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Sample records for comparative theoretical study

  1. A Comparative Study of Theoretical Graph Models for Characterizing Structural Networks of Human Brain

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    Xiaojin Li

    2013-01-01

    Full Text Available Previous studies have investigated both structural and functional brain networks via graph-theoretical methods. However, there is an important issue that has not been adequately discussed before: what is the optimal theoretical graph model for describing the structural networks of human brain? In this paper, we perform a comparative study to address this problem. Firstly, large-scale cortical regions of interest (ROIs are localized by recently developed and validated brain reference system named Dense Individualized Common Connectivity-based Cortical Landmarks (DICCCOL to address the limitations in the identification of the brain network ROIs in previous studies. Then, we construct structural brain networks based on diffusion tensor imaging (DTI data. Afterwards, the global and local graph properties of the constructed structural brain networks are measured using the state-of-the-art graph analysis algorithms and tools and are further compared with seven popular theoretical graph models. In addition, we compare the topological properties between two graph models, namely, stickiness-index-based model (STICKY and scale-free gene duplication model (SF-GD, that have higher similarity with the real structural brain networks in terms of global and local graph properties. Our experimental results suggest that among the seven theoretical graph models compared in this study, STICKY and SF-GD models have better performances in characterizing the structural human brain network.

  2. Comparative theoretical and experimental study on novel tri-quinoline system and its anticancer studies

    Science.gov (United States)

    Gayathri, Kasirajan; Radhika, Ramachandran; Shankar, Ramasamy; Malathi, Mahalingam; Savithiri, Krishnaswamy; Sparkes, Hazel A.; Howard, Judith A. K.; Mohan, Palathurai Subramaniam

    2017-04-01

    A novel compound 2-chloro-3,6-bis-(quinolin-8-yloxymethyl)-quinoline 3 bearing a tri-quinoline moiety has been synthesized from 2-chloro-3,6-dimethyl quinoline 1 and 8-hydroxy quinoline 2 using dry acetone and K2CO3 as a base. 3 has been characterized by using FT-IR, FT-Raman, UV-Vis, 1H NMR, 13C NMR spectra and single crystal X-ray diffraction methods. We have also made a combined experimental and theoretical study on the molecular structure, vibrational spectra, NMR, FT-IR, FT-Raman and UV-Vis spectra of 2-chloro-3,6-bis-(quinolin-8-yloxymethyl)-quinoline. The theoretical studies of the title compound have been evaluated by using density functional theory calculations using B3LYP/6-31+G(d,p) and M06-2X/6-31+G(d,p) level of theories. The calculated theoretical values were found to be in good agreement with the experimental findings. The single crystal structure 3 crystallized in the orthorhombic space group Pna21. The compound 3 exhibits higher cytotoxicity in human cervical cancer cell lines (HeLa) than human breast cancer cell lines (MCF7).

  3. Platinum adsorption on ceria: A comparative theoretical study of different surfaces

    Science.gov (United States)

    Ma, Dongwei; Li, Tingxian; Wang, Qinggao; Yang, Gui; He, Chaozheng; He, Bingling; Lu, Zhansheng; Yang, Zongxian

    2017-02-01

    A comparative study, based on the density functional theory, on the adsorption of single Pt atoms on the CeO2(111), (110), and (100) surfaces has been performed. According to the calculated adsorption energies, it is suggested that the deposited Pt atoms on the CeO2(111) surface are easy to aggregate and form nanoparticles compared with those on the CeO2(110) and (100) surfaces. Further, the interaction strength between Pt and the three CeO2 surfaces follows the order of (100) > (110) > (111). It is also found that there is a correlation between the formal oxidation state of the adsorbed Pt and its coordination number with respect to O. The Pt atom coordinated by one O atom on the CeO2 surfaces is only slightly charged and almost neutral, and that coordinately by four O atoms exclusively has the formal oxidation state of Pt2+. The possible reasons for these findings have been discussed. And the present theoretical results have been compared with the available experimental reports. It is expected that our studies will give useful insights into the shape-dependent interaction between Pt with CeO2 nanocrystals and the shape-dependent oxidation state of the deposited Pt.

  4. Theoretical investigation of manganese adsorption on graphene and graphane: A first-principles comparative study

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    AlZahrani, A.Z., E-mail: azalzahrani@kau.edu.sa [Physics department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)

    2012-03-15

    Within the framework of spin-polarized generalized gradient approximation ({sigma}GGA) of the density functional theory (DFT) and pseudopotential method, the structural, magnetic, and electronic properties of graphene and graphane upon the adsorption of manganese atoms have been theoretically investigated. In contrast to the recent results (New J. Phys. 12, 063020 (2010)), Mn atom has been found to be adsorbed on a hollow-site configuration and no appreciable indication to substitute one of the C atoms of the graphene sheet. Unlike the recent results on Mn-doped graphane (Carbon 48, 3901 (2010)), the Mn adatom prefers to adsorb on the top of a carbon atom, forming a bridge with the uppermost hydrogen atoms. The magnetic moment of the Mn-doped graphene is found to be larger than that of the Mn-doped graphane. The structural parameters and electronic properties of both Mn-doped graphene and Mn-doped graphane are determined and compared with the available data.

  5. Comparative study of two theoretical models of methane and ethane steam reforming process

    Science.gov (United States)

    Brus, Grzegorz; Kaczmarczyk Marcin Tomiczek, Robert; Mozdzierz, Marcin

    2016-09-01

    From the chemical point of view the reforming process of heavy hydrocarbons such as Associated Petroleum Gas (APG) is very complex. One of the main issue is a set of undesired chemical reactions that causes deposition of solid carbon and consequently block catalytic property of a reactor. The experimental investigation is crucial to design APG reforming reactors. However, the experiment needs to be preceded by careful thermodynamical analysis to design safe operation conditions. In case of small number of reactants and reactions such as in case of steam reforming of pure methane, the problem can be solved by treating each equilibrium reaction constant as an element of the system of non-linear equations. The system of equations can be solved by Newton-Raphson method. However in case of large number of reactants and reaction, such as in case of APG reforming this method is inefficient. A large number of strongly non-linear equations leads often to converge problem. In this paper the authors suggest to use different approach called Parametric Equation Method. In this method a system of non-linear equations is replaced by a set of single non-linear equations solved separately. The methods were used to simulate steam reforming of methane-ethane rich fuel. The results of computations from both methods were juxtaposed and comparative study were conducted. Finally safe operation conditions for steam reforming of methane-ethane fuel were calculated and presented.

  6. Theoretical and experimental comparative study of a derivative from 2-pyridinecarboxaldehyde which exhibits configurational dynamics

    Science.gov (United States)

    Gordillo, Mónica A.; Soto-Monsalve, Mónica; Gutiérrez, Gustavo; D'vries, Richard F.; Chaur, Manuel N.

    2016-09-01

    The (E)-4-nitro-N‧-(pyridine-2-ylmethylene)benzohydrazide, a derivative from 2-pyridinecarboxaldehyde, displays E/Z isomerization induced by ultraviolet radiation in which the process of photoisomerization was evidenced and followed by 1D 1H NMR. The structure of the compound was determined by FT-IR and NMR techniques and confirmed by single-crystal X-ray diffraction. The results in terms of bond angle and length, chemical shift (13C and 1H) and vibrational frequencies obtained experimentally were compared to computed values at two levels of theory (Restricted Hartree-Fock and Density Functional Theory) using different basis set. The understanding of spectroscopy and dynamic properties of these type of compounds is of importance in view of their potential use in molecular machines and electronic devices.

  7. Comparative theoretical study of adsorption of lithium polysulfides (Li2Sx) on pristine and defective graphene

    Science.gov (United States)

    Jand, Sara Panahian; Chen, Yanxin; Kaghazchi, Payam

    2016-03-01

    Adsorption of Li2Sx on pristine and defective (Stone-Wales (SW) and vacancy) graphene is studied using density functional theory. Results show that the interaction between Li2Sx and graphene is dominated by dispersion interaction (physisorption), which depends on the size of molecule as well as the existence and type of defect sites on graphene. We find that single Li2Sx molecules interact only slightly stronger to the SW sites than to the defect-free sites, but they interact very strongly with single-vacant defects. In the later cases, the vacant site catches one S atom from the Li2Sx molecule, leading to the formation of a Li2Sx-1 molecule, which adsorbs weakly on the created S-doped graphene. This study suggests that defect sites can not improve the ability of graphene to catch lithium polysulfides in Li-S batteries.

  8. COMPARATIVE STUDY BETWEEN TRADITIONAL AND ENTERPRISE RISK MANAGEMENT -A THEORETICAL APPROACH

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    Cican Simona-Iulia

    2014-07-01

    Full Text Available The complexity, volatility and unpredictability of the current economic environment are a daily reminder that organizations face many risks. The traditional approach, according to which risk is a necessary evil which must be removed, is no longer sufficient and that is why companies nowadays are forced to spend significant resources to manage risks. Risk transparency is what one looks for; therefore, identification and management of risks within an organization become increasingly necessary for success and longevity. Risk approach has a major role in a company’s ability to avoid, reduce and turn risks into opportunities. Enterprise risk management is a new concept that revolutionizes the traditional approach and summarizes risk management in an integrated, comprehensive and strategic system. Studies use several synonyms for enterprise risk management such as integrated risk management, holistic risk management, global risk management and strategic risk management. Enterprise risk management implements at the end of the last century a new way to deal with risks: the holistic approach. This risks approach – i.e. interaction of several types of risks which become increasingly threatening and varied and may cause more damage than individual risk – brings forward the need of risk management and raises issues at the highest level of company management. For a proper view on company risks, each individual risk and the possibility of risk interaction must be understood. This is essential to establish a risk classification according to their impact on the company. Traditional approach on risk management, as a management function, is limited to only threats and losses, so relatively few organizations see risks as potential earning-generated opportunities. However, risk management process is not radically changed. Enterprise risk management is an improved version of the traditional risk management, created by expanding its scope. The new risk

  9. Comparative theoretical study of the UV/Vis absorption spectra of styrylpyridine compounds using TD-DFT calculations.

    Science.gov (United States)

    Castro, Maria Eugenia; Percino, M Judith; Chapela, Victor M; Soriano-Moro, Guillermo; Ceron, Margarita; Melendez, Francisco J

    2013-05-01

    This study examined absorption properties of 2-styrylpyridine, trans-2-(m-cyanostyryl)pyridine, trans-2-[3-methyl-(m-cyanostyryl)]pyridine, and trans-4-(m-cyanostyryl)pyridine compounds based on theoretical UV/Vis spectra, with comparisons between time-dependent density functional theory (TD-DFT) using B3LYP, PBE0, and LC-ωPBE functionals. Basis sets 6-31G(d), 6-31G(d,p), 6-31+G(d,p), and 6-311+G(d,p) were tested to compare molecular orbital energy values, gap energies, and maxima absorption wavelengths. UV/Vis spectra were calculated from fully optimized geometry in B3LYP/6-311+G(d,p) in gas phase and using the IEFPCM model. B3LYP/6-311+G(d,p) provided the most stable form, a planar structure with parameters close to 2-styrylpyridine X-ray data. Isomeric structures were evaluated by full geometry optimization using the same theory level. Similar energetic values were found: ~4.5 kJ mol(-1) for 2-styrylpyridine and ~1 kJ mol(-1) for derivative compound isomers. The 2-styrylpyridine isomeric structure differed at the pyridine group N-atom position; structures considered for the other compounds had the cyano group attached to the phenyl ring m-position equivalent. The energy difference was almost negligible between m-cyano-substituted molecules, but high energy barriers existed for cyano-substituted phenyl ring torsion. TD-DFT appeared to be robust and accurate approach. The B3LYP functional with the 6-31G(d) basis set produced the most reliable λmax values, with mean errors of 0.5 and 12 nm respect to experimental values, in gas and solution, respectively. The present data describes effects on the λmax changes in the UV/Vis absorption spectra of the electron acceptor cyano substituent on the phenyl ring, the electron donor methyl substituent, and the N-atom position on the electron acceptor pyridine ring, causing slight changes respect to the 2-styrylpyridine title compound.

  10. EVOLUTION OF THEORETICAL AND METHODOLOGICAL FOUNDATIONS OF COMPARATIVE ECONOMICS

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    N. Grazhevska

    2014-12-01

    Full Text Available The article reveals the evolution stages of theoretical and methodological foundations of comparative economics. The author highlights algorithms of comparative analysis as well as theoretical and methodological limitations of four research programs of the new comparative economics. The article justifies the necessity of a comprehensive comparative study of the major trends and contradictions in the development of national economies in the era of globalization.

  11. The OH-initiated atmospheric chemical reactions of polyfluorinated dibenzofurans and polychlorinated dibenzofurans: A comparative theoretical study.

    Science.gov (United States)

    Zeng, Xiaolan; Chen, Jing; Qu, Ruijuan; Pan, Xiaoxue; Wang, Zunyao

    2017-02-01

    The atmospheric chemical reactions of some polyfluorinated dibenzofurans (PFDFs) and polychlorinated dibenzofurans (PCDFs), initiated by OH radical, were investigated by performing theoretical calculations using density functional theory (DFT) and B3LYP/6-311++G(2df,p) method. The obtained results indicate that OH addition reactions of PFDFs and PCDFs occurring at C1∼4 and CA sites are thermodynamic spontaneous changes and the branching ratio of the PF(C)DF-OH adducts is decided primarily by kinetic factor. The OH addition reactions of PFDFs taking place at fluorinated C1∼4 positions are kinetically comparable with those occurring at nonfluorinated C1∼4 positions, while OH addition reactions of PCDFs occurring at chlorinated C1∼4 sites are negligible. The total rate constants of the addition reactions of PFDFs or PCDFs become smaller with consecutive fluorination or chlorination, and substituting at C1 position has more adverse effects than substitution at other sites. The succedent O2 addition reactions of PF(C)DF-OH adducts are thermodynamic nonspontaneous processes under the atmospheric conditions, and have high Gibbs free energies of activation (ΔrG(≠)). The substituted dibenzofuranols are the primary oxidation products for PCDFs under the atmospheric conditions. However, other oxidative products may also be available for PFDFs besides substituted dibenzofuranols.

  12. Comparative antioxidant status in freshwater fish Carassius auratus exposed to six current-use brominated flame retardants: A combined experimental and theoretical study

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    Feng, Mingbao; Qu, Ruijuan; Wang, Chao; Wang, Liansheng; Wang, Zunyao, E-mail: wangzun315cn@163.com

    2013-09-15

    Highlights: •A combined experimental and theoretical approach was used for risk assessments of six BFRs in fish. •Oxidative stress biomarkers were measured for toxicity identification. •Toxicity order was proposed via the integrated biomarker response. •Theoretical calculations were performed to analyze the BFRs toxicity. -- Abstract: Decabromodiphenyl ether (BDE-209) and several non-polybrominated diphenyl ether (PBDE) brominated flame retardants (BFRs), such as tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), decabromodiphenyl ethane (DBDPE), hexabromobenzene (HBB) and pentabromotoluene (PBT), are persistent halogenated contaminants ubiquitously detected in aquatic systems. However, data on comparative toxicological effects of these BFRs are lacking for fish. In this study, a combined experimental and theoretical approach was used to compare and analyze the effects of these BFRs on biochemical biomarkers in liver of Carassius auratus injected intraperitoneally with different doses (10 and 100 mg/kg) for 7, 14 and 30 days. Oxidative stress was evoked evidently for the prolonged exposure, represented by the significantly altered indices (superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, and malondialdehyde). The integrated biomarker response (IBR) index ranked biotoxicity as: PBT > HBB > HBCD > TBBPA > BDE-209 > DBDPE. Quantum chemical calculations (electronic parameters, frontier molecular orbitals, and Wiberg bond order) were performed for theoretical analysis. Notably, some descriptors were correlated with the toxicity order, probably implying the existence of a potential structure–activity relationship when more BFRs were included. Besides, theoretical calculations also provided some valuable information regarding the molecular characteristics and metabolic pathways of these current-use BFRs, which may facilitate the understanding on their environmental behavior and fate. Overall, this study adopted a combined

  13. Comparative Study of Two Carbon Fiber Cathodes and Theoretical Analysis in Microbial Fuel Cells on Ocean Floor

    Institute of Scientific and Technical Information of China (English)

    FU Yubin; LIU Yuanyuan; XU Qian; LU Zhikai; ZHANG Yelong

    2014-01-01

    Cathode activity plays an important role in the improvement of the microbial fuel cells on ocean floor (BMFCs). A comparison study between Rayon-based (CF-R) and PAN-based carbon fiber (CF-P) cathodes is conducted in the paper. The two carbon fibers were heat treated to improve cell performance (CF-R-H&CF-P-H), and were used to build a new BMFCs structure with a foamy carbon anode. The maximum power density was 112.4 mW m-2 for CF-R-H, followed by 66.6 mW m-2 for CF-R, 49.7 mW m-2 for CF-P-H and 21.6 mW m-2 for CF-P respectively. The higher specific area and deep groove make CF-R have a better power output than with CF-P. Meanwhile, heat treatment of carbon fiber can improve cell power, nearly two-fold higher than heat treatment of plain fiber. This improvement may be due to the quinones group formation to accelerate the reduction of oxygen and electron transfer on the fiber surface in the three phase boundary after heat treatment. Compared to PAN-based carbon fiber, Rayon-based carbon fiber would be preferentially selected as cathode in novel BMFCs design due to its high surface area, low cost and higher power. The comparison research is significant for cathode material selection and cell design.

  14. Comparative Theoretical Study of the Ring-Opening Polymerization of Caprolactam vs Caprolactone Using QM/MM Methods

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    Elsasser, Brigitta M.; Schoenen, Iris; Fels, Gregor

    2013-06-07

    Candida antarctica lipase B (CALB) efficiently catalyzes the ring-opening polymerization of lactones to high molecular weight products in good yield. In contrast, an efficient enzymatic synthesis of polyamides has so far not been described in the literature. This obvious difference in enzyme catalysis is the subject of our comparative study of the initial steps of a CALB catalyzed ring-opening polymerization of ε- caprolactone and ε-caprolactam. We have applied docking tools to generate the reactant state complex and performed quantum mechanical/molecular mechanical (QM/MM) calculations at the density functional theory (DFT) PBE0 level of theory to simulate the acylation of Ser105 by the lactone and the lactam, respectively, via the corresponding first tetrahedral intermediates. We could identify a decisive difference in the accessibility of the two substrates in the ring-opening to the respective acyl enzyme complex as the attack of ε-caprolactam is hindered because of an energetically disfavored proton transfer during this part of the catalytic reaction while ε-caprolactone is perfectly processed along the widely accepted pathway using the catalytic triade of Ser105, His224, and Asp187. Since the generation of an acylated Ser105 species is the crucial step of the polymerization procedure, our results give an explanation for the unsatisfactory enzymatic polyamide formation and opens up new possibilities for targeted rational catalyst redesign in hope of an experimentally useful CALB catalyzed polyamide synthesis.

  15. Comparing Theoretical Perspectives in Describing Mathematics Departments: Complexity and Activity

    Science.gov (United States)

    Beswick, Kim; Watson, Anne; De Geest, Els

    2010-01-01

    We draw on two studies of mathematics departments in 11-18 comprehensive maintained schools in England to compare and contrast the insights provided by differing theoretical perspectives. In one study, activity theory was used to describe common features of the work of three departments. In the other, a mathematics department was viewed and…

  16. Theoretical ambiguity and the weight of historical heritage: a comparative study of the British and Norwegian electricity liberalisation

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    Midttun, Atle [Norwegian School of Management, Sandvika (Norway); Thomas, Steve [Sussex Univ., Science Policy Research Unit, Brighton (United Kingdom)

    1998-02-01

    Britain and Norway have been European pioneers in liberalising their electricity systems, but they have done so in very different ways. Both attempted to create a system in which the potentially competitive activities, generation and supply to final consumers, were opened up to market forces. However, Britain has liberalised by privatisation leaving generation largely concentrated in a few companies. Norway has maintained a dominant public ownership, but has sought to create a competitive environment through a decentralised production structure. The British `capitalist` and the Norwegian `structuralist` approach both exhibit clear market oriented features, but with the dynamics placed respectively on the ownership side and on decentralised competition. Yet the two models are also reflections of two historical heritages. The differences in political styles helps to explain the more dramatic and controversial character of the British reform as compared to the rather pragmatic Norwegian process. (author)

  17. A comparative theoretical study of CO oxidation reaction by O2 molecule over Al- or Si-decorated graphene oxide.

    Science.gov (United States)

    Esrafili, Mehdi D; Sharifi, Fahimeh; Nematollahi, Parisa

    2016-09-01

    Using density functional theory calculations, the probable CO oxidation reaction mechanisms are investigated over Al- or Si-decorated graphene oxide (GO). The equilibrium geometry and electronic structure of these metal decorated-GOs along with the O2/CO adsorption configurations are studied in detail. The relatively large adsorption energies reveal that both Al and Si atoms can disperse on GO quite stably without clustering problem. Hence, both Al- and Si-decorated GOs are stable enough to be utilized in catalytic oxidation of CO by molecular O2. The two possible reaction pathways proposed for the oxidation of CO with O2 molecule are as follows: O2+CO→CO2+Oads and CO+Oads→CO2. The estimated energy barriers of the first oxidation reaction on Si-decorated GOs, following the Eley-Rideal (ER) reaction, are lower than that on Al-decorated ones. This is most likely due to the larger atomic charge on the Si atom than the Al one, which tends to stabilize the corresponding transition state structure. The results of this study can be useful for better understanding the chemical properties of Al- and Si-decorated GOs, and are valuable for the development of an automobile catalytic converter in order to remove the toxic CO molecule.

  18. Comparative studies in education: new theoretical and methodological approaches - doi: 10.4025/actascieduc.v36i1.19012

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    Elma Júlia Gonçalves de Carvalho

    2014-02-01

    Full Text Available Comparative methodology is an extremely rich analytic tool in educational systems. Since it identifies similar and different issues, it broadens the field of analysis and understanding on the national reality when contrasted to that of other countries, especially with their public policies and their administration of education. Several theoretical and methodological issues on comparative studies are historically investigated and the new perspectives on current comparative education are indicated. Current research demonstrates that the production of a new paradigmatic perspective, highlighting the rejection of traditional national frontiers as the only or the main categories of analysis, is on the increase. On the one hand, the above-mentioned perspective invites experts to adopt international references in the analysis of educational systems and policies and, on the other hand, makes them aware of regional differences and provides them with new horizons for their investigation.

  19. Theoretical Advanced Study Institute: 2014

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    DeGrand, Thomas [Univ. of Colorado, Boulder, CO (United States)

    2016-08-17

    The Theoretical Advanced Study Institute was held at the University of Colorado, Boulder, during June 2-27, 2014. The topic was "Journeys through the Precision Frontier: Amplitudes for Colliders." The organizers were Professors Lance Dixon (SLAC) and Frank Petriello (Northwestern and Argonne). There were fifty one students. Nineteen lecturers gave sixty seventy five minute lectures. A Proceedings was published.

