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Sample records for bonding agents role

  1. Dentin-bonding agents

    Directory of Open Access Journals (Sweden)

    João Carlos Gomes

    2008-01-01

    Full Text Available New dental restorative materials have been developed to meet not only the functional demands, but esthetics as well, and in the last few years an enormous range of new materials has appeared for use in dentistry. Among them, several adhesive systems, and different operative techniques for each group materials. Therefore, is indispensable for the professional to know about the properties, characteristics, and association of these materials with the dental structures, in order to select and use them correctly. Should conventional self-etching adhesive systems be used? This question encouraged this literature review to be conducted, with the aim of comparing the conventional adhesive systems with the self-etching systems and to look for scientific data that would help professionals to choose which adhesive system to use. When compared to conventional systems, it was noted that the self-etching systems show less sensitivity to technique, especially as regards errors the operator could commit. The self-etching systems, particularly the 2-step type, have shown equivalent values of bond strength, marginal microleakage and performance, therefore, will be an option for direct composite resin restorations in posterior teeth.

  2. Amalgam shear bond strength to dentin using different bonding agents.

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    Vargas, M A; Denehy, G E; Ratananakin, T

    1994-01-01

    This study evaluated the shear bond strength of amalgam to dentin using five different bonding agents: Amalgambond Plus, Optibond, Imperva Dual, All-Bond 2, and Clearfil Liner Bond. Flat dentin surfaces obtained by grinding the occlusal portion of 50 human third molars were used for this study. To contain the amalgam on the tooth surface, cylindrical plastic molds were placed on the dentin and secured with sticky wax. The bonding agents were then applied according to the manufacturers' instructions or light activated and Tytin amalgam was condensed into the plastic molds. The samples were thermocycled and shear bond strengths were determined using an Instron Universal Testing Machine. Analysis by one-way ANOVA indicated significant difference between the five groups (P < 0.05). The bond strength of amalgam to dentin was significantly higher with Amalgambond Plus using the High-Performance Additive than with the other four bonding agents.

  3. Enamel Bond Strength of New Universal Adhesive Bonding Agents.

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    McLean, D E; Meyers, E J; Guillory, V L; Vandewalle, K S

    2015-01-01

    Universal bonding agents have been introduced for use as self-etch or etch-and-rinse adhesives depending on the dental substrate and clinician's preference. The purpose of this study was to evaluate the shear bond strength (SBS) of composite to enamel using universal adhesives compared to a self-etch adhesive when applied in self-etch and etch-and-rinse modes over time. Extracted human third molars were used to create 120 enamel specimens. The specimens were ground flat and randomly divided into three groups: two universal adhesives and one self-etch adhesive. Each group was then subdivided, with half the specimens bonded in self-etch mode and half in etch-and-rinse mode. The adhesives were applied as per manufacturers' instructions, and composite was bonded using a standardized mold and cured incrementally. The groups were further divided into two subgroups with 10 specimens each. One subgroup was stored for 24 hours and the second for six months in 37°C distilled water and tested in shear. Failure mode was also determined for each specimen. A three-way analysis of variance (ANOVA) found a significant difference between groups based on bonding agent (p0.05). Clearfil SE in etch-and-rinse and self-etch modes had more mixed fractures than either universal adhesive in either mode. Etching enamel significantly increased the SBS of composite to enamel. Clearfil SE had significantly greater bond strength to enamel than either universal adhesive, which were not significantly different from each other.

  4. Hybrid layer difference between sixth and seventh generation bonding agent

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    Grace Syavira Suryabrata

    2006-03-01

    Full Text Available Since etching is completed at the same stage as priming and bonding, when applying the sixth and seventh generation bonding, the exposed smear layers are constantly surrounded by primer and bonding and cannot collapse. The smear layer and the depth of penetration of resin bonding in dentinal tubules are completely integrated into hybrid layer. The purpose of this laboratory research was to study the penetration depth of two self etching adhesive. Fourteen samples of human extracted teeth were divided into two groups. Each groups consisted of seven samples, each of them was treated with sixth generation bonding agent and the other was treated with seventh generation bonding agent. The results disclosed that the penetration into dentinal tubules of seventh generation bonding agent was deeper than sixth generation bonding agent. Conclusion: bond strength will improve due to the increasing of penetration depth of resin bonding in dentinal tubules.

  5. Comparative evaluation of shear bond strength of metallic brackets bonded with two different bonding agents under dry conditions and with saliva contamination

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    Mashallah Khanehmasjedi

    2017-02-01

    Conclusion: Application of Single Bond and Assure bonding agents resulted in adequate bond strength of brackets to tooth structures. Contamination with saliva significantly decreased the bond strength of Assure bonding agent compared with dry conditions.

  6. Evaluation of a New Nano-filled Bonding Agent for Bonding Orthodontic Brackets as Compared to a Conventional Bonding Agent: An in vitro Study

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    Sandesh S Pai

    2012-01-01

    Conclusion: Although both bonding agents provide clinically acceptable levels of bond strength, the technique to bond the nano-filled Prime and Bond NT is more cumbersome as compared to the Transbond XT material, which makes the latter a more popular choice in the clinical set up. If the application procedures for the Prime and Bond NT can be simplified then it could be a convenient option in the orthodontic practice.

  7. In vitro Comparative Evaluation of Tensile Bond Strength of 6(th), 7(th) and 8(th) Generation Dentin Bonding Agents.

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    Kamble, Suresh S; Kandasamy, Baburajan; Thillaigovindan, Ranjani; Goyal, Nitin Kumar; Talukdar, Pratim; Seal, Mukut

    2015-05-01

    Newer dentin bonding agents were developed to improve the quality of composite restoration and to reduce time consumption in its application. The aim of the present study was to evaluate tensile bond strength of 6(th), 7(th) and 8(th) generation bonding agents by in vitro method. Selected 60 permanent teeth were assigned into 20 in each group (Group I: 6(th) generation bonding agent-Adper SE plus 3M ESPE, Group II: 7(th) generation bonding agent-G-Bond GC Corp Japan and Group III: 8(th) generation dentin adhesives-FuturaBond, DC, Voco, Germany). With high-speed diamond disc, coronal dentin was exposed, and selected dentin bonding agents were applied, followed by composite restoration. All samples were saved in saline for 24 h and tensile bond strength testing was done using a universal testing machine. The obtained data were tabulated and statistically analyzed using ANOVA test. The tensile bond strength readings for 6(th) generation bonding agent was 32.2465, for 7(th) generation was 31.6734, and for 8(th)-generation dentine bonding agent was 34.74431. The highest tensile bond strength was seen in 8(th) generation bonding agent compared to 6(th) and 7(th) generation bonding agents. From the present study it can be conclude that 8(th) generation dentine adhesive (Futura DC, Voco, Germany) resulted in highest tensile bond strength compared to 6(th) (Adper SE plus, 3M ESPE) and 7(th) generation (G-Bond) dentin bonding agents.

  8. Relationship between thin-film bond strength as measured by a scratch test, and indentation hardness for bonding agents.

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    Kusakabe, Shusuke; Rawls, H Ralph; Hotta, Masato

    2016-03-01

    To evaluate thin-film bond strength between a bonding agent and human dentin, using a scratch test, and the characteristics and accuracy of measurement. One-step bonding agents (BeautiBond; Bond Force; Adper Easy Bond; Clearfil tri-S Bond) and two-step bonding agents (Cleafil SE Bond; FL-Bond II) were investigated in this study. Flat dentin surfaces were prepared for extracted human molars. The dentin surfaces were ground and bonding agents were applied and light cured. The thin-film bond strength test of the specimens was evaluated by the critical load at which the coated bonding agent failed and dentin appeared. The scratch mark sections were then observed under a scanning electron microscope. Indentation hardness was evaluated by the variation in depth under an applied load of 10gf. Data were compared by one-way ANOVA with the Scheffé's post hoc multiple comparison test (pstrength and indentation hardness were analyzed using analysis of correlation and covariance. The thin-film bond strength of two-step bonding agents were found to be significantly higher than that of one-step bonding agents with small standard deviations. Scratch marks consistently showed adhesive failure in the vicinity of the bonding agent/dentin interface. The indentation hardness showed a trend that two-step bonding agents have greater hardness than one-step bonding agents. A moderately significant correlation (r(2)=0.31) was found between thin-film bond strength and indentation hardness. Thin-film bond strength test is a valid and reliable means of evaluating bond strength in the vicinity of the adhesive interface and is more accurate than other methods currently in use. Further, the thin-film bond strength is influenced by the hardness of the cued bonding agent. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  9. Evaluation of a New Nano-filled Bonding Agent for Bonding Orthodontic Brackets as Compared to a Conventional Bonding Agent: An in vitro Study

    OpenAIRE

    Sandesh S Pai; Amrita Nagendra; Vinaya S Pai; K Neelima; A E Vishwanath; P Vinod; Sharanya Ajit Kumar; Roopa R Tubaki

    2012-01-01

    Introduction: Recent advances in the field of material sciences have opened up a new horizon of options for bonding agents that can be used efficiently in orthodontics. The purpose of this study was evaluate and compare the shear bond strength (SBS) of the traditionally used Transbond XT and a newer nano-filled material Prime and Bond NT. Materials and methods: Sixty freshly extracted maxillary first premolars were stored in 0.1% (weight/volume) thymol. These were divided into two Groups. ...

  10. Effect of mode of polymerization of bonding agent on shear bond strength of autocured resin composite luting cements.

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    Dong, Cecilia C S; McComb, Dorothy; Anderson, James D; Tam, Laura E

    2003-04-01

    There have been anecdotal reports of low bond strength with autocured resin composite materials, particularly when light-cured bonding agents that combine primer and adhesive in a 1-bottle preparation are used. The objective of this study was to determine if the mode of polymerization of the bonding agent influences the strength of the attachment of autocured resin composite luting cements to dentin. The shear bond strength of 2 resin luting cements, Calibra and RelyX ARC, polymerized by autocuring, in combination with 4 different bonding agents, Scotchbond Multipurpose Plus, Prime & Bond NT, IntegraBond and Single Bond, polymerized to bovine dentin by light-curing, autocuring or dual-curing, was determined. The pH of each bonding agent and its components was measured. Two-way analysis of variance was used to test the effect of cement and adhesive on shear bond strength. For each bonding agent, the adhesive variable combined the factors product brand and mode of polymerization. With significant interaction among the above variables, the least square means of the 16 combinations of resin cement and adhesive were compared. There was no consistent relationship between shear bond strength and mode of polymerization of the bonding agent. Significant differences in bond strength were specific to the proprietary brand of bonding agent. The pH of the bonding agent depends on the manufacturer's formulation, and low pH may contribute to low bond strength. The low in vitro bond strength occurring with some combinations of bonding agent and resin cement could be clinically significant.

  11. Comparative evaluation of shear bond strength of metallic brackets bonded with two different bonding agents under dry conditions and with saliva contamination.

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    Khanehmasjedi, Mashallah; Naseri, Mohammad Ali; Khanehmasjedi, Samaneh; Basir, Leila

    2017-02-01

    This study compared the shear bond strength of metallic brackets bonded with Single Bond and Assure bonding agents under dry and saliva-contamination conditions. Sixty sound premolar teeth were selected, and stainless-steel brackets were bonded on enamel surfaces with Single Bond and Assure bonding agents under dry condition or with saliva contamination. Shear bond strength values of brackets were measured in a universal testing machine. The adhesive remnant index scores were determined after debonding of the brackets under a stereomicroscope. One-way analysis of variance (ANOVA) was used to analyze bond strength. Two-by-two comparisons were made with post hoc Tukey tests (pbrackets to tooth structure were 9.29±8.56 MPa and 21.25±8.93 MPa with the use of Assure resin bonding agent under saliva-contamination and dry conditions, respectively. These values were 10.13±6.69 MPa and 14.09±6.6 MPa, respectively, under the same conditions with the use of Single Bond adhesive. Contamination with saliva resulted in a significant decrease in the bond strength of brackets to tooth structure with the application of Assure adhesive resin (pbrackets to tooth structures. Contamination with saliva significantly decreased the bond strength of Assure bonding agent compared with dry conditions. Copyright © 2016. Published by Elsevier Taiwan LLC.

  12. Effects of recycling and bonding agent application on bond strength of stainless steel orthodontic brackets.

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    Bahnasi, Faisal I; Abd-Rahman, Aida Na; Abu-Hassan, Mohame I

    2013-10-01

    1) to assess different methods of recycling orthodontic brackets, 2) to evaluate Shear Bond Strength (SBS) of (a) new, (b) recycled and (c) repeated recycled stainless steel brackets (i) with and (ii) without bracket base primer. A total of 180 extracted human premolar teeth and 180 premolar stainless steel brackets were used. One hundred teeth and 100 brackets were divided into five groups of 20-teeth each. Four methods of recycling orthodontic brackets were used in each of the first four groups while the last one (group V) was used as the control. Groups (I-V) were subjected to shear force within half an hour until the brackets debond. SBS was measured and the method showing the highest SBS was selected. A New group (VI) was recycled twice with the selected method. Six subgroups (1-6) were established; the primer was applied for three sub-groups, and the composite was applied for all brackets. Brackets were subjected to the same shear force, and SBS was measured for all sub-groups. There was a significant difference between the mean SBS of the sandblasting method and the means of SBS of each of the other three methods. There was however, no significant difference between the mean SBS of the new bracket and the mean SBS of recycled bracket using sandblasting. The mean SBS of all sub-groups were more than that recommended by Reynolds (17) in 1975. Brackets with primer showed slightly higher SBS compared to those of brackets without bonding agent. To decrease cost, sandblasted recycled orthodontic brackets can be used as an alternative to new brackets. It is recommended to apply a bonding agent on the bracket base to provide greater bond strength. Key words:Recycled bracket, shear bond strength, sandblasting, stainless steel orthodontic bracket.

  13. Effects of recycling and bonding agent application on bond strength of stainless steel orthodontic brackets

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    Bahnasi, Faisal I.; Abu-Hassan, Mohame I.

    2013-01-01

    Objectives: 1) to assess different methods of recycling orthodontic brackets, 2) to evaluate Shear Bond Strength (SBS) of (a) new, (b) recycled and (c) repeated recycled stainless steel brackets (i) with and (ii) without bracket base primer. Study Design: A total of 180 extracted human premolar teeth and 180 premolar stainless steel brackets were used. One hundred teeth and 100 brackets were divided into five groups of 20-teeth each. Four methods of recycling orthodontic brackets were used in each of the first four groups while the last one (group V) was used as the control. Groups (I-V) were subjected to shear force within half an hour until the brackets debond. SBS was measured and the method showing the highest SBS was selected. A New group (VI) was recycled twice with the selected method. Six subgroups (1-6) were established; the primer was applied for three sub-groups, and the composite was applied for all brackets. Brackets were subjected to the same shear force, and SBS was measured for all sub-groups. Results: There was a significant difference between the mean SBS of the sandblasting method and the means of SBS of each of the other three methods. There was however, no significant difference between the mean SBS of the new bracket and the mean SBS of recycled bracket using sandblasting. The mean SBS of all sub-groups were more than that recommended by Reynolds (17) in 1975. Brackets with primer showed slightly higher SBS compared to those of brackets without bonding agent. Conclusion: To decrease cost, sandblasted recycled orthodontic brackets can be used as an alternative to new brackets. It is recommended to apply a bonding agent on the bracket base to provide greater bond strength. Key words:Recycled bracket, shear bond strength, sandblasting, stainless steel orthodontic bracket. PMID:24455081

  14. Recent Advances in Adhesive Bonding - The Role of Biomolecules, Nanocompounds, and Bonding Strategies in Enhancing Resin Bonding to Dental Substrates.

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    Münchow, Eliseu A; Bottino, Marco C

    2017-09-01

    To present an overview on the main agents (i.e., biomolecules and nanocompounds) and/or strategies currently available to amplify or stabilize resin-dentin bonding. According to studies retrieved for full text reading (2014-2017), there are currently six major strategies available to overcome resin-dentin bond degradation: (i) use of collagen crosslinking agents, which may form stable covalent bonds with collagen fibrils, thus strengthening the hybrid layer; (ii) use of antioxidants, which may allow further polymerization reactions over time; (iii) use of protease inhibitors, which may inhibit or inactivate metalloproteinases; (iv) modification of the bonding procedure, which may be performed by using the ethanol wet-bonding technique or by applying an additional adhesive (hydrophobic) coating, thereby strengthening the hybrid layer; (v) laser treatment of the substrate prior to bonding, which may cause specific topographic changes in the surface of dental substrates, increasing bonding efficacy; and (vi) reinforcement of the resin matrix with inorganic fillers and/or remineralizing agents, which may positively enhance physico-mechanical properties of the hybrid layer. With the present review, we contributed to the better understanding of adhesion concepts and mechanisms of resin-dentin bond degradation, showing the current prospects available to solve that problematic. Also, adhesively-bonded restorations may be benefited by the use of some biomolecules, nanocompounds or alternative bonding strategies in order to minimize bond strength degradation.

  15. Tensile bond strength of hydroxyethyl methacrylate dentin bonding agent on dentin surface at various drying techniques

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    Kun Ismiyatin

    2010-06-01

    Full Text Available Background: There are several dentin surface drying techniques to provide a perfect resin penetration on dentin. There are two techniques which will be compared in this study. The first technique was by rubbing dentin surface gently using cotton pellet twice, this technique is called blot dry technique. The second technique is by air blowing dentin surface for one second and continued by rubbing dentin surface gently using moist cotton. Purpose: This experiment was aimed to examine the best dentin surface drying techniques after 37% phosphoric acid etching to obtain the optimum tensile bond strength between hydroxyethyl methacrylate (HEMA and dentin surface. Method: Bovine teeth was prepared flat to obtain the dentin surface and than was etched using 37% phosphoric acid for 15 seconds. After etching the dentin was cleaned using 20 cc plain water and dried with blot dry techniques (group I, or dried with air blow for one second (group II, or dried with air blow for one second, and continued with rubbing gently using moist cotton pellet (group III, and without any drying as control group (group IV. After these drying, the dentin surfaces were applied with resin dentin bonding agent and put into plunger facing the composite mould. The antagonist plunger was filled with composite resin. After 24 hours, therefore bond strength was measured using Autograph. Result: Data obtained was analyzed using One-Way ANOVA with 95% confidence level and continued with LSD test on p≤0.05. The result showed that the highest tensile bond strength was on group I, while the lowest on group IV. Group II and IV, III and IV, II and III did not show signigicant difference (p>0.05. Conclusion: Dentin surface drying techniques through gentle rubbing using cotton pellet twice (blot dry technique gave the greatest tensile bond strength.Latar belakang masalah: Tehnik pengeringan permukaan dentin agar resin dapat penetrasi dengan sempurna adalah dengan cara pengusapan secara

  16. Influence of disinfectant solutions on the tensile bond strength of a fourth generation dentin bonding agent

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    BOCANGEL Jorge Saldivar

    2000-01-01

    Full Text Available The purpose of the present study was to evaluate the influence of different disinfectant solutions on the tensile bond strength of a fourth generation dentin bonding agent. Forty non carious human molars were selected. Teeth were embedded in acrylic resin and ground until the exposure of a flat superficial dentin surface. Teeth were randomly divided in 4 groups and treated as follows: Group 1 - 2.5% NaOCl for 40 seconds; Group 2 - 2% chlorhexidine for 40 seconds; Group 3 - 1.23% acidulated fluoride for 4 minutes; and Group 4 - control (without disinfectant solution. Following treatments, Scotchbond Multipurpose Plus® (3M was used according to the manufacturer's instructions. After that, the test specimens were built with composite resin (Z100®-3M, using a standard Teflon matrix. The specimens were stored in distilled water for 24 hours at a temperature of 37ºC. The tensile strength test was performed using a Mini Instrom testing machine. The mean values obtained for each group, in MPa, were: Group 1 - 7.37 (± 2.51; Group 2 - 11.25 (± 4.65; Group 3 - 9.80 (± 3.11; and Group 4 - 10.96 (± 3.37. The results were submitted to statistical analysis using the ANOVA test, and no statistical significant differences among the groups were found. It can be concluded that the different disinfectant substances used in this research do not adversely affect dentin adhesion.

  17. Knowledge Management in Role Based Agents

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    Kır, Hüseyin; Ekinci, Erdem Eser; Dikenelli, Oguz

    In multi-agent system literature, the role concept is getting increasingly researched to provide an abstraction to scope beliefs, norms, goals of agents and to shape relationships of the agents in the organization. In this research, we propose a knowledgebase architecture to increase applicability of roles in MAS domain by drawing inspiration from the self concept in the role theory of sociology. The proposed knowledgebase architecture has granulated structure that is dynamically organized according to the agent's identification in a social environment. Thanks to this dynamic structure, agents are enabled to work on consistent knowledge in spite of inevitable conflicts between roles and the agent. The knowledgebase architecture is also implemented and incorporated into the SEAGENT multi-agent system development framework.

  18. Effect of a whitening agent application on enamel bond strength of self-etching primer systems.

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    Miyazaki, Masashi; Sato, Hikaru; Sato, Tomomi; Moore, B Keith; Platt, Jeffrey A

    2004-06-01

    Though reduction in bond strength after tooth whitening has been reported, little is known about it's effect on enamel bond strength of two-step bonding systems that exclude phosphoric acid etching prior to bonding agent application. The purpose of this study was to determine the effect of whitening procedure using an in-office whitening agent on enamel bond strength of self-etching primer systems. Three self-etching primer systems, Imperva Fluoro Bond, Mac Bond II, Clearfil SE Bond, and a one-bottle adhesive system Single Bond as a control material, were used. Bovine mandibular incisors were mounted in self-curing resin and the facial enamel or dentin surfaces were ground wet on 600-grit SiC paper. An in-office whitening agent, Hi-Lite was applied on the tooth surface according to the manufacturer's instruction. Bonding procedures were done soon after rinsing off the whitening agent or after 24 hours storage in distilled water. Specimens without whitening procedure were prepared as controls. Fifteen specimens per test group were stored in 37 degrees C distilled water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVA followed by Duncan multiple range test were used for statistical analysis of the results. For the specimens made soon after rinsing off the whitening agent, a significant decrease in enamel bond strength was observed for all the bonding systems used. For the specimens made after 24 hours storage in water, a small decrease in enamel bond strength was observed and no significant differences were found compared to those of controls (without whitening). From the results of this study, enamel bond strengths of the self-etching primer systems might be affected to a lesser degree after rinsing with water followed by 24 hours storage in water.

  19. Enamel Wetness Effects on Microshear Bond Strength of Different Bonding Agents (Adhesive Systems): An in vitro Comparative Evaluation Study.

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    Kulkarni, Girish; Mishra, Vinay K

    2016-05-01

    The purpose of this study was to compare the effect of enamel wetness on microshear bond strength using different adhesive systems. To evaluate microshear bond strength of three bonding agents on dry enamel; to evaluate microshear bond strength of three bonding agents on wet enamel; and to compare microshear bond strength of three different bonding agents on dry and wet enamel. Sixty extracted noncarious human premolars were selected for this study. Flat enamel surfaces of approximately 3 mm were obtained by grinding the buccal surfaces of premolars with water-cooled diamond disks. This study evaluated one etch-and-rinse adhesive system (Single Bond 2) and two self-etching adhesive systems (Clearfil SE Bond and Xeno-V). The specimens were divided into two groups (n = 30). Group I (dry) was air-dried for 30 seconds and in group II (wet) surfaces were blotted with absorbent paper to remove excess water. These groups were further divided into six subgroups (n = 10) according to the adhesives used. The resin composite, Filtek Z 250, was bonded to flat enamel surfaces that had been treated with one of the adhesives, following the manufacturer's instructions. After being stored in water at 37°C for 24 hours, bonded specimens were stressed in universal testing machine (Fig. 3) at a crosshead speed of 1 mm/min. The data were evaluated with one-way and two-way analysis of variance (ANOVA), t-test, and Tukey's Multiple Post hoc tests (a = 0.05). The two-way ANOVA and Tukey's Multiple Post hoc tests showed significant differences among adhesive systems, but wetness did not influence microshear bond strength (p = 0.1762). The one-way ANOVA and t-test showed that the all-in-one adhesive (Xeno-V) was the only material influenced by the presence of water on the enamel surface. Xeno-V showed significantly higher microshear bond strength when the enamel was kept wet. Single Bond 2 adhesive showed significantly higher microshear bond strength as compared with Xeno-V adhesive but no

  20. ROLE OF DIASPORA BONDS IN DEVELOPING COUNTRIES

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    Y. Bunyk

    2015-08-01

    Full Text Available The article deals with the problem of the bond issue for the Diaspora as a source of financing of the national economy and a factor of development. We reveal the following factors driving demand in the diaspora bond market: targeting at a project, channels, audience and marketing. The paper shows international experience to attract migrants’ savings and use them to issue bonds. Investors consider diaspora bonds because: firstly, people who have disposable income, who can commit that income or that excess income to a long term investment should look at diaspora bonds: secondly, people who really want to participate in transforming the home country should look at diaspora bond specifically diaspora bonds related to projects: and last but not least, if there are incentives around diaspora bonds for example whether there’s tax incentive and other kinds of incentive, that also should be taken into account. Also we disclosed the possibility of using this type of securities in Ukraine and its expedience.

  1. Clinical Evaluation of applying a hydrophobic and a hydrophilic bonding agent on the retention and durability of fissure sealant therapy

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    Mostafa GHandi

    2016-03-01

    Full Text Available Background and Aims: As in fissure sealant therapy the tooth surface is mostly enamel, the use of an enamel bonding agent (hydrophobic bonding agent may be more cost effective than that of newer generations of bonding (hydrophilic bonding agents. The aim of this study was to compare the retention and durability of fissure sealant therapy when applying an enamel bonding agent, a dentin bonding agent and no bonding agent during 4 years. Materials and Methods: This study was done on the first permanent molars of the upper and lower jaws of 24 students of the first grade of a primary school (6-7 years old. On 36 teeth, a dentin bonding agent (Excite was applied under the fissure sealant and on 36 teeth an enamel bonding agent (Margin bond was applied under the fissure sealant. Then, 24 teeth were selected from these two groups and were compared with a group (including 24 teeth with no bonding agent under the fissure sealant (as control group. All the fissures of the teeth were evaluated annually for 4 years to find out the presence or absence of fissure sealant substance. Data were analyzed using Wilcoxon test. Results: From the statistical analysis, there was no significant difference in retention and durability of the fissure sealant substance comparing the group with dentin bonding agent (Excite and the group with enamel bonding agent (Margin bond. Also, using a bonding agent made no significant difference (P>0.05. Conclusion: According to the results of this study, using a bonding agent made no improvement in the retention and durability of fissure sealant substance.

  2. Are Bonding Agents being Effective on the Shear Bond Strength of Orthodontic Brackets Bonded to the Composite?

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    Fahimeh Farzanegan

    2014-06-01

    Full Text Available Introduction: One of the clinical problems in orthodontics is the bonding of brackets tocomposite restorations. The aim of this study was to evaluate the shear bondstrength of brackets bonded to composite restorations using Excite. Methods:Forty brackets were bonded to composite surfaces, which were embedded inacrylic resin. One of the following four protocols was employed for surfacepreparation of the composite: group 1 37% phosphoric acid for 60 seconds, group2 roughening with a diamond bur plus 37% phosphoric acid for 60 seconds, group3 37% phosphoric acid for 60 seconds and the applying Excite®, group4 roughening with diamond bur plus 37% phosphoric acid for 60 seconds andapplying Excite®. Maxillary central brackets were bonded onto thecomposite prepared samples with Transbond XT. Shear Bond Strength (SBS wasmeasured by a universal testing machine. The ANOVA and Tukey test was utilizedfor data analysis. Results: There was a significant difference betweenthe four groups (P

  3. Shear strength of orthodontic bracket bonding with GIC bonding agent after the application of CPP-ACPF paste

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    Melisa Budipramana

    2013-03-01

    Full Text Available Background: White spot lesion is a major problem during fixed orthodontic treatment. This problem can be solved by minimizing white spot lesion before the treatment and using a fluoride-releasing bonding agent. The application of casein phosphopeptidesamorphous calcium phospate fluoride (CPP-ACPF paste as remineralization agent before treatment and GIC as orthodontic bonding agent is expected to overcome this problem as well as to strengthen GIC bonding. Purpose: To measure the shear strength of fix orthodontic appliance using GIC bonding with CPP-ACPF application prior treatment. Methods: In this study, 50 extracted premolars were randomly divided into 2 groups: group 1 as treatment group and group II as control group that was not given CPPACPF pretreatment. After having been cut and put into acrylic device, the samples in group I were given pretreatment with CPP-ACPF paste on enamel surface for 2 minutes twice a day as instructed in product label for 14 days. Orthodontic brackets were bonded with GIC bonding agent on all samples in both groups as instructed in product label. Then, the shear strength was measured by Autograph Shimatzu with crosshead speed 0.5 mm/minute. The data was analyzed with Independent t-test. Results: The mean shear bond strength in treatment group was 19.22 ± 4.04 MPa and in control group was 12.97 ± 3.97 MPa. Independent t-test analysis showed that there was a significant difference between treatment and control group (p<0.05. Conclusion: CPP-ACPF pretreatment could increase GIC orthodontic bonding shear strength.Latar belakang: Lesi putih karies merupakan masalah utama selama perawatan dengan peranti cekat ortodonti. Hal ini dapat diatasi dengan cara mengurangi lesi putih sebelum perawatan dengan menggunakan bahan bonding yang mengandung fluorida. Aplikasi pasta casein phosphopeptides-amorphous calcium phospate fluoride (CPP-ACPF sebagai bahan remineralisasi sebelum perawatan dan bahan bonding GIC diharapkan dapat

  4. Assessing the effects of hydrogen peroxide bleaching agent on the shear bond strength of orthodontic brackets.

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    Andrighetto, Augusto Ricardo; de Leão Withers, Eduardo Henrique; Grando, Karlos Giovani; Ambrosio, Aldrieli Regina; Shimizu, Roberto Hideo; Melo, Ana Cláudia

    2016-01-01

    Tooth bleaching is, today, one of the most widespread cosmetic treatments in dental practice,  so it is important to determine whether it can interfere with orthodontic bonding or not. The aim of this study was to assess the in vitro effects of 35% hydrogen peroxide bleaching agent on the shear bond strength of orthodontic brackets. Forty-five upper bicuspids were divided into three groups (n = 15). In the control Group (C), the brackets were bonded without previous bleaching treatment. Group 1 (G1) was treated with 35% hydrogen peroxide bleaching agent 24 h before bracket bonding. Group 2 was also bleached, and the brackets were bonded after 30 days. The shear bond strength of the brackets was measured using an EMIC machine, and the results were analyzed by ANOVA. There were no statistically significant differences between the three groups (P > 0.05), with Group C showing a mean bond strength of 9.72 ± 2.63 MPa, G1 of 8.09 ± 2.63 MPa, and G2 of 11.15 ± 4.42 MPa. It was possible to conclude that 35% hydrogen peroxide bleaching agent does not affect the shear strength of orthodontic brackets bonded 24 h and 30 days after bleaching.

  5. Shear bond strength after dentin bleaching with 10% carbamide peroxide agents

    OpenAIRE

    Basting, Roberta Tarkany; Freitas, Patrícia Moreira de; Pimenta, Luiz André Freire; Serra, Mônica Campos

    2004-01-01

    This in vitro study evaluated the shear bond strength (SBS) of dentin treated with two 10% carbamide peroxide bleaching agents 15 days after bleaching and storage in artificial saliva. Dentin fragments were randomly divided into 3 groups (n = 20) for the treatment with the two different bleaching agents (Rembrandt 10% or Opalescence 10%) or with a placebo agent, applied to the tooth surface for 8 hours a day. During the remaining time, the specimens were stored in artificial saliva. After 42 ...

  6. Investigation of the interfacial bonding in composite propellants. 1,3,5-Trisubstituted isocyanurates as universal bonding agents

    Directory of Open Access Journals (Sweden)

    GORDANA S. USCUMLIC

    2006-05-01

    Full Text Available A series of 1,3,5-trisubstituted isocyanurates (substituents: CH2CH2OH, CH2CH=CH2 and CH2CH2COOH was synthesized according to a modified literature procedure. Experimental investigations included modification of the synthetic procedure in terms of the starting materials, solvents, temperature, isolation techniques, as well as purification and identification of the products. All the synthesized isocyanurates were identified by their melting point and FTIR, 1H NMR and UV spectroscopic data. Fourier transform infrared spectrophotometry was also used to study the interaction between ammonium perchlorate, hydroxyl terminated poly(butadiene, carboxyl terminated poly(butadiene, poly(butadiene-co-acrylonitrile, poly(propylene ether, cyclotrimethylenetrinitramine and the compounds synthesized in this work, which can serve as bonding agents. The results show that tris(2-hydroxyethylisocyanurate is a universal bonding agent for the ammonium perchlorate/carboxyl terminated poly(butadiene/cyclotrimethylenetrinitramine composite propellant system.

  7. Application Framework with Abstractions for Protocol and Agent Role

    DEFF Research Database (Denmark)

    Kristensen, Bent Bruun

    2016-01-01

    In multi-agent systems, agents interact by sending and receiving messages and the actual sequences of message form interaction structures between agents. Protocols and agents organized internally by agent roles support these interaction structures. Description and use of protocols based on agent ...... roles are supported by a simple and expressive application framework....

  8. [The bonding mechanisms of base metals for metal-ceramic crown microstructure analysis of bonding agent and gold bond between porcelain and base metals].

    Science.gov (United States)

    Wang, C C; Hsu, C S

    1996-06-01

    The use of base metal alloys for porcelain fused to a metal crown and bridges has increased recently because of lower price, high hardness, high tensile strength and high elastic modulus. The addition of beryllium to base metal alloys increased fluidity and improved casting fitness. Beryllium also controlled surface oxidation and bonding strength. The bonding agent and gold bonding agent also affected the bonding strength between porcelain and metal alloys. Four commercially available ceramic base alloys were studied (two alloys contained beryllium element, another two did not). The purpose of this investigation was to study the microstructure between porcelain matrix, bonding agent and alloy matrix interfaces. A scanning electron micro-probe analyzer and energy dispersive X-ray spectroscopy (EDXS) were used to study the distribution of elements (Ni, Cr, Mo, Cu, O, Si, Sn, Al) in four base alloys. The following results were obtained: 1. The thickness of the oxidized layer of Rexillium III alloy and Unitbond alloy (contained beryllium) was thinner than Unibond alloy and Wiron 88 alloy (no beryllium). 2. The thickness of the oxidized layer of alloys in air (10 minutes and 30 minutes) was thinner in Unitbond (2.45 microns and 3.80 microns) and thicker in Wiron 88 (4.39 microns and 5.96 microns). 3. The thickness of the oxidized layer occurring for a duration of ten minutes (in vaccum) showed that the Rexillium III alloy was the thinnest (1.93 microns), and Wiron 88 alloy was the thickest (2.30 microns). But in thirty minutes (vacuum), Unitbond alloy was the thinnest (3.37 microns), and Wiron 88 alloy was the thickest (5.51 microns). 4. The intensity of Cr elements was increased obviously near the interface between Unitbond alloy, Wiron 88 alloy (no beryllium) and oxidized layer, but the intensity of Ni and Mo elements was slightly increased. The intensity of Cr element was not increased markedly between Rexillium III alloy, Unitbond alloy (beryllium) and oxidized

  9. A novel biomimetic orthodontic bonding agent helps prevent white spot lesions adjacent to brackets.

    Science.gov (United States)

    Manfred, Lauren; Covell, David A; Crowe, Jennifer J; Tufekci, Eser; Mitchell, John C

    2013-01-01

    To compare changes in enamel microhardness adjacent to orthodontic brackets after using bonding agents containing various compositions of bioactive glass compared to a traditional resin adhesive following a simulated caries challenge. Extracted human third molars (n  =  10 per group) had orthodontic brackets bonded using one of four novel bioactive glass (BAG)-containing orthodontic bonding agents (BAG-Bonds) or commercially available Transbond-XT. The four new adhesives contained BAG in varying percentages incorporated into a traditional resin monomer mixture. Teeth were cycled through low-pH demineralizing and physiologic-pH remineralizing solutions once each day over 14 days. Microhardness was measured on longitudinal sections of the teeth 100, 200, and 300 µm from the bracket edge and beneath the brackets, at depths of 25 to 200 µm from the enamel surface. Normalized hardness values were compared using three-way analysis of variance. Significantly less reduction in enamel microhardness was found with the experimental adhesives at depths of 25 and 50 µm at all distances from the bracket edge. In all groups, there were no significant changes in enamel microhardness past 125-µm depth. Results varied with the different BAG-Bonds, with 81BAG-Bond showing the smallest decrease in enamel microhardness. The BAG-Bonds tested in this study showed a reduction in the amount of superficial enamel softening surrounding orthodontic brackets compared to a traditional bonding agent. The results indicate that clinically, BAG-Bonds may aid in maintaining enamel surface hardness, therefore helping prevent white spot lesions adjacent to orthodontic brackets.

  10. Effects of recycling and bonding agent application on bond strength of stainless steel orthodontic brackets

    OpenAIRE

    Bahnasi, Faisal I.; Abd-Rahman, Aida NA.; Abu-Hassan, Mohame I.

    2013-01-01

    Objectives: 1) to assess different methods of recycling orthodontic brackets, 2) to evaluate Shear Bond Strength (SBS) of (a) new, (b) recycled and (c) repeated recycled stainless steel brackets (i) with and (ii) without bracket base primer. Study Design: A total of 180 extracted human premolar teeth and 180 premolar stainless steel brackets were used. One hundred teeth and 100 brackets were divided into five groups of 20-teeth each. Four methods of recycling orthodontic brackets were used in...

  11. Bond Strength of Resin Cements to Dentin Using New Universal Bonding Agents

    Science.gov (United States)

    2015-06-30

    and acidic simplified adhesives is a well-studied phenomenon (Kanehira et al., 2006). A chemical incompatibility may occur in the oxygen-inhibited...not completely eliminate this incompatibility (Tay et al., 2003). Recently, new “universal adhesives ” have been introduced. These universal...potential incompatibilities with self-curing resin materials. Low bond strength between self-curing resin materials and acidic simplified adhesives is

  12. Antibacterial activity and ion release of bonding agent containing amorphous calcium phosphate nanoparticles.

    Science.gov (United States)

    Chen, Chen; Weir, Michael D; Cheng, Lei; Lin, Nancy J; Lin-Gibson, Sheng; Chow, Laurence C; Zhou, Xuedong; Xu, Hockin H K

    2014-08-01

    Recurrent caries at the margins is a primary reason for restoration failure. The objectives of this study were to develop bonding agent with the double benefits of antibacterial and remineralizing capabilities, to investigate the effects of NACP filler level and solution pH on Ca and P ion release from adhesive, and to examine the antibacterial and dentin bond properties. Nanoparticles of amorphous calcium phosphate (NACP) and a quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM) were synthesized. Scotchbond Multi-Purpose (SBMP) primer and adhesive served as control. DMADDM was incorporated into primer and adhesive at 5% by mass. NACP was incorporated into adhesive at filler mass fractions of 10%, 20%, 30% and 40%. A dental plaque microcosm biofilm model was used to test the antibacterial bonding agents. Calcium (Ca) and phosphate (P) ion releases from the cured adhesive samples were measured vs. filler level and solution pH of 7, 5.5 and 4. Adding 5% DMADDM and 10-40% NACP into bonding agent, and water-aging for 28 days, did not affect dentin bond strength, compared to SBMP control at 1 day (p>0.1). Adding DMADDM into bonding agent substantially decreased the biofilm metabolic activity and lactic acid production. Total microorganisms, total streptococci, and mutans streptococci were greatly reduced for bonding agents containing DMADDM. Increasing NACP filler level from 10% to 40% in adhesive increased the Ca and P ion release by an order of magnitude. Decreasing solution pH from 7 to 4 increased the ion release from adhesive by 6-10 folds. Bonding agents containing antibacterial DMADDM and remineralizer NACP were formulated to have Ca and P ion release, which increased with NACP filler level from 10% to 40% in adhesive. NACP adhesive was "smart" and dramatically increased the ion release at cariogenic pH 4, when these ions would be most-needed to inhibit caries. Therefore, bonding agent containing DMADDM and NACP may be promising to inhibit

  13. Microtensile dentin bond strength of fifth with five seventh-generation dentin bonding agents after thermocycling: An in vitro study

    Directory of Open Access Journals (Sweden)

    Bruhvi Poptani

    2012-01-01

    Full Text Available Objectives: The objective of this in vitro study was to compare the microtensile dentin bond strength (μTBS of five seventh-generation dentin bonding agents (DBA with fifth-generation DBA before and after thermocycling. Materials and Methods: Ten extracted teeth were assigned to fifth generation control group (optibond solo and each of the five experimental groups namely, Group I (G-Bond ,Group II (S 3 Clearfil, Group III (One Coat 7.0, Group IV (Xeno V, and Group V (Optibond all in one. The crown portions of the teeth were horizontally sectioned below the central groove to expose the dentin. The adhesive resins from all groups were bonded to the teeth with their respective composites. Specimens of sizes 1 × 1 × 6 mm 3 were obtained. Fifty specimens that bonded to dentin from each group were selected. Twenty-five of the specimens were tested for debonding without thermocycling and the remaining were subjected to thermocycling followed by μTBS testing. The data were analyzed with one-way ANOVA and Dunnett′s-test for comparison with the reference group(Vth Generation. Results: There was no significant difference (P > 0.05 between the fifth- and seventh-generation adhesives before and after thermocycling. The results of our study showed significantly higher value (P < 0.05 of μTBS of seventh-generation Group II (Clearfil S 3 compared to the fifth-generation before and after thermocycling. Conclusion: The study demonstrated that the Clearfil S 3 bond had the highest μTBS values. In addition, of the five tested seventh-generation adhesive resins were comparable to the fifth-generation DBA.

  14. Effects of surface treatment on bond strength between dental resin agent and zirconia ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Moradabadi, Ashkan [Department of Electrochemistry, Universität Ulm, Ulm (Germany); Roudsari, Sareh Esmaeily Sabet [Department of Optoelectonics, Universität Ulm, Ulm (Germany); Yekta, Bijan Eftekhari [School of Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Rahbar, Nima, E-mail: nrahbar@wpi.edu [Department of Civil and Environmental Engineering, Worcester Polytechnic Institute, Worcester, MA 01609 (United States)

    2014-01-01

    This paper presents the results of an experimental study to understand the dominant mechanism in bond strength between dental resin agent and zirconia ceramic by investigating the effects of different surface treatments. Effects of two major mechanisms of chemical and micromechanical adhesion were evaluated on bond strength of zirconia to luting agent. Specimens of yttrium-oxide-partially-stabilized zirconia blocks were fabricated. Seven groups of specimens with different surface treatment were prepared. 1) zirconia specimens after airborne particle abrasion (SZ), 2) zirconia specimens after etching (ZH), 3) zirconia specimens after airborne particle abrasion and simultaneous etching (HSZ), 4) zirconia specimens coated with a layer of a Fluorapatite-Leucite glaze (GZ), 5) GZ specimens with additional acid etching (HGZ), 6) zirconia specimens coated with a layer of salt glaze (SGZ) and 7) SGZ specimens after etching with 2% HCl (HSGZ). Composite cylinders were bonded to airborne-particle-abraded surfaces of ZirkonZahn specimens with Panavia F2 resin luting agent. Failure modes were examined under 30 × magnification and the effect of surface treatments was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). SZ and HSZ groups had the highest and GZ and SGZ groups had the lowest mean shear bond strengths among all groups. Mean shear bond strengths were significantly decreased by applying a glaze layer on zirconia surfaces in GZ and SGZ groups. However, bond strengths were improved after etching process. Airborne particle abrasion resulted in higher shear bond strengths compared to etching treatment. Modes of failure varied among different groups. Finally, it is concluded that micromechanical adhesion was a more effective mechanism than chemical adhesion and airborne particle abrasion significantly increased mean shear bond strengths compared with another surface treatments. - Highlights: • Understanding the dominant mechanism of bonding

  15. The effect of bonding agents on the microleakage of sealant following contamination with saliva

    Directory of Open Access Journals (Sweden)

    Askarizadeh Nahid

    2008-06-01

    Full Text Available Aims : An issue of concern in dentistry is the inadequacy of adhesion and proper sealing following restoration of a tooth, which can lead to marginal leakage. The aim of this study was to evaluate the effect of a bonding agent on the microleakage of a sealant material following contamination with saliva. Materials and Methods : In this experimental research, 48 sound premolars were divided into two groups. The first group received sealant without bonding and the other group was given sealant with bonding. After prophylaxis, the occlusal surfaces were etched with 37% phosphoric acid gel and the teeth were then placed in fresh human saliva for l0 s. Following this, in the first group fissure sealant (Kerr was applied directly and cured; for the second group sealant was placed and cured after bonding (Single Bond; 3M. All samples were thermocycled (500 cycles; between 5°C and 55°C; dwell time of 30 s. Silver nitrate was used as the leakage tracer. The teeth were sectioned. Microleakage evaluation was made by stereomicroscope at 40x magnification and the results were evaluated with the Mann-Whitney U test. Results : In the group that received sealant without bonding extensive microleakage was seen; placement of sealant with bonding significantly reduced microleakage. Conclusion : In the presence of contamination with saliva, use of bonding under the fissure sealant can reduce microleakage

  16. Microleakage of three self-etch bonding agents in class 5 composite cavities

    Directory of Open Access Journals (Sweden)

    Saeed Nemati Anaraki

    2016-07-01

    Full Text Available Background and Aims: Microleakage is one of the most common problems in bonding systems, which cause different clinical shortcomings such as post operative sensitivity, marginal discoloration and pulp necrosis that can decrease those using bonding systems. The aim of this study was to compare the microleakage of three self etch bonding agents (generation 6 and 7 in class 5 composite cavities. Materials and Methods: In this experimental study, 30 facial class 5 cavities were prepared in 30 human premolar teeth which were freshly extracted for orthodontic purposes. Cl V cavities were prepared in 2*3*2 mm dimensions. Occlusal margins were in enamel and gingival ones in cementum and randomly divided into 3 groups of 10 each. Then the cavities were treated by clearhil SE Bond (Kuraray, Japan, G Bond (GC, Japan, and Opti Bond Solo Plus (Kerr, USA, according to the manufacturers’ insductions. Then the cavities were filled using Z100 resin composite. The specimens were then immersed in a 50% AgNo solution for 24 hrs. Then, the teeth were cut buccolingually to be evaluated for dye penetration with stereomicroscope. Data were analyzed using Kruskal-Wallis test. Results: This study revealed that Opti bond solo plus had type1 microleakage (dye penetration up to 1/3 of cavity in 80% of specimen, and type 4 microleakage (along axial wall in 10%. Clearfil SE bond had no leakage in 50%, type1 in 40% and type 2 (up to 2/3 of cavity in 10%. But there was no significant difference in the microleakage at the gingival margins between 3 groups (P>0.05. Conclusion: Clearfil SE Bond and G bond could prevent microleakage more effectively than that of Opti Bond Solo Plus on the occlusal margins. However, no difference in the microleakage on the gingival surfaces was found.

  17. Effect of a re‑wetting agent on bond strength of an adhesive to ...

    African Journals Online (AJOL)

    Objective: This study investigated the effect of a re‑wetting agent on the microtensile bond strengths (μTBS) of primary and permanent dentin after acid or laser etching. Materials and Methods: Twelve permanent and 12 primary molar teeth were ground to expose an occlusal dentin surface. Each group teeth were randomly ...

  18. Release Of Gaseous NH(3) From NH(4)CIO(4) By HTPB-Bonding Agents

    Science.gov (United States)

    Mccomb, James C.

    1993-01-01

    Report describes experimental study of rate of generation of ammonia and total amount of ammonia generated by chemical reactions between bonding agents and grains of ammonium perchlorate in solid rocket propellants. Also provides insight into mechanisms of chemical reactions between several types of organic amines with solid ammonium perchlorate.

  19. How Is the Enamel Affected by Different Orthodontic Bonding Agents and Polishing Techniques?

    Directory of Open Access Journals (Sweden)

    Farzin Heravi

    2015-10-01

    Full Text Available Objectives: The objective of this study was to assess the effect of new bonding techniques on enamel surface.Materials and Methods: Sixty upper central incisors were randomly divided into two equal groups. In the first group, metal brackets were bonded using Trans- bondXT and, in the second group, the same brackets were bonded with MaxcemElite. The shear bond strength (SBS of both agents to enamel was measured and the number and length of enamel cracks before bonding, after debonding and after polishing were compared. The number of visible cracks and the adhesive remnant index (ARI scores in each group were also measured.Results: There were significantly more enamel cracks in the Transbond XT group after debonding and polishing compared to the Maxcem Elite group. There was no significant difference in the length of enamel cracks between the two groups; but, in each group, a significant increase in the length of enamel cracks was noticeable after debonding. Polishing did not cause any statistically significant change in crack length. The SBS of Maxcem Elite was significantly lower than that of Transbond XT (95% confidence interval.Conclusion: Maxcem Elite offers clinically acceptable bond strength and can thus be used as a routine adhesive for orthodontic purposes since it is less likely todamage the enamel.

  20. Combination Effect of Hemostatic and Disinfecting Agents on Micro-leakage of Restorations Bonded with Different Bonding Systems

    Directory of Open Access Journals (Sweden)

    Farhadpour H

    2016-09-01

    Full Text Available Statement of Problem: Hemostatic agents may affect the micro-leakage of different adhesive systems. Also, chlorhexidine has shown positive effects on micro-leakage. However, their interaction effect has not been reported yet. Objectives: To evaluate the effect of contamination with a hemostatic agent on micro- leakage of total- and self-etching adhesive systems and the effect of chlorhexidine application after the removal of the hemostatic agent. Materials and Methods: Standardized Class V cavity was prepared on each of the sixty caries free premolars at the cemento-enamel junction, with the occlusal margin located in enamel and the gingival margin in dentin. Then, the specimens were randomly divided into 6 groups (n = 10 according to hemostatic agent (H contamination, chlorhexidine (CHX application, and the type of adhesive systems (Adper Single Bond and Clearfil SE Bond used. After filling the cavities with resin composite, the root apices were sealed with utility wax. Furthermore, all the surfaces, except for the restorations and 1mm from the margins, were covered with two layers of nail varnish. The teeth were immersed in a 0.5% basic fuschin dye for 24 hours, rinsed, blot-dried and sectioned longitudinally through the center of the restorations bucco- lingualy. The sections were examined using a stereomicroscope and the extension of dye penetration was analyzed according to a non-parametric scale from 0 to 3. Statistical analysis was performed using Kruskal-Wallis test and Mann-Whitney U-test. Results: While ASB group showed no micro-leakage in enamel, none of the groups showed complete elimination of micro-leakage from the dentin. Regarding micro- leakage at enamel, and dentin margins, there was no significant difference between groups 1 and 2, 1 and 3, and 2 and 3 (p > 0.05. A significantly lower micro-leakage at the enamel and dentin margins was observed in group 3, compared to group 6. No significant difference was observed between

  1. How Is the Enamel Affected by Different Orthodontic Bonding Agents and Polishing Techniques?

    Science.gov (United States)

    Heravi, Farzin; Shafaee, Hooman; Abdollahi, Mojtaba; Rashed, Roozbeh

    2015-03-01

    The objective of this study was to assess the effect of new bonding techniques on enamel surface. Sixty upper central incisors were randomly divided into two equal groups. In the first group, metal brackets were bonded using TransbondXT and, in the second group, the same brackets were bonded with Maxcem Elite. The shear bond strength (SBS) of both agents to enamel was measured and the number and length of enamel cracks before bonding, after debonding and after polishing were compared. The number of visible cracks and the adhesive remnant index (ARI) scores in each group were also measured. There were significantly more enamel cracks in the Transbond XT group after debonding and polishing compared to the Maxcem Elite group. There was no significant difference in the length of enamel cracks between the two groups; but, in each group, a significant increase in the length of enamel cracks was noticeable after debonding. Polishing did not cause any statistically significant change in crack length. The SBS of Maxcem Elite was significantly lower than that of Transbond XT (95% confidence interval). Maxcem Elite offers clinically acceptable bond strength and can thus be used as a routine adhesive for orthodontic purposes since it is less likely to damage the enamel.

  2. An in vitro study to evaluate the effect of two ethanol-based and two acetone-based dental bonding agents on the bond strength of composite to enamel treated with 10% carbamide peroxide

    Directory of Open Access Journals (Sweden)

    Deepa Basavaraj Benni

    2014-01-01

    Full Text Available Background and Objective: Carbamide peroxide bleaching has been implicated in adversely affecting the bond strength of composite to enamel. The objective of this in vitro study was to evaluate the effect of ethanol-based (Clearfil S 3 bond, Kuraray, Adper Single bond 2, 3M ESPE dental products and acetone-based (Prime and Bond NT, Dentsply, One Step, Bisco bonding agents on the shear bond strength of composite to enamel treated with 10% carbamide peroxide bleaching agent. Materials and Methods: A total of 120 extracted human noncarious permanent incisors were randomly divided into two groups (control and experimental. Experimental group specimens were subjected to a bleaching regimen with a 10% carbamide peroxide bleaching system (Opalescence; Ultradent Products Inc, South Jordan, USA. Composite resin cylinders were bonded to the specimens using four bonding agents and shear bond strength was determined with universal testing machine. Results: There was no statistically significant difference in the shear bond strength between control and experimental groups with both ethanol-based (Clearfil S 3 Bond and Adper Single Bond 2 and acetone-based bonding agent (Prime and Bond NT and One Step. Interpretation and Conclusion: The adverse effect of bleaching on bonding composite to enamel can be reduced or eliminated by using either ethanol- or acetone-based bonding agent. Clinical Significances: Immediate bonding following bleaching procedure can be done using ethanol- or acetone-based bonding agent without compromising bond strength.

  3. Desensitizing bioactive agents improves bond strength of indirect resin-cemented restorations: preliminary results

    Directory of Open Access Journals (Sweden)

    Fernanda de Carvalho Panzeri Pires-de-Souza

    2007-04-01

    Full Text Available OBJECTIVE: The aim of this study was to assess the bond strength of indirect composite restorations cemented with a resin-based cement associated with etch-and-rinse and self-etching primer adhesive systems to dentin treated or not with a bioactive material. MATERIALS AND METHOD: Twenty bovine incisor crowns had the buccal enamel removed and the dentin ground flat. The teeth were assigned to 4 groups (n=5: Group I: acid etching + Prime & Bond NT (Dentsply; Group II: application of a bioactive glass (Biosilicato®+ acid etching + Prime & Bond NT; Group III: One-up Bond F (J Morita; Group IV: Biosilicato® + One-up Bond F. Indirect composite resin (Artglass, Kulzer cylinders (6x10mm were fabricated and cemented to the teeth with a dual-cure resin-based cement (Enforce, Dentsply. After cementation, the specimens were stored in artificial saliva at 37ºC for 30 days and thereafter tested in tensile strength in a universal testing machine (EMIC with 50 kgf load cell at a crosshead speed of 1 mm/min. Failure modes were assessed under scanning electron microscopy. Data were analyzed statistically by ANOVA and Tukey's test (95% level of confidence. RESULTS: Groups I, II and III had statistically similar results (p>0.05. Group IV had statistically significant higher bond strength means (p<0.05 than the other groups. The analysis of the debonded surfaces showed a predominance of adhesive failure mode for Group III and mixed failure mode for the other groups. CONCLUSION: The use of desensitizing agent did not affect negatively the bonding of the indirect composite restorations to dentin, independently of the tested adhesive systems.

  4. In vitro shear bond strength of cementing agents to fixed prosthodontic restorative materials.

    Science.gov (United States)

    Piwowarczyk, Andree; Lauer, Hans-Christoph; Sorensen, John A

    2004-09-01

    Durable bonding to fixed prosthodontic restorations is desirable; however, little information is available on the strength of the bond between different cements and fixed prosthodontic restorative materials. This study determined the shear-bond strength of cementing agents to high-gold-content alloy castings and different dental ceramics: high-strength aluminum oxide (Procera AllCeram), leucite-reinforced (IPS Empress), and lithium disilicate glass-ceramic (IPS Empress 2). Prepolymerized resin composite cylinders (5.5 mm internal diameter, n=20) were bonded to the pretreated surfaces of prosthodontic materials. High-gold-content alloy and high-strength aluminum oxide surfaces were airborne-particle-abraded, and pressable ceramics were hydrofluoric acid-etched and silanized prior to cementing. The cementing agents tested were a zinc-phosphate cement (Fleck's zinc cement), glass ionomer cements (Fuji I, Ketac-Cem), resin-modified glass ionomer cements (Fuji Plus, Fuji Cem, RelyX Luting), resin cements (RelyX ARC, Panavia F, Variolink II, Compolute), and a self-adhesive universal resin cement (RelyX Unicem). Half the specimens (n=10) were tested after 30 minutes; the other half (n=10) were stored in distilled water at 37 degrees C for 14 days and then thermal cycled 1000 times between 5 degrees C and 55 degrees C prior to testing. Shear-bond strength tests were performed using a universal testing machine at a constant crosshead speed of 0.5 mm/min. Statistical analysis was performed by multifactorial analysis of variance taking interactions between effects into account. For multiple paired comparisons, the Tukey method was used (alpha=.05). In a 3-way ANOVA model, the main factors substrate, cement, time, and all corresponding interactions were statistically significant (all P <.0001). In subsequent separate 1-way or 2-way ANOVA models for each substrate type, significant differences between cement types and polymerizing modes were found (all P <.001). None of the

  5. Using Agent-Based Modeling to Assess Liquidity Mismatch in Open-End Bond Funds

    Directory of Open Access Journals (Sweden)

    Donald J. Berndt

    2017-12-01

    Full Text Available In this paper, we introduce a small-scale heterogeneous agent-based model of the US corporate bond market. The model includes a realistic micro-grounded ecology of investors that trade a set of bonds through dealers. Using the model, we simulate market dynamics that emerge from agent behaviors in response to basic exogenous factors (such as interest rate shocks and the introduction of regulatory policies and constraints. A first experiment focuses on the liquidity transformation provided by mutual funds and investigates the conditions under which redemption-driven bond sales may trigger market instability. We simulate the effects of increasing mutual fund market shares in the presence of market-wide repricing of risk (in the form of a 100 basis point increase in the expected returns. The simulations highlight robust-yet-fragile aspects of the growing liquidity transformation provided by mutual funds, with an inflection point beyond which redemption-driven negative feedback loops trigger market instability.

  6. Biasing hydrogen bond donating host systems towards chemical warfare agent recognition.

    Science.gov (United States)

    Hiscock, Jennifer R; Wells, Neil J; Ede, Jayne A; Gale, Philip A; Sambrook, Mark R

    2016-10-12

    A series of neutral ditopic and negatively charged, monotopic host molecules have been evaluated for their ability to bind chloride and dihydrogen phosphate anions, and neutral organophosphorus species dimethyl methylphosphonate (DMMP), pinacolyl methylphosphonate (PMP) and the chemical warfare agent (CWA) pinacolyl methylphosphonofluoridate (GD, soman) in organic solvent via hydrogen bonding. Urea, thiourea and boronic acid groups are shown to bind anions and neutral guests through the formation of hydrogen bonds, with the urea and thiourea groups typically exhibiting higher affinity interactions. The introduction of a negative charge on the host structure is shown to decrease anion affinity, whilst still allowing for high stability host-GD complex formation. Importantly, the affinity of the host for the neutral CWA GD is greater than for anionic guests, thus demonstrating the potential for selectivity reversal based on charge repulsion.

  7. Revealing the Interface Structure and Bonding Mechanism of Coupling Agent Treated WPC

    Directory of Open Access Journals (Sweden)

    Jiuping Rao

    2018-03-01

    Full Text Available This paper presents the interfacial optimisation of wood plastic composites (WPC based on recycled wood flour and polyethylene by employing maleated and silane coupling agents. The effect of the incorporation of the coupling agents on the variation of chemical structure of the composites were investigated by Attenuated total reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR and Solid state 13C Nuclear Magnetic Resonance spectroscopy (NMR analyses. The results revealed the chemical reactions that occurred between the coupling agents and raw materials, which thus contributed to the enhancement of compatibility and interfacial adhesion between the constituents of WPC. NMR results also indicated that there existed the transformation of crystalline cellulose to an amorphous state during the coupling agent treatments, reflecting the inferior resonance of crystalline carbohydrates. Fluorescence Microscope (FM and Scanning Electron Microscope (SEM analyses showed the improvements of wood particle dispersion and wettability, compatibility of the constituents, and resin penetration, and impregnation of the composites after the coupling agent treatments. The optimised interface of the composites was attributed to interdiffusion, electrostatic adhesion, chemical reactions, and mechanical interlocking bonding mechanisms.

  8. Influence of different bonding agents on marginal sealing quality of amalgam restorations

    Directory of Open Access Journals (Sweden)

    Melih Irena

    2011-01-01

    Full Text Available Introduction. Although advanced adhesive systems are in use, marginal microleakage is one of the greatest problems of contemporary restorative dentistry. Objective. The aim of this in vitro study was to evaluate the influence of different bonding agents on the marginal sealing quality of class II amalgam restorations. Methods. Forty freshly extracted human premolar and molar teeth were divided into four groups with 10 teeth in each one. Class II preparations were prepared and different adhesives were applied as follows: group I - Amalgam Liner® (Voco; group II - ONE-STEP® PLUS (Bisco; group III - PQ 1 (Ultradent. Group IV was used as a control, without any bonding agent. Amalgam (Cavex Non Gamma 2, Cavex was hand-condensed into each preparation. Specimens were thermocycled 200 times at the following temperatures: 5-7°C, 37°C and 57-59°C, and were then immersed into 1% solution of gentian violet for 72 hours. The teeth were sectioned longitudinally and microleakage was graded in the area of the gingival and occlusal quantity rim using a binocular magnifying glass with 25 times magnification. Results. The highest microleakage was recorded in the Amalgam Liner group; 1526.0 μm at the gingival wall and 694.5 μm at the occlusal cavity wall. The lowest dye penetration was observed in the PQ1 group; 589.5 μm at the gingival wall, and 599.9 μm at the occlusal wall of the restoration. ANOVA test showed that there was a statistically significant difference of dye penetration values at the gingival wall among all examination groups (p<0.01. No statistically significant differences were found comparing microleakage values at the occlusal wall. Conclusion. Results of this study showed that the best marginal sealing was accomplished by using the PQ1 bonding agent.

  9. A comparative evaluation of the shear bond strength of five different orthodontic bonding agents polymerized using halogen and light-emitting diode curing lights: An in vitro investigation

    Directory of Open Access Journals (Sweden)

    Sujoy Banerjee

    2011-01-01

    Full Text Available Purpose: With the introduction of photosensitive (light-activated restorative materials in orthodontics, various methods have been suggested to enhance the polymerization of the materials used, including use of more powerful light curing devices. Bond strength is an important property and determines the amount of force delivered and the treatment duration. Many light-cured bonding materials have become popular but it is the need of the hour to determine the bonding agent that is the most efficient and has the desired bond strength. Aim: To evaluate and compare the shear bond strengths of five different orthodontic light cure bonding materials cured with traditional halogen light and low-intensity light-emitting diode (LED light curing unit. Materials and Methods: 100 human maxillary premolar teeth, extracted for orthodontic purpose, were used to prepare the samples. 100 maxillary stainless steel bicuspid brackets of 0.018 slot of Roth prescription, manufactured by D-tech Company, were bonded to the prepared tooth surfaces of the mounted samples using five different orthodontic bracket bonding light-cured materials, namely, Enlight, Fuji Ortho LC (resin-modified glass ionomer cement, Orthobond LC, Relybond, and Transbond XT. The bond strength was tested on an Instron Universal testing machine (model no. 5582. Results: In Group 1 (halogen group, Enlight showed the highest shear bond strength (16.4 MPa and Fuji Ortho LC showed the least bond strength (6.59 MPa (P value 0.000. In Group 2 (LED group, Transbond showed the highest mean shear bond strength (14.6 MPa and Orthobond LC showed the least mean shear bond strength (6.27 MPa (P value 0.000. There was no statistically significant difference in the shear bond strength values of all samples cured using either halogen (mean 11.49 MPa or LED (mean 11.20 MPa, as the P value was 0.713. Conclusion: Polymerization with both halogen and LED resulted in shear bond strength values which were above the

  10. Evaluation of Different Dentin Bonding Agents Accompanied with Composite Coronal Barrier

    Directory of Open Access Journals (Sweden)

    Zahed Mohammadi

    2015-06-01

    Full Text Available Introduction: The purpose of this study was to evaluate the sealing ability of dentin bonding agents in root canals obturated with gutta-percha and MTA. Methods: Forty-five single rooted human premolar teeth were decoronated so that remaining root portions were 12 mm in length. The samples were divided randomly into three experimental (n=13 and two control groups (n=3. All teeth were instrumented up to #40 K-file using step-back technique. The roots were obturated with gutta-percha/AH26 and MTA for 5 and 3 mm, respectively. Excite, Clearfil SE Bond, and iBond were applied for experimental groups and then 2mm was filled with composite Filtek Z250. The roots in the controls were merely instrumented and obturated. Two coats of nail varnish were applied on the surface of the teeth in the experimental and positive groups, except 2 mm around the apical foramen and coronal surfaces. In the negative control, the surfaces were completely covered by two layers of nail varnish. After thermocycling, the roots mounted in plastic caps of tubes containing BHI medium and inoculated coronally with Enterococcus faecalis. The data were statistically analyzed using Fisher's exact and Kaplan-Meier survival Analysis. Results: There were no statistically significant differences between three experimental groups regarding the leakage rate (P=0.738. Conclusion: Within the limitations of this study, it was observed that the adhesive systems in alliance with gutta-percha and MTA obturation could not entirely

  11. Decalcification prevention around orthodontic brackets bonded to bleached enamel using different topical agents.

    Science.gov (United States)

    Msallam, Ferial Ahmed; Grawish, Mohammed El-Awady; Hafez, Ahmad Mohammed; Abdelnaby, Yasser Lotfy

    2017-12-01

    The present study was conducted to evaluate the effect of different topical agents utilized for prevention of enamel decalcification around orthodontic brackets bonded to bleached and non-bleached enamel. Human maxillary premolars (n = 120) were divided into two equal groups. Teeth in group I were left without bleaching while those in group II were bleached with Vivastyle gel. Metal brackets were bonded to all the teeth using light-cured adhesive. Each group was divided into six equal subgroups (A, B, C, D, E, and F). In subgroup A, no material was applied (control). In subgroups B, C, D, E, and F, the following materials were applied respectively: Profluorid varnish, Enamel Pro Varnish, Ortho-Choice Ortho-Coat, GC Tooth Mousse, and GC MI Paste Plus. All teeth were cycled in a demineralization solution/artificial saliva for 15 days. Laser fluorescence was used to measure the level of enamel mineralization. The data were statistically analyzed. Regarding the non-bleaching subgroups, all studied material revealed significant demineralization reduction in comparison to the control subgroup (P  0.05). Ortho-Choice Ortho-Coat, and Profluorid and Enamel Pro varnishes could be utilized successfully to reduce enamel demineralization around brackets bonded to either bleached or non-bleached enamel. GC MI Paste Plus and GC Tooth Mousse were effective only in non-bleached enamel.

  12. Effect of antioxidant agents on bond strength of composite to bleached enamel with 38% hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Juliane Marcela Guimaraes da Silva

    2011-01-01

    Full Text Available This study evaluated the effect of antioxidant agents on microtensile bond strengths (mTBS of composite to bleached enamel. Fifteen freshly extracted human third molars were selected and randomly assigned to 6 groups (n = 5: (NB enamel not bleached, (B bleached enamel, (BR7 bleached enamel and restored 7 days later, (BSA bleached enamel+sodium ascorbate, (BMC bleached enamel+malvidin chloride, (BPC bleached enamel+pelargonidin chloride. The groups were bleached with 38% hydrogen peroxide (HP - Opalescence Xtra Boost and restored with Single Bond+Filtek Z350. The specimens were thermocycled and submitted to a microtensile load at 1 mm/min crosshead speed. The data were evaluated by ANOVA and Tukey test at 5% of significance. The mean and standard-deviation for all groups were: NB: 30.95(±11.97a; BSA: 30.34(±8.73a, BPC: 22.81(6.00b, BR7: 21.41(±6.12b, B: 14.10(±4.45c, BMC: 13.25(±6.02c. Sodium ascorbate reversed the bond strengths to enamel immediately after bleaching.

  13. Influence of ceramic thickness and type on micromechanical properties of light-cured adhesive bonding agents.

    Science.gov (United States)

    Öztürk, Elif; Bolay, Sükran; Hickel, Reinhard; Ilie, Nicoleta

    2014-10-01

    The aim of this study was to evaluate the micromechanical properties of different adhesive bonding agents when polymerized through ceramics. Sixty sound extracted human third molars were selected and the crowns were sectioned perpendicular to the long axis in order to obtain dentin slices to be bonded with one of the following adhesives: Syntac/Heliobond (Ivoclar-Vivadent) or Adper-Scotchbond-1XT (3M-ESPE). The adhesives were cured by using a LED-unit (Bluephase®, Ivoclar Vivadent) with three different curing times (10 s, 20 s and 30 s) under two ceramics (IPS-e.max-Press, Ivoclar-Vivadent; IPS-Empress®CAD, Ivoclar-Vivadent) of different thicknesses (0 mm, 0.75 mm, 2 mm). Thirty groups were included, each containing 60 measurements. Micromechanical properties (Hardness, HV; indentation modulus, E; and creep, Cr) of the adhesives were measured with an automatic microhardness indenter (Fisherscope H100C, Germany). Data were statistically analyzed by using one-way ANOVA and Tukey's post-hoc test, as well as a multivariate analysis to test the influence of the study parameters (SPSS 18.0). Significant differences were observed between the micromechanical properties of the adhesives (p ceramic type showed the highest effect on HV (Partial-eta squared (η(2)) = 0.109) of the tested adhesives, while E (η(2) = 0.275) and Cr (η(2) = 0.194) were stronger influenced by the adhesive type. Ceramic thickness showed no effect on the E and Cr of the adhesives. The adhesive bonding agents used in this study performed well by curing through different thicknesses of ceramics. The micromechanical properties of the adhesives were determined by the adhesive type and were less influenced by ceramic type and curing time.

  14. Microshear Bond Strength of OptiBond All-in-One Self-adhesive Agent to Er:YAG Laser Treated Enamel After Thermocycling and Water Storage.

    Science.gov (United States)

    Kasraei, Shahin; Yarmohammadi, Ebrahim; Ghazizadeh, Mohammad Vahid

    2016-01-01

    Introduction: This study aimed to compare the microshear bond strength of composite to enamel treated with Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser using a self-etch one step bonding agent. Methods: Seventy-six enamel surfaces were prepared from 38 sound human third molar teeth. Specimens were randomly divided into four groups of 18. The enamel surface in half the specimens was irradiated with Er:YAG laser. One extra specimen from each group was evaluated under a scanning electron microscope (SEM). Composite micro-cylinders were bonded to the specimen surfaces using OptiBond All-In-One (OB) adhesive agent and stored in distilled water for 24 hours. Half the specimens were thermocycled (2000 cycles) and stored in distilled water at 37°C for three months (TW). The microshear bond strength of composite to enamel was measured using a universal testing machine at a crosshead speed of 1 mm/min. The fractured surfaces were evaluated under a stereomicroscope at ×40 magnification to determine the mode of failure. Data were analyzed using repeated measures analysis of variance (ANOVA) and t test. Results: The mean values (±standard deviation) were 17.96 ± 2.92 MPa in OB group, 22.29 ± 4.25 MPa in laser + OB group, 18.11 ± 3.52 MPa in laser + OB + TW group and 9.42 ± 2.47 MPa in OB + TW group. Repeated measures ANOVA showed that laser irradiation increased the microshear bond strength ( P Enamel surface preparation with Er:YAG laser is recommended to enhance the durability of the bond of self-etch bonding systems to enamel.

  15. Efficacy of antimicrobial agents incorporated in orthodontic bonding systems: a systematic review and meta-analysis.

    Science.gov (United States)

    de Almeida, C M; da Rosa, W L O; Meereis, C T W; de Almeida, S M; Ribeiro, J S; da Silva, A F; Lund, Rafael Guerra

    2018-03-05

    The purpose of this study was to evaluate the efficacy of orthodontic bonding systems containing different antimicrobial agents, as well as the influence of antimicrobial agent incorporation in the bonding properties of these materials. Eight databases were searched: PubMed (Medline), Web of Science, Scopus, Lilacs, Ibecs, BBO, Scielo and Google Scholar. Any study that evaluated antimicrobial activity in experimental or commercial orthodontic bonding systems was included. Data were tabulated independently and in duplicated by two authors on pre-designed data collection form. The global analysis was carried out using a random-effects model, and pooled-effect estimates were obtained by comparing the standardised mean difference of each antimicrobial orthodontic adhesive with the respective control group. A p-value orthodontic bonding systems. The antimicrobial agent incorporation in orthodontic bonding systems showed higher antimicrobial activity than the control group in agar diffusion (overall standardised mean difference: 3.71; 95% CI 2.98 to 4.43) and optical density tests (0.41; 95% CI -0.05 to 0.86) (p orthodontic bonding systems were statistically similar to the control. Although there is evidence of antibacterial activity from in vitro studies, clinical and long-term studies are still necessary to confirm the effectiveness of antibacterial orthodontic bonding systems in preventing caries disease.

