WorldWideScience

Sample records for bond activation expanded

  1. Rh(I)-Catalyzed Arylation of Heterocycles via C-H Bond Activation: Expanded Scope Through Mechanistic Insight

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Jared; Berman, Ashley; Bergman, Robert; Ellman, Jonathan

    2007-07-18

    A practical, functional group tolerant method for the Rh-catalyzed direct arylation of a variety of pharmaceutically important azoles with aryl bromides is described. Many of the successful azole and aryl bromide coupling partners are not compatible with methods for the direct arylation of heterocycles using Pd(0) or Cu(I) catalysts. The readily prepared, low molecular weight ligand, Z-1-tert-butyl-2,3,6,7-tetrahydrophosphepine, which coordinates to Rh in a bidentate P-olefin fashion to provide a highly active yet thermally stable arylation catalyst, is essential to the success of this method. By using the tetrafluoroborate salt of the corresponding phosphonium, the reactions can be assembled outside of a glove box without purification of reagents or solvent. The reactions are also conducted in THF or dioxane, which greatly simplifies product isolation relative to most other methods for direct arylation of azoles employing high-boiling amide solvents. The reactions are performed with heating in a microwave reactor to obtain excellent product yields in two hours.

  2. Bigelow Expandable Activity Module Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Bigelow Expandable Activity Module (BEAM) project is a NASA-industry partnership with Bigelow Aerospace (BA) that has developing the first human-rated expandable...

  3. Manufacture of Strand Board Bonded with Disposal Expanded Polystyrene as Binder

    OpenAIRE

    Hermawan, Andi; Ohuchi, Takeshi; Fujimoto, Noboru; 大内, 毅; 藤本, 登留

    2010-01-01

    The objective of this study was to evaluate the physical and mechanical properties of strand board bonded with disposal expanded polystyrene (EPS) as binder. The strand board was manufactured using strand made from Douglas-fir beams selected from construction scrap wood. The strands were oriented, and two types of three-layer (face-core-face) strand board were manufactured: one in which the board bounded with only disposal EPS (P board), and the other in which the board bonded with disposal...

  4. complexes on disulphide bond activation

    Indian Academy of Sciences (India)

    Administrator

    The antitumor, antibiotic leinamycin and its analogues are known as 'chemical nucleases' forming reactive hydroxyl species. 8,9. Earlier reports from our laboratory have shown that redox active copper(II) complexes having ligands with thioalkyl moieties are efficient DNA-cleaving agents on treat- ment with either a reducing ...

  5. Studying the effects of coarse pore expanded clay concrete on a permanent formwork made of cement bonded particle boards

    Directory of Open Access Journals (Sweden)

    Sigalov Aleksandr

    2017-01-01

    Full Text Available This paper suggests using a formwork system based on cement bonded particle boards (CBPB filled with coarse pore expanded clay concrete in order to improve the technical efficiency of the building envelope. Such a structure is made of lightweight or honeycomb concrete units, has a thickness equal to that of heavyweight concrete blocks and provides increased resistance to heat, better fire resistance and longer durability. The relatively modest price of the suggested option is seen as a notable advantage. The effects of coarse pore expanded clay concrete have been shown as being similar to the effects of heavyweight concrete, with the nature of the effects demonstrated on a hydrostatic pressure curve. The author has substantiated the geometric parameters for the suggested heat-efficient envelope design: a 800×800×370 mm block of CBPB filled with coarse-pore expanded clay concrete γ= 500kg/m3.

  6. Bonding, Achievement, and Activities: School Bonding, Academic Achievement, and Participation in Extracurricular Activities

    Science.gov (United States)

    Howard, Anissa K.; Ziomek-Daigle, Jolie

    2009-01-01

    Utilizing a single-group interrupted time series design (Creswell, 2003), this pilot study examined the relationship between academic achievement, school bonding, and the extracurricular activity participation of "uninvolved" students (n=11) who participated in a voluntary support group at a suburban high school in the southeast. Results…

  7. Real earnings management activities prior to bond issuance

    Directory of Open Access Journals (Sweden)

    Cristhian Mellado-Cid

    2017-07-01

    Full Text Available We examine real activities manipulation by firms prior to their debt issuances and how such manipulation activities affect bond yield spreads. We find that bond-issuing firms increase their real activities manipulation in the five quarters leading to a bond issuance. We document an inverse association between yield spread and pre-issue real activities manipulation, i.e., firms engaged in abnormally high levels of real activities manipulation are associated with subsequent lower cost of debt.

  8. Strength and leak testing of plasma activated bonded interfaces

    DEFF Research Database (Denmark)

    Visser, M.M.; Weichel, Steen; Reus, Roger De

    2002-01-01

    on detection of changes in membrane deflections. The detection limit for leak was 8E-13 mbar l/s. For comparison, strength and leak tests were also performed with regular fusion bonded wafers annealed at 1100 degreesC. The PAB was found to withstand post-processing steps such as RCA cleaning, 24 h in de......Bond strength and hermeticity of plasma activated bonded (PAB) Si-Si interfaces are reported. Bonding of 100 mm Si(1 0 0) wafers was performed. An average bond strength of 9.0+/-3.9 MPa was achieved without performing any annealing steps. Cavities bonded in vacuum were found to be hermetic based...

  9. 76 FR 28801 - Agency Information Collection Activities: Bonded Warehouse Regulations

    Science.gov (United States)

    2011-05-18

    ... Activities: Bonded Warehouse Regulations AGENCY: U.S. Customs and Border Protection, Department of Homeland... (OMB) for review and approval in accordance with the Paperwork Reduction Act: Bonded Warehouse.... Title: Bonded Warehouse Regulations. OMB Number: 1651-0041. Form Number: None. Abstract: Owners or...

  10. 76 FR 12364 - Agency Information Collection Activities: Bonded Warehouse Regulations

    Science.gov (United States)

    2011-03-07

    ... Activities: Bonded Warehouse Regulations AGENCY: U.S. Customs and Border Protection (CBP), Department of... requirement concerning the Bonded Warehouse Regulations. This request for comment is being made pursuant to...: Title: Bonded Warehouse Regulations. OMB Number: 1651-0041. Form Number: None. Abstract: Owners or...

  11. Strength and leak testing of plasma activated bonded interfaces

    DEFF Research Database (Denmark)

    Visser, M.M.; Weichel, Steen; Reus, Roger De

    2002-01-01

    Bond strength and hermeticity of plasma activated bonded (PAB) Si-Si interfaces are reported. Bonding of 100 mm Si(1 0 0) wafers was performed. An average bond strength of 9.0+/-3.9 MPa was achieved without performing any annealing steps. Cavities bonded in vacuum were found to be hermetic based...... on detection of changes in membrane deflections. The detection limit for leak was 8E-13 mbar l/s. For comparison, strength and leak tests were also performed with regular fusion bonded wafers annealed at 1100 degreesC. The PAB was found to withstand post-processing steps such as RCA cleaning, 24 h in de......-ionised water (DIW), 24 h in 2.5% HF, 24 h in acetone and 60 s in a resist developer. By analysing the thin silicon oxide present on the surfaces to be bonded with optical methods, the influence of pre-cleaning and activation process parameters was investigated....

  12. Rhodium-Catalyzed C-C Bond Formation via Heteroatom-Directed C-H Bond Activation

    Energy Technology Data Exchange (ETDEWEB)

    Colby, Denise; Bergman, Robert; Ellman, Jonathan

    2010-05-13

    Once considered the 'holy grail' of organometallic chemistry, synthetically useful reactions employing C-H bond activation have increasingly been developed and applied to natural product and drug synthesis over the past decade. The ubiquity and relative low cost of hydrocarbons makes C-H bond functionalization an attractive alternative to classical C-C bond forming reactions such as cross-coupling, which require organohalides and organometallic reagents. In addition to providing an atom economical alternative to standard cross - coupling strategies, C-H bond functionalization also reduces the production of toxic by-products, thereby contributing to the growing field of reactions with decreased environmental impact. In the area of C-C bond forming reactions that proceed via a C-H activation mechanism, rhodium catalysts stand out for their functional group tolerance and wide range of synthetic utility. Over the course of the last decade, many Rh-catalyzed methods for heteroatom-directed C-H bond functionalization have been reported and will be the focus of this review. Material appearing in the literature prior to 2001 has been reviewed previously and will only be introduced as background when necessary. The synthesis of complex molecules from relatively simple precursors has long been a goal for many organic chemists. The ability to selectively functionalize a molecule with minimal pre-activation can streamline syntheses and expand the opportunities to explore the utility of complex molecules in areas ranging from the pharmaceutical industry to materials science. Indeed, the issue of selectivity is paramount in the development of all C-H bond functionalization methods. Several groups have developed elegant approaches towards achieving selectivity in molecules that possess many sterically and electronically similar C-H bonds. Many of these approaches are discussed in detail in the accompanying articles in this special issue of Chemical Reviews. One approach

  13. Mechanism of bonding and debonding using surface activated bonding method with Si intermediate layer

    Science.gov (United States)

    Takeuchi, Kai; Fujino, Masahisa; Matsumoto, Yoshiie; Suga, Tadatomo

    2018-04-01

    Techniques of handling thin and fragile substrates in a high-temperature process are highly required for the fabrication of semiconductor devices including thin film transistors (TFTs). In our previous study, we proposed applying the surface activated bonding (SAB) method using Si intermediate layers to the bonding and debonding of glass substrates. The SAB method has successfully bonded glass substrates at room temperature, and the substrates have been debonded after heating at 450 °C, in which TFTs are fabricated on thin glass substrates for LC display devices. In this study, we conducted the bonding and debonding of Si and glass in order to understand the mechanism in the proposed process. Si substrates are also successfully bonded to glass substrates at room temperature and debonded after heating at 450 °C using the proposed bonding process. By the composition analysis of bonding interfaces, it is clarified that the absorbed water on the glass forms interfacial voids and cause the decrease in bond strength.

  14. Theoretical Characterization of the H-Bonding and Stacking Potential of Two Non-Standard Nucleobases Expanding the Genetic Alphabet

    KAUST Repository

    Chawla, Mohit

    2016-02-16

    We report a quantum chemical characterization of the non-natural (synthetic) H-bonded base pair formed by 6-amino-5-nitro-2(1H)-pyridone (Z) and 2-amino-imidazo [1,2-a]-1,3,5-triazin-4(8H)-one (P). The Z:P base pair, orthogonal to the classical G:C base pair, has been introduced in DNA molecules for expanding the genetic code. Our results indicate that the Z:P base pair closely mimics the G:C base pair both in terms of structure and stability. To clarify the role of the NO2 group on the C5 position of the Z base, we compared the stability of the Z:P base pair with that of base pairs having different functional group on the C5 position of Z. Our results indicate that the electron donating/withdrawing properties of the group in the C5 position has a clear impact on the stability of the Z:P base pair, with the strong electron withdrawing nitro group achieving the largest stabilizing effect on the H-bonding interaction, and the strong electron donating NH2 group destabilizing the Z:P pair by almost 4 kcal/mol. Finally, our gas phase and in water calculations confirm that the Z-nitro group reinforce the stacking interaction with its adjacent purine or pyrimidine ring.

  15. Hydrogen bonds and antiviral activity of benzaldehyde derivatives

    Science.gov (United States)

    Tolstorozhev, G. B.; Skornyakov, I. V.; Belkov, M. V.; Shadyro, O. I.; Brinkevich, S. D.; Samovich, S. N.

    2012-09-01

    We have obtained the Fourier transform IR spectra of solutions of benzaldehyde derivatives having different antiviral activities against a herpes virus. We observe a correlation between the presence of hydrogen bonds in the benzaldehyde molecules and the appearance of antiviral properties in the compounds. For compounds having antiviral activity, we have obtained spectral data suggesting the existence of hydrogen bonds of the type C=OṡṡṡH-O and O-HṡṡṡO in the molecules. When the hydrogen atom in the hydroxyl groups are replaced by a methyl group, no intramolecular hydrogen bonds are formed and the compounds lose their antiviral activity.

  16. Science and technology of plasma activated direct wafer bonding

    Science.gov (United States)

    Roberds, Brian Edward

    This dissertation studied the kinetics of silicon direct wafer bonding with emphasis on low temperature bonding mechanisms. The project goals were to understand the topological requirements for initial bonding, develop a tensile test to measure the bond strength as a function of time and temperature and, using the kinetic information obtained, develop lower temperature methods of bonding. A reproducible surface metrology metric for bonding was best described by power spectral density derived from atomic force microscopy measurements. From the tensile strength kinetics study it was found that low annealing temperatures could be used to obtain strong bonds, but at the expense of longer annealing times. Three models were developed to describe the kinetics. A diffusion controlled model and a reaction rate controlled model were developed for the higher temperature regimes (T > 600sp°C), and an electric field assisted oxidation model was proposed for the low temperature range. An in situ oxygen plasma treatment was used to further enhance the field-controlled mechanism which resulted in dramatic increases in the low temperature bonding kinetics. Multiple internal transmission Fourier transform infrared spectroscopy (MIT-FTIR) was used to monitor species evolution at the bonded interface and a capacitance-voltage (CV) study was undertaken to investigate charge distribution and surface states resulting from plasma activation. A short, less than a minute, plasma exposure prior to contacting the wafers was found to obtain very strong bonds for hydrophobic silicon wafers at very low temperatures (100sp°C). This novel bonding method may enable new technologies involving heterogeneous material systems or bonding partially fabricated devices to become realities.

  17. 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.

  18. Management of skeletal Class III malocclusion with unilateral crossbite on a growing patient using facemask-bonded rapid palatal expander and fixed appliances

    Directory of Open Access Journals (Sweden)

    Tinnie Effendy

    2015-01-01

    Full Text Available Facemask (FM and bonded rapid palatal expander (RPE are part of growth modification treatments for correcting skeletal Class III pattern with retrognathic maxilla. This orthopaedic treatment is usually preceded by fixed appliances to achieve aesthetic dental alignment and improve interdigitation. This case report reviews treatment of Class III malocclusion with unilateral crossbite in a 12-year-old boy using FM and bonded RPE, followed by fixed appliances. Choice of FM and bonded RPE was in line with indication which was mild Class III malocclusion with retrognathic maxilla. Execution of treatment was made considering treatment biomechanics and patient cooperation. This orthopaedic treatment was followed by orthodontic treatment specifically aimed to correct unilateral crossbite, canine relationship yet to reach Class I, lower midline shift, as well as unintended dental consequences of using bonded RPE, namely posterior open bite and deepening curve of spee. Posttreatment facial profile and smile are more esthetic. Occlusion is significantly improved both functionally and aesthetically.

  19. Expanding the mirror : vicarious activity for actions, emotions, and sensations

    NARCIS (Netherlands)

    Keysers, Christian; Gazzola, Valeria

    2009-01-01

    We often empathically share the states of others. The discovery of 'mirror neurons' suggested a neural mechanism for monkeys to share the actions of others. Here we expand this view by showing that mirror neurons for actions not only exist in the premotor cortex or in monkeys and that vicarious

  20. Actor Bonds in Situations of Discontinuous Business Activities

    DEFF Research Database (Denmark)

    Skaates, Maria Anne

    2000-01-01

    in situations of discontinuity. Therefore an analysis and comparison of relevant concepts that capture the key generative features of actor bonds in both socially constructed networks and socially constructed markets is undertaken. These concepts include the "milieu" of project marketing (Cova et al., 1996......Demand in many industrial buying situations, e.g. project purchases or procurement related to virtual organizations, is discontinuous. In situations of discontinuity, networks are often more of an ad hos informational and social nature, as strong activity and resource links are not present......) and the institutional concept of the "field". Finally this paper introduces the concept of "social capital" (Bourdieu, 1983) and discusses whether it can be used to conceptualize the dynamic features of actor bonds in situations of discontinuity....

  1. Surface activated room-temperature bonding in Ar gas ambient for MEMS encapsulation

    Science.gov (United States)

    Takagi, Hideki; Kurashima, Yuichi; Takamizawa, Akifumi; Ikegami, Takeshi; Yanagimachi, Shinya

    2018-02-01

    Surface activated room-temperature bonding of Si and sapphire wafers in high-purity inert gas ambient was examined. Although surface activated bonding has been mainly performed in high vacuum, Si and sapphire wafers were successfully bonded in Ar gas ambient up to 90 kPa, which is almost atmospheric pressure. The dicing test proved that the bonding prepared in Ar gas ambient was strong enough for MEMS packaging, although the bonding strength was slightly decreased compared with that prepared in vacuum. Transmission electron microscope observation revealed that the bonding interface prepared in Ar gas ambient is almost the same as that prepared in vacuum. It means that Ar atoms in the bonding ambient do not hamper the interatomic bond formation at the bonding interface. Room-temperature bonding in gas ambient enables hermetic packaging of MEMS devices, such as inertia sensors, MEMS switches, and Cs vapor cells for MEMS atomic clocks at various pressures.

  2. Developments of a bonding technique for optical materials by a surface activation method

    International Nuclear Information System (INIS)

    Sugiyama, Akira; Oda, Tomohiro; Abe, Tomoyuki; Kusunoki, Isao

    2005-01-01

    We started developing the laser crystal bounding by the surface activation method which can splice crystals together without using hydrogen bonding. For the surface activation, neutral argon beams were used for irradiation of specimens. In the bonding trials with sapphire crystals, we recognized possibility of the bonding method for optical elements. (author)

  3. Activation of Dihydrogen by Masked Doubly Bonded Aluminum Species.

    Science.gov (United States)

    Nagata, Koichi; Murosaki, Takahiro; Agou, Tomohiro; Sasamori, Takahiro; Matsuo, Tsukasa; Tokitoh, Norihiro

    2016-10-04

    Activation of dihydrogen by masked dialumenes (Al=Al doubly bonded species) is reported. Reactions of barrelene-type dialumanes, which have the reactivity as masked equivalents of 1,2-diaryldialumenes ArAl=AlAr, with H2 afforded dihydroalumanes ArAlH2 at room temperature (Ar: bulky aryl groups). These dihydroalumanes form hydrogen-bridged dimers [ArHAl(μ-H)]2 in the crystalline state, while a monomer-dimer equilibrium was suggested in solution. The 1,2-diaryldialumenes generated from the barrelene-type dialumanes are the putative active species in the cleavage of H2 . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Disulfide bond within mu-calpain active site inhibits activity and autolysis.

    Science.gov (United States)

    Lametsch, René; Lonergan, Steven; Huff-Lonergan, Elisabeth

    2008-09-01

    Oxidative processes have the ability to influence mu-calpain activity. In the present study the influence of oxidation on activity and autolysis of mu-calpain was examined. Furthermore, LC-MS/MS analysis was employed to identify and characterize protein modifications caused by oxidation. The results revealed that the activity of mu-calpain is diminished by oxidation with H2O2 in a reversible manner involving cysteine and that the rate of autolysis of mu-calpain concomitantly slowed. The LC-MS/MS analysis of the oxidized mu-calpain revealed that the amino acid residues 105-133 contained a disulfide bond between Cys(108) and Cys(115). The finding that the active site cysteine in mu-calpain is able to form a disulfide bond has, to our knowledge, not been reported before. This could be part of a unique oxidation mechanism for mu-calpain. The results also showed that the formation of the disulfide bond is limited in the control (no oxidant added), and further limited in a concentration-dependent manner when beta-mercaptoethanol is added. However, the disulfide bond is still present to some extent in all conditions indicating that the active site cysteine is potentially highly susceptible to the formation of this intramolecular disulfide bond.

  5. 77 FR 6814 - Agency Information Collection Activities: Bonded Warehouse Proprietor's Submission

    Science.gov (United States)

    2012-02-09

    ... Activities: Bonded Warehouse Proprietor's Submission AGENCY: U.S. Customs and Border Protection (CBP... requirement concerning the Bonded Warehouse Proprietor's Submission (CBP Form 300). This request for comment... collection: Title: Bonded Warehouse Proprietor's Submission. OMB Number: 1651-0033. Form Number: CBP Form 300...

  6. 77 FR 26024 - Agency Information Collection Activities: Bonded Warehouse Proprietor's Submission

    Science.gov (United States)

    2012-05-02

    ... Activities: Bonded Warehouse Proprietor's Submission AGENCY: U.S. Customs and Border Protection, Department... Budget (OMB) for review and approval in accordance with the Paperwork Reduction Act: Bonded Warehouse..., or other technological techniques or other forms of information. Title: Bonded Warehouse Proprietor's...

  7. α-Halogenoacetanilides as hydrogen-bonding organocatalysts that activate carbonyl bonds: fluorine versus chlorine and bromine.

    Science.gov (United States)

    Koeller, Sylvain; Thomas, Coralie; Peruch, Fréderic; Deffieux, Alain; Massip, Stéphane; Léger, Jean-Michel; Desvergne, Jean-Pierre; Milet, Anne; Bibal, Brigitte

    2014-03-03

    α-Halogenoacetanilides (X=F, Cl, Br) were examined as H-bonding organocatalysts designed for the double activation of CO bonds through NH and CH donor groups. Depending on the halide substituents, the double H-bond involved a nonconventional CH⋅⋅⋅O interaction with either a HCXn (n=1-2, X=Cl, Br) or a HCAr bond (X=F), as shown in the solid-state crystal structures and by molecular modeling. In addition, the catalytic properties of α-halogenoacetanilides were evaluated in the ring-opening polymerization of lactide, in the presence of a tertiary amine as cocatalyst. The α-dichloro- and α-dibromoacetanilides containing electron-deficient aromatic groups afforded the most attractive double H-bonding properties towards CO bonds, with a NH⋅⋅⋅O⋅⋅⋅HCX2 interaction. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Redox-​Active Ligand-​Induced Homolytic Bond Activation

    NARCIS (Netherlands)

    Broere, D.L.J.; Metz, L.L.; de Bruin, B.; Reek, J.N.H.; Siegler, M.A.; van der Vlugt, J.I.

    2015-01-01

    Coordination of the novel redox-​active phosphine-​appended aminophenol pincer ligand (PNOH2) to PdII generates a paramagnetic complex with a persistent ligand-​centered radical. The complex undergoes fully reversible single-​electron oxidn. and redn. Homolytic bond activation of diphenyldisulfide

  9. Metal-ligand cooperation by aromatization-dearomatization as a tool in single bond activation.

    Science.gov (United States)

    Milstein, David

    2015-03-13

    Metal-ligand cooperation (MLC) plays an important role in bond activation processes, enabling many chemical and biological catalytic reactions. A recent new mode of activation of chemical bonds involves ligand aromatization-dearomatization processes in pyridine-based pincer complexes in which chemical bonds are broken reversibly across the metal centre and the pincer-ligand arm, leading to new bond-making and -breaking processes, and new catalysis. In this short review, such processes are briefly exemplified in the activation of C-H, H-H, O-H, N-H and B-H bonds, and mechanistic insight is provided. This new bond activation mode has led to the development of various catalytic reactions, mainly based on alcohols and amines, and to a stepwise approach to thermal H2 and light-induced O2 liberation from water. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  10. Expanded activity of schools in Serbia: Legal framework and practical experiences

    Directory of Open Access Journals (Sweden)

    Ognjenović Kosovka Đ.

    2012-09-01

    Full Text Available Expanded activities of schools and activities of student cooperatives are important components of the educational process in schools, which are contributing to the improvement of the quality of education and better social inclusion of students. The main objective of this article is to focus on opportunities enabled by the legal framework that supports the realization of expanded activities and activities of student cooperatives in Serbian schools and to compare relevant experiences in Serbia with the practice in neighbouring countries and the old EU Member States. In particular, in this article it is examined to what extent the adoption of entrepreneurial competences through different entrepreneurship development programs contributes to the probability of implementation of additional activities in Serbian schools. For this purpose, the data of the Survey on practising, types and usefulness of expanded activities and activities of student cooperatives are used. This survey was conducted in 2010 at the samples of public primary and secondary schools that executed some sort of additional activities, as well as of schools that did not practice extended activities.

  11. Crystallization of microparticulate pure polymorphs of active pharmaceutical ingredients using CO 2-expanded solvents

    OpenAIRE

    Veciana, J.; Sala, S.; Córdoba, A.; Moreno Calvo, E.; Elizondo, E.; Muntó, M.; Rojas, P.E.; Larrayoz Iriarte, María Angeles; Ventosa, N.

    2012-01-01

    The feasibility of the Depressurization of an Expanded Liquid Organic Solution (DELOS) method to process different active pharmaceutical ingredients (APIs) as finely divided powders with narrow particle size distribution, high crystallinity degree, high polymorphic purity, and free from residual solvent has been demonstrated. Cholesterol, acetylsalicylic acid (aspirin), naproxen, acetaminophen, and ibuprofen were chosen as model drugs. It has been demonstrated that the supersat...

  12. Diffusion bonding of reduced activation ferritic steel F82H for demo blanket application

    International Nuclear Information System (INIS)

    Kurasawa, T.; Tamura, M.

    1996-01-01

    A reduced activation ferritic steel, a grade F82H developed by JAERI, is a promising candidate structural material for the blanket and the first wall of DEMO reactors. In the present study, diffusion bonding of F82H has been investigated to develop the fabrication procedures of the blanket box and the first wall panel with cooling channels embedded by F82H. The parameters examined are the bonding temperature (810-1050 C), bonding pressure (2-10 MPa) and roughness of the bonding surface (0.5-12.8 μR max ), and metallurgical examination and mechanical tests of the diffusion bonded joints have been conducted. From the tests, sufficient bonding was obtained under the temperatures of 840-1 050 C (compressive stress of 3-12 MPa), and it was found that heat treatment following diffusion bonding is essential to obtain the mechanical properties similar to that of the base metal. (orig.)

  13. 26 CFR 1.103(n)-3T - Private activity bond limit (temporary).

    Science.gov (United States)

    2010-04-01

    ... containing constitutional home rule cities. Q-2: What is the private activity bond limit for a State agency... a constitutional home rule city is an amount that bears the same ratio to the State ceiling for such... population of the entire State. The private activity bond limit for issuers other than constitutional home...

  14. Non-activated high surface area expanded graphite oxide for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Vermisoglou, E.C.; Giannakopoulou, T.; Romanos, G.E.; Boukos, N.; Giannouri, M. [Institute of Nanoscience and Nanotechnology “Demokritos”, 153 43 Ag. Paraskevi, Attikis (Greece); Lei, C.; Lekakou, C. [Division of Mechanical, Medical, and Aerospace Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); Trapalis, C., E-mail: c.trapalis@inn.demokritos.gr [Institute of Nanoscience and Nanotechnology “Demokritos”, 153 43 Ag. Paraskevi, Attikis (Greece)

    2015-12-15

    Graphical abstract: - Highlights: • One-step exfoliation and reduction of graphite oxide via microwave irradiation. • Effect of pristine graphite (type, flake size) on the microwave expanded material. • Effect of pretreatment and oxidation cycles on the produced expanded material. • Expanded graphene materials with high BET surface areas (940 m{sup 2}/g–2490 m{sup 2}/g). • Non-activated graphene based materials suitable for supercapacitors. - Abstract: Microwave irradiation of graphite oxide constitutes a facile route toward production of reduced graphene oxide, since during this treatment both exfoliation and reduction of graphite oxide occurs. In this work, the effect of pristine graphite (type, size of flakes), pretreatment and oxidation cycles on the finally produced expanded material was examined. All the types of graphite that were tested afforded materials with high BET surface areas ranging from 940 m{sup 2}/g to 2490 m{sup 2}/g, without intervening an activation stage at elevated temperature. SEM and TEM images displayed exfoliated structures, where the flakes were significantly detached and curved. The quality of the reduced graphene oxide sheets was evidenced both by X-ray photoelectron spectroscopy and Raman spectroscopy. The electrode material capacitance was determined via electrochemical impedance spectroscopy and cyclic voltammetry. The materials with PEDOT binder had better performance (∼97 F/g) at low operation rates while those with PVDF binder performed better (∼20 F/g) at higher rates, opening up perspectives for their application in supercapacitors.

  15. A General Catalyst for Site-Selective C(sp(3))-H Bond Amination of Activated Secondary over Tertiary Alkyl C(sp(3))-H Bonds.

    Science.gov (United States)

    Scamp, Ryan J; Jirak, James G; Dolan, Nicholas S; Guzei, Ilia A; Schomaker, Jennifer M

    2016-06-17

    The discovery of transition metal complexes capable of promoting general, catalyst-controlled and selective carbon-hydrogen (C-H) bond amination of activated secondary C-H bonds over tertiary alkyl C(sp(3))-H bonds is challenging, as substrate control often dominates when reactive nitrene intermediates are involved. In this letter, we report the design of a new silver complex, [(Py5Me2)AgOTf]2, that displays general and good-to-excellent selectivity for nitrene insertion into propargylic, benzylic, and allylic C-H bonds over tertiary alkyl C(sp(3))-H bonds.

  16. Bond strength of resin composite to light activated bleached enamel

    African Journals Online (AJOL)

    2015-09-02

    Sep 2, 2015 ... Conclusion: The various irradiation treatments following the application of the whiteness HP bleaching agent to enamel did not significantly reduce the µTBS within a 14‑day period. Key words: Bleaching agents, lasers, lasers neodymium: yttrium aluminum garnet, resin bonding, tooth bleaching. Date of ...

  17. Activation of C-H bond in methane by Pd atom from the bonding evolution theory perspective.

    Science.gov (United States)

    Nizovtsev, Anton S

    2013-08-15

    We report detailed study focused on the electron density redistribution during the simple oxidative addition reaction being the crucial stage of various catalytic processes. The bonding evolution theory based on the electron localization function and Thom's catastrophe theory shows that activation of methane's C-H bond by Pd atom consist of six elementary steps. The important feature revealed is the pronounced reorganization of Pd's outer core maxima corresponding to N-shell electrons of metal. Electronic rearrangements identified in this model reaction are likely to be the case in the more complex reactions of the same type involving transition metal compounds and, in principle, can be observed by modern ultrafast spectroscopy and diffraction techniques. Copyright © 2013 Wiley Periodicals, Inc.

  18. 78 FR 66038 - Agency Information Collection Activities: Application for Exportation of Articles Under Special Bond

    Science.gov (United States)

    2013-11-04

    ... forms of information. Title: Application for Exportation of Articles under Special Bond. OMB Number... DEPARTMENT OF HOMELAND SECURITY U. S. Customs and Border Protection Agency Information Collection Activities: Application for Exportation of Articles Under Special Bond AGENCY: U.S. Customs and Border...

  19. Rhodium mediated bond activation: from synthesis to catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Hung-An [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    Recently, our lab has developed monoanionic tridentate ligand, ToR, showing the corresponding coordination chemistry and catalyst reactivity of magnesium, zirconium, zinc and iridium complexes. This thesis details synthetic chemistry, structural study and catalytic reactivity of the ToR-supported rhodium compounds. Tl[ToR] has been proved to be a superior ligand transfer agent for synthesizing rhodium complexes. The salt metathesis route of Tl[ToM] with [Rh(μ-Cl)(CO)]2 and [Rh(μ- Cl)(COE)]2 gives ToMRh(CO)2 (2.2) and ToMRhH(β3-C8H13) (3.1) respectively while Tl[ToM] with [Rh(μ-Cl)(CO)]2 affords ToPRh(CO)2 (2.3). 2.2 reacts with both strong and weak electrophiles, resulting in the oxazoline N-attacked and the metal center-attacked compounds correspondingly. Using one of the metal center-attacked electrophiles, 2.3 was demonstrated to give high diastereoselectivity. Parallel to COE allylic C-H activation complex 3.1, the propene and allylbenzene allylic C-H activation products have also been synthesized. The subsequent functionalization attempts have been examined by treating with Brønsted acids, Lewis acids, electrophiles, nucleophiles, 1,3-dipolar reagents and reagents containing multiple bonds able to be inserted. Various related complexes have been obtained under these conditions, in which one of the azide insertion compounds reductively eliminates to give an allylic functionalization product stoichiometrically. 3.1 reacts with various primary alcohols to give the decarbonylation dihydride complex ToMRh(H)2CO (4.1). 4.1 shows catalytic reactivity for primary alcohol decarbonylation under a photolytic condition. Meanwhile, 2.2 has been found to be more reactive than 4.1 for catalytic alcohol decarbonylation under the same condition. Various complexes and primary

  20. Metal-free oxidative olefination of primary amines with benzylic C-H bonds through direct deamination and C-H bond activation.

    Science.gov (United States)

    Gong, Liang; Xing, Li-Juan; Xu, Tong; Zhu, Xue-Ping; Zhou, Wen; Kang, Ning; Wang, Bin

    2014-09-14

    An oxidative olefination reaction between aliphatic primary amines and benzylic sp(3) C-H bonds has been achieved using N-bromosuccinimide as catalyst and tert-butyl hydroperoxide as oxidant. The olefination proceeds under mild metal-free conditions through direct deamination and benzylic C-H bond activation, and provides easy access to biologically active 2-styrylquinolines with (E)-configuration.

  1. CHEMICAL ACTIVATION OF MOLECULES BY METALS: EXPERIMENTAL STUDIES OF ELECTRON DISTRIBUTIONS AND BONDING; FINAL

    International Nuclear Information System (INIS)

    LICHTENBERGER, DENNIS L.

    2002-01-01

    This research program is directed at obtaining detailed experimental information on the electronic interactions between metals and organic molecules. These interactions provide low energy pathways for many important chemical and catalytic processes. A major feature of the program is the continued development and application of our special high-resolution valence photoelectron spectroscopy (UPS), and high-precision X-ray core photoelectron spectroscopy (XPS) instrumentation for study of organometallic molecules in the gas phase. The study involves a systematic approach towards understanding the interactions and activation of bound carbonyls, C-H bonds, methylenes, vinylidenes, acetylides, alkenes, alkynes, carbenes, carbynes, alkylidenes, alkylidynes, and others with various monometal, dimetal, and cluster metal species. Supporting ligands include -aryls, alkoxides, oxides, and phosphines. We are expanding our studies of both early and late transition metal species and electron-rich and electron-poor environments in order to more completely understand the electronic factors that serve to stabilize particular organic fragments and intermediates on metals. Additional new directions for this program are being taken in ultra-high vacuum surface UPS, XPS, scanning tunneling microscopy (STM) and atomic force microscopy (AFM) experiments on both physisorbed and chemisorbed organometallic thin films. The combination of these methods provides additional electronic structure information on surface-molecule and molecule-molecule interactions. A very important general result emerging from this program is the identification of a close relationship between the ionization energies of the species and the thermodynamics of the chemical and catalytic reactions of these systems

  2. CHEMICAL ACTIVATION OF MOLECULES BY METALS: EXPERIMENTAL STUDIES OF ELECTRON DISTRIBUTIONS AND BONDING

    Energy Technology Data Exchange (ETDEWEB)

    LICHTENBERGER, DENNIS L.

    2002-03-26

    This research program is directed at obtaining detailed experimental information on the electronic interactions between metals and organic molecules. These interactions provide low energy pathways for many important chemical and catalytic processes. A major feature of the program is the continued development and application of our special high-resolution valence photoelectron spectroscopy (UPS), and high-precision X-ray core photoelectron spectroscopy (XPS) instrumentation for study of organometallic molecules in the gas phase. The study involves a systematic approach towards understanding the interactions and activation of bound carbonyls, C-H bonds, methylenes, vinylidenes, acetylides, alkenes, alkynes, carbenes, carbynes, alkylidenes, alkylidynes, and others with various monometal, dimetal, and cluster metal species. Supporting ligands include -aryls, alkoxides, oxides, and phosphines. We are expanding our studies of both early and late transition metal species and electron-rich and electron-poor environments in order to more completely understand the electronic factors that serve to stabilize particular organic fragments and intermediates on metals. Additional new directions for this program are being taken in ultra-high vacuum surface UPS, XPS, scanning tunneling microscopy (STM) and atomic force microscopy (AFM) experiments on both physisorbed and chemisorbed organometallic thin films. The combination of these methods provides additional electronic structure information on surface-molecule and molecule-molecule interactions. A very important general result emerging from this program is the identification of a close relationship between the ionization energies of the species and the thermodynamics of the chemical and catalytic reactions of these systems.

  3. Sequential plasma activation methods for hydrophilic direct bonding at sub-200 °C

    Science.gov (United States)

    He, Ran; Yamauchi, Akira; Suga, Tadatomo

    2018-02-01

    We present our newly developed sequential plasma activation methods for hydrophilic direct bonding of silica glasses and thermally grown SiO2 films. N2 plasma was employed to introduce a metastable oxynitride layer on wafer surfaces for the improvement of bond energy. By using either O2-plasma/N2-plasma/N-radical or N2-plasma/N-radical sequential activation, the quartz-quartz bond energy was increased from 2.7 J/m2 to close to the quartz bulk fracture energy that was estimated to be around 9.0 J/m2 after post-bonding annealing at 200 °C. The silicon bulklike bond energy between thermal SiO2 films was also obtained. We suggest that the improvement is attributable to surface modification such as N-related defect formation and asperity softening by the N2 plasma surface treatment.

  4. 26 CFR 1.103(n)-1T - Limitation on aggregrate amount of private activity bonds (temporary).

    Science.gov (United States)

    2010-04-01

    ... activity bonds (temporary). 1.103(n)-1T Section 1.103(n)-1T Internal Revenue INTERNAL REVENUE SERVICE... Excluded from Gross Income § 1.103(n)-1T Limitation on aggregrate amount of private activity bonds (temporary). Q-1: What does section 103(n) provide? A-1: Interest on an issue of private activity bonds will...

  5. Structural snapshots of concerted double E-H bond activation at a transition metal centre

    Science.gov (United States)

    Abdalla, Joseph A. B.; Caise, Alexa; Sindlinger, Christian P.; Tirfoin, Rémi; Thompson, Amber L.; Edwards, Alison J.; Aldridge, Simon

    2017-12-01

    Bond activation at a transition metal centre is a key fundamental step in numerous chemical transformations. The oxidative addition of element-hydrogen bonds, for example, represents a critical step in a range of widely applied catalytic processes. Despite this, experimental studies defining steps along the bond activation pathway are very rare. In this work, we report on fundamental studies defining a new oxidative activation pathway: combined experimental and computational approaches yield structural snapshots of the simultaneous activation of both bonds of a β-diketiminate-stabilized GaH2 unit at a single metal centre. Systematic variation of the supporting phosphine ligands and single crystal X-ray/neutron diffraction are exploited in tandem to allow structural visualization of the activation process, from a η2-H,H σ-complex showing little Ga-H bond activation, through species of intermediate geometry featuring stretched Ga-H and compressed M-H/M-Ga bonds, to a fully activated metal dihydride featuring a neutral (carbene-type) N-heterocyclic GaI ligand.

  6. New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

    Directory of Open Access Journals (Sweden)

    Pavel Nagorny

    2016-12-01

    Full Text Available Hydrogen bond donor catalysis represents a rapidly growing subfield of organocatalysis. While traditional hydrogen bond donors containing N–H and O–H moieties have been effectively used for electrophile activation, activation based on other types of non-covalent interactions is less common. This mini review highlights recent progress in developing and exploring new organic catalysts for electrophile activation through the formation of C–H hydrogen bonds and C–X halogen bonds.

  7. Direct Functionalization of Nitrogen Heterocycles via Rh-Catalyzed C-H Bond Activation

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Jared; Bergman, Robert; Ellman, Jonathan

    2008-02-04

    heterocycles, including azoles, azolines, dihydroquinazolines, pyridines, and quinolines, with a wide range of functionalized olefins. They demonstrated the utility of this methodology in the synthesis of natural products, drug candidates, and other biologically active molecules. In addition, they developed conditions to directly arylate these heterocycles with aryl halides. The initial conditions that used PCy{sub 3} as a ligand were successful only for aryl iodides. However, efforts designed to avoid catalyst decomposition led to the development of ligands based on 9-phosphabicyclo[4.2.1]nonane (Phoban) that also facilitated the coupling of aryl bromides. They then replicated the unique coordination environment, stability, and catalytic activity of this complex using the much simpler tetrahydrophosphepine ligands and developed conditions that coupled aryl bromides bearing diverse functional groups without the use of a glovebox or purified reagents. With further mechanistic inquiry, they anticipate that researchers will better understand the details of the aforementioned Rh-catalyzed C-H bond functionalization reactions, resulting in the design of more efficient and robust catalysts, expanded substrate scope, and new transformations.

  8. Iron Coordination and Halogen-Bonding Assisted Iodosylbenzene Activation

    DEFF Research Database (Denmark)

    Wegeberg, Christina; Poulsen de Sousa, David; McKenzie, Christine

    The iron complex of the hexadentate ligand N,N,N'-tris(2-pyridylmethyl)ethylendiamine-N'-acetate (tpena) efficiently catalyzes selective oxidations of electron-rich olefins and sulfides by insoluble iodosylbenzene (PhIO). Surprisingly, these reactions are faster and more selective than homogenous...... catalytic mixtures using soluble terminal oxygen transfer agents. Isolation of a reactive iron-terminal oxidant adduct, an unique Fe(III)-OIPh complex, is facilitated by strong stabilizing supramolecular halogen-bonding. L3-edge XANES suggests +1.6 for the average oxidation state for the iodine atom3...... in the iron(III)-coordinated PhIO. This represents a reduction of iodine relative to the original “hypervalent” (+3) PhIO. The equivalent of electron density must be removed from the {(tpena)Fe(III)O} moiety, however Mössbauer spectroscopy shows that the iron atom is not high valent....

  9. What Expands in an Expanding Universe?

    Directory of Open Access Journals (Sweden)

    JOSÉ A. DE FREITAS PACHECO

    2015-12-01

    Full Text Available ABSTRACT In the present investigation, the possible effects of the expansion of the Universe on systems bonded either by gravitational or electromagnetic forces, are reconsidered. It will be shown that the acceleration (positive or negative of the expanding background, is the determinant factor affecting planetary orbits and atomic sizes. In the presently accepted cosmology (ΛCDM all bonded systems are expanding at a decreasing rate that tends to be zero as the universe enters in a de Sitter phase. It is worth mentioning that the estimated expansion rates are rather small and they can be neglected for all practical purposes.

  10. What Expands in an Expanding Universe?

    Science.gov (United States)

    Pacheco, José A De Freitas

    2015-01-01

    In the present investigation, the possible effects of the expansion of the Universe on systems bonded either by gravitational or electromagnetic forces, are reconsidered. It will be shown that the acceleration (positive or negative) of the expanding background, is the determinant factor affecting planetary orbits and atomic sizes. In the presently accepted cosmology (ΛCDM) all bonded systems are expanding at a decreasing rate that tends to be zero as the universe enters in a de Sitter phase. It is worth mentioning that the estimated expansion rates are rather small and they can be neglected for all practical purposes.

  11. Antibacterial Activity of Commercial Dentine Bonding Systems against E. faecalis–Flow Cytometry Study

    Directory of Open Access Journals (Sweden)

    Monika Lukomska-Szymanska

    2017-04-01

    Full Text Available Literature presents inconsistent results on the antibacterial activity of dentine bonding systems (DBS. Antibacterial activity of adhesive systems depends on several factors, including composition and acidity. Flow cytometry is a novel detection method to measure multiple characteristics of a single cell: total cell number, structural (size, shape, and functional parameters (viability, cell cycle. The LIVE/DEAD® BacLightTM bacterial viability assay was used to evaluate an antibacterial activity of DBS by assessing physical membrane disruption of bacteria mediated by DBS. Ten commercial DBSs: four total-etching (TE, four self-etching (SE and two selective enamel etching (SEE were tested. Both total-etching DBS ExciTE F and OptiBond Solo Plus showed comparatively low antibacterial activity against E. faecalis. The lowest activity of all tested TE systems showed Te-Econom Bond. Among SE DBS, G-ænial Bond (92.24% dead cells followed by Clearfil S3 Bond Plus (88.02% and Panavia F 2.0 ED Primer II (86.67% showed the highest antibacterial activity against E. faecalis, which was comparable to isopropranol (positive control. In the present study, self-etching DBS exhibited higher antimicrobial activity than tested total-etching adhesives against E. faecalis.

  12. Antibacterial Activity of Commercial Dentine Bonding Systems against E. faecalis-Flow Cytometry Study.

    Science.gov (United States)

    Lukomska-Szymanska, Monika; Konieczka, Magdalena; Zarzycka, Beata; Lapinska, Barbara; Grzegorczyk, Janina; Sokolowski, Jerzy

    2017-04-29

    Literature presents inconsistent results on the antibacterial activity of dentine bonding systems (DBS). Antibacterial activity of adhesive systems depends on several factors, including composition and acidity. Flow cytometry is a novel detection method to measure multiple characteristics of a single cell: total cell number, structural (size, shape), and functional parameters (viability, cell cycle). The LIVE/DEAD® BacLightTM bacterial viability assay was used to evaluate an antibacterial activity of DBS by assessing physical membrane disruption of bacteria mediated by DBS. Ten commercial DBSs: four total-etching (TE), four self-etching (SE) and two selective enamel etching (SEE) were tested. Both total-etching DBS ExciTE F and OptiBond Solo Plus showed comparatively low antibacterial activity against E. faecalis. The lowest activity of all tested TE systems showed Te-Econom Bond. Among SE DBS, G-ænial Bond (92.24% dead cells) followed by Clearfil S3 Bond Plus (88.02%) and Panavia F 2.0 ED Primer II (86.67%) showed the highest antibacterial activity against E. faecalis, which was comparable to isopropranol (positive control). In the present study, self-etching DBS exhibited higher antimicrobial activity than tested total-etching adhesives against E. faecalis.

  13. Murine gammaherpesvirus-68 expands, but does not activate, CD11b+ gr-1+ splenocytes in vivo

    Directory of Open Access Journals (Sweden)

    Nelson Daniel A

    2012-04-01

    Full Text Available Abstract Background Murine gammaherpesvirus 68 (HV-68 is an efficient pathogen, capable of infecting and establishing lifelong latency in rodents. While many studies have demonstrated the ability of this viral infection to modulate immune responses, a unifying mechanism for HV-68-induced subversion of a protective host response remains elusive. We questioned whether infection with HV-68 could expand a population of myeloid derived suppressor cells (MDSC as one mechanism for altering protective immunity. Methods Mice were infected with HV-68, with viral latency being established in these animals. At varying times post-infection, cells were isolated for detection of viral genomes, phenotyping of myeloid cell populations, and ex vivo analysis of suppressor activity of myeloid cells. Results CD11b + Gr-1+ myeloid cells accumulated in the spleens, but not the bone marrow, of HV-68 infected mice. These cells were predominantly Gr-1+ Ly-6 G+, and could be found to contain viral genomes. Increased levels of serum S100A8/A9 produced during viral infection were consistent with the expansion of these CD11b + Gr-1+ myeloid cells. Despite their expansion, these cells exhibited no increased arginase 1 or iNOS activity, and did not have the ability to suppress anti-CD3 antibody activated T lymphocyte responses. Conclusions We concluded that HV-68 infection was capable of expanding a population of myeloid cells which were phenotypically similar to MDSC. However these cells were not sufficiently activated during the establishment of viral latency to actively suppress T cell responses.

  14. Expanding voluntary active-learning opportunities for pharmacy students in a Respiratory Physiology Module.

    Science.gov (United States)

    Ernst, Hardy; Colthorpe, Kay

    2008-04-15

    To expand voluntary active-learning opportunities for bachelor of pharmacy students enrolled in a third-year human physiology and pharmacology course and determine whether the additional course components improved learning outcomes. Additional voluntary active-learning opportunities including a large-class tutorial, additional formative assessment, and an online discussion were added to the Respiratory Physiology Module of the course. Examination scores were compared with those from previous years. A questionnaire was administered to assess students' perception of the active-learning components. Mean examination scores increased from 69.3% +/- 24.4% in 2003 to 88.9% +/- 13.4% in 2004 and 86.9% +/- 17.6% in 2005, after the addition of the active-learning components. Students' overall perception of the value of the active-learning activities was positive. The addition of voluntary active-learning course components to a required pharmacy course resulted in improved student examination scores, and decreased failure rate, and were accomplished at low cost and with little additional staff time.

  15. Explicit consideration of spatial hydrogen bonding direction for activity coefficient prediction based on implicit solvation calculations.

    Science.gov (United States)

    Chen, Wei-Lin; Lin, Shiang-Tai

    2017-08-09

    The activity coefficient of a chemical in a mixture is important in understanding the thermodynamic properties and non-ideality of the mixture. The COSMO-SAC model based on the result of quantum mechanical implicit solvation calculations has been shown to provide reliable predictions of activity coefficients for mixed fluids. However, it is found that the prediction accuracy is in general inferior for associating fluids. Existing methods for describing the hydrogen-bonding interaction consider the strength of the interaction based only on the polarity of the screening charges, neglecting the fact that the formation of hydrogen bonds requires a specific orientation between the donor and acceptor pairs. In this work, we propose a new approach that takes into account the spatial orientational constraints in hydrogen bonds. Based on the Valence Shell Electron Pair Repulsion (VSEPR) theory, the molecular surfaces associated with the formation of hydrogen bonds are limited to those in the projection of the lone pair electrons of hydrogen bond acceptors, in addition to the polarity of the surface screening charges. Our results show that this new directional hydrogen bond approach, denoted as the COSMO-SAC(DHB) model, requires fewer universal parameters and is significantly more accurate and reliable compared to previous models for a variety of properties, including vapor-liquid equilibria (VLE), infinite dilution activity coefficient (IDAC) and water-octanol partition coefficient (K ow ).

  16. Cu-catalyzed cross-dehydrogenative coupling: A versatile strategy for C-C bond formations via the oxidative activation of sp3 C-H bonds

    Science.gov (United States)

    Li, Zhiping; Bohle, D. Scott; Li, Chao-Jun

    2006-06-01

    Cu-catalyzed cross-dehydrogenative coupling (CDC) methodologies were developed based on the oxidative activation of sp3 C-H bonds adjacent to a nitrogen atom. Various sp, sp2, and sp3 C-H bonds of pronucleophiles were used in the Cu-catalyzed CDC reactions. Based on these results, the mechanisms of the CDC reactions also are discussed. C-H activation | catalysis | Baylis-Hillman reaction | Mannich reaction | Friedel-Crafts reaction

  17. The anti-canine distemper virus activities of ex vivo-expanded canine natural killer cells.

    Science.gov (United States)

    Park, Ji-Yun; Shin, Dong-Jun; Lee, Soo-Hyeon; Lee, Je-Jung; Suh, Guk-Hyun; Cho, Duck; Kim, Sang-Ki

    2015-04-17

    Natural killer (NK) cells play critical roles in induction of antiviral effects against various viruses of humans and animals. However, few data on NK cell activities during canine distemper virus (CDV) infections are available. Recently, we established a culture system allowing activation and expansion of canine non-B, non-T, large granular NK lymphocytes from PBMCs of normal dogs. In the present study, we explored the ability of such expanded NK cells to inhibit CDV infection in vitro. Cultured CD3-CD5-CD21- NK cells produced large amounts of IFN-γ, exhibited highly upregulated expression of mRNAs encoding NK-cell-associated receptors, and demonstrated strong natural killing activity against canine tumor cells. Although the expanded NK cells were dose-dependently cytotoxic to both normal and CDV-infected Vero cells, CDV infection rendered Vero cells more susceptible to NK cells. Pretreatment with anti-CDV serum from hyperimmunized dogs enhanced the antibody-dependent cellular cytotoxicity (ADCC) of NK cells against CDV-infected Vero cells. The culture supernatants of NK cells, added before or after infection, dose-dependently inhibited both CDV replication and development of CDV-induced cytopathic effects (CPEs) in Vero cells. Anti-IFN-γ antibody neutralized the inhibitory effects of NK cell culture supernatants on CDV replication and CPE induction in Vero cells. Such results emphasize the potential significance of NK cells in controlling CDV infection, and indicate that NK cells may play roles both during CDV infection and in combating such infections, under certain conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. 29 CFR 2580.412-8 - The nature of the duties or activities to which the bonding requirement relates.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 9 2010-07-01 2010-07-01 false The nature of the duties or activities to which the bonding requirement relates. 2580.412-8 Section 2580.412-8 Labor Regulations Relating to Labor (Continued) EMPLOYEE... INCOME SECURITY ACT OF 1974 TEMPORARY BONDING RULES Scope and Form of the Bond § 2580.412-8 The nature of...

  19. Modification of Purine and Pyrimidine Nucleosides by Direct C-H Bond Activation

    Directory of Open Access Journals (Sweden)

    Yong Liang

    2015-03-01

    Full Text Available Transition metal-catalyzed modifications of the activated heterocyclic bases of nucleosides as well as DNA or RNA fragments employing traditional cross-coupling methods have been well-established in nucleic acid chemistry. This review covers advances in the area of cross-coupling reactions in which nucleosides are functionalized via direct activation of the C8-H bond in purine and the C5-H or C6-H bond in uracil bases. The review focuses on Pd/Cu-catalyzed couplings between unactivated nucleoside bases with aryl halides. It also discusses cross-dehydrogenative arylations and alkenylations as well as other reactions used for modification of nucleoside bases that avoid the use of organometallic precursors and involve direct C-H bond activation in at least one substrate. The scope and efficiency of these coupling reactions along with some mechanistic considerations are discussed.

  20. Shear bond strength to enamel after power bleaching activated by different sources.

    Science.gov (United States)

    Can-Karabulut, Deniz C; Karabulut, Baris

    2010-01-01

    The purpose of the present study was to evaluate enamel bond strength of a composite resin material after hydrogen peroxide bleaching, activated by a diode laser (LaserSmile), an ozone device (HealOzone), a light-emitting diode (BT Cool whitening system), and a quartz-Plus. Fifty extracted caries-free permanent incisors were used in this study. Thirty-eight percent hydrogen peroxidegel was applied to sound, flattened labial enamel surfaces and activated by different sources. Enamel surfaces that had received no treatment were used as control samples. Bonding agent was applied according to the manufacturer's instructions and the adhesion test was performed according to ISO/TS 11405. Statistical analysis showed significant influence of the different activation technique of hydrogen peroxide on shear bond strength to enamel (ANOVA, LSD, P < 0.05). The data in this vitro explorative study suggest the activation of hydrogen peroxide by different sources may further affect the shear bond strength of subsequent composite resin restoration to enamel. Within the limitations of this in vitro study, further studies examining the structural changes of activated hydrogen peroxide-treated enamel are needed. Due to the different activation methods; duration of light irradiation effects, longer time periods may be needed before application of adhesive restorations to enamel, compared with non-activated bleaching.

  1. Hormonal changes and couple bonding in consensual sadomasochistic activity.

    Science.gov (United States)

    Sagarin, Brad J; Cutler, Bert; Cutler, Nadine; Lawler-Sagarin, Kimberly A; Matuszewich, Leslie

    2009-04-01

    In two studies, 58 sadomasochistic (SM) practitioners provided physiological measures of salivary cortisol and testosterone (hormones associated with stress and dominance, respectively) and psychological measures of relationship closeness before and after participating in SM activities. Observed activities included bondage, sensory deprivation, a variety of painful and pleasurable stimulation, verbal and non-verbal communication, and expressions of caring and affection. During the scenes, cortisol rose significantly for participants who were bound, receiving stimulation, and following orders, but not for participants who were providing stimulation, orders, or structure. Female participants who were bound, receiving stimulation, and following orders also showed increases in testosterone during the scenes. Thereafter, participants who reported that their SM activities went well showed reductions in physiological stress (cortisol) and increases in relationship closeness. Among participants who reported that their SM activities went poorly, some showed decreases in relationship closeness whereas others showed increases. The increases in relationship closeness combined with the displays of caring and affection observed as part of the SM activities offer support for the modern view that SM, when performed consensually, has the potential to increase intimacy between participants.

  2. Galectin-9 activates and expands human T-helper 1 cells.

    Directory of Open Access Journals (Sweden)

    Marloes J M Gooden

    Full Text Available Galectin-9 (Gal-9 is known for induction of apoptosis in IFN-γ and IL-17 producing T-cells and amelioration of autoimmunity in murine models. On the other hand, Gal-9 induced IFN-γ positive T-cells in a sarcoma mouse model and in food allergy, suggesting that Gal-9 can have diametric effects on T-cell immunity. Here, we aimed to delineate the immunomodulatory effect of Gal-9 on human resting and ex vivo activated peripheral blood lymphocytes. Treatment of resting lymphocytes with low concentrations of Gal-9 (5-30 nM induced apoptosis in ∼60% of T-cells after 1 day, but activated the surviving T-cells. These viable T-cells started to expand after 4 days with up to 6 cell divisions by day 7 and an associated shift from naïve towards central memory and IFN-γ producing phenotype. In the presence of T-cell activation signals (anti-CD3/IL-2 Gal-9 did not induce T-cell expansion, but shifted the CD4/CD8 balance towards a CD4-dominated T-cell response. Thus, Gal-9 activates resting T-cells in the absence of typical T-cell activating signals and promotes their transition to a TH1/C1 phenotype. In the presence of T-cell activating signals T-cell immunity is directed towards a CD4-driven response by Gal-9. Thus, Gal-9 may specifically enhance reactive immunological memory.

  3. Diffusion Bonding Beryllium to Reduced Activation Ferritic Martensitic Steel: Development of Processes and Techniques

    Science.gov (United States)

    Hunt, Ryan Matthew

    Only a few materials are suitable to act as armor layers against the thermal and particle loads produced by magnetically confined fusion. These candidates include beryllium, tungsten, and carbon fiber composites. The armor layers must be joined to the plasma facing components with high strength bonds that can withstand the thermal stresses resulting from differential thermal expansion. While specific joints have been developed for use in ITER (an experimental reactor in France), including beryllium to CuCrZr as well as tungsten to stainless steel interfaces, joints specific to commercially relevant fusion reactors are not as well established. Commercial first wall components will likely be constructed front Reduced Activation Ferritic Martensitic (RAFM) steel, which will need to be coating with one of the three candidate materials. Of the candidates, beryllium is particularly difficult to bond, because it reacts during bonding with most elements to form brittle intermetallic compounds. This brittleness is unacceptable, as it can lead to interface crack propagation and delamination of the armor layer. I have attempted to overcome the brittle behavior of beryllium bonds by developing a diffusion bonding process of beryllium to RAFM steel that achieves a higher degree of ductility. This process utilized two bonding aids to achieve a robust bond: a. copper interlayer to add ductility to the joint, and a titanium interlayer to prevent beryllium from forming unwanted Be-Cu intermetallics. In addition, I conducted a series of numerical simulations to predict the effect of these bonding aids on the residual stress in the interface. Lastly, I fabricated and characterized beryllium to ferritic steel diffusion bonds using various bonding parameters and bonding aids. Through the above research, I developed a process to diffusion bond beryllium to ferritic steel with a 150 M Pa tensile strength and 168 M Pa shear strength. This strength was achieved using a Hot Isostatic

  4. Leukemia-associated activating mutation of Flt3 expands dendritic cells and alters T cell responses.

    Science.gov (United States)

    Lau, Colleen M; Nish, Simone A; Yogev, Nir; Waisman, Ari; Reiner, Steven L; Reizis, Boris

    2016-03-07

    A common genetic alteration in acute myeloid leukemia is the internal tandem duplication (ITD) in FLT3, the receptor for cytokine FLT3 ligand (FLT3L). Constitutively active FLT3-ITD promotes the expansion of transformed progenitors, but also has pleiotropic effects on hematopoiesis. We analyzed the effect of FLT3-ITD on dendritic cells (DCs), which express FLT3 and can be expanded by FLT3L administration. Pre-leukemic mice with the Flt3(ITD) knock-in allele manifested an expansion of classical DCs (cDCs) and plasmacytoid DCs. The expansion originated in DC progenitors, was cell intrinsic, and was further enhanced in Flt3(ITD/ITD) mice. The mutation caused the down-regulation of Flt3 on the surface of DCs and reduced their responsiveness to Flt3L. Both canonical Batf3-dependent CD8(+) cDCs and noncanonical CD8(+) cDCs were expanded and showed specific alterations in their expression profiles. Flt3(ITD) mice showed enhanced capacity to support T cell proliferation, including a cell-extrinsic expansion of regulatory T (T reg) cells. Accordingly, these mice restricted alloreactive T cell responses during graft-versus-host reaction, but failed to control autoimmunity without T reg cells. Thus, the FLT3-ITD mutation directly affects DC development, indirectly modulating T cell homeostasis and supporting T reg cell expansion. We hypothesize that this effect of FLT3-ITD might subvert immunosurveillance and promote leukemogenesis in a cell-extrinsic manner. © 2016 Lau et al.