  20. Theoretical Studies of Reaction Surfaces

    Science.gov (United States)

    2007-11-02

    Similar levels of agreement are being found in studies of water clusters12 , the Menshutkin reaction 13 (ion separation reaction ), a prototypical SN2 ...of both reactants and products. These analyses reveal that Bery pseudorotation occurs repeatedly during the side attack, whereas the SN2 reaction H...31 Aug 97 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS AASERT93 THEORETICAL STUDIES OF REACTION SURFACES F49620-93-1-0556 3484/XS 6. AUTHOR(S) 61103D DR

  1. Linear response properties required to simulate vibrational spectra of biomolecules in various media: (R)-phenyloxirane (A comparative theoretical and spectroscopic vibrational study)

    DEFF Research Database (Denmark)

    Jalkanen, Karl J.; Jürgensen, Vibeke Würtz; Degtyarenko, I.M.

    2005-01-01

    in understanding the photo induced chemical reactivity observed in many systems. This work is a continuation of our goal to interpret the results of experimental studies on the basis of theoretical results, which can help to understand the structure and function of proteins, other biomolecules and ligands...... in their native environments. As the physical tools used to observe and study biological processes have evolved, so have the theoretical methods and models to interpret, understand and completely utilize the results of these new measurements. The work on developing methods for modeling amino acids, peptides...

  2. Theoretical Studies of Silicon Chemistry

    Science.gov (United States)

    1990-02-01

    Molecular and Electronic Structure of Silyl Nitrene , M.S. Gordon, Chem. Phys. Lett., 146, 148 (1988). 18. A Theoretical Study of the Three-Membered Rings...phase and crystal structures. Of course, all three possibilities may contribute. B. The Electronic and Molecular Structure of Silyl Nitrene , M.S...a silaimine. An interesting question regarding the primary process is whether the silyl nitrene , R3SiN, is formed as an intermediate. As a first step

  3. Theoretical modeling of RF ablation with internally cooled electrodes: comparative study of different thermal boundary conditions at the electrode-tissue interface.

    Science.gov (United States)

    Rivera, María J; Molina, Juan A López; Trujillo, Macarena; Berjano, Enrique J

    2009-07-01

    Previous studies on computer modeling of RF ablation with cooled electrodes modeled the internal cooling circuit by setting surface temperature at the coolant temperature (i.e., Dirichlet condition, DC). Our objective was to compare the temperature profiles computed from different thermal boundary conditions at the electrode-tissue interface. We built an analytical one-dimensional model based on a spherical electrode. Four cases were considered: A) DC with uniform initial condition, B) DC with pre-cooling period, C) Boundary condition based on Newton's cooling law (NC) with uniform initial condition, and D) NC with a pre-cooling period. The results showed that for a long time (120 s), the profiles obtained with (Cases B and D) and without (Cases A and C) considering pre-cooling are very similar. However, for shorter times ( 30 s), Cases A and C overestimated the temperature at points away from the electrode-tissue interface. In the NC cases, this overestimation was more evident for higher values of the convective heat transfer coefficient (h). Finally, with NC, when h was increased the temperature profiles became more similar to those with DC. The results suggest that theoretical modeling of RF ablation with cooled electrodes should consider: 1) the modeling of a pre-cooling period, especially if one is interested in the thermal profiles registered at the beginning of RF application; and 2) NC rather than DC, especially for low flow in the internal circuit.

  4. Theoretical Advanced Study Institute: 2014

    Energy Technology Data Exchange (ETDEWEB)

    DeGrand, Thomas [Univ. of Colorado, Boulder, CO (United States)

    2016-08-17

    The Theoretical Advanced Study Institute (TASI) was held at the University of Colorado, Boulder, during June 2-27, 2014. The topic was "Journeys through the Precision Frontier: Amplitudes for Colliders." The organizers were Professors Lance Dixon (SLAC) and Frank Petriello (Northwestern and Argonne). There were fifty-one students. Nineteen lecturers gave sixty seventy-five minute lectures. A Proceedings was published. This TASI was unique for its large emphasis on methods for calculating amplitudes. This was embedded in a program describing recent theoretical and phenomenological developments in particle physics. Topics included introductions to the Standard Model, to QCD (both in a collider context and on the lattice), effective field theories, Higgs physics, neutrino interactions, an introduction to experimental techniques, and cosmology.

  5. Theoretical studies of combustion dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bowman, J.M. [Emory Univ., Atlanta, GA (United States)

    1993-12-01

    The basic objectives of this research program are to develop and apply theoretical techniques to fundamental dynamical processes of importance in gas-phase combustion. There are two major areas currently supported by this grant. One is reactive scattering of diatom-diatom systems, and the other is the dynamics of complex formation and decay based on L{sup 2} methods. In all of these studies, the authors focus on systems that are of interest experimentally, and for which potential energy surfaces based, at least in part, on ab initio calculations are available.

  6. THEORETICAL ASPECTS OF FILMMUSIC STUDY

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    Egorova Tatiana K.

    2014-04-01

    Full Text Available In this article, author analyzes the theoretical aspects of the film music study taking into account with modern realities in the development of world film-process and attempts to its scientific understanding. Need for innovation in this area is long overdue, because the existing on this topic nonfiction no longer meets the new aesthetic and art-practical achievements and innovations in the film music development at the XXI century. Related to the phenomenon of music in screen arts a number of new terms and concepts require a certain adjustment as well. Their range of action is not yet fully defined. Author of the article offered her version of their content-semantic interpretation (largely experimental designed to promote new research methods for the film music study.

  7. Comparing theoretical models of our galaxy with observations

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    Johnston K.V.

    2012-02-01

    Full Text Available With the advent of large scale observational surveys to map out the stars in our galaxy, there is a need for an efficient tool to compare theoretical models of our galaxy with observations. To this end, we describe here the code Galaxia, which uses efficient and fast algorithms for creating a synthetic survey of the Milky Way, and discuss its uses. Given one or more observational constraints like the color-magnitude bounds, a survey size and geometry, Galaxia returns a catalog of stars in accordance with a given theoretical model of the Milky Way. Both analytic and N-body models can be sampled by Galaxia. For N-body models, we present a scheme that disperses the stars spawned by an N-body particle, in such a way that the phase space density of the spawned stars is consistent with that of the N-body particles. The code is ideally suited to generating synthetic data sets that mimic near future wide area surveys such as GAIA, LSST and HERMES. In future, we plan to release the code publicly at http://galaxia.sourceforge.net. As an application of the code, we study the prospect of identifying structures in the stellar halo with future surveys that will have velocity information about the stars.

  8. Theoretical Studies of Proton Radioactivity

    Institute of Scientific and Technical Information of China (English)

    Ldia S Ferreira; Enrico Maglione

    2016-01-01

    In the paper, we will discuss the most recent theoretical approaches developed by our group, to understand the mechanisms of decay by one proton emission, and the structure and shape of exotic nuclei at the limits of stability.

  9. Theoretical Studies of Nanocluster Formation

    Science.gov (United States)

    2016-05-26

    5f. WORK UNIT NUMBER Q188 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NO. Air Force Research...For presentation at AFOSR Molecular Dynamics and Theoretical Chemistry Program Review; Arlington, VA (25 May 2016) PA Case Number: #16215; Clearance...Approved for public release; Distribution Unlimited. PA Clearance No: 16215 This briefing contains information up to: 2 Outline 1. Introduction

  10. Studies in theoretical particle physics

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, D.B.

    1991-07-01

    This proposal focuses on research on three distinct areas of particle physics: (1) Nonperturbative QCD. I tend to continue work on analytic modelling of nonperturbative effects in the strong interactions. I have been investigating the theoretical connection between the nonrelativistic quark model and QCD. The primary motivation has been to understand the experimental observation of nonzero matrix elements involving current strange quarks in ordinary matter -- which in the quark model has no strange quark component. This has led to my present work on understanding constituent (quark model) quarks as collective excitations of QCD degrees of freedom. (2) Weak Scale Baryogenesis. A continuation of work on baryogenesis in the early universe from weak interactions. In particular, an investigation of baryogenesis occurring during the weak phase transition through anomalous baryon violating processes in the standard model of weak interactions. (3) Flavor and Compositeness. Further investigation of a new mechanism that I recently discovered for dynamical mass generation for fermions, which naturally leads to a family hierarchy structure. A discussion of recent past work is found in the next section, followed by an outline of the proposed research. A recent publication from each of these three areas is attached to this proposal.

  11. Graph theoretical similarity approach to compare molecular electrostatic potentials.

    Science.gov (United States)

    Marín, Ray M; Aguirre, Nestor F; Daza, Edgar E

    2008-01-01

    In this work we introduce a graph theoretical method to compare MEPs, which is independent of molecular alignment. It is based on the edit distance of weighted rooted trees, which encode the geometrical and topological information of Negative Molecular Isopotential Surfaces. A meaningful chemical classification of a set of 46 molecules with different functional groups was achieved. Structure--activity relationships for the corticosteroid binding affinity (CBG) of 31 steroids by means of hierarchical clustering resulted in a clear partitioning in high, intermediate, and low activity groups, whereas the results from quantitative structure--activity relationships, obtained from a partial least-squares analysis, showed comparable or better cross-validated correlation coefficients than the ones reported for previous methods based solely in the MEP.

  12. Theoretical studies of unconventional superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Groensleth, Martin Sigurd

    2008-07-01

    This thesis presents four research papers. In the first three papers we have derived analytical results for the transport properties in unconventional superconductors and ferromagnetic systems with multiple broken symmetries. In Paper I and parts of Paper II we have studied tunneling transport between two non-unitary ferromagnetic spin-triplet superconductors, and found a novel interplay between ferromagnetism and superconductivity manifested in the Josephson effect as a spin- and charge-current in the absence of an applied voltage across the junction. The critical amplitudes of these currents can be adjusted by the relative magnetization direction on each side of the junction. Furthermore, in Paper II, we have found a way of controlling a spin-current between two ferromagnets with spin-orbit coupling. Paper III considers a junction consisting of a ferromagnet and a non-unitary ferromagnetic superconductor, and we show that the conductance spectra contains detailed information about the superconducting gaps and pairing symmetry of the Cooper-pairs. In the last paper we present a Monte Carlo study of an effective Hamiltonian describing orbital currents in the CuO2 layers of high-temperature superconductive cuprates. The model features two intrinsically anisotropic Ising models, coupled through an anisotropic next-nearest neighbor interaction, and an Ashkin-Teller nearest neighbor fourth order coupling. We have studied the specific heat anomaly, as well as the anomaly in the staggered magnetization associated with the orbital currents and its susceptibility. We have found that in a limited parameter regime, the specific heat anomaly is substantially suppressed, while the susceptibility has a non-analytical peak across the order-disorder transition. The model is therefore a candidate for describing the breakup of hidden order when crossing the pseudo-gap line on the under-doped side in the phase diagram of high-temperature superconductors. (Author) 64 refs., figs

  13. Theoretical Study of Dinoflagellate Bioluminescence.

    Science.gov (United States)

    Wang, Ming-Yu; Liu, Ya-Jun

    2017-03-01

    Dinoflagellates are the most ubiquitous luminescent protists in the marine environment and have drawn much attention for their crucial roles in marine ecosystems. Dinoflagellate bioluminescence has been applied in underwater target detection. The luminescent system of dinoflagellates is a typical luciferin-luciferase one. However, the excited-state oxyluciferin is not the light emitter of dinoflagellate bioluminescence as in most luciferin-luciferase bioluminescent organisms. The oxyluciferin of bioluminescent dinoflagellates is not fluorescent, whereas its luciferin emits bright fluorescence with similar wavelength of the bioluminescence. What is the light emitter of dinoflagellate bioluminescence and what is the chemical process of the light emission like? These questions have not been answered by the limited experimental evidence so far. In this study, for the first time, the density functional calculation is employed to investigate the geometries and properties of luciferin and oxyluciferin of bioluminescent dinoflagellate. The calculated results agree with the experimental observations and indicate the luciferin or its analogue, rather than oxyluciferin, is the bioluminophore of dinoflagellate bioluminescence. A rough mechanism involving energy transfer is proposed for dinoflagellate bioluminescence.

  14. Theoretical biology: Comparing models of species abundance - Brief Communications Arising

    NARCIS (Netherlands)

    Chave, J.; Alonso, D.; Etienne, R.S.

    2006-01-01

    Ecologists are struggling to explain how so many tropical tree species can coexist in tropical forests, and several empirical studies have demonstrated that negative density dependence is an important mechanism of tree-species coexistence1, 2. Volkov et al.3 compare a model incorporating negative de

  15. Theoretical studies of chemical reaction dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Schatz, G.C. [Argonne National Laboratory, IL (United States)

    1993-12-01

    This collaborative program with the Theoretical Chemistry Group at Argonne involves theoretical studies of gas phase chemical reactions and related energy transfer and photodissociation processes. Many of the reactions studied are of direct relevance to combustion; others are selected they provide important examples of special dynamical processes, or are of relevance to experimental measurements. Both classical trajectory and quantum reactive scattering methods are used for these studies, and the types of information determined range from thermal rate constants to state to state differential cross sections.

  16. CO oxidation on gold nanoparticles: Theoretical studies

    DEFF Research Database (Denmark)

    Remediakis, Ioannis; Lopez, Nuria; Nørskov, Jens Kehlet

    2005-01-01

    We present a summary of our theoretical results regarding CO oxidation on both oxide-supported and isolated gold nanoparticles. Using Density Functional Theory we have studied the adsorption of molecules and the oxidation reaction of CO on gold clusters. Low-coordinated sites on the gold...

  17. Theoretical aspects of studying the migration processes

    Directory of Open Access Journals (Sweden)

    Dilfuza Rasulova

    2010-02-01

    Full Text Available In conditions of continuous growth of population in Uzbekistan the issue of managing the labor migration processes is becoming more important. Effective coordination of migration processes requires comprehensive study of theory and methodology of labour migration, particularly considering cases of transition countries. The paper considers some theoretic concepts that seem important for understanding the mechanism of migration princesses, suggests practical recommendations for the associated decision-making.

  18. Theoretical study on single-molecule spectroscopy

    Institute of Scientific and Technical Information of China (English)

    SHAN Guang-cun; HUANG Wei

    2006-01-01

    The photon-by-photon approach for single molecule spectroscopy experiments utilizes the information carried by each detected photon and allows the measurements of conformational fluctuation with time resolution on a vast range of time scales,where each photon represents a data point.Here,we theoretically simulate the photon emission dynamics of a single molecule spectroscopy using the kinetic Monte Carlo algorithm to understand the underlying complex photon dynamic process of a single molecule.In addition,by following the molecular process in real time,the mechanism of complex biochemical reactions can be revealed.We hope that this theoretical study will serve as an introduction and a guideline into this exciting new field.

  19. Theoretical study on a water muffler

    Science.gov (United States)

    Du, T.; Chen, Y. W.; Miao, T. C.; Wu, D. Z.

    2016-05-01

    Theoretical computation on a previously studied water muffler is carried out in this article. Structure of the water muffler is composed of two main parts, namely, the Kevlar- reinforced rubber tube and the inner-noise-reduction structure. Rubber wall of the rubber tube is assumed to function as rigid wall lined with sound absorption material and is described by a complex radial wave number. Comparison among the results obtained from theoretical computation, FEM (finite element method) simulation and experiment of the rubber tube and that of the water muffler has been made. The theoretical results show a good accordance in general tendency with the FEM simulated and the measured results. After that, parametric study on the diameter of the inner structure and that of the rubber tube is conducted. Results show that the diameter of the left inner structure has the most significant effect on the SPL of the water muffler due to its location and its effect on the diameter ratio D2/D1.

  20. CO oxidation on gold nanoparticles: Theoretical studies

    DEFF Research Database (Denmark)

    Remediakis, Ioannis; Lopez, Nuria; Nørskov, Jens Kehlet

    2005-01-01

    We present a summary of our theoretical results regarding CO oxidation on both oxide-supported and isolated gold nanoparticles. Using Density Functional Theory we have studied the adsorption of molecules and the oxidation reaction of CO on gold clusters. Low-coordinated sites on the gold...... nanoparticles can adsorb small inorganic molecules such as O2 and CO, and the presence of these sites is the key factor for the catalytic properties of supported gold nanoclusters. Other contributions, induced by the presence of the support, can provide parallel channels for the reaction and modulate the final...

  1. Comparative Packaging Study

    Science.gov (United States)

    Perchonok, Michele; Antonini, David

    2008-01-01

    This viewgraph presentation describes a comparative packaging study for use on long duration space missions. The topics include: 1) Purpose; 2) Deliverables; 3) Food Sample Selection; 4) Experimental Design Matrix; 5) Permeation Rate Comparison; and 6) Packaging Material Information.

  2. Theoretical study on spherical proton emission

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The proton radioactivity half-lives of spherical proton emitters are investigated within a generalized liquid drop model(GLDM),including the proximity effects between nuclei in a neck and the mass and charge asymmetry.The penetrability is calculated in the WKB approximation and the assault frequency is estimated by the quantum mechanism method considering the structure of the parent nucleus.The spectroscopic factor is taken into account in half-life calculation,which is obtained by employing the relativistic mean field(RMF) theory.The half-lives within the GLDM are compared with the experimental data and other theoretical values.The results show that the GLDM works quite well for spherical proton emitters when the assault frequency is estimated by the quantum mechanical method and the spectroscopic factor is considered.

  3. Theoretical study on spherical proton emission

    Institute of Scientific and Technical Information of China (English)

    ZHANG HongFei; WANG YongJia; DONG JianMin; LI JunQing

    2009-01-01

    The proton radioactivity half-lives of spherical proton emitters are investigated within a generalized liquid drop model (GLDM),including the proximity effects between nuclei in a neck and the mass and charge asymmetry.The penetrability is calculated in the WKB approximation and the assault frequency is estimated by the quantum mechanism method considering the structure of the parent nucleus.The spectroscopic factor is taken into account in half-life calculation,which is obtained by employing the relativistic mean field (RMF) theory.The half-lives within the GLDM are compared with the experimental data and other theoretical values.The results show that the GLDM works quite well for spherical proton emitters when the assault frequency is estimated by the quantum mechanical method and the spectroscopic factor is considered.

  4. Theoretical pluralism in psychoanalytic case studies.

    Science.gov (United States)

    Willemsen, Jochem; Cornelis, Shana; Geerardyn, Filip M; Desmet, Mattias; Meganck, Reitske; Inslegers, Ruth; Cauwe, Joachim M B D

    2015-01-01

    The aim of this study is to provide an overview of the scientific activity of different psychoanalytic schools of thought in terms of the content and production of case studies published on ISI Web of Knowledge. Between March 2013 and November 2013, we contacted all case study authors included in the online archive of psychoanalytic and psychodynamic case studies (www.singlecasearchive.com) to inquire about their psychoanalytic orientation during their work with the patient. The response rate for this study was 45%. It appears that the two oldest psychoanalytic schools, Object-relations psychoanalysis and Ego psychology or "Classical psychoanalysis" dominate the literature of published case studies. However, most authors stated that they feel attached to two or more psychoanalytic schools of thought. This confirms that the theoretical pluralism in psychoanalysis stretches to the field of single case studies. The single case studies of each psychoanalytic school are described separately in terms of methodology, patient, therapist, or treatment features. We conclude that published case studies features are fairly similar across different psychoanalytic schools. The results of this study are not representative of all psychoanalytic schools, as some do not publish their work in ISI ranked journals.

  5. Theoretical Study on Standing Wave Thermoacoustic Engine

    Science.gov (United States)

    Kalra, S.; Desai, K. P.; Naik, H. B.; Atrey, M. D.

    Applications of thermoacoustic engines are not limited to driving pulse tube cryocoolers. The performance of a thermoacoustic engine is governed by various design parameters like type of resonator, stack geometry, frequency, type of working gas etc. and various operating parameters like heat input, charging pressure etc. It is very important to arrive at an optimum configuration of the engine for which a theoretical model is required. In the present work, a theoretical analysis, based on linear acoustic theory of a standing wave type half wavelength thermoacoustic engine is carried out using DeltaEC software. The system dimensions like length of resonator, stack, hot and cold heat exchangers are fixed with a helium-argon mixture as the working gas and a parallel plate type stack. Later on, two plate spacings, corresponding to helium-argon mixture and nitrogen gas, are used for carrying out analysis with helium, argon, nitrogen, carbon dioxide and helium-argon mixture as working gases of the system. The effect of charging pressure on the performance of the system is studied in terms of resonating frequency, onset temperature, pressure amplitude, acoustic power and efficiency. The conclusions derived from the analysis are reported in the paper.

  6. Theoretical study of rock mass investigation efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Holmen, Johan G.; Outters, Nils [Golder Associates, Uppsala (Sweden)

    2002-05-01

    The study concerns a mathematical modelling of a fractured rock mass and its investigations by use of theoretical boreholes and rock surfaces, with the purpose of analysing the efficiency (precision) of such investigations and determine the amount of investigations necessary to obtain reliable estimations of the structural-geological parameters of the studied rock mass. The study is not about estimating suitable sample sizes to be used in site investigations.The purpose of the study is to analyse the amount of information necessary for deriving estimates of the geological parameters studied, within defined confidence intervals and confidence level In other words, how the confidence in models of the rock mass (considering a selected number of parameters) will change with amount of information collected form boreholes and surfaces. The study is limited to a selected number of geometrical structural-geological parameters: Fracture orientation: mean direction and dispersion (Fisher Kappa and SRI). Different measures of fracture density (P10, P21 and P32). Fracture trace-length and strike distributions as seen on horizontal windows. A numerical Discrete Fracture Network (DFN) was used for representation of a fractured rock mass. The DFN-model was primarily based on the properties of an actual fracture network investigated at the Aespoe Hard Rock Laboratory. The rock mass studied (DFN-model) contained three different fracture sets with different orientations and fracture densities. The rock unit studied was statistically homogeneous. The study includes a limited sensitivity analysis of the properties of the DFN-model. The study is a theoretical and computer-based comparison between samples of fracture properties of a theoretical rock unit and the known true properties of the same unit. The samples are derived from numerically generated boreholes and surfaces that intersect the DFN-network. Two different boreholes are analysed; a vertical borehole and a borehole that is

  7. Theoretical studies on aerosol agglomeration processes

    Energy Technology Data Exchange (ETDEWEB)

    Lehtinen, K.E.J. [VTT Energy, Espoo (Finland). Energy Use

    1997-12-31

    In this thesis, theoretical modeling of certain aerosol systems has been presented. At first, the aerosol general dynamic equation is introduced, along with a discretization routine for its numerical solution. Of the various possible phenomena affecting aerosol behaviour, this work is mostly focused on aerosol agglomeration. The fundamentals of aerosol agglomeration theory are thus briefly reviewed. The two practical applications of agglomeration studied in this thesis are flue gas cleaning using an electrical agglomerator and nanomaterial synthesis with a free jet reactor. In an electrical agglomerator the aerosol particles are charged and brought into an alternating electric field. The aim is to remove submicron particles from flue gases by collisions with larger particles before conventional gas cleaning devices that have a clear penetration window in the problematic 0.1-1{mu}m size range. A mathematical model was constructed to find out the effects of the different system parameters on the agglomerator`s performance. A crucial part of this task was finding out the collision efficiencies of particles of varying size and charge. The original idea was to use unipolar charging of the particles, and a laboratory scale apparatus was constructed for this purpose. Both theory and experiments clearly show that significant removal of submicron particles can not be achieved by such an arrangement. The theoretical analysis further shows that if the submicron particles and the large collector particles were charged with opposite polarity, significant removal of the submicron particles could be obtained. The second application of agglomeration considered in this thesis is predicting/controlling nanoparticle size in the gas-to-particle aerosol route to material synthesis. In a typical material reactor, a precursor vapor reacts to form molecules of the desired material. In a cooling environment, a particulate phase forms, the dynamics of which are determined by the rates of

  8. Theoretical studies on kinetics of singlet oxygen in nonthermal plasma

    Science.gov (United States)

    Frolov, Mikhail P.; Ionin, Andrei A.; Kotkov, Andrei A.; Kochetov, Igor V.; Napartovich, Anatolii P.; Podmarkov, Yurii P.; Seleznev, Leonid V.; Sinitsyn, Dmitrii V.; Vagin, Nikolai P.; Yuryshev, Nikolay N.