  16. Assessment of covalent bond formation between coupling agents and wood by FTIR spectroscopy and pull strength tests

    DEFF Research Database (Denmark)

    Rasmussen, Jonas Stensgaard; Barsberg, Søren Talbro; Venås, Thomas Mark

    2014-01-01

    In the focus was the question whether metal alkoxide coupling agents – titanium, silane, and zirconium – form covalent bonds to wood and how they improve coating adhesion. In a previous work, a downshift of the lignin infrared (IR) band ∼1600 cm-1 was shown to be consistent with the formation...... of ether linkages between lignin and titanium coupling agent. In the present work, changes were found in the attenuated total reflectance-Fourier transform IR (ATR-FTIR) spectra of lignin and wood mixed with silane, and titanium coupling agents, and to a lesser extent for a zirconium coupling agent...

  17. Effects of drying agents on bond strength of etch-and-rinse adhesive systems to enamel immediately after bleaching.

    Science.gov (United States)

    Niat, Alireza Boruzi; Yazdi, Fatmeh Maleknejad; Koohestanian, Niloufar

    2012-12-01

    To determine the effect of drying agents and adhesive solvents on the bond strength of resin composite to enamel immediately after bleaching. Sixty healthy human premolars were bleached using 15% carbamide peroxide gel and randomly divided into three groups according to the immersing solutions applied immediately after bleaching: 70% alcohol, acetone, and distilled water. Each group was randomly divided into two subgroups according to the adhesives that were applied: an alcohol-based adhesive (Single Bond) and an acetone-based adhesive (One Step). By using rubber washers, composite Z100 was placed onto the enamel and shear bond strength was evaluated in a universal testing machine at a crosshead speed of 1 mm/min. The type of failure was also assessed using a stereomicroscope. The data were statistically analyzed by two-way ANOVA and Tukey's post-hoc test (α = 0.05). Fisher's Exact test was used to evaluate differences in the failure modes. Statistical analysis showed that the bond strength of the distilled water groups was significantly lower than that of the other groups, but the bond strengths of the two groups where a drying agent was applied were similar to that of the unbleached group. The acetone-based adhesive (One Step) provided higher bond strength than did the alcohol-based adhesive (Single Bond) (p 0.05). Fisher's Exact test showed there was no significant difference in the failure mode of all the experimental groups (p > 0.05). The application of drying agents improves the bond strength of resin composite to bleached enamel. Furthermore, the acetone-based adhesive used in the study had a higher bond strength to bleached enamel than did the alcohol-based adhesive used.

  18. Effect of a bonding agent on in vitro biochemical activities of remineralizing resin-based calcium phosphate cements.

    Science.gov (United States)

    Dickens, Sabine H; Flaim, Glenn M

    2008-09-01

    To test whether fluoride in a resin-based Ca-PO4 ion releasing cement or coating with an acidic bonding agent for improved adhesion compromised the cement remineralization potential. Cements were formulated without fluoride (Cement A) or with fluoride (Cement B). The treatment groups were A=Cement A; A2=Cement A+bonding agent; B=Cement B; B2=Cement B+bonding agent. The calcium, phosphate, and fluoride ion release in saliva-like solution (SLS) was determined from hardened cement disks without or with a coating of bonding agent. For the remineralization, two cavities were prepared in dentin of extracted human molars and demineralized. One cavity received composite resin (control); the other received treatment A, A2, B or B2. After 6 week incubation in SLS, 180 microm cross-sections were cut. The percentage remineralization was determined by transverse microradiography comparing the dentin mineral density under the cement to that under the control. The percentage of remineralization (mean+/-S.D.) was A (39+/-14)=B (37+/-18), A2 (23+/-13), B2 (14+/-7). Two-way analysis of variance (ANOVA) and Holm-Sidak test showed a significant effect from the presence of bonding agent (p0.05). The ion solution concentrations of all groups showed undersaturation with respect to dicalcium phosphate dihydrate and calcium fluoride and supersaturation for fluorapatite and hydroxyapatite suggesting a positive remineralization potential. Compared to the control all treatments resulted in mineral increase. The remineralization was negatively affected by the presence of the bonding agent.

  19. A Comparative Evaluation of the Effect of Bonding Agent on the Tensile Bond Strength of Two Pit and Fissure Sealants Using Invasive and Non-invasive Techniques: An in-vitro Study.

    Science.gov (United States)

    Singh, Shamsher; Adlakha, Vivek; Babaji, Prashant; Chandna, Preetika; Thomas, Abi M; Chopra, Saroj

    2013-10-01

    Newer technologies and the development of pit and fissure sealants have shifted the treatment philosophy from 'drill and fill' to that of 'seal and heal'. The purpose of this in-vitro study was to evaluate the effects of bonding agents on the tensile bond strengths of two pit and fissure sealants by using invasive and non-invasive techniques. One hundred and twenty bicuspids were collected and teeth were divided into two groups: Group-I (Clinpro) and Group-II (Conseal f) with 60 teeth in each group. For evaluating tensile bond strengths, occlusal surfaces of all the teeth were flattened by reducing buccal and lingual cusps without disturbing fissures. Standardised polyvinyl tube was bonded to occlusal surfaces with respective materials. Sealants were applied, with or without bonding agents, in increments and they were light cured. Tensile bond strengths were determined by using Universal Testing Machine. Data were then statistically analysed by using Student t-test for comparison. A statistically significant difference was found in tensile bond strength in invasive with bonding agent group than in non-invasive with bonding agent group. This study revealed that invasive techniques increase the tensile bond strengths of sealants as compared to non- invasive techniques and that the use of a bonding agent as an intermediate layer between the tooth and fissure sealant is beneficial for increasing the bond strength.

  20. Bond strength of three luting agents to zirconia ceramic - influence of surface treatment and thermocycling

    Directory of Open Access Journals (Sweden)

    Ahmed Attia

    2011-08-01

    Full Text Available OBJECTIVE: This in vitro study aimed to evaluate the influence of different surface treatments, 3 luting agents and thermocycling on microtensile bond strength (µTBS to zirconia ceramic. Material and METHODS: A total of 18 blocks (5x5x4 mm were fabricated from zirconia ceramic (ICE Zirkonia and duplicated into composite blocks (Alphadent. Ceramic blocks were divided into 3 groups (n=6 according to the following surface treatments: airborne-particle abrasion (AA, silica-coating, (SC (CoJet and silica coating followed by silane application (SCSI (ESPE Sil. Each group was divided into 3 subgroups (n=2 according to the 3 luting agents used. Resin-modified glass-ionomer cement (RMGIC, Ketac Cem Plus, self-adhesive resin cement (UN, RelyX Unicem and adhesive resin cement (ML, MultiLink Automix were used for bonding composite and zirconia blocks. Each bonding assembly was cut into microbars (10 mm long and 1±0.1 mm². Seven specimens of each subgroup were stored in water bath at 37ºC for 1 week. The other 7 specimens were stored in water bath at 37ºC for 30 days then thermocycled (TC for 7,500 cycles. µTBS values were recorded for each specimen using a universal testing machine. Statistical analyses were performed using a 3-way ANOVA model followed by serial 1-way ANOVAs. Comparison of means was performed with Tukey's HSD test at (α=0.05. RESULTS: µTBS ranged from 16.8 to 31.8 MPa after 1 week and from 7.3 to 16.4 MPa after 30 days of storage in water and thermocycling. Artificial aging significantly decreased µTBS (p<0.05. Considering surface treatment, SCSI significantly increased µTBS (p<0.05 compared to SC and AA. Resin cements (UN and ML demonstrated significantly higher µTBS (p<0.05 compared to RMGIC cement. CONCLUSIONS: Silica coating followed by silane application together with adhesive resin cements significantly increased µTBS, while thermocycling significantly decreased µTBS.

  1. The Effect of Food-Simulating Agents on the Bond Strength of Hard Chairside Reline Materials to Denture Base Resin.

    Science.gov (United States)

    Fatemi, Farzaneh Sadat; Vojdani, Mahroo; Khaledi, Amir Ali Reza

    2018-06-08

    To investigate the influence of food-simulating agents on the shear bond strength between direct hard liners and denture base acrylic resin. In addition, mode of failure was evaluated. One hundred fifty cylindrical columns of denture base resin were fabricated and bonded to three types of hard reline materials (Hard GC Reline, Tokuyama Rebase II Fast, TDV Cold Liner Rebase). Specimens of each reline material were divided into five groups (n = 10) to undergo 12-day immersion in distilled water, 0.02 N citric acid aqueous solution, heptane, and 40% ethanol/water solution at 37°C. The control group was not immersed in any solution. The shear bond strength test was performed, and the failure mode was determined. Statistics were analyzed with two-way ANOVA and chi-square test (α = 0.05). Significant interaction was found between the hard liners and food simulating agents (p < 0.001). The shear bond strength of Tokuyama in 40% ethanol and TDV in heptane decreased significantly (p = 0.001, p < 0.001 respectively); however, none of the solutions could significantly affect the shear bond strength of Hard GC Reline (p = 0.208). The mixed failure mode occurred more frequently in Hard GC Reline compared with the other liners (p < 0.001) and was predominant in specimens with higher bond strength values (p = 0.012). Food simulating agents did not adversely affect the shear bond strength of Hard GC Reline; however, ethanol and heptane decreased the bond strength of Tokuyama and TDV, respectively. These findings may provide support to dentists to recommend restricted consumption of some foods and beverages for patients who have to use dentures relined with certain hard liners. © 2018 by the American College of Prosthodontists.

  2. Role of bulking agents in bladder exstrophyepispadias complexes ...

    African Journals Online (AJOL)

    Background: Role of pelvic osteotomy in surgical management of bladder exstrophy is controversial But pelvic rim closure importantly. Bulking agents have been used for perineal and pelvic dysfunction in adults. In this study, bladder extrophy repair was performed without pubic closure And bulking agent injections were ...

  3. Effects of contamination by either blood or a hemostatic agent on the shear bond strength of orthodontic buttons

    Science.gov (United States)

    Alkis, Huseyin; Turkkahraman, Hakan

    2013-01-01

    Objective To evaluate the effects of contamination by either blood or a hemostatic agent on the shear bond strength (SBS) of orthodontic buttons. Methods We used 45 freshly extracted, non-carious, impacted third molars that were divided into 3 groups of 15. Each tooth was etched with 37% phosphoric acid gel for 30 s. Human blood or the blood stopper agent was applied to the tooth surface in groups I and II, respectively. Group III teeth were untreated (controls). Orthodontic buttons were bonded to the teeth using light-curing composite resin. After bonding, the SBS of the button was determined using a Universal testing machine. Any adhesive remaining after debonding was assessed and scored according to the modified adhesive remnant index (ARI). ANOVA with post-hoc Tukey's test was used to determine significant differences in SBS and Fisher's exact test, to determine significant differences in ARI scores among groups. Results ANOVA indicated a significant difference between groups (p Contamination of tooth surfaces with either blood or hemostatic agent significantly decreased the SBS of orthodontic buttons. When the contamination risk is high, it is recommended to use the blood stopper agent when bonding orthodontic buttons on impacted teeth. PMID:23671834

  4. Influence of surface conditions and silane agent on the bond of resin to IPS Empress 2 ceramic.

    Science.gov (United States)

    Spohr, Ana Maria; Sobrinho, Lourenço Correr; Consani, Simonides; Sinhoreti, Mario Alexandre Coelho; Knowles, Jonathan C

    2003-01-01

    The aim of this study was to evaluate the effect of different ceramic surface treatments on the tensile bond strength between IPS Empress 2 ceramic framework and Rely X adhesive resin cement, with or without the application of a silane coupling agent. One hundred twenty disks were made, embedded in resin, and randomly divided into six groups: group 1 = sandblasting (100 microm), no silanation; group 2 = sandblasting (100 microm), silane treatment; group 3 = sandblasting (50 microm), no silanation; group 4 = sandblasting (50 microm), silane treatment; group 5 = hydrofluoric acid etching, no silanation; and group 6 = hydrofluoric acid etching, silane treatment. The disks were bonded into pairs with adhesive resin cement. All samples were stored in distilled water at 37 degrees C for 24 hours and then thermocycled. The samples were submitted to tensile testing. The use of silane improved the bond strength in relation to the groups in which silane was not applied (P Empress 2 ceramic framework and resin agent.

  5. 211 At-labeled agents for alpha-immunotherapy: On the in vivo stability of astatine-agent bonds

    OpenAIRE

    Ayed , Tahra ,; Pilmé , Julien; Tézé , David; Bassal , Fadel ,; Barbet , Jacques ,; Chérel , Michel; Champion , Julie ,; Maurice , Rémi; Montavon , Gilles ,; Galland , Nicolas ,

    2016-01-01

    International audience; The application of 211 At to targeted cancer therapy is currently hindered by the rapid deastatination that occurs in vivo. As the deastatination mechanism is unknown, we tackled this issue from the viewpoint of the intrinsic properties of At-involving chemical bonds. An apparent correlation has been evidenced between in vivo stability of 211 At-labeled compounds and the AtÀR (R ¼ C, B) bond enthalpies obtained from relativistic quantum mechanical calculations. Further...

  6. Role of interatomic bonding in the mechanical anisotropy and interlayer cohesion of CSH crystals

    Energy Technology Data Exchange (ETDEWEB)

    Dharmawardhana, C.C. [Department of Physics and Astronomy, University of Missouri—Kansas City, Kansas City, MO 64110 (United States); Misra, A. [Department of Civil, Environmental, and Architectural Engineering, University of Kansas, Lawrence, KS 66045 (United States); Aryal, S.; Rulis, P. [Department of Physics and Astronomy, University of Missouri—Kansas City, Kansas City, MO 64110 (United States); Ching, W.Y., E-mail: ccdxz8@mail.umkc.edu [Department of Physics and Astronomy, University of Missouri—Kansas City, Kansas City, MO 64110 (United States)

    2013-10-15

    Atomic scale properties of calcium silicate hydrate (CSH), the main binding phase of hardened Portland cement, are not well understood. Over a century of intense research has identified almost 50 different crystalline CSH minerals which are mainly categorized by their Ca/Si ratio. The electronic structure and interatomic bonding in four major CSH crystalline phases with structures close to those found in hardened cement are investigated via ab initio methods. Our result reveals the critical role of hydrogen bonding and importance of specifying precise locations for water molecules. Quantitative analysis of contributions from different bond types to the overall cohesion shows that while the Si-O covalent bonds dominate, the hydrogen bonding and Ca-O bonding are also very significant. Calculated results reveal the correlation between bond topology and interlayer cohesion. The overall bond order density (BOD) is found to be a more critical measure than the Ca/Si ratio in classifying different CSH crystals.

  7. Do blood contamination and haemostatic agents affect microtensile bond strength of dual cured resin cement to dentin?

    Directory of Open Access Journals (Sweden)

    Kerem KiLiC

    2013-01-01

    Full Text Available Objective The purpose of this study was to evaluate the effects of blood contamination and haemostatic agents such as Ankaferd Blood Stopper (ABS and hydrogen peroxide (H2O2 on the microtensile bond strength between dual cured resin cement-dentin interface. Material and Methods Twelve pressed lithium disilicate glass ceramics were luted to flat occlusal dentin surfaces with Panavia F under the following conditions: Control Group: no contamination, Group Blood: blood contamination, Group ABS: ABS contamination Group H2O2: H2O2 contamination. The specimens were sectioned to the beams and microtensile testing was carried out. Failure modes were classified under stereomicroscope. Two specimens were randomly selected from each group, and SEM analyses were performed. Results There were significant differences in microtensile bond strengths (µTBS between the control and blood-contaminated groups (p0.05. Conclusions Contamination by blood of dentin surface prior to bonding reduced the bond strength between resin cement and the dentin. Ankaferd Blood Stoper and H2O2 could be used safely as blood stopping agents during cementation of all-ceramics to dentin to prevent bond failure due to blood contamination.

  8. Bonding properties of acrylonitrile butadiene rubber with polyamide mediated by a functional layer of silane coupling agent

    International Nuclear Information System (INIS)

    Sang, J.; Aisawa, S.; Hirahara, H.; Mori, K.

    2017-01-01

    This study demonstrates that coating layers, expected to be formed as self-assembled monolayers, of silane coupling agents can act as adhesion layers as the hydrogenated acrylonitrile butadiene rubber (HNBR) and polyamide (PA6) plate interfaces. The resulting PA6/HNBR joints showed excellent adhesion properties with cohesive failure and the interfaces were jointed through chemical bonds, which were confirmed by swelling tests. The surfaces and bonding properties of rubber and PA6 were studied by means of peel tests, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and nanoscale infrared microscopy and chemical imaging (AFM-IR). (authors)

  9. Poly (amido amine) and nano-calcium phosphate bonding agent to remineralize tooth dentin in cyclic artificial saliva/lactic acid

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Kunneng [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Weir, Michael D.; Reynolds, Mark A. [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Zhou, Xuedong [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Li, Jiyao, E-mail: jiyaoliscu@163.com [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Xu, Hockin H.K., E-mail: hxu@umaryland.edu [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD 21201 (United States); Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore County, MD 21250 (United States)

    2017-03-01

    The objectives of this study were to develop a novel method to remineralize dentin lesions, and investigate the remineralization effects of poly (amido amine) (PAMAM) dendrimer plus a bonding agent with nanoparticles of amorphous calcium phosphate (NACP) in a cyclic artificial saliva/lactic acid environment for the first time. Dentin lesions were produced via phosphoric acid. Four groups were tested: (1) dentin control, (2) dentin with PAMAM, (3) dentin with NACP bonding agent, and (4) dentin with PAMAM plus NACP bonding agent. Specimens were treated with cyclic artificial saliva/lactic acid. The remineralized dentin was examined using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), hardness and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). NACP bonding agent yielded a dentin shear bond strength similar to commercial controls (Prime & Bond NT, Dentsply; Scotchbond Multi-purpose, 3M) (p > 0.1). Increasing NACP in bonding agent from 0 to 40% did not affect bond strength. NACP bonding agent neutralized the acid and released Ca ions with concentrations of 4 to 20 mmol/L, and P ions of 2 to 9 mmol/L. PAMAM or NACP bonding agent alone achieved slight remineralization. The PAMAM + NACP group achieved the greatest dentin remineralization p < 0.05). At 20 days, PAMAM + NACP increased the hardness of pre-demineralized dentin to reach the normal dentin hardness (p > 0.1). In conclusion, superior remineralization of PAMAM + NACP bonding agent was demonstrated for the first time. PAMAM + NACP bonding agent induced dentin remineralization under acid challenge, when conventional remineralization methods such as PAMAM alone did not work well. The novel PAMAM + NACP bonding agent method is promising to improve the longevity of resin-dentin bonds, inhibit caries, and protect teeth. - Highlights: • PAMAM induced moderate remineralization for dentin in artificial saliva/lactic acid. • Acid challenge reduced the

  10. Poly (amido amine) and nano-calcium phosphate bonding agent to remineralize tooth dentin in cyclic artificial saliva/lactic acid

    International Nuclear Information System (INIS)

    Liang, Kunneng; Weir, Michael D.; Reynolds, Mark A.; Zhou, Xuedong; Li, Jiyao; Xu, Hockin H.K.

    2017-01-01

    The objectives of this study were to develop a novel method to remineralize dentin lesions, and investigate the remineralization effects of poly (amido amine) (PAMAM) dendrimer plus a bonding agent with nanoparticles of amorphous calcium phosphate (NACP) in a cyclic artificial saliva/lactic acid environment for the first time. Dentin lesions were produced via phosphoric acid. Four groups were tested: (1) dentin control, (2) dentin with PAMAM, (3) dentin with NACP bonding agent, and (4) dentin with PAMAM plus NACP bonding agent. Specimens were treated with cyclic artificial saliva/lactic acid. The remineralized dentin was examined using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), hardness and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). NACP bonding agent yielded a dentin shear bond strength similar to commercial controls (Prime & Bond NT, Dentsply; Scotchbond Multi-purpose, 3M) (p > 0.1). Increasing NACP in bonding agent from 0 to 40% did not affect bond strength. NACP bonding agent neutralized the acid and released Ca ions with concentrations of 4 to 20 mmol/L, and P ions of 2 to 9 mmol/L. PAMAM or NACP bonding agent alone achieved slight remineralization. The PAMAM + NACP group achieved the greatest dentin remineralization p < 0.05). At 20 days, PAMAM + NACP increased the hardness of pre-demineralized dentin to reach the normal dentin hardness (p > 0.1). In conclusion, superior remineralization of PAMAM + NACP bonding agent was demonstrated for the first time. PAMAM + NACP bonding agent induced dentin remineralization under acid challenge, when conventional remineralization methods such as PAMAM alone did not work well. The novel PAMAM + NACP bonding agent method is promising to improve the longevity of resin-dentin bonds, inhibit caries, and protect teeth. - Highlights: • PAMAM induced moderate remineralization for dentin in artificial saliva/lactic acid. • Acid challenge reduced the

  11. In vitro antibacterial and cytotoxicity assessments of an orthodontic bonding agent containing benzalkonium chloride.

    Science.gov (United States)

    Saito, Kayo; Hayakawa, Tohru; Kawabata, Rihito; Meguro, Daijiro; Kasai, Kazutaka

    2009-03-01

    To assess the antibacterial activity and cytotoxicity of an orthodontic bonding material containing an antibacterial agent. Superbond C&B (4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane [4-META/MMA-TBB]) resin was mixed with benzalkonium chloride (BAC) to obtain final BAC concentrations of 0.25%, 0.75%, 1.25%, 1.75%, 2.5%, and 5.0% (wt/ wt). Antibacterial activity against Streptococcus mutans and Streptococcus sobrinus was evaluated by soaking the BAC-resin in distilled water at 37 degrees C for periods of 30, 90, and 180 days. Antibacterial activity of the BAC-resin was measured by the disk diffusion method, and the inhibition zone around each sample was measured and recorded. For evaluation of cytotoxicity, BAC-resin samples were put into cell culture inserts placed above human gingival cells and were incubated at 37 degrees C for 1, 3, and 6 days. Cytotoxicity was assessed with a tetrazolium bromide reduction assay. The antibacterial activity of BAC-incorporated resin samples decreased significantly after immersion in water for 180 days, regardless of BAC concentration. The antibacterial activity of nonimmersed resin containing 0.25% or 1.75% BAC was comparable with that of 5.0% BAC-resin immersed for 180 days. In cytotoxicity tests, most cells died when exposed to resins containing 1.75%, 2.5%, and 5% BAC. No difference was observed between resins containing 0.25% and 0.75% BAC at 1, 3, and 6 days of culture. The addition of BAC to 4-META/MMA-TBB resin confers an antibacterial effect even after immersion in water, and 4-META/MMA-TBB resin containing 0.25% to 0.75% BAC has no significant cytotoxic effect.

  12. A role based coordination model in agent systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ya-ying; YOU Jin-yuan

    2005-01-01

    Coordination technology addresses the construction of open, flexible systems from active and independent software agents in concurrent and distributed systems. In most open distributed applications, multiple agents need interaction and communication to achieve their overall goal. Coordination technologies for the Internet typically are concerned with enabling interaction among agents and helping them cooperate with each other.At the same time, access control should also be considered to constrain interaction to make it harmless. Access control should be regarded as the security counterpart of coordination. At present, the combination of coordination and access control remains an open problem. Thus, we propose a role based coordination model with policy enforcement in agent application systems. In this model, coordination is combined with access control so as to fully characterize the interactions in agent systems. A set of agents interacting with each other for a common global system task constitutes a coordination group. Role based access control is applied in this model to prevent unauthorized accesses. Coordination policy is enforced in a distributed manner so that the model can be applied to the open distributed systems such as Intemet. An Internet online auction system is presented as a case study to illustrate the proposed coordination model and finally the performance analysis of the model is introduced.

  13. The Role of a Corporate Bond Market in an Economy -- and in Avoiding Crises

    OpenAIRE

    Hakansson, Nils H.

    1999-01-01

    While much attention has been focused on the optimal ratio of a firm's debt to equity, the "optimal" or best balance between bond financing and (longer-term) bank financing has scarcely been addressed. This essay examines the principal differences between an economy with a well-developed corporate bond market free from government interference and an economy in which bank financing plays a central role (as in East Asia). When a full-fledged corporate bond market is present, market forces hav...

  14. Soil aggregate formation: the role of wetting-drying cycles in the genesis of interparticle bonding

    Science.gov (United States)

    Albalasmeh, Ammar; Ghezzehei, Teamrat

    2013-04-01

    Soil structure influences many soil properties including aeration, water retention, drainage, bulk density, and resistance to erosion and indirectly influences most biological and chemical processes that occur in and around soil. In nature, soil is continually exposed to wetting (e.g., rainfall and diffusive flow) and drying (e.g., evaporation, diffusive flow and plant uptake). These natural wetting and drying cycles of soils are physical events that profoundly affect the development of soil structure, aggregate stability, carbon (C) flux and mineralization. We hypothesize that drying of capillary water transports suspended and/or dissolved cementing agents toward inter-particle contacts and eventually deposits part of the colloidal mass forming inter-particle bonds. Here, we will show the role of wetting and drying cycles on soil aggregation and stabilization and how these cycles transport and deposit organic cementing agents at the inter-particle contact. We found that aggregates of sand and silt particles can be formed by subjecting loose particles to wetting-drying cycles in the presence of dilute solutions of organic matter that mimic root or microbial exudates. Moreover, majority of the organic matter was deposited in the contact region between the sand particles, where the water accumulates during drying. The model predictions and aggregate stability measurements are supported by scanning electron micrographs that clearly show the process of aggregate formation.

  15. Evaluating the effect of antioxidant agents on shear bond strength of tooth-colored restorative materials after bleaching: A systematic review.

    Science.gov (United States)

    Feiz, Atiyeh; Mosleh, Hamid; Nazeri, Rahman

    2017-07-01

    The main objective of the present study was to make a systematic review of how antioxidant agents affect shear bond strength of tooth-colored restorative materials after bleaching. Electronic search was used to extract the related articles on the targeted key words such as "antioxidant", "dental bleaching" and "shear bond strength" (SBS) from MeSH, PubMed, Medline, and Cochrane electronic data bases. These articles were all published before 2016. Inclusion criteria were restricted to English journal articles concerning humans, clinical trials, cohorts and case-control studies. Therefore, systematic reviews, case reports, letters to editors, editorials and congress abstracts were excluded from the analysis. Most studies conducted on the issue have produced experimental data which are rather controversial, and there is no general agreement about the reported outcomes. As an illustration, most studies have not considered the relationship between the type of antioxidant materials and the shear bond strength. In point of fact, some researchers (e.g Kimyai et al.) have concluded that antioxidants like gel and solution leave similar effects on SBS. Alternatively, certain studies (e.g., Kunt et al.) have produced inconclusive data regarding the impact of one week postponement of the restorative process on SBS after the bleaching process. The results of the studies evaluating the role of various adhesive systems used after bleaching have demonstrated that regardless of the type of adhesive system used, applying antioxidants before restorative procedures can adversely affect the bleaching agents utilized for SBS. It has also been suggested that the type of the adhesive system used might be correlated with the magnitude of SBS. The results obtained from the systematic review of the articles under investigation reflected that the use of antioxidant agents, regardless of their type, form, concentration and duration of application, can improve SBS after bleaching. Copyright

  16. Olivine-type cathode for rechargeable batteries: Role of chelating agents

    International Nuclear Information System (INIS)

    Kandhasamy, Sathiyaraj; Singh, Pritam; Thurgate, Stephen; Ionescu, Mihail; Appadoo, Dominique; Minakshi, Manickam

    2012-01-01

    Highlights: ► Olivine powder was synthesized by sol–gel method using a range of chelating agents. ► Role of chelating agents in olivine cathode was investigated for battery application. ► Battery was fabricated with olivine cathode, Zn anode and aqueous electrolyte. ► Synergetic effect of additives (CA + TEA + PVP) led to improved storage capacity. - Abstract: Olivine (LiCo 1/3 Mn 1/3 Ni 1/3 PO 4 ) powders were synthesized at 550–600 °C for 6 h in air by a sol–gel method using multiple chelating agents and used as a cathode material for rechargeable batteries. Range of chelating agents like a weak organic acid (citric acid – CA), emulsifier (triethanolamine – TEA) and non-ionic surfactant (polyvinylpyrrolidone – PVP) in sol–gel wet chemical synthesis were used. The dependence of the physicochemical properties of the olivine powders such as particle size, morphology, structural bonding and crystallinity on the chelating agent was extensively investigated. Among the chelating agents used, unique cycling behavior (75 mAh/g after 25 cycles) is observed for the PVP assisted olivine. This is due to volumetric change in trapped organic layer for first few cycles. The trapped organic species in the electrode–electrolyte interface enhances the rate of lithium ion diffusion with better capacity retention. In contrast, CA and TEA showed a gradual capacity fade of 30 and 38 mAh/g respectively after multiple cycles. The combination of all the three mixed chelating agents showed an excellent electrochemical behavior of 100 mAh/g after multiple cycles and the synergistic effect of these agents are discussed.

  17. Improving Tensile Bond Strength of Orthodontic Bracket by Applying Papain Gel as an Email Deproteinization Agent

    Directory of Open Access Journals (Sweden)

    Niswati Fathmah Rosyida

    2017-12-01

    Full Text Available An effort to improve the bonding between bracket and tooth surface is required. Objective: The aim of this studywas to evaluate the effect of papain gel on tensile bond strength (TBS and adhesive remnant index (ARI of the orthodontic brackets. Methods: A total of 42 healthy human premolars were randomly divided into six groups. 1 Resin-modifed glass ionomer cement (RMGIC without papain, 2 RMGIC with papain 8%, 3 RMGIC with papain 10%, 4 Composite resin (CR without papain, 5 CR with papain 8%, 6 CR with papain 10%. The TBS was determined using a universal testing machine. Bond failure was classifed according to the ARI. The TBS data were analyzed with Kruskal-Wallis test followed by Mean Whitney tests with 5% of signifcance level. Results: The mean of TBS(MPa values of RMGIC groups are without papain (5.03 ± 1.52, papain 8% (4.79 ± 2.61, papain 10 (7.75 ± 1, 48. CR groups without papain (5.45 ± 1.23, papain 8% (2.30 ± 0.73, and papain 10% (4.84 ± 1.72 Bond failure was mainly classifed as score 1. The TBS values were statistically influenced by the application of papain and adhesive. Conclusion: The application of papain 10% before RMGIC cementation improves the tensile bond strength and could decrease the bond failure of the orthodontic bracket.

  18. The importance of role sending in the sensemaking of change agent roles.

    Science.gov (United States)

    Tucker, Danielle A; Hendy, Jane; Barlow, James

    2015-01-01

    The purpose of this paper is to investigate what happens when a lack of role-sending results in ambiguous change agent roles during a large scale organisational reconfiguration. The authors consider the role of sensemaking in resolving role ambiguity of middle manager change agents and the consequences of this for organisational restructuring. Data were collected from a case study analysis of significant organisational reconfiguration across a local National Health Service Trust in the UK. Data consists of 82 interviews, complemented by analysis of over 100 documents and field notes from 51 hours of observations collected over five phases covering a three year period before, during and after the reconfiguration. An inductive qualitative analysis revealed the sensemaking processes by which ambiguity in role definition was resolved. The data explains how change agents collectively make sense of a role in their own way, drawing on their own experiences and views as well as cues from other organisational members. The authors also identified the organisational outcomes which resulted from this freedom in sensemaking. This study demonstrates that by leaving too much flexibility in the definition of the role, agents developed their own sensemaking which was subsequently very difficult to manipulate. In creating new roles, management first needs to have a realistic vision of the task and roles that their agents will perform, and second, to communicate these expectations to both those responsible for recruiting these roles and to the agents themselves. Much of the focus in sensemaking research has been on the importance of change agents' sensemaking of the change but there has been little focus on how change agents sensemake their own role in the change.

  19. In vitro Effects of a Neutral Fluoride Agent on Shear Bond Strength and Microleakage of Orthodontic Brackets

    Directory of Open Access Journals (Sweden)

    Farzaneh Ahrari

    2014-06-01

    Full Text Available Introduction: This study aimed to evaluate the effect of pretreatment with a neutral fluoride agent on shear bond strength (SBS and microleakage of orthodontic brackets, and to investigate any significant relationship between SBS and microleakage. Methods: Forty intact premolars were selected and randomly divided into 2 groups. Group 1 served as the control, while group 2 underwent treatment with a 2% sodium fluoride (NaF gel, which was applied on the enamel surface for 4 minutes before etching. After bonding orthodontic brackets, the teeth were immersed for 12 hours in methylen blue dye, followed by mounting in acrylic resin. Shear bond strength was determined using an Instron Universal Testing Machine and the amount of microleakage and the adhesive remnant index (ARI were assessed under a stereomicroscope. Results: The mean SBS and microleakage beneath metal brackets were not significantly different among the control and NaF-treated groups (P>0.05. Furthermore, no significant correlation was found between SBS and microleakage (r=-0.04, P=0.796. The ARI scores revealed that in both groups, most of the adhesive remained on the enamel surface after debonding. Conclusions: It may be concluded that pretreatment of enamel with 2% NaF prior to the bonding procedure does not significantly affect microleakage and SBS of orthodontic brackets and thus, it can be recommended as a suitable approach to reduce the incidence of white spot lesions in orthodontically treated patients, especially those at high risk of caries formation.  

  20. Effects of three silane primers and five adhesive agents on the bond strength of composite material for a computer-aided design and manufacturing system.

    Science.gov (United States)

    Shinohara, Ayano; Taira, Yohsuke; Sakihara, Michino; Sawase, Takashi

    2018-01-01

    Objective The objective of this study was to evaluate the effects of combinations of silane primers and adhesive agents on the bond strength of a composite block for a computer-aided design and manufacturing system. Material and Methods Three silane primers [Clearfil Ceramic Primer (CP), Super-Bond PZ Primer (PZ), and GC Ceramic Primer II (GP)] were used in conjunction with five adhesive agents [G-Premio Bond (P-Bond), Repair Adhe Adhesive (R-Adhesive), Super-Bond D-Liner Dual (SB-Dual), Super-Bond C&B (SB-Self), and SB-Dual without tributylborane derivative (SB-Light)]. The surface of a composite block (Gradia Block) was ground with silicon carbide paper. After treatment with a silane primer, a adhesive agent was applied to each testing specimen. The specimens were then bonded with a light-curing resin composite. After 24 h, the shear bond strength values were determined and compared using a post hoc test (α=0.05, n=8/group). We also prepared control specimens without primer (No primer) and/or without adhesive agent (No adhesive). Results PZ/SB-Dual and GP/SB-Dual presented the highest bond strength, followed by GP/P-Bond, CP/SB-Dual, CP/R-Adhesive, No primer/SB-Dual, GP/R-Adhesive, CP/P-Bond, No primer/R-Adhesive, PZ/R-Adhesive, CP/SB-Self, PZ/P-Bond, PZ/SB-Self, and GP/SB-Self in descending order of bond strength. No primer/P-Bond, No primer/SB-Self, and all specimens in the SB-Light and No adhesive groups presented the lowest bond strengths. Conclusion A dual-curing adhesive agent (SB-Dual) containing a tributylborane derivative in combination with a silane primer (GP or PZ) presents a greater bond strength between the composite block and the repairing resin composite than the comparators used in the study.

  1. The role of radial nodes of atomic orbitals for chemical bonding and the periodic table.

    Science.gov (United States)

    Kaupp, Martin

    2007-01-15

    The role of radial nodes, or of their absence, in valence orbitals for chemical bonding and periodic trends is discussed from a unified viewpoint. In particular, we emphasize the special role of the absence of a radial node whenever a shell with angular quantum number l is occupied for the first time (lack of "primogenic repulsion"), as with the 1s, 2p, 3d, and 4f shells. Although the consequences of the very compact 2p shell (e.g. good isovalent hybridization, multiple bonding, high electronegativity, lone-pair repulsion, octet rule) are relatively well known, it seems that some of the aspects of the very compact 3d shell in transition-metal chemistry are less well appreciated, e.g., the often weakened and stretched bonds at equilibrium structure, the frequently colored complexes, and the importance of nondynamical electron-correlation effects in bonding. Copyright (c) 2006 Wiley Periodicals, Inc.

  2. [Influence of different bonding agents on traction resistance of metal alloys to dentin].

    Science.gov (United States)

    Adabo, G L; da Silva Filho, F P; de Sá, D N; Rettondini, W C; dos Santos Cruz, C A

    1990-01-01

    They were casted pieces using three kinds of alloy (Ni-Cr, Ag-Sn and Cu-Al) with circular and smooth surface. They were cemented to human teeth, on occlusal surface, grounded at dentin level, through three different materials kind (zinc polycarboxylate cement, glassionomer cement and composite). After 24 hours storing, the samples were subjected to the tensile test. The results showed that the samples cemented with composite and the casts made with Ag-Sn alloy had higher bond strength.

  3. Effects of cleaning agents on bond strength to dentin Efeitos de agentes de limpeza na resistência adesiva à dentina

    Directory of Open Access Journals (Sweden)

    Celso Rosin

    2005-06-01

    Full Text Available The cleaning of cavity walls aims to improve adhesive restorative procedures and longevity of restorations. This study has compared the effect of three cleaning agents - sodium bicarbonate jet (Profi II, Dabi Atlante, São Paulo, Brazil; pumice paste plus a biologic detergent (Tergestesim, Probem, São Paulo, Brazil; air water spray - on the bond strength between dentin and two different adhesive systems: Clearfil SE Bond (Kuraray, Kioto, Japan and Scotchbond Multi-Purpose Plus (3M-ESPE, São Paulo, Brazil. Six groups (n:10 of dental fragments obtained from young adult extracted teeth were prepared, and each one received one of the listed surface cleaning techniques. After the adhesive application, a cone-shaped test body was built with AP-X (Kuraray, Kioto, Japan or Z100 (3M-ESPE, São Paulo, Brazil composite resins, using a Teflon matrix. The specimens were tested for tensile bond strength after one-week storage in distilled water at 37°C. Two pairs of fractured specimens of each group were randomly chosen and processed for scanning electron microscopy (SEM analysis. ANOVA test of the bond strength values showed no statistical differences among the cleaning agents and neither between their interactions with the bonding systems. Upon SEM analysis, most surfaces showed mixed fractures of adhesive and cohesive failures in bonding resin to dentin. Based on statistical and SEM analysis, it was concluded that the cleaning agents studied did not interfere with the bond strength of the adhesive systems used to dentin.A limpeza das paredes cavitárias é um passo importante na clínica odontológica e visa otimizar os procedimentos adesivos e a longevidade das restaurações. O presente estudo comparou o efeito de três agentes de limpeza cavitária - jato abrasivo de bicarbonato de sódio/ar/água (Profi II, Dabi Atlante, São Paulo, Brasil; pasta de pedra-pomes e água, somada a um detergente biológico (Tergestesim, Probem, São Paulo, Brasil; e

  4. Production of an experimental bonding agent containing doxycyicline as matrix metalloproteinase inhibitor, and its release rate

    Directory of Open Access Journals (Sweden)

    Ghavam M

    2010-01-01

    Full Text Available Background and Aims: In spite of the advances achieved in the field of dentin adhesives, the longevity of bond to dentin is still a challenge. According to recent studies, Matrix Metaloproteinase (MMP inhibitors can increase clinical longevity of bonding and decrease leakage. The aim of this study was to evaluate the amount and pattern of doxycycline release from an experimental dentin adhesive containing this MMP inhibitor. Materials and Methods: In this experimental study, specimens containing 0.25 and 0.5 loading percent of doxycycline in an experimental monomer were prepared in cylindrical moulds of 12 mm diameter and 2 mm thickness. The adhesive monomer was composed of 12 wt% Bis-GMA, 10 wt% TMPTMA, 28 wt% HEMA and 50 wt% ethanol. Camphorquinone and amine were used as initiators. Results: Addition of 0.25 and 0.5 w% doxycycline showed linear release in both groups. Increasing the loading percent of doxycycline caused more release. The release continued during the test period. Conclusion: Doxycycline release was observed from the experimental adhesive. Further studies in this field will help in preparing adhesive systems with more clinical longevity.

  5. Bacterial leakage in root canals filled with AH Plus and dentine bonding agents.

    Science.gov (United States)

    Navarro-Escobar, Esther; Baca, Pilar; Ruiz-Linares, Matilde; Arias-Moliz, Maria Teresa; Perez-Heredia, Mercedes; Ferrer-Luque, Carmen Maria

    2014-11-01

    The aim of this study was to compare the efficacy of different dentine adhesives in delaying the coronal bacterial leakage of Enterococcus faecalis in filled root canals. Materials and methods. Ninety-five lower incisors of patients >65 years of age were instrumented using the ProTaper system and were irrigated with 1 mL of 2.5% sodium hypochlorite (NaOCl) alternated with 1 mL 17% EDTA between each file change. Final irrigation was performed with 5 mL of 17% EDTA and then flushed with 5 mL of distilled water. The teeth were randomly divided into five experimental groups (n = 15/group) and one of the following dentine adhesives was applied: (1) AdheSE; (2) Excite DSC; (3) Clearfil Protect Bond; (4) One Coat 7.0; or (5) Control group without adhesive. After filling the root canals, the samples were mounted on a double chamber device to evaluate the bacterial filtration of E. faecalis during a period of 240 days. The results underwent non-parametric Kaplan-Meier survival analysis and comparisons among groups were done using the Log-Rank test. At 240 days, E. faecalis was detected in samples of all groups in the lower chamber. The highest survival value was obtained by One Coat 7.0, giving statistically significant differences from the other groups, whereas Clearfil Protect Bond, AdheSE and Excite DSC showed similar behaviours, likewise similar to the Control group. One Coat 7.0 adhesive system provides the longest survival value to delay E. faecalis coronal leakage in filled root canals.

  6. Aryl diazonium salts: a new class of coupling agents for bonding polymers, biomacromolecules and nanoparticles to surfaces.

    Science.gov (United States)

    Mahouche-Chergui, Samia; Gam-Derouich, Sarra; Mangeney, Claire; Chehimi, Mohamed M

    2011-07-01

    This critical review summarizes existing knowledge on the use of diazonium salts as a new generation of surface modifiers and coupling agents for binding synthetic polymers, biomacromolecules, and nanoparticles to surfaces. Polymer grafts can be directly grown at surfaces through the so-called grafting from approaches based on several polymerization methods but can also be pre-formed in solution and then grafted to surfaces through grafting onto strategies including "click" reactions. Several routes are also described for binding biomacromolecules through aryl layers in view of developing biosensors and protein arrays, while the use of aryl diazonium coupling agents is extended to the attachment of nanoparticles. Patents and industrial applications of the surface chemistry of diazonium compounds are covered. This review stresses the paramount role of aryl diazonium coupling agents in adhesion, surface and materials sciences (114 references).

  7. Effect of adding Matrix Metallo proteinase inhibitors on the degree of conversion of monomers to polymer an experimental bonding agent

    Directory of Open Access Journals (Sweden)

    Ghavam M.

    2009-11-01

    Full Text Available "nBackground and Aim: In spite of the achievements in the field of dental adhesives, we are facing challenges with dentine bonding resistance, strength and stability. According to recent studies the role of MMP inhibitors in association with bonding,s persistence and leakage reduction and restoration,s persistence is important. The aim of this study was to investigate the effect of doxycycline as a MMP inhibitor on the degree of conversion (DC of an experimental dental adhesive. "nMaterials and Methods: In this experimental study, a new dental adhesive blend was prepared by mixing doxycycline monohydrate (in concentrations of 0.0, 0.25, 0.5, and 1 wt.% with monomers. The monomers were composed of 12% Bis-GMA and 10% TMPTMA, 28% HEMA, and 50% Ethanol by weight for all groups. Comphorquinone and amines were chosen as photo initiator system. Degree of conversion of all adhesives was measured using FTIR spectroscopy. The results were analyzed using one-way ANOVA and Tukey post hoc tests. "nResults: The results showed that addition of 0.25, 0.5, and 1 weight percent doxycycline did not significantly reduce the DC of the adhesives compared to 0.0% control group (p>0.05%. "nConclusion: According to the results of this study, adding doxycycline to the adhesives did not adversely affect the DC.

  8. Resistance of an enamel-bonding agent to saliva and acid exposure in vitro assessed by liquid scintillation.

    Science.gov (United States)

    Schmidlin, P R; Göhring, T N; Sener, B; Lutz, F

    2002-06-01

    To determine the leakage and resistance of a bonding agent and a light-curing fine hybrid composite when exposed to saliva or lactic acid (pH 4) in vitro. Twenty discs in each of four groups of selected irradiated bovine lower central incisors were treated with one of three sealing options: an enamel bond (Heliobond, Vivadent, Schaan, Liechenstein) in a single-step application; Heliobond in a two-step application; and Tetric Flow (Vivadent) as the negative control. One group served as the positive control and remained unsealed. Loss of apatite was determined using the radiochemical method of liquid scintillation. The Cherenkov radiation was assessed in order to evaluate the acid resistance and leakage of smooth surface enamel bonding after exposure to saliva and lactic acid. In addition, replicas were made for SEM analysis of micromorphologic surface changes. A mean loss of 416.5 g (s.d. 57.0) apatite was observed over the unsealed sites following 14 days of exposure to lactic acid. The application of Heliobond in a one- and two-step application still revealed a remarkable degree of leakage, and substance losses of 196.5 g (s.d. 38.9) and 161.8 g (s.d. 39.7), but a protective potential was evident. In saliva, untreated, as well as sealed teeth, showed a modest leakage that was less than 20 g. When Tetric Flow was used (negative control) leakage was reduced to a minimum of 2.4 g (s.d. 1.0) in saliva and 12.8 g (s.d. 19.6) in lactic acid. These results were confirmed by SEM analysis. The method of liquid scintillation was revealed to be of considerable value in evaluating leakage and acid resistance of potential smooth enamel sealing options. Sealing with an unfilled resin still demonstrated remarkable levels of acid dissolution, although a protection tendency could be observed. This leads to the conclusion that there is a need for further investigation to establish more acid-resistant enamel sealing agents.

  9. The role of zoonotic chlamydial agents in ruminants abortion.

    Science.gov (United States)

    Barati, Sara; Moori-Bakhtiari, Naghmeh; Najafabadi, Masoud Ghorbanpoor; Momtaz, Hassan; Shokuhizadeh, Leili

    2017-10-01

    Enzootic abortion of ewes (EAE) is caused by infection of sheep and goats by Chlamydia abortus bacterium. Chlamydial abortion in bovine could occur by Chlamydia abortus, Chlamydia psittaci and Chlamydia pecorum. C. psittaci is the causative agent of psittacosis or ornithosis disease in humans and birds. It also causes acute pneumonia in cattle and sheep. The present study aimed at surveying the role of chlamydial agents in ruminants abortion. A total of 117 aborted material samples (Cotyledon, liver, spleen, and abomasal contents of fetus) from 9 cattle and 100 sheep in Shahr-e-Kord and 8 sheep from Bagh-e-Malek were collected from different herds with abortion history during the lambing periods from 2014 to 2016. After DNA extraction, the samples were tested by species-specific PCR to detect C. abortus, C. pecorum and C. psittaci. Out of 117 clinical sample (108 sheep and 9 cattle), chlamydial infection was detected in 66 (56.41%) samples by Chlamydiales order-specific primers. A total of 24 (36.36%) and 24 (36.36%) samples indicated positive forms of C. abortus and C. psittasi infections, respectively. Only 1 (1.5%) C. pecorum was identified from cattle using nested PCR during this study. Among 66 Chlamydiales -positive samples, 20 (30.30%) samples with coinfection of C. abortus and C. psittaci were detected, however, infection of 3 species was not detected in the samples. Because of the high percentage of chlamydial infection in these regions and probability of coinfection, conducting epidemiological studies on the role of different animals is highly recommended.

  10. Silane coupling agent for attaching fusion-bonded epoxy to steel.

    Science.gov (United States)

    Tchoquessi Diodjo, Madeleine R; Belec, Lénaïk; Aragon, Emmanuel; Joliff, Yoann; Lanarde, Lise; Perrin, François-Xavier

    2013-07-24

    We describe the possibility of using γ-aminopropyltriethoxysilane (γ-APS) to increase the durability of epoxy powder coating/steel joints. The curing temperature of epoxy powder coatings is frequently above 200 °C, which is seen so far as a major limitation for the use of the heat-sensitive aminosilane coupling agent. Despite this limitation, we demonstrate that aminosilane is a competitive alternative to traditional chromate conversion to enhance the durability of epoxy powder coatings/steel joints. Fourier-transform reflection-absorption infrared spectroscopy (FT-RAIRS), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) were used to identify the silane deposition conditions that influence the adhesion of epoxy powder coatings on steel. We show that AFM analysis provides highly sensitive measurements of mechanical property development and, as such, the degree of condensation of the silane. The joint durability in water at 60 °C was lower when the pH of the γ-APS solution was controlled at 4.6 using formic acid, rather than that at natural pH (10.6). At the curing temperature of 220 °C, oxidation of the carbon adjacent to the amine headgroup of γ-APS gives amide species by a pseudofirst-order kinetics. However, a few amino functionalities remain to react with oxirane groups of epoxy resin and, thus, strengthen the epoxy/silane interphase. The formation of ammonium formate in the acidic silane inhibits the reaction between silane and epoxy, which consequently decreases the epoxy/silane interphase cohesion. We find that the nanoroughness of silane deposits increases with the cure temperature which is beneficial to the wet stability of the epoxy/steel joints, due to increased mechanical interlocking.

  11. Transition Metal Free C-N Bond Forming Dearomatizations and Aryl C-H Aminations by in Situ Release of a Hydroxylamine-Based Aminating Agent.

    Science.gov (United States)

    Farndon, Joshua J; Ma, Xiaofeng; Bower, John F

    2017-10-11

    We outline a simple protocol that accesses directly unprotected secondary amines by intramolecular C-N bond forming dearomatization or aryl C-H amination. The method is dependent on the generation of a potent electrophilic aminating agent released by in situ deprotection of O-Ts activated N-Boc hydroxylamines.

  12. Role of intermetallics on the mechanical fatigue behavior of Cu–Al ball bond interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lassnig, A., E-mail: alice.lassnig@univie.ac.at [University of Vienna, Faculty of Physics, Physics of Nanostructured Materials, Boltzmanngasse 5, 1090 Wien (Austria); Pelzer, R. [Infineon Technologies Austria AG, Siemensstrae 2, 9500 Villach (Austria); Gammer, C. [University of Vienna, Faculty of Physics, Physics of Nanostructured Materials, Boltzmanngasse 5, 1090 Wien (Austria); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Khatibi, G. [Vienna University of Technology, Institute of Chemical Technology and Analytics, Getreidemarkt 9, 1060 Wien (Austria)

    2015-10-15

    The mechanical fatigue behavior of Cu–Al interfaces occurring in thermosonic ball bonds –typically used in microelectronic packages for automotive applications – is investigated by means of a specially designed fatigue test technique. Fully reversed cyclic shear stresses are induced at the bond interface, leading to subsequent fatigue lift off failure and revealing the weakest site of the bond. A special focus is set on the role of interfacial intermetallic compounds (IMC) on the fatigue performance of such interfaces. Therefore fatigue life curves were obtained for three representative microstructural states: The as-bonded state is compared to two annealed states at 200 °C for 200 h and at 200 °C for 2000 h respectively. In the moderately annealed state two IMC layers (Al{sub 2}Cu, Al{sub 4}Cu{sub 9}) could be identified, whereas in the highly aged state the original pad metallization was almost entirely consumed and AlCu is formed as a third IMC. Finally, the crack path is traced back as a function of interfacial microstructure by means of electron microscopy techniques. Whereas conventional static shear tests reveal no significant decrease of the bond shear force with increased IMC formation the fatigue tests prove a clear degradation in the cyclic mechanical performance. It can be concluded that during cycling the crack deflects easily into the formed intermetallics, leading to early failure of the ball bonds due to their brittle nature. - Highlights: • High cycle fatigue of various miniaturized Cu–Al interfaces is investigated. • Interfacial intermetallic compounds consist of Al2Cu, AlCu and Al4Cu9. • Static shear strength shows minor dependency on interfacial phase formation. • Fatigue tests prove significant degradation with intermetallic compound evolution. • Fatigue fracture surface analysis reveal microstructure dependent crack path.

  13. Role of intermetallics on the mechanical fatigue behavior of Cu–Al ball bond interfaces

    International Nuclear Information System (INIS)

    Lassnig, A.; Pelzer, R.; Gammer, C.; Khatibi, G.

    2015-01-01

    The mechanical fatigue behavior of Cu–Al interfaces occurring in thermosonic ball bonds –typically used in microelectronic packages for automotive applications – is investigated by means of a specially designed fatigue test technique. Fully reversed cyclic shear stresses are induced at the bond interface, leading to subsequent fatigue lift off failure and revealing the weakest site of the bond. A special focus is set on the role of interfacial intermetallic compounds (IMC) on the fatigue performance of such interfaces. Therefore fatigue life curves were obtained for three representative microstructural states: The as-bonded state is compared to two annealed states at 200 °C for 200 h and at 200 °C for 2000 h respectively. In the moderately annealed state two IMC layers (Al 2 Cu, Al 4 Cu 9 ) could be identified, whereas in the highly aged state the original pad metallization was almost entirely consumed and AlCu is formed as a third IMC. Finally, the crack path is traced back as a function of interfacial microstructure by means of electron microscopy techniques. Whereas conventional static shear tests reveal no significant decrease of the bond shear force with increased IMC formation the fatigue tests prove a clear degradation in the cyclic mechanical performance. It can be concluded that during cycling the crack deflects easily into the formed intermetallics, leading to early failure of the ball bonds due to their brittle nature. - Highlights: • High cycle fatigue of various miniaturized Cu–Al interfaces is investigated. • Interfacial intermetallic compounds consist of Al2Cu, AlCu and Al4Cu9. • Static shear strength shows minor dependency on interfacial phase formation. • Fatigue tests prove significant degradation with intermetallic compound evolution. • Fatigue fracture surface analysis reveal microstructure dependent crack path

  14. Role of the bond defect for structural transformations between crystalline and amorphous silicon: A molecular-dynamics study

    International Nuclear Information System (INIS)

    Stock, D. M.; Weber, B.; Gaertner, K.

    2000-01-01

    The relation between the bond defect, which is a topological defect, and structural transformations between crystalline and amorphous silicon, is studied by molecular-dynamics simulations. The investigation of 1-keV boron implantation into crystalline silicon proves that the bond defect can also be generated directly by collisional-induced bond switching in addition to its formation by incomplete recombination of primary defects. This supports the assumption that the bond defect may play an important role in the amorphization process of silicon by light ions. The analysis of the interface between (001) silicon and amorphous silicon shows that there are two typical defect configurations at the interface which result from two different orientations of the bond defect with respect to the interface. Thus the bond defect appears to be a characteristic structural feature of the interface. Moreover, annealing results indicate that the bond defect acts as a growth site for interface-mediated crystallization

  15. The Effect of Simplified Bonding Agents on the Bond Strength to Dentin of Self-Activated Dual-Cure Resin Cements

    Science.gov (United States)

    2013-04-26

    steps that included an acidic conditioner, primer, and adhesive monomer. Examples include Optibond FL (Kerr) and Adper Scotchbond MultiPurpose ( 3M ESPE...Bond NT (Dentsply) and Adper Prompt L-Pop ( 3M /ESPE); and two non-simplified adhesives , Optibond FL (Kerr) and Clearfil SE (Kuraray). The four...presentation at the 2013 IADR by Bisco Inc. compared their simplified adhesive and self-cure resin combination All-Bond Universal and Duolink with

  16. The effect of different surface treatments of stainless steel crown and different bonding agents on shear bond strength of direct composite resin veneer

    Directory of Open Access Journals (Sweden)

    Ajami B

    2007-01-01

    Full Text Available Background and Aim: Stainless steel crown (SSC is the most durable and reliable restoration for primary teeth with extensive caries but its metalic appearance has always been a matter of concern. With advances in restorative materials and metal bonding processes, composite veneer has enhanced esthetics of these crowns in clinic. The aim of this study was to evaluate the shear bond strength of SSC to composite resin using different surface treatments and adhesives. Materials and Methods: In this experimental study, 90 stainless steel crowns were selected. They were mounted in molds and divided into 3 groups of 30 each (S, E and F. In group S (sandblast, buccal surfaces were sandblasted for 5 seconds. In group E (etch acidic gel was applied for 5 minutes and in group F (fissure bur surface roughness was created by fissure diamond bur. Each group was divided into 3 subgroups (SB, AB, P based on different adhesives: Single Bond, All Bond2 and Panavia F. Composite was then bonded to specimens. Cases were incubated in 100% humidity at 37°C for 24 hours. Shear bond strength was measured by Zwick machine with crosshead speed of 0.5 mm/min. Data were analyzed by ANOVA test with p0.05 so the two variables were studied separately. No significant difference was observed in mean shear bond strength of composite among the three kinds of adhesives (P>0.05. Similar results were obtained regarding surface treatments (P>0.05. Conclusion: Based on the results of this study, treating the SSC surface with bur and using single bond adhesive and composite can be used successfully to obtain esthetic results in pediatric restorative treatments.

  17. Microleakage of bonded amalgam restorations using different adhesive agents with dye under vacuum: An in vitro study

    Directory of Open Access Journals (Sweden)

    Abhishek Parolia

    2011-01-01

    Clinical Significance: Bonded amalgam restorations prevent over-preparation and reduce the tooth flexure. GIC type I under amalgam provides chemical bonding in between amalgam and tooth structure and thus reduces the microleakage.

  18. Non-Classical C–H···X Hydrogen Bonding and Its Role in Asymmetric Organocatalysis

    KAUST Repository

    Ajitha, Manjaly John; Huang, Kuo-Wei

    2016-01-01

    Non-classical hydrogen bonds (NCHBs) have attracted significant interest in the past decade particularly because of their important role in asymmetric catalytic systems. These weak interactions (< 4 kcal/mol) offer much flexibility1 Introduction2 Hydrogen Bonds (HBs) and Non-Classical Hydrogen Bonds (NCHBs)3 Early Developments in NCHBs4 Selected Examples of NCHBs in Organic Transformations5 Recent Examples of NCHBs in Enantioselective Reactions6 Conclusions and Outlook

  19. The Role of Molecule Clustering by Hydrogen Bond in Hydrous Ethanol on Laminar Burning Velocity

    Directory of Open Access Journals (Sweden)

    I Made Suarta

    2016-01-01

    Full Text Available The role of hydrogen bond molecule clustering in laminar burning velocities was observed. The water in hydrous ethanol can change the interaction between water-ethanol molecules. A certain amount of water can become oxygenated which increases the burning velocity. The hydrogen bond interaction pattern of ethanol and water molecules was modeled. Based on the molecular model, azeotropic behavior emerges from ethanol-water hydrogen bond, which is at a 95.1%v composition. The interaction with water molecule causes the ethanol molecule to be clustered with centered oxygenated compound. So, it supplies extra oxygen and provides intermolecular empty spaces that are easily infiltrated by the air. In the azeotropic composition, the molecular bond chain is the shortest, so hypothetically the burning velocity is anticipated to increase. The laminar burning velocity of ethanol fuel was tested in a cylindrical explosion bomb in lean, stoichiometric, and rich mixtures. The experimental result showed that the maximum burning velocity occurred at hydrous ethanol of 95.5%v composition. This discrepancy is the result of the addition of energy from 7.7% free ethanol molecules that are not clustered. At the rich mixture, the burning velocity of this composition is higher than that of anhydrous ethanol.

  20. Bond markets and banking crises in emerging market economies: The role of institutions

    Directory of Open Access Journals (Sweden)

    Boukhatem Jamel

    2012-01-01

    Full Text Available This paper deals with the question of knowing if countries whose activity of financing is mainly bank based face crises more expensive than those where the bond markets are broader and more developed. The results of the empirical tests on a panel of emerging countries suggest that bank based financial systems are associated with crises slightly more expensive, whereas the relationship between the bond markets and the crises’ costs is fragile. Moreover, financial systems where bond markets play an important role are associated with a higher growth of the production, and this, independently of the presence or not of crises. The consideration of the combined effect of financial liberalization and institutional framework on the bond markets development shows the importance of the direction of the financial liberalization. We join in this case one of the most significant aspects of the “sequencing” theorized by McKinnon (1973. Finally, an effective prudential regulation tends to reduce significantly the probability of occurrence of banking crises.

  1. Dissecting the role of disulfide bonds on the amyloid formation of insulin

    International Nuclear Information System (INIS)

    Li, Yang; Gong, Hao; Sun, Yue; Yan, Juan; Cheng, Biao; Zhang, Xin; Huang, Jing; Yu, Mengying; Guo, Yu; Zheng, Ling; Huang, Kun

    2012-01-01

    Highlights: ► We dissect how individual disulfide bond affects the amyloidogenicity of insulin. ► A controlled reduction system for insulin is established in this study. ► Disulfide breakage is associated with unfolding and increased amyloidogenicity. ► Breakage of A6-A11 is associated with significantly increased cytotoxicity. ► Analogs without A6-A11 have a higher potency to form high order toxic oligomers. -- Abstract: Disulfide bonds play a critical role in the stability and folding of proteins. Here, we used insulin as a model system, to investigate the role of its individual disulfide bond during the amyloid formation of insulin. Tris(2-carboxyethyl)phosphine (TCEP) was applied to reduce two of the three disulfide bonds in porcine insulin and the reduced disulfide bonds were then alkylated by iodoacetamide. Three disulfide bond-modified insulin analogs, INS-2 (lack of A6-A11), INS-3 (lack of A7-B7) and INS-6 (lack of both A6-A11 and A7-B7), were obtained. Far-UV circular dichroism (CD) spectroscopy results indicated that the secondary structure of INS-2 was the closest to insulin under neutral conditions, followed by INS-3 and INS-6, whereas in an acidic solution all analogs were essentially unfolded. To test how these modifications affect the amyloidogenicity of insulin, thioflavin-T (ThT) fluorescence and transmission electronic microscopy (TEM) were performed. Our results showed that all analogs were more prone to aggregation than insulin, with the order of aggregation rates being INS-6 > INS-3 > INS-2. Cross-linking of unmodified proteins (PICUP) assay results showed that analogs without A6-A11 (INS-2 and INS-6) have a higher potential for oligomerization than insulin and INS-3, which is accompanied with a higher cytotoxicity as the hemolytic assays of human erythrocytes suggested. The results indicated that breakage of A7-B7 induced more unfolding of the insulin structure and a higher amyloidogenicity than breakage of A6-A11, but breakage of A6

  2. Role of dispersion corrected hybrid GGA class in accurately calculating the bond dissociation energy of carbon halogen bond: A benchmark study

    Science.gov (United States)

    Kosar, Naveen; Mahmood, Tariq; Ayub, Khurshid

    2017-12-01

    Benchmark study has been carried out to find a cost effective and accurate method for bond dissociation energy (BDE) of carbon halogen (Csbnd X) bond. BDE of C-X bond plays a vital role in chemical reactions, particularly for kinetic barrier and thermochemistry etc. The compounds (1-16, Fig. 1) with Csbnd X bond used for current benchmark study are important reactants in organic, inorganic and bioorganic chemistry. Experimental data of Csbnd X bond dissociation energy is compared with theoretical results. The statistical analysis tools such as root mean square deviation (RMSD), standard deviation (SD), Pearson's correlation (R) and mean absolute error (MAE) are used for comparison. Overall, thirty-one density functionals from eight different classes of density functional theory (DFT) along with Pople and Dunning basis sets are evaluated. Among different classes of DFT, the dispersion corrected range separated hybrid GGA class along with 6-31G(d), 6-311G(d), aug-cc-pVDZ and aug-cc-pVTZ basis sets performed best for bond dissociation energy calculation of C-X bond. ωB97XD show the best performance with less deviations (RMSD, SD), mean absolute error (MAE) and a significant Pearson's correlation (R) when compared to experimental data. ωB97XD along with Pople basis set 6-311g(d) has RMSD, SD, R and MAE of 3.14 kcal mol-1, 3.05 kcal mol-1, 0.97 and -1.07 kcal mol-1, respectively.

  3. Initial and long-term bond strengths of one-step self-etch adhesives with silane coupling agent to enamel-dentin-composite in combined situation.

    Science.gov (United States)

    Mamanee, Teerapong; Takahashi, Masahiro; Nakajima, Masatoshi; Foxton, Richard M; Tagami, Junji

    2015-01-01

    This study evaluated the effect of adding silane coupling agent on initial and long-term bond strengths of one-step self-etch adhesives to enamel-dentin-composite in combined situation. Cervical cavities were prepared on extracted molars and filled with Clearfil AP-X. After water-storage for one-week, the filled teeth were sectioned in halves to expose enamel, dentin and composite surfaces and then enamel-dentin-composite surface was totally applied with one of adhesive treatments (Clearfil SE One, Clearfil SE One with Clearfil Porcelain Bond Activator, Beautibond Multi, Beautibond Multi with Beautibond Multi PR Plus and Scotchbond Universal). After designed period, micro-shear bond strengths (µSBSs) to each substrate were determined. For each period of water-storage, additive silane treatments significantly increased µSBS to composite (penamel (p>0.05). Moreover, the stability of µSBS was depended on materials and substrates used.

  4. Chemotherapy-induced pulmonary hypertension: role of alkylating agents.

    Science.gov (United States)

    Ranchoux, Benoît; Günther, Sven; Quarck, Rozenn; Chaumais, Marie-Camille; Dorfmüller, Peter; Antigny, Fabrice; Dumas, Sébastien J; Raymond, Nicolas; Lau, Edmund; Savale, Laurent; Jaïs, Xavier; Sitbon, Olivier; Simonneau, Gérald; Stenmark, Kurt; Cohen-Kaminsky, Sylvia; Humbert, Marc; Montani, David; Perros, Frédéric

    2015-02-01

    Pulmonary veno-occlusive disease (PVOD) is an uncommon form of pulmonary hypertension (PH) characterized by progressive obstruction of small pulmonary veins and a dismal prognosis. Limited case series have reported a possible association between different chemotherapeutic agents and PVOD. We evaluated the relationship between chemotherapeutic agents and PVOD. Cases of chemotherapy-induced PVOD from the French PH network and literature were reviewed. Consequences of chemotherapy exposure on the pulmonary vasculature and hemodynamics were investigated in three different animal models (mouse, rat, and rabbit). Thirty-seven cases of chemotherapy-associated PVOD were identified in the French PH network and systematic literature analysis. Exposure to alkylating agents was observed in 83.8% of cases, mostly represented by cyclophosphamide (43.2%). In three different animal models, cyclophosphamide was able to induce PH on the basis of hemodynamic, morphological, and biological parameters. In these models, histopathological assessment confirmed significant pulmonary venous involvement highly suggestive of PVOD. Together, clinical data and animal models demonstrated a plausible cause-effect relationship between alkylating agents and PVOD. Clinicians should be aware of this uncommon, but severe, pulmonary vascular complication of alkylating agents. Copyright © 2015 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  5. The role of antiseptic agents in atopic dermatitis.

    Science.gov (United States)

    Lee, Melissa; Van Bever, Hugo

    2014-10-01

    The skin of individuals with atopic dermatitis has a susceptibility to be colonized with Staphylococcus aureus. This has been associated with increased frequency and severity of exacerbations of atopic dermatitis. Therefore, there is a growing interest in the use of antiseptic agents to target primary bacterial colonization and infection. Antiseptic agents have been found to be better tolerated and less likely to induce bacterial resistance as compared to antibiotics. There is also a wide variety of antiseptic agents available. The efficacy of antiseptic agents has yet to be established as the studies reviewed previously have been small and of suboptimal quality. This review discusses the rationale behind targeting S. aureus with antiseptic agents and presents findings from a review of studies assessing the efficacy of antiseptics in atopic dermatitis in the last five years. Four studies were found, including a bleach bath study which has already been reviewed elsewhere. The remaining 3 studies assessed the efficacy of sodium hypochlorite containing cleansing body wash, sodium hypochlorite baths and 1% triclosan in leave on emollient. These studies suggested some benefit for the inclusion of antiseptic use with the mainstay management of atopic dermatitis, including a potential steroid sparring effect. However, there are many limitations to these studies which therefore warrant further investigation on the impact of antiseptic use in atopic dermatitis.

  6. Pedagogical Agents as Learning Companions: The Role of Agent Competency and Type of Interaction

    Science.gov (United States)

    Kim, Yanghee; Baylor, Amy L.

    2006-01-01

    This study was designed to examine the effects of the competency (low vs. high) and interaction type (proactive vs. responsive) of pedagogical agents as learning companions (PALs) on learning, self-efficacy, and attitudes. Participants were 72 undergraduates in an introductory computer-literacy course who were randomly assigned to one of four…

  7. Role of hydrogen bonds in the reaction mechanism of chalcone isomerase.

    Science.gov (United States)

    Jez, Joseph M; Bowman, Marianne E; Noel, Joseph P

    2002-04-23

    In flavonoid, isoflavonoid, and anthocyanin biosynthesis, chalcone isomerase (CHI) catalyzes the intramolecular cyclization of chalcones into (S)-flavanones with a second-order rate constant that approaches the diffusion-controlled limit. The three-dimensional structures of alfalfa CHI complexed with different flavanones indicate that two sets of hydrogen bonds may possess critical roles in catalysis. The first set of interactions includes two conserved amino acids (Thr48 and Tyr106) that mediate a hydrogen bond network with two active site water molecules. The second set of hydrogen bonds occurs between the flavanone 7-hydroxyl group and two active site residues (Asn113 and Thr190). Comparison of the steady-state kinetic parameters of wild-type and mutant CHIs demonstrates that efficient cyclization of various chalcones into their respective flavanones requires both sets of contacts. For example, the T48A, T48S, Y106F, N113A, and T190A mutants exhibit 1550-, 3-, 30-, 7-, and 6-fold reductions in k(cat) and 2-3-fold changes in K(m) with 4,2',4'-trihydroxychalcone as a substrate. Kinetic comparisons of the pH-dependence of the reactions catalyzed by wild-type and mutant enzymes indicate that the active site hydrogen bonds contributed by these four residues do not significantly alter the pK(a) of the intramolecular cyclization reaction. Determinations of solvent kinetic isotope and solvent viscosity effects for wild-type and mutant enzymes reveal a change from a diffusion-controlled reaction to one limited by chemistry in the T48A and Y106F mutants. The X-ray crystal structures of the T48A and Y106F mutants support the assertion that the observed kinetic effects result from the loss of key hydrogen bonds at the CHI active site. Our results are consistent with a reaction mechanism for CHI in which Thr48 polarizes the ketone of the substrate and Tyr106 stabilizes a key catalytic water molecule. Hydrogen bonds contributed by Asn113 and Thr190 provide additional

  8. The role of uranium-arene bonding in H2O reduction catalysis

    Science.gov (United States)

    Halter, Dominik P.; Heinemann, Frank W.; Maron, Laurent; Meyer, Karsten

    2018-03-01

    The reactivity of uranium compounds towards small molecules typically occurs through stoichiometric rather than catalytic processes. Examples of uranium catalysts reacting with water are particularly scarce, because stable uranyl groups form that preclude the recovery of the uranium compound. Recently, however, an arene-anchored, electron-rich uranium complex has been shown to facilitate the electrocatalytic formation of H2 from H2O. Here, we present the precise role of uranium-arene δ bonding in intermediates of the catalytic cycle, as well as details of the atypical two-electron oxidative addition of H2O to the trivalent uranium catalyst. Both aspects were explored by synthesizing mid- and high-valent uranium-oxo intermediates and by performing comparative studies with a structurally related complex that cannot engage in δ bonding. The redox activity of the arene anchor and a covalent δ-bonding interaction with the uranium ion during H2 formation were supported by density functional theory analysis. Detailed insight into this catalytic system may inspire the design of ligands for new uranium catalysts.

  9. Understanding Emerging Market Sovereign Bond Yield Spread: Role of Default and Non-Default Determinants

    Directory of Open Access Journals (Sweden)

    Adelia Surya Pratiwi

    2015-04-01

    Full Text Available This paper is motivated by the fact that emerging market assets size has been expanding and trying to use sovereign debt market as part of capital market as main research focus. It is highlighting the distinction between default and non-default determinants and examining their significance in explaining emerging market sovereign bond yield spread. Using Cross-Sectional Fixed-Effect Panel Estimator, we found that both default (as proxied by Credit Rating and Outlook Index and non-default (as proxied by 3-month Fed Funds Futures determinants has significant explanatory power to sovereign bond yield spread. Extensively, we also found the significance to add volatility of 3-month Fed Funds Futures and Fed Target Rate basis and volatility of advanced stock markets as variables to stand for non-default determinants in the model. The significance of the latter model is strengthened by higher forecasting as well as indicates the significant role of US market to emerging market sovereign bond market.

