sensitive to early drying. The curing temperatures did not affect the water penetration of concrete, but affected the chloride penetration and compressive strength of concrete significantly.

  9. Investigation of Film Curing by Dielectric Analysis.

    NASA Astrophysics Data System (ADS)

    Guma, Noemi Candelaria

    1995-01-01

    Dielectric analysis (DEA) relies on the response of molecules to a changing electric field. Permittivity (epsilon^') is a parameter obtained from DEA, which is proportional to the amount of molecular alignment (or motion). A DEA methodology was developed to evaluate and classify the degree of cure of films, and to demonstrate the mechanism of the curing phenomenon at a molecular level. The model material employed in the study was Eudragit^circler RS30D, an aqueous-based film forming polymeric material, containing 20% acetyl tributyl citrate as plasticizer. The data showed changes in the dielectric behavior of the polymer molecules in films that were subjected to accelerated stability or improper curing conditions. These dielectric changes were also manifested as changes in the permeability characteristics of the film, which ultimately influenced the final performance of the dosage form. By monitoring the dielectric behavior of the coating material during a curing cycle, a classification of three stages of curing was developed, namely undercured, optimally cured, and overcured. The changes in dielectric properties of the film reflected the changes in molecular structure, which correlated with changes in permeability and surface morphology. Based on the data, a mechanism of improper cure was proposed, which contends that the curing phenomenon is driven by two major forces, namely: the heterogenous loss and/or redistribution of plasticizer molecules during the curing process and the development of strain in the film structure during the coating process. A mathematical equation was derived to predict the epsilon^' of film-coated beads based on the epsilon^ ' data of free films cured under the same conditions. The model is based on the premise that "equal epsilon^' denotes equal mobility" for the same material, whether as free film or applied onto a substrate. The DEA technique developed and the proposed rationale of the curing phenomenon may be useful in optimizing the

  10. Interfacial Properties of Electron Beam Cured Composites

    SciTech Connect

    Eberle, C.C.

    1999-12-30

    The objectives of the CRADA are to: Confirm that fiber-resin adhesion is responsible for the observed poor shear properties; Determine the mechanism(s) responsible for poor adhesion between carbon fibers and epoxy resins after e-beam curing; Develop and evaluate resin systems and fiber treatments to improve the properties of e-beam cured, carbon-fiber-reinforced composites; and Develop refined methods for processing e-beam cured, carbon-fiber-reinforced composites.

  11. Modeling of Salt Diffusion in Raw Hide: An Optimization of the Curing Process

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The most common method of preserving raw hides is brine curing with sodium chloride. However, this process has three important disadvantages: first, the length of time that it takes, which is a minimum of 18 hours; second, the insufficient degree of curing reached in some hides due to an overload a...

  12. Modeling of salt diffusion in raw hide: an optimization of the curing process

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The most common method of preserving raw hides is brine curing with sodium chloride. However, this process has three important disadvantages: first, the length of time that it takes, which is a minimum of 18 hours; second, the insufficient degree of curing reached in some hides due to an overload a...

  13. Effect of time on the interfacial and foaming properties of beta-lactoglobulin/acacia gum electrostatic complexes and coacervates at pH 4.2.

    PubMed

    Schmitt, Christophe; da Silva, Tânia Palma; Bovay, Claudine; Rami-Shojaei, Sabrina; Frossard, Philippe; Kolodziejczyk, Eric; Leser, Martin E

    2005-08-16

    The electrostatic complexation between beta-lactoglobulin and acacia gum was investigated at pH 4.2 and 25 degrees C. The binding isotherm revealed a spontaneous exothermic reaction, leading to a DeltaHobs = -2108 kJ mol(-1) and a saturation protein to polysaccharide weight mixing ratio of 2:1. Soluble electrostatic complexes formed in these conditions were characterized by a hydrodynamic diameter of 119 +/- 0.6 nm and a polydispersity index of 0.097. The effect of time on the interfacial and foaming properties of these soluble complexes was investigated at a concentration of 0.1 wt % at two different times after mixing (4 min, referred as t approximately 0 h and t = 24 h). At t approximately 0 h, the mixture is mainly made of aggregating soluble electrostatic complexes, whereas after 24 h these complexes have already insolubilize to form liquid coacervates. The surface elasticity, viscosity and phase angle obtained at low frequency (0.01 Hz) using oscillating bubble tensiometry revealed higher fluidity and less rigidity in the film formed at t approximately 0 h. This observation was confirmed by diminishing bubble experiments coupled with microscopy of the thin film. It was thicker, more homogeneous and contained more water at t approximately 0 h as compared to t = 24 h (thinner film, less water). This led to very different gas permeability's of Kt approximately 0 h = 0.021 cm s(-1) and Kt=24 h) = 0.449 cm s(-1), respectively. Aqueous foams produced with the beta-lactoglobulin/acacia gum electrostatic complexes or coacervates exhibited very different stability. The former (t approximately 0 h) had a stable volume, combining low drainage rate and mainly air bubble disproportionation as the destabilization mechanism. By contrast, using coacervates aged for 24 h, the foam was significantly less stable, combining fast liquid drainage and air bubble destabilization though fast gas diffusion followed by film rupture and bubble coalescence. The strong effect of time on