  5. 78 FR 49761 - Agency Information Collection Activities: Application for Exportation of Articles Under Special Bond

    Science.gov (United States)

    2013-08-15

    ... DEPARTMENT OF HOMELAND SECURITY U.S. Customs and Border Protection Agency Information Collection Activities: Application for Exportation of Articles Under Special Bond AGENCY: U.S. Customs and Border... existing collection of information. SUMMARY: As part of its continuing effort to reduce paperwork and...

  6. 75 FR 61162 - Agency Information Collection Activities: Application for Exportation of Articles Under Special Bond

    Science.gov (United States)

    2010-10-04

    ... DEPARTMENT OF HOMELAND SECURITY U.S. Customs and Border Protection Agency Information Collection Activities: Application for Exportation of Articles Under Special Bond AGENCY: U.S. Customs and Border... existing information collection: 1651-0004. SUMMARY: U.S. Customs and Border Protection (CBP) of the...

  7. Si-H Bond Activation of Alkynylsilanes by Group 4 Metallocene Complexes

    Czech Academy of Sciences Publication Activity Database

    Lamač, Martin; Spannenberg, A.; Baumann, W.; Jiao, H.; Fischer, Ch.; Hansen, S.; Arndt, P.; Rosenthal, U.

    2010-01-01

    Roč. 132, č. 12 (2010), s. 4369-4380 ISSN 0002-7863 Institutional research plan: CEZ:AV0Z40400503 Keywords : Si-H bond activation * alkynylsilanes * metallocene complexes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 9.019, year: 2010

  8. Synergy of corrosion activity and defects in weld bonds

    Directory of Open Access Journals (Sweden)

    Michal Černý

    2004-01-01

    Full Text Available Presented work evaluates synergism of atmosphere corrosive action and material defects. These defects appear not only during particular technological process of connecting of structural material but also during cooling and up to hundreds hours afterwards. The multiplication of degradation impact of defects in joint welds and heat-affected zone caused by activity of atmosphere acidic medium is simulated in condensation chambers. The verification is realized by use of mechanical uniaxial tension loading and following fractographic and metalgraphic analysis.The metal plasticity is sufficient factor to eliminate thermal stress in tough metal (11 373. This is reflected in more homogenous weld root area (with no cracks. The corrosion influence of environment is in case of such specimens limited to very slight decrease of weld maximum load. The ultimate strength value decreases approximately for 20MPa only in contrast to dramatic strength decrease in case of 11 503 material. Before metalographic examination was observed surprisingly great value of load capacity of spot welds. These welds were not ruptured nor in a single case even during maximum length of corrosion exploitation. The consequent material analysis discovered high qualitative material and strength properties of this kind of joint.

  9. Bonding of Si wafers by surface activation method for the development of high efficiency high counting rate radiation detectors

    International Nuclear Information System (INIS)

    Kanno, Ikuo; Yamashita, Makoto; Onabe, Hideaki

    2006-01-01

    Si wafers with two different resistivities ranging over two orders of magnitude were bonded by the surface activation method. The resistivities of bonded Si wafers were measured as a function of annealing temperature. Using calculations based on a model, the interface resistivities of bonded Si wafers were estimated as a function of the measured resistivities of bonded Si wafers. With thermal treatment from 500degC to 900degC, all interfaces showed high resistivity, with behavior that was close to that of an insulator. Annealing at 1000degC decreased the interface resistivity and showed close to ideal bonding after thermal treatment at 1100degC. (author)

  10. Allogeneic lymphocyte-licensed DCs expand T cells with improved antitumor activity and resistance to oxidative stress and immunosuppressive factors

    Directory of Open Access Journals (Sweden)

    Chuan Jin

    2014-01-01

    Full Text Available Adoptive T-cell therapy of cancer is a treatment strategy where T cells are isolated, activated, in some cases engineered, and expanded ex vivo before being reinfused to the patient. The most commonly used T-cell expansion methods are either anti-CD3/CD28 antibody beads or the “rapid expansion protocol” (REP, which utilizes OKT-3, interleukin (IL-2, and irradiated allogeneic feeder cells. However, REP-expanded or bead-expanded T cells are sensitive to the harsh tumor microenvironment and often short-lived after reinfusion. Here, we demonstrate that when irradiated and preactivated allosensitized allogeneic lymphocytes (ASALs are used as helper cells to license OKT3-armed allogeneic mature dendritic cells (DCs, together they expand target T cells of high quality. The ASAL/DC combination yields an enriched Th1-polarizing cytokine environment (interferon (IFN-γ, IL-12, IL-2 and optimal costimulatory signals for T-cell stimulation. When genetically engineered antitumor T cells were expanded by this coculture system, they showed better survival and cytotoxic efficacy under oxidative stress and immunosuppressive environment, as well as superior proliferative response during tumor cell killing compared to the REP protocol. Our result suggests a robust ex vivo method to expand T cells with improved quality for adoptive cancer immunotherapy.

  11. New Concept of C–H and C–C Bond Activation via Surface Organometallic Chemistry

    KAUST Repository

    Samantaray, Manoja

    2015-08-18

    In this chapter we describe the recent applications of well-defined oxidesupported metal alkyls/alkylidenes/alkylidynes and hydrides of group IV, V, and VI transition metals in the field of C–H and C–C bond activation. The activation of ubiquitous C–H and C–C bonds of paraffin is a long-standing challenge because of intrinsic low reactivity. There are many concepts derived from surface organometallic chemistry (SOMC): surface organometallic fragments are always intermediates in heterogeneous catalysis. The study of their synthesis and reactivity is a way to rationalize mechanism of heterogeneous catalysis and to achieve structure activity relationship. By surface organometallic chemistry one can enter any catalytic center by a reaction intermediate leading in fine to single site catalysts. With surface organometallic chemistry one can coordinate to the metal which can play a role in different elementary steps leading for example to C–H activation and Olefin metathesis. Because of the development of SOMC there is a lot of space for the improvement of homogeneous catalysis. After the 1997 discovery of alkane metathesis using silica-supported tantalum hydride by Basset et al. at low temperature (150ºC) the focus in this area was shifted to the discovery of more and more challenging surface complexes active in the application of C–H and C–C bond activation. Here we describe the evolution of well-defined metathesis catalyst with time as well as the effect of support on catalysis. We also describe here which metal–ligand combinations are responsible for a variety of C–H and C–C bond activation.

  12. The active site of hen egg-white lysozyme: flexibility and chemical bonding

    International Nuclear Information System (INIS)

    Held, Jeanette; Smaalen, Sander van

    2014-01-01

    Chemical bonding at the active site of lysozyme is analyzed on the basis of a multipole model employing transferable multipole parameters from a database. Large B factors at low temperatures reflect frozen-in disorder, but therefore prevent a meaningful free refinement of multipole parameters. Chemical bonding at the active site of hen egg-white lysozyme (HEWL) is analyzed on the basis of Bader’s quantum theory of atoms in molecules [QTAIM; Bader (1994 ▶), Atoms in Molecules: A Quantum Theory. Oxford University Press] applied to electron-density maps derived from a multipole model. The observation is made that the atomic displacement parameters (ADPs) of HEWL at a temperature of 100 K are larger than ADPs in crystals of small biological molecules at 298 K. This feature shows that the ADPs in the cold crystals of HEWL reflect frozen-in disorder rather than thermal vibrations of the atoms. Directly generalizing the results of multipole studies on small-molecule crystals, the important consequence for electron-density analysis of protein crystals is that multipole parameters cannot be independently varied in a meaningful way in structure refinements. Instead, a multipole model for HEWL has been developed by refinement of atomic coordinates and ADPs against the X-ray diffraction data of Wang and coworkers [Wang et al. (2007), Acta Cryst. D63, 1254–1268], while multipole parameters were fixed to the values for transferable multipole parameters from the ELMAM2 database [Domagala et al. (2012), Acta Cryst. A68, 337–351] . Static and dynamic electron densities based on this multipole model are presented. Analysis of their topological properties according to the QTAIM shows that the covalent bonds possess similar properties to the covalent bonds of small molecules. Hydrogen bonds of intermediate strength are identified for the Glu35 and Asp52 residues, which are considered to be essential parts of the active site of HEWL. Furthermore, a series of weak C

  13. The active site of hen egg-white lysozyme: flexibility and chemical bonding

    Energy Technology Data Exchange (ETDEWEB)

    Held, Jeanette, E-mail: jeanette.netzel@uni-bayreuth.de; Smaalen, Sander van [University of Bayreuth, D-95440 Bayreuth (Germany)

    2014-04-01

    Chemical bonding at the active site of lysozyme is analyzed on the basis of a multipole model employing transferable multipole parameters from a database. Large B factors at low temperatures reflect frozen-in disorder, but therefore prevent a meaningful free refinement of multipole parameters. Chemical bonding at the active site of hen egg-white lysozyme (HEWL) is analyzed on the basis of Bader’s quantum theory of atoms in molecules [QTAIM; Bader (1994 ▶), Atoms in Molecules: A Quantum Theory. Oxford University Press] applied to electron-density maps derived from a multipole model. The observation is made that the atomic displacement parameters (ADPs) of HEWL at a temperature of 100 K are larger than ADPs in crystals of small biological molecules at 298 K. This feature shows that the ADPs in the cold crystals of HEWL reflect frozen-in disorder rather than thermal vibrations of the atoms. Directly generalizing the results of multipole studies on small-molecule crystals, the important consequence for electron-density analysis of protein crystals is that multipole parameters cannot be independently varied in a meaningful way in structure refinements. Instead, a multipole model for HEWL has been developed by refinement of atomic coordinates and ADPs against the X-ray diffraction data of Wang and coworkers [Wang et al. (2007), Acta Cryst. D63, 1254–1268], while multipole parameters were fixed to the values for transferable multipole parameters from the ELMAM2 database [Domagala et al. (2012), Acta Cryst. A68, 337–351] . Static and dynamic electron densities based on this multipole model are presented. Analysis of their topological properties according to the QTAIM shows that the covalent bonds possess similar properties to the covalent bonds of small molecules. Hydrogen bonds of intermediate strength are identified for the Glu35 and Asp52 residues, which are considered to be essential parts of the active site of HEWL. Furthermore, a series of weak C

  14. The 11S Proteasomal Activator REGγ Impacts Polyglutamine-Expanded Androgen Receptor Aggregation and Motor Neuron Viability through Distinct Mechanisms

    Directory of Open Access Journals (Sweden)

    Jill M. Yersak

    2017-05-01

    Full Text Available Spinal and bulbar muscular atrophy (SBMA is caused by expression of a polyglutamine (polyQ-expanded androgen receptor (AR. The inefficient nuclear proteasomal degradation of the mutant AR results in the formation of nuclear inclusions containing amino-terminal fragments of the mutant AR. PA28γ (also referred to as REGγ is a nuclear 11S-proteasomal activator with limited proteasome activation capabilities compared to its cytoplasmic 11S (PA28α, PA28β counterparts. To clarify the role of REGγ in polyQ-expanded AR metabolism, we carried out genetic and biochemical studies in cell models of SBMA. Overexpression of REGγ in a PC12 cell model of SBMA increased polyQ-expanded AR aggregation and contributed to polyQ-expanded AR toxicity in the presence of dihydrotestosterone (DHT. These effects of REGγ were independent of its association with the proteasome and may be due, in part, to the decreased binding of polyQ-expanded AR by the E3 ubiquitin-ligase MDM2. Unlike its effects in PC12 cells, REGγ overexpression rescued transgenic SBMA motor neurons from DHT-induced toxicity in a proteasome binding-dependent manner, suggesting that the degradation of a specific 11S proteasome substrate or substrates promotes motor neuron viability. One potential substrate that we found to play a role in mutant AR toxicity is the splicing factor SC35. These studies reveal that, depending on the cellular context, two biological roles for REGγ impact cell viability in the face of polyQ-expanded AR; a proteasome binding-independent mechanism directly promotes mutant AR aggregation while a proteasome binding-dependent mechanism promotes cell viability. The balance between these functions likely determines REGγ effects on polyQ-expanded AR-expressing cells.

  15. Passive characterization and active testing of epoxy bonded regenerators for room temperature magnetic refrigeration

    DEFF Research Database (Denmark)

    Lei, Tian; Navickaité, Kristina; Engelbrecht, Kurt

    2017-01-01

    Epoxy bonded regenerators of both spherical and irregular La(Fe,Mn,Si)13Hy particles have been developed aiming at increasing the mechanical strength of active magnetic regenerators (AMR) loaded with brittle magnetocaloric materials and improving the flexibility of shaping the regenerator geometry......-layer AMR based on spherical particles is tested actively in a small reciprocating magnetic refrigerator, achieving a no-load temperature span of 16.8 °C using about 143 g of epoxy-bonded La(Fe,Mn,Si)13Hy materials. Simulations based on a one-dimensional (1D) AMR model are also implemented to validate...... and analyze the results from the active test....

  16. Site-selective and stereoselective functionalization of non-activated tertiary C-H bonds

    Science.gov (United States)

    Liao, Kuangbiao; Pickel, Thomas C.; Boyarskikh, Vyacheslav; Bacsa, John; Musaev, Djamaladdin G.; Davies, Huw M. L.

    2017-11-01

    The synthesis of complex organic compounds usually relies on controlling the reactions of the functional groups. In recent years, it has become possible to carry out reactions directly on the C-H bonds, previously considered to be unreactive. One of the major challenges is to control the site-selectivity because most organic compounds have many similar C-H bonds. The most well developed procedures so far rely on the use of substrate control, in which the substrate has one inherently more reactive C-H bond or contains a directing group or the reaction is conducted intramolecularly so that a specific C-H bond is favoured. A more versatile but more challenging approach is to use catalysts to control which site in the substrate is functionalized. p450 enzymes exhibit C-H oxidation site-selectivity, in which the enzyme scaffold causes a specific C-H bond to be functionalized by placing it close to the iron-oxo haem complex. Several studies have aimed to emulate this enzymatic site-selectivity with designed transition-metal catalysts but it is difficult to achieve exceptionally high levels of site-selectivity. Recently, we reported a dirhodium catalyst for the site-selective functionalization of the most accessible non-activated (that is, not next to a functional group) secondary C-H bonds by means of rhodium-carbene-induced C-H insertion. Here we describe another dirhodium catalyst that has a very different reactivity profile. Instead of the secondary C-H bond, the new catalyst is capable of precise site-selectivity at the most accessible tertiary C-H bonds. Using this catalyst, we modify several natural products, including steroids and a vitamin E derivative, indicating the applicability of this method of synthesis to the late-stage functionalization of complex molecules. These studies show it is possible to achieve site-selectivity at different positions within a substrate simply by selecting the appropriate catalyst. We hope that this work will inspire the design of

  17. Improvement of silicon direct bonding using surfaces activated by hydrogen plasma treatment

    CERN Document Server

    Choi, W B; Lee Jae Sik; Sung, M Y

    2000-01-01

    The plasma surface treatment, using hydrogen gas, of silicon wafers was studied as a pretreatment for silicon direct bonding. Chemical reactions of the hydrogen plasma with the surfaces were used for both surface activation and removal of surface contaminants. Exposure of the silicon wafers to the plasma formed an active oxide layer on the surface. This layer was hydrophilic. The surface roughness and morphology were examined as functions of the plasma exposure time and power. The surface became smoother with shorter plasma exposure time and lower power. In addition, the plasma surface treatment was very efficient in removing the carbon contaminants on the silicon surface. The value of the initial surface energy, as estimated by using the crack propagation method, was 506 mJ/M sup 2 , which was up to about three times higher than the value for the conventional direct bonding method using wet chemical treatments.

  18. Enantioselective synthesis of a PKC inhibitor via catalytic C-H bond activation.

    Science.gov (United States)

    Wilson, Rebecca M; Thalji, Reema K; Bergman, Robert G; Ellman, Jonathan A

    2006-04-13

    [reaction: see text] The syntheses of two biologically active molecules possessing dihydropyrroloindole cores (1 and 2) were completed using rhodium-catalyzed imine-directed C-H bond functionalization, with the second of these molecules containing a stereocenter that can be set with 90% ee during cyclization using chiral nonracemic phosphoramidite ligands. Catalytic decarbonylation and direct indole/maleimide coupling provide efficient access to 2.

  19. Z-H Bond Activation in (Di)hydrogen Bonding as a Way to Proton/Hydride Transfer and H2Evolution.

    Science.gov (United States)

    Belkova, Natalia V; Filippov, Oleg A; Shubina, Elena S

    2018-02-01

    The ability of neutral transition-metal hydrides to serve as a source of hydride ion H - or proton H + is well appreciated. The hydride ligands possessing a partly negative charge are proton accepting sites, forming a dihydrogen bond, M-H δ- ⋅⋅⋅ δ+ HX (M=transition metal or metalloid). On the other hand, some metal hydrides are able to serve as a proton source and give hydrogen bond of M-H δ+ ⋅⋅⋅X type (X=organic base). In this paper we analyse recent works on transition-metal and boron hydrides showing i) how formation of an intermolecular complex between the reactants changes the Z-H (M-H and X-H) bond polarity and ii) what is the implication of such activation in the mechanisms of hydrides reactions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. 26 CFR 1.103(n)-4T - Elective carryforward of unused private activity bond limit (temporary).

    Science.gov (United States)

    2010-04-01

    ... bond limit (temporary). 1.103(n)-4T Section 1.103(n)-4T Internal Revenue INTERNAL REVENUE SERVICE... Excluded from Gross Income § 1.103(n)-4T Elective carryforward of unused private activity bond limit... carryforward for any one or more projects described in A-5 of this § 1.103(n)-4T (carryforward projects). Q-2...

  1. Shock-induced electrical activity in polymeric solids. A mechanically induced bond scission model

    International Nuclear Information System (INIS)

    Graham, R.A.

    1979-01-01

    When polymeric solids are subjected to high-pressure shock loading, two anomalous electrical phenomena, shock-induced conduction and shock-induced polarization, are observed. The present paper proposes a model of mechanically induced bond scission within the shock front to account for the effects. An experimental study of shock-induced polarization in poly(pyromellitimide) (Vespel SP-1) is reported for shock compressions from 17 to 23% (pressures from 2.5 to 5.4 GPa). Poly(pyromellitimide) is found to be a strong generator of such polarization and the polarization is found to reflect an irreversible or highly hysteretic process. The present measurements are combined with prior measurements to establish a correlation between monomer structure and strength of shock-induced polarization; feeble signals are observed in the simpler monomer repeat units of poly(tetrafluoroethylene) and polyethylene while the strongest signals are observed in more complex monomers of poly(methyl methacrylate) and poly(pyromellitimide). It is also noted that there is an apparent correlation between shock-induced conduction and shock-induced polarization. Such shock-induced electrical activity is also found to be well correlated with the propensity for mechanical bond scission observed in experiments carried out in conventional mechanochemical studies. The bond scission model can account for characteristics observed for electrical activity in shock-loaded polymers and their correlation to monomer structure. Localization of elastic energy within the monomer repeat unit or along the main chain leads to the different propensities for bond scission and resulting shock-induced electrical activity

  2. Importance of the oxygen bond strength for catalytic activity in soot oxidation

    DEFF Research Database (Denmark)

    Christensen, Jakob M.; Grunwaldt, Jan-Dierk; Jensen, Anker D.

    2016-01-01

    energies for soot oxidation follow linear Brønsted-Evans-Polanyi relationships with the heat of oxygen chemisorption. Among the tested metal or metal oxide catalysts Co3O4 and CeO2 were nearest to the optimal bond strength in tight contact oxidation, while Cr2O3 was nearest to the optimum in loose contact......The oxygen bond strength on a catalyst, as measured by the heat of oxygen chemisorption, is observed to be a very important parameter for the activity of the catalyst in soot oxidation. With both intimate contact between soot and catalyst (tight contact) and with the solids stirred loosely together...... oxidation. The optimum of the volcano curve in loose contact is estimated to occur between the bond strengths of α-Fe2O3 and α-Cr2O3. Guided by an interpolation principle FeaCrbOx binary oxides were tested, and the activity of these oxides was observed to pass through an optimum for an FeCr2Ox binary oxide...

  3. Photosynthetic water oxidation: binding and activation of substrate waters for O-O bond formation.

    Science.gov (United States)

    Vinyard, David J; Khan, Sahr; Brudvig, Gary W

    2015-01-01

    Photosynthetic water oxidation occurs at the oxygen-evolving complex (OEC) of Photosystem II (PSII). The OEC, which contains a Mn4CaO5 inorganic cluster ligated by oxides, waters and amino-acid residues, cycles through five redox intermediates known as S(i) states (i = 0-4). The electronic and structural properties of the transient S4 intermediate that forms the O-O bond are not well understood. In order to gain insight into how water is activated for O-O bond formation in the S4 intermediate, we have performed a detailed analysis of S-state dependent substrate water binding kinetics taking into consideration data from Mn coordination complexes. This analysis supports a model in which the substrate waters are both bound as terminal ligands and react via a water-nucleophile attack mechanism.

  4. Sphalerite is a geochemical catalyst for carbon-hydrogen bond activation.

    Science.gov (United States)

    Shipp, Jessie A; Gould, Ian R; Shock, Everett L; Williams, Lynda B; Hartnett, Hilairy E

    2014-08-12

    Reactions among minerals and organic compounds in hydrothermal systems are critical components of the Earth's deep carbon cycle, provide energy for the deep biosphere, and may have implications for the origins of life. However, there is limited information as to how specific minerals influence the reactivity of organic compounds. Here we demonstrate mineral catalysis of the most fundamental component of an organic reaction: the breaking and making of a covalent bond. In the absence of mineral, hydrothermal reaction of cis- and trans-1,2-dimethylcyclohexane is extremely slow and generates many products. In the presence of sphalerite (ZnS), however, the reaction rate increases dramatically and one major product is formed: the corresponding stereoisomer. Isotope studies show that the sphalerite acts as a highly specific heterogeneous catalyst for activation of a single carbon-hydrogen bond in the dimethylcyclohexanes.

  5. Ultrafast studies of organometallic photochemistry: The mechanism of carbon-hydrogen bond activation in solution

    Energy Technology Data Exchange (ETDEWEB)

    Bromberg, S.E.

    1998-05-01

    When certain organometallic compounds are photoexcited in room temperature alkane solution, they are able to break or activate the C-H bonds of the solvent. Understanding this potentially practical reaction requires a detailed knowledge of the entire reaction mechanism. Because of the dynamic nature of chemical reactions, time-resolved spectroscopy is commonly employed to follow the important events that take place as reactants are converted to products. For the organometallic reactions examined here, the electronic/structural characteristics of the chemical systems along with the time scales for the key steps in the reaction make ultrafast UV/Vis and IR spectroscopy along with nanosecond Step-Scan FTIR spectroscopy the ideal techniques to use for this study. An initial study of the photophysics of (non-activating) model metal carbonyls centering on the photodissociation of M(CO){sub 6} (M = Cr, W, Mo) was carried out in alkane solutions using ultrafast IR spectroscopy. Next, picosecond UV/vis studies of the C-H bond activation reaction of Cp{sup *}M(CO){sub 2} (M = Rh, Ir), conducted in room temperature alkane solution, are described in an effort to investigate the origin of the low quantum yield for bond cleavage ({approximately}1%). To monitor the chemistry that takes place in the reaction after CO is lost, a system with higher quantum yield is required. The reaction of Tp{sup *}Rh(CO){sub 2} (Tp{sup *} = HB-Pz{sub 3}{sup *}, Pz{sup *} = 3,5-dimethylpyrazolyl) in alkanes has a quantum yield of {approximately}30%, making time resolved spectroscopic measurements possible. From ultrafast IR experiments, two subsequently formed intermediates were observed. The nature of these intermediates are discussed and the first comprehensive reaction mechanism for a photochemical C-H activating organometallic complex is presented.

  6. Active Thermochemical Tables: Sequential Bond Dissociation Enthalpies of Methane, Ethane, and Methanol and the Related Thermochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Ruscic, Branko

    2015-07-16

    Active Thermochemical Tables (ATcT) thermochemistry for the sequential bond dissociations of methane, ethane, and methanol systems were obtained by analyzing and solving a very large thermochemical network (TN). Values for all possible C–H, C–C, C–O, and O–H bond dissociation enthalpies at 298.15 K (BDE298) and bond dissociation energies at 0 K (D0) are presented. The corresponding ATcT standard gas-phase enthalpies of formation of the resulting CHn, n = 4–0 species (methane, methyl, methylene, methylidyne, and carbon atom), C2Hn, n = 6–0 species (ethane, ethyl, ethylene, ethylidene, vinyl, ethylidyne, acetylene, vinylidene, ethynyl, and ethynylene), and COHn, n = 4–0 species (methanol, hydroxymethyl, methoxy, formaldehyde, hydroxymethylene, formyl, isoformyl, and carbon monoxide) are also presented. The ATcT thermochemistry of carbon dioxide, water, hydroxyl, and carbon, oxygen, and hydrogen atoms is also included, together with the sequential BDEs of CO2 and H2O. The provenances of the ATcT enthalpies of formation, which are quite distributed and involve a large number of relevant determinations, are analyzed by variance decomposition and discussed in terms of principal contributions. The underlying reasons for periodic appearances of remarkably low and/or unusually high BDEs, alternating along the dissociation sequences, are analyzed and quantitatively rationalized. The present ATcT results are the most accurate thermochemical values currently available for these species.

  7. The biologically active form of the sea urchin egg receptor for sperm is a disulfide-bonded homo-multimer

    OpenAIRE

    1994-01-01

    Since many cell surface receptors exist in their active form as oligomeric complexes, we have investigated the subunit composition of the biologically active sperm receptor in egg plasma membranes from Strongylocentrotus purpuratus. Electrophoretic analysis of the receptor without prior reduction of disulfide bonds revealed that the surface receptor exists in the form of a disulfide-bonded multimer, estimated to be a tetramer. These findings are in excellent agreement with the fact that the N...

  8. Annulation of aromatic imines via directed C-H bond activation.

    Science.gov (United States)

    Thalji, Reema K; Ahrendt, Kateri A; Bergman, Robert G; Ellman, Jonathan A

    2005-08-19

    A directed C-H bond activation approach to the synthesis of indans, tetralins, dihydrofurans, dihydroindoles, and other polycyclic aromatic compounds is presented. Cyclization of aromatic ketimines and aldimines containing alkenyl groups tethered at the meta position relative to the imine directing group has been achieved using (PPh3)3RhCl (Wilkinson's catalyst). The cyclization of a range of aromatic ketimines and aldimines provides bi- and tricyclic ring systems with good regioselectivity. Different ring sizes and substitution patterns can be accessed through the coupling of monosubstituted, 1,1- or 1,2-disubstituted, and trisubstituted alkenes bearing both electron-rich and electron-deficient functionality.

  9. Highly efficient and enantioselective cyclization of aromatic imines via directed C-H bond activation.

    Science.gov (United States)

    Thalji, Reema K; Ellman, Jonathan A; Bergman, Robert G

    2004-06-16

    The first highly enantioselective catalytic reaction involving aromatic C-H bond activation is communicated. Enantioselective cyclization of aromatic ketimines containing alkenyl groups tethered at the meta position of an imine directing group has been achieved using 5 mol % [RhCl(coe)2]2 and 15 mol % of an (S)-binol-derived phosphoramidite ligand. Selectivities of up to 96% ee and up to quantitative yields were obtained. Moreover, the identified catalyst system enables the intramolecular alkylation reaction to be performed at temperatures 75 degrees C lower than our previously reported achiral system. The reaction can even be performed at room temperature for one of the optimal substrates.

  10. Selective molecular recognition, C-H bond activation, and catalysis in nanoscale reaction vessels

    Energy Technology Data Exchange (ETDEWEB)

    Fiedler, Dorothea; Leung, Dennis H.; Raymond, Kenneth N.; Bergman, Robert G.

    2004-11-27

    Supramolecular chemistry represents a way to mimic enzyme reactivity by using specially designed container molecules. We have shown that a chiral self-assembled M{sub 4}L{sub 6} supramolecular tetrahedron can encapsulate a variety of cationic guests, with varying degrees of stereoselectivity. Reactive iridium guests can be encapsulated and the C-H bond activation of aldehydes occurs, with the host cavity controlling the ability of substrates to interact with the metal center based upon size and shape. In addition, the host container can act as a catalyst by itself. By restricting reaction space and preorganizing the substrates into reactive conformations, it accelerates the sigmatropic rearrangement of enammonium cations.

  11. Two-dimensional gold nanostructures with high activity for selective oxidation of carbon–hydrogen bonds

    KAUST Repository

    Wang, Liang

    2015-04-22

    Efficient synthesis of stable two-dimensional (2D) noble metal catalysts is a challenging topic. Here we report the facile synthesis of 2D gold nanosheets via a wet chemistry method, by using layered double hydroxide as the template. Detailed characterization with electron microscopy and X-ray photoelectron spectroscopy demonstrates that the nanosheets are negatively charged and [001] oriented with thicknesses varying from single to a few atomic layers. X-ray absorption spectroscopy reveals unusually low gold–gold coordination numbers. These gold nanosheets exhibit high catalytic activity and stability in the solvent-free selective oxidation of carbon–hydrogen bonds with molecular oxygen.

  12. GMP-compliant, large-scale expanded allogeneic natural killer cells have potent cytolytic activity against cancer cells in vitro and in vivo.

    Directory of Open Access Journals (Sweden)

    Okjae Lim

    Full Text Available Ex vivo-expanded, allogeneic natural killer (NK cells can be used for the treatment of various types of cancer. In allogeneic NK cell therapy, NK cells from healthy donors must be expanded in order to obtain a sufficient number of highly purified, activated NK cells. In the present study, we established a simplified and efficient method for the large-scale expansion and activation of NK cells from healthy donors under good manufacturing practice (GMP conditions. After a single step of magnetic depletion of CD3(+ T cells, the depleted peripheral blood mononuclear cells (PBMCs were stimulated and expanded with irradiated autologous PBMCs in the presence of OKT3 and IL-2 for 14 days, resulting in a highly pure population of CD3(-CD16(+CD56(+ NK cells which is desired for allogeneic purpose. Compared with freshly isolated NK cells, these expanded NK cells showed robust cytokine production and potent cytolytic activity against various cancer cell lines. Of note, expanded NK cells selectively killed cancer cells without demonstrating cytotoxicity against allogeneic non-tumor cells in coculture assays. The anti-tumor activity of expanded human NK cells was examined in SCID mice injected with human lymphoma cells. In this model, expanded NK cells efficiently controlled lymphoma progression. In conclusion, allogeneic NK cells were efficiently expanded in a GMP-compliant facility and demonstrated potent anti-tumor activity both in vitro and in vivo.

  13. Nickel-Catalyzed C sp2 –C sp3 Cross-Coupling via C–O Bond Activation

    KAUST Repository

    Guo, Lin

    2016-06-13

    A new and efficient nickel-catalyzed alkylation of CAr-O electrophiles with B-alkyl-9-BBNs is described. The transformation is characterized by its functional group tolerance and provides a practical and versatile access to various Csp2-Csp3 bonds through Csp2-O substitution, without the restriction of β-hydride elimination. Moreover, the advantage of the newly developed method was demonstrated in a selective and sequential C-O bond activation process. © 2016 American Chemical Society.

  14. Selective Activation of C−H Bonds in a Cascade Process Combining Photochemistry and Biocatalysis

    Science.gov (United States)

    Zhang, Wuyuan; Burek, Bastien O.; Fernández‐Fueyo, Elena; Alcalde, Miguel

    2017-01-01

    Abstract Selective oxyfunctionalizations of inert C−H bonds can be achieved under mild conditions by using peroxygenases. This approach, however, suffers from the poor robustness of these enzymes in the presence of hydrogen peroxide as the stoichiometric oxidant. Herein, we demonstrate that inorganic photocatalysts such as gold–titanium dioxide efficiently provide H2O2 through the methanol‐driven reductive activation of ambient oxygen in amounts that ensure that the enzyme remains highly active and stable. Using this approach, the stereoselective hydroxylation of ethylbenzene to (R)‐1‐phenylethanol was achieved with high enantioselectivity (>98 % ee) and excellent turnover numbers for the biocatalyst (>71 000). PMID:28994504

  15. Manganese-Oxygen Intermediates in O-O Bond Activation and Hydrogen-Atom Transfer Reactions.

    Science.gov (United States)

    Rice, Derek B; Massie, Allyssa A; Jackson, Timothy A

    2017-11-21

    Biological systems capitalize on the redox versatility of manganese to perform reactions involving dioxygen and its derivatives superoxide, hydrogen peroxide, and water. The reactions of manganese enzymes influence both human health and the global energy cycle. Important examples include the detoxification of reactive oxygen species by manganese superoxide dismutase, biosynthesis by manganese ribonucleotide reductase and manganese lipoxygenase, and water splitting by the oxygen-evolving complex of photosystem II. Although these enzymes perform very different reactions and employ structurally distinct active sites, manganese intermediates with peroxo, hydroxo, and oxo ligation are commonly proposed in catalytic mechanisms. These intermediates are also postulated in mechanisms of synthetic manganese oxidation catalysts, which are of interest due to the earth abundance of manganese. In this Account, we describe our recent efforts toward understanding O-O bond activation pathways of Mn III -peroxo adducts and hydrogen-atom transfer reactivity of Mn IV -oxo and Mn III -hydroxo complexes. In biological and synthetic catalysts, peroxomanganese intermediates are commonly proposed to decay by either Mn-O or O-O cleavage pathways, although it is often unclear how the local coordination environment influences the decay mechanism. To address this matter, we generated a variety of Mn III -peroxo adducts with varied ligand environments. Using parallel-mode EPR and Mn K-edge X-ray absorption techniques, the decay pathway of one Mn III -peroxo complex bearing a bulky macrocylic ligand was investigated. Unlike many Mn III -peroxo model complexes that decay to oxo-bridged-Mn III Mn IV dimers, decay of this Mn III -peroxo adduct yielded mononuclear Mn III -hydroxo and Mn IV -oxo products, potentially resulting from O-O bond activation of the Mn III -peroxo unit. These results highlight the role of ligand sterics in promoting the formation of mononuclear products and mark an important

  16. Peel resistance characterization of localized polymer film bonding via thin film adhesive thermally activated by scanned CO2 laser

    Science.gov (United States)

    Dowding, Colin; Dowding, Robert; Griffiths, Jonathan; Lawrence, Jonathan

    2013-06-01

    Thermal laser polymer bonding is a non-contact process for the joining of polymer laminates using thermally activated adhesives. Conventional, contact based bonding techniques suffer from mechanical wear, geometric inflexibility and poor energy efficiency. The application of lasers offers the potential for highly localized delivery of energy and increased process flexibility whilst achieving controlled and repeatable bonding of polymer laminates in a contact free process. Unlike previously reported techniques, here it is reported that laser based non-contact bonding is both viable and highly desirable due to the increased levels of control it affords the user. In this work, laser polymer bonding of 75 μm thick linear low density polyethylene (LLDPE) film backed with a thermally activated adhesive to a 640 μm thick polypropylene (PP) substrate was conducted using continuous wave 10.6 μm laser radiation and scanning galvanometric optics. The effect of laser power and scanning traverse speed on the peel resistance properties of the bonded polymer laminates is presented, with a threshold specific energy density for successful adhesive activation determined.

  17. Miniature PT Cryocooler Activated by Resonant Piezoelectric Compressor and Passive Warm Expander

    Science.gov (United States)

    Sobol, S.; Grossman, G.

    2017-12-01

    A novel type of PZT-based compressor operating at mechanical resonance, suitable for pneumatically-driven Stirling-type cryocoolers, was presented at CEC-ICMC 2015. The detailed concept, analytical model and the test results on the preliminary prototype were reported earlier and presented at ICC17. Despite some mismatch between the impedances and insufficient structural stiffness, this compressor demonstrated the feasibility to drive our miniature Pulse Tube cryocooler MTSa, operating at 103 Hz and requiring an average PV power of 11 W, filling pressure of 40 Bar and a pressure ratio of 1.3. At ICC19 the prototype of a miniature passive warm expander (WE) was presented. The WE mechanism included a phase shifting piston suspended on a silicone diaphragm, a mass element, and a viscous damping system. Several technical drawbacks prevented perfect matching between the WE and MTSa; however, the presented prototype proved the ability to create any flow-to-pressure phase appropriate for a PT cryocooler. This paper concentrates on integration of the MTSa cryocooler with the recently modified PZT compressor operating at corrected mechanical resonance and the modified WE, which was also updated recently to match the MTSa requirements.

  18. N-heterocyclic carbene gold(I) and copper(I) complexes in C-H bond activation.

    Science.gov (United States)

    Gaillard, Sylvain; Cazin, Catherine S J; Nolan, Steven P

    2012-06-19

    Environmental concerns have and will continue to have a significant role in determining how chemistry is carried out. Chemists will be challenged to develop new, efficient synthetic processes that have the fewest possible steps leading to a target molecule, the goal being to decrease the amount of waste generated and reduce energy use. Along this path, chemists will need to develop highly selective reactions with atom-economical pathways producing nontoxic byproduct. In this context, C-H bond activation and functionalization is an extremely attractive method. Indeed, for most organic transformations, the presence of a reactive functionality is required. In Total Synthesis, the "protection and deprotection" approach with such reactive groups limits the overall yield of the synthesis, involves the generation of significant chemical waste, costs energy, and in the end is not as green as one would hope. In turn, if a C-H bond functionalization were possible, instead of the use of a prefunctionalized version of the said C-H bond, the number of steps in a synthesis would obviously be reduced. In this case, the C-H bond can be viewed as a dormant functional group that can be activated when necessary during the synthetic strategy. One issue increasing the challenge of such a desired reaction is selectivity. The cleavage of a C-H bond (bond dissociation requires between 85 and 105 kcal/mol) necessitates a high-energy species, which could quickly become a drawback for the control of chemo-, regio-, and stereoselectivity. Transition metal catalysts are useful reagents for surmounting this problem; they can decrease the kinetic barrier of the reaction yet retain control over selectivity. Transition metal complexes also offer important versatility in having distinct pathways that can lead to activation of the C-H bond. An oxidative addition of the metal in the C-H bond, and a base-assisted metal-carbon bond formation in which the base can be coordinated (or not) to the metal

  19. CFC/Cu bond damage in actively cooled plasma facing components

    International Nuclear Information System (INIS)

    Schlosser, J; Martin, E; Henninger, C; Boscary, J; Camus, G; Escourbiac, F; Leguillon, D; Missirlian, M; Mitteau, R

    2007-01-01

    Carbon fibre composite (CFC) armours have been successfully used for actively cooled plasma facing components (PFCs) of the Tore Supra (TS) tokamak. They were also selected for the divertor of the stellarator W7-X under construction and for the vertical target of the ITER divertor. In TS and W7-X a flat tile design for heat fluxes of 10 MW m -2 has been chosen. To predict the lifetime of such PFCs, it is necessary to analyse the damage mechanisms and to model the damage propagation when the component is exposed to thermal cycling loads. Work has been performed to identify a constitutive law for the CFC and parameters to model crack propagation from the edge singularity. The aim is to predict damage rates and to propose geometric or material improvements to increase the strength and the lifetime of the interfacial bond. For ITER a tube-in-tile concept (monoblock), designed to sustain heat fluxes up to 20 MW m -2 , has been developed. The optimization of the CFC/Cu bond, proposed for flat tiles, could be adopted for the monoblock concept

  20. Fingolimod induces BAFF and expands circulating transitional B cells without activating memory B cells and plasma cells in multiple sclerosis.

    Science.gov (United States)

    Miyazaki, Yusei; Niino, Masaaki; Takahashi, Eri; Suzuki, Masako; Mizuno, Masanori; Hisahara, Shin; Fukazawa, Toshiyuki; Amino, Itaru; Nakano, Fumihito; Nakamura, Masakazu; Akimoto, Sachiko; Minami, Naoya; Fujiki, Naoto; Doi, Shizuki; Shimohama, Shun; Terayama, Yasuo; Kikuchi, Seiji

    2018-02-01

    Patients with multiple sclerosis (MS) who are treated with fingolimod have an increased proportion of transitional B cells in the circulation, but the underlying mechanism is not known. We hypothesized that B cell-activating factor of the tumor necrosis factor family (BAFF) is involved in the process. Compared with healthy controls and untreated MS patients, fingolimod-treated MS patients had significantly higher serum concentrations of BAFF, which positively correlated with the proportions and the absolute numbers of transitional B cells in blood. Despite the elevated concentrations of BAFF in fingolimod-treated MS patients, serum levels of soluble transmembrane activator and calcium-modulating cyclophilin ligand interactor, and B cell maturation antigen were not elevated. Our results show that fingolimod induces BAFF in the circulation and expands transitional B cells, but does not activate memory B cells or plasma cells in MS, which is favorable for the treatment of this disease. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Expanding the agenda for research on the physically active aging body.

    Science.gov (United States)

    Phoenix, Cassandra; Grant, Bevan

    2009-07-01

    In this article, the authors consider the different approaches that can be used to examine the relationship between physical activity and aging. They propose that much is to be gained in our awareness of this dynamic relationship by drawing on multiple forms of knowledge that can generate diverse understandings regarding the impact of physical activity on physiological, psychological, and social aspects of aging. Accordingly, 3 different approaches to understanding the older physically (in)active body are presented. These are categorized as (a) the objective truth about the aging, physically active body; (b) the subjective truth about the aging, physically active body; and (c) "tales" about the aging, physically active body. The key underpinnings, strengths, and weaknesses of each approach are outlined. A number of examples from the literature are also offered to demonstrate where and how each approach has been used to contribute to our understanding about older people and physical activity. The more thorough, multidisciplinary, and wide spanning our knowledge of the aging, active body is, the more informed we might become in every dimension of its existence.

  2. Serine Proteolytic Pathway Activation Reveals an Expanded Ensemble of Wound Response Genes in Drosophila

    Science.gov (United States)

    Patterson, Rachel A.; Juarez, Michelle T.; Hermann, Anita; Sasik, Roman; Hardiman, Gary; McGinnis, William

    2013-01-01

    After injury to the animal epidermis, a variety of genes are transcriptionally activated in nearby cells to regenerate the missing cells and facilitate barrier repair. The range and types of diffusible wound signals that are produced by damaged epidermis and function to activate repair genes during epidermal regeneration remains a subject of very active study in many animals. In Drosophila embryos, we have discovered that serine protease function is locally activated around wound sites, and is also required for localized activation of epidermal repair genes. The serine protease trypsin is sufficient to induce a striking global epidermal wound response without inflicting cell death or compromising the integrity of the epithelial barrier. We developed a trypsin wounding treatment as an amplification tool to more fully understand the changes in the Drosophila transcriptome that occur after epidermal injury. By comparing our array results with similar results on mammalian skin wounding we can see which evolutionarily conserved pathways are activated after epidermal wounding in very diverse animals. Our innovative serine protease-mediated wounding protocol allowed us to identify 8 additional genes that are activated in epidermal cells in the immediate vicinity of puncture wounds, and the functions of many of these genes suggest novel genetic pathways that may control epidermal wound repair. Additionally, our data augments the evidence that clean puncture wounding can mount a powerful innate immune transcriptional response, with different innate immune genes being activated in an interesting variety of ways. These include puncture-induced activation only in epidermal cells in the immediate vicinity of wounds, or in all epidermal cells, or specifically in the fat body, or in multiple tissues. PMID:23637905

  3. Serine proteolytic pathway activation reveals an expanded ensemble of wound response genes in Drosophila.

    Directory of Open Access Journals (Sweden)

    Rachel A Patterson

    Full Text Available After injury to the animal epidermis, a variety of genes are transcriptionally activated in nearby cells to regenerate the missing cells and facilitate barrier repair. The range and types of diffusible wound signals that are produced by damaged epidermis and function to activate repair genes during epidermal regeneration remains a subject of very active study in many animals. In Drosophila embryos, we have discovered that serine protease function is locally activated around wound sites, and is also required for localized activation of epidermal repair genes. The serine protease trypsin is sufficient to induce a striking global epidermal wound response without inflicting cell death or compromising the integrity of the epithelial barrier. We developed a trypsin wounding treatment as an amplification tool to more fully understand the changes in the Drosophila transcriptome that occur after epidermal injury. By comparing our array results with similar results on mammalian skin wounding we can see which evolutionarily conserved pathways are activated after epidermal wounding in very diverse animals. Our innovative serine protease-mediated wounding protocol allowed us to identify 8 additional genes that are activated in epidermal cells in the immediate vicinity of puncture wounds, and the functions of many of these genes suggest novel genetic pathways that may control epidermal wound repair. Additionally, our data augments the evidence that clean puncture wounding can mount a powerful innate immune transcriptional response, with different innate immune genes being activated in an interesting variety of ways. These include puncture-induced activation only in epidermal cells in the immediate vicinity of wounds, or in all epidermal cells, or specifically in the fat body, or in multiple tissues.

  4. Annulation of Aromatic Imines via Directed C-H BondActivation

    Energy Technology Data Exchange (ETDEWEB)

    Thalji, Reema K.; Ahrendt, Kateri A.; Bergman, Robert G.; Ellman,Jonathan A.

    2005-04-14

    A directed C-H bond activation approach to the synthesis of indans, tetralins, dihydrofurans, dihydroindoles, and other polycyclic aromatic compounds is presented. Cyclization of aromatic ketimines and aldimines containing alkenyl groups tethered at the meta position relative to the imine directing group has been achieved using (PPh{sub 3}){sub 3}RhCl (Wilkinson's catalyst). The cyclization of a range of aromatic ketimines and aldimines provides bi- and tricyclic ring systems with good regioselectivity. Different ring sizes and substitution patterns can be accessed through the coupling of monosubstituted, 1,1- or 1,2-disubstituted, and trisubstituted alkenes bearing both electron-rich and electron-deficient functionality.

  5. Annealing effects on recombinative activity of nickel at direct silicon bonded interface

    International Nuclear Information System (INIS)

    Kojima, Takuto; Ohshita, Yoshio; Yamaguchi, Masafumi

    2015-01-01

    By performing capacitance transient analyses, the recombination activity at a (110)/(100) direct silicon bonded (DSB) interface contaminated with nickel diffused at different temperatures, as a model of grain boundaries in multicrystalline silicon, was studied. The trap level depth from the valence band, trap density of states, and hole capture cross section peaked at an annealing temperature of 300 °C. At temperatures ⩾400 °C, the hole capture cross section increased with temperature, but the density of states remained unchanged. Further, synchrotron-based X-ray analyses, microprobe X-ray fluorescence (μ-XRF), and X-ray absorption near edge structure (XANES) analyses were performed. The analysis results indicated that the chemical phase after the sample was annealed at 200 °C was a mixture of NiO and NiSi 2

  6. Soil Moisture Active and Passive (SMAP) White-Painted Expanded Polystyrene (EPS) Radome Survivability Test

    Science.gov (United States)

    Mikhaylov, Rebecca; Kwack, Eug; Stegman, Matthew; Dawson, Douglas; Hoffman, Pamela

    2015-01-01

    NASA's SMAP Mission launched in January 2015 into a 685 km near-polar, sun-synchronous orbit. The SMAP instrument architecture incorporates an L-band radar and radiometer which share a common feedhorn and mesh reflector. The instrument rotates about the nadir axis at approximately 15 rpm, thereby providing a conically scanning wide swath antenna beam that is capable of achieving global coverage within three days. The radiometer and its associated electronics have tight thermal stability requirements in order to meet the required surface emittance measurement precision from space. Maintaining the thermal stabilities is quite challenging because the radiometer is located on a spinning platform that can either be in full sunlight or eclipse, and thus exposed to a highly transient environment. Stability requirements were met by integrating a light-weight Expanded Polystyrene (EPS) radome into the design to prevent solar illumination of the feed horn interior. The radome was painted white since the thermo-optical properties of bare sunlit EPS degrade rapidly over the three-year mission. Milling of the EPS and solvent within the white paint created cavities on the EPS surface which may introduce localized hot spots possibly violating the EPS glass transition temperature of 96degC and leading to structural integrity concerns. A three-day thermal test was conducted in a vacuum chamber to verify survivability of the radome during a simulated non-spin fault condition at end of mission. A portable solar simulator illuminated the test article and the beam irradiance was kept nearly constant during the entire 50 hour test, except during the first hour which simulated the expected 79degC on-orbit surface temperature of the radome. The test article survived based on the established pass criteria for three separate metrics: dimensional, optical property, and color. If any hot spots exist locally, they did not cause any observable permanent deformation when compared to pre- and

  7. The road to the first, fully active and more stable human insulin variant with an additional disulfide bond

    DEFF Research Database (Denmark)

    Vinther, Tine N.; Kjeldsen, Thomas B.; Jensen, Knud Jørgen

    2015-01-01

    Insulin, a small peptide hormone, is crucial in maintaining blood glucose homeostasis. The stability and activity of the protein is directed by an intricate system involving disulfide bonds to stabilize the active monomeric species and by their non-covalent oligomerization. All known insulin vari...

  8. Challenges encountered when expanding activated sludge models: a case study based on N2O production

    DEFF Research Database (Denmark)

    Snip, Laura; Boiocchi, Riccardo; Flores Alsina, Xavier

    2014-01-01

    It is common practice in wastewater engineering to extend standard activated sludge models (ASMs) with extra process equations derived from batch experiments. However, such experiments have often been performed under conditions different from the ones normally found in wastewater treatment plants......-scale activated sludge plant. Finally, the simulation results show large differences in oxygen uptake rates, nitritation rates and consequently the quantity of N2O emission (G(N2O)) using the different models......It is common practice in wastewater engineering to extend standard activated sludge models (ASMs) with extra process equations derived from batch experiments. However, such experiments have often been performed under conditions different from the ones normally found in wastewater treatment plants...

  9. Did volcanic activity of the Emeishan large igneous province expand in Wuchiapingian times?

    Science.gov (United States)

    Bagherpour, Borhan; Bucher, Hugo; Yuan, Dong-Xun; Shen, Shu-zhong; Leu, Marc; Zhang, Chao

    2017-04-01

    first drowning event has been related to subsidence phase prior to the ELIP volcanism (e.g. Sun et al., 2010). The strikingly similar architecture of the Pingtang event with that of earlier Capitanian examples suggests a similar driving mechanism for these three phases of drowning/eruptive events. These results open up the possibility that ELIP volcanism extended into early Wuchiapingian times and further tests are currently under way. -Sun, Y., Lai, X., Wignall, P.B., Widdowson, M., Ali, J.R., Jiang, H., Wang, W., Yan, C., Bond, D.P.G., Védrine, S., 2010. Dating the onset and nature of the Middle Permian Emeishan large igneous province eruptions in SW China using conodont biostratigraphy and its bearing on mantle plume uplift models. Lithos 119, 20-33.

  10. Forum: Communication Activism Pedagogy. Expanding CAP's Interventionist Model and Developing Proper Learning Rubrics

    Science.gov (United States)

    Del Gandio, Jason

    2017-01-01

    For Frey and Palmer (2014), communication activism pedagogy (CAP) "teaches students how to use their communication knowledge and resources (e.g., theories, research methods, pedagogies, and other practices) to work with community members to intervene into and reconstruct unjust discourses in more just ways." The author of this response…

  11. Ceftaroline fosamil: a novel broad-spectrum cephalosporin with expanded anti-Gram-positive activity.

    Science.gov (United States)

    Biek, Donald; Critchley, Ian A; Riccobene, Todd A; Thye, Dirk A

    2010-11-01

    Ceftaroline fosamil is a novel cephalosporin with broad-spectrum activity against Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Streptococcus pneumoniae, and common Gram-negative organisms. The activity of ceftaroline against MRSA is attributed to its ability to bind to penicillin-binding protein (PBP) 2a with high affinity and inhibit the biochemical activity of PBP 2a more efficiently than other presently available β-lactams. The activity of ceftaroline against MRSA and the β-haemolytic streptococci makes it an attractive monotherapy agent for the treatment of complicated skin and skin structure infections (cSSSIs). Recent profiling and surveillance studies have shown that ceftaroline is active against contemporary skin pathogens collected from US and European medical centres in 2008. The mean free drug %T  >  MIC (percentage of time the drug concentration remains above the MIC) needed for stasis ranged from 26% for S. aureus to 39% for S. pneumoniae in the murine thigh infection model. Pharmacokinetic and pharmacodynamic target attainment predictions for 600 mg of ceftaroline fosamil every 12 h showed that the mean %T  >  MICs for which plasma free-drug concentrations exceeded an MIC of 1 and 2 mg/L were 71% and 51% of the dosing interval, respectively. For a 40% T  >  MIC target, the predicted attainments for infections due to pathogens for which ceftaroline MICs were 1 or 2 mg/L were 100% and 90%, respectively. Clinical and microbiological successes of ceftaroline fosamil in treating cSSSIs were demonstrated in two Phase III clinical studies, in which 96.8% of all baseline cSSSI isolates from the microbiologically evaluable population were inhibited by ceftaroline at ≤ 2 mg/L. Ceftaroline fosamil is a promising broad-spectrum agent for the treatment of cSSSIs.

  12. Activation of a σ-SnSn bond at copper, followed by double addition to an alkyne.

    Science.gov (United States)

    Lassauque, Nicolas; Gualco, Pauline; Mallet-Ladeira, Sonia; Miqueu, Karinne; Amgoune, Abderrahmane; Bourissou, Didier

    2013-09-18

    Many synthetically useful copper-catalyzed transformations involve the activation of apolar or weakly polar σ-bonds (E-H and E-E' bonds, with E = C, B, Si, Sn, etc.). Yet, little is known so far about the associated elementary steps, and it is highly desirable to gain better knowledge regarding the way σ-bonds can be activated by copper to help further development in this area. To this end, we became interested in investigating the coordination and activation of apolar or weakly polar σ-bonds at copper using chelating assistance. Here we report investigations of gold and copper complexes deriving from the diphosphine-stannane [Ph2P(o-C6H4)Me2Sn-SnMe2(o-C6H4)PPh2] 1. The σ-SnSn bond of 1 readily undergoes oxidative addition at both gold and copper, giving bis(stannyl) Au(+) and Cu(+) complexes 2 and 3. Coordination of 1 to CuBr leads to the neutral complex 4 which features more σ-SnSn complex character. The ability of complex 3 to undergo insertion reactions with alkynes was then examined. With methyl propiolate, a clean reaction occurred, and the bis-stannylated alkene copper complex 5 was isolated. The structures of ligand 1 and complexes 2-5 have been unambiguously determined by multinuclear NMR spectroscopy and crystallography. These results substantiate the ability of copper to promote the addition of apolar σ-bonds to CC multiple bonds via a 2e redox sequence and draw thereby an unprecedented parallel with the group 10 metals.

  13. Origin of the Ability of α-Fe2 O3 Mesopores to Activate C-H Bonds in Methane.

    Science.gov (United States)

    Dong, Bing; Han, Zhen; Zhang, Yongbo; Yu, Youyi; Kong, Aiguo; Shan, Yongkui

    2016-02-01

    Methane is a most abundant and inexpensive hydrocarbon feedstock for the production of chemicals and fuels. However, it is extremely difficult to directly convert methane to higher hydrocarbons because the C-H bonds in methane are the most stable C-H bonds of all hydrocarbons. The activation of the C-H bonds in methane by using an efficient and mild route remains a daunting challenge. Here, we show that the inner surface structures of the pore walls in mesoporous α-Fe 2 O 3 possess excellent catalytic performance for methane activation and convert C-H bonds into the C-O bonds in an O 2 atmosphere at 140 °C. We found that such unusual structures are mainly comprised of turbostratic ribbons and K crystal faces and have higher catalytic activity than the (110) plane. These results are without precedent in the history of catalysis chemistry and will provide a new pathway for designing and preparing highly efficient catalytic materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Expanding the calculation of activation volumes: Self-diffusion in liquid water.

    Science.gov (United States)

    Piskulich, Zeke A; Mesele, Oluwaseun O; Thompson, Ward H

    2018-04-07

    A general method for calculating the dependence of dynamical time scales on macroscopic thermodynamic variables from a single set of simulations is presented. The approach is applied to the pressure dependence of the self-diffusion coefficient of liquid water as a particularly useful illustration. It is shown how the activation volume associated with diffusion can be obtained directly from simulations at a single pressure, avoiding approximations that are typically invoked.

  15. Expanding the calculation of activation volumes: Self-diffusion in liquid water

    Science.gov (United States)

    Piskulich, Zeke A.; Mesele, Oluwaseun O.; Thompson, Ward H.

    2018-04-01

    A general method for calculating the dependence of dynamical time scales on macroscopic thermodynamic variables from a single set of simulations is presented. The approach is applied to the pressure dependence of the self-diffusion coefficient of liquid water as a particularly useful illustration. It is shown how the activation volume associated with diffusion can be obtained directly from simulations at a single pressure, avoiding approximations that are typically invoked.

  16. Effect of copper-sulphur bond on the DNA photo-cleavage activity of ...

    Indian Academy of Sciences (India)

    The Cu-N bond lengths are in the range of 1.968(3) to 2.158(4) Å. The Cu-S bond lengths of 2.599(2) and 2.705(2) Å are significantly long indicating weak covalent interaction between copper and sulphur atoms. The thiomethyl groups are cis to each other giving S-Cu-S angle of 75.82(5)°. The Cu-N(pyridyl) bond distances ...

  17. TIMP-3 recruits quiescent hematopoietic stem cells into active cell cycle and expands multipotent progenitor pool.

    Science.gov (United States)

    Nakajima, Hideaki; Ito, Miyuki; Smookler, David S; Shibata, Fumi; Fukuchi, Yumi; Morikawa, Yoshihiro; Ikeda, Yuichi; Arai, Fumio; Suda, Toshio; Khokha, Rama; Kitamura, Toshio

    2010-11-25

    Regulating transition of hematopoietic stem cells (HSCs) between quiescent and cycling states is critical for maintaining homeostasis of blood cell production. The cycling states of HSCs are regulated by the extracellular factors such as cytokines and extracellular matrix; however, the molecular circuitry for such regulation remains elusive. Here we show that tissue inhibitor of metalloproteinase-3 (TIMP-3), an endogenous regulator of metalloproteinases, stimulates HSC proliferation by recruiting quiescent HSCs into the cell cycle. Myelosuppression induced TIMP-3 in the bone marrow before hematopoietic recovery. Interestingly, TIMP-3 enhanced proliferation of HSCs and promoted expansion of multipotent progenitors, which was achieved by stimulating cell-cycle entry of quiescent HSCs without compensating their long-term repopulating activity. Surprisingly, this effect did not require metalloproteinase inhibitory activity of TIMP-3 and was possibly mediated through a direct inhibition of angiopoietin-1 signaling, a critical mediator for HSC quiescence. Furthermore, bone marrow recovery from myelosuppression was accelerated by over-expression of TIMP-3, and in turn, impaired in TIMP-3-deficient animals. These results suggest that TIMP-3 may act as a molecular cue in response to myelosuppression for recruiting dormant HSCs into active cell cycle and may be clinically useful for facilitating hematopoietic recovery after chemotherapy or ex vivo expansion of HSCs.