  10. The Role of Conversation Policy in Carrying Out Agent Conversations

    International Nuclear Information System (INIS)

    Link, Hamilton E.; Phillips, Laurence R.

    1999-01-01

    Structured conversation diagrams, or conversation specifications, allow agents to have predictable interactions and achieve predefined information-based goals, but they lack the flexibility needed to function robustly in an unpredictable environment. We propose a mechanism that combines a typical conversation structure with a separately established policy to generate an actual conversation. The word ''policy'' connotes a high-level direction external to a specific planned interaction with the environment. Policies, which describe acceptable procedures and influence decisions, can be applied to broad sets of activity. Based on their observation of issues related to a policy, agents may dynamically adjust their communication patterns. The policy object describes limitations, constraints, and requirements that may affect the conversation in certain circumstances. Using this new mechanism of interaction simplifies the description of individual conversations and allows domain-specific issues to be brought to bear more easily during agent communication. By following the behavior of the conversation specification when possible and deferring to the policy to derive behavior in exceptional circumstances, an agent is able to function predictably under normal situations and still act rationally in abnormal situations. Different conversation policies applied to a given conversation specification can change the nature of the interaction without changing the specification

  11. Halogen bond tunability II: the varying roles of electrostatic and dispersion contributions to attraction in halogen bonds

    Czech Academy of Sciences Publication Activity Database

    Riley, Kevin Eugene; Murray, J. S.; Fanfrlík, Jindřich; Řezáč, Jan; Solá, R. J.; Concha, M. C.; Ramos, F. M.; Politzer, P.

    2013-01-01

    Roč. 19, č. 11 (2013), s. 4651-4659 ISSN 1610-2940 R&D Projects: GA ČR GBP208/12/G016 Grant - others:Operational Program Research and Development for Innovations(XE) CZ.1.05/2.1.00/03.0058 Institutional support: RVO:61388963 Keywords : dispersion * electrostatics * halogen bonding * noncovalent interactions Subject RIV: CE - Biochemistry Impact factor: 1.867, year: 2013

  12. Pedagogical Agents as Learning Companions: The Role of Agent Competency and Type of Interaction

    OpenAIRE

    Kim, Yanghee; Baylor, Amy L.; PALS Group,

    2006-01-01

    This study was designed to examine the effects of the competency (low vs. high) and interaction type (proactive vs. responsive) of pedagogical agents as learning companions (PALs) on learning, self-efficacy, and attitudes. Participants were 72 undergraduates in an introductory computer-literacy course who were randomly assigned to one of four treatments: Low-Proactive, Low-Responsive, High-Proactive, and High-Responsive. Results indicated a main effect for PAL competency. Students who worked ...

  13. Probing the role of backbone hydrogen bonds in protein-peptide interactions by amide-to-ester mutations

    DEFF Research Database (Denmark)

    Eildal, Jonas N N; Hultqvist, Greta; Balle, Thomas

    2013-01-01

    -protein interactions, those of the PDZ domain family involve formation of intermolecular hydrogen bonds: C-termini or internal linear motifs of proteins bind as β-strands to form an extended antiparallel β-sheet with the PDZ domain. Whereas extensive work has focused on the importance of the amino acid side chains...... of the protein ligand, the role of the backbone hydrogen bonds in the binding reaction is not known. Using amide-to-ester substitutions to perturb the backbone hydrogen-bonding pattern, we have systematically probed putative backbone hydrogen bonds between four different PDZ domains and peptides corresponding...... to natural protein ligands. Amide-to-ester mutations of the three C-terminal amides of the peptide ligand severely affected the affinity with the PDZ domain, demonstrating that hydrogen bonds contribute significantly to ligand binding (apparent changes in binding energy, ΔΔG = 1.3 to >3.8 kcal mol(-1...

  14. Computer Agent's Role in Modeling an Online Math Help User

    OpenAIRE

    Dragana Martinovic

    2007-01-01

    This paper investigates perspectives of deployments of open learner model on mathematics online help sites. It proposes enhancing a regular human-to-human interaction with an involvement of a computer agent suitable for tracking users, checking their input and making useful suggestions. Such a design would provide the most support for the interlocutors while keeping the nature of existing environment intact. Special considerations are given to peer-to-peer and expert-to-student mathematics on...

  15. Shear bond strength of composite to deep dentin after treatment with two different collagen cross-linking agents at varying time intervals.

    Science.gov (United States)

    Srinivasulu, S; Vidhya, S; Sujatha, M; Mahalaxmi, S

    2012-01-01

    This in vitro study evaluated the shear bond strength of composite resin to deep dentin using a total etch adhesive after treatment with two collagen cross-linking agents at varying time intervals. Thirty freshly extracted human maxillary central incisors were sectioned longitudinally into equal mesial and distal halves (n=60). The proximal deep dentin was exposed, maintaining a remaining dentin thickness (RDT) of approximately 1 mm. The specimens were randomly divided into three groups based on the surface treatment of dentin prior to bonding as follows: group I (n=12, control): no prior dentin surface treatment; group II (n=24): dentin surface pretreated with 10% sodium ascorbate; and group III (n=24): dentin surface pretreated with 6.5% proanthocyanidin. Groups II and III were further subdivided into two subgroups of 12 specimens each, based on the pretreatment time of five minutes (subgroup A) and 10 minutes (subgroup B). Shear bond strength of the specimens was tested with a universal testing machine, and the data were statistically analyzed. Significantly higher shear bond strength to deep dentin was observed in teeth treated with 10% sodium ascorbate (group II) and 6.5% proanthocyanidin (group III) compared to the control group (group I). Among the collagen cross-linkers used, specimens treated with proanthocyanidin showed significantly higher shear bond strength values than those treated with sodium ascorbate. No significant difference was observed between the five-minute and 10-minute pretreatment times in groups II and III. It can be concluded that dentin surface pretreatment with both 10% sodium ascorbate and 6.5% proanthocyanidin resulted in significant improvement in bond strength of resin composite to deep dentin.

  16. Role of contact bonding on electronic transport in metal-carbon nanotube-metal systems

    International Nuclear Information System (INIS)

    Deretzis, I; La Magna, A

    2006-01-01

    We have investigated the effects of the interfacial bond arrangement on the electronic transport features of metal-nanotube-metal systems. The transport properties of finite, defect-free armchair and zigzag single-walled carbon nanotubes attached to Au(111) metallic contacts have been calculated by means of the non-equilibrium Green functional formalism with the tight-binding and the extended Hueckel Hamiltonians. Our calculations show that the electrode material is not the only factor which rules contact transparency. Indeed, for the same electrode, but changing nanotube helicities, we have observed an overall complex behaviour of the transmission spectra due to band mixing and interference. A comparison of the two models shows that the tight-binding approach fails to give a satisfactory representation of the transmission function when a more accurate description of the C-C and Au-C chemical bonds has to be considered. We have furthermore examined the effect of interface geometry variance on conduction and found that the contact-nanotube distance has a significant impact, while the contact-nanotube symmetry plays a marginal, yet evident role

  17. The Relationship Between Perceived Parental Bonding and Bullying: The Mediating Role of Empathy

    Directory of Open Access Journals (Sweden)

    Effrosyni Mitsopoulou

    2013-03-01

    Full Text Available Despite the importance of parenting in the development of empathy in children as well as their involvement in bullying behaviours, no study has ever examined the mediating role of empathy in the relationship between parental bonding and bullying and victimization. The present study aims in examining these relationships. Participants included 504 children (255 boys, 246 girls from different primary schools of Crete. The standard version of the Peer Experiences Questionnaire was used to assess experiences in bullying behaviours, the Parental Bonding Instrument was used to assess self-reported sense of care and overprotection from the mother and father separately, whereas empathy was assessed using the Greek version of Bryant’s Empathy Index. A series of multiple regression analyses were conducted. Results showed that boys scored significantly higher on average with respect to Victimisation of Others, and girls scored higher to specific sub-factors of empathy. It was also found that in the case of Care Mother, Sadness and Understanding of Feelings were significant mediators of Victimization of Others. Further, in the subsample of boys it was revealed that Sadness and Understanding of Feelings were significant mediators of the relationship between Care Mother and Victimization of Others. Implications for counselling interventions are also discussed.

  18. New conception in the theory of chemical bonding; the role of core and valence atomic orbitals in formation of chemical bonds

    International Nuclear Information System (INIS)

    Kostikova, G.P.; Kostikov, Yu.P.; Korol'kov, D.V.

    1986-01-01

    An analysis of x-ray photoelectron spectra leads to a simple and consistent conception in the theory of chemical bonding, which satisfies (unlike the simple MO-LCAO theory) the virial theorem and defines the roles of the core and valence atomic orbitals in the formation of chemical bonds. Its essence is clear from the foregoing: the exothermic effects of the formation of complexes are caused by the lowering of the energies of the core levels of the central atoms with simultaneous small changes in the energies of the core levels of the ligands despite the significant destabilization of the delocalized valence MO's in comparison to the orbital energies of the corresponding free atoms. In order to confirm these ideas, they recorded the x-ray photoelectron spectra of the valence region and the inner levels of single-crystal silicon carbide, silicon, and graphite

  19. Computer Agent's Role in Modeling an Online Math Help User

    Directory of Open Access Journals (Sweden)

    Dragana Martinovic

    2007-06-01

    Full Text Available This paper investigates perspectives of deployments of open learner model on mathematics online help sites. It proposes enhancing a regular human-to-human interaction with an involvement of a computer agent suitable for tracking users, checking their input and making useful suggestions. Such a design would provide the most support for the interlocutors while keeping the nature of existing environment intact. Special considerations are given to peer-to-peer and expert-to-student mathematics online help that is free of charge and asynchronous. Examples from other collaborative, Web-based environments are also discussed. Suggestions for improving the existing architectures are given, based on the results of a number of studies on on-line learning systems.

  20. Pull-out bond strength of a self-adhesive resin cement to NaOCl-treated root dentin: effect of antioxidizing agents

    Directory of Open Access Journals (Sweden)

    Maryam Khoroushi

    2014-05-01

    Full Text Available Objectives This study evaluated the effect of three antioxidizing agents on pull-out bond strengths of dentin treated with sodium hypochlorite. Materials and Methods Root canals of 75 single-rooted human teeth were prepared. Fifteen teeth were irrigated with normal saline for a negative control group, and the remaining 60 teeth (groups 2 - 5 with 2.5% NaOCl. The teeth in group 2 served as a positive control. Prior to post cementation, the root canals in groups 3 - 5 were irrigated with three antioxidizing agents including 10% rosmarinic acid (RA, Baridge essence, 10% hesperidin (HPN, Sigma, and 10% sodium ascorbate hydrogel (SA, AppliChem. Seventy-five spreaders (#55, taper .02, Produits Dentaires S.A were coated with silica and silanized with the Rocatec system and ceramic bond. All the prepared spreaders were cemented with a self-adhesive resin cement (Bifix SE, Voco Gmbh in the prepared canals. After storage in distilled water (24 h/37℃, the spreaders were pulled out in a universal testing machine at a crosshead speed of 1.0 mm/min. Pull-out strength values were analyzed by one-way ANOVA and Tukey's HSD test (α = 0.05. Results There were significant differences between study groups (p = 0.016. The highest pull-out strength was related to the SA group. The lowest strength was obtained in the positive control group. Conclusions Irrigation with NaOCl during canal preparation decreased bond strength of resin cement to root dentin. Amongst the antioxidants tested, SA had superior results in reversing the diminishing effect of NaOCl irrigation on the bond strength to root dentin.

  1. Role of Monomer Sequence, Hydrogen Bonding and Mesoscale Architecture in Marine Antifouling Coatings

    Science.gov (United States)

    Segalman, Rachel

    Polypeptoids are non-natural, sequence specific polymers that offer the opportunity to probe the effect of monomer sequence, chirality, and chain shape on self-assembly and surface properties. Additionally, polypeptoid synthesis is more scaleable than traditional polypeptides suggesting their utility in large area applications. We have designed efficient marine anti-fouling coatings by using triblock copolymer scaffolds to which polypeptoids are tethered in order to tune both the modulus and surface energies with great precision. Surprisingly, when short sequences are tethered to a polymer backbone, polypeptoids consistently outperform analogous polypeptides in antifouling properties. We hypothesize that the hydrogen bonding inherent to the polypeptide backbone drives the observed differences in performance. We also find that the polymer scaffold housing the polypeptoids also plays a crucial role in directing surface presentation and therefore the overall coating properties.

  2. The Role of Hydrogen Bonds Of The Azeotropic Hydrous Ethanol Fuel Composition To The Exhaust Emissions

    Science.gov (United States)

    Made Suarta, I.; Nyoman Gede Baliarta, I.; Sopan Rahtika, I. P. G.; Wijaya Sunu, Putu

    2018-01-01

    In this study observed the role of hydrogen bonding to the composition of exhaust emissions which is produced hydrous ethanol fuel (95.5% v). Testing is done by using single cylinder four stroke motor engine. The composition of exhaust gas emissions is tested using exhaust gas analyzer on lean and stoichiometry mixer. The exhaust emissions produced by anhydrous ethanol were also tested. The composition of emissions produced by that two fuels is compared. The results showed CO emissions levels produced by hydrous ethanol are slightly higher than anhydrous ethanol in stoichiometric mixtures. But the composition of CO hydrous ethanol emissions is lower in the lean mix. If lean the mixer the different in the composition of emissions is increasing. On hydrous ethanol emission CO2 content little bit lower on the stoichiometric mixer and higher on the lean mixture. Exhaust emissions of ethanol fuel also produce O2. O2 hydrous ethanol emissions is higher than anhydrous ethanol fuel.

  3. Role of Socializing Agents in Female Sport Involvement

    Science.gov (United States)

    Greendorfer, Susan L.

    1977-01-01

    Research into the socializing of women into sports activities revealed that peers were most influential at all life-cycle stages, family was the most influential during childhood, and coaches and teachers during adolescence; in addition, males were the predominant role models during childhood, and females during adolescence and adult life. (MB)

  4. Effects of Maternal Anxiety Disorders on Infant Self-Comforting Behaviors: The Role of Maternal Bonding, Infant Gender and Age.

    Science.gov (United States)

    Müller, Mitho; Tronick, Ed; Zietlow, Anna-Lena; Nonnenmacher, Nora; Verschoor, Stephan; Träuble, Birgit

    We investigated the links between maternal bonding, maternal anxiety disorders, and infant self-comforting behaviors. Furthermore, we looked at the moderating roles of infant gender and age. Our sample (n = 69) comprised 28 mothers with an anxiety disorder (according to DSM-IV criteria) and 41 controls, each with their 2.5- to 8-month-old infant (41 females and 28 males). Infant behaviors were recorded during the Face-to-Face Still-Face paradigm. Maternal bonding was assessed by the Postpartum Bonding Questionnaire. Conditional process analyses revealed that lower maternal bonding partially mediated between maternal anxiety disorders and increased self-comforting behaviors but only in older female infants (over 5.5 months of age). However, considering maternal anxiety disorders without the influence of bonding, older female infants (over 5.5 months of age) showed decreased rates of self-comforting behaviors, while younger male infants (under 3 months of age) showed increased rates in the case of maternal anxiety disorder. The results suggest that older female infants (over 5.5 months of age) are more sensitive to lower maternal bonding in the context of maternal anxiety disorders. Furthermore, results suggest a different use of self-directed regulation strategies for male and female infants of mothers with anxiety disorders and low bonding, depending on infant age. The results are discussed in the light of gender-specific developmental trajectories. © 2016 S. Karger AG, Basel.

  5. The Role of Inflation-Linked Bonds. Increasing, but Still Modest

    NARCIS (Netherlands)

    Westerhout, Ed; Ciocyte, Ona

    2017-01-01

    Although the market for inflation-linked bonds has expanded enormously, nominal bonds are still the main instrument to finance public debts. This paper seeks to explain why. It focuses on the Eurozone countries for which the standard argument that inflation-linked bonds may help to reduce inflation

  6. Early biofilm formation and the effects of antimicrobial agents on orthodontic bonding materials in a parallel plate flow chamber

    NARCIS (Netherlands)

    Chin, Yeen; Busscher, HJ; Evans, R; Noar, J; Pratten, J

    Decalcification is a commonly recognized complication of orthodontic treatment with fixed appliances. A technology, based on a parallel plate flow chamber, was developed to investigate early biofilm formation of a strain of Streptococcus sanguis on the surface of four orthodontic bonding materials:

  7. Reactions of 4-nitro-1,2,3-triazole with alkylating agents and compounds with activated multiple bonds

    Energy Technology Data Exchange (ETDEWEB)

    Vereshchagin, L.I.; Kuznetsova, N.I.; Kirillova, L.P.; Shcherbakov, V.V.; Sukhanov, G.T.; Gareev, G.A.

    1987-01-01

    When 4-nitro-1,2,3-triazole is alkylated, a mixture of N1- and N2-isomers is formed, with the latter usually predominating. The same behavior is also observed in addition reactions of 4-nitrotriazole to activated multiple bonds.

  8. Effect of composite resin placement techniques on the microleakage of two self-etching dentin-bonding agents.

    NARCIS (Netherlands)

    Santini, A.; Plasschaert, A.J.M.; Mitchell, S.M.

    2001-01-01

    PURPOSE: To evaluate microleakage of Class V resin-based composites (RBC) bonded with two self-etching dentin adhesive systems. Class V cavities were restored with either one or three increments of RBC to determine whether the restorative method affected microleakage. MATERIALS AND METHODS: 60

  9. Role of the H bond network in the radiation chemistry of hydrated systems

    International Nuclear Information System (INIS)

    Pommeret, S.; Renault, J.P.; Le Caer, S.; Vigneron, G.; Palmer, J.; Lima, M.; Righini, R.

    2006-01-01

    Introduction: In the present contribution, we want to address the influence of the H bond network on the observed reactivity of hydrated system. In radiation chemistry the primary species appear extremely simple and at the same time are very reactive. The comprehension of their dynamics is rather difficult since their reactivity involves the solvent molecules as reactant. Some of those species like the hydrated electron and the proton are highly hydrophilic, while others like the hydroxide radical and the H atom are rather hydrophobic. Both the hydrated electron and the H atom locate near a defect of the H bond network i.e. a cavity. As an example of the role of the environment in radical chemistry, when studying the radiation chemistry of porous media we noticed that the interface play a crucial role in the outcome of that chemistry. More particularly we observed that the silanol band of the silica/water interface was strongly affected by the irradiation even so no energy is directly absorbed by an interface. In this contribution, we will first review the recent work on the H bond dynamics, in absence of any reactant. We will then present recent results on the radiation chemistry of nanoporous media and its influence on the H bond network of an interface and will also present recent results obtained on the H bond dynamics at an alumina-water interface. All those results will be discussed in light of the H bonded nature of neat water. Radiation chemistry of an H bonded interface: A Fourier transformed infrared detection associated to an electron accelerator was developed so as to characterise in situ the effects of irradiation on various systems. The FT-IR spectrometer and the detector were moved out of the accelerator room to be protected against radiation. The infrared beam was guided on a distance of 6 meters by optical conduits and mirrors. The spectra were obtained from 100 scans accumulated with a Bruker Vertex 70 equipment operating with a 4 cm -1 resolution

  10. Programming secure mobile agents in healthcare environments using role-based permissions.

    Science.gov (United States)

    Georgiadis, C K; Baltatzis, J; Pangalos, G I

    2003-01-01

    The healthcare environment consists of vast amounts of dynamic and unstructured information, distributed over a large number of information systems. Mobile agent technology is having an ever-growing impact on the delivery of medical information. It supports acquiring and manipulating information distributed in a large number of information systems. Moreover is suitable for the computer untrained medical stuff. But the introduction of mobile agents generates advanced threads to the sensitive healthcare information, unless the proper countermeasures are taken. By applying the role-based approach to the authorization problem, we ease the sharing of information between hospital information systems and we reduce the administering part. The different initiative of the agent's migration method, results in different methods of assigning roles to the agent.

  11. Effects of at-home and in-office bleaching agents on the shear bond strength of metal, ceramic, and composite brackets to enamel.

    Science.gov (United States)

    Rahul, M; Kumar, P Anil; Nair, Amal S; Mathew, Shino; Amaladas, Antony Shijoy; Ommen, Anna

    2017-01-01

    This study aimed to evaluate the effects of at-home and in-office bleaching on the shear bond strength (SBS) of metal, ceramic, and composite orthodontic brackets and to compare their SBSs. A total of 96 human lower premolar teeth were used for this study. Six teeth were used for scanning electron microscopic study while the remaining ninety were divided into three equal groups. Each group was further subdivided into three subgroups with ten samples each. Three protocols were used. In the at-home bleaching group (n = 30), opalescence non-PF (potassium nitrate and fluoride) bleaching agent (10% carbamide peroxide) was applied onto the teeth daily for 14 days and left for 8 h each day. Teeth in the in-office group (n = 30) were treated twice in consecutive days with Opalescence boost PF (40% hydrogen peroxide). After bleaching, the specimens were stored in distilled water for 1 day before bonding. SBS testing was performed on all teeth using Instron universal testing machine. Analysis of variance indicated a significant difference (P brackets in control group (Ib) and minimum was shown by composite brackets of in-office bleached group (IIIc). The results showed that at-home bleaching did not affect the SBS significantly whereas in-office bleaching reduced SBS of metal, ceramic, and composite brackets significantly. It is preferable to use metal or ceramic brackets than composite brackets for bonding 24 h after bleaching.

  12. Role of sodium tungstate as a potential antiplatelet agent

    Directory of Open Access Journals (Sweden)

    Fernández-Ruiz R

    2015-05-01

    slightly this response. In human blood, a dose-dependent effect was observed. At 200 µM, closure times in the PFA-100 were prolonged. On denuded vessels, %SC and thrombi formation (%T decreased with Na2O4W. Neither the aggregating response nor the viscoelastic clot properties were affected.Conclusion: Na2O4W decreases consistently the hemostatic capacity of platelets, inhibiting their adhesive and cohesive properties under flow conditions in mice and in human blood, resulting in smaller thrombi. Although Na2O4W may be acting on platelet PTP1B, other potential targets should not be disregarded. Keywords: sodium tungstate, protein tyrosine phosphatase 1B, platelet adhesion, antiplatelet agents

  13. Mechanism of conformational coupling in SecA: Key role of hydrogen-bonding networks and water interactions.

    Science.gov (United States)

    Milenkovic, Stefan; Bondar, Ana-Nicoleta

    2016-02-01

    SecA uses the energy yielded by the binding and hydrolysis of adenosine triphosphate (ATP) to push secretory pre-proteins across the plasma membrane in bacteria. Hydrolysis of ATP occurs at the nucleotide-binding site, which contains the conserved carboxylate groups of the DEAD-box helicases. Although crystal structures provide valuable snapshots of SecA along its reaction cycle, the mechanism that ensures conformational coupling between the nucleotide-binding site and the other domains of SecA remains unclear. The observation that SecA contains numerous hydrogen-bonding groups raises important questions about the role of hydrogen-bonding networks and hydrogen-bond dynamics in long-distance conformational couplings. To address these questions, we explored the molecular dynamics of SecA from three different organisms, with and without bound nucleotide, in water. By computing two-dimensional hydrogen-bonding maps we identify networks of hydrogen bonds that connect the nucleotide-binding site to remote regions of the protein, and sites in the protein that respond to specific perturbations. We find that the nucleotide-binding site of ADP-bound SecA has a preferred geometry whereby the first two carboxylates of the DEAD motif bridge via hydrogen-bonding water. Simulations of a mutant with perturbed ATP hydrolysis highlight the water-bridged geometry as a key structural element of the reaction path. Copyright © 2015. Published by Elsevier B.V.

  14. An evaluation on microleakage and gap width of different dentin bonding agents in high copper amalgam restorations

    Directory of Open Access Journals (Sweden)

    Ghavam-Nasiri M. Associate Professor

    2003-07-01

    Full Text Available Statement of Problem: A lot of efforts have been made to create a complete adaptation between tooth"nand amalgam restorations."nPurpose: The aim of this study was to evaluate microleakage and interfacial micromorphology of"namalgam restorations lined with dentin adhesives, namely One Coat Bond, Syntac, Excite and Copalite,"nas liners."nMaterials and Methods: 144 intact human canine teeth were selected. Then class V cavities, with"nenamel and dentinal margins, were prepared on each of them. Cavities were lined with different dentin"nbonding systems (Syntac, One Coat Bond and Excite according to the manufacturer's instructions and"nrestored with Oralloy and Cinalloy, non gamma 2 spherical amalgams and Aristaloy a non gamma 2"nAdmixed alloy. Copalite was used in the group, served as controls. After thirty days storage in synthetic"nsaliva at 37°c, the specimens were thermocycled in saliva (4000 cycles. The degree of microleakage was"nassessed by means of basic fushin dye penetration and recorded. The gap width was evaluated with"nScanning Electron Microscope. Pearson and %2 tests were used to analyze the results."nResults: None of the systems, tested in this study, eliminated microleakage completely, Pearson's"ncorrelation coefficient showed a positive correlation between gap and microleakage (P<0/05.Statistical"nsignificant differences were revealed among the liners regarding gap and microleakage (P<0.05."nOne Coat Bond and Syntac appeared to leak less than other groups. The gap width by One Coat Bond"nand Syntac were respectively 0.35 and 0.3 urn in dentine, 0.2 and 0.1 in enamel. Excite and copalite gap"nwidth in dentine and enamel were 1,3-1.36 urn and 0.3-0.6, respectively. The type of amalgam did not"nhave any effect in the degree of microleakage and gap width (P>0/05."nConclusion: One Coat Bond and Syntac, comparing to Excite and Copalite, showed less microleakage"nand gap width.

  15. ANTIOXIDANT AGENTS: THEIR ROLE IN NUTRITION AND HEALTH OF ATHLETS.

    Directory of Open Access Journals (Sweden)

    Ana Paula Gerin Fanhani e Márcia Pires Ferreira

    2006-12-01

    Full Text Available Physical exercise, when practiced with moderation, proporcionates organic benefits. However, physical activities, which exceed physiological limits, promote an increase in production of oxygen free radicals. These radicals, when not neutralized, may initiate a deleterious process in cells and tissues, named oxidative stress. This degenerative process may originate different illnesses and, moreover, it seems to play an important role in the process of early aging. This study aimed to evaluate the consumption levels of food that contains antioxidants and the knowledge about its benefits among athletes, practitioners of different sportive modalities, of both sexes, in Umuarama-Paraná. A form containing four questions and an alimentary consumption frequency table was used. Were included in the study 11 men (22 to 30 years and 10 women (18 to 22 years, all of them had the sport as a professional activity. It was observed that the athletes do not possess enough information about the action mechanisms of antioxidant substances in organism, as well as about its effect in the prevention of illnesses and early aging. Considering the frequency of antioxidant food consumption, 70% of the male athletes rarely ingest selenium and flavonoids, 50% rarely ingest vitamin E. Among female athletes, 73% and 55% rarely consume selenium and flavonoids, respectively. Thus, this research evidences the need to inform athletes about the importance of varied and balanced feeding that includes antioxidant foods in their day-by-day, preventing chronic illnesses and early aging.

  16. The role of the autonomic nervous system in hypertension: a bond graph model study

    International Nuclear Information System (INIS)

    Chen, Shuzhen; Gong, Yuexian; Dai, Kaiyong; Sui, Meirong; Yu, Yi; Ning, Gangmin; Zhang, Shaowen

    2008-01-01

    A bond graph model of the cardiovascular system with embedded autonomic nervous regulation was developed for a better understanding of the role of the autonomic nervous system (ANS) in hypertension. The model is described by a pump model of the heart and a detailed representation of the head and neck, pulmonary, coronary, abdomen and extremity circulation. It responds to sympathetic and parasympathetic activities by modifying systemic peripheral vascular resistance, heart rate, ventricular end-systolic elastance and venous unstressed volumes. The impairment of ANS is represented by an elevation of the baroreflex set point. The simulation results show that, compared with normotensive, in hypertension the systolic and diastolic blood pressure (SBP/DBP) rose from 112/77 mmHg to 144/94 mmHg and the left ventricular wall thickness (LVWT) increased from 10 mm to 12.74 mm. In the case that ANS regulation was absent, both the SBP and DBP further increased by 8 mmHg and the LVWT increased to 13.22 mm. The results also demonstrate that when ANS regulation is not severely damaged, e.g. the baroreflex set point is 97 mmHg, it still has an effect in preventing the rapid rise of blood pressure in hypertension; however, with the worsening of ANS regulation, its protective role weakens. The results agree with human physiological and pathological features in hemodynamic parameters and carotid baroreflex function curves, and indicate the role of ANS in blood pressure regulation and heart protection. In conclusion, the present model may provide a valid approach to study the pathophysiological conditions of the cardiovascular system and the mechanism of ANS regulation

  17. Evaluating the effect of dentin surface pretreatment on the static contact angle of a drop of a bonding agent: an in vitro study

    Directory of Open Access Journals (Sweden)

    Mehrdad Barekatain

    2016-03-01

    Full Text Available Introduction: The aim of this study was to investigate the effect of dentinal pretreatment on the static contact angle of a bonding agent as a measure of dentin surface wettability. Materials &Methods: Twenty mid-coronal dentin surfaces were prepared and randomly allocated to four groups (n=5 according to the priming solutions. All segments were etched with 35% phosphoric acid gel for 15 s, rinsed for 30 s and dried. Each group was rehydrated with 10 µL of distilled water, 0.2 % chlorhexidine, 70% ethanol and 5.25% Sodium Hypochlorite respectively and the excess solution was removed after 60 sec using an absorbent paper. Using a micro syringe, a droplet of the Adper Single Bond 2 was placed on each prepared surface. Then the profile and the static contact angle of the droplet were analyzed with a video-based optical contact angle measuring system. The statistical analysis was performed using One-way ANOVA and Dunnett’s t tests (p<0.05. Results: There was a statistically significant difference between the water and sodium hypochlorite groups which indicates the negative effect sodium hypochlorite may have on dentinal surface energy. (p=0.013. The differences between the water and ethanol groups (p=0.168 and between the water and chlorhexidine groups (p=0.665 were not significant. Conclusion: The use of 5.25% sodium hypochlorite as a priming solution in bonding procedure is not recommended. There is no improvement in dentinal surface wettability by using 70% ethanol or 0.2% chlorhexidine instead of water and the recommendation for use of any of the two should be based on other long-term or short-term effects they may have on the bonding procedure.

  18. Bonding to new CAD/CAM resin composites: influence of air abrasion and conditioning agents as pretreatment strategy.

    Science.gov (United States)

    Reymus, Marcel; Roos, Malgorzata; Eichberger, Marlis; Edelhoff, Daniel; Hickel, Reinhard; Stawarczyk, Bogna

    2018-04-27

    Because of their industrially standardized process of manufacturing, CAD/CAM resin composites show a high degree of conversion, making a reliable bond difficult to achieve. The purpose of this experiment was to investigate the tensile bond strength (TBS) of luting composite to CAD/CAM resin composite materials as influenced by air abrasion and pretreatment strategies. The treatment factors of the present study were (1) brand of the CAD/CAM resin composite (Brilliant Crios [Coltene/Whaledent], Cerasmart [GC Europe], Shofu Block HC [Shofu], and Lava Ultimate [3M]); (2) air abrasion vs. no air abrasion; and (3) pretreatment using a silane primer (Clearfil Ceramic Primer, Kuraray) vs. a resin primer (One Coat 7 Universal, Coltene/Whaledent). Subsequently, luting composite (DuoCem, Coltene/Whaledent) was polymerized onto the substrate surface using a mold. For each combination of the levels of the three treatment factors (4 (materials) × 2 (air abrasion vs. no air abrasion; resin) × 2 (primer vs. silane primer)), n = 15, specimens were prepared. After 24 h of water storage at 37 °C and 5000 thermo-cycles (5/55 °C), TBS was measured and failure types were examined. The resulting data was analyzed using Kaplan-Meier estimates of the cumulative failure distribution function with Breslow-Gehan tests and non-parametric ANOVA (Kruskal-Wallis test) followed by the multiple pairwise Mann-Whitney U test with α-error adjustment using the Benjamini-Hochberg procedure and chi-square test (p CAD/CAM resin composites, the restorations should be air abraded and pretreated using a resin primer containing methyl-methacrylate to successfully bond to the luting composite. The pretreatment of the CAD/CAM resin composite using merely a silane primer results in deficient adhesion. For a reliable bond of CAD/CAM resin composites to the luting composite, air abrasion and a special pretreatment strategy are necessary in order to achieve promising long-term results.

  19. Role of bond adaptability in the passivation of colloidal quantum dot solids.

    Science.gov (United States)

    Thon, Susanna M; Ip, Alexander H; Voznyy, Oleksandr; Levina, Larissa; Kemp, Kyle W; Carey, Graham H; Masala, Silvia; Sargent, Edward H

    2013-09-24

    Colloidal quantum dot (CQD) solids are attractive materials for photovoltaic devices due to their low-cost solution-phase processing, high absorption cross sections, and their band gap tunability via the quantum size effect. Recent advances in CQD solar cell performance have relied on new surface passivation strategies. Specifically, cadmium cation passivation of surface chalcogen sites in PbS CQDs has been shown to contribute to lowered trap state densities and improved photovoltaic performance. Here we deploy a generalized solution-phase passivation strategy as a means to improving CQD surface management. We connect the effects of the choice of metal cation on solution-phase surface passivation, film-phase trap density of states, minority carrier mobility, and photovoltaic power conversion efficiency. We show that trap passivation and midgap density of states determine photovoltaic device performance and are strongly influenced by the choice of metal cation. Supported by density functional theory simulations, we propose a model for the role of cations, a picture wherein metals offering the shallowest electron affinities and the greatest adaptability in surface bonding configurations eliminate both deep and shallow traps effectively even in submonolayer amounts. This work illustrates the importance of materials choice in designing a flexible passivation strategy for optimum CQD device performance.

  20. Role of bond adaptability in the passivation of colloidal quantum dot solids

    KAUST Repository

    Thon, Susanna

    2013-09-24

    Colloidal quantum dot (CQD) solids are attractive materials for photovoltaic devices due to their low-cost solution-phase processing, high absorption cross sections, and their band gap tunability via the quantum size effect. Recent advances in CQD solar cell performance have relied on new surface passivation strategies. Specifically, cadmium cation passivation of surface chalcogen sites in PbS CQDs has been shown to contribute to lowered trap state densities and improved photovoltaic performance. Here we deploy a generalized solution-phase passivation strategy as a means to improving CQD surface management. We connect the effects of the choice of metal cation on solution-phase surface passivation, film-phase trap density of states, minority carrier mobility, and photovoltaic power conversion efficiency. We show that trap passivation and midgap density of states determine photovoltaic device performance and are strongly influenced by the choice of metal cation. Supported by density functional theory simulations, we propose a model for the role of cations, a picture wherein metals offering the shallowest electron affinities and the greatest adaptability in surface bonding configurations eliminate both deep and shallow traps effectively even in submonolayer amounts. This work illustrates the importance of materials choice in designing a flexible passivation strategy for optimum CQD device performance. © 2013 American Chemical Society.

  1. Watson-Crick hydrogen bonds : Nature and role in DNA replication

    NARCIS (Netherlands)

    Guerra, Célia Fonseca; Bickelhaupt, F. Matthias

    2006-01-01

    The hydrogen bonds in DNA Watson–Crick base pairs have long been considered predominantly electrostatic phenomena. In this chapter, we show with state-of-the-art calculations that this is not true and that electrostatic interactions and covalent contributions in these hydrogen bonds are in fact of

  2. The role of hydrogen bonds in the melting points of sulfonate-based protic organic salts

    DEFF Research Database (Denmark)

    Luo, Jiangshui

    2016-01-01

    There are three main types of interactions inside organic salts - electrostatic interaction, hydrogen bonding and van der Waals force [1-4]. While van der Waals force is relatively weak, it is hydrogen bonding and particularly electrostatic interaction that determine the lattice energies of ionic...

  3. Role of the H bond network in the radiation chemistry of hydrated systems

    International Nuclear Information System (INIS)

    Pommeret, S.; Renault, J.P.; Caeer, S.Le; Vigneron, G.; Vuilleumier, R.; Bratos, S.; Leicknam, J.Cl.

    2006-01-01

    In the present contribution a review of the recent work on the H bond dynamics, in absence of any reactant and a new theory that unambiguously establishes a new link between spectroscopic observation and geometric properties is presented, along with results on the radiation chemistry of nanoporous media and its influence on the H bond network of an interface

  4. A Look at the Roles of Look & Roles in Embodied Pedagogical Agents--A User Preference Perspective

    Science.gov (United States)

    Haake, Magnus; Gulz, Agneta

    2009-01-01

    The paper presents a theoretical framework addressing three aspects of embodied pedagogical agents: visual static appearance, pedagogical role, and communicative style. The framework is then applied to a user study where 90 school children (aged 12-15) in a dummy multimedia program were presented with either an instructor or a learning companion…

  5. The role of independent agents in the success of health insurance market reforms.

    Science.gov (United States)

    Hall, M A

    2000-01-01

    The impact of reforms on the health insurance markets cannot be understood without more information about the role played by insurance agents and a closer analysis of their contribution. An in-depth, qualitative study of insurance-market reforms in seven illustrative states forms the basis for this report on how agents help to shape the efficiency and fairness of insurance markets. Different types of agents relate to insurers in their own ways and are compensated differently. This study shows agents to be almost uniformly enthusiastic about guaranteed-issue requirements and other components of market reforms. Although insurers devise strategies for manipulating agents in order to avoid undesirable business, these opportunities are limited and do not appear to be seriously undermining the effectiveness of market reforms. Despite the layer of cost that agents add to the system, they play an important role in making market reforms work, and they fill essential information and service functions for which many purchasers have no ready substitute.

  6. Comparative study on the tensile bond strength and marginal fit of complete veneer cast metal crowns using various luting agents: An in vitro study

    Directory of Open Access Journals (Sweden)

    B Devi Parameswari

    2016-01-01

    Full Text Available Introduction: Several commercially available luting agents are used to cement the dental restorations such as intra-coronal, extra-coronal, and fixed partial dentures. Tensile bond strength (TBS and accurate marginal fit are the essential factors to determine the good clinical results in fixed prosthesis. The retentivity of the luting cements is assessed by their adhesive capacity over the tooth surface and metal surface. Generally, the adhesive ability has been evaluated with in vitro testing, with tensile bond tests. The failure of fixed prosthesis may be happened as a result of incomplete seating during cementation. Most research on cementation of crowns relates seating failure to the thickness of the cement film. Materials and Methods: The study is divided into four groups with 10 samples for each of the luting cement taken up for testing TBS and four groups with 5 samples for each luting agent chosen for assessing marginal fit. The results were tabulated and statistically analyzed. Results: In this in vitro study, the TBS of luting cements, and marginal fit in relation to luting cements were tested by using appropriate testing devices. The TBS of cement is measured using universal testing machine, and the results are tabulated. The marginal gap that exists between the margin of the cast metal crown, and the finish line is measured using travelling microscope before and after cementation. The difference between these two values gives the discrepancy that is due to the film thickness of cement used for luting the restoration. Summary and Conclusion: The TBS value of zinc phosphate cement and glass ionomer cement were found to be almost same. The chemical adhesiveness of the glass ionomer with calcium ions of enamel and dentin may be the attributed reason (ionic bonding. In this study, the polycarboxylate is the one that showed low TBS, and it may be attributed to the weakness of the cement due to reduced film thickness, though this cement has

  7. Exploration of agent of change’s role in biodiesel energy transition process using agent-based model

    Science.gov (United States)

    Hidayatno, A.; Vicky, L. R.; Destyanto, A. R.

    2017-11-01

    As the world’s largest Crude Palm Oil (CPO) producer, Indonesia uses CPO as raw material for biodiesel. A number of policies have been designed by the Indonesian government to support adoption of biodiesel. However, the role of energy alternatives faced complex problems. Agent-based modeling can be applied to predict the impact of policies on the actors in the business process to acquire a rich discernment of the behavior and decision making by the biodiesel industries. This study evaluates government policy by attending at the adoption of the biodiesel industry in the tender run by a government with the intervention of two policy options biodiesel energy utilization by developing an agent-based model. The simulation result show that the policy of adding the biodiesel plant installed capacity has a good impact in increasing the production capacity and vendor adoption in the tender. Even so, the government should consider the cost to be incurred and the profits for vendors, so the biodiesel production targets can be successfully fulfilled.

  8. POSTPARTUM BONDING DIFFICULTIES AND ADULT ATTACHMENT STYLES: THE MEDIATING ROLE OF POSTPARTUM DEPRESSION AND CHILDBIRTH-RELATED PTSD.

    Science.gov (United States)

    S Hairston, Ilana; E Handelzalts, Jonathan; Assis, Chen; Kovo, Michal

    2018-03-01

    Despite decades of research demonstrating the role of adult attachment styles and early mother-infant bonding in parenting behaviors and maternal mental health, these constructs have seldom been studied together. The present study aimed to investigate the relationship between attachment styles and specific bonding difficulties of mothers. In addition, as postpartum depression and childbirth-related posttraumatic stress symptoms have been associated with both constructs, we explored their possible mediation effect. One hundred fourteen mothers, 4 to 12 weeks' postpartum, completed a demographic questionnaire, the Adult Attachment Style Questionnaire (M. Mikulincer, V. Florian, & A. Tolmacz, 1990), the Postpartum Bonding Questionnaire (L.F. Brockington, C. Fraser, & D. Wilson, 2006), the Modified Perinatal Posttraumatic Stress Disorder Questionnaire (J.L. Callahan, S.E. Borja, & M.T. Hynan, 2006), and the Edinburgh Postnatal Depression Scale (J.L. Cox, G. Chapman, D. Murray, & P. Jones, 1996), using an online survey system. As predicted, insecure attachment styles were associated with bonding difficulties wherein anxious/ambivalent attachment was associated with greater infant-focused anxiety, mediated by postpartum depression but not childbirth-related PTSD symptoms. In contrast, greater avoidant attachment style was associated with greater rejection and anger, mediated by childbirth-related posttraumatic stress disorder (PTSD), but not depression symptoms. The current study confirmed the association of different attachment styles with bonding as well as the mediating roles of childbirth-related PTSD and postpartum depression symptoms. Future psychological interventions may utilize such evidence to target interventions for bonding disorders in accordance with individual differences. © 2018 Michigan Association for Infant Mental Health.

  9. In Pursuit of a Participatory Society: The Role of the participatory agent

    NARCIS (Netherlands)

    Pineda Revilla, Beatriz; Valk, van der A.J.J.

    2016-01-01

    In the last decade, Dutch cities have witnessed a rise in the number of citizen-led initiatives-initiatives which have increasingly attracted the interest of science, the public and policy makers. This article focuses on the role of the "participatory agent", a civil servant whose main task is to

  10. Research-Based Design of Pedagogical Agent Roles: A Review, Progress, and Recommendations

    Science.gov (United States)

    Kim, Yanghee; Baylor, Amy L.

    2016-01-01

    In this paper we review the contribution of our original work titled "Simulating Instructional Roles Through Pedagogical Agents" published in the "International Journal of Artificial Intelligence and Education" (Baylor and Kim in "Computers and Human Behavior," 25(2), 450-457, 2005). Our original work operationalized…

  11. Coping behaviour of extension agents in role conflict situations : a case study in Xinji county, China

    NARCIS (Netherlands)

    Huang, R.Q.

    1998-01-01

    This book is about the coping behaviour of extension agents in role conflict situations in a changing environment in China. The study presents the case of cotton production in Xinji county, China.

    Chapter 1 gives background information on Chinese agricultural and rural

  12. Agentive Role of Government in African Education: North Nyanza, 1890-1920

    Science.gov (United States)

    Omwami, Edith Mukudi

    2014-01-01

    This paper examines the agentive role of the colonial administration in accessing formal education for Africans in North Nyanza, Kenya from 1890 to 1920. It demonstrates the complexities of the colonial experience in which the ultimate application of policy and practice was shaped by the overriding principle of protection of the economic and…

  13. Agents of Structural Change : The Role of Firms and Entrepreneurs in Regional Diversification

    NARCIS (Netherlands)

    Neffke, Frank; Hartog, Matté; Boschma, Ron; Henning, Martin

    2018-01-01

    Who introduces structural change in regional economies: Entrepreneurs or existing firms? And do local or nonlocal establishment founders create most novelty in a region? We develop a theoretical framework that focuses on the roles different agents play in regional transformation. We then apply this

  14. The mediating role of parent-child bonding to prevent adolescent alcohol abuse among Asian American families.

    Science.gov (United States)

    Wang, Meme; Kviz, Frederick J; Miller, Arlene M

    2012-10-01

    The purpose of this paper is to describe unique culturally-based factors that may increase the vulnerability of Asian American adolescents to engage in alcohol use and abuse and the role of parent-child bonding as a protective factor. In particular, this paper addresses the interactions among acculturation, alcohol use, and parent-child bonding and the challenges Asian American families face in strengthening parent-child bonds. We begin by examining likely causes for alienation that occur as a result of immigration to the United States. We then present the cultural context of Asian American families that can also serve to create distance between parent and child, including the contrasting cultural orientations of individualism and collectivism, Asian traditional values, differences in Eastern and Western parenting styles, and intergenerational cultural dissonance. Next, we present a review of the research that has examined acculturation as a risk factor for alcohol use and abuse among Asian American adolescents, with special attention to the mediating role of parent-child bonding. Finally, we conclude with recommendations for future research on the risk and protective factors for adolescent substance abuse, as well as other risky health behaviors among the growing population of Asian Americans in the United States.

  15. Acylhydrazone bond dynamic covalent polymer gel monolithic column online coupling to high-performance liquid chromatography for analysis of sulfonamides and fluorescent whitening agents in food.

    Science.gov (United States)

    Zhang, Chengjiang; Luo, Xialin; Wei, Tianfu; Hu, Yufei; Li, Gongke; Zhang, Zhuomin

    2017-10-13

    A new dynamic covalent polymer (DCP) gel was well designed and constructed based on imine chemistry. Polycondensation of 4,4'-biphenyldicarboxaldehyde and 1,3,5-benzenetricarbohydrazide via Schiff-base reaction resulted in an acylhydrazone bond gel (AB-gel) DCP. AB-gel DCP had three-dimensional network of interconnected nanoparticles with hierarchically porous structure. AB-gel DCP was successfully fabricated as a monolithic column by an in-situ chemical bonding method for online enrichment and separation purpose with excellent permeability. AB-gel DCP based monolithic column showed remarkable adsorption affinity towards target analytes including sulfonamides (SAs) and fluorescent whitening agents (FWAs) due to its strong π-π affinity, hydrophobic effect and hydrogen bonding interaction. Then, AB-gel DCP based monolithic column was applied for online separation and analysis of trace SAs and FWAs in food samples coupled with high-performance liquid chromatography (HPLC). Sulfathiazole (ST) and sulfadimidine (SM2) in one positive weever sample were actually found and determined with concentrations of 273.8 and 286.3μg/kg, respectively. 2,5-Bis(5-tert-butyl-2-benzoxazolyl) thiophene (FWA184) was actually quantified in one tea infusion sample with the concentration of 268.5ng/L. The spiked experiments suggested the good recoveries in range of 74.5-110% for SAs in weever and shrimp samples with relative standard deviations (RSDs) less than 9.7% and in range of 74.0-113% for FWAs in milk and tea infusion samples with RSDs less than 9.0%. AB-gel DCP monolithic column was proved to be a promising sample preparation medium for online separation and analysis of trace analytes in food samples with complex matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Effects of at-home and in-office bleaching agents on the shear bond strength of metal, ceramic, and composite brackets to enamel

    Directory of Open Access Journals (Sweden)

    M Rahul

    2017-01-01

    Full Text Available Aims and Objectives: This study aimed to evaluate the effects of at-home and in-office bleaching on the shear bond strength (SBS of metal, ceramic, and composite orthodontic brackets and to compare their SBSs. Subjects and Methods: A total of 96 human lower premolar teeth were used for this study. Six teeth were used for scanning electron microscopic study while the remaining ninety were divided into three equal groups. Each group was further subdivided into three subgroups with ten samples each. Three protocols were used. In the at-home bleaching group (n = 30, opalescence non-PF (potassium nitrate and fluoride bleaching agent (10% carbamide peroxide was applied onto the teeth daily for 14 days and left for 8 h each day. Teeth in the in-office group (n = 30 were treated twice in consecutive days with Opalescence boost PF (40% hydrogen peroxide. After bleaching, the specimens were stored in distilled water for 1 day before bonding. SBS testing was performed on all teeth using Instron universal testing machine. Results: Analysis of variance indicated a significant difference (P < 0.005 among the groups. Maximum SBS was shown by ceramic brackets in control group (Ib and minimum was shown by composite brackets of in-office bleached group (IIIc. Conclusions: The results showed that at-home bleaching did not affect the SBS significantly whereas in-office bleaching reduced SBS of metal, ceramic, and composite brackets significantly. It is preferable to use metal or ceramic brackets than composite brackets for bonding 24 h after bleaching.

  17. The effects of light curing units and environmental temperatures on C 000000000000 000000000000 000000000000 111111111111 000000000000 111111111111 000000000000 000000000000 000000000000 C conversion of commercial and experimental bonding agents.

    Science.gov (United States)

    Jafarzadeh-Kashi, Tahereh Sadat; Erfan, Mohmmad; Kalbasi, Salmeh; Ghadiri, Malihe; Rakhshan, Vahid

    2014-10-01

    Polymerization of bonding agents (BA) is a critical factor in determining the success of bonded restorations. We aimed to assess the effects of two light curing units and two temperatures on the extent of polymerization (EP) of a commercial BA and an experimental BA. Forty BA specimens were randomly divided into 8 subgroups of n = 5 to compare the polymerization of two BAs (experimental/Scotchbond) based on the variables: temperature (23/37 °C) and light-curing unit (quartz-tungsten-halogen/light-emitting diode). The EP (%) was measured using differential scanning calorimetry, and analyzed using the t-test, two- and three-way analyses of variance (ANOVA), and the Bonferroni test (α = 0.05). There were significant differences between the EP results between the two BAs (P = 0.012) and due to the different temperatures (P = 0.001), but not between the different light-curing units (P = 0.548). The interaction between BA and temperature was significant (P units had similar effects on the EP. The EP values were better when curing was performed at human body temperature.

  18. Non-Classical C–H···X Hydrogen Bonding and Its Role in Asymmetric Organocatalysis

    KAUST Repository

    Ajitha, Manjaly John

    2016-08-17

    Non-classical hydrogen bonds (NCHBs) have attracted significant interest in the past decade particularly because of their important role in asymmetric catalytic systems. These weak interactions (< 4 kcal/mol) offer much flexibility in the preorganization of molecular entities required to achieve high enantioselectivity. Herein, we review some recent important organocatalytic asymmetric reactions where a NCHB serves as a critical factor in determining the stereoselectivity.

  19. Halogen Bonding from Dispersion-Corrected Density-Functional Theory: The Role of Delocalization Error.

    Science.gov (United States)

    Otero-de-la-Roza, A; Johnson, Erin R; DiLabio, Gino A

    2014-12-09

    Halogen bonds are formed when a Lewis base interacts with a halogen atom in a different molecule, which acts as an electron acceptor. Due to its charge transfer component, halogen bonding is difficult to model using many common density-functional approximations because they spuriously overstabilize halogen-bonded dimers. It has been suggested that dispersion-corrected density functionals are inadequate to describe halogen bonding. In this work, we show that the exchange-hole dipole moment (XDM) dispersion correction coupled with functionals that minimize delocalization error (for instance, BH&HLYP, but also other half-and-half functionals) accurately model halogen-bonded interactions, with average errors similar to other noncovalent dimers with less charge-transfer effects. The performance of XDM is evaluated for three previously proposed benchmarks (XB18 and XB51 by Kozuch and Martin, and the set proposed by Bauzá et al.) spanning a range of binding energies up to ∼50 kcal/mol. The good performance of BH&HLYP-XDM is comparable to M06-2X, and extends to the "extreme" cases in the Bauzá set. This set contains anionic electron donors where charge transfer occurs even at infinite separation, as well as other charge transfer dimers belonging to the pnictogen and chalcogen bonding classes. We also show that functional delocalization error results in an overly delocalized electron density and exact-exchange hole. We propose intermolecular Bader delocalization indices as an indicator of both the donor-acceptor character of an intermolecular interaction and the delocalization error coming from the underlying functional.

  20. INGENIERÍA DE SOFTWARE ORIENTADA A AGENTES: ROLES Y METODOLOGÍAS

    Directory of Open Access Journals (Sweden)

    Joaquín Pina Amargós

    2006-12-01

    Full Text Available

     

    Hoy los estándares de ingeniería de software, RUP como proceso de desarrollo y UML como lenguaje de modelado, enfrentan retos debido a los paradigmas distribuidos: Servicios Web y agentes. Los agentes, paradigma prometedor para la ingeniería de software, tienen un gran reto, la falta de estándares metodológicos para su desarrollo. En este trabajo se realiza un estudio comparativo de nueve metodologías de agentes, se analizan roles de personas en la ingeniería de software orientada a agentes y se proponen algunos roles no presentes en RUP y recomendaciones para otros sí presentes que parecen necesarios con este nuevo paradigma.

  1. Role of the Disulfide Bond in Prion Protein Amyloid Formation: A Thermodynamic and Kinetic Analysis.

    Science.gov (United States)

    Honda, Ryo

    2018-02-27

    Prion diseases are associated with the structural conversion of prion protein (PrP) to a β-sheet-rich aggregate, PrP Sc . Previous studies have indicated that a reduction of the disulfide bond linking C179 and C214 of PrP yields an amyloidlike β-rich aggregate in vitro. To gain mechanistic insights into the reduction-induced aggregation, here I characterized how disulfide bond reduction modulates the protein folding/misfolding landscape of PrP, by examining 1) the equilibrium stabilities of the native (N) and aggregated states relative to the unfolded (U) state, 2) the transition barrier separating the U and aggregated states, and 3) the final structure of amyloidlike misfolded aggregates. Kinetic and thermodynamic experiments revealed that disulfide bond reduction decreases the equilibrium stabilities of both the N and aggregated states by ∼3 kcal/mol, without changing either the amyloidlike aggregate structure, at least at the secondary structural level, or the transition barrier of aggregation. Therefore, disulfide bond reduction modulates the protein folding/misfolding landscape by entropically stabilizing disordered states, including the U and transition state of aggregation. This also indicates that the equilibrium stability of the N state, but not the transition barrier of aggregation, is the dominant factor determining the reduction-induced aggregation of PrP. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  2. Excited state hydrogen bonding fluorescent probe: Role of structure and environment

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Debarati, E-mail: debaratidey07@gmail.com [Department of Chemistry, Vidyasagar College, 39 Sankar Ghosh Lane, Kolkata 700006 (India); Sarangi, Manas Kumar [Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); Ray, Angana; Bhattacharyya, Dhananjay [Computational Science Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); Maity, Dilip Kumar [Department of Chemistry, University College of Science and Technology, 92 A.P.C. Road, Kolkata 700009 (India)

    2016-05-15

    An environment sensitive fluorescent probe, 11-benzoyl-dibenzo[a,c]phenazine (BDBPZ), has been synthesized and characterized that acts via excited state hydrogen bonding (ESHB). On interaction with hydrogen bond donating solvents the fluorescence intensity of BDBPZ increases abruptly with a concomitant bathochromic shift. The extent of fluorescence increment and the red-shift of λ{sub max} depend on hydrogen bond donating ability of the solvent associated. ESHB restricts the free rotation of the benzoyl group and hence blocks the non-radiative deactivation pathway. BDBPZ forms an exciplex with organic amine in nonpolar medium that readily disappears on increasing the polarity of the solvent. In polar environment the fluorescence of both the free molecule and excited state hydrogen bonded species are quenched on addition of amine unlike its parent dibenzo[a,c]phenazine (DBPZ), that remains very much inaccessible towards the solvent as well as quencher molecules due to its structure. This newly synthesized derivative BDBPZ is much more interactive due to the benzoyl group that is flanked outside the skeletal aromatic rings of DBPZ, which helps to sense the environment properly and thus shows better ESHB capacity than DBPZ.

  3. Direct reciprocity in animals: The roles of bonding and affective processes.

    Science.gov (United States)

    Freidin, Esteban; Carballo, Fabricio; Bentosela, Mariana

    2017-04-01

    The presence of direct reciprocity in animals is a debated topic, because, despite its evolutionary plausibility, it is believed to be uncommon. Some authors claim that stable reciprocal exchanges require sophisticated cognition which has acted as a constraint on its evolution across species. In contrast, a more recent trend of research has focused on the possibility that direct reciprocity occurs within long-term bonds and relies on simple as well as more complex affective mechanisms such as emotional book-keeping, rudimentary and higher forms of empathy, and inequity aversion, among others. First, we present evidence supporting the occurrence of long-term reciprocity in the context of existing bonds in social birds and mammals. Second, we discuss the evidence for affective responses which, modulated by bonding, may underlie altruistic behaviours in different species. We conclude that the mechanisms that may underlie reciprocal exchanges are diverse, and that some act in interaction with bonding processes. From simple associative learning in social contexts, through emotional contagion and behavioural mimicry, to empathy and a sense of fairness, widespread and diverse social affective mechanisms may explain why direct reciprocity may not be a rare phenomenon among social vertebrates. © 2015 International Union of Psychological Science.

  4. Role of disulphide bonds in a thermophilic serine protease aqualysin I from Thermus aquaticus YT-1.

    Science.gov (United States)

    Sakaguchi, Masayoshi; Takezawa, Makoto; Nakazawa, Rie; Nozawa, Kazutaka; Kusakawa, Taro; Nagasawa, Takeshi; Sugahara, Yasusato; Kawakita, Masao

    2008-05-01

    A thermophilic serine protease, Aqualysin I, from Thermus aquaticus YT-1 has two disulphide bonds, which are also found in a psychrophilic serine protease from Vibrio sp. PA-44 and a proteinase K-like enzyme from Serratia sp. at corresponding positions. To understand the significance of these disulphide bonds in aqualysin I, we prepared mutants C99S, C194S and C99S/C194S (WSS), in which Cys69-Cys99, Cys163-Cys194 and both of these disulphide bonds, respectively, were disrupted by replacing Cys residues with Ser residues. All mutants were expressed stably in Escherichia coli. The C99S mutant was 68% as active as the wild-type enzyme at 40 degrees C in terms of k(cat) value, while C194S and WSS were only 6 and 3%, respectively, as active, indicating that disulphide bond Cys163-Cys194 is critically important for maintaining proper catalytic site conformation. Mutants C194S and WSS were less thermostable than wild-type enzyme, with a half-life at 90 degrees C of 10 min as compared to 45 min of the latter and with transition temperatures on differential scanning calorimetry of 86.7 degrees C and 86.9 degrees C, respectively. Mutant C99S was almost as stable as the wild-type aqualysin I. These results indicate that the disulphide bond Cys163-Cys194 is more important for catalytic activity and conformational stability of aqualysin I than Cys67-Cys99.

  5. Photophysics of Curcumin excited state in toluene-polar solvent mixtures: Role of H-bonding properties of the polar solvent

    Energy Technology Data Exchange (ETDEWEB)

    Saini, R.K.; Das, K., E-mail: kaustuv@rrcat.gov.in

    2014-01-15

    Excited state dynamics of Curcumin in binary solvent mixtures of toluene and polar H-bonding solvents were compared by using an instrument endowed with 40 ps time resolution. The solvation time constant of Curcumin increases significantly (and can therefore be measured) in polar solvents which have, either, both H-bond donating and accepting ability, or, only H-bond donating ability. These results suggest that the rate limiting step in the excited state dynamics of the pigment might be the formation and reorganization of the intermolecular H-bonding between the keto group of the pigment and the H-bond donating moieties of the polar solvent. -- Highlights: • Excited state dynamics of Curcumin in a binary solvent mixture of toluene and three polar H-bonding solvents were compared. • The solvation time constant increases significantly with polar solvents having, H-bond donating and accepting, or, H-bond donating ability. • Observed results suggest that H-bonding property of polar solvent plays an important role in the excited state dynamics. • Intermolecular H-bonding between the keto group of the pigment and polar solvent may be the rate limiting step.

  6. Photophysics of Curcumin excited state in toluene-polar solvent mixtures: Role of H-bonding properties of the polar solvent

    International Nuclear Information System (INIS)

    Saini, R.K.; Das, K.

    2014-01-01

    Excited state dynamics of Curcumin in binary solvent mixtures of toluene and polar H-bonding solvents were compared by using an instrument endowed with 40 ps time resolution. The solvation time constant of Curcumin increases significantly (and can therefore be measured) in polar solvents which have, either, both H-bond donating and accepting ability, or, only H-bond donating ability. These results suggest that the rate limiting step in the excited state dynamics of the pigment might be the formation and reorganization of the intermolecular H-bonding between the keto group of the pigment and the H-bond donating moieties of the polar solvent. -- Highlights: • Excited state dynamics of Curcumin in a binary solvent mixture of toluene and three polar H-bonding solvents were compared. • The solvation time constant increases significantly with polar solvents having, H-bond donating and accepting, or, H-bond donating ability. • Observed results suggest that H-bonding property of polar solvent plays an important role in the excited state dynamics. • Intermolecular H-bonding between the keto group of the pigment and polar solvent may be the rate limiting step

  7. Recent perspectives on the role of nutraceuticals as cholesterol-lowering agents.

    Science.gov (United States)

    Ward, Natalie; Sahebkar, Amirhossein; Banach, Maciej; Watts, Gerald

    2017-12-01

    Reduction in circulating cholesterol is an important step in lowering cardiovascular risk. Although statins are the most frequently prescribed cholesterol-lowering medication, there remains a significant portion of patients who require alternative treatment options. Nutraceuticals are increasingly popular as cholesterol-lowering agents. Despite the lack of long-term trials evaluating their use on cardiovascular endpoints and mortality, several studies have demonstrated their potential cholesterol-lowering effects. The purpose of this review is to provide an update on the role of nutraceuticals as cholesterol-lowering agents. The present review will focus on individual nutraceutical compounds, which have shown modest cholesterol-lowering abilities, as well as combination nutraceuticals, which may offer potential additive and/or synergistic effects. Berberine, red yeast rice, and plant sterols have moderate potential as cholesterol-lowering agents. Combination nutraceuticals, including the proprietary formulation, Armolipid Plus, appear to confer additional benefit on plasma lipid profiles, even when taken with statins and other agents. Although robust, long-term clinical trials to examine the effects of nutraceuticals on clinical outcomes are still required, their cholesterol-lowering ability, together with their reported tolerance and safety, offer a pragmatic option for lowering plasma cholesterol levels.

  8. Agentic women and communal leadership: how role prescriptions confer advantage to top women leaders.

    Science.gov (United States)

    Rosette, Ashleigh Shelby; Tost, Leigh Plunkett

    2010-03-01

    The authors contribute to the ongoing debate about the existence of a female leadership advantage by specifying contextual factors that moderate the likelihood of the emergence of such an advantage. The investigation considered whether the perceived role incongruence between the female gender role and the leader role led to a female leader disadvantage (as predicted by role congruity theory) or whether instead a female leader advantage would emerge (as predicted by double standards and stereotype content research). In Study 1, it was only when success was internally attributed that women top leaders were evaluated as more agentic and more communal than men top leaders. Study 2 showed that the favorable ratings were unique to top-level positions and further showed that the effect on agentic traits was mediated by perceptions of double standards, while the effect on communal traits was mediated by expectations of feminized management skills. Finally, Study 2 showed that top women leaders were evaluated most favorably on overall leader effectiveness, and this effect was mediated by both mediators. Our results support the existence of a qualified female leadership advantage. 2010 APA, all rights reserved

  9. The role indigenous bacterial isolates for bioremediation agent in the uranium contaminated aquatic environment

    International Nuclear Information System (INIS)

    Mochd Yazid

    2014-01-01

    A Research on the role of indigenous bacterial isolates for bio-remediation agent of the uranium contaminated in the aquatic environment has been conducted. The objective of the research is to study the role of Pseudomonas sp and Bacillus sp. have been isolated from low level uranium waste for bioremediation agent in their environment, such as the determination of efficiency of the uranium binding compared by the non indigenous bacterial, location of these binding and the influences of added acethyl acid stimulant. The uranium reduction studied was measured by weighting bacterial biomass and uranium concentration was measured by spectrophotometer. The acethyl acid stimulant addition has been done with the variation of concentration and volume. The efficiency of the uranium reduction by indigenous bacterial isolate such as Pseudomonas sp were 84.99 % and Bacillus sp were 52.70 %, so the reduction efficiency by non indigenous bacterial such as Pseudomonas aerogenes were 78.47 % and Bacillus subtilis were 45.22 % for 54 hours incubation time. The result of this research can be concluded that Pseudomonas sp and Bacillus sp. Indigenous bacterial have been isolates from the liquid uranium waste can contributed in bioremediation agent for uranium radionuclide in the environment for 60 ppm concentration with reduction efficiency 52.70 %-84.99 %, that is higher non indigenous bacterial for 54 hours incubation time, the stimulant addition of acethyl acid, the efficiency can be increased up to 99.8 %. (author)

  10. Mechanical properties of hexaferite based magnet composite of SrFe12019 and BaFe12O19 with natural rubber bonding agent

    International Nuclear Information System (INIS)

    Waluyo, T.; Herman, Y.A.; Sudirman; Ridwan

    2000-01-01

    Research on mechanical properties at magnet composite of SrFe 12 0 19 (SrM) and BaFe 12 O 19 (BaM)magnet powder with natural rubber bonding agent have been done. The natural rubber used was rubber made of latex without vulcanization, The SrM powder having average particle size of 1.6 μm and flat shaped. and the BaM powder having particle size of 1.2 μm and nodular shaped. The production of composite carried out in Labo Plastomill at 100 o C and mixer speed of 30 rpm for 7 minutes. The result obtained from Labo Plastomill then made into sheets. Mechanical properties of the composite tested were strain, elongation break and hardness, The results showed that the highest strain of the SrM composite obtained at composition of 70% vol of powder that is 2,22 MPa, and 3,84 MPa for BaM composite at 50% vol. of powder The elongation break of SrM composite decreased by increasing of powder volume fraction, that is 90% at the composition or 70% vol. of powder, and 370% for BaM composite at 50% vol. fraction of powder. The highest hardness for SrM composite obtained at composition of of 70% vol. of powder, that is 95 SHA. and for the BaM composite at 50% vol. of powder. that is 52 SHA

  11. Preparation of Biocomposites using Sawdust and Lignosulfonate with a Culturе Liquid of Levan Producer Azotobacter vinelandii as a Bonding Agent

    Directory of Open Access Journals (Sweden)

    Victor V. Revin

    2016-02-01

    Full Text Available The possibility of preparing molding-bioengineered materials, such as woodchip boards (WCB, from sawdust using technical lignosulfonate (LGS, a wood waste product, and a culture liquid (CL of levan microbial polysaccharide producer by Azotobacter vinelandii D-08 is explored in this article. The parameters of the derived materials are comparable to those of traditional materials made from toxic phenol-formaldehyde resins. The various physical and mechanical characteristics of the materials depend on the quantity of the bonding agent used for the preparation. Adding a culture liquid increases the humidity resistance of the molding materials. Using electron microscopy and X-ray micro-tomography, it is clear that the structure of woodchip boards become more homogeneous without microcracks with the addition of CL. The strength of the best samples prepared was approximately 24 to 29 MPa with a density of 1170 to 1255 kg/m3 and a swell on wetting of 6.7%. During hot pressing, noticeable changes were observed by Fourier transform infrared spectroscopy (FTIR at frequencies typical of LGS sulfonic-acid groups, levan fructose fragments, and skeletal vibrations of a syringal/guaiacyl core in lignin and of C-H groups of hemicelluloses. This indicates the involvement of these functional groups in the process of binding wood particles with hot pressing.

  12. Possible role of common spices as a preventive and therapeutic agent for Alzheimer′s disease

    Directory of Open Access Journals (Sweden)

    Omid Mirmosayyeb

    2017-01-01

    Full Text Available For centuries, spices have been consumed as food additives or medicinal agents. However, there is increasing evidence indicating the plant-based foods in regular diet may lower the risk of neurodegenerative diseases including Alzheimer disease. Spices, as one of the most commonly used plant-based food additives may provide more than just flavors, but as agents that may prevent or even halt neurodegenerative processes associated with aging. In this article, we review the role and application of five commonly used dietary spices including saffron turmeric, pepper family, zingiber, and cinnamon. Besides suppressing inflammatory pathways, these spices may act as antioxidant and inhibit acetyl cholinesterase and amyloid β aggregation. We summarized how spice-derived nutraceuticals mediate such different effects and what their molecular targets might be. Finally, some directions for future research are briefly discussed.

  13. THE ROLE OF INTERNATIONAL INNOVATION CLUSTERS ON INCREASING ECONOMIC AGENTS SUSTAINABILITY

    Directory of Open Access Journals (Sweden)

    M. Ustymenko

    2014-09-01

    Full Text Available The influence of enterprises integration into international innovation clusters on the increasing of enterprises, countries and regions economic sustainability under the global instability are explored. Potential sources of instability and threats of the integration into international cluster structures are defined. Author outlines the main benefits of international innovation cluster for enhancement of economic agents sustainability, such as: possibility for joint exploitation of market opportunities and efforts consolidation for overcoming market threats, cluster self-sufficiency, effective cluster internal reorganization and adaptation in response to external changes. Three clusters (engineering for agriculture production cluster (Hersonska oblast and German enterprises, IT cluster (Lvivska oblast and Poland enterprises, cluster for R&D commercialization (Slobodzanschina euroregion are examined to uncover the role of international innovation cluster formation on enhancement of economic agents' economic sustainability.

  14. The roles of the various plasma agents in the inactivation of bacteria

    International Nuclear Information System (INIS)

    Lu Xinpei; Xiong Qing; Tang Zhiyuan; Xiong Zhilan; Hu Jing; Jiang Zhonghe; Pan Yuan; Ye Tao; Cao Yingguang; Sun Ziyong

    2008-01-01

    The roles of various plasma agents in the inactivation of bacteria have recently been investigated. However, up to now, the effect of the charged particles on the inactivation of bacteria is not well understood. In this paper, an atmospheric pressure plasma jet device, which generates a cold plasma plume carrying a peak current of 300 mA, is used to investigate the role of the charged particles in the inactivation process. It is found that the charged particles play a minor role in the inactivation process when He/N 2 (3%) is used as working gas. On the other hand, when He/O 2 (3%) is used, the charged particles are expected to play an important role in the inactivation of bacteria. Further analysis shows that the negative ions O 2 - might be the charged particles that are playing the role. Besides, it is found that the active species, including O, O 3 , and metastable state O 2 *, can play a crucial role in the inactivation of the bacteria. However, the excited He*, N 2 C 3 Π u , and N 2 + B 2 Σ u + have no significant direct effect on the inactivation of bacteria. It is also concluded that heat and UV play no or minor role in the inactivation process

  15. Dynamic Correlations of Sovereign Bond Yield Spreads in the Euro zone and the Role of Credit Rating Agencies' Downgrades

    OpenAIRE

    Antonakakis, Nikolaos

    2012-01-01

    The European debt crisis that followed the global financial crisis, erupting first with Greece, then Ireland, Portugal, Italy and Spain, has threatened the very existence of the Euro zone. In this paper we examine the evolution of dynamic co-movements of sovereign bond yield spreads (BYS) in the Euro zone and the role of credit rating agency downgrades on those co-movements. Estimation results from a multivariate DCC-GARCH model on daily BYS data for nine Euro zone countries over the period 2...

  16. Role of Austenite in Brittle Fracture of Bond Region of Super Duplex Stainless Steel

    Science.gov (United States)

    Kitagawa, Yoshihiko; Ikeuchi, Kenji; Kuroda, Toshio

    Weld simulation of heat-affected zone (HAZ) was performed to investigate the mechanism by which austenite affects the toughness of super duplex stainless steel. Thermal cycles of various peak temperatures in the range from 1373 K to 1673 K corresponding to the HAZ were applied to SAF2507 super duplex stainless steel specimens. Charpy impact test was carried out using the specimens after the weld simulation, and the fracture surfaces were observed by SEM using three-dimensionally reconstruction technique. Austenite content decreased with increasing the peak temperature when the peak temperature exceeded 1473 K and the impact value decreased with increasing the peak temperature and decreasing the austenite content. The thermal cycle of the peak temperature of 1673 K corresponding to weld bond region caused decreasing of austenite content which was 22% lower than that of the base metal. The ductile-brittle transition temperature was measured. As a result the temperature increased rapidly in the weld bond region, the peak temperature of which exceeded 1623 K by the grain growth of ferrite matrix occurring subsequently to the completely dissolution of austenite. The morphology of the fracture surfaces after impact testing at 77 K showed cleavage fracture of ferrite. The {100} orientations of cleavage fracture facets were measured using three-dimensional images of the fracture surfaces and the results were visualized as the orientation color maps. The results showed that there were cleavage fractures consisting of a few facets parallel to each other. It was considered that a few facets existed in one ferrite grain. It was concluded that Widmanstätten austenite divided the large fracture into smaller cleavage facets in a ferrite grain and then suppressed the degradation of bond toughness of duplex stainless steel.