    2004-09-01

    An idea to replace singlet delta oxygen (SDO) generator working with wet chemistry by electric discharge generator has got much attention last years. Different kinds of discharge were examined for this purpose, but without a great success. The existing theoretical models are not validated by well-characterized experimental data. To describe complicated kinetics in gas discharge with oxygen one needs to know in detail processes involving numerous electronic excited oxygen molecules and atoms. To gain new knowledge about these processes experimental studies were made on electric discharge properties in gas mixture flow with independent control of inlet SDO concentration. The theoretical model extended to include minor additives like oxygen atoms, water molecules, ozone was developed. Comparison with careful experimental measurements of electric characteristics along with gas composition allows us to verify the model and make theoretical predictions more reliable. Results of numerical simulations using this model for an electron-beam sustained discharge are reported and compared with the experimental data.

  9. Studies In Theoretical High Energy Particle Physics

    Energy Technology Data Exchange (ETDEWEB)

    Keung, Wai Yee [Univ. of Illinois, Chicago, IL (United States)

    2017-07-01

    This is a final technical report for grant no. DE-SC0007948 describing research activities in theoretical high energy physics at University of Illinois at Chicago for the whole grant period from July 1, 2012 to March 31, 2017.

  10. Theoretical Study of a Spherical Plasma Focus

    Science.gov (United States)

    Ay, Yasar

    A theoretical model is developed for two concentric electrodes spherical plasma focus device in order to investigate the plasma sheath dynamics, radiative emission, and the ion properties. The work focuses on the model development of the plasma sheath dynamics and its validation, followed by studying of the radiation effects and the beam-ion properties in such unique geometry as a pulsed source for neutrons, soft and hard x-rays, and electron and ion beams. Chapter 1 is an introduction on fusion systems including plasma focus. Chapter 2 is an extensive literature survey on plasma focus modeling and experiments including the various radiations and their mechanism. Chapter 3 details modeling and validation of the plasma sheath dynamics model with comparison between hydrogen, deuterium, tritium and deuterium-tritium mixture for the production of pulsed neutrons. Chapter 4 is a study of the radiative phase, in which neutron yield is investigated, as well as the predicted beam-ion properties. Chapter 5 summarizes and discusses the results. Chapter 6 provides concluding remarks and proposed future works. The phases of the developed model are the rundown phase I, rundown phase II, the reflected phase and a radiative phase. The rundown phase I starts immediately after the completion of the gas breakdown and ends when the current sheath reaches the equator point of the spherical shape. Then immediately followed by rundown phase II to start and it ends when the shock front hits the axis, which is the beginning of the reflected shock phase. Reflected shock front moves towards the incoming current sheath and meets it which is both the end of the reflected shock phase and the beginning of the radiative phase. After the reflected shock front and the current sheath meet, the current sheath continues to move radially inward by compressing the produced plasma column until it reaches the axis. Since the discharge current contains important information about the plasma dynamic

  11. Operations dashboard: comparative study

    Science.gov (United States)

    Ramly, Noor Nashriq; Ismail, Ahmad Zuhairi; Aziz, Mohd Haris; Ahmad, Nurul Haszeli

    2011-10-01

    In this present days and age, there are increasing needs for companies to monitor application and infrastructure health. Apart from having proactive measures to secure their application and infrastructure, many see monitoring dashboards as crucial investment in disaster preparedness. As companies struggle to find the best solution to cater for their needs and interest for monitoring their application and infrastructure's health, this paper summarizes the studies made on several known off-the-shelf operations dashboard and in-house developed dashboard. A few criteria of good dashboard are collected from previous studies carried out by several researchers and rank them according to importance and business needs. The finalized criteria that will be discussed in later sections are data visualization, performance indicator, dashboard personalization, audit capability and alert/ notification. Comparative studies between several popular dashboards were then carried out to determine whether they met these criteria that we derived from the first exercise. The findings hopefully can be used to educate and provide an overview of selecting the best IT application and infrastructure operations dashboard that suit business needs, thus become the main contribution of this paper.

  12. Theoretical Studies in Elementary Particle Physics

    Energy Technology Data Exchange (ETDEWEB)

    Collins, John C.; Roiban, Radu S

    2013-04-01

    This final report summarizes work at Penn State University from June 1, 1990 to April 30, 2012. The work was in theoretical elementary particle physics. Many new results in perturbative QCD, in string theory, and in related areas were obtained, with a substantial impact on the experimental program.

  13. Voltammetry at porous electrodes: A theoretical study

    CERN Document Server

    Barnes, Edward O; Li, Peilin; Compton, Richard G

    2014-01-01

    Theory is presented to simulate both chronoamperometry and cyclic voltammetry at porous electrodes fabricated by means of electro-deposition around spherical templates. A theoretical method to extract heterogeneous rate constants for quasireversible and irreversible systems is proposed by the approximation of decoupling of the diffusion within the porous electrode and of bulk diffusion to the electrode surface.

  14. Theoretic Study of CⅡ Recombination Line

    Institute of Scientific and Technical Information of China (English)

    彭永伦; 王民盛; 韩小英; 李家明

    2004-01-01

    Using the R-matrix method, we carry out theoretical calculations for recombination line λ 8794 A(3d'-3p') of CⅡ, which is important to estimate the abundances of carbon in planetary nebulae. Our calculations are based on three sets of target orbital basis, through which we elucidate the electron correlation and static polarization effects in the dielectronic recombination processes.

  15. Comparative waste forms study

    Energy Technology Data Exchange (ETDEWEB)

    Wald, J.W.; Lokken, R.O.; Shade, J.W.; Rusin, J.M.

    1980-12-01

    A number of alternative process and waste form options exist for the immobilization of nuclear wastes. Although data exists on the characterization of these alternative waste forms, a straightforward comparison of product properties is difficult, due to the lack of standardized testing procedures. The characterization study described in this report involved the application of the same volatility, mechanical strength and leach tests to ten alternative waste forms, to assess product durability. Bulk property, phase analysis and microstructural examination of the simulated products, whose waste loading varied from 5% to 100% was also conducted. The specific waste forms investigated were as follows: Cold Pressed and Sintered PW-9 Calcine; Hot Pressed PW-9 Calcine; Hot Isostatic Pressed PW-9 Calcine; Cold Pressed and Sintered SPC-5B Supercalcine; Hot Isostatic pressed SPC-5B Supercalcine; Sintered PW-9 and 50% Glass Frit; Glass 76-68; Celsian Glass Ceramic; Type II Portland Cement and 10% PW-9 Calcine; and Type II Portland Cement and 10% SPC-5B Supercalcine. Bulk property data were used to calculate and compare the relative quantities of waste form volume produced at a spent fuel processing rate of 5 metric ton uranium/day. This quantity ranged from 3173 L/day (5280 Kg/day) for 10% SPC-5B supercalcine in cement to 83 L/day (294 Kg/day) for 100% calcine. Mechanical strength, volatility, and leach resistance tests provide data related to waste form durability. Glass, glass-ceramic and supercalcine ranked high in waste form durability where as the 100% PW-9 calcine ranked low. All other materials ranked between these two groupings.

  16. Using Graph and Vertex Entropy to Compare Empirical Graphs with Theoretical Graph Models

    Directory of Open Access Journals (Sweden)

    Tomasz Kajdanowicz

    2016-09-01

    Full Text Available Over the years, several theoretical graph generation models have been proposed. Among the most prominent are: the Erdős–Renyi random graph model, Watts–Strogatz small world model, Albert–Barabási preferential attachment model, Price citation model, and many more. Often, researchers working with real-world data are interested in understanding the generative phenomena underlying their empirical graphs. They want to know which of the theoretical graph generation models would most probably generate a particular empirical graph. In other words, they expect some similarity assessment between the empirical graph and graphs artificially created from theoretical graph generation models. Usually, in order to assess the similarity of two graphs, centrality measure distributions are compared. For a theoretical graph model this means comparing the empirical graph to a single realization of a theoretical graph model, where the realization is generated from the given model using an arbitrary set of parameters. The similarity between centrality measure distributions can be measured using standard statistical tests, e.g., the Kolmogorov–Smirnov test of distances between cumulative distributions. However, this approach is both error-prone and leads to incorrect conclusions, as we show in our experiments. Therefore, we propose a new method for graph comparison and type classification by comparing the entropies of centrality measure distributions (degree centrality, betweenness centrality, closeness centrality. We demonstrate that our approach can help assign the empirical graph to the most similar theoretical model using a simple unsupervised learning method.

  17. Theoretical study on stability of hybrid bilayers

    Science.gov (United States)

    Silva, Thiago S.; de Lima Bernardo, Bertúlio; Azevedo, Sèrgio

    2015-04-01

    Motivated by the recent experimental realization of the hybrid nanostructure of graphene and boron nitride (h-BN) sheet, and studies of gap modulation by strain, we use first principles calculations based on density functional theory to investigate the effects of strain in hybrid bilayers composed of two monolayers of graphene with a nanodomain of {{B}3}{{N}3}. The calculations were made with two different approximations for the functional exchange-correlation, GGA and VDW-DF. We investigate the modification in the electronic structure and structural properties of various configurations of the hybrid bilayers. Among the configurations, those with Bernal stacking are found to be more stable when compared to the others. Studies of the compressive strain influence were made only in the structure that has been shown to be the most stable. We have found that the two approximations used in the calculations exhibit the same results for the electronic properties of all structures. The opening of the energy gap due to strain was possible in the calculations by using the GGA approximation, but the same does not happen in the calculations using the VDW-DF approximation. Our analysis shows that the VDW-DF approximation is better suited for studies involving surfaces.

  18. Vapor Sensing Theoretical Study on Optical Microcavities

    Institute of Scientific and Technical Information of China (English)

    ZHANG Le-xin; ZHANG Ran; LI Zhi-quan

    2007-01-01

    When the organic vapors absorbed to the surface of porous silicon(PS), capillary condensation takes place due to the porous structure of the PS layer, accordingly resulting in the effective refractive index changing. For PS multi-layer microcavities, the different resonant peaks shift in the reflectivity spectrum of porous silicon microcavities(PSMs). The optical sensing model is set up by applying Bruggeman effective medium approximation theory, capillary condensation process and transfer matrix theoretically analytical method of one-dimensional photonic crystals. At the same time, comprehensively researched on are the sensing characteristics of PSMs which are exposed to give concentration organic vapors. At last, made is the theoretical simulation for sensing model of the PSMs in case of saturation by using computer numerical calculation, and found is the linearity relation between the refractive index of organic solvent and the peak-shift. At the same time deduced is the peak-shift as a function of the concentration of ethanol vapors.

  19. Theoretical study of conjugated porphyrin polymers

    DEFF Research Database (Denmark)

    Pedersen, T.G.; Lynge, T.B.; Kristensen, P.K.

    2005-01-01

    The optical gap of conjugated triply linked porphyrin chains is exceptionally low (similar to 0.5 eV). Hence, such chains are candidates for organic infrared detectors and solar cells harvesting the infrared part of the solar spectrum. However, a low exciton binding energy is required for these a......The optical gap of conjugated triply linked porphyrin chains is exceptionally low (similar to 0.5 eV). Hence, such chains are candidates for organic infrared detectors and solar cells harvesting the infrared part of the solar spectrum. However, a low exciton binding energy is required...... for these applications. From a theoretical analysis of excitons in long metalloporphyrin chains, we demonstrate that the binding energy is much lower than in usual conjugated polymers. Our calculated absorption spectra are in good agreement with measurements. (c) 2004 Elsevier B.V. All rights reserved....

  20. Theoretical study of the NO beta system

    Science.gov (United States)

    Langhoff, Stephen R.; Partridge, Harry; Bauschlicher, Charles W., Jr.; Komornicki, Andrew

    1991-01-01

    A theoretical determination of the transition moment functions (TMFs) for the beta system of NO is presented. High levels of correlation treatment are required to show the changing degree of Rydberg character in the B2II with decreasing r values. The state-averaged complete-active-space self-consistent-field multireference configuration-interaction method is used for the determination. Previous lifetime measurements made with laser-induced fluorescence, varying between 2 and 0.85 microns, are discussed in terms of the calculated lifetimes for v-prime values 0-6, which vary from 2.12-1.17 microns. When larger r values are used for the transition moment function, the calculated lifetimes correlate with experimental lifetimes. The Einstein coefficients agree with experimental results, although limitations in the calibration of the spectrometer can account for systematic differences. The correlation with earlier experimental results suggests that radiative lifetimes are in the range of 1-2 microns.

  1. Theoretical studies of ionic conductivity of crosslinked chitosan membranes

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, Ernesto Lopez [Programa de Ingenieria Molecular y Nuevos Materiales, Universidad Autonoma de la Ciudad de Mexico, Fray Servando Teresa de Mier 92, 1er. Piso, Col Centro, Mexico D.F. CP 06080 (Mexico); Oviedo-Roa, R.; Contreras-Perez, Gustavo; Martinez-Magadan, Jose Manuel [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas Norte 152, Col. San Bartolo Atepehuacan, CP 07730 Mexico D.F. (Mexico); Castillo-Alvarado, F.L. [Escuela Superior de Fisica y Matematicas del Instituto Politecnico Nacional, Edificio 9 de la UPALM, Colonia Lindavista, Mexico D.F. CP 07738 (Mexico)

    2010-11-15

    Ionic conductivity of crosslinked chitosan membranes was studied using techniques of molecular modeling and simulation. The COMPASS force field was used. The simulation allows the description of the mechanism of ionic conductivity along the polymer matrix. The theoretical results obtained are compared with experimental results for chitosan membranes. The analysis suggests that the conduction mechanism is portrayed by the overlapping large Polaron tunneling model. In addition, when the chitosan membrane was crosslinked with an appropriate degree of crosslinking its ionic conductivity, at room temperature, was increased by about one order of magnitude. The chitosan membranes can be used as electrolytes in solid state batteries, electric double layer capacitors and fuel cells. (author)

  2. A comparative study of the DR reactions of c-C{sub 3}H{sup +}{sub 3} and l-C{sub 3}H{sup +}{sub 3}: Preliminary theoretical studies

    Energy Technology Data Exchange (ETDEWEB)

    Talbi, D [Universite Montpellier II - GRAAL, CNRS - UMR 5024, place Eugene Bataillon, 34095 Montpellier (France); Hickman, A P; Kashinski, D; Malenda, R F [Department of Physics, Lehigh University, 16 Memorial Dr. E, Bethlehem, PA, 18015 (United States); Redondo, P, E-mail: Dahbia.Talbi@graal.univ-montp2.f, E-mail: aph2@lehigh.ed [Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Valladolid, 47005 Valladolid (Spain)

    2009-11-15

    Preliminary calculations related to the dissociative recombination (DR) of electrons with C{sub 3}H{sup +}{sub 3} have been carried out. Both the linear and cyclic isomers of this ion exist in the interstellar medium, and accurate DR rate constants for both isomers are needed for astrophysical models. The electronic structure calculations reported here yield quasi-diabatic potential energy curves that can be used to assess the efficiency of dissociation of a CH bond. The calculations confirm a favorable position of a dissociative state for the cyclic isomer and suggest that dissociation of the linear isomer is less probable. More detailed dynamical studies are planned, and a normal mode analysis of the vibrational modes of C{sub 3}H{sup +}{sub 3} is reported as the first step in that direction.

  3. A Comparative Study of Teaching Comparative Education

    OpenAIRE

    2007-01-01

    The purpose of this paper is to characterize the comparative education subjects offered in different programs in different foreign universities. As a subject, comparative education has not been firmly institutionalized in education programs in Japanese universities. There was a movement which aimed at making comparative education as one of the mandatory subjects in the teacher training program, however it was not successful. To date, comparative education subject has been offered in various p...

  4. Theoretical & Experimental Studies of Elementary Particles

    Energy Technology Data Exchange (ETDEWEB)

    McFarland, Kevin

    2012-10-04

    Abstract High energy physics has been one of the signature research programs at the University of Rochester for over 60 years. The group has made leading contributions to experimental discoveries at accelerators and in cosmic rays and has played major roles in developing the theoretical framework that gives us our ``standard model'' of fundamental interactions today. This award from the Department of Energy funded a major portion of that research for more than 20 years. During this time, highlights of the supported work included the discovery of the top quark at the Fermilab Tevatron, the completion of a broad program of physics measurements that verified the electroweak unified theory, the measurement of three generations of neutrino flavor oscillations, and the first observation of a ``Higgs like'' boson at the Large Hadron Collider. The work has resulted in more than 2000 publications over the period of the grant. The principal investigators supported on this grant have been recognized as leaders in the field of elementary particle physics by their peers through numerous awards and leadership positions. Most notable among them is the APS W.K.H. Panofsky Prize awarded to Arie Bodek in 2004, the J.J. Sakurai Prizes awarded to Susumu Okubo and C. Richard Hagen in 2005 and 2010, respectively, the Wigner medal awarded to Susumu Okubo in 2006, and five principal investigators (Das, Demina, McFarland, Orr, Tipton) who received Department of Energy Outstanding Junior Investigator awards during the period of this grant. The University of Rochester Department of Physics and Astronomy, which houses the research group, provides primary salary support for the faculty and has waived most tuition costs for graduate students during the period of this grant. The group also benefits significantly from technical support and infrastructure available at the University which supports the work. The research work of the group has provided educational opportunities

  5. Theoretical Studies of Hydrogen Storage Alloys.

    Energy Technology Data Exchange (ETDEWEB)

    Jonsson, Hannes

    2012-03-22

    Theoretical calculations were carried out to search for lightweight alloys that can be used to reversibly store hydrogen in mobile applications, such as automobiles. Our primary focus was on magnesium based alloys. While MgH{sub 2} is in many respects a promising hydrogen storage material, there are two serious problems which need to be solved in order to make it useful: (i) the binding energy of the hydrogen atoms in the hydride is too large, causing the release temperature to be too high, and (ii) the diffusion of hydrogen through the hydride is so slow that loading of hydrogen into the metal takes much too long. In the first year of the project, we found that the addition of ca. 15% of aluminum decreases the binding energy to the hydrogen to the target value of 0.25 eV which corresponds to release of 1 bar hydrogen gas at 100 degrees C. Also, the addition of ca. 15% of transition metal atoms, such as Ti or V, reduces the formation energy of interstitial H-atoms making the diffusion of H-atoms through the hydride more than ten orders of magnitude faster at room temperature. In the second year of the project, several calculations of alloys of magnesium with various other transition metals were carried out and systematic trends in stability, hydrogen binding energy and diffusivity established. Some calculations of ternary alloys and their hydrides were also carried out, for example of Mg{sub 6}AlTiH{sub 16}. It was found that the binding energy reduction due to the addition of aluminum and increased diffusivity due to the addition of a transition metal are both effective at the same time. This material would in principle work well for hydrogen storage but it is, unfortunately, unstable with respect to phase separation. A search was made for a ternary alloy of this type where both the alloy and the corresponding hydride are stable. Promising results were obtained by including Zn in the alloy.

  6. Friendship in Latin American Social Comparative Studies

    Directory of Open Access Journals (Sweden)

    Agnaldo Garcia

    2016-06-01

    Full Text Available Friendship has been traditionally investigated in the field of interpersonal relationships using different theoretical frameworks and approaches. This paper discusses the possibility of investigating friendship from a comparative Latin American perspective, based on a wide literature review on the subject. Based on the theoretical proposals of Hinde (1997 for the investigation of interpersonal relationships, the paper considers that friendship involves several levels of complexity and affects and is affected by distinct dimensions of Latin American society. The paper recognizes that comparative studies have placed the importance of friends and friendship in areas such as economy, health, education, and migration, among others. As expected, Latin American comparative studies are more frequent in some disciplines, mainly those based on censuses data, and theoretically related to social-economic and demographic concepts, including social networks and social capital. The possibility of developing a Latin American perspective for the study of friendship requires not only the need of empirical but also theoretical advances, as well as scientific cooperation and innovation. Friendship is seen as relevant for the constitution of the social tissue of Latin American society, being affected and affecting different areas and levels. In the social economic dimension, friends are relevant, specifically in Latin America, to themes such as poverty and social vulnerability. Some future possibilities for investigation are discussed.

  7. Theoretical study of inhomogeneous plasma turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Yagi, Masatoshi; Itoh, Sanae-I. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics; Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan); Fukuyama, Atsushi [Kyoto Univ. (Japan). Dept. of Nuclear Engineering

    2000-07-01

    A hierarchy of models, i.e., (1) a model with many degrees of freedom, (2) a model with intermediate degrees of freedom, (3) a model with a few degrees of freedom is considered to understand the nature of turbulence. Results obtained from models of different levels are compared and characteristics of the interchange mode turbulence such as chaotic nature, cascade and statistical expression are discussed. (author)

  8. Measuring health lifestyles in a comparative analysis: theoretical issues and empirical findings.

    Science.gov (United States)

    Abel, T

    1991-01-01

    The concept of lifestyle bears great potential for research in medical sociology. Yet, weaknesses in current methods have restrained lifestyle research from realizing its full potentials. The present focus is on the links between theoretical conceptions and their empirical application. The paper divides into two parts. The first part provides a discussion of basic theoretical and methodological issues. In particular selected lines of thought from Max Weber are presented and their usefulness in providing a theoretical frame of reference for health lifestyle research is outlined. Next, a theory guided definition of the subject matter is introduced and basic problems in empirical applications of theoretical lifestyle concepts are discussed. In its second part the paper presents findings from comparative lifestyle analyses. Data from the U.S. and West Germany are utilized to explore issues of measurement equivalence and theoretical validity. Factor analyses indicate high conceptual equivalence for new measures of health lifestyle dimensions in both the U.S. and West Germany. Divisive cluster analyses detect three distinct lifestyle groups in both nations. Implications for future lifestyle research are discussed.