  14. Raman spectroscopic studies of the cure of dicyclopentadiene (DCPD)

    NASA Astrophysics Data System (ADS)

    Barnes, S. E.; Brown, E. C.; Corrigan, N.; Coates, P. D.; Harkin-Jones, E.; Edwards, H. G. M.

    2005-10-01

    The cure of polydicyclopentadiene conducted by ring-opening metathesis polymerisation in the presence of a Grubbs catalyst was studied using non-invasive Raman spectroscopy. The spectra of the monomer precursor and polymerised product were fully characterised and all stages of polymerisation monitored. Because of the monomer's high reactivity, the cure process is adaptable to reaction injection moulding and reactive rotational moulding. The viscosity of the dicyclopentadiene undergoes a rapid change at the beginning of the polymerisation process and it is critical that the induction time of the viscosity increase is determined and controlled for successful manufacturing. The results from this work show non-invasive Raman spectroscopic monitoring to be an effective method for monitoring the degree of cure, paving the way for possible implementation of the technique as a method of real-time analysis for control and optimisation during reactive processing. Agreement is shown between Raman measurements and ultrasonic time of flight data acquired during the initial induction period of the curing process.

  15. [Nonnius and the Spa cure].

    PubMed

    Lecomte, J; Lemli, J; Marganne, M H; Melard, M

    1996-01-01

    The 12th of July 1635, Jan van Beverwyck wrote a letter from Dordrecht to his esteemed friend Luis Nunez, in Antwerp. He asked him for indications about the cure of kidney stones of which he was suffering. He had just passed two calculi very painfully. Nunez answered on July 31. His letter summarized his own experience with this disease. In such cases, temperate diuretics and emollients are well indicated: ingestion of light decoctions of Malva and Viola, Caerefolium and Parieteria as well as Marshmallow syrup. No purge and no 'chemicals'. However, the best remedy was drinking Spa water. Usually the best way to absorb it is to come to the springs, in the Ardennes, part of the independent Principality of Liège. However, considering the horrors of the war (the Thirty Years War) endangering the country, van Beverwyck would be wise to drink imported water during 40 or 50 days, while staying home quietly, in Dordrecht. The letter points out the importance of provoked diuresis in the treatment of kidney stones. On the other hand the letter is an illustration of the continuing contacts between the United Provinces and the Spanish territories and of the commercial traffic between Antwerp, Dordrecht and Spa. The exported water was bottled from many 'pouhons'. It was acid, ferruginous, sulfurous and saturated with carbon dioxide; no pathogen germs, at least at the spring. Nunez quoted the large number of his patients cured with Spa water in Antwerp. This is an illustration of its commercial expansion even during this critical period. PMID:8848877

  16. Hepatitis C, stigma and cure

    PubMed Central

    Marinho, Rui Tato; Barreira, David Pires

    2013-01-01

    The infection with hepatitis C virus (HCV) is one of the most important global chronic viral infections worldwide. It is estimated to affect around 3% of the world population, about 170-200 million people. Great part of the infections are asymptomatic, the patient can be a chronic carrier for decades without knowing it. The most severe consequences of the chronic infection are liver cirrhosis and hepatocellular carcinoma, which appears in 20%-40% of the patients, leading to hepatic failure and death. The HCV was discovered 25 years ago in 1989, is a RNA virus and classified by the World Health Organization as an oncogenic one. Hepatocellular carcinoma is one of the most important cancers, the fifth worldwide in terms of mortality. It has been increasing in the Ocidental world, mainly due to chronic hepatitis C. Hepatitis C is not only a liver disease and a cause of cirrhosis, but also a mental, psychological, familiar, and social disease. The stigma that the infected person sometimes carries is tremendous having multiple consequences. The main cause is lack of adequate information, even in the health professionals setting. But, besides the “drama” of being infected, health professionals, family, society and the infected patients, must be aware of the chance of real cure and total and definitive elimination of the virus. The treatment for hepatitis C has begun in the last 80´s with a percentage of cure of 6%. Step by step the efficacy of the therapy for hepatitis C is rapidly increasing and nowadays with the very new medications, the so called Direct Antiviral Agents-DAAs of new generation, is around 80%-90%. PMID:24187444