  18. Challenges encountered when expanding activated sludge models: a case study based on N2O production.

    Science.gov (United States)

    Snip, L J P; Boiocchi, R; Flores-Alsina, X; Jeppsson, U; Gernaey, K V

    2014-01-01

    It is common practice in wastewater engineering to extend standard activated sludge models (ASMs) with extra process equations derived from batch experiments. However, such experiments have often been performed under conditions different from the ones normally found in wastewater treatment plants (WWTPs). As a consequence, these experiments might not be representative for full-scale performance, and unexpected behaviour may be observed when simulating WWTP models using the derived process equations. In this paper we want to highlight problems encountered using a simplified case study: a modified version of the Activated Sludge Model No. 1 (ASM1) is upgraded with nitrous oxide (N2O) formation by ammonia-oxidizing bacteria. Four different model structures have been implemented in the Benchmark Simulation Model No. 1 (BSM1). The results of the investigations revealed two typical difficulties: problems related to the overall mathematical model structure and problems related to the published set of parameter values. The paper describes the model implementation incompatibilities, the variability in parameter values and the difficulties of reaching similar conditions when simulating a full-scale activated sludge plant. Finally, the simulation results show large differences in oxygen uptake rates, nitritation rates and consequently the quantity of N2O emission (GN2O) using the different models.

  19. Expanding subjectivities

    DEFF Research Database (Denmark)

    Lundgaard Andersen, Linda; Soldz, Stephen

    2012-01-01

    A major theme in recent psychoanalytic thinking concerns the use of therapist subjectivity, especially “countertransference,” in understanding patients. This thinking converges with and expands developments in qualitative research regarding the use of researcher subjectivity as a tool...... to understanding, especially but not exclusively in observational and interview-based studies. Psychodynamic or psychoanalytic approaches to research add an emphasis on unconscious motivational processes in both researchers and research participants that impact research experience and data. Building upon Anglo......-Saxon and continental traditions, this special issue provides examples of the use of researcher subjectivity, informed by psychoanalytic thinking, in expanding research understanding....

  20. Catalytic activity of autoantibodies toward myelin basic protein correlates with the scores on the multiple sclerosis expanded disability status scale.

    Science.gov (United States)

    Ponomarenko, Natalia A; Durova, Oxana M; Vorobiev, Ivan I; Belogurov, Alexey A; Telegin, Georgy B; Suchkov, Sergey V; Misikov, Victor K; Morse, Herbert C; Gabibov, Alexander G

    2006-02-28

    Autoantibodies toward myelin basic protein (MBP) evidently emerge in sera and cerebrospinal fluid of the patients with multiple sclerosis (MS), as well as in a MS rodent model, i.e., experimental autoimmune encephalomyelitis (EAE). The studies of the last two decades have unveiled somewhat controversial data on the diagnostic applicability of anti-MBP autoantibodies as a disease' marker. Here, we present the results of new functional analysis of the anti-MBP autoantibodies isolated from MS (in patients) and EAE (in mice) sera, based on their proteolytic activity against the targeted autoantigen. The activity was shown to be the intrinsic property of the IgG molecule. No activity was found in the sera-derived antibody fraction of healthy donors and control mice. Sera of 24 patients with clinically proven MS at different stages of the disease, and 20 healthy controls were screened for the anti-MBP antibody-mediated proteolytic activity. The activity correlated with the scores on the MS expanded disability status scale (EDSS) (r(2)=0.85, P<0.001). Thus, the anti-MBP autoantibody-mediated proteolysis may be regarded as an additional marker of the disease progression.

  1. Active Metal Brazing and Adhesive Bonding of Titanium to C/C Composites for Heat Rejection System

    Science.gov (United States)

    Singh, M.; Shpargel, Tarah; Cerny, Jennifer

    2006-01-01

    Robust assembly and integration technologies are critically needed for the manufacturing of heat rejection system (HRS) components for current and future space exploration missions. Active metal brazing and adhesive bonding technologies are being assessed for the bonding of titanium to high conductivity Carbon-Carbon composite sub components in various shapes and sizes. Currently a number of different silver and copper based active metal brazes and adhesive compositions are being evaluated. The joint microstructures were examined using optical microscopy, and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). Several mechanical tests have been employed to ascertain the effectiveness of different brazing and adhesive approaches in tension and in shear that are both simple and representative of the actual system and relatively straightforward in analysis. The results of these mechanical tests along with the fractographic analysis will be discussed. In addition, advantages, technical issues and concerns in using different bonding approaches will also be presented.

  2. Expander Codes

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 1. Expander Codes - The Sipser–Spielman Construction. Priti Shankar. General Article Volume 10 ... Author Affiliations. Priti Shankar1. Department of Computer Science and Automation, Indian Institute of Science Bangalore 560 012, India.

  3. Modifications of the alpha,beta-double bond in chalcones only marginally affect the antiprotozoal activities

    DEFF Research Database (Denmark)

    Nielsen, S F; Kharazmi, A; Christensen, S B

    1998-01-01

    Methods for selective alkylation of chalcones in the alpha- or beta-position and for selective reduction of the alpha,beta-double bond have been developed. The antiparasitic potencies of the alpha,beta-double bond modified chalcones only differ marginally from the potencies of the parent chalcones...

  4. 75 FR 47608 - Agency Information Collection Activities: Application for Exportation of Articles under Special Bond

    Science.gov (United States)

    2010-08-06

    ... information collection requirement concerning the: Application for Exportation of Articles under Special Bond... information collection: Title: Application for Exportation of Articles under Special Bond. OMB Number: 1651... DEPARTMENT OF HOMELAND SECURITY U.S. Customs and Border Protection Agency Information Collection...

  5. Preparation and photocatalytic activity of chemically-bonded phosphate ceramics containing TiO2

    Science.gov (United States)

    Martins, Monize Aparecida; de Lima, Bruna de Oliveira; Ferreira, Leticia Patrício; Colonetti, Emerson; Feltrin, Jucilene; De Noni, Agenor

    2017-05-01

    Titanium dioxide was incorporated into chemically-bonded phosphate ceramic for use as photocatalytic inorganic coating. The coatings obtained were applied to unglazed ceramic tiles and cured at 350 °C. The surfaces were characterized by photocatalytic activity, determined in aqueous medium, based on the degradation of methylene blue dye. The effects of the percentage of TiO2 and the thickness of the layer on the photocatalytic efficiency were evaluated. The influence of the incorporation of TiO2 on the consolidation of the phosphate matrix coating was investigated using the wear resistance test. The crystalline phases of the coatings obtained were determined by XRD. The microstructure of the surfaces was analyzed by SEM. The thermal curing treatment did not cause a phase transition from anatase to rutile. An increase in the photocatalytic activity of the coating was observed with an increase in the TiO2 content. The dye degradation indices ranged from 14.9 to 44.0%. The photocatalytic efficiency was not correlated with the thickness of the coating layer deposited. The resistance to wear decreased with an increase in the TiO2 content. Comparison with a commercial photocatalytic ceramic coating indicated that there is a range of values for the TiO2 contents which offer potential for photocatalytic applications.

  6. Expanded insecticide catabolic activity gained by a single nucleotide substitution in a bacterial carbamate hydrolase gene.

    Science.gov (United States)

    Öztürk, Başak; Ghequire, Maarten; Nguyen, Thi Phi Oanh; De Mot, René; Wattiez, Ruddy; Springael, Dirk

    2016-12-01

    Carbofuran-mineralizing strain Novosphingobium sp. KN65.2 produces the CfdJ enzyme that converts the N-methylcarbamate insecticide to carbofuran phenol. Purified CfdJ shows a remarkably low K M towards carbofuran. Together with the carbaryl hydrolase CehA of Rhizobium sp. strain AC100, CfdJ represents a new protein family with several uncharacterized bacterial members outside the proteobacteria. Although both enzymes differ by only four amino acids, CehA does not recognize carbofuran as a substrate whereas CfdJ also hydrolyzes carbaryl. None of the CfdJ amino acids that differ from CehA were shown to be silent regarding carbofuran hydrolytic activity but one particular amino acid substitution, i.e., L152 to F152, proved crucial. CfdJ is more efficient in degrading methylcarbamate pesticides with an aromatic side chain whereas CehA is more efficient in degrading the oxime carbamate nematicide oxamyl. The presence of common flanking sequences suggest that the cfdJ gene is located on a remnant of the mobile genetic element Tnceh carrying cehA. Our results suggest that these enzymes can be acquired through horizontal gene transfer and can evolve to degrade new carbamate substrates by limited amino acid substitutions. We demonstrate that a carbaryl hydrolase can gain the additional capacity to degrade carbofuran by a single nucleotide transversion. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  7. C–H Bond activation of methane with gaseous [(CH3)Pt(L)]+ complexes (L = pyridine, bipyridine, and phenanthroline)

    Czech Academy of Sciences Publication Activity Database

    Butschke, B.; Schlangen, M.; Schwarz, H.; Schröder, Detlef

    62b, č. 3 (2007), s. 309-311 ISSN 0932-0776 Grant - others:Deutsche Forschungsgemeinschaft(DE) SFB546 Institutional research plan: CEZ:AV0Z40550506 Keywords : C-H bond activation * electrospray ionization * mass spectrometry * methane * platinum Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.770, year: 2007

  8. Unlocking the Electrocatalytic Activity of Chemically Inert Amorphous Carbon-Nitrogen for Oxygen Reduction: Discerning and Refactoring Chaotic Bonds

    DEFF Research Database (Denmark)

    Zhang, Caihong; Zhang, Wei; Wang, Dong

    2017-01-01

    Mild annealing enables inactive nitrogen (N)-doped amorphous carbon (a-C) films abundant with chaotic bonds prepared by magnetron sputtering to become effective for the oxygen reduction reaction (ORR) by virtue of generating pyridinic N. The rhythmic variation of ORR activity elaborates well on t...

  9. 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.

  10. Epoxy-bonded La(Fe,mn,si)13Hz As A Multi Layered Active Magnetic Regenerator

    DEFF Research Database (Denmark)

    Neves Bez, Henrique; Navickaité, Kristina; Lei, Tian

    2016-01-01

    of the material may break apart during operation. In this context, we studied epoxy-bonded La(Fe,Mn,Si)13Hz regenerators, in a small versatile active magnetic regeneration (AMR) test device with a 1.1 T permanent magnet source. The magnetocaloric material was in the form of packed irregular particles (250-500 µm......), which were mechanically held in place by an epoxy matrix connecting the particles, improving the mechanical integrity, while allowing a continuous porosity for the fluid flow. Water with 2 wt% ENTEK FNE as anti-corrosion additive was used as the heat transfer fluid for the epoxy-bonded regenerators...

  11. Chemical activation of molecules by metals: Experimental studies of electron distributions and bonding

    International Nuclear Information System (INIS)

    Lichtenberger, D.L.

    1991-10-01

    The formal relationship between measured molecular ionization energies and thermodynamic bond dissociation energies has been developed into a single equation which unifies the treatment of covalent bonds, ionic bonds, and partially ionic bonds. This relationship has been used to clarify the fundamental thermodynamic information relating to metal-hydrogen, metal-alkyl, and metal-metal bond energies. We have been able to obtain a direct observation and measurement of the stabilization energy provided by the agostic interaction of the C-H bond with the metal. The ionization energies have also been used to correlate the rates of carbonyl substitution reactions of (η 5 -C 5 H 4 X)Rh(CO) 2 complexes, and to reveal the electronic factors that control the stability of the transition state. The extent that the electronic features of these bonding interactions transfer to other chemical systems is being investigated in terms of the principle of additivity of ligand electronic effects. Specific examples under study include metal- phosphines, metal-halides, and metallocenes. Especially interesting has been the recent application of these techniques to the characterization of the soccer-ball shaped C 60 molecule, buckminsterfullerene, and its interaction with a metal surface. The high-resolution valence ionizations in the gas phase reveal the high symmetry of the molecule, and studies of thin films of C 60 reveal weak intermolecular interactions. Scanning tunneling and atomic force microscopy reveal the arrangement of spherical molecules on gold substrates, with significant delocalization of charge from the metal surface. 21 refs

  12. Electrical conduction of Si/indium tin oxide/Si junctions fabricated by surface activated bonding

    Science.gov (United States)

    Liang, Jianbo; Ogawa, Tomoki; Hara, Tomoya; Araki, Kenji; Kamioka, Takefumi; Shigekawa, Naoteru

    2018-02-01

    The electrical properties of n+-Si//indium tin oxide (ITO)/n+-Si, n+-Si//ITO/p+-Si, and p+-Si//ITO/n+-Si junctions fabricated by surface activated bonding (SAB) were investigated. The current-voltage (I-V) characteristics of n+-Si//ITO/n+-Si, n+-Si//ITO/p+-Si, and p+-Si//ITO/n+-Si junctions showed excellent linear properties. The interface resistances of n+-Si//ITO/n+-Si, n+-Si//ITO/p+-Si, and p+-Si//ITO/n+-Si junctions were found to be 0.030, 0.025, and 0.029 Ω·cm2, respectively, which are lower than required for concentrator photovoltaics. The interface resistances of all the junctions increased with increasing annealing temperature. The degradation of the interface resistance is lower in n+-Si//ITO/n+-Si junctions than in n+-Si//ITO/p+-Si and p+-Si//ITO/n+-Si junctions, when the annealing temperature is higher than 100 °C. These results demonstrate that the ITO thin film as an intermediate layer has high potential application for the connection of subcells in the fabrication of tandem solar cells.

  13. Hydrogen bonding effect between active site and protein environment on catalysis performance in H2-producing [NiFe] hydrogenases.

    Science.gov (United States)

    Qiu, Siyao; Azofra, Luis Miguel; MacFarlane, Douglas R; Sun, Chenghua

    2018-02-28

    The interaction between the active site and the surrounding protein environment plays a fundamental role in the hydrogen evolution reaction (HER) in [NiFe] hydrogenases. Our density functional theory (DFT) findings demonstrate that the reaction Gibbs free energy required for the rate determining step decreases by 7.1 kcal mol -1 when the surrounding protein environment is taken into account, which is chiefly due to free energy decreases for the two H + /e - addition steps (the so-called Ni-SIa to I1, and Ni-C to Ni-R), being the largest thermodynamic impediments of the whole reaction. The variety of hydrogen bonds (H-bonds) between the amino acids and the active site is hypothesised to be the main reason for such stability: H-bonds not only work as electrostatic attractive forces that influence the charge redistribution, but more importantly, they act as an electron 'pull' taking electrons from the active site towards the amino acids. Moreover, the electron 'pull' effect through H-bonds via the S - in cysteine residues shows a larger influence on the energy profile than that via the CN - ligands on Fe.

  14. Tast Force report on bonding and perpetual care of nuclear licensed activities

    International Nuclear Information System (INIS)

    Anon.

    1975-01-01

    Potential issues which should be considered prior to the adoption and implementation of a bonding or perpetual care program are examined. The following topics are discussed: problem definition; major processors; factors in setting the amount of a bond; waste handling licensees; ore refineries and mills; former AEC licensed facilities; other specific licenses; authority; states where it is deemed that amendment of existing statutes is necessary to authorize imposition of a bonding requirement for licenses; administration; and recommendations. The following appendices are included: summary of cost estimate to decontaminate the American Nuclear Company; report on 1974 national conference on radiation control workshop no. 3; suggested changes to state regulations; and suggested legislation for licensee bonding and perpetual care trust funds

  15. Effector T-cells are expanded in systemic lupus erythematosus patients with high disease activity and damage indexes.

    Science.gov (United States)

    Piantoni, S; Regola, F; Zanola, A; Andreoli, L; Dall'Ara, F; Tincani, A; Airo', P

    2018-01-01

    patients with no damage ( p = .01). In SLE patients an inverse correlation was found between the percentages of TREGs and those of TDEM ( p < .01) or CD4 + CD28- ( p < .01) T-cells. Conclusions CD4+ T-cell subpopulations displaying phenotype characteristics of effector lymphocytes are proportionally expanded in patients with active SLE and a higher damage index. These findings may suggest a role of effector T-cells in the pathogenesis of the disease and in the mechanisms of damage in SLE.

  16. Partition expanders

    Czech Academy of Sciences Publication Activity Database

    Gavinsky, Dmitry; Pudlák, Pavel

    2017-01-01

    Roč. 60, č. 3 (2017), s. 378-395 ISSN 1432-4350 R&D Projects: GA ČR GBP202/12/G061 Institutional support: RVO:67985840 Keywords : expanders * pseudo randomness * communication complexity Subject RIV: BA - General Mathematics OBOR OECD: Computer sciences, information science, bioinformathics (hardware development to be 2.2, social aspect to be 5.8) Impact factor: 0.645, year: 2016 http://link.springer.com/article/10.1007%2Fs00224-016-9738-5

  17. Partition expanders

    Czech Academy of Sciences Publication Activity Database

    Gavinsky, Dmitry; Pudlák, Pavel

    2017-01-01

    Roč. 60, č. 3 (2017), s. 378-395 ISSN 1432-4350 R&D Projects: GA ČR GBP202/12/G061 Institutional support: RVO:67985840 Keywords : expanders * pseudorandomness * communication complexity Subject RIV: BA - General Mathematics OBOR OECD: Computer sciences, information science, bioinformathics (hardware development to be 2.2, social aspect to be 5.8) Impact factor: 0.645, year: 2016 http://link.springer.com/article/10.1007%2Fs00224-016-9738-5

  18. Shear bond strength of metallic brackets photo-activated with light-emitting diode (LED at different exposure times

    Directory of Open Access Journals (Sweden)

    Emanuel Braga Rêgo

    2007-10-01

    Full Text Available The purpose of this study was to compare the shear bond strength of orthodontic metallic brackets photo-activated with two different light-curing sources at different exposure times: halogen light (XL 1500, 3M ESPE and LED light (Ortholux, 3M Unitek. Sixty bovine permanent lower incisors were inserted into PVC tubes containing plaster. The buccal surfaces were cleaned with pumice and water, and then etched with 37% phosphoric acid gel. The XT Primer bonding agent (3M Unitek was applied to the enamel surfaces and the metallic pre-coated brackets (Transbond APC II system, 3M Unitek were attached to upper central incisors. The teeth were randomly divided into four groups (n=15. In Group I (Control, halogen light was used for 40 seconds, while in Groups II, III, and IV were light-cured with LED light unit for 40, 10, and 5 seconds, respectively. The teeth were stored in distilled water at 37°C for 24 hours. The brackets were submitted to shear bond strength test in universal testing machine (Instron at a crosshead speed of 0.5 mm/minute. Shear bond strength means (MPa were 4.87 for Group I; 5.89 for Group II; 4.83 for Group III, and 4.39 for Group IV. Tukey's test detected no statistically significant differences among the groups regarding the shear bond strength (p>0.05. Neither of the types of light-curing sources or exposure times influenced the shear bond strength of metallic brackets.

  19. H-bonding networks of the distal residues and water molecules in the active site of Thermobifida fusca hemoglobin.

    Science.gov (United States)

    Nicoletti, Francesco P; Droghetti, Enrica; Howes, Barry D; Bustamante, Juan P; Bonamore, Alessandra; Sciamanna, Natascia; Estrin, Darío A; Feis, Alessandro; Boffi, Alberto; Smulevich, Giulietta

    2013-09-01

    The ferric form of truncated hemoglobin II from Thermobifida fusca (Tf-trHb) and its triple mutant WG8F-YB10F-YCD1F at neutral and alkaline pH, and in the presence of CN(-) have been characterized by resonance Raman spectroscopy, electron paramagnetic resonance spectroscopy, and molecular dynamics simulations. Tf-trHb contains three polar residues in the distal site, namely TrpG8, TyrCD1 and TyrB10. Whereas TrpG8 can act as a potential hydrogen-bond donor, the tyrosines can act as donors or acceptors. Ligand binding in heme-containing proteins is determined by a number of factors, including the nature and conformation of the distal residues and their capability to stabilize the heme-bound ligand via hydrogen-bonding and electrostatic interactions. Since both the RR Fe-OH(-) and Fe-CN(-) frequencies are very sensitive to the distal environment, detailed information on structural variations has been obtained. The hydroxyl ligand binds only the WT protein giving rise to two different conformers. In form 1 the anion is stabilized by H-bonds with TrpG8, TyrCD1 and a water molecule, in turn H-bonded to TyrB10. In form 2, H-bonding with TyrCD1 is mediated by a water molecule. Unlike the OH(-) ligand, CN(-) binds both WT and the triple mutant giving rise to two forms with similar spectroscopic characteristics. The overall results clearly indicate that H-bonding interactions both with distal residues and water molecules are important structural determinants in the active site of Tf-trHb. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Exploration of earth-abundant transition metals (Fe, Co, and Ni) as catalysts in unreactive chemical bond activations.

    Science.gov (United States)

    Su, Bo; Cao, Zhi-Chao; Shi, Zhang-Jie

    2015-03-17

    Activation of inert chemical bonds, such as C-H, C-O, C-C, and so on, is a very important area, to which has been drawn much attention by chemists for a long time and which is viewed as one of the most ideal ways to produce valuable chemicals. Under modern chemical bond activation logic, many conventionally viewed "inert" chemical bonds that were intact under traditional conditions can be reconsidered as novel functionalities, which not only avoids the tedious synthetic procedures for prefunctionalizations and the emission of undesirable wastes but also inspires chemists to create novel synthetic strategies in completely different manners. Although activation of "inert" chemical bonds using stoichiometric amounts of transition metals has been reported in the past, much more attractive and challenging catalytic transformations began to blossom decades ago. Compared with the broad application of late and noble transition metals in this field, the earth-abundant first-row transition-metals, such as Fe, Co, and Ni, have become much more attractive, due to their obvious advantages, including high abundance on earth, low price, low or no toxicity, and unique catalytic characteristics. In this Account, we summarize our recent efforts toward Fe, Co, and Ni catalyzed "inert" chemical bond activation. Our research first unveiled the unique catalytic ability of iron catalysts in C-O bond activation of both carboxylates and benzyl alcohols in the presence of Grignard reagents. The benzylic C-H functionalization was also developed via Fe catalysis with different nucleophiles, including both electron-rich arenes and 1-aryl-vinyl acetates. Cobalt catalysts also showed their uniqueness in both aromatic C-H activation and C-O activation in the presence of Grignard reagents. We reported the first cobalt-catalyzed sp(2) C-H activation/arylation and alkylation of benzo[h]quinoline and phenylpyridine, in which a new catalytic pathway via an oxidative addition process was demonstrated

  1. σ Bond activation through tunneling: formation of the boron hydride cations BHn(+) (n = 2, 4, 6).

    Science.gov (United States)

    Qiu, Yudong; Wu, Chia-Hua; Schaefer, Henry F; Allen, Wesley D; Agarwal, Jay

    2016-02-07

    The network of H2 additions to B(+) and subsequent insertion reactions serve as a tractable model for hydrogen storage in elementary boron-containing compounds. Here, they are investigated using state-of-the-art ab initio methods (up to CCSDTQ and cc-pCV6Z basis sets). The binding energies of H2 to HBH(+) (14.9 kcal mol(-1)) and HBH(H2)(+) (18.1 kcal mol(-1)) are determined to be much higher than those for B(H2)(+) (3.8 kcal mol(-1)), B(H2)2(+) (3.0 kcal mol(-1)), and B(H2)3(+) (2.5 kcal mol(-1)) at the CCSDTQ/CBS level of theory. These predictions are in agreement with the experiments of Kemper, Bushnell, Weis, and Bowers (J. Am. Chem. Soc., 1998, 120, 7577). Molecular orbital analyses show that the enhanced binding in HBH(H2)m(+) complexes originates from the strong interaction between the 1σu HOMO of HBH(+) and the 1σu LUMO of H2. For the insertion reactions B(H2)n(+) → HBH(H2)n-1(+), activation barriers are determined to be 58.3 kcal mol(-1) [Mk-MRCCSD(T)/CBS], 12.2 kcal mol(-1) (CCSDTQ/CBS) and 4.6 kcal mol(-1) (CCSDTQ/CBS) for n = 1, 2, and 3, respectively. After using theoretical results to remove tunneling effects from the experimental rate constants, new Arrhenius fits yield activation barriers of 4.6(3) kcal mol(-1) and 3.8(1) kcal mol(-1) for the BH6(+) and BD6(+) insertion reactions, respectively, which are in near perfect agreement with converged theoretical values (4.6 kcal mol(-1) and 3.9 kcal mol(-1)). These findings demonstrate that earlier Arrhenius fits considerably underestimate these barriers, and that quantum tunneling dominates the σ bond activation mechanism witnessed in previous experiments involving BH6(+).

  2. Investigation of E. coli bacteria inactivation by photocatalytic activity of TiO2 coated expanded polystyrene foam

    Science.gov (United States)

    Varnagiris, S.; Sakalauskaite, S.; Tuckute, S.; Lelis, M.; Daugelavicius, R.; Milcius, D.

    2017-03-01

    Photocatalytic properties of anatase and other TiO2 polymorphs are widely researched and applied in practical application. In current study TiO2 films on the plasma pre-treated expanded polystyrene (EPS) foam were deposited using magnetron sputtering technique. Main properties of the films were characterised using combination of XRD, XPS and SEM techniques. Photocatalytic properties of the observed crystalline anatase phase were tested by investigating bleaching of the methylene blue (MB) aqueous solution and by testing Escherichia coli (E. coli) viability after incubation under UV-B irradiation. E. coli viability experiments indicated that there are two mechanisms of E. coli bacteria inactivation. UV irradiation alone causes rapid damage to the outer membrane of E. coli bacteria. The second mechanism of E. coli inactivation is invoked only with synergistic combination of TiO2 and UV. Acting as photocatalyst TiO2 generates active radicals who initiate the chain peroxidation of organic molecules and within 45 min reduce E. coli bacteria viability by nearly 90%.

  3. Expanding Anti-Stokes Shifting in Triplet-Triplet Annihilation Upconversion for In Vivo Anticancer Prodrug Activation.

    Science.gov (United States)

    Huang, Ling; Zhao, Yang; Zhang, He; Huang, Kai; Yang, Jinyi; Han, Gang

    2017-11-13

    A strategy to expand anti-Stokes shifting from the far-red to deep-blue region in metal-free triplet-triplet annihilation upconversion (TTA-UC) is presented. The method is demonstrated by in vivo titration of the photorelease of an anticancer prodrug. This new TTA system has robust brightness and the longest anti-Stokes shift of any reported TTA system. TTA core-shell-structured prodrug delivery capsules that benefit from these properties were developed; they can operate with low-power density far-red light-emitting diode light. These capsules contain mesoporous silica nanoparticles preloaded with TTA molecules as the core, and amphiphilic polymers encapsulating anticancer prodrug molecules as the shell. When stimulated by far-red light, the intense TTA upconversion blue emission in the system activates the anticancer prodrug molecules and shows effective tumor growth inhibition in vivo. This work paves the way to new organic TTA upconversion techniques that are applicable to in vivo photocontrollable drug release and other biophotonic applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Removal of xenobiotics from effluent discharge by adsorption on zeolite and expanded clay: an alternative to activated carbon?

    Science.gov (United States)

    Tahar, A; Choubert, J M; Miège, C; Esperanza, M; Le Menach, K; Budzinski, H; Wisniewski, C; Coquery, M

    2014-04-01

    Xenobiotics such as pesticides and pharmaceuticals are an increasingly large problem in aquatic environments. A fixed-bed adsorption filter, used as tertiary stage of sewage treatment, could be a solution to decrease xenobiotics concentrations in wastewater treatment plants (WWTPs) effluent. The adsorption efficiency of two mineral adsorbent materials (expanded clay (EC) and zeolite (ZE)), both seen as a possible alternative to activated carbon (AC), was evaluated in batch tests. Experiments involving secondary treated domestic wastewater spiked with a cocktail of ten xenobiotics (eight pharmaceuticals and two pesticides) known to be poorly eliminated in conventional biological process were carried out. Removal efficiencies and partitions coefficients were calculated for two levels of initial xenobiotic concentration, i.e, concentrations lower to 10 μg/L and concentrations ranged from 100 to 1,000 μg/L. While AC was the most efficient adsorbent material, both alternative adsorbent materials showed good adsorption efficiencies for all ten xenobiotics (from 50 to 100 % depending on the xenobiotic/adsorbent material pair). For all the targeted xenobiotics, at lower concentrations, EC presented the best adsorption potential with higher partition coefficients, confirming the results in terms of removal efficiencies. Nevertheless, Zeolite presents virtually the same adsorption potential for both high and low xenobiotics concentrations to be treated. According to this first batch investigation, ZE and EC could be used as alternative absorbent materials to AC in WWTP.

  5. Status of the beryllium tile bonding qualification activities for the manufacturing of the ITER first wall

    Energy Technology Data Exchange (ETDEWEB)

    Mitteau, Raphaël, E-mail: Raphael.mitteau@iter.org [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Eaton, R.; Perez, G. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Zacchia, F.; Banetta, S.; Bellin, B. [Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Gervash, A.; Glazunov, D. [Efremov Research Institute, 189631 St. Petersburg (Russian Federation); Chen, J. [Southwestern Institute of Physics, Huangjing Road, Chengdu 610225 (China)

    2015-10-15

    The preparation of the manufacturing of the ITER first wall involves a qualification stage. The qualification aims at demonstrating that manufacturers can deliver the needed reliability and quality for the beryllium to copper bond, before the manufacturing can commence. The qualification is done on semi-prototype, containing relevant features relative to the beryllium armour (about 1/6 of the panel size). The qualification is done by the participating parties, firstly by a manufacturing semi-prototype and then by testing it under heat flux. One semi-prototype is manufactured and is being tested, and further from other manufacturers are still to come. The qualification programme is accompanied by bond defect investigations, which aim at defining defect acceptance criteria. Qualification and defect acceptance programme are supported by thermal and stress analyses, with good agreement regarding the thermal results, and some insights about the governing factors to bond damage.

  6. Insulin analog with additional disulfide bond has increased stability and preserved activity

    DEFF Research Database (Denmark)

    Vinther, Tine N.; Norrman, Mathias; Ribel, Ulla

    2013-01-01

    under high physical stress even though the C-terminus of the B-chain thought to be directly involved in fibril formation was not modified. Importantly, this analog was capable of forming hexamer upon Zn addition as typical for wild-type insulin and its crystal structure showed only minor deviations from...... (HI) structure. This insulin analog had increased affinity for the insulin receptor and apparently augmented glucodynamic potency in a normal rat model compared with HI. Addition of the disulfide bond also resulted in a 34.6°C increase in melting temperature and prevented insulin fibril formation...... bond may enhance insulin structural stability which would be highly desirable in a pharmaceutical use. To address this hypothesis, we designed insulin with an additional interchain disulfide bond in positions A10/B4 based on Cα-Cα distances, solvent exposure, and side-chain orientation in human insulin...

  7. Research on the Bond Anchorage Properties of Alkali-Activated Slag Cementitious Material

    Science.gov (United States)

    Zhu, J.; Zheng, W. Z.; Leng, Y. F.; Qin, C. Z.; Xu, Z. Z.

    2017-12-01

    By bond-anchorage property tests at 20°C ∼500°C, the distribution of shear stress between carbon fiber sheets and concrete at all levels of loading and anchorage lengths were measured, which means the bond lengths during CFRP sheets are pulled off at the same time when the concrete is torn and stripped were gotten. The failure modes were obtained. In addition, the failure loads were measured, and the calculated formulas of anchorage lengths were identified by fitting at high temperature. It can be seen that the anchorage lengths of carbon fiber sheets increase with increasing temperature at 20°C ∼100°C, the anchorage lengths of carbon fiber sheets decrease with increasing temperature at 100°C ∼500°C. Tests prove that AASCM has favorable high-temperature resistant and bond anchorage properties.

  8. Status of the beryllium tile bonding qualification activities for the manufacturing of the ITER first wall

    International Nuclear Information System (INIS)

    Mitteau, Raphaël; Eaton, R.; Perez, G.; Zacchia, F.; Banetta, S.; Bellin, B.; Gervash, A.; Glazunov, D.; Chen, J.

    2015-01-01

    The preparation of the manufacturing of the ITER first wall involves a qualification stage. The qualification aims at demonstrating that manufacturers can deliver the needed reliability and quality for the beryllium to copper bond, before the manufacturing can commence. The qualification is done on semi-prototype, containing relevant features relative to the beryllium armour (about 1/6 of the panel size). The qualification is done by the participating parties, firstly by a manufacturing semi-prototype and then by testing it under heat flux. One semi-prototype is manufactured and is being tested, and further from other manufacturers are still to come. The qualification programme is accompanied by bond defect investigations, which aim at defining defect acceptance criteria. Qualification and defect acceptance programme are supported by thermal and stress analyses, with good agreement regarding the thermal results, and some insights about the governing factors to bond damage.

  9. Bond strength of Epiphany™ Sealer combined with different adhesive systems photo-activated with LED and QTH

    Science.gov (United States)

    Minto, A. M. P.; Bandéca, M. C.; Borges, A. H.; Nadalin, M. R.; Thomé, L. H. C.

    2009-08-01

    The Epiphany™ Sealer is a new dual-curing resin-based sealer and has been introduced as an alternative to gutta-percha and traditional root canal sealers. The canal filling is claimed to create a seal with the dentinal tubules within the root canal system producing a ‘monoblock’ effect between the sealer and dentinal tubules. Therefore, considering the possibility to incorporate the others adhesive systems, it is important to study the bond strength of the resulting cement. Forty-eight root mandibular canines were sectioned 8-mm below CEJ. The dentine discs were prepared using a tapered diamond bur and irrigated with 1% NaOCl and 17% EDTA. Previous the application Epiphany™ Sealer, the Epiphany™ Primer, AdheSE, and One Up Bond F were applied to the root canal walls. The LED and QTH (Quartz Tungsten Halogen) were used to photo-activation during 45 s with power density of 400 and 720 mW/cm2, respectively. The specimens were performed on a universal testing machine at a cross-head speed of 1 mm/min until bond failure occurred. The force was recorded and the debonding values were used to calculate Push-out bond strength. The analysis of variance (ANOVA) and Tukey’s post-hoc tests showed significant statistical differences ( P light curing unit used including the power density, the polymerization characteristics of these resin-based filling materials, depending on the primer/adhesive used.

  10. The significance of disulfide bonding in biological activity of HB-EGF, a mutagenesis approach

    OpenAIRE

    Hoskins, J.T.; Zhou, Z.; Harding, P.A.

    2008-01-01

    A site-directed mutagenesis approach was taken to disrupt each of 3 disulfide bonds within human HB-EGF by substituting serine for both cysteine residues that contribute to disulfide bonding. Each HB-EGF disulfide analogue (HB-EGF-Cys/Ser108/121, HB-EGF-Cys/Ser116/132, and HB-EGF-Cys/Ser134/143) was cloned under the regulation of the mouse metallothionein (MT) promoter and stably expressed in mouse fibroblasts. HB-EGF immunoreactive proteins with Mr of 6.5, 21 and 24kDa were observed from lys...

  11. Activation of the Hg-C Bond of Methylmercury by [S2]-Donor Ligands.

    Science.gov (United States)

    Karri, Ramesh; Banerjee, Mainak; Chalana, Ashish; Jha, Kunal Kumar; Roy, Gouriprasanna

    2017-10-16

    Here we report that [S 2 ]-donor ligands Bmm OH , Bmm Me , and Bme Me bind rapidly and reversibly to the mercury centers of organomercurials, RHgX, and facilitate the cleavage of Hg-C bonds of RHgX to produce stable tetracoordinated Hg(II) complexes and R 2 Hg. Significantly, the rate of cleavage of Hg-C bonds depends critically on the X group of RHgX (X = BF 4 - , Cl - , I - ) and the [S 2 ]-donor ligands used to induce the Hg-C bonds. For instance, the initial rate of cleavage of the Hg-C bond of MeHgI induced by Bme Me is almost 2-fold higher than the initial rate obtained by Bmm OH or Bmm Me , indicating that the spacer between the two imidazole rings of [S 2 ]-donor ligands plays a significant role here in the cleavage of Hg-C bonds. Surprisingly, we noticed that the initial rate of cleavage of the Hg-C bond of MeHgI induced by Bme Me (or Bmm Me ) is almost 10-fold and 100-fold faster than the cleavage of Hg-C bonds of MeHgCl and [MeHg]BF 4 respectively, under identical reaction conditions, suggesting that the Hg-C bond of [MeHg]BF 4 is highly inert at room temperature (21 °C). We also show here that the nature of the final stable cleaved products, i.e. Hg(II) complexes, depends on the X group of RHgX and the [S 2 ]-donor ligands. For instance, the reaction of Bmm Me with MeHgCl (1:1 molar ratio) afforded the formation of the 16-membered metallacyclic dinuclear mercury compound (Bmm Me ) 2 Hg 2 Cl 4 , in which the two Cl atoms are located inside the ring, whereas due to the large size of the I atom, a similar reaction with MeHgI yielded polymeric [(Bmm Me ) 2 HgI 2 ] m ·(MeHgI) n . However, the treatment of Bmm Me with ionic [RHg]BF 4 led to the formation of the tetrathione-coordinated mononuclear mercury compound [(Bmm Me ) 2 Hg](BF 4 ) 2 , where BF 4 - serves as a counteranion.

  12. Vapour-induced solid-state C-H bond activation for the clean synthesis of an organopalladium biothiol sensor.

    Science.gov (United States)

    Monas, Andrea; Užarević, Krunoslav; Halasz, Ivan; Kulcsár, Marina Juribašić; Ćurić, Manda

    2016-10-27

    Room-temperature accelerated aging in the solid state has been applied for atom- and energy-efficient activation of either one or two C-H bonds of azobenzene and methyl orange by palladium(ii) acetate. Organopalladium complexes are prepared in quantitative reactions without potentially harmful side products. Dicyclopalladated methyl orange is water-soluble and is a selective chromogenic biothiol sensor at physiologically-relevant micromolar concentrations in buffered aqueous media.

  13. Palladium-Catalyzed ortho-Olefination of Phenyl Acetic and Phenyl Propylacetic Esters via C-H Bond Activation.

    Science.gov (United States)

    Hu, Jundie; Guan, Mingyu; Han, Jian; Huang, Zhi-Bin; Shi, Da-Qing; Zhao, Yingsheng

    2015-08-21

    A highly regioselective palladium-catalyzed ester-directed ortho-olefination of phenyl acetic and propionic esters with olefins via C-H bond activation has been developed. A wide variety of phenyl acetic and propionic esters were tolerated in this transformation, affording the corresponding olefinated aromatic compounds. The ortho-olefination of heterocyclic acetic and propionic esters also took place smoothly giving the products in good yields, thus proving the potential utility of this protocol in synthetic chemistry.

  14. 26 CFR 1.144-1 - Qualified small issue bonds, qualified student loan bonds, and qualified redevelopment bonds.

    Science.gov (United States)

    2010-04-01

    ... student loan bonds, and qualified redevelopment bonds. (a) Overview. Interest on a private activity bond... 26 Internal Revenue 2 2010-04-01 2010-04-01 false Qualified small issue bonds, qualified student loan bonds, and qualified redevelopment bonds. 1.144-1 Section 1.144-1 Internal Revenue INTERNAL...

  15. Activation of Propane C-H and C-C Bonds by Gas-Phase Pt Atom: A Theoretical Study

    Directory of Open Access Journals (Sweden)

    Chang-Wei Hu

    2012-07-01

    Full Text Available The reaction mechanism of the gas-phase Pt atom with C3H8 has been systematically investigated on the singlet and triplet potential energy surfaces at CCSD(T//BPW91/6-311++G(d, p, Lanl2dz level. Pt atom prefers the attack of primary over secondary C-H bonds in propane. For the Pt + C3H8 reaction, the major and minor reaction channels lead to PtC3H6 + H2 and PtCH2 + C2H6, respectively, whereas the possibility to form products PtC2H4 + CH4 is so small that it can be neglected. The minimal energy reaction pathway for the formation of PtC3H6 + H2, involving one spin inversion, prefers to start at the triplet state and afterward proceed along the singlet state. The optimal C-C bond cleavages are assigned to C-H bond activation as the first step, followed by cleavage of a C-C bond. The C-H insertion intermediates are kinetically favored over the C-C insertion intermediates. From C-C to C-H oxidative insertion, the lowering of activation barrier is mainly caused by the more stabilizing transition state interaction ΔEint, which is the actual interaction energy between the deformed reactants in the transition state.

  16. Halogen-Bonding-Assisted Iodosylbenzene Activation by a Homogenous Iron Catalyst

    DEFF Research Database (Denmark)

    de Sousa, David P.; Wegeberg, Christina; Vad, Mads Sørensen

    2016-01-01

    molecules of [Fe(tpena)]2+ cooperate to solubilize PhIO, extracting two equivalents to form the halogen-bonded dimeric {[Fe(tpena)OIPh]2}4+. The closest intradimeric I⋅⋅⋅O distance, 2.56 Å, is nearly 1 Å less than the sum of the van de Waals radii of these atoms. A correlation of the rates of the reaction...... of {[Fe(tpena)OIPh]2}4+ with para-substituted thioanisoles indicate that this species is a direct metal-based oxidant rather than a derived ferryl or perferryl complex. A study of gas-phase reactions indicate that an ion at m/z=231.06100 originates from solution-state {[Fe(tpena)OIPh]2}4+ and is ascribed...... to [FeIII(tpenaO)]2+, derived from an intramolecular O atom insertion into an Fe–tpena donor bond. Proposed ion pairs, {[Fe(tpena)OIPh]Cl}+ and {[Fe(tpena)OIPh]ClO4}+, are more stable than native [Fe(tpena)OIPh]2+ ions, suggesting that halogen-bonding, as for the solution and solid states, operates also...

  17. Evolution of the chemical bonding nature and electrode activity of indium selenide upon the composite formation with graphene nanosheets

    International Nuclear Information System (INIS)

    Oh, Seung Mi; Lee, Eunsil; Adpakpang, Kanyaporn; Patil, Sharad B.; Park, Mi Jin; Lim, Young Soo; Lee, Kyu Hyoung; Kim, Jong-Young; Hwang, Seong-Ju

    2015-01-01

    Graphical abstract: Display Omitted -- Highlights: • In 4 Se 2.85 @graphene nanocomposite is easily prepared by high energy mechanical milling process. • The bond covalency of In 4 Se 2.85 is notably changed upon the composite formation with graphene. • In 4 Se 2.85 @graphene nanocomposite shows promising anode performance for lithium ion battery. -- Abstract: Evolution of the chemical bonding nature and electrochemical activity of indium selenide upon the composite formation with carbon species is systematically investigated. Nanocomposites of In 4 Se 2.85 @graphene and In 4 Se 2.85 @carbon-black are synthesized via a solid state reaction between In and Se elements, and the following high energy mechanical milling of In 4 Se 2.85 with graphene and carbon-black, respectively. The high energy mechanical milling (HEMM) of In 4 Se 2.85 with carbon species gives rise to a decrease of particle size with a significant depression of the crystallinity of In 4 Se 2.85 phase. In contrast to the composite formation with carbon-black, that with graphene induces a notable decrease of (In−Se) bond covalency, underscoring significant chemical interaction between graphene and In 4 Se 2.85 . Both the nanocomposites of In 4 Se 2.85 @graphene and In 4 Se 2.85 @carbon-black show much better anode performance for lithium ion batteries with larger discharge capacity and better cyclability than does the pristine In 4 Se 2.85 material, indicating the beneficial effect of composite formation on the electrochemical activity of indium selenide. Between the present nanocomposites, the electrode performance of the In 4 Se 2.85 @graphene nanocomposite is superior to that of the In 4 Se 2.85 @carbon-black nanocomposite, which is attributable to the weakening of (In−Se) bonds upon the composite formation with graphene as well as to the better mixing between In 4 Se 2.85 and graphene. The present study clearly demonstrates that the composite formation with graphene has strong influence

  18. Solubilization and folding of a fully active recombinant Gaussia luciferase with native disulfide bonds by using a SEP-Tag.

    Science.gov (United States)

    Rathnayaka, Tharangani; Tawa, Minako; Nakamura, Takashi; Sohya, Shihori; Kuwajima, Kunihiro; Yohda, Masafumi; Kuroda, Yutaka

    2011-12-01

    Gaussia luciferase (GLuc) is the smallest known bioluminescent protein and is attracting much attention as a potential reporter protein. However, its 10 disulfide bond forming cysteines have hampered the efficient production of recombinant GLuc and thus limited its use in bio-imaging application. Here, we demonstrate that the addition of a short solubility enhancement peptide tag (SEP-Tag) to the C-terminus of GLuc (GLuc-C9D) significantly increased the fraction of soluble protein at a standard expression temperature. The expression time was much shorter, and the final yield of GLuc-C9D was significantly higher than with our previous pCold expression system. Reversed phase HPLC indicated that the GLuc-C9D variant folded with a single disulfide bond pattern after proper oxidization. Further, the thermal denaturation of GLuc-C9D was completely reversible, and its secondary structure content remained unchanged until 40°C as assessed by CD spectroscopy. The (1)H-NMR spectrum of GLuc indicated sharp well dispersed peaks typical for natively folded proteins. GLuc-C9D bioluminescence activity was strong and fully retained even after incubation at high temperatures. These results suggest that solubilization using SEP-Tags can be useful for producing large quantities of proteins containing multiple disulfide bonds. Copyright © 2011. Published by Elsevier B.V.

  19. Selective C-C and C-H bond activation/cleavage of pinene derivatives: synthesis of enantiopure cyclohexenone scaffolds and mechanistic insights.

    Science.gov (United States)

    Masarwa, Ahmad; Weber, Manuel; Sarpong, Richmond

    2015-05-20

    The continued development of transition-metal-mediated C-C bond activation/cleavage methods would provide even more opportunities to implement novel synthetic strategies. We have explored the Rh(I)-catalyzed C-C activation of cyclobutanols resident in hydroxylated derivatives of pinene, which proceed in a complementary manner to the C-C bond cleavage that we have observed with many traditional electrophilic reagents. Mechanistic and computational studies have provided insight into the role of C-H bond activation in the stereochemical outcome of the Rh-catalyzed C-C bond activation process. Using this new approach, functionalized cyclohexenones that form the cores of natural products, including the spiroindicumides and phomactin A, have been accessed.

  20. A visible light-activated direct-bonding material: An in vivo comparative study

    OpenAIRE

    O'Brien, K. D.; Read, M. J F; Sandison, R. J.; Roberts, C. T.

    1989-01-01

    A clinical trial was carried out to evaluate and compare the clinical performance of a visible light-cured material with a chemically cured adhesive. This was used in combination with two types of bracket base. Fifty-two patients entered the trial and 542 bracket bases were placed. The incidence and site of bond failure were recorded. The overall failure rate for the light-cured material in combination with both types of bracket was 4.7% and 6% for the chemical-cured adhesive. There were no s...

  1. Microfluidic DNA microarrays in PMMA chips: streamlined fabrication via simultaneous DNA immobilization and bonding activation by brief UV exposure

    DEFF Research Database (Denmark)

    Sabourin, David; Petersen, J; Snakenborg, Detlef

    2010-01-01

    This report presents and describes a simple and scalable method for producing functional DNA microarrays within enclosed polymeric, PMMA, microfluidic devices. Brief (30 s) exposure to UV simultaneously immobilized poly(T)poly(C)-tagged DNA probes to the surface of unmodified PMMA and activated...... the surface for bonding below the glass transition temperature of the bulk PMMA. Functionality and validation of the enclosed PMMA microarrays was demonstrated as 18 patients were correctly genotyped for all eight mutation sites in the HBB gene interrogated. The fabrication process therefore produced probes...

  2. Formation of sulfido ciobium complexes through C-S bond activation

    Directory of Open Access Journals (Sweden)

    Azevedo Nélio Pires

    1998-01-01

    Full Text Available Upon reacting (eta5-C5H52NbCl2, eta5-C5H5 = Cp, and (Ph3Sn(SPh, in THF, (eta5-C5H52Nb(Cl(mu-SSn(Ph3(Cl, 1, and (eta5-C5H52Nb(SCl, 2, were obtained. Complexes 1 and 2 were characterized by IR, ¹H-NMR, 13C-NMR, Mössbauer spectroscopies, elemental analysis as well as by atomic absorption. Hydrolysis of 1 yielded the mu-oxo species, (eta5-C5H52Nb(Cl(mu-OSn(Ph3Cl, 3, which was characterized by IR, ¹H-NMR, 13C-NMR and Mössbauer spectroscopies, elemental analysis, atomic absorption as well as by X-ray crystallography. It crystallizes in the space group Pca2(1 with a = 17.282(3, b = 18.122(4, c = 17.3269(2, V = 5426.2(16 ų, and Z = 8. Additional studies indicated that the complexes were formed as a result of the nucleophilic displacement of the niobium-chloride bond by the thiolate ligand followed by a C-S bond cleavage. The cleavage occurs with an excess of the thiolate compound equal to or greater than 2:1.

  3. The significance of disulfide bonding in biological activity of HB-EGF, a mutagenesis approach

    International Nuclear Information System (INIS)

    Hoskins, J.T.; Zhou, Z.; Harding, P.A.

    2008-01-01

    A site-directed mutagenesis approach was taken to disrupt each of 3 disulfide bonds within human HB-EGF by substituting serine for both cysteine residues that contribute to disulfide bonding. Each HB-EGF disulfide analogue (HB-EGF-Cys/Ser 108/121 , HB-EGF-Cys/Ser 116/132 , and HB-EGF-Cys/Ser 134/143 ) was cloned under the regulation of the mouse metallothionein (MT) promoter and stably expressed in mouse fibroblasts. HB-EGF immunoreactive proteins with M r of 6.5, 21 and 24 kDa were observed from lysates of HB-EGF and each HB-EGF disulfide analogue. HB-EGF immunohistochemical analyses of each HB-EGF stable cell line demonstrated ubiquitous protein expression except HB-EGF-Cys/Ser 108/121 and HB-EGF-Cys/Ser 116/132 stable cell lines which exhibited accumulated expression immediately outside the nucleus. rHB-EGF, HB-EGF, and HB-EGF 134/143 proteins competed with 125 I-EGF in an A431 competitive binding assay, whereas HB-EGF-Cys/Ser 108/121 and HB-EGF-Cys/Ser 116/132 failed to compete. Each HB-EGF disulfide analogue lacked the ability to stimulate tyrosine phosphorylation of the 170 kDa EGFR. These results suggest that HB-EGF-Cys/Ser 134/143 antagonizes EGFRs

  4. Gas-phase C-H and N-H bond activation by a high valent nitrido-iron dication and {NH}-transfer to activated olefins

    Czech Academy of Sciences Publication Activity Database

    Schlangen, M.; Neugebauer, J.; Reiher, M.; Schröder, Detlef; López, J. P.; Haryono, M.; Heinemann, F. W.; Grohmann, A.; Schwarz, H.

    2008-01-01

    Roč. 130, č. 13 (2008), s. 4285-4294 ISSN 0002-7863 R&D Projects: GA AV ČR KJB400550704 Grant - others:DFG(DE) SFB658 Institutional research plan: CEZ:AV0Z40550506 Keywords : azides * bond activation * dications * iron * mass spectrometry * metal nitrenes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 8.091, year: 2008

  5. Cooperative Ge-N Bond activation in aluminium-functionalised aminogermanes and spontaneous imine elimination via an intermediate germyl cation.

    Science.gov (United States)

    Uhl, Werner; Tannert, Jens; Honacker, Christian; Layh, Marcus; Qu, Zheng-Wang; Risthaus, Tobias; Grimme, Stefan

    2015-02-02

    Hydrometallation of iPr2 N-Ge(CMe3 )(C≡C-CMe3 )2 with H-M(CMe3 )2 (M=Al, Ga) affords alkenyl-alkynylgermanes in which the Lewis-acidic metal atoms are not coordinated by the amino N atoms but by the α-C atoms of the ethynyl groups. These interactions result in a lengthening of the Ge-C bonds by approximately 10 pm and a comparably strong deviation of the Ge-CC angle from linearity (154.3(1)°). This unusual behaviour may be caused by steric shielding of the N atoms. Coordination of the metal atoms by the amino groups is observed upon hydrometallation of Et2 N-Ge(C6 H5 )(C≡C-CMe3 )2 , bearing a smaller NR2 group. Strong M-N interactions lead to a lengthening of the Ge-N bonds by 10 to 15 pm and a strong deviation of the M atoms from the MC3 plane by 52 and 47 pm, for Al and Ga, respectively. Dual hydrometallation is achieved only with HAl(CMe3 )2 . In the product, there is a strong Al-N bond with converging Al-N and Ge-N distances (208 vs. 200 pm) and an interaction of the second Al atom to the phenyl group. Addition of chloride anions terminates the latter interaction while the activated Ge-N bond undergoes an unprecedented elimination of EtN=C(H)Me at room temperature, leading to a germane with a Ge-H bond. State-of-the-art DFT calculations reveal that the unique mechanism comprises the transfer of the amino group from Ge to Al to yield an intermediate germyl cation as a strong Lewis acid, which induces β-hydride elimination, with chloride binding being crucial for providing the thermodynamic driving force. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. INFLUENCE OF SILANE HEAT TREATMENT ON THE TENSILE BOND STRENGTH BETWEEN EX-3 SYNTHETIC VENEERING PORCELAIN AND COMPOSITE RESIN USING FIVE DIFFERENT ACTIVATION TEMPERATURES

    Directory of Open Access Journals (Sweden)

    Spartak Yanakiev

    2017-02-01

    Full Text Available Purpose: The purpose of the present study is to assess the effect of five different silane activation temperatures and eight activation methods on the tensile bond strength between one veneering porcelain and one composite resin material. Material and methods: A total of 81 ceramic rods were made of EX-3 veneering ceramic (Kuraray Noritake Dental, Japan. Sintered ceramic bars were grinded with diamond disks to size 10x2x2mm ± 0,05mm. The front part of each bar was polished. After ultrasonic cleaning in distilled water, the specimens were divided into nine groups. Silane was activated with air at room temperature, 38º С, 50º С, 100º С, 120º С using a custom made blow drier. In a silicone mold, a composite resin Z250 (3М ESPE, St. Paul, USA was condensed toward the bond ceramic surface. A total of 81 specimens approximately 2,0 cm long were prepared for tensile bond testing. One way ANOVA, followed by Bonferroni and Games-Howell tests were used for statistical analysis. Results: The lowest tensile bond strength was observed in the control group (3,51MPa. Group 2 yielded the highest bond strength among all groups (19,54MPa. Silane heat treatment enhanced the bond strength for all treatment methods. Within the polished specimens, the highest bond strength was yielded with warm air at 120ºС (11,31MPa. Conclusion: The most effective method for bonding Z250 composite resin to EX-3 veneering ceramic includes HF etching, silane, and adhesive resin. The most effective heat treatment method for bonding is hot air at 120ºС.

  7. New type polyamides containing disulfide bonds for positive active material of lithium secondary batteries

    Science.gov (United States)

    Tsutsumi, Hiromori; Okada, Keiji; Fujita, Kazunari; Oishi, Tsutomu

    Various polyamides containing a disulfide bond in their main chain were prepared by condensation of a diacid, 3,3'-dithiodipropionic acid (P), 6,6'-dithiodinicotinic acid (N), or 2,2'-dithiodibenzoic acid (B) and a diamine, alkyldiamine (I, II, III, and IV: NH 2-(CH 2) n-NH 2, n = 4, 6, 8, and 12) or cystamine, V: NH 2-(CH 2) 2-S-S-(CH 2) 2-NH 2. Polyamides P-I, P-II, P-III, P-IV, and P-V were insoluble common organic solvents, but soluble in formic acid or trifluoroacetic acid. Polyamides containing N or B as the acid moiety, i.e. aromatic polyamides, were soluble in N,N'-dimethylformamide or dimethyl sulfoxide. The electrochemical behavior of P-II electrode in the organic electrolytes, such as propylene carbonate (PC), PC—1,2-dimethoxyethane (DME) mixture, ethylene carbonate (EC)—DME mixture, which are used as the electrolytes for common lithium batteries was investigated. In the mixed electrolyte, PC—DME (1:1, by volume) a good electrochemical response of P-II electrode based on the redox of disulfide bonds in the polymer was observed. Charge/discharge cycling tests of Li/P-II cells were also performed. At the first discharge, the net capacity of the cell was 97.5 Ah kg -1 (this value was calculated from the weight of loaded P-II on the electrode). Utilization of P-II was 53%. Cell capacity versus cycle number was also investigated.

  8. Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds

    Directory of Open Access Journals (Sweden)

    Burkhard Koenig

    2011-01-01

    Full Text Available N-Arylated aliphatic and aromatic amines are important substituents in many biologically active compounds. In the last few years, transition-metal-mediated N-aryl bond formation has become a standard procedure for the introduction of amines into aromatic systems. While N-arylation of simple aromatic halides by simple amines works with many of the described methods in high yield, the reactions may require detailed optimization if applied to the synthesis of complex molecules with additional functional groups, such as natural products or drugs. We discuss and compare in this review the three main N-arylation methods in their application to the synthesis of biologically active compounds: Palladium-catalysed Buchwald–Hartwig-type reactions, copper-mediated Ullmann-type and Chan–Lam-type N-arylation reactions. The discussed examples show that palladium-catalysed reactions are favoured for large-scale applications and tolerate sterically demanding substituents on the coupling partners better than Chan–Lam reactions. Chan–Lam N-arylations are particularly mild and do not require additional ligands, which facilitates the work-up. However, reaction times can be very long. Ullmann- and Buchwald–Hartwig-type methods have been used in intramolecular reactions, giving access to complex ring structures. All three N-arylation methods have specific advantages and disadvantages that should be considered when selecting the reaction conditions for a desired C–N bond formation in the course of a total synthesis or drug synthesis.

  9. Active application of primer acid on acid-treated enamel: Influence on the bond effectiveness of self-etch adhesives systems.

    Science.gov (United States)

    Araújo, Cíntia Tereza Pimenta; Prieto, Lúcia Trazzi; Costa, Daiane Cristianismo; Bosso, Mariana Avalone; Coppini, Erick Kamiya; Dias, Carlos Tadeu Santos; Paulillo, Luis Alexandre Maffei Sartini

    2017-08-01

    Evaluate the composite-to-enamel bond after passive or active application of self-etching primer systems on polished or pre-etched enamel with phosphoric acid. Two self-etch adhesives systems (SEAS) were used: Clearfil SE Bond and Easy Bond. Third human molars were divided into 8 groups (N = 10). The crown of each tooth was sectioned into halves and the mesial/distal surfaces were used. The adhesives were actively or passively applied on enamel with or without prior phosphoric-acid etching. Resin composite cylinders were built after adhesive application. After stored in relative humidity for 24 hr/37°C the specimens were subjected to microshear test in universal testing a machine at a crosshead speed of 0.5 mm/minute. The results were analyzed with three-way ANOVA and the Tukey test. The enamel-etching pattern was evaluated under SEM. The 2-step SEAS system presented significantly higher adhesive bond strength means (47.37 MPa) than the 1-step (36.87 MPa). A poor enamel- etching pattern was observed in active mode showing irregular and short resin tags, however there was not compromised the bond strength. Active or passive application produced similar values of bond strength to enamel regardless of enamel pretreatment and type of SEAS. © 2017 Wiley Periodicals, Inc.

  10. Increased Back-Bonding Explains Step-Edge Reactivity and Particle Size Effect for CO Activation on Ru Nanoparticles.

    Science.gov (United States)

    Foppa, Lucas; Copéret, Christophe; Comas-Vives, Aleix

    2016-12-28

    Carbon monoxide is a ubiquitous molecule, a key feedstock and intermediate in chemical processes. Its adsorption and activation, typically carried out on metallic nanoparticles (NPs), are strongly dependent on the particle size. In particular, small NPs, which in principle contain more corner and step-edge atoms, are surprisingly less reactive than larger ones. Hereby, first-principles calculations on explicit Ru NP models (1-2 nm) show that both small and large NPs can present step-edge sites (e.g., B 5 and B 6 sites). However, such sites display strong particle-size-dependent reactivity because of very subtle differences in local chemical bonding. State-of-the-art crystal orbital Hamilton population analysis allows a detailed molecular orbital picture of adsorbed CO on step-edges, which can be classified as flat (η 1 coordination) and concave (η 2 coordination) sites. Our analysis shows that the CO π-metal d π hybrid band responsible for the electron back-donation is better represented by an oxygen lone pair on flat sites, whereas it is delocalized on both C and O atoms on concave sites, increasing the back-bonding on these sites compared to flat step-edges or low-index surface sites. The bonding analysis also rationalizes why CO cleavage is easier on step-edge sites of large NPs compared to small ones irrespective of the site geometry. The lower reactivity of small NPs is due to the smaller extent of the Ru-O interaction in the η 2 adsorption mode, which destabilizes the η 2 transition-state structure for CO direct cleavage. Our findings provide a molecular understanding of the reactivity of CO on NPs, which is consistent with the observed particle size effect.