  9. A Theoretical Study of Subsurface Drainage Model Simulation of ...

    African Journals Online (AJOL)

    A Theoretical Study of Subsurface Drainage Model Simulation of Drainage Flow and ... of subsurface drain spacing, evapotranspiration and irrigation water quality on ... The study was carried out on a conceptual uniform homogenous irrigated ...

  10. Theoretical Studies Of Small Boson Clusters

    CERN Document Server

    Chen, Y

    2005-01-01

    This work uses the DVR method to study the vibrational states of small boson clusters. With the adiabatic hyperspherical approximation, the lower and upper bounds of the bound states of the helium trimer are calculated. The first fully converged 3-dimensional basis set variational calculation for this system is carried out using Pekeris coordinates and the Laguerre basis functions. Two bound states are found for the system, as well as a third state which might be an Efimov state. The same method is used to study the bound states and resonance states of the neon trimer using a realistic potential, and proved to be efficient and accurate.

  11. Theoretical Studies of Long Lived Plasma Structures

    CERN Document Server

    Dvornikov, Maxim

    2010-01-01

    We construct the model of a long lived plasma structure based on spherically symmetric oscillations of electrons in plasma. Oscillations of electrons are studied in frames of both classical and quantum approaches. We obtain the density profile of electrons and the dispersion relations for these oscillations. The differences between classical and quantum approaches are discussed. Then we study the interaction between electrons participating in spherically symmetric oscillations. We find that this interaction can be attractive and electrons can form bound states. The applications of the obtained results to the theory of natural plasmoids are considered.

  12. A Theoretical Study of Leading Edge Noise

    Science.gov (United States)

    2008-05-01

    measurements of the noise radiated from a number of different airfoils made as -part of a companion study at Virginia lech . It was concluded that the...vectors in the direction normal to the local flow velocity and in the spanwise direction respectively. The transport equation for the vorticity is

  13. Theoretical and Experimental Studies in Reactive Scattering.

    Science.gov (United States)

    1986-08-11

    containing He and the neutral beam formed, cleansed of ions by appropriate electrostatic deflection plates, is reionized in a second charge exchange...H3 (having D3h symmetry) which could therefore support bound states. The technique of neutralization and reionization of H’ in order to study H 3 was...technique has been used again recently by Gaillard and co-workers 7 . By placing an electric field between the neutralization and reionization gas cells they

  14. Theoretical study of pair density wave superconductors

    Science.gov (United States)

    Zheng, Zhichao

    In conventional superconductors, the Cooper pairs are formed from quasiparticles. We explore another type of superconducting state, a pair density wave (PDW) order, which spontaneously breaks some of the translational and point group symmetries. In a PDW superconductor, the order parameter is a periodic function of the center-of-mass coordinate, and the spatial average value of the superconducting order parameter vanishes. In the early 1960s, following the success of the BCS theory of superconductivity, Fulde and Ferrell and Larkin and Ovchinnikov (FFLO) developed theories of inhomogeneous superconducting states. Because of this Zeeman splitting in a magnetic field, the Cooper pairs having a nonzero center-of-mass momentum are more stable than the normal pairing, leading to the FFLO state. Experiments suggest possible occurrence of the FFLO state in the heavy-fermion compound CeCoIn5, and in quasi-low-dimensional organic superconductors. FFLO phases have also been argued to be of importance in understanding ultracold atomic Fermi gases and in the formation of color superconductivity in high density quark matter. In all Fermi superfluids known at the present time, Cooper pairs are composed of particles with spin 1/2. The spin component of a pair wave function can be characterized by its total spin S = 0 (singlet) and S = 1 (triplet). In the discovered broken inversion superconductors CePt3Si, Li2Pt3B, and Li2Pd3B, the magnetic field leads to novel inhomogeneous superconducting states, namely the helical phase and the multiple-q phase. Its order parameter exhibits periodicity similar to FFLO phase, and the consequences of both phases are same: the enhancement of transition temperature as a function of magnetic field. We have studied the PDW phases in broken parity superconductors with vortices included. By studying PDW vortex states, we find the usual Abrikosov vortex solution is unstable against a new solution with fractional vortex pairs. We have also studied the

  15. Theoretical Studies of Solids under Extreme Conditions.

    Science.gov (United States)

    1983-12-01

    C. Pattnaik, Phys. Rev. 1327, 3987 (1983). 9. M. E. Schabes , J. L. Fry and P. C. Pattnaik, Bull. 4I. Phys. Soc. 29, 76 (1984). 10. C. M. Varma et al...phonon interactions in transition metals," P. C. Pattnaik, M. E. Schabes and J. L. Fry,to be submitted to The Physical Review. 10. "A Study of the linear...C. Pattnaik, J. L. Fry and M. E. Schabes . 13. "Positron work functions in metallic alloys," P. C. Pattnaik and G. Fletcher (to be submitted to The

  16. Theoretical studies on nitrogen rich energetic azoles.

    Science.gov (United States)

    Ghule, Vikas Dasharath; Sarangapani, Radhakrishnan; Jadhav, Pandurang M; Tewari, Surya P

    2011-06-01

    Different nitro azole isomers based on five membered heterocyclics were designed and investigated using computational techniques in order to find out the comprehensive relationships between structure and performances of these high nitrogen compounds. Electronic structure of the molecules have been calculated using density functional theory (DFT) and the heat of formation has been calculated using the isodesmic reaction approach at B3LYP/6-31G* level. All designed compounds show high positive heat of formation due to the high nitrogen content and energetic nitro groups. The crystal densities of these energetic azoles have been predicted with different force fields. All the energetic azoles show densities higher than 1.87 g/cm(3). Detonation properties of energetic azoles are evaluated by using Kamlet-Jacobs equation based on the calculated densities and heat of formations. It is found that energetic azoles show detonation velocity about 9.0 km/s, and detonation pressure of 40GPa. Stability of the designed compounds has been predicted by evaluating the bond dissociation energy of the weakest C-NO(2) bond. The aromaticity using nucleus independent chemical shift (NICS) is also explored to predict the stability via delocalization of the π-electrons. Charge on the nitro group is used to assess the impact sensitivity in the present study. Overall, the study implies that all energetic azoles are found to be stable and expected to be the novel candidates of high energy density materials (HEDMs).

  17. Experimental and theoretical study of reflux condensation

    Energy Technology Data Exchange (ETDEWEB)

    Bakke, Knut

    1997-12-31

    This thesis studies the separation of gas mixtures in a reflux condenser. also called a dephlegmator. Reflux condensation is separation of a gas mixture, in reflux flow with condensing liquid, under continuous heat removal. A numerical model of a dephlegmator for binary mixtures was developed. The model may readily be extended to multi-component mixtures, as the solution method is based on a matrix solver. Separation of a binary mixture in a reflux condenser test rig is demonstrated. The test facility contains a single-tube test section that was designed and built as part of the project. Test mixtures of propane and n-butane were used, and a total of 15 experiments are reported. Limited degree of separation was achieved due to limited heat transfer area and narrow boiling point range of the test mixture. The numerical model reproduces the experimental data within reasonable accuracy. Deviation between calculated and measured properties is less than 6% of the measured temperature and less than 5% of the measured flow rate. The model is based on mechanistic models of physical processes and is not calibrated or tuned to fit the experimental data. The numerical model is applied to a number of separation processes. These case studies show that the required heat transfer area increases rapidly with increments in top product composition (light component). Flooding limits the amount of reflux liquid. The dephlegmator is suitable for separation of feed mixtures that are rich in light components. The gliding temperature in the dephlegmation process enables utilization of top product as refrigerant, with subsequent energy saving as a result. 61 refs., 50 figs., 34 tabs.

  18. Theoretical Studies in Percolation and Polymer Theory

    Science.gov (United States)

    Wu, Kang

    We study the theta points for the self-avoiding walk (SAW) and the self-avoiding trail (SAT). In a small cell real space renormalization group study on a model that includes self-attracting SAW's (SASAW) and self-attracting SAT's (SASAT) as special cases, we find distinct fixed points for the SASAW and SASAT collapse transitions, and so conclude that these transitions are in different universality classes. A percolation model, which we call bond percolation on antipercolation clusters (BPAPC), is introduced. A mapping between BPAPC and the diluted alternating Potts model (DAPM) is established. We solve the DAPM in the Bethe cluster approximation and obtain the static critical exponents beta = 1 and gamma = 1. The approximate phase diagram for arbitrary coordination number z is also constructed. In our Monte Carlo simulations of kinetic antipercolation, we observe growth oscillations that have no analog in regular percolation. A mean field theory that explains the existence of these oscillations is presented. The result of our simulations suggests that kinetic antipercolation may be in the same universality class as kinetic percolation. We introduce a dynamic fuse model for the damage done to a current-carrying polycrystalline metal thin film by electromigration. We determine the exact scaling behavior of the crack tip velocity for a single crack oriented perpendicularly to the direction of the ambient current. For any value of the initial density of defects, the mean failure time is to an excellent approximation proportional to the average length of the shortest path across the film in a certain metric. This conclusion is supported by our simulations and by analytical work based on a variational formulation of our problem. The Green's function formulation (GFF) is obtained for a random resistor network. The GFF yields a linear system equivalent to Kirchhoff's laws but with a smaller number of variables. We present the technical details of solving the GFF linear

  19. Theoretical Studies of Homogeneous Catalysts Mimicking Nitrogenase

    Directory of Open Access Journals (Sweden)

    Alessandra Magistrato

    2011-01-01

    Full Text Available The conversion of molecular nitrogen to ammonia is a key biological and chemical process and represents one of the most challenging topics in chemistry and biology. In Nature the Mo-containing nitrogenase enzymes perform nitrogen ‘fixation’ via an iron molybdenum cofactor (FeMo-co under ambient conditions. In contrast, industrially, the Haber-Bosch process reduces molecular nitrogen and hydrogen to ammonia with a heterogeneous iron catalyst under drastic conditions of temperature and pressure. This process accounts for the production of millions of tons of nitrogen compounds used for agricultural and industrial purposes, but the high temperature and pressure required result in a large energy loss, leading to several economic and environmental issues. During the last 40 years many attempts have been made to synthesize simple homogeneous catalysts that can activate dinitrogen under the same mild conditions of the nitrogenase enzymes. Several compounds, almost all containing transition metals, have been shown to bind and activate N2 to various degrees. However, to date Mo(N2(HIPTN3N with (HIPTN3N= hexaisopropyl-terphenyl-triamidoamine is the only compound performing this process catalytically. In this review we describe how Density Functional Theory calculations have been of help in elucidating the reaction mechanisms of the inorganic compounds that activate or fix N2. These studies provided important insights that rationalize and complement the experimental findings about the reaction mechanisms of known catalysts, predicting the reactivity of new potential catalysts and helping in tailoring new efficient catalytic compounds.

  20. Theoretical study of cisplatin adsorption on silica

    Energy Technology Data Exchange (ETDEWEB)

    Simonetti, S., E-mail: ssimonet@uns.edu.ar [Departamento de Fisica and IFISUR, Universidad Nacional del Sur-CONICET, Av. Alem 1253, 8000 Bahia Blanca (Argentina); Departamentos de Ciencias Basicas e Ingenieria Mecanica, Universidad Tecnologica Nacional, 11 de Abril 461, 8000 Bahia Blanca (Argentina); Company, A. Diaz; Brizuela, G.; Juan, A. [Departamento de Fisica and IFISUR, Universidad Nacional del Sur-CONICET, Av. Alem 1253, 8000 Bahia Blanca (Argentina)

    2011-11-15

    The adsorption of cisplatin and its complexes, cis-[PtCl(NH{sub 3}){sub 2}]{sup +} and cis-[Pt(NH{sub 3}){sub 2}]{sup 2+}, on a SiO{sub 2}(1 1 1) hydrated surface has been studied by the Atom Superposition and Electron Delocalization method. The adiabatic energy curves for the adsorption of the drug and its products on the delivery system were considered. The electronic structure and bonding analysis were also performed. The molecule-surface interactions are formed at expenses of the OH surface bonds. The more important interactions are the Cl-H bond for cis-[PtCl{sub 2}(NH{sub 3}){sub 2}] and cis-[PtCl(NH{sub 3}){sub 2}]{sup +} adsorptions, and the Pt-O interaction for cis-[Pt(NH{sub 3}){sub 2}]{sup 2+} adsorption. The Cl p orbitals and Pt s, p y d orbitals of the molecule and its complexes, and the s H orbital and, the s and p orbitals of the O atoms of the hydrated surface are the main contribution to the surface bonds.

  1. Theoretical and Experimental Studies in Accelerator Physics

    Energy Technology Data Exchange (ETDEWEB)

    Rosenzweig, James [Univ. of California, Los Angeles, CA (United States). Dept. of Physics and Astronomy

    2017-03-08

    . We note also that PBPL graduates remain as close elaborators for the program after leaving UCLA. The UCLA PBPL program is a foremost developer of on-campus facilities, such as the Neptune and Pegasus Laboratories, providing a uniquely strong environment for student-based research. In addition, the PBPL is a strong user of off-campus national lab facilities, such as SLAC FACET and NLCTA, and the BNL ATF. UCLA has also vigorously participated in the development of these facilities. The dual emphases on off- and on-campus opportunities permit the PBPL to address in an agile way a wide selection of cutting-edge research topics. The topics embraced by this proposal illustrate this program aspect well. These include: GV/m dielectric wakefield acceleration/coherent Cerenkov radiation experiments at FACET (E-201) and the ATF; synergistic laser-excited dielectric accelerator and light source development; plasma wakefield (PWFA) experiments on “Trojan horse” ionization injection (FACET E-210), quasi-nonlinear PWFA at BNL and the production at Neptune high transformer ratio plasma wakes; the inauguration of a new type of RF photoinjector termed “hybrid” at UCLA, and application to PWFA; space-charge dominated beam and cathode/near cathode physics; the study of advanced IFEL systems, for very high energy gain and utilization of novel OAM modes; the physcis of inverse Compton scattering (ICS), with applications to e+ production and γγ colliders; electron diffraction; and advanced beam diagnostics using coherent imaging techniques. These subjects are addressed under the leadership of PBPL director Prof. James Rosenzweig in Task A, and Prof. Pietro Musumeci in Task J, which was initiated following his OHEP Outstanding Junior Investigator award.

  2. Experimental and theoretical study of Rayleigh-Lamb wave propagation

    Science.gov (United States)

    Rogers, Wayne P.; Datta, Subhendu K.; Ju, T. H.

    1990-01-01

    Many space structures, such as the Space Station Freedom, contain critical thin-walled components. The structural integrity of thin-walled plates and shells can be monitored effectively using acoustic emission and ultrasonic testing in the Rayleigh-Lamb wave frequency range. A new PVDF piezoelectric sensor has been developed that is well suited to remote, inservice nondestructive evaluation of space structures. In the present study the new sensor was used to investigate Rayleigh-Lamb wave propagation in a plate. The experimental apparatus consisted of a glass plate (2.3 m x 25.4 mm x 5.6 mm) with PVDF sensor (3 mm diam.) mounted at various positions along its length. A steel ball impact served as a simulated acoustic emission source, producing surface waves, shear waves and longitudinal waves with dominant frequencies between 1 kHz and 200 kHz. The experimental time domain wave-forms were compared with theoretical predictions of the wave propagation in the plate. The model uses an analytical solution for the Green's function and the measured response at a single position to predict response at any other position in the plate. Close agreement was found between the experimental and theoretical results.

  3. Comparing simulated and theoretical sampling distributions of the U3 person-fit statistic

    NARCIS (Netherlands)

    Emons, W.H.M.; Meijer, R.R.; Sijtsma, K.

    2002-01-01

    The accuracy with which the theoretical sampling distribution of van der Flier's person-.t statistic U3 approaches the empirical U3 sampling distribution is affected by the item discrimination. A simulation study showed that for tests with a moderate or a strong mean item discrimination, the Type I

  4. Theoretical Studies of Elementary Hydrocarbon Species and Their Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Wesley D. [Univ. of Georgia, Athens, GA (United States). Dept. of Chemistry. Center for Computational Quantum Chemistry; Schaefer, III, Henry F. [Univ. of Georgia, Athens, GA (United States). Dept. of Chemistry. Center for Computational Quantum Chemistry

    2015-11-14

    This is the final report of the theoretical studies of elementary hydrocarbon species and their reactions. Part A has a bibliography of publications supported by DOE from 2010 to 2016 and Part B goes into recent research highlights.

  5. EXPERIMENTAL AND THEORETICAL NMR STUDY OF 4-(1 ...

    African Journals Online (AJOL)

    Preferred Customer

    3 Department of Physics, Arts and Science Faculty, Dumlupınar University, Kütahya, Turkey. 4 Department ... been studied experimentally and theoretically using nuclear magnetic resonance (NMR) spectroscopy. 1H, 13C, ... INTRODUCTION.

  6. Theoretical study of pulsed microwave discharge in nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Bonaventura, Z; Trunec, D; Mesko, M; Vasina, P; Kudrle, V [Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic)

    2005-11-15

    A pulsed microwave discharge burning in pure nitrogen was studied theoretically. The time-dependent Boltzmann equation for electrons was solved numerically in multi-term approximation. It was assumed that the discharge was ignited by a 100 kW microwave (f = 9.4 GHz) pulses with 2.5 {mu}s duration; the repetition frequency was 400 Hz. It was shown that the electron distribution function approaches very quickly the steady state distribution function after a change of the amplitude of electric field intensity. The steady state time averaged values of electron mean energy, diffusion and rate coefficients and drift velocity were calculated for different values of electric field intensity. With these values the actual values of electric field intensity from a previous experiment were determined from the measured time dependence of electron concentration. The calculated values were compared with previous experimental results.

  7. A Comparative Study on Error Analysis

    DEFF Research Database (Denmark)

    Wu, Xiaoli; Zhang, Chun

    2015-01-01

    Title: A Comparative Study on Error Analysis Subtitle: - Belgian (L1) and Danish (L1) learners’ use of Chinese (L2) comparative sentences in written production Xiaoli Wu, Chun Zhang Abstract: Making errors is an inevitable and necessary part of learning. The collection, classification and analysis...... the occurrence of errors either in linguistic or pedagogical terms. The purpose of the current study is to demonstrate the theoretical and practical relevance of error analysis approach in CFL by investigating two cases - (1) Belgian (L1) learners’ use of Chinese (L2) comparative sentences in written production....... Finally, pedagogical implication of CFL is discussed and future research is suggested. Keywords: error analysis, comparative sentences, comparative structure ‘‘bǐ - 比’, Chinese as a foreign language (CFL), written production...

  8. Experimental and theoretical study on hollow-cone spray

    Science.gov (United States)

    Chang, Keh-Chin; Wang, Muh-Rong; Wu, Wen-Jing; Hong, Chia-Hong

    1993-02-01

    A theoretical and experimental investigation has been conducted to study the two-phase turbulent structure in an isothermal hollow-cone spray. Mean and fluctuating velocity components, drop number density, as well as drop-size distribution were measured with a nonintrusive diagnostic tool, a two-component phase Doppler particle analyzer. Complete initial conditions required for theoretical calculations were also provided with measurements. Theoretical calculations were made with an Eulerian-Lagrangian formulism. Turbulent dispersion effects were numerically simulated using a Monte Carlo method. Turbulence modulation effects were also taken into account in the modeling. The well-defined experimental data were used to assess the accuracy of the resultant Eulerian-Lagrangian model. Comparisons showed that the theoretical predictions, based upon the Eulerian-Lagrangian model, yielded reasonable agreement with the experimental data. The improvements made by inclusion of the selected turbulence modulation model were insignificant in this work.

  9. A single theoretical framework for circular features processing in humans: orientation and direction of motion compared

    Directory of Open Access Journals (Sweden)

    Tzvetomir eTzvetanov

    2012-05-01

    Full Text Available Common computational principles underly processing of various visual features in the cortex. They are considered to create similar patterns of contextual modulations in behavioral studies for different features as orientation and direction of motion. Here, I studied the possibility that a single theoretical framework, implemented in different visual areas, of circular feature coding and processing could explain these similarities in observations. Stimuli were created that allowed direct comparison of the contextual effects on orientation and motion direction with two different psychophysical probes: changes in weak and strong signal perception. One unique simplified theoretical model of circular feature coding including only inhibitory interactions, and decoding through standard vector average, successfully predicted the similarities in the two domains, while different feature population characteristics explained well the differences in modulation on both experimental probes. These results demonstrate how a single computational principle underlies processing of various features across the cortices.

  10. Studies of Chinese speakers with dysarthria: informing theoretical models.

    Science.gov (United States)

    Whitehill, Tara L

    2010-01-01

    Most theoretical models of dysarthria have been developed based on research using individuals speaking English or other Indo-European languages. Studies of individuals with dysarthria speaking other languages can allow investigation into the universality of such models, and the interplay between language-specific and language-universal aspects of dysarthria. In this article, studies of Cantonese- and Mandarin-Chinese speakers with dysarthria are reviewed. The studies focused on 2 groups of speakers: those with cerebral palsy and those with Parkinson's disease. Key findings are compared with similar studies of English speakers. Since Chinese is tonal in nature, the impact of dysarthria on lexical tone has received considerable attention in the literature. The relationship between tone [which involves fundamental frequency (F(0)) control at the syllable level] and intonation (involving F(0) control at the sentential level) has received more recent attention. Many findings for Chinese speakers with dysarthria support earlier findings for English speakers, thus affirming the language-universal aspect of dysarthria. However, certain differences, which can be attributed to the distinct phonologies of Cantonese and Mandarin, highlight the language-specific aspects of the condition.

  11. Theoretical study of the adsorption of benzene on coinage metals

    Directory of Open Access Journals (Sweden)

    Werner Reckien

    2014-08-01

    Full Text Available The adsorption of benzene on the M(111, M(100 and M(110 surfaces of the coinage metals copper (M = Cu, silver (M = Ag and gold (M = Au is studied on the basis of density functional theory (DFT calculations with an empirical dispersion correction (D3. Variants of the Perdew–Burke–Ernzerhof functionals (PBE, RPBE and RevPBE in combination with different versions of the dispersion correction (D3 and D3(BJ are compared. PBE-D3, PBE-D3(BJ and RPBE-D3 give similar results which exhibit a good agreement with experimental data. RevPBE-D3 and RevPBE-D3(BJ tend to overestimate adsorption energies. The inclusion of three-center terms (PBE-D3(ABC leads to a slightly better agreement with the experiment in most cases. Vertical adsorbate–substrate distances are calculated and compared to previous theoretical results. The observed trends for the surfaces and metals are consistent with the calculated adsorption energies.