  17. The Dominant Role of Chalcogen Bonding in the Crystal Packing of 2D/3D Aromatics

    Czech Academy of Sciences Publication Activity Database

    Fanfrlík, Jindřich; Přáda, A.; Padělková, Z.; Pecina, Adam; Macháček, Jan; Lepšík, Martin; Holub, Josef; Růžička, A.; Hnyk, Drahomír; Hobza, Pavel

    2014-01-01

    Roč. 53, č. 38 (2014), s. 10139-10142 ISSN 1433-7851 R&D Projects: GA ČR GBP208/12/G016; GA ČR GAP208/10/2269 Grant - others:GA MŠk(CZ) ED2.1.00/03.0058; GA MŠk(CZ) ED1.1.00/02.0070; GA MŠk(CZ) LM2011033 Program:ED; ED Institutional support: RVO:61388963 ; RVO:61388980 Keywords : boranes * chalcogen bonds * crystal structures * sulfur * X-ray diffraction Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 11.261, year: 2014

  18. The Effect Of Gamma Radiation On The Shear Bond Strength And Micro-Hardness Of Zirconia Ceramic Using Three Types Of Luting Agents

    International Nuclear Information System (INIS)

    Abd El Rahman, R.H.M.

    2012-01-01

    . Therefore, GICs are important restorative materials for these patients. Resin cements are widely used as luting materials used for cementation of restoration to tooth structure as they provide superior retention and improve resistance to fracture. There are several factors that influence the retention strength in cement retained restorations including the properties of luting agent, surface area of crown, surface roughness, height of abutment, cementation technique, variation in cement viscosity and convergence. The ability of resin cement to bond to restorative material is critical for maximal crown retention.

  19. The role of family planning communications--an agent of reinforcement or change.

    Science.gov (United States)

    Chen, E C

    1981-12-01

    Results are presented of a multiple classification analysis of responses to a 1972 KAP survey in Taiwan of 2013 married women aged 18-34 designed to determine whether family planning communication is primarily a reinforcement agent or a change agent. 2 types of independent variables, social demographic variables including age, number of children, residence, education, employment status, and duration of marriage; and social climate variables including ever receiving family planning information from mass media and ever discussing family planning with others, were used. KAP levels, the dependent variables, were measured by 2 variables each: awareness of effective methods and awareness of government supply of contraceptives for knowledge, wish for additional children and approve of 2-child family for attitude, and never use contraception and neither want children nor use contraception for practice. Social demographic and attitudinal variables were found to be the critical ones, while social climate and knowledge variables had only negligible effects on various stages of family planning adoption, indicating that family planning communications functioned primarily as a reinforcement agent. The effects of social demographic variables were prominent in all stages of contraceptive adoption. Examination of effects of individual variables on various stages of family planning adoption still supported the argument that family planning communications played a reinforcement role. Family planning communications functioned well in diffusing family planning knowledge and accessibility, but social demographic variables and desire for additional children were the most decisive influences on use of contraception.

  20. Agentic and communal narcissism and satisfaction with life: The mediating role of psychological entitlement and self-esteem.

    Science.gov (United States)

    Żemojtel-Piotrowska, Magdalena A; Piotrowski, Jarosław P; Maltby, John

    2017-10-01

    This study examined the mediational role of self-esteem (as an enhancement) and psychological entitlement (as a cost) in the relationship between an agentic-communal model of grandiose narcissism and satisfaction with life. Two hundred and forty-eight university undergraduate students completed measures of agentic and communal narcissism, self-esteem, psychological entitlement and satisfaction with life. The findings suggest that there is support for the usefulness of the agentic-communal model of narcissism, and, consistent with predictions in the wider literature, self-esteem and psychological entitlement mediated the relationship between agentic-communal narcissism and life satisfaction. © 2015 International Union of Psychological Science.

  1. The role of monoamines in the actions of established and "novel" antidepressant agents: a critical review.

    Science.gov (United States)

    Millan, Mark J

    2004-10-01

    Monoaminergic pathways are highly responsive to aversive stimuli and play a crucial role in the control of affect, cognition, endocrine secretion, chronobiotic rhythms, appetite, and motor function, all of which are profoundly disrupted in depressive states. Accordingly, a perturbation of monoaminergic transmission is implicated in the aetiology of depressive disorders, and all clinically available antidepressants increase corticolimbic availability of monoamines. However, their limited efficacy, delayed onset of action, and undesirable side effects underlie ongoing efforts to identify improved therapeutic agents. Sequencing the human genome has raised the hope not only of better symptomatic control of depression, but even of the prevention or cure of depressive states. In the pursuit of these goals, there is currently a tendency to focus on selective ligands of "novel" nonmonoaminergic targets. However, certain classes of novel agent (such as neurokinin(1) receptor antagonists) indirectly modulate the activity of monoaminergic networks. Others may act "downstream" of them, converging onto common cellular substrates controlling gene expression, synaptic plasticity, and neurogenesis. Further, by analogy to the broad-based actions of currently employed drugs, multitarget agents may be better adapted than selective agents to the management of depression-a complex disorder with hereditary, developmental, and environmental origins. It is, thus, important to continue the creative exploration of clinically validated and innovative monoaminergic strategies within a multitarget framework. In this light, drugs combining monoaminergic and nonmonoaminergic mechanisms of action may be of particular interest. The present article provides a critical overview of monoaminergic strategies for the treatment of depressive states, both established and under development, and discusses interactions of novel "nonmonoaminergic" antidepressants with monoaminergic mechanisms.

  2. Berberine as a promising safe anti-cancer agent - is there a role for mitochondria?

    Science.gov (United States)

    Diogo, Catia V; Machado, Nuno G; Barbosa, Inês A; Serafim, Teresa L; Burgeiro, Ana; Oliveira, Paulo J

    2011-06-01

    Metabolic regulation is largely dependent on mitochondria, which play an important role in energy homeostasis. Imbalance between energy intake and expenditure leads to mitochondrial dysfunction, characterized by a reduced ratio of energy production (ATP production) to respiration. Due to the role of mitochondrial factors/events in several apoptotic pathways, the possibility of targeting that organelle in the tumor cell, leading to its elimination is very attractive, although the safety issue is problematic. Berberine, a benzyl-tetra isoquinoline alkaloid extracted from plants of the Berberidaceae family, has been extensively used for many centuries, especially in the traditional Chinese and Native American medicine. Several evidences suggest that berberine possesses several therapeutic uses, including anti-tumoral activity. The present review supplies evidence that berberine is a safe anti-cancer agent, exerting several effects on mitochondria, including inhibition of mitochondrial Complex I and interaction with the adenine nucleotide translocator which can explain several of the described effects on tumor cells.

  3. The role of hydrogen bonding on kinetics of rearrangement of heterocyclic aldoximes in perchloric acide

    International Nuclear Information System (INIS)

    Azzouz, A.S.; Abdullah, K.A.; Al-Niemi, I.

    1995-01-01

    Four paris of syn and anti aromatic heterocyclic aldoximes as 2-thiophenealdoxime, 2- furfuraladoxime, 2-pyridinealdoxime and 2-pyrrolealdoxime are prepared. The strcutures of these geometrical isomers are confirmed by the meaasurements of their U.V. I, R and melting points. Experiments show the existence of these aldoximers in an intramolecular hy-drogen bonding with variable strength depending on the hetero ztoms in the aldoximes. The first order rate constants of the rearrangement of syn aldoximes follow the order of hetero S>O>N, while the anti aldoximes show irregular order, Factors governing the aniti constants of the rearrangement of syn and anti aldoximes are analysed. Activation parameters are estimated and discussed on the basis of isokinetic relation-ship. The differences in physical and spectroscpic behavior of aldoximes lead to an important suggestion regarding the configuration of oxime. (author). 27 refs., 2 figs., 2 tabs

  4. Sulfur dioxide induced aggregation of wine thaumatin-like proteins: Role of disulfide bonds.

    Science.gov (United States)

    Chagas, Ricardo; Laia, César A T; Ferreira, Ricardo B; Ferreira, Luísa M

    2018-09-01

    Aggregation of heat unstable wine proteins is responsible for the economically and technologically detrimental problem called wine protein haze. This is caused by the aggregation of thermally unfolded proteins that can precipitate in bottled wine. To study the influence of SO 2 in this phenomenon, wine proteins were isolated and thaumatins were identified has the most prone to aggregate in the presence of this compound. Isolated wine thaumatins aggregation was followed by dynamic light scattering (DLS), circular dichroism (CD), fluorescence spectroscopy and size exclusion chromatography (SEC). Our experimental results demonstrate that protein thermal unfolding after exposure of the protein to 70 °C does not present differences whether SO 2 is present or not. Conversely, when the protein solution is cooled to 15 °C (after heat stress) significant analytical changes can be observed between samples with and without SO 2 . A remarkable change of circular dichroism spectra in the region 220-230 nm is observed (which can be related to S-S torsion angles), as well as an increase in tryptophan fluorescence intensity (absence of fluorescence quenching by S-S bonds). Formation of covalently-linked dimeric and tetrameric protein species were also detected by SEC. The ability to dissolve the aggregates with 8 M urea seems to indicate that hydrophobic interactions are prevalent in the formed aggregates. Also, the reduction of these aggregates with tris (2-carboxyethyl) phosphine (TCEP) to only monomeric species reveals the presence of intermolecular S-S bonds. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Roles for Agent Assistants in Field Science: Understanding Personal Projects and Collaboration

    Science.gov (United States)

    Clancey, William J.

    2003-01-01

    A human-centered approach to computer systems design involves reframing analysis in terms of the people interacting with each other. The primary concern is not how people can interact with computers, but how shall we design work systems (facilities, tools, roles, and procedures) to help people pursue their personal projects, as they work independently and collaboratively? Two case studies provide empirical requirements. First, an analysis of astronaut interactions with CapCom on Earth during one traverse of Apollo 17 shows what kind of information was conveyed and what might be automated today. A variety of agent and robotic technologies are proposed that deal with recurrent problems in communication and coordination during the analyzed traverse. Second, an analysis of biologists and a geologist working at Haughton Crater in the High Canadian Arctic reveals how work interactions between people involve independent personal projects, sensitively coordinated for mutual benefit. In both cases, an agent or robotic system's role would be to assist people, rather than collaborating, because today's computer systems lack the identity and purpose that consciousness provides.

  6. Role of bonding mechanisms during transfer hydrogenation reaction on heterogeneous catalysts of platinum nanoparticles supported on zinc oxide nanorods

    Science.gov (United States)

    Al-Alawi, Reem A.; Laxman, Karthik; Dastgir, Sarim; Dutta, Joydeep

    2016-07-01

    For supported heterogeneous catalysis, the interface between a metal nanoparticle and the support plays an important role. In this work the dependency of the catalytic efficiency on the bonding chemistry of platinum nanoparticles supported on zinc oxide (ZnO) nanorods is studied. Platinum nanoparticles were deposited on ZnO nanorods (ZnO NR) using thermal and photochemical processes and the effects on the size, distribution, density and chemical state of the metal nanoparticles upon the catalytic activities are presented. The obtained results indicate that the bonding at Pt-ZnO interface depends on the deposition scheme which can be utilized to modulate the surface chemistry and thus the activity of the supported catalysts. Additionally, uniform distribution of metal on the catalyst support was observed to be more important than the loading density. It is also found that oxidized platinum Pt(IV) (platinum hydroxide) provided a more suitable surface for enhancing the transfer hydrogenation reaction of cyclohexanone with isopropanol compared to zero valent platinum. Photochemically synthesized ZnO supported nanocatalysts were efficient and potentially viable for upscaling to industrial applications.

  7. Role of infectious agents in the carcinogenesis of brain and head and neck cancers

    Directory of Open Access Journals (Sweden)

    Alibek Kenneth

    2013-02-01

    Full Text Available Abstract This review concentrates on tumours that are anatomically localised in head and neck regions. Brain cancers and head and neck cancers together account for more than 873,000 cases annually worldwide, with an increasing incidence each year. With poor survival rates at late stages, brain and head and neck cancers represent serious conditions. Carcinogenesis is a multi-step process and the role of infectious agents in this progression has not been fully identified. A major problem with such research is that the role of many infectious agents may be underestimated due to the lack of or inconsistency in experimental data obtained globally. In the case of brain cancer, no infection has been accepted as directly oncogenic, although a number of viruses and parasites are associated with the malignancy. Our analysis of the literature showed the presence of human cytomegalovirus (HCMV in distinct types of brain tumour, namely glioblastoma multiforme (GBM and medulloblastoma. In particular, there are reports of viral protein in up to 100% of GBM specimens. Several epidemiological studies reported associations of brain cancer and toxoplasmosis seropositivity. In head and neck cancers, there is a distinct correlation between Epstein-Barr virus (EBV and nasopharyngeal carcinoma (NPC. Considering that almost every undifferentiated NPC is EBV-positive, virus titer levels can be measured to screen high-risk populations. In addition there is an apparent association between human papilloma virus (HPV and head and neck squamous cell carcinoma (HNSCC; specifically, 26% of HNSCCs are positive for HPV. HPV type 16 was the most common type detected in HNSCCs (90% and its dominance is even greater than that reported in cervical carcinoma. Although there are many studies showing an association of infectious agents with cancer, with various levels of involvement and either a direct or indirect causative effect, there is a scarcity of articles covering the role of

  8. The Specific Role of Childhood Abuse, Parental Bonding, and Family Functioning in Female Adolescents With Borderline Personality Disorder.

    Science.gov (United States)

    Infurna, Maria Rita; Brunner, Romuald; Holz, Birger; Parzer, Peter; Giannone, Francesca; Reichl, Corinna; Fischer, Gloria; Resch, Franz; Kaess, Michael

    2016-04-01

    This study examined a broad variety of adverse childhood experiences in a consecutive sample of female adolescent inpatients with borderline personality disorder (BPD; n = 44) compared with a clinical control (CC; n = 47) group with mixed psychiatric diagnoses. BPD was diagnosed using a structured clinical interview; different dimensions of childhood adversity were assessed using the Childhood Experiences of Care and Abuse Questionnaire, the Parental Bonding Instrument, and the Family Assessment Device. A history of childhood adversity was significantly more common in patients with BPD than in the CC group. Using a multivariate model, sexual abuse (OR = 13.8), general family functioning (OR = 8.9), and low maternal care (OR = 7.6) were specific and independent predictors of adolescent BPD. The results increase our knowledge of the specific role of different dimensions of childhood adversity in adolescent BPD. They have important implications for prevention and early intervention as they highlight the need for specific strategies for involving the family.

  9. Role of carbene complexes in initiation and chain propagation in double bond redistribution reactions

    International Nuclear Information System (INIS)

    Dolgoplosk, K.L.; Makovetskij, E.I.; Tinyakova, E.I.; Golenko, T.G.; Oreshkin, I.A.

    1976-01-01

    A study has been made of the role of carbene complexes of tungsten in initiation and propagation of the ring-opening polymerization of cycloolefins. Data are given on polymerization of cyclopentene and cycloocterdiene-1,5 in the presence of the system tungsten chloride-diazo-compound (DAC)

  10. Cobalt bis(dicarbollide) ions with covalently bonded CMPO groups as selective extraction agents for lanthanide and actinide cations from highly acidic nuclear waste solutions

    International Nuclear Information System (INIS)

    Gruner, B.; Plesek, J.; Baca, J.; Cisarova, I.; Dozol, J.F.; Rouquette, H.; Vinas, C.; Selucky, P.; Rais, J.

    2002-01-01

    A new series of boron substituted cobalt bis(dicarbollide)(1-) ion (1) derivatives of the general formula [(8-CMPO-(CH 2 -CH 2 O) 2 -1,2-C 2 B 9 H 10 )(1',2'-C 2 B 9 H 11 )-3,3'-Co] - (CMPO = Ph 2 P(O)-CH 2 C(O)NR, R = C 4 H 9 (3b), -C 12 H 25 (4b), -CH 2 -C 6 H 5 (5b)) was prepared by ring cleavage of the 8-dioxane-cobalt bis(dicarbollide) (2) bi-polar compound by the respective primary amines and by subsequent reaction of the resulting amino derivatives (3a-5a) with the nitrophenyl ester of diphenyl-phosphoryl-acetic acid. The compounds were synthesized with the aim to develop a new class of more efficient extraction agents for liquid/liquid extraction of polyvalent cations, i.e. lanthanides and actinides, from high-level activity nuclear waste. All compounds were characterized by a combination of 11 B NMR, 1 H high field NMR, Mass Spectrometry with Electro-spray and MALDI TOF ionisation, HPLC and other techniques. The molecular structure of the supramolecular Ln 3+ complex of the anion 5b was determined by single crystal X-ray diffraction analysis. Crystallographic results proved that the Ln(m) atom is bonded to three functionalized cobalt bis(dicarbollide) anions in a charge compensated complex. The cation is tightly coordinated by six oxygen atoms of the CMPO terminal groups (two of each ligand) and by three water molecules completing the metal coordination number to 9. Atoms occupying the primary coordination sphere form a tri-capped trigonal prismatic arrangement. Very high liquid-liquid extraction efficiency of all anionic species was observed. Moreover, less polar toluene can be applied as an auxiliary solvent replacing the less environmentally friendly nitro- and chlorinated solvents used in the current dicarbollide liquid-liquid extraction process. The extraction coefficients are sufficiently high for possible technological applications. (authors)

  11. Effect of X-ray contrast agents on hemostasis and its role in the genesis of adverse reactions

    International Nuclear Information System (INIS)

    Sviridov, N.K.; Napolov, Yu.K.

    2001-01-01

    Based on available data, the effect of X-ray contrast agents (XCA) on homeostasis and its role in side reactions genesis are discussed. It is shown that the contrast agent type used can essentially affect the thrombocytes. Nonionic XCA are able to increase the thrombocytes degranulation in case of coronarography and percutaneous transluminal coronary angioplastics with release of procoagulants in vessel gap. This effect can to lead to acute thromboses and be the start of restenosis [ru

  12. The role of the epoxy resin: Curing agent ratio in composite interfacial strength by single fibre microbond test

    DEFF Research Database (Denmark)

    Minty, Ross; Thomason, James L.; Petersen, Helga Nørgaard

    2015-01-01

    This paper focuses on an investigation into the role of the epoxy resin: curing agent ratio in composite interfacial shear strength of glass fibre composites. The procedure involved changing the percentage of curing agent (Triethylenetetramine [TETA]) used in the mixture with several different...... percentages used, ranging from 4% up to 30%, including the stoichiometric ratio. It was found by using the microbond test, that there may exist a relationship between the epoxy resin to curing agent ratio and the level of adhesion between the reinforcing fibre and the polymer matrix of the composite....

  13. Repair Bond Strength of Aged Resin Composite after Different Surface and Bonding Treatments

    Directory of Open Access Journals (Sweden)

    Michael Wendler

    2016-07-01

    Full Text Available The aim of this study was to compare the effect of different mechanical surface treatments and chemical bonding protocols on the tensile bond strength (TBS of aged composite. Bar specimens were produced using a nanohybrid resin composite and aged in distilled water for 30 days. Different surface treatments (diamond bur, phosphoric acid, silane, and sandblasting with Al2O3 or CoJet Sand, as well as bonding protocols (Primer/Adhesive were used prior to application of the repair composite. TBS of the specimens was measured and the results were analyzed using analysis of variance (ANOVA and the Student–Newman–Keuls test (α = 0.05. Mechanically treated surfaces were characterized under SEM and by profilometry. The effect of water aging on the degree of conversion was measured by means of FTIR-ATR spectroscopy. An important increase in the degree of conversion was observed after aging. No significant differences in TBS were observed among the mechanical surface treatments, despite variations in surface roughness profiles. Phosphoric acid etching significantly improved repair bond strength values. The cohesive TBS of the material was only reached using resin bonding agents. Application of an intermediate bonding system plays a key role in achieving reliable repair bond strengths, whereas the kind of mechanical surface treatment appears to play a secondary role.

  14. Involving immigrant religious organizations in HIV/AIDS prevention: The role of bonding and bridging social capital.

    Science.gov (United States)

    Leung, ManChui R; Chin, John J; Petrescu-Prahova, Miruna

    2016-08-01

    Immigrant religious organizations in the United States are uniquely positioned to address critical issues beyond religion because of their moral, social and cultural prominence in community life. Increasingly, religious organizations have taken on a leadership role around health issues such as decreasing HIV/AIDS stigma and misinformation. However, there are barriers for some religious leaders and organizations in adopting new health programs, especially if the issue is seen as controversial. Our study examines how social network structures among religious members influence organizational acceptance of new information or controversial ideas, like HIV/AIDS. Using social network analysis methods on data from 2841 contacts in 20 immigrant Chinese Buddhist temples and Christian churches in New York City, we tested whether an immigrant religious organization's likelihood of being involved in HIV/AIDS activities was associated with the presence of bonding or bridging social capital. These two forms of social capital have been found to mediate the levels of exposure and openness to new ideas. We found HIV/AIDS-involved religious organizations were more likely to have lower levels of bonding social capital as indicated by members having fewer ties and fewer demographic attributes in common. We also found HIV/AIDS-involved religious organizations were more likely to have higher levels of bridging social capital as indicated by members having significantly more ties to people outside of their organization. Our study highlights the importance of looking beyond religion type and leadership attributes to social network structures among members in order to better explain organization-level receptiveness to HIV/AIDS involvement. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Influência da adição de carga inorgânica aos sistemas adesivos na resistência adesiva à dentina = Influence of filler addition to bonding agents on dentin bond strength

    Directory of Open Access Journals (Sweden)

    Cesar, Patricia Desiderio

    2005-01-01

    Full Text Available O objetivo desse estudo foi avaliar o papel da presença ou não de partículas de carga nos sistemas adesivos sobre a resistência adesiva à dentina. Foram utilizados 70 dentes bovinos, divididos em 7 grupos, que foram embutidos em resina acrílica e desgastados até a exposição de uma área plana de dentina. Todos os espécimes receberam o condicionamento ácido e aplicação dos sistemas adesivos, contendo ou não as partículas de carga, de acordo com as instruções do fabricante: Prime & Bond 2. 1 (sem carga – SC, Prime & Bond NT (com carga – CC, Prime & Bond 2. 1 + 10% de SiO² (CC, One Step (SC, One Step Plus (CC, Sigle Bond (SC e Single Bond +10% de SiO² (CC. Cilindros de resina composta TPH Spectrum foram realizados sobre a área de adesão. Os espécimes foram armazenados por 24 a 37C°, e então submetidos ao teste de cisalhamento. Os dados obtidos foram submetidos à análise estatística, empregando- se o teste de análise de variância paramétrica, seguida pelo teste de Tukey a um nível de significância de 5%. Concluiu-se que, para todos os sistemas adesivos testados, a adição de partículas de carga não resultou em diferenças significativas na força de adesão. Porém, entre as marcas comerciais, observamos diferenças significativas, o que demonstra a influência dos demais componentes na eficiência adesiva

  16. Investigating the role of water in the Diffusion of Cholera using Agent-Based simulation

    Science.gov (United States)

    Augustijn, Ellen-Wien; Doldersum, Tom; Augustijn, Denie

    2014-05-01

    Traditionally, cholera was considered to be a waterborne disease. Currently we know that many other factors can contribute to the spread of this disease including human mobility and human behavior. However, the hydrological component in cholera diffusion is significant. The interplay between cholera and water includes bacteria (V. cholera) that survive in the aquatic environment, the possibility that run-off water from dumpsites carries the bacteria to surface water (rivers and lakes), and when the bacteria reach streams they can be carried downstream to infect new locations. Modelling is a very important tool to build theory on the interplay between different types of transmission mechanisms that together are responsible for the spread of Cholera. Agent-based simulation models are very suitable to incorporate behavior at individual level and to reproduce emergence. However, it is more difficult to incorporate the hydrological components in this type of model. In this research we present the hydrological component of an Agent-Based Cholera model developed to study a Cholera epidemic in Kumasi (Ghana) in 2005. The model was calibrated on the relative contribution of each community to the distributed pattern of cholera rather than the absolute number of incidences. Analysis of the results shows that water plays an important role in the diffusion of cholera: 75% of the cholera cases were infected via river water that was contaminated by runoff from the dumpsites. To initiate infections upstream, the probability of environment-to-human transmission seemed to be overestimated compared to what may be expected from literature. Scenario analyses show that there is a strong relation between the epidemic curve and the rainfall. Removing dumpsites that are situated close to the river resulted in a strong decrease in the number of cholera cases. Results are sensitive to the scheduling of the daily activities and the survival time of the cholera bacteria.

  17. Trichoderma ROLE IN AGROFORESTRY-CACAOTAL SYSTEMS AS AN ANTAGONAL AGENT

    Directory of Open Access Journals (Sweden)

    Úrsula del Carmen López-Ferrer

    2017-05-01

    Full Text Available Agricultural and cocoa agroforestry systems are important for food production and biodiversity conservation. Among this diversity there is a group of fungi of the genus Trichoderma that present antagonistic effects against phytopathogens and this action can be used as a form of biological control of plant pathogens. In the agroforestry-cacao system the diseases with the highest frequency and with the greatest impact on cocoa production (Theobroma cacao are black rot (Phytophthora spp., Broom broom (Moniliophthora perniciosa and moniliasis (Moniliophthora roreri. The objective of this work was to perform an analysis of the main theoretical and practical aspects about the genus Trichoderma and its role in agriculture as an antagonistic agent. One of the microscopic features in the delimitation of the genus, especially by the presence of structures called phalid. The antagonistic mechanisms used by Trichoderma spp. Are described as competition, antibiosis and mycoparasitism. Mycoparasitism is having a relevance on the implications of extracellular enzymes such as chitinases, cellulases, β-1-3-glucanases and proteases that lyse or digest the walls of fungi, Moniliophthora roreri disease. This fungus can inhibit the growth of other fungi and bacteria by producing several volatile and non-volatile secondary metabolites. On the other hand, it participates in the production of regulators of growth and stimulation of the division, differentiation and cellular growth in the plant by the elicitor agent. Trichoderma species that are commercialized for biological control, growth promoter and biofertilizer are T. viride, T. polysporum and T. harzianum. The T. virens and T. harzianum species are most used for the antagonistic control of M. roreri, Phytophthora spp., and M. perniciosa in agroforestry-cacao systems (Theobroma cacao L. with optimal results to the inhibitory effect for these diseases.

  18. Immigrant self-employment : testing hypotheses about the role of origin- and host country human capital and bonding and bridging social capital

    NARCIS (Netherlands)

    Kanas, A.M.; Tubergen, F.A. van; Lippe, T. van der

    2009-01-01

    Using large-scale data on immigrants in the Netherlands, the authors tested competing arguments about the role of origin- and host-country human capital and bonding and bridging social capital in immigrants’ self-employment. When taking job-skill level into account, immigrants with a higher level of

  19. In vitro efficiency and mechanistic role of indocyanine green as photodynamic therapy agent for human melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Mamoon, A.M.; Miller, L.; Gamal-Eldeen, A. M.; Ruppel, M. E.; Smith, R. J.; Tsang, T.; Miller, L. M.

    2009-05-02

    Photodynamic therapy (PDT) is a promising treatment for superficial cancer. However, poor therapeutic results have been reported for melanoma, due to the high melanin content. Indocyanine green (ICG) has near infrared absorption (700-800 nm) and melanins do not absorb strongly in this area. This study explores the efficiency of ICG as a PDT agent for human melanoma, and its mechanistic role in the cell death pathway. Human skin melanoma cells (Sk-Mel-28) were incubated with ICG and exposed to a low power Ti:Sapphire laser. Synchrotron-assisted Fourier transform infrared microspectroscopy and hierarchical cluster analysis were used to assess the cell damage and changes in lipid, protein, and nucleic acids. The cell death pathway was determined by analysis of cell viability and apoptosis and necrosis markers. In the cell death pathway, {sup 1}O{sub 2} generation evoked rapid multiple consequences that trigger apoptosis after laser exposure for only 15min including the release of cytochrome c, the activation of total caspases, caspase-3, and caspase-9, the inhibition of NF-{Kappa}B P65, and the enhancement of DNA fragmentation, and histone acetylation. ICG/PDT can efficiently and rapidly induce apoptosis in human melanoma cells and it can be considered as a new therapeutic approach for topical treatment of melanoma.

  20. A Novel Role of Serotonin Receptor 2B Agonist as an Anti-Melanogenesis Agent

    Directory of Open Access Journals (Sweden)

    Eun Ju Oh

    2016-04-01

    Full Text Available BW723C86, a serotonin receptor 2B agonist, has been investigated as a potential therapeutic for various conditions such as anxiety, hyperphagia and hypertension. However, the functional role of BW723C86 against melanogenesis remains unclear. In this study, we investigate the effect of serotonin receptor 2B (5-HTR2B agonist on melanogenesis and elucidate the mechanism involved. BW723C86 reduced melanin synthesis and intracellular tyrosinase activity in melan-A cells and normal human melanocytes. The expression of melanogenesis-related proteins (tyrosinase, TRP-1 and TRP-2 and microphthalmia-associated transcription factor (MITF in melan-A cells decreased after BW723C86 treatment. The promoter activity of MITF was also reduced by BW723C86 treatment. The reduced level of MITF was associated with inhibition of protein kinase A (PKA and cAMP response element-binding protein (CREB activation by BW723C86 treatment. These results suggest that the serotonin agonist BW723C86 could be a potential therapeutic agent for skin hyperpigmentation disorders.

  1. Role of direct covalent bonding in enhanced heat dissipation property of flexible graphene oxide–carbon nanotube hybrid film

    International Nuclear Information System (INIS)

    Hwang, Yongseon; Kim, Myeongjin; Kim, Jooheon

    2013-01-01

    The thermal conductivity of graphene oxide/multiwalled carbon nanotube (GO/MWCNT) hybrid films with and without covalent bonding is examined in this study. To fabricate chemically bonded GO/MWCNT hybrid films, chlorinated GO and amino-functionalized MWCNTs are bonded covalently. The mixtures of surface modified GO and MWCNT were filtered and then subjected to hot pressing to fabricate stacked films. Examination of these chemically bonded hybrid films reveal that chlorine-doped GO exhibits enhanced electrical properties because it creates hole charge carriers by attracting the electrons in GO towards chlorine. Enhanced electrical conductivity and low sheet resistance are observed also with increasing MWCNT loadings. On comparing the through-plane thermal properties, the chemically bonded hybrid films were found to exhibit higher thermal conductivity than do the physically bonded hybrid films because of the synergetic interaction of functional groups in GO and MWCNTs in the former films. However, excess addition of MWCNTs to the films leads to an increasing phonon scattering density and a decreased thermal conductivity. - Highlights: • Graphene oxide/carbon nanotube (GO/CNT) films are bonded covalently. • GO/CNT hybrid films are prepared through filtering and hot-pressing method. • Chemically bonded hybrid films exhibit enhanced electrical and thermal properties. • Enhanced thermal conductivity is explained according to increasing CNT contents

  2. The role of genetic background in susceptibility to chemical warfare nerve agents across rodent and non-human primate models.

    Science.gov (United States)

    Matson, Liana M; McCarren, Hilary S; Cadieux, C Linn; Cerasoli, Douglas M; McDonough, John H

    2018-01-15

    Genetics likely play a role in various responses to nerve agent exposure, as genetic background plays an important role in behavioral, neurological, and physiological responses to environmental stimuli. Mouse strains or selected lines can be used to identify susceptibility based on background genetic features to nerve agent exposure. Additional genetic techniques can then be used to identify mechanisms underlying resistance and sensitivity, with the ultimate goal of developing more effective and targeted therapies. Here, we discuss the available literature on strain and selected line differences in cholinesterase activity levels and response to nerve agent-induced toxicity and seizures. We also discuss the available cholinesterase and toxicity literature across different non-human primate species. The available data suggest that robust genetic differences exist in cholinesterase activity, nerve agent-induced toxicity, and chemical-induced seizures. Available cholinesterase data suggest that acetylcholinesterase activity differs across strains, but are limited by the paucity of carboxylesterase data in strains and selected lines. Toxicity and seizures, two outcomes of nerve agent exposure, have not been fully evaluated for genetic differences, and thus further studies are required to understand baseline strain and selected line differences. Published by Elsevier B.V.

  3. The Role of Backbone Hydrogen Bonds in the Transition State for Protein Folding of a PDZ Domain.

    Directory of Open Access Journals (Sweden)

    Søren W. Pedersen

    Full Text Available Backbone hydrogen bonds are important for the structure and stability of proteins. However, since conventional site-directed mutagenesis cannot be applied to perturb the backbone, the contribution of these hydrogen bonds in protein folding and stability has been assessed only for a very limited set of small proteins. We have here investigated effects of five amide-to-ester mutations in the backbone of a PDZ domain, a 90-residue globular protein domain, to probe the influence of hydrogen bonds in a β-sheet for folding and stability. The amide-to-ester mutation removes NH-mediated hydrogen bonds and destabilizes hydrogen bonds formed by the carbonyl oxygen. The overall stability of the PDZ domain generally decreased for all amide-to-ester mutants due to an increase in the unfolding rate constant. For this particular region of the PDZ domain, it is therefore clear that native hydrogen bonds are formed after crossing of the rate-limiting barrier for folding. Moreover, three of the five amide-to-ester mutants displayed an increase in the folding rate constant suggesting that the hydrogen bonds are involved in non-native interactions in the transition state for folding.

  4. The role of erythropoietin stimulating agents in anemic patients with heart failure: solved and unresolved questions

    Directory of Open Access Journals (Sweden)

    Palazzuoli A

    2014-08-01

    Full Text Available Alberto Palazzuoli, Gaetano Ruocco, Marco Pellegrini, Carmelo De Gori, Gabriele Del Castillo, Nicola Giordano, Ranuccio NutiDepartment of Internal Medicine and Metabolic Diseases, Cardiology Section, Le Scotte Hospital, University of Siena, Siena, ItalyAbstract: Anemia is a common finding in congestive heart failure (CHF and is associated with an increased mortality and morbidity. Several conditions can cause depression of erythroid progenitor cells: reduction of iron absorption and reuptake, decreased bone marrow activity, reduced endogenous erythropoietin production, and chronic inflammatory state. Anemia’s etiology in CHF is complex and partially understood; it involves several systems including impaired hemodynamic condition, reduced kidney and bone perfusion, increased inflammatory activity, and neurohormonal overdrive. The use of erythropoiesis stimulating agents (ESAs such as erythropoietin and its derivatives is recently debated; the last interventional trial seems to demonstrate a neutral or negative effect in the active arm with darbepoetin treatment. The current data is opposite to many single blind studies and previous meta-analysis showing an improvement in quality of life, New York Heart Association class, and exercise tolerance using ESA therapy. These contrasting data raise several concerns regarding the target of hemoglobin levels needing intervention, the exact anemia classification and categorization, and the standardization of hematocrit cutoffs. Some cardiac and systemic conditions (ie, hypertension, atrial fibrillation, prothrombotic status may predispose to adverse events, and ESA administration should be avoided. To prevent the negative effects, high-dosage and chronic administration should be avoided. Clarification of these items could probably identify patients that may benefit from additional iron or ESA treatment. In this review, we discuss the interventional trials made in anemic heart failure patients, the

  5. Catching the role of anisotropic electronic distribution and charge transfer in halogen bonded complexes of noble gases

    Energy Technology Data Exchange (ETDEWEB)

    Bartocci, Alessio; Cappelletti, David; Pirani, Fernando [Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Perugia 06123 (Italy); Belpassi, Leonardo [Istituto di Scienze e Tecnologie Molecolari del CNR, Perugia 06123 (Italy); Falcinelli, Stefano [Dipartimento di Ingegneria Civile ed Ambientale, Università degli Studi di Perugia, 06125 Perugia (Italy); Grandinetti, Felice [Dipartimento per la Innovazione nei sistemi Biologici, Agroalimentari e Forestali (DIBAF), Università della Tuscia, 01100 Viterbo (Italy); Tarantelli, Francesco [Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Perugia 06123 (Italy); Istituto di Scienze e Tecnologie Molecolari del CNR, Perugia 06123 (Italy)

    2015-05-14

    The systems studied in this work are gas-phase weakly bound adducts of the noble-gas (Ng) atoms with CCl{sub 4} and CF{sub 4}. Their investigation was motivated by the widespread current interest for the intermolecular halogen bonding (XB), a structural motif recognized to play a role in fields ranging from elementary processes to biochemistry. The simulation of the static and dynamic behaviors of complex systems featuring XB requires the formulation of reliable and accurate model potentials, whose development relies on the detailed characterization of strength and nature of the interactions occurring in simple exemplary halogenated systems. We thus selected the prototypical Ng-CCl{sub 4} and Ng-CF{sub 4} and performed high-resolution molecular beam scattering experiments to measure the absolute scale of their intermolecular potentials, with high sensitivity. In general, we expected to probe typical van der Waals interactions, consisting of a combination of size (exchange) repulsion with dispersion/induction attraction. For the He/Ne-CF{sub 4}, the analysis of the glory quantum interference pattern, observable in the velocity dependence of the integral cross section, confirmed indeed this expectation. On the other hand, for the He/Ne/Ar-CCl{sub 4}, the scattering data unravelled much deeper potential wells, particularly for certain configurations of the interacting partners. The experimental data can be properly reproduced only including a shifting of the repulsive wall at shorter distances, accompanied by an increased role of the dispersion attraction, and an additional short-range stabilization component. To put these findings on a firmer ground, we performed, for selected geometries of the interacting complexes, accurate theoretical calculations aimed to evaluate the intermolecular interaction and the effects of the complex formation on the electron charge density of the constituting moieties. It was thus ascertained that the adjustments of the potential

  6. The Different Sensitive Behaviors of a Hydrogen-Bond Acidic Polymer-Coated SAW Sensor for Chemical Warfare Agents and Their Simulants

    Directory of Open Access Journals (Sweden)

    Yin Long

    2015-07-01

    Full Text Available A linear hydrogen-bond acidic (HBA linear functionalized polymer (PLF, was deposited onto a bare surface acoustic wave (SAW device to fabricate a chemical sensor. Real-time responses of the sensor to a series of compounds including sarin (GB, dimethyl methylphosphonate (DMMP, mustard gas (HD, chloroethyl ethyl sulphide (2-CEES, 1,5-dichloropentane (DCP and some organic solvents were studied. The results show that the sensor is highly sensitive to GB and DMMP, and has low sensitivity to HD and DCP, as expected. However, the sensor possesses an unexpected high sensitivity toward 2-CEES. This good sensing performance can’t be solely or mainly attributed to the dipole-dipole interaction since the sensor is not sensitive to some high polarity solvents. We believe the lone pair electrons around the sulphur atom of 2-CEES provide an electron-rich site, which facilitates the formation of hydrogen bonding between PLF and 2-CEES. On the contrary, the electron cloud on the sulphur atom of the HD molecule is offset or depleted by its two neighbouring strong electron-withdrawing groups, hence, hydrogen bonding can hardly be formed.

  7. Thermal decay of rhodopsin: role of hydrogen bonds in thermal isomerization of 11-cis retinal in the binding site and hydrolysis of protonated Schiff base.

    Science.gov (United States)

    Liu, Jian; Liu, Monica Yun; Nguyen, Jennifer B; Bhagat, Aditi; Mooney, Victoria; Yan, Elsa C Y

    2009-07-01

    Although thermal stability of the G protein-coupled receptor rhodopsin is directly related to its extremely low dark noise level and has recently generated considerable interest, the chemistry behind the thermal decay process of rhodopsin has remained unclear. Using UV-vis spectroscopy and HPLC analysis, we have demonstrated that the thermal decay of rhodopsin involves both hydrolysis of the protonated Schiff base and thermal isomerization of 11-cis to all-trans retinal. Examining the unfolding of rhodopsin by circular dichroism spectroscopy and measuring the rate of thermal isomerization of 11-cis retinal in solution, we conclude that the observed thermal isomerization of 11-cis to all-trans retinal happens when 11-cis retinal is in the binding pocket of rhodopsin. Furthermore, we demonstrate that solvent deuterium isotope effects are involved in the thermal decay process by decreasing the rates of thermal isomerization and hydrolysis, suggesting that the rate-determining step of these processes involves breaking hydrogen bonds. These results provide insight into understanding the critical role of an extensive hydrogen-bonding network on stabilizing the inactive state of rhodopsin and contribute to our current understanding of the low dark noise level of rhodopsin, which enables this specialized protein to function as an extremely sensitive biological light detector. Because similar hydrogen-bonding networks have also been suggested by structural analysis of two other GPCRs, beta1 and beta2 adrenergic receptors, our results could reveal a general role of hydrogen bonds in facilitating GPCR function.

  8. Aprendizaje de los roles de los agentes BIM en la organización de proyectos = Learning the roles of BIM agents in project management

    Directory of Open Access Journals (Sweden)

    Carolina Piña Ramirez

    2017-04-01

    Full Text Available Actualmente la metodología BIM se está desarrollando en todas las ramas de la construcción e ingeniería. La Unión Europea con la Directiva2014/24/UE marca un hito en el mercado, recomendando a los estados miembros el uso de BIM en sus proyectos, y España, por su parte está en fase de desarrollo de una transposición de esa directiva para implantar esa metodología, con el Ministerio de Fomento. Esta transformación del sector nos lleva a la necesidad de instituir profesionales de calidad cuya formación sea la competente para la inmersión en el mercado profesional existente. Por ello, el propósito de este artículo es exportar a la universidad el conocimiento de la relación entre las implicaciones de los agentes intervinientes en la metodología BIM y las fases de un proyecto. Este trabajo tiene como finalidad de conseguir una mejora en la enseñanza del Graduado en Ingeniería de la Edificación de la Universidad Politécnica de Madrid, hacia el cambio BIM. Abstract Currently the BIM methodology is being developed in all branches of construction and engineering. The European Union with the Directive2014/2/EU set a benchmark in the market, recommending to Member States the use of BIM in projects. Spain is actually in the process of developing a transposition of that directive to implement that methodology. This sector transformation makes it necessary to train professionals with adequate training to be immerse in the market. Therefore, the aim of this article is to export to the university the knowledge of the relationship between the implications of the intervening agents in the BIM methodology and the phases of a project. This has the purpose of obtaining an improvement in the teaching of the Graduate in Engineering of the Building of the Polytechnic University of Madrid, towards the BIM change.

  9. Fatigue aging of adhesive bonds

    International Nuclear Information System (INIS)

    DeLollis, N.J.

    1979-01-01

    A year long study has been made of the effect of fatigue on the bond between two epoxy encapsulant formulations and a fused alumina disc. The variables studied included isothermal aging at temperatures up to and including the cure temperature and cyclic thermal aging from +74 to -54 0 C. The encapsulants were glass microballoon filled epoxies differing only in curing agents. One was cured with an aromatic amine eutectic (Shell Curing Agent Z). The other was cured with diethanolamine. The Z cured encapsulant bond failed completely at the bond interface with little or no aging; infrared evidence indicated a soluble interlayer as a possible cause of failure. The diethanolamine cured encapsulant survived a year of isothermal aging with little or no evidence of bond degradation. Cyclic thermal aging resulted in gradual bond failure with time. An extrapolation of the cyclic aging data indicates that the stresses induced by thermal cycling would result in complete bond failure in about 1200 days

  10. The role that bond coat depletion of aluminum has on the lifetime of APS-TBC under oxidizing conditions

    Energy Technology Data Exchange (ETDEWEB)

    Renusch, D.; Schorr, M.; Schuetze, M. [Karl-Winnacker-Institut der DECHEMA e.V., D-60486 Frankfurt am Main (Germany)

    2008-07-15

    Bond coat oxidation as well as bond coat depletion of Al are still believed to be a major degradation mechanism with respect to the lifetime of thermal barrier coating (TBC) systems. In this study the top coat lifetime is described as being limited by both bond coat depletion of Al and mechanical failure of the top coat. The empirical results are introduced by considering three spallation cases, namely, Al depletion failure, thermal fatigue failure, and thermal aging failure. Al depletion failure occurs when the Al content within the bond coat reaches a critical value. In this paper bond coat depletion of Al is modeled by considering the diffusion of Al into both the thermally grown oxide (TGO) and substrate. The diffusion model results are compared to Al concentration profiles measured with an electron beam microprobe. These measured results are from oxidized air plasma sprayed TBC systems (APS-TBC) with vacuum plasma sprayed (VPS) bond coats for exposures up to 5000 h in the temperature range of 950-1100 C. This paper focuses on the Al depletion failure and how it relates to top coat spallation. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  11. Sexism in Language: Do Fiction Writers Assign Agentive and Patient Roles Equally to Male and Female Characters?

    Directory of Open Access Journals (Sweden)

    Dunlop Ochieng

    2012-10-01

    Full Text Available Problem Statement: Studies have shown that language is used discriminatorily to women and men. Hence, there have been movements against gender biased language−the movements which are reported so successful especially in the West.Purpose of Study: This paper however argues that discrimination stems from speakers’ minds; and hence performing gender neutral language alone does not confirm gender neutrality of the performer. The reliable way of judging gender neutrality would then be studying the speakers’ minds.Method: The study applied psychoanalytic literary criticism as a gateway to the unconscious minds of American authors–to find out how gender neutral they were at cognitive level. Through psychoanalytic literary criticism, authors’ suppressed desires would find their way out onto their works in a distorted form. Along these lines, the study assessed the equality in assigning agentive and patient semantic roles between males and females in American fictions–to find out who between males and females were frequently assigned agentive and patient roles of the reciprocal verbs: kiss, hug, marry, and divorce.Findings: The study found out that males were assigned more agentive roles in kiss and hug, and females in divorce. Moreover, both were assigned almost equal roles in marry.Conclusion: The implication of the findings is that speakers’ unconscious mind is basically gender biased along gender stereotypes.

  12. Influence of carbamide peroxide-based bleaching agents on the bond strength of resin-enamel/dentin interfaces Influência de agentes clareadores à base de peróxido de carbamida na resistência de união entre resina-esmalte/dentina

    Directory of Open Access Journals (Sweden)

    Vanessa Cavalli

    2005-03-01

    Full Text Available In this bond strength study, a bleaching agent containing 10% carbamide peroxide was applied over composite-teeth bonded interfaces of two adhesive systems applied to enamel and dentin. Sixteen human third molars were used for bonding procedures. Single Bond (SB and Clearfil SE Bond (CB were applied to enamel and dentin according to the manufacturers' instructions. A resin composite cube-like structure was incrementally built on the bonded surfaces. The restored teeth were sectioned into 0.7 mm thick slices that were trimmed at enamel or dentin bonded interfaces to an hourglass shape with a cross-sectional area of approximately 0.5 mm². Specimens were assigned to 8 groups (n = 10 according to the following factors under study: dental substrate (enamel and dentin; adhesive system (SB and CB and treatment (10% carbamide peroxide and not bleached/control. The bleaching gel (Opalescence was applied at the bonded interfaces for 6 hours during 14 days and after daily treatment specimens were stored in artificial saliva. Unbleached specimens were stored in artificial saliva for 14 days. Specimens were tested for tension and the data were analyzed by three-way ANOVA and Tukey's test (p Este estudo avaliou a resistência de união de dois sistemas adesivos ao esmalte e à dentina após a aplicação de agente clareador sobre a união compósito-dente. Dezesseis terceiros molares humanos foram usados nos procedimentos restauradores. Single Bond (SB e Clearfil SE Bond (CB foram aplicados no esmalte e na dentina de acordo com as instruções dos fabricantes. Um bloco de compósito foi construído nas superfícies tratadas com os adesivos. Os dentes restaurados foram seccionados em fatias com espessura de 0,7 mm, que receberam constrição na interface de união num formato de ampulheta, com área de secção transversal de ± 0,5 mm². Os espécimes foram distribuídos em 8 grupos (n = 10 de acordo com os fatores em estudo: substrato dental (esmalte e

  13. Bond Issues.

    Science.gov (United States)

    Pollack, Rachel H.

    2000-01-01

    Notes trends toward increased borrowing by colleges and universities and offers guidelines for institutions that are considering issuing bonds to raise money for capital projects. Discussion covers advantages of using bond financing, how use of bonds impacts on traditional fund raising, other cautions and concerns, and some troubling aspects of…

  14. Maternal bonding in mothers with postpartum anxiety disorder: the crucial role of subclinical depressive symptoms and maternal avoidance behaviour.

    Science.gov (United States)

    Tietz, A; Zietlow, A-L; Reck, C

    2014-10-01

    Hardly any research has examined the link between postpartum anxiety disorder and maternal bonding. This study examined if postpartum anxiety disorder and maternal bonding are related in the postpartum period. Thereby, subclinical depressive symptoms and specific aspects of an anxious symptomatology were also taken into consideration. The German sample of N = 78 mother-infant dyads is composed of n = 30 mothers with postpartum anxiety disorders but without major or minor depression according to the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) and n = 48 healthy mothers. Subjects were interviewed with the Structured Clinical Interview for DSM-IV Disorders at an average infant age of M = 4.1 months. Moreover, mothers filled out the Postpartum Bonding Questionnaire-16. The Anxiety Cognitions Questionnaire, the Body Sensations Questionnaire and the Mobility Inventory were chosen to assess different aspects of anxious symptomatology. To control for concurrent subclinical depressive symptoms, we used the German Edinburgh-Postnatal-Depression Scale. Mothers with postpartum anxiety disorder reported significantly lower bonding than healthy mothers. However, in a linear regression analysis, concurrent subclinical depressive symptoms and avoidance of anxiety-related situations in company explained 27 % of the overall variance in maternal bonding. The perceived lower bonding of mothers with anxiety disorder could be due to aspects of a concurrent subclinical depressive symptomatology. This notion emphasizes the need to target even mild depressive symptoms in the treatment of postpartum anxiety disorders. The outcomes also underline that the severity of anxious symptomatology, reflected by avoidance behaviour in company, puts the mother-infant bond at risk.

  15. Optimal Investment in Structured Bonds

    DEFF Research Database (Denmark)

    Jessen, Pernille; Jørgensen, Peter Løchte

    The paper examines the role of structured bonds in the optimal portfolio of a small retail investor. We consider the typical structured bond essentially repacking an exotic option and a zero coupon bond, i.e. an investment with portfolio insurance. The optimal portfolio is found when the investment...

  16. In Vitro Efficacy and Mechanistic Role of Indocyanine Green as a Photodynamic Therapy Agent for Human Melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Mamoon, A.; Gamal-Eldeen, A; Ruppel, M; Smith, R; Tsang, T; Miller, L

    2009-01-01

    Photodynamic therapy (PDT) is a promising treatment for superficial cancer. However, poor therapeutic results have been reported for melanoma, due to the high melanin content. Indocyanine green (ICG) has near infrared absorption (700-800nm) and melanins do not absorb strongly in this area. This study explores the efficiency of ICG as a PDT agent for human melanoma, and its mechanistic role in the cell death pathway.

  17. Direct, simple derivatization of disulfide bonds in proteins with organic mercury in alkaline medium without any chemical pre-reducing agents

    Energy Technology Data Exchange (ETDEWEB)

    Campanella, Beatrice; Onor, Massimo [National Research Council of Italy, C.N.R., Istituto di Chimica dei Composti Organo Metallici-ICCOM- UOS Pisa, Area di Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy); Ferrari, Carlo [National Research Council of Italy, C.N.R., Istituto Nazionale di Ottica, INO-UOS Pisa, Area di Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy); D’Ulivo, Alessandro [National Research Council of Italy, C.N.R., Istituto di Chimica dei Composti Organo Metallici-ICCOM- UOS Pisa, Area di Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy); Bramanti, Emilia, E-mail: bramanti@pi.iccom.cnr.it [National Research Council of Italy, C.N.R., Istituto di Chimica dei Composti Organo Metallici-ICCOM- UOS Pisa, Area di Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy)

    2014-09-16

    Highlights: • A simple procedure for the derivatization of proteins disulfide bonds. • Cysteine groups in several proteins derivatised with pHMB in alkaline media. • 75–100% labelling of cysteines in proteins with pHMB. - Abstract: In this work we have studied the derivatization of protein disulfide bonds with p-Hydroxymercurybenzoate (pHMB) in strong alkaline medium without any preliminary reduction. The reaction has been followed by the determination of the protein–pHMB complex using size exclusion chromatography coupled to a microwave/UV mercury oxidation system for the on-line oxidation of free and protein-complexed pHMB and atomic fluorescence spectrometry (SEC–CVG–AFS) detection. The reaction has been optimized by an experimental design using lysozyme as a model protein and applied to several thiolic proteins. The proposed method reports, for the first time, that it is possible to label 75–100% cysteines of proteins and, thus, to determine thiolic proteins without the need of any reducing step to obtain reduced -SH groups before mercury labelling. We obtained a detection limit of 100 nmol L{sup −1} based on a signal-to-noise ratio of 3 for unbound and complexed pHMB, corresponding to a detection limit of proteins ranged between 3 and 360 nmol L{sup −1}, depending on the number of cysteines in the protein sequence.

  18. Direct, simple derivatization of disulfide bonds in proteins with organic mercury in alkaline medium without any chemical pre-reducing agents

    International Nuclear Information System (INIS)

    Campanella, Beatrice; Onor, Massimo; Ferrari, Carlo; D’Ulivo, Alessandro; Bramanti, Emilia

    2014-01-01

    Highlights: • A simple procedure for the derivatization of proteins disulfide bonds. • Cysteine groups in several proteins derivatised with pHMB in alkaline media. • 75–100% labelling of cysteines in proteins with pHMB. - Abstract: In this work we have studied the derivatization of protein disulfide bonds with p-Hydroxymercurybenzoate (pHMB) in strong alkaline medium without any preliminary reduction. The reaction has been followed by the determination of the protein–pHMB complex using size exclusion chromatography coupled to a microwave/UV mercury oxidation system for the on-line oxidation of free and protein-complexed pHMB and atomic fluorescence spectrometry (SEC–CVG–AFS) detection. The reaction has been optimized by an experimental design using lysozyme as a model protein and applied to several thiolic proteins. The proposed method reports, for the first time, that it is possible to label 75–100% cysteines of proteins and, thus, to determine thiolic proteins without the need of any reducing step to obtain reduced -SH groups before mercury labelling. We obtained a detection limit of 100 nmol L −1 based on a signal-to-noise ratio of 3 for unbound and complexed pHMB, corresponding to a detection limit of proteins ranged between 3 and 360 nmol L −1 , depending on the number of cysteines in the protein sequence

  19. The Role of Potential Agents in Making Spatial Perspective Taking Social

    Directory of Open Access Journals (Sweden)

    Amy M Clements-Stephens

    2013-09-01

    Full Text Available A striking relationship between visual spatial perspective taking (VSPT and social skills has been demonstrated for perspective-taking tasks in which the target of the imagined or inferred perspective is a potential agent, suggesting that the presence of a potential agent may create a social context for the seemingly spatial task of imagining a novel visual perspective. In a series of studies, we set out to investigate how and when a target might be viewed as sufficiently agent-like to incur a social influence on VSPT performance. By varying the perceptual and conceptual features that defined the targets as potential agents, we find that even something as simple as suggesting animacy for a simple wooden block may be sufficient. More critically, we found that experience with one potential agent influenced the performance with subsequent targets, either by inducing or eliminating the influence of social skills on VSPT performance. These carryover effects suggest that the relationship between social skills and VSPT performance is mediated by a complex relationship that includes the task, the target, and the context in which that target is perceived. These findings highlight potential problems that arise when identifying a task as belonging exclusively to a single cognitive domain and stress instead the highly interactive nature of cognitive domains and their susceptibility to cross-domain individual differences.

  20. The Role of Inflation-Indexed Bond in Optimal Management of Defined Contribution Pension Plan During the Decumulation Phase

    Directory of Open Access Journals (Sweden)

    Xiaoyi Zhang

    2018-03-01

    Full Text Available This paper investigates the optimal investment strategy for a defined contribution (DC pension plan during the decumulation phase which is risk-averse and pays close attention to inflation risk. The plan aims to maximize the expected constant relative risk aversion (CRRA utility from the terminal real wealth by investing the fund in a financial market consisting of an inflation-indexed bond, an ordinary zero coupon bond and a risk-free asset. We derive the optimal investment strategy in closed-form using the dynamic programming approach by solving the related Hamilton-Jacobi-Bellman (HJB equation. The results reveal that, with any level of the parameters, an inflation-indexed bond has significant advantage to hedge inflation risk.

  1. Risk for Arrest: The Role of Social Bonds in Protecting Foster Youth Making the Transition to Adulthood

    Science.gov (United States)

    Cusick, Gretchen Ruth; Havlicek, Judy R.; Courtney, Mark E.

    2012-01-01

    This study examines a sample of foster youth at the onset of the transition to adulthood and explores how social bonds are related to the risk of arrest during adulthood. Drawing from official arrest records, event history models are used to examine the time to arrest. Because individuals may be at risk for different types of crime, competing risk regression models are used to distinguish among arrests for drug-related, nonviolent, or violent crimes. Between the ages of 17–18 and 24, 46% of former foster youth experience an arrest. Arrests were evenly distributed across drug, nonviolent, and violent crimes columns. Although findings fail to support the significance of social bonds to interpersonal domains, bonds to employment and education are associated with a lower risk for arrest. Child welfare policy and practice implications for building connections and protections around foster youth are discussed. PMID:22239390

  2. Shear bond strength after dentin bleaching with 10% carbamide peroxide agents Resistência ao cisalhamento da dentina após clareamento com peróxido de carbamida a 10%

    Directory of Open Access Journals (Sweden)

    Roberta Tarkany Basting

    2004-06-01

    Full Text Available This in vitro study evaluated the shear bond strength (SBS of dentin treated with two 10% carbamide peroxide bleaching agents 15 days after bleaching and storage in artificial saliva. Dentin fragments were randomly divided into 3 groups (n = 20 for the treatment with the two different bleaching agents (Rembrandt 10% or Opalescence 10% or with a placebo agent, applied to the tooth surface for 8 hours a day. During the remaining time, the specimens were stored in artificial saliva. After 42 days, the fragments were stored in artificial saliva for 14 days. Another group (n = 20 was exposed to distilled and deionized water for 56 days. An adhesive system and microhybrid composite resin were used to prepare specimens for the SBS test. SBS tests were performed and the fractured surfaces were visually examined using a stereoscope at 30 X magnification. The analysis of variance (ANOVA and SIDAK tests showed higher SBS values for dentin treated with Opalescence 10% than for dentin treated with Rembrandt 10% or placebo. Groups treated with Rembrandt 10%, Opalescence 10% or placebo did not differ from the group treated with distilled and deionized water. Ten percent carbamide peroxide agents or a placebo agent caused no differences in SBS of dentin after 15 days of storage in artificial saliva.Este estudo in vitro avaliou a resistência ao cisalhamento da dentina submetida ao tratamento com dois agentes clareadores contendo peróxido de carbamida a 10% depois de 15 dias de clareamento e armazenagem em saliva artificial. Fragmentos de dentina foram aleatoriamente distribuídos em 3 grupos (n = 20 para receber o tratamento com dois diferentes agentes clareadores (Rembrandt a 10% ou Opalescence a 10% ou com um agente placebo, aplicados na superfície dental por 8 horas diárias. No restante do tempo, os espécimens permaneceram imersos em saliva artificial. Após o tratamento por 42 dias, os fragmentos foram armazenados em saliva artificial por 14 dias. Outro

  3. Genomic phenotyping by barcode sequencing broadly distinguishes between alkylating agents, oxidizing agents, and non-genotoxic agents, and reveals a role for aromatic amino acids in cellular recovery after quinone exposure.

    Science.gov (United States)

    Svensson, J Peter; Quirós Pesudo, Laia; McRee, Siobhan K; Adeleye, Yeyejide; Carmichael, Paul; Samson, Leona D

    2013-01-01

    Toxicity screening of compounds provides a means to identify compounds harmful for human health and the environment. Here, we further develop the technique of genomic phenotyping to improve throughput while maintaining specificity. We exposed cells to eight different compounds that rely on different modes of action: four genotoxic alkylating (methyl methanesulfonate (MMS), N-Methyl-N-nitrosourea (MNU), N,N'-bis(2-chloroethyl)-N-nitroso-urea (BCNU), N-ethylnitrosourea (ENU)), two oxidizing (2-methylnaphthalene-1,4-dione (menadione, MEN), benzene-1,4-diol (hydroquinone, HYQ)), and two non-genotoxic (methyl carbamate (MC) and dimethyl sulfoxide (DMSO)) compounds. A library of S. cerevisiae 4,852 deletion strains, each identifiable by a unique genetic 'barcode', were grown in competition; at different time points the ratio between the strains was assessed by quantitative high throughput 'barcode' sequencing. The method was validated by comparison to previous genomic phenotyping studies and 90% of the strains identified as MMS-sensitive here were also identified as MMS-sensitive in a much lower throughput solid agar screen. The data provide profiles of proteins and pathways needed for recovery after both genotoxic and non-genotoxic compounds. In addition, a novel role for aromatic amino acids in the recovery after treatment with oxidizing agents was suggested. The role of aromatic acids was further validated; the quinone subgroup of oxidizing agents were extremely toxic in cells where tryptophan biosynthesis was compromised.

  4. Genomic phenotyping by barcode sequencing broadly distinguishes between alkylating agents, oxidizing agents, and non-genotoxic agents, and reveals a role for aromatic amino acids in cellular recovery after quinone exposure.

    Directory of Open Access Journals (Sweden)

    J Peter Svensson

    Full Text Available Toxicity screening of compounds provides a means to identify compounds harmful for human health and the environment. Here, we further develop the technique of genomic phenotyping to improve throughput while maintaining specificity. We exposed cells to eight different compounds that rely on different modes of action: four genotoxic alkylating (methyl methanesulfonate (MMS, N-Methyl-N-nitrosourea (MNU, N,N'-bis(2-chloroethyl-N-nitroso-urea (BCNU, N-ethylnitrosourea (ENU, two oxidizing (2-methylnaphthalene-1,4-dione (menadione, MEN, benzene-1,4-diol (hydroquinone, HYQ, and two non-genotoxic (methyl carbamate (MC and dimethyl sulfoxide (DMSO compounds. A library of S. cerevisiae 4,852 deletion strains, each identifiable by a unique genetic 'barcode', were grown in competition; at different time points the ratio between the strains was assessed by quantitative high throughput 'barcode' sequencing. The method was validated by comparison to previous genomic phenotyping studies and 90% of the strains identified as MMS-sensitive here were also identified as MMS-sensitive in a much lower throughput solid agar screen. The data provide profiles of proteins and pathways needed for recovery after both genotoxic and non-genotoxic compounds. In addition, a novel role for aromatic amino acids in the recovery after treatment with oxidizing agents was suggested. The role of aromatic acids was further validated; the quinone subgroup of oxidizing agents were extremely toxic in cells where tryptophan biosynthesis was compromised.

  5. Role of Cell-Cell bond for the viability and the function of vascular smooth muscle cells

    Directory of Open Access Journals (Sweden)

    M. Mura

    2010-01-01

    Full Text Available Vascular smooth muscle cell (VSMC viability and homeostasis is regulated by cell-matrix and cell-cell contact: disruption of these interactions are responsible of a switch from a mature to a high proliferative phenotype. VSMCs migration, rate of growth and apoptosis, and the extent of their extracellular matrix (ECM deposition can be also modulated by proatherogenic peptides. Among them, ATII induces the transactivation of IGF I R, which, together with the binding protein IGFBP3, represents a determinant of cell survival, growth and proliferation. Aim of our in vitro study was to verify the role of elective cell-cell bond in moulating the response to ATII. Thus, we evaluated viability, proliferation, IGFIR, IGFBP3 expression and the long term survival and production of ECM in a provisional tissue. A7r5 cell-line was used in adherent cultures or incubated in agarose-coated culture plates to inhibit cell-matrix interactions. Cells, treated or not with ATII 100 nM, were evaluated for apoptosis rate, cell cycle, IGFIR and IGFBP3 protei expression. Fibrin provisional tissue was developed polymerizing a fibrin solution. cantaining A7r5 cells with thrombin. Histological stainings for ECM components were performed on sections of prvisional tissue. An exclusive cell-cell contact resulted to monolayer cell cultures. ATII did not affect the cell survival in both culture conditions, but promoted a 10% decrease in "S" phase and an increases IGFIR expression only in adherent cells. while suspended cell aggregates were resistant to ATII administration; IGFBP3 was reduced both in ATII treated adherent cells and in floating clustered cells, irrespective of the treatmentn. VSMC conditioning in agarose-coated plates before seeding in fibrin provisional matrix reduced, but not abolished, the cell ability to colonize the clot and to produce ECM. This study demonstrates that the elective cell-cell contact induces a quiescent status in cells lacking of cell

  6. Role of the chemical bonding for the time-dependent electron transport through an interacting quantum dot

    KAUST Repository

    Goker, Ali

    2011-06-01

    A combination of ab initio and many-body calculations is utilized to determine the effects of the bonding in Au electrodes on the time dependent current through a quantum dot suddenly shifted into the Kondo regime by a gate voltage. For an asymmetrically coupled system the instantaneous conductance exhibits fluctuations. The frequencies of the fluctuations turn out to be proportional to the energetic separation between the dominating peaks in the density of states and the Fermi level. The chemical bonding in the electrodes, thus, drastically alters the transient current, which can be accessed by ultrafast pump-probe techniques. © 2011 Elsevier B.V. All rights reserved.

  7. Role of the chemical bonding for the time-dependent electron transport through an interacting quantum dot

    KAUST Repository

    Goker, Ali; Zhu, Zhiyong; Manchon, Aurelien; Schwingenschlö gl, Udo

    2011-01-01

    A combination of ab initio and many-body calculations is utilized to determine the effects of the bonding in Au electrodes on the time dependent current through a quantum dot suddenly shifted into the Kondo regime by a gate voltage. For an asymmetrically coupled system the instantaneous conductance exhibits fluctuations. The frequencies of the fluctuations turn out to be proportional to the energetic separation between the dominating peaks in the density of states and the Fermi level. The chemical bonding in the electrodes, thus, drastically alters the transient current, which can be accessed by ultrafast pump-probe techniques. © 2011 Elsevier B.V. All rights reserved.

  8. Photoisomerization Mechanism of Ruthenium Sulfoxide Complexes: Role of the Metal-Centered Excited State in the Bond Rupture and Bond Construction Processes.

    Science.gov (United States)

    Li, Huifang; Zhang, Lisheng; Zheng, Lvyin; Li, Xun; Fan, Xiaolin; Zhao, Yi

    2016-09-26

    Phototriggered intramolecular isomerization in a series of ruthenium sulfoxide complexes, [Ru(L)(tpy)(DMSO)](n+) (where tpy=2,2':6',2''-terpyridine; DMSO=dimethyl sulfoxide; L=2,2'-bipyridine (bpy), n=2; N,N,N',N'-tetramethylethylenediamine (tmen) n=2; picolinate (pic), n=1; acetylacetonate (acac), n=1; oxalate (ox), n=0; malonate (mal), n=0), was investigated theoretically. It is observed that the metal-centered ligand field ((3) MC) state plays an important role in the excited state S→O isomerization of the coordinated DMSO ligand. If the population of (3) MCS state is thermally accessible and no (3) MCO can be populated from this state, photoisomerization will be turned off because the (3) MCS excited state is expected to lead to fast radiationless decay back to the original (1) GSS ground state or photodecomposition along the Ru(2+) -S stretching coordinate. On the contrary, if the population of (3) MCS (or (3) MCO ) state is inaccessible, photoinduced S→O isomerization can proceed adiabatically on the potential energy surface of the metal-to-ligand charge transfer excited states ((3) MLCTS →(3) MLCTO ). It is hoped that these results can provide valuable information for the excited state isomerization in photochromic d(6) transition-metal complexes, which is both experimentally and intellectually challenging as a field of study. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Bifunctional RuII -Complex-Catalysed Tandem C-C Bond Formation: Efficient and Atom Economical Strategy for the Utilisation of Alcohols as Alkylating Agents.

    Science.gov (United States)

    Roy, Bivas Chandra; Chakrabarti, Kaushik; Shee, Sujan; Paul, Subhadeep; Kundu, Sabuj

    2016-12-12

    Catalytic activities of a series of functional bipyridine-based Ru II complexes in β-alkylation of secondary alcohols using primary alcohols were investigated. Bifunctional Ru II complex (3 a) bearing 6,6'-dihydroxy-2,2'-bipyridine (6DHBP) ligand exhibited the highest catalytic activity for this reaction. Using significantly lower catalyst loading (0.1 mol %) dehydrogenative carbon-carbon bond formation between numerous aromatic, aliphatic and heteroatom substituted alcohols were achieved with high selectivity. Notably, for the synthesis of β-alkylated secondary alcohols this protocol is a rare one-pot strategy using a metal-ligand cooperative Ru II system. Remarkably, complex 3 a demonstrated the highest reactivity compared to all the reported transition metal complexes in this reaction. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Role of tin as a reducing agent in iron containing heat absorbing ...

    Indian Academy of Sciences (India)

    Unknown

    infrared region and a narrow weak band for Fe3+ ion at its λmax at around 380 nm was observed in the silicate glass. ... Tin reducing agent; iron heat absorption; silicate glass. 1. ... ing point of aluminium metal is far below than the glass.

  11. New roles and strategies of a research council: intermediation of the principal-agent relationship

    NARCIS (Netherlands)

    van der Meulen, Barend

    2003-01-01

    Research councils have mediated the principal-agent relation between government and science: they are expected to mediate the political and policy interests in scientific research into the world of science and technology and promote the interests of science and technology in the policy world.

  12. Herbal radiation countermeasure agents: promising role in the management of radiological/nuclear exigencies

    International Nuclear Information System (INIS)

    Arora, Rajesh; Sharma, A.; Kumar, R.; Tripathi, R.P.

    2008-01-01

    In the future, there is a need to substantially boost biomass production and employ elicitors/precursors for improving the production of radioprotective compounds from such alternative sources for ensuring a sustainable supply of the high-value, low volume radioprotective molecules. Chemical fingerprinting, identification and characterization of bioactive constituents using modem analytical techniques and evaluation of their multifaceted mode of action at genomic/proteomic level is also the need of the hour. Such data will help in the development of novel, safe and effective radiation countermeasure agents for human use. Herbal radiation countermeasure agents, including several dietary agents, are likely to find large-scale acceptance in most countries in view of their widespread acceptance, holistic mode of action, less toxicity and economical nature. Endeavours made at INMAS in this direction are likely to fructify in coming years and radiation countermeasure agents from several of these herbal sources would become available, possibly several would be obtainable over-the-counter, for use by civilians, military personnel, first emergency responders and other rescue and recovery personnel. (author)

  13. The Role of Attentional Priority of the Agent in the Acquisition of Word Reference.

    Science.gov (United States)

    Grace, Janet; Suci, George J.

    A study is undertaken to determine whether the nonlinguistic priority of the agent of an action facilitates the comprehension of word reference. The subjects were twelve male and twelve female infants at the one word stage of language production. The children were presented with three nonsense names (presented as part of a narration of a filmed…

  14. The Role of Agent Age and Gender for Middle-Grade Girls

    Science.gov (United States)

    Kim, Yanghee

    2016-01-01

    Compared to boys, many girls are more aware of a social context in the learning process and perform better when the environment supports frequent interactions and social relationships. For these girls, embodied agents (animated on-screen characters acting as tutors) could afford simulated social interactions in computer-based learning and thereby…

  15. Teacher's PAT? Multiple-Role Principal-Agent Theory, Education Politics, and Bureaucrat Power

    Science.gov (United States)

    Vanhuysse, Pieter; Sulitzeanu-Kenan, Raanan

    2009-01-01

    This article aims to contribute to current debates about political power and agency relationships in education and other public sectors. In a recent clarion call for a major redirection of political principal-agent theories (PAT), Terry Moe has argued that standard information asymmetries ought no longer to be regarded as the sole foundation of…

  16. Fostering Multimedia Learning of Science: Exploring the Role of an Animated Agent's Image

    Science.gov (United States)

    Dunsworth, Qi; Atkinson, Robert K.