  17. Changes on degree of conversion of dual-cure luting light-cured with blue LED

    NASA Astrophysics Data System (ADS)

    Bandéca, M. C.; El-Mowafy, O.; Saade, E. G.; Rastelli, A. N. S.; Bagnato, V. S.; Porto-Neto, S. T.

    2009-05-01

    The indirect adhesive procedures constitute recently a substantial portion of contemporary esthetic restorative treatments. The resin cements have been used to bond tooth substrate and restorative materials. Due to recently introduction of the self-bonding resin luting cement based on a new monomer, filler and initiation technology has become important to study the degree of conversion of these new materials. In the present work the polymerization reaction and the filler content of dual-cured dental resin cements were studied by means of infra-red spectroscopy (FT-IR) and thermogravimetry (TG). Twenty specimens were made in a metallic mold (8 mm diameter × 1 mm thick) from each of 2 cements, Panavia® F2.0 (Kuraray) and RelyX™ Unicem Applicap (3M/ESPE). Each specimen was cured with blue LED with power density of 500 mW/cm2 for 30 s. Immediately after curing, 24 and 48 h, and 7 days DC was determined. For each time interval 5 specimens were pulverized, pressed with KBr and analyzed with FT-IR. The TG measurements were performed in Netzsch TG 209 under oxygen atmosphere and heating rate of 10°C/min from 25 to 700°C. A two-way ANOVA showed DC (%) mean values statistically significance differences between two cements ( p < 0.05). The Tukey’s test showed no significant difference only for the 24 and 48 h after light irradiation for both resin cements ( p > 0.05). The Relx-Y™ Unicem mean values were significantly higher than Panavia® F 2.0. The degree of conversion means values increasing with the storage time and the filler content showed similar for both resin cements.

  18. Towards the real-time monitoring of glucose in tear fluid: holographic glucose sensors with reduced interference from lactate and pH.

    PubMed

    Yang, Xiaoping; Pan, Xiaohan; Blyth, Jeff; Lowe, Christopher R

    2008-01-18

    Glucose-selective holographic sensors were fabricated from unique tetrahedral 2-acrylamidophenylboronic acid (2-APB) incorporated with co-monomers poly(ethylene glycol) acrylate (PEG), (3-acrylamidopropyl)trimethylammonium chloride (ATMA) and [2-(acryloyloxy)ethyl]-trimethylammonium chloride (AETA) into thin hydrogel films which were transformed into volume holograms using a diffusion method coupled with holographic recording using a frequency-doubled Nd:YAG laser (532 nm). The results showed that the 2-APB-based holographic sensors contracted upon addition of glucose due to the formation of a 2:1 complex between the tetrahedral 2-APB and glucose. More significantly, the 2-APB-based holographic sensors had greatly reduced lactate dependence and a hugely reduced pH effect over the physiological range of pH. These features are vital for development of contact lens-based glucose sensor, where the pH variability is greater (pH 5.8-7.8) and the lactate concentration is substantially higher than in blood. Furthermore, the 2-APB-based holographic sensors also displayed fast response to glucose. The successful union of holograms and the tetrahedral 2-APB receptor for glucose detection in artificial tear fluid is also demonstrated. This new type of holographic sensors responding to glucose with features of minor pH effect and negligible interference from lactate is applicable to the detection of glucose concentrations in tear fluid for the management of diabetes. PMID:18060763