  11. Effect of activation mode of dual-cured resin cements and low-viscosity composite liners on bond strength to dentin.

    Science.gov (United States)

    Garcia, Rubens Nazareno; Reis, André Figueiredo; Giannini, Marcelo

    2007-07-01

    The aim of this study was to investigate the influence of the activation mode of dual-cured resin cements and application of low-viscosity composite liners over self-primed dentin on bond strength (BS) of dentin-bonding agents (DBA). Three DBA (Single Bond; Prompt L-Pop and Clearfil SE Bond), their respective resin cements (RelyX ARC and Panavia F) and two low-viscosity composites (Filtek Flow and Protect Liner F) were tested. After removing the buccal enamel surfaces of 25 bovine incisors, each flat dentin surface was sectioned longitudinally and divided into two similar parts. The dentin surfaces were wet-abraded with 600-grit SiC paper and randomly divided into 10 groups. Experimental groups comprised the use of DBA and their respective dual-cured resin cements, with or without light-activation of resin cements. The low-viscosity resin was used only for the self-etching systems, Prompt L-Pop and Clearfil SE Bond. Three resin cement cylinders (0.5mm high and 0.75mm diameter) were built on each bonded dentin surface, using a tygon tubing mold. After water storage for 24h, specimens were subjected to micro-shear testing. Data were statistically analyzed by two-way ANOVA and Tukey test. Light-activation of resin cements resulted in significantly higher BS for all DBA versus groups in which the resin cements were allowed to self-cure. The low-viscosity composite application increased the BS only for Prompt L-Pop. The bond strength of resin cements to dentin is reduced if light-activation is not employed. The use of a low-viscosity composite liner resulted in improved bond strength only for the single-step self-etching adhesive.

  12. The Comparative Studies of Binding Activity of Curcumin and Didemethylated Curcumin with Selenite: Hydrogen Bonding vs Acid-Base Interactions.

    Science.gov (United States)

    Liao, Jiahn-Haur; Wu, Tzu-Hua; Chen, Ming-Yi; Chen, Wei-Ting; Lu, Shou-Yun; Wang, Yi-Hsuan; Wang, Shao-Pin; Hsu, Yen-Min; Huang, Yi-Shiang; Huang, Zih-You; Lin, Yu-Ching; Chang, Ching-Ming; Huang, Fu-Yung; Wu, Shih-Hsiung

    2015-12-04

    In this report, the in vitro relative capabilities of curcumin (CCM) and didemethylated curcumin (DCCM) in preventing the selenite-induced crystallin aggregation were investigated by turbidity tests and isothermal titration calorimetry (ITC). DCCM showed better activity than CCM. The conformers of CCM/SeO3(2-) and DCCM/SeO3(2-) complexes were optimized by molecular orbital calculations. Results reveal that the selenite anion surrounded by CCM through the H-bonding between CCM and selenite, which is also observed via IR and NMR studied. For DCCM, the primary driving force is the formation of an acid-base adduct with selenite showing that the phenolic OH group of DCCM was responsible for forming major conformer of DCCM. The formation mechanisms of selenite complexes with CCM or DCCM explain why DCCM has greater activity than CCM in extenuating the toxicity of selenite as to prevent selenite-induced lens protein aggregation.

  13. The Comparative Studies of Binding Activity of Curcumin and Didemethylated Curcumin with Selenite: Hydrogen Bonding vs Acid-Base Interactions

    Science.gov (United States)

    Liao, Jiahn-Haur; Wu, Tzu-Hua; Chen, Ming-Yi; Chen, Wei-Ting; Lu, Shou-Yun; Wang, Yi-Hsuan; Wang, Shao-Pin; Hsu, Yen-Min; Huang, Yi-Shiang; Huang, Zih-You; Lin, Yu-Ching; Chang, Ching-Ming; Huang, Fu-Yung; Wu, Shih-Hsiung

    2015-12-01

    In this report, the in vitro relative capabilities of curcumin (CCM) and didemethylated curcumin (DCCM) in preventing the selenite-induced crystallin aggregation were investigated by turbidity tests and isothermal titration calorimetry (ITC). DCCM showed better activity than CCM. The conformers of CCM/SeO32- and DCCM/SeO32- complexes were optimized by molecular orbital calculations. Results reveal that the selenite anion surrounded by CCM through the H-bonding between CCM and selenite, which is also observed via IR and NMR studied. For DCCM, the primary driving force is the formation of an acid-base adduct with selenite showing that the phenolic OH group of DCCM was responsible for forming major conformer of DCCM. The formation mechanisms of selenite complexes with CCM or DCCM explain why DCCM has greater activity than CCM in extenuating the toxicity of selenite as to prevent selenite-induced lens protein aggregation.

  14. Methandiide as a non-innocent ligand in carbene complexes: from the electronic structure to bond activation reactions and cooperative catalysis.

    Science.gov (United States)

    Becker, Julia; Modl, Tanja; Gessner, Viktoria H

    2014-09-01

    The synthesis of a ruthenium carbene complex based on a sulfonyl-substituted methandiide and its application in bond activation reactions and cooperative catalysis is reported. In the complex, the metal-carbon interaction can be tuned between a Ru-C single bond with additional electrostatic interactions and a Ru=C double bond, thus allowing the control of the stability and reactivity of the complex. Hence, activation of polar and non-polar bonds (O-H, H-H) as well as dehydrogenation reactions become possible. In these reactions the carbene acts as a non-innocent ligand supporting the bond activation as nucleophilic center in the 1,2-addition across the metal-carbon double bond. This metal-ligand cooperativity can be applied in the catalytic transfer hydrogenation for the reduction of ketones. This concept opens new ways for the application of carbene complexes in catalysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Bond-based 2D quadratic fingerprints in QSAR studies: virtual and in vitro tyrosinase inhibitory activity elucidation.

    Science.gov (United States)

    Casañola-Martin, Gerardo M; Marrero-Ponce, Yovani; Khan, Mahmud T H; Khan, Sher B; Torrens, Francisco; Pérez-Jiménez, Facundo; Rescigno, Antonio; Abad, Concepción

    2010-12-01

    In this report, we show the results of quantitative structure-activity relationship (QSAR) studies of tyrosinase inhibitory activity, by using the bond-based quadratic indices as molecular descriptors (MDs) and linear discriminant analysis (LDA), to generate discriminant functions to predict the anti-tyrosinase activity. The best two models [Eqs (6) and (12)] out of the total 12 QSAR models developed here show accuracies of 93.51% and 91.21%, as well as high Matthews correlation coefficients (C) of 0.86 and 0.82, respectively, in the training set. The validation external series depicts values of 90.00% and 89.44% for these best two equations (6) and (12), respectively. Afterwards, a second external prediction data are used to perform a virtual screening of compounds reported in the literature as active (tyrosinase inhibitors). In a final step, a series of lignans is analysed using the in silico-developed models, and in vitro corroboration of the activity is carried out. An issue of great importance to remark here is that all compounds present greater inhibition values than Kojic acid (standard tyrosinase inhibitor: IC₅₀ = 16.67 μm). The current obtained results could be used as a framework to increase the speed, in the biosilico discovery of leads for the treatment of skin disorders. © 2010 John Wiley & Sons A/S.

  16. 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.

  17. Electrical properties of Al foil/n-4H-SiC Schottky junctions fabricated by surface-activated bonding

    Science.gov (United States)

    Morita, Sho; Liang, Jianbo; Matsubara, Moeko; Dhamrin, Marwan; Nishio, Yoshitaka; Shigekawa, Naoteru

    2018-02-01

    We fabricate 17-µm-thick Al foil/n-4H-SiC Schottky junctions by surface-activated bonding. Their current–voltage and capacitance–voltage characteristics are compared with those of Schottky junctions fabricated by evaporating Al layers on n-4H-SiC epilayers. We find that the ideality factor of Al foil/SiC junctions is larger than that of conventional junctions, which is due to the irradiation of the fast atom beam (FAB) of Ar. The ideality factor of Al foil/SiC junctions is improved by annealing at 400 °C. We also find that the Schottky barrier height is increased by FAB irradiation, which is likely to be due to the negative charges formed at SiC surfaces.

  18. Hydrolysis activities of the particle of agarose-Ce4+ complex for compounds containing phosphodiester or peptide bonds

    Science.gov (United States)

    Yu, Lina; Wang, Dongfeng; Su, Lin; Luo, Yi; Sun, Liping; Xue, Changhu

    2005-07-01

    Hydrolysis activities of PACC (particle of agarose-Ce4+ complex, newly made through double emulsification) for compounds containing phosphodiester or peptide bonds were studied. The results showed that PACC could hydrolyze organophosphorous pesticides not only in water but also in vegetable juice or tea extract. Hydrolysis rates of methamidophos, omethoate and chlorpyrifos in water are 32.39%, 27.12% and 46.62% respectively, those of chlorpyrifos and methamidophos in mung sprout juice 38.28% and 35.45% respectively, and that of chlorpyrifos in tea extract 59.76%. Hydrolysis rates of BSA (bovine serum albumin) in water and protein in tea extract by PACC increase by 54.30% and 86.46% respectively as compared with the control.

  19. Activation of the C-H bond in benzene in the presence of vanadium and titanium complexes

    International Nuclear Information System (INIS)

    Grigoryan, Eh.A.; D'yachkovskij, F.S.; Zhuk, S.Ya.; Papoyan, A.T.; Vyshinskaya, L.I.

    1980-01-01

    A multiple deuterium hydrogen exchange between benzene and deuterated ethylene and methanol in the presence of bis-cyclopentadienylvanadium (CPsub(d)V) and deuterium is found. The reaction is carried out in glass ampules at the temperature of 70 deg C pressure of 0.3-40.0 atm and CP 2 V catalyst concentrations of 0.007-0.035 mol/l during 80-100 hrs under conditions of constant mixing. It is shown that deuterium hydrogen exchange takes place between benzene and deuterium molecules, in the presence of V(2). The deuterium hydrogen exchange under experimental conditions is only possible as a result of activation of the C-H bond in benzene molecules in V coordination sphere and is considerably accelerated in the presence of ethylene

  20. The effect of different final irrigant activation techniques on the bond strength of an epoxy resin-based endodontic sealer: a preliminary study.

    Science.gov (United States)

    Topçuoğlu, Hüseyin Sinan; Tuncay, Öznur; Demirbuga, Sezer; Dinçer, Asiye Nur; Arslan, Hakan

    2014-06-01

    The aim of this study was to evaluate whether or not different final irrigation activation techniques affect the bond strength of an epoxy resin-based endodontic sealer (AH Plus; Dentsply DeTrey, Konstanz, Germany) to the root canal walls of different root thirds. Eighty single-rooted human mandibular premolars were prepared by using the ProTaper system (Dentsply Maillefer, Ballaigues, Switzerland) to size F4, and a final irrigation regimen using 3% sodium hypochlorite and 17% EDTA was performed. The specimens were randomly divided into 4 groups (n = 20) according to the final irrigation activation technique used as follows: no activation (control), manual dynamic activation (MDA), CanalBrush (Coltene Whaledent, Altststten, Switzerland) activation, and ultrasonic activation. Five specimens from each group were prepared for scanning electron microscopic observation to assess the smear layer removal after the final irrigation procedures. All remaining roots were then obturated with gutta-percha and AH Plus sealer. A push-out test was used to measure the bond strength between the root canal dentin and AH Plus sealer. The data obtained from the push-out test were analyzed using 2-way analysis of variance and Tukey post hoc tests. The bond strength values mostly decreased in the coronoapical direction (P < .001). In the coronal and middle thirds, ultrasonic activiation showed a higher bond strength than other groups (P < .05). In the apical third, MDA displayed the highest bond strength to root dentin (P < .05). The majority of specimens exhibited cohesive failures. The bond strength of AH Plus sealer to root canal dentin may improve with ultrasonic activation in the coronal and middle thirds and MDA in the apical third. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  1. The Plant-Window system: A flexible, expandable computing environment for the integration of power plant activities

    International Nuclear Information System (INIS)

    Wood, R.T.; Mullens, J.A.; Naser, J.A.

    1994-01-01

    Power plant data, and the information that can be derived from it, provide the link to the plant through which the operations, maintenance and engineering staff understand and manage plant performance. The increasing use of computer technology in the US nuclear power industry has greatly expanded the capability to obtain, analyze, and present data about the plant to station personnel. However, it is necessary to transform the vast quantity of available data into clear, concise, and coherent information that can be readily accessed and used throughout the plant. This need can be met by an integrated computer workstation environment that provides the necessary information and software applications, in a manner that can be easily understood and used, to the proper users throughout the plant. As part of a Cooperative Research and Development Agreement with the Electric Power Research Institute, the Oak Ridge National Laboratory has developed functional requirements for a Plant-Wide Integrated Environment Distributed on Workstations (Plant-Window) System. The Plant-Window System (PWS) can serve the needs of operations, engineering, and maintenance personnel at nuclear power stations by providing integrated data and software applications (e.g., monitoring, analysis, diagnosis, and control applications) within a common environment. The PWS requirements identify functional capabilities and provide guidelines for standardized hardware, software, and display interfaces to define a flexible computer environment that permits a tailored implementation of workstation capabilities and facilitates future upgrades

  2. Isomerization of Internal Alkynes to Iridium(III) Allene Complexes via C-H Bond Activation: Expanded Substrate Scope, and Progress towards a Catalytic Methodology.

    Science.gov (United States)

    Phadke, Neha; Findlater, Michael

    2015-11-10

    The synthesis of a series of allene complexes (POCOP)Ir(η²-RC=(.)=CR') 1b-4b (POCOP = 2,6-bis(di-tert-butylphosphonito)benzene) via isomerization of internal alkynes is reported. We have demonstrated that the application of this methodology is viable for the isomerization of a wide variety of alkyne substrates. Deuterium labeling experiments support our proposed mechanism. The structures of the allene complexes 1b-4b were determined using spectroscopic data analysis. Additionally, the solid-state molecular structure of complex 2b was determined using single crystal X-ray diffraction studies and it confirmed the assignment of an iridium-bound allene isomerization product. The rates of isomerization were measured using NMR techniques over a range of temperatures to allow determination of thermodynamic parameters. Finally, we report a preliminary step towards developing a catalytic methodology; the allene may be liberated from the metal center by exposure of the complex to an atmosphere of carbon monoxide.

  3. Isomerization of Internal Alkynes to Iridium(III Allene Complexes via C–H Bond Activation: Expanded Substrate Scope, and Progress towards a Catalytic Methodology

    Directory of Open Access Journals (Sweden)

    Neha Phadke

    2015-11-01

    Full Text Available The synthesis of a series of allene complexes (POCOPIr(η2-RC=.=CR’ 1b–4b (POCOP = 2,6-bis(di-tert-butylphosphonitobenzene via isomerization of internal alkynes is reported. We have demonstrated that the application of this methodology is viable for the isomerization of a wide variety of alkyne substrates. Deuterium labeling experiments support our proposed mechanism. The structures of the allene complexes 1b–4b were determined using spectroscopic data analysis. Additionally, the solid-state molecular structure of complex 2b was determined using single crystal X-ray diffraction studies and it confirmed the assignment of an iridium-bound allene isomerization product. The rates of isomerization were measured using NMR techniques over a range of temperatures to allow determination of thermodynamic parameters. Finally, we report a preliminary step towards developing a catalytic methodology; the allene may be liberated from the metal center by exposure of the complex to an atmosphere of carbon monoxide.

  4. Rhodium-catalyzed C-H bond activation for the synthesis of quinonoid compounds: Significant Anti-Trypanosoma cruzi activities and electrochemical studies of functionalized quinones.

    Science.gov (United States)

    Jardim, Guilherme A M; Silva, Thaissa L; Goulart, Marilia O F; de Simone, Carlos A; Barbosa, Juliana M C; Salomão, Kelly; de Castro, Solange L; Bower, John F; da Silva Júnior, Eufrânio N

    2017-08-18

    Thirty four halogen and selenium-containing quinones, synthesized by rhodium-catalyzed C-H bond activation and palladium-catalyzed cross-coupling reactions, were evaluated against bloodstream trypomastigotes of T. cruzi. We have identified fifteen compounds with IC 50 /24 h values of less than 2 μM. Electrochemical studies on A-ring functionalized naphthoquinones were also performed aiming to correlate redox properties with trypanocidal activity. For instance, (E)-5-styryl-1,4-naphthoquinone 59 and 5,8-diiodo-1,4-naphthoquinone 3, which are around fifty fold more active than the standard drug benznidazole, are potential derivatives for further investigation. These compounds represent powerful new agents useful in Chagas disease therapy. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  5. Influence of light-activated and auto- and dual-polymerizing adhesive systems on bond strength of indirect composite resin to dentin.

    Science.gov (United States)

    de Menezes, Maria Jose Lorena; Arrais, Cesar Augusto Galvao; Giannini, Marcelo

    2006-08-01

    Clinicians must be aware of the bonding effectiveness of auto- and dual- polymerizing adhesive systems before choosing the material and technique of cementing inlay/onlays to dentin. An inadequate choice may compromise the success of indirect restorations. This study compared the microtensile bond strength (MTBS) of indirect composite resin bonded to dentin by light-activated, autopolymerizing, and dual-polymerizing adhesive systems. Occlusal dentin surfaces of 36 human third molars were exposed and flattened. Teeth were assigned to 1 of the following 6 groups (n=6) of adhesive luting systems: 2 dual-polymerizing systems (Scotchbond Multipurpose Plus/Rely X [SBMP] and Prime & Bond NT Dual Cure/Enforce [PBDC]); 1 autopolymerizing system (ED Primer/Panavia F [EDP]); and 3 light-activated systems (control groups) (Adper Single Bond/Rely X [SB], Prime & Bond NT/Enforce [PB], and Clearfil SE Bond/Panavia F [CF]). The restorative materials were applied according to manufacturer's directions. A 2-mm-thick prepolymerized composite resin (Clearfil APX) disc was cemented with the resin cements on the bonded dentin. Teeth were stored in water at 37 degrees C for 24 hours. Afterwards, teeth were sectioned both mesial-distally and buccal-lingually to obtain multiple bonded beam specimens with 0.8 mm(2) of cross-sectional area. Each specimen was tested in tension at a crosshead speed of 0.5 mm/min until failure. Data (MPa) were analyzed by 1-way analysis of variance and the Tukey post hoc test (alpha=.05). Failure patterns of tested specimens were analyzed using scanning electron microscopy. Mean MTBS values (MPa) for experimental groups were as follows: SBMP, 32.89 +/- 3.26(a); SB, 26.74 +/- 7.45(ab); PB, 26.11 +/- 4.48(ab); CF, 25.30 +/- 6.42(ab); EDP, 16.82 +/- 5.53(bc); PBDC, 11.20 +/- 5.89(c) (P<.001). Groups with similar lowercase letters were not significantly different. Failure pattern of fractured specimens varied according to the polymerization mode. The

  6. Molecular heterogeneous catalysts derived from bipyridine-based organosilica nanotubes for C-H bond activation.

    Science.gov (United States)

    Zhang, Shengbo; Wang, Hua; Li, Mei; Han, Jinyu; Liu, Xiao; Gong, Jinlong

    2017-06-01

    Heterogeneous metal complex catalysts for direct C-H activation with high activity and durability have always been desired for transforming raw materials into feedstock chemicals. This study described the design and synthesis of one-dimensional organosilica nanotubes containing 2,2'-bipyridine (bpy) ligands in the framework (BPy-NT) and their post-synthetic metalation to provide highly active and robust molecular heterogeneous catalysts. By adjusting the ratios of organosilane precursors, very short BPy-NT with ∼50 nm length could be controllably obtained. The post-synthetic metalation of bipyridine-functionalized nanotubes with [IrCp*Cl(μ-Cl)] 2 (Cp* = η 5 -pentamethylcyclopentadienyl) and [Ir(cod)(OMe)] 2 (cod = 1,5-cyclooctadiene) afforded solid catalysts, IrCp*-BPy-NT and Ir(cod)-BPy-NT, which were utilized for C-H oxidation of heterocycles and cycloalkanes as well as C-H borylation of arenes. The cut-short nanotube catalysts displayed enhanced activities and durability as compared to the analogous homogeneous catalysts and other conventional heterogeneous catalysts, benefiting from the isolated active sites as well as the fast transport of substrates and products. After the reactions, a detailed characterization of Ir-immobilized BPy-NT via TEM, SEM, nitrogen adsorption, UV/vis, XPS, and 13 C CP MAS NMR indicated the molecular nature of the active species as well as stable structures of nanotube scaffolds. This study demonstrates the potential of BPy-NT with a short length as an integration platform for the construction of efficient heterogeneous catalytic systems for organic transformations.

  7. Intramolecular C-H Bond Activation through a Flexible Ester Linkage

    Czech Academy of Sciences Publication Activity Database

    Shaffer, Christopher; Schröder, Detlef; Gutz, Ch.; Lutzen, A.

    2012-01-01

    Roč. 51, č. 32 (2012), s. 8097-8100 ISSN 1433-7851 Grant - others:European Research Council(XE) AdG HORIZOMS Institutional support: RVO:61388963 Keywords : C-H activation * copper * gas phase * ion mobility * oxidation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 13.734, year: 2012

  8. Computational evaluations of charge coupling and hydrogen bonding in the active site of a family 7 cellobiohydrolase.

    Science.gov (United States)

    Granum, David M; Vyas, Shubham; Sambasivarao, Somisetti V; Maupin, C Mark

    2014-01-16

    Solution pH and the pKa values of ionizable residues are critical factors known to influence enzyme catalysis, structural stability, and dynamical fluctuations. Presented here is an exhaustive computational study utilizing long time constant pH molecular dynamics, pH replica exchange simulations, and kinetic modeling to evaluate pH-dependent conformations, charge dynamics, residue pKa values, and the catalytic activity-pH profile for cellobiohydrolase Cel7B from Melanocarpus albomyces . The predicted pKa values support the role of Glu212 as the catalytic nucleophile and Glu217 as the acid-base residue. The presence of a charge-correlated active site and an extensive hydrogen bonding network is found to be critical in enabling favorable residue orientations for catalysis and shuttling excess protons around the active site. Clusters of amino acids are identified that act in concert to effectively modulate the optimal pH for catalysis while elevating the overall catalytic rate with respect to a noncoupled system. The work presented here demonstrates the complex and critical role of coupled ionizable residues to the proper functioning of cellobiohydrolase Cel7B, functionally related glycosyl hydrolases, and enzymes in general. The simulations also support the use of the CpHMD for the accurate prediction of residue pKa values and to evaluate the impact of pH on protein structure and charge dynamics.

  9. Horseshoe crab coagulation factor B. A unique serine protease zymogen activated by cleavage of an Ile-Ile bond.

    Science.gov (United States)

    Muta, T; Oda, T; Iwanaga, S

    1993-10-05

    Horseshoe crab factor B is an intracellular serine protease zymogen involved in the bacterial endotoxin-responsive hemolymph coagulation cascade. cDNAs for factor B were isolated utilizing a polymerase chain reaction product using two primers derived from the partial amino acid sequence. The cloned cDNA of 1928 base pairs encoded 400 amino acid residues of factor B precursor. The first 23 amino acid residues constitute a presumed prepropeptide that may be processed by both a signal peptidase and a processing protease, similar to mammalian vitamin K-dependent protease precursors. The mature protein consists of 377 amino acids with a calculated molecular mass of 40,570 Da. The overall structure is highly homologous to that of limulus proclotting enzyme (35.9% identity), the substrate for active factor B in the cascade. Like the proclotting enzyme, mature factor B is composed of an amino-terminal "clip"-like domain and a carboxyl-terminal serine protease domain homologous to that of human plasma prekallikrein (36.5%). Internal sequences encode a unique activation peptide. Surprisingly, the cleavage sites of the zymogen factor B for activation by limulus active factor C were found to be an Arg-Ser and an Ile-Ile bond, the latter of which has not been found in any other protease zymogens. These cleavages result in the release of the activation peptide, which consists of 21 residues with a carboxyl-terminal isoleucine. These results indicate that the intracellular clotting system of the limulus hemocyte, like mammalian plasma clotting cascade, proceeds with the sequential activation of three serine protease zymogens: factor C, factor B, and proclotting enzyme.

  10. The Use of Acoustic Emission for Detection of Active Corrosion and Degraded Adhesive Bonding in Aircraft Structure,

    Science.gov (United States)

    1975-11-01

    vertical stabilizer It was discovered that manufacturing defects ( wormholes ) in the adhesive-bonded leadinp edge were allowing water penetration into the...bond to the core walls, which is the weakest bonding mode. Further confirmation of this theory is displayed in Figure 13, which comnared to Pigure 3...leading edge. Area was missed in previous X-ray inspection due to lack of standing water in honeycomb. Arrow denotes wormholes in arrowhead bond which allowed water entry. 28W) "Now ~I mAE - MeCI

  11. Quantification of the selective activation of C--H bonds in short chain alkanes: The reactivity of ethane, propane, isobutane, n-butane, and neopentane on Ir(111)

    International Nuclear Information System (INIS)

    Johnson, D.F.; Weinberg, W.H.

    1995-01-01

    The initial probabilities of precursor-mediated, dissociative chemisorption of the saturated hydrocarbons 13 C-labeled ethane, propane, isobutane, n-butane, and neopentane on the close-packed Ir(111) surface have been measured. The selective activation of primary (1 degree), secondary (2 degree), and tertiary (3 degree) C--H bonds has been quantified by examining the reactivities of the selectively deuterated isotopomers of propane, C 3 H 8 , CH 3 CD 2 CH 3 , and C 3 D 8 , and of isobutane, (CH 3 ) 3 CH, (CH 3 ) 3 CD, and (CD 3 ) 3 CH. With respect to the bottom of the physically adsorbed well for each hydrocarbon, the apparent C--H bond activation energies have been found to be 10.4±0.3 kcal/mol (ethane), 11.4±0.3 kcal/mol (propane), 11.5±0.3 kcal/mol (n-butane), 11.3±0.3 kcal/mol (i-butane), and 11.3±0.3 kcal/mol (neopentane). For all the alkanes examined, the ratios of the preexponential factors of the rate coefficients of reaction and desorption are 1x10 -2 . The C--D bond activation energies are higher than the corresponding C--H bond activation energies by 480 cal/mol (ethane), 630 cal/mol (propane), and 660 cal/mol (i-butane). By analyzing the primary kinetic isotope effects for the selectively deuterated isotopomers of propane and isobutane, the 2 degree C--H bond activation energy is found to be 310±160 cal/mol less than the 1 degree C--H bond activation energy on this surface, and similarly, 3 degree C--H bond cleavage is less by 80±70 cal/mol. The quantification of the branching ratios within the C--H bond activation channel for propane and isobutane on this surface shows that the formation of 1 degree-alkyl intermediates is, in general, favored over the formation of either 2 degree- or 3 degree-alkyl intermediates. (Abstract Truncated)

  12. Aromatic C-H bond activation revealed by infrared multiphoton dissociation spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Jašíková, L.; Hanikýřová, E.; Schröder, Detlef; Roithová, J.

    2012-01-01

    Roč. 47, č. 4 (2012), s. 460-465 ISSN 1076-5174 Grant - others:GA ČR(CZ) GAP207/11/0338; Seventh Framework Program(XE) 226716 Institutional research plan: CEZ:AV0Z40550506 Keywords : C-H activation * density functional theory calculations * ion spectroscopy * metal oxides * rearrangements Subject RIV: CC - Organic Chemistry Impact factor: 3.214, year: 2012

  13. Synthesis of a Benzodiazepine-derived Rhodium NHC Complex by C-H Bond Activation

    Energy Technology Data Exchange (ETDEWEB)

    Bergman, Roberg G.; Gribble, Jr., Michael W.; Ellman, Jonathan A.

    2008-01-30

    The synthesis and characterization of a Rh(I)-NHC complex generated by C-H activation of 1,4-benzodiazepine heterocycle are reported. This complex constitutes a rare example of a carbene tautomer of a 1,4-benzodiazepine aldimine stabilized by transition metal coordination and demonstrates the ability of the catalytically relevant RhCl(PCy{sub 3}){sub 2} fragment to induce NHC-forming tautomerization of heterocycles possessing a single carbene-stabilizing heteroatom. Implications for the synthesis of benzodiazepines and related pharmacophores via C-H functionalization are discussed.

  14. Effect of Laser-Activated Irrigation on the Push-Out Bond Strength of ProRoot Mineral Trioxide Aggregate and Biodentine in Furcal Perforations.

    Science.gov (United States)

    Nagas, Emre; Kucukkaya, Selen; Eymirli, Ayhan; Uyanik, Mehmet Ozgur; Cehreli, Zafer Cavit

    2017-04-01

    The objective of the present study was to assess the effect of erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser-activated irrigation (LAI) of NaOCl on the push-out bond strength of furcal perforations repaired with ProRoot mineral trioxide aggregate (MTA) and Biodentine. Several studies investigated the adhesion of calcium silicate-based cements after exposure to endodontic irrigants, while effect of LAI on bond strength remains to be elucidated. Bur-cut furcal perforations with standard dimensions were created in 100 extracted human mandibular molars. Teeth were randomly distributed into two groups (n = 50/group) according to the repair material applied: (1) ProRoot MTA or (2) Biodentine. The specimens were further assigned into five subgroups according to the irrigation regimens used over the set materials: (a) distilled water with needle irrigation; (b) 5.25% NaOCl with needle irrigation; (c) distilled water with LAI; (d) 5.25% NaOCl with LAI; and (e) no irrigation (control). Bond strengths of the test materials were assessed by using push-out bond strength test. Biodentine showed significantly higher dislocation resistance than ProRoot MTA (p  0.05). Biodentine showed higher dislocation resistance than ProRoot MTA as a perforation repair material. Er,Cr:YSGG laser activation of irrigation aqueous solutions had no adverse effect on push-out bond strength of Biodentine and ProRoot MTA.

  15. Expanding the neuron's calcium signaling repertoire: intracellular calcium release via voltage-induced PLC and IP3R activation.

    Directory of Open Access Journals (Sweden)

    Stefanie Ryglewski

    2007-04-01

    Full Text Available Neuronal calcium acts as a charge carrier during information processing and as a ubiquitous intracellular messenger. Calcium signals are fundamental to numerous aspects of neuronal development and plasticity. Specific and independent regulation of these vital cellular processes is achieved by a rich bouquet of different calcium signaling mechanisms within the neuron, which either can operate independently or may act in concert. This study demonstrates the existence of a novel calcium signaling mechanism by simultaneous patch clamping and calcium imaging from acutely isolated central neurons. These neurons possess a membrane voltage sensor that, independent of calcium influx, causes G-protein activation, which subsequently leads to calcium release from intracellular stores via phospholipase C and inositol 1,4,5-trisphosphate receptor activation. This allows neurons to monitor activity by intracellular calcium release without relying on calcium as the input signal and opens up new insights into intracellular signaling, developmental regulation, and information processing in neuronal compartments lacking calcium channels.

  16. The Link Between ADHD and the Risk of Sexual Victimization Among College Women: Expanding the Lifestyles/Routine Activities Framework.

    Science.gov (United States)

    Snyder, Jamie A

    2015-11-01

    Using data from a nationally representative sample of college women, the current study examines attention deficit hyperactivity disorder (ADHD) as a potential risk factor in the prediction of sexual victimization among college women and as an extension of the lifestyles/routine activities framework. The findings indicate that college women with ADHD experienced sexual victimization at significantly higher rates than college women without ADHD. Furthermore, ADHD emerged as a significant predictor of sexual victimization across models. The lifestyles/routine activities theory also received general support, particularly for the concepts of exposure, proximity, and guardianship. This research suggests that other risk factors outside the lifestyles/routine activities framework are important in the prediction of sexual victimization in college women. © The Author(s) 2015.

  17. Active vibration reduction of a flexible structure bonded with optimised piezoelectric pairs using half and quarter chromosomes in genetic algorithms

    International Nuclear Information System (INIS)

    Daraji, A H; Hale, J M

    2012-01-01

    The optimal placement of sensors and actuators in active vibration control is limited by the number of candidates in the search space. The search space of a small structure discretized to one hundred elements for optimising the location of ten actuators gives 1.73 × 10 13 possible solutions, one of which is the global optimum. In this work, a new quarter and half chromosome technique based on symmetry is developed, by which the search space for optimisation of sensor/actuator locations in active vibration control of flexible structures may be greatly reduced. The technique is applied to the optimisation for eight and ten actuators located on a 500×500mm square plate, in which the search space is reduced by up to 99.99%. This technique helps for updating genetic algorithm program by updating natural frequencies and mode shapes in each generation to find the global optimal solution in a greatly reduced number of generations. An isotropic plate with piezoelectric sensor/actuator pairs bonded to its surface was investigated using the finite element method and Hamilton's principle based on first order shear deformation theory. The placement and feedback gain of ten and eight sensor/actuator pairs was optimised for a cantilever and clamped-clamped plate to attenuate the first six modes of vibration, using minimization of linear quadratic index as an objective function.

  18. Leishmania-specific T cells expressing interferon-¿(IFN-¿) and IL-10 upon activation are expanded in individuals cured of visceral leishmaniasis

    DEFF Research Database (Denmark)

    Kemp, K; Kemp, M; Kharazmi, A

    1999-01-01

    Peripheral blood mononuclear cells (PBMC) from patients who have recovered from visceral leishmaniasis often respond to Leishmania antigens in vitro by production of both IL-4, IFN-gamma and IL-10. In order to establish the cellular sources of these cytokines, we activated cells from individuals...... in Leishmania-activated PBMC cultures from the previous patients and from individuals living in a village where leishmaniasis does not occur. The percentage of IL-10- and IFN-gamma-containing cells was significantly higher in the previous patients than in the controls, indicating that Leishmania-specific T...... cells producing IL-10 and/or IFN-gamma had been expanded as a result of the infection. The cytokine-producing cells in the previous patients could be divided into three types: (i) cells producing IFN-gamma only; (ii) cells producing IL-4 only; and (iii) cells producing IFN-gamma and IL-10 simultaneously...

  19. Ligand-Controlled Chemoselective C(acyl)–O Bond vs C(aryl)–C Bond Activation of Aromatic Esters in Nickel Catalyzed C(sp2)–C(sp3) Cross-Couplings

    KAUST Repository

    Chatupheeraphat, Adisak

    2018-02-20

    A ligand-controlled and site-selective nickel catalyzed Suzuki-Miyaura cross-coupling reaction with aromatic esters and alkyl organoboron reagents as coupling partners was developed. This methodology provides a facile route for C(sp2)-C(sp3) bond formation in a straightforward fashion by successful suppression of the undesired β-hydride elimination process. By simply switching the phosphorus ligand, the ester substrates are converted into the alkylated arenes and ketone products, respectively. The utility of this newly developed protocol was demonstrated by its wide substrate scope, broad functional group tolerance and application in the synthesis of key intermediates for the synthesis of bioactive compounds. DFT studies on the oxidative addition step helped rationalizing this intriguing reaction chemoselectivity: whereas nickel complexes with bidentate ligands favor the C(aryl)-C bond cleavage in the oxidative addition step leading to the alkylated product via a decarbonylative process, nickel complexes with monodentate phosphorus ligands favor activation of the C(acyl)-O bond, which later generates the ketone product.

  20. Stereocontrolled generation of nucleophilic (Z)- or (E)-α-fluoroalkenylchromium reagents via carbon-fluorine bond activation: highly stereoselective synthesis of (E)- or (Z)-β-fluoroallylic alcohols.

    Science.gov (United States)

    Nihei, Takashi; Yokotani, Saya; Ishihara, Takashi; Konno, Tsutomu

    2014-02-14

    Highly nucleophilic (Z)- or (E)-α-fluoroalkenylchromium species could be generated in a stereoselective manner via C-F bond activation of CBrF2-containing molecules, and they reacted smoothly with various aldehydes to give (E)- or (Z)-β-fluoroallylic alcohol derivatives in high yields, respectively.

  1. Discovery of molluscicidal and cercaricidal activities of 3-substituted quinazolinone derivatives by a scaffold hopping approach using a pseudo-ring based on the intramolecular hydrogen bond formation.

    Science.gov (United States)

    Guo, Wei; Zheng, Lv-Yin; Li, Yong-Dong; Wu, Ren-Miao; Chen, Qiang; Yang, Ding-Qiao; Fan, Xiao-Lin

    2016-06-10

    Discovery of novel topological agents against Oncomelania hupensis snails and cercariae remains a significant challenge in current Schistosomiasis control. A pseudo-ring formed from salicylanilide by an intramolecular hydrogen bond led to the discovery of 3-substituted quinazolinone derivatives which showed a potent molluscicidal and cercaricidal activities. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  2. A facile preparation of TiO2/ACF with Csbnd Ti bond and abundant hydroxyls and its enhanced photocatalytic activity for formaldehyde removal

    Science.gov (United States)

    Liu, R. F.; Li, W. B.; Peng, A. Y.

    2018-01-01

    The quantum yields and efficiency(ACF) was prepared via a modified deposition-precipitation method to facilitate its photon absorption and of photogenerated charge carriers have been the major issues for photocatalysis on titania catalyst. The TiO2/ACF catalyst with anatase TiO2 uniformly dispersed on activated carbon fibers electron transfer, thus improve the quantum yields and efficiency of the photogenerated electrons and holes. XPS analysis on the catalyst demonstrates the existence of Ti3+ and Ti2+ species, Csbnd Ti bond and abundant hydroxyls, which are also proved by UV-vis DRS and TG-DSC analysis. It is believed that the acid environment in preparation plays an essential role in the formation of Csbnd Ti bond and surface hydroxyls, which can be tuned by changing hydrothermal synthesis time. The Csbnd Ti bond can improve the electron transfer in the catalyst and the substantial surface hydroxyls lead to high absorption for UV lines and enhanced adsorption of water and formaldehyde, resulting in more active OH free radicals and the outstanding photocatalytic activity of TiO2/ACF, which is much higher than the titania powder for photocatalytic removal of low concentration formaldehyde. The essential role of surface hydroxyls for photocatalytic activity was confirmed surpassing that of chemical bond between carbon and titanium in TiO2-carbon composite for the first time.

  3. Mechanistic insight into conjugated N-N bond cleavage by Rh(III)-catalyzed redox-neutral C-H activation of pyrazolones.

    Science.gov (United States)

    Wu, Weirong; Liu, Yuxia; Bi, Siwei

    2015-08-14

    Density functional theory (DFT) calculations have been performed to investigate the detailed mechanism of Rh(III)-catalyzed redox-neutral C-H activation of pyrazolones with PhC≡CPh. It is found that (1) the methylene C-H activation is prior to the phenyl C-H activation, (2) the N-N bond cleavage is realized via Rh(III) → Rh(I) → Rh(III) rather than via Rh(III) → Rh(V) → Rh(III). The zwitterionic Rh(I) complex is identified to be a key intermediate in promoting the N-N bond cleavage. (3) Different from the Rh(III)-catalyzed hydrazine-directed C-H activation for indole synthesis, the rate-determining step of the reaction studied in this work is the Rh(III) → Rh(I) → Rh(III) process resulting in the N-N bond cleavage rather than the alkyne insertion step. The present theoretical study provides new insight into the mechanism of the conjugated N-N bond cleavage.

  4. Implementation and Evaluation of Web-Based Learning Activities on Bonding and the Structure of Matter for 10-th Grade Chemistry

    Science.gov (United States)

    Frailich, Marcel

    This study deals with the development, implementation, and evaluation of web-based activities associated with the topic of chemical bonding , as taught in 10th grade chemistry. A website was developed entitled: "Chemistry and the Chemical Industry in the Service of Mankind", its URL is: http://stwww.weizmann.ac.il/g-chem/learnchem (Kesner, Frailich, & Hofstein, 2003). The main goal of this study was to assess the educational effectiveness of website activities dealing with the chemical bonding concept. These activities include visualization tools, as well as topics relevant to daily life and industrial applications. The study investigated the effectiveness of a web-based learning environment regarding the understanding of chemical bonding concepts, students' perceptions of the classroom learning environment, their attitudes regarding the relevance of learning chemistry to everyday life, and their interest in chemistry studies. As mentioned before, in the present study we focused on activities (from the website), all of which deal with chemical bonding concept. The following are the reasons for the decision to focus on this topic: (1) Chemical bonding is a key concept that is taught in 10th grade chemistry in high school. It provides the basis for many other chemistry topics that are taught later, and (2) Chemical bonding is a difficult for students using existing tools (e. g., static models in books, ball-and- stick models), which are insufficient to demonstrate the abstract nature phenomena associated with this topic. The four activities developed for this study are (1) models of the atomic structure, (2) metals -- structure and properties, (3) ionic substances in everyday life and in industry, and (4) molecular substances -- structure, properties, and uses. The study analyzed both quantitative and qualitative research. The quantitative tools of the study included: A Semantic Differential questionnaire and a Chemistry Classroom Web-Based Learning Environment

  5. The Sirt1 activator SRT3025 expands hematopoietic stem and progenitor cells and improves hematopoiesis in Fanconi anemia mice

    Directory of Open Access Journals (Sweden)

    Qing-Shuo Zhang

    2015-07-01

    Full Text Available Fanconi anemia is a genetic bone marrow failure syndrome. The current treatment options are suboptimal and do not prevent the eventual onset of aplastic anemia requiring bone marrow transplantation. We previously showed that resveratrol, an antioxidant and an activator of the protein deacetylase Sirt1, enhanced hematopoiesis in Fancd2 mutant mice and improved the impaired stem cell quiescence observed in this disease. Given that Sirt1 is important for the function of hematopoietic stem cells, we hypothesized that Sirt1 activation may improve hematopoiesis. Indeed, Fancd2−/− mice and wild-type mice treated with the selective Sirt1 activator SRT3025 had increased numbers of hematopoietic stem and progenitor cells, platelets and white blood cells. SRT3025 was also protective against acetaldehyde-induced hematopoietic damage. Unlike resveratrol, however, SRT3025 did not affect stem cell quiescence, suggesting distinct mechanisms of action. Conditional deletion of Sirt1 in hematopoietic cells did not abrogate the beneficial effects of SRT3025, indicating that the drug did not act by directly stimulating Sirt1 in stem cells, but must be acting indirectly via extra-hematopoietic effects. RNA-Seq transcriptome analysis revealed the down-regulation of Egr1–p21 expression, providing a potential mechanism for improved hematopoiesis. Overall, our data indicate that SRT3025 or related compounds may be beneficial in Fanconi anemia and other bone marrow failure syndromes.

  6. Iron-Catalyzed C-O Bond Activation: Opportunity for Sustainable Catalysis.

    Science.gov (United States)

    Bisz, Elwira; Szostak, Michal

    2017-10-23

    Oxygen-based electrophiles have emerged as some of the most valuable cross-coupling partners in organic synthesis due to several major strategic and environmental benefits, such as abundance and potential to avoid toxic halide waste. In this context, iron-catalyzed C-O activation/cross-coupling holds particular promise to achieve sustainable catalytic protocols due to its natural abundance, inherent low toxicity, and excellent economic and ecological profile. Recently, tremendous progress has been achieved in the development of new methods for functional-group-tolerant iron-catalyzed cross-coupling reactions by selective C-O cleavage. These methods establish highly attractive alternatives to traditional cross-coupling reactions by using halides as electrophilic partners. In particular, new easily accessible oxygen-based electrophiles have emerged as substrates in iron-catalyzed cross-coupling reactions, which significantly broaden the scope of this catalysis platform. New mechanistic manifolds involving iron catalysis have been established; thus opening up vistas for the development of a wide range of unprecedented reactions. The synthetic potential of this sustainable mode of reactivity has been highlighted by the development of new strategies in the construction of complex motifs, including in target synthesis. The most recent advances in sustainable iron-catalyzed cross-coupling of C-O-based electrophiles are reviewed, with a focus on both mechanistic aspects and synthetic utility. It should be noted that this catalytic manifold provides access to motifs that are often not easily available by other methods, such as the assembly of stereodefined dienes or C(sp 2 )-C(sp 3 ) cross-couplings, thus emphasizing the synthetic importance of this mode of reactivity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Monoiron hydrogenase catalysis: hydrogen activation with the formation of a dihydrogen, Fe-H(delta-)...H(delta+)-O, bond and methenyl-H4MPT+ triggered hydride transfer.

    Science.gov (United States)

    Yang, Xinzheng; Hall, Michael B

    2009-08-12

    A fully optimized resting state model with a strong Fe-H(delta-)...H(delta+)-O dihydrogen bond for the active site of the third type of hydrogenase, [Fe]-hydrogenase, is proposed from density functional theory (DFT) calculations on the reformulated active site from the recent X-ray crystal structure study of C176A (Cys176 was mutated to an alanine) mutated [Fe]-hydrogenase in the presence of dithiothreitol. The computed vibrational frequencies for this new active site model possess an average error of only +/-4.5 cm(-1) with respect to the wild-type [Fe]-hydrogenase. Based on this resting state model, a new mechanism with the following unusual aspects for hydrogen activation catalyzed by [Fe]-hydrogenase is also proposed from DFT calculations. (1) Unexpected dual pathways for H(2) cleavage with proton transfer to Cys176-sulfur or 2-pyridinol's oxygen for the formation and regeneration of the resting state with an Fe-H(delta-)...H(delta+)-O dihydrogen bond before the appearance of methenyl-H(4)MPT(+) (MPT(+)). (2) The strong dihydrogen bond in this resting state structure prevents D(2)/H(2)O exchange. (3) Only upon the arrival of MPT(+) with its strong hydride affinity can D(2)/H(2)O exchange take place as the arrival of MPT(+) triggers the breaking of the strong Fe-H(delta-)...H(delta+)-O dihydrogen bond by taking a hydride from the iron center and initiating the next H(2) (D(2)) cleavage. This new mechanism is completely different than that previously proposed (J. Am. Chem. Soc. 2008, 130, 14036) which was based on an active site model related to an earlier crystal structure. Here, Fe's role is H(2) capture and hydride formation without MPT(+) while the pyridone's special role involves the protection of the hydride by the dihydrogen bond.

  8. Microstructural evolution in the partial transient liquid phase diffusion bonding of Zircaloy-4 to stainless steel 321 using active titanium filler metal

    Energy Technology Data Exchange (ETDEWEB)

    Atabaki, M. Mazar, E-mail: m.mazaratabaki@gmail.co [Department of Materials Engineering, Faculty of Mechanical Engineering, University Technology Malaysia, 81310 (Malaysia); Institute for Materials Research, the School of Process, Environmental and Materials Engineering, Faculty of Engineering, University of Leeds, Leeds (United Kingdom)

    2010-11-30

    Microstructural evolution of the partial transient liquid phase diffusion bonded Zircaloy-4 and stainless steel 321 using an active Ti-base interlayer were studied at different temperatures. Additionally, simple analytical models were developed to predict the evolution of the interlayer and intermetallics during the bonding operation. Bonds were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. Precision measurement of the interlayer width was made as a function of the bonding temperature. The liquid film migration occurred as a result of chemical solubility differences between the stable and metastable phases. The formation and growth model of the intermetallic compounds at the interfaces of Zircaloy-4/Ti-base interlayer and stainless steel 321/Ti-base interlayer for controlling the bonding process was studied considering the diffusion kinetics and the thermodynamics. The evolution of the interlayer thickness indicated a good agreement between the calculation and experimental measurement. It was also demonstrated that the low isothermal solidification kinetic was not only due to the enrichment of the liquid phase with the base alloying elements such as Ti and Zr, but also the reduction of solid solubility limit of Cu in the base alloys contributed to the reduction of isothermal solidification kinetic.

  9. Microstructural evolution in the partial transient liquid phase diffusion bonding of Zircaloy-4 to stainless steel 321 using active titanium filler metal

    Science.gov (United States)

    Atabaki, M. Mazar

    2010-11-01

    Microstructural evolution of the partial transient liquid phase diffusion bonded Zircaloy-4 and stainless steel 321 using an active Ti-base interlayer were studied at different temperatures. Additionally, simple analytical models were developed to predict the evolution of the interlayer and intermetallics during the bonding operation. Bonds were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. Precision measurement of the interlayer width was made as a function of the bonding temperature. The liquid film migration occurred as a result of chemical solubility differences between the stable and metastable phases. The formation and growth model of the intermetallic compounds at the interfaces of Zircaloy-4/Ti-base interlayer and stainless steel 321/Ti-base interlayer for controlling the bonding process was studied considering the diffusion kinetics and the thermodynamics. The evolution of the interlayer thickness indicated a good agreement between the calculation and experimental measurement. It was also demonstrated that the low isothermal solidification kinetic was not only due to the enrichment of the liquid phase with the base alloying elements such as Ti and Zr, but also the reduction of solid solubility limit of Cu in the base alloys contributed to the reduction of isothermal solidification kinetic.

  10. Effects of hydrogen peroxide pretreatment and heat activation of silane on the shear bond strength of fiber-reinforced composite posts to resin cement.

    Science.gov (United States)

    Pyun, Jung-Hoon; Shin, Tae-Bong; Lee, Joo-Hee; Ahn, Kang-Min; Kim, Tae-Hyung; Cha, Hyun-Suk

    2016-04-01

    To evaluate the effects of hydrogen peroxide pretreatment and heat activation of silane on the shear bond strength of fiber-reinforced composite posts to resin cement. The specimens were prepared to evaluate the bond strength of epoxy resin-based fiber posts (D.T. Light-Post) to dual-curing resin cement (RelyX U200). The specimens were divided into four groups (n=18) according to different surface treatments: group 1, no treatment; group 2, silanization; group 3, silanization after hydrogen peroxide etching; group 4, silanization with warm drying at 80℃ after hydrogen peroxide etching. After storage of the specimens in distilled water at 37℃ for 24 hours, the shear bond strength (in MPa) between the fiber post and resin cement was measured using a universal testing machine. The fractured surface of the fiber post was examined using scanning electron microscopy. Data were analyzed using one-way ANOVA and post-hoc analysis with Tukey's HSD test (α=0.05). Silanization of the fiber post (Group 2) significantly increased the bond strength in comparison with the non treated control (Group 1) (Psilanization also significantly increased the bond strength (Group 3 and 4) (Psilane agent (Group 2 and 3) (P>.05). Fiber post silanization and subsequent heat treatment (80℃) with warm air blower can be beneficial in clinical post cementation. However, hydrogen peroxide etching prior to silanization was not effective in this study.

  11. Expanded therapeutic potential in activity space of next-generation 5-nitroimidazole antimicrobials with broad structural diversity

    Science.gov (United States)

    Miyamoto, Yukiko; Kalisiak, Jarosław; Korthals, Keith; Lauwaet, Tineke; Cheung, Dae Young; Lozano, Ricardo; Cobo, Eduardo R.; Upcroft, Peter; Upcroft, Jacqueline A.; Berg, Douglas E.; Gillin, Frances D.; Fokin, Valery V.; Sharpless, K. Barry; Eckmann, Lars

    2013-01-01

    Metronidazole and other 5-nitroimidazoles (5-NI) are among the most effective antimicrobials available against many important anaerobic pathogens, but evolving resistance is threatening their long-term clinical utility. The common 5-NIs were developed decades ago, yet little 5-NI drug development has since taken place, leaving the true potential of this important drug class unexplored. Here we report on a unique approach to the modular synthesis of diversified 5-NIs for broad exploration of their antimicrobial potential. Many of the more than 650 synthesized compounds, carrying structurally diverse functional groups, have vastly improved activity against a range of microbes, including the pathogenic protozoa Giardia lamblia and Trichomonas vaginalis, and the bacterial pathogens Helicobacter pylori, Clostridium difficile, and Bacteroides fragilis. Furthermore, they can overcome different forms of drug resistance, and are active and nontoxic in animal infection models. These findings provide impetus to the development of structurally diverse, next-generation 5-NI drugs as agents in the antimicrobial armamentarium, thus ensuring their future viability as primary therapeutic agents against many clinically important infections. PMID:24101497

  12. Au@Pd Bimetallic Nanocatalyst for Carbon-Halogen Bond Cleavage: An Old Story with New Insight into How the Activity of Pd is Influenced by Au.

    Science.gov (United States)

    Liu, Rui; Chen, Hui-Min; Fang, Li-Ping; Xu, Cuihong; He, Zuoliang; Lai, Yujian; Zhao, Huachao; Bekana, Deribachew; Liu, Jing-Fu

    2018-03-21

    AuPd bimetallic nanocatalysts exhibit superior catalytic performance in the cleavage of carbon-halogen bonds (C-X) in the hazardous halogenated pollutants. A better understanding of how Au atoms promote the reactivity of Pd sites rather than vaguely interpreting as bimetallic effect and determining which type of Pd sites are necessary for these reactions are crucial factors for the design of atomically precise nanocatalysts that make full use of both the Pd and Au atoms. Herein, we systematically manipulated the coordination number of Pd-Pd, d-orbital occupation state, and the Au-Pd interface of the Pd reactive centers and studied the structure-activity relationship of Au-Pd in the catalyzed cleavage of C-X bonds. It is revealed that Au enhanced the activity of Pd atoms primarily by increasing the occupation state of Pd d-orbitals. Meanwhile, among the Pd sites formed on the Au surface, five to seven contiguous Pd atoms, three or four adjacent Pd atoms, and isolated Pd atoms were found to be the most active in the cleavage of C-Cl, C-Br, and C-I bonds, respectively. Besides, neighboring Au atoms directly contribute to the weakening of the C-Br/C-I bond. This work provides new insight into the rational design of bimetallic metal catalysts with specific catalytic properties.

  13. Hydrodesulfurization on Transition Metal Catalysts: Elementary Steps of C-S Bond Activation and Consequences of Bifunctional Synergies

    Science.gov (United States)

    Yik, Edwin Shyn-Lo

    convergence to a single phase is expected and predictable from thermodynamics at a given temperature and sulfur chemical potential, metastability of two phases can exist. We demonstrate, through extensive characterization and kinetic evidence, such behaviors exist in Re, where structural disparities between its phases lead to kinetic hurdles that prevent interconversions between layered ReSx nanostructures and sulfur-covered Re metal clusters. Such features allowed, for the first time, direct comparisons of reaction rates at identical conditions on two disparate phases of the same transition metal identity. Rigorous assessments of kinetic and selectivity data indicated that more universal mechanistic features persist across all catalysts studied, suggesting that differences in their catalytic activity were the result of different densities of HDS sites, which appeared to correlate with their respective metal-sulfur bond energies. Kinetic responses and product distributions indicated that the consumption of thiophene proceeds by the formation of a partially-hydrogenated surface intermediate, which subsequently produces tetrahydrothiophene (THT) and butene/butane (C4) via primary routes on similar types of sites. These sites are formed from desorption of weakly-bound sulfur adatoms on sulfur-covered metal surfaces, which can occur when the heat of sulfur adsorption is sufficiently low at high sulfur coverage as a result of increased sulfur-sulfur repulsive interactions. Relative stabilities and differences in the molecularity of the respective transition states that form THT and C4 dictate product distributions. THT desulfurization to form C4 occurs via readsorption and subsequent dehydrogenation, evidenced by secondary rates that exhibited negative H2 dependences. These behaviors suggest that C-S bond activation occurs on a partially (un)saturated intermediate, analogous to behaviors observed in C-C bond scission reactions of linear and cycloalkanes on hydrogen-covered metal

  14. Interplay of Electronic Cooperativity and Exchange Coupling in Regulating the Reactivity of Diiron(IV)-oxo Complexes towards C-H and O-H Bond Activation.

    Science.gov (United States)

    Ansari, Azaj; Ansari, Mursaleem; Singha, Asmita; Rajaraman, Gopalan

    2017-07-26

    Activation of inert C-H bonds such as those of methane are extremely challenging for chemists but in nature, the soluble methane monooxygenase (sMMO) enzyme readily oxidizes methane to methanol by using a diiron(IV) species. This has prompted chemists to look for similar model systems. Recently, a (μ-oxo)bis(μ-carboxamido)diiron(IV) ([Fe IV 2 O(L) 2 ] 2+ L=N,N-bis-(3',5'-dimethyl-4'-methoxypyridyl-2'-methyl)-N'-acetyl-1,2-diaminoethane) complex has been generated by bulk electrolysis and this species activates inert C-H bonds almost 1000 times faster than mononuclear Fe IV =O species and at the same time selectively activates O-H bonds of alcohols. The very high reactivity and selectivity of this species is puzzling and herein we use extensive DFT calculations to shed light on this aspect. We have studied the electronic and spectral features of diiron {Fe III -μ(O)-Fe III } +2 (complex I), {Fe III -μ(O)-Fe IV } +3 (II), and {Fe IV -μ(O)-Fe IV } +4 (III) complexes. Strong antiferromagnetic coupling between the Fe centers leads to spin-coupled S=0, S=3/2, and S=0 ground state for species I-III respectively. The mechanistic study of the C-H and O-H bond activation reveals a multistate reactivity scenario where C-H bond activation is found to occur through the S=4 spin-coupled state corresponding to the high-spin state of individual Fe IV centers. The O-H bond activation on the other hand, occurs through the S=2 spin-coupled state corresponding to an intermediate state of individual Fe IV centers. Molecular orbital analysis reveals σ-π/π-π channels for the reactivity. The nature of the magnetic exchange interaction is found to be switched during the course of the reaction and this offers lower energy pathways. Significant electronic cooperativity between two metal centers during the course of the reaction has been witnessed and this uncovers the reason behind the efficiency and selectivity observed. The catalyst is found to prudently choose the desired spin

  15. Effect of simulated pulpal pressure on composite bond strength to ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-19

    Oct 19, 2009 ... Simulated pulpal pressure had a negative effect on microtensile bond strength of laser ablated dentin when Single Bond adhesive system was used. Key words: Bond strength, laser treatment, pulpal pressure, resin composite. INTRODUCTION. Adhesive techniques have expanded the range of possi-.

  16. Bigelow Expandable Activity Module Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The BEAM project advances inflatable habitat technology further and conducts flight demonstration of a commercially-designed inflatable system to achieve Technology...

  17. Conserved water-mediated hydrogen bond network between TM-I, -II, -VI, and -VII in 7TM receptor activation

    DEFF Research Database (Denmark)

    Nygaard, Rie; Hansen, Louise Valentin; Mokrosinski, Jacek

    2010-01-01

    Five highly conserved polar residues connected by a number of structural water molecules together with two rotamer micro-switches, TrpVI:13 and TyrVII:20, constitute an extended hydrogen bond network between the intracellular segments of TM-I, -II, -VI, and -VII of 7TM receptors. Molecular dynamics...... simulations showed that, although the fewer water molecules in rhodopsin were relatively movable, the hydrogen bond network of the beta2-adrenergic receptor was fully loaded with water molecules that were surprisingly immobilized between the two rotamer switches, both apparently being in their closed...... (AsnI:18, AspII:10, and AsnVII:13), whereas others (AsnVII:12 and AsnVII:16) located one helical turn apart and sharing a water molecule were shown to be essential for agonist-induced signaling. It is concluded that the conserved water hydrogen bond network of 7TM receptors constitutes an extended...

  18. Molecular structure, Normal Coordinate Analysis, harmonic vibrational frequencies, Natural Bond Orbital, TD-DFT calculations and biological activity analysis of antioxidant drug 7-hydroxycoumarin

    Science.gov (United States)

    Sebastian, S.; Sylvestre, S.; Jayarajan, D.; Amalanathan, M.; Oudayakumar, K.; Gnanapoongothai, T.; Jayavarthanan, T.