  12. Piezoelectricity in quasicrystals: A group-theoretical study

    Indian Academy of Sciences (India)

    K Rama Rao; P Hemagiri Rao; B S K Chaitanya

    2007-03-01

    Group-theoretical methods have been accepted as exact and reliable tools in studying the physical properties of crystals and quasicrystalline materials. By group representation theory, the maximum number of non-vanishing and independent second- order piezoelectric coefficients required by the seven pentagonal and two icosahedral point groups - that describe the quasicrystal symmetry groups in two and three dimensions - is determined. The schemes of non-vanishing and independent second-order piezoelectric tensor components needed by the nine point groups with five-fold rotations are identified and tabulated employing a compact notation. The results of this group-theoretical study are briefly discussed.

  13. Diffusion in liquids a theoretical and experimental study

    CERN Document Server

    Tyrrell, H J V

    1984-01-01

    Diffusion in Liquids: A Theoretical and Experimental Study aims to discuss the principles, applications, and advances in the field of diffusion, thermal diffusion, and thermal conduction in liquid systems. The book covers topics such as the principles of non-equilibrium thermodynamics; diffusion in binary and multicompetent systems; and experimental methods of studying diffusion processes in liquids. Also covered in the book are topics such as the theoretical interpretations of diffusion coefficients; hydrodynamic and kinetic theories; and diffusion in electrolyte systems. The text is recommen

  14. Theoretical and Methodological Perspectives on Designing Video Studies of Interaction

    Directory of Open Access Journals (Sweden)

    Anna-Lena Rostvall

    2005-12-01

    Full Text Available In this article the authors discuss the theoretical basis for the methodological decisions made during the course of a Swedish research project on interaction and learning. The purpose is to discuss how different theories are applied at separate levels of the study. The study is structured on three levels, with separate sets of research questions and theoretical concepts. The levels reflect a close-up description, a systematic analysis, and an interpretation of how teachers and students act and interact. The data consist of 12 hours of video-recorded and transcribed music lessons from high school and college. Through a multidisciplinary theoretical framework, the general understanding of teaching and learning in terms of interaction can be widened. The authors also present a software tool developed to facilitate the processes of transcription and analysis of the video data.

  15. Is it really theoretical? A review of sampling in grounded theory studies in nursing journals.

    Science.gov (United States)

    McCrae, Niall; Purssell, Edward

    2016-10-01

    Grounded theory is a distinct method of qualitative research, where core features are theoretical sampling and constant comparative analysis. However, inconsistent application of these activities has been observed in published studies. This review assessed the use of theoretical sampling in grounded theory studies in nursing journals. An adapted systematic review was conducted. Three leading nursing journals (2010-2014) were searched for studies stating grounded theory as the method. Sampling was assessed using a concise rating tool. A high proportion (86%) of the 134 articles described an iterative process of data collection and analysis. However, half of the studies did not demonstrate theoretical sampling, with many studies declaring or indicating a purposive sampling approach throughout. Specific reporting guidelines for grounded theory studies should be developed to ensure that study reports describe an iterative process of fieldwork and theoretical development. © 2016 John Wiley & Sons Ltd.

  16. Theoretical study on the flow about Savonius rotor

    Science.gov (United States)

    Ogawa, T.

    1984-03-01

    A method for the two-dimensional analysis of the separated flow about Savonius rotors is presented. Calculations are performed by combining the singularity method and the discrete vortex method. The method is applied to the simulation of flows about a stationary rotor and a rotating rotor. Moreover, torque and power coefficients are computed and compared with the experimental results presented by Sheldahl et al. Theoretical and experimental results agree well qualitatively.

  17. Species comparative studies and cognitive development.

    Science.gov (United States)

    Gómez, Juan-Carlos

    2005-03-01

    The comparative study of infant development and animal cognition brings to cognitive science the promise of insights into the nature and origins of cognitive skills. In this article, I review a recent wave of comparative studies conducted with similar methodologies and similar theoretical frameworks on how two core components of human cognition--object permanence and gaze following--develop in different species. These comparative findings call for an integration of current competing accounts of developmental change. They further suggest that evolution has produced developmental devices capable at the same time of preserving core adaptive components, and opening themselves up to further adaptive change, not only in interaction with the external environment, but also in interaction with other co-developing cognitive systems.

  18. A theoretical model for smoking prevention studies in preteen children.

    Science.gov (United States)

    McGahee, T W; Kemp, V; Tingen, M

    2000-01-01

    The age of the onset of smoking is on a continual decline, with the prime age of tobacco use initiation being 12-14 years. A weakness of the limited research conducted on smoking prevention programs designed for preteen children (ages 10-12) is a well-defined theoretical basis. A theoretical perspective is needed in order to make a meaningful transition from empirical analysis to application of knowledge. Bandura's Social Cognitive Theory (1977, 1986), the Theory of Reasoned Action (Ajzen & Fishbein, 1980), and other literature linking various concepts to smoking behaviors in preteens were used to develop a model that may be useful for smoking prevention studies in preteen children.

  19. Theoretical and Experimental Study of Time Reversal in Cubic Crystals

    Institute of Scientific and Technical Information of China (English)

    陆铭慧; 张碧星; 汪承灏

    2004-01-01

    The self-adaptive focusing of the time reversal in anisotropic media is studied theoretically and experimentally. It is conducted for the compressional wave field in the cubic crystal silicon. The experimental result is in agreement with our theoretical analysis. The focusing gain and the displacement distributions of the time reversal field are analysed in detail. It is shown that the waves from different elements of the transducer array arrive at the original place of the source simultaneously after the time reversal operation. The waveform distortions caused by the velocity anisotropy can automatically be compensated for after the time reversal processing.

  20. Theoretical study of n-alkane adsorption on metal surfaces

    DEFF Research Database (Denmark)

    Morikawa, Yoshitada; Ishii, Hisao; Seki, Kazuhiko

    2004-01-01

    The interaction between n-alkane and metal surfaces has been studied by means of density-functional theoretical calculations within a generalized gradient approximation (GGA). We demonstrate that although the GGA cannot reproduce the physisorption energy well, our calculations can reproduce the e...

  1. Theoretical Study of Small (NaI)n Clusters

    CERN Document Server

    Aguado, A; López, J M; Alonso, J A

    1997-01-01

    A systematic theoretical study of stoichiometric clusters (NaI)n up to n=15 is performed using the ab initio Perturbed-Ion (PI) model. The structures obtained are compared to previous pair potential results, and observed differences between (NaI)n clusters and previous ab initio results for other alkali halide clusters are discussed. (NaI)n clusters with n up to 15 do not show yet a marked preference for geometries which are fragments of the bulk lattice. Instead, stacks of hexagonal rings or more open structures are obtained as ground structures in clusters with n=3, 6, 7, 9, 10, 12, 13 and 15, indicating that convergence to bulk structure is not achieved yet at this size range. Low lying isomers which are fragments of the crystal lattice exist, nevertheless, for those cases. The binding energies show that clusters with n=(4), 6, 9 and 12 molecules are specially stable. The binding energy has been decomposed in contributions which allow for an intuitive interpretation. Some electronic properties like ionizat...

  2. A comparative theoretical-experimental analysis of settlements of shallow foundations on granular soil

    Directory of Open Access Journals (Sweden)

    Davidović Nebojša

    2010-01-01

    Full Text Available The paper presents a brief description of experiment within the research project 'Theoretical and experimental analysis of interaction of shallow reinforced concrete foundations and soil for the purpose of improvement of national regulations and implementaation of Eurocode system' where in situ tests of a series of reinforced concrete foundation footing were performed, by loading until failure. As a rule, methods for calculation of shallow foundations settlement on granular soils overestimate the expected settlement, and underestimate soil bearing capacity, which results in a conservative foundation design. In order to test accuracy and reliability of the different settlements prediction methods, a comparative analysis of settlements calculated using these methods and those measured during experiment, was performed.

  3. Comparative study of hydrogenated and lithiated superhalogens

    Science.gov (United States)

    Xu, Li-Na; Li, Ying; Liu, Jia-Yuan; Wu, Di; Sun, Yan-Bo; Li, Zhi-Ru

    2016-09-01

    The structural features, properties and stability of two kinds of representative superhalogen compounds, namely hydrogenated superhalogens and lithiated superhalogens, are theoretically studied in detail, providing further insight into the behavior of superhalogens. According to topological analysis of the electron localization function, most of superhalogen clusters as a whole combine with Li atom through ionic bond(s). In contrast, the H atom tends to bind with superhalogen by covalent bond although a portion of superhalogens are broken upon hydrogenation. In addition, the electric properties of these superhalogen compounds are also obtained and compared with those of traditional acid and salt molecules.

  4. Towards a Theoretical Framework for the Comparative Understanding of Globalisation, Higher Education, the Labour Market and Inequality

    Science.gov (United States)

    Kupfer, Antonia

    2011-01-01

    This paper is a theoretical examination of three major empirical trends that affect many people: globalisation, increasingly close relations between higher education (HE) and labour markets, and increasing social inequality. Its aim is to identify key theoretical resources and their contribution to the development of a comparative theoretical…

  5. Dimerization of Indanedioneketene to Spiro-oextanone: A Theoretical Study

    Energy Technology Data Exchange (ETDEWEB)

    Bakalbassis, Evangelos G; Malamidou-Xenikaki, Elizabeth; Spyroudis, Spyros; Xantheas, Sotiris S

    2010-08-20

    Indanedioneketene, a compound resulting from the thermal degradation of the phenyliodonium ylide of lawsone, dimerises quantitatively to a spiro-oxetanone derivative, a key compound for further transformations. A theoretical DFT study of this unusual for α-oxoketenes [2+2] cyclization reaction both in the gas phase and in dichloromethane solution, provides support for a) a single-step, transitionstate (involving a four-membered cyclic ring) charge controlled, concerted mechanism, and b) a [4+2] cyclization reaction, not observed but studied theoretically in this study. A parallel study of an open chain α,α'-dioxoketene dimerization explains the difference in the stability and reactivity observed experimentally between the cyclic and open chain products.

  6. Postcoital Sperm Assessment Comparative Study.

    Science.gov (United States)

    Pelekanos, Michael J

    2015-11-01

    This postcoital sperm assessment study was performed over a 10 month time period (November 2014-August 2015). Fifteen couples enrolled in the study. The study was a non-blinded, non-randomized, single-center comparison study comparing The Stork® OTC (Rinovum Women's Health, Monroeville, PA) to natural intercourse (NI), using the subjects as their own control/baseline. This was an efficacy study designed to compare the number of sperm in the cervical mucus following the use of The Stork OTC conception aid with the number of sperm in the cervical mucus following natural intercourse. Subjects used both The Stork OTC conception system and the natural intercourse method to evaluate concentrations of sperm in the cervical mucus. Post-coital test (PCT) data was collected demonstrating higher concentrations of sperm within the cervical mucus with The Stork OTC conception system versus natural intercourse for 85% of test subjects in this study. Of the 15 couples enrolled in the study, 2 were lost to follow-up. Mean age for male subjects was 31.7 +/ 5.4 years of age and mean age for female subjects was 29.7+/- 5.4. The average sperm score value of the 85% of test subjects with higher sperm concentrations from The Stork OTC was 3.23 times the score value of sperm concentration compared to natural intercourse. The remaining 15% of test subjects showed no change in sperm score value between The Stork OTC and natural intercourse.

  7. Theoretical Studies on Photoionization Cross Sections of Solid Gold

    Institute of Scientific and Technical Information of China (English)

    MA Xiao-Guang; SUN Wei-Guo; CHENG Yah-Song

    2005-01-01

    Accurate expression for photoabsorption (photoionization) cross sections of high density system proposed recently is used to study the photoionization of solid gold. The results show that the present theoretical photoionization cross sections have good agreement both in structure and in magnitude with the experimental results of gold crystal.The studies also indicate that both the real part ε'and the imaginary part ε" of the complex dielectric constant ε,and the dielectric influence function of a nonideal system have rich structures in low energy side with a range about 50 eV, and suggest that the influence of particle interactions of surrounding particles with the photoionized particle on the photoionization cross sections can be easily investigated using the dielectric influence function. The electron overlap effects are suggested to be implemented in the future studies to improve the accuracy of theoretical photoionization cross sections of a solid system.

  8. Experimental and theoretical studies of interactions between Si{7} clusters

    Science.gov (United States)

    Gynz-Rekowski, F. V.; Quester, W.; Dietsche, R.; Lim, D. C.; Bertram, N.; Fischer, T.; Ganteför, G.; Schach, M.; Nielaba, P.; Kim, Y. D.

    2007-12-01

    The possibility of using magic Si7 clusters to form a cluster material was studied experimentally and theoretically. In experiments Si7 clusters were deposited on carbon surfaces, and the electronic structure and chemical properties of the deposited clusters were measured using X-ray photoelectron spectroscopy (XPS). A non bulk-like electronic structure of Si7 was found in the Si 2p core level spectra. Si7 is suggested to form a more stable structure than the non-magic Si8 cluster and Si atoms upon deposition on carbon surfaces. Theoretically it was possible to study the interaction between the clusters without the effect of a surface. Density functional theory (DFT) calculations of potential curves of two free Si7 clusters approaching each other in various orientations hint at the formation of cluster materials rather than the fusion of clusters forming bulk-like structures.

  9. Theoretical and material studies on thin-film electroluminescent devices

    Science.gov (United States)

    Summers, C. J.; Goldman, J. A.; Brennan, K.

    1988-01-01

    During this report period work was performed on the modeling of High Field Electronic Transport in Bulk ZnS and ZnSe, and also on the surface cleaning of Si for MBE growth. Some MBE growth runs have also been performed in the Varian GEN II System. A brief outline of the experimental work is given. A complete summary will be done at the end of the next reporting period at the completion of the investigation. The theoretical studies are included.

  10. Experimental and theoretical study on rapid transient nucleated boiling

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A laser heater has been used to impose a pulsed high power laser beam on a metal film inunersed in liquid to generate a very high rate of temperature rise up to 9.3 × 106K/s in the metal film. The rapid transient boiling phenomena have been observed and the temperature variations in the metal film have been measured. Theoretical calculations have been carried out with the fluctuation nucleation theory and the heat conduction theory to compare with the experimental results, and some results are reported.

  11. Experimental and theoretical study on the electrospinning nanoporous fibers process

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jianghui; Si, Na [National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou (China); Xu, Lan, E-mail: lanxu@suda.edu.cn [National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou (China); Nantong Textile Institute of Soochow University, Nantong (China); Tang, Xiaopeng; Song, Yanhua; Sun, Zhaoyang [National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou (China)

    2016-02-15

    Porous materials can be prepared by sol–gel method, hydrothermal synthesis method, electrospinning and other methods. In this paper, electrospun porous nanofibers were prepared by adjusting electrospinning parameters. And the properties of obtained porous nanofiber mats were investigated. Theoretical analysis and experiment research were carried out to research mechanical mechanism of electrospun porous nanofibers, and could be used to optimize and control the porous structure. The theoretical analysis results were further verified according to the experimental data. In addition, Bernoulli equation was used to study the electrospinning “splaying” process. We found the ratio of pore width to pore length was varied along with the variation of the internal pressure of the jet, and the internal pressure of the jet increases with the velocity of the charged jet decreases. - Highlights: • Mechanical mechanism of electrospun porous nanofibers process was studied. • A simplifying gas–liquid two-phase flow model was established. • Bernoulli equation was used to study the electrospinning “splaying” process. • The theoretical results were in good agreement with the experimental data. • The electrospinning parameters affected the surface morphology of charged jet.

  12. Sociomateriality: a theoretical framework for studying distributed medical education.

    Science.gov (United States)

    MacLeod, Anna; Kits, Olga; Whelan, Emma; Fournier, Cathy; Wilson, Keith; Power, Gregory; Mann, Karen; Tummons, Jonathan; Brown, Peggy Alexiadis

    2015-11-01

    Distributed medical education (DME) is a type of distance learning in which students participate in medical education from diverse geographic locations using Web conferencing, videoconferencing, e-learning, and similar tools. DME is becoming increasingly widespread in North America and around the world.Although relatively new to medical education, distance learning has a long history in the broader field of education and a related body of literature that speaks to the importance of engaging in rigorous and theoretically informed studies of distance learning. The existing DME literature is helpful, but it has been largely descriptive and lacks a critical "lens"-that is, a theoretical perspective from which to rigorously conceptualize and interrogate DME's social (relationships, people) and material (technologies, tools) aspects.The authors describe DME and theories about distance learning and show that such theories focus on social, pedagogical, and cognitive considerations without adequately taking into account material factors. They address this gap by proposing sociomateriality as a theoretical framework allowing researchers and educators to study DME and (1) understand and consider previously obscured actors, infrastructure, and other factors that, on the surface, seem unrelated and even unimportant; (2) see clearly how the social and material components of learning are intertwined in fluid, messy, and often uncertain ways; and (3) perhaps think differently, even in ways that disrupt traditional approaches, as they explore DME. The authors conclude that DME brings with it substantial investments of social and material resources, and therefore needs careful study, using approaches that embrace its complexity.

  13. Sustainable Nanotechnology: Opportunities and Challenges for Theoretical/Computational Studies.

    Science.gov (United States)

    Cui, Qiang; Hernandez, Rigoberto; Mason, Sara E; Frauenheim, Thomas; Pedersen, Joel A; Geiger, Franz

    2016-08-04

    For assistance in the design of the next generation of nanomaterials that are functional and have minimal health and safety concerns, it is imperative to establish causality, rather than correlations, in how properties of nanomaterials determine biological and environmental outcomes. Due to the vast design space available and the complexity of nano/bio interfaces, theoretical and computational studies are expected to play a major role in this context. In this minireview, we highlight opportunities and pressing challenges for theoretical and computational chemistry approaches to explore the relevant physicochemical processes that span broad length and time scales. We focus discussions on a bottom-up framework that relies on the determination of correct intermolecular forces, accurate molecular dynamics, and coarse-graining procedures to systematically bridge the scales, although top-down approaches are also effective at providing insights for many problems such as the effects of nanoparticles on biological membranes.

  14. Theoretical and Experimental Study of Plasmonic Polymer Solar Cells

    DEFF Research Database (Denmark)

    Mirsafaei, Mina; Adam, Jost; Madsen, Morten

    The organic bulk hetero-junction solar cell has remarkable advantages such as low cost, mechanical flexibility and simple process techniques. Recently, low-band gap photoactive materials have obtained a significant attention due to their potential to absorb a wider range of the solar spectrum...... other approaches, be achieved by using nano- or micro-structures that trap light at specific wavelengths [2], or by using the localized surface plasmon resonance effect of metal nanoparticles in the devices. In this work, we theoretically studied planar polymer solar cell based on finite-difference time......-domain approach. Also, we have optimized reference polymer solar cells with PTB7:PC70BM as active layer, using two different electron transport layers. The aim is to integrate Gold nanoparticles in the reference devices, and support the integration theoretically....

  15. Statistical and theoretical studies of flares from Sagittarius A*

    Science.gov (United States)

    Li, Ya-Ping; Yuan, Qiang; Wang, Q. Daniel; Chen, P. F.; Neilsen, Joseph; Fang, Taotao; Zhang, Shuo; Dexter, Jason

    2017-01-01

    Multi-wavelength flares have routinely been observed from the supermassive black hole, Sagittarius A* (Sgr A*), at our Galactic center. The nature of these flares remains largely unclear, despite many theoretical models. We study the statistical properties of the Sgr A* X-ray flares and find that they are consistent with the theoretical prediction of the self-organized criticality system with the spatial dimension S = 3. We suggest that the X-ray flares represent plasmoid ejections driven by magnetic reconnection (similar to solar flares) in the accretion flow onto the black hole. Motivated by the statistical results, we further develop a time-dependent magnetohydrodynamic (MHD) model for the multi-band flares from Sgr A* by analogy with models of solar flares/coronal mass ejections (CMEs). We calculate the X-ray, infrared flare light curves, and the spectra, and find that our model can explain the main features of the flares.

  16. Average cross section measurement for 162Er (γ, n) reaction compared with theoretical calculations using TALYS

    Science.gov (United States)

    Vagena, E.; Stoulos, S.

    2017-01-01

    Bremsstrahlung photon beam delivered by a linear electron accelerator has been used to experimentally determine the near threshold photonuclear cross section data of nuclides. For the first time, (γ, n) cross section data was obtained for the astrophysical important nucleus 162Er. Moreover, theoretical calculations have been applied using the TALYS 1.6 code. The effect of the gamma ray strength function on the cross section calculations has been studied. A satisfactorily reproduction of the available experimental data of photonuclear cross section at the energy region below 20 MeV could be achieved. The photon flux was monitored by measuring the photons yield from seven well known (γ, n) reactions from the threshold energy of each reaction up to the end-point energy of the photon beam used. An integrated cross-section 87 ± 14 mb is calculated for the photonuclear reaction 162Er (γ, n) at the energy 9.2-14 MeV. The effective cross section estimated using the TALYS code range between 89 and 96 mb depending on the γ-strength function used. To validate the method for the estimation of the average cross-section data of 162Er (γ, n) reaction, the same procedure has been performed to calculate the average cross-section data of 197Au (γ, n) and 55Mn (γ, n) reactions. In this case, the photons yield from the rest well known (γ, n) reactions was used in order to monitoring the photon flux. The results for 162Er (γ, n), 197Au (γ, n) and 55Mn (γ, n) are found to be in good agreement with the theoretical values obtained by TALYS 1.6. So, the present indirect process could be a valuable tool to estimate the effective cross section of (γ, n) reaction for various isotopes using bremsstrahlung beams.

  17. THEORETICAL STUDY OF THREE-DIMENSIONAL NUMERICAL MANIFOLD METHOD

    Institute of Scientific and Technical Information of China (English)

    LUO Shao-ming; ZHANG Xiang-wei; L(U) Wen-ge; JIANG Dong-ru

    2005-01-01

    The three-dimensional numerical manifold method(NMM) is studied on the basis of two-dimensional numerical manifold method. The three-dimensional cover displacement function is studied. The mechanical analysis and Hammer integral method of three-dimensional numerical manifold method are put forward. The stiffness matrix of three-dimensional manifold element is derived and the dissection rules are given. The theoretical system and the numerical realizing method of three-dimensional numerical manifold method are systematically studied. As an example, the cantilever with load on the end is calculated, and the results show that the precision and efficiency are agreeable.

  18. THEORETICAL AND EXPERIMENTAL STUDY OF STRUCTURES SUBJECTED TO EARTHQUAKES

    Energy Technology Data Exchange (ETDEWEB)

    Soubirou, A.