  19. Colour and organic removal of biologically treated coffee curing wastewater by electrochemical oxidation method.

    PubMed

    Bejankiwar, Rajesh S; Lokesh, K S; Gowda, T P Halappa

    2003-05-01

    The treatment of biologically treated wastewater of coffee-curing industry by the electrochemical oxidation using steel anode was investigated. Bench-scale experiments were conducted for activated sludge process on raw wastewater and the treated effluents were further treated by electrochemical oxidation method for its colour and organic content removal. The efficiency of the process was determined in terms of removal percentage of COD, BOD and colour during the course of reaction. Several operating parameters like time, pH and current density were examined to ascertain their effects on the treatment efficiency. Steel anode was found to be effective for the COD and colour removal with anode efficiency of 0.118 kgCOD x h(-1) x A(-1) x m(-2) and energy consumption 20.61 kWh x kg(-1) of COD at pH 9. The decrease in pH from 9 to 3 found to increase the anode efficiency from 0.118 kgCOD x h(-1) x A(-1) x m(-2) to 0.144 kWh x kg(-1) of COD while decrease the energy consumption from 20.61 kWh x kg(-1) of COD to 12.86 kWh x kg(-1) of COD. The pH of 5 was considered an ideal from the present treatment process as it avoids the addition of chemicals for neutralization of treated effluents and also economical with respect to energy consumption. An empirical relation developed for relationship between applied current density and COD removal efficiency showed strong predictive capability with coefficient of determination of 96.5%. PMID:12938980

  20. A new hypothesis on HIV cure

    PubMed Central

    Hladik, Florian

    2015-01-01

    In this opinion article, I provide the rationale for my hypothesis that nucleoside reverse transcriptase inhibitors (NRTIs) may prevent human immunodeficiency virus (HIV) cure by promoting the survival of cells with integrated provirus. If correct, we may be closer to a cure than we realize. PMID:26380071

  1. Ultrasonic mixing of epoxy curing agents

    NASA Technical Reports Server (NTRS)

    Hodges, W. T.; St.clair, T. L.

    1983-01-01

    A new technique for mixing solid curing agents into liquid epoxy resins using ultrasonic energy was developed. This procedure allows standard curing agents such as 4,4 prime-diaminodiphenyl sulfone (4,4 prime-DDS) and its 3,3 prime-isomer, (3,3 prime-DDS) to be mixed without prior melting of the curing agent. It also allows curing agents such as 4,4 prime-diaminodiphenyl sulfone (4,4 prime-DDS) and its 3,3 prime-isomer, (3,3 prime-DDS) to be mixed without prior melting of the curing agent. It also allows curing agents with very high melt temperatures such as 4,4 prime-diaminobenzophenone (4,4 prime-DABP) (242 C) to be mixed without premature curing. Four aromatic diamines were ultrasonically blended into MY-720 epoxy resin. These were 4,4 prime-DDS; 3,3 prime-DDA; 4,4 prime-DABP and 3,3 prime-DABP. Unfilled moldings were cast and cured for each system and their physical and mechanical properties compared.

  2. Animal Models for HIV Cure Research

    PubMed Central

    Policicchio, Benjamin B.; Pandrea, Ivona; Apetrei, Cristian

    2016-01-01

    The HIV-1/AIDS pandemic continues to spread unabated worldwide, and no vaccine exists within our grasp. Effective antiretroviral therapy (ART) has been developed, but ART cannot clear the virus from the infected patient. A cure for HIV-1 is badly needed to stop both the spread of the virus in human populations and disease progression in infected individuals. A safe and effective cure strategy for human immunodeficiency virus (HIV) infection will require multiple tools, and appropriate animal models are tools that are central to cure research. An ideal animal model should recapitulate the essential aspects of HIV pathogenesis and associated immune responses, while permitting invasive studies, thus allowing a thorough evaluation of strategies aimed at reducing the size of the reservoir (functional cure) or eliminating the reservoir altogether (sterilizing cure). Since there is no perfect animal model for cure research, multiple models have been tailored and tested to address specific quintessential questions of virus persistence and eradication. The development of new non-human primate and mouse models, along with a certain interest in the feline model, has the potential to fuel cure research. In this review, we highlight the major animal models currently utilized for cure research and the contributions of each model to this goal. PMID:26858716

  3. Framing expectations in early HIV cure research.

    PubMed

    Dubé, Karine; Henderson, Gail E; Margolis, David M

    2014-10-01

    Language used to describe clinical research represents a powerful opportunity to educate volunteers. In the case of HIV cure research there is an emerging need to manage expectations by using the term 'experiment'. Cure experiments are proof-of-concept studies designed to evaluate novel paradigms to reduce persistent HIV-1 reservoirs, without any expectation of medical benefit. PMID:25280965