    2013-01-01

    In this work, we report harmonic vibrational frequencies, molecular structure, NBO and HOMO, LUMO analysis of Umbelliferone also known as 7-hydroxycoumarin (7HC). The optimized geometric bond lengths and bond angles obtained by computation (monomer and dimmer) shows good agreement with experimental XRD data. Harmonic frequencies of 7HC were determined and analyzed by DFT utilizing 6-311+G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of Normal Coordinate Analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). The change in electron density (ED) in the σ* and π* antibonding orbitals and stabilization energies E(2) have been calculated by Natural Bond Orbital (NBO) analysis to give clear evidence of stabilization originating in the hyperconjugation of hydrogen-bonded interaction. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincides with the experimental spectra. Microbial activity of studied compounds was tested against Staphylococcus aureus, Streptococcus pyogenes, Bacillus subtilis, Escherichia coli, Psuedomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Shigella flexneri, Salmonella typhi and Enterococcus faecalis.

  19. Synthesis of Biotin Linkers with the Activated Triple Bond Donor [p-(N-propynoylaminotoluic Acid] (PATA for Efficient Biotinylation of Peptides and Oligonucleotides

    Directory of Open Access Journals (Sweden)

    Martina Jezowska

    2012-11-01

    Full Text Available Biotin is an important molecule for modern biological studies including, e.g., cellular transport. Its exclusive affinity to fluorescent streptavidin/avidin proteins allows ready and specific detection. As a consequence methods for the attachment of biotin to various biological targets are of high importance, especially when they are very selective and can also proceed in water. One useful method is Hüisgen dipolar [3+2]-cycloaddition, commonly referred to as “click chemistry”. As we reported recently, the activated triple bond donor p-(N-propynoylaminotoluic acid (PATA gives excellent results when used for conjugations at submicromolar concentrations. Thus, we have designed and synthesized two biotin linkers, with different lengths equipped with this activated triple bond donor and we proceeded with biotinylation of oligonucleotides and C-myc peptide both in solution and on solid support with excellent yields of conversion.

  20. Cu(II)-catalyzed allylic silylation of Morita-Baylis-Hillman alcohols via dual activation of Si-B bond and hydroxyl group.

    Science.gov (United States)

    Xuan, Qing-Qing; Zhong, Neng-Jun; Ren, Chuan-Li; Liu, Li; Wang, Dong; Chen, Yong-Jun; Li, Chao-Jun

    2013-11-01

    The reaction of Morita-Baylis-Hillman (MBH) alcohols with Me2PhSiBpin under the catalysis of Cu(OTf)2/pyridine in methanol has been developed. The direct silylation of allylic alcohols via dual activation of the Si-B bond and the hydroxyl group of the MBH alcohol provides an efficient and convenient method for the synthesis of functionalized allylsilanes.

  1. Iodine-catalyzed sp³ C-H bond activation by selenium dioxide: synthesis of diindolylmethanes and di(3-indolyl)selanides.

    Science.gov (United States)

    Naidu, P Seetham; Majumder, Swarup; Bhuyan, Pulak J

    2015-11-01

    An efficient reaction protocol was developed for the synthesis of several diindolylmethane derivatives via the [Formula: see text] C-H bond activation of aryl methyl ketones by [Formula: see text] and indoles in the presence of catalytic amounts of [Formula: see text] at 80 [Formula: see text] using dioxane as solvent. Unexpectedly, an interesting class of di(3-indolyl)selenide compounds was isolated when the reaction was carried out at room temperature.

  2. 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

  3. Effect of light-activation with different light-curing units and time intervals on resin cement bond strength to intraradicular dentin.

    Science.gov (United States)

    Miguel-Almeida, Maria Eleonora; Azevedo, Mario Lucio da Costa; Rached-Júnior, Fuad Abi; Oliveira, Camila Favero; Silva, Ricardo Gariba; Messias, Danielle Cristine

    2012-01-01

    The aim of this study was to assess the bond strength of a resin cement to intraradicular dentin varying the light-curing unit and the moment at which the light was applied. Post spaces of endodontically treated canines were prepared. The roots were distributed into 6 groups (n=10) according to the light-curing unit and the moment of light exposure: I) Quartz tungsten halogen-600 mW/cm² (QTH) + immediate light activation (t0); II) QTH + light activation after 10 min (t10); III) Light-emitting diodes (LED)-800 mW/cm² (LED-800)+ t0; IV) LED-800 + t10; V) LED-1,500 mW/cm² (LED-1500)+ t0; VI) LED-1500 + t10. After post cementation, slices from coronal, middle and apical post/root regions were submitted to the push-out test and failure evaluation. It was verified that LED-800 (4.40 ± 3.00 MPa) and LED-1500 (4.67 ± 3.04 MPa) provided bond strength statistically superior to QTH (3.13 ± 1.76 MPa) (p0.05). There was no significant difference between t0 and t10 (p>0.05). Coronal post/root region (4.75 ± 3.10 MPa) presented significantly higher bond strength than the apical (3.32 ± 2.30 MPa) (plight-activation, regardless of the moment of light exposure.

  4. Expanding roles for GILT in immunity

    OpenAIRE

    West, Laura Ciaccia; Cresswell, Peter

    2012-01-01

    Gamma-interferon-inducible lysosomal thiol reductase (GILT), a thioredoxin-related oxidoreductase, functions in MHC class II-restricted antigen processing and MHC class I-restricted cross-presentation by reducing disulfide bonds of endocytosed proteins and facilitating their unfolding and optimal degradation. However, recent reports have greatly expanded our understanding of GILT’s function. Several studies of GILT and antigen processing have shown that the influence of GILT on the peptide re...

  5. Asymmetric Synthesis of (-)-Incarvillateine Employing an Intramolecular Alkylation via Rh-Catalyzed Olefinic C-H Bond Activation

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Andy; Bergman, Robert; Ellman, Jonathan

    2008-02-18

    An asymmetric total synthesis of (-)-incarvillateine, a natural product having potent analgesic properties, has been achieved in 11 steps and 15.4% overall yield. The key step is a rhodium-catalyzed intramolecular alkylation of an olefinic C-H bond to set two stereocenters. Additionally, this transformation produces an exocyclic, tetrasubstituted alkene through which the bicyclic piperidine moiety can readily be accessed.

  6. Layouts of Expander Graphs

    OpenAIRE

    Dujmović, Vida; Sidiropoulos, Anastasios; Wood, David R.

    2015-01-01

    Bourgain and Yehudayoff recently constructed $O(1)$-monotone bipartite expanders. By combining this result with a generalisation of the unraveling method of Kannan, we construct 3-monotone bipartite expanders, which is best possible. We then show that the same graphs admit 3-page book embeddings, 2-queue layouts, 4-track layouts, and have simple thickness 2. All these results are best possible.

  7. Promotional effects of chemisorbed oxygen and hydroxide in the activation of C-H and O-H bonds over transition metal surfaces

    Science.gov (United States)

    Hibbitts, David; Neurock, Matthew

    2016-08-01

    Electronegative coadsorbates such as atomic oxygen (O*) and hydroxide (OH*) can act as Brønsted bases when bound to Group 11 as well as particular Group 8-10 metal surfaces and aid in the activation of X-H bonds. First-principle density functional theory calculations were carried out to systematically explore the reactivity of the C-H bonds of methane and surface methyl intermediates as well as the O-H bond of methanol directly and with the assistance of coadsorbed O* and OH* intermediates over Group 11 (Cu, Ag, and Au) and Group 8-10 transition metal (Ru, Rh, Pd, Os, Ir, and Pt) surfaces. C-H as well as O-H bond activation over the metal proceeds via a classic oxidative addition type mechanism involving the insertion of the metal center into the C-H or O-H bond. O* and OH* assist C-H and O-H activation over particular Group 11 and Group 8-10 metal surfaces via a σ-bond metathesis type mechanism involving the oxidative addition of the C-H or O-H bond to the metal along with a reductive deprotonation of the acidic C-H and O-H bond over the M-O* or M-OH* site pair. The O*- and OH*-assisted C-H activation paths are energetically preferred over the direct metal catalyzed C-H scission for all Group 11 metals (Cu, Ag, and Au) with barriers that are 0.4-1.5 eV lower than those for the unassisted routes. The barriers for O*- and OH*-assisted C-H activation of CH4 on the Group 8-10 transition metals, however, are higher than those over the bare transition metal surfaces by as much as 1.4 eV. The C-H activation of adsorbed methyl species show very similar trends to those for CH4 despite the differences in structure between the weakly bound methane and the covalently adsorbed methyl intermediates. The activation of the O-H bond of methanol is significantly promoted by O* as well as OH* intermediates over both the Group 11 metals (Cu, Ag, and Au) as well as on all Group 8-10 metals studied (Ru, Rh, Pd, Os, Ir, and Pt). The O*- and OH*-assisted CH3O-H barriers are 0.6 to 2

  8. Mechanistic Insights on C-O and C-C Bond Activation and Hydrogen Insertion during Acetic Acid Hydrogenation Catalyzed by Ruthenium Clusters in Aqueous Medium

    Energy Technology Data Exchange (ETDEWEB)

    Shangguan, Junnan; Olarte, Mariefel V.; Chin, Ya-Huei [Cathy

    2016-06-07

    Catalytic pathways for acetic acid (CH3COOH) and hydrogen (H2) reactions on dispersed Ru clusters in the aqueous medium and the associated kinetic requirements for C-O and C-C bond cleavages and hydrogen insertion are established from rate and isotopic assessments. CH3COOH reacts with H2 in steps that either retain its carbon backbone and lead to ethanol, ethyl acetate, and ethane (47-95 %, 1-23 %, and 2-17 % carbon selectivities, respectively) or break its C-C bond and form methane (1-43 % carbon selectivities) at moderate temperatures (413-523 K) and H2 pressures (10-60 bar, 298 K). Initial CH3COOH activation is the kinetically relevant step, during which CH3C(O)-OH bond cleaves on a metal site pair at Ru cluster surfaces nearly saturated with adsorbed hydroxyl (OH*) and acetate (CH3COO*) intermediates, forming an adsorbed acetyl (CH3CO*) and hydroxyl (OH*) species. Acetic acid turnover rates increase proportionally with both H2 (10-60 bar) and CH3COOH concentrations at low CH3COOH concentrations (<0.83 M), but decrease from first to zero order as the CH3COOH concentration and the CH3COO* coverages increase and the vacant Ru sites concomitantly decrease. Beyond the initial CH3C(O)-OH bond activation, sequential H-insertions on the surface acetyl species (CH3CO*) lead to C2 products and their derivative (ethanol, ethane, and ethyl acetate) and the competitive C-C bond cleavage of CH3CO* causes the eventual methane formation. The instantaneous carbon selectivities towards C2 species (ethanol, ethane, and ethyl acetate) increase linearly with the concentration of proton-type Hδ+ (derived from carboxylic acid dissociation) and chemisorbed H*. The selectivities towards C2 products decrease with increasing temperature, because of higher observed barriers for C-C bond cleavage than H-insertion. This study offers an interpretation of mechanism and energetics and provides kinetic evidence of carboxylic acid assisted proton-type hydrogen (Hδ+) shuffling during H

  9. Computational Study of Pincer Iridium Catalytic Systems: C-H, N-H, and C-C Bond Activation and C-C Coupling Reactions

    Science.gov (United States)

    Zhou, Tian

    Computational chemistry has achieved vast progress in the last decades in the field, which was considered to be only experimental before. DFT (density functional theory) calculations have been proven to be able to be applied to large systems, while maintaining high accuracy. One of the most important achievements of DFT calculations is in exploring the mechanism of bond activation reactions catalyzed by organometallic complexes. In this dissertation, we discuss DFT studies of several catalytic systems explored in the lab of Professor Alan S. Goldman. Headlines in the work are: (1) (R4PCP)Ir alkane dehydrogenation catalysts are highly selective and different from ( R4POCOP)Ir catalysts, predicting different rate-/selectivity-determining steps; (2) The study of the mechanism for double C-H addition/cyclometalation of phenanthrene or biphenyl by (tBu4PCP)Ir(I) and ( iPr4PCP)Ir illustrates that neutral Ir(III) C-H addition products can undergo a very facile second C-H addition, particularly in the case of sterically less-crowded Ir(I) complexes; (3) (iPr4PCP)Ir pure solid phase catalyst is highly effective in producing high yields of alpha-olefin products, since the activation enthalpy for dehydrogenation is higher than that for isomerization via an allyl pathway; higher temperatures favor the dehydrogenation/isomerization ratio; (4) (PCP)Ir(H)2(N2H4) complex follows a hydrogen transfer mechanism to undergo both dehydrogenation to form N 2 and H2, as well as hydrogen transfer followed by N-N bond cleavage to form NH3, N2, and H2; (5) The key for the catalytic effect of solvent molecule in CO insertion reaction for RMn(CO)5 is hydrogen bond assisted interaction. The basicity of the solvent determines the strength of the hydrogen bond interaction during the catalytic path and determines the catalytic power of the solvent; and (6) Dehydrogenative coupling of unactivated C-H bonds (intermolecular vinyl-vinyl, intramolecular vinyl-benzyl) is catalyzed by precursors of the

  10. Can Density Matrix Embedding Theory with the Complete Activate Space Self-Consistent Field Solver Describe Single and Double Bond Breaking in Molecular Systems?

    Science.gov (United States)

    Pham, Hung Q; Bernales, Varinia; Gagliardi, Laura

    2018-03-13

    Density matrix embedding theory (DMET) [ Phys. Rev. Lett. 2012, 109, 186404] has been demonstrated as an efficient wave-function-based embedding method to treat extended systems. Despite its success in many quantum lattice models, the extension of DMET to real chemical systems has been tested only on selected cases. Herein, we introduce the use of the complete active space self-consistent field (CASSCF) method as a correlated impurity solver for DMET, leading to a method called CAS-DMET. We test its performance in describing the dissociation of H-H single bonds in a H 10 ring model system and an N═N double bond in azomethane (CH 3 -N═N-CH 3 ) and pentyldiazene (CH 3 (CH 2 ) 4 -N═NH). We find that the performance of CAS-DMET is comparable to CASSCF with different active space choices when single-embedding DMET corresponding to only one embedding problem for the system is used. When multiple embedding problems are used for the system, the CAS-DMET is in good agreement with CASSCF for the geometries around the equilibrium, but not in equal agreement at bond dissociation.

  11. Mechanism of carbon-halogen bond reductive cleavage in activated alkyl halide initiators relevant to living radical polymerization: theoretical and experimental study.

    Science.gov (United States)

    Isse, Abdirisak A; Gennaro, Armando; Lin, Ching Yeh; Hodgson, Jennifer L; Coote, Michelle L; Guliashvili, Tamaz

    2011-04-27

    The mechanism of reductive cleavage of model alkyl halides (methyl 2-bromoisobutyrate, methyl 2-bromopropionate, and 1-bromo-1-chloroethane), used as initiators in living radical polymerization (LRP), has been investigated in acetonitrile using both experimental and computational methods. Both theoretical and experimental investigations have revealed that dissociative electron transfer to these alkyl halides proceeds exclusively via a concerted rather than stepwise manner. The reductive cleavage of all three alkyl halides requires a substantial activation barrier stemming mainly from the breaking C-X bond. The activation step during single electron transfer LRP (SET-LRP) was originally proposed to proceed via formation and decomposition of RX(•-) through an outer sphere electron transfer (OSET) process (Guliashvili, T.; Percec, V. J. Polym. Sci., Part A: Polym. Chem. 2007, 45, 1607). These radical anion intermediates were proposed to decompose via heterolytic rather than homolytic C-X bond dissociation. Here it is presented that injection of one electron into RX produces only a weakly associated charge-induced donor-acceptor type radical anion complex without any significant covalent σ type bond character between carbon-centered radical and associated anion leaving group. Therefore, neither homolytic nor heterolytic bond dissociation applies to the reductive cleavage of C-X in these alkyl halides inasmuch as a true radical anion does not form in the process. In addition, the whole mechanism of SET-LRP has to be revisited since it is based on presumed OSET involving intermediate RX(•-), which is shown here to be nonexistent.

  12. sp{sup 3} versus sp{sup 2} C-H bond activation chemistry of 2-picoline by Th(IV) and U(IV) metallocene complexes

    Energy Technology Data Exchange (ETDEWEB)

    Kiplinger, Jaqueline L. [Los Alamos National Laboratory, Mail Stop J514, Los Alamos, NM 87545 (United States)], E-mail: kiplinger@lanl.gov; Scott, Brian L.; Schelter, Eric J. [Los Alamos National Laboratory, Mail Stop J514, Los Alamos, NM 87545 (United States); Pool Davis Tournear, Jaime A

    2007-10-11

    The thorium alkyl complex (C{sub 5}Me{sub 5}){sub 2}Th(CH{sub 3}){sub 2} and 2-picoline react to give preferential sp{sup 3} C-H bond activation in the presence of a more reactive sp{sup 2} C-H bond, while the analogous uranium complex, (C{sub 5}Me{sub 5}){sub 2}U(CH{sub 3}){sub 2}, reacts with only the ortho 2-picoline sp{sup 2} C-H bond, as originally expected. Herein, we describe this competitive sp{sup 3} versus sp{sup 2} C-H bond activation chemistry with 2-picoline and (C{sub 5}Me{sub 5}){sub 2}An(CH{sub 3}){sub 2} (An = Th, U) and provide experimental observations that suggest different mechanistic reaction pathways are operative for the uranium and thorium complexes. We also report the X-ray crystal structures for the thorium picolyl complex, (C{sub 5}Me{sub 5}){sub 2}Th(CH{sub 3})[{eta}{sup 2}-(N,C)-2-CH{sub 2}-NC{sub 5}H{sub 3}], and the {eta}{sup 2}-pyridyl complexes (C{sub 5}Me{sub 5}){sub 2}Th(CH{sub 3})[{eta}{sup 2}-(N,C)-6-CH{sub 3}-NC{sub 5}H{sub 3}] and (C{sub 5}Me{sub 5}){sub 2}U(CH{sub 3})[{eta}{sup 2}-(N,C)-6-CH{sub 3}-NC{sub 5}H{sub 3}].

  13. D1-Asn-298 in photosystem II is involved in a hydrogen-bond network near the redox-active tyrosine YZfor proton exit during water oxidation.

    Science.gov (United States)

    Nagao, Ryo; Ueoka-Nakanishi, Hanayo; Noguchi, Takumi

    2017-12-08

    In photosynthetic water oxidation, two water molecules are converted into one oxygen molecule and four protons at the Mn 4 CaO 5 cluster in photosystem II (PSII) via the S-state cycle. Efficient proton exit from the catalytic site to the lumen is essential for this process. However, the exit pathways of individual protons through the PSII proteins remain to be identified. In this study, we examined the involvement of a hydrogen-bond network near the redox-active tyrosine Y Z in proton transfer during the S-state cycle. We focused on spectroscopic analyses of a site-directed variant of D1-Asn-298, a residue involved in a hydrogen-bond network near Y Z We found that the D1-N298A mutant of Synechocystis sp. PCC 6803 exhibits an O 2 evolution activity of ∼10% of the wild-type. D1-N298A and the wild-type D1 had very similar features of thermoluminescence glow curves and of an FTIR difference spectrum upon Y Z oxidation, suggesting that the hydrogen-bonded structure of Y Z and electron transfer from the Mn 4 CaO 5 cluster to Y Z were little affected by substitution. In the D1-N298A mutant, however, the flash-number dependence of delayed luminescence showed a monotonic increase without oscillation, and FTIR difference spectra of the S-state cycle indicated partial and significant inhibition of the S 2 → S 3 and S 3 → S 0 transitions, respectively. These results suggest that the D1-N298A substitution inhibits the proton transfer processes in the S 2 → S 3 and S 3 → S 0 transitions. This in turn indicates that the hydrogen-bond network near Y Z can be functional as a proton transfer pathway during photosynthetic water oxidation. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. Metal-catalyzed activation of ethers via C-O bond cleavage: a new strategy for molecular diversity.

    Science.gov (United States)

    Cornella, Josep; Zarate, Cayetana; Martin, Ruben

    2014-12-07

    In 1979, the seminal work of Wenkert set the standards for the utilization of aryl and vinyl ethers as coupling partners via C-O bond-cleavage. Although the topic remained dormant for almost three decades, the last few years have witnessed a renaissance in this area of expertise, experiencing an exponential growth and becoming a significant discipline within the cross-coupling arena. The means to utilize readily accessible aryl or vinyl ethers as counterparts does not only represent a practical, powerful and straightforward alternative to organic halides, but also constitutes an excellent opportunity to improve our chemical knowledge about a relatively unexplored area of expertise. This review summarizes the most significant developments in the area of C-O bond-cleavage when employing aryl or vinyl ethers, providing a detailed overview of the current state of the art and including future aspects, when applicable.

  15. Functionalized expanded porphyrins

    Science.gov (United States)

    Sessler, Jonathan L; Pantos, Patricia J

    2013-11-12

    Disclosed are functionalized expanded porphyrins that can be used as spectrometric sensors for high-valent actinide cations. The disclosed functionalized expanded porphyrins have the advantage over unfunctionalized systems in that they can be immobilized via covalent attachment to a solid support comprising an inorganic or organic polymer or other common substrates. Substrates comprising the disclosed functionalized expanded porphyrins are also disclosed. Further, disclosed are methods of making the disclosed compounds (immobilized and free), methods of using them as sensors to detect high valent actinides, devices that comprise the disclosed compounds, and kits.

  16. Activation of dinitrogen-derived hafnium nitrides for nucleophilic N-C bond formation with a terminal isocyanate.

    Science.gov (United States)

    Semproni, Scott P; Chirik, Paul J

    2013-12-02

    Better by Hf: Anion coordination to a bridging hafnocene nitride complex, prepared from CO-induced N2 cleavage, increases the nucleophilicity of the nitrogen atom, thus promoting additional NC bond formation with a typically inert terminal isocyanate ligand. This cascade sequence allows synthesis of otherwise challenging mono-substituted ureas using N2 , CO, and an appropriate electrophile. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Expanding Thurston maps

    CERN Document Server

    Bonk, Mario

    2017-01-01

    This monograph is devoted to the study of the dynamics of expanding Thurston maps under iteration. A Thurston map is a branched covering map on a two-dimensional topological sphere such that each critical point of the map has a finite orbit under iteration. It is called expanding if, roughly speaking, preimages of a fine open cover of the underlying sphere under iterates of the map become finer and finer as the order of the iterate increases. Every expanding Thurston map gives rise to a fractal space, called its visual sphere. Many dynamical properties of the map are encoded in the geometry of this visual sphere. For example, an expanding Thurston map is topologically conjugate to a rational map if and only if its visual sphere is quasisymmetrically equivalent to the Riemann sphere. This relation between dynamics and fractal geometry is the main focus for the investigations in this work.

  18. Spectroscopic Evidence for a H Bond Network at Y356 Located at the Subunit Interface of Active E. coli Ribonucleotide Reductase.

    Science.gov (United States)

    Nick, Thomas U; Ravichandran, Kanchana R; Stubbe, JoAnne; Kasanmascheff, Müge; Bennati, Marina

    2017-07-18

    The reaction catalyzed by E. coli ribonucleotide reductase (RNR) composed of α and β subunits that form an active α2β2 complex is a paradigm for proton-coupled electron transfer (PCET) processes in biological transformations. β2 contains the diferric tyrosyl radical (Y 122 ·) cofactor that initiates radical transfer (RT) over 35 Å via a specific pathway of amino acids (Y 122 · ⇆ [W 48 ] ⇆ Y 356 in β2 to Y 731 ⇆ Y 730 ⇆ C 439 in α2). Experimental evidence exists for colinear and orthogonal PCET in α2 and β2, respectively. No mechanistic model yet exists for the PCET across the subunit (α/β) interface. Here, we report unique EPR spectroscopic features of Y 356 ·-β, the pathway intermediate generated by the reaction of 2,3,5-F 3 Y 122 ·-β2/CDP/ATP with wt-α2, Y 731 F-α2, or Y 730 F-α2. High field EPR (94 and 263 GHz) reveals a dramatically perturbed g tensor. [ 1 H] and [ 2 H]-ENDOR reveal two exchangeable H bonds to Y 356 ·: a moderate one almost in-plane with the π-system and a weak one. DFT calculation on small models of Y· indicates that two in-plane, moderate H bonds (r O-H ∼1.8-1.9 Å) are required to reproduce the g x value of Y 356 · (wt-α2). The results are consistent with a model, in which a cluster of two, almost symmetrically oriented, water molecules provide the two moderate H bonds to Y 356 · that likely form a hydrogen bond network of water molecules involved in either the reversible PCET across the subunit interface or in H + release to the solvent during Y 356 oxidation.

  19. Research on the Effects of Process Parameters on Surface Roughness in Wet-Activated Silicon Direct Bonding Base on Orthogonal Experiments

    Directory of Open Access Journals (Sweden)

    Lei NIE

    2015-11-01

    Full Text Available Surface roughness is a very important index in silicon direct bonding and it is affected by processing parameters in the wet-activated process. These parameters include the concentration of activation solution, holding time and treatment temperature. The effects of these parameters were investigated by means of orthogonal experiments. In order to analyze the wafer roughness more accurately, the bear ratio of the surface was used as the evaluation index. From the results of the experiments, it could be concluded that the concentration of the activation solution affected the roughness directly and the higher the concentration, the lower the roughness. Holding time did not affect the roughness as acutely as that of the concentration, but a reduced activation time decreased the roughness perceptibly. It was also discovered that the treatment temperature had a weak correlation with the surface roughness. Based on these conclusions, the parameters of concentration, temperature and holding time were optimized respectively as NH4OH:H2O2=1:1 (without water, 70 °C and 5 min. The results of bonding experiments proved the validity of the conclusions of orthogonal experiments.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9711

  20. Synthesis of Fluorine-Containing 6-Arylpurine Derivatives via Cp*Co(III)-Catalyzed C-H Bond Activation.

    Science.gov (United States)

    Murakami, Nanami; Yoshida, Misaki; Yoshino, Tatsuhiko; Matsunaga, Shigeki

    2018-01-01

    Cp*Co(III)-catalyzed (Cp*=pentamethylcyclopentadienyl) C-H bond functionalization of 6-arylpurines using gem-difluoroalkenes and allyl fluorides is described. The reaction with gem-difluoroalkenes afforded monofluoroalkenes with high (Z)-selectivity, while the reaction with allyl fluorides led to C-H allylation in moderate (Z)-selectivity. Both reactions proceeded using a user-friendly single-component catalyst [Cp*Co(CH 3 CN) 3 ](SbF 6 ) 2 in fluorinated alcohol solvents without any additives. Robustness was also demonstrated by a preparative-scale reaction under air.

  1. H-bonding networks of the distal residues and water molecules in the active site of Thermobifida fusca hemoglobin.

    OpenAIRE

    Nicoletti , Francesco P; Droghetti , Enrica; Howes , Barry D; Bustamante , Juan P; Bonamore , Alessandra; Sciamanna , Natascia; Estrin , Darío A; Feis , Alessandro; Boffi , Alberto; Smulevich , Giulietta

    2013-01-01

    International audience; The ferric form of truncated hemoglobin II from Thermobifida fusca (Tf-trHb) and its triple mutant WG8F-YB10F-YCD1F at neutral and alkaline pH, and in the presence of CN(-) have been characterized by resonance Raman spectroscopy, electron paramagnetic resonance spectroscopy, and molecular dynamics simulations. Tf-trHb contains three polar residues in the distal site, namely TrpG8, TyrCD1 and TyrB10. Whereas TrpG8 can act as a potential hydrogen-bond donor, the tyrosine...

  2. In vitro activity of expanded-spectrum pyridazinyl oxime ethers related to pirodavir: novel capsid-binding inhibitors with potent antipicornavirus activity.

    Science.gov (United States)

    Barnard, D L; Hubbard, V D; Smee, D F; Sidwell, R W; Watson, K G W; Tucker, S P T; Reece, P A R

    2004-05-01

    Picornaviruses (PV) include human rhinovirus (HRV), the primary cause of the common cold, and the enteroviruses (EV), which cause serious diseases such as poliomyelitis, meningoencephalitis, and systemic neonatal disease. Although no compounds for PV infections have been approved in the United States, pirodavir was one of the most promising capsid-binding compounds to show efficacy in human clinical trials for chemoprophylaxis of the common cold. Susceptibility to hydrolysis precluded its use as an oral agent. We have developed orally bioavailable pyridazinyl oxime ethers that are as potent as pirodavir. Compounds BTA39 and BTA188 inhibited a total of 56 HRV laboratory strains and three clinical isolates as determined by neutral red uptake assay. At concentrations of poliovirus strain WM-1 at 204 nM, and BTA188 only inhibited poliovirus strain Chat at 82 nM. EV 71 was inhibited by BTA39 and BTA188, with IC(50)s of 1 and 82 nM, respectively. Both compounds were relatively nontoxic in actively growing cells (50% cytotoxic doses, >/=4,588 nM). These data suggest that these oxime ethers warrant further investigation as potential agents for treating selected PV infections.

  3. Activation of methane by zinc: gas-phase synthesis, structure, and bonding of HZnCH3.

    Science.gov (United States)

    Flory, Michael A; Apponi, Aldo J; Zack, Lindsay N; Ziurys, Lucy M

    2010-12-08

    The methylzinc hydride molecule, HZnCH3, has been observed in the gas phase for the first time in the monomeric form using high-resolution spectroscopic techniques. The molecule was synthesized by two methods: the reaction of dimethylzinc with hydrogen gas and methane in an AC discharge and the reaction of zinc vapor produced in a Broida-type oven with methane in a DC discharge. HZnCH3 was identified on the basis of its pure rotational spectrum, which was recorded using millimeter/submillimeter direct-absorption and Fourier transform microwave techniques over the frequency ranges 332-516 GHz and 18-41 GHz, respectively. Multiple rotational transitions were measured for this molecule in seven isotopic variants. K-ladder structure was clearly present in all of the spectra, indicating a molecule with C3v symmetry and a (1)A1 ground electronic state. Extensive quadrupole hyperfine structure arising from the (67)Zn nucleus was observed for the H(67)ZnCH3 species, suggesting covalent bonding to the zinc atom. From the multiple isotopic substitutions, a precise structure for HZnCH3 has been determined. The influence of the axial hydrogen atom slightly distorts the methyl group but stabilizes the Zn-C bond. This study suggests that HZnCH3 can be formed through the oxidative addition of zinc to methane in the gas phase under certain conditions. HZnCH3 is the first metal-methane insertion complex to be structurally characterized.

  4. Understanding Bonds - Denmark

    DEFF Research Database (Denmark)

    Rimmer, Nina Røhr

    2016-01-01

    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...

  5. Instability of expanding bacterial droplets.

    Science.gov (United States)

    Sokolov, Andrey; Rubio, Leonardo Dominguez; Brady, John F; Aranson, Igor S

    2018-04-03

    Suspensions of motile bacteria or synthetic microswimmers, termed active matter, manifest a remarkable propensity for self-organization, and formation of large-scale coherent structures. Most active matter research deals with almost homogeneous in space systems and little is known about the dynamics of strongly heterogeneous active matter. Here we report on experimental and theoretical studies on the expansion of highly concentrated bacterial droplets into an ambient bacteria-free fluid. The droplet is formed beneath a rapidly rotating solid macroscopic particle inserted in the suspension. We observe vigorous instability of the droplet reminiscent of a violent explosion. The phenomenon is explained in terms of continuum first-principle theory based on the swim pressure concept. Our findings provide insights into the dynamics of active matter with strong density gradients and significantly expand the scope of experimental and analytic tools for control and manipulation of active systems.

  6. Synthesis and structure of unprecedented samarium complex with bulky bis-iminopyrrolyl ligand via intramolecular C=N bond activation

    Energy Technology Data Exchange (ETDEWEB)

    Das, Suman; Anga, Srinivas; Harinath, Adimulam; Panda, Tarun K. [Department of Chemistry, Indian Institute of Technology, Hyderabad (India); Pada Nayek, Hari [Department of Applied Chemistry, Indian Institute of Technology, (ISM) Dhanbad, Jharkhand (India)

    2017-12-29

    An unprecedentate samarium complex of the molecular composition [{κ"3-{(Ph_2CH)N=CH}{sub 2}C{sub 4}H{sub 2}N}{κ"3-{(Ph_2CHN=CH)(Ph_2CHNCH)C_4H_2N}Sm}{sub 2}] (2), which was isolated by the reaction of a potassium salt of 2,5-bis{N-(diphenylmethyl)-iminomethyl}pyrrolyl ligand [K(THF){sub 2}{(Ph_2CH)N=CH}{sub 2}C{sub 4}H{sub 2}N] (1) with anhydrous samarium diiodide in THF at 60 C through the in situ reduction of imine bond is presented. The homoleptic samarium complex [[κ{sup 3}-{(Ph_2CH)-N=CH}{sub 2}C{sub 4}H{sub 2}N]{sub 3}Sm] (3) can also be obtained from the reaction of compound 1 with anhydrous samarium triiodide (SmI{sub 3}) in THF at 60 C. The molecular structures of complexes 2 and 3 were established by single-crystal X-ray diffraction analysis. The molecular structure of complex 2 reveals the formation of a C-C bond in the 2,5-bis{N-(diphenylmethyl)iminomethyl}pyrrole ligand moiety (Ph{sub 2}Py{sup -}). However, complex 3 is a homoleptic samarium complex of three bis-iminopyrrolyl ligands. In complex 2, the samarium ion adopts an octahedral arrangement, whereas in complex 3, a distorted three face-centered trigonal prismatic mode of nine coordination is observed around the metal ion. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Pressure bonding molybdenum alloy (TZM) to reaction-bonded silicon nitride

    International Nuclear Information System (INIS)

    Huffsmith, S.A.; Landingham, R.L.

    1978-01-01

    Topping cycles could boost the energy efficiencies of a variety of systems by using what is now waste heat. One such topping cycle uses a ceramic helical expander and would require that a reaction-bonded silicon nitride (RBSN) rotor be bonded to a shaft of TZM (Mo-0.5 wt % Ti-0.08 wt % Zr). Coupon studies show that TZM can be bonded to RBSN at 1300 0 C and 69 MPa if there is an interlayer of MoSi 2 . A layer of finely ground (10 μm) MoSi 2 facilitates bond formation and provides a thicker bond interface. The hardness and grain structure of the TZM and RBSN were not affected by the temperature and pressure required to bond the coupons

  8. Expanding mediation theory

    NARCIS (Netherlands)

    Verbeek, Peter P.C.C.

    2012-01-01

    In his article In Between Us, Yoni van den Eede expands existing theories of mediation into the realm of the social and the political, focusing on the notions of opacity and transparency. His approach is rich and promising, but two pitfalls should be avoided. First, his concept of ‘in-between’ runs

  9. Expression of the activation antigen CD69 predicts functionality of in vitro expanded peripheral blood mononuclear cells (PBMC) from healthy donors and HIV-infected patients

    DEFF Research Database (Denmark)

    Nielsen, S D; Afzelius, P; Ersbøll, A K

    1998-01-01

    Gene therapy for AIDS necessitates harvest and expansion of PBMC from HIV-infected patients. We expanded PBMC from healthy blood donors and HIV-infected patients for up to 14 days using four expansion protocols: 3 days of phytohaemagglutinin (PHA) stimulation, continuous PHA stimulation, 3 days...... examined for apoptosis. Only a minor fraction was primed for apoptosis, and this fraction could be significantly reduced by addition of IL-2 to the culture medium (P

  10. Siroheme- and [Fe4-S4]-dependent NirA from Mycobacterium tuberculosis is a sulfite reductase with a covalent Cys-Tyr bond in the active site.

    Science.gov (United States)

    Schnell, Robert; Sandalova, Tatyana; Hellman, Ulf; Lindqvist, Ylva; Schneider, Gunter

    2005-07-22

    The nirA gene of Mycobacterium tuberculosis is up-regulated in the persistent state of the bacteria, suggesting that it is a potential target for the development of antituberculosis agents particularly active against the pathogen in its dormant phase. This gene encodes a ferredoxin-dependent sulfite reductase, and the structure of the enzyme has been determined using x-ray crystallography. The enzyme is a monomer comprising 555 amino acids and contains a [Fe4-S4] cluster and a siroheme cofactor. The molecule is built up of three domains with an alpha/beta fold. The first domain consists of two ferredoxin-like subdomains, related by a pseudo-2-fold symmetry axis passing through the whole molecule. The other two domains, which provide much of the binding interactions with the cofactors, have a common fold that is unique to the sulfite/nitrite reductase family. The domains form a trilobal structure, with the cofactors and the active site located at the interface of all three domains in the center of the molecule. NirA contains an unusual covalent bond between the side chains of Tyr69 and Cys161 in the active site, in close proximity to the siroheme cofactor. Removal of this covalent bond by site-directed mutagenesis impairs catalytic activity, suggesting that it is important for the enzymatic reaction. These residues are part of a sequence fingerprint, able to distinguish between ferredoxin-dependent sulfite and nitrite reductases. Comparison of NirA with the structure of the truncated NADPH-dependent sulfite reductase from Escherichia coli suggests a binding site for the external electron donor ferredoxin close to the [Fe4-S4] cluster.

  11. The Human-Animal Bond: Implications for Practice.

    Science.gov (United States)

    Netting, F. Ellen; And Others

    1987-01-01

    Provides an overview of the rapidly expanding area of human-animal bonding. The historical background of human-animal bonding, the current multidisciplinary interest in companion animals, and theoretical perspectives are reviewed. The article examines programmatic and legislative developments in which social workers have participated and presents…

  12. Subsurface defect detection in first layer of pavement structure and reinforced civil engineering structure by FRP bonding using active infrared thermography

    Science.gov (United States)

    Dumoulin, Jean; Ibos, Laurent

    2010-05-01

    In many countries road network ages while road traffic and maintenance costs increase. Nowadays, thousand and thousand kilometers of roads are each year submitted to surface distress survey. They generally lean on pavement surface imaging measurement techniques, mainly in the visible spectrum, coupled with visual inspection or image processing detection of emergent distresses. Nevertheless, optimisation of maintenance works and costs requires an early detection of defects within the pavement structure when they still are hidden from surface. Accordingly, alternative measurement techniques for pavement monitoring are currently under investigation (seismic methods, step frequency radar). On the other hand, strengthening or retrofitting of reinforced concrete structures by externally bonded Fiber Reinforced Polymer (FRP) systems is now a commonly accepted and widespread technique. However, the use of bonding techniques always implies following rigorous installing procedures. To ensure the durability and long-term performance of the FRP reinforcements, conformance checking through an in situ auscultation of the bonded FRP systems is then highly suitable. The quality-control program should involve a set of adequate inspections and tests. Visual inspection and acoustic sounding (hammer tap) are commonly used to detect delaminations (disbonds) but are unable to provide sufficient information about the depth (in case of multilayered composite) and width of debonded areas. Consequently, rapid and efficient inspection methods are also required. Among the non destructive methods under study, active infrared thermography was investigated both for pavement and civil engineering structures through experiments in laboratory and numerical simulations, because of its ability to be also used on field. Pulse Thermography (PT), Pulse Phase Thermography (PPT) and Principal Component Thermography (PCT) approaches have been tested onto pavement samples and CFRP bonding on concrete

  13. Grazing incidence beam expander

    Energy Technology Data Exchange (ETDEWEB)

    Akkapeddi, P.R.; Glenn, P.; Fuschetto, A.; Appert, Q.; Viswanathan, V.K.

    1985-01-01

    A Grazing Incidence Beam Expander (GIBE) telescope is being designed and fabricated to be used as an equivalent end mirror in a long laser resonator cavity. The design requirements for this GIBE flow down from a generic Free Electron Laser (FEL) resonator. The nature of the FEL gain volume (a thin, pencil-like, on-axis region) dictates that the output beam be very small. Such a thin beam with the high power levels characteristic of FELs would have to travel perhaps hundreds of meters or more before expanding enough to allow reflection from cooled mirrors. A GIBE, on the other hand, would allow placing these optics closer to the gain region and thus reduces the cavity lengths substantially. Results are presented relating to optical and mechanical design, alignment sensitivity analysis, radius of curvature analysis, laser cavity stability analysis of a linear stable concentric laser cavity with a GIBE. Fabrication details of the GIBE are also given.

  14. Expandable LED array interconnect

    Science.gov (United States)

    Yuan, Thomas Cheng-Hsin; Keller, Bernd

    2011-03-01

    A light emitting device that can function as an array element in an expandable array of such devices. The light emitting device comprises a substrate that has a top surface and a plurality of edges. Input and output terminals are mounted to the top surface of the substrate. Both terminals comprise a plurality of contact pads disposed proximate to the edges of the substrate, allowing for easy access to both terminals from multiple edges of the substrate. A lighting element is mounted to the top surface of the substrate. The lighting element is connected between the input and output terminals. The contact pads provide multiple access points to the terminals which allow for greater flexibility in design when the devices are used as array elements in an expandable array.

  15. Expanding the HAWC Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Johanna [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-17

    The High Altitude Water Cherenkov Gamma-Ray Observatory is expanding its current array of 300 water tanks to include 350 outrigger tanks to increase sensitivity to gamma rays above 10 TeV. This involves creating and testing hardware with which to build the new tanks, including photomultiplier tubes, high voltage supply units, and flash analog to digital converters. My responsibilities this summer included preparing, testing and calibrating that equipment.

  16. 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...

  17. Demonstration of Subscale Cermet Fuel Specimen Fabrication Approach Using Spark Plasma Sintering and Diffusion Bonding

    Science.gov (United States)

    Barnes, Marvin W.; Tucker, Dennis S.; Benensky, Kelsa M.

    2018-01-01

    Nuclear thermal propulsion (NTP) has the potential to expand the limits of human space exploration by enabling crewed missions to Mars and beyond. The viability of NTP hinges on the development of a robust nuclear fuel material that can perform in the harsh operating environment (> or = 2500K, reactive hydrogen) of a nuclear thermal rocket (NTR) engine. Efforts are ongoing to develop fuel material and to assemble fuel elements that will be stable during the service life of an NTR. Ceramic-metal (cermet) fuels are being actively pursued by NASA Marshall Space Flight Center (MSFC) due to their demonstrated high-temperature stability and hydrogen compatibility. Building on past cermet fuel development research, experiments were conducted to investigate a modern fabrication approach for cermet fuel elements. The experiments used consolidated tungsten (W)-60vol%zirconia (ZrO2) compacts that were formed via spark plasma sintering (SPS). The consolidated compacts were stacked and diffusion bonded to assess the integrity of the bond lines and internal cooling channel cladding. The assessment included hot hydrogen testing of the manufactured surrogate fuel and pure W for 45 minutes at 2500 K in the compact fuel element environmental test (CFEET) system. Performance of bonded W-ZrO2 rods was compared to bonded pure W rods to access bond line integrity and composite stability. Bonded surrogate fuels retained structural integrity throughout testing and incurred minimal mass loss.

  18. X hydrogen bonds

    Indian Academy of Sciences (India)

    sigma electrons, can be hydrogen bond acceptors.11–14. The recent IUPAC report and recommendation on hydro gen bond have recognised the diverse nature of hydro- gen bond donors and acceptors.13,14. Unlike methane, hydrogen bonding by higher alkanes has not received much attention. One of the earlier works.

  19. C-N Bond Activation and Ring Opening of a Saturated N-Heterocyclic Carbene by Lateral Alkali-Metal-Mediated Metalation.

    Science.gov (United States)

    Hernán-Gómez, Alberto; Kennedy, Alan R; Hevia, Eva

    2017-06-01

    Combining alkali-metal-mediated metalation (AMMM) and N-heterocyclic carbene (NHC) chemistry, a novel C-N bond activation and ring-opening process is described for these increasingly important NHC molecules, which are generally considered robust ancillary ligands. Here, mechanistic investigations on reactions of saturated NHC SIMes (SIMes=[:C{N(2,4,6-Me 3 C 6 H 2 )CH 2 } 2 ]) with Group 1 alkyl bases suggest this destructive process is triggered by lateral metalation of the carbene. Exploiting co-complexation and trans-metal-trapping strategies with lower polarity organometallic reagents (Mg(CH 2 SiMe 3 ) 2 and Al(TMP)iBu 2 ), key intermediates in this process have been isolated and structurally defined. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Adhesive wafer bonding

    Science.gov (United States)

    Niklaus, F.; Stemme, G.; Lu, J.-Q.; Gutmann, R. J.

    2006-02-01

    Wafer bonding with intermediate polymer adhesives is an important fabrication technique for advanced microelectronic and microelectromechanical systems, such as three-dimensional integrated circuits, advanced packaging, and microfluidics. In adhesive wafer bonding, the polymer adhesive bears the forces involved to hold the surfaces together. The main advantages of adhesive wafer bonding include the insensitivity to surface topography, the low bonding temperatures, the compatibility with standard integrated circuit wafer processing, and the ability to join different types of wafers. Compared to alternative wafer bonding techniques, adhesive wafer bonding is simple, robust, and low cost. This article reviews the state-of-the-art polymer adhesive wafer bonding technologies, materials, and applications.

  1. Computational study of the double C-Cl bond activation of dichloromethane and phosphine alkylation at [CoCl(PR3)3].

    Science.gov (United States)

    Algarra, Andrés G; Braunstein, Pierre; Macgregor, Stuart A

    2013-03-28

    Density functional theory calculations have been employed to model the double C-Cl bond activation of CH(2)Cl(2) at [CoCl(PR(3))(3)] to give [CoCl(3)(CH(2)PR(3))(PR(3))(2)]. Calculations incorporating dichloromethane solution (PCM approach) on a [CoCl(PMe(3))(3)] model system showed the two C-Cl cleavage steps to involve different mechanisms. The first C-Cl cleavage step occurs on the triplet surface and proceeds via Cl abstraction with a barrier of 19.1 kcal mol(-1). Radical recombination would then give singlet mer,trans-[CoCl(2)(CH(2)Cl)(PMe(3))(3)] with an overall free energy change of +1.8 kcal mol(-1). Alternative C-Cl activation processes based on nucleophilic attack by the Co centre at dichloromethane with loss of Cl(-) have significantly higher barriers. The second C-Cl cleavage occurs via nucleophilic attack of PMe(3) at the CH(2)Cl ligand with formation of a new P-C bond and displacement of Cl(-). This may either occur in an intermolecular fashion (after prior PMe(3) dissociation) or intramolecularly. Both processes have similar barriers of ca. 12 kcal mol(-1). The comproportionation of [CoCl(3)(CH(2)PMe(3))(PMe(3))(2)] with [CoCl(PMe(3))(3)] to give [CoCl(2)(CH(2)PMe(3))(PMe(3))], [CoCl(2)(PMe(3))(2)] and 2 PMe(3) is computed to be strongly exergonic, consistent with the observation of this process in analogous experimental systems.

  2. Experimentally calibrated computational chemistry of tryptophan hydroxylase: Trans influence, hydrogen-bonding, and 18-electron rule govern O-2-activation

    DEFF Research Database (Denmark)

    Haahr, Lærke Tvedebrink; Kepp, Kasper Planeta; Boesen, Jane

    2010-01-01

    with the experimental value (0.25 mm/s) which we propose as the structure of the hydroxylating intermediate, with the tryptophan substrate well located for further reaction 3.5 Å from the ferryl group. Based on the optimized transition states, the activation barriers for the two paths (glu and his) are similar, so...... a two-state scenario involving Ohis and Pglu is possible. A structure of the activated deoxy state which is high-spin implies that the valence electron count has been lowered from 18 to 16 (glutamate becomes bidentate), giving a “green light” that invites O2-binding. Our mechanism of oxygen activation...

  3. Expanding Your Horizon 2015

    CERN Multimedia

    Kaltenhauser, Kristin

    2015-01-01

    Expanding your horizons is a bi-annual “Science Day” for girls aged 11 to 14, held at the University of Geneva on 14 November. The girls had the opportunity to take part in hands-on workshops held by local professional women in the field of science, mathematics, engineering and technology. For the fourth time, CERN was part of this event, offering three workshops as well as a booth at the Discovery Fair, including Higgnite, an interactive visualization of the Higgs Field.

  4. The expanding universe

    CERN Document Server

    Lew, Kristi

    2011-01-01

    People have always been fascinated with the stars above and the universe that contains them. Over the years, astronomers have developed numerous theories to explain how the universe began, how it works, and what its ultimate fate will be. But all of the scientists' questions are far from answered. The Expanding Universe goes beyond the creation of the universe to explain how scientists think the universe works, grows, and changes, including what great thinkers Isaac Newton and Albert Einstein had to say about its fate. Readers will also learn about how researchers are slowly shedding light on

  5. An Active Insect Kinin Analog with 4-Aminopyroglutamate, A Novel cis-Peptide Bond, Type VI beta-Turn Motif

    Science.gov (United States)

    2004-01-01

    Kinin Analogs in the Cricket Acheta domesticus Peptidomimetic Analog Stimulation of Malpighian Tubule Fluid Secretion-EC50 (10 7M) (% maximal...Malpighian tubule fluid secretion in the cricket, Acheta domesticus . Active Insect Kinin Analog with Type VI Turn-Mimic 4-Aminopyroglutamate 415 zole moiety

  6. Tissue expander infections in children: look beyond the expander pocket.

    Science.gov (United States)

    Mason, A C; Davison, S P; Manders, E K

    1999-11-01

    Infection of the expander pocket is the most common complication encountered with soft-tissue expansion. It is usually due to direct inoculation with skin flora either at the time of expander insertion or from extrusion of the device. The authors report two cases of infection of tissue expanders in which the children had concomitant infected sites distant from the prosthesis. Etiological bacteria of common pediatric infections like otitis media and pharyngitis were cultured from the infected expander pocket, raising suspicion that translocation of the organism to the expander had occurred. Aggressive antibiotic treatment, removal of the prosthesis, and flap advancement is advocated.

  7. Expanding hollow metal rings

    Science.gov (United States)

    Peacock, Harold B [Evans, GA; Imrich, Kenneth J [Grovetown, GA

    2009-03-17

    A sealing device that may expand more planar dimensions due to internal thermal expansion of a filler material. The sealing material is of a composition such that when desired environment temperatures and internal actuating pressures are reached, the sealing materials undergoes a permanent deformation. For metallic compounds, this permanent deformation occurs when the material enters the plastic deformation phase. Polymers, and other materials, may be using a sealing mechanism depending on the temperatures and corrosivity of the use. Internal pressures are generated by either rapid thermal expansion or material phase change and may include either liquid or solid to gas phase change, or in the gaseous state with significant pressure generation in accordance with the gas laws. Sealing material thickness and material composition may be used to selectively control geometric expansion of the seal such that expansion is limited to a specific facing and or geometric plane.

  8. Expandable pattern casting research

    Science.gov (United States)

    1993-09-01

    The Expandable Pattern Casting (EPC) Process is a developing foundry technology that allows designers the opportunity to consolidate parts, reduce machining, and minimize assembly operations. An air gauging system was developed for measuring foam patterns; exact shrinkage depended on type and density of the foam. Compaction studies showed that maximum sand densities in cavities and under overhangs are achieved with vibrational amplitudes 0.001-0.004 in., and that sand moved most freely within a few inches of the top free surface. Key to complete mold filling while minimizing casting defects lies in removing the foam decomposition products. The most precise iron castings were made by EPC in four commercial EPC foundries, with attention paid to molding and compaction. EP cast 60-45-12 ductile iron had yield strengths, ultimate strengths, and elastic modulus similar to conventionally cast ductile iron cast from the same ladle.

  9. Expanding or postponing?

    DEFF Research Database (Denmark)

    Jensen, Tanja Dall; Caswell, Dorte

    2017-01-01

    setting. Working with data from 97 team meetings in a social work setting, we identify two patterns of negotiation in talk; expanding and postponing. ‘Expanding’ covers a group of interactional actions involving turn-taking and closure, while ‘postponing’ includes a group of actions whereby assessments......In this paper, we examine patterns of negotiation in multi-party interaction in social work. We draw on Strauss’ theory of negotiated order and a conversation analytical approach, seeking to gain insight into the complex accomplishment of making a decision in an inter-professional and multiparty...... or topics are avoided or made irrelevant. Both are examples of the complex ways in which team members negotiate both the institutional order and the decision to be made in the specific case in situ....

  10. Proton migration in portlandite inferred from activation energy of self-diffusion and potential energy curve of OH bond

    Science.gov (United States)

    Noguchi, Naoki; Shinoda, Keiji

    2010-06-01

    A fundamental mechanism on the atomic level for self-diffusion in the proton layer of portlandite, Ca(OH)2, was investigated by conducting hydrogen-deuterium (H-D) exchange diffusion experiments and by deriving potential energy curves of OH vibrations from optical absorption measurements. Synthetic single crystals of portlandite were used in H-D experiments between 250 and 450°C at 150 MPa. Arrhenius parameters for proton diffusion perpendicular to the c-axis gave a frequency factor of 1.0 × 10-10 m2/s and activation energy of 0.61 eV (58.5 kJ/mol). The activation energy corresponds to the height of the potential barrier between two oxygen atoms across an interlayer. The potential barrier height was also theoretically estimated using the OH potential energy curve (OH-PEC) determined by optical absorption measurements. Experimental and theoretical results suggest that the potential barrier height cannot be simply determined by overlapping two OH-PECs. The potential barrier derived theoretically was 3.11 eV. This is too high for the activation energy of the proton diffusion. It implies that the interaction between a diffusing proton and the vacancy of a proton site, and the shortening of interlayer oxygen distance by thermal vibration reduce the potential barrier.

  11. Palladium on Layered Double Hydroxide: A Heterogeneous System for the Enol Phosphate Carbon-Oxygen Bond Activation in Aqueous Media

    Directory of Open Access Journals (Sweden)

    Jaqueline D. Senra

    2017-01-01

    Full Text Available In this work, a new catalytic approach for the C-O activation of enol phosphates based on a palladium supported on layered double hydroxide was developed. In this case, two different ketene aminal phosphates were used as models to study the synthesis of α-phenyl enecarbamates N-Boc/CBz under the Suzuki-Miyaura conditions. The use of an ortho-bromoaniline as precursor allowed the synthesis of the 2-phenyl indole through an arylation/Heck cyclization. Catalyst reusability enabled the synthesis of the heterocycle in moderate yields for four consecutive runs.

  12. PM6 study of free radical scavenging mechanisms of flavonoids: why does O-H bond dissociation enthalpy effectively represent free radical scavenging activity?

    Science.gov (United States)

    Amić, Dragan; Stepanić, Višnja; Lučić, Bono; Marković, Zoran; Dimitrić Marković, Jasmina M

    2013-06-01

    It is well known that the bond dissociation enthalpy (BDE) of the O-H group is related to the hydrogen atom transfer (HAT) mechanism of free radical scavenging that is preferred in gas-phase and non-polar solvents. The present work shows that the BDE may also be related to radical scavenging processes taking place in polar solvents, i.e., single electron transfer followed by proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET). This is so because the total energy requirements related to the SET-PT [sum of the ionization potential (IP) and proton dissociation enthalpy (PDE)] and the SPLET [sum of the proton affinity (PA) and electron transfer enthalpy (ETE)] are perfectly correlated with the BDE. This could explain why the published data for polyphenolic antioxidant activity measured by various assays are better correlated with the BDE than with other reaction enthalpies involved in radical scavenging mechanisms, i.e., the IP, PDE, PA and ETE. The BDE is fairly well able to rank flavonoids as antioxidants in any medium, but to conclude which radical scavenging mechanism represents the most probable reaction pathway from the thermodynamic point of view, the IP and PA (ETE) should also be considered. This is exemplified in the case of the radical scavenging activity of 25 flavonoids.

  13. SHEAR ACCELERATION IN EXPANDING FLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Rieger, F. M. [ZAH, Institut für Theoretische Astrophysik, Universität Heidelberg, Philosophenweg 12, D-69120 Heidelberg (Germany); Duffy, P., E-mail: frank.rieger@mpi-hd.mpg.de, E-mail: peter.duffy@ucd.ie [University College Dublin, Belfield, Dublin 4 (Ireland)

    2016-12-10

    Shear flows are naturally expected to occur in astrophysical environments and potential sites of continuous non-thermal Fermi-type particle acceleration. Here we investigate the efficiency of expanding relativistic outflows to facilitate the acceleration of energetic charged particles to higher energies. To this end, the gradual shear acceleration coefficient is derived based on an analytical treatment. The results are applied to the context of the relativistic jets from active galactic nuclei. The inferred acceleration timescale is investigated for a variety of conical flow profiles (i.e., power law, Gaussian, Fermi–Dirac) and compared to the relevant radiative and non-radiative loss timescales. The results exemplify that relativistic shear flows are capable of boosting cosmic-rays to extreme energies. Efficient electron acceleration, on the other hand, requires weak magnetic fields and may thus be accompanied by a delayed onset of particle energization and affect the overall jet appearance (e.g., core, ridge line, and limb-brightening).

  14. The Artful Universe Expanded

    Energy Technology Data Exchange (ETDEWEB)

    Bassett, B A [Institute of Cosmology and Gravitation, University of Portsmouth (United Kingdom)

    2005-07-29

    The cosmos is an awfully big place and there is no better guide to its vast expanse and fascinating nooks and crannies than John Barrow. A professor of mathematical sciences at Cambridge University, Barrow embodies that rare combination of highly polished writer and expert scientist. His deft touch brings together the disparate threads of human knowledge and weaves them into a tapestry as rich and interesting for the expert as it is for the layperson. The Artful Universe Expanded is an updated edition of this popular book first published in 1995. It explores the deeply profound manner in which natural law and the nature of the cosmos have moulded and shaped us, our cultures and the very form of our arts and music-a new type of 'cosmic' anthropology. The main themes Barrow chooses for revealing this new anthropology are the subjects of evolution, the size of things, the heavens and the nature of music. The book is a large, eclectic repository of knowledge often unavailable to the layperson, hidden in esoteric libraries around the world. It rivals The Da Vinci Code for entertainment value and insights, but this time it is Nature's code that is revealed. It is rare indeed to find common threads drawn through topics as diverse as The Beetles, Bach and Beethoven or between Jackson Pollock, the Aztecs, Kant, Picasso, Byzantine mosaics, uranium-235 and the helix nebula. Barrow unerringly binds them together, presenting them in a stimulating, conversational style that belies the amount of time that must have gone into researching this book. Dip into it at random, or read it from cover to cover, but do read it. The Artful Universe Expanded is an entertaining antidote to the oft-lamented pressures to know more and more about less and less and the apparently inexorable march of specialization. On reading this book one can, for a short time at least, hold in one's mind a vision that unifies science, art and culture and glimpse a universal tapestry of great

  15. The Artful Universe Expanded

    International Nuclear Information System (INIS)

    Bassett, B A

    2005-01-01

    The cosmos is an awfully big place and there is no better guide to its vast expanse and fascinating nooks and crannies than John Barrow. A professor of mathematical sciences at Cambridge University, Barrow embodies that rare combination of highly polished writer and expert scientist. His deft touch brings together the disparate threads of human knowledge and weaves them into a tapestry as rich and interesting for the expert as it is for the layperson. The Artful Universe Expanded is an updated edition of this popular book first published in 1995. It explores the deeply profound manner in which natural law and the nature of the cosmos have moulded and shaped us, our cultures and the very form of our arts and music-a new type of 'cosmic' anthropology. The main themes Barrow chooses for revealing this new anthropology are the subjects of evolution, the size of things, the heavens and the nature of music. The book is a large, eclectic repository of knowledge often unavailable to the layperson, hidden in esoteric libraries around the world. It rivals The Da Vinci Code for entertainment value and insights, but this time it is Nature's code that is revealed. It is rare indeed to find common threads drawn through topics as diverse as The Beetles, Bach and Beethoven or between Jackson Pollock, the Aztecs, Kant, Picasso, Byzantine mosaics, uranium-235 and the helix nebula. Barrow unerringly binds them together, presenting them in a stimulating, conversational style that belies the amount of time that must have gone into researching this book. Dip into it at random, or read it from cover to cover, but do read it. The Artful Universe Expanded is an entertaining antidote to the oft-lamented pressures to know more and more about less and less and the apparently inexorable march of specialization. On reading this book one can, for a short time at least, hold in one's mind a vision that unifies science, art and culture and glimpse a universal tapestry of great beauty. (book review)

  16. 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 ...