    2007-01-01

    Research suggests that students learn better when studying a picture coupled with narration rather than on-screen text in a computer-based multimedia learning environment. Moreover, combining narration with the visual presence of an animated pedagogical agent may also encourage students to process information deeper than narration or on-screen…

  17. Why Two Smoking Cessation Agents Work Better than One: Role of Craving Suppression

    Science.gov (United States)

    Bolt, Daniel M.; Piper, Megan E.; Theobald, Wendy E.; Baker, Timothy B.

    2012-01-01

    Objective: This research examined why smokers receiving combination medication for smoking cessation are more likely to quit smoking than are those who receive either single agent (monotherapy) or placebo. Method: Data were collected from 1,504 current smokers (58.2% women, 83.9% White; mean age = 44.67 years, SD = 11.08) participating in a…

  18. The role of isotopes in the development of β-adrenoceptor blocking agents

    International Nuclear Information System (INIS)

    Allen, J.

    1987-01-01

    This chapter is devoted to the applications of labelled β-blocking agents in drug development and to the procedures which have been described in the literature for labelling this class of compounds with radioactive or stable isotopes. 149 refs.; 4 figs

  19. The Role of Agent and Social Context in Judgments of Freedom of Speech and Religion.

    Science.gov (United States)

    Helwig, Charles C

    1997-06-01

    This study examined children's, adolescents', and college students' judgments of the rights of child and adult agents to freedom of speech and religion in 3 social contexts: the general level of society, the school, and the family. Two hundred forty participants, evenly divided into 5 grade levels (mean ages 6,6, 8,5,10,6,12,4, and 22,7) made judgments of the legitimacy of authority prohibition, rule evaluation, generalizability, and rule violation for all freedom/social context/agent combinations. Concepts of freedom of speech and religion were found to emerge in the early elementary school years, and endorsements of freedoms were increasingly affected by social context and agent with age. College students were less likely than any other age group to affirm children's freedom of religion in the family context. Considerations of the mental competence and maturity of agents and the potential for harm to ensue from acting on freedoms played an important part in the decisions of older, but not younger, participants.

  20. The role of zoonotic and parasitic agent in bioterrorism the need for ...

    African Journals Online (AJOL)

    As a result of new world era of terrorism in 21st century; terrorist have employed different types of weapons to kill and maim people in soft targets. The risk posed by biological agents as a weapon needs evaluation both historical and technological for a better understanding. From historical and technological point of view ...

  1. The role of research efficiency in the evolution of scientific productivity and impact: An agent-based model

    International Nuclear Information System (INIS)

    You, Zhi-Qiang; Han, Xiao-Pu; Hadzibeganovic, Tarik

    2016-01-01

    We introduce an agent-based model to investigate the effects of production efficiency (PE) and hot field tracing capability (HFTC) on productivity and impact of scientists embedded in a competitive research environment. Agents compete to publish and become cited by occupying the nodes of a citation network calibrated by real-world citation datasets. Our Monte-Carlo simulations reveal that differences in individual performance are strongly related to PE, whereas HFTC alone cannot provide sustainable academic careers under intensely competitive conditions. Remarkably, the negative effect of high competition levels on productivity can be buffered by elevated research efficiency if simultaneously HFTC is sufficiently low. - Highlights: • We study the role of production efficiency (PE) and research topic selectivity in the evolution of performance in academia. • In our model, agents compete to publish and become cited by occupying the nodes of an artificial citation network. • Our agent-based model is calibrated by using datasets from the APS journals and the arxiv.org online preprint repository. • Individual performance is strongly affected by PE, whereas topic selectivity cannot significantly enhance academic success. • With even minimal reductions of research efficiency gaps, fairly profound boosts of scientific careers can be achieved.

  2. The role of research efficiency in the evolution of scientific productivity and impact: An agent-based model

    Energy Technology Data Exchange (ETDEWEB)

    You, Zhi-Qiang [Alibaba Research Center for Complexity Sciences, Hangzhou Normal University, Hangzhou 311121 (China); Institute of Information Economy and Alibaba Business College, Hangzhou Normal University, Hangzhou 311121 (China); Han, Xiao-Pu, E-mail: xp@hznu.edu.cn [Alibaba Research Center for Complexity Sciences, Hangzhou Normal University, Hangzhou 311121 (China); Institute of Information Economy and Alibaba Business College, Hangzhou Normal University, Hangzhou 311121 (China); Hadzibeganovic, Tarik, E-mail: tarik.hadzibeganovic@gmail.com [Department of Psychology, University of Graz, 8010 Graz (Austria)

    2016-02-22

    We introduce an agent-based model to investigate the effects of production efficiency (PE) and hot field tracing capability (HFTC) on productivity and impact of scientists embedded in a competitive research environment. Agents compete to publish and become cited by occupying the nodes of a citation network calibrated by real-world citation datasets. Our Monte-Carlo simulations reveal that differences in individual performance are strongly related to PE, whereas HFTC alone cannot provide sustainable academic careers under intensely competitive conditions. Remarkably, the negative effect of high competition levels on productivity can be buffered by elevated research efficiency if simultaneously HFTC is sufficiently low. - Highlights: • We study the role of production efficiency (PE) and research topic selectivity in the evolution of performance in academia. • In our model, agents compete to publish and become cited by occupying the nodes of an artificial citation network. • Our agent-based model is calibrated by using datasets from the APS journals and the arxiv.org online preprint repository. • Individual performance is strongly affected by PE, whereas topic selectivity cannot significantly enhance academic success. • With even minimal reductions of research efficiency gaps, fairly profound boosts of scientific careers can be achieved.

  3. The Role of Implied Volatility in Forecasting Future Realized Volatility and Jumps in Foreign Exchange, Stock and Bond Markets

    DEFF Research Database (Denmark)

    Christensen, Bent Jesper

    We study the forecasting of future realized volatility in the stock, bond, and foreign exchange markets, as well as the continuous sample path and jump components of this, from variables in the information set, including implied volatility backed out from option prices. Recent nonparametric...

  4. Role of chemotherapy and molecularly targeted agents in the treatment of adenoid cystic carcinoma of the lacrimal gland.

    Science.gov (United States)

    Le Tourneau, Christophe; Razak, Albiruni R A; Levy, Christine; Calugaru, Valentin; Galatoire, Olivier; Dendale, Rémi; Desjardins, Laurence; Gan, Hui K

    2011-11-01

    Adenoid cystic carcinoma (ACC) is the most common malignant epithelial cancer of the lacrimal gland. Despite a slow rate of growth, ACCs are ultimately associated with poor clinical outcome. Given the rarity of this disease, most recommendations regarding therapy are guided by expert opinion and retrospective data rather than level 1 evidence. Surgery and postoperative radiation therapy are commonly used as initial local treatment. In patients at high risk of recurrence, concomitant platinum-based chemotherapy may be added to postoperative radiotherapy in an attempt to enhance radio-sensitivity. While encouraging responses have been reported with intra-arterial neoadjuvant chemotherapy, this strategy is associated with substantial toxicity and should be considered investigational. For patients with metastatic disease not amenable to surgery or radiotherapy, chemotherapy may have a role based on its modest efficacy in non-lacrimal ACC. Similarly, molecular targeted agents may have a role, although the agents tested to date in non-lacrimal ACC have been disappointing. A better understanding of the biology of ACC will be crucial to the future success of developing targeted agents for this disease.

  5. The role of a chemical bond in thermal expansion of TlIn1-xYbxSe2 solid solutions

    International Nuclear Information System (INIS)

    Zarbaliev, M.M.; Sardarova, N.S.; Mamedov, E.G.; Nagiyev, A.B.

    2008-01-01

    Report focuses on the study of the role of the chemical bond in the thermal expansion of solid solutions TLIn 1 -x Yb x Se 2 (0bonds between atoms in a crystal lattice one and the same. It leads to the same temperature changes of enharmonic part of the thermal variations of atoms in the crystal lattice. But the level of anharmonism depends on the character interatomic interaction and temperature, which defined the value of α

  6. Parental Bonding

    Directory of Open Access Journals (Sweden)

    T. Paul de Cock

    2014-08-01

    Full Text Available Estimating the early parent–child bonding relationship can be valuable in research and practice. Retrospective dimensional measures of parental bonding provide a means for assessing the experience of the early parent–child relationship. However, combinations of dimensional scores may provide information that is not readily captured with a dimensional approach. This study was designed to assess the presence of homogeneous groups in the population with similar profiles on parental bonding dimensions. Using a short version of the Parental Bonding Instrument (PBI, three parental bonding dimensions (care, authoritarianism, and overprotection were used to assess the presence of unobserved groups in the population using latent profile analysis. The class solutions were regressed on 23 covariates (demographics, parental psychopathology, loss events, and childhood contextual factors to assess the validity of the class solution. The results indicated four distinct profiles of parental bonding for fathers as well as mothers. Parental bonding profiles were significantly associated with a broad range of covariates. This person-centered approach to parental bonding has broad utility in future research which takes into account the effect of parent–child bonding, especially with regard to “affectionless control” style parenting.

  7. Assay of common sunscreen agents in suncare products by high-performance liquid chromatography on a cyanopropyl-bonded silica column.

    Science.gov (United States)

    Simeoni, Silvia; Tursilli, Rosanna; Bianchi, Anna; Scalia, Santo

    2005-06-15

    A rapid high-performance liquid chromatographic method was developed for the simultaneous assay of eight of the most common sunscreen agents (octyl-methoxycinnamate, oxybenzone, butyl-methoxydibenzoylmethane, octyl-salicilate, methylbenzylidene camphor, octyl-dimethylamminobenzoate, phenylbenzimidazole sulphonic acid and octocrylene) in sun protection products. Evaluation of the influence of different stationary phases and eluents on the separation selectivity showed that optimal resolution was obtained on a cyanopropyl-silica column eluted with methanol-acetonitrile-tetrahydrofuran-aqueous acetic acid. A small adjustment of the proposed chromatographic system (reduction in the aqueous content of the mobile phase) permitted also the determination of the extremely hydrophobic UV filter, methylene bis-benzotriazolyl tetramethylbutylphenol along with three other sunscreen agents, octyl-methoxycinnamate, oxybenzone, butyl-methoxydibenzoylmethane. Recoveries of the UV filters from the spiked formulation were between 95.7 and 103.7% and the precision of the method was better than 6.1% relative standard deviation. The developed HPLC procedure is suitable for quality control and photostability analyses of commercial suncare products.

  8. Untangling the Role of the Capping Agent in Nanocatalysis: Recent Advances and Perspectives

    Directory of Open Access Journals (Sweden)

    Sebastiano Campisi

    2016-11-01

    Full Text Available Capping agents (organic ligands, polymers, surfactants, etc. are a basic component in the synthesis of metal nanoparticles with controlled size and well-defined shape. However, their influence on the performances of nanoparticle-based catalysts is multifaceted and controversial. Indeed, capping agent can act as a “poison”, limiting the accessibility of active sites, as well as a “promoter”, producing improved yields and unpredicted selectivity control. These effects can be ascribed to the creation of a metal-ligand interphase, whose unique properties are responsible for the catalytic behavior. Therefore, understanding the structure of this interphase is of prime interest for the optimization of tailored nanocatalyst design. This review provides an overview of the interfacial key features affecting the catalytic performances and details a selection of related literature examples. Furthermore, we highlight critical points necessary for the design of highly selective and active catalysts with surface and interphase control.

  9. Novel Role of Carbon Dioxide as a Selective Agent in Palladium-Catalyzed Cyclotrimerization of Alkynes

    Institute of Scientific and Technical Information of China (English)

    李金恒; 谢叶香

    2004-01-01

    Carbon dioxide was found as a selective agent to promote the palladium-catalyzed cyclotrimerization of alkynes in water. Both aryl and alkylacetylenes afforded the corresponding cyclotrimerization products regioselectively in high yields using PdCl2, CuCl2, and CO2 as the catalytic system. However, tert-butylacetylene bearing a bulky group gave a dimerization product. Mechanism of this reaction was also discussed.

  10. The possible role of intravenous lipid emulsion in the treatment of chemical warfare agent poisoning

    Directory of Open Access Journals (Sweden)

    Arik Eisenkraft

    Full Text Available Organophosphates (OPs are cholinesterase inhibitors that lead to a characteristic toxidrome of hypersecretion, miosis, dyspnea, respiratory insufficiency, convulsions and, without proper and early antidotal treatment, death. Most of these compounds are highly lipophilic. Sulfur mustard is a toxic lipophilic alkylating agent, exerting its damage through alkylation of cellular macromolecules (e.g., DNA, proteins and intense activation of pro-inflammatory pathways. Currently approved antidotes against OPs include the peripheral anticholinergic drug atropine and an oxime that reactivates the inhibited cholinesterase. Benzodiazepines are used to stop organophosphate-induced seizures. Despite these approved drugs, efforts have been made to introduce other medical countermeasures in order to attenuate both the short-term and long-term clinical effects following exposure. Currently, there is no antidote against sulfur mustard poisoning. Intravenous lipid emulsions are used as a source of calories in parenteral nutrition. In recent years, efficacy of lipid emulsions has been shown in the treatment of poisoning by fat-soluble compounds in animal models as well as clinically in humans. In this review we discuss the usefulness of intravenous lipid emulsions as an adjunct to the in-hospital treatment of chemical warfare agent poisoning. Keywords: Intravenous lipid emulsion, Organophosphates, Sulfur mustard, Antidotes, Poisoning, Chemical Warfare agents

  11. Bond strength of compomers to dentin using acidic primers.

    Science.gov (United States)

    Tate, W H; You, C; Powers, J M

    1999-10-01

    To determine the in vitro bond strengths of seven compomer/bonding agent restorative systems to human dentin. Seven compomer/bonding agents were bonded to human dentin, stored in water at 37 degrees C for 24 hours, and debonded in tension. Bonding conditions were with and without phosphoric acid etching, with and without the use of combined primer/bonding agents, and under moist and wet bond interfaces. Without phosphoric acid etching, F2000/F2000 Compomer Primer/Adhesive and F2000/Single Bond Dental Adhesive System were less sensitive to dentin wetness. With moist dentin, bond strengths of Dyract/Prime & Bond 2.1, Dyract AP/Prime & Bond 2.1, Hytac/OSB light-curing, one-component bonding agent, F2000/Single Bond, and Freedom/STAE single component light-cured dentin/enamel adhesive system, were improved with phosphoric acid etching. Also, with moist dentin, the bond strength of F2000/F2000 Compomer Primer/Adhesive in the 3M Clicker dispensing system was higher without phosphoric acid etching, whereas bonds of Compoglass/Syntac Single-component were not affected by phosphoric acid etching. Bonding did not occur without primer/bonding agent, regardless of surface condition or use of phosphoric acid etching.

  12. Role of hydrogen-bonding and its interplay with octahedral tilting in CH3NH3PbI3

    OpenAIRE

    Lee, Paul David; Bristowe, Nicholas C; Bristowe, Paul D; Cheetham, Anthony Kevin

    2015-01-01

    First principles calculations on the hybrid perovskite CH3NH3PbI3 predict strong hydrogen-bonding which influences the structure and dynamics of the methylammonium cation and reveal its interaction with the tilting of the PbI6 octahedra. The calculated atomic coordinates are in excellent agreement with neutron diffraction results. [Image - see article] Funding from the Winton Programme for the Physics of Sustainability at the University of Cambridge is gratefully acknowledged. NCB acknowle...

  13. Role of the brain dopaminergic and opioid system in the regulation of "child's" (maternal bonding) behavior of newborn albino rats.

    Science.gov (United States)

    Stovolosov, I S; Dubynin, V A; Kamensky, A A

    2011-01-01

    Administration of D(2) receptor antagonist clebopride in a dose not affecting locomotor activity was followed by a decrease in maternal bonding behavior of 10-day-old and 15-day-old albino rat pups. D(1) receptor antagonist SCH23390 had a stimulatory effect only on the behavior of 10-day-old newborns. Opioid peptide β-casomorphin-7 abolished the effect of clebopride in rat pups of the older age group.

  14. Different redox sensitivity of endoplasmic reticulum associated degradation clients suggests a novel role for disulphide bonds in secretory proteins.

    Science.gov (United States)

    Medraño-Fernandez, Iria; Fagioli, Claudio; Mezghrani, Alexandre; Otsu, Mieko; Sitia, Roberto

    2014-04-01

    To maintain proteostasis in the endoplasmic reticulum (ER), terminally misfolded secretory proteins must be recognized, partially unfolded, and dislocated to the cytosol for proteasomal destruction, in a complex process called ER-associated degradation (ERAD). Dislocation implies reduction of inter-chain disulphide bonds. When in its reduced form, protein disulphide isomerase (PDI) can act not only as a reductase but also as an unfoldase, preparing substrates for dislocation. PDI oxidation by Ero1 favours substrate release and transport across the ER membrane. Here we addressed the redox dependency of ERAD and found that DTT stimulates the dislocation of proteins with DTT-resistant disulphide bonds (i.e., orphan Ig-μ chains) but stabilizes a ribophorin mutant (Ri332) devoid of them. DTT promotes the association of Ri332, but not of Ig-µ, with PDI. This discrepancy may suggest that disulphide bonds in cargo proteins can be utilized to oxidize PDI, hence facilitating substrate detachment and degradation also in the absence of Ero1. Accordingly, Ero1 silencing retards Ri332 degradation, but has little if any effect on Ig-µ. Thus, some disulphides can increase the stability and simultaneously favour quality control of secretory proteins.

  15. O hydrogen bonds in alkaloids

    Indian Academy of Sciences (India)

    An overview of general classification scheme, medicinal importance and crystal structure analysis with emphasis on the role of hydrogen bonding in some alkaloids is presented in this paper. The article is based on a general kind of survey while crystallographic analysis and role of hydrogen bonding are limited to only ...

  16. Simulation of the Role of Government in Spatial Agent-Based Model

    Directory of Open Access Journals (Sweden)

    Viktor Ivanovich Suslov

    2016-09-01

    Full Text Available The paper describes the further development of an agent-based multiregional input-output model of the Russian economy. We consider the idea of incorporating the government into the model and analyze the results of experimental calculations for the conditional example of spatial economy. New agents are included into the model such as the federal and regional governments, pension fund and also the state enterprises producing public goods at the federal and regional levels. The government sets four types of taxes (personal and business income taxes, VAT and payroll taxes, ensures the provision of public goods and provides social, investment and interbudgetary transfers to households, firms and budgets. Social transfers consist of social assistance and unemployment benefits. The utility functions of households are expanded by the terms associated with national and regional public goods. The budget policy is designed in accordance with the maximization of isoelastic function of social welfare that formalizes the choice between the different concepts of social justice. The Gini index is used for the monitoring the inequality of income distribution. The results of experimental calculations present the convergence of the new version of the model to the state of quasi-equilibrium. The special attention is paid an optimal level of the taxation maximizing the social welfare function. Four variants of the optimal tax rates are defined: for three major taxes at a fixed proportion of rates and for each of the tax separately at zero rates of two other taxes. The further directions of modelling are identified, they allow to investigate the spatial development of the Russian economy taking into account the decision-making by private agents in responding to government policies.

  17. The intertemporal choice behaviour. The role of emotions in a multi-agent decision problem

    Directory of Open Access Journals (Sweden)

    Angelarosa Longo

    2015-12-01

    Full Text Available Decision Neuroscience has shown positive and negative side of emotions in intertemporal choices. Psychological evidences, indeed, point out anomalies (impulsivity modifies the discount function of each individual and the false consensus effect which increases the degree of consensus in a multi-agent decision problem. An experiment (Engelmann and Strobel 2004 demonstrates that the relevance of the false consensus effect depends on the difficulty of the information retrieval, so the underlying mechanism is an information processing deficiency rather than egocentricity. We demonstrate that emotions can not cause anomalies in a cooperative strategic interaction because information is explicit.

  18. The role of socializing agents in communicating healthy eating to adolescents

    DEFF Research Database (Denmark)

    Chan, Kara; Prendergast, Gerard; Grønhøj, Alice

    A survey was conducted of 386 Danish and Hong Kong adolescents aged 11 to 16. Looking at socializing agents, respondents claimed that parents asked them to eat healthy food more often than the government publicity, teachers or friends. Parents were also perceived as being the most effective sourc...... five advertising appeals....... in encouraging them to eat healthy food. Respondents considered news and fear appeals for communicating healthy eating the most effective, while popularity and achievement appeals were considered less effective. Respondents with higher collectivism scores showed a higher liking and perceived effectiveness of all...

  19. [The role of Marisa cornuarietis as a biological control agent and its economic and epidemiological implications].

    Science.gov (United States)

    Ferrer López, J R; Moné, H; Perera de Puga, G; Yong Cong, M

    1991-01-01

    It was determined that M. cornuarietis, a mollusk which has been used as agent for the biological control of the schistosomiasis hosts, may be a plague for rice fields. Each mollusk can consume 0.3 g of this plant in 24 hours, accounting for the destruction of 0.015 m2 of a rice field. On the other hand, it was observed that B. glabrata shows preference for the consumption of M. cornuarietis faeces. This fact favors the vector's growth and reproduction rate and at the same time decreases its mortality.

  20. Protective roles of bacterioruberin and intracellular KCl in the resistance of Halobacterium salinarium against DNA-damaging agents

    International Nuclear Information System (INIS)

    Shahmohammadi, H.R.; Asgarani, E.; Terato, Hiroaki; Saito, Takeshi; Ohyama, Yoshihiko; Gekko, Kunihiko; Yamamoto, Osamu; Ide, Hiroshi

    1998-01-01

    Halobacterium salinarium, a member of the extremely halophilic archaebacteria, contains a C 50 -carotenoid namely bacterioruberin. We have previously reported the high resistance of this organism against the lethal actions of DNA-damaging agents including ionizing radiation and ultraviolet light (UV). In this study, we have examined whether bacterioruberin and the highly concentrated salts in this bacterium play protective roles against the lethal actions of ionizing radiation, UV, hydrogen peroxide, and mitomycin-C (MMC). The colourless mutant of H. salinarium deficient in bacterioruberin was more sensitive than the red-pigmented wild-type to all tested DNA-damaging agents except MMC. Circular dichroism (CD) spectra of H. salinarium chromosomal DNA at various concentrations of KCl (0-3.5 M) were similar to that of B-DNA, indicating that no conformational changes occurred as a result of high salt concentrations. However, DNA strand-breaks induced by ionizing radiation were significantly reduced by the presence of either bacterioruberin or concentrated KCl, presumably due to scavenging of free radicals. These results suggest that bacterioruberin and intracellular KCl of H. salinarium protect this organism against the lethal effects of oxidative DNA-damaging agents. (author)

  1. The role of job satisfaction, work engagement, self-efficacy and agentic capacities on nurses' turnover intention and patient satisfaction.

    Science.gov (United States)

    De Simone, Silvia; Planta, Anna; Cicotto, Gianfranco

    2018-02-01

    Nurses' voluntary turnover is a worrying global phenomenon which affects service quality. Retaining nursing staff within a hospital is important to eliminate the negative influence of voluntary turnover on the quality of care and organisation costs. This research helps explain nurses' voluntary turnover by analysing the role of self-efficacy, agentic capacities, job satisfaction, and work engagement on hospital turnover intention, and to study the relationships between these variables and patient satisfaction. This study gathered data from 194 nurses and 181 patients from 22 inpatient wards at two hospitals in southern Italy. Correlation analysis revealed that job satisfaction, work engagement, self-efficacy and agentic capacities were positively interrelated and negatively correlated with turnover intention. Path analysis showed that self-efficacy, some agentic capacities (anticipation and self-regulation), job satisfaction, and work engagement had direct or indirect effects on nurses' turnover intention, and that job satisfaction exerted a stronger effect on turnover intention. Also, patient satisfaction was positively correlated with nurses' job satisfaction, work engagement, self-efficacy, self-regulation and anticipation and negatively correlated with nurses' turnover intention. Results highlighted the importance of implementing actions (for example through feedforward methodology and the goal setting technique) to improve self-efficacy, self-regulation skill, work engagement and job satisfaction in order to reduce nurses' turnover intention and increase patient satisfaction with nursing care. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. The emerging role of antineoplastic agents in the treatment of keloids and hypertrophic scars: a review.

    Science.gov (United States)

    Shridharani, Sachin M; Magarakis, Michael; Manson, Paul N; Singh, Navin K; Basdag, Basak; Rosson, Gedge D

    2010-03-01

    The management of keloids and hypertrophic scars continues to challenge health-care providers. Though both forms of pathologic scarring are distinct entities at the macro and microscopic level, their etiologies and treatment are often similar. Potential treatment approaches are progressing, and combinations of treatment options have been proposed in the literature with promising outcomes. The treatment evolution has reached a level where molecular therapeutic modalities are being investigated. Currently, no gold standard treatment exists. Overall success rates and patient satisfaction seem to be slowly climbing, but additional investigational studies must continue to be performed. Several studies have investigated antineoplastic agents, and there seems to be a marked improvement in rates of recurrence, patient satisfaction, and overall quality of scar when these agents are used. Intralesional injection and/or wound irrigation with interferon-a2b, interferon-g, mitomycin-C, bleomycin, or 5-fluorouracil seems to have a positive effect on the reduction of pathologic scars. There is mounting evidence that these drugs used alone or in combination therapy, have the potential to be an integral part of the treatment paradigm for hypertrophic scars and keloids.

  3. Phentolamine mesylate: It′s role as a reversal agent for unwarranted prolonged local analgesia

    Directory of Open Access Journals (Sweden)

    Harpreet Singh Grover

    2015-01-01

    Full Text Available Administration of local anesthesia is an integral procedure prior to dental treatments to minimize the associated pain. It is learned that its effect stays more than the time required for the dental procedure to be completed. This prolonged soft tissue anesthesia (STA can be detrimental, inconvenient, and unnecessary. Phentolamine mesylate, a Food and Drug Administration-approved drug essentially serves the purpose of faster recovery from numbness at the site of local anesthesia. This article reviews the development of the drug phentolamine mesylate and its indication as a local anesthetic reversal agent. A literature search for phentolamine mesylate as a STA reversal agent was conducted in PubMed using the terms "dental local anesthesia reversal, phentolamine mesylate" up to March 2014. The search was limited to articles published in English. The search revealed 13 PubMed indexed articles stating the development and application of phentolamine mesylate. Phentolamine mesylate is an important step in the progress of developing patient care as well as an aid to the dental clinician.

  4. ON ROLE OF CHONDROPROTECTIVE AGENTS IN OSTEOARTHRITIS: ON THE WAY TO THE EVIDENCE-BASED MEDICINE

    Directory of Open Access Journals (Sweden)

    S. V. Jargin

    2010-01-01

    Full Text Available Chondroitin sulfate, glucosamine and hyaluronic acid (HA applied for the treatment of arthrosis (osteoarthritis are designated as chondroprotective agents. There is evidence in favor of their effectiveness. However, some recent reviews questioned it, while it was noticed that later publications tended to be less positive than older industry-sponsored trials. For intraarticular injections predominantly HA is used. Clinical efficacy of intraarcticular injections and significance of the difference from placebo has been questioned as well. Moreover, no plausible explanation has been found for the discrepancy between the short intraarticular half-life of injected HA and reported long duaration of the positive effect (6-9 months after a course of intraarticular injections. Chondroprotective agents are administered to osteoarthritis patients, including pensioners and citizens with low incomes, who purchase them for a prolonged use. It must be largely equivalent to recommend them, instead of peroral drugs or dietary supplements, a diet modification with consumption of more food containing natural glycosaminoglycans. More comprehensive analysis of literature is required in the process of registration of drugs and dietary supplements.

  5. Toxicity induced by chemical warfare agents: insights on the protective role of melatonin.

    Science.gov (United States)

    Pita, René; Marco-Contelles, José; Ramos, Eva; Del Pino, Javier; Romero, Alejandro

    2013-11-25

    Chemical Warfare Agents (CWAs) are substances that can be used to kill, injure or incapacitate an enemy in warfare, but also against civilian population in terrorist attacks. Many chemical agents are able to generate free radicals and derived reactants, excitotoxicity process, or inflammation, and as consequence they can cause neurological symptoms and damage in different organs. Nowadays, taking into account that total immediate decontamination after exposure is difficult to achieve and there are not completely effective antidotes and treatments against all CWAs, we advance and propose that medical countermeasures against CWAs poisoning would benefit from a broad-spectrum multipotent molecule. Melatonin, a versatile and ubiquitous antioxidant molecule, originally discovered as a hormone synthesized mainly in the pineal gland, has low toxicity and high efficacy in reducing oxidative damage, anti-inflammatory effects by regulation of multiple cellular pathways and properties to prevent excitotoxicity, among others. The purpose of this review is to show the multiple and diverse properties of melatonin, as a pleiotropic indole derivative, and its marked potential for improving human health against the most widely used chemical weapons. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  6. Microstructure control of SOFC cathode material: The role of dispersing agent

    Science.gov (United States)

    Ismail, Ismariza; Jani, Abdul Mutalib Md; Osman, Nafisah

    2017-09-01

    In the present works, La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode powders were synthesized by a sol-gel method with the aid of ethylene glycol which served as the dispersing agent. The phase formation and morphology of the powders were examined by X-Ray diffractometer (XRD) and field emission scanning electron microscopy (FESEM), respectively. The electrochemical properties of the synthesized cathode were obtained using an electrochemical impedance spectroscopy (EIS). The characteristic peaks for LSCF phase appears in the X-ray diffractogram after calcined at 500 °C and complete formation of LSCF single phase was attained at 700 °C. FESEM micrographs showed the presence of spherical particles of the powders with approximate particle size between 10 to 60 nm along with agglomerate morphologies. Well dispersed particles and fewer aggregates were observed for samples prepared with addition of ethylene glycol as the synthesizing aid. The surface area obtained for powder sample prepared with the aid of dispersing agent is 12.0 m2g-1. The EIS measurement results depicts a lower area specific resistance (ASR) obtained for sample prepared with addition of the ethylene glycol as compared to the pristine sample. The present results encourage the optimization of the cathode particle design in order to further improve the cathode performance.

  7. {alpha}-Al{sub 2}O{sub 3} catalyst supports for synthesis gas production: influence of different alumina bonding agents on support and catalyst properties

    Energy Technology Data Exchange (ETDEWEB)

    Marturano, M. [Centro de Investigacion y Desarrollo en Procesos Cataliticos, La Plata (Argentina); Aglietti, E.F. [Centro de Tecnologia de Recursos Minerales y Ceramica (CETMIC), Gonnet (Argentina); Ferretti, O. [Centro de Investigacion y Desarrollo en Procesos Cataliticos, La Plata (Argentina)]|[Univ. Nacional de La Plata, Dept. de Ingenieria Quimica de la Facultad de Ingenieria, La Plata (Argentina)

    1997-02-01

    Aluminas are widely used as catalytic supports in chemical reactions. Reforming reactions to obtain synthesis gas requires good mechanical strength and low sintering behaviour. In this work, the influence of bentonite, aluminium phosphate and alumina gel as binder agents of a calcined {alpha}-Al{sub 2}O{sub 3} are analyzed with respect to support and catalytic properties. The {alpha}-Al{sub 2}O{sub 3} supports, calcined at 1300 C, are then impregnated with solutions of Ni and Al inorganic salts to obtain the catalysts and are finally tested in the reforming reaction of methane to synthesis gas at 500-900 C. Supports and catalysts are characterized by XRD, SEM, N{sub 2} adsorption, mechanical strength test and other techniques. Mechanical strength depends on the type and quantity of binder material used during support preparation. The influence of the support on the performance of the resulting catalyst is evidenced by means of catalytic tests. (orig.) 8 refs.

  8. Evolving perspectives of the role of novel agents in androgen-independent prostate cancer

    Directory of Open Access Journals (Sweden)

    Sujith Kalmadi

    2008-01-01

    Full Text Available Metastatic androgen-independent prostate cancer presents an intriguing clinical challenge, with a subtle interaction between hormone-responsive and refractory tumor cell elements. The treatment of advanced prostate carcinoma, which had remained stagnant for several decades following the understanding of the link between androgenic stimulation and carcinogenesis, has now started to make steady headway with chemotherapy and targeted approaches. Metastatic prostate cancer is almost always treated with initial androgen deprivation, in various forms. However, despite such treatment androgen-independent prostate cancer cells eventually emerge and progress to threaten life. The therapeutic objectives for treatment of metastatic prostate cancer are to maintain the quality of life and prolong survival. The out-dated nihilistic dogma of deferring chemotherapy until the most advanced stages in advanced prostate cancer is now falling by the wayside with the development of newer effective, tolerable agents.

  9. The pleotropic role of statins: Could it be the imminent host modulation agent in periodontics?

    Science.gov (United States)

    Grover, Harpreet Singh; Luthra, Shailly; Maroo, Shruti; Maroo, Niteeka

    2013-03-01

    Periodontal disease is a chronic inflammatory disease which represents a primarily anaerobic Gram-negative oral infection that results in gingival inflammation, loss of attachment, bone destruction. Bacterial endotoxins in the form of lipopolysaccharides (LPS) that are instrumental in generating a host-mediated tissue destructive immune response by mobilizing their defensive cells and releasing cytokines like Interleukin-1β (IL-1β), Tumor Necrosis Factor-α (TNF-α), and Interleukin-6 (IL-6), which lead to tissue destruction by stimulating the production of the collagenolytic enzymes: Matrix metalloproteinases (MMPs). Since the host-mediated tissue destruction is to be controlled, various means have been employed for modulating this response. Statins, 3-hydroxy-3-methylglutarylcoenzyme A (HMG CoA) reductase inhibitors, besides having lipid-lowering abilities also have antioxidant, antithrombotic, anti-inflammatory, immunomodulatory and osteomodulatory properties. All of these pleiotropic effects of statins point out to it perhaps becoming the novel host modulation agent in periodontics.

  10. The role of socializing agents in communicating healthy eating to adolescents

    DEFF Research Database (Denmark)

    Chan, Kara; Prendergast, Gerard; Grønhøj, Alice

    2011-01-01

    A survey was conducted of 386 Danish and Hong Kong adolescents aged 11 to 16. Results showed that the consumption of relatively unhealthy food was common among respondents. Looking at socializing agents, respondents claimed that parents asked them to eat healthy food more often than the governmen....... There were some gender and age differences in the liking and perceived effectiveness of five advertising appeals. Respondents with higher collectivism scores showed a higher liking and perceived effectiveness of advertising appeals....... publicity, teachers or friends. Parents were also perceived as being the most effective source in encouraging them to eat healthy food. Respondents considered news and fear appeals for communicating healthy eating the most effective, while popularity and achievement appeals were considered less effective...

  11. Antioxidant and antigenotoxic role of recombinant human erythropoeitin against alkylating agents: cisplatin and mitomycin C in cultured Vero cells.

    Science.gov (United States)

    Rjiba-Touati, Karima; Ayed-Boussema, Imen; Soualeh, Nidhal; Achour, Abdellatif; Bacha, Hassen; Abid, Salwa

    2013-08-01

    Cisplatin (CDDP) and mitomycin C (MMC), two alkylating agents used against various solid tumours, are a common source of acute kidney injury. Thus, strategies for minimizing CDDP and MMC toxicity are of a clinical interest. In this study, we aimed to investigate the protective role of recombinant human erythropoietin (rhEPO) against oxidative stress and genotoxicity induced by CDDP and MMC in cultured Vero cells. Three types of treatments were performed: (i) cells were treated with rhEPO 24 h before exposure to CDDP/MMC (pre-treatment), (ii) cells were treated with rhEPO and CDDP/MMC simultaneously (co-treatment), (iii) cells were treated with rhEPO 24 h after exposure to CDDP/MMC (post-treatment). Our results showed that rhEPO decreased the reactive oxygen species levels, the malondialdehyde levels and ameliorated glutathione (reduced and oxidized glutathione) modulation induced by CDDP and MMC in cultured Vero cells. Furthermore, rhEPO administration prevented alkylating agents-induced DNA damage accessed by comet test. Altogether, our results suggested a protective role of rhEPO, against CDDP- and MMC-induced oxidative stress and genotoxicity, especially in pre-treatment condition.

  12. Effect of the antitumoral alkylating agent 3-bromopyruvate on mitochondrial respiration: role of mitochondrially bound hexokinase.

    Science.gov (United States)

    Rodrigues-Ferreira, Clara; da Silva, Ana Paula Pereira; Galina, Antonio

    2012-02-01

    The alkylating agent 3-Bromopyruvate (3-BrPA) has been used as an anti-tumoral drug due to its anti-proliferative property in hepatomas cells. This propriety is believed to disturb glycolysis and respiration, which leads to a decreased rate of ATP synthesis. In this study, we evaluated the effects of the alkylating agent 3-BrPA on the respiratory states and the metabolic steps of the mitochondria of mice liver, brain and in human hepatocarcinoma cell line HepG2. The mitochondrial membrane potential (ΔΨ(m)), O(2) consumption and dehydrogenase activities were rapidly dissipated/or inhibited by 3-BrPA in respiration medium containing ADP and succinate as respiratory substrate. 3-BrPA inhibition was reverted by reduced glutathione (GSH). Respiration induced by yeast soluble hexokinase (HK) was rapidly inhibited by 3-BrPA. Similar results were observed using mice brain mitochondria that present HK naturally bound to the outer mitochondrial membrane. When the adenine nucleotide transporter (ANT) was blocked by the carboxyatractiloside, the 3-BrPA effect was significantly delayed. In permeabilized human hepatoma HepG2 cells that present HK type II bound to mitochondria (mt-HK II), the inhibiting effect occurred faster when the endogenous HK activity was activated by 2-deoxyglucose (2-DOG). Inhibition of mt-HK II by glucose-6-phosphate retards the mitochondria to react with 3-BrPA. The HK activities recovered in HepG2 cells treated or not with 3-BrPA were practically the same. These results suggest that mitochondrially bound HK supporting the ADP/ATP exchange activity levels facilitates the 3-BrPA inhibition reaction in tumors mitochondria by a proton motive force-dependent dynamic equilibrium between sensitive and less sensitive SDH in the electron transport system.

  13. Towards quantifying the role of exact exchange in the prediction hydrogen bond spin-spin coupling constants involving fluorine

    Energy Technology Data Exchange (ETDEWEB)

    San Fabián, J.; Omar, S.; García de la Vega, J. M., E-mail: garcia.delavega@uam.es [Departamento de Química Física Aplicada, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid (Spain)

    2016-08-28

    The effect of a fraction of Hartree-Fock exchange on the calculated spin-spin coupling constants involving fluorine through a hydrogen bond is analyzed in detail. Coupling constants calculated using wavefunction methods are revisited in order to get high-level calculations using the same basis set. Accurate MCSCF results are obtained using an additive approach. These constants and their contributions are used as a reference for density functional calculations. Within the density functional theory, the Hartree-Fock exchange functional is split in short- and long-range using a modified version of the Coulomb-attenuating method with the SLYP functional as well as with the original B3LYP. Results support the difficulties for calculating hydrogen bond coupling constants using density functional methods when fluorine nuclei are involved. Coupling constants are very sensitive to the Hartree-Fock exchange and it seems that, contrary to other properties, it is important to include this exchange for short-range interactions. Best functionals are tested in two different groups of complexes: those related with anionic clusters of type [F(HF){sub n}]{sup −} and those formed by difluoroacetylene and either one or two hydrogen fluoride molecules.

  14. The differential role of the media as an agent of political socialization in Europe

    NARCIS (Netherlands)

    Moeller, J.; de Vreese, C.

    2013-01-01

    Declining political involvement of adolescents in western society has caused widespread concerns about the health of democracy in the future. This study investigates the role of the media in the formation of political attitudes and political mobilization of adolescents. Based on a secondary data

  15. Different Roles of Endo- and Exo-cyclic Double Bonds in Limonene Ozonolysis System: Effect of Water and OH Radical Scavengers

    Science.gov (United States)

    Gong, Y.; Li, H.; Chen, Z.

    2017-12-01

    Limonene, as an important monoterpene, has a high emission rate both from biogenic and anthropogenic sources. Its doubly unsaturated structure leads to a high potential for secondary organic aerosol formation and a detailed understanding of roles of endo- and exo-cyclic double bonds in limonene ozonolysis is in urgent need. This study provided new insights into the mechanism and effect of both unsaturated bonds oxidation. A low and a high ratio set of [O3]/[limonene] experiments in the presence or absence of OH scavenger (2-butanol or cyclohexane) in the relative humidity (RH) range of 0-90% were conducted. Molar yields of hydrogen peroxide (H2O2) and hydromethyl hydroperoxide (HMHP) both increased rapidly as RH rose from 0 to 50%, then reached a plateau above 70% RH, while peroxyformic acid (PFA) and peroxyacetic acid (PAA) kept increasing with RH. The ozonolysis of exocyclic double bonds showed larger capacity for producing these peroxides than endocyclic ones, resulting in significantly higher yields of H2O2, HMHP, PFA and PAA in limonene ozonolysis than α-pinene when ozone was sufficient. The SOA mass fraction of total peroxides was 50% at high [O3]/[limonene] ratio, whereas only 12% at low ratio. The gas-particle partitioning coefficient of undetected peroxides rose up from (0.8-2.0)×10-3m3μg-1 at 0% RH to (4.0-5.2)×10-3m3μg-1 at 90% RH, indicating some water-dependent channels contributed low-volatility peroxides formation. A box model was employed to simulate the reaction system, and the results obviously underestimated the yield of H2O2, whilst overestimated the yield of undetected peroxides. It is interesting to note that SOA produced at high [O3]/[limonene] ratio could generate considerable amount of H2O2 in the aqueous phase, which may be another source of H2O2 in cloud drops. To elucidate the mechanism further, the yield of OH radicals formed from endocyclic double bonds was found to be about 3 times larger than that from exocyclic double bonds

  16. The role of bacillus-based biological control agents in integrated pest management systems: plant diseases.

    Science.gov (United States)

    Jacobsen, B J; Zidack, N K; Larson, B J

    2004-11-01

    ABSTRACT Bacillus-based biological control agents (BCAs) have great potential in integrated pest management (IPM) systems; however, relatively little work has been published on integration with other IPM management tools. Unfortunately, most research has focused on BCAs as alternatives to synthetic chemical fungicides or bactericides and not as part of an integrated management system. IPM has had many definitions and this review will use the national coalition for IPM definition: "A sustainable approach to managing pests by combining biological, cultural, physical and chemical tools in a way that minimizes economic, health and environmental risks." This review will examine the integrated use of Bacillus-based BCAs with disease management tools, including resistant cultivars, fungicides or bactericides, or other BCAs. This integration is important because the consistency and degree of disease control by Bacillus-based BCAs is rarely equal to the control afforded by the best fungicides or bactericides. In theory, integration of several tools brings stability to disease management programs. Integration of BCAs with other disease management tools often provides broader crop adaptation and both more efficacious and consistent levels of disease control. This review will also discuss the use of Bacillus-based BCAs in fungicide resistance management. Work with Bacillus thuringiensis and insect pest management is the exception to the relative paucity of reports but will not be the focus of this review.

  17. Follistatin during pregnancy and its potential role as an ovarian suppressing agent.

    Science.gov (United States)

    Köninger, Angela; Schmidt, Börge; Damaske, Daniela; Birdir, Cahit; Enekwe, Antje; Kimmig, Rainer; Strowitzki, Thomas; Gellhaus, Alexandra

    2017-05-01

    Ovarian quiescence is a common condition during pregnancy. In vitro, follistatin, an antagonist of follicle-stimulating hormone, blocks follicular development at early stages, and its serum levels increase during pregnancy. A possible surrogate biomarker of ovarian arrest during pregnancy is a decrease in anti-mullerian hormone (AMH) levels followed by an increase in these levels on the second day after labor. The purpose of this study was to determine whether follistatin could act as an ovarian-suppressing agent during pregnancy. Follistatin levels and AMH levels were determined at various stages of pregnancy and postpartum. The follistatin and AMH levels of 69 patients were retrospectively determined with the AMH Gen II ELISA and with the Human Follistatin Quantikine ELISA Kit. For 49 patients, samples were available from various trimesters for cross-sectional analysis; for the other 20, samples were available longitudinally from day one before labor and then daily on days 1 through 4 after labor. Statistical significance was determined with linear regression, the Friedman rank sum test and the Wilcoxon-Nemenyi-McDonald-Thompson post hoc test. The behavior of follistatin levels was exactly opposite that of AMH levels: Follistatin levels increased significantly during pregnancy and on the first day after parturition but declined afterwards, whereas AMH levels decreased significantly during pregnancy and increased after labor. Follistatin can induce ovarian arrest during pregnancy. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. The pleotropic role of statins: Could it be the imminent host modulation agent in periodontics?

    Directory of Open Access Journals (Sweden)

    Harpreet Singh Grover

    2013-01-01

    Full Text Available Periodontal disease is a chronic inflammatory disease which represents a primarily anaerobic Gram-negative oral infection that results in gingival inflammation, loss of attachment, bone destruction. Bacterial endotoxins in the form of lipopolysaccharides (LPS that are instrumental in generating a host-mediated tissue destructive immune response by mobilizing their defensive cells and releasing cytokines like Interleukin-1β (IL-1β, Tumor Necrosis Factor-α (TNF-α, and Interleukin-6 (IL-6, which lead to tissue destruction by stimulating the production of the collagenolytic enzymes: Matrix metalloproteinases (MMPs. Since the host-mediated tissue destruction is to be controlled, various means have been employed for modulating this response. Statins, 3-hydroxy-3-methylglutarylcoenzyme A (HMG CoA reductase inhibitors, besides having lipid-lowering abilities also have antioxidant, antithrombotic, anti-inflammatory, immunomodulatory and osteomodulatory properties . All of these pleiotropic effects of statins point out to it perhaps becoming the novel host modulation agent in periodontics.

  19. The role of latency reversal agents in the cure of HIV: A review of current data.

    Science.gov (United States)

    Bashiri, Kiandokht; Rezaei, Nima; Nasi, Milena; Cossarizza, Andrea

    2018-04-01

    The definitive cure for human immunodeficiency virus type-1 (HIV) infection is represented by the eradication of the virus from the patient's body. To reach this result, cells that are infected but do not produce the virus must become recognizable to be killed by the immune system. For this purpose, drugs defined "latency reverting agents" (LRA) that reactivate viral production are under investigation. A few clinical studies have been performed in HIV-infected patients treated with LRA and combined antiretroviral therapy (cART). The strategy is thus to combine cART and LRA to reactivate the virus and unmask latently infected cells that, because of cART, cannot produce a fully competent form of the virus. Unmasked cells can present viral antigens to the immune system, that ultimately recognizes and kills such latently infected cells. This review reports and discusses recent studies that have been published on this topic. Copyright © 2018 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.

  20. The role of sourcing service agents in the competitiveness of Mexico as an international sourcing region

    Directory of Open Access Journals (Sweden)

    María del Pilar Ester Arroyo-López

    2015-01-01

    Full Text Available El objetivo de este trabajo fue el explorar y definir los servicios de abastecimiento de terceras partes mexicanas para proporcionar un mejor entendimiento en relación a cómo estos agentes contribuyen al atractivo del país como una región de producción de bajo-costo. Dada la naturaleza exploratoria del estudio, el estudio de caso fue el método cualitativo de investigación elegido. Dos compañías mexicanas asociadas a cadenas de suministro global de diferente tipo –impulsada por el producto e impulsada por el comprador- fueron seleccionadas como casos representativos. La información primaria fue recolectada a través de entrevistas personales a fondo, visitas en sitio y documentos secundarios. A partir del análisis de los dos casos se determina la estructura de gobierno en la cadena, la contribución que realizan las terceras partes a la integración de los proveedores locales a cadenas de suministro globales (CSG así como el valor que sus servicios de tercerización del abasto representa para los compradores internacionales.

  1. Understanding the properties of chitosan aryl substituted thioureas in their role and potential as antibacterial agents

    Science.gov (United States)

    Khairul, Wan M.; Daud, Adibah Izzati; Ismail, Noraznawati

    2018-02-01

    In this study, the effort was to design and synthesize a series of thiourea-chitosan derivatives featuring five aryl substituted members namely N-chitosan-N'-(4-nitrobenzoyl) thiourea (1), N-chitosan-N'-(4-chlorobenzoyl) thiourea (2), N-chitosan-N'-(4-methylbenzoyl) thiourea (3), N-chitosan-N'-(2-iodobenzoyl) thiourea (4), and N-chitosan-N'-(2-methylbenzoyl) thiourea (5) via SN2 reaction pathway having different donating and withdrawing groups. Their molecular structures were then characterised by FT-IR, UV-Vis, and thermogravimetric analysis (TGA). The antimicrobial activities of these derivatives against four species bacteria Bacillus cereus, Staphylococcus aureus, Salmonella typhi, and Escherichia coli of both Gram-positive and Gram-negative type bacteria at minimum concentration 6mg/ml were carried out to investigate their potential as antibacterial agents. Compound 1 exhibited specific activity as it can only inhibit Gram-positive bacteria while other compounds 2-5 showed broad range spectrum activity as they were able to inhibit both Gram-positive and Gram-negative bacteria. Therefore, 1-5 showed good antibacterial activity and have high potential to be further developed as active materials in pharmaceutical interests.

  2. Stability of a metabolizable ester bond in radioimmunoconjugates

    International Nuclear Information System (INIS)

    Arano, Yasushi; Wakisaka, Kouji; Mukai, Takahiro; Uezono, Takashi; Motonari, Hiroshi; Akizawa, Hiromichi; Kairiyama, Claudia; Ohmomo, Yoshiro; Tanaka, Chiaki; Ishiyama, Munetaka; Sakahara, Harumi; Konishi, Junji; Yokoyama, Akira

    1996-01-01

    Ester bonds have been used as metabolizable linkages to reduce radioactivity levels in non-target tissues following the administration of antibodies labeled with metallic radionuclides. In this radiochemical design of antibodies, while the ester bonds should be cleaved rapidly in non-target tissues, high stability of the ester bonds in plasma is also required to preserve target radioactivity levels. To assess the structural requirements to stabilize the ester bond, a new benzyl-EDTA-derived bifunctional chelating agent with an ester bond, (1-[4-[4-(2-maleimidoethoxy)succinamido]benzyl]ethylenediamine-N,N,N',N'- tetraacetic acid; MESS-Bz-EDTA), was developed. MESS-Bz-EDTA was coupled with a thiolated monoclonal antibody (OST7, IgG 1 ) prepared by reducing its disulfide bonds to introduce the ester bond close and proximal to the antibody molecule. For comparison, 1-[4-(5-maleimidopentyl)aminobenzyl]ethylenediamine-N,N,N',N'-tetraacetic acid (EMCS-Bz-EDTA) and meleimidoethyl 3-[ 131 I]iodohippurate (MIH) was coupled to OST7 under the same conjunction chemistry. When incubated in 50% murine plasma or a buffered-solution of neutral pH, OST7-MESS-Bz-EDTA- 111 In rapidly released the radioactivity, and more than 95% of the initial radioactivity was liberated after a 24 h incubation in both solutions, due to a cleavage of the ester bond. On the other hand, only about 20% of the radioactivity was released from OST7-MIH- 131 I in both solutions during the same incubation period. In mice biodistribution studies, while a slightly faster radioactivity clearance from the blood with less radioactivity levels in the liver and kidneys was observed with OST7-MIH- 131 I than with OST7-EMCS-Bz-EDTA- 111 In, OST7-MESS-Bz-EDTA- 111 In indicated radioactivity clearance from the blood much faster than and almost comparable to that of OST7-MIH- 131 I and succinamidobenzyl-EDTA- 111 In, respectively. These findings as well as previous findings on radiolabeled antibodies with ester bonds

  3. The roles of social bonds, personality, and perceived costs: an empirical investigation into Hirschi's "new" control theory.

    Science.gov (United States)

    Intravia, Jonathan; Jones, Shayne; Piquero, Alex R

    2012-12-01

    Hirschi's reconceptualized control theory suggests that social bonds serve as the primary inhibitors to delinquency and that personality-based self-control (PBSC) is not relevant. He also indicates that the number of inhibitors, multiplied by their salience, influences the perceived costs of delinquency. These claims have not been widely tested. Using a large, school-based sample of adolescents, the authors test Hirschi's reconceptualization and find that certain inhibitors (e.g., parental monitoring) are more important than others (e.g., maternal attachment). There are also unique types of costs (e.g., parental costs, peer costs) with differential impacts. Salience exerts a main effect, but there was little evidence to suggest it interacts with costs. Finally, PBSC has the strongest effect. These findings not only offer support for some of Hirschi's claims but also provide directions to better formulate a more comprehensive and empirically supported control theory.

  4. Parental bonds and body dissatisfaction in a clinical sample: The mediating roles of attachment anxiety and media internalization.

    Science.gov (United States)

    Grenon, Renee; Tasca, Giorgio A; Maxwell, Hilary; Balfour, Louise; Proulx, Genevieve; Bissada, Hany

    2016-12-01

    We evaluated an attachment theory model in which mother and father care were hypothesized to be indirectly related to body dissatisfaction mediated by attachment anxiety and media internalization. Participants were 232 women diagnosed with an eating disorder who completed a retrospective measure of parental bonds, and measures of attachment anxiety, media internalization, and body image. Mother care was negatively associated with body dissatisfaction, suggesting that recollection of mothers as less caring was directly related to poorer body image. Lower father care, was indirectly associated with greater body dissatisfaction mediated by higher attachment anxiety and higher media internalization. That is, women with an eating disorder who recollected fathers as less caring had higher attachment anxiety, which was related to greater internalizing of media-related thin ideals, that in turn was associated with poorer body image. Mothers and fathers may impact body dissatisfaction by differing mechanisms in clinical samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Pricing catastrophic bonds for earthquakes in Mexico

    OpenAIRE

    Cabrera, Brenda López

    2006-01-01

    After the occurrence of a natural disaster, the reconstruction can be financed with catastrophic bonds (CAT bonds) or reinsurance. For insurers, reinsurers and other corporations CAT bonds provide multi year protection without the credit risk present in reinsurance. For investors CAT bonds offer attractive returns and reduction of portfolio risk, since CAT bonds defaults are uncorrelated with defaults of other securities. As the study of natural catastrophe models plays an important role in t...

  6. The role of erythropoiesis stimulating agents and intravenous (IV) iron in the cardio renal anemia syndrome.

    Science.gov (United States)

    Silverberg, Donald S

    2011-11-01

    Anemia is common in Congestive Heart Failure (CHF) and is associated with an increased mortality, morbidity and progressive renal failure. The most common causes of the anemia in CHF are (1) the associated Chronic Kidney Disease (CKD), which causes depression of erythropoietin (EPO) production in the kidney, and (2) excessive cytokine production in CHF, which can cause both depression of erythropoietin production in the kidney and depression of erythropoietin response in the bone marrow. The cytokines can also induce iron deficiency by increasing hepcidin production from the liver, which both reduces gastrointestinal iron absorption and reduces iron release from iron stores located in the macrophages and hepatocytes. It appears that iron deficiency is very common in CHF and is rarely recognized or treated. The iron deficiency can cause a thrombocytosis that might contribute to cardiovascular complications in both CHF and CKD and is reversible with iron treatment. Thus, attempts to control this anemia in CHF will have to take into consideration both the use of both Erythropoiesis Stimulating Agents (ESA) such as EPO and oral and, probably more importantly, intravenous (IV) iron. Many studies of anemia in CHF with ESA and oral or IV iron and even with IV iron without ESA have shown a positive effect on hospitalization, New York Heart Association functional class, cardiac and renal function, quality of life, exercise capacity and reduced Beta Natriuretic Peptide and have not demonstrated an increase in cardiovascular damage related to the therapy. However, adequately powered long-term placebo-controlled studies of ESA and of IV iron in CHF are still needed and are currently being carried out.

  7. Urate-Lowering Agents in Asymptomatic Hyperuricemia: Role of Urine Sediment Analysis and Musculoskeletal Ultrasound.

    Science.gov (United States)

    Viggiano, Davide; Gigliotti, Giuseppe; Vallone, Gianfranco; Giammarino, Anna; Nigro, Michelangelo; Capasso, Giovambattista

    2018-01-01

    Current urate-lowering therapy (ULT) includes three direct acting drugs (allopurinol, febuxostat, Rasburicase) and at least four 'indirect' drugs with other important targets (canagliflozin, losartan, fenofibrate and sevelamer). Moreover, the alcalinization of urines using bicarbonate can be used to dissolve urate crystals and the clinician may discontinue several drugs are known to increase serum levels of uric acid, such as diuretics, aspirin, cyclosporine, theophylline, mycophenolate and ACE inhibitors. While there is a consensus to start ULT in cases of symptomatic hyperuricemia (gout, urate-nephrolithiasis), the very frequent conditions of asymptomatic hyperuricemia remains a major conundrum. The effect of asymptomatic hyperuricemia on kidney function has had fluctuating positions over decades. The conflicting results might indicate: (i) the presence of counterbalancing positive and negative effects on kidney function of both serum uric acid and urate-lowering agents, (ii) the presence of a subpopulation of patients, as yet unidentified, which could truly benefit from a urate-lowering therapy. Therefore, today the treatment of asymptomatic hyperuricemia is not recommended nor excluded by current guidelines. Here we suggest that a possible guide for the treatment of asymptomatic hyperuricemia might be the presence of urate crystals in the urine sediment and/or signs of asymptomatic articular damage by urates, identified by musculo-skeletal ultrasound. Moreover, a watchful analysis of the trend in creatinine/eGFR, proteinuria or urate levels might also guide the clinician. Initiation of ULT and follow-up in cases of asymptomatic hyperuricemia should consider urine sediment analysis, musculoskeletal ultrasound and trends in creatinine, proteinuria and serum urate levels. © 2018 The Author(s). Published by S. Karger AG, Basel.

  8. Urate-Lowering Agents in Asymptomatic Hyperuricemia: Role of Urine Sediment Analysis and Musculoskeletal Ultrasound

    Directory of Open Access Journals (Sweden)

    Davide Viggiano

    2018-04-01

    Full Text Available Current urate-lowering therapy (ULT includes three direct acting drugs (allopurinol, febuxostat, Rasburicase and at least four ‘indirect’ drugs with other important targets (canagliflozin, losartan, fenofibrate and sevelamer. Moreover, the alcalinization of urines using bicarbonate can be used to dissolve urate crystals and the clinician may discontinue several drugs are known to increase serum levels of uric acid, such as diuretics, aspirin, cyclosporine, theophylline, mycophenolate and ACE inhibitors. While there is a consensus to start ULT in cases of symptomatic hyperuricemia (gout, urate-nephrolithiasis, the very frequent conditions of asymptomatic hyperuricemia remains a major conundrum. The effect of asymptomatic hyperuricemia on kidney function has had fluctuating positions over decades. The conflicting results might indicate: (i the presence of counterbalancing positive and negative effects on kidney function of both serum uric acid and urate-lowering agents, (ii the presence of a subpopulation of patients, as yet unidentified, which could truly benefit from a urate-lowering therapy. Therefore, today the treatment of asymptomatic hyperuricemia is not recommended nor excluded by current guidelines. Here we suggest that a possible guide for the treatment of asymptomatic hyperuricemia might be the presence of urate crystals in the urine sediment and/or signs of asymptomatic articular damage by urates, identified by musculo-skeletal ultrasound. Moreover, a watchful analysis of the trend in creatinine/eGFR, proteinuria or urate levels might also guide the clinician. Initiation of ULT and follow-up in cases of asymptomatic hyperuricemia should consider urine sediment analysis, musculoskeletal ultrasound and trends in creatinine, proteinuria and serum urate levels.

  9. Role of chicken astrovirus as a causative agent of gout in commercial broilers in India.

    Science.gov (United States)

    Bulbule, N R; Mandakhalikar, K D; Kapgate, S S; Deshmukh, V V; Schat, K A; Chawak, M M

    2013-01-01

    Several outbreaks of gout were reported in commercial broilers in India during 2011 and 2012, causing up to 40% mortality in the birds. Gross and histopathological observations confirmed gout. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) analysis from kidney samples of gout-affected birds indicated the presence of chicken astrovirus (CAstV) in 41.7% of cases and a mixed infection of CAstV and avian nephritis virus (ANV) in 36.4% of cases. CAstV isolated from gout-affected kidneys by inoculating embryonated specific pathogen free (SPF) eggs showed dwarfing in embryos and a cytopathic effect in chicken embryo kidney cells. Inoculation of 1-day-old SPF and broiler chicks with CAstVs caused gout and mortality between 4 and 10 days post inoculation. Virus isolation and qRT-PCR analysis showed the presence of only CAstV in inoculated chicks. Sequence analysis of capsid genes indicated a major group of Indian CAstVs that displayed 92.0 to 99.2% intergroup amino acid identity and 83.9 to 90.4% identity with subgroup Bi CAstVs of UK origin. We designated this group Indian Bi. Analysis of the partial polymerase amino acid sequences of our isolates indicated two groups of CAstVs (Indian 1 and 2) that displayed 90.2 to 95.5% amino acid identity between them. We thus report for the first time that, in addition to infectious bronchitis virus and ANV, CAstVs are a causative agent of gout.

  10. A 2D suspension of active agents: the role of fluid mediated interactions

    International Nuclear Information System (INIS)

    Behmadi, Hojjat; Najafi, Ali; Fazli, Zahra

    2017-01-01

    Taking into account both the Vicsek short-range ordering and the far-field hydrodynamic interactions mediated by the ambient fluid, we investigate the role of long-range interactions in the ordering phenomena in a quasi 2-dimensional active suspension. By studying the number fluctuations, the velocity correlation functions and cluster size distribution function, we show that depending on the number density of swimmers and the strength of noise, the hydrodynamic interactions can have significant effects in a suspension. For a fixed value of noise, at larger density of particles, long-range interactions enhance the particle pairing and cluster formation in the system. (paper)

  11. Exploring the Role of Social Media and Individual Behaviors in Flood Evacuation Processes: An Agent-Based Modeling Approach

    Science.gov (United States)

    Du, Erhu; Cai, Ximing; Sun, Zhiyong; Minsker, Barbara

    2017-11-01

    Flood warnings from various information sources are important for individuals to make evacuation decisions during a flood event. In this study, we develop a general opinion dynamics model to simulate how individuals update their flood hazard awareness when exposed to multiple information sources, including global broadcast, social media, and observations of neighbors' actions. The opinion dynamics model is coupled with a traffic model to simulate the evacuation processes of a residential community with a given transportation network. Through various scenarios, we investigate how social media affect the opinion dynamics and evacuation processes. We find that stronger social media can make evacuation processes more sensitive to the change of global broadcast and neighbor observations, and thus, impose larger uncertainty on evacuation rates (i.e., a large range of evacuation rates corresponding to sources of information). For instance, evacuation rates are lower when social media become more influential and individuals have less trust in global broadcast. Stubborn individuals can significantly affect the opinion dynamics and reduce evacuation rates. In addition, evacuation rates respond to the percentage of stubborn agents in a nonlinear manner, i.e., above a threshold, the impact of stubborn agents will be intensified by stronger social media. These results highlight the role of social media in flood evacuation processes and the need to monitor social media so that misinformation can be corrected in a timely manner. The joint impacts of social media, quality of flood warnings, and transportation capacity on evacuation rates are also discussed.

  12. The role of coal technology in redefining India’s climate change agents and other pollutants

    Science.gov (United States)

    Sahu, S. K.; Ohara, T.; Beig, G.

    2017-10-01

    It is well established that carbon dioxide (CO2) is the most prominent agent of climate change. The level of CO2 in the atmosphere has been increasing persistently over the last few decades due to rising dependence on fossil fuels for energy production. India is facing a potential energy crisis. India has large coal reserves and coal is currently the linchpin of the Indian power sector, making Indian coal-derived emissions a focus of global attention. Further, India’s journey from a challenging energy security situation to the ‘Make in India’ initiative is expected to drive energy needs exponentially. Thus, in the context of a rapidly changing climate, it has become imperative to quantify the emissions of greenhouse gases (GHGs) from emerging coal-based energy plants in India. The present work attempts not only to do this, with the intention of highlighting India’s commitment to reducing CO2 emissions, but also to redefine India’s future emissions. We draw attention to India’s attempt to transform the coal technology used in coal-based thermal power plants. We have tried to adopt a holistic approach to quantify the past (2010), present (2015) and future (2025) emission trends for important GHGs like CO2 and other critical air pollutants from rapidly penetrating low-emission advanced coal technology. Our estimation shows that CO2 emissions will increase from 1065 Tg yr-1 (2015) to 2634 Tg yr-1 (2025), which is approximately 147% of the current value. This rapid increase is largely attributed to rising energy demand due to industrial development, followed by demand from the domestic and agricultural sectors. The present trend of CO2 emissions is sure to propel India to become world’s second largest emitter of GHGs in 2025, dislodging the United States. We have also estimated the emission of other pollutants like NOx, SO2, black carbon, organic carbon, particulate matter (PM2.5, PM10), volatile organic compounds and CO. Our findings seem to suggest

  13. SOCIAL BONDING: REGULATION BY NEUROPEPTIDES

    Directory of Open Access Journals (Sweden)

    Claudia eLieberwirth

    2014-06-01

    Full Text Available Affiliative social relationships (e.g., among spouses, family members, and friends play an essential role in human society. These relationships affect psychological, physiological, and behavioral functions. As positive and enduring bonds are critical for the overall well-being of humans, it is not surprising that considerable effort has been made to study the neurobiological mechanisms that underlie social bonding behaviors. The present review details the involvement of the nonapeptides, oxytocin (OT and arginine vasopressin (AVP, in the regulation of social bonding in mammals including humans. In particular, we will discuss the role of OT and AVP in the formation of social bonds between partners of a mating pair as well as between parents and their offspring. Furthermore, the role of OT and AVP in the formation of interpersonal bonding involving trust is also discussed.

  14. Peak electricity demand and social practice theories: Reframing the role of change agents in the energy sector

    International Nuclear Information System (INIS)

    Strengers, Yolande

    2012-01-01

    Demand managers currently draw on a limited range of psychology and economic theories in order to shift and shed peak electricity demand. These theories place individual consumers and their attitudes, behaviours and choices at the centre of the problem. This paper reframes the issue of peak electricity demand using theories of social practices, contending that the ‘problem’ is one of transforming, technologically-mediated social practices. It reflects on how this body of theory repositions and refocuses the roles and practices of professions charged with the responsibility and agency for affecting and managing energy demand. The paper identifies three areas where demand managers could refocus their attention: (i) enabling co-management relationships with consumers; (ii) working beyond their siloed roles with a broader range of human and non-human actors; and (iii) promoting new practice ‘needs’ and expectations. It concludes by critically reflecting on the limited agency attributed to ‘change agents’ such as demand managers in dominant understandings of change. Instead, the paper proposes the need to identify and establish a new group of change agents who are actively but often unwittingly involved in reconfiguring the elements of problematic peaky practices. - Highlights: ► I reframe peak electricity demand as a problem of changing social practices. ► Micro-grids, and dynamic pricing reorient household routines and enable co-management. ► Infrastructures inside and outside the home configure peaky practices. ► Demand managers are encouraged to promote and challenge consumer ‘needs’. ► I identify a new group of change agents implicated in peaky practices.

  15. Reasoning about emotional agents

    OpenAIRE

    Meyer, J.-J.

    2004-01-01

    In this paper we discuss the role of emotions in artificial agent design, and the use of logic in reasoning about the emotional or affective states an agent can reside in. We do so by extending the KARO framework for reasoning about rational agents appropriately. In particular we formalize in this framework how emotions are related to the action monitoring capabilities of an agent.

  16. Role of residual water hydrogen bonding in sugar/water/biomolecule systems: a possible explanation for trehalose peculiarity

    Energy Technology Data Exchange (ETDEWEB)

    Cordone, L; Cottone, G; Giuffrida, S [Dipartimento di Scienze Fisiche ed Astronomiche, Universita di Palermo and CNISM (Italy)

    2007-05-23

    We report on the set of experimental and simulative evidences which enabled us to suggest how biological structures embedded in a non-liquid water-saccharide solvent are anchored to the surrounding matrix via a hydrogen bond network. Such a network, whose rigidity increases by decreasing the sample water content, couples the degrees of freedom of the biostructure to those of the matrix and gives place to protein-saccharide-water structures (protein-solvent conformational substates). In particular, the whole set of data evidences that, while the protein-sugar interaction is well described in terms of a water entrapment hypothesis, the water replacement hypothesis better describes the sugar-membrane interaction; furthermore, it gives a hint towards the understanding of the origin of the trehalose peculiarity since the biomolecule-matrix coupling, specific to each particular sugar, always results in being the tightest for trehalose. In line with the heterogeneous dynamics in supercooled fluids and in carbohydrate glasses of different residual water contents, recent results confirm, at the single molecule level, the existence of protein-solvent conformational substates, spatially heterogeneous and interconverting, whose rigidity increases by lowering the sample hydration.

  17. Another way of looking at bonding on bimetallic surfaces: the role of spin polarization of surface metal d states

    International Nuclear Information System (INIS)

    Escano, M C; Nguyen, T Q; Nakanishi, H; Kasai, H

    2009-01-01

    The nature of electronic and chemical properties of an unstrained Pt monolayer on a 3d transition metal substrate, M (M = Cr, Mn, Fe), is studied using spin-polarized density functional theory calculations. High spin polarization of Pt d states is noted, verifying the magnetization induced on Pt, which is observed to be responsible for redirecting the analysis of bond formation on a metal surface towards a different perspective. While the shift in the Pt d band center (the average energy of the Pt d band, commonly used to predict the reactivity of surfaces) does give the expected trend in adsorbate (oxygen) chemisorption energy across the bimetallic surfaces in this work, our results show that for spin-polarized Pt d states, the variation in strength of adsorption with respect to the Fermi level density of states is more predictive of Pt chemisorption properties. Hence, this study introduces a scheme for analyzing trends in reactivity of bimetallic surfaces where adsorption energies are used as reactivity parameters and where spin polarization effects cannot be neglected. (fast track communication)

  18. Enhanced Deployment Strategy for Role-based Hierarchical Application Agents in Wireless Sensor Networks with Established Clusterheads

    Science.gov (United States)

    Gendreau, Audrey

    Efficient self-organizing virtual clusterheads that supervise data collection based on their wireless connectivity, risk, and overhead costs, are an important element of Wireless Sensor Networks (WSNs). This function is especially critical during deployment when system resources are allocated to a subsequent application. In the presented research, a model used to deploy intrusion detection capability on a Local Area Network (LAN), in the literature, was extended to develop a role-based hierarchical agent deployment algorithm for a WSN. The resulting model took into consideration the monitoring capability, risk, deployment distribution cost, and monitoring cost associated with each node. Changing the original LAN methodology approach to model a cluster-based sensor network depended on the ability to duplicate a specific parameter that represented the monitoring capability. Furthermore, other parameters derived from a LAN can elevate costs and risk of deployment, as well as jeopardize the success of an application on a WSN. A key component of the approach presented in this research was to reduce the costs when established clusterheads in the network were found to be capable of hosting additional detection agents. In addition, another cost savings component of the study addressed the reduction of vulnerabilities associated with deployment of agents to high volume nodes. The effectiveness of the presented method was validated by comparing it against a type of a power-based scheme that used each node's remaining energy as the deployment value. While available energy is directly related to the model used in the presented method, the study deliberately sought out nodes that were identified with having superior monitoring capability, cost less to create and sustain, and are at low-risk of an attack. This work investigated improving the efficiency of an intrusion detection system (IDS) by using the proposed model to deploy monitoring agents after a temperature sensing

  19. Bonds Boom.

    Science.gov (United States)

    Reynolds, Cathryn

    1989-01-01

    The combined effect of the "Serrano" decision and Proposition 13 left California school districts with aging, overcrowded facilities. Chico schools won a $18.5 million general obligation bond election for facilities construction. With $11 billion needed for new school construction, California will need to tap local sources. A sidebar…

  20. Roles of a solo LuxR in the biological control agent Lysobacter enzymogenes strain OH11.

    Science.gov (United States)

    Qian, Guoliang; Xu, Feifei; Venturi, Vittorio; Du, Liangcheng; Liu, Fengquan

    2014-03-01

    Lysobacter enzymogenes is a ubiquitous plant-associated and environmentally friendly bacterium emerging as a novel biological control agent of plant disease. This bacterium produces diverse antifungal factors, such as lytic enzymes and a secondary metabolite (heat-stable antifungal factor [HSAF]) having antifungal activity with a novel structure and mode of action. The regulatory mechanisms for biosynthesis of antifungal factors is largely unknown in L. enzymogenes. The solo LuxR proteins have been shown to be widespread, playing important roles in plant-associated bacteria. Here, we cloned and studied a solo LuxR protein, LesR, from L. enzymogenes strain OH11. Overexpression but not deletion of lesR significantly impaired HSAF biosynthesis levels and antimicrobial activities but did not show visible effect on production of major lytic enzymes. Overexpression of lesR also led to remarkably accelerated cell aggregation and induced production of a melanin-like pigment in L. enzymogenes; these two phenotypes are mediated by the diffusible factor cell-to-cell signaling system of L. enzymogenes. The C-terminus helix-turn-helix domain was shown to be critical for several lesR-controlled functions. Overall, our study provides the first example of the roles and mechanisms of a solo LuxR protein in a plant-associated L. enzymogenes.