    1967-12-31

    The object of the study was the investigation of the behaviour of structures subject to earthquakes. After .describing and analysing seismic movements, useful concepts for earthquake-proofing structures are lintroduced. Then, the dynamic behaviour of systems with n degrees of freedom was studied in order to evolve the theoretical computation of seismic behaviour, a typical application being reticulated structures. The next stage was showing the computational procedure for seismic spectra and the natural frequencies of buildings, an attempt being made to define earthquake-proofing criteria for a special type of reinforced-concrete construction. . The last matter dealt with is elastoplastic behaviour of structures, a study of increasingly growing importance.

  19. Theoretical studies of lipid bilayer electroporation using molecular dynamics simulations

    Science.gov (United States)

    Levine, Zachary Alan

    system where lipids can become damaged or severely impacted from interacting with reactive oxygen species, and these events become more frequent with age. The results are then compared to experiments where we show agreement between our simulations, theoretical models, and experiments with peroxidized cells in our lab. In Chapter 3 I outline a set of unique metrics which can be used to quantitatively measure the life cycle of a discrete electropore for the first time, across multiple lipid species, and I compare these results to analytical models where we find good agreement with theory. In Chapter 4 I use the life cycle of an electropore as a tool to measure the effects of electrolyte and lipid headgroup charge on electroporation compared to electrolyte-free and zwitterionic systems, in addition to presenting ion binding isotherms to determine the validity of our simulated electrolyte models. Chapters 5 and 6 focus on the roles of water and lipid respectively on electroporation using simplified water:vacuum systems, osmotic swelling simulations, systems at varying temperature, and systems where we successfully modulated the electropore radius using customized time-dependent electric fields. I conclude this dissertation with a brief summary of these studies followed by a short outlook on the future of electroporation simulations as a whole.

  20. Theoretical study for solar air pretreatment collector/regenerator

    Energy Technology Data Exchange (ETDEWEB)

    Peng Donggen; Zhang Xiaosong; Yin Yonggao [School of Energy and Environment, Southeast Univ., Nanjing (China)

    2008-07-01

    A new liquid regeneration equipment - solar air pretreatment collector/regenerator for liquid desiccant cooling system is put forward in this paper, which is preferable to solution regeneration in hot and moist climate in South China. The equipment can achieve liquid regeneration in lower temperature. When the solution and the air are in ''match'' state in collector/ regenerator, a match air to salt mass ratio ASMR* is found by theoretical study in which there is the largest theoretical storage capacity SC{sub max}. After two new concepts of the effective solution proportion (EPS) and the effective storage capacity (ESC) are defined, it is found by theoretical calculation that when ESP drops from 100% to 67%, ESC raises lowly, not drops and liquid outlet concentration C{sub str} {sub sol} increases from 40% to 49% in which its increment totals to 90%. All these data explain fully that air pretreatment liquid regeneration equipment enables to improve the performance of liquid desiccant cooling system. (orig.)

  1. Theoretical and experimental study of the normal modes in a coupled two-dimensional system

    CERN Document Server

    Giménez, Marcos H; Gómez-Tejedor, José Antonio; Velazquez, Luisberis; Monsoriu, Juan A

    2016-01-01

    In this work, the normal modes of a two-dimensional oscillating system have been studied from a theoretical and experimental point of view. The normal frequencies predicted by the Hessian matrix for a coupled two-dimensional particle system are compared to those obtained for a real system consisting of two oscillating smartphones coupled one to the other by springs. Experiments are performed on an air table in order to remove the friction forces. The oscillation data are captured by the acceleration sensor of the smartphones and exported to file for further analysis. The experimental frequencies compare reasonably well with the theoretical predictions, namely, within 1.7 % of discrepancy.

  2. [Comparative studies of face recognition].

    Science.gov (United States)

    Kawai, Nobuyuki

    2012-07-01

    Every human being is proficient in face recognition. However, the reason for and the manner in which humans have attained such an ability remain unknown. These questions can be best answered-through comparative studies of face recognition in non-human animals. Studies in both primates and non-primates show that not only primates, but also non-primates possess the ability to extract information from their conspecifics and from human experimenters. Neural specialization for face recognition is shared with mammals in distant taxa, suggesting that face recognition evolved earlier than the emergence of mammals. A recent study indicated that a social insect, the golden paper wasp, can distinguish their conspecific faces, whereas a closely related species, which has a less complex social lifestyle with just one queen ruling a nest of underlings, did not show strong face recognition for their conspecifics. Social complexity and the need to differentiate between one another likely led humans to evolve their face recognition abilities.

  3. Theoretical study of fractal growth and stability on surface

    DEFF Research Database (Denmark)

    Dick, Veronika V.; Solov'yov, Ilia; Solov'yov, Andrey V.

    2009-01-01

    We perform a theoretical study of the fractal growing process on surface by using the deposition, diffusion, aggregation method. We present a detailed analysis of the post-growth processes occurring in a nanofractal on surface. For this study we developed a method which describes the internal...... dynamics of particles in a fractal and accounts for their diffusion and detachment. We demonstrate that these kinetic processes are responsible for the formation of the final shape of the islands on surface after the post-growth relaxation....

  4. Complex coacervation: A field theoretic simulation study of polyelectrolyte complexation

    Science.gov (United States)

    Lee, Jonghoon; Popov, Yuri O.; Fredrickson, Glenn H.

    2008-06-01

    Using the complex Langevin sampling strategy, field theoretic simulations are performed to study the equilibrium phase behavior and structure of symmetric polycation-polyanion mixtures without salt in good solvents. Static structure factors for the segment density and charge density are calculated and used to study the role of fluctuations in the electrostatic and chemical potential fields beyond the random phase approximation. We specifically focus on the role of charge density and molecular weight on the structure and complexation behavior of polycation-polyanion solutions. A demixing phase transition to form a ``complex coacervate'' is observed in strongly charged systems, and the corresponding spinodal and binodal boundaries of the phase diagram are investigated.

  5. Theoretical study of fractal growth and stability on surface

    DEFF Research Database (Denmark)

    Dick, Veronika V.; Solov'yov, Ilia; Solov'yov, Andrey V.

    2009-01-01

    We perform a theoretical study of the fractal growing process on surface by using the deposition, diffusion, aggregation method. We present a detailed analysis of the post-growth processes occurring in a nanofractal on surface. For this study we developed a method which describes the internal...... dynamics of particles in a fractal and accounts for their diffusion and detachment. We demonstrate that these kinetic processes are responsible for the formation of the final shape of the islands on surface after the post-growth relaxation....

  6. Electronic structure of copper phthalocyanine : An experimental and theoretical study of occupied and unoccupied levels

    NARCIS (Netherlands)

    Evangelista, Fabrizio; Carravetta, Vincenzo; Stefani, Giovanni; Jansik, Branislav; Alagia, Michele; Stranges, Stefano; Ruocco, Alessandro

    2007-01-01

    An experimental and theoretical study of the electronic structure of copper phthalocyanine (CuPc) molecule is presented. We performed x-ray photoemission spectroscopy (XPS) and photoabsorption [x-ray absorption near-edge structure (XANES)] gas phase experiments and we compared the results with self-

  7. Electronic structure of copper phthalocyanine : An experimental and theoretical study of occupied and unoccupied levels

    NARCIS (Netherlands)

    Evangelista, Fabrizio; Carravetta, Vincenzo; Stefani, Giovanni; Jansik, Branislav; Alagia, Michele; Stranges, Stefano; Ruocco, Alessandro

    2007-01-01

    An experimental and theoretical study of the electronic structure of copper phthalocyanine (CuPc) molecule is presented. We performed x-ray photoemission spectroscopy (XPS) and photoabsorption [x-ray absorption near-edge structure (XANES)] gas phase experiments and we compared the results with

  8. Electronic structure of copper phthalocyanine : An experimental and theoretical study of occupied and unoccupied levels

    NARCIS (Netherlands)

    Evangelista, Fabrizio; Carravetta, Vincenzo; Stefani, Giovanni; Jansik, Branislav; Alagia, Michele; Stranges, Stefano; Ruocco, Alessandro

    2007-01-01

    An experimental and theoretical study of the electronic structure of copper phthalocyanine (CuPc) molecule is presented. We performed x-ray photoemission spectroscopy (XPS) and photoabsorption [x-ray absorption near-edge structure (XANES)] gas phase experiments and we compared the results with self-

  9. Theoretical Studies of Substitutionally Doped Single-Walled Nanotubes

    Directory of Open Access Journals (Sweden)

    Charles See Yeung

    2010-01-01

    Full Text Available The rich chemistry of single-walled carbon nanotubes (SWCNTs is enhanced by substitutional doping, a process in which a single atom of the nanotube sidewall is replaced by a heteroatom. These so-called heteroatom-substituted SWCNTs (HSWCNTs exhibit unique chemical and physical properties not observed in their corresponding undoped congeners. Herein, we present theoretical studies of both main group element and transition metal-doped HSWCNTs. Within density functional theory (DFT, we discuss mechanistic details of their proposed synthesis from vacancy-defected SWCNTs and describe their geometric and electronic properties. Additionally, we propose applications for these nanomaterials in nanosensing, nanoelectronics, and nanocatalysis.

  10. Theoretical Study of 1,8-Diaminonaphthalene Polymerization

    Science.gov (United States)

    Nateghi, Mohammad R.; Kalantari, F.

    2007-12-01

    The polymerization of 1,8-diaminonaphthalene (1,8-DAN) was studied by a theoretical approach based on Hartree-Fock calculations. Investigation of relative stability of most possible dimers, trimers and tetramers yields very useful data concerning the regioselectivity of the coupling reaction as well as the final structures of the polymeric chains. The mechanism is more likely to occur via a radical-radical pathway and leads to mixture of compounds through ortho-C-C and para-C-N linkages.

  11. Theoretical Study of the Diastereofacial Isomers of Aldrin and Dieldrin

    Directory of Open Access Journals (Sweden)

    Zoran Zdravkovski

    2006-02-01

    Full Text Available The Diels-Alder reaction of hexachlorocyclopentadiene with norbornadiene givesaldrin but theoretically three other diastereofacial isomers are possible. On oxidation theseisomers can generate eight adducts one of which is known as dieldrin. All these, as well asthe corresponding reactions with hexafluorocyclopenadiene were studied by semiempirical(AM1 and PM3 and hybrid density functional (B3LYP methods. Besides the energy levels,the transition states were calculated for the reactions leading to the diastereofacial isomers ofaldrin, which indicate that aldrin is the favored product of the reaction both fromthermodynamic and kinetic point of view.

  12. Theoretical and numerical studies on morphological transitions in crack growth

    CERN Document Server

    Mühle, V

    1999-01-01

    This paper investigates the formation of crack patterns in stationary and transient temperature fields analytically with linear elastic fracture mechanics and numerically with the finite elements method (FEM). In particular, we consider the experimental situation of a narrow thin strip of hot glass slowly lowered into cold water, with temperature difference and velocity as variable parameters. The parameter regions of no crack, one straight crack and one oscillating crack are determined. The type of phase transition related to the borderline between straight and oscillating crack is characterized. The theoretical results are compared with those of other Similar investigations and comparisons are done for the propagation of multiple cracks. Quenching of a wide thin strip leads to a hierarchy of cracks whose scaling properties are analyzed. Without any fitting, theory and experiment agree surprisingly well.

  13. Theoretical study on a solar collector loop during stagnation

    DEFF Research Database (Denmark)

    Chen, Ziqian; Dragsted, Janne; Furbo, Simon;

    2010-01-01

    A mathematical model simulating the stagnation behavior of a pressurized solar collector loop with solar collectors with a good emptying behavior is developed. Based on the pre-pressure of the expansion vessel, the system filling pressure of the solar collector loop and the design of the solar...... collector loop, the mass of the fluid flowing into the pressurized expansion vessel and the pressures at the top part and at the bottom part of the solar collector loop during stagnation for the solar collector loop are calculated. The theoretically calculated results are compared with experimental results....... There is a good agreement between calculations and measurements. The developed simulation model is therefore suitable to determine the behavior of solar collector loops during stagnation....

  14. Theoretical study on a solar collector loop during stagnation

    DEFF Research Database (Denmark)

    Chen, Ziqian; Dragsted, Janne; Furbo, Simon;

    A mathematical model simulating the stagnation behavior of a pressurized solar collector loop with solar collectors with a good emptying behavior is developed. Based on the pre-pressure of the expansion vessel, the system filling pressure of the solar collector loop and the design of the solar...... collector loop, the mass of the fluid flowing into the pressurized expansion vessel and the pressures at the top part and at the bottom part of the solar collector loop during stagnation for the solar collector loop are calculated. The theoretically calculated results are compared with experimental results....... There is a good agreement between calculations and measurements. The developed simulation model is therefore suitable to determine the behavior of solar collector loops during stagnation....

  15. The intensity of immunogold labeling of deplasticized acrylic sections compared to deplasticized epoxy sections-Theoretical deductions and experimental data.

    Science.gov (United States)

    Brorson, Sverre-Henning; Reinholt, Finn P

    2008-01-01

    The purpose of this study was to compare the level of immunogold labeling of deplasticized acrylic sections and deplasticized epoxy sections. Pure protein gels of IgG, albumin and thyroglobulin were produced by glutaraldehyde fixation and embedded in non-crosslinked acrylic resin (Technovit 9100) and epoxy resin (Epon 812), respectively. Ultrathin sections of acrylic and epoxy resin were separately deplasticized in 2-methoxyethyl acetate (MEA) and sodium ethoxide. Quantitative immunogold labeling was performed with anti-IgG, anti-albumin and anti-thyroglobulin antibodies on sections of the corresponding protein gels. For all antibodies tested, the intensity of labeling for deplasticized acrylic sections was significantly higher (two to four times) than for the corresponding deplasticized epoxy sections. The results fit with a theoretically deduced relation: the quotient of the labeling of two deplasticized sections of different resins is equivalent to the square root of the quotient of the labeling of the similar sections not exposed to any kind of pre-treatment. The practical significance of the results is that immunolabeling of deplasticized non-crosslinked acrylic resin results in more intense immunogold labeling than deplasticized epoxy sections. Deplasticizing is most useful when the requirements for ultrastructural preservation according to conventional criteria are moderate. Our theoretically deduced results also indicate that deplasticized Technovit (or other non-crosslinked acrylic resins) sections will be significantly better suited for immunolabeling at the light microscopic level than deplasticized epoxy sections.

  16. Experimental and Theoretical Study on Pyrolysis of Isopsoralen

    Institute of Scientific and Technical Information of China (English)

    Jiu-zhong Yang; Feng Zhang; Liang-yuan Jia; Li-dong Zhang; Fei Qi; Hai-yan Fan; Ji-bao Cai

    2012-01-01

    The pyrolysis of isopsoralen was studied by synchrotron vacuum ultraviolet photoionization mass spectrometry at low pressure.The pyrolysis products were detected at different photon energies,the ratios of products to precursor were measured at various pyrolysis temperatures.The experimental results demonstrate that the main pyrolysis products are primary CO and sequential CO elimination products (C10H6O2 and C9H6O).The decomposition channels of isopsoralen were also studied by the density functional theory,then rate constants for competing pathways were calculated by the transition state theory.The dominant decomposition channels of isopsoralen and the molecular structures for corresponding products were identified bv combined experimental and theoretical studies.

  17. Comparative study of theoretical accounting and actual measuring results of the safety protection distance of WCDMA network base station%WCDMA网络基站安全防护距离理论计算与实测对比研究

    Institute of Scientific and Technical Information of China (English)

    郝睿; 徐续; 江君; 张晓峰

    2012-01-01

    This paper would like to introduce the results of our comparative study of theoretical accounting and actual measuring results of the safety protection distance of WCDMA network base station. As a matter of fact, more and more mobile base stations have been set up with the advancement of urban mobile communication technology. And, in turn, problems are emerging on how to reduce the detrimental electromagnetic radiation of these stations to the surrounding buildings , offices, schools and hospitals. Wideband Code Division Multiple Access (WCDMA) technology of China Unicom is one representative of 3G networks, which are planning and constructing extensively. Based on the calculation formula for the microwave far-field axial power density from Guideline on the Management of Radioactive Environmental Protection Electromagnetic Radiation Monitoring Instruments and Methods, we have made necessary theoretical accounting and actual measuring of the safety protection distance of the network base stations. Here we found that the electromagnetic radiation of the base station can be measured by means of a Germany-EMR 300 electromagnetic analyzer. Compared with the actual values measured, the results of the theoretical prediction prove to be more conservative than that of actual measurements on the horizontal direction, but close to the vertical direction. The reasons for the discrepancy may account for a few reasons, such as transmission power, traffic, monitoring conditions, building interference and the features of WCDMA network station, etc. Due to the limited power control technology, the actual transmission power of the network station is likely to be weaker than the maximum values, but can also satisfy the system quality and the customers' demands. In addition, the discrepancy between the practical measurement and the theoretical calculation may also result from the diffraction, reflection of buildings, air absorption, blocking and the other factors. Combined to the

  18. THEORETICAL ANALYSIS STUDY OF FORMATION OF FUTURE LEGAL LAWYERS

    Directory of Open Access Journals (Sweden)

    Eugene Stepanovich Shevlakov

    2015-09-01

    Full Text Available The article deals with topical issues of formation of legal consciousness of future lawyers in high school. Obtained kinds of legal consciousness of future lawyers, determined its structure. Dedicated components of justice are mutually reinforcing, and provide an opportunity for further development of the personality of the future specialist, their personal growth.The purpose: to carry out theoretical analysis of the problem of formation of legal consciousness of future lawyers.The novelty is based. On the analysis of theoretical appro-aches of pedagogy, psychology, law, the notion of «lawfulness of the future of the law student», which is regarded as a form of social consciousness, which is a set of legal views and feelings, expressing the attitude to the law and legal phenomena that have regulatory in character and which includes know-ledge of legal phenomena and their evaluation from the point of view of fairness and justice, formed in the process of studying in the University.Results: this article analyzes different approaches to understanding the content and essence of the concept of legal consciousness of the legal profession. Define the types and structure of legal consciousness of future lawyers.

  19. Phototransformations of quinaldic acid: Theoretical and experimental study

    Science.gov (United States)

    Shterev, Ivan G.; Delchev, Vassil B.

    2017-01-01

    A combined theoretical and experimental study was performed in order to clarify the mechanisms of phototransformations of a quinaldic acid solution in acetonitrile when exposed to UV radiation. The theoretical calculations were performed at the BLYP/aug-cc-pVDZ level. It was established that the most stable isomer of the compound in the solution is the one with an intramolecular H-bond between the H atom from the carboxylic group and the N atom from the quinoline ring. The major photoprocess is the breaking of the intramolecular H-bond, i.e. the rotation around the Csbnd OH bond of the carboxylic group through the specroscopically active 1ππ* excited state. Rietveld method was applied to refine the crystal structure of the compound. The refinement lead to the following unit cell parameters: a = 9.76754 Å, b = 6.02724 Å, c = 28.11714 Å, β = 90.495°; and a space Group of P 2/c (Z = 4). The cell volume is 1655.23 Å3.

  20. Theoretical study of ionization potentials of N-heterocyclic compounds

    Directory of Open Access Journals (Sweden)

    Liudmyla K. Sviatenko

    2014-12-01

    Full Text Available The ability to predict the redox properties is an important tool for study electron transfer processes occurring in the gas-phase (atmospheric chemistry or in the condensed phase (electrochemistry, biochemistry. MPWB1K/6-31+G(d and MPWB1K/tzvp theoretical models were found to provide reasonable accuracy of the prediction of ionization potentials for mono- and polycyclic azacompounds. The root mean square errors of the methods are 0.19 and 0.20, respectively. While the mean absolute deviation for both methods is the same and equals to 0.15 eV. These theoretical models were applied to predict ionization potentials for compounds not evaluated experimentally. Influence of substitutes and a number of nitrogen atoms on value of ionization potential was analyzed. Methyl-, and phenyl- groups, and fused benzo cycle decrease ionization potentials of N-heterocycles. Increase of amount of nitrogen atoms in five-membered cycles leads to significant enlargement of ionization potentials.

  1. Theoretical Study on Sulfur Dioxide Absorption with Citrate Solution

    Institute of Scientific and Technical Information of China (English)

    薛娟琴; 洪涛; 王召启; 李林波

    2006-01-01

    The citrate absorption of SO2 is currently one of the most successful and economic methods to harness sulfur dioxide pollution.In order to theoretically elucidate the mechanism of SO2 absorption by citrate solution and provide theoretical instruction for experiments and industrial process, the theory of multi-buffer solution, combined with computer numerical calculation methods, was applied to study the distribution parameters of the components of the citrate solution in the process of SO2 absorption and the following results were obtained: (1) HCi2- and H2Ci- in the citrate solution played the dominant role in the absorption and desorption processes; (2) Through the calculation for the buffer capacity of citrate solution, it was found that the pH of the absorption and desorption solution should be in the range of 2~8, while at pH=4.5 the buffer capacity reached its maximum. Some valuable parameters were obtained, which are instructive to the ensuing experiments and industrial design.

  2. Comparative experimental and theoretical investigations of the DM neutron moisture probe

    DEFF Research Database (Denmark)

    Ølgaard, Povl Lebeck; Haahr, Vagner

    1967-01-01

    Theoretical and experimental investigations of the Danish produced DM subsurface moisture probe have been carried out at the Research Establishment Risö, and the results obtained are presented in this paper. The DM probe contains an Am-Be fast neutron source and has a glass scintillator containi...

  3. Frequencies Shift in Relativistic Binary System (Theoretical Study)

    Science.gov (United States)

    El Fady Morcos, Abd

    2016-07-01

    A generalized formula for Kermack, McCrea and Whittaker (KMW), has been derived by the author and et al., to study the limb effect of massive rapidly rotating stars. In this work a modified Curzon exact solution for Einstein's field equations has been used to study the variation in the frequencies of signals' carriers from a relativistic binary system. The primary star is assumed to be massive with respect to the secondary one. The center of mass is considered to be coincident to the center of rotating polar coordinate system. The rotation of the secondary star around the primary star and Earth's observer rotates with the Earth are considered in our calculation. A general theoretical formula for the variation in the frequencies of the signals' carriers from a binary system is obtained

  4. A Combined Theoretical and Experimental Study for Silver Electroplating

    Science.gov (United States)

    Liu, Anmin; Ren, Xuefeng; An, Maozhong; Zhang, Jinqiu; Yang, Peixia; Wang, Bo; Zhu, Yongming; Wang, Chong

    2014-01-01

    A novel method combined theoretical and experimental study for environmental friendly silver electroplating was introduced. Quantum chemical calculations and molecular dynamic (MD) simulations were employed for predicting the behaviour and function of the complexing agents. Electronic properties, orbital information, and single point energies of the 5,5-dimethylhydantoin (DMH), nicotinic acid (NA), as well as their silver(I)-complexes were provided by quantum chemical calculations based on density functional theory (DFT). Adsorption behaviors of the agents on copper and silver surfaces were investigated using MD simulations. Basing on the data of quantum chemical calculations and MD simulations, we believed that DMH and NA could be the promising complexing agents for silver electroplating. The experimental results, including of electrochemical measurement and silver electroplating, further confirmed the above prediction. This efficient and versatile method thus opens a new window to study or design complexing agents for generalized metal electroplating and will vigorously promote the level of this research region.