  17. Expanding the Catalytic Promiscuity of Heparinase III from Pedobacter heparinus.

    Science.gov (United States)

    Gu, Yayun; Lu, Meiling; Wang, Zongqiang; Wu, Xuri; Chen, Yijun

    2017-02-21

    Glycosaminoglycans (GAG) lyases are useful biocatalysts for the preparation of oligosaccharides, but their substrate spectra are limited to the same family. Thus, the degradation activity across families of GAG lyases is advantageous and desirable for various applications. In this study, residue Lys130 at the substrate entrance of monomeric heparinase III from Pedobacter heparinus ATCC 13125 was replaced by cysteine, and the resulting mutant K130C showed novel catalytic activity in degrading hyaluronic acid without affecting its native activity toward heparin and heparan sulfate. The broadened catalytic promiscuity by mutant K130C was the result of dimerization through a disulfide bond to expand the substrate binding pocket. This bifunctional enzyme is potentially valuable in the degradation of different types of GAGs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. 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

  19. Nickel-Catalyzed Alkoxy-Alkyl Interconversion with Alkylborane Reagents through C−O Bond Activation of Aryl and Enol Ethers

    KAUST Repository

    Guo, Lin

    2016-11-07

    A nickel-catalyzed alkylation of polycyclic aromatic methyl ethers as well as methyl enol ethers with B-alkyl 9-BBN and trialkylborane reagents that involves the cleavage of stable C(sp2)−OMe bonds is described. The transformation has a wide substrate scope and good chemoselectivity profile while proceeding under mild reaction conditions; it provides a versatile way to form C(sp2)−C(sp3) bonds that does not suffer from β-hydride elimination. Furthermore, a selective and sequential alkylation process by cleavage of inert C−O bonds is presented to demonstrate the advantage of this method.

  20. The Artful Universe Expanded

    Science.gov (United States)

    Barrow, John D.

    2005-07-01

    Our love of art, writes John Barrow, is the end product of millions of years of evolution. How we react to a beautiful painting or symphony draws upon instincts laid down long before humans existed. Now, in this enhanced edition of the highly popular The Artful Universe , Barrow further explores the close ties between our aesthetic appreciation and the basic nature of the Universe. Barrow argues that the laws of the Universe have imprinted themselves upon our thoughts and actions in subtle and unexpected ways. Why do we like certain types of art or music? What games and puzzles do we find challenging? Why do so many myths and legends have common elements? In this eclectic and entertaining survey, Barrow answers these questions and more as he explains how the landscape of the Universe has influenced the development of philosophy and mythology, and how millions of years of evolutionary history have fashioned our attraction to certain patterns of sound and color. Barrow casts the story of human creativity and thought in a fascinating light, considering such diverse topics as our instinct for language, the origins and uses of color in nature, why we divide time into intervals as we do, the sources of our appreciation of landscape painting, and whether computer-generated fractal art is really art. Drawing on a wide variety of examples, from the theological questions raised by St. Augustine and C.S. Lewis to the relationship between the pure math of Pythagoras and the music of the Beatles, The Artful Universe Expanded covers new ground and enters a wide-ranging debate about the meaning and significance of the links between art and science.

  1. Transport characteristics of minority electrons across surface-activated-bonding based p-Si/n-4H-SiC heterointerfaces

    Science.gov (United States)

    Shigekawa, Naoteru; Shimizu, Sae; Liang, Jianbo; Shingo, Masato; Shiojima, Kenji; Arai, Manabu

    2018-02-01

    We investigate the transport properties of minority electrons across p-Si/n-4H-SiC interfaces fabricated using surface activated bonding. The transport properties along each direction are examined by measuring the photoresponse (PR) of p-Si/n-4H-SiC heterojunctions and characterizing 4H-SiC/Si heterojunction bipolar transistors (HBTs). The photoyield obtained in PR measurements is sensitive to the concentration of acceptors in p-Si and reverse-bias voltages, which indicates that the energy of optically excited electrons in p-Si is first relaxed and then they are driven to n-SiC through the tunneling process. By the postprocess annealing of HBTs, the properties of emitter/base interfaces are improved so that the current gain is drastically increased, which means that the Si/4H-SiC interfaces are in metastable states when the device process is completed. A maximum current gain of >10 is demonstrated.

  2. Expanding Public/Private Partnerships For Improving Basic Education through School Sponsorship in the Dominican Republic. Final Report. Basic Education and Policy Support Activity.

    Science.gov (United States)

    Craig, Patricia; Kane, Michael

    The Basic Education and Policy Support Activity (BEPS), a new five-year initiative sponsored by United States Agency for International Development's (USAID) Center for Human Capacity Development, is designed to improve the quality, effectiveness, and access to formal and nonformal basic education. BEPS operates through both core funds and buy-ins…

  3. C(sp₃)-H bond activation with triel metals: indium and gallium zwitterions through internal hydride abstraction in rigid salan ligands.

    Science.gov (United States)

    Maudoux, Nicolas; Fang, Jian; Roisnel, Thierry; Dorcet, Vincent; Maron, Laurent; Carpentier, Jean-François; Sarazin, Yann

    2014-06-16

    The hydropyrimidine salan (salan=N,N'-dimethyl-N,N'-bis[(2-hydroxyphenyl)methylene]-1,2-diaminoethane) proteo-ligands with a rigid backbone {ON^(CH2)^NO}H2 react with M(CH2SiMe3)3 (M=Ga, In) to yield the zwitterions {ON^(CH(+))^NO}M(-)(CH2SiMe3)2 (M=Ga, 2; In, 3) by abstraction of a hydride from the ligand backbone followed by elimination of dihydrogen. By contrast, with Al2Me6, the neutral-at-metal bimetallic complex [{ON^(CH2)^NO}AlMe]2 ([1]2) is obtained quantitatively. The formation of indium zwitterions is also observed with sterically more encumbered ligands containing o-Me substituents on the phenolic rings, or an N (CHPh) N moiety in the heterocyclic core. Overall, the ease of C(sp3)-H bond activation follows the order Al≪Gahydride species. DFT calculations indicate that the systems {ON^(CH2)^NO}H2+M(CH2SiMe3)3 (M=Al, Ga, In) all initially lead to the formation of the neutral monophenolate dihydrocarbyl species through a single protonolysis. From here, the thermodynamic product, the model neutral-at-metal complex 1, is formed in the case of aluminum after a second protonolysis. On the other hand, lower activation energy pathways lead to the generation of zwitterionic complexes 2 and 3 in the cases of gallium and indium, and the formation of these zwitterions obeys a strict kinetic control; the computations suggest that, as inferred from the experimental data, the reaction proceeds through an instable metal-hydride species, which could not be isolated synthetically. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Leishmania-specific T cells expressing interferon-¿(IFN-¿) and IL-10 upon activation are expanded in individuals cured of visceral leishmaniasis

    DEFF Research Database (Denmark)

    Kemp, K; Kemp, M; Kharazmi, A

    1999-01-01

    Peripheral blood mononuclear cells (PBMC) from patients who have recovered from visceral leishmaniasis often respond to Leishmania antigens in vitro by production of both IL-4, IFN-gamma and IL-10. In order to establish the cellular sources of these cytokines, we activated cells from individuals...... with a history of visceral leishmaniasis with Leishmania antigen for 6 days in culture, and identified cytokine production at the single-cell level by flow cytometry. The cytokines were only found in CD3+ cells and among these mainly within the CD4+ subset. The percentage of cytokine-producing cells was compared...... in Leishmania-activated PBMC cultures from the previous patients and from individuals living in a village where leishmaniasis does not occur. The percentage of IL-10- and IFN-gamma-containing cells was significantly higher in the previous patients than in the controls, indicating that Leishmania-specific T...

  5. The Expanding Universe: Dark Energy

    Energy Technology Data Exchange (ETDEWEB)

    Lincoln, Don [Fermilab; Nord, Brian [Fermilab

    2014-09-01

    In 1998, observations of distant supernovae led physicists that not only was the universe expanding, but the expansion was speeding up. In this article, we describe the evidence for an expanding universe and describe what physicists and cosmologists have learned in the intervening years. The target audience for this article is high school physics teachers and college physics professors at teaching institutions.

  6. Iridium complexes containing mesoionic C donors: selective C(sp3)-H versus C(sp2)-H bond activation, reactivity towards acids and bases, and catalytic oxidation of silanes and water.

    Science.gov (United States)

    Petronilho, Ana; Woods, James A; Mueller-Bunz, Helge; Bernhard, Stefan; Albrecht, Martin

    2014-11-24

    Metalation of a C2-methylated pyridylimidazolium salt with [IrCp*Cl2]2 affords either an ylidic complex, resulting from C(sp(3))-H bond activation of the C2-bound CH3 group if the metalation is performed in the presence of a base, such as AgO2 or Na2CO3, or a mesoionic complex via cyclometalation and thermally induced heterocyclic C(sp(2))-H bond activation, if the reaction is performed in the absence of a base. Similar cyclometalation and complex formation via C(sp(2))-H bond activation is observed when the heterocyclic ligand precursor consists of the analogous pyridyltriazolium salt, that is, when the metal bonding at the C2 position is blocked by a nitrogen rather than a methyl substituent. Despite the strongly mesoionic character of both the imidazolylidene and the triazolylidene, the former reacts rapidly with D(+) and undergoes isotope exchange at the heterocyclic C5 position, whereas the triazolylidene ligand is stable and only undergoes H/D exchange under basic conditions, where the imidazolylidene is essentially unreactive. The high stability of the Ir-C bond in aqueous solution over a broad pH range was exploited in catalytic water oxidation and silane oxidation. The catalytic hydrosilylation of ketones proceeds with turnover frequencies as high as 6,000 h(-1) with both the imidazolylidene and the triazolylidene system, whereas water oxidation is enhanced by the stronger donor properties of the imidazol-4-ylidene ligands and is more than three times faster than with the triazolylidene analogue. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Aliphatic C-H activation with aluminium trichloride-acetyl chloride: expanding the scope of the Baddeley reaction for the functionalisation of saturated hydrocarbons.

    Science.gov (United States)

    Lyall, Catherine L; Uosis-Martin, Mario; Lowe, John P; Mahon, Mary F; Pantoş, G Dan; Lewis, Simon E

    2013-03-07

    The functionalisation of decalin by means of an "aliphatic Friedel-Crafts" reaction was reported over fifty years ago by Baddeley et al. This protocol is of current relevance in the context of C-H activation and here we demonstrate its applicability to a range of other saturated hydrocarbons. Structural elucidation of the products is described and a mechanistic rationale for their formation is presented. The "aliphatic Friedel-Crafts" procedure allows for production of novel oxygenated building blocks from abundant hydrocarbons and as such can be considered to add significant synthetic value in a single step.

  8. Expanding the family of heteroleptic oxidovanadium(IV) compounds with salicylaldehyde semicarbazones and polypyridyl ligands showing anti-Trypanosoma cruzi activity.

    Science.gov (United States)

    Scalese, Gonzalo; Benítez, Julio; Rostán, Santiago; Correia, Isabel; Bradford, Lara; Vieites, Marisol; Minini, Lucía; Merlino, Alicia; Coitiño, E Laura; Birriel, Estefania; Varela, Javier; Cerecetto, Hugo; González, Mercedes; Pessoa, João Costa; Gambino, Dinorah

    2015-06-01

    Searching for prospective vanadium-based drugs for the treatment of Chagas disease, a new series of heteroleptic [V(IV)O(L-2H)(NN)] compounds was developed by including the lipophilic 3,4,7,8-tetramethyl-1,10-phenanthroline (tmp) NN ligand and seven tridentate salicylaldehyde semicarbazone derivatives (L1-L7). The compounds were characterized in the solid state and in solution. EPR spectroscopy suggests that the NN ligand is bidentate bound through both nitrogen donor atoms in an axial-equatorial mode. The EPR and (51)V-NMR spectra of aerated solutions at room temperature indicate that the compounds are stable to hydrolysis and that no significant oxidation of V(IV) to V(V) takes place at least in 24h. The complexes are more active in vitro against Trypanosoma cruzi, the parasite responsible for Chagas disease, than the reference drug Nifurtimox and most of them are more active than previously reported [V(IV)O(L-2H)(NN)] complexes of other NN co-ligands. Selectivity towards the parasite was analyzed using J-774 murine macrophages as mammalian cell model. Due to both, high activity and high selectivity, L2, L4, L5 and L7 complexes could be considered new hits for further drug development. Lipophilicity probably plays a relevant role in the bioactivity of the new compounds. The [V(IV)O(L-2H)(NN)] compounds were designed aiming DNA as potential molecular target. Therefore, the novel L1-L7 tmp complexes were screened by computational modeling, comparing their DNA-binding features with those of previously reported [V(IV)O(L-2H)(NN)] compounds with different NN co-ligands. Whereas all the complexes interact well with DNA, with binding modes and strength tuned in different extents by the NN and semicarbazone co-ligands, molecular docking suggests that the observed anti-T. cruzi activity cannot be explained upon DNA intercalation as the sole mechanism of action. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Direct arylation of benzene with aryl bromides using high-temperature/high-pressure process windows: expanding the scope of C-H activation chemistry.

    Science.gov (United States)

    Pieber, Bartholomäus; Cantillo, David; Kappe, C Oliver

    2012-04-16

    A detailed investigation on the direct arylation of benzene with aryl bromides by using first-row transition metals under high-temperature/high-pressure (high-T/p) conditions is described. By employing a parallel reactor platform for rapid reaction screening and discovery at elevated temperatures, various metal/ligand/base combinations were evaluated for their ability to enable biaryl formation through C-H activation. The combination of cobalt(III) acetylacetonate and lithium bis(trimethylsilyl)amide was subjected to further process intensification at 200 °C (15 bar), allowing a significant reduction of the catalyst/base loading and a dramatic increase in catalytic efficiency (turnover frequency) by a factor of 1000 compared to traditional protocols. The high-throughput screening additionally identified novel nickel- and copper-based metal/ligand combinations that favored an amination pathway competing with C-H activation, with the addition of ligands, such as 1,10-phenanthroline, having a profound influence on the selectivity. In addition to metal-based catalysts, high-T/p process windows were also successfully applied to transition-metal-free systems, utilizing 1,10-phenanthroline as organocatalyst. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. The enhancement of the deteriorated South African bond options market

    Directory of Open Access Journals (Sweden)

    Coert Frederik Erasmus

    2015-06-01

    Full Text Available nvestments, especially those in the bond market, carry a level of risk. Risks in the bond market can be mitigated by transacting in option contracts. In the developing South African economy, trading activity of over-the-counter (OTC bond options decreased significantly. Possible deteriorating factors and interventions to enhance OTC bond options were investigated in this research. Experts in the OTC bond option market were surveyed and the quantitative data collected was analysed with descriptive statistical methods. Results indicated that three factors were positively identified as deteriorating factors in the OTC bond option market and that five different interventions were possible to possible enhance this market.

  11. Formation, Characterization, and O-O Bond Activation of a Peroxomanganese(III) Complex Supported by a Cross-Clamped Cyclam Ligand.

    Science.gov (United States)

    Colmer, Hannah E; Howcroft, Anthony W; Jackson, Timothy A

    2016-03-07

    Although there have been reports describing the nucleophilic reactivity of peroxomanganese(III) intermediates, as well as their conversion to high-valent oxo-bridged dimers, it remains a challenge to activate peroxomanganese(III) species for conversion to high-valent, mononuclear manganese complexes. Herein, we report the generation, characterization, and activation of a peroxomanganese(III) adduct supported by the cross-clamped, macrocyclic Me2EBC ligand (4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane). This ligand is known to support high-valent, mononuclear Mn(IV) species with well-defined spectroscopic properties, which provides an opportunity to identify mononuclear Mn(IV) products from O-O bond activation of the corresponding Mn(III)-peroxo adduct. The peroxomanganese(III) intermediate, [Mn(III)(O2)(Me2EBC)](+), was prepared at low-temperature by the addition of KO2 to [Mn(II)(Cl)2(Me2EBC)] in CH2Cl2, and this complex was characterized by electronic absorption, electron paramagnetic resonance (EPR), and Mn K-edge X-ray absorption (XAS) spectroscopies. The electronic structure of the [Mn(III)(O2)(Me2EBC)](+) intermediate was examined by density functional theory (DFT) and time-dependent (TD) DFT calculations. Detailed spectroscopic investigations of the decay products of [Mn(III)(O2)(Me2EBC)](+) revealed the presence of mononuclear Mn(III)-hydroxo species or a mixture of mononuclear Mn(IV) and Mn(III)-hydroxo species. The nature of the observed decay products depended on the amount of KO2 used to generate [Mn(III)(O2)(Me2EBC)](+). The Mn(III)-hydroxo product was characterized by Mn K-edge XAS, and shifts in the pre-edge transition energies and intensities relative to [Mn(III)(O2)(Me2EBC)](+) provide a marker for differences in covalency between peroxo and nonperoxo ligands. To the best of our knowledge, this work represents the first observation of a mononuclear Mn(IV) center upon decay of a nonporphyrinoid Mn(III)-peroxo center.

  12. 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...

  13. Expanding career options

    OpenAIRE

    Smilde, Rineke

    2009-01-01

    The musical landscape in Europe shows a complex picture. Societal change leads to change in the careers of artists. We see an increasing number of unstable jobs in the music profession. It no longer offers many opportunities for full-time, long-term contract work, but is often more project-based, calling on musicians to contribute on a sporadic basis or for specific activities. Many graduates employ themselves as freelance artists. Rarely employed in one job for life, the musician is increasi...

  14. Active groups for oxidative activation of C-H bond in C{sub 2}-C{sub 5} paraffins on V-P-O catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zazhigalov, V.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

    1998-12-31

    For the first time in scientific literature, in our joint work with Dr. G. Ladwig in 1978 it was established phase portraite of the oxide vanadium-phosphorus system within wide range of P/V ratios from 0.5 to 3.2. Some later those data were confirmed. By investigation of the properties of individual vanadium-phosphorus phases it was also shown that the active component of such catalysts in n-butane oxidation was vanadyl pyrophosphate phase (VO){sub 2}Pr{sub 2}O{sub 7}. From then the conclusion has been evidenced by numerous publications and at present it has been out of doubt practically all over the world. It was hypothized that the unique properties of (VO){sub 2}P{sub 2}O{sub 7} in the reaction of n-butane oxidation could be explained by the presence of paired vanadyl groups and nearness of the distances between neighbouring vanadyl pairs and that between the first and fourth carbon atoms in n-butane molecule. The molecule activation occured at the latter atoms by proton abstraction. A comparison of the results on n-butane and butenes oxidation over vanadyl pyrophosphate allowed to conclude that the paraffin oxidation did not take place due to the molecule dehydrogenation process at the first stage of its conversion. Up to now, more than 100 papers related to paraffins oxidation over vanadyl pyrophosphate and the physico-chemical properties of the catalyst have been published. The process of n-butane oxidation is realized in practice. But still, the question about the nature of active sites of the catalyst and the reaction mechanism remains open and provokes further investigations. The present paper deals with our opinion about the problem and the experimental results supporting it. (orig.)

  15. Structures, bonding and reactivity of iron and manganese high ...

    Indian Academy of Sciences (India)

    attributed to the intricate metal–oxygen bonding. By thoroughly probing the bonding in all these species, their reactivity towards common chemical reactions such as C–H activation and oxygen atom transfer are discussed. Keywords. Electronic structures and bonding; DFT calculations; high-valent iron and manganese; oxo- ...

  16. Intermolecular Dehydrative Coupling Reaction of Arylketones with Cyclic Alkenes Catalyzed by a Well-Defined Cationic Ruthenium-Hydride Complex: A Novel Ketone Olefination Method via Vinyl C–H Bond Activation

    Science.gov (United States)

    Yi, Chae S.; Lee, Do W.

    2010-01-01

    Summary The cationic ruthenium-hydride complex [(η6-C6H6)(PCy3)(CO)RuH]+BF4− was found to be a highly effective catalyst for the intermolecular olefination reaction of arylketones with cycloalkenes. The preliminary mechanistic analysis revealed that electrophilic ruthenium-vinyl complex is the key species for mediating both vinyl C–H bond activation and the dehydrative olefination steps of the coupling reaction. PMID:20567607

  17. The Application Effect of Learning Model Acquisition Concept Combined with Cooperative Learning STAD to the Learning Achievement, activeness, and Students Responses In Learning Chemistry Bond

    Directory of Open Access Journals (Sweden)

    Putri Ridha Ilahi

    2014-06-01

    Full Text Available Pengaruh Penerapan Model Pembelajaran Pemerolehan Konsep Dipadu Pembelajaran Kooperatif STAD terhadap Prestasi Belajar, Keaktifan, dan Respon Siswa pada Pembelajaran Ikatan Kimia Abstract: This study aims to determine differences: (1 student achievement acquisition make use of the concept of combined learning model STAD cooperative learning and student achievement using model concepts in conventional learning acquisition; (2 active students use learning model acquisition combined the concept of cooperative learning and student activity STAD learning model acquisition using the concept in the conventional learning; (3 The students 'response to the acquisition of the concept of combined learning STAD cooperative learning and students' response to the acquisition of learning concepts in conventional learning. This research uses descriptive research design and quasi-experimental design (quasy experiment design. Learning achievement data were collected using an objective test and reliability coefficient calculated by using SPSS 16 for windows Data recorded in the learning activity of students using observation sheet. Student response data to the learning model was obtained by questionnaire. Data were analyzed statistically and descriptive. The results showed: (1 student achievement using learning model acquisition combined the concept of cooperative learning STAD higher compared to student achievement using model concepts in conventional learning acquisition; (2 active students use learning model acquisition combined the concept of cooperative learning STAD higher than students' active learning model acquisition using the concept in the conventional learning; (3 The students 'response to learning acquisition combined the concept of cooperative learning STAD is more positive than the students' response to the acquisition of learning concepts in conventional learning. Key Words: acquisition of concepts, STAD, chemical bonds   Abstrak: Penelitian ini

  18. Shape Bonding method

    Science.gov (United States)

    Pontius, James T. (Inventor)

    2010-01-01

    The present invention is directed to a method of bonding at least two surfaces together. The methods step of the present invention include applying a strip of adhesive to a first surface along a predefined outer boundary of a bond area and thereby defining a remaining open area there within. A second surface, or gusset plate, is affixed onto the adhesive before the adhesive cures. The strip of adhesive is allowed to cure and then a second amount of adhesive is applied to cover the remaining open area and substantially fill a void between said first and second surfaces about said bond area. A stencil may be used to precisely apply the strip of adhesive. When the strip cures, it acts as a dam to prevent overflow of the subsequent application of adhesive to undesired areas. The method results in a precise bond area free of undesired shapes and of a preferred profile which eliminate the drawbacks of the prior art bonds.

  19. 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...

  20. 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...... 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...... bonds. The purpose is further to analyse the tax consequences of issuing bonds in both a direct issue of bonds and through securitization....

  1. Hydrogen Bonds and Life in the Universe.

    Science.gov (United States)

    Vladilo, Giovanni; Hassanali, Ali

    2018-01-03

    The scientific community is allocating more and more resources to space missions and astronomical observations dedicated to the search for life beyond Earth. This experimental endeavor needs to be backed by a theoretical framework aimed at defining universal criteria for the existence of life. With this aim in mind, we have explored which chemical and physical properties should be expected for life possibly different from the terrestrial one, but similarly sustained by genetic and catalytic molecules. We show that functional molecules performing genetic and catalytic tasks must feature a hierarchy of chemical interactions operating in distinct energy bands. Of all known chemical bonds and forces, only hydrogen bonds are able to mediate the directional interactions of lower energy that are needed for the operation of genetic and catalytic tasks. For this reason and because of the unique quantum properties of hydrogen bonding, the functional molecules involved in life processes are predicted to have extensive hydrogen-bonding capabilities. A molecular medium generating a hydrogen-bond network is probably essential to support the activity of the functional molecules. These hydrogen-bond requirements constrain the viability of hypothetical biochemistries alternative to the terrestrial one, provide thermal limits to life molecular processes, and offer a conceptual framework to define a transition from a "covalent-bond stage" to a "hydrogen-bond stage" in prebiotic chemistry.

  2. Hydrogen Bonds and Life in the Universe

    Science.gov (United States)

    2018-01-01

    The scientific community is allocating more and more resources to space missions and astronomical observations dedicated to the search for life beyond Earth. This experimental endeavor needs to be backed by a theoretical framework aimed at defining universal criteria for the existence of life. With this aim in mind, we have explored which chemical and physical properties should be expected for life possibly different from the terrestrial one, but similarly sustained by genetic and catalytic molecules. We show that functional molecules performing genetic and catalytic tasks must feature a hierarchy of chemical interactions operating in distinct energy bands. Of all known chemical bonds and forces, only hydrogen bonds are able to mediate the directional interactions of lower energy that are needed for the operation of genetic and catalytic tasks. For this reason and because of the unique quantum properties of hydrogen bonding, the functional molecules involved in life processes are predicted to have extensive hydrogen-bonding capabilities. A molecular medium generating a hydrogen-bond network is probably essential to support the activity of the functional molecules. These hydrogen-bond requirements constrain the viability of hypothetical biochemistries alternative to the terrestrial one, provide thermal limits to life molecular processes, and offer a conceptual framework to define a transition from a “covalent-bond stage” to a “hydrogen-bond stage” in prebiotic chemistry. PMID:29301382

  3. Activation of wood surfaces for glue bonds by mechanical pre-treatment and its effects on some properties of veneer surfaces and plywood panels

    Science.gov (United States)

    Aydin, İsmail

    2004-06-01

    Some chemical pre-treatments with chemical reagents are widely applied to wood surfaces in order to improve bonding ability, wettability and reactivate wood surfaces for glue-wood bonds. Besides these chemical treatments, some mechanical pre-treatments such as sanding and planing can be applied to get a fresh surface which eliminates bonding problems and improves glue bonding of wood. In this study, 2 mm thick rotary cut veneers obtained from steamed beech ( Fagus orientalis) logs were used as material. Both air-drying and oven-drying methods were used for drying veneer. After drying, the surfaces of some veneers were sanded with 100 and 180 grit sandpapers. Three-layer-plywood panels were produced from sanded and non-sanded veneers by using urea formaldehyde and phenol formaldehyde glue resins to evaluate the effects of sanding some mechanical properties of plywood. Changes in pH, surface roughness and adhesive wettability of veneers were evaluated. Wettability of veneers was assessed with contact angle measurements according to the sessile drop method. Both veneer and plywood properties investigated in this study improved clearly after the sanding process. Shear and bending strength values of plywood panels manufactured from sanded and non-sanded veneers were vary depending on glue types and veneer drying methods.

  4. Effects of tributylborane-activated adhesive and two silane agents on bonding computer-aided design and manufacturing (CAD/CAM) resin composite.

    Science.gov (United States)

    Shinohara, Ayano; Taira, Yohsuke; Sawase, Takashi

    2017-10-01

    The present study was conducted to evaluate the effects of an experimental adhesive agent [methyl methacrylate-tributylborane liquid (MT)] and two adhesive agents containing silane on the bonding between a resin composite block of a computer-aided design and manufacturing (CAD/CAM) system and a light-curing resin composite veneering material. The surfaces of CAD/CAM resin composite specimens were ground with silicon-carbide paper, treated with phosphoric acid, and then primed with either one of the two silane agents [Scotchbond Universal Adhesive (SC) and GC Ceramic Primer II (GC)], no adhesive control (Cont), or one of three combinations (MT/SC, MT/GC, and MT/Cont). A light-curing resin composite was veneered on the primed CAD/CAM resin composite surface. The veneered specimens were subjected to thermocycling between 4 and 60 °C for 10,000 cycles, and the shear bond strengths were determined. All data were analyzed using analysis of variance and a post hoc Tukey-Kramer HSD test (α = 0.05, n = 8). MT/SC (38.7 MPa) exhibited the highest mean bond strengths, followed by MT/GC (30.4 MPa), SC (27.9 MPa), and MT/Cont (25.7 MPa), while Cont (12.9 MPa) and GC (12.3 MPa) resulted in the lowest bond strengths. The use of MT in conjunction with a silane agent significantly improved the bond strength. Surface treatment with appropriate adhesive agents was confirmed as a prerequisite for veneering CAD/CAM resin composite restorations.

  5. Effect of EDTA with various surface active agents on the bond strength of an epoxy resin-based sealer to dentin: ex vivo

    Directory of Open Access Journals (Sweden)

    Mehmet Burak Güneşer

    2017-09-01

    Full Text Available Objective: The aim of this in vitro study was to evaluate the effect of addition of various surface-modifying agents to EDTA solution on the bond strength of an epoxy-based sealer to the root canal dentin. Materials and Method: Sixty single-rooted human mandibular premolars were decoronated and instrumented using rotary system. The specimens were then randomly divided into four groups (n=15 according to irrigation with different EDTA solution (Wizard, Rehber Kimya, Istanbul, Turkey combinations as follows: Group 1: 17% EDTA + 0.1% benzalkonium chloride; Group 2: 17% EDTA + 0.1% Tween 80; Group 3: 17% EDTA + 0.1% Triton X-100 and control group: 17% EDTA without any surface-modifying agents. Surface tensions of the EDTA solutions were controlled with a tensiometer. Final irrigation was with 5 mL of 5% sodium hypochlorite (Wizard for 1 min, followed by 5 mL of the mentioned EDTA solution for another minute. Roots were obturated with gutta-percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany using cold lateral compaction technique. Horizontal root sections were obtained, and push-out test was used to measure the bond strength between the root canal dentin and sealer. Data were analyzed using the two-way analysis of variance and post hoc Tukey tests (p<0.05. Results: The bond strength of sealer in groups irrigated with EDTA in combination with surface modifying agents did not differ from that of the control (p=0.106. The coronal and middle third in all groups exhibited significantly greater bond strength values when compared with the apical third (p=0.004 and p=0.002, respectively. There was no statistical significant difference between the coronal and the middle thirds (p=0.979. Conclusion: The addition of surface modifying agents to EDTA solution did not affect the bond strength of the epoxy resin–based sealer.

  6. Expanding the Interaction Equivalency Theorem

    Directory of Open Access Journals (Sweden)

    Brenda Cecilia Padilla Rodriguez

    2015-06-01

    Full Text Available Although interaction is recognised as a key element for learning, its incorporation in online courses can be challenging. The interaction equivalency theorem provides guidelines: Meaningful learning can be supported as long as one of three types of interactions (learner-content, learner-teacher and learner-learner is present at a high level. This study sought to apply this theorem to the corporate sector, and to expand it to include other indicators of course effectiveness: satisfaction, knowledge transfer, business results and return on expectations. A large Mexican organisation participated in this research, with 146 learners, 30 teachers and 3 academic assistants. Three versions of an online course were designed, each emphasising a different type of interaction. Data were collected through surveys, exams, observations, activity logs, think aloud protocols and sales records. All course versions yielded high levels of effectiveness, in terms of satisfaction, learning and return on expectations. Yet, course design did not dictate the types of interactions in which students engaged within the courses. Findings suggest that the interaction equivalency theorem can be reformulated as follows: In corporate settings, an online course can be effective in terms of satisfaction, learning, knowledge transfer, business results and return on expectations, as long as (a at least one of three types of interaction (learner-content, learner-teacher or learner-learner features prominently in the design of the course, and (b course delivery is consistent with the chosen type of interaction. Focusing on only one type of interaction carries a high risk of confusion, disengagement or missed learning opportunities, which can be managed by incorporating other forms of interactions.

  7. 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...... non-linear fracture mechanics. The results indicated a good correlation between theory and tests. Furthermore, the model is suggested as theoretical base for determining load capacity of bonded anchorages with transverse pressure, in externally reinforced concrete structures....

  8. Green and social bonds - A promising tool

    International Nuclear Information System (INIS)

    Blanc, Dominique; Barochez, Aurelie de; Cozic, Aela

    2013-11-01

    Issues of green bonds, socially responsible bonds and climate bonds are on the rise. Novethic estimates that some Euro 5 billion in such bonds has been issued since the start of 2013 by development banks, the main issuers of this type of debt. The figure is equal to over half of their total issues since 2007. Including local authorities, corporations and banks, a total Euro 8 billion of these bonds has been issued thus far in 2013. Given the size of the bond market, which the OECD estimated at Euro 95,000 billion in 2011, green and social bonds are still something of a niche but have strong growth potential. A number of large issues, from Euro 500 million to Euro 1 billion, were announced at the end of the year. Unlike conventional bonds, green and social bonds are not intended to finance all the activities of the issuer or refinance its debt. They serve instead to finance specific projects, such as producing renewable energy or adapting to climate change, the risk of which is shouldered by the issuer. This makes them an innovative instrument, used to earmark investments in projects with a direct environmental or social benefit rather than simply on the basis of the issuer's sustainable development policy. With financing being sought for the ecological transition, green and social bonds are promising instruments, sketching out at global level the shape of tools adapted to the financing of a green economy. On the strength of these advantages, the interest of responsible investors - the main target of green and social bond issuers - is growing fast. Judging by issuer press releases and the most commonly used currencies, the main subscribers today are US investors, among them CalSTRS and fund managers like Calvert Investment Management and Trillium Asset Management. European asset owners are also starting to focus on green and social bonds. A Novethic survey shows that 13% of them have already subscribed to such an issue or plan to do so. The present study

  9. Synthesis, characterization and molecular modelling of a novel dipyridamole supramolecule - X-ray structure, quantum mechanics and molecular dynamics study to comprehend the hydrogen bond structure-activity relationship

    Science.gov (United States)

    Vepuri, Suresh B.; Devarajegowda, H. C.; Soliman, Mahmoud E.

    2016-02-01

    Hydrochloride salt formation for Active Pharmaceutical Ingredients (APIs) is the primary choice to impart aqueous solubility and to promote dissolution. Dipyridamole (DIP) is a cardiovascular drug which is practically insoluble in water. We discovered a new form of DIP called as dipyridamole hydrochloride trihydrate (DIPHT), which was prepared by an unusual method of reacting the DIP with hydrated hydrochloric acid (HCl) that was liberated in situ by the reaction of ferric chloride with water. The liberated HCl was consumed as reagent in situ by the scavenger (API) and was converted to a hydrochloride trihydrate. The product was characterized by FTIR, mass spectroscopy, PXRD and DSC. Supramolecular structure of this novel DIPHT was revealed by single crystal XRD. A sustained intramolecular hydrogen bond alliance was found in DIP and the DIPHT. Stability of this hydrogen bond was further evaluated by means of molecular modelling studies. We performed electron calculations using quantum mechanics (QM) on both the base and salt structures to compare their geometry and molecular orbital energy levels. Molecular Dynamics (MD) simulations were also conducted in explicit solvent models to provide more insights into the hydrogen bond strength and conformational preferences of the base and salt structure. Together with QM and MD, we were able to explain the influence of hydrogen bonds on proton uptake activity of DIP and stability of DIP and DIPHT. DIPHT which can dissolve faster than DIP in water may enhance the dissolution and bioavailability of the drug. As the current drug development research is shifting to repurpose the existing drugs in order to subside the untoward risks in new drug development, we believe that DIPHT with its intrinsic aqueous solubility could bring more application for DIP and generate interest within the pharmaceutical industry.

  10. Quality of Affectional Bonding, Learned Helplessness, and Clinical Depression.

    Science.gov (United States)

    Kessler, Ronald P.

    John Bowlby's theory of affectional bonding and the reformulated learned helplessness theory of depression were integrated into a multivariate model in order to expand the breadth of current attributional theories of depression. This retrospective study focused upon the quality of parent-child relations, the types of discipline parents employed,…

  11. Distance Protection of Cross-Bonded Transmission Cable-Systems

    DEFF Research Database (Denmark)

    Bak, Claus Leth; F. Jensen, Christian

    2014-01-01

    In this paper the problems of protecting a cross-bonded cable system using distance protection are analysed. The combination of the desire to expand the high voltage transmission grid and the public's opinion towards new installations of overhead lines (OHL), more and more transmission cable syst...

  12. Neural mechanisms of mother-infant bonding and pair bonding: Similarities, differences, and broader implications

    Science.gov (United States)

    Numan, Michael; Young, Larry J.

    2015-01-01

    Mother-infant bonding is a characteristic of virtually all mammals. The maternal neural system may have provided the scaffold upon which other types of social bonds in mammals have been built. For example, most mammals exhibit a polygamous mating system, but monogamy and pair bonding between mating partners occurs in ∼5% of mammalian species. In mammals, it is plausible that the neural mechanisms that promote mother-infant bonding have been modified by natural selection to establish the capacity to develop a selective bond with a mate during the evolution of monogamous mating strategies. Here we compare the details of the neural mechanisms that promote mother-infant bonding in rats and other mammals with those that underpin pair bond formation in the monogamous prairie vole. Although details remain to be resolved, remarkable similarities and a few differences between the mechanisms underlying these two types of bond formation are revealed. For example, amygdala and nucleus accumbens-ventral pallidum (NA-VP) circuits are involved in both types of bond formation, and dopamine and oxytocin action within NA appears to promote the synaptic plasticity that allows either infant or mating partner stimuli to persistently activate NA-VP attraction circuits, leading to an enduring social attraction and bonding. Further, although the medial preoptic area is essential for maternal behavior, its role in pair bonding remains to be determined. Our review concludes by examining the broader implications of this comparative analysis, and evidence is provided that the maternal care system may have also provided the basic neural foundation for other types of strong social relationships, beyond pair bonding, in mammals, including humans. PMID:26062432

  13. Chemisorption bonding and catalysis

    International Nuclear Information System (INIS)

    Danese, J.B.; Schrieffer, J.R.

    1976-01-01

    The general features of the LCAO--MO, Green's function, and multiple-scattering chi α methods and their applications to surfaces and surface-related problems are discussed. Emphasis is placed on the localization of bonding in surface complexes

  14. Tile-bonding tool

    Science.gov (United States)

    Haynie, C. C.; Holt, J. W.

    1978-01-01

    Device applies uniform, constant, precise pressure to hold tiles in place during bonding. Tool consists of pressure bladders supported by adjustable pole. Pole can accomodate single or multiple bladders. Tiles can be flat or contoured.

  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. Heterometallic Pd(II)-Ni(II) complexes with meso-substituted dibenzotetraaza[14]annulene: double C-H bond activation and formation of a rectangular tetradibenzotetraaza[14]annulene.

    Science.gov (United States)

    Khaledi, Hamid; Olmstead, Marilyn M; Fukuda, Takamitsu; Ali, Hapipah Mohd

    2014-11-03

    Three isomeric 2[Pd(II)-Ni(II)] metal complexes, derived from indoleninyl meso-substituted dibenzotetraaza[14]annulene, were synthesized. The resulting dimers feature Ni···Ni or, alternatively, Ni···π interactions in staggered or slipped cofacial structures. A remarkable insertion of palladium into two different C-H bonds yielded a 4[Pd(II)-Ni(II)] rectangular complex with dimensions of 8.73 × 10.38 Å.

  17. Effects of irradiation on mechanical properties of HIP-bonded reduced-activation ferritic/martensitic steel F82H first wall

    International Nuclear Information System (INIS)

    Kazuyuki, Furuya; Eiichi, Wakai; Kenji, Miyamoto; Masato, Akiba; Masayoshi, Sugimoto

    2007-01-01

    HIP-bonded regions in the first wall of a fusion blanket are subjected to intense neutron irradiation. The purpose of this study is to investigate the influence of radiation damage on the tensile properties of the HIP-bonded regions. Tensile tests have been performed on specimens taken from a HIP-bonded mock-up structure, made to simulate the different fabrication processes. The neutron irradiation was carried out at about 423 K and 523 K to doses up to about 2 dpa. The tensile tests were performed at room temperature, irradiation temperatures and at 623 K. The main results are as follows: (1) Before irradiation, the tensile properties in the HIP-interface were equivalent to those of the matrix region. (2) Rupture did not occur at the HIP-interface of irradiated material. (3) The tensile properties in irradiated material were not notably affected due to manufacturing/fabricating histories. (4) Changes in properties produced by irradiation at 423 K show significant recovery for a test temperature of 673 K

  18. 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.

  19. 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

  20. The Measurement of the Relationship between Taiwan’s Bond Funds’ Net Flow and the Investment Risk -Threshold Autoregressive Model

    OpenAIRE

    Wo-Chiang Lee; Joe-Ming Lee

    2014-01-01

    This article applies the threshold autoregressive model to investigate the relationship between bond funds’ net flow and investment risk in Taiwan. Our empirical findings show that bond funds’ investors are concerned about the investment return and neglect the investment risk. In particular, when expanding the size of the bond funds, fund investors believe that the fund cannot lose any money on investment products. In order to satisfy investors, bond fund managers only target short-term retur...

  1. Expanding Technological Frames Towards Mediated Collaboration

    DEFF Research Database (Denmark)

    Bjørn, Pernille; Scupola, Ada; Fitzgerald, Brian

    2006-01-01

    This paper provides an in-depth analysis of technological and social factors leading to the successful adoption of groupware in a virtual team in educational setting. Drawing on a theoretical framework based on the concept of technological frames, we conducted an action research study to analyze...... the chronological sequence of events leading to groupware adoption. We argue that groupware adoption can be conceptualized as a three-step process of expanding and aligning individual technological frames towards groupware: The first step comprises activities facilitating participants in articulation and evaluation...... collaborative practice and use of technology, and that this activity cannot take place at the outset....

  2. Flow boiling in expanding microchannels

    CERN Document Server

    Alam, Tamanna

    2017-01-01

    This Brief presents an up to date summary of details of the flow boiling heat transfer, pressure drop and instability characteristics; two phase flow patterns of expanding microchannels. Results obtained from the different expanding microscale geometries are presented for comparison and addition to that, comparison with literatures is also performed. Finally, parametric studies are performed and presented in the brief. The findings from this study could help in understanding the complex microscale flow boiling behavior and aid in the design and implementation of reliable compact heat sinks for practical applications.

  3. Expanded Definition of the Oxidation State

    Science.gov (United States)

    Loock, Hans-Peter

    2011-01-01

    A proposal to define the oxidation state of an atom in a compound as the hypothetical charge of the corresponding atomic ion that is obtained by heterolytically cleaving its bonds such that the atom with the higher electronegativity in a bond is allocated all electrons in the bond. Bonds between like atoms are cleaved homolytically. This…

  4. Selective activation of C-F and C-H bonds with iron complexes, the relevant mechanism study by DFT calculations and study on the chemical properties of hydrido iron complex.

    Science.gov (United States)

    Xu, Xiaofeng; Jia, Jiong; Sun, Hongjian; Liu, Yuxia; Xu, Wengang; Shi, Yujie; Zhang, Dongju; Li, Xiaoyan

    2013-03-14

    The reactions of (2,6-difluorophenyl)phenylmethanone (2,6-F(2)C(6)H(3)-C(=O)-C(6)H(5)) (1) and (2,6-difluorophenyl)phenylmethanimine (2,6-F(2)C(6)H(3)-C(=NH)-C(6)H(5)) (3) with Fe(PMe(3))(4) afforded different selective C-F/C-H bond activation products. The reaction of 1 with Fe(PMe(3))(4) gave rise to bis-chelate iron(II) complex [C(6)H(5)-C(=O)-3-FC(6)H(3))Fe(PMe(3))](2) (2) via C-F bond activation. The reaction of 3 with Fe(PMe(3))(4) delivered chelate hydrido iron(II) complex 2,6-F(2)C(6)H(3)-C(=NH)-C(6)H(4))Fe(H)(PMe(3))(3) (4) through C-H bond activation. The DFT calculations show the detailed elementary steps of the mechanism of formation of hydrido complex 4 and indicate 4 is the kinetically preferred product. Complex 4 reacted with HCl, CH(3)Br and CH(3)I delivered the chelate iron halides (2,6-F(2)C(6)H(3)-C(=NH)-C(6)H(4))Fe(PMe(3))(3)X (X = Cl (5); Br (6); I (7)). A ligand (PMe(3)) replacement by CO of 4 was observed giving (2,6-F(2)C(6)H(3)-C(=NH)-C(6)H(4))Fe(H)(CO)(PMe(3))(2) (8). The chelate ligand exchange occurred through the reaction of 4 with salicylaldehydes. The reaction of 4 with Me(3)SiC[triple bond, length as m-dash]CH afforded (2,6-F(2)C(6)H(3)-C([double bond, length as m-dash]N)-C(6)H(5))Fe(C≡C-SiMe(3))(PMe(3))(3) (11). A reaction mechanism from 4 to 11 was discussed with the support of IR monitoring. The molecular structures of complexes 2, 4, 6, 7, 10 and 11 were determined by X-ray diffraction.

  5. Expanding nail or expanding femur? An adverse event with the expandable intramedullary nail.

    Science.gov (United States)

    Gangopadhyay, Soham; Riley, Nicholas D; Sivaji, Chellappan K

    2010-01-01

    The expandable intramedullary nail is self-locking and has the advantage of reducing operating time and exposure to ionizing radiation. The nail is recommended for simple diaphyseal fractures involving the middle third of long bones, where the nail can bypass the fracture site by at least 5 cm. We encountered a unique complication with the expandable nail in a simple transverse shaft fracture at the junction of the middle and distal third of the left femur in an otherwise healthy 57-year-old man. The fracture was reduced and a 12-mm expandable nail was inserted. Following full expansion, intraoperative radiographs were obtained prior to closure. After six postoperative weeks, it was noted that the nail expanded the femoral canal, converting a simple fracture to a distally progressing comminuted fracture with a butterfly fragment. A review of the intraoperative radiographs showed slight widening of the medullary canal at the level of the fracture. As the alignment was satisfactory and callus was present, no further surgical intervention was considered. The patient was advised not to bear weight and was provided with a locked knee brace in extension to wear for six weeks. Radiographs at 12 weeks demonstrated good progress of healing with adequate callus and the patient was permitted to bear weight as tolerated and commence knee flexion. The fracture united satisfactorily at four months. This adverse experience emphasizes that caution should be exercised when expanding the nail, with close observation of the medullary canal diameter during the later stages of expansion.

  6. Expanding the eukaryotic genetic code

    Energy Technology Data Exchange (ETDEWEB)

    Chin, Jason W.; Cropp, T. Ashton; Anderson, J. Christopher; Schultz, Peter G.

    2017-02-28

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  7. Expanding the eukaryotic genetic code

    Science.gov (United States)

    Chin, Jason W.; Cropp, T. Ashton; Anderson, J. Christopher; Schultz, Peter G.

    2013-01-22

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  8. Quintuple super bonding between the superatoms of metallic clusters.

    Science.gov (United States)

    Wang, Haiyan; Cheng, Longjiu

    2017-09-14

    The synthesis of a stable compound with Cr-Cr quintuple bonding (σ, 2π, 2δ) opened the door to a new field of chemistry (T. Nguyen, A. D. Sutton, M. Brynda, J. C. Fettinger, G. J. Long and P. P. Power, Science, 2005, 310, 844). Looking back to the mass experiments on sodium clusters (W. D. Knight, K. Clemenger, W. A. de Heer, W. A. Saunders, M. Y. Chou and M. L. Cohen, Phys. Rev. Lett., 1984, 52, 2141), this work tells some new stories about the experimentally viewed magic numbers 26e and 30e. By unbiased global search, the 26e Li 20 Mg 3 cluster has a perfect double-icosahedral motif with a large HOMO-LUMO energy gap (1.44 eV). We theoretically found that each icosahedron is an independent superatom and molecule-like electronic shell-closure is achieved via quintuple super bonding between two superatoms: [8e](1D2S) 5 -(1D2S) 5 [8e]. Similar quintuple bonding also exists in the 30e double-icosahedral Li 18 Mg 3 Al 2 cluster: [8e](1D2S) 7 -(1D2S) 7 [8e]. The 26e/30e quintuple bonding was verified by the beautiful analogies in molecular orbital diagrams and chemical bonding patterns with V 2 /Re 2 molecules. Such a quintuple super bonding makes a bridge between the jellium model and chemical bonding, which further expands the community of chemical bonds.

  9. Fundamentals of fiber bonding in thermally point-bonded nonwovens

    Science.gov (United States)

    Chidambaram, Aparna

    Thermal point bonding (TPB) uses heat and pressure to bond a web of fibers at discrete points imparting strength to the manufactured fabric. This process significantly reduces the strength and elongation of the bridging fibers between bond points while strengthening the web. Single fiber experiments were performed with four structurally different polypropylene fibers to analyze the inter-relationships between fiber structure, fiber properties and bonding process. Two fiber types had a low birefringence sheath or surface layer while the remaining had uniform birefringence profiles through their thickness. Bonds were formed between isolated pairs of fibers by subjecting the fibers to a calendering process and simulating TPB process conditions. The dependence of bond strength on bonding temperature and on the type of fiber used was evaluated. Fiber strengths before and after bonding were measured and compared to understand the effect of bonding on fiber strength. Additionally, bonded fiber strength was compared to the strength of single fibers which had experienced the same process conditions as the bonded pairs. This comparison estimated the effect of mechanical damage from pressing fibers together with steel rolls while creating bonds in TPB. Interfiber bond strength increased with bonding temperature for all fiber types. Fiber strength decreased with increasing bonding temperature for all fiber types except for one type of low birefringent sheath fibers. Fiber strength degradation was unavoidable at temperatures required for successful bonding. Mechanical damage from compression of fibers between rolls was an insignificant factor in this strength loss. Thermal damage during bonding was the sole significant contributor to fiber strength degradation. Fibers with low birefringence skins formed strong bonds with minimal fiber strength loss and were superior to fibers without such surface layers in TPB performance. A simple model to predict the behavior of a two-bond

  10. 46 CFR Sec. 10 - Bonds.

    Science.gov (United States)

    2010-10-01

    ... open penalty type. (e) No repair voucher (progress or final) where bond coverage is required shall be... awarded work and the furnishing of the performance and payment bonds required by Article 14 of the NSA...) shall be used. (b) In compliance with the perform- ance bond and payment bond requirements of Article 14...

  11. Looking at hydrogen bonds in cellulose.

    Science.gov (United States)

    Nishiyama, Yoshiharu; Langan, Paul; Wada, Masahisa; Forsyth, V Trevor

    2010-11-01

    A series of cellulose crystal allomorphs has been studied using high-resolution X-ray and neutron fibre diffraction to locate the positions of H atoms involved in hydrogen bonding. One type of position was always clearly observed in the Fourier difference map (F(d)-F(h)), while the positions of other H atoms appeared to be less well established. Despite the high crystallinity of the chosen samples, neutron diffraction data favoured some hydrogen-bonding disorder in native cellulose. The presence of disorder and a comparison of hydrogen-bond geometries in different allomorphs suggests that although hydrogen bonding may not be the most important factor in the stabilization of cellulose I, it is essential for stabilizing cellulose III, which is the activated form, and preventing it from collapsing back to the more stable cellulose I.

  12. Inert C-H Bond Transformations Enabled by Organometallic Manganese Catalysis.

    Science.gov (United States)

    Hu, Yuanyuan; Zhou, Bingwei; Wang, Congyang

    2018-03-20

    (with or w/o bases) and acids, we disclosed a "dual activation" mode for performing manganese-catalyzed C-H bond transformations, that is, merging C-H activation by manganese catalysts and C-X multiple bond activation by Lewis acids. Consequently, the scope of C-H substrates could be expanded to include challenging ketones and olefinic C-H compounds. Additionally, the range of reaction partners could be significantly broadened to include those bearing more polarized C═O, C═N, and C≡N bonds such as aldehydes, imines, and nitriles. Remarkably, the innate reactivity of different C-H bonds in ketones could be reversed by manganese catalysis, and the reactions could even be carried out at room temperature. Our findings provide guiding information for the future development of manganese-catalyzed C-H activation reactions and beyond. Related important contributions from other groups are mentioned, and the remaining challenges and future perspective in this emerging area are also presented.

  13. DFT modelling of a diphosphane - N-heterocyclic carbene-Rh(i) pincer complex rearrangement: a computational evaluation of the electronic effects in C-P bond activation.

    Science.gov (United States)

    Qin, H-L; Leng, J; Zhang, W; Kantchev, E A B

    2018-02-20

    DFT calculations confirmed that the rearrangement of a PCP-Rh-H pincer to a CCP-Rh-phosphane pincer occured by C-P oxidative addition (ΔG ‡ = 29.5 kcal mol -1 , rate-determining step), followed by P-H reductive elimination (ΔG ‡ = 4.8 kcal mol -1 ). The oxidative addition proceeded via a 3-centered transition state and is accelerated by electron-withdrawing substituents p- to the reacting C-P bond, resulting in a reaction constant (ρ) of 2.12 for ΔG ‡ and 2.76 for ΔH ‡ in a Hammett-type linear free energy relationship. AIM wavefunction analyses indicated a decrease in the negative charge on the carbon bonded to Rh with a concomitant increase in the positive charge on the latter. The electronic density at the Rh-P bond critical point and the atomic charge on Rh correlate well with the Hammett constants (σ) of the p-substituents. The replacement of the Rh-bound hydride with other anions (CH 3 , Ph, t-Bu, OH, F, Cl, and CN) results in a decrease in the OA barrier only for CH 3 , which is in accordance with the experimental results. The reductive elimination occurs via a 3-centered (Rh, H, P) transition state, which adopts a conformation wherein the steric clash between the i-Pr groups is minimized, followed by recomplexation of Rh and the newly formed (i-Pr) 2 PH by a conformational twist around the Rh-P axis.

  14. 26 CFR 1.147(b)-1 - Bond maturity limitation-treatment of working capital.

    Science.gov (United States)

    2010-04-01

    ... and Local Bonds § 1.147(b)-1 Bond maturity limitation-treatment of working capital. Section 147(b) does not apply to proceeds of a private activity bond issue used to finance working capital... 26 Internal Revenue 2 2010-04-01 2010-04-01 false Bond maturity limitation-treatment of working...

  15. Hydrogen-Bond Accepting Properties of New Heteroaromatic Ring Chemical Motifs: A Theoretical Study.

    Science.gov (United States)

    Graton, Jérôme; Le Questel, Jean-Yves; Maxwell, Peter; Popelier, Paul

    2016-02-22

    The prediction of hydrogen-bond (H-bond) acceptor ability is crucial in drug design. This important property is quantified in a large pKBHX database of consistently measured values. We aim to expand the chemical diversity of the studied H-bond acceptors and to increase the range of H-bond strength considered. Two quantum chemical descriptors are contrasted, called ΔE(H) (the change in the energy of a topological hydrogen atom upon complexation) and Vmin (the local minimum in the electrostatic potential on the H-bond accepting site). We performed a systematic analysis of the correlations between pKBHX and Vmin for an initial set of 106 compounds (including O- and N-containing subsets, as well as compounds including sulfur, chlorine, and π-bases). Correlations improve for family dependent subsets, and after outlier treatment, a set of 90 compounds was used to set up a linear equation to predict pKBHX from Vmin. This equation and a previously published equation [Green and Popelier J. Chem. Inf. 2014, 54 (2), 553-561], to predict pKBHX from ΔE(H), were used to predict the pKBHX values for 22 potentially biologically active heteroaromatic ring compounds, [Pitt et al. J. Med. Chem. 2009, 52 (9), 2952-2963], among which several structures still remain experimentally unavailable. H-Bond basicity of sp(2) nitrogen sites were consistently predicted with both descriptors. A worse agreement was found with carbonyl acceptor sites, with the stronger deviations observed for the lactam groups. It was shown that secondary interactions involving the neighboring NH group were influencing the results. Substitution of the NH group with an NMe group resulted in an improved consistency from both Vmin and ΔE(H) predictions, the latter being more prominently affected by the methyl substitution. Both approaches appear as efficient procedures for the H-bond ability prediction of novel heteroaromatic rings. Nevertheless, the ΔE(H) parameter presents slight chemical structure limitations

  16. New Architectures in Hydrogen Bond Catalysis

    Science.gov (United States)

    Rodriguez, Andrew A.; Yoo, Hoseong; Ziller, Joseph W.; Shea, Kenneth J.

    2009-01-01

    New achiral sulfamide, phosphoric triamide, and thiophosphoric triamide compounds have been synthesized. Their activity as hydrogen bond catalysts for the Friedel-Crafts and Baylis-Hillman reactions compares favorably with that of a known and active thiourea catalyst. The new compounds were also studied by X-ray crystallography and their solid state structures are described. PMID:20160884

  17. Expanding the Game Design Space

    DEFF Research Database (Denmark)

    Larsen, Lasse Juel; Majgaard, Gunver

    2016-01-01

    This article considers game design research in educational settings. Its focus is on how undergraduate students – particularly engineering students – learn computer game design. From observations conducted during our game design courses we have developed a model of expanded game design space....... It encapsulates the entire development process from the first ideas to the final game with emphasis on game design thinking. Our model of expanded game design space consists of four separate – yet interconnected – layers in the process of game development. The first layer addresses the importance of framing......, providing a clear game design assignment that involves the formulation of intended player experience and a description of game mechanics. The second layer focuses on game design thinking from six different aspects of game design chosen in relation to the framing of the game design assignment. The third...

  18. Helical screw expander evaluation project

    Science.gov (United States)

    McKay, R.

    1982-03-01

    A one MW helical rotary screw expander power system for electric power generation from geothermal brine was evaluated. The technology explored in the testing is simple, potentially very efficient, and ideally suited to wellhead installations in moderate to high enthalpy, liquid dominated field. A functional one MW geothermal electric power plant that featured a helical screw expander was produced and then tested with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing, operation on two-phase geothermal fluids. The Project also produced a computer equipped data system, an instrumentation and control van, and a 1000 kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

  19. Seal-less cryogenic expander

    International Nuclear Information System (INIS)

    Faria, L.E.; Christopher, E.H.

    1987-01-01

    In an expander for use in a split Stirling cycle refrigeration system of the type wherein a displacer moves with reciprocating motion inside an expander housing, and wherein a plunger force and a regenerator force are formed on the displacer, the plunger force cyclically varying and having a time of minimum and maximum plunger force amplitude, and the regenerator force cyclically varying and having a time of minimum and maximum regenerator force amplitude, the improvement is described comprising: (a) means for maintaining displacer forces, such that the maximum plunger force amplitude is substantially equal to the maximum regenerator force amplitude; and (b) means for adjusting a time difference, the time difference being the time between the time of maximum plunger force and the time of maximum regenerator force such that a measure of the cooling power of the refrigeration system is maximized

  20. 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

  1. Cytotoxicity of dentin bonding agents.

    Science.gov (United States)

    Cal, Ebru; Guneri, Pelin; Atay, Ayse; Cetintas, Vildan Bozok

    2014-01-01

    This study sought to evaluate the cytotoxicity of 5 dentin bonding agents (Admira Bond, Adper Single Bond Plus, Clearfil SE Bond, Clearfil S3 Bond, and Heliobond) by XTT assay using human gingival fibroblast cells. Samples of dentin bonding agents were prepared on a black 96-well microplate, and the cytotoxicity of each bonding material was measured every 24 hours for 7 days, then on Days 14, 21, and 28. One-way ANOVA and Bonferroni post hoc tests were used for statistical analyses. All 5 materials were evaluated as severely cytotoxic (P agents showed severe cytotoxicity with viability results exception of Adper Single Bond Plus, toxicity continued to Day 28 for all compounds. The utmost care must be considered during the clinical utilization of dentin bonding agents to keep them within the area of restoration and prevent their contact with adjacent tissues.

  2. Photochemical tissue bonding

    Science.gov (United States)

    Redmond, Robert W [Brookline, MA; Kochevar, Irene E [Charlestown, MA

    2012-01-10

    Photochemical tissue bonding methods include the application of a photosensitizer to a tissue and/or tissue graft, followed by irradiation with electromagnetic energy to produce a tissue seal. The methods are useful for tissue adhesion, such as in wound closure, tissue grafting, skin grafting, musculoskeletal tissue repair, ligament or tendon repair and corneal repair.

  3. Neutron diffraction reveals hydrogen bonds critical for cGMP-selective activation: insights for cGMP-dependent protein kinase agonist design.