  1. Role of O6-alkylguanine-DNA alkyltransferase in the resistance of mouse spermatogenic cells to O6-alkylating agents.

    Science.gov (United States)

    Thompson, M J; Abdul-Rahman, S; Baker, T G; Rafferty, J A; Margison, G P; Bibby, M C

    2000-07-01

    The O(6)-alkylguanine-DNA alkyltransferase inactivator O(6)-benzylguanine was administered to BALB/c mice either alone or before exposure to 1,3-bis(2-chloroethyl)-1-nitrosourea to study the role of the DNA repair protein O(6)-alkylguanine-DNA alkyltransferase in the protection of the testis against anti-cancer O(6)-alkylating agents. Exposure of the mice to 1, 3-bis(2-chloroethyl)-1-nitrosourea or O(6)-benzylguanine alone did not produce any marked testicular toxicity at the times studied. Testicular O(6)-alkylguanine-DNA alkyltransferase concentrations were assayed between 0 and 240 min after O(6)-benzylguanine treatment and were shown to be > 95% depleted 15 min after treatment with O(6)-benzylguanine and remained at > 95% at all the times assayed. Histological examination, the reduction in testicular mass and the induction of spermatogenic cell apoptosis showed that this depletion significantly potentiated 1, 3-bis(2-chloroethyl)-1-nitrosourea-induced testicular damage after treatment. Major histological damage was apparent 42 days after treatment, demonstrating that the stem spermatogonia were significantly affected by the combination. These results demonstrate that O(6)-alkylguanine-DNA alkyltransferase plays a significant role in protecting the spermatogenic cells from damage caused by DNA alkylation and indicate that the observed toxicity may result from damage to stem spermatogonia.

  2. Role of reducing agent in extraction of arsenic and heavy metals from soils by use of EDTA.

    Science.gov (United States)

    Kim, Eun Jung; Jeon, Eun-Ki; Baek, Kitae

    2016-06-01

    Although many metal-contaminated sites contain both anionic arsenic and cationic heavy metals, the current remediation technologies are not effective for the simultaneous removal of both anionic and cationic elements from the contaminated sites due to their different characteristics. In this study, the role of reducing agent in simultaneous extraction of As, Cu, Pb, and Zn from contaminated soils was investigated using EDTA. The addition of reducing agents, which includes sodium oxalate (Na2C2O4), ascorbic acid (C6H8O6) and sodium dithionite (Na2S2O4), greatly enhanced the EDTA extraction of both As and heavy metals from the contaminated soils due to the increased mobility of the metals under the reduced conditions. The extent of the enhancement of the EDTA extraction was greatly affected by the reducing conditions. Strong reducing conditions (0.1 M of dithionite) were required for the extraction of metals strongly bound to the soil, while weak reducing conditions (0.01 M of dithionite or 0.1 M of oxalate/ascorbic acid) were sufficient for extraction of metals that were relatively weakly bound to the soil. An almost 90% extraction efficiency of total metals (As, Cu, Zn, and Pb) was obtained from the contaminated soils using the combination of dithionite and EDTA. Our results clearly showed that the combination of dithionite and EDTA can effectively extract As and heavy metals simultaneously from soils under a wide range of pH conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Space Shuttle OV-105 Subnominal Bond Investigation

    National Research Council Canada - National Science Library

    Gunn-Golkin, Anna E

    2005-01-01

    ... with Krylon 1201 Spray Starch or MS-143 Mold Release Agent. The research was accomplished by analyzing historical NASA documents, results of bond verification tests, peel tests, contamination tests and fabrication process anomaly tests.

  4. Diffusion bonding

    International Nuclear Information System (INIS)

    Anderson, R.C.

    1976-01-01

    A method is described for joining beryllium to beryllium by diffusion bonding. At least one surface portion of at least two beryllium pieces is coated with nickel. A coated surface portion is positioned in a contiguous relationship with another surface portion and subjected to an environment having an atmosphere at a pressure lower than ambient pressure. A force is applied on the beryllium pieces for causing the contiguous surface portions to abut against each other. The contiguous surface portions are heated to a maximum temperature less than the melting temperature of the beryllium, and the applied force is decreased while increasing the temperature after attaining a temperature substantially above room temperature. A portion of the applied force is maintained at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions

  5. Purpose in life and work-related stress in mariners. Mediating role of quality of marriage bonds and perceived anxiety.

    Science.gov (United States)

    Peplińska, Aleksandra; Jeżewska, Maria; Leszczyńska, Irena; Połomski, Piotr

    2014-01-01

    The specific character of mariners' work is connected with many factors conducive to stress, overload, fatigue and emotional tension, all of which can negatively influence subjective quality of life, including particularly the sense of life's purpose and meaning. However, over the course of entire life one plays many various roles and takes part in many areas of life which influence one another, both positively and negatively. Undoubtedly one of such areas, essential from the point of fulfilling individual's important needs, is one's family and marriage that can function as a crucial factor for neutralising on-the-job problems and tensions. The research presented here attempts to verify the relation between stress perceived by mariners and their sense of purpose in life along with the mediating role of marriage quality and anxiety levels. A total of 210 mariners working on deep-sea ships were examined. The following research tools were applied in the study: the Purpose in Life Test (PIL), the State-Trait Anxiety Inventory (STAI), the Perceived Stress Questionnaire (PSQ) and the Questionnaire of Suitable Marriage (KDM). The results arrived at indicate that both marriage satisfaction and anxiety levels can indeed mediate the relation between stress and sense of purpose in life among mariners.

  6. Liquidity risk premia in corporate bond markets

    NARCIS (Netherlands)

    Driessen, J.J.A.G.; de Jong, F.C.J.M.

    2012-01-01

    This paper explores the role of liquidity risk in the pricing of corporate bonds. We show that corporate bond returns have significant exposures to fluctuations in treasury bond liquidity and equity market liquidity. Further, this liquidity risk is a priced factor for the expected returns on

  7. De Dicto Moral Desires and the Moral Sentiments : Adam Smith on the Role of De Dicto Moral Desires in the Virtuous Agent

    NARCIS (Netherlands)

    Archer, Alfred

    2017-01-01

    What role should a motivation to do the right thing, read de dicto, play in the life of a virtuous agent? According to a prominent argument from Michael Smith, those who are only ever motivated by such a desire are moral fetishists. Smith’s argument is designed to support motivational judgment

  8. Classical group theory adapted to the mechanism of Pt3Ni nanoparticle growth: the role of W(CO)6 as the "shape-controlling" agent.

    Science.gov (United States)

    Radtke, M; Ignaszak, A

    2016-01-07

    Classical group theory was applied to prove the Pt3Ni crystallographic transformation from Platonic cubic to Archimedean cuboctahedral structures and the formation of Pt3Ni polypods. The role of W(CO)6 as a shape-controlling agent is discussed with respect to the crystallographic features of the clusters and superstructures generated as control samples.

  9. Effects of matrix metallproteinases on dentin bonding and strategies to increase durability of dentin adhesion

    Directory of Open Access Journals (Sweden)

    Jung-Hyun Lee

    2012-02-01

    Full Text Available The limited durability of resin-dentin bonds severely compromises the longevity of composite resin restorations. Resin-dentin bond degradation might occur via degradation of water-rich and resin sparse collagen matrices by host-derived matrix metalloproteinases (MMPs. This review article provides overview of current knowledge of the role of MMPs in dentin matrix degradation and four experimental strategies for extending the longevity of resin-dentin bonds. They include: (1 the use of broad-spectrum inhibitors of MMPs, (2 the use of cross-linking agents for silencing the activities of MMPs, (3 ethanol wet-bonding with hydrophobic resin, (4 biomimetic remineralization of water-filled collagen matrix. A combination of these strategies will be able to overcome the limitations in resin-dentin adhesion.

  10. The role of short-range Cys171-Cys178 disulfide bond in maintaining cutinase active site integrity: A molecular dynamics simulation

    International Nuclear Information System (INIS)

    Matak, Mehdi Youssefi; Moghaddam, Majid Erfani

    2009-01-01

    Understanding structural determinants in enzyme active site integrity can provide a good knowledge to design efficient novel catalytic machineries. Fusarium solani pisi cutinase with classic triad Ser-His-Asp is a promising enzyme to scrutinize these structural determinants. We performed two MD simulations: one, with the native structure, and the other with the broken Cys171-Cys178 disulfide bond. This disulfide bond stabilizes a turn in active site on which catalytic Asp175 is located. Functionally important H-bonds and atomic fluctuations in catalytic pocket have been changed. We proposed that this disulfide bond within active site can be considered as an important determinant of cutinase active site structural integrity.

  11. Non-malignant disease mortality in meat workers: a model for studying the role of zoonotic transmissible agents in non-malignant chronic diseases in humans.

    Science.gov (United States)

    Johnson, E S; Zhou, Y; Sall, M; Faramawi, M El; Shah, N; Christopher, A; Lewis, N

    2007-12-01

    Current research efforts have mainly concentrated on evaluating the role of substances present in animal food in the aetiology of chronic diseases in humans, with relatively little attention given to evaluating the role of transmissible agents that are also present. Meat workers are exposed to a variety of transmissible agents present in food animals and their products. This study investigates mortality from non-malignant diseases in workers with these exposures. A cohort mortality study was conducted between 1949 and 1989, of 8520 meat workers in a union in Baltimore, Maryland, who worked in manufacturing plants where animals were killed or processed, and who had high exposures to transmissible agents. Mortality in meat workers was compared with that in a control group of 6081 workers in the same union, and also with the US general population. Risk was estimated by proportional mortality and standardised mortality ratios (SMRs) and relative SMR. A clear excess of mortality from septicaemia, subarachnoid haemorrhage, chronic nephritis, acute and subacute endocarditis, functional diseases of the heart, and decreased risk of mortality from pre-cerebral, cerebral artery stenosis were observed in meat workers when compared to the control group or to the US general population. The authors hypothesise that zoonotic transmissible agents present in food animals and their products may be responsible for the occurrence of some cases of circulatory, neurological and other diseases in meat workers, and possibly in the general population exposed to these agents.

  12. Sibling bereavement and continuing bonds.

    Science.gov (United States)

    Packman, Wendy; Horsley, Heidi; Davies, Betty; Kramer, Robin

    2006-11-01

    Historically, from a Freudian and medical model perspective, emotional disengagement from the deceased was seen as essential to the successful adaptation of bereavement. A major shift in the bereavement literature has occurred and it is now generally accepted that despite the permanence of physical separation, the bereaved remains involved and connected to the deceased and can be emotionally sustained through continuing bonds. The majority of literature has focused on adults and on the nature of continuing bonds following the death of a spouse. In this article, the authors demonstrate how the continuing bonds concept applies to the sibling relationship. We describe the unique continued relationship formed by bereaved children and adolescents following a sibling loss, highlight the factors that influence the siblings continuing bonds expressions, and offer clinical interventions. In our view, mental health professionals can play an important role in helping parents encourage activities that may facilitate the creation and maintenance of continuing bonds in their children.

  13. When artificial social agents try to persuade people : the role of social agency on the occurrence of psychological reactance

    NARCIS (Netherlands)

    Roubroeks, M.A.J.; Ham, J.R.C.; Midden, C.J.H.

    2011-01-01

    In the near future, robotic agents might employ persuasion to influence people’s behavior or attitudes, just as human agents do in many situations. People can comply with these requests, but, people can also experience psychological reactance, which may lead to the complete opposite of the proposed

  14. Reasoning about emotional agents

    NARCIS (Netherlands)

    Meyer, J.-J.

    In this paper we discuss the role of emotions in artificial agent design, and the use of logic in reasoning about the emotional or affective states an agent can reside in. We do so by extending the KARO framework for reasoning about rational agents appropriately. In particular we formalize in

  15. Evidence for a role of the oxytocin system, indexed by genetic variation in CD38, in the social bonding effects of expressed gratitude.

    Science.gov (United States)

    Algoe, Sara B; Way, Baldwin M

    2014-12-01

    Oxytocin is thought to play a central role in promoting close social bonds via influence on social interactions. The current investigation targeted interactions involving expressed gratitude between members of romantic relationships because recent evidence suggests gratitude and its expression provides behavioral and psychological 'glue' to bind individuals closer together. Specifically, we took a genetic approach to test the hypothesis that social interactions involving expressed gratitude would be associated with variation in a gene, CD38, which has been shown to affect oxytocin secretion. A polymorphism (rs6449182) that affects CD38 expression was significantly associated with global relationship satisfaction, perceived partner responsiveness and positive emotions (particularly love) after lab-based interactions, observed behavioral expression of gratitude toward a romantic partner in the lab, and frequency of expressed gratitude in daily life. A separate polymorphism in CD38 (rs3796863) previously associated with plasma oxytocin levels and social engagement was also associated with perceived responsiveness in the benefactor after an expression of gratitude. The combined influence of the two polymorphisms was associated with a broad range of gratitude-related behaviors and feelings. The consistent pattern of findings suggests that the oxytocin system is associated with solidifying the glue that binds adults into meaningful and important relationships. © The Author (2014). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  16. Isolating the Roles of Different Forcing Agents in Global Stratospheric Temperature Changes Using Model Integrations with Incrementally Added Single Forcings

    Science.gov (United States)

    Aquila, V.; Swartz, W. H.; Waugh, D. W.; Colarco, P. R.; Pawson, S.; Polvani, L. M.; Stolarski, R. S.

    2016-01-01

    Satellite instruments show a cooling of global stratospheric temperatures over the whole data record (1979-2014). This cooling is not linear and includes two descending steps in the early 1980s and mid-1990s. The 1979-1995 period is characterized by increasing concentrations of ozone depleting substances (ODS) and by the two major volcanic eruptions of El Chichon (1982) and Mount Pinatubo (1991). The 1995-present period is characterized by decreasing ODS concentrations and by the absence of major volcanic eruptions. Greenhouse gas (GHG) concentrations increase over the whole time period. In order to isolate the roles of different forcing agents in the global stratospheric temperature changes, we performed a set of AMIP-style simulations using the NASA Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM). We find that in our model simulations the cooling of the stratosphere from 1979 to present is mostly driven by changes in GHG concentrations in the middle and upper stratosphere and by GHG and ODS changes in the lower stratosphere. While the cooling trend caused by increasing GHGs is roughly constant over the satellite era, changing ODS concentrations cause a significant stratospheric cooling only up to the mid-1990s, when they start to decrease because of the implementation of the Montreal Protocol. Sporadic volcanic events and the solar cycle have a distinct signature in the time series of stratospheric temperature anomalies but do not play a statistically significant role in the long-term trends from 1979 to 2014. Several factors combine to produce the step-like behavior in the stratospheric temperatures: in the lower stratosphere, the flattening starting in the mid-1990s is due to the decrease in ozone-depleting substances; Mount Pinatubo and the solar cycle cause the abrupt steps through the aerosol-associated warming and the volcanically induced ozone depletion. In the middle and upper stratosphere, changes in solar irradiance are largely

  17. Influência do agente clareador peróxido de carbamida a 10% na resistência mecânica da colagem de braquetes ortodônticos Influence of 10% carbamide peroxide gel on the shear bond strength of orthodontic brackets

    Directory of Open Access Journals (Sweden)

    Edgard Norões R. da Matta

    2005-04-01

    Full Text Available O propósito deste estudo in vitro foi determinar a influência do agente clareador peróxido de carbamida a 10% na resistência mecânica da colagem de braquetes ortodônticos. Foram estudados três grupos denominados G1 (não submetido ao clareamento, G2 (com clareamento e colagem realizada 1 semana após e G3 (com clareamento e colagem realizada 24h após. O teste de cisalhamento foi conduzido na máquina de ensaios mecânicos Emic, com a velocidade de deformação de 0,5 mm/min.A resitência ao cisalhamento em relação à área de colagem foi calculada para cada dente e expressa em MPa. Os resultados mostraram aumento estatisticamente significante (pThe purpose of this in vitro study was to determine the influence of 10% carbamide peroxide gel on the shear bond strength of orthodontic brackets. Three group were studied: G1 (without bleaching, G2 (bleaching and bonding after 1 week and G3 (bleaching and bonding after 24h. The shear test was conduced in a Emic testing machine with a crosshead speed of 0,5 mm/min. The shear bond strength was calculated for each tooth and expressed in MPa. The results show enhance statistical significant (p<0,001 on the shear bond strength after bleaching and encreased with the time interval between bleaching and bonding, significantily.

  18. Pharmacological prevention of reperfusion injury in acute myocardial infarction. A potential role for adenosine as a therapeutic agent.

    Science.gov (United States)

    Quintana, Miguel; Kahan, Thomas; Hjemdahl, Paul

    2004-01-01

    The concept of reperfusion injury, although first recognized from animal studies, is now recognized as a clinical phenomenon that may result in microvascular damage, no-reflow phenomenon, myocardial stunning, myocardial hibernation and ischemic preconditioning. The final consequence of this event is left ventricular (LV) systolic dysfunction leading to increased morbidity and mortality. The typical clinical case of reperfusion injury occurs in acute myocardial infarction (MI) with ST segment elevation in which an occlusion of a major epicardial coronary artery is followed by recanalization of the artery. This may occur either spontaneously or by means of thrombolysis and/or by primary percutaneous coronary intervention (PCI) with efficient platelet inhibition by aspirin (acetylsalicylic acid), clopidogrel and glycoprotein IIb/IIIa inhibitors. Although the pathophysiology of reperfusion injury is complex, the major role that neutrophils play in this process is well known. Neutrophils generate free radicals, degranulation products, arachidonic acid metabolites and platelet-activating factors that interact with endothelial cells, inducing endothelial injury and neutralization of nitrous oxide vasodilator capacity. Adenosine, through its multi-targeted pharmacological actions, is able to inhibit some of the above-mentioned detrimental effects. The net protective of adenosine in in vivo models of reperfusion injury is the reduction of the infarct size, the improvement of the regional myocardial blood flow and of the regional function of the ischemic area. Additionally, adenosine preserves the post-ischemic coronary flow reserve, coronary blood flow and the post-ischemic regional contractility. In small-scale studies in patients with acute MI, treatment with adenosine has been associated with smaller infarcts, less no-reflow phenomenon and improved LV function. During elective PCI adenosine reduced ST segment shifts, lactate production and ischemic symptoms. During the

  19. FATHER, SOCIAL BOND AND WOMEN

    Directory of Open Access Journals (Sweden)

    SYLVIA DE CASTRO KORGI

    2006-05-01

    Full Text Available On the cross-point of two of the most important and inseparable Freudian questions: What is a father?and, What a woman wants?, this paper begins a reflection about the women’s place in the Freudianarticulation of the relationship between the father and the social bond. In fact, the Freudian father, thanksto the law mediation which he is its agent, has as a function the regulation of the pleasure that participatesin the social bond, making this way possible the human community. On the other hand, the support ofthe human community is the bond among brothers, as well as Freud presents it in his foundational textof the Law. How to precise the women’s place in this arrangement? The reflection stands out this thatexceeds the Father’s Law and that Freud sets on women’s account, initially under the figure of heropposition to the culture.

  20. Bond strength of masonry

    NARCIS (Netherlands)

    Pluijm, van der R.; Vermeltfoort, A.Th.

    1992-01-01

    Bond strength is not a well defined property of masonry. Normally three types of bond strength can be distinguished: - tensile bond strength, - shear (and torsional) bond strength, - flexural bond strength. In this contribution the behaviour and strength of masonry in deformation controlled uniaxial

  1. The role of hydrogen bonding in the fluorescence quenching of 2,6-bis((E)-2-(benzoxazol-2-yl)vinyl)naphthalene (BBVN) in methanol

    Science.gov (United States)

    Hammam, Essam; Basahi, Jalal; Ismail, Iqbal; Hassan, Ibrahim; Almeelbi, Talal

    2017-02-01

    The excited state hydrogen bonding dynamics of BBVN in hydrogen donating methanol solvent was explored at the TD-BMK/cc-pVDZ level of theory with accounting for the bulk environment effects at the polarizable continuum model (PCM). The heteroatoms of the BBVN laser dye form hydrogen bonds with four methanol molecules. In the formed BBVN-(MeOH)4 complex, the A-type hydrogen bond (N…HO), of an average strength of 25 kJ mol- 1, is twofold stronger than the B-type (O…HO) one. Upon photon absorption, the total HB binding energy increases from 78.5 kJ mol- 1 in the ground state to 82.6 kJ mol- 1 in the first singlet (S1) excited state. In consequence of the hydrogen bonding interaction, the absorption band maximum of the BBVN-(MeOH)4 complex, which was anticipated at 398 nm (exp. 397), is redshifted by 5 nm relative to that of the free dye in methanol. The spectral shift of the stretching vibrational mode for the hydrogen bonded hydroxyl groups (with a maximum shift of 285 cm- 1) from that of the free methanol indicated the elevated strengthening of hydrogen bonds in the excited state. The vibrational modes associated with hydrogen bonding provide effective accepting modes for the dissipation of the excitation energy, thus, decreasing the fluorescence quantum yield of BBVN in alcohols as compared to that in the polar aprotic solvents. Since there is no sign of photochemistry or phosphorescence, it seems reasonable in view of the outcomes of this study to assign the major decay process of the excited singlet (S1) of BBVN in alcohols to vibronically induced internal conversion (IC) facilitated by hydrogen bonding.

  2. The role of oxytocin in the ability of domestic dogs (Canis familiaris) to use human social cues and bond with humans.

    OpenAIRE

    Oliva, Jessica Lee

    2017-01-01

    The domestic dog (Canis familiaris) demonstrates attachment/bonding behaviour towards humans, whilst wolves (Canis lupus) do not. Domestic dogs also use humans’ non-verbal social cues to solve problems better than wolves do, even wolves raised in the same manner as domestic dogs. The neuropeptide oxytocin has been implicated in mammalian bonding and non-verbal intelligence and therefore the oxytocinergic system may have evolved in the dog during domestication in such a manner as to enable the...

  3. Zinc and resin bonded NdFeB magnets

    International Nuclear Information System (INIS)

    Leonowicz, M.; Kaszuwara, W.

    2002-01-01

    Zinc and resin bonded NdFeB magnets were processed. Basic magnetic parameters as well as compressive strength were evaluated versus annealing temperature and volume fraction of the bonding agent. For the zinc bonded magnets phase composition was investigated. The additional NdZn 5 phase was found in the Zn bonded magnets after annealing. Comparison of the Zn and resin bonded magnets reveals higher remanence for the former and higher coercivity for the latter. For the Zn and resin bonded magnets, 15 wt.% Zn / 370 o C and 7-10 wt.% resin were chosen as the optimal processing parameters. (author)

  4. Composite Bonding to Stainless Steel Crowns Using a New Universal Bonding and Single-Bottle Systems

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Hattan

    2013-01-01

    Full Text Available Aim. The aim of this study is to evaluate the shear bond strength of nanocomposite to stainless steel crowns using a new universal bonding system. Material and Methods. Eighty (80 stainless steel crowns (SSCs were divided into four groups (20 each. Packable nanocomposite was bonded to the lingual surface of the crowns in the following methods: Group A without adhesive (control group, Group B using a new universal adhesive system (Scotchbond Universal Adhesive, 3M ESPE, Seefeld, Germany, and Group C and Group D using two different brands of single-bottle adhesive systems. Shear bond strengths were calculated and the types of failure also were recorded. Results. The shear strength of Group B was significantly greater than that of other groups. No significant differences were found between the shear bond strengths of Groups C and D. The control group had significantly lower shear bond strength ( to composite than the groups that utilized bonding agents. Conclusion. Composites bonding to stainless steel crowns using the new universal bonding agent (Scotchbond Universal Adhesive, 3M ESPE, Seefeld, Germany show significantly greater shear bond strengths and fewer adhesive failures when compared to traditional single-bottle systems.

  5. Comparison of Shear Bond Strengths of three resin systems for a Base Metal Alloy bonded to

    Directory of Open Access Journals (Sweden)

    Jlali H

    1999-12-01

    Full Text Available Resin-bonded fixed partial dentures (F.P.D can be used for conservative treatment of partially edentulous"npatients. There are numerous studies regarding the strength of resin composite bond to base meta! alloys. Shear bond"nstrength of three resin systems were invistigated. In this study these systems consisted of: Panavia Ex, Mirage FLC and"nMarathon V. Thirty base metal specimens were prepared from rexillium III alloy and divided into three groups. Then each"ngroup was bonded to enamel of human extracted molar teeth with these systems. All of specimens were stored in water at"n37ac for 48 hours. A shear force was applied to each specimen by the instron universal testing machine. A statistical"nevaluation of the data using one-way analysis of variance showed that there was highly significant difference (P<0.01"nbetween the bond strengths of these three groups."nThe base metal specimens bonded with panavia Ex luting agent, exhibited the highest mean bond strength. Shear bond"nstrength of the specimens bonded to enamel with Mirage F1C showed lower bond strenght than panavia EX. However, the"nlowest bond strength was obtained by the specimens bonded with Marathon V.

  6. Understanding Bonds - Denmark

    DEFF Research Database (Denmark)

    Rimmer, Nina Røhr

    2016-01-01

    Undervisningsmateriale. A bond is a debt security, similar to an ”I Owe You document” (IOU). When you purchase a bond, you are lending money to a government, municipality, corporation, federal agency or other entity known as the issuer. In return for the loan, the issuer promises to pay you...... a specified rate of interest during the life of the bond and to repay the face value of the bond (the principal) when it “matures,” or comes due. Among the types of bonds you can choose from are: Government securities, municipal bonds, corporate bonds, mortgage and asset-backed securities, federal agency...... securities and foreign government bonds....

  7. An Agent-Based Model for the Role of Short-Term Memory Enhancement in the Emergence of Grammatical Agreement.

    Science.gov (United States)

    Vera, Javier

    2018-01-01

    What is the influence of short-term memory enhancement on the emergence of grammatical agreement systems in multi-agent language games? Agreement systems suppose that at least two words share some features with each other, such as gender, number, or case. Previous work, within the multi-agent language-game framework, has recently proposed models stressing the hypothesis that the emergence of a grammatical agreement system arises from the minimization of semantic ambiguity. On the other hand, neurobiological evidence argues for the hypothesis that language evolution has mainly related to an increasing of short-term memory capacity, which has allowed the online manipulation of words and meanings participating particularly in grammatical agreement systems. Here, the main aim is to propose a multi-agent language game for the emergence of a grammatical agreement system, under measurable long-range relations depending on the short-term memory capacity. Computer simulations, based on a parameter that measures the amount of short-term memory capacity, suggest that agreement marker systems arise in a population of agents equipped at least with a critical short-term memory capacity.

  8. Criminal investigation in the light of Law 9,034 / 95: the role of undercover agents and their criminal consequences

    Directory of Open Access Journals (Sweden)

    Jayme José de Souza FIlho

    2012-04-01

    Full Text Available Law 9034 of May 3, 1995 provides for the use of means operacionaispara prevention and prosecution of actions taken by organizations criminosas.Sofreu amendment by Law 10,217 of April 11, 2001, which entered the Brazilian legal noordenamento agents infiltration technique comoinstrumento to combat such organizations. It provides that police officers or deinteligência in any criminal prosecution phase, since autorizadosjudicialmente, can enter into criminal groups acting dissimuladamentecomo part thereof, to obtain information and evidence to reach oseu dismantling. the owners acting as agenteinfiltrado is unacceptable. It is silent on legislation about the limits and succinct with aosrequisitos relationship that should be imposed for the exercise of this method investigativo.Silenciou is still about the criminal liability of the undercover agent noexercício of its activities, thus any responsibility should serresolvidas in the field of Theory of Crime, contained in the general section of the Code Penal.Difere the undercover agent provocateur, where the first ageconstantemente passively collecting data, while the second agede actively, prompting the target (suspect to commit crimes. The evidence obtained by the undercover agent and testimony are legitimate to instruct inquiry policiale competent prosecution.

  9. The Role of Compounds Derived from Natural Supplement as Anticancer Agents in Renal Cell Carcinoma: A Review

    Science.gov (United States)

    Haque, Inamul; Subramanian, Arvind; Huang, Chao H.; Godwin, Andrew K.; Van Veldhuizen, Peter J.; Banerjee, Snigdha; Banerjee, Sushanta K.

    2017-01-01

    Renal Cell Carcinoma (RCC) is the most prominent kidney cancer derived from renal tubules and accounts for roughly 85% of all malignant kidney cancer. Every year, over 60,000 new cases are registered, and about 14,000 people die from RCC. The incidence of this has been increasing significantly in the U.S. and other countries. An increased understanding of molecular biology and the genomics of RCC has uncovered several signaling pathways involved in the progression of this cancer. Significant advances in the treatment of RCC have been reported from agents approved by the Food and Drug Administration (FDA) that target these pathways. These agents have become drugs of choice because they demonstrate clinical benefit and increased survival in patients with metastatic disease. However, the patients eventually relapse and develop resistance to these drugs. To improve outcomes and seek approaches for producing long-term durable remission, the search for more effective therapies and preventative strategies are warranted. Treatment of RCC using natural products is one of these strategies to reduce the incidence. However, recent studies have focused on these chemoprevention agents as anti-cancer therapies given they can inhibit tumor cell grow and lack the severe side effects common to synthetic compounds. This review elaborates on the current understanding of natural products and their mechanisms of action as anti-cancer agents. The present review will provide information for possible use of these products alone or in combination with chemotherapy for the prevention and treatment of RCC. PMID:29301217

  10. The Role of Compounds Derived from Natural Supplement as Anticancer Agents in Renal Cell Carcinoma: A Review.

    Science.gov (United States)

    Haque, Inamul; Subramanian, Arvind; Huang, Chao H; Godwin, Andrew K; Van Veldhuizen, Peter J; Banerjee, Snigdha; Banerjee, Sushanta K

    2017-12-31

    Renal Cell Carcinoma (RCC) is the most prominent kidney cancer derived from renal tubules and accounts for roughly 85% of all malignant kidney cancer. Every year, over 60,000 new cases are registered, and about 14,000 people die from RCC. The incidence of this has been increasing significantly in the U.S. and other countries. An increased understanding of molecular biology and the genomics of RCC has uncovered several signaling pathways involved in the progression of this cancer. Significant advances in the treatment of RCC have been reported from agents approved by the Food and Drug Administration (FDA) that target these pathways. These agents have become drugs of choice because they demonstrate clinical benefit and increased survival in patients with metastatic disease. However, the patients eventually relapse and develop resistance to these drugs. To improve outcomes and seek approaches for producing long-term durable remission, the search for more effective therapies and preventative strategies are warranted. Treatment of RCC using natural products is one of these strategies to reduce the incidence. However, recent studies have focused on these chemoprevention agents as anti-cancer therapies given they can inhibit tumor cell grow and lack the severe side effects common to synthetic compounds. This review elaborates on the current understanding of natural products and their mechanisms of action as anti-cancer agents. The present review will provide information for possible use of these products alone or in combination with chemotherapy for the prevention and treatment of RCC.

  11. Insights into the Diels-Alder Reaction between 3-Vinylindoles and Methyleneindolinone without and with the Assistance of Hydrogen-Bonding Catalyst Bisthiourea: Mechanism, Origin of Stereoselectivity, and Role of Catalyst.

    Science.gov (United States)

    Yan, Chao-Xian; Yang, Fan; Yang, Xing; Zhou, Da-Gang; Zhou, Pan-Pan

    2017-03-17

    The Diels-Alder reaction between 3-vinylindoles and methyleneindolinone can proceed both under catalyst-free conditions and with bisthiourea as the catalyst. The reaction with bisthiourea is much faster and results in higher stereoselectivity of the product. The reaction mechanism, origin of stereoselectivity, and role of the catalyst were elaborated based on quantum mechanical calculations and theoretical methods of reactivity indices, NCI, QTAIM, and distortion/interaction models. In the uncatalyzed reaction, the two C-C bonds that are formed undergo conversion from noncovalent to covalent bonding via a concerted asynchronous mechanism. The weak intermolecular interactions formed in the transition state play important roles. The difference between the interaction and distortion energies is responsible for the stereoselectivity. In the catalyzed reaction, bisthiourea induces both the diene and dienophile to approach it via weak intermolecular interactions, which greatly lowers the energy barrier of the reaction and leads to the product with excellent stereoselectivity. The possible pathways of this reaction were explored, which suggested that the formation of the two C-C bonds goes through either a stepwise or concerted asynchronous mechanism. These results detail the reaction mechanism and shed light on both the significant role of the bisthiourea catalyst and the origin of stereoselectivity for this type of Diels-Alder reaction and related ones.

  12. Wire bonding in microelectronics

    CERN Document Server

    Harman, George G

    2010-01-01

    Wire Bonding in Microelectronics, Third Edition, has been thoroughly revised to help you meet the challenges of today's small-scale and fine-pitch microelectronics. This authoritative guide covers every aspect of designing, manufacturing, and evaluating wire bonds engineered with cutting-edge techniques. In addition to gaining a full grasp of bonding technology, you'll learn how to create reliable bonds at exceedingly high yields, test wire bonds, solve common bonding problems, implement molecular cleaning methods, and much more. Coverage includes: Ultrasonic bonding systems and technologies, including high-frequency systems Bonding wire metallurgy and characteristics, including copper wire Wire bond testing Gold-aluminum intermetallic compounds and other interface reactions Gold and nickel-based bond pad plating materials and problems Cleaning to improve bondability and reliability Mechanical problems in wire bonding High-yield, fine-pitch, specialized-looping, soft-substrate, and extreme-temperature wire bo...

  13. Biological Agents

    Science.gov (United States)

    ... E-Tools Safety and Health Topics / Biological Agents Biological Agents This page requires that javascript be enabled ... 202) 693-2300 if additional assistance is required. Biological Agents Menu Overview In Focus: Ebola Frederick A. ...

  14. Moral actor, selfish agent.

    Science.gov (United States)

    Frimer, Jeremy A; Schaefer, Nicola K; Oakes, Harrison

    2014-05-01

    People are motivated to behave selfishly while appearing moral. This tension gives rise to 2 divergently motivated selves. The actor-the watched self-tends to be moral; the agent-the self as executor-tends to be selfish. Three studies present direct evidence of the actor's and agent's distinct motives. To recruit the self-as-actor, we asked people to rate the importance of various goals. To recruit the self-as-agent, we asked people to describe their goals verbally. In Study 1, actors claimed their goals were equally about helping the self and others (viz., moral); agents claimed their goals were primarily about helping the self (viz., selfish). This disparity was evident in both individualist and collectivist cultures, attesting to the universality of the selfish agent. Study 2 compared actors' and agents' motives to those of people role-playing highly prosocial or selfish exemplars. In content (Study 2a) and in the impressions they made on an outside observer (Study 2b), actors' motives were similar to those of the prosocial role-players, whereas agents' motives were similar to those of the selfish role-players. Study 3 accounted for the difference between the actor and agent: Participants claimed that their agent's motives were the more realistic and that their actor's motives were the more idealistic. The selfish agent/moral actor duality may account for why implicit and explicit measures of the same construct diverge, and why feeling watched brings out the better angels of human nature.

  15. The role of the oximes HI-6 and HS-6 inside human acetylcholinesterase inhibited with nerve agents: a computational study.

    Science.gov (United States)

    Cuya, Teobaldo; Gonçalves, Arlan da Silva; da Silva, Jorge Alberto Valle; Ramalho, Teodorico C; Kuca, Kamil; C C França, Tanos

    2017-10-27

    The oximes 4-carbamoyl-1-[({2-[(E)-(hydroxyimino) methyl] pyridinium-1-yl} methoxy) methyl] pyridinium (known as HI-6) and 3-carbamoyl-1-[({2-[(E)-(hydroxyimino) methyl] pyridinium-1-yl} methoxy) methyl] pyridinium (known as HS-6) are isomers differing from each other only by the position of the carbamoyl group on the pyridine ring. However, this slight difference was verified to be responsible for big differences in the percentual of reactivation of acetylcholinesterase (AChE) inhibited by the nerve agents tabun, sarin, cyclosarin, and VX. In order to try to find out the reason for this, a computational study involving molecular docking, molecular dynamics, and binding energies calculations, was performed on the binding modes of HI-6 and HS-6 on human AChE (HssAChE) inhibited by those nerve agents.

  16. What is the role of biosimilar G-CSF agents in hematopoietic stem cell mobilization at present?

    Science.gov (United States)

    Korkmaz, Serdal; Altuntas, Fevzi

    2017-12-01

    Mobilization of hematopoietic stem cells, which has largely replaced bone marrow harvesting as a source of hematopoietic stem cells, using recombinant agents such as filgrastim or lenograstim has become a standard procedure in both patients and healthy donors prior to peripheral blood stem cell collection for autologous and allogeneic stem cell transplantation. Published literature data suggest that mobilization with recombinant granulocyte-colony stimulating factor (G-CSF) is safe and mobilization outcomes are satisfactory. In recent years, besides G-CSF originators, biosimilar G-CSF agents have been approved by the regulatory agencies for the same indications. Current data showed that by using the biosimilar G-CSF, similar results regarding safety and efficacy of hematopoietic stem cell mobilization may be achieved compared to the originator G-CSF. Although the issues such as the similarity to a licenced biological medicine, differences in manufacturing processes, the potential to cause immunogenicity, extrapolation and interchangeability of these biosimilar products are still being discussed by the scientific area, however, more experience with these agents now exists in approved endications and there seems to be no reason to expect significant differences between biosimilar G-CSF and originator G-CSF regarding their efficacy and safety in both patients and healthy donors. Also, the significant cost savings of biosimilars in real life setting may enhance the use of these agents in the future. Nonetheless, the collection of long-term follow-up data is mandatory for both patients and healthy donors, and multicentre randomized clinical trials that directly compare biosimilar G-CSF with the originator G-CSF are needed in order to allow the transplant community to make informed decisions regarding the choice of G-CSF. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Role of the thickening agent concentration and surfactant additions in the system's soap-oil

    Energy Technology Data Exchange (ETDEWEB)

    Shchegolev, G.G.; Trapeznikov, A.A.; Taranenko, V.G.

    1973-03-01

    The effect of the thickening agent concentration, surfactant additions and mechanical treatment on the microstructure and structural-mechanical properties of the system's lithium stearate-oil has been studied. The rate of cooling of the soap-oil system has been shown also to be of importance. The surfactants are less effective when introduced into a finished pseudogel, than when added during crystallization.

  18. Banks, Government Bonds, and Default: What do the Data Say?

    OpenAIRE

    Gennaioli, Nicola; Martin, Alberto; Rossi, Stefano

    2014-01-01

    We analyze holdings of public bonds by over 20,000 banks in 191 countries, and the role of these bonds in 20 sovereign defaults over 1998-2012. Banks hold many public bonds (on average 9% of their assets), particularly in less financially-developed countries. During sovereign defaults, banks increase their exposure to public bonds, especially large banks and when expected bond returns are high. At the bank level, bondholdings correlate negatively with subsequent lending during sovereign defau...

  19. Role of different chelating agent in synthesis of copper doped tin oxide (Cu-SnO2) nanoparticles

    Science.gov (United States)

    Saravanakumar, B.; Anusiya, A.; Rani, B. Jansi; Ravi, G.; Yuvakkumar, R.

    2018-05-01

    An attempt was made to synthesis the copper doped tin oxide (Cu-SnO2) nanoparticles by adopting different chelating agents (NaOH, KOH and C2H2O4) by Sol-gel process. The synthesized products were characterized by XRD, Photoluminescence (PL), Infra- Red (FTIR) and SEM analysis. The XRD confirms the formation of Cu-SnO2 shows the maximum peak at 33.8° with lattice plane (101). The PL peak at 361 and 382 nm due to the recombination of electron in conduction band to valence band infers the optical properties. The IR spectra correspond to the peak at 551 and 620 cm-1 attributed to the characteristics peak for Cu-SnO2 nanoparticles. The SEM images for all three Cu-SnO2 nanoparticles formed by three chelating agent (NaOH, KOH and C2H2O4) facilitates the formation mechanism and the chelating agent Oxalic acid results in formation of nano flowers with diverse layers orientated in random direction. Further SEM studies reveal that, the Cu-SnO2 nanoparticles formed by oxalic acid could posses high surface area with large number layered structured enables the better electrochemical properties and its applications.

  20. The role of alternative and natural agents, cryotherapy, and/or laser for management of alimentary mucositis.

    Science.gov (United States)

    Migliorati, Cesar A; Oberle-Edwards, Loree; Schubert, Mark

    2006-06-01

    To review the literature and update the current guidelines of alternative/natural agents, cryotherapy, and/or laser therapy in the management of alimentary mucositis (AM). The original guidelines developed by the Multinational Association for Supportive Care in Cancer (MASCC)/International Society for Oral Oncology (ISOO) mucositis study group were the basis for this study. A medical librarian conducted an initial Medline search to identify research articles published between 2002 and 2005 in English language. A search term combination that included stomatitis, mucositis, mucous membrane, neoplasm, lasers, complimentary therapies, amino acids, antioxidants, vitamins, minerals, plant extracts, and cryotherapy was conducted. This initial search identified articles with a strong scientific methodology that included both preclinical and clinical research. Using standardized scoring forms, authors reviewed and scored individual articles. A consensus result of the review was achieved in a meeting of reviewers in June of 2005. The initial search identified a total of 167 new articles. Of these, 14 were selected and reviewed: alternative/natural therapy (one preclinical study); cryotherapy (four clinical studies); lasers (two clinical studies); and alternative/natural agents (seven clinical studies). A new guideline could be established for the use of cryotherapy in the management of AM in hematopoietic stem cell transplant (HSCT) patients receiving melphalan in the conditioning phase. The rapid progress in the understanding of AM created a need for new prevention and management protocols. Frequent literature review is now necessary to identify agents and protocols being developed in this important area of supportive care in cancer.

  1. Psychometric Validation of the Parental Bonding Instrument in a UK Population–Based Sample Role of Gender and Association With Mental Health in Mid-Late Life

    NARCIS (Netherlands)

    M.K. Xu (Kate); A. J. S. Morin (Alexandre); H. W. Marsh (Herbert); M. Richards (Martin); P. B. Jones (Peter)

    2016-01-01

    markdownabstractThe factorial structure of the Parental Bonding Instrument (PBI) has been frequently studied in diverse samples but no study has examined its psychometric properties from large, population-based samples. In particular, important questions have not been addressed such as the

  2. Role of thermal spray processing method on the microstructure, residual stress and properties of coatings:an integrated study for Ni-5wt.% Al bond coats

    Czech Academy of Sciences Publication Activity Database

    Sampath, S.; Jiang, X.; Matějíček, Jiří; Prchlík, L.; Kulkarni, A.; Vaidya, A.

    2004-01-01

    Roč. 364, 1-2 (2004), s. 216-231 ISSN 0921-5093 Grant - others:NSF(US) DMR9632570 Institutional research plan: CEZ:AV0Z2043910 Keywords : bond coats, thermal spraying, microstructure Subject RIV: JG - Metallurgy Impact factor: 1.445, year: 2004

  3. The role of hydrogen bonds in the crystals of 2-amino-4-methyl-5-nitropyridinium trifluoroacetate monohydrate and 4-hydroxybenzenesulfonate - X-ray and spectroscopic studies.

    Science.gov (United States)

    Bryndal, I; Marchewka, M; Wandas, M; Sąsiadek, W; Lorenc, J; Lis, T; Dymińska, L; Kucharska, E; Hanuza, J

    2014-04-05

    Two new organic-organic salts, 2-amino-4-methyl-5-nitropyridinium trifluoroacetate monohydrate (AMNP-TFA), and 2-amino-4-methyl-5-nitropyridinium 4-hydroxybenzenesulfonate (AMNP-HBS), were obtained and characterized by means of FT-IR, FT-Raman and single crystal X-ray crystallography. In the former crystal, the cations, anions and water molecules are linked into layers by three types of hydrogen bonds, NPH⋯O, NAH⋯O and OH⋯O. These layers are connected by weaker CH⋯O hydrogen bonds. In the latter crystal, the cations and anions form one-dimensional structure through a number of hydrogen-bonding interactions involving the OH, NH(+) and NH2 groups as donors. In this case the NPH⋯O and NAH⋯O hydrogen bonds are formed. The combination of interactions between cations and anions results in the formation of columns. Additionally, there are π-π stacking interactions between the columns. The obtained X-ray structural data are related to the vibrational spectra of the studied crystals. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Adhesive bonding of wood materials

    Science.gov (United States)

    Charles B. Vick

    1999-01-01

    Adhesive bonding of wood components has played an essential role in the development and growth of the forest products industry and has been a key factor in the efficient utilization of our timber resource. The largest use of adhesives is in the construction industry. By far, the largest amounts of adhesives are used to manufacture building materials, such as plywood,...

  5. Enthalpies of ligand substitution for [Mo(η5C5H5)(CO)2(NO)] – The role of π-bonding effects in metal–ligand bond strengths

    International Nuclear Information System (INIS)

    Majumdar, Subhojit; Captain, Burjor; Cazin, Catherine S.J.; Nolan, Steven P.; Hoff, Carl D.

    2014-01-01

    Graphical abstract: - Highlights: • Enthalpies of ligand substitution are measured for Mo(C 5 H 5 )(CO) 2 (NO). • Phosphines and N-heterocyclic carbenes are stronger ligands and displace CO. • Backbonding to π ∗ orbitals is an important part of complex stability. • FTIR studies show shifts to lower wavenumbers of ν-CO and ν-NO. • Structural studies show lengthening of the C-O and N-O bonds. - Abstract: Enthalpies of ligand substitution for [Mo(η 5 -C 5 H 5 )(CO) 2 (NO)] producing [Mo(η 5 -C 5 H 5 )Mo(CO)(L)(NO)] have been measured by solution calorimetry at 30 °C in THF for L = P(OMe) 3 2 2 Ph 3 (SIPr = 1,3-bis(2,6-bis(diisopropylphenyl)imidazolinylidene; IPr = 1,3-bis(2,6-bis(diisopropylphenyl)-imidazol-2-ylidene)). The accepting metal fragment [Mo(η 5 -C 5 H 5 )(CO)(NO)] has a vacant site containing strongly π-accepting carbonyl and nitrosyl ligands and this is shown to influence the stability of the product complex. Infrared studies of both ν CO and ν NO show that metal-to-ligand backbonding increases in the order P(OMe) 3 3 5 -C 5 H 5 )(CO)(IPr)(NO)] and [Mo(η 5 -C 5 H 5 )(CO)(SIPr)(NO)] are reported

  6. The role of natural indigo dye in alleviation of genotoxicity of sodium dithionite as a reducing agent.

    Science.gov (United States)

    Bektaş, İdris; Karaman, Şengül; Dıraz, Emel; Çelik, Mustafa

    2016-12-01

    Indigo blue is a natural dye used for thousands of years by civilizations to dye fabric blue and it is naturally obtained from Isatis tinctoria. I. tinctoria is not only used for extraction of indigo blue color but also used medicinally in Traditional Chinese Medicine because of its active compounds. Sodium dithionite (Na 2 S 2 O 4 ) is used in dye bath for indigo blue extraction, but this reducing agent and its derivatives are major pollutants of textile industry and subsequently have hazardous influences on public health. Herein, the present study was designed to obtain the high yield of natural indigo dye but with low possible toxic effect. In this context, genotoxic effects of particular combinations of natural dye solutions obtained from Isatis tinctoria subsp. tomentolla with Na 2 S 2 O 4 as reducing agent were investigated. Dye solutions were obtained using two different pH levels (pH 9 and 11) and three different concentrations of Na 2 S 2 O 4 (2.5, 5 and 10 mg/ml). In addition to the dye solutions and reducing agent, aqueous extracts of I. tinctoria were assessed for their genotoxicity on human lymphocytes. For in vitro testing of genotoxicity, chromosomal aberrations (CAs), sister chromatid exchanges (SCEs) and mitotic indexes (MI) assays were used. Accordingly, Na 2 S 2 O 4 caused significant increases in CA and SCE as well decrease in MI but the genotoxic effects of sodium dithionite were reduced with natural indigo dye. As a result, aqueous extracts of Isatis leaves removed the toxic effects of sodium dithionite and showed anti-genotoxic effect. For the optimal and desired quality but with less toxic effects of natural dye, 2.5 mg/ml (for wool yarn) and 5 mg/ml (for cotton yarn) of Na 2 S 2 O 4 doses were found to be the best doses for reduction in the dye bath at Ph 9.

  7. The role of the HCR system in the repair of lethal lesions of Bacillus subtilis phages and their transfecting DNA damaged by radiation and alkylating agents

    International Nuclear Information System (INIS)

    Vizdalova, M.; Janovska, E.; Zhestyanikov, V.D.

    1980-01-01

    The role of the HCR system in the repair of prelethal lesions induced by UV light, γ radiation and alkylating agents was studied in the Bacillus subtilis SPP1 phage, its heat sensitive mutants (N3, N73 nad ts 1 ) and corresponding infectious DNA. The survival of phages and their transfecting DNA after treatment with UV light is substantially higher in hcr + cells than in hcr cells, the differences being more striking in intact phages than in their transfecting DNA's. Repair inhibitors reduce survival in hcr + cells: caffeine lowers the survival of UV-irradiated phage SPP1 in exponentially growing hcr + cells but has no effect on its survival in competent hcr + cells; acriflavin and ethidium bromide decrease the survival of the UV-irradiated SPP1 phage in both exponentially growing and competent hcr + cells to the level of survival observed in hcr cells; moreover, ethidium bromide lowers the number of infective centres in hcr + cells of the UV-irradiated DNA of the SPP1 phage. Repair inhibitors do not lower the survival of the UV-irradiated phages or their DNA in hcr cells. The repair mechanism under study also effectively repairs lesions induced by polyfunctional alkylating agents in the transfecting DNA's of B. subtilis phages but is not functional with lesions induced by these agents in free phages and lesions caused in the phages and their DNA by ethyl methanesulphonate or γ radiation. (author)

  8. The role of wild canids and felids in spreading parasites to dogs and cats in Europe. Part I: Protozoa and tick-borne agents.

    Science.gov (United States)

    Otranto, Domenico; Cantacessi, Cinzia; Pfeffer, Martin; Dantas-Torres, Filipe; Brianti, Emanuele; Deplazes, Peter; Genchi, Claudio; Guberti, Vittorio; Capelli, Gioia

    2015-09-30

    Over the last few decades, the world has witnessed radical changes in climate, landscape, and ecosystems. These events, together with other factors such as increasing illegal wildlife trade and changing human behaviour towards wildlife, are resulting into thinning boundaries between wild canids and felids and their domestic counterparts. As a consequence, the epidemiology of diseases caused by a number of infectious agents is undergoing profound readjustements, as pathogens adapt to new hosts and environments. Therefore, there is a risk for diseases of wildlife to spread to domestic carnivores and vice versa, and for zoonotic agents to emerge or re-emerge in human populations. Hence, the identification of the hazards arising from the co-habitation of these species is critical in order to plan and develop adequate control strategies against these pathogens. In the first of this two-part article, we review the role that wild canids and felids may play in the transmission of protozoa and arthropod-borne agents to dogs and cats in Europe, and provide an account of how current and future progress in our understanding of the ecology and epidemiology of parasites, as well as of host-parasite interactions, can assist efforts aimed at controlling parasite transmission. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Surface modification of basalt with silane coupling agent on asphalt mixture moisture damage

    Energy Technology Data Exchange (ETDEWEB)

    Min, Yahong; Fang, Ying; Huang, Xiaojun; Zhu, Yinhui; Li, Wensheng [College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Yuan, Jianmin [College of Materials Engineering, Hunan University, Changsha, 410082 (China); Tan, Ligang [College of Mechanical and Vehicle Engineering, Hunan University, Changsha, 410082 (China); Wang, Shuangyin [State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Wu, Zhenjun, E-mail: wooawt@163.com [College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China)

    2015-08-15

    Graphical abstract: - Highlights: • A new silane coupling agent was synthesized based on KH570. • Basalt surface was modified using the new silane coupling agent. • Chemical bond between basalt and the new silane coupling agent was formed. • Asphalt mixture which used modified basalt show superior water stability. - Abstract: A new silane coupling agent was synthesized based on γ-(methacryloyloxy) propyltrimethoxysilane (KH570). The surface of basalt rocks was modified by KH570 and the new silane coupling agent (NSCA), and the interfacial interaction between silane coupling agent and basalt was also studied. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis showed that the silane coupling agent molecule bound strongly with basalt rocks. Scanning electronic microscopy (SEM) observation showed that a thin layer of coupling agent was formed on the surface of modified basalt. The boiling test and immersion Marshall test confirmed that the moisture sensitivity of basalt modified with the new silane coupling agent increased more significantly than that untreated and treated with KH570. The Retained Marshall Strength of basalt modified with the new coupling agent increased from 71.74% to 87.79% compared with untreated basalt. The results indicated that the new silane coupling agent played an important role in improving the interfacial performance between basalt and asphalt.

  10. Ab initio and DFT studies of the interaction between carbonyl and thiocarbonyl groups: the role of S center dot center dot center dot O chalcogen bonds

    Czech Academy of Sciences Publication Activity Database

    Zierkiewicz, W.; Fanfrlík, Jindřich; Hobza, Pavel; Michalska, D.; Zeegers-Huyskens, T.

    2016-01-01

    Roč. 135, č. 9 (2016), č. článku 217. ISSN 1432-881X R&D Projects: GA ČR(CZ) GBP208/12/G016 Institutional support: RVO:61388963 Keywords : chalcogen bonds * carbonyl and thiocarbonyl groups * CCSD(T) * DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.890, year: 2016 http://link.springer.com/article/10.1007%2Fs00214-016-1972-z

  11. Medieval orality, mothers, and bonding.

    Science.gov (United States)

    Schwartz, Scott C

    2004-01-01

    The role of women in the Middle Ages was vilification, veneration, and exclusion. Due to the high rates of maternal and infant mortality bonding shifted from the mother-child dyad to one in which the Church, Holy Family, and king acted as pseudo-parents. In art this is suggested by the virtual absence of eye contact between the Virgin and Christ-child. Frustration of early oral needs consequent to lack of adequate mother-child bonding prompted a reactive emphasis on orality in art and legend. A decrease in infant mortality and a reciprocal improvement in mother child bonding contributed to cultural shifts in how self-realization would be accomplished during the Renaissance and in the later emergence of secular humanism.

  12. The role of agency in becoming and being a teacher : identifying teachers as change agents in primary education

    NARCIS (Netherlands)

    van der Heijden, H.R.M.A.

    2013-01-01

    Teachers themselves play a key role in school development. Every school needs teachers who are ‘change agents’ at both classroom and school level. However, little is known about what characterizes these teachers. Therefore, an interview study has been conducted to obtain a broad and coherent insight

  13. Bonding with Your Baby

    Science.gov (United States)

    ... the future bonding of the child and parent. Adoptive parents may be concerned about bonding with their ... general emotional support. And it's OK to ask family members and friends for help in the days — ...

  14. Australia's Bond Home Bias

    OpenAIRE

    Anil V. Mishra; Umaru B. Conteh

    2014-01-01

    This paper constructs the float adjusted measure of home bias and explores the determinants of bond home bias by employing the International Monetary Fund's high quality dataset (2001 to 2009) on cross-border bond investment. The paper finds that Australian investors' prefer investing in countries with higher economic development and more developed bond markets. Exchange rate volatility appears to be an impediment for cross-border bond investment. Investors prefer investing in countries with ...

  15. Anti-Hyperglycemic Agents for the Treatment of Type 2 Diabetes Mellitus: Role in Cardioprotection During the Last Decade.

    Science.gov (United States)

    Kocyigit, Duygu; Gurses, Kadri Murat; Yalcin, Muhammed Ulvi; Tokgozoglu, Lale

    2017-01-01

    Type 2 diabetic patients are known to have a tendency to develop cardiovascular (CV) disease (CVD), and related unfavourable outcomes such as heart failure, myocardial infarction (MI), cerebrovascular events (e.g. stroke), and related mortality. Long- term clinical trials have revealed contradictory findings regarding the relationship between glycemic control and CV benefits due to variations in the key characteristics of the study population. During the last decade, number of pharmacological agents used for glucose- lowering in the treatment of type 2 diabetes mellitus (T2DM) has increased owing to the introduction of dipeptidyl peptidase- IV (DPP- IV) inhibitors, glucagon- like peptide- 1 (GLP- 1) receptor agonists, and sodium-glucose co-transporter 2 (SGLT- 2) inhibitors. This review aims to focus on the mechanisms of action of these drugs in the cardiovascular system and the trials evaluating their impact on CVD. Furthermore, trials in the last decade evaluating the impact of traditional glucose- lowering drugs on CVD are included. For this purpose, we searched PubMed for articles in English using the search terms "type 2 diabetes mellitus, glucose- lowering drugs, antidiabetic medications, cardiovascular, cardiovascular disease, cardiovascular system" between inception to September 2016. We also searched separately for each medication in addition to the keyword "cardiovascular disease" on PubMed. To identify further articles, we hand searched related citations in review articles and commentaries. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  16. Studies on functional roles of the histaminergic neuron system by using pharmacological agents, knockout mice and positron emission tomography

    International Nuclear Information System (INIS)

    Watanabe, Takehiko; Yanai, Kazuhiko

    2001-01-01

    Since one of us, Takehiko Watanabe (TW), elucidated the location and distribution of the histaminergic neuron system in the brain with antibody raised against L-histidine decarboxylase (a histamine-forming enzyme, HDC) as a marker in 1984 and came to Tohoku University School of Medicine in Sendai, we have been collaborating on the functions of this neuron system by using pharmacological agents, knockout mice of the histamine-related genes, and, in some cases, positron emission tomography (PET). Many of our graduate students and colleagues have been actively involved in histamine research since 1985. Our extensive studies have clarified some of the functions of histamine neurons using methods from molecular techniques to non-invasive human PET imaging. Histamine neurons are involved in many brain functions, such as spontaneous locomotion, arousal in wake-sleep cycle, appetite control, seizures, learning and memory, aggressive behavior and emotion. Particularly, the histaminergic neuron system is one of the most important neuron systems to maintain and stimulate wakefulness. Histamine also functions as a biprotection system against various noxious and unfavorable stimuli (for examples, convulsion, nociception, drug sensitization, ischemic lesions, and stress). Although activators of histamine neurons have not been clinically available until now, we would like to point out that the activation of the histaminergic neuron system is important to maintain mental health. Here, we summarize the newly-discovered functions of histamine neurons mainly on the basis of results from our research groups. (author)

  17. Generation and Role of Reactive Oxygen and Nitrogen Species Induced by Plasma, Lasers, Chemical Agents, and Other Systems in Dentistry

    Science.gov (United States)

    Jha, Nayansi; Ryu, Jae Jun

    2017-01-01

    The generation of reactive oxygen and nitrogen species (RONS) has been found to occur during inflammatory procedures, during cell ischemia, and in various crucial developmental processes such as cell differentiation and along cell signaling pathways. The most common sources of intracellular RONS are the mitochondrial electron transport system, NADH oxidase, and cytochrome P450. In this review, we analyzed the extracellular and intracellular sources of reactive species, their cell signaling pathways, the mechanisms of action, and their positive and negative effects in the dental field. In dentistry, ROS can be found—in lasers, photosensitizers, bleaching agents, cold plasma, and even resin cements, all of which contribute to the generation and prevalence of ROS. Nonthermal plasma has been used as a source of ROS for biomedical applications and has the potential for use with dental stem cells as well. There are different types of dental stem cells, but their therapeutic use remains largely untapped, with the focus currently on only periodontal ligament stem cells. More research is necessary in this area, including studies about ROS mechanisms with dental cells, along with the utilization of reactive species in redox medicine. Such studies will help to provide successful treatment modalities for various diseases. PMID:29204250

  18. Studies on functional roles of the histaminergic neuron system by using pharmacological agents, knockout mice and positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Takehiko; Yanai, Kazuhiko [Tohoku Univ., Sendai (Japan). Graduate School of Medicine

    2001-12-01

    Since one of us, Takehiko Watanabe (TW), elucidated the location and distribution of the histaminergic neuron system in the brain with antibody raised against L-histidine decarboxylase (a histamine-forming enzyme, HDC) as a marker in 1984 and came to Tohoku University School of Medicine in Sendai, we have been collaborating on the functions of this neuron system by using pharmacological agents, knockout mice of the histamine-related genes, and, in some cases, positron emission tomography (PET). Many of our graduate students and colleagues have been actively involved in histamine research since 1985. Our extensive studies have clarified some of the functions of histamine neurons using methods from molecular techniques to non-invasive human PET imaging. Histamine neurons are involved in many brain functions, such as spontaneous locomotion, arousal in wake-sleep cycle, appetite control, seizures, learning and memory, aggressive behavior and emotion. Particularly, the histaminergic neuron system is one of the most important neuron systems to maintain and stimulate wakefulness. Histamine also functions as a biprotection system against various noxious and unfavorable stimuli (for examples, convulsion, nociception, drug sensitization, ischemic lesions, and stress). Although activators of histamine neurons have not been clinically available until now, we would like to point out that the activation of the histaminergic neuron system is important to maintain mental health. Here, we summarize the newly-discovered functions of histamine neurons mainly on the basis of results from our research groups. (author)

  19. Phenylacetylene and H bond

    Indian Academy of Sciences (India)

    ... all resembling H bonds. Non-linear H bonds due to secondary interactions. C-H stretching frequency shows blue shift. Heavy atom distances are longer than the sum of van der Waals radii. Formed a task group through IUPAC to come up with a modern definition of H bond. 15 international experts including Desiraju.

  20. Chemical bond fundamental aspects of chemical bonding

    CERN Document Server

    Frenking, Gernot

    2014-01-01

    This is the perfect complement to ""Chemical Bonding - Across the Periodic Table"" by the same editors, who are two of the top scientists working on this topic, each with extensive experience and important connections within the community. The resulting book is a unique overview of the different approaches used for describing a chemical bond, including molecular-orbital based, valence-bond based, ELF, AIM and density-functional based methods. It takes into account the many developments that have taken place in the field over the past few decades due to the rapid advances in quantum chemica

  1. Organizations as Socially Constructed Agents in the Agent Oriented Paradigm

    NARCIS (Netherlands)

    G. Boella (Guido); L.W.N. van der Torre (Leon)

    2005-01-01

    htmlabstractIn this paper we propose a new role for the agent metaphor in the definition of the organizational structure of multiagent systems. The agent metaphor is extended to consider as agents also social entities like organizations, groups and normative systems, so that mental attitudes can

  2. The role of lenders' trust in determining borrowing conditions for sovereign debt: An analysis of one-period government bonds with default risk

    OpenAIRE

    Guo, Yanling

    2015-01-01

    In this paper, the author considers the sovereign debt in the form of one-period government bonds with default risk, which can be purchased by and traded among domestic and foreign investors. She shows that the weight assigned to the lenders' interest by the borrowing government at the time of debt repayment, which captures the lenders' trust in the government's propensity to repay the debt and is denoted as », also determines the default risk: a higher » means a lower default risk ceteris pa...

  3. Diagnostic agent for radioimmunological determinations

    International Nuclear Information System (INIS)

    Updike, S.J.

    1978-01-01

    The invention concerns a diagnostic agent for radioimmunological determinations. According to the invention, a binding protein (protein globulins, antibodies) of an aqueous solution specific for the substance to be determined is incorporated in gel particles of a strongly hydrophilic insoluble gel of controlled pore size. After subsequent drying of the system, a radioactively labelled form of the substance to be determined from a non-aqueous medium is included. The mixture is dried again. The diagnostic agent forred can be well stored and is very stable. There is no loss of activity of the specific bonding protein when drying according to the invented method. The described reagent can be effectively applied to the determination of many antigens and haptens: The gel is rehydrated by the sample to be investigated; as a result of this, the non-bonded tracer is set free and competes with the non-labelled substance for the bonding position. (VJ) [de

  4. Combination of Vessel-Targeting Agents and Fractionated Radiation Therapy: The Role of the SDF-1/CXCR4 Pathway

    International Nuclear Information System (INIS)

    Chen, Fang-Hsin; Fu, Sheng-Yung; Yang, Ying-Chieh; Wang, Chun-Chieh; Chiang, Chi-Shiun; Hong, Ji-Hong

    2013-01-01

    Purpose: To investigate vascular responses during fractionated radiation therapy (F-RT) and the effects of targeting pericytes or bone marrow-derived cells (BMDCs) on the efficacy of F-RT. Methods and Materials: Murine prostate TRAMP-C1 tumors were grown in control mice or mice transplanted with green fluorescent protein-tagged bone marrow (GFP-BM), and irradiated with 60 Gy in 15 fractions. Mice were also treated with gefitinib (an epidermal growth factor receptor inhibitor) or AMD3100 (a CXCR4 antagonist) to examine the effects of combination treatment. The responses of tumor vasculatures to these treatments and changes of tumor microenvironment were assessed. Results: After F-RT, the tumor microvascular density (MVD) was reduced; however, the surviving vessels were dilated, incorporated with GFP-positive cells, tightly adhered to pericytes, and well perfused with Hoechst 33342, suggesting a more mature structure formed primarily via vasculogenesis. Although the gefitinib+F-RT combination affected the vascular structure by dissociating pericytes from the vascular wall, it did not further delay tumor growth. These tumors had higher MVD and better vascular perfusion function, leading to less hypoxia and tumor necrosis. By contrast, the AMD3100+F-RT combination significantly enhanced tumor growth delay more than F-RT alone, and these tumors had lower MVD and poorer vascular perfusion function, resulting in increased hypoxia. These tumor vessels were rarely covered by pericytes and free of GFP-positive cells. Conclusions: Vasculogenesis is a major mechanism for tumor vessel survival during F-RT. Complex interactions occur between vessel-targeting agents and F-RT, and a synergistic effect may not always exist. To enhance F-RT, using CXCR4 inhibitor to block BM cell influx and the vasculogenesis process is a better strategy than targeting pericytes by epidermal growth factor receptor inhibitor

  5. Optimized detection and characterization of liver metastases. The role of current MRI contrast agents; Optimierte Detektion und Charakterisierung von Lebermetastasen. Leistungsvermoegen aktueller MRT-Kontrastmittel

    Energy Technology Data Exchange (ETDEWEB)

    Weinrich, J.M.; Well, L.; Bannas, P. [Universitaetsklinikum Hamburg-Eppendorf, Zentrum fuer Radiologie und Endoskopie, Klinik und Poliklinik fuer diagnostische und interventionelle Radiologie und Nuklearmedizin, Hamburg (Germany)

    2017-05-15

    Metastases are the most common malignant lesions of the liver. The presence of liver metastases is an important prognostic factor and is decisive for the further management, especially in patients with colorectal cancer. Detection and characterization of liver metastases as well as differentiation from benign lesions are of high importance and a daily challenge in clinical radiology. Contrast-enhanced magnetic resonance imaging (MRI) has the highest sensitivity in detecting liver metastases. The sensitivity of MRI has been further increased due to the development of liver-specific contrast agents. This article describes the role of extracellular and hepatobiliary contrast agents for the detection and characterization of liver metastases. Moreover, the current knowledge on safety, sequence optimization, transient severe dyspnea and the combination of hepatobiliary with intravascular contrast agents for liver imaging is discussed. (orig.) [German] Metastasen sind die haeufigsten malignen Leberlaesionen. Das Vorhandensein von Lebermetastasen ist entscheidend fuer die Prognose und weitere Therapieplanung von Tumorpatienten, insbesondere von Patienten mit kolorektalen Karzinomen. Die Detektion von Lebermetastasen sowie deren Unterscheidung von anderen Leberlaesionen sind daher von hoechster Bedeutung und stellen eine alltaegliche Herausforderung fuer den Radiologen dar. Die Bildgebung mit der hoechsten Sensitivitaet fuer die Detektion von Lebermetastasen stellt die dynamische kontrastmittelgestuetzte Magnetresonanztomographie (MRT) dar. Die bereits hohe Sensitivitaet der MRT wird durch den Einsatz leberspezifischer Kontrastmittel noch weiter gesteigert. Dieser Artikel beleuchtet die Rolle der aktuellen unspezifischen und leberspezifischen MRT-Kontrastmittel fuer die Detektion und Charakterisierung von Lebermetastasen. Weiterhin werden Erkenntnisse zur Sicherheit, Sequenzoptimierung, zu transienten Atemartefakten und zur Kombination von MRT-Kontrastmitteln fuer die

  6. Multi-functional roles of a soldier-specific volatile as a worker arrestant, primer pheromone and an antimicrobial agent in a termite.

    Science.gov (United States)

    Mitaka, Yuki; Mori, Naoki; Matsuura, Kenji

    2017-07-26

    Division of labour in eusocial insects is characterized by efficient communication systems based on pheromones. Among such insects, termites have evolved specialized sterile defenders, called soldiers. Because they are incapable of feeding themselves, it has been suggested that soldiers are sustained by workers and emit the pheromone arresting workers. However, such a soldier pheromone has not been identified in any termite species, and the details of the soldier-worker interaction remain to be explored. Here, we identified a soldier-specific volatile sesquiterpene as a worker arrestant, which also acts as a primer pheromone regulating soldier differentiation and fungistatic agent in a termite Reticulitermes speratus Chemical analyses revealed that (-)- β -elemene is the major component of soldier extract, and its authentic standard exhibited arrestant activity to workers and inhibited the differentiation from workers to soldiers. This compound also showed fungistatic activity against entomopathogenic fungi. These suggest that (-)- β -elemene secreted by soldiers acts not only as a worker arrestant but also as one component of inhibitory primer pheromone and an anti-pathogenic agent. Our study provides novel evidence supporting the multi-functionality of termite soldier pheromone and provides new insights into the role of soldiers and the evolutionary mechanisms of pheromone compounds. © 2017 The Author(s).

  7. An agent-based modelling framework to explore the role of social media and stubborn people on evacuation rates during flooding events

    Science.gov (United States)

    Du, E.; Cai, X.; Minsker, B. S.; Sun, Z.

    2017-12-01

    Flood warnings from various information sources are important for individuals to make evacuation decisions during a flood event. In this study, we develop a general opinion dynamics model to simulate how individuals update their flood hazard awareness when exposed to multiple information sources, including global broadcast, social media, and observations of neighbors' actions. The opinion dynamics model is coupled with a traffic model to simulate the evacuation processes of a residential community with a given transportation network. Through various scenarios, we investigate how social media affect the opinion dynamics and evacuation processes. We find that stronger social media can make evacuation processes more sensitive to the change of global broadcast and neighbor observations, and thus, impose larger uncertainty on evacuation rates (i.e., a large range of evacuation rates corresponding to sources of information). For instance, evacuation rates are lower when social media become more influential and individuals have less trust in global broadcast. Stubborn individuals can significantly affect the opinion dynamics and reduce evacuation rates. In addition, evacuation rates respond to the percentage of stubborn agents in a non-linear manner, i.e., above a threshold, the impact of stubborn agents will be intensified by stronger social media. These results highlight the role of social media in flood evacuation processes and the need to monitor social media so that misinformation can be corrected in a timely manner. The joint impacts of social media, quality of flood warnings and transportation capacity on evacuation rates are also discussed.

  8. INTEREST RATES AND CURRENCIES EFFECTS ON ISLAMIC AND CONVENTIONAL BONDS

    Directory of Open Access Journals (Sweden)

    Ghazali Syamni

    2011-09-01

    Full Text Available Bond markets have not been well developed in emerging countries. Realizing its important role, especially after the 1997 crises and the islamic economics development, emerging countries have started to develop such markets. This research examines the effect of interest rates and currencies on Islamic and conventional bonds in Bursa Malaysia. The analysis on Islamic bonds shows that interest rates and currencies do not influence Islamic bonds, which supports the prohibition of interest in Islam. The analysis on conventional bonds finds evidence that both interest rates and currencies affect conventional bond. It also finds evidence of a negative association between interest rates and a conventional bond. Keywords: Interest rate, currency, conventional bond, Islamic bond JEL classification numbers: G11, G12, G15

  9. Dual Role of ROS as Signal and Stress Agents: Iron Tips the Balance in favor of Toxic Effects

    Directory of Open Access Journals (Sweden)

    Elena Gammella

    2016-01-01

    Full Text Available Iron is essential for life, while also being potentially harmful. Therefore, its level is strictly monitored and complex pathways have evolved to keep iron safely bound to transport or storage proteins, thereby maintaining homeostasis at the cellular and systemic levels. These sequestration mechanisms ensure that mildly reactive oxygen species like anion superoxide and hydrogen peroxide, which are continuously generated in cells living under aerobic conditions, keep their physiologic role in cell signaling while escaping iron-catalyzed transformation in the highly toxic hydroxyl radical. In this review, we describe the multifaceted systems regulating cellular and body iron homeostasis and discuss how altered iron balance may lead to oxidative damage in some pathophysiological settings.