  5. Theoretical study of the thermal decomposition of dimethyl disulfide.

    Science.gov (United States)

    Vandeputte, Aäron G; Reyniers, Marie-Françoise; Marin, Guy B

    2010-10-07

    Despite its use in a wide variety of industrially important thermochemical processes, little is known about the thermal decomposition mechanism of dimethyl disulfide (DMDS). To obtain more insight, the radical decomposition mechanism of DMDS is studied theoretically and a kinetic model is developed accounting for the formation of all the decomposition products observed in the experimental studies available in literature. Thermochemical data and rate coefficients are obtained using the high-level CBS-QB3 composite method. Among five methods tested (BMK/6-311G(2d,d,p), MPW1PW91/6-311G(2d,d,p), G3, G3B3, and CBS-QB3), the CBS-QB3 method was found to reproduce most accurately the experimental standard enthalpies of formation for a set of 17 small organosulfur compounds and the bond dissociation energies for a set of 10 sulfur bonds. Enthalpies of formation were predicted within 4 kJ mol(-1) while the mean absolute deviation on the bond dissociation enthalpies amounts to 7 kJ mol(-1). From the theoretical study, a new reaction path is identified for the formation of carbon disulfide via dithiirane (CH(2)S(2)). A reaction mechanism was constructed containing 36 reactions among 25 species accounting for the formation of all the decomposition products reported in literature. High-pressure limit rate coefficients for the 36 reactions in the reaction mechanism are presented. The kinetic model is able to grasp the experimental observations. With the recombination of thiyl radicals treated as being in the low-pressure limit, the experimentally reported first-order rate coefficients for the decomposition of DMDS are reproduced within 1 order of magnitude, while the observed product selectivities of most compounds are reproduced satisfactory. Simulations indicate that at high conversions most of the carbon disulfide forms according to the newly identified reaction path involving the formation of dithiirane.

  6. A regional comparative analysis of empirical and theoretical flood peak-volume relationships

    Directory of Open Access Journals (Sweden)

    Szolgay Ján

    2016-12-01

    Full Text Available This paper analyses the bivariate relationship between flood peaks and corresponding flood event volumes modelled by empirical and theoretical copulas in a regional context, with a focus on flood generation processes in general, the regional differentiation of these and the effect of the sample size on reliable discrimination among models. A total of 72 catchments in North-West of Austria are analysed for the period 1976–2007. From the hourly runoff data set, 25 697 flood events were isolated and assigned to one of three flood process types: synoptic floods (including long- and short-rain floods, flash floods or snowmelt floods (both rain-on-snow and snowmelt floods. The first step of the analysis examines whether the empirical peak-volume copulas of different flood process types are regionally statistically distinguishable, separately for each catchment and the role of the sample size on the strength of the statements. The results indicate that the empirical copulas of flash floods tend to be different from those of the synoptic and snowmelt floods. The second step examines how similar are the empirical flood peak-volume copulas between catchments for a given flood type across the region. Empirical copulas of synoptic floods are the least similar between the catchments, however with the decrease of the sample size the difference between the performances of the process types becomes small. The third step examines the goodness-of-fit of different commonly used copula types to the data samples that represent the annual maxima of flood peaks and the respective volumes both regardless of flood generating processes (the traditional engineering approach and also considering the three process-based classes. Extreme value copulas (Galambos, Gumbel and Hüsler-Reiss show the best performance both for synoptic and flash floods, while the Frank copula shows the best performance for snowmelt floods. It is concluded that there is merit in treating flood

  7. Experimental and theoretical study of metal combustion in oxygen flows

    CERN Document Server

    El-Rabii, Hazem; Muller, Maryse

    2016-01-01

    The effects of oxygen flow speed and pressure on the iron and mild steel combustion are investigated experimentally and theoretically. The studied specimens are vertical cylindrical rods subjected to an axial oxygen flow and ignited at the upper end by laser irradiation. Three main stages of the combustion process have been identified experimentally: (1) Induction period, during which the rod is heated until an intensive metal oxidation begins at its upper end; (2) Static combustion, during which a laminar liquid "cap" slowly grows on the upper rod end; and, after the liquid cap detachment from the sample, (3) Dynamic combustion, which is characterized by a rapid metal consumption and turbulent liquid motions. An analytical description of these stages is given. In particular, a model of the dynamic combustion is constructed based on the turbulent oxygen transport through the liquid metal-oxide flow. This model yields a simple expression for the fraction of metal burned in the process, and allows one to calcul...

  8. Theoretical study on alkaline hydrolysis of trinitrotoluene: later steps

    Directory of Open Access Journals (Sweden)

    Liudmyla K. Sviatenko

    2015-10-01

    Full Text Available Alkaline hydrolysis is an effective method to destroy such the pollutant as 2,4,6-trinitrotoluene (TNT in solution and in well-mixed soil. The mechanism of hydrolytic transformation of polynegative complex, which is one of the products of early stages of TNT hydrolysis, was theoretically investigated at the SMD(Pauling/M06-2X/6-31+G(d,p level under alkali condition. The studied process consists of more than twenty steps and includes a six-membered cycle cleavage and sequenced [1,3]-hydrogen migration and C-C bond rupture. The highest energy barrier is observed for interaction of nitromethanide with hydroxide. The most exothermic steps are C–C bonds breaking. As a result final products such as formate, acetate, ammonium, and nitrogen are formed.

  9. Theoretical study of disorder induced magnetoresistance in graphene

    Science.gov (United States)

    Adam, Shaffique; Ping, Jinglei; Yudhistira, Indra; Ramakrishnan, Navneeth; Cho, Sungjae; Fuhrer, Michael S.

    2014-03-01

    In this work we predict theoretically that carrier density inhomogeneity provides a new mechanism for classical magnetoresistance. For concreteness, we study the case of graphene where density inhomogeneity and carrier scattering is dominated by charged impurities, although the mechanism itself is quite general and applies to other systems in which there are large spatial fluctuations of the carrier density. Calculations using an effective medium approximation show that low-field magnetoresistance becomes a universal function of the ratio between the average carrier density and the fluctuations of the carrier density, and scales as a power-law when this ratio is large. Our finding is in excellent agreement with recent experimental results. This work is supported by the Singapore National Research Foundation NRF-NRFF2012-01.

  10. Field-Theoretic Studies of Nanostructured Triblock Polyelectrolyte Gels

    Science.gov (United States)

    Audus, Debra; Fredrickson, Glenn

    2012-02-01

    Recently, experimentalists have developed nanostructured, reversible gels formed from triblock polyelectrolytes (Hunt et al. 2011, Lemmers et al. 2010, 2011). These gels have fascinating and tunable properties that reflect a heterogeneous morphology with domains on the order of tens of nanometers. The complex coacervate domains, aggregated oppositely charged end-blocks, are embedded in a continuous aqueous matrix and are bridged by uncharged, hydrophilic polymer mid-blocks. We report on simulation studies that employ statistical field theory models of triblock polyelectrolytes, and we explore the equilibrium self-assembly of these remarkable systems. As the charge complexation responsible for the formation of coacervate domains is driven by electrostatic correlations, we have found it necessary to pursue full ``field-theoretic simulations'' of the models, as opposed to the familiar self-consistent field theory approach. Our investigations have focused on morphological trends with mid- and end-block lengths, polymer concentration, salt concentration and charge density.

  11. Theoretical Study on Reaction Mechanism of Aluminum-Water System

    Institute of Scientific and Technical Information of China (English)

    Yun-lan Sun; Yan Tian; Shu-fen Li

    2008-01-01

    A theoretical study on the reaction of aluminum with water in the gas phase was performed using the hybrid density functional B3LYP and QCISD(T) methods with the 6-311+G(d,p) and the 6-311++G(d,p) basis sets. The results show that there are three possible reaction pathways that involve four isomers, seven transition structures, and two possible products for the reaction of aluminum with water. The two most favorable reaction pathways were found, whose intermediates and products agreed quite well with experimental results. The enthalpy and Gibbs free energy change of the reaction between AI and H2O at 298 and 2000 K were calculated. Some results are also in good agreement with the previous calculations or experimental results.

  12. Theoretical study of irradiation effects in close binaries

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao M.

    2009-01-01

    Full Text Available The effect of irradiation is studied in a close binary system assuming that the secondary component is a point source, moving in a circular orbit. The irradiation effects are calculated on the atmosphere of the primary component in a 3-dimensional Cartesian coordinate geometry. In treating the reflection effect theoretically, the total radiation (ST is obtained as the sum of the radiation of 1 the effect of irradiation on the primary component which is calculated by using one dimensional rod model (Sr and 2 the self radiation of the primary component which is calculated by using the solution of radiative transfer equation in spherical symmetry (Ss. The radiation field is estimated along the line of sight of the observer at infinity. It is shown how the radiation field changes depending on the position of the secondary component.

  13. Theoretical Study of Irradiation Effects in Close Binaries

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao, M.

    2009-06-01

    Full Text Available The effect of irradiation is studied in a close binary systemassuming that the secondary component is a point source, moving in a circularorbit. The irradiation effects are calculatedon the atmosphere of the primary component in a 3-dimensional Cartesiancoordinate geometry. In treating the reflection effect theoretically, the totalradiation $(S_mathrm{T}$ is obtained as the sum of the radiation of 1 the effect ofirradiation on the primary component which is calculated by using onedimensional rod model $(S_mathrm{r}$ and 2 the self radiation of the primarycomponent which is calculated by using the solution of radiative transferequation in spherical symmetry $(S_mathrm{s}$. The radiation field is estimated alongthe line of sight of the observer at infinity. It is shown how the radiationfield changes depending on the position of the secondary component.

  14. Electrochemistry of chlorogenic acid: experimental and theoretical studies

    Energy Technology Data Exchange (ETDEWEB)

    Namazian, Mansoor [Department of Chemistry, Yazd University, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of)]. E-mail: namazian@yazduni.ac.ir; Zare, Hamid R. [Department of Chemistry, Yazd University, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of)

    2005-08-10

    Cyclic voltammetry, chronoamperometry and rotating disk electrode voltammetry as well as quantum chemical methods, are used for electrochemical study of chlorogenic acid, as an important biological molecule. The standard formal potential, diffusion coefficient, and heterogeneous electron transfer rate constant of chlorogenic acid in aqueous solution are investigated. Acidic dissociation constant of chlorogenic acid is also obtained. Quantum mechanical calculations on oxidation of chlorogenic acid in aqueous solution, using density functional theory are presented. The change of Gibbs free energy and entropy of oxidation of chlorogenic acid are calculated using thermochemistry calculations. The calculations in aqueous solution are carried out with the use of polarizable continuum solvation method. Theoretical standard electrode potential of chlorogenic acid is achieved to be 0.580 V versus standard calomel electrode (SCE) which is in agreement with the experimental value of 0.617 V obtained experimentally in this work. The difference is consistent with the values we previously reported for other quinone derivatives.

  15. Theoretical studies on Santilli's intermediate nuclear fusions without radiations

    Science.gov (United States)

    Cai, Wei

    2012-09-01

    Experiments of intermediate controlled nuclear fusion are strongly supported by theoretical study. First, current investigation based on quantum mechanics has proved that under super-strong magnetic field, which can be produced by a sudden large current of arc, the wave function of electron cloud changes from a spherical shape to a toroidal shape, which explores nuclear of atom. Second, hadronic mechanics shows that when a trigger, for example, a sudden change of arc, pushes two explored nucleus into a distance of 10-13 cm, a non-unitary, non-linear and nonpotential interaction, introduced by Santilli, leads two nucleus strongly attract each other, while the effective mass of nucleus being renormalized and becomes larger, which leads to a new view of structure of nucleus and results to new types of nuclear fusion.

  16. Biofuel: a comparative case study

    OpenAIRE

    Siddiqui, Aamir; Kading, Christopher; Carter, Kasey

    2013-01-01

    Approved for public release; distribution is unlimited This project analyzes the governments role in the commercialization of biofuel by comparing biofuel commercialization efforts to those of nuclear power and nanotechnology commercialization. The PESTEL framework is applied to nuclear power and nanotechnology to identify key factors relevant to successful commercialization. These success factors are compared to current government biofuel policies to infer the likelihood of successful bio...

  17. A comparative theoretical-experimental analysis of settlements of shallow foundations on granular soil

    OpenAIRE

    Davidović Nebojša; Bonić Zoran; Prolović Verka; Mladenović Biljana; Stojić Dragoslav

    2010-01-01

    The paper presents a brief description of experiment within the research project 'Theoretical and experimental analysis of interaction of shallow reinforced concrete foundations and soil for the purpose of improvement of national regulations and implementaation of Eurocode system' where in situ tests of a series of reinforced concrete foundation footing were performed, by loading until failure. As a rule, methods for calculation of shallow foundations settlement on granular soils overestimate...

  18. Theoretical and Numerical Study of Nonlinear Phononic Crystals

    Science.gov (United States)

    Guerder, Pierre-Yves

    This work is dedicated to the theoretical and numerical study of nonlinear phononic crystals. The studied nonlinearities are those due to the second (quadratic) and third (cubic) order elastic constants of the materials that constitute the crystals. Nonlinear effects are studied by the means of finite element methods, used to simulate the propagation of an elastic wave through the crystals. A first research project concerns the study of a bone structure, namely the dispersion of elastic waves in a structure composed of collagen and hydroxy apatite alternate constituent layers. Simulations showed that it exists a strong link between bones hydration and their ability to dissipate the energy. The second study relates to an elastic resonator. A structure composed of steel inclusions in a silica matrix shows a switch behavior when the cubic nonlinearities of steel are taken into account. This strong nonlinear effect appears when the amplitude of the incident wave reaches a threshold. A full analytical model is provided. The last study demonstrates the design of composite materials with both strong cubic nonlinearities and weak quadratic nonlinearities. The derivation of the mixing laws of the elastic parameters of a nonlinear material inside a linear one is performed up to order three. Equations show a strong amplification of the nonlinear parameters of the material for some concentrations. Numerical simulations allow to conclude that the above mentioned resonator can be produced.

  19. Theoretical study of excitation energy transfer in DNA photolyase.

    Science.gov (United States)

    Zheng, Xuehe; Garcia, Jorge; Stuchebrukhov, Alexei A

    2008-07-24

    Photolyase (PL) is a DNA repair enzyme which splits UV light-induced thymine dimers on DNA by an electron transfer reaction occurring between the photoactivated FADH(-) cofactor and the DNA dimer in the DNA/PL complex. The crystal structure of the DNA/photolyase complex from Anacystis nidulans has been solved. Here, using the experimental crystal structure, we re-examine the details of the repair electron transfer reaction and address the question of energy transfer from the antenna HDF to the redox active FADH(-) cofactor. The photoactivation of FADH(-) immediately preceding the electron transfer is a key step in the repair mechanism that is largely left unexamined theoretically. An important butterfly thermal motion of flavin is identified in ab initio calculations; we propose its role in the back electron transfer from DNA to photolyase. Molecular dynamics simulation of the whole protein/DNA complex is carried out to obtain relevant cofactor conformations for ZINDO/S spectroscopic absorption and fluorescence calculations. We find that significant thermal broadening of the spectral lines, due to protein dynamics, as well as the alignment of the donor HDF and the acceptor FADH(-) transition dipole moments both contribute to the efficiency of energy transfer. The geometric factor of Förster's dipolar coupling is calculated to be 1.82, a large increase from the experimentally estimated 0.67. Using Förster's mechanism, we find that the energy transfer occurs with remarkable efficiency, comparable with the experimentally determined value of 98%.

  20. Theoretical Study on the Mechanism of Sonogashira Coupling Reaction

    Institute of Scientific and Technical Information of China (English)

    CHEN Li-Ping; HONG San-Guo; HOU Hao-Qing

    2008-01-01

    The mechanism of palladium-catalyzed Sonogashira cross-coupling reaction has been studied theoretically by DFT (density functional theory) calculations. The model system studied consists of Pd(PH3)2 as the starting catalyst complex, phenyl bromide as the substrate and acetylene as the terminal alkyne, without regarding to the co-catalyst and base. Mechanistically and energetically plausible catalytic cycles for the cross-coupling have been identified. The DFT analysis shows that the catalytic cycle occurs in three stages: oxidative addition of phenyl bromide to the palladium center, alkynylation of palladium(II) intermediate, and reductive elimination to phenylacetylene. In the oxidative addition, the neutral and anionic pathways have been investigated, which could both give rise to cis-configured palladium(II) diphosphine intermediate. Starting from the palladium(II) diphosphine intermediate, the only identifiable pathway in alkynylation involves the dissociation of Br group and the formation of square-planar palladium(II) intermediate, in which the phenyl and alkynyl groups are oriented cis to each other. Due to the close proximity of phenyl and alkynyl groups, the reductive elimination of phenylacetylene proceeds smoothly.

  1. Theoretical spectroscopic study of protonated and deuteronated PAHs

    Science.gov (United States)

    Buragohain, Mridusmita; Pathak, Amit

    The study of Polycyclic Aromatic Hydrocarbon (PAH) plays a key role to understand astrophysical environments as they are ubiquitous in the Interstellar Medium (ISM). They account for about 5-10% of carbon budget in the universe and are responsible for the strong IR emission features at 3.3, 6.2, 7.7, 8.6, 11.2 and 12.7mum seen towards most of the interstellar objects including HII regions, reflection nebulae, planetary nebulae, late-type stars, as well as active star-forming regions. These IR features result from the relaxation of vibrationally excited PAHs. As PAHs are stable enough to survive the interstellar conditions, they could possibly be responsible for the enigmatic Diffuse Interstellar Bands (DIBs) which are optical absorption features on the interstellar extinction curve. The fact that interstellar PAHs are more likely to be ions has motivated the study of radical PAHs. Protonated PAHs formed by H(+) addition to neutral parent molecules, denoted as HPAH(+) , are an important form of closed shell PAH cation. Protonated forms show electronic transitions in the visible part of the spectrum where most DIBs are present, whereas neutral forms generally show their strongest electronic transitions in the UV region. We also report quantum chemical calculations on HPAH(+) and DPAH(+) (D(+) attached to PAH) to get the electronic and IR spectra to understand the IR emission and DIB features. A comparison of theoretical spectra with the available experimental spectra has also been carried out.

  2. a correlational study of students 'theoretical and practical ...

    African Journals Online (AJOL)

    Galadanci & Mukhtar

    Moment Correlation Coefficient, the Coefficients of Correlation obtained are ... students' understanding of subjects/courses that have been taught to ... Literature Review ... the theoretical and practical scores of students in some basic science ...

  3. Three theoretical studies of ferroelectric materials in different geometries

    Science.gov (United States)

    Palova, Lucia

    Using a combination of numerical and analytical techniques, I present characterizations of ferroelectric materials in bulk, thin-film and nanostructure geometries. My results have impact on ongoing research and on design for nanodevices. Size-dependent effects in ferroelectrics are important due to their long-range electrostatic interactions; thus their dielectric properties depend on electromechanical boundary conditions. In my first study, I address the effects of strain on the measured properties of thin-film (TF) ferroelectrics. It has been suggested that the observed suppression of many TF dielectric characteristics implies underlying strain gradients in the film. I show that the same effects can be explained by a simpler model with homogeneous strain, and I suggest a "smoking gun" benchtop probe. The quantum paraelectric-ferroelectric transition (QPFT) is the topic of my second study. Using methods including finite-size scaling and self-consistent Gaussian theory, I calculate the classical-quantum crossover in the dielectric susceptbility and the resulting temperature-pressure phase diagram; comparison with current experiment is excellent and predictions are made for future measurements. Here, temperature can be considered a "finite-size effet" in time, and previous results on the QPFT using diagrammatic techniques are recovered and extended using this approach. Recent synthesis of artificially structured oxides with "checkerboard" patterning at the nanoscale has been reported, and this serves as motivation for my third study. Here, I use first-principles methods to characterize an atomic-scale BiFeO3-BiMnO3 nanocheckerboard, and find that it has properties that are distinctive from those of either parent compound. More specifically, it has both a spontaneous polarization and magnetization, and also displays a magnetostructural effect. My work on this prototypical multiferroic nanocheckerboard motivates further theoretical and experimental studies of new

  4. Benchmarked Library Websites Comparative Study

    KAUST Repository

    Ramli, Rindra M.

    2015-01-01

    This presentation provides an analysis of services provided by the benchmarked library websites. The exploratory study includes comparison of these websites against a list of criterion and presents a list of services that are most commonly deployed by the selected websites. In addition to that, the investigators proposed a list of services that could be provided via the KAUST library website.

  5. Theoretical studies of potential energy surfaces and computational methods

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, R. [Argonne National Laboratory, IL (United States)

    1993-12-01

    This project involves the development, implementation, and application of theoretical methods for the calculation and characterization of potential energy surfaces involving molecular species that occur in hydrocarbon combustion. These potential energy surfaces require an accurate and balanced treatment of reactants, intermediates, and products. This difficult challenge is met with general multiconfiguration self-consistent-field (MCSCF) and multireference single- and double-excitation configuration interaction (MRSDCI) methods. In contrast to the more common single-reference electronic structure methods, this approach is capable of describing accurately molecular systems that are highly distorted away from their equilibrium geometries, including reactant, fragment, and transition-state geometries, and of describing regions of the potential surface that are associated with electronic wave functions of widely varying nature. The MCSCF reference wave functions are designed to be sufficiently flexible to describe qualitatively the changes in the electronic structure over the broad range of geometries of interest. The necessary mixing of ionic, covalent, and Rydberg contributions, along with the appropriate treatment of the different electron-spin components (e.g. closed shell, high-spin open-shell, low-spin open shell, radical, diradical, etc.) of the wave functions, are treated correctly at this level. Further treatment of electron correlation effects is included using large scale multireference CI wave functions, particularly including the single and double excitations relative to the MCSCF reference space. This leads to the most flexible and accurate large-scale MRSDCI wave functions that have been used to date in global PES studies.

  6. Experimental and Theoretical Studies on Biologically Active Lanthanide (III) Complexes

    Science.gov (United States)

    Kostova, I.; Trendafilova, N.; Georgieva, I.; Rastogi, V. K.; Kiefer, W.