    Science.gov (United States)

    Huang, Gilbert Y; Gerlits, Oksana O; Blakeley, Matthew P; Sankaran, Banumathi; Kovalevsky, Andrey Y; Kim, Choel

    2014-11-04

    High selectivity of cyclic-nucleotide binding (CNB) domains for cAMP and cGMP are required for segregating signaling pathways; however, the mechanism of selectivity remains unclear. To investigate the mechanism of high selectivity in cGMP-dependent protein kinase (PKG), we determined a room-temperature joint X-ray/neutron (XN) structure of PKG Iβ CNB-B, a domain 200-fold selective for cGMP over cAMP, bound to cGMP (2.2 Å), and a low-temperature X-ray structure of CNB-B with cAMP (1.3 Å). The XN structure directly describes the hydrogen bonding interactions that modulate high selectivity for cGMP, while the structure with cAMP reveals that all these contacts are disrupted, explaining its low affinity for cAMP.

  4. Expanding Business With Effective Networking

    OpenAIRE

    Lehto, Tanja

    2012-01-01

    The aim of the thesis process was to investigate networking, personal selling and Russian markets in order to create a clear view of what is vital for effective networking in Russia. The objective of the study was to observe the case company´s readiness for expanding operations to Russia as well as analyzing the company´s existing values and how they could be developed further. Additionally the purpose of the thesis was to give recommendations of the factors needed to be developed and suggest...

  5. 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.

  6. Environmental assessment, expanded Ponnequin wind energy project, Weld County, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-02-01

    The US Department of Energy (DOE) has considered a proposal from the State of Colorado, Office of Energy Conservation (OEC), for funding construction of the Expanded Ponnequin Wind Project in Weld County, Colorado. OEC plans to enter into a contracting arrangement with Public Service Company of Colorado (PSCo) for the completion of these activities. PSCo, along with its subcontractors and business partners, are jointly developing the Expanded Ponnequin Wind Project. The purpose of this Final Environmental Assessment (EA) is to provide DOE and the public with information on potential environmental impacts associated with the Expanded Ponnequin Wind Energy Project. This EA, and public comments received on it, were used in DOE`s deliberations on whether to release funding for the expanded project under the Commercialization Ventures Program.

  7. Environmental assessment, expanded Ponnequin wind energy project, Weld County, Colorado

    International Nuclear Information System (INIS)

    1999-02-01

    The US Department of Energy (DOE) has considered a proposal from the State of Colorado, Office of Energy Conservation (OEC), for funding construction of the Expanded Ponnequin Wind Project in Weld County, Colorado. OEC plans to enter into a contracting arrangement with Public Service Company of Colorado (PSCo) for the completion of these activities. PSCo, along with its subcontractors and business partners, are jointly developing the Expanded Ponnequin Wind Project. The purpose of this Final Environmental Assessment (EA) is to provide DOE and the public with information on potential environmental impacts associated with the Expanded Ponnequin Wind Energy Project. This EA, and public comments received on it, were used in DOE's deliberations on whether to release funding for the expanded project under the Commercialization Ventures Program

  8. 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.

  9. Safe and Liquid Mortgage Bonds

    DEFF Research Database (Denmark)

    Dick-Nielsen, Jens; Gyntelberg, Jacob; Lund, Jesper

    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...

  10. Development of a surrogate potency assay to determine the angiogenic activity of Stempeucel®, a pooled, ex-vivo expanded, allogeneic human bone marrow mesenchymal stromal cell product.

    Science.gov (United States)

    Thej, Charan; Ramadasse, Balamurugan; Walvekar, Ankita; Majumdar, Anish S; Balasubramanian, Sudha

    2017-02-28

    Mesenchymal stromal cells (MSCs) have emerged as a more beneficial alternative to conventional therapy and may offer a potential cure for unmet medical needs. MSCs are known to possess strong immunomodulatory and anti-inflammatory properties. Moreover, they promote angiogenesis and tissue regeneration through the secretion of trophic factors. For these reasons, the past decade witnessed a sharp increase in the number of clinical trials conducted with stem cells for various vascular diseases requiring angiogenesis. In this study, we evaluated the in vitro angiogenic potency of Stempeucel®, which is an allogeneic pooled human bone marrow-derived mesenchymal stromal cell (phBMMSC) product. We previously established the safety of Stempeucel® in our pre-clinical studies, and clinical trials conducted for critical limb ischaemia and acute myocardial infarction. Because the proposed mechanism of action of phBMMSCs is mainly through the secretion of pro-angiogenic cytokines, we developed a surrogate potency assay by screening various batches of large-scale expanded phBMMSCs for the expression of angiogenic factors and cytokines through gene expression and growth factor analyses, followed by in vitro functional assays. The well characterized angiogenic vascular endothelial growth factor (VEGF) was selected and quantified in twenty six manufactured batches of phBMMSCs to establish consistency following the United States Food and Drug Administration recommendations. According to recommendations 21 CFR 211.165(e) and 211.194(a)(2), we also established and documented the specificity and reproducibility of the test methods employed through validation. Moreover, we also attempted to elucidate the mechanism of action of the cell population to ensure appropriate biological activity. The functional role of VEGF has been established through in vitro angiogenic assays and a dose-dependent correlation was observed with in vitro functional results. The data generated from this study

  11. 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.

  12. An assessment of bonding characteristics of a newly introduced bonding agent: "beauty ortho bond"

    Directory of Open Access Journals (Sweden)

    Padmashree Veeramachineni

    2010-01-01

    Conclusion: Although Transbond XT had higher bond strength, the BOB and FOLC showed clinically acceptable bond strengths. However, clean-up after debonding would be easier with the two latter materials.

  13. Fundamental reactivity of the Metal-Carbon bond in cyclometalated PNC-complexes

    NARCIS (Netherlands)

    Jongbloed, L.S.

    2016-01-01

    The activation of C-H bonds by transition metals and the reactivity of the corresponding metal-carbon bond are interesting research topics form different point of views. Catalytic C-H bond functionalization has emerged as a highly active research area for the development of green construction of

  14. Leak detection with expandable coatings

    Science.gov (United States)

    1971-01-01

    Developed and evaluated is a system for leak detection that can be easily applied over separable connectors and that expands into a bubble or balloon if a leak is present. This objective is accomplished by using thin films of Parafilm tape wrapped over connectors, which are then overcoated with a special formulation. The low yield strength and the high elongation of the envelope permit bubble formation if leakage occurs. This system is appropriate for welds and other hardware besides separable connectors. The practical limit of this system appears to be for leaks exceeding 0.000001 cc/sec. If this envelope is used to trap gases for mass spectrometer inspection, leaks in the range of ten to the minus 8th power cc/sec. may be detectable.

  15. OCT Expanded Clinical Data Analysis

    Science.gov (United States)

    Van Baalen, Mary; Tafreshi, Ali; Patel, Nimesh; Young, Millennia; Mason, Sara; Otto, Christian; Samuels, Brian; Koslovsky, Matthew; Schaefer, Caroline; Taiym, Wafa; hide

    2017-01-01

    Vision changes identified in long duration space fliers has led to a more comprehensive clinical monitoring protocol. Optical Coherence Tomography (OCT) was recently implemented on board the International Space Station in 2013. NASA is collaborating with Heidelberg Engineering to expand our current OCT data analysis capability by implementing a volumetric approach. Volumetric maps will be created by combining the circle scan, the disc block scan, and the radial scan. This assessment may provide additional information about the optic nerve and further characterize changes related microgravity exposure. We will discuss challenges with collection and analysis of OCT data, present the results of this reanalysis and outline the potential benefits and limitations of the additional data.

  16. Preventive Ethics Through Expanding Education.

    Science.gov (United States)

    Ho, Anita; MacDonald, Lisa Mei-Hwa; Unger, David

    2016-03-01

    Healthcare institutions have been making increasing efforts to standardize consultation methodology and to accredit both bioethics training programs and the consultants accordingly. The focus has traditionally been on the ethics consultation as the relevant unit of ethics intervention. Outcome measures are studied in relation to consultations, and the hidden assumption is that consultations are the preferred or best way to address day-to-day ethical dilemmas. Reflecting on the data from an internal quality improvement survey and the literature, we argue that having general ethics education as a key function of ethics services may be more important in meeting the contemporaneous needs of acute care settings. An expanded and varied ethics education, with attention to the time constraints of healthcare workers' schedules, was a key recommendation brought forward by survey respondents. Promoting ethical reflection and creating a culture of ethics may serve to prevent ethical dilemmas or mitigate their effects.

  17. Structures, bonding and reactivity of iron and manganese high ...

    Indian Academy of Sciences (India)

    Direct structural comparison to iron and manganese-oxo species are made and the observed similarity and differences among them are attributed to the intricate metal–oxygen bonding. By thoroughly probing the bonding in all these species, their reactivity towards common chemical reactions such as C–H activation and ...

  18. 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...... opportunities consist of a risky reference fund, a risk-free asset and a structured bond. Key model elements are the trading strategy and utility function of the investor. Our numerical results indicate structured bonds do have basis for consideration in the optimal portfolio. The product holdings...

  19. Photochemical tissue bonding with chitosan adhesive films

    Directory of Open Access Journals (Sweden)

    Piller Sabine C

    2010-09-01

    Full Text Available Abstract Background Photochemical tissue bonding (PTB is a promising sutureless technique for tissue repair. PTB is often achieved by applying a solution of rose bengal (RB between two tissue edges, which are irradiated by a green laser to crosslink collagen fibers with minimal heat production. In this study, RB has been incorporated in chitosan films to create a novel tissue adhesive that is laser-activated. Methods Adhesive films, based on chitosan and containing ~0.1 wt% RB were manufactured and bonded to calf intestine by a solid state laser (λ = 532 nm, Fluence~110 J/cm2, spot size~0.5 cm. A single-column tensiometer, interfaced with a personal computer, tested the bonding strength. K-type thermocouples recorded the temperature (T at the adhesive-tissue interface during laser irradiation. Human fibroblasts were also seeded on the adhesive and cultured for 48 hours to assess cell growth. Results The RB-chitosan adhesive bonded firmly to the intestine with adhesion strength of 15 ± 2 kPa, (n = 31. The adhesion strength dropped to 0.5 ± 0.1 (n = 8 kPa when the laser was not applied to the adhesive. The average temperature of the adhesive increased from 26°C to 32°C during laser exposure. Fibroblasts grew confluent on the adhesive without morphological changes. Conclusion A new biocompatible chitosan adhesive has been developed that bonds photochemically to tissue with minimal temperature increase.

  20. 76 FR 8761 - Privacy Act of 1974; U.S. Immigration and Customs Enforcement, DHS/ICE-004 Bond Management...

    Science.gov (United States)

    2011-02-15

    ... 1974; U.S. Immigration and Customs Enforcement, DHS/ICE-004 Bond Management Information System (BMIS... Bond Management Information System (74 FR 57891, Dec. 21, 2009) expand the categories of records... Information System (BMIS). Security classification: Unclassified. System location: Records are maintained at U...

  1. 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...

  2. N-H bond activation by palladium(ii) and copper(i) complexes featuring a reactive bidentate PN-ligand

    NARCIS (Netherlands)

    de Boer, S.Y.; Gloaguen, Y.; Reek, J.N.H.; Lutz, M.; van der Vlugt, J.I.

    2012-01-01

    The first examples of reactivity at the backbone of a bidentate PN-ligand L1H relevant to N-H activation are described, leading to novel PdII and CuI amido complexes. Activation of the PN-ligand backbone led to selective dearomatization of the pyridyl ring structure. In the case of PdII, the

  3. Functional coupling of Cys-226 and Cys-296 in the glucagon-like peptide-1 (GLP-1) receptor indicates a disulfide bond that is close to the activation pocket.

    Science.gov (United States)

    Mann, Rosalind J; Al-Sabah, Suleiman; de Maturana, Rakel López; Sinfield, John K; Donnelly, Dan

    2010-12-01

    G protein-coupled receptors (GPCRs) are seven transmembrane α-helical (7TM) integral membrane proteins that play a central role in both cell signaling and in the action of many pharmaceuticals. The crystal structures of several Family A GPCRs have shown the presence of a disulfide bond linking transmembrane helix 3 (TM3) to the second extracellular loop (ECL2), enabling ECL2 to stabilize and contribute to the ligand binding pocket. Family B GPCRs share no significant sequence identity with those in Family A but nevertheless share two conserved cysteines in topologically equivalent positions. Since there are no available crystal structures for the 7TM domain of any Family B GPCR, we used mutagenesis alongside pharmacological analysis to investigate the role of ECL2 and the conserved cysteine residues. We mutated Cys-226, at the extracellular end of TM3 of the glucagon-like peptide-1 (GLP-1) receptor, to alanine and observed a 38-fold reduction in GLP-1 potency. Interestingly, this potency loss was restored by the additional substitution of Cys-296 in ECL2 to alanine. Alongside the complete conservation of these cysteine residues in Family B GPCRs, this functional coupling suggested the presence of a disulfide bond. Further mutagenesis demonstrated that the low potency observed at the C226A mutant, compared with the C226A-C296A double mutant, was the result of the bulky nature of the released Cys-296 side chain. Since this suggested that ECL2 was in close proximity to the agonist activation pocket, an alanine scan of ECL2 was carried out which confirmed the important role of this loop in agonist-induced receptor activation. Copyright © 2010 Elsevier Inc. All rights reserved.

  4. Expanding forensic science through forensic intelligence.

    Science.gov (United States)

    Ribaux, Olivier; Talbot Wright, Benjamin

    2014-12-01

    Research and Development ('R&D') in forensic science currently focuses on innovative technologies improving the efficiency of existing forensic processes, from the detection of marks and traces at the scene, to their presentation in Court. R&D approached from this perspective provides no response to doubts raised by recent criminological studies, which question the effective contribution of forensic science to crime reduction, and to policing in general. Traces (i.e. forensic case data), as remnants of criminal activity are collected and used in various forms of crime monitoring and investigation. The aforementioned doubts therefore need to be addressed by expressing how information is conveyed by traces in these processes. Modelling from this standpoint expands the scope of forensic science and provides new R&D opportunities. Twelve propositions for R&D are stated in order to pave the way. Copyright © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

  5. Extremozymes: expanding the limits of biocatalysis.

    Science.gov (United States)

    Adams, M W; Perler, F B; Kelly, R M

    1995-07-01

    The study of enzymes isolated from organisms inhabiting unconventional ecosystems has led to the realization that biocatalysis need not be constrained to mild conditions and can be considered at pH's, temperatures, pressures, ionic and solvent environments long thought to be destructive to biomolecules. Parallel to this, it has been demonstrated that even conventional enzymes will catalyze reactions in solvents other than water. However, the intrinsic basis for biological function under extreme conditions is only starting to be addressed, as are associated applications. This was the focus of a recent NSF/NIST-sponsored workshop on extremozymes. Given the information acquired from the study of extremozymes, modification of enzymes to improve their ranges of stability and activity remains a possibility. Ultimately, by expanding the range of conditions suitable for enzyme function, new opportunities to use biocatalysis will be created.

  6. Multiconfiguration Pair-Density Functional Theory and Complete Active Space Second Order Perturbation Theory. Bond Dissociation Energies of FeC, NiC, FeS, NiS, FeSe, and NiSe.

    Science.gov (United States)

    Sharkas, Kamal; Gagliardi, Laura; Truhlar, Donald G

    2017-12-07

    We investigate the performance of multiconfiguration pair-density functional theory (MC-PDFT) and complete active space second-order perturbation theory for computing the bond dissociation energies of the diatomic molecules FeC, NiC, FeS, NiS, FeSe, and NiSe, for which accurate experimental data have become recently available [Matthew, D. J.; Tieu, E.; Morse, M. D. J. Chem. Phys. 2017, 146, 144310-144320]. We use three correlated participating orbital (CPO) schemes (nominal, moderate, and extended) to define the active spaces, and we consider both the complete active space (CAS) and the separated-pair (SP) schemes to specify the configurations included for a given active space. We found that the moderate SP-PDFT scheme with the tPBE on-top density functional has the smallest mean unsigned error (MUE) of the methods considered. This level of theory provides a balanced treatment of the static and dynamic correlation energies for the studied systems. This is encouraging because the method is low in cost even for much more complicated systems.

  7. Hydrogen bonding, solvent exchange, and coupled proton and electron transfer in the oxidation and reduction of redox-active tyrosine Y(Z) in Mn-depleted core complexes of photosystem II.

    Science.gov (United States)

    Diner, B A; Force, D A; Randall, D W; Britt, R D

    1998-12-22

    The redox-active tyrosines, Y(Z) and Y(D), of Photosystem II are oxidized by P680+ to the neutral tyrosyl radical. This oxidation thus involves the transfer of the phenolic proton as well as an electron. It has recently been proposed that tyrosine Y(Z) might replace the lost proton by abstraction of a hydrogen atom or a proton from a water molecule bound to the manganese cluster, thereby increasing the driving force for water oxidation. To compare and contrast with the intact system, we examine here, in a simplified Mn-depleted PSII core complex, isolated from a site-directed mutant of Synechocystis PCC 6803 lacking Y(D), the role of proton transfer in the oxidation and reduction of Y(Z). We show how the oxidation and reduction rates for Y(Z), the deuterium isotope effect on these rates, and the Y(Z)* - Y(Z) difference spectra all depend on pH (from 5.5 to 9.5). This simplified system allows examination of electron-transfer processes over a broader range of pH than is possible with the intact system and with more tractable rates. The kinetic isotope effect for the oxidation of P680+ by Y(Z) is maximal at pH 7.0 (3.64). It decreases to lower pH as charge recombination, which shows no deuterium isotope, starts to become competitive with Y(Z) oxidation. To higher pH, Y(Z) becomes increasingly deprotonated to form the tyrosinate, the oxidation of which at pH 9.5 becomes extremely rapid (1260 ms(-1)) and no longer limited by proton transfer. These observations point to a mechanism for the oxidation of Y(Z) in which the tyrosinate is the species from which the electron occurs even at lower pH. The kinetics of oxidation of Y(Z) show elements of rate limitation by both proton and electron transfer, with the former dominating at low pH and the latter at high pH. The proton-transfer limitation of Y(Z) oxidation at low pH is best explained by a gated mechanism in which Y(Z) and the acceptor of the phenolic proton need to form an electron/proton-transfer competent complex in

  8. Graphene for Expandable Space Structures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Graphene's tightly bonded impermeable single atomic layer of carbon offers unrivalled potential for lightweight flexible gas barrier applications. Graphene has been...

  9. Development of Self-Expanding Idealflo (tm) Sandcontrol Technology

    Energy Technology Data Exchange (ETDEWEB)

    Jeff A. Spray

    2007-09-30

    Development of Self-Expanding Idealflo{trademark} Sandscreen Technology was a successfully executed design-by-analysis through field demonstration project. This final report is presented as a two-part progression of concept development and manufacturing activities. The first part, conceptual development activities, discusses novel specifications creation and non-linear analytical design generation. The second part, manufacturing, contains achievement related information for detailed-design, fabrication, mechanical testing, and field demonstration activities.

  10. The human-animal bond in veterinary medical education: accessing web-based information.

    Science.gov (United States)

    Hart, Lynette A; Wood, Mary W

    2008-01-01

    Various aspects of the field known as the human-animal bond (HAB), or human-animal interactions, have expanded within veterinary medical education over the past quarter of a century. Using a variety of databases and informed search strategies, relevant information can be accessed, including recent articles, databases, journals, academic centers, societies and associations, programs, and key references. In this paper, methods for accessing resources supporting veterinary education on the HAB are organized into four subject areas: the HAB in veterinary school curricula; social work and support services for veterinary clients; the benefits of the HAB for human well-being, with applications of animal-assisted therapies, activities, and education; and companion animal behavior and welfare concerns. A related Web site can be accessed at http://www.vetmed.ucdavis.edu/CCAB/humananimalinteractions.html.

  11. Attitudes toward expanding nurses' authority.

    Science.gov (United States)

    Kerzman, Hana; Van Dijk, Dina; Eizenberg, Limor; Khaikin, Rut; Phridman, Shoshi; Siman-Tov, Maya; Goldberg, Shoshi

    2015-01-01

    In recent years, an increasing number of care procedures previously under the physician's authority have been placed in the hands of registered nurses. The purpose of this study was to examine the attitudes of nurses towards expanding nurses' authority and the relationships between these attitudes and job satisfaction facets, professional characteristics, and demographics. A cross-sectional study was conducted between 2010 and 2011 in three major medical centers in Israel. Participants included 833 nurses working in 89 departments. Attitudes toward the expansion of nurses' authority were assessed by self-report questionnaire, as well as job satisfaction facets including perception of professional autonomy, nurse-physician working relations, workload and burnout, perceptions of quality of care, and nursing staff satisfaction at work. Nurses reported positive attitudes toward the expansion of nurses' authority and moderate attitudes for interpretation of diagnostic tests in selected situations. The results of multivariate regression analyses demonstrate that the nurses' satisfaction from professional autonomy and work relations were the most influential factors in explaining their attitudes toward the expansion of nurses' authority. In addition, professionally young nurses tend to be more positive regarding changes in nurses' authority. In the Israeli reality of a nurse's shortage, we are witnessing professional transitions toward expansion of the scope of nurses' accountability and decision-making authority. The current research contributes to our understanding of attitudes toward the expansion of nurses' authority among the nursing staffs. The findings indicate the necessity of redefining the scope of nursing practice within the current professional context.

  12. Solder extrusion pressure bonding process and bonded products produced thereby

    Science.gov (United States)

    Beavis, Leonard C.; Karnowsky, Maurice M.; Yost, Frederick G.

    1992-01-01

    Production of soldered joints which are highly reliable and capable of surviving 10,000 thermal cycles between about -40.degree. C. and 110.degree. C. Process involves interposing a thin layer of a metal solder composition between the metal surfaces of members to be bonded and applying heat and up to about 1000 psi compression pressure to the superposed members, in the presence of a reducing atmosphere, to extrude the major amount of the solder composition, contaminants including fluxing gases and air, from between the members being bonded, to form a very thin, strong intermetallic bonding layer having a thermal expansion tolerant with that of the bonded members.

  13. A heparin-bonded vascular graft generates no systemic effect on markers of hemostasis activation or detectable heparin-induced thrombocytopeniaassociated antibodies in humans

    NARCIS (Netherlands)

    Heyligers, Jan M. M.; Lisman, Ton; Verhagen, Hence J. M.; Weeterings, Cees; de Groot, Philip G.; Moll, Frans L.

    Objectives. Almost a third of patients who undergo peripheral bypass procedures do not have suitable veins, making the use of prosthetic materials necessary. Prosthetic materials can cause platelet adhesion and activation of the coagulation cascade on the graft. One potential strategy to reduce this

  14. Better Bonded Ethernet Load Balancing

    Energy Technology Data Exchange (ETDEWEB)

    Gabler, Jason

    2006-09-29

    When a High Performance Storage System's mover shuttles large amounts of data to storage over a single Ethernet device that single channel can rapidly become saturated. Using Linux Ethernet channel bonding to address this and similar situations was not, until now, a viable solution. The various modes in which channel bonding could be configured always offered some benefit but only under strict conditions or at a system resource cost that was greater than the benefit gained by using channel bonding. Newer bonding modes designed by various networking hardware companies, helpful in such networking scenarios, were already present in their own switches. However, Linux-based systems were unable to take advantage of those new modes as they had not yet been implemented in the Linux kernel bonding driver. So, except for basic fault tolerance, Linux channel bonding could not positively combine separate Ethernet devices to provide the necessary bandwidth.

  15. Synchrony and exertion during dance independently raise pain threshold and encourage social bonding.

    Science.gov (United States)

    Tarr, Bronwyn; Launay, Jacques; Cohen, Emma; Dunbar, Robin

    2015-10-01

    Group dancing is a ubiquitous human activity that involves exertive synchronized movement to music. It is hypothesized to play a role in social bonding, potentially via the release of endorphins, which are analgesic and reward-inducing, and have been implicated in primate social bonding. We used a 2 × 2 experimental design to examine effects of exertion and synchrony on bonding. Both demonstrated significant independent positive effects on pain threshold (a proxy for endorphin activation) and in-group bonding. This suggests that dance which involves both exertive and synchronized movement may be an effective group bonding activity. © 2015 The Authors.

  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. Expanding Sex-Role Definitions by Self-Discovery.

    Science.gov (United States)

    Kahn, Sharon E.; Greenberg, Leslie S.

    1980-01-01

    Counselors who stimulate client self-discovery may help these clients experience undeveloped parts of themselves and expand their definitions of themselves and their sex-role possibilities. Stimulation methods actively involve clients in the exploration of sex-role concerns to change restrictive self-concepts. (Author)

  19. Halogen light versus LED for bracket bonding: shear bond strength

    Directory of Open Access Journals (Sweden)

    Paulo Eduardo Guedes Carvalho

    2013-02-01

    Full Text Available INTRODUCTION: LED light-curing devices seek to provide a cold light activator which allows protocols of material polymerization with shorter duration. OBJECTIVE: The present study aimed to evaluate the shear bond strength of bracket bonding using three types of light-curing devices: One with halogen light (Optilight Plus - Gnatus and two with LEDs (Optilight CL - Gnatus and Elipar Freelight - 3M/ESPE. RESULTS: Comparing the results by analysis of variance, the Gnatus LED device showed an inferior statistical behavior in relation to other light sources, when activated by a short time. But, when it was used for 40 seconds, the polymerization results were consistent with the other evaluated sources. The device with the best average performance was the halogen light, followed by the 3M/ESPE LED. CONCLUSION: It was concluded that the LEDs may be indicated in orthodontic practice, as long as a protocol is used for the application of light with the activation time of 40 seconds.INTRODUÇÃO: os aparelhos de fotopolimerização por LED buscam proporcionar uma luz ativadora fria, que possibilite protocolos de polimerização do material com menor tempo de duração. OBJETIVO: avaliar a resistência à tração da colagem de braquetes, utilizando três tipos de aparelhos fotoativadores: um de luz halógena (Optilight Plus - Gnatus e outros dois de LED (Optilight CL - Gnatus; e Elipar Freelight - 3M/Espe. RESULTADOS: comparando os resultados por meio da análise de variância, o aparelho de LED Gnatus apresentou comportamento estatístico inferior em relação às outras fontes de luz, quando ativado por tempo reduzido. Já quando foi utilizado o tempo de 40 segundos, os resultados de polimerização foram compatíveis com as demais fontes avaliadas. O aparelho que apresentou melhor desempenho médio foi o de luz halógena, seguido pelo LED 3M/Espe. CONCLUSÃO: concluiu-se que os LEDs podem ser indicados na prática ortodôntica, uma vez que seja utilizado

  20. A simplified indirect bonding technique

    Directory of Open Access Journals (Sweden)

    Radha Katiyar

    2014-01-01

    Full Text Available With the advent of lingual orthodontics, indirect bonding technique has become an integral part of practice. It involves placement of brackets initially on the models and then their transfer to teeth with the help of transfer trays. Problems encountered with current indirect bonding techniques used are (1 the possibility of adhesive flash remaining around the base of the brackets which requires removal (2 longer time required for the adhesive to gain enough bond strength for secure tray removal. The new simplified indirect bonding technique presented here overcomes both these problems.

  1. Wafer bonding applications and technology

    CERN Document Server

    Gösele, Ulrich

    2004-01-01

    During the past decade direct wafer bonding has developed into a mature materials integration technology. This book presents state-of-the-art reviews of the most important applications of wafer bonding written by experts from industry and academia. The topics include bonding-based fabrication methods of silicon-on-insulator, photonic crystals, VCSELs, SiGe-based FETs, MEMS together with hybrid integration and laser lift-off. The non-specialist will learn about the basics of wafer bonding and its various application areas, while the researcher in the field will find up-to-date information about this fast-moving area, including relevant patent information.

  2. Bonding of Cf/SiC composite to Invar alloy using an active cement, Ag-Cu eutectic and Cu interlayer

    Science.gov (United States)

    Lei, Zhao; Xiaohong, Li; Jinbao, Hou; Qiang, Sun; Fuli, Zhang

    2012-10-01

    The interfacial microstructures and mechanical properties of the joints formed by active cement added brazing in vacuum of Cf/SiC composite to Invar alloy, using Ag-Cu eutectic alloy and pure copper foil as braze alloy and interlayer respectively, were investigated. CuTi, Cu4Ti3, Fe2Ti and the reaction layer of TiC and Si were the predominant components at the joint interface. The maximum shear strength of the joint was 77 MPa for brazing at 850 °C for 15 min. The results show that active cement added brazing in vacuum using Ag-Cu eutectic alloy and Cu interlayer can be used successfully for joining Cf/SiC composites to Invar alloy.

  3. Chemical bonding and quadrupole splittings of 57Fe Moessbauer spectrum in active sites of oxyhemoglobin as calculated by Xα-discrete variation method

    International Nuclear Information System (INIS)

    Yuryeva, E. I.

    2008-01-01

    Results of quantum-chemical X α -discrete variation method (X α -DVM) calculations of interaction parameters between iron (II) and oxygen molecule in active sites of α- and β-subunits of oxyhemoglobin are presented within three models: without extra electron and in spin-unrestricted mode (model I); without extra electron and in spin-restricted mode (model II); with extra electrons in spin-unrestricted mode (model III). The electronic structure and 57 Fe quadrupole splitting ΔE Q for the active site of α- and β-subunits (within model I) and only of the α-subunit (within models II and III) of oxyhemoglobin are calculated. The differences in ΔE Q values for these three models are discussed.

  4. Chemical bonding and quadrupole splittings of {sup 57}Fe Moessbauer spectrum in active sites of oxyhemoglobin as calculated by X{sub {alpha}}-discrete variation method

    Energy Technology Data Exchange (ETDEWEB)

    Yuryeva, E. I., E-mail: yuryeva@ihim.uran.ru [Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences (Russian Federation)

    2008-07-15

    Results of quantum-chemical X{sub {alpha}}-discrete variation method (X{sub {alpha}}-DVM) calculations of interaction parameters between iron (II) and oxygen molecule in active sites of {alpha}- and {beta}-subunits of oxyhemoglobin are presented within three models: without extra electron and in spin-unrestricted mode (model I); without extra electron and in spin-restricted mode (model II); with extra electrons in spin-unrestricted mode (model III). The electronic structure and {sup 57}Fe quadrupole splitting {Delta}E{sub Q} for the active site of {alpha}- and {beta}-subunits (within model I) and only of the {alpha}-subunit (within models II and III) of oxyhemoglobin are calculated. The differences in {Delta}E{sub Q} values for these three models are discussed.

  5. Preferential activation of primary C–H bonds in the reactions of small alkanes with the diatomic MgO+. cation

    Czech Academy of Sciences Publication Activity Database

    Schröder, Detlef; Roithová, J.; Alikhani, E.; Kwapien, K.; Sauer, J.

    2010-01-01

    Roč. 16, č. 13 (2010), s. 4110-4119 ISSN 0947-6539 R&D Projects: GA AV ČR KJB400550704; GA ČR GA203/08/1487 Grant - others: ERC (XE) HORIZOMS AdG226373 Institutional research plan: CEZ:AV0Z40550506 Keywords : alkanes * C-H activation * density functional calculations * magnesium oxide Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.476, year: 2010

  6. Human Bond Communication

    DEFF Research Database (Denmark)

    Prasad, Ramjee

    2016-01-01

    Modern dexterous communication technology is progressively enabling humans to communicate their information through them with speech (aural) and media (optical) as underpinning essence. Humans realize this kind of aural and optical information by their optical and auditory senses. However, due...... to certain constraints, the ability to incorporate the other three sensory features namely, olfactory, gustatory, and tactile are still far from reality. Human bond communication is a novel concept that incorporates olfactory, gustatory, and tactile that will allow more expressive and holistic sensory...... information exchange through communication techniques for more human sentiment centric communication. This concept endorses the need of inclusion of other three senses and proposes an innovative approach of holistic communication for future communication network....

  7. 30 CFR 281.33 - Bonds and bonding requirements.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Bonds and bonding requirements. 281.33 Section 281.33 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR OFFSHORE LEASING OF MINERALS OTHER THAN OIL, GAS, AND SULPHUR IN THE OUTER CONTINENTAL SHELF Financial Considerations § 281.33...

  8. Cysteines introduced into extracellular loops 1 and 4 of human P-glycoprotein that are close only in the open conformation spontaneously form a disulfide bond that inhibits drug efflux and ATPase activity.

    Science.gov (United States)

    Loo, Tip W; Clarke, David M

    2014-09-05

    P-glycoprotein (P-gp) is an ATP-binding cassette drug pump that protects us from toxic compounds and confers multidrug resistance. The protein is organized into two halves. The halves contain a transmembrane domain (TMD) with six transmembrane segments and a nucleotide-binding domain (NBD). The drug- and ATP-binding sites reside at the TMD1/TMD2 and NBD1/NBD2 interfaces, respectively. ATP-dependent drug efflux involves changes between the open inward-facing (NBDs apart, extracellular loops (ECLs) close together) and the closed outward-facing (NBDs close together, ECLs apart) conformations. It is controversial, however, whether the open conformation only exists transiently in intact cells because of the presence of high levels of ATP. To test for the presence of an open conformation in intact cells, reporter cysteines were placed in extracellular loops 1 (A80C, N half) and 4 (R741C, C half). The rationale was that cysteines A80C/R741C would only come close enough to form a disulfide bond in an open conformation (6.9 Å apart) because they are separated widely (30.4 Å apart) in the closed conformation. It was observed that the mutant A80C/R741C cross-linked spontaneously (>90%) when expressed in cells. In contrast to previous reports showing that trapping P-gp in a closed conformation highly activated ATPase activity, here we show that A80C/R741C cross-linking inhibited ATPase activity and drug efflux. Both activities were restored when the cross-linked mutant was treated with a thiol-reducing agent. The results show that an open conformation can be readily detected in cells and that cross-linking of cysteines placed in ECLs 1 and 4 inhibits activity. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  9. Glutamic Acid Selective Chemical Cleavage of Peptide Bonds.

    Science.gov (United States)

    Nalbone, Joseph M; Lahankar, Neelam; Buissereth, Lyssa; Raj, Monika

    2016-03-04

    Site-specific hydrolysis of peptide bonds at glutamic acid under neutral aqueous conditions is reported. The method relies on the activation of the backbone amide chain at glutamic acid by the formation of a pyroglutamyl (pGlu) imide moiety. This activation increases the susceptibility of a peptide bond toward hydrolysis. The method is highly specific and demonstrates broad substrate scope including cleavage of various bioactive peptides with unnatural amino acid residues, which are unsuitable substrates for enzymatic hydrolysis.

  10. C-H and H-H Bond Activation via Ligand Dearomatization/Rearomatization of a PN3P-Rhodium(I) Complex

    KAUST Repository

    Huang, Kuo-Wei

    2015-04-13

    A neutral complex PN3P-Rh(I)Cl (2) was prepared from a reaction of the PN3P pincer ligand (1) with [Rh(COD)Cl]2 (COD = 1,5-cyclooctadiene). Upon treatment with a suitable base, H–H and Csp2–H activation reactions can be achieved through the deprotonation/reprotonation of one of the N–H arms and dearomatization/rearomatization of the central pyridine ring with the oxidation state of Rh remaining I.

  11. Breaking Rules – Making Bonds

    Indian Academy of Sciences (India)

    IAS Admin

    RESONANCE | January 2016. GENERAL | ARTICLE. Breaking Rules – Making Bonds. A G Samuelson. Boron-containing molecules discovered recently have new types of dative bonds between carbenes and borylenes. At the same time, they show that traditional thumb rules regarding acids and bases are no longer valid.

  12. Why are Hydrogen Bonds Directional?

    Indian Academy of Sciences (India)

    Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore,. Karnataka 560 012, India e-mail: ... Lewis succeeded in explaining the 'chemical bonds' that held the neutral molecules together. The covalent bonding has dominated chemistry so much over the last century and most chemists appear ...

  13. 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 ...

  14. Distance criterion for hydrogen bond

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Distance criterion for hydrogen bond. In a D-H ...A contact, the D...A distance must be less than the sum of van der Waals Radii of the D and A atoms, for it to be a hydrogen bond.

  15. Why are Hydrogen Bonds Directional?

    Indian Academy of Sciences (India)

    for an interaction to be characterized as a hydro- gen bond but does not provide any rationale for the same. This article reports a rationale for limiting the angle, based on the electron density topology using the quantum theory of atoms in molecules. Electron density topol- ogy for common hydrogen bond donors HF, HCl, ...

  16. Flexible PVC flame retarded with expandable graphite

    CSIR Research Space (South Africa)

    Focke, WW

    2014-02-01

    Full Text Available The utility of expandable graphite as a flame retardant for PVC, plasticized with 60 phr of a phosphate ester, was investigated. Cone calorimeter results, at a radiant flux of 35 kW m 2, revealed that adding only 5 wt.% expandable graphite lowered...

  17. 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.

  18. Microstructure of plastic bonded nickel electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Kulcsar, S.; Agh, J.; Fazekas, A.; Vigh, J.; Bujdoso, Z.

    1982-07-01

    Structure is of great importance in the characteristics of plastic bonded nickel electrodes. On the basis of SEM tests it has been established that in pressed Ni electrodes some tenth of a millimetre-long PTFE fibres can be found with a diameter smaller than 500 nm. These form a net-like structure in the electrode which holds the active material together without any decrease in the conductivity. The formation and arrangement of this structure can be influenced by technological parameters.

  19. Photochemical tissue bonding with chitosan adhesive films

    OpenAIRE

    Lauto, Antonio; Mawad, Damia; Barton, Matthew; Gupta, Abhishek; Piller, Sabine C; Hook, James

    2010-01-01

    Abstract Background Photochemical tissue bonding (PTB) is a promising sutureless technique for tissue repair. PTB is often achieved by applying a solution of rose bengal (RB) between two tissue edges, which are irradiated by a green laser to crosslink collagen fibers with minimal heat production. In this study, RB has been incorporated in chitosan films to create a novel tissue adhesive that is laser-activated. Methods Adhesive films, based on chitosan and containing ~0.1 wt% RB were manufact...

  20. Short hydrogen bonds in the catalytic mechanism of serine proteases

    Directory of Open Access Journals (Sweden)

    VLADIMIR LESKOVAC

    2008-04-01

    Full Text Available The survey of crystallographic data from the Protein Data Bank for 37 structures of trypsin and other serine proteases at a resolution of 0.78–1.28 Å revealed the presence of hydrogen bonds in the active site of the enzymes, which are formed between the catalytic histidine and aspartate residues and are on average 2.7 Å long. This is the typical bond length for normal hydrogen bonds. The geometric properties of the hydrogen bonds in the active site indicate that the H atom is not centered between the heteroatoms of the catalytic histidine and aspartate residues in the active site. Taken together, these findings exclude the possibility that short “low-barrier” hydrogen bonds are formed in the ground state structure of the active sites examined in this work. Some time ago, it was suggested by Cleland that the “low-barrier hydrogen bond” hypothesis is operative in the catalytic mechanism of serine proteases, and requires the presence of short hydrogen bonds around 2.4 Å long in the active site, with the H atom centered between the catalytic heteroatoms. The conclusions drawn from this work do not exclude the validity of the “low-barrier hydrogen bond” hypothesis at all, but they merely do not support it in this particular case, with this particular class of enzymes.

  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. Madumycin II inhibits peptide bond formation by forcing the peptidyl transferase center into an inactive state

    Energy Technology Data Exchange (ETDEWEB)

    Osterman, Ilya A.; Khabibullina, Nelli F.; Komarova, Ekaterina S.; Kasatsky, Pavel; Kartsev, Victor G.; Bogdanov, Alexey A.; Dontsova, Olga A.; Konevega, Andrey L.; Sergiev, Petr V.; Polikanov, Yury S. (InterBioScreen); (UIC); (MSU-Russia); (Kurchatov)

    2017-05-13

    The emergence of multi-drug resistant bacteria is limiting the effectiveness of commonly used antibiotics, which spurs a renewed interest in revisiting older and poorly studied drugs. Streptogramins A is a class of protein synthesis inhibitors that target the peptidyl transferase center (PTC) on the large subunit of the ribosome. In this work, we have revealed the mode of action of the PTC inhibitor madumycin II, an alanine-containing streptogramin A antibiotic, in the context of a functional 70S ribosome containing tRNA substrates. Madumycin II inhibits the ribosome prior to the first cycle of peptide bond formation. It allows binding of the tRNAs to the ribosomal A and P sites, but prevents correct positioning of their CCA-ends into the PTC thus making peptide bond formation impossible. We also revealed a previously unseen drug-induced rearrangement of nucleotides U2506 and U2585 of the 23S rRNA resulting in the formation of the U2506•G2583 wobble pair that was attributed to a catalytically inactive state of the PTC. The structural and biochemical data reported here expand our knowledge on the fundamental mechanisms by which peptidyl transferase inhibitors modulate the catalytic activity of the ribosome.

  3. Time to Grow: Year Two Report on ExpandED Schools. A TASC Report

    Science.gov (United States)

    Traill, Saskia; Brohawn, Katie

    2014-01-01

    An analysis of data from the second year of The After-School Corporation's (TASC's) national demonstration of an expanded school day for elementary and middle school students shows that ExpandED Schools improved school culture, decreased rates of students' chronic absenteeism and helped students develop positive learning habits and attitudes.…

  4. Compact Radiometers Expand Climate Knowledge

    Science.gov (United States)

    2010-01-01

    To gain a better understanding of Earth's water, energy, and carbon cycles, NASA plans to embark on the Soil Moisture Active and Passive mission in 2015. To prepare, Goddard Space Flight Center provided Small Business Innovation Research (SBIR) funding to ProSensing Inc., of Amherst, Massachusetts, to develop a compact ultrastable radiometer for sea surface salinity and soil moisture mapping. ProSensing incorporated small, low-cost, high-performance elements into just a few circuit boards and now offers two lightweight radiometers commercially. Government research agencies, university research groups, and large corporations around the world are using the devices for mapping soil moisture, ocean salinity, and wind speed.

  5. Parenting stress and parental bonding.

    Science.gov (United States)

    Willinger, Ulrike; Diendorfer-Radner, Gabriela; Willnauer, Ruth; Jörgl, Gudrun; Hager, Veronika

    2005-01-01

    Attachment experiences are thought to be important because of their implications for later development. The authors' aim with the questionnaire-based study was to investigate the differences between recalled parental bonding regarding 4 types of maternal and paternal bonding with respect to experienced parenting stress caused by child characteristics, parent attributes, and life events under the consideration of the child's gender and age. The authors gathered parental bonding behavior data with the German version of the Parental Bonding Instrument (PBI). The authors assessed parenting stress with their German version of the "Parenting Stress Index (PSI)." They found significant differences among 120 mothers grouped in the 4 maternal and the 4 paternal bonding types regarding parenting stress caused by child, maternal bonding: F(5, 113) = 4.13, p = .002, paternal bonding: F(5, 111) = 8.50, p mothers who themselves recalled the "optimal parental bonding type" with respect to the child and parental domain. The authors did not find any significant differences between the 4 maternal, F(5, 113) = 1.25, p = .29, and the 4 paternal, F(5, 111) = 1.87, p = .106, bonding types with respect to the life stress. According to the authors' findings, the representation of attachment relationships seems to have a special impact on the adult's capacity to cope with challenges and stress, either directly or indirectly as an internal working model of attachment. For the clinical practice, these findings seem to recommend the combination of both the PSI and PBI regarding the diagnostic of stressful mother-child system to plan an optimal intervention program.

  6. Expanding community through ARV provision in Thailand.

    Science.gov (United States)

    Lyttleton, C; Beesey, A; Sitthikriengkrai, M

    2007-01-01

    Anti-retrovirals (ARVs) have altered the complexion of HIV/AIDS management in Thailand. In 2005, ARVs were included within a subsidised health scheme making provision widespread. Increased access has been brought about through the legal and political advocacy of the Thai Network for People Living with HIV/AIDS (TNP+) who now play a central role in expanded ARV provision. HIV-infected volunteers help the state deliver comprehensive services and assist with follow-up and adherence programs. Alongside improvements in drug provision, a focus on pharmaceutical treatment has left other issues, such as community support of orphans and the social responses to living with HIV, less central within community responses. As they take on new responsibilities, people living with HIV/AIDS (PLHA) groups move from activities focused on reversing local stigma to constitute a new social movement that is increasingly prominent in Thai civil society. Networks of PLHA confront new social and political challenges as they also seek to broaden access to marginalised groups who remain excluded from these services. Many ethnic minority groups without full Thai citizenship have been denied access to subsidised health services including ARVs. As part of a broadening advocacy profile, the PLHA movement is now engaging in a politics of difference defined not simply by presence or absence of HIV but also by wider issues of national identity and belonging.

  7. Queensland set to expand coal operations

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-03-15

    In addition to new coal mines which came on line in 2006 (as mentioned on pp 8-12 in this issue in the article entitled 'Coal production, exports and new mine developments' a number of advanced coal projects are at various stages of assessment and most are proceeding through the statutory approvals process while others are progressing to and beyond pre-feasibility studies. An overview of several of these projects is given in the article. These are: development of the Clermont open-cut thermal project; expanding open-cut operations at Ensham Central; assessing development of the Glen Wilga and Haystack Road deposits; and development at mines at Goonyella-Riverside, Hail Creek, Monto, Lenton, New Acland, Olive Downs, Peak Downs, Sonoma and Vermont. Coal exploration developments, particularly in the Bowen Basin, are reported, together with work in progress under the AUS $20 m Smart Exploration program. Figures are given for private expenditure on coal exploration, exploration, permits for coal received and active exploration permits for coal for June 1997 to June 2006. The article is part of a review called 'Queensland Mining and Production Industries 2006'. 3 figs., 1 tab.

  8. The expanding universe of prion diseases.

    Directory of Open Access Journals (Sweden)

    Joel C Watts

    2006-03-01

    Full Text Available Prions cause fatal and transmissible neurodegenerative disease. These etiological infectious agents are formed in greater part from a misfolded cell-surface protein called PrP(C. Several mammalian species are affected by the diseases, and in the case of "mad cow disease" (BSE the agent has a tropism for humans, with negative consequences for agribusiness and public health. Unfortunately, the known universe of prion diseases is expanding. At least four novel prion diseases--including human diseases variant Creutzfeldt-Jakob disease (vCJD and sporadic fatal insomnia (sFI, bovine amyloidotic spongiform encephalopathy (BASE, and Nor98 of sheep--have been identified in the last ten years, and chronic wasting disease (CWD of North American deer (Odocoileus Specis and Rocky Mountain elk (Cervus elaphus nelsoni is undergoing a dramatic spread across North America. While amplification (BSE and dissemination (CWD, commercial sourcing of cervids from the wild and movement of farmed elk can be attributed to human activity, the origins of emergent prion diseases cannot always be laid at the door of humankind. Instead, the continued appearance of new outbreaks in the form of "sporadic" disease may be an inevitable outcome in a situation where the replicating pathogen is host-encoded.

  9. The expanding universe of prion diseases.

    Directory of Open Access Journals (Sweden)

    2006-03-01

    Full Text Available Prions cause fatal and transmissible neurodegenerative disease. These etiological infectious agents are formed in greater part from a misfolded cell-surface protein called PrP(C. Several mammalian species are affected by the diseases, and in the case of "mad cow disease" (BSE the agent has a tropism for humans, with negative consequences for agribusiness and public health. Unfortunately, the known universe of prion diseases is expanding. At least four novel prion diseases-including human diseases variant Creutzfeldt-Jakob disease (vCJD and sporadic fatal insomnia (sFI, bovine amyloidotic spongiform encephalopathy (BASE, and Nor98 of sheep-have been identified in the last ten years, and chronic wasting disease (CWD of North American deer (Odocoileus Specis and Rocky Mountain elk (Cervus elaphus nelsoni is undergoing a dramatic spread across North America. While amplification (BSE and dissemination (CWD, commercial sourcing of cervids from the wild and movement of farmed elk can be attributed to human activity, the origins of emergent prion diseases cannot always be laid at the door of humankind. Instead, the continued appearance of new outbreaks in the form of "sporadic" disease may be an inevitable outcome in a situation where the replicating pathogen is host-encoded.

  10. Innovative metal thermo-compression wafer bonding for microelectronics and MEMS devices

    Science.gov (United States)

    Rebhan, B.; Dragoi, V.

    2017-06-01

    With the continuously increasing level of integration for microelectronics and microelectromechanical systems (MEMS) devices, such as gyroscopes, accelerometers and bolometers, metal wafer bonding becomes progressively more importance. In the present work common metal wafer bonding techniques were categorized, described and compared. While devices produced with metal thermo-compression wafer bonding ensure high bonding quality and a high degree of reliability, the required bonding temperatures are very often close to the maximum complementary metal oxide semiconductor (CMOS) compatible process temperature (400-450°C). Based on a thermodynamic model of increasing the Gibbs free energy prior wafer bonding, in-situ ComBond(R) surface activation was applied to enable low-temperature Au-Au, Al-Al and Cu-Cu wafer bonding. Different aspects, such as bonding quality, dicing yield, bond strength, grain growth and elemental analysis across the initial bonding interface, were investigated. Based on these parameters successful wafer bonding was demonstrated at room temperature for Au-Au and Cu-Cu, and at 100°C for Al-Al wafer bonding.

  11. Direct Bonded Pontic (Laporan Kasus

    Directory of Open Access Journals (Sweden)

    Suhandi Sidjaja

    2015-10-01

    Full Text Available Advanced science and technology in dentistry enable dental practitioners to modified she bonding techniques in tooth replacement. A pontic made of composite resin bonded to etched enamel of the adjacent teeth can be used in the replacement of one missing anterior tooth with a virgin or sowed adpicent tooth. The advantages of this technique include a one visit treatment, cow cost, good esthetics, less side effects and easy repair or rebounding. Clinical evaluation showed a high success rate therefore with a proper diagnosis and a perfect skill of the direct bonded technique this treatment can be used as an alternative restoration.

  12. The chemisorptive bond basic concepts

    CERN Document Server

    Clark, Alfred

    1974-01-01

    The Chemisorptive Bond: Basic Concepts describes the basic concepts of the chemisorptive bond on solid surfaces from the simple analogies with ordinary chemical bonds to the quantum-mechanical approaches.This book is composed of 10 chapters and begins with discussions of simple formulas for correlating measurable quantities in chemisorptions and catalysis. The succeeding chapters deal with theories based on quantum-mechanical principles that describe the mutual interactions of atoms of the solid and foreign atoms on the surface. The remaining chapters consider the possible arrangements

  13. 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......-EMU members and stronger for old than new EU members. For EMU countries, the integration is weaker the lower the credit rating is. During the recent crisis periods, the integration is weaker, particularly for EMU countries....

  14. Roll bonding of strained aluminium

    DEFF Research Database (Denmark)

    Staun, Jakob M.

    2003-01-01

    This report investigates roll bonding of pre-strained (å ~ 4) aluminium sheets to produce high strain material from high purity aluminium (99.996%) and commercial pure aluminium (99.6%). The degree of bonding is investigated by optical microscopy and ultrasonic scanning. Under the right...... of the cross rolled volume fraction is found. To further asses this effect, and the anisotropy, it is necessary to acquire knowledge about both texture and microstructure, e.g. by TEM. Roll bonding of pre-strained aluminium is found to be a possible alternative to ARB in the quest for ultra-fine grained...

  15. A-coupled-expanding and distributional chaos

    International Nuclear Information System (INIS)

    Kim, Cholsan; Ju, Hyonhui; Chen, Minghao; Raith, Peter

    2015-01-01

    The concept of A-coupled-expanding maps is one of the more natural and useful ideas generalized from the horseshoe map which is commonly known as a criterion of chaos. It is well known that distributional chaos is one of the concepts which reflect strong chaotic behavior. In this paper, we focus on the relationship between A-coupled-expanding and distributional chaos. We prove two theorems which give sufficient conditions for a strictly A-coupled-expanding map to be distributionally chaotic in the senses of two kinds, where A is an m × m irreducible transition matrix

  16. Accelerator business in Japan expanding

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    Accelerators have become to be used increasingly in Japan in such fields as medicine, physics research and industry. This has caused stiff competition for market share by the manufacturers of accelerators. Electron beam accelerators for industrial use provide an indispensable means for adding values to products, for example, electric cables with incombustible insulators. Linear accelerators for the nondestructive inspection of nuclear components have been widely installed at equipment manufacturing plants. Active efforts have been exerted to develop small synchrotron radiation accelerators for next generation electronic industry. Cyclotrons for producing short life radioisotopes for medical diagnosis and electron beam accelerators for radiation therapy are also used routinely. The suppliers of accelerators include the companies manufacturing heavy electric machinery, heavy machinery and the engineering division of steelmakers. Accelerator physics is being formed, but universities do not yet offer the course regarding accelerators. Accelerator use in Japan and the trend of accelerator manufacturers are reported. (K.I.)

  17. Definition of a multicentral bond index

    International Nuclear Information System (INIS)

    Giambiagi, M.; Giambiagi, M.S. de; Mundim, K.C.

    1989-01-01

    The tensor character of the first-order density matrix leads to the definition of an MO multicentral bond index for closed-shell systems. It is here applied to three-center bonds. Satisfactory results are obtained for compounds involving 'secondary' bonds, strong and normal hydrogen bonds; the index for the peptide bond is found to be similar to that of strong hydrogen bonds. (author) [pt

  18. Can laccases catalyze bond cleavage in lignin?

    DEFF Research Database (Denmark)

    Munk, Line; Sitarz, Anna Katarzyna; Kalyani, Dayanand

    2015-01-01

    Modification of lignin is recognized as an important aspect of the successful refining of lignocellulosic biomass, and enzyme-assisted processing and upcycling of lignin is receiving significant attention in the literature. Laccases (EC 1.103.2) are taking the centerstage of this attention, since...... these enzymes may help degrading lignin, using oxygen as the oxidant. Laccases can catalyze polymerization of lignin, but the question is whether and how laccases can directly catalyze modification of lignin via catalytic bond cleavage. Via a thorough review of the available literature and detailed...... illustrations of the putative laccase catalyzed reactions, including the possible reactions of the reactive radical intermediates taking place after the initial oxidation of the phenol-hydroxyl groups, we show that i) Laccase activity is able to catalyze bond cleavage in low molecular weight phenolic lignin...

  19. Towards a unified description of the hydrogen bond network of liquid water: A dynamics based approach

    International Nuclear Information System (INIS)

    Ozkanlar, Abdullah; Zhou, Tiecheng; Clark, Aurora E.

    2014-01-01

    The definition of a hydrogen bond (H-bond) is intimately related to the topological and dynamic properties of the hydrogen bond network within liquid water. The development of a universal H-bond definition for water is an active area of research as it would remove many ambiguities in the network properties that derive from the fixed definition employed to assign whether a water dimer is hydrogen bonded. This work investigates the impact that an electronic-structure based definition, an energetic, and a geometric definition of the H-bond has upon both topological and dynamic network behavior of simulated water. In each definition, the use of a cutoff (either geometric or energetic) to assign the presence of a H-bond leads to the formation of transiently bonded or broken dimers, which have been quantified within the simulation data. The relative concentration of transient species, and their duration, results in two of the three definitions sharing similarities in either topological or dynamic features (H-bond distribution, H-bond lifetime, etc.), however no two definitions exhibit similar behavior for both classes of network properties. In fact, two networks with similar local network topology (as indicated by similar average H-bonds) can have dramatically different global network topology (as indicated by the defect state distributions) and altered H-bond lifetimes. A dynamics based correction scheme is then used to remove artificially transient H-bonds and to repair artificially broken bonds within the network such that the corrected network exhibits the same structural and dynamic properties for two H-bond definitions (the properties of the third definition being significantly improved). The algorithm described represents a significant step forward in the development of a unified hydrogen bond network whose properties are independent of the original hydrogen bond definition that is employed

  20. Adhesives for orthodontic bracket bonding

    Directory of Open Access Journals (Sweden)

    Déborah Daniella Diniz Fonseca

    2010-04-01

    Full Text Available The advent of acid etching, introduced by Buonocore in 1955, brought the possibility of bonding between the bracket base and enamel, contributing to more esthetic and conservative orthodontics. This direct bracket bonding technique has brought benefits such as reduced cost and time in performing the treatment, as well as making it easier to perform oral hygiene. The aim of this study was to conduct a survey of published studies on orthodontic bracket bonding to dental enamel. It was verified that resin composites and glass ionomer are the most studied and researched materials for this purpose. Resin-modified glass ionomer, with its biocompatibility, capacity of releasing fluoride and no need for acid etching on the tooth structure, has become increasingly popular among dentists. However, due to the esthetic and mechanical properties of light polymerizable resin composite, it continues to be one of the adhesives of choice in the bracket bonding technique and its use is widely disseminated.

  1. Hydrogen bonding in tight environments

    DEFF Research Database (Denmark)

    Pirrotta, Alessandro; Solomon, Gemma C.; Franco, Ignacio

    2016-01-01

    The single-molecule force spectroscopy of a prototypical class of hydrogen-bonded complexes is computationally investigated. The complexes consist of derivatives of a barbituric acid and a Hamilton receptor that can form up to six simultaneous hydrogen bonds. The force-extension (F-L) isotherms...... of the host-guest complexes are simulated using classical molecular dynamics and the MM3 force field, for which a refined set of hydrogen bond parameters was developed from MP2 ab initio computations. The F-L curves exhibit peaks that signal conformational changes during elongation, the most prominent...... of which is in the 60-180 pN range and corresponds to the force required to break the hydrogen bonds. These peaks in the F-L curves are shown to be sensitive to relatively small changes in the chemical structure of the host molecule. Thermodynamic insights into the supramolecular assembly were obtained...

  2. Optimal Investment in Structured Bonds

    DEFF Research Database (Denmark)

    Jessen, Pernille; Jørgensen, Peter Løchte

    2012-01-01

    of the article is to provide possible explanations for the puzzle of why small retail investors hold structured bonds. The investment universe consists of a stock index, a risk-free bank account, and a structured bond containing an option written on another index. We apply expected utility maximization......Retail structured products regularly receive much criticism from financial experts but seem to remain popular with investors. This article considers a generic structured product: the principal-protected index-linked note (structured bond), which resembles a portfolio insurance contract. The purpose...... and consider different utility functions and trading strategies. Our results show that investors should include structured bonds in their optimal portfolio only if they cannot access the index underlying the option directly and only if the products then provide sufficient diversification to compensate...

  3. Enzyme mediated silicon-oxygen bond formation; the use of Rhizopus oryzae lipase, lysozyme and phytase under mild conditions.

    Science.gov (United States)

    Abbate, Vincenzo; Bassindale, Alan R; Brandstadt, Kurt F; Lawson, Rachel; Taylor, Peter G

    2010-10-21

    The potential for expanding the variety of enzymic methods for siloxane bond formation is explored. Three enzymes, Rhizopus oryzae lipase (ROL), lysozyme and phytase are reported to catalyse the condensation of the model compound, trimethylsilanol, formed in situ from trimethylethoxysilane, to produce hexamethyldisiloxane in aqueous media at 25 °C and pH 7. Thermal denaturation and reactant inhibition experiments were conducted to better understand the catalytic role of these enzyme candidates. It was found that enzyme activities were significantly reduced following thermal treatment, suggesting a potential key-role of the enzyme active sites in the catalysis. Similarly, residue-specific modification of the key-amino acids believed to participate in the ROL catalysis also had a significant effect on the silicon bio-catalysis, indicating that the catalytic triad of the lipase may be involved during the enzyme-mediated formation of the silicon-oxygen bond. E. coli phytase was found to be particularly effective at catalysing the condensation of trimethylsilanol in a predominantly organic medium consisting of 95% acetonitrile and 5% water. Whereas the use of enzymes in silicon chemistry is still very much a developing and frontier activity, the results presented herein give some grounds for optimism that the variety of enzyme mediated reactions will continue to increase and may one day become a routine element in the portfolio of the synthetic silicon chemist.