  10. The effect of air thinning on dentin adhesive bond strength.

    Science.gov (United States)

    Hilton, T J; Schwartz, R S

    1995-01-01

    The purpose of this study was to determine if air thinning three dentin adhesives would affect bond strength to dentin. Ninety human molars were mounted in acrylic and the occlusal surfaces ground to expose a flat dentin surface. Thirty teeth were randomly assigned to one of the following dentin bonding agent/composite combinations: A) Universal Bond 3/TPH (Caulk), B) All-Bond 2/Bis-Fil-P (Bisco), and C) Scotchbond Multi-Purpose/Z-100 (3m). The primers were applied following the manufacturers' instructions. The adhesives were applied by two methods. A thin layer of adhesive was applied with a brush to 15 specimens in each group and light cured. Adhesive was brushed on to the remaining 15 teeth in the group, air thinned for 3 seconds, and then polymerized. The appropriate composite was applied in 2 mm increments and light cured utilizing a 5 mm-in-diameter split Teflon mold. Following 3 months of water storage, all groups were shear tested to failure on an Instron Universal Testing Machine. Bond strength was significantly higher in all groups when the dentin bonding agent was painted on without being air thinned. Scotchbond Multi-Purpose had significantly higher bond strength than All-Bond 2, which had significantly higher bond strength than Universal Bond 3.

  11. Role of hydrogen-bonding and photoinduced electron transfer (PET) on the interaction of resorcinol based acridinedione dyes with Bovine Serum Albumin (BSA) in water

    International Nuclear Information System (INIS)

    Kumaran, Rajendran; Vanjinathan, Mahalingam; Ramamurthy, Perumal

    2015-01-01

    Resorcinol based acridinedione (ADDR) dyes are a class of laser dyes and have structural similarity with purine derivatives, nicotinamide adenine dinucleotide (NADH) analogs. These dyes are classified into photoinduced electron transfer (PET) and non-photoinduced electron transfer dyes, and the photophysical properties of family of these dyes exhibiting PET behavior are entirely different from that of non-PET dyes. The PET process in ADDR dyes is governed by the solvent polarity such that an ADDR dye exhibits PET process through space in an aprotic solvent like acetonitrile and does not exhibit the same in protic solvents like water and methanol. A comparison on the fluorescence emission, lifetime and nature of interaction of various ADDR dyes with a large globular protein like Bovine Serum Albumin (BSA) was carried out in aqueous solution. The interaction of PET based ADDR dyes with BSA in water is found to be largely hydrophobic, but hydrogen-bonding interaction of BSA with dye molecule influences the fluorescence emission of the dye and shifts the emission towards red region. Fluorescence spectral studies reveal that the excited state properties of PET based ADDR dyes are largely influenced by the addition of BSA. The microenvironment around the dye results in significant change in the fluorescence lifetime and emission. Fluorescence enhancement with a red shift in the emission results after the addition of BSA to ADDR dyes containing free amino hydrogen in the 10th position of basic acridinedione dye. The amino hydrogen (N–H) in the 10th position of ADDR dye is replaced by methyl group (N–CH 3 ), a significant decrease in the fluorescence intensity with no apparent shift in the emission maximum was observed after the addition of BSA. The nature of interaction between ADDR dyes with BSA is hydrogen-bonding and the dye remains unbound even at the highest concentration of BSA. Circular Dichroism (CD) studies show that the addition of dye to BSA results in a

  12. Effects of etching time on enamel bond strengths.

    Science.gov (United States)

    Triolo, P T; Swift, E J; Mudgil, A; Levine, A

    1993-12-01

    This study evaluated the effects of etching time on bond strengths of composite to enamel. Proximal surfaces of extracted molars were etched with either a conventional etchant (35% phosphoric acid) or one of two dentin/enamel conditioners, 10% maleic acid (Scotchbond Multi-Purpose Etchant), or a solution of oxalic acid, aluminum nitrate, and glycine (Gluma 1 & 2 Conditioner). Each agent was applied for 15, 30, or 60 seconds. Specimens etched with 35% phosphoric acid had the highest mean bond strengths at each etching time. At the manufacturer's recommended application times, the other two agents gave significantly lower shear bond strengths than phosphoric acid.

  13. The correlation of cathodic peak potentials of vitamin K(3) derivatives and their calculated electron affinities. The role of hydrogen bonding and conformational changes.

    Science.gov (United States)

    Nasiri, Hamid Reza; Panisch, Robin; Madej, M Gregor; Bats, Jan W; Lancaster, C Roy D; Schwalbe, Harald

    2009-06-01

    2-methyl-1,4-naphtoquinone 1 (vitamin K(3), menadione) derivatives with different substituents at the 3-position were synthesized to tune their electrochemical properties. The thermodynamic midpoint potential (E(1/2)) of the naphthoquinone derivatives yielding a semi radical naphthoquinone anion were measured by cyclic voltammetry in the aprotic solvent dimethoxyethane (DME). Using quantum chemical methods, a clear correlation was found between the thermodynamic midpoint potentials and the calculated electron affinities (E(A)). Comparison of calculated and experimental values allowed delineation of additional factors such as the conformational dependence of quinone substituents and hydrogen bonding which can influence the electron affinities (E(A)) of the quinone. This information can be used as a model to gain insight into enzyme-cofactor interactions, particularly for enzyme quinone binding modes and the electrochemical adjustment of the quinone motif.

  14. Role for the disulfide-bonded region of human immunodeficiency virus type 1 gp41 in receptor-triggered activation of membrane fusion function

    International Nuclear Information System (INIS)

    Bellamy-McIntyre, Anna K.; Baer, Severine; Ludlow, Louise; Drummer, Heidi E.; Poumbourios, Pantelis

    2010-01-01

    The conserved disulfide-bonded region (DSR) of the human immunodeficiency virus type 1 (HIV-1) fusion glycoprotein, gp41, mediates association with the receptor-binding glycoprotein, gp120. Interactions between gp120, CD4 and chemokine receptors activate the fusion activity of gp41. The introduction of W596L and W610F mutations to the DSR of HIV-1 QH1549.13 blocked viral entry and hemifusion without affecting gp120-gp41 association. The fusion defect correlated with inhibition of CD4-triggered gp41 pre-hairpin formation, consistent with the DSR mutations having decoupled receptor-induced conformational changes in gp120 from gp41 activation. Our data implicate the DSR in sensing conformational changes in the gp120-gp41 complex that lead to fusion activation.

  15. Monitoring volatile anaesthetic agents

    International Nuclear Information System (INIS)

    Russell, W.J.

    2000-01-01

    Full text: The methods that have been used for monitoring volatile anaesthetic agents depend on some physical property such as Density, Refractometry, Mass, Solubility, Raman scattering, or Infra-red absorption. Today, refractometry and infra-red techniques are the most common. Refractometry is used for the calibration of vaporizers. All anaesthetic agents increase the refractive index of the carrier gas. Provided the mixture is known then the refractive change measures the concentration of the volatile anaesthetic agent. Raman Scattering is when energy hits a molecule a very small fraction of the energy is absorbed and re-emitted at one or more lower frequencies. The shift in frequency is a function of the chemical bonds and is a fingerprint of the substance irradiated. Electromagnetic (Infra-red) has been the commonest method of detection of volatile agents. Most systems use a subtractive system, i.e. the agent in the sampling cell absorbed some of the infrared energy and the photo-detector therefore received less energy. A different approach is where the absorbed energy is converted into a pressure change and detected as sound (Acoustic monitor). This gives a more stable zero reference. More recently, the detector systems have used multiple narrow-band wavelengths in the infrared bands and by shape matching or matrix computing specific agent identification is achieved and the concentration calculated. In the early Datex AS3 monitors, a spectral sweep across the 3 micron infrared band was used to create spectral fingerprints. The recently released AS3 monitors use a different system with five very narrow band filters in the 8-10 micron region. The transmission through each of these filters is a value in a matrix which is solved by a micro computer to identify the agent and its concentration. These monitors can assist in improving the safety and efficiency of our anaesthetics but do not ensure that the patient is completely anaesthetized. Copyright (2000

  16. Monitoring volatile anaesthetic agents

    Energy Technology Data Exchange (ETDEWEB)

    Russell, W J [Royal Adelaide Hospital, SA (Australia). Department of Anaesthesia and Intensive Care

    2000-12-01

    Full text: The methods that have been used for monitoring volatile anaesthetic agents depend on some physical property such as Density, Refractometry, Mass, Solubility, Raman scattering, or Infra-red absorption. Today, refractometry and infra-red techniques are the most common. Refractometry is used for the calibration of vaporizers. All anaesthetic agents increase the refractive index of the carrier gas. Provided the mixture is known then the refractive change measures the concentration of the volatile anaesthetic agent. Raman Scattering is when energy hits a molecule a very small fraction of the energy is absorbed and re-emitted at one or more lower frequencies. The shift in frequency is a function of the chemical bonds and is a fingerprint of the substance irradiated. Electromagnetic (Infra-red) has been the commonest method of detection of volatile agents. Most systems use a subtractive system, i.e. the agent in the sampling cell absorbed some of the infrared energy and the photo-detector therefore received less energy. A different approach is where the absorbed energy is converted into a pressure change and detected as sound (Acoustic monitor). This gives a more stable zero reference. More recently, the detector systems have used multiple narrow-band wavelengths in the infrared bands and by shape matching or matrix computing specific agent identification is achieved and the concentration calculated. In the early Datex AS3 monitors, a spectral sweep across the 3 micron infrared band was used to create spectral fingerprints. The recently released AS3 monitors use a different system with five very narrow band filters in the 8-10 micron region. The transmission through each of these filters is a value in a matrix which is solved by a micro computer to identify the agent and its concentration. These monitors can assist in improving the safety and efficiency of our anaesthetics but do not ensure that the patient is completely anaesthetized. Copyright (2000

  17. Mating system and role of pycnidiospores in biology of Polystigma amygdalinum, the causal agent of almond red leaf blotch

    Directory of Open Access Journals (Sweden)

    Azadeh HABIBI

    2016-05-01

    Full Text Available Polystigma amygdalinum is a serious leaf pathogen of almonds. Ascospores are believed to be the only inoculum of this pathogen. Ascocarp initials develop in infected leaves in contact with, or in close proximity to, filimentous spore-bearing bodies, which are the first to appear. While the aseptate filiform spores (scolecospores, are suspected of involvement in the sexual cycle of P. amygdalinum, there is no direct evidence of this. In order to study the role of the scolecospores, infected almond leaves, collected during the period from first appearance of symptoms to perithecium development, were sectioned by freezing microtome and the developmental anatomy was examined. Since ascogonia were not evident prior to the appearance of scolecospores, it was concluded that these were part of the sexual cycle of P. amygdalinum. This is supported by observations that perithecium initials always developed beside scolecospore fruit bodies, scolecospores failed to germinate in vitro, and almond leaves inoculated with them never became infected. We conclude that the filiform spores are spermatia essential to the sexual process and not asexual spores. Moreover, P. amygdalinum is likely to be homothallic, because single lesions in leaves infected by P. amygdalinum, assumed to have arisen from single ascospore infections, produced perithecia as abundantly as occurred in coalescing lesions caused by multiple ascospore infections.

  18. [Alkylating agents].

    Science.gov (United States)

    Pourquier, Philippe

    2011-11-01

    With the approval of mechlorethamine by the FDA in 1949 for the treatment of hematologic malignancies, alkylating agents are the oldest class of anticancer agents. Even though their clinical use is far beyond the use of new targeted therapies, they still occupy a major place in specific indications and sometimes represent the unique option for the treatment of refractory diseases. Here, we are reviewing the major classes of alkylating agents and their mechanism of action, with a particular emphasis for the new generations of alkylating agents. As for most of the chemotherapeutic agents used in the clinic, these compounds are derived from natural sources. With a complex but original mechanism of action, they represent new interesting alternatives for the clinicians, especially for tumors that are resistant to conventional DNA damaging agents. We also briefly describe the different strategies that have been or are currently developed to potentiate the use of classical alkylating agents, especially the inhibition of pathways that are involved in the repair of DNA lesions induced by these agents. In this line, the development of PARP inhibitors is a striking example of the recent regain of interest towards the "old" alkylating agents.

  19. Comparison of the tensile bond strength of high-noble, noble, and base metal alloys bonded to enamel.

    Science.gov (United States)

    Sen, D; Nayir, E; Pamuk, S

    2000-11-01

    Although the bond strengths of various resin composite luting materials have been reported in the literature, the evaluation of these systems with various cast alloys of different compositions has not been completely clarified. To evaluate the tensile bond strength of sandblasted high-noble, noble, and base metal alloys bonded to etched enamel by 2 different bonding agents of different chemical composition: Panavia-Ex (BIS-GMA) and Super-Bond (4-META acrylic). Flat enamel surfaces were prepared on buccal surfaces of 60 extracted noncarious human incisors. Teeth were divided into 3 groups of 20 each. Twenty circular disks of 5 mm diameter were prepared for casting for each group. Group I was cast with a high-noble, group II with a noble, and group III with a base metal alloy. The surfaces of the disks were sandblasted with 250 microm Al(2)O(3). Ten disks of each group were bonded to exposed enamel surfaces with Super-Bond and 10 disks with Panavia-Ex as recommended by the manufacturer. The tensile bond strength was measured with an Instron universal testing machine with a crosshead speed of 0.5 mm/min until failure occurred. Two-way ANOVA was used to evaluate the results. The differences in bond strengths of Super-Bond and Panavia-Ex with different alloys were not significant. The highest bond strengths were obtained in base metal alloys, followed by noble and high-noble alloys. These results were significant. Panavia-Ex and Super-Bond exhibited comparable tensile bond strengths. For both luting agents, the highest bond strengths were achieved with base metal alloys and the lowest with high-noble alloys.

  20. Composite bonding to stainless steel crowns using a new universal bonding and single-bottle systems.

    Science.gov (United States)

    Hattan, Mohammad Ali; Pani, Sharat Chandra; Alomari, Mohammad

    2013-01-01

    Aim. The aim of this study is to evaluate the shear bond strength of nanocomposite to stainless steel crowns using a new universal bonding system. Material and Methods. Eighty (80) stainless steel crowns (SSCs) were divided into four groups (20 each). Packable nanocomposite was bonded to the lingual surface of the crowns in the following methods: Group A without adhesive (control group), Group B using a new universal adhesive system (Scotchbond Universal Adhesive, 3M ESPE, Seefeld, Germany), and Group C and Group D using two different brands of single-bottle adhesive systems. Shear bond strengths were calculated and the types of failure also were recorded. Results. The shear strength of Group B was significantly greater than that of other groups. No significant differences were found between the shear bond strengths of Groups C and D. The control group had significantly lower shear bond strength (P universal bonding agent (Scotchbond Universal Adhesive, 3M ESPE, Seefeld, Germany) show significantly greater shear bond strengths and fewer adhesive failures when compared to traditional single-bottle systems.

  1. Comparative study to evaluate shear bond strength of RMGIC to composite resin using different adhesive systems

    Directory of Open Access Journals (Sweden)

    Manoj G Chandak

    2012-01-01

    Full Text Available Aim: The aim of the study is to compare and evaluate the role of new dental adhesives to bond composite to the resinmodified glass inomer cement (RMGIC. Materials and Methods: Thirty specimens were prepared on acrylic blocks, with wells prepared in it by drilling holes, to retain the RMGIC. The specimens were randomly divided into three groups of ten specimens each. In Group a thin layer of selfetch adhesive (3M ESPE was applied between the RMGIC and the composite resin FILTEK P60 (3M SPE. In Group II, total etch adhesive (Adeper Scotch bond 2, 3M ESPE was applied, and in Group III, there was no application of any adhesive between RMGIC and the composite resin. After curing all the specimens, the shear bond strength was measured using an Instron universal testing machine. Results: The results were drawn and tabulated using ANOVA-fishers and Dunnet D statistical tests.The maximum shear bond strength values were recorded in Group I specimens with self-etch adhesive showing a mean value of 2.74 when compared to the Group II adhesive (Total etch showing a mean shear strength of value 1.89, where no adhesive was used, showed a minimum mean shear bond strength of 1.42. There was a great and significant difference between Group I and Group II (P value 0.05 whereas, both Group I and Group II showed a vast and significant difference from Group III (P value = 0-001. Conclusion: Hence, this present study concludes that application of self-etch adhesive (3M ESPE, U.S.A in between RMGIC and composite resin increases the shear bond strength between RMGIC and the resin composites, as compared to the total-etch type adhesive (Adeper Scotch bond 2,3M ESPE, U.S.A as well as without application of the adhesive agent.

  2. Synthesis, crystal structure and DFT studies of a Zinc(II) complex of 1,3-diaminopropane (Dap), [Zn(Dap)(NCS)2][Zn(Dap)(NCS)2]n. The additional stabilizing role of S⋯π chalcogen bond

    Science.gov (United States)

    Alotaibi, Mshari A.; Alharthi, Abdulrahman I.; Zierkiewicz, Wiktor; Akhtar, Muhammad; Tahir, Muhammad Nawaz; Mazhar, Muhammad; Isab, Anvarhusein A.; Ahmad, Saeed

    2017-04-01

    A zinc(II) complex of 1,3-diaminopropane (Dap), [Zn(Dap)(NCS)2][Zn(Dap)(NCS)2]n (1) has been prepared and characterized by elemental analysis, IR, 1H &13C NMR spectroscopy, and its crystal structure was determined by X-ray crystallography. The crystal structure of 1 consists of two types of molecules, a discrete monomer and a polymeric one. In the monomeric unit, the zinc atom is bound to one terminal Dap molecule and to two N-bound thiocyanate ions, while in the polymeric unit, Dap acts as a bridging ligand forming a linear chain. The Zn(II) ions in both assume a slightly distorted tetrahedral geometry. The structures of two systems: the [Zn(Dap)(NCS)2][Zn(Dap)(NCS)2]3 complex as a model of 1 and [Zn(Dap)(NCS)2]4 as a simple polymeric structure were optimized with the B3LYP-D3 method. The DFT results support that the experimentally determined structure (1) is more stable in comparison to a simple polymeric structure, [Zn(Dap)(NCS)2]n (2). The interaction energies (ΔE) for NCS anions obtained by B3LYP-D3 method are about -145 kcal mol-1, while the calculated ΔE values for neutral organic ligands are about twice smaller. The X-ray structure of 1 shows that the complex is stabilized mainly by hydrogen bonds. We also found that weak chalcogen bonds play an additional role in stabilization of compound 1. Some of the intermolecular S⋯N distances are smaller than the sum of the van der Waals radii of the corresponding atoms. To the best of our knowledge, this is the first study that shows the structure where the trivalent sulfur is involved in formation of a S⋯π chalcogen bond. The NBO and NCI analyses confirm the existence of this kind of interactions.

  3. BONDING ALUMINUM METALS

    Science.gov (United States)

    Noland, R.A.; Walker, D.E.

    1961-06-13

    A process is given for bonding aluminum to aluminum. Silicon powder is applied to at least one of the two surfaces of the two elements to be bonded, the two elements are assembled and rubbed against each other at room temperature whereby any oxide film is ruptured by the silicon crystals in the interface; thereafter heat and pressure are applied whereby an aluminum-silicon alloy is formed, squeezed out from the interface together with any oxide film, and the elements are bonded.

  4. Money and bonds: an equivalence theorem

    OpenAIRE

    Narayana R. Kocherlakota

    2007-01-01

    This paper considers four models in which immortal agents face idiosyncratic shocks and trade only a single risk-free asset over time. The four models specify this single asset to be private bonds, public bonds, public money, or private money respectively. I prove that, given an equilibrium in one of these economies, it is possible to pick the exogenous elements in the other three economies so that there is an outcome-equivalent equilibrium in each of them. (The term ?exogenous variables? ref...

  5. Bond strength of self-etch adhesives after saliva contamination at different application steps.

    Science.gov (United States)

    Cobanoglu, N; Unlu, N; Ozer, F F; Blatz, M B

    2013-01-01

    This study evaluated and compared the effect of saliva contamination and possible decontamination methods on bond strengths of two self-etching adhesive systems (Clearfil SE Bond [CSE], Optibond Solo Plus SE [OSE]). Flat occlusal dentin surfaces were created on 180 extracted human molar teeth. The two bonding systems and corresponding composite resins (Clearfil AP-X, Kerr Point 4) were bonded to the dentin under six surface conditions (n=15/group): group 1 (control): primer/bonding/composite; group 2: saliva/drying/primer/bonding/composite; group 3: primer/saliva/rinsing/drying/primer/bonding/composite; group 4: primer/saliva/rinsing/drying/bonding/composite; group 5: primer/bonding (cured)/saliva/rinsing/drying/primer/bonding/composite; group 6: primer/bonding (cured)/saliva/removing contaminated layer with a bur/rinsing/drying/primer/bonding/composite. Shear bond strength was tested after specimens were stored in distilled water at 37°C for 24 hours. One-way analysis of variance and Tukey post hoc tests were used for statistical analyses. For CSE, groups 2, 3, and 4 and for OSE, groups 6, 2, and 4 showed significantly lower bond strengths than the control group (pcontamination occurred after light polymerization of the bonding agent, repeating the bonding procedure recovered the bonding capacity of both self-etch adhesives. However, saliva contamination before or after primer application negatively affected their bond strength.

  6. Hydrogen bond dynamics in bulk alcohols

    International Nuclear Information System (INIS)

    Shinokita, Keisuke; Cunha, Ana V.; Jansen, Thomas L. C.; Pshenichnikov, Maxim S.

    2015-01-01

    Hydrogen-bonded liquids play a significant role in numerous chemical and biological phenomena. In the past decade, impressive developments in multidimensional vibrational spectroscopy and combined molecular dynamics–quantum mechanical simulation have established many intriguing features of hydrogen bond dynamics in one of the fundamental solvents in nature, water. The next class of a hydrogen-bonded liquid—alcohols—has attracted much less attention. This is surprising given such important differences between water and alcohols as the imbalance between the number of hydrogen bonds, each molecule can accept (two) and donate (one) and the very presence of the hydrophobic group in alcohols. Here, we use polarization-resolved pump-probe and 2D infrared spectroscopy supported by extensive theoretical modeling to investigate hydrogen bond dynamics in methanol, ethanol, and isopropanol employing the OH stretching mode as a reporter. The sub-ps dynamics in alcohols are similar to those in water as they are determined by similar librational and hydrogen-bond stretch motions. However, lower density of hydrogen bond acceptors and donors in alcohols leads to the appearance of slow diffusion-controlled hydrogen bond exchange dynamics, which are essentially absent in water. We anticipate that the findings herein would have a potential impact on fundamental chemistry and biology as many processes in nature involve the interplay of hydrophobic and hydrophilic groups

  7. Hydrogen bond dynamics in bulk alcohols.

    Science.gov (United States)

    Shinokita, Keisuke; Cunha, Ana V; Jansen, Thomas L C; Pshenichnikov, Maxim S

    2015-06-07

    Hydrogen-bonded liquids play a significant role in numerous chemical and biological phenomena. In the past decade, impressive developments in multidimensional vibrational spectroscopy and combined molecular dynamics-quantum mechanical simulation have established many intriguing features of hydrogen bond dynamics in one of the fundamental solvents in nature, water. The next class of a hydrogen-bonded liquid--alcohols--has attracted much less attention. This is surprising given such important differences between water and alcohols as the imbalance between the number of hydrogen bonds, each molecule can accept (two) and donate (one) and the very presence of the hydrophobic group in alcohols. Here, we use polarization-resolved pump-probe and 2D infrared spectroscopy supported by extensive theoretical modeling to investigate hydrogen bond dynamics in methanol, ethanol, and isopropanol employing the OH stretching mode as a reporter. The sub-ps dynamics in alcohols are similar to those in water as they are determined by similar librational and hydrogen-bond stretch motions. However, lower density of hydrogen bond acceptors and donors in alcohols leads to the appearance of slow diffusion-controlled hydrogen bond exchange dynamics, which are essentially absent in water. We anticipate that the findings herein would have a potential impact on fundamental chemistry and biology as many processes in nature involve the interplay of hydrophobic and hydrophilic groups.

  8. Copper wire bonding

    CERN Document Server

    Chauhan, Preeti S; Zhong, ZhaoWei; Pecht, Michael G

    2014-01-01

    This critical volume provides an in-depth presentation of copper wire bonding technologies, processes and equipment, along with the economic benefits and risks.  Due to the increasing cost of materials used to make electronic components, the electronics industry has been rapidly moving from high cost gold to significantly lower cost copper as a wire bonding material.  However, copper wire bonding has several process and reliability concerns due to its material properties.  Copper Wire Bonding book lays out the challenges involved in replacing gold with copper as a wire bond material, and includes the bonding process changes—bond force, electric flame off, current and ultrasonic energy optimization, and bonding tools and equipment changes for first and second bond formation.  In addition, the bond–pad metallurgies and the use of bare and palladium-coated copper wires on aluminum are presented, and gold, nickel and palladium surface finishes are discussed.  The book also discusses best practices and re...

  9. Role of contamination on the bondline integrity of composite structures

    Energy Technology Data Exchange (ETDEWEB)

    Shang, Xu [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    Adhesively bonding composite structures have many applications in aerospace, automotive and submarine industries. The adhesive bonding joints have substantial advantage over the traditional metallic mechanical bonding joints, such as rivet and welding. However, the adhesive bonding joints require additional steps of surface preparation and cleaning to ensure consistent bond strength. In application, the adhesively bonded joints are exposed to environmental degradation and industrial solvent contaminates. Accordingly, the assurance of reliability of bonded composite structures requires detailed investigation of the role of contaminates on bondline integrity. This dissertation focuses on assessing the contaminates effect on the adhesive bondline integrity. A combined experimental and numerical framework is developed to study the contamination effect on the adhesive mechanical properties and adhesive joint strength. The bondline integrity were examined for a system of adhesive (EA9394) and the carbonfiber system (Hexply IM7/8552), after being subjected to different level of exposures to aviation hydraulic fluids and mold cleaning agents. A testing protocol based on nanoindentation for initial screening is used to predict the interfacial fracture characteristics after exposure to contamination. It is found the adhesive modulus and stiffness dropped by up to 10% for the hydraulic fluid contaminates, suggesting increase of the plastic dissipation within the bondline. However, the trend for the cleaning agent was not clear since the modulus drop while its hardness increased.

  10. Human serum albumin as protecting agent of silver nanoparticles: role of the protein conformation and amine groups in the nanoparticle stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Alarcon, Emilio I.; Bueno-Alejo, Carlos J.; Noel, Christopher W.; Stamplecoskie, Kevin G. [Centre for Catalysis Research and Innovation, University of Ottawa, Department of Chemistry (Canada); Pacioni, Natalia L. [Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, INFIQC, Departamento de Quimica Organica (Argentina); Poblete, Horacio [Center for Bioinformatics and Molecular Simulations, Universidad de Talca (Chile); Scaiano, J. C., E-mail: tito@photo.chem.uottawa.ca [Centre for Catalysis Research and Innovation, University of Ottawa, Department of Chemistry (Canada)

    2013-01-15

    Thermally denatured human serum albumin interacts with {approx}3.0 nm spherical AgNP enhancing the fluorescence of Trp-214 at large protein/nanoparticle ratios. However, using native HSA, no changes in the emission were observed. The observation is likely due to differences between native and denatured protein packing resulting from protein corona formation. We have also found that NH{sub 2} blocking of the protein strongly affects the ability of the protein to protect AgNP from different salts/ions such as NaCl, PBS, Hank's buffer, Tris-HCl, MES, and DMEM. Additionally, AgNP can be readily prepared in aqueous solutions by a photochemical approach employing HSA as an in situ protecting agent. The role of the protein in this case is beyond that of protecting agent; thus, Ag{sup +} ions and I-2959 complexation within the protein structure also affects the efficiency of AgNP formation. Blocking NH{sub 2} in HSA modified the AgNP growth profile, surface plasmon band shape, and long-term stability suggesting that amine groups are directly involved in the formation and post-stabilization of AgNP. In particular, AgNP size and shape are extensively influenced by NH{sub 2} blocking, leading primarily to cubes and plates with sizes around 5-15 nm; in contrast, spherical monodisperse 4.0 nm AgNP are observed for native HSA. The nanoparticles prepared by this protocol are non-toxic in primary cells and have remarkable antibacterial properties. Finally, surface plasmon excitation of native HSA-AgNP promoted loss of protein conformation in just 5 min, suggesting that plasmon heating causes protein denaturation using continuous light sources such as commercial LED.

  11. Effect of beta2-adrenoceptor agonists and other cAMP-elevating agents on inflammatory gene expression in human ASM cells: a role for protein kinase A.

    Science.gov (United States)

    Kaur, Manminder; Holden, Neil S; Wilson, Sylvia M; Sukkar, Maria B; Chung, Kian Fan; Barnes, Peter J; Newton, Robert; Giembycz, Mark A

    2008-09-01

    In diseases such as asthma, airway smooth muscle (ASM) cells play a synthetic role by secreting inflammatory mediators such as granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-6, or IL-8 and by expressing surface adhesion molecules, including ICAM-1. In the present study, PGE(2), forskolin, and short-acting (salbutamol) and long-acting (salmeterol and formoterol) beta(2)-adrenoceptor agonists reduced the expression of ICAM-1 and the release of GM-CSF evoked by IL-1beta in ASM cells. IL-1beta-induced IL-8 release was also repressed by PGE(2) and forskolin, whereas the beta(2)-adrenoceptor agonists were ineffective. In each case, repression of these inflammatory indexes was prevented by adenoviral overexpression of PKIalpha, a highly selective PKA inhibitor. These data indicate a PKA-dependent mechanism of repression and suggest that agents that elevate intracellular cAMP, and thereby activate PKA, may have a widespread anti-inflammatory effect in ASM cells. Since ICAM-1 and GM-CSF are highly NF-kappaB-dependent genes, we used an adenoviral-delivered NF-kappaB-dependent luciferase reporter to examine the effects of forskolin and the beta(2)-adrenoceptor agonists on NF-kappaB activation. There was no effect on luciferase activity measured in the presence of forskolin or beta(2)-adrenoceptor agonists. This finding is consistent with the observation that IL-1beta-induced expression of IL-6, a known NF-kappaB-dependent gene in ASM, was also unaffected by beta(2)-adrenoceptor agonists, forskolin, PGE(2), 8-bromo-cAMP, or rolipram. Collectively, these results indicate that repression of IL-1beta-induced ICAM-1 expression and GM-CSF release by cAMP-elevating agents, including beta(2)-adrenoceptor agonists, may not occur through a generic effect on NF-kappaB.

  12. Cone and seed traits of two Juniperus species influence roles of frugivores and scatter-hoarding rodents as seed dispersal agents

    Science.gov (United States)

    Dimitri, Lindsay A.; Longland, William S.; Vander Wall, Stephen B.

    2017-11-01

    Seed dispersal in Juniperus is generally attributed to frugivores that consume the berry-like female cones. Some juniper cones are fleshy and resinous such as those of western juniper (Juniperus occidentalis), while others are dry and leathery such as those of Utah juniper (J. osteosperma). Rodents have been recorded harvesting Juniperus seeds and cones but are mostly considered seed predators. Our study sought to determine if rodents play a role in dispersal of western and Utah juniper seeds. We documented rodent harvest of cones and seeds of the locally-occurring juniper species and the alternate (non-local) juniper species in removal experiments at a western juniper site in northeastern California and a Utah juniper site in western Nevada. Characteristics of western and Utah juniper cones appeared to influence removal, as cones from the local juniper species were preferred at both sites. Conversely, removal of local and non-local seeds was similar. Piñon mice (Peromyscus truei) were responsible for most removal of cones and seeds at both sites. We used radioactively labeled seeds to follow seed fate and found many of these seeds in scattered caches (western juniper: 415 seeds in 82 caches, 63.0% of seeds found; Utah juniper: 458 seeds in 127 caches, 39.5% of seeds found) most of which were attributed to piñon mice. We found little evidence of frugivores dispersing Utah juniper seeds, thus scatter-hoarding rodents appear to be the main dispersal agents. Western juniper cones were eaten by frugivores, and scatter-hoarding is a complimentary or secondary form of seed dispersal. Our results support the notion that Utah juniper has adapted to xeric environments by conserving water through the loss of fleshy fruits that attract frugivores and instead relies on scatter-hoarding rodents as effective dispersal agents.

  13. Human serum albumin as protecting agent of silver nanoparticles: role of the protein conformation and amine groups in the nanoparticle stabilization

    International Nuclear Information System (INIS)

    Alarcon, Emilio I.; Bueno-Alejo, Carlos J.; Noel, Christopher W.; Stamplecoskie, Kevin G.; Pacioni, Natalia L.; Poblete, Horacio; Scaiano, J. C.

    2013-01-01

    Thermally denatured human serum albumin interacts with ∼3.0 nm spherical AgNP enhancing the fluorescence of Trp-214 at large protein/nanoparticle ratios. However, using native HSA, no changes in the emission were observed. The observation is likely due to differences between native and denatured protein packing resulting from protein corona formation. We have also found that NH 2 blocking of the protein strongly affects the ability of the protein to protect AgNP from different salts/ions such as NaCl, PBS, Hank’s buffer, Tris–HCl, MES, and DMEM. Additionally, AgNP can be readily prepared in aqueous solutions by a photochemical approach employing HSA as an in situ protecting agent. The role of the protein in this case is beyond that of protecting agent; thus, Ag + ions and I-2959 complexation within the protein structure also affects the efficiency of AgNP formation. Blocking NH 2 in HSA modified the AgNP growth profile, surface plasmon band shape, and long-term stability suggesting that amine groups are directly involved in the formation and post-stabilization of AgNP. In particular, AgNP size and shape are extensively influenced by NH 2 blocking, leading primarily to cubes and plates with sizes around 5–15 nm; in contrast, spherical monodisperse 4.0 nm AgNP are observed for native HSA. The nanoparticles prepared by this protocol are non-toxic in primary cells and have remarkable antibacterial properties. Finally, surface plasmon excitation of native HSA-AgNP promoted loss of protein conformation in just 5 min, suggesting that plasmon heating causes protein denaturation using continuous light sources such as commercial LED.

  14. Potential Role of Social Impact Bond and Socially Responsible Investment Sukuk as Financial Tools that Can Help Address Issues of Poverty and Socio-Economic Insecurity

    Directory of Open Access Journals (Sweden)

    Syed Marwan Mujahid bin Syed Azman

    2017-01-01

    Full Text Available The purpose of this paper is to highlight the potential of Social Impact Bond (SIB and Socially Responsible Investment (SRI sukuk as financial models that can be used to help alleviate the social problem of poverty and also potentially provide economic security for the society. From the review of literature, this paper takes case studies of SIB programmes and SRI sukuk, and relates them as programmes that can be used to address the issue of poverty and economic insecurity. The paper finds that there is a growing global interest in innovative financial tools such as SIB and SRI sukuk. Furthermore, the paper explicates that SIB and SRI sukuk models embody the spirit of social responsibility, which is one of the major essence that is currently missing in the Islamic finance industry practice. This paper is conceptual and exploratory in nature. Therefore, further empirical research can be done to provide better understanding and knowledge. Findings from this paper can be used as a reference to understand the concepts and mechanisms involved in SIB and SRI sukuk models. This paper contributes to the awareness of the emerging global interest in SIB and SRI. In addition, it highlights SIB and SRI sukuks’ potential contribution towards Islamic finance. Although SIB and SRI sukuk is gaining interest worldwide, it has not caught much attention of researchers and practitioners involved with Islamic finance. Therefore, this paper offers insight towards SIB and SRI sukuk, which is relatively unknown to academics and Islamic finance industry practitioners.

  15. Role of powder preparation route on microstructure and mechanical properties of Al-TiB2 composites fabricated by accumulative roll bonding (ARB)

    International Nuclear Information System (INIS)

    Askarpour, M.; Sadeghian, Z.; Reihanian, M.

    2016-01-01

    Accumulative roll bonding (ARB) was conducted up to seven cycles to fabricate Al-TiB 2 particulate metal matrix composites. The reinforcing particles were prepared and used in three different processing conditions: as-received TiB 2 , mixed TiB 2 -Al and in-situ synthesized TiB 2 -Al. The mixed TiB 2 -Al powder was produced by milling of TiB 2 with Al powder and in-situ synthesized TiB 2 -Al powder was prepared by mechanical alloying (MA) through inducing TiB 2 particles in the Al with various composition of 10, 20 and 30 wt% Al. Transmission electron microscope (TEM) and scanning electron microscope (SEM) were used to evaluate the microstructure of the produced composites. The composite obtained from the in-situ TiB 2 -Al powder showed the most uniform distribution of particles and exhibited the highest tensile strength of about 177 MPa in comparison with the composites reinforced with the as-received TiB 2 (156 MPa) and mixed TiB 2 -Al powder (160 MPa). After seven ARB cycles, an ultra-fine grained structure with the average size of about 300 nm was obtained in the composite reinforced with in-situ TiB 2 -Al powder. The appearance of dimples in tensile fracture surfaces revealed a ductile-type fracture in the produced composites.

  16. Molecular Dynamics Simulations for Loading-Dependent Diffusion of CO2, SO2, CH4, and Their Binary Mixtures in ZIF-10: The Role of Hydrogen Bond.

    Science.gov (United States)

    Li, Li; Yang, Deshuai; Fisher, Trevor R; Qiao, Qi; Yang, Zhen; Hu, Na; Chen, Xiangshu; Huang, Liangliang

    2017-10-24

    The loading-dependent diffusion behavior of CH 4 , CO 2 , SO 2 , and their binary mixtures in ZIF-10 has been investigated in detail by using classical molecular dynamics simulations. Our simulation results demonstrate that the self-diffusion coefficient D i of CH 4 molecules decreases sharply and monotonically with the loading while those of both CO 2 and SO 2 molecules initially display a slight increase at low uptakes and follow a slow decrease at high uptakes. Accordingly, the interaction energies between CH 4 molecules and ZIF-10 remain nearly constant regardless of the loading due to the absence of hydrogen bonds (HBs), while the interaction energies between CO 2 (or SO 2 ) and ZIF-10 decease rapidly with the loading, especially at small amounts of gas molecules. Such different loading-dependent diffusion and interaction mechanisms can be attributed to the relevant HB behavior between gas molecules and ZIF-10. At low loadings, both the number and strength of HBs between CO 2 (or SO 2 ) molecules and ZIF-10 decrease obviously as the loading increases, which is responsible for the slight increase of their diffusion coefficients. However, at high loadings, their HB strength increases with the loading. Similar loading-dependent phenomena of diffusion, interaction, and HB behavior can be observed for CH 4, CO 2 , and SO 2 binary mixtures in ZIF-10, only associated with some HB competition between CO 2 and SO 2 molecules in the case of the CO 2 /SO 2 mixture.

  17. Role of atomic bonding for compound and glass formation in Ni-Si, Pd-Si, and Ni-B systems

    Science.gov (United States)

    Tanaka, K.; Saito, T.; Suzuki, K.; Hasegawa, R.

    1985-11-01

    Valence electronic structures of crystalline compounds and glassy alloys of Ni silicides, Pd silicides, and Ni borides are studied by soft-x-ray spectroscopy over wide ranges of Si and B concentrations. The samples prepared include bulk compounds, glassy ribbons, and amorphous sputtered films. Silicon Kβ emissions of Ni and Pd silicides generally consist of a prominent peak fixed at ~=4.5 and ~=5.8 eV below the Fermi level EF, respectively, with a shoulder near EF which grows and shifts toward lower energy with increasing Si concentration. The former is identified as due to Si p-like states forming Si 3p-Ni 3d or Si 3p-Pd 4d bonding states while the latter as due to the corresponding antibonding states. Ni L3 and Pd L3 emissions of these silicides indicate that Ni 3d and Pd 4d states lie between the above two states. These local electronic configurations are consistent with partial-density-of-states (PDOS) calculations performed by Bisi and Calandra. Similar electronic configurations are suggested for Ni borides from B Kα and Ni L3 emissions. Differences of emission spectra between compounds and glasses of similar compositions are rather small, but some enhancement of the contribution of antibonding states to the PDOS near EF is suggested for certain glasses over that of the corresponding compounds. These features are discussed in connection with the compound stability and glass formability.

  18. Role of powder preparation route on microstructure and mechanical properties of Al-TiB{sub 2} composites fabricated by accumulative roll bonding (ARB)

    Energy Technology Data Exchange (ETDEWEB)

    Askarpour, M.; Sadeghian, Z., E-mail: z.sadeghian@scu.ac.ir; Reihanian, M.

    2016-11-20

    Accumulative roll bonding (ARB) was conducted up to seven cycles to fabricate Al-TiB{sub 2} particulate metal matrix composites. The reinforcing particles were prepared and used in three different processing conditions: as-received TiB{sub 2}, mixed TiB{sub 2}-Al and in-situ synthesized TiB{sub 2}-Al. The mixed TiB{sub 2}-Al powder was produced by milling of TiB{sub 2} with Al powder and in-situ synthesized TiB{sub 2}-Al powder was prepared by mechanical alloying (MA) through inducing TiB{sub 2} particles in the Al with various composition of 10, 20 and 30 wt% Al. Transmission electron microscope (TEM) and scanning electron microscope (SEM) were used to evaluate the microstructure of the produced composites. The composite obtained from the in-situ TiB{sub 2}-Al powder showed the most uniform distribution of particles and exhibited the highest tensile strength of about 177 MPa in comparison with the composites reinforced with the as-received TiB{sub 2} (156 MPa) and mixed TiB{sub 2}-Al powder (160 MPa). After seven ARB cycles, an ultra-fine grained structure with the average size of about 300 nm was obtained in the composite reinforced with in-situ TiB{sub 2}-Al powder. The appearance of dimples in tensile fracture surfaces revealed a ductile-type fracture in the produced composites.

  19. Bonding silicon nitride using glass-ceramic

    International Nuclear Information System (INIS)

    Dobedoe, R.S.

    1995-01-01

    Silicon nitride has been successfully bonded to itself using magnesium-aluminosilicate glass and glass-ceramic. For some samples, bonding was achieved using a diffusion bonder, but in other instances, following an initial degassing hold, higher temperatures were used in a nitrogen atmosphere with no applied load. For diffusion bonding, a small applied pressure at a temperature below which crystallisation occurs resulted in intimate contact. At slightly higher temperatures, the extent of the reaction at the interface and the microstructure of the glass-ceramic joint was highly sensitive to the bonding temperature. Bonding in a nitrogen atmosphere resulted in a solution-reprecipitation reaction. A thin layer of glass produced a ''dry'', glass-free joint, whilst a thicker layer resulted in a continuous glassy join across the interface. The chromium silicide impurities within the silicon nitride react with the nucleating agent in the glass ceramic, which may lead to difficulty in producing a fine glass-ceramic microstructure. Slightly lower temperatures in nitrogen resulted in a polycrystalline join but the interfacial contact was poor. It is hoped that one of the bonds produced may be developed to eventually form part of a graded joint between silicon nitride and a high temperature nickel alloy. (orig.)

  20. 29 CFR 2580.412-22 - Interests held in agents, brokers and surety companies.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 9 2010-07-01 2010-07-01 false Interests held in agents, brokers and surety companies... SECURITY ACT OF 1974 TEMPORARY BONDING RULES Qualified Agents, Brokers and Surety Companies for the Placing of Bonds § 2580.412-22 Interests held in agents, brokers and surety companies. Section 13(c...

  1. Transversely Compressed Bonded Joints

    DEFF Research Database (Denmark)

    Hansen, Christian Skodborg; Schmidt, Jacob Wittrup; Stang, Henrik

    2012-01-01

    The load capacity of bonded joints can be increased if transverse pressure is applied at the interface. The transverse pressure is assumed to introduce a Coulomb-friction contribution to the cohesive law for the interface. Response and load capacity for a bonded single-lap joint was derived using...

  2. Corporate Bonds in Denmark

    DEFF Research Database (Denmark)

    Tell, Michael

    2015-01-01

    Corporate financing is the choice between capital generated by the corporation and capital from external investors. However, since the financial crisis shook the markets in 2007–2008, financing opportunities through the classical means of financing have decreased. As a result, corporations have...... to think in alternative ways such as issuing corporate bonds. A market for corporate bonds exists in countries such as Norway, Germany, France, the United Kingdom and the United States, while Denmark is still behind in this trend. Some large Danish corporations have instead used foreign corporate bonds...... markets. However, NASDAQ OMX has introduced the First North Bond Market in December 2012 and new regulatory framework came into place in 2014, which may contribute to a Danish based corporate bond market. The purpose of this article is to present the regulatory changes in Denmark in relation to corporate...

  3. The role of oxytocin in social bonding, stress regulation and mental health: an update on the moderating effects of context and interindividual differences

    NARCIS (Netherlands)

    Olff, Miranda; Frijling, Jessie L.; Kubzansky, Laura D.; Bradley, Bekh; Ellenbogen, Mark A.; Cardoso, Christopher; Bartz, Jennifer A.; Yee, Jason R.; van Zuiden, Mirjam

    2013-01-01

    In this review we summarize the results and conclusions of five studies as presented in a symposium at the 42nd annual meeting of the International Society for Psychoneuroendocrinology, in New York in September 2012. Oxytocin administration has received increasing attention for its role in promoting

  4. Chemical Agents

    Science.gov (United States)

    ... CR) see Riot Control Agents Digitalis Distilled mustard (HD) see Sulfur mustard E Ethylene glycol F Fentanyls and other opioids H Hydrazine Hydrofluoric acid (hydrogen fluoride) Hydrogen chloride Hydrogen cyanide (AC) Hydrogen ...

  5. Tensile bond strength of metal bracket bonding to glazed ceramic surfaces with different surface conditionings.

    Science.gov (United States)

    Akhoundi, Ms Ahmad; Kamel, M Rahmati; Hashemi, Sh Mahmood; Imani, M

    2011-01-01

    The objective of this study was to compare the tensile bond strength of metal brackets bonding to glazed ceramic surfaces using three various surface treatments. Forty two glazed ceramic disks were assigned to three groups. In the first and second groups the specimens were etched with 9.5% hydrofluoric acid (HFA). Subsequently in first group, ceramic primer and adhesive were applied, but in second group a bonding agent alone was used. In third group, specimens were treated with 35% phosphoric acid followed by ceramic primer and adhesive application. Brackets were bonded with light cure composites. The specimens were stored in distilled water in the room temperature for 24 hours and thermocycled 500 times between 5°C and 55°C. The universal testing machine was used to test the tensile bond strength and the adhesive remenant index scores between three groups was evaluated. The data were subjected to one-way ANOVA, Tukey and Kruskal-Wallis tests respectively. The tensile bond strength was 3.69±0.52 MPa forfirst group, 2.69±0.91 MPa for second group and 3.60±0.41 MPa for third group. Group II specimens showed tensile strength values significantly different from other groups (Ptensile bond strength.

  6. Structural, vibrational and bonding properties of hydro-nitrogen ...

    Indian Academy of Sciences (India)

    Strength of secondary bonds is approximately one tenth ... are weaker, they play significant role in determining the stability of ... actions play major role in crystal binding, physical ... ties of HZA using vdW-TS method at ambient as well.

  7. Effects of green tea on the shear bond strength of orthodontic brackets after in-office vital bleaching.

    Science.gov (United States)

    Berger, Sandrine Bittencourt; Guiraldo, Ricardo Danil; Lopes, Murilo Baena; Oltramari-Navarro, Paula Vanessa; Fernandes, Thais Maria; Schwertner, Renata de Castro Alves; Ursi, Wagner José Silva

    2016-01-01

    The application of bleaching agents before placement of resin-bonded fixed appliances significantly, but temporarily, reduces bond strength to tooth structure. Antioxidants have been studied as a means to remove residual oxygen that compromises bonding to bleached enamel. This in vitro study evaluated whether green tea (GT) could restore the shear bond strength between bonded orthodontic brackets and bleached enamel. Six experimental groups were compared: group 1, no bleaching plus bracket bonding (positive control); group 2, bleaching with 35% hydrogen peroxide (HP) plus bracket bonding (negative control); group 3, 35% HP plus 10% sodium ascorbate (SA) plus bracket bonding; group 4, 35% HP plus 10% GT plus bracket bonding; group 5, no bleaching plus 10% SA plus bracket bonding; group 6, no bleaching plus 10% GT plus bracket bonding. Results suggested that GT, like SA, may be beneficial for bracket bonding immediately after bleaching.

  8. Russian olive (Elaeagnus angustifolia L.: From a variety of traditional medicinal applications to its novel roles as active antioxidant, anti-inflammatory, anti-mutagenic and analgesic agent

    Directory of Open Access Journals (Sweden)

    Rafie Hamidpour

    2017-01-01

    Full Text Available Elaeagnus angustifolia L., which is commonly known as oleaster or Russian olive, is a deciduous plant from Elaeagnacea family. This plant can tolerate and survive a wide variety of environmental conditions. Different parts of E. angustifolia plant, especially the fruits and flowers, have been used traditionally in treating a variety of common illnesses such as nausea, cough, asthma, fever, jaundice, and diarrhea. The use of fruit powder and extract of E. angustifolia L. have shown to be effective in alleviating pain in patients with rheumatoid arthritis and also in reducing the healing time of wounds in injured person. In addition, some recent reports have indicated the anti-oxidant, anti-inflammatory, antimicrobial, anticancer and some other properties of oleaster plant. The other important property of this plant would be its role in bio-monitoring the environment for some toxic elements and also its action as a bio-fertilizer agent in distressed lands. It seems that with more advanced studies on E. angustifolia L. and its bioactive components, this plant might be potentially effective and can be used as a natural alternative resource in pharmaceutical industries for treating chronic and serious problems, Fig. 1.

  9. A role for b-cell-depleting agents in treating psoriatic skin lesions induced by tumor necrosis factor-alpha antagonists: A case report and literature review

    Directory of Open Access Journals (Sweden)

    Ancuta Codrina Mihaela

    2014-01-01

    Full Text Available Despite recent advances in understanding the pathological pathways, clinical pattern and management opportunities for new-onset psoriasis as a paradoxical adverse event in patients receiving TNF inhibitors for their immune-mediated disorder, there is a subset of patients who are either partial responders or non-responders, whatever the therapeutic scenario. We present the case of new-onset psoriasis and severe alopecia development in a case study of long-standing rheumatoid arthritis (RA treated with adalimumab (ADA and leflunomide. Since skin lesions and alopecia are resistant to the classic protocol (topical treatment, ADA discontinuation and RA becomes highly active, rituximab (RTX was started. Dramatic improvement in joint disease, total remission of alopecia and partial remission of pustular psoriasis were described after the first RTX cycle. Although B-cell-depleting agents result in controversial effects on psoriatic skin lesions, this is the first case of ADA-induced psoriasis and alopecia that improved under RTX, suggesting a possible role in treating such a patient population.

  10. Two-component bond for coating materials coming into contact with radioactivity

    International Nuclear Information System (INIS)

    Svoboda, L.; Fajfr, K.

    1989-01-01

    The two-component bonding agent consists of an epoxy resin of the diane-bis-glycidyl ether type and an amine hardener containing benzyl alcohol and bis-2-ethylhexyl phthalate. The claimed bond features high radiation stability and very good decontaminability. Thanks to low viscosity of the bond, pigmented reactor-plastics can be prepared. The procedure is described of applying the bond onto a concrete surface. (E.S.)

  11. Mimicry of the regulatory role of urokinase in lamellipodia formation by introduction of a non-native interdomain disulfide bond in its receptor

    DEFF Research Database (Denmark)

    Gårdsvoll, Henrik; Kjærgaard, Magnus; Jacobsen, Benedikte

    2011-01-01

    The high-affinity interaction between the urokinase-type plasminogen activator (uPA) and its glycolipid-anchored receptor (uPAR) plays a regulatory role for both extravascular fibrinolysis and uPAR-mediated adhesion and migration on vitronectin-coated surfaces. We have recently proposed that the ......The high-affinity interaction between the urokinase-type plasminogen activator (uPA) and its glycolipid-anchored receptor (uPAR) plays a regulatory role for both extravascular fibrinolysis and uPAR-mediated adhesion and migration on vitronectin-coated surfaces. We have recently proposed...... that the adhesive function of uPAR is allosterically regulated via a "tightening" of its three-domain structure elicited by uPA binding. To challenge this proposition, we redesigned the uPAR structure to limit its inherent conformational flexibility by covalently tethering domains DI and DIII via a non...... adhering to vitronectin. In this respect, the engineered constraint in uPAR(H47C-N259C) thus bypasses the regulatory role of uPA binding, resulting in a constitutively active uPAR. In conclusion, our data argue for a biological relevance of the interdomain dynamics of the glycolipid-anchored u...

  12. Teaching tourism change agents

    DEFF Research Database (Denmark)

    Blichfeldt, Bodil Stilling; Kvistgaard, Hans-Peter; Hird, John

    2017-01-01

    This article discuss es know ledge, competencies and skills Master’s students should obtain during their academic studies and particularly, the differences between teaching about a topic and teaching to do. This is ex emplified by experiential learning theory and the case of a change management...... course that is part of a Tourism Master’s program, where a major challenge is not only to teach students about change and change agents, but to teach them how change feels and ho w to become change agents. The c hange management course contains an experiment inspired by experiential teaching literature...... and methods. The experiment seeks to make students not only hear/learn about change agency and management, but to make them feel cha nge, hereby enabling them to develop the skills and competencies necessary for them to take on the role as change agent s and thus enable them to play key role s in implementing...

  13. Destination bonding: Hybrid cognition using Instagram

    Directory of Open Access Journals (Sweden)

    Arup Kumar Baksi

    2015-01-01

    Full Text Available Empirical research has identified the phenomenon of destination bonding as a result of summated physical and emotional values associated with the destination. Physical values, namely natural landscape & other physical settings and emotional values, namely the enculturation processes, have a significant role to play in portraying visitors’ cognitive framework for destination preference. The physical values seemed to be the stimulator for bonding that embodies action or behavior tendencies in imagery. The emotional values were the conditions that lead to affective bonding and are reflected in attitudes for a place which were evident in text narratives. Social networking on virtual platforms offers the scope for hybrid cognitive expression using imagery and text to the visitors. Instagram has emerged as an application-window to capture these hybrid cognitions of visitors. This study focuses on assessing the relationship between hybrid cognition of visitors expressed via Instagram and their bond with the destination. Further to this, the study attempts to examine the impact of hybrid cognition of visitors on the behavioral pattern of prospective visitors to the destination. The study revealed that sharing of visual imageries and related text by the visitors is an expression of the physico-emotional bonding with the destination. It was further established that hybrid cognition strongly asserts destination bonding and has been also found to have moderating impact on the link between destination bonding and electronic-word-of-mouth.

  14. Bond financing for renewable energy in Asia

    International Nuclear Information System (INIS)

    Ng, Thiam Hee; Tao, Jacqueline Yujia

    2016-01-01

    Addressing the financing gap for renewable energy (RE) projects in Asia is critical to ensure that the rapidly increasing energy needs could be met sustainably. This paper explores the cause of the financing gap in Asia and proposes the use of bond financing to address the financing gap. Specifically, three fixed income instruments, namely local currency denominated (LCY) corporate bonds, asset backed project bonds and financial green bonds, will be assessed. Whilst the potential for these three instruments to mobilize large flows of private sector financing is great, key supportive policies aimed at reducing the capital market bias for conventional power generation technologies and supportive RE policies are required. Another key aspect would be the necessary deepening of local and regional fixed income markets before such capital market instruments are able to play a big role. - Highlights: •This study looks at the current financing gap and RE financing landscape in developing Asia. •LCY corporate bonds, asset backed projects bonds and financial green bonds could help to address the financing gap for RE in the region. •Policy recommendations for building the fixed income market for RE projects are provided.

  15. Bond markets in Africa

    Directory of Open Access Journals (Sweden)

    Yibin Mu

    2013-07-01

    Full Text Available African bond markets have been steadily growing in recent years, but nonetheless remain undeveloped. African countries would benefit from greater access to financing and deeper financial markets. This paper compiles a unique set of data on government securities and corporate bond markets in Africa. It then applies an econometric model to analyze the key determinants of African government securities market and corporate bond market capitalization. Government securities market capitalization is directly related to better institutions and interest rate volatility, and inversely related to smaller fiscal deficits, higher interest rate spreads, exchange rate volatility, and current and capital account openness. Corporate bond market capitalization is directly linked to economic size, the level of development of the economy and financial markets, better institutions, and interest rate volatility, and inversely related to higher interest rate spreads and current account openness. Policy implications follow.

  16. Tensile Bond Strength of Metal Bracket Bonding to Glazed Ceramic Surfaces With Different Surface Conditionings

    Directory of Open Access Journals (Sweden)

    M. Imani

    2011-12-01

    Full Text Available Objective: The objective of this study was to compare the tensile bond strength of metal brackets bonding to glazed ceramic surfaces using three various surface treatments.Materials and Methods: Forty two glazed ceramic disks were assigned to three groups. In the first and second groups the specimens were etched with 9.5% hydrofluoric acid (HFA. Subsequently in first group, ceramic primer and adhesive were applied, but in second group a bonding agent alone was used. In third group, specimens were treated with 35% phosphoric acid followed by ceramic primerand adhesive application. Brackets were bonded with light cure composites. The specimens were stored in distilled water in the room temperature for 24 hours and thermocycled 500 times between 5°C and 55°C. The universal testing machine was used to test the tensile bond strength and the adhesive remenant index scores between three groups was evaluated. The data were subjected to one-way ANOVA, Tukey and Kruskal-Wallis tests respectively.Results: The tensile bond strength was 3.69±0.52 MPa forfirst group, 2.69±0.91 MPa for second group and 3.60±0.41 MPa for third group. Group II specimens showed tensile strength values significantly different from other groups (P<0.01.Conclusion: In spite of limitations in laboratory studies it may be concluded that in application of Scotch bond multipurpose plus adhesive, phosphoric acid can be used instead of HFA for bonding brackets to the glazed ceramic restorations with enough tensile bond strength.

  17. Handbook of wafer bonding

    CERN Document Server

    Ramm, Peter; Taklo, Maaike M V

    2011-01-01

    Written by an author and editor team from microsystems companies and industry-near research organizations, this handbook and reference presents dependable, first-hand information on bonding technologies.In the first part, researchers from companies and institutions around the world discuss the most reliable and reproducible technologies for the production of bonded wafers. The second part is devoted to current and emerging applications, including microresonators, biosensors and precise measuring devices.

  18. Diffusion bonding techniques

    International Nuclear Information System (INIS)

    Peters, R.D.

    1978-01-01

    The applications of diffusion bonding at the General Electric Neutron Devices Department are briefly discussed, with particular emphasis on the gold/gold or gold/indium joints made between metallized alumina ceramic parts in the vacuum switch tube and the crystal resonator programs. Fixtures which use the differential expansion of dissimilar metals are described and compared to one that uses hydraulic pressure to apply the necessary bonding force

  19. The Agent of Change: The Agent of Conflict.

    Science.gov (United States)

    Hatfield, C. R., Jr.

    This speech examines the role of change agents in third world societies and indicates that the change agent must, to some extent, manipulate the social situation, even if his view of society is a more optimistic one than he finds in reality. If he considers strains and stresses to be the lubricants of change, then his focus on conflict as a…

  20. Using Diffusion Bonding in Making Piezoelectric Actuators

    Science.gov (United States)

    Sager, Frank E.

    2003-01-01

    A technique for the fabrication of piezoelectric actuators that generate acceptably large forces and deflections at relatively low applied voltages involves the stacking and diffusion bonding of multiple thin piezoelectric layers coated with film electrodes. The present technique stands in contrast to an older technique in which the layers are bonded chemically, by use of urethane or epoxy agents. The older chemical-bonding technique entails several disadvantages, including the following: It is difficult to apply the bonding agents to the piezoelectric layers. It is difficult to position the layers accurately and without making mistakes. There is a problem of disposal of hazardous urethane and epoxy wastes. The urethane and epoxy agents are nonpiezoelectric materials. As such, they contribute to the thickness of a piezoelectric laminate without contributing to its performance; conversely, for a given total thickness, the performance of the laminate is below that of a unitary piezoelectric plate of the same thickness. The figure depicts some aspects of the fabrication of a laminated piezoelectric actuator by the present diffusion- bonding technique. First, stock sheets of the piezoelectric material are inspected and tested. Next, the hole pattern shown in the figure is punched into the sheets. Alternatively, if the piezoelectric material is not a polymer, then the holes are punched in thermoplastic films. Then both faces of each punched piezoelectric sheet or thermoplastic film are coated with a silver-ink electrode material by use of a silkscreen printer. The electrode and hole patterns are designed for minimal complexity and minimal waste of material. After a final electrical test, all the coated piezoelectric layers (or piezoelectric layers and coated thermoplastic films) are stacked in an alignment jig, which, in turn, is placed in a curved press for the diffusion-bonding process. In this process, the stack is pressed and heated at a specified curing temperature

  1. Effects of subinhibitory concentrations of antimicrobial agents on Escherichia coli O157:H7 Shiga toxin release and role of the SOS response.

    Science.gov (United States)

    Nassar, Farah J; Rahal, Elias A; Sabra, Ahmad; Matar, Ghassan M

    2013-09-01

    Treatment of Escherichia coli O157:H7 by certain antimicrobial agents often exacerbates the patient's condition by increasing either the release of preformed Shiga toxins (Stx) upon cell lysis or their production through the SOS response-triggered induction of Stx-producing prophages. Recommended subinhibitory concentrations (sub-MICs) of azithromycin (AZI), gentamicin (GEN), imipenem (IMI), and rifampicin (RIF) were evaluated in comparison to norfloxacin (NOR), an SOS-inducer, to assess the role of the SOS response in Stx release. Relative expression of recA (SOS-inducer), Q (late antitermination gene of Stx-producing prophage), stx1, and stx2 genes was assessed at two sub-MICs of the antimicrobials for two different strains of E. coli O157:H7 using reverse transcription-real-time polymerase chain reaction. Both strains at the two sub-MICs were also subjected to Western blotting for LexA protein expression and to reverse passive latex agglutination for Stx detection. For both strains at both sub-MICs, NOR and AZI caused SOS-induced Stx production (high recA, Q, and stx2 gene expression and high Stx2 production), so they should be avoided in E. coli O157:H7 treatment; however, sub-MICs of RIF and IMI induced Stx2 production in an SOS-independent manner except for one strain at the first twofold dilution below MIC of RIF where Stx2 production decreased. Moreover, GEN caused somewhat increased Stx2 production due to its mode of action rather than any effect on gene expression. The choice of antimicrobial therapy should rely on the antimicrobial mode of action, its concentration, and on the nature of the strain.

  2. Integrating evolutionary game theory into an agent-based model of ductal carcinoma in situ: Role of gap junctions in cancer progression.

    Science.gov (United States)

    Malekian, Negin; Habibi, Jafar; Zangooei, Mohammad Hossein; Aghakhani, Hojjat

    2016-11-01

    There are many cells with various phenotypic behaviors in cancer interacting with each other. For example, an apoptotic cell may induce apoptosis in adjacent cells. A living cell can also protect cells from undergoing apoptosis and necrosis. These survival and death signals are propagated through interaction pathways between adjacent cells called gap junctions. The function of these signals depends on the cellular context of the cell receiving them. For instance, a receiver cell experiencing a low level of oxygen may interpret a received survival signal as an apoptosis signal. In this study, we examine the effect of these signals on tumor growth. We make an evolutionary game theory component in order to model the signal propagation through gap junctions. The game payoffs are defined as a function of cellular context. Then, the game theory component is integrated into an agent-based model of tumor growth. After that, the integrated model is applied to ductal carcinoma in situ, a type of early stage breast cancer. Different scenarios are explored to observe the impact of the gap junction communication and parameters of the game theory component on cancer progression. We compare these scenarios by using the Wilcoxon signed-rank test. The Wilcoxon signed-rank test succeeds in proving a significant difference between the tumor growth of the model before and after considering the gap junction communication. The Wilcoxon signed-rank test also proves that the tumor growth significantly depends on the oxygen threshold of turning survival signals into apoptosis. In this study, the gap junction communication is modeled by using evolutionary game theory to illustrate its role at early stage cancers such as ductal carcinoma in situ. This work indicates that the gap junction communication and the oxygen threshold of turning survival signals into apoptosis can notably affect cancer progression. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  3. Investigation of glutathione-derived electrostatic and hydrogen-bonding interactions and their role in defining Grx5 [2Fe-2S] cluster optical spectra and transfer chemistry.

    Science.gov (United States)

    Sen, Sambuddha; Bonfio, Claudia; Mansy, Sheref S; Cowan, J A

    2018-03-01

    Human glutaredoxin 5 (Grx5) is one of the core components of the Isc (iron-sulfur cluster) assembly and trafficking machinery, and serves as an intermediary cluster carrier, putatively delivering cluster from the Isu scaffold protein to target proteins. The tripeptide glutathione is intimately involved in this role, providing cysteinyl coordination to the iron center of the Grx5-bound [2Fe-2S] cluster. Grx5 has a well-defined glutathione-binding pocket with protein amino acid residues providing many ionic and hydrogen binding contacts to the bound glutathione. In this report, we investigated the importance of these interactions in cluster chirality and exchange reactivity by systematically perturbing the crucial contacts by use of natural and non-natural amino acid substitutions to disrupt the binding contacts from both the protein and glutathione. Native Grx5 could be reconstituted with all of the glutathione analogs used, as well as other thiol ligands, such as DTT or L-cysteine, by in vitro chemical reconstitution, and the holo proteins were found to transfer [2Fe-2S] cluster to apo ferredoxin 1 at comparable rates. However, the circular dichroism spectra of these derivatives displayed prominent differences that reflect perturbations in local cluster chirality. These studies provided a detailed molecular understanding of glutathione-protein interactions in holo Grx5 that define both cluster spectroscopy and exchange chemistry.

  4. Bonding and magnetic response properties of several toroid structures. Insights of the role of Ni2S2 as a building block from relativistic density functional theory calculations.

    Science.gov (United States)

    Muñoz-Castro, Alvaro

    2011-10-06

    Relativistic density functional calculations were carried out on several nickel toroid mercaptides of the general formula [Ni(μ-SR)(2)](n), with the aim to characterize and analyze their stability and magnetic response properties, in order to gain more insights into their stabilization and size-dependent behavior. The Ni-ligand interaction has been studied by means projected density of states and energy decomposition analysis, which denotes its stabilizing character. The graphical representation of the response to an external magnetic field is applied for the very first time taking into account the spin-orbit term. This map allows one to clearly characterize the magnetic behavior inside and in the closeness of the toroid structure showing the prescence of paratropic ring currents inside the Ni(n) ring, and by contrast, diatropic currents confined in each Ni(2)S(2) motif denoting an aromatic behavior (in terms of magnetic criteria). The calculated data suggests that the Ni(2)S(2) moiety can be regarded as a stable constructing block, which can afford several toroid structures of different nuclearities in agreement with that reported in the experimental literature. In addition, the effects of the relativistic treatment over the magnetic response properties on these lighter compounds are denoted by comparing nonrelativistic, scalar relativistic, and scalar plus spin-orbit relativistic treatments, showing their acting, although nonpronunced, role.

  5. Comparison of shear bond strength of amalgam bonded to primary and permanent dentin

    Directory of Open Access Journals (Sweden)

    Mahdi S

    2008-06-01

    Full Text Available Amalgam′s non-adhesive characteristics necessitate cavity preparations incorporating retentive features, which often require the removal of non-carious tooth structure. Use of adhesives beneath amalgam restorations, would be helpful to overcome this disadvantage. This study was undertaken to compare the mean shear bond strength of amalgam bonded to primary and permanent dentin, to evaluate the efficacy of amalgam adhesives in pediatric dentistry.27 primary and 28 permanent posterior teeth with intact buccal or lingual surfaces were grounded to expose dentin and wet-polished with 400-grit silicone carbide paper. Scotchbond Multi Purpose Plus adhesive system was applied to the dentin surfaces and light cured. Amalgam was condensed onto the treated dentin through a plastic mold.shear bond strength testing was done using an Instron Universal testing machine, at a crosshead speed of 0.5 mm/min.The data were analyzed by independent samples t-test The difference among the two groups was not statistically significant (p>0.05 Bonded amalgam showed the same level of bond strength to primary and permanent dentin; so, application of amalgam bonding agents in pediatric dentistry can be recommended.

  6. Longevity of Self-etch Dentin Bonding Adhesives Compared to Etch-and-rinse Dentin Bonding Adhesives: A Systematic Review.

    Science.gov (United States)

    Masarwa, Nader; Mohamed, Ahmed; Abou-Rabii, Iyad; Abu Zaghlan, Rawan; Steier, Liviu

    2016-06-01

    A systematic review and meta-analysis were performed to compare longevity of Self-Etch Dentin Bonding Adhesives to Etch-and-Rinse Dentin Bonding Adhesives. The following databases were searched for PubMed, MEDLINE, Web of Science, CINAHL, the Cochrane Library complemented by a manual search of the Journal of Adhesive Dentistry. The MESH keywords used were: "etch and rinse," "total etch," "self-etch," "dentin bonding agent," "bond durability," and "bond degradation." Included were in-vitro experimental studies performed on human dental tissues of sound tooth structure origin. The examined Self-Etch Bonds were of two subtypes; Two Steps and One Step Self-Etch Bonds, while Etch-and-Rinse Bonds were of two subtypes; Two Steps and Three Steps. The included studies measured micro tensile bond strength (μTBs) to evaluate bond strength and possible longevity of both types of dental adhesives at different times. The selected studies depended on water storage as the aging technique. Statistical analysis was performed for outcome measurements compared at 24 h, 3 months, 6 months and 12 months of water storage. After 24 hours (p-value = 0.051), 3 months (p-value = 0.756), 6 months (p-value=0.267), 12 months (p-value=0.785) of water storage self-etch adhesives showed lower μTBs when compared to the etch-and-rinse adhesives, but the comparisons were statistically insignificant. In this study, longevity of Dentin Bonds was related to the measured μTBs. Although Etch-and-Rinse bonds showed higher values at all times, the meta-analysis found no difference in longevity of the two types of bonds at the examined aging times. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. The social life of bonding theory.

    Science.gov (United States)

    Crouch, M; Manderson, L

    1995-09-01

    'Bonding' as a crucial factor of the early post-partum entered obstetric and paediatric practice after the publication of Maternal and Infant Bonding in 1976 by Klaus and Kennell. The concept has held its place since, as witnessed by medical textbook accounts of it, and the perception of 'instantaneous bonding' as a vital component of the ideal birth experience has dominated media representations of childbirth and, until very recently, feminist writing. Only during the last few years has this literature taken into account research findings concerning the guilt and anxiety experienced by women whose expectations regarding 'bonding' are not realised. While it is now generally acknowledged that maternal attachment develops over an extended period of time, 'bonding' as used extensively in both popular and scientific literature conflates a wide range of meanings and blurs the boundaries between process and outcome. This facilitates the entry of ideological elements into a field which is, by its very nature, deeply significant for human experience. We therefore argue for a continuing critical appraisal of the role of 'bonding' in both general and scientific research.

  8. Romanian government bond market

    Directory of Open Access Journals (Sweden)

    Cornelia POP

    2012-12-01

    Full Text Available The present paper aims to present the level of development reached by Romanian government bond market segment, as part of the country financial market. The analysis will be descriptive (the data series available for Romania are short, based on the secondary data offered by the official bodies involved in the process of issuing and trading the Romanian government bonds (Romanian Ministry of Public Finance, Romanian National Bank and Bucharest Stock Exchange, and also on secondary data provided by the Federation of European Stock Exchanges.To enhance the market credibility as a benchmark, a various combination of measures is necessary; among these measures are mentioned: the extension of the yield curve; the issuance calendars in order to improve transparency; increasing the disclosure of information on public debt issuance and statistics; holding regular meetings with dealers, institutional investors and rating agencies; introducing a system of primary dealers; establishing a repurchase (repo market in the government bond market. These measures will be discussed based on the evolution presented inside the paper.The paper conclude with the fact that, until now, the Romanian government bond market did not provide a benchmark for the domestic financial market and that further efforts are needed in order to increase the government bond market transparency and liquidity.

  9. Interstellar hydrogen bonding

    Science.gov (United States)

    Etim, Emmanuel E.; Gorai, Prasanta; Das, Ankan; Chakrabarti, Sandip K.; Arunan, Elangannan

    2018-06-01

    This paper reports the first extensive study of the existence and effects of interstellar hydrogen bonding. The reactions that occur on the surface of the interstellar dust grains are the dominant processes by which interstellar molecules are formed. Water molecules constitute about 70% of the interstellar ice. These water molecules serve as the platform for hydrogen bonding. High level quantum chemical simulations for the hydrogen bond interaction between 20 interstellar molecules (known and possible) and water are carried out using different ab-intio methods. It is evident that if the formation of these species is mainly governed by the ice phase reactions, there is a direct correlation between the binding energies of these complexes and the gas phase abundances of these interstellar molecules. Interstellar hydrogen bonding may cause lower gas abundance of the complex organic molecules (COMs) at the low temperature. From these results, ketenes whose less stable isomers that are more strongly bonded to the surface of the interstellar dust grains have been observed are proposed as suitable candidates for astronomical observations.