  4. Animal Models for HIV Cure Research.

    PubMed

    Policicchio, Benjamin B; Pandrea, Ivona; Apetrei, Cristian

    2016-01-01

    The HIV-1/AIDS pandemic continues to spread unabated worldwide, and no vaccine exists within our grasp. Effective antiretroviral therapy (ART) has been developed, but ART cannot clear the virus from the infected patient. A cure for HIV-1 is badly needed to stop both the spread of the virus in human populations and disease progression in infected individuals. A safe and effective cure strategy for human immunodeficiency virus (HIV) infection will require multiple tools, and appropriate animal models are tools that are central to cure research. An ideal animal model should recapitulate the essential aspects of HIV pathogenesis and associated immune responses, while permitting invasive studies, thus allowing a thorough evaluation of strategies aimed at reducing the size of the reservoir (functional cure) or eliminating the reservoir altogether (sterilizing cure). Since there is no perfect animal model for cure research, multiple models have been tailored and tested to address specific quintessential questions of virus persistence and eradication. The development of new non-human primate and mouse models, along with a certain interest in the feline model, has the potential to fuel cure research. In this review, we highlight the major animal models currently utilized for cure research and the contributions of each model to this goal. PMID:26858716

  5. Cure Chemistry of Phenylethynyl Terminated Oligomers

    NASA Technical Reports Server (NTRS)

    Wood, Karen H.; Orwoll, Robert A.; Young, Philip R.; Jensen, Brian J.; McNair, Harold M.

    1997-01-01

    The ability to process high performance polymers into quality, void-free composites has been significantly advanced using oligomers terminated with reactive groups which cure or crosslink at elevated temperature without the evolution of volatile byproducts. Several matrix resin systems of considerable interest to the aerospace community utilize phenylethynyl-terminated imide (PETI) technology to achieve this advantage. The present paper addresses the cure chemistry of PETI oligomers. The thermal cure of a low molecular weight model compound was studied using a variety of analytical techniques including differential scanning calorimetry, Fourier transform infrared spectroscopy, and liquid chromatography-mass spectroscopy. The studies indicate an extremely complex cure process. Many stable products were isolated and this paper reports current work on identification of those products. The intent of this research is to provide fundamental insight into the molecular structure of the cured PETI engineering materials so that performance and durability can be more fully assessed.

  6. Biodegradable Epoxy Networks Cured with Polypeptides

    NASA Astrophysics Data System (ADS)

    Nakamura, Shigeo; Kramer, Edward J.

    2006-03-01

    Epoxy resins are used widely for adhesives as well as coatings. However, once cured they are usually highly cross-linked and are not biodegradable. To obtain potentially biodegradable polypeptides that can cure with epoxy resins and achieve as good properties as the conventional phenol novolac hardeners, poly(succinimide-co-tyrosine) was synthesized by thermal polycondensation of L-aspartic acid and L-tyrosine with phosphoric acid under reduced pressure. The tyrosine/succinimide ratio in the polypeptide was always lower than the tyrosine/(aspartic acid) feed ratio and was influenced by the synthesis conditions. Poly(succinimide-tyrosine- phenylalanine) was also synthesized from L-aspartic acid, L- tyrosine and L-phenylalanine. The thermal and mechanical properties of epoxy resins cured with these polypeptides are comparable to those of similar resins cured with conventional hardeners. In addition, enzymatic degradability tests showed that Chymotrypsin or Subtilisin A could cleave cured films in an alkaline borate buffer.

  7. Knowledge based control for microwave curing of polymer composite materials

    SciTech Connect

    Hawkins, R.; Sticklen, J.; Hawley, M.C.

    1996-12-31

    Traditionally, the majority of thermoset composite materials have been autoclave cured. Some alternatives to curing in an autoclave include E-Beam and microwave curing. In the Microwave Research Group at MSU, microwave curing technology is being pursued for the purpose of achieving higher throughput, lower cost and higher energy efficiency, relative to autoclave curing.

  8. 7 CFR 29.2519 - Fire-cured.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION Standards Official Standard Grades for Kentucky and Tennessee Fire-Cured and Foreign-Grown Fire-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2519 Fire-cured. Tobacco cured under... 7 Agriculture 2 2010-01-01 2010-01-01 false Fire-cured. 29.2519 Section 29.2519...

  9. 7 CFR 29.2519 - Fire-cured.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... INSPECTION Standards Official Standard Grades for Kentucky and Tennessee Fire-Cured and Foreign-Grown Fire-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2519 Fire-cured. Tobacco cured under... 7 Agriculture 2 2012-01-01 2012-01-01 false Fire-cured. 29.2519 Section 29.2519...

  10. 7 CFR 29.2519 - Fire-cured.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... INSPECTION Standards Official Standard Grades for Kentucky and Tennessee Fire-Cured and Foreign-Grown Fire-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2519 Fire-cured. Tobacco cured under... 7 Agriculture 2 2011-01-01 2011-01-01 false Fire-cured. 29.2519 Section 29.2519...