  4. Dexmedetomidine: Expanding role in anesthesia

    Directory of Open Access Journals (Sweden)

    Jyotsna S Paranjpe

    2013-01-01

    Full Text Available The potential uses of dexmedetomidine (DEX, a highly selective α2 - adrenoceptor agonist are very diverse. DEX appears to mimic many of the actions of mythical ′ideal′ sedative/analgesic agent. Although not orally active, DEX shows good bioavailability when administered via various other routes like intranasal, buccal, IM than intra-venous. DEX has similar pharmacokinetics in all age groups. Its side effects are predictable and easily treatable, hence it has found place as a part of fast-tracking anesthesia regimens in children. DEX is the sedative of choice for peri-operative use in high risk patients, since it is cardioprotective, neuroprotective and renoprotective. Premedication with DEX obtunds the autonomic pressor responses due to laryngoscopy and endotracheal intubation when used as an adjuvant to general anesthesia. DEX in high doses offers another approach to managing morbidly obese patients and patients with a compromised airway; without causing any cardio-respiratory depression. It is near ideal hypotensive agent used for controlled hypotension. Its value as a primary sedative and analgesic is becoming more accepted and evident in critically ill patients; in adult and paediatric intensive care units. Besides use in locoregional anesthesia, it is also used as an opioid substitute, for treatment of substance withdrawal, as an anti-shivering agent, for treatment of delirium and as an end of life medication. Availability of an antidote (Atipamezole with similar elimination half life is taking the drug into new frontiers. However, use of DEX is contraindicated in patients with hepatic failure, hypovolemic shock, advanced heart block or ventricular dysfunction.

  5. Theoretical evidence for bond stretch isomerism in Grubbs olefin metathesis.

    Science.gov (United States)

    Remya, Premaja R; Suresh, Cherumuttathu H

    2017-07-15

    A comprehensive density functional theory study on the dissociative and associative mechanisms of Grubbs first and second generation olefin metathesis catalysis reveals that ruthenacyclobutane intermediate (RuCB) observed in the Chauvin mechanism is not unique as it can change to a non-metathetic ruthenacyclobutane (RuCB') via the phenomenon of bond stretch isomerism (BSI). RuCB and RuCB' differ mainly in RuC α , RuC β , and C α C β bond lengths of the metallacycle. RuCB is metathesis active due to the agostic type bonding-assisted simultaneous activation of both C α C β bonds, giving hypercoordinate character to C β whereas an absence of such bonding interactions in RuCB' leads to typical CC single bond distances and metathesis inactivity. RuCB and RuCB' are connected by a transition state showing moderate activation barrier. The new mechanistic insights invoking BSI explains the non-preference of associative mechanism and the requirement of bulky ligands in the Grubbs catalyst design. The present study lifts the status of BSI from a concept of largely theoretical interest to a phenomenon of intense importance to describe an eminent catalytic reaction. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  6. Establishment of mouse expanded potential stem cells.

    Science.gov (United States)

    Yang, Jian; Ryan, David J; Wang, Wei; Tsang, Jason Cheuk-Ho; Lan, Guocheng; Masaki, Hideki; Gao, Xuefei; Antunes, Liliana; Yu, Yong; Zhu, Zhexin; Wang, Juexuan; Kolodziejczyk, Aleksandra A; Campos, Lia S; Wang, Cui; Yang, Fengtang; Zhong, Zhen; Fu, Beiyuan; Eckersley-Maslin, Melanie A; Woods, Michael; Tanaka, Yosuke; Chen, Xi; Wilkinson, Adam C; Bussell, James; White, Jacqui; Ramirez-Solis, Ramiro; Reik, Wolf; Göttgens, Berthold; Teichmann, Sarah A; Tam, Patrick P L; Nakauchi, Hiromitsu; Zou, Xiangang; Lu, Liming; Liu, Pentao

    2017-10-19

    Mouse embryonic stem cells derived from the epiblast contribute to the somatic lineages and the germline but are excluded from the extra-embryonic tissues that are derived from the trophectoderm and the primitive endoderm upon reintroduction to the blastocyst. Here we report that cultures of expanded potential stem cells can be established from individual eight-cell blastomeres, and by direct conversion of mouse embryonic stem cells and induced pluripotent stem cells. Remarkably, a single expanded potential stem cell can contribute both to the embryo proper and to the trophectoderm lineages in a chimaera assay. Bona fide trophoblast stem cell lines and extra-embryonic endoderm stem cells can be directly derived from expanded potential stem cells in vitro. Molecular analyses of the epigenome and single-cell transcriptome reveal enrichment for blastomere-specific signature and a dynamic DNA methylome in expanded potential stem cells. The generation of mouse expanded potential stem cells highlights the feasibility of establishing expanded potential stem cells for other mammalian species.

  7. LAMMPS Framework for Directional Dynamic Bonding

    DEFF Research Database (Denmark)

    2012-01-01

    and bond types. When breaking bonds, all angular and dihedral interactions involving broken bonds are removed. The framework allows chemical reactions to be modeled, and use it to simulate a simplistic, coarse-grained DNA model. The resulting DNA dynamics illustrates the power of the present framework.......We have extended the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to support directional bonds and dynamic bonding. The framework supports stochastic formation of new bonds, breakage of existing bonds, and conversion between bond types. Bond formation can be controlled...... to limit the maximal functionality of a bead with respect to various bond types. Concomitant with the bond dynamics, angular and dihedral interactions are dynamically introduced between newly connected triplets and quartets of beads, where the interaction type is determined from the local pattern of bead...

  8. Korea: an expanding economy trying to gain energy independence

    International Nuclear Information System (INIS)

    Parrott, M.

    1980-01-01

    South Korea expects to have 6426 MW of power installed by 1986, representing 30.7% of its capacity. Following a summary of nuclear activities in South Korea the current situation is discussed. Prospects for energy supply and demand are shown. The difficulties associated with the expanding nuclear programme are mainly on the international front, eg those relating to fuel supply, or to proliferation issue. (UK)

  9. Topology of electron charge density for chemical bonds from valence bond theory: a probe of bonding types.

    Science.gov (United States)

    Zhang, Lixian; Ying, Fuming; Wu, Wei; Hiberty, Philippe C; Shaik, Sason

    2009-01-01

    To characterize the nature of bonding we derive the topological properties of the electron charge density of a variety of bonds based on ab initio valence bond methods. The electron density and its associated Laplacian are partitioned into covalent, ionic, and resonance components in the valence bond spirit. The analysis provides a density-based signature of bonding types and reveals, along with the classical covalent and ionic bonds, the existence of two-electron bonds in which most of the bonding arises from the covalent-ionic resonance energy, so-called charge-shift bonds. As expected, the covalent component of the Laplacian at the bond critical point is found to be largely negative for classical covalent bonds. In contrast, for charge-shift bonds, the covalent part of the Laplacian is small or positive, in agreement with the weakly attractive or repulsive character of the covalent interaction in these bonds. On the other hand, the resonance component of the Laplacian is always negative or nearly zero, and it increases in absolute value with the charge-shift character of the bond, in agreement with the decrease of kinetic energy associated with covalent-ionic mixing. A new interpretation of the topology of the total density at the bond critical point is proposed to characterize covalent, ionic, and charge-shift bonding from the density point of view.

  10. Can laccases catalyze bond cleavage in lignin?

    Science.gov (United States)

    Munk, Line; Sitarz, Anna K; Kalyani, Dayanand C; Mikkelsen, J Dalgaard; Meyer, Anne S

    2015-01-01

    Modification of lignin is recognized as an important aspect of the successful refining of lignocellulosic biomass, and enzyme-assisted processing and upcycling of lignin is receiving significant attention in the literature. Laccases (EC 1.10.3.2) are taking the centerstage of this attention, since these enzymes may help degrading lignin, using oxygen as the oxidant. Laccases can catalyze polymerization of lignin, but the question is whether and how laccases can directly catalyze modification of lignin via catalytic bond cleavage. Via a thorough review of the available literature and detailed illustrations of the putative laccase catalyzed reactions, including the possible reactions of the reactive radical intermediates taking place after the initial oxidation of the phenol-hydroxyl groups, we show that i) Laccase activity is able to catalyze bond cleavage in low molecular weight phenolic lignin model compounds; ii) For laccases to catalyze inter-unit bond cleavage in lignin substrates, the presence of a mediator system is required. Clearly, the higher the redox potential of the laccase enzyme, the broader the range of substrates, including o- and p-diphenols, aminophenols, methoxy-substituted phenols, benzenethiols, polyphenols, and polyamines, which may be oxidized. In addition, the currently available analytical methods that can be used to detect enzyme catalyzed changes in lignin are summarized, and an improved nomenclature for unequivocal interpretation of the action of laccases on lignin is proposed. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. CS Bond formation by

    Indian Academy of Sciences (India)

    2017-02-02

    Feb 2, 2017 ... G, Brancale A, Hamel E, Artico M and Silvestri R. 2006 New arylthioindoles: Potent inhibitors of tubulin polymerization. 2. Structure-activity relationships and molecular modeling studies J. Med. Chem. 49 947;. (c) Gangjee A, Zeng Y, Talreja T, McGuire J J, Kisliuk. R L and Queener S F 2007 Design and ...

  12. What moves the primary stock and bond markets? Influence of macroeconomic factors on bond and equity issues in Malaysia and Korea

    OpenAIRE

    Ameer, Rashid

    2007-01-01

    This paper examines the impact of macroeconomic factors on the stock and bond market activities in two Asian countries. We examine the influence of interest rate changes, expected inflation rate, and stock market returns on aggregate stock and bond issuance in Malaysia and Korea. Using vector autoregressive models (VARs) and variance decomposition techniques, our result show that dynamics of equity and bond issuance in both countries vary significantly. Our findings show that there has been a...

  13. Heterolytic cleavage of ammonia N-H bond by bifunctional activation in silica-grafted single site Ta(V) imido amido surface complex. Importance of the outer sphere NH3 assistance

    KAUST Repository

    Gouré, Eric

    2011-01-01

    Ammonia N-H bond is cleaved at room temperature by the silica-supported tantalum imido amido complex [(≡SiO)2Ta(NH)(-NH2)], 2, if excess ammonia is present, but requires 150 °C to achieve the same reaction if only one equivalent NH3 is added to 2. MAS solid-state 15N NMR and in situ IR spectroscopic studies of the reaction of either 15N or 2H labeled ammonia with 2 show that initial coordination of the ammonia is followed by scrambling of either 15N or 2H among ammonia, amido and imido groups. Density functional theory (DFT) calculations with a cluster model [{(μ-O)[(H3SiO) 2SiO]2}Ta(NH)(-NH2)(NH3)], 2 q·NH3, show that the intramolecular H transfer from Ta-NH2 to TaNH is ruled out, but the H transfers from the coordinated ammonia to the amido and imido groups have accessible energy barriers. The energy barrier for the ammonia N-H activation by the Ta-amido group is energetically preferred relative to the Ta-imido group. The importance of excess NH3 for getting full isotope scrambling is rationalized by an outer sphere assistance of ammonia acting as proton transfer agent, which equalizes the energy barriers for H transfer from coordinated ammonia to the amido and imido groups. In contrast, additional coordinated ammonia does not favor significantly the H transfer. These results rationalize the experimental conditions used. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.

  14. AstroCom NYC: Expanding the Partnership

    Science.gov (United States)

    Paglione, Timothy; Ford, Saavik; Agueros, Marcel A.; Mac Low, Mordecai-Mark; Robbins, Dennis

    2015-01-01

    AstroCom NYC is an undergraduate mentoring program designed to improve urban minority student access to opportunities in astrophysical research by greatly enhancing partnerships between research astronomers in New York City (City University of New York - an MSI, American Museum of Natural History, and Columbia). AstroCom NYC provides centralized, personalized mentoring as well as financial and academic support, to CUNY undergraduates throughout their studies, plus the resources and opportunities to further CUNY faculty research with students. The goal is that students' residency at AMNH helps them build a sense of belonging in the field, and readies and inspires them for graduate study. AstroCom NYC provides a rigorous Methods of Scientific Research course developed specifically to this purpose, a laptop, research and career mentors, outreach activities, scholarships and stipends, Metrocards, and regular assessment for maximum effectiveness. Stipends in part alleviate the burdens at home typical for CUNY students so they may concentrate on their academic success. AMNH serves as the central hub for our faculty and students, who are otherwise dispersed among all five boroughs of the City. For our second cohort, we dramatically improved the application and screening process, implemented a number of tools to evaluate their potential for grad school, and began growing a network of potential hosts for summer internships around NY State and the US. We review these implementations and outcomes, as well as plans for Year 3, when we expect many of our current students to compete for external summer REUs, and after greatly expanding the program reach through a NASA community college initiative.

  15. "Vibrational bonding": a new type of chemical bond is discovered.

    Science.gov (United States)

    Rhodes, Christopher J; Macrae, Roderick M

    2015-01-01

    A long-sought but elusive new type of chemical bond, occurring on a minimum-free, purely repulsive potential energy surface, has recently been convincingly shown to be possible on the basis of high-level quantum-chemical calculations. This type of bond, termed a vibrational bond, forms because the total energy, including the dynamical energy of the nuclei, is lower than the total energy of the dissociated products, including their vibrational zero-point energy. For this to be the case, the ZPE of the product molecule must be very high, which is ensured by replacing a conventional hydrogen atom with its light isotope muonium (Mu, mass = 1/9 u) in the system Br-H-Br, a natural transition state in the reaction between Br and HBr. A paramagnetic species observed in the reaction Mu +Br2 has been proposed as a first experimental sighting of this species, but definitive identification remains challenging.

  16. 27 CFR 19.516 - Bond account.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bond account. 19.516... Determination and Payment of Tax § 19.516 Bond account. Where the proprietor has furnished a withdrawal or unit... maximum penal sum, he shall maintain an account of his bond and he shall charge the bond with the amount...

  17. Common Factors in International Bond Returns

    NARCIS (Netherlands)

    Driessen, J.J.A.G.; Melenberg, B.; Nijman, T.E.

    2000-01-01

    In this paper we estimate and interpret the factors that jointly determine bond returns of different maturities in the US, Germany and Japan.We analyze both currency-hedged and unhedged bond returns.For currency-hedged bond returns, we find that five factors explain 96.5% of the variation of bond

  18. Possible involvement of the A20-A21 peptide bond in the expression of the biological activity of insulin. 3. [21-Desasparagine,20-cysteine ethylamide-A]insulin and [21-desasparagine,20-cysteine 2,2,2-trifluoroethylamide-A]insulin

    International Nuclear Information System (INIS)

    Chu, Y.C.; Wang, R.Y.; Burke, G.T.; Chanley, J.D.; Katsoyannis, P.G.

    1987-01-01

    The authors have synthesized [21-desasparagine,20-cysteine ethylamide-A]insulin and [21-desasparagine,20-cysteine,2,2,2,-trifluoroethylamide-A]insulin, which differ from natural insulin in that the C-terminal amino residue of the A chain, asparagine, has been removed and the resulting free carboxyl group of the A 20 cysteine residue has been converted to an ethylamide and a trifluoroethylamide group, respectively. [21-Desasparagine,20-cysteine ethylamide-A]insulin displayed equivalent potency in receptor binding and biological activity, ca. 12% and ca. 14%, respectively, relative to bovine insulin. In contrast, [21-desasparagine,20-cysteine 2,2,2-trifluoroethylamide-A]insulin displayed a divergence in these properties, ca. 13% in receptor binding and ca. 6% in biological activity. This disparity is ascribed to a difference in the electronic state of the A 20 -A 21 amide bond in these two analogues. A model is proposed to account for the observation of divergence between receptor binding and biological activity in a number of synthetic insulin analogues and naturally occurring insulins. In this model, changes in the electronic state and/or the orientation of the A 20 -A 21 amide bond can modulate biological activity independently of receptor binding affinity. The A 20 -A 21 amide bond is thus considered as an important element in the message region of insulin

  19. Three methods to measure RH bond energies

    Energy Technology Data Exchange (ETDEWEB)

    Berkowitz, J. [Argonne National Lab., IL (United States); Ellison, G.B. [Univ. of Colorado, Boulder, CO (United States). Dept. of Chemistry and Biochemistry; Gutman, D. [Catholic Univ. of America, Washington, DC (United States). Dept. of Chemistry

    1993-03-21

    In this paper the authors compare and contrast three powerful methods for experimentally measuring bond energies in polyatomic molecules. The methods are: radical kinetics; gas phase acidity cycles; and photoionization mass spectroscopy. The knowledge of the values of bond energies are a basic piece of information to a chemist. Chemical reactions involve the making and breaking of chemical bonds. It has been shown that comparable bonds in polyatomic molecules, compared to the same bonds in radicals, can be significantly different. These bond energies can be measured in terms of bond dissociation energies.

  20. Three methods to measure RH bond energies

    International Nuclear Information System (INIS)

    Berkowitz, J.; Ellison, G.B.; Gutman, D.

    1993-01-01

    In this paper the authors compare and contrast three powerful methods for experimentally measuring bond energies in polyatomic molecules. The methods are: radical kinetics; gas phase acidity cycles; and photoionization mass spectroscopy. The knowledge of the values of bond energies are a basic piece of information to a chemist. Chemical reactions involve the making and breaking of chemical bonds. It has been shown that comparable bonds in polyatomic molecules, compared to the same bonds in radicals, can be significantly different. These bond energies can be measured in terms of bond dissociation energies

  1. Low temperature anodic bonding to silicon nitride

    DEFF Research Database (Denmark)

    Weichel, Steen; Reus, Roger De; Bouaidat, Salim

    2000-01-01

    Low-temperature anodic bonding to stoichiometric silicon nitride surfaces has been performed in the temperature range from 3508C to 4008C. It is shown that the bonding is improved considerably if the nitride surfaces are either oxidized or exposed to an oxygen plasma prior to the bonding. Both bulk...... and thin-film glasses were used in the bonding experiments. Bond quality was evaluated using a tensile test on structured dies. The effect of oxygen-based pre-treatments of the nitride surface on the bond quality has been evaluated. Bond strengths up to 35 Nrmm2 and yields up to 100% were obtained....

  2. Deriving the bond pricing equation

    Directory of Open Access Journals (Sweden)

    Kožul Nataša

    2014-01-01

    Full Text Available Given the recent focus on Eurozone debt crisis and the credit rating downgrade not only of US debt, but that of other countries and many UK major banking institutions, this paper aims to explain the concept of bond yield, its different measures and bond pricing equation. Yields on capital market instruments are rarely quoted on the same basis, which makes direct comparison between different as investment choices impossible. Some debt instruments are quoted on discount basis, whilst coupon-bearing ones accrue interest differently, offer different compounding opportunities, have different coupon payment frequencies, and manage non-business day maturity dates differently. Moreover, rules governing debt vary across countries, markets and currencies, making yield calculation and comparison a rather complex issue. Thus, some fundamental concepts applicable to debt instrument yield measurement, with focus on bond equation, are presented here. In addition, bond equation expressed in annuity form and used to apply Newton-Raphson algorithm to derive true bond yield is also shown.

  3. Diffusionless bonding of aluminum to Zircaloy-2

    International Nuclear Information System (INIS)

    Watson, R.D.

    1965-04-01

    Aluminum can be bonded to zirconium without difficulty even when a thin layer of oxide is present on the surface of the zirconium . No detectable diffusion takes place during the bonding process. The bond layer can be stretched as much. as 8% without affecting the bond. The bond can be heated for 1000 hours at 260 o C (500 o F), and can be water quenched from 260 o C (500 o F) without any noticeable change in the bond strength. An extrusion technique has been devised for making transition sections of aluminum bonded to zirconium which can then be used to join these metals by conventional welding. Welding can be done close to the bond zone without seriously affecting the integrity of the bond. This method of bonding aluminum to Zircaloy-2 is covered by Canadian patent 702,438 January 26, 1965. (author)

  4. Cooperative Research and Development Agreement Final Report for Cooperative Research and Development Agreement Number ORNL93-0237 Adhesive Bonding Technologies for Automotive Structural Composites; TOPICAL

    International Nuclear Information System (INIS)

    Boeman, R.G.

    2001-01-01

    In 1993, the Oak Ridge National Laboratory (ORNL) entered into a Cooperative Research and Development Agreement (CRADA) with the Automotive Composites Consortium (ACC) to conduct research and development that would overcome technological hurdles to the adhesive bonding of current and future automotive materials. This effort is part of a larger Department of Energy (DOE) program to promote the use of lighter weight materials in automotive structures for the purpose of increasing fuel efficiency and reducing environmental pollutant emissions. In accomplishing this mission, the bonding of similar and dissimilar materials was identified as being of primary importance to the automotive industry since this enabling technology would give designers the freedom to choose from an expanded menu of low mass materials for component weight reduction. The research undertaken under this CRADA addresses the following areas of importance: bulk material characterization, structural fracture mechanics, modeling/characterization, process control and nondestructive evaluation (PC/NDE), manufacturing demonstration, and advanced processing. For the bulk material characterization task, the individual material properties of the adherends and adhesives were characterized. This included generating a database of mechanical and physical properties, after identifying and developing standard test methods to obtain properties. The structural fracture mechanics task concentrated on test development to characterize the fracture toughness of adhesively bonded joints subjected to Mode I, Mode II and mixed-mode conditions. Standard test procedures for quantifying an adhesive/adherend system's resistance to crack growth were developed for use by industry. In the modeling/characterization task, fracture mechanics-based design guidelines and predictive methodologies have been developed which will facilitate iteration on design concepts for bonded joints while alleviating the need for extensive testing

  5. Graphite-to-metal bonding techniques

    International Nuclear Information System (INIS)

    Lindquist, L.O.; Mah, R.

    1977-11-01

    The results of various bonding methods to join graphite to different metals are reported. Graphite/metal bonds were tested for thermal flux limits and thermal flux cycling lifetimes. The most successful bond transferred a heat flux of 6.50 MW/m 2 in more than 500 thermal cycles. This bond was between pyrolytic graphite and copper with Ti-Cu-Sil as the bonding agent

  6. Expanding Horizons Teachers and Scientists Collabortaing

    Science.gov (United States)

    Teres, A.

    2017-12-01

    As a participant in PolarTrec, I joined the crew of NASA's Operation IceBridge in Greenland for the month of April 2017. As an active member of the team I learned the ins and outs of field research, and I learned about the work done by Operation IceBridge. As a result of participating in this project, I grew as a teacher and a scientist. I took my experiences and shared them with my classroom through stories, pictures, videos, and my lesson plans. By seeing the Artic through my experiences the class became enraptured by the subject matter. I was no longer talking about a distant or abstract place instead I was talking about an experience. This enabled my students to take an active part in the discussion and to feel like the cryosphere was part of their life too. Not only did I learn about the science but I leaned about logistics of field research. I reached out to my community and local communications outlets before and after my trip to Greenland to familiarize whomever I could connect with about my experience. I contacted a local news station and they did an interview with me about my trip. I emailed a local newspaper about my trip and was interviewed before I left and after I returned. Due to the newscast, I was contacted by my college sorority and was interviewed for the sorority's national newsletter which is distributed throughout the United States. Each connection helped to spread the word. I'm continuing to spread the word by volunteering to present my experience to schools throughout Broward County in Florida. I've already connected with teachers and schools to set up my presentation in the calendar. Having these types of experiences is critical for teachers to continue their growth within the scientific field and education. Effective teachers are those not constrained by the walls of their classroom. Having the opportunity to work with scientists and do research in the field has expanded my horizons. The people I met I am still in contact with and I am

  7. Bank Directors’ Perceptions of Expanded Auditor's Reports

    DEFF Research Database (Denmark)

    Boolaky, Pran Krishansing; Quick, Reiner

    2016-01-01

    Subsequent to the financial crisis, standard setters developed suggestions for enhancing the audit function, in order to increase financial stability. One related idea is to expand the audit report disclosed to the public, to ensure that it is fit for purpose. This study investigates the impact...... of expanded audit reports, namely information on the assurance level, materiality levels and key audit matters (KAM), on bank director perceptions of the quality of the financial statements, the audit and the audit report, as well as on their credit approval decisions. We conduct an experiment involving...... a sample of 105 bank directors and use ANCOVA to determine the predictors of bank director perceptions and decisions. Our findings suggest that disclosing the assurance level has a significantly positive impact. In contrast, we cannot demonstrate a material effect of expanding the audit report to include...

  8. Bonded retainers--clinical reliability.

    Science.gov (United States)

    Segner, D; Heinrici, B

    2000-01-01

    Bonded retainers have become a very important retention appliance in orthodontic treatment. They are popular because they are considered reliable, independent of patient cooperation, highly efficient, easy to fabricate, and almost invisible. Of these traits, reliability is the subject of this clinical study. A total of 549 patients with retainers were analyzed with regard to wearing time, extension of the retainer, mean time between failures, operator, and age of patient. The average frequency of breakage or loss was 0.55 per retainer per year. This frequency was dependent primarily on the operator who bonded the retainer and on the extent of the retainer. If the upper canines were involved, reliability was lower. The majority of failures occurred during the first 3 to 6 months. The study showed that bonded retainers represent a highly efficient and reliable retention appliance suited to long-term use.

  9. EFFECTIVE CHEMICALLY BONDED BUILDING MATERIALS

    Directory of Open Access Journals (Sweden)

    Сергей Николаевич Золотухин

    2017-11-01

    Full Text Available Physical and physical-and-chemical preconditions for creation of the production technology of chemically bonded building materials and products based on phosphogypsum are presented. The methodology and production technology of chemically bonded lime-and-sandy phosphogypsum material (LSPM with the use of modern computerized differential scanning calorimetry are developed and offered. The structure of LSPM is examined. The conceptions of making building composites on the basis of dispersed materials are proved and updated. It was found out that at the definite thickness of water film on the surface of disperse materials, in the thermodynamically unstable state, in the presence of external fields, heightened temperatures and definite pH, cheap water-resistant chemically bonded building composites on the basis of dispersed materials can be made. The results of the LSPM studies showed that such material is effective for forming of low- and middle-quality wall small-piece blocks, partition slabs and bulkheads.

  10. Simultaneous bond degradation and bond formation during phenol-formaldehyde curing with wood

    Science.gov (United States)

    Daniel J. Yelle; John Ralph

    2016-01-01

    Bonding of wood using phenol–formaldehyde adhesive develops highly durable bonds. Phenol– formaldehyde is believed to form primary bonds with wood cell wall polymers (e.g., lignin). However, it is unclear how this adhesive interacts and bonds to lignin. Through wood solubilisation methodologies, earlywood and latewood bonded assemblies were characterized using two-...

  11. Operational test of bonded magnetocaloric plates

    DEFF Research Database (Denmark)

    Bahl, Christian; Navickaité, Kristina; Neves Bez, Henrique

    2017-01-01

    Bonded plates made by hot pressing La0.85Ce0.15Fe11.25Mn0.25Si1.5Hy particles and resin have been tested as active magnetic regenerators in a small scale magnetocaloric device. Firstly the plates were carefully characterised magnetically and thermally. The plates were prepared with 5 wt% resin......, and from density measurements it was found that the volume ratio of the magnetocaloric material in the plates was 0.53, due to the resin and porosity. The best operating conditions for the plate regenerator were determined at which a temperature span of 6.4 K was measured along the plates....

  12. Electron transfer in pnicogen bonds.

    Science.gov (United States)

    Guan, Liangyu; Mo, Yirong

    2014-10-02

    As a new type of noncovalent interactions, pnicogen bond between a VA group element (N, P, and As) and an electron donor (Lewis base) has grabbed attention in recent several years. Here we employ the block-localized wave function (BLW) based energy decomposition scheme to probe the bonding nature in a series of substituted phosphines X(n)PH(3-n) complexed with ammonia. As the BLW method can derive the optimal monomer orbitals in a complex with the electron transfer among monomers quenched, we can effectively examine the HOMO-LUMO interaction in these pnicogen bonding systems. Among various energy components, electron transfer energy together with the polarization energy dominates the pnicogen bonding energy. Although usually it is assumed that the electron transfer from ammonia to substituted phosphines occurs in the form of n → σ*(XP) hyperconjugative interaction, we identify a kind of new pathway when X = NO2 and CN, i.e., n → dπ*, which results from the interaction between the π orbital of cyano or nitro substituent and d orbitals on P. But still this picture of electron transfer using a single pair of orbitals is greatly simplified, as the electron density difference (EDD) maps corresponding to the overall electron transfer processes show the accumulation of electron density on the P side opposite to the X-P bond, with insignificant or even negligible gain of electron density on the substituent group side. Thus, the EDD maps tend to support the concept of σ-hole in pnicogen bonds.

  13. Theoretical models for recombination in expanding gas

    International Nuclear Information System (INIS)

    Avron, Y.; Kahane, S.

    1978-09-01

    In laser isotope separation of atomic uranium, one is confronted with the theoretical problem of estimating the concentration of thermally ionized uranium atoms. To investigate this problem theoretical models for recombination in an expanding gas and in the absence of local thermal equilibrium have been constructed. The expansion of the gas is described by soluble models of the hydrodynamic equation, and the recombination by rate equations. General results for the freezing effect for the suitable ranges of the gas parameters are obtained. The impossibility of thermal equilibrium in expanding two-component systems is proven

  14. Expanding your horizons in science and mathematics

    Science.gov (United States)

    1985-01-01

    Through the presentation of its Expanding Your Horizons in Science and Mathematics career education conferences for secondary school young women, the Math/Science Network continues its efforts to remove the educational, psychological, and cultural barriers which prevent women from entering math-and science-based careers. The Expanding Your Horizons conferences were presented on 77 college, university and high school campuses across the United States. This year, these unique one day conferences reached 15,500 students, 3,000 parents and educators, and involved 3,000 career women who volunteered their services as conference planners, workshop leaders, speakers, and role models.

  15. Catalysis of Protein Disulfide Bond Isomerization in a Homogeneous Substrate†

    Science.gov (United States)

    Kersteen, Elizabeth A.; Barrows, Seth R.; Raines, Ronald T.

    2008-01-01

    Protein disulfide isomerase (PDI) catalyzes the rearrangement of nonnative disulfide bonds in the endoplasmic reticulum of eukaryotic cells, a process that often limits the rate at which polypeptide chains fold into a native protein conformation. The mechanism of the reaction catalyzed by PDI is unclear. In assays involving protein substrates, the reaction appears to involve the complete reduction of some or all of its nonnative disulfide bonds followed by oxidation of the resulting dithiols. The substrates in these assays are, however, heterogeneous, which complicates mechanistic analyses. Here, we report the first analysis of disulfide bond isomerization in a homogeneous substrate. Our substrate is based on tachyplesin I, a 17-mer peptide that folds into a _-hairpin stabilized by two disulfide bonds. We describe the chemical synthesis of a variant of tachyplesin I in which its two disulfide bonds are in a nonnative state and side chains near its N-and C-terminus contain a fluorescence donor (tryptophan) and acceptor (N_-dansyllysine). Fluorescence resonance energy transfer from 280 to 465 nm increases by 28-fold upon isomerization of the disulfide bonds into their native state (which has a lower E°_ = -0.313 V than does PDI). We use this continuous assay to analyze catalysis by wild-type human PDI and a variant in which the C-terminal cysteine residue within each Cys—Gly—His—Cys active site is replaced with alanine. We find that wild-type PDI catalyzes the isomerization of the substrate with kcat/KM = 1.7 _ 105 M–1M s–1, which is the largest value yet reported for catalysis of disulfide bond isomerization. The variant, which is a poor catalyst of disulfide bond reduction and dithiol oxidation, retains virtually all of the activity of wild-type PDI in catalysis of disulfide bond isomerization. Thus, the C-terminal cysteine residues play an insignificant role in the isomerization of the disulfide bonds in nonnative tachyplesin I. We conclude that

  16. Catalysis of protein disulfide bond isomerization in a homogeneous substrate.

    Science.gov (United States)

    Kersteen, Elizabeth A; Barrows, Seth R; Raines, Ronald T

    2005-09-13

    Protein disulfide isomerase (PDI) catalyzes the rearrangement of nonnative disulfide bonds in the endoplasmic reticulum of eukaryotic cells, a process that often limits the rate at which polypeptide chains fold into a native protein conformation. The mechanism of the reaction catalyzed by PDI is unclear. In assays involving protein substrates, the reaction appears to involve the complete reduction of some or all of its nonnative disulfide bonds followed by oxidation of the resulting dithiols. The substrates in these assays are, however, heterogeneous, which complicates mechanistic analyses. Here, we report the first analysis of disulfide bond isomerization in a homogeneous substrate. Our substrate is based on tachyplesin I, a 17-mer peptide that folds into a beta hairpin stabilized by two disulfide bonds. We describe the chemical synthesis of a variant of tachyplesin I in which its two disulfide bonds are in a nonnative state and side chains near its N and C terminus contain a fluorescence donor (tryptophan) and acceptor (N(epsilon)-dansyllysine). Fluorescence resonance energy transfer from 280 to 465 nm increases by 28-fold upon isomerization of the disulfide bonds into their native state (which has a lower E(o') = -0.313 V than does PDI). We use this continuous assay to analyze catalysis by wild-type human PDI and a variant in which the C-terminal cysteine residue within each Cys-Gly-His-Cys active site is replaced with alanine. We find that wild-type PDI catalyzes the isomerization of the substrate with kcat/K(M) = 1.7 x 10(5) M(-1) s(-1), which is the largest value yet reported for catalysis of disulfide bond isomerization. The variant, which is a poor catalyst of disulfide bond reduction and dithiol oxidation, retains virtually all of the activity of wild-type PDI in catalysis of disulfide bond isomerization. Thus, the C-terminal cysteine residues play an insignificant role in the isomerization of the disulfide bonds in nonnative tachyplesin I. We conclude

  17. Why Bond Critical Points Are Not "Bond" Critical Points.

    Science.gov (United States)

    Shahbazian, Shant

    2017-12-28

    Equating (3,-1) critical points (CPs), derived from the topological analysis of the electron densities, to chemical bonds has triggered a lot of confusion in recent years. Part of this confusion stems from calling these CPs "bond" CPs (BCPs). While the origin of this terminology is traceable to the late seventies and beginning of eighties, when it sounded reasonable, new computational studies conducted on molecular electron densities cast serious doubt on the supposed universal equivalence between the chemical bonds and (3,-1) CPs. Herein, recent computational studies are briefly reviewed to demonstrate why (3,-1) CPs are not indicators of chemical bonds. It is discussed why this confusing terminology needs to be changed and reemphasized that (3,-1) CPs should be called "line" critical points (LCPs). The proposed terminology detaches the topological properties of molecular electron densities from any a priori chemical interpretation. Such detachment, if adopted by other authors, will hopefully prevent further misinterpretation of the data emerging from the quantum theory of atoms in molecules (QTAIM). © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Analysis Of Chemical Bonding Using Ab Initio Valence Bond Theory

    NARCIS (Netherlands)

    Engelberts, J.J.

    2017-01-01

    In this thesis, theoretical chemical research is presented in which the Valence Bond (VB) Theory plays a central role. For the last three chapters, the VB method is used, in combination with Magnetically Induced Ring Currents, to analyze the aromaticity of several conjugated molecules. The

  19. Shear bond strength of dual-cured and self-cured resin composites to dentin using different bonding agents and techniques.

    Science.gov (United States)

    Leevailoj, C; Ua-wutthikrerk, P; Poolthong, S

    2007-01-01

    This study determined the effects of bonding agents on the shear bond strength of dual- and self-cured resin composites to dentin. Two light-cured dentin bonding agents (Excite and One-Step) and a dual-cured bonding agent (Excite DSC) were compared. Light activation of the bonding agents prior to placement of the resin composites was also evaluated. This in vitro study was performed on 120 extracted non-carious human third molars. The occlusal part of the crowns was removed to expose a flat dentin surface. The teeth were then randomly divided into three major groups for Excite, One-Step and Excite DSC as bonding agents. The specimens in each adhesive group were divided into four subgroups: with and without light activation of the bonding agent and with dual-cured (Luxacore Dualcure, DMG, Hamburg, Germany) or light-cured resin (Luxacore, DMG, Hamburg, Germany) composites. After placing the restorations, the specimens were kept in water at 37 degrees C for 24 hours before being tested for shear bond strength on an Instron universal testing machine at a crosshead speed of 0.5 mm/minute. The results showed that the shear bond strength of dual-cured resin composite to dentin was significantly higher than that of self-cured resin composite (p = 0.017). Light activation of the bonding agents prior to applying the resin composites led to a significantly higher shear bond strength of the resin composites to dentin, compared to no light activation (p < 0.05).

  20. High-temperature, high-pressure bonding of nested tubular metallic components

    International Nuclear Information System (INIS)

    Quinby, T.C.

    1980-01-01

    This invention is a tool for effecting high-temperature, high compression bonding between the confronting faces of nested, tubular, metallic components. In a typical application, the tool is used to produce tubular target assemblies for irradiation in nuclear reactors or particle accelerators, the target assembly comprising a uranium foil and an aluminum-alloy substrate. The tool preferably is composed throughout of graphite. It comprises a tubular restraining member in which a mechanically expandable tubular core is mounted to form an annulus with the member. The components to be bonded are mounted in nested relation in the annulus. The expandable core is formed of individually movable, axially elongated segments whose outer faces cooperatively define a cylindrical pressing surface and whose inner faces cooperatively define two opposed, inwardly tapered, axial bores. Tapered rams extend respectively into the bores. The loaded tool is mounted in a conventional hot-press provided with evacuation means, heaters for maintaining its interior at bonding temperature, and hydraulic cylinders for maintaining a selected inwardly directed pressure on the tapered rams. With the hotpress evacuated and the loaded tool at the desired temperature, the cylinders are actuated to apply the selected pressure to the rams. The rams in turn expand the segmented core to maintain the nested components in compression against the restraining member. These conditions are maintained until the confronting faces of the nested components are joined in a continuous, uniform bond characterized by high thermal conductivity

  1. High-temperature, high-pressure bonding of nested tubular metallic components

    Science.gov (United States)

    Quinby, T.C.

    A tool is described for effecting high-temperature, high-compression bonding between the confronting faces of nested, tubular, metallic components. In a typical application, the tool is used to produce tubular target assemblies for irradiation in nuclear reactors or particle accelerators. The target assembly comprising a uranum foil and an aluninum-alloy substrate. The tool is composed of graphite. It comprises a tubular restraining member in which a mechanically expandable tubular core is mounted to form an annulus. The components to be bonded are mounted in nested relation in the annulus. The expandable core is formed of individually movable, axially elongated segments whose outer faces cooperatively define a cylindrical pressing surface and whose inner faces cooperatively define two opposed, inwardly tapered, axial bores. Tapered rams extend into the bores. The loaded tool is mounted in a conventional hot-press provided with evacuation means, heaters for maintaining its interior at bonding temperature, and hydraulic cylinders for maintaining a selected inwardly directed pressure on the tapered rams. With the hot-press evacuated and the loaded tool at the desired temperature, the cylinders are actuated to apply the selected pressure to the rams. The rams in turn expand the segmented core to maintain the nested components in compression against the restraining member. These conditions are maintained until the confronting faces of the nested components are joined in a continuous, uniform bond characterized by high thermal conductivity.

  2. Circle diffeomorphisms forced by expanding circle maps

    NARCIS (Netherlands)

    Homburg, A.J.

    2012-01-01

    We discuss the dynamics of skew product maps defined by circle diffeomorphisms forced by expanding circle maps. We construct an open class of such systems that are robustly topologically mixing and for which almost all points in the same fiber converge under iteration. This property follows from the

  3. Strengthening youth friendly health services through expanding ...

    African Journals Online (AJOL)

    Strengthening youth friendly health services through expanding method choice to include long-acting reversible contraceptives for Ethiopian youth. ... Odds of adopting LARCs at pre-intervention (0.70); rose to 1.30 for the post-intervention phase (p-value <0.0001); comparing intervention to non-intervention study arms.

  4. Expanding economic opportunities in protracted displacement

    Directory of Open Access Journals (Sweden)

    Miki Takahashi

    2018-02-01

    Full Text Available Welcome progress has been made towards realising commitments made by international donors and host country governments to expand economic opportunities for Syrian refugees and host communities in neighbouring countries. However targets and commitments also bring new challenges, and evidence must underpin new policies.

  5. Expanded austenite; crystallography and residual stress

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Hummelshøj, Thomas Strabo; Somers, Marcel A. J.

    2009-01-01

    The identity of expanded austenite as developing during low temperature nitriding and/or carburizing of austenitic stainless steel has been under debate since the very first observation of this phase. In the present article recent results obtained with i) homogeneous samples of various uniform co...

  6. Expanded austenite, crystallography and residual stress

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Hummelshøj, Thomas Strabo; Somers, Marcel A. J.

    2010-01-01

    The identity of expanded austenite as developing during low temperature nitriding and/or carburising of austenitic stainless steel has been under debate since the very first observation of this phase. In the present article, recent results obtained with (a) homogeneous samples of various uniform ...

  7. Expanding Arts Education in a Digital Age

    Science.gov (United States)

    Choi, Haeryun; Piro, Joseph M.

    2009-01-01

    This article proposes a way to expand the study of arts education within new contexts of technology and globalization. Drawing upon theories that have informed arts and aesthetic education in the past, the authors suggest new applications for these ideas to ensure that arts education sustains its significance in twenty-first-century society. The…

  8. FDA Expands Abiraterone Approval for Prostate Cancer

    Science.gov (United States)

    The FDA has expanded the approval of abiraterone (Zytiga) to treat men with metastatic prostate cancer. The agency approved abiraterone, in combination with prednisone, for men whose cancer that is responsive to hormone-blocking treatments (also known as castration-sensitive) and is at high risk of progressing.

  9. Sulfonated graphenes catalyzed synthesis of expanded porphyrins ...

    Indian Academy of Sciences (India)

    Sulfonated graphene; expanded porphyrins; heterogeneous catalysis; solid acid; non-covalent interaction. 1. Introduction. Graphene, an important allotropic member of carbon, has received much attention owing to its interest- ing properties in material science with wide range of applications in energy devices, electronics, ...

  10. Expanding the applicability of Heallth Technology Assessments

    DEFF Research Database (Denmark)

    Draborg, Eva; Hansen, Helle Ploug

    2012-01-01

    The objective of the presentation is to expand the foundations of input into policy decision making relying on health technology assessments (HTA). HTAs are primarily based on systematic reviews (SR) and thereby mostly on randomized controlled trials (RCT). RCTs can be distinguished on a continuu...

  11. Hubble, Hubble's Law and the Expanding Universe

    Indian Academy of Sciences (India)

    Srimath

    Hubble, Hubble's Law and the Expanding Universe. J S Bagla. Jasjeet Bagla works at the. Harish-Chandra Research. Institute, Allahabad. His research is mainly on cosmology and he is interested in all areas of physics. Keywords. Cosmology, Big Bang, expan- sion of universe. H ubble's nam e is associated closely w ith ...

  12. Hubble, Hubble's Law and the Expanding Universe

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 3. Hubble, Hubble's Law and the Expanding Universe. J S Bagla. General Article Volume 14 Issue 3 March 2009 pp 216-225. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/014/03/0216-0225 ...

  13. Women Engineering Faculty: Expanding the Pipeline

    Science.gov (United States)

    Greni, Nadene Deiterman

    2006-01-01

    The purpose for this case study was to explore the features of undergraduate engineering departmental and college support that influenced the persistence of women students. Women engineering faculty members were among the participants at three Land Grant universities in the Midwest. The data revealed the theme, Expanding the Pipeline, and…

  14. CLASSICS WHY THE UNIVERSE IS EXPANDING

    Indian Academy of Sciences (India)

    accuracy, to the product of the particle velocity u and the time t: r = ut. But this is nothing other than Hubble's law of the expanding Universe. Rewriting the formula as u = (1/t)r and putting 1/t = H (Hubble's constant), we obtain u = Hr. So, the two principal similarities of a chemical explosion and the “Big Bang” are: cooling.

  15. Sulfonated graphenes catalyzed synthesis of expanded porphyrins ...

    Indian Academy of Sciences (India)

    A newer synthesis of sulfonic acid functionalized graphenes have been developed, which have been characterized, examined as heterogeneous solid acid carbocatalyst in the synthesis of selected expanded porphyrins in different reaction conditions. This environment-friendly catalyst avoids the use of toxic catalysts and ...

  16. Heptaphyrins: Expanded porphyrins with seven heterocyclic rings

    Indian Academy of Sciences (India)

    Unknown

    -mail: tkc@iitk.ac.in ... The syntheses of expanded porphyrins continue to attract the attention of chemists because of their diverse .... The aromatic nature of the heptaphyrins, 7–9, was proved by various analytical methods. The Soret-like ...

  17. Heptaphyrins: Expanded porphyrins with seven heterocyclic rings

    Indian Academy of Sciences (India)

    Unknown

    ring inversion. 1. Introduction. The syntheses of expanded porphyrins continue to attract the attention of chemists because of their diverse biological applications such as: anion receptors, photosensitizing agents, MRI contrast agents1 etc. They are also of interest, theoretically, to study the fundamental property of aromaticity ...

  18. Technical Note: Effect of Incorporating Expanded Polystyrene ...

    African Journals Online (AJOL)

    Workability which is an important property of concrete, aects the rate of placement and the degree of compaction of concrete. Inadequate compaction leads to reduction in both strength and durability of concrete. In this research work, the effect of incorporation of expanded polystyrene aggregate granules in concrete was ...

  19. Hubble, Hubble's Law and the Expanding Universe

    Indian Academy of Sciences (India)

    Srimath

    Cosmology, Big Bang, expan- sion of universe. H ubble's nam e is associated closely w ith the idea of an expanding universe as he discovered the relation between the recession velocity and the distances of galaxies. H ubble also did a lot of pioneering w ork on the distribution of galaxies in the universe. In this article we ...

  20. Properties of extruded expandable breadfruit products

    Science.gov (United States)

    Dried breadfruit was extruded with a twin screw extruder to develop a value-added expanded fruit product. This research studied the effects of barrel temperature (120-160°C), moisture content (13-25%), feeding rate (13-25 kg/h) and screw speed (115-175rpm) on physicochemical properties (bulk densit...

  1. Expanding Your Horizons Conference in Geneva

    CERN Multimedia

    Chromek-Burckhart, Doris

    2011-01-01

    CERN and its experiments participated in Expanding Your Horizons (EYH) in Science and Mathematics conference in Geneva on 12th November. EYH nurture girls' interest in science and math courses to encourage them to consider careers in science, technology, engineering, and math.

  2. Expanded Core Curriculum: 12 Years Later

    Science.gov (United States)

    Lohmeier, Keri; Blankenship, Karen; Hatlen, Phil

    2009-01-01

    This study investigated changes in teachers' and parents' understanding and implementation of or philosophy on the implementation of the content areas of the expanded core curriculum for students who are visually impaired. The results demonstrated some changes since the original survey results were reported in 1998 and a discrepancy between the…

  3. Heat expanded starch-based compositions.

    Science.gov (United States)

    Glenn, Gregory M; Klamczynski, Artur K; Holtman, Kevin M; Shey, Justin; Chiou, Bor-Sen; Berrios, Jose; Wood, Delilah; Orts, William J; Imam, Syed H

    2007-05-16

    A heat expansion process similar to that used for expanded bead polystyrene was used to expand starch-based compositions. Foam beads made by solvent extraction had the appearance of polystyrene beads but did not expand when heated due to an open-cell structure. Nonporous beads, pellets, or particles were made by extrusion or by drying and milling cooked starch slurries. The samples expanded into a low-density foam by heating 190-210 degrees C for more than 20 s at ambient pressures. Formulations containing starch (50-85%), sorbitol (5-15%), glycerol (4-12%), ethylene vinyl alcohol (EVAL, 5-15%), and water (10-20%) were studied. The bulk density was negatively correlated to sorbitol, glycerol, and water content. Increasing the EVAL content increased the bulk density, especially at concentrations higher than 15%. Poly(vinyl alcohol) (PVAL) increased the bulk density more than EVAL. The bulk density was lowest in samples made of wheat and potato starch as compared to corn starch. The expansion temperature for the starch pellets decreased more than 20 degrees C as the moisture content was increased from 10 to 25%. The addition of EVAL in the formulations decreased the equilibrium moisture content of the foam and reduced the water absorption during a 1 h soaking period.

  4. 76 FR 14746 - Surety Companies Acceptable on Federal Bonds Change in State of Incorporation; Western Bonding...

    Science.gov (United States)

    2011-03-17

    ... Fiscal Service Surety Companies Acceptable on Federal Bonds Change in State of Incorporation; Western Bonding Company; Western Insurance Company AGENCY: Financial Management Service, Fiscal Service... Bonding Company (NAIC 13191) and Western Insurance Company (NAIC 10008) have redomesticated from the state...

  5. Essays on European bond markets

    NARCIS (Netherlands)

    Cheung, Y.C.

    2005-01-01

    This dissertation focused on a number of issues that are of importance in the current European bond market. In the past years, the fiscal policy of the Eurozone members, advances in the technology of trading platforms and the introduction of a single currency have reshaped the fixed income markets

  6. Analysis of Disulfide Bond Formation

    NARCIS (Netherlands)

    Braakman, Ineke; Lamriben, Lydia; van Zadelhoff, Guus; Hebert, Daniel N.

    2017-01-01

    In this unit, protocols are provided for detection of disulfide bond formation in cultures of intact cells and in an in vitro translation system containing isolated microsomes or semi-permeabilized cells. First, the newly synthesized protein of interest is biosynthetically labeled with radioactive

  7. Bonding in ZnSb

    DEFF Research Database (Denmark)

    Bjerg, Lasse; Madsen, Georg K. H.; Iversen, Bo Brummerstedt

    of the lowest conduction band have therefore been investigated. Electrons placed in the lowest conduction band are predicted to increase the bonding between second nearest neighbour atoms. This causes a lowering of the energy at special points in the first Brillouin zone. Thereby, the dispersion of the lowest...

  8. 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,...

  9. Weld bonding of stainless steel

    DEFF Research Database (Denmark)

    Santos, I. O.; Zhang, Wenqi; Goncalves, V.M.

    2004-01-01

    This paper presents a comprehensive theoretical and experimental investigation of the weld bonding process with the purpose of evaluating its relative performance in case of joining stainless steel parts, against alternative solutions based on structural adhesives or conventional spot-welding. Th...

  10. Breaking Rules–Making Bonds

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 1. Breaking Rules - Making Bonds. A G Samuelson. General Article Volume 21 Issue 1 January 2016 pp 43- ... Author Affiliations. A G Samuelson1. Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bengaluru 560 012 ...

  11. dimensional architectures via hydrogen bonds

    Indian Academy of Sciences (India)

    Administrator

    However, the utilization of hydrogen bond supramolecular syn- thons in assembling metal–organic frameworks is relatively less explored area of research. The combi- nation of these two aspects is expected to result in more control over the network geometries and there- fore the properties. The aim of the present work is to.

  12. Refrigeration generation using expander-generator units

    Science.gov (United States)

    Klimenko, A. V.; Agababov, V. S.; Koryagin, A. V.; Baidakova, Yu. O.

    2016-05-01

    The problems of using the expander-generator unit (EGU) to generate refrigeration, along with electricity were considered. It is shown that, on the level of the temperatures of refrigeration flows using the EGU, one can provide the refrigeration supply of the different consumers: ventilation and air conditioning plants and industrial refrigerators and freezers. The analysis of influence of process parameters on the cooling power of the EGU, which depends on the parameters of the gas expansion process in the expander and temperatures of cooled environment, was carried out. The schematic diagram of refrigeration generation plant based on EGU is presented. The features and advantages of EGU to generate refrigeration compared with thermotransformer of steam compressive and absorption types were shown, namely: there is no need to use the energy generated by burning fuel to operate the EGU; beneficial use of the heat delivered to gas from the flow being cooled in equipment operating on gas; energy production along with refrigeration generation, which makes it possible to create, using EGU, the trigeneration plants without using the energy power equipment. It is shown that the level of the temperatures of refrigeration flows, which can be obtained by using the EGU on existing technological decompression stations of the transported gas, allows providing the refrigeration supply of various consumers. The information that the refrigeration capacity of an expander-generator unit not only depends on the parameters of the process of expansion of gas flowing in the expander (flow rate, temperatures and pressures at the inlet and outlet) but it is also determined by the temperature needed for a consumer and the initial temperature of the flow of the refrigeration-carrier being cooled. The conclusion was made that the expander-generator units can be used to create trigeneration plants both at major power plants and at small energy.

  13. Synthesis and Characteristics of Highly Oil-absorptive Expanded Polyurethane

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.H. [Pusan National University, Pusan (Korea); Kim, W. [Dong Ah Chem. Co. Ltd., Kyungnam (Korea); Kim, W.H. [Pusan National University, Pusan (Korea)

    2000-03-01

    Oil-absorptive expanded polyurethane (EPU) was prepared with a lypophilic polyol, polypropyleneglycol (PPG) as the soft segment, and toluenediisocyanate (TDI) and H{sub 2}O as the hard segment. PPGs having various average molecular weights (M{sub n} : 1000, 2000, 3000) were employed to investigate that the soft segment content was consequent on the oil-absorptivity and the mechanical properties of the EPUs. As M{sub n} of PPG was decreased from 3000 to 1000, the oil-absorptivity and the tensile strength of the EPUs increased from 1460 to 3010% and from 0.26 to 0.55 kg{sub f}/cm{sup 2} respectively. As the hard segment content ratio, {gamma}([NCO]/[OH]) was increased from 1.0 to 1.2, the tensile strength of the EPUs increased from 0.56 to 0.95 kg{sub f}/cm{sup 2}, due to the formation of allophanate and/or biuret bondings. However, as the surfactant (S-A) content was increased from 1.0 to 2.5 pbw, the oil-absorptivity was decreased from 3634 to 3312%, due to the formation of closed cell structures. (author). 18 refs., 4 tabs., 14 figs.

  14. Probing hydrogen bonding interactions and proton transfer in proteins

    Science.gov (United States)

    Nie, Beining

    intermediate states of proteins. Our MD simulations on the structures of photoactive yellow protein (PYP) and its photoproducts provide deep insight into the much-debated structural nature of chromophore photo-isomerization. Our simulation data of three plausible photoproducts provide a specific guide on how to use time-resolved infrared spectroscopy to identify which photoproduct is formed after photo-isomerization. Our data also indicate that hydrogen bond with Tyr42 may be crucial to increase the proton affinity of the chromophore and trigger the intra-protein proton transfer during PYP photoreceptor activation.

  15. Strength of Bond Covenants and Bond Assessment Framework

    Directory of Open Access Journals (Sweden)

    Noel Yahanpath

    2012-06-01

    Full Text Available We examine bond covenants of 29 New Zealand bond issues between 2001 and 2007.Results from the study indicate that protection provided for bondholders is weak and limited.On average, only 2-3 types of covenants are embedded with the issues and only 27% of thesecovenants provide full protection to the bondholders. However, bondholders are not compensated for taking the additional risk. We propose an alternative assessment framework that directly assesses the level of protection offered to bondholders. We calculate thecovenant quality score for the issues and classify them into four levels of protection: very high protection, moderate, low and very low. Recent legislative changes will go some way towards improving investor protection and confidence, but the effect is yet to be seen. This proposed scoring framework can be used by potential investors to complement the traditional credit ratings when making their investment decisions.

  16. Life cycle assessment of bio-based, waterborne PU adhesives for fast industrial bonding processes

    OpenAIRE

    Maga, Daniel; Melchiors, Martin; Henneken, Hartmut; Taden, Andreas

    2017-01-01

    Aqueous PU dispersion adhesives based on high molecular weight, semi-crystalline polyurethane polymers have long demonstrated their outstanding performance and are a well-established bonding technology in several industrial applications. Due to their thermal activation properties and sharp melting area, these adhesives allow for efficient bonding processes with short bond strength build-up times. State-of-the-art is the use of polyester building blocks from fossil raw material resources to sy...

  17. Anatomy of Bond Formation. Bond Length Dependence of the Extent of Electron Sharing in Chemical Bonds

    Czech Academy of Sciences Publication Activity Database

    Ponec, Robert; Cooper, D.

    2005-01-01

    Roč. 727, 1-3 (2005), s. 133-138 ISSN 0166-1280 R&D Projects: GA AV ČR(CZ) IAA4072403 Institutional research plan: CEZ:AV0Z40720504 Keywords : electron sharing * chemical bonds Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.045, year: 2005

  18. Expanding signaling-molecule wavefront model of cell polarization in the Drosophila wing primordium.

    Science.gov (United States)

    Wortman, Juliana C; Nahmad, Marcos; Zhang, Peng Cheng; Lander, Arthur D; Yu, Clare C

    2017-07-01

    In developing tissues, cell polarization and proliferation are regulated by morphogens and signaling pathways. Cells throughout the Drosophila wing primordium typically show subcellular localization of the unconventional myosin Dachs on the distal side of cells (nearest the center of the disc). Dachs localization depends on the spatial distribution of bonds between the protocadherins Fat (Ft) and Dachsous (Ds), which form heterodimers between adjacent cells; and the Golgi kinase Four-jointed (Fj), which affects the binding affinities of Ft and Ds. The Fj concentration forms a linear gradient while the Ds concentration is roughly uniform throughout most of the wing pouch with a steep transition region that propagates from the center to the edge of the pouch during the third larval instar. Although the Fj gradient is an important cue for polarization, it is unclear how the polarization is affected by cell division and the expanding Ds transition region, both of which can alter the distribution of Ft-Ds heterodimers around the cell periphery. We have developed a computational model to address these questions. In our model, the binding affinity of Ft and Ds depends on phosphorylation by Fj. We assume that the asymmetry of the Ft-Ds bond distribution around the cell periphery defines the polarization, with greater asymmetry promoting cell proliferation. Our model predicts that this asymmetry is greatest in the radially-expanding transition region that leaves polarized cells in its wake. These cells naturally retain their bond distribution asymmetry after division by rapidly replenishing Ft-Ds bonds at new cell-cell interfaces. Thus we predict that the distal localization of Dachs in cells throughout the pouch requires the movement of the Ds transition region and the simple presence, rather than any specific spatial pattern, of Fj.

  19. Scalable bonding of nanofibrous polytetrafluoroethylene (PTFE) membranes on microstructures

    Science.gov (United States)

    Mortazavi, Mehdi; Fazeli, Abdolreza; Moghaddam, Saeed

    2018-01-01

    Expanded polytetrafluoroethylene (ePTFE) nanofibrous membranes exhibit high porosity (80%-90%), high gas permeability, chemical inertness, and superhydrophobicity, which makes them a suitable choice in many demanding fields including industrial filtration, medical implants, bio-/nano- sensors/actuators and microanalysis (i.e. lab-on-a-chip). However, one of the major challenges that inhibit implementation of such membranes is their inability to bond to other materials due to their intrinsic low surface energy and chemical inertness. Prior attempts to improve adhesion of ePTFE membranes to other surfaces involved surface chemical treatments which have not been successful due to degradation of the mechanical integrity and the breakthrough pressure of the membrane. Here, we report a simple and scalable method of bonding ePTFE membranes to different surfaces via the introduction of an intermediate adhesive layer. While a variety of adhesives can be used with this technique, the highest bonding performance is obtained for adhesives that have moderate contact angles with the substrate and low contact angles with the membrane. A thin layer of an adhesive can be uniformly applied onto micro-patterned substrates with feature sizes down to 5 µm using a roll-coating process. Membrane-based microchannel and micropillar devices with burst pressures of up to 200 kPa have been successfully fabricated and tested. A thin layer of the membrane remains attached to the substrate after debonding, suggesting that mechanical interlocking through nanofiber engagement is the main mechanism of adhesion.

  20. Neutron diffraction structure investigations for expanded liquid selenium up to 14000C and 300 bar

    International Nuclear Information System (INIS)

    Edeling, M.

    1980-01-01

    The static structure factor of the expanded liquid Selenium is measured by means of the neutron diffraction for temperatures between 600 0 C and 1400 0 C and for pressures up to 300 bar. From the structure factors the pair distribution functions show that the bond length of the Selenium atoms is constant 2.37 A to 2.38 A for the whole concentration range. For temperatures above 1200 0 C the calculated intermolecular coordination number shows that the intermolecular interaction increases. (BHO)