  10. Safe and Liquid Mortgage Bonds

    DEFF Research Database (Denmark)

    Dick-Nielsen, Jens; Gyntelberg, Jacob; Lund, Jesper

    This paper shows that strict match pass-through funding of covered bonds provides safe and liquid mortgage bonds. Despite a 30% drop in house prices during the 2008 global crisis Danish mortgage bonds remained as liquid as most European government bonds. The Danish pass-through system effectively...... eliminates credit risk from the investor's perspective. Similar to other safe bonds, funding liquidity becomes the main driver of mortgage bond liquidity and this creates commonality in liquidity across markets and countries. These findings have implications for how to design a robust mortgage bond system...

  11. The Role of Implicit Motives in Strategic Decision-Making: Computational Models of Motivated Learning and the Evolution of Motivated Agents

    Directory of Open Access Journals (Sweden)

    Kathryn Merrick

    2015-11-01

    Full Text Available Individual behavioral differences in humans have been linked to measurable differences in their mental activities, including differences in their implicit motives. In humans, individual differences in the strength of motives such as power, achievement and affiliation have been shown to have a significant impact on behavior in social dilemma games and during other kinds of strategic interactions. This paper presents agent-based computational models of power-, achievement- and affiliation-motivated individuals engaged in game-play. The first model captures learning by motivated agents during strategic interactions. The second model captures the evolution of a society of motivated agents. It is demonstrated that misperception, when it is a result of motivation, causes agents with different motives to play a given game differently. When motivated agents who misperceive a game are present in a population, higher explicit payoff can result for the population as a whole. The implications of these results are discussed, both for modeling human behavior and for designing artificial agents with certain salient behavioral characteristics.

  12. [Biological agents].

    Science.gov (United States)

    Amano, Koichi

    2009-03-01

    There are two types of biological agents for the treatment of rheumatoid arthritis (RA); monoclonal antibodies and recombinant proteins. Among the latter, etanercept, a recombinant fusion protein of soluble TNF receptor and IgG was approved in 2005 in Japan. The post-marketing surveillance of 13,894 RA patients revealed the efficacy and safety profiles of etanercept in the Japanese population, as well as overseas studies. Abatacept, a recombinant fusion protein of CTLA4 and IgG, is another biological agent for RA. Two clinical trials disclosed the efficacy of abatacept for difficult-to-treat patients: the AIM for MTX-resistant cases and the ATTAIN for patients who are resistant to anti-TNF. The ATTEST trial suggested abatacept might have more acceptable safety profile than infliximab. These biologics are also promising for the treatment of RA for not only relieving clinical symptoms and signs but retarding structural damage.

  13. Effects of hemostatic agents on shear bond strength of orthodontic ...

    African Journals Online (AJOL)

    2014-08-14

    Aug 14, 2014 ... Clinical Significance: In impacted tooth surgical operations, blood contamination poses a ... impacted teeth operation for the prevention of blood contamination. ... preparations including solutions, sprays, and tampons. It.

  14. Significance of wood extractives for wood bonding.

    Science.gov (United States)

    Roffael, Edmone

    2016-02-01

    Wood contains primary extractives, which are present in all woods, and secondary extractives, which are confined in certain wood species. Extractives in wood play a major role in wood-bonding processes, as they can contribute to or determine the bonding relevant properties of wood such as acidity and wettability. Therefore, extractives play an immanent role in bonding of wood chips and wood fibres with common synthetic adhesives such as urea-formaldehyde-resins (UF-resins) and phenol-formaldehyde-resins (PF-resins). Extractives of high acidity accelerate the curing of acid curing UF-resins and decelerate bonding with alkaline hardening PF-resins. Water-soluble extractives like free sugars are detrimental for bonding of wood with cement. Polyphenolic extractives (tannins) can be used as a binder in the wood-based industry. Additionally, extractives in wood can react with formaldehyde and reduce the formaldehyde emission of wood-based panels. Moreover, some wood extractives are volatile organic compounds (VOC) and insofar also relevant to the emission of VOC from wood and wood-based panels.

  15. Hydrogen bonded supramolecular materials

    CERN Document Server

    Li, Zhan-Ting

    2015-01-01

    This book is an up-to-date text covering topics in utilizing hydrogen bonding for constructing functional architectures and supramolecular materials. The first chapter addresses the control of photo-induced electron and energy transfer. The second chapter summarizes the formation of nano-porous materials. The following two chapters introduce self-assembled gels, many of which exhibit unique functions. Other chapters cover the advances in supramolecular liquid crystals and the versatility of hydrogen bonding in tuning/improving the properties and performance of materials. This book is designed

  16. Continuing bonds and place.

    Science.gov (United States)

    Jonsson, Annika; Walter, Tony

    2017-08-01

    Where do people feel closest to those they have lost? This article explores how continuing bonds with a deceased person can be rooted in a particular place or places. Some conceptual resources are sketched, namely continuing bonds, place attachment, ancestral places, home, reminder theory, and loss of place. The authors use these concepts to analyze interview material with seven Swedes and five Britons who often thought warmly of the deceased as residing in a particular place and often performing characteristic actions. The destruction of such a place, by contrast, could create a troubling, haunting absence, complicating the deceased's absent-presence.

  17. 31 CFR 351.47 - May I purchase definitive Series EE savings bonds through a payroll savings plan?

    Science.gov (United States)

    2010-07-01

    ... savings bonds through a payroll savings plan? 351.47 Section 351.47 Money and Finance: Treasury....47 May I purchase definitive Series EE savings bonds through a payroll savings plan? You may purchase... maintains a payroll savings plan. An authorized issuing agent must issue the bonds. ...

  18. Comparison of the biological effects of MMS and Me-lex, a minor groove methylating agent: clarifying the role of N3-methyladenine.

    Science.gov (United States)

    Monti, Paola; Foggetti, Giorgia; Menichini, Paola; Inga, Alberto; Gold, Barry; Fronza, Gilberto

    2014-01-01

    N3-methyladenine (3-mA), generated by the reaction of methylating agents with DNA, is considered a highly toxic but weakly mutagenic lesion. However, due to its intrinsic instability, some of the biological effects of the adduct can result from the formation of the corresponding depurination product [an apurinic (AP)-site]. Previously, we exploited Me-lex, i.e. {1-methyl-4-[1-methyl-4-(3-methoxysulfonylpropanamido)pyrrole-2-carboxamido]-pyrrole-2 carboxamido}propane, a minor groove equilibrium binder with selectivity for A/T rich sequences that efficiently reacts with DNA to afford 3-mA as the dominant product, to probe the biology of this lesion. Using human p53 cDNA as a target in a yeast system, a weak increase in mutagenicity was observed in the absence of Mag1 (3-methyladenine-DNA glycosylase 1, mag1), the enzyme devoted to remove 3-mA from DNA. Moreover, a significant increase in mutagenicity occurred in the absence of the enzymes involved in the repair of AP-sites (AP endonucleases 1 and 2, apn1apn2). Since methyl methanesulfonate (MMS) has been extensively used to explore the biological effects of 3-mA, even though it produces 3-mA in low relative yield, we compared the toxicity and mutagenicity induced by MMS and Me-lex in yeast. A mutagenesis reporter plasmid was damaged in vitro by MMS and then transformed into wild-type and Translesion Synthesis (TLS) Polζ (REV3) and Polη (RAD30) deficient strains. Furthermore, a mag1rad30 double mutant strain was constructed and transformed with the DNA plasmid damaged in vitro by Me-lex. The results confirm the important role of Polζ in the mutagenic bypass of MMS and Me-lex induced lesions, with Polη contributing only towards the bypass of Me-lex induced lesions, mainly in an error-free way. Previous and present results point towards the involvement of AP-sites, derived from the depurination of 3-mA, in the observed toxicity and mutagenicity. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Role of mono- and oligosaccharides from FOS as stabilizing agents during freeze-drying and storage of Lactobacillus delbrueckii subsp. bulgaricus.

    Science.gov (United States)

    Romano, Nelson; Schebor, Carolina; Mobili, Pablo; Gómez-Zavaglia, Andrea

    2016-12-01

    The aim of this work was to assess the role of mono- and oligosaccharides present in fructo-oligosaccharides (FOS) mixtures as protective agents during freeze-drying and storage of Lactobacillus delbrueckii subsp. bulgaricus CIDCA 333. Different FOS mixtures were enzymatically obtained from sucrose and further purified by removing the monosaccharides produced as secondary products. Their glass transition temperatures (T g ) were determined at 11, 22 and 33% relative humidity (RH). Bacterial cultures were freeze-dried in the presence of 20% w/v solutions of the studied FOS. Their protective effect during freeze-drying was assessed by bacterial plate counting, and by determining the lag time from growth kinetics and the uptake of propidium iodide (PI). Plate counting during bacterial storage at 4°C, and 11, 22 and 33% RH for 80days completed this rational analysis of the protective effect of FOS. Purification of FOS led to an increase of T g in all the conditions assayed. Microorganisms freeze-dried in the presence of non-purified FOS were those with the shortest lag times. Bacteria freeze-dried with pure or commercial FOS (92% of total FOS) showed larger lag times (8.9-12.6h). The cultivability of microorganisms freeze-dried with non-purified FOS and with sucrose was not significantly different from that of bacteria before freeze-drying (8.74±0.14logCFU/mL). Pure or commercial FOS were less efficient in protecting bacteria during freeze-drying. All the protectants prevented membrane damage. The cultivability of bacteria freeze-dried with FOS decayed <1logarithmicunit after 80days of storage at 11% RH. When storing at 22 and 33% RH, pure and commercial FOS were those that best protected bacteria, and FOS containing monosaccharides were less efficient. The effect of FOS on bacterial protection is the result of a balance between monosaccharides, sucrose and larger FOS in the mixtures: the smallest sugars are more efficient in protecting lipid membranes, and the

  20. Disulphide bond formation in food protein aggregation and gelation

    NARCIS (Netherlands)

    Visschers, R.W.; Jongh, de H.H.J.

    2005-01-01

    In this short review we discuss the role of cysteine residues and cystine bridges for the functional aggregation of food proteins. We evaluate how formation and cleavage of disulphide bonds proceeds at a molecular level, and how inter- and intramolecular disulfide bonds can be detected and modified.

  1. Structural and Biochemical Characterization of a Copper-Binding Mutant of the Organomercurial Lyase MerB: Insight into the Key Role of the Active Site Aspartic Acid in Hg-Carbon Bond Cleavage and Metal Binding Specificity.

    Science.gov (United States)

    Wahba, Haytham M; Lecoq, Lauriane; Stevenson, Michael; Mansour, Ahmed; Cappadocia, Laurent; Lafrance-Vanasse, Julien; Wilkinson, Kevin J; Sygusch, Jurgen; Wilcox, Dean E; Omichinski, James G

    2016-02-23

    In bacterial resistance to mercury, the organomercurial lyase (MerB) plays a key role in the detoxification pathway through its ability to cleave Hg-carbon bonds. Two cysteines (C96 and C159; Escherichia coli MerB numbering) and an aspartic acid (D99) have been identified as the key catalytic residues, and these three residues are conserved in all but four known MerB variants, where the aspartic acid is replaced with a serine. To understand the role of the active site serine, we characterized the structure and metal binding properties of an E. coli MerB mutant with a serine substituted for D99 (MerB D99S) as well as one of the native MerB variants containing a serine residue in the active site (Bacillus megaterium MerB2). Surprisingly, the MerB D99S protein copurified with a bound metal that was determined to be Cu(II) from UV-vis absorption, inductively coupled plasma mass spectrometry, nuclear magnetic resonance, and electron paramagnetic resonance studies. X-ray structural studies revealed that the Cu(II) is bound to the active site cysteine residues of MerB D99S, but that it is displaced following the addition of either an organomercurial substrate or an ionic mercury product. In contrast, the B. megaterium MerB2 protein does not copurify with copper, but the structure of the B. megaterium MerB2-Hg complex is highly similar to the structure of the MerB D99S-Hg complexes. These results demonstrate that the active site aspartic acid is crucial for both the enzymatic activity and metal binding specificity of MerB proteins and suggest a possible functional relationship between MerB and its only known structural homologue, the copper-binding protein NosL.

  2. Coxsackievirus B4 as a Causative Agent of Diabetes Mellitus Type 1: Is There a Role of Inefficiently Treated Drinking Water and Sewage in Virus Spreading?

    Science.gov (United States)

    El-Senousy, Waled M; Abdel-Moneim, Adel; Abdel-Latif, Mahmoud; El-Hefnawy, Mohamed H; Khalil, Rehab G

    2018-03-01

    for isolation of separate EV isolates from treated and untreated water and sewage samples. Characterization of the EV amplicons by RT-PCR followed by sequencing of these isolates revealed high homology (97%) with human coxsackievirus B4 (CV B4) in 60% of the isolates, while the rest of the isolates belonged to poliovirus type 1 and type 2 vaccine strains. On the other hand, characterization of the EV amplicons by RT-PCR followed by sequencing for T1D-EV + children specimens indicated that all samples contained CV B4 with the same sequence characterized in the environmental samples. CV B4-contaminated drinking water or treated sewage may play a role as a causative agent of T1D in children.

  3. Trading Agents

    CERN Document Server

    Wellman, Michael

    2011-01-01

    Automated trading in electronic markets is one of the most common and consequential applications of autonomous software agents. Design of effective trading strategies requires thorough understanding of how market mechanisms operate, and appreciation of strategic issues that commonly manifest in trading scenarios. Drawing on research in auction theory and artificial intelligence, this book presents core principles of strategic reasoning that apply to market situations. The author illustrates trading strategy choices through examples of concrete market environments, such as eBay, as well as abst

  4. Integration of European Bond Markets

    DEFF Research Database (Denmark)

    Christiansen, Charlotte

    2014-01-01

    I investigate the time variation in the integration of EU government bond markets. The integration is measured by the explanatory power of European factor portfolios for the individual bond markets for each year. The integration of the government bond markets is stronger for EMU than non-EMU memb......I investigate the time variation in the integration of EU government bond markets. The integration is measured by the explanatory power of European factor portfolios for the individual bond markets for each year. The integration of the government bond markets is stronger for EMU than non...

  5. Convertible bond valuation focusing on Chinese convertible bond market

    OpenAIRE

    Yang, Ke

    2010-01-01

    This paper mainly discusses the methods of valuation of convertible bonds in Chinese market. Different from common convertible bonds in European market, considering the complicate features of Chinese convertible bond, this paper represents specific pricing approaches for pricing convertible bonds with different provisions along with the increment of complexity of these provisions. More specifically, this paper represents the decomposing method and binomial tree method for pricing both of Non-...

  6. Overall survival patterns in patients with multiple myeloma in the era of novel agents and the role of initial clinical presentation and comorbidities: A population-based study

    NARCIS (Netherlands)

    Oortgiesen, Berdien; Van Roon, Eric N.; Joosten, Peter; Kibbelaar, Robby; Storm, Huib; Hovenga, Sjoerd; Van Rees, Bas P.; Woolthuis, Gerhard; Veeger, Nic J. G. M.; Hoogendoorn, Mels

    2014-01-01

    Introduction Clinical trials have shown improved response rates, progression-free survival and overall survival (OS) in patients with multiple myeloma (MM) when using the novel agents thalidomide, lenalidomide and bortezomib. However, outcome data provided by population-based registries, reflecting

  7. Adolescents' Financial Literacy: The Role of Financial Socialization Agents, Financial Experiences, and Money Attitudes in Shaping Financial Literacy among South Korean Youth

    Science.gov (United States)

    Sohn, Sang-Hee; Joo, So-Hyun; Grable, John E.; Lee, Seonglim; Kim, Minjeung

    2012-01-01

    The purpose of this study was to test the relationships between financial socialization agents, financial experiences, money attitudes, demographic characteristics, and the financial literacy of Korean adolescents. Using the 2006 Korean National Financial Literacy Test Survey for Adolescents (N = 1185), a series of regression analyses were…

  8. 基于多智能体协同的角色互换策略的研究应用%Research Application Based on Strategy of Multi-Agent Cooperative Role Exchange

    Institute of Scientific and Technical Information of China (English)

    章成飞; 程泽凯; 秦锋

    2013-01-01

    Multi-Agent cooperative technology is an important branch in the field of Artificial Intelligence ( AI) . Robot football race pro-vides a test platform for the study of Multi-Agent cooperative technology. The football player named Agent in the robot simulation foot-ball race has both number attribute and role attribute. It makes Agent in the robot simulation football race as the research subject. Model for Agent with online coach mechanism and put forward the tactics to identify the counterparts as well as the strategy of football players'dynamic role exchange. In the underlying 2D of Agent,programming comes into effect. When one robot simulation football team tests with the other one,the winning probability is going to be raised by a big margin,which demonstrates the efficiency of this algorithm. And the algorithm can also improve attack ability of the football team.%多智能体协同技术是人工智能领域的一个重要分支。机器人足球比赛为多智能体协同技术的研究提供了一个测试平台,仿真机器人足球比赛球员Agent具有号码属性与角色属性。文中以仿真机器人足球比赛中的球员Agent为研究对象,利用在线教练机制对球员Agent进行建模,提出了对手角色识别策略以及基于多智能体协同的球员Agent动态角色互换策略。在Agent2D底层中编程实现,与某球队进行测试,胜率大大增加,结果表明了该算法的有效性,该算法可提高球队的进攻能力。

  9. Comparison of shear bond strength of the stainless steel metallic brackets bonded by three bonding systems

    Directory of Open Access Journals (Sweden)

    Mehdi Ravadgar

    2013-09-01

    Full Text Available Introduction: In orthodontic treatment, it is essential to establish a satisfactory bond between enamel and bracket. After the self-etch primers (SEPs were introduced for the facilitation of bracket bonding in comparison to the conventional etch-and-bond system, multiple studies have been carried out on their shear bond strengths which have yielded different results. This study was aimed at comparing shear bond strengths of the stainless steel metallic brackets bonded by three bonding systems. Methods: In this experimental in vitro study, 60 extracted human maxillary premolar teeth were randomly divided into three equal groups: in the first group, Transbond XT (TBXT light cured composite was bonded with Transbond plus self-etching primer (TPSEP in the second group, TBXT composite was bonded with the conventional method of acid etching and in the third group, the self cured composite Unite TM bonding adhesive was bonded with the conventional method of acid etching. In all the groups, Standard edgewise-022 metallic brackets (American Orthodontics, Sheboygan, USA were used. Twenty-four hours after the completion of thermocycling, shear bond strength of brackets was measured by Universal Testing Machine (Zwick. In order to compare the shear bond strengths of the groups, the variance analysis test (ANOVA was adopted and p≤0.05 was considered as a significant level. Results: Based on megapascal, the average shear bond strength for the first, second, and third groups was 8.27±1.9, 9.78±2, and 8.92±2.5, respectively. There was no significant difference in the shear bond strength of the groups. Conclusions: Since TPSEP shear bond strength is approximately at the level of the conventional method of acid etching and within the desirable range for orthodontic brackets shear bond strength, applying TPSEP can serve as a substitute for the conventional method of etch and bond, particularly in orthodontic operations.

  10. Comparison of shear bond strength of the stainless steel metallic brackets bonded by three bonding systems

    Directory of Open Access Journals (Sweden)

    Mehdi Ravadgar

    2013-09-01

    Full Text Available Introduction: In orthodontic treatment, it is essential to establish a satisfactory bond between enamel and bracket. After the self-etch primers (SEPs were introduced for the facilitation of bracket bonding in comparison to the conventional etch-and-bond system, multiple studies have been carried out on their shear bond strengths which have yielded different results. This study was aimed at comparing shear bond strengths of the stainless steel metallic brackets bonded by three bonding systems. Methods: In this experimental in vitro study, 60 extracted human maxillary premolar teeth were randomly divided into three equal groups: in the first group, Transbond XT (TBXT light cured composite was bonded with Transbond plus self-etching primer (TPSEP; in the second group, TBXT composite was bonded with the conventional method of acid etching; and in the third group, the self cured composite Unite TM bonding adhesive was bonded with the conventional method of acid etching. In all the groups, Standard edgewise-022 metallic brackets (American Orthodontics, Sheboygan, USA were used. Twenty-four hours after the completion of thermocycling, shear bond strength of brackets was measured by Universal Testing Machine (Zwick. In order to compare the shear bond strengths of the groups, the variance analysis test (ANOVA was adopted and p≤0.05 was considered as a significant level. Results: Based on megapascal, the average shear bond strength for the first, second, and third groups was 8.27±1.9, 9.78±2, and 8.92±2.5, respectively. There was no significant difference in the shear bond strength of the groups. Conclusions: Since TPSEP shear bond strength is approximately at the level of the conventional method of acid etching and within the desirable range for orthodontic brackets shear bond strength, applying TPSEP can serve as a substitute for the conventional method of etch and bond, particularly in orthodontic operations.

  11. Types, risks and market of municipal bonds

    Directory of Open Access Journals (Sweden)

    Grujić Miloš

    2012-01-01

    Full Text Available Municipal bonds are issued by cities, municipalities or other local communities in order to quickly raise funds to cover current budget deficits, finish infrastructure projects for production and distribution of thermal energy, improve water supply, road construction, sports and recreation centers, schools or to fund such projects on more favorable terms than to borrow from banks. In this manner, necessary conditions are created for faster development of the real sector. The aim of this study is to evaluate the importance, possibilities and effects of the bond issue in the Republika Srpska aimed at securing funding for and development of local communities. Good examples that local government bonds enhance community development include capital markets in countries that have made the transition from the socialist system design, similar to the market of the Republika Srpska, like the Polish, Slovakian, Hungarian and Croatian markets. Issues of municipal bonds in the Republika Srpska succeeded mostly due to the workings of Investment-Development Bank of RS. However, it certainly shows that further high-quality municipal bonds could attract more interest from various institutional investors, especially mutual funds and insurance companies, and investors who are more risk-averse will be able to familiarize and inform themselves with the functioning of capital markets. In this manner, our capital market would confirm its essential role and thus become a generator of overall economic development of the Republika Srpska because it would enable more efficient collection and allocation of capital resources.

  12. Binding of reactive organophosphate by oximes via hydrogen bond

    Indian Academy of Sciences (India)

    In this contribution, the ability of simple oximes to bind a well-known nerve agent simulant (dimethylmethylphosphonate, DMMP) via hydrogen bond is reported. UV/Vis measurements indicate the formation of 1:1 complexes. 1H-, 31P-NMR titrations and T-ROESY experiments confirm that oximes bind the organophosphate ...

  13. Humor and Embodied Conversational Agents

    NARCIS (Netherlands)

    Nijholt, Antinus

    This report surveys the role of humor in human-to-human interaction and the possible role of humor in human-computer interaction. The aim is to see whether it is useful for embodied conversational agents to integrate humor capabilities in their internal model of intelligence, emotions and

  14. Shear bond strength of two bonding systems on dentin surfaces prepared with Er:YAG laser

    International Nuclear Information System (INIS)

    Dall'Magro, Eduardo

    2001-01-01

    The purpose of this study was to examine the shear bond strength of two bonding dentin systems, one 'one step' (Single Bond - 3M) and one 'self-etching' (Prompt-L-ESPE), when applied on dentin surfaces prepared with Er:YAG laser (2,94μm) that underwent ar not, acid etched. Forty one human molars just extracted were selected and after the cut with diamond disc and included in acrylic resin, resulting in 81 specimens (hemi crowns). After, the specimens were divided in one group treated with sand paper and another two groups treated with Er:YAG laser with 200 mJ and 250 mJ of energy and 2 Hz of frequency. Next, the prepared surfaces received three treatments with following application: 1) acid + Single Bond + Z 250 resin, 2) prompt-L-Pop + Z 250 resin, and 3) acid without, Single Bond + Z 250 resin. The Z 250 resin was applied and photopolymerized in increments on a Teflon matrix that belonged to an apparatus called 'Assembly Apparatus' machine producing cylinders of 3,5 mm of diameter and 5 mm of height. After these specimens were submitted to thermo cycling during 1 minute the 55 deg C and during 1 minute with 5 deg C with a total of 500 cycles for specimen, and the measures of shear bond strength were abstained using EMIC model DL 2000 rehearsed machine, with speed of 0,5 mm/min, measuring the final rupture tension (Mpa). The results showed an statistic superiority of 5% of probability level in dentin flattened with sandpaper and with laser using 200 mJ of energy with aspect to the ones flattened with laser using 250 mJ of energy. It was observed that using 'Single Bond' bonding dentin system the marks were statistically superior at 5% of probability with reference to the use of the Prompt-L-Pop adhesive system. So, it was concluded that Er:YAG Laser with 200 mJ of energy produced similar dentin cavity prepare than sandpaper and Single Bond seemed the best bonding agent system between restorative material and dentin. (author)

  15. Radioprotective Agents

    Directory of Open Access Journals (Sweden)

    Ilker Kelle

    2008-01-01

    Full Text Available Since1949, a great deal of research has been carried out on the radioprotective activity of various chemical substances. Thiol compounds, compounds which contain –SH radical, different classes of pharmacological agents and other compounds such as vitamine C and WR-2721 have been shown to reduce mortality when administered prior to exposure to a lethal dose of radiation. Recently, honey bee venom as well as that of its components melittin and histamine have shown to be valuable in reduction of radiation-induced damage and also provide prophylactic alternative treatment for serious side effects related with radiotherapy. It has been suggested that the radioprotective activity of bee venom components is related with the stimulation of the hematopoetic system.

  16. Why are Hydrogen Bonds Directional?

    Indian Academy of Sciences (India)

    century and most chemists appear to think of 'chemi- cal bond' as ..... These complexes, in their global min- ima, have ... taneously act as hydrogen bond donor and acceptor displaying ... also has a local minimum, which is linear and similar to.

  17. Regioselectivity in the Reductive Bond Cleavage of Diarylalkylsulfonium Salts

    DEFF Research Database (Denmark)

    Kampmeier, Jack; Mansurul Hoque, AKM; D. Saeva, Franklin

    2009-01-01

    products vary from regiospecific alkyl cleavage to predominant aryl cleavage as a function of the potential of the reducing agent. We conclude that differences between the reductive cleavages of mono- and diarylsulfonium salts are direct consequences of the structures of the sulfuranyl radical......- tolylethylsulfonium and di-4-tolyl-2-phenylethylsulfonium salts by a variety of one-electron reducing agents ranging in potential from -0.77 to +2.5 eV (vs SCE) and including thermal reductants, indirect electrolyses mediated by a series of cyanoaromatics, and excited singlet states. We report that the cleavage...... intermediates and the bond dissociation energies of the alkyl and aryl bonds. Competitions between the rates of cleavage and oxidation of the intermediate sulfuranyl radicals and between concerted and stepwise mechanisms are discussed to explain the variations in bond cleavage products as a function...

  18. Bond yield curve construction

    Directory of Open Access Journals (Sweden)

    Kožul Nataša

    2014-01-01

    Full Text Available In the broadest sense, yield curve indicates the market's view of the evolution of interest rates over time. However, given that cost of borrowing it closely linked to creditworthiness (ability to repay, different yield curves will apply to different currencies, market sectors, or even individual issuers. As government borrowing is indicative of interest rate levels available to other market players in a particular country, and considering that bond issuance still remains the dominant form of sovereign debt, this paper describes yield curve construction using bonds. The relationship between zero-coupon yield, par yield and yield to maturity is given and their usage in determining curve discount factors is described. Their usage in deriving forward rates and pricing related derivative instruments is also discussed.

  19. Corporate Hybrid Bonds

    OpenAIRE

    Ahlberg, Johan; Jansson, Anton

    2016-01-01

    Hybrid securities do not constitute a new phenomenon in the Swedish capital markets. Most commonly, hybrids issued by Swedish real estate companies in recent years are preference shares. Corporate hybrid bonds on the other hand may be considered as somewhat of a new-born child in the family of hybrid instruments. These do, as all other hybrid securities, share some equity-like and some debt-like characteristics. Nevertheless, since 2013 the interest for the instrument has grown rapidly and ha...

  20. Hybrid Cat Bonds

    OpenAIRE

    Barrieu, Pauline; Louberge, Henri

    2009-01-01

    Natural catastrophes attract regularly the attention of media and have become a source of public concern. From a financial viewpoint, natural catastrophes represent idiosyncratic risks, diversifiable at the world level. But for reasons analyzed in this paper reinsurance markets are unable to cope with this risk completely. Insurance-linked securities, such as cat bonds, have been issued to complete the international risk transfer process, but their development is disappointing so far. This pa...

  1. Effect of Two-minute Application of 35% Sodium Ascorbate on Composite Bond Strength following Bleaching.

    Science.gov (United States)

    Ismail, Eman H; Kilinc, Evren; Hardigan, Patrick C; Rothrock, James K; Thompson, Jeffrey Y; Garcia-Godoy, Cristina

    2017-10-01

    The aim of this study is to assess the effect of 35% sodium ascorbate on microtensile bond strength of dentin immediately after bleaching with 35% hydrogen peroxide. A total of 25 sound human 3 rd molars were collected. Teeth were randomly divided into five groups for different treatments: Group I [bleaching + immediate bonding (i.e., restoration)], group II (bleaching + delayed bonding), group III (bleaching + sodium ascorbate + immediate bonding), group IV (bleaching + sodium ascorbate + delayed bonding), and group V (bonding only). After bleaching, but before bonding, groups II and IV were stored for 1 week in deionized water at 37°C. All samples were bonded using OptiBoned FL (Kerr) and Filtek Supreme (3M/ESPE). Teeth were sectioned into 1 × 1 mm 2 bars, and microtensile bond strength was tested with a universal testing machine (Instron 8841) at a cross-head speed of 0.5 mm/minute. Microtensile bond strength differed significantly across the five groups, with a significant reduction in microtensile bond strength observed for samples in group I relative to samples in any of the other treatment groups (p bleaching on composite bonding strength to dentin. The negative effects of bleaching on composite bonding can be neutralized by the application of the reversing agent sodium ascorbate thus, increasing the efficiency of clinic chair time. This is clinically relevant for those patients requiring restorative treatment immediately after in-office bleaching.

  2. Solute's perspective on how trimethylamine oxide, urea, and guanidine hydrochloride affect water's hydrogen bonding ability.

    Science.gov (United States)

    Pazos, Ileana M; Gai, Feng

    2012-10-18

    While the thermodynamic effects of trimethylamine oxide (TMAO), urea, and guanidine hydrochloride (GdnHCl) on protein stability are well understood, the underlying mechanisms of action are less well characterized and, in some cases, even under debate. Herein, we employ the stretching vibration of two infrared (IR) reporters, i.e., nitrile (C≡N) and carbonyl (C═O), to directly probe how these cosolvents mediate the ability of water to form hydrogen bonds with the solute of interest, e.g., a peptide. Our results show that these three agents, despite having different effects on protein stability, all act to decrease the strength of the hydrogen bonds formed between water and the infrared probe. While the behavior of TMAO appears to be consistent with its protein-protecting ability, those of urea and GdnHCl are inconsistent with their role as protein denaturants. The latter is of particular interest as it provides strong evidence indicating that although urea and GdnHCl can perturb the hydrogen-bonding property of water their protein-denaturing ability does not arise from a simple indirect mechanism.

  3. Effect of universal adhesive etching modes on bond strength to dual-polymerizing composite resins.

    Science.gov (United States)

    Michaud, Pierre-Luc; Brown, Matthew

    2018-04-01

    Information is lacking as to the effect on bond strength of the etching modes of universal adhesives when they are used to bond dual-polymerizing composite resins to dentin. The purpose of this in vitro study was to investigate the bonding of dual-polymerizing foundation composite resins to dentin when universal bonding agents are used in self-etch or etch-and-rinse modes. Sixty caries-free, extracted third molar teeth were sectioned transversely in the apical third of the crown and allocated to 12 groups (n=5). Three different bonding agents (Scotchbond Universal, OptiBond XTR, All-Bond Universal) were used to bond 2 different dual-polymerizing composite resins (CompCore AF or CoreFlo DC) to dentin, using 2 different etching approaches (etch-and-rinse or self-etch). The specimens were sectioned into sticks (1×1×8 mm) with a precision saw. The bond strength of the specimens was tested under microtensile force at a crosshead speed of 0.5 mm/min. The data were analyzed using a 3-way ANOVA, a Games-Howell post hoc comparisons model, and Student t tests with Bonferroni corrections (α=.05). In the overall model, the composite resin used had no effect on bond strength (P=.830). The etching protocol by itself also did not have a significant effect (P=.059), although a trend was present. The bonding agent, however, did have an effect (Pcomposite resins to dentin, no single etching protocol is better than another. Depending on which bonding agent is being used, one etching mode may perform better. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  4. 46 CFR Sec. 10 - Bonds.

    Science.gov (United States)

    2010-10-01

    ... REPAIRS UNDER NATIONAL SHIPPING AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 10 Bonds. (a... awarded work and the furnishing of the performance and payment bonds required by Article 14 of the NSA... of the NSA-LUMPSUMREP Contract, the standard form of individual performance bond (Standard Form 25...

  5. Post-bleaching application of an antioxidant on dentin bond strength of three dental adhesives

    Directory of Open Access Journals (Sweden)

    Maryam Khoroushi

    2012-01-01

    Conclusions: The findings suggest that bond strength of resin to bleached dentin may be affected with the adhesive system. Reduced SBS to bleached dentin can be amended by the use of SA as an antioxidizing agent. However, the amount of reversed bond strength subsequent to applying antioxidant might be related to the kind of dental adhesive.

  6. The chemical bond in inorganic chemistry the bond valence model

    CERN Document Server

    Brown, I David

    2016-01-01

    The bond valence model is a version of the ionic model in which the chemical constraints are expressed in terms of localized chemical bonds formed by the valence charge of the atoms. Theorems derived from the properties of the electrostatic flux predict the rules obeyed by both ionic and covalent bonds. They make quantitative predictions of coordination number, crystal structure, bond lengths and bond angles. Bond stability depends on the matching of the bonding strengths of the atoms, while the conflicting requirements of chemistry and space lead to the structural instabilities responsible for the unusual physical properties displayed by some materials. The model has applications in many fields ranging from mineralogy to molecular biology.

  7. The role of lipid and carbohydrate digestive enzyme inhibitors in the management of obesity: a review of current and emerging therapeutic agents

    Directory of Open Access Journals (Sweden)

    Tucci S

    2010-05-01

    Full Text Available Sonia A Tucci, Emma J Boyland, Jason CG HalfordKissileff Laboratory for the Study of Human Ingestive Behaviour, School of Psychology, University of Liverpool, Liverpool, UKAbstract: Obesity is a global epidemic associated with significant morbidity and mortality in adults and ill health in children. A proven successful approach in weight management has been the disruption of nutrient digestion, with orlistat having been used to treat obesity for the last 10 years. Although orlistat-induced weight loss remains modest, it produces meaningful reductions in risk factors for obesity-related conditions such as diabetes and cardiovascular disease. Moreover, this lipase inhibitor is free of the serious side effects that have dogged appetite-suppressing drugs. This success had driven investigation into new generation nutraceuticals, supplements and pharmaceutical agents that inhibit the breakdown of complex carbohydrates and fats within the gut. This review focuses on agents purported to inhibit intestinal enzymes responsible for macronutrient digestion. Except for some synthetic products, the majority of agents reviewed are either botanical extracts or bacterial products. Currently, carbohydrate digestion inhibitors are under development to improve glycemic control and these may also induce some weight loss. However, colonic fermentation induced side effects, such as excess gas production, remain an issue for these compounds. The α-glucosidase inhibitor acarbose, and the α-amylase inhibitor phaseolamine, have been used in humans with some promising results relating to weight loss. Nonetheless, few of these agents have made it into clinical studies and without any clinical proof of concept or proven efficacy it is unlikely any will enter the market soon.Keywords: lipase, amylase, saccharidases, overweight, orlistat, Alli®, digestion, body weight

  8. Quantum Devices Bonded Beneath a Superconducting Shield: Part 2

    Science.gov (United States)

    McRae, Corey Rae; Abdallah, Adel; Bejanin, Jeremy; Earnest, Carolyn; McConkey, Thomas; Pagel, Zachary; Mariantoni, Matteo

    The next-generation quantum computer will rely on physical quantum bits (qubits) organized into arrays to form error-robust logical qubits. In the superconducting quantum circuit implementation, this architecture will require the use of larger and larger chip sizes. In order for on-chip superconducting quantum computers to be scalable, various issues found in large chips must be addressed, including the suppression of box modes (due to the sample holder) and the suppression of slot modes (due to fractured ground planes). By bonding a metallized shield layer over a superconducting circuit using thin-film indium as a bonding agent, we have demonstrated proof of concept of an extensible circuit architecture that holds the key to the suppression of spurious modes. Microwave characterization of shielded transmission lines and measurement of superconducting resonators were compared to identical unshielded devices. The elimination of box modes was investigated, as well as bond characteristics including bond homogeneity and the presence of a superconducting connection.

  9. Targeting Bacterial Dsb Proteins for the Development of Anti-Virulence Agents

    Directory of Open Access Journals (Sweden)

    Roxanne P. Smith

    2016-07-01

    Full Text Available Recent years have witnessed a dramatic increase in bacterial antimicrobial resistance and a decline in the development of novel antibiotics. New therapeutic strategies are urgently needed to combat the growing threat posed by multidrug resistant bacterial infections. The Dsb disulfide bond forming pathways are potential targets for the development of antimicrobial agents because they play a central role in bacterial pathogenesis. In particular, the DsbA/DsbB system catalyses disulfide bond formation in a wide array of virulence factors, which are essential for many pathogens to establish infections and cause disease. These redox enzymes are well placed as antimicrobial targets because they are taxonomically widespread, share low sequence identity with human proteins, and many years of basic research have provided a deep molecular understanding of these systems in bacteria. In this review, we discuss disulfide bond catalytic pathways in bacteria and their significance in pathogenesis. We also review the use of different approaches to develop inhibitors against Dsb proteins as potential anti-virulence agents, including fragment-based drug discovery, high-throughput screening and other structure-based drug discovery methods.

  10. Radiological and physiological studies on the role of some therapeutic agents used for internal decontamination of radionuclides from male albino rats

    International Nuclear Information System (INIS)

    Mangood, S.A.

    2008-01-01

    With the earths increasing nuclear arsenal and the growing use of nuclear energy, the possibility of radiological accidents involving release of radioactive materials, internal contamination may consequently occurs via inhalation, ingestion or absorption of radioisotopes.Therefore, the present work was oriented to deal with four topics related to the internal decontamination of two of the most widely used isotopes, namely 134 Cs and 60 Co from contaminated rats:-In vitro study aimed to select agents that can strongly bind the two metal ions and elucidate the best conditions and the factors affecting this binding. The tested agents were bentonite, vermiculite and Prussian blue (PB). The sorption capacity of PB and vermiculite for both metal ions was high and equivalent to more than 10 11 Bq 137 Cs or 60 Co per gram sorbent. As bentonite has lower capacity to both isotopes, further in vivo experiments were performed with PB and vermiculite.-In vivo studies, via 5 groups of rats, devoted to investigate the kinetics of excretion of 134 Cs and/or 60 Co from contaminated rats. The biological half lives of excretion, excretion stages for both isotopes and the effect of route of entry on the excretion were estimated.-In vivo studies aimed to investigate the effectiveness of PB + vermiculite and CaDTPA as therapeutic agents for accelerating the elimination of 134 Cs and/or 60 Co from contaminated rats. The study was performed via 6 groups of rats given different regimes of therapy. The results showed the high efficiency of PB + vermiculite for accelerating elimination of 134 Cs and orally administrated 60 Co while CaDTPA succeeded in accelerating intraperitoneally administrated 60 Co. The study proved that oral administration of PB + vermiculite and injection with CaDTPA at the same time is very effective in accelerating elimination of both contaminants simultaneously.-The physiological studies aimed to evaluate the hazardous effects of 134 Cs and/or 60 Co incorporation and

  11. Hydrogen bonding in ionic liquids.

    Science.gov (United States)

    Hunt, Patricia A; Ashworth, Claire R; Matthews, Richard P

    2015-03-07

    Ionic liquids (IL) and hydrogen bonding (H-bonding) are two diverse fields for which there is a developing recognition of significant overlap. Doubly ionic H-bonds occur when a H-bond forms between a cation and anion, and are a key feature of ILs. Doubly ionic H-bonds represent a wide area of H-bonding which has yet to be fully recognised, characterised or explored. H-bonds in ILs (both protic and aprotic) are bifurcated and chelating, and unlike many molecular liquids a significant variety of distinct H-bonds are formed between different types and numbers of donor and acceptor sites within a given IL. Traditional more neutral H-bonds can also be formed in functionalised ILs, adding a further level of complexity. Ab initio computed parameters; association energies, partial charges, density descriptors as encompassed by the QTAIM methodology (ρBCP), qualitative molecular orbital theory and NBO analysis provide established and robust mechanisms for understanding and interpreting traditional neutral and ionic H-bonds. In this review the applicability and extension of these parameters to describe and quantify the doubly ionic H-bond has been explored. Estimating the H-bonding energy is difficult because at a fundamental level the H-bond and ionic interaction are coupled. The NBO and QTAIM methodologies, unlike the total energy, are local descriptors and therefore can be used to directly compare neutral, ionic and doubly ionic H-bonds. The charged nature of the ions influences the ionic characteristics of the H-bond and vice versa, in addition the close association of the ions leads to enhanced orbital overlap and covalent contributions. The charge on the ions raises the energy of the Ylp and lowers the energy of the X-H σ* NBOs resulting in greater charge transfer, strengthening the H-bond. Using this range of parameters and comparing doubly ionic H-bonds to more traditional neutral and ionic H-bonds it is clear that doubly ionic H-bonds cover the full range of weak

  12. Immunological effects of hypomethylating agents.

    Science.gov (United States)

    Lindblad, Katherine E; Goswami, Meghali; Hourigan, Christopher S; Oetjen, Karolyn A

    2017-08-01

    Epigenetic changes resulting from aberrant methylation patterns are a recurrent observation in hematologic malignancies. Hypomethylating agents have a well-established role in the management of patients with high-risk myelodysplastic syndrome or acute myeloid leukemia. In addition to the direct effects of hypomethylating agents on cancer cells, there are several lines of evidence indicating a role for immune-mediated anti-tumor benefits from hypomethylating therapy. Areas covered: We reviewed the clinical and basic science literature for the effects of hypomethylating agents, including the most commonly utilized therapeutics azacitidine and decitabine, on immune cell subsets. We summarized the effects of hypomethylating agents on the frequency and function of natural killer cells, T cells, and dendritic cells. In particular, we highlight the effects of hypomethylating agents on expression of immune checkpoint inhibitors, leukemia-associated antigens, and endogenous retroviral elements. Expert commentary: In vitro and ex vivo studies indicate mixed effects on the function of natural killer, dendritic cells and T cells following treatment with hypomethylating agents. Clinical correlates of immune function have suggested that hypomethylating agents have immunomodulatory functions with the potential to synergize with immune checkpoint therapy for the treatment of hematologic malignancy, and has become an active area of clinical research.

  13. Effects of tacky mat contamination on bond degradation for Chemlok/liner and NBR/liner bonds

    Science.gov (United States)

    Padilla, A. M.

    1989-01-01

    Tacky mats are placed by the rubber lay-up areas for the solid rocket motor segments. These mats dust off the shoes prior to entering the platform where the lay-up work is performed. The possibility exists that a tacky mat could be touched with gloved hands prior to handling the uncured nitride butadiene rubber (NBR). Tests were run to determine if NBR were accidentally touched would there be any degradation of the liner/NBR bond. The tacky mats were judged solely on the basis of bond degradation caused by either direct or indirect contamination. Test results all indicate that there was no notable NBR/Chemlok or liner/NBR bond degradation on samples that came into contact with the tacky mat material. Testing procedures are described. The tacky mat adhesive composition does not contain fluorocarbons or release agents that would affect bonding.

  14. Additional disulfide bonds in insulin

    DEFF Research Database (Denmark)

    Vinther, Tine N; Pettersson, Ingrid; Huus, Kasper

    2015-01-01

    The structure of insulin, a glucose homeostasis-controlling hormone, is highly conserved in all vertebrates and stabilized by three disulfide bonds. Recently, we designed a novel insulin analogue containing a fourth disulfide bond located between positions A10-B4. The N-terminus of insulin's B......-chain is flexible and can adapt multiple conformations. We examined how well disulfide bond predictions algorithms could identify disulfide bonds in this region of insulin. In order to identify stable insulin analogues with additional disulfide bonds, which could be expressed, the Cβ cut-off distance had...... in comparison to analogues with additional disulfide bonds that were more difficult to predict. In contrast, addition of the fourth disulfide bond rendered all analogues resistant to fibrillation under stress conditions and all stable analogues bound to the insulin receptor with picomolar affinities. Thus...

  15. Crystal growth vs. conventional acid etching: A comparative evaluation of etch patterns, penetration depths, and bond strengths

    Directory of Open Access Journals (Sweden)

    Devanna Raghu

    2008-01-01

    Full Text Available The present study was undertaken to investigate the effect on enamel surface, penetration depth, and bond strength produced by 37% phosphoric acid and 20% sulfated polyacrylic acid as etching agents for direct bonding. Eighty teeth were used to study the efficacy of the etching agents on the enamel surface, penetration depth, and tensile bond strength. It was determined from the present study that a 30 sec application of 20% sulfated polyacrylic acid produced comparable etching topography with that of 37% phosphoric acid applied for 30 sec. The 37% phosphoric acid dissolves enamel to a greater extent than does the 20% sulfated polyacrylic acid. Instron Universal testing machine was used to evaluate the bond strengths of the two etching agents. Twenty percent sulfated polyacrylic acid provided adequate tensile bond strength. It was ascertained that crystal growth can be an alternative to conventional phosphoric acid etching as it dissolves lesser enamel and provides adequate tensile bond strength.

  16. Shear bond strength of resin composite bonded with two adhesives: Influence of Er: YAG laser irradiation distance

    Science.gov (United States)

    Shirani, Farzaneh; Birang, Reza; Malekipour, Mohammad Reza; Hourmehr, Zahra; Kazemi, Shantia

    2014-01-01

    Background: Dental surfaces prepared with different Er:YAG laser distance may have different characteristics compared with those prepared with conventional instruments. The aim of this study was to investigate the effect of Er:YAG laser irradiation distance from enamel and dentin surfaces on the shear bond strength of composite with self-etch and etch and rinse bonding systems compared with conventional preparation method. Materials and Methods: Two hundred caries-free human third molars were randomly divided into twenty groups (n = 10). Ten groups were designated for enamel surface (E1-E10) and ten for dentin surface (D1-D10). Er: YAG laser (2940 nm) was used on the E1-E8 (240 mJ, 25 Hz) and D1-D8 (140 mJ, 30 Hz) groups at four different distances of 0.5 (standard), 2, 4 and 11 mm. Control groups (E9, E10, D9 and D10) were ground with medium grit diamond bur. The enamel and dentin specimens were divided into two subgroups that were bonded with either Single Bond or Clearfil SE Bond. Resin composite (Z100) was dispensed on prepared dentin and enamel. The shear bond strengths were tested using a universal testing machine. Data were analyzed by SPSS12 statistical software using three way analysis of variance, Tukey and independent t-test. P enamel and dentin substrates (P enamel surfaces (in both bonding agent subgroups) and on dentin surfaces (in the Single Bond subgroup). Conclusion: Laser irradiation decreases shear bond strength. Irradiation distance affects shear bond strength and increasing the distance would decrease the negative effects of laser irradiation. PMID:25540665

  17. Effect of moisture and drying time on the bond strength of the one-step self-etching adhesive system

    Directory of Open Access Journals (Sweden)

    Yoon Lee

    2012-08-01

    Full Text Available Objectives To investigate the effect of dentin moisture degree and air-drying time on dentin-bond strength of two different one-step self-etching adhesive systems. Materials and Methods Twenty-four human third molars were used for microtensile bond strength testing of G-Bond and Clearfil S3 Bond. The dentin surface was either blot-dried or air-dried before applying these adhesive agents. After application of the adhesive agent, three different air drying times were evaluated: 1, 5, and 10 sec. Composite resin was build up to 4 mm thickness and light cured for 40 sec with 2 separate layers. Then the tooth was sectioned and trimmed to measure the microtensile bond strength using a universal testing machine. The measured bond strengths were analyzed with three-way ANOVA and regression analysis was done (p = 0.05. Results All three factors, materials, dentin wetness and air drying time, showed significant effect on the microtensile bond strength. Clearfil S3 Bond, dry dentin surface and 10 sec air drying time showed higher bond strength. Conclusions Within the limitation of this experiment, air drying time after the application of the one-step self-etching adhesive agent was the most significant factor affecting the bond strength, followed by the material difference and dentin moisture before applying the adhesive agent.

  18. Comparative Evaluation of shear Bond Strength of universal Dental Adhesives -An in vitro study.

    Science.gov (United States)

    Jayasheel, Arun; Niranjan, Nandini; Pamidi, Hemanthkumar; Suryakanth, Mayuri B

    2017-07-01

    Patient demand for tooth colored restorations and desire for minimally invasive restorations have made composites an indispensable part of the restorative process. An important factor affecting the intra-oral performance of composite restorations is bonding. Ninty six freshly extracted molar teeth were collected and occlusal 3mm is removed using a diamond disc to expose dentine. Following with samples were divided in to two main groups (self-etch & total etch). Each main group is again sub divided in to three groups each according to bonding agent used (Tetric N- Bond Universal, Single Bond Universal, Tetric N Bond Total etch in total etch group and Clear Fill SE in self etch group). Following which bonding protocol is followed according to manufacture instructions, a composite buildup of 2x3 mm is done on each specimen and then specimen were subjected to shear bond test under universal testing machine. All the readings were noted and subjected to statistical analysis using One way ANOVA and Tukey's posthoc test. It showed that there is no significant difference among the groups in both self-etch and total etch modes. It can be concluded that application of an etching step prior to Universal Adhesives significantly improves their dentine penetration pattern, although this does not affect their mean SBS. The bond strength values of the TBU regardless of application mode were comparable to SBU making them reliable for working under different clinical conditions. Key words: Dentine bonding agents, self-etch mode, total etch mode, shear bond strength.

  19. An agent-based simulation of persistent inequalities in health behavior: Understanding the interdependent roles of segregation, clustering, and social influence.

    Science.gov (United States)

    Langellier, Brent A

    2016-12-01

    Health inequalities are conspicuously persistent through time and often durable even in spite of interventions. In this study, I use agent-based simulation models (ABMs) to understand how the complex interrelationships between residential segregation, social network formation, group-level preferences, and social influence may contribute to this persistence. I use a more-stylized ABM, Bubblegum Village (BV), to understand how initial inequalities in bubblegum-chewing behaviors either endure, increase, or decrease over time given group-level differences in preferences, neighborhood-level barriers or facilitators of bubblegum chewing (e.g., access to bubblegum shops), and agents' preferences for segregation, homophily, and clustering (i.e., the 'tightness' of social networks). I further use BV to understand whether segregation and social network characteristics impact whether the effects of a bubblegum-reduction intervention that is very effective in the short term are durable over time, as well as to identify intervention strategies to reduce attenuation of the intervention effects. In addition to BV, I also present results from an ABM based on the distribution and social characteristics of the population in Philadelphia, PA. This model explores similar questions to BV, but examines racial/ethnic inequalities in soda consumption based on agents' social characteristics and baseline soda consumption probabilities informed by the 2007-2010 National Health and Nutrition Examination Survey. Collectively, the models suggest that residential segregation is a fundamental process for the production and persistence of health inequalities. The other major conclusion of the study is that, for behaviors that are subject to social influence and that cluster within social groups, interventions that are randomly-targeted to individuals with 'bad' behaviors will likely experience a large degree of recidivism to pre-intervention behaviors. In contrast, interventions that target

  20. Effect of Nanofiller Addition to an Experimental Dentin Adhesive on Microtensile Bond Strength to Human Dentin

    Directory of Open Access Journals (Sweden)

    SH. Kasraei

    2009-06-01

    Full Text Available Objective: The purpose of the study was to evaluate the influence of adding nanofiller particles to a dentin bonding agent on resin-dentin bond strength.Materials and Methods: Fifty-four human intact premolar teeth were divided in to 6 groups of nine. The teeth were ground on occlusal surfaces and polished with 320 and then 600 grit silicon carbide papers. An experimental bonding system based on acetone/alcoholsolvent was provided with filler contents of 0.0, 0.5, 1.0, 2.5, 5.0, and 10.0 weight percent fumed silica nanofiller. After dentin surface etching, rinsing and blot drying, the experimentalbonding agents were applied to dentin surface. A composite resin was, then,bonded to the dentin on the bonding agent. The specimens were thermocycled for 500 cycles and sectioned in stick form. After two week of storage in distilled water, resin-dentin microtensile bond strength of the specimens was measured. Data were analyzed by one way ANOVA and DunnettT3 tests.Results: Bond strength to dentin was significantly affected by the filler level. Minimum and maximum resin-microtensile bond strength was in the experimental bonding agent with no filler (5.88 MPa and with filler level of 1.0 weight percent (15.15 MPa, respectively,and decreased with the increase of filler content down to 8.95 MPa for the filler level of 10.0 weight percent.Conclusion: Filler content seems to be one of the important factors influencing the bond strength of dental adhesives. Maximum dentin bond strength was obtained with 1% silanized nanofiller silica added to experimental adhesive system.

  1. Complex responses to alkylating agents

    International Nuclear Information System (INIS)

    Samson, L.D.

    2003-01-01

    Using Affymetrix oligonucleotide GeneChip analysis, we previously found that, upon exposure to the simple alkylating agent methylmethane sulfonate, the transcript levels for about one third of the Saccharomyces cerevisiae genome (∼2,000 transcripts) are induced or repressed during the first hour or two after exposure. In order to determine whether the responsiveness of these genes has any relevance to the protection of cells against alkylating agents we have undertaken several follow-up studies. First, we explored the specificity of this global transcriptional response to MMS by measuring the global response of S. cerevisiae to a broad range of agents that are known to induce DNA damage. We found that each agent produced a very different mRNA transcript profile, even though the exposure doses produced similar levels of toxicity. We also found that the selection of genes that respond to MMS is highly dependent upon what cell cycle phase the cells are in at the time of exposure. Computational clustering analysis of the dataset derived from a large number of exposures identified several promoter motifs that are likely to control some of the regulons that comprise this large set of genes that are responsive to DNA damaging agents. However, it should be noted that these agents damage cellular components other than DNA, and that the responsiveness of each gene need not be in response to DNA damage per se. We have also begun to study the response of other organisms to alkylating agents, and these include E. coli, cultured mouse and human cells, and mice. Finally, we have developed a high throughput phenotypic screening method to interrogate the role of all non-essential S. cerevisiae genes (about 4,800) in protecting S. cerevisiae against the deleterious effects of alkylating agents; we have termed this analysis 'genomic phenotyping'. This study has uncovered a plethora of new pathways that play a role in the recovery of eukaryotic cells after exposure to toxic

  2. Citrate-Induced Nanocubes: A Re-Examination of the Role of Citrate as a Shape-Directing Capping Agent for Ag-Based Nanostructures.

    Science.gov (United States)

    Hajfathalian, Maryam; Gilroy, Kyle D; Hughes, Robert A; Neretina, Svetlana

    2016-07-01

    Seed-mediated syntheses utilizing facet-selective surface passivation provide the necessary chemical controls to direct noble metal nanostructure formation to a predetermined geometry. The foremost protocol for the synthesis of (111)-faceted Ag octahedra involves the reduction of metal ions onto pre-existing seeds in the presence of citrate and ascorbic acid. It is generally accepted that the capping of (111) facets with citrate dictates the shape while ascorbic acid acts solely as the reducing agent. Herein, a citrate-based synthesis is demonstrated in which the presence or absence of ascorbic acid is the shape-determining factor. Reactions are carried out in which Ag(+) ions are reduced onto substrate-immobilized Ag, Au, Pd, and Pt seeds. Syntheses lacking ascorbic acid, in which citrate acts as both the capping and the reducing agent, result in a robust nanocube growth mode able to withstand wide variations in the concentration of reactants, reaction rates, seed material, seed orientation and faceting, pH, and substrate material. If, however, ascorbic acid is included in these syntheses, then the growth mode reverts to one that advances the octahedral geometry. The implication of these results is that citrate, or one of its oxidation products, selectively caps (100) facets, but where this capability is compromised by ascorbic acid. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Macroeconomic Stability in a Model with Bond Transaction Services

    Directory of Open Access Journals (Sweden)

    Massimiliano Marzo

    2018-02-01

    Full Text Available Cochrane (2014 shows that high-powered money balances and short-term government bonds can be considered as perfect substitutes for the U.S economy during the past twenty years. We build on this claim and consider a variant of the standard cashless new-Keynesian model with two types of government bonds, which can be thought of as short- and long-term bonds. The first one has a macroeconomic role in the sense that it provides transaction services in addition to generating a yield. The other type of government bond pays only an interest rate. Consistent with previous findings, the Taylor principle is not a panacea for equilibrium determinacy in a model without money. When the government bond market matters beyond the need for fiscal solvency, monetary policy rules do not need to comply with the Taylor principle for unique equilibria to exist.

  4. Time varying determinants of bond flows to emerging markets

    Directory of Open Access Journals (Sweden)

    Yasemin Erduman

    2016-06-01

    Full Text Available This paper investigates the time varying nature of the determinants of bond flows with a focus on the global financial crisis period. We estimate a time varying regression model using Bayesian estimation methods, where the posterior distribution is approximated by Gibbs sampling algorithm. Our findings suggest that the interest rate differential is the most significant pull factor of portfolio bond flows, along with the inflation rate, while the growth rate does not play a significant role. Among the push factors, global liquidity is the most important driver of bond flows. It matters the most, when unconventional monetary easing policies were first announced; and its importance as a determinant of portfolio bond flows decreases over time, starting with the Eurozone crisis, and diminishes with the tapering talk. Global risk appetite and the risk perception towards the emerging countries also have relatively small and stable significant effects on bond flows.

  5. Elucidating bonding preferences in tetrakis(imido)uranate(VI) dianions

    Science.gov (United States)

    Anderson, Nickolas H.; Xie, Jing; Ray, Debmalya; Zeller, Matthias; Gagliardi, Laura; Bart, Suzanne C.

    2017-09-01

    Actinyl species, [AnO2]2+, are well-known derivatives of the f-block because of their natural occurrence and essential roles in the nuclear fuel cycle. Along with their nitrogen analogues, [An(NR)2]2+, actinyls are characterized by their two strong trans-An-element multiple bonds, a consequence of the inverse trans influence. We report that these robust bonds can be weakened significantly by increasing the number of multiple bonds to uranium, as demonstrated by a family of uranium(VI) dianions bearing four U-N multiple bonds, [M]2[U(NR)4] (M = Li, Na, K, Rb, Cs). Their geometry is dictated by cation coordination and sterics rather than by electronic factors. Multiple bond weakening by the addition of strong π donors has the potential for applications in the processing of high-valent actinyls, commonly found in environmental pollutants and spent nuclear fuels.

  6. Controllable synthesis of silver and silver sulfide nanocrystals via selective cleavage of chemical bonds

    International Nuclear Information System (INIS)

    Tang Aiwei; Wang Yu; Ye Haihang; Zhou Chao; Yang Chunhe; Li Xu; Peng Hongshang; Zhang Fujun; Hou Yanbing; Teng Feng

    2013-01-01

    A one-step colloidal process has been adopted to prepare silver (Ag) and silver sulfide (Ag 2 S) nanocrystals, thus avoiding presynthesis of an organometallic precursor and the injection of a toxic phosphine agent. During the reaction, a layered intermediate compound is first formed, which then acts as a precursor, decomposing into the nanocrystals. The composition of the as-obtained products can be controlled by selective cleavage of S–C bonds or Ag–S bonds. Pure Ag 2 S nanocrystals can be obtained by directly heating silver acetate (Ag(OAc)) and n-dodecanethiol (DDT) at 200 ° C without any surfactant, and pure Ag nanocrystals can be synthesized successfully if the reaction temperature is reduced to 190 ° C and the amount of DDT is decreased to 1 ml in the presence of a non-coordinating organic solvent (1-octadecene, ODE). Otherwise, the mixture of Ag and Ag 2 S is obtained by directly heating Ag(OAc) in DDT by increasing the reaction temperature or in a mixture of DDT and ODE at 200 ° C. The formation mechanism has been discussed in detail in terms of selective S–C and Ag–S bond dissociation due to the nucleophilic attack of DDT and the lower bonding energy of Ag–S. Interestingly, some products can easily self-assemble into two- or three-dimensional (2D or 3D) highly ordered superlattice structures on a copper grid without any additional steps. The excess DDT plays a key role in the superlattice structure due to the bundling and interdigitation of the thiolate molecules adsorbed on the as-obtained nanocrystals. (paper)

  7. Dentine bond strength and antimicrobial activity evaluation of adhesive systems.

    Science.gov (United States)

    André, Carolina Bosso; Gomes, Brenda Paula Figueiredo Almeida; Duque, Thais Mageste; Stipp, Rafael Nobrega; Chan, Daniel Chi Ngai; Ambrosano, Glaucia Maria Bovi; Giannini, Marcelo

    2015-04-01

    This study evaluated the dentine bond strength (BS) and the antibacterial activity (AA) of six adhesives against strict anaerobic and facultative bacteria. Three adhesives containing antibacterial components (Gluma 2Bond (glutaraldehyde)/G2B, Clearfil SE Protect (MDPB)/CSP and Peak Universal Bond (PUB)/chlorhexidine) and the same adhesive versions without antibacterial agents (Gluma Comfort Bond/GCB, Clearfil SE Bond/CSB and Peak LC Bond/PLB) were tested. The AA of adhesives and control groups was evaluated by direct contact method against four strict anaerobic and four facultative bacteria. After incubation, according to the appropriate periods of time for each microorganism, the time to kill microorganisms was measured. For BS, the adhesives were applied according to manufacturers' recommendations and teeth restored with composite. Teeth (n=10) were sectioned to obtain bonded beams specimens, which were tested after artificial saliva storage for one week and one year. BS data were analyzed using two-way ANOVA and Tukey test. Saliva storage for one year reduces the BS only for GCB. In general G2B and GCB required at least 24h for killing microorganisms. PUB and PLB killed only strict anaerobic microorganisms after 24h. For CSP the average time to eliminate the Streptococcus mutans and strict anaerobic oral pathogens was 30 min. CSB showed no AA against facultative bacteria, but had AA against some strict anaerobic microorganisms. Storage time had no effect on the BS for most of the adhesives. The time required to kill bacteria depended on the type of adhesive and never was less than 10 min. Most of the adhesives showed stable bond strength after one year and the Clearfil SE Protect may be a good alternative in restorative procedures performed on dentine, considering its adequate bond strength and better antibacterial activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Modeling of direct wafer bonding: Effect of wafer bow and etch patterns

    Science.gov (United States)

    Turner, K. T.; Spearing, S. M.

    2002-12-01

    Direct wafer bonding is an important technology for the manufacture of silicon-on-insulator substrates and microelectromechanical systems. As devices become more complex and require the bonding of multiple patterned wafers, there is a need to understand the mechanics of the bonding process. A general bonding criterion based on the competition between the strain energy accumulated in the wafers and the surface energy that is dissipated as the bond front advances is developed. The bonding criterion is used to examine the case of bonding bowed wafers. An analytical expression for the strain energy accumulation rate, which is the quantity that controls bonding, and the final curvature of a bonded stack is developed. It is demonstrated that the thickness of the wafers plays a large role and bonding success is independent of wafer diameter. The analytical results are verified through a finite element model and a general method for implementing the bonding criterion numerically is presented. The bonding criterion developed permits the effect of etched features to be assessed. Shallow etched patterns are shown to make bonding more difficult, while it is demonstrated that deep etched features can facilitate bonding. Model results and their process design implications are discussed in detail.

  9. Detection of Alkylating Agents using Electrical and Mechanical Means

    Science.gov (United States)

    Gerchikov, Yulia; Borzin, Elena; Gannot, Yair; Shemesh, Ariel; Meltzman, Shai; Hertzog-Ronen, Carmit; Tal, Shay; Stolyarova, Sara; Nemirovsky, Yael; Tessler, Nir; Eichen, Yoav

    2011-08-01

    Alkylating agents are reactive molecules having at least one polar bond between a carbon atom and a good leaving group. These often simple molecules are frequently used in organic synthesis, as sterilizing agents in agriculture and even as anticancer agents in medicine. Unfortunately, for over a century, some of the highly reactive alkylating agents are also being used as blister chemical warfare agents. Being relatively simple to make, the risk is that these will be applied by terrorists as poor people warfare agents. The detection and identification of such alkylating agents is not a simple task because of their high reactivity and simple structure of the reactive site. Here we report on new approaches to the detection and identification of such alkylating agents using electrical (organic field effect transistors) and mechanical (microcantilevers) means.

  10. Detection of Alkylating Agents using Electrical and Mechanical Means

    International Nuclear Information System (INIS)

    Gerchikov, Yulia; Borzin, Elena; Gannot, Yair; Shemesh, Ariel; Meltzman, Shai; Hertzog-Ronen, Carmit; Eichen, Yoav; Tal, Shay; Stolyarova, Sara; Nemirovsky, Yael; Tessler, Nir

    2011-01-01

    Alkylating agents are reactive molecules having at least one polar bond between a carbon atom and a good leaving group. These often simple molecules are frequently used in organic synthesis, as sterilizing agents in agriculture and even as anticancer agents in medicine. Unfortunately, for over a century, some of the highly reactive alkylating agents are also being used as blister chemical warfare agents. Being relatively simple to make, the risk is that these will be applied by terrorists as poor people warfare agents. The detection and identification of such alkylating agents is not a simple task because of their high reactivity and simple structure of the reactive site. Here we report on new approaches to the detection and identification of such alkylating agents using electrical (organic field effect transistors) and mechanical (microcantilevers) means.

  11. Detection of Alkylating Agents using Electrical and Mechanical Means

    Energy Technology Data Exchange (ETDEWEB)

    Gerchikov, Yulia; Borzin, Elena; Gannot, Yair; Shemesh, Ariel; Meltzman, Shai; Hertzog-Ronen, Carmit; Eichen, Yoav [Schulich Department of Chemistry, Technion-Israel Institute of Technology, Technion City, 32000, Haifa (Israel) (Israel); Tal, Shay [Present address: Systems Biology Department, Harvard Medical School, Boston, MA 02115 (United States); Stolyarova, Sara; Nemirovsky, Yael; Tessler, Nir, E-mail: chryoav@tx.technion.ac.il [Department of Electrical Engineering, Technion-Israel Institute of Technology, Technion City, 32000, Haifa (Israel)

    2011-08-17

    Alkylating agents are reactive molecules having at least one polar bond between a carbon atom and a good leaving group. These often simple molecules are frequently used in organic synthesis, as sterilizing agents in agriculture and even as anticancer agents in medicine. Unfortunately, for over a century, some of the highly reactive alkylating agents are also being used as blister chemical warfare agents. Being relatively simple to make, the risk is that these will be applied by terrorists as poor people warfare agents. The detection and identification of such alkylating agents is not a simple task because of their high reactivity and simple structure of the reactive site. Here we report on new approaches to the detection and identification of such alkylating agents using electrical (organic field effect transistors) and mechanical (microcantilevers) means.

  12. Effect of different surface treatments on bond strength, surface and microscopic structure of zirconia ceramic

    Directory of Open Access Journals (Sweden)

    Zeinab R. El-Shrkawy

    2016-06-01

    Conclusions: (1 Surface treatments of Y-TZP ceramic together with MDP primer and silane-coupling agent application improve the bond strength to resin cement. (2 Plasma-Silica coating and plasma-oxygen treatment, both are valuable methods that improve the bond strength of resin cement to Y-TZP ceramic. (3 Silica coating by plasma technology provides durable bond strength and can be a promising alternative pretreatment before silane application to enhance bonding with zirconia ceramic. (4 Tetragonal-monoclinic phase transformation had occurred in Y-TZP samples received both types of plasma treatment.

  13. Important role of the nucleotide excision repair pathway in Mycobacterium smegmatis in conferring protection against commonly encountered DNA-damaging agents.

    Science.gov (United States)

    Kurthkoti, Krishna; Kumar, Pradeep; Jain, Ruchi; Varshney, Umesh

    2008-09-01

    Mycobacteria are an important group of human pathogens. Although the DNA repair mechanisms in mycobacteria are not well understood, these are vital for the pathogen's persistence in the host macrophages. In this study, we generated a null mutation in the uvrB gene of Mycobacterium smegmatis to allow us to compare the significance of the nucleotide excision repair (NER) pathway with two important base excision repair pathways, initiated by uracil DNA glycosylase (Ung) and formamidopyrimidine DNA glycosylase (Fpg or MutM), in an isogenic strain background. The strain deficient in NER was the most sensitive to commonly encountered DNA-damaging agents such as UV, low pH, reactive oxygen species, hypoxia, and was also sensitive to acidified nitrite. Taken together with previous observations on NER-deficient M. tuberculosis, these results suggest that NER is an important DNA repair pathway in mycobacteria.

  14. Concepts, problems and the role of modifying agents in the relationship between recovery of cells' survival ability and mechanisms of repair of radiation lesions

    International Nuclear Information System (INIS)

    Orr, J.S.

    1984-01-01

    The two strands of the problem are the shapes and changes with time of cell survival curves on the one hand and the responses of cell constituents to radiation on the other. Evidence of correlations between results of studies of these two types of phenomena under the influence of a wide range of modifying agents is required to establish mechanisms. Recovery may be defined as referring to the whole cell, while repair should be regarded as a process carried out by one substance on another. The degrees of usefulness and possible deficiencies of a multi-hit/target model and a repair model for explaining cell survival curves and cell recovery are compared in a range of circumstances. A fully satisfactory model is not yet available. (author)

  15. Evaluating the role of behavioral factors and practical constraints in the performance of an agent-based model of farmer decision making

    DEFF Research Database (Denmark)

    Malawska, Anna Katarzyna; Topping, Christopher John

    2016-01-01

    Farmer decision making models often focus on the behavioral assumptions in the representation of the decision making, applying bounded rationality theory to shift away from the generally criticized profit maximizer approach. Although complex on the behavioral side, such representations are usually...... simplistic with respect to the available choice options in farmer decision making and practical constraints related to farming decisions. To ascertain the relevance of modeling different facets of farmer decision making, we developed an agent based model of farmer decision making on crop choice, fertilizer...... and pesticide usage using an existing economic farm optimization model. We then gradually modified the model to include practical agronomic constraints and assumptions reflecting bounded rationality, and assessed the explanatory power of the added model components. The assessments were based on comparisons...

  16. What is a hydrogen bond?

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. What is a hydrogen bond? Precise definition of a hydrogen bond is still elusive!1. Several criteria are listed usually for X-H•••Y, X and Y initially thought to be F, O and N only1. Structural: The X-Y bond length is less than the sum of their van der Waals radii. X-H•••Y is ...

  17. Composite interlayer for diffusion bonding

    International Nuclear Information System (INIS)

    1976-01-01

    A ductile interlayer is described, which is useful for transient liquid phase diffusion bonding of metallic articles; the interlayer consisting of a melting point depressant and a plurality of ductile lamellae which are free from carbides, aluminides and borides. The composition and fabrication of the lamellae, and the process for bonding the metallic articles, depend on the composition of the metals to be bonded, and are exemplified in the specification. (U.K.)

  18. Laser spectroscopic visualization of hydrogen bond motions in liquid water

    Science.gov (United States)

    Bratos, S.; Leicknam, J.-Cl.; Pommeret, S.; Gallot, G.

    2004-12-01

    Ultrafast pump-probe experiments are described permitting a visualization of molecular motions in diluted HDO/D 2O solutions. The experiments were realized in the mid-infrared spectral region with a time resolution of 150 fs. They were interpreted by a careful theoretical analysis, based on the correlation function approach of statistical mechanics. Combining experiment and theory, stretching motions of the OH⋯O bonds as well as HDO rotations were 'filmed' in real time. It was found that molecular rotations are the principal agent of hydrogen bond breaking and making in water. Recent literatures covering the subject, including molecular dynamics simulations, are reviewed in detail.

  19. Assessing the role of access and price on the consumption of fruits and vegetables across New York City using agent-based modeling.

    Science.gov (United States)

    Li, Yan; Zhang, Donglan; Thapa, Janani R; Madondo, Kumbirai; Yi, Stella; Fisher, Elisa; Griffin, Kerry; Liu, Bian; Wang, Youfa; Pagán, José A

    2018-01-01

    Most residents in New York City (NYC) do not consume sufficient fruits and vegetables every day. Difficulties with access and high prices of fruits and vegetables in some neighborhoods contribute to different consumption patterns across NYC neighborhoods. We developed an agent-based model (ABM) to predict dietary behaviors of individuals at the borough and neighborhood levels. Model parameters we