    2008-11-01

    The complexation ability and the binding mode of the ligand coumarin-3-carboxylic acid (HCCA) to La(III), Ce(III), Nd(III), Sm(III), Gd(III) and Dy(III) lanthanide ions (Ln(III)) are elucidated at experimental and theoretical level. The complexes were characterized using elemental analysis, DTA and TGA data as well as 1H NMR and 13C NMR spectra. FTIR and Raman spectroscopic techniques as well as DFT quantum chemical calculations were used for characterization of the binding mode and the structures of lanthanide(III) complexes of HCCA. The metal—ligand binding mode is predicted through molecular modeling and energy estimation of different Ln—CCA structures using B3LYP/6-31G(d) method combined with a large quasi-relativistic effective core potential for lanthanide ion. The energies obtained predict bidentate coordination of CCA- to Ln(III) ions through the carbonylic oxygen and the carboxylic oxygen. Detailed vibrational analysis of HCCA, CCA- and Ln(III) complexes based on both calculated and experimental frequencies confirms the suggested metal—ligand binding mode. The natural bonding analysis predicts strongly ionic character of the Ln(III)-CCA bonding in the- complexes studied. With the relatively resistant tumor cell line K-562 we obtained very interesting in-vitro results which are in accordance with our previously published data concerning the activity of lanthanide(III) complexes with other coumarin derivatives.

  7. Experimental and Theoretical Studies of Volatile Metal Hydroxides

    Science.gov (United States)

    Myers, Dwight L.; Jacobson, Nathan S.

    2015-01-01

    Modern superalloys used in the construction of turbomachinery contain a wide range of metals in trace quantities. In addition, metal oxides and silicon dioxide are used to form Thermal Barrier Coatings (TBC) to protect the underlying metal in turbine blades. Formation of volatile hydroxides at elevated temperatures is an important mechanism for corrosion of metal alloys or oxides in combustion environments (N. Jacobson, D. Myers, E. Opila, and E. Copland, J. Phys. Chem. Solids 66, 471-478, 2005). Thermodynamic data is essential to proper design of components of modern gas turbines. It is necessary to first establish the identity of volatile hydroxides formed from the reaction of a given system with high temperature water vapor, and then to determine the equilibrium pressures of the species under operating conditions. Theoretical calculations of reaction energies are an important check of experimental results. This presentation reports results for several important systems: Si-O-H, Cr-O-H, Al-O-H, Ti-O-H, and ongoing studies of Ta-O-H.

  8. A theoretical and spectroscopic study of conformational structures of piroxicam

    Science.gov (United States)

    Souza, Kely Ferreira de; Martins, José A.; Pessine, Francisco B. T.; Custodio, Rogério

    2010-02-01

    Piroxicam (PRX) has been widely studied in an attempt to elucidate the causes and mechanisms of its side effects, mainly the photo-toxicity. In this paper fluorescence spectra in non-protic solvents and different polarities were carried out along with theoretical calculations. Preliminary potential surfaces of the keto and enol forms were obtained at AM1 level of theory providing the most stable conformers, which had their structure re-optimized through the B3LYP/CEP-31G(d,p) method. From the optimized structures, the electronic spectra were calculated using the TD-DFT method in vacuum and including the solvent effect through the PCM method and a single water molecule near PRX. A new potential surface was constructed to the enol tautomer at DFT level and the most stable conformers were submitted to the QST2 calculations. The experimental data showed that in apolar media, the solution fluorescence is raised. Based on conformational analysis for the two tautomers, keto and enol, the results indicated that the PRX-enol is the main tautomer related to the drug fluorescence, which is reinforced by the spectra results, as well as the interconvertion barrier obtained from the QST2 calculations. The results suggest that the PRX one of the enol conformers presents great possibility of involvement in the photo-toxicity mechanisms.

  9. THE THEORETICAL STUDY OF ADSORPTION OF METAL IONS ON CHITOSAN

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The interactions between metal ions such as Zn2+, Pb2+, Mn2+, Hg2+, Cd2+, Ni2+ and chitosan have been investigated using the model cluster model method and density functional method. Full optimization and frequency analysis of all cluster models have been performed employing B3LYP hybrid method at 3-21G basis set level except metal ions which were invoked to use effective core potential (ECP) method. The energy changes, and the main structural parameters have been obtained during the theoretical study of the adsorption of metal ions on the chitosan. The calculations showed that the coordination modes of metal ions with chitosan models were different, the geometries of Mn2+, Zn2+, Cd2+, Hg2+, Pb2+ ions coordinated with two nitrogen atoms and two oxygen atoms were distorted tetrahedral, while the square planar structure of Ni2+ coordinated two nitrogen atoms and two oxygen atoms was observed. The heat of reaction between six metal ions and chitosan models showed the order: Mn2+ >Ni2+ >Zn2+ >Pb2+ >Hg2+ >Cd2+, this suggested that the coordination strength of Mn2+ >Ni2+ >Zn2+ >Pb2+ >Hg2+ >Cd2+.

  10. Theoretical Study of the Proton Transfer in Enaminones

    Directory of Open Access Journals (Sweden)

    Rita S. Elias

    2012-01-01

    Full Text Available Problem statement: Hydrogen bonding has a vital rule to unrevealed the nature of many different interactions both in gas phase and condensed media thus it is one of the most important concepts in chemistry. Enaminoes with their ability to form intrahydrogen bonded cheated rings represent one of the suitable compounds to study such concept. Approach: The three possible tautomers of eneminones were fully optimized at several theoretical levels including B3LYP with the 6-31+G(d,p, 6-311++G(d,p and aug-cc-pVDZ basis sets as well as MP2/6-311++G(d,p level of theory. Then a search for the possible transition state between the two most stable tautomers; the ketamine and the enolimine was done at the B3LYP/6-311++G(d,p level of theory. Results: The ketamine is the most stable while the diketo is the less stable within the tautomeric mixture and the proton transfer occurs through a transition state that is energetically resemble the enolimine tautomer. Conclusion: The interconversion of the tautomers is preferable in the enolimine ketamine direction.

  11. Experimental, theoretical, and numerical studies of small scale combustion

    Science.gov (United States)

    Xu, Bo

    Recently, the demand increased for the development of microdevices such as microsatellites, microaerial vehicles, micro reactors, and micro power generators. To meet those demands the biggest challenge is obtaining stable and complete combustion at relatively small scale. To gain a fundamental understanding of small scale combustion in this thesis, thermal and kinetic coupling between the gas phase and the structure at meso and micro scales were theoretically, experimentally, and numerically studied; new stabilization and instability phenomena were identified; and new theories for the dynamic mechanisms of small scale combustion were developed. The reduction of thermal inertia at small scale significantly reduces the response time of the wall and leads to a strong flame-wall coupling and extension of burning limits. Mesoscale flame propagation and extinction in small quartz tubes were theoretically, experimentally and numerically studied. It was found that wall-flame interaction in mesoscale combustion led to two different flame regimes, a heat-loss dominant fast flame regime and a wall-flame coupling slow flame regime. The nonlinear transition between the two flame regimes was strongly dependent on the channel width and flow velocity. It is concluded that the existence of multiple flame regimes is an inherent phenomenon in mesoscale combustion. In addition, all practical combustors have variable channel width in the direction of flame propagation. Quasi-steady and unsteady propagations of methane and propane-air premixed flames in a mesoscale divergent channel were investigated experimentally and theoretically. The emphasis was the impact of variable cross-section area and the flame-wall coupling on the flame transition between different regimes and the onset of flame instability. For the first time, spinning flames were experimentally observed for both lean and rich methane and propane-air mixtures in a broad range of equivalence ratios. An effective Lewis number

  12. Exergy performance of different space heating systems: A theoretical study

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2016-01-01

    Three space heating systems (floor heating with different floor covering resistances, radiator heating with different working temperatures, warm-air heating with and without heat recovery) were compared using a natural gas fired condensing boiler as the heat source. For the floor heating systems......, the effects of floor covering resistance on the whole system performance were studied using two heat sources; a natural gas fired condensing boiler and an air-source heat pump. The heating systems were also compared in terms of auxiliary exergy use for pumps and fans. The low temperature floor heating system...

  13. Theoretical study of the unimolecular dissociation of HCO

    Science.gov (United States)

    Whittier, Gregory Scott

    This thesis offers a detailed theoretical study of the unimolecular dissociation of formyl radical, HCO, which is an important intermediate in combustion chemistry. A quantum mechanical treatment of the dissociation of isolated HCO is presented along with a mixed quantum/classical study of the excitation and deexcitation of HCO in collisions of HCO with the bath gas Ar. The results are then used to model the kinetics of the collision-induced dissociation of HCO by Ar. Resonance states of HCO are calculated for total angular momentum J = 0, 1, and 3 using the artificial boundary inhomogeneity (ABI) method of Jang and Light [J. Chem. Phys. 102, 3262 (1995)]. Resonance energies and widths are determined by analyzing the Smith lifetime matrix. A resonance search algorithm and a method for resolving overlapping resonances are described. The accurate prediction of J = 3 resonances from J = 0 and 1 data is tested with good results for excited stretch resonance and less accurate results for bending resonances, demonstrating the degree of separability of vibration from overall rotation for these quasi-bound states. A quantum/classical time-dependent self-consistent field (Q/C TDSCF) approach is used to simulate the dynamics of collisions of Ar with HCO. State-to-state cross sections and thermal rate constants for vibrational transitions are presented. Using this model together with assumptions about the rotational energy transfer and a master equation treatment of the kinetics, the low-pressure thermal rate of collision-induced dissociation was calculated over the 300-4000 K temperature range. Comparison with experiment shows good agreement at high temperatures and poor agreement at low temperatures. The high temperature results were sufficient to obtain an Arrhenius expression for the rate that agrees with all experimental results of which we are aware.

  14. The theoretical studies of piezoresistive effect in diamond films

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the Fuchs and Sondheimer thin film theory (F-S film theory) and a revised valence band split-off model, considering a mixed scattering by lattice vibrations, ionized impurities and surfaces, a theoretical description of the piezoresistive effect (PR effect) in p-type heteroepitaxial diamond films was presented by solving the Boltzmann transport equation in the relaxation time approximation and using the parallel connection resistance model. A calculating expression of the PR effect was given. The main characteristics that were identical with the experiment were obtained by theoretical calculation. Giving out a model to show that the energy level interval between the split-off band and the heavy-hole band was changed by strain, a reasonable explanation was presented for the error between experimental results and theoretical values of saturated PR effect under big strain.

  15. Theoretical Study of the Compound Parabolic Trough Solar Collector

    Directory of Open Access Journals (Sweden)

    Dr. Subhi S. Mahammed

    2012-06-01

    Full Text Available Theoretical design of compound parabolic trough solar collector (CPC without tracking is presented in this work. The thermal efficiency is obtained by using FORTRAN 90 program. The thermal efficiency is between (60-67% at mass flow rate between (0.02-0.03 kg/s at concentration ratio of (3.8 without need to tracking system.The total and diffused radiation is calculated for Tikrit city by using theoretical equations. Good agreement between present work and the previous work.

  16. Interactions between Antibiotics and Graphene-Based Materials in Water: A Comparative Experimental and Theoretical Investigation.

    Science.gov (United States)

    Zhang, Xuntong; Shen, Jiachun; Zhuo, Ning; Tian, Ziqi; Xu, Peiran; Yang, Zhen; Yang, Weiben

    2016-09-14

    Complex interactions between antibiotics and graphene-based materials determine both the adsorption performance of graphene-based materials and the transport behaviors of antibiotics in water. In this work, such interactions were investigated through adsorption experiments, instrumental analyses and theoretical DFT calculations. Three typical antibiotics (norfloxacin (NOR), sulfadiazine (SDZ) and tetracycline (TC)) and different graphene-based materials (divided into two groups: graphene oxides-based ones (GOs) and reduced GOs (RGOs)) were employed. Optimal adsorption pHs for NOR, SDZ, and TC are 6.2, 4.0, and 4.0, respectively. At corresponding optimal pHs, NOR favored RGOs (adsorption capability: ∼50 mg/g) while SDZ preferred GOs (∼17 mg/g); All adsorbents exhibited similar uptake of TC (∼70 mg/g). Similar amounts of edge carboxyls of both GOs and RGOs wielded electrostatic attraction with NOR and TC, but not with SDZ. According to DFT-calculated most-stable-conformations of antibiotics-adsorbents complexes, the intrinsic distinction between GOs and RGOs was the different amounts of sp(2) and sp(3) hybridization regions: π-π electron donor-acceptor effect of antibiotic-sp(2)/sp(3) and H-bonds of antibiotic-sp(3) coexisted. Binding energy (BE) of the former was larger for NOR; the latter interaction was stronger for SDZ; two species of TC at the optimal pH, i.e., TC(+) and TC(0), possessed larger BE with sp(3) and sp(2) regions, respectively.

  17. A Comparative Study of Actuator Configurations for Satellite Attitude Control

    Directory of Open Access Journals (Sweden)

    Raymond Kristiansen

    2005-10-01

    Full Text Available In this paper a controllability study of different actuator configurations consisting of magnetic torquers, reaction wheels and a gravity boom is presented. The theoretical analysis is performed with use of controllability gramians, and simulation results with the different configurations are presented and compared regarding settling time and power consumption to substantiate the theoretical analysis. A reference model is also introduced to show how the power consumption can he lowered to the same magnitude as when magnetic torquers are used, without degrading the satellite response significantly.

  18. THEORETICAL STUDY (AB INITIO AND DFT METHODS) ON ...

    African Journals Online (AJOL)

    3Division of Computational Physics, Institute for Computational Science, Ton ... 4Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, ... a complex of Al(III) with xylenol orange as an ultra-sensitive colored reagent ..... Husain, A. Pharmaceutical Analysis, Theoretical Basis of Analysis: Complexometric.

  19. A theoretical study of Favorskii reaction stereochemistry. Lessons in torquoselectivity.

    Science.gov (United States)

    Hamblin, Graham D; Jimenez, Raphael P; Sorensen, Ted S

    2007-10-12

    The mechanisms of the chloroenolate-->cyclopropanone step of the "normal" Favorskii rearrangement have been investigated in detail using high-level ab initio calculations. A series of simple alpha-chloroenolates, based on chloroacetone (6), all monomethyl derivatives (7-9), a dimethyl analogue (10), and 1-acetyl-1-chlorocyclohexane (11) was first used to explore and define the basic features of the mechanism, which include the finding of both an "inversion" and a "retention" transition state and that in most cases these arise from separate ground-state conformations of the chloroenolate. These theoretical studies were then extended to an isomeric pair of chloroenolates 1 and 2, the cis- and trans-2-methyl derivatives of 11, which are the reactive intermediates involved in a well-known experimental study carried out by Stork and Borowitz (S-B). Finally, three alpha-chlorocyclohexanone enolate systems 12-14 were studied, since these intermediates have a more restricted enolate geometry. The "inversion" mechanism has been described as an SN2 process but the present results, while supporting a concerted process, is better described as an oxyallyl structure undergoing concerted ring closure. The "retention" mechanism has been described as SN1-like, but the calculations show that this process is also concerted, although much less so, and again involves oxyallyl-like transition-states. The model systems 6-8, 10, and 11 with a potential plane of symmetry have two enantiomeric transition states for inversion and another two for retention of configuration (at the C-Cl center). With 9 and the S-B models 1 and 2, with no symmetry plane, there are a calculated total of four diastereomeric transition states for cyclopropanone ring closure in each case, two for inversion and two for retention. While the transition-state energies calculated for simple chloroenolates favor the inversion process, the S-B models 1 and 2 have almost equal inversion-retention transition-state energies

  20. Generation of pulsed Bessel-Gauss beams using passive axicon-theoretical and experimental studies.

    Science.gov (United States)

    Parsa, Shahrzad; Fallah, Hamid Reza; Ramezani, Mohsen; Soltanolkotabi, Mahmood

    2012-10-20

    We studied the conditions for generating passive Bessel-Gauss beams by using an axicon. We designed an appropriate Gaussian resonator and extracted a quasi-fundamental Gaussian mode from a pulsed Nd:YAG laser pumped by a Xenon flash lamp and measured its parameters, such as propagation factor, divergence angle, and Rayleigh range. Then we generated passive Bessel-Gauss beams using an axicon and investigated their propagation properties, theoretically and experimentally. For example, for the axicon of 1°, the output energy and the Rayleigh range of the generated Bessel-Gauss beams were measured to be 58 mJ and 229.3 mm, respectively. We compared these properties with our results of the Gaussian mode. Finally, by using axicons with different apex angles, and also by changing the beam spot size on the axicon, we generated Bessel-Gauss beams and studied their properties theoretically and experimentally.

  1. Experimental and Theoretical Study for Performance Enhancement of Air Solar Collectors by Using Different Absorbers

    Directory of Open Access Journals (Sweden)

    Ahmed A. Mohammad Saleh

    2016-09-01

    Full Text Available An experimental and theoretical study has been done to investigate the thermal performance of different types of air solar collectors, In this work air solar collector with a dimensions of (120 cm x90 cm x12 cm , was tested under climate condition of Baghdad city with a (43° tilt angel by using the absorber plate (1.45 mm thickness, 115 cm height x 84 cm width, which was manufactured from iron painted with a black matt. The experimental test deals with five types of absorber:- Conventional smooth flat plate absorber , Finned absorber , Corrugated absorber plate, Iron wire mesh on absorber And matrix of porous media on absorber . The hourly and average efficiency of the collectors were investigated for three values of mass flow rates (0.016 kg/s to 0.027 kg/s for each type of collector and then the porosity for the last collector type was tested by changing the porosity of porous media. A typical air solar collector has been studied Theoretically to build a standard software for testing any type of air solar collectors with local weather data . From the experimental study it can be seen by using some obstacle material to the air flow (fins, corrugated absorber plate, iron wire mesh porous media on the absorber could be enhanced the efficiencies not less than 4 % for finned type and 8 % for corrugated and 25 % for mesh and 30 % for porous media comparing with flat plate (smooth collector . Theoretically, the results showed that the collector with high convention heat transfer coefficient porous media has high hourly efficiency about (η = 56 % and iron wire mesh on absorber ( η = 52 % , on the other side the minimum performance occurred in the flat plate absorber (η = 28 %. Comparison of results reveals that the theoretical predictions agree reasonably well with experimental results. And the difference between the theoretical and experimental efficiency in general was between (1─ 15 %.

  2. Exergy performance of different space heating systems: A theoretical study

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2016-01-01

    Three space heating systems (floor heating with different floor covering resistances, radiator heating with different working temperatures, warm-air heating with and without heat recovery) were compared using a natural gas fired condensing boiler as the heat source. For the floor heating systems......, the effects of floor covering resistance on the whole system performance were studied using two heat sources; a natural gas fired condensing boiler and an air-source heat pump. The heating systems were also compared in terms of auxiliary exergy use for pumps and fans. The low temperature floor heating system...... performed better than other systems in terms of exergy demand. The use of boiler as a heat source for a low-exergy floor heating system creates a mismatch in the exergy supply and demand. Although an air-source heat pump could be a better heat source, this depends on the origin of the electricity supplied...

  3. Experiment and Theoretical Analysis Study of ETFE Inflatable Tubes

    Directory of Open Access Journals (Sweden)

    YanLi He

    2014-01-01

    Full Text Available The load bearing capacity of an ETFE (ethylene-tetra-fluoro-ethylene inflatable tube is tested in this paper, and a comparative study of two wrinkling theories, the bifurcation theory and the tension field theory, is carried out for wrinkling analysis of the ETFE inflatable tube. Results obtained from the bifurcation theory and experiment reveal the limitations of tension field theory on the wrinkling analysis. The load-displacement curves of inflatable beams under bending load are obtained and compared with the experimental results; curves obtained using the bifurcation theory show coincidence with experimental curves, but the curves obtained using the tension field theory have noticeable deviations between calculated and experimental results.

  4. AB Initio Protein Tertiary Structure Prediction: Comparative-Genetic Algorithm with Graph Theoretical Methods

    Energy Technology Data Exchange (ETDEWEB)

    Gregurick, S. K.

    2001-04-20

    During the period from September 1, 1998 until September 1, 2000 I was awarded a Sloan/DOE postdoctoral fellowship to work in collaboration with Professor John Moult at the Center for Advanced Research in Biotechnology (CARB). Our research project, ''Ab Initio Protein Tertiary Structure Prediction and a Comparative Genetic algorithm'', yielded promising initial results. In short, the project is designed to predict the native fold, or native tertiary structure, of a given protein by inputting only the primary sequence of the protein (one or three letter code). The algorithm is based on a general learning, or evolutionary algorithm and is called Genetic Algorithm (GAS). In our particular application of GAS, we search for native folds, or lowest energy structures, using two different descriptions for the interactions of the atoms and residues in a given protein sequence. One potential energy function is based on a free energy description, while the other function is a threading potential derived by Moult and Samudrala. This modified genetic algorithm was loosely termed a Comparative Genetic Algorithm and was designed to search for native folded structures on both potential energy surfaces, simultaneously. We tested the algorithm on a series of peptides ranging from 11 to 15 residues in length, which are thought to be independent folding units and thereby will fold to native structures independent of the larger protein environment. Our initial results indicated a modest increase in accuracy, as compared to a standard Genetic Algorithm. We are now in the process of improving the algorithm to increase the sensitivity to other inputs, such as secondary structure requirements. The project did not involve additional students and as of yet, the work has not been published.

  5. The physics of neutrino cross sections: theoretical studies

    CERN Document Server

    Alvarez-Ruso, Luis

    2016-01-01

    The present status of neutrino cross section physics is reviewed focusing on the recent theoretical developments in quasielastic scattering, multi-nucleon contributions to the inclusive scattering and pion production on nucleons and nuclei. A good understanding of these processes is crucial to meet the precision needs of neutrino oscillation experiments. Some of the challenges that arise in the consistent description of MiniBooNE and MINERvA recent data are discussed.

  6. Theoretical Study of Electronic Properties of Carbon Allotropes

    OpenAIRE

    Dral, Pavlo

    2013-01-01

    This doctoral thesis describes theoretical investigations of the different physicochemical and above all electronic properties of numerous already discovered and yet to be synthesized modern carbon allotropes, their model compounds and derivatives. In the last century it was ascertained that carbon is not only the most important chemical element for the existence of living beings, but is also becoming increasingly more important for electronics and especially in recent decades for molecula...

  7. Theoretical study of a melting curve for tin

    Institute of Scientific and Technical Information of China (English)

    Xi Feng; Cai Ling-Cang

    2009-01-01

    The melting curve of Sn has been calculated using the dislocation-mediated melting model with the 'zone-linking method'. The results are in good agreement with the experimental data. According to our calculation, the melting temperature of γ-Sn at zero pressure is about 436 K obtained by the extrapolation of the method from the triple point of Sn. The results show that this calculation method is better than other theoretical methods for predicting the meltingcurve of polymorphic material Sn.

  8. [Theoretical studies in weak, electromagnetic and strong interactions. Attachments

    Energy Technology Data Exchange (ETDEWEB)

    Nandi, S.

    1999-09-01

    The project covered a wide area of current research in theoretical high-energy physics. This included Standard Model (SM) as well as physics beyond the Standard Model. Specific topics included supersymmetry (SUSY), perturbative quantum chromodynamics (QCD), a new weak interaction for the third family (called topflavor), neutrino masses and mixings, topcolor model, Pade approximation, and its application to perturbative QCD and other physical processes.

  9. Theoretical Study of First Language Transfer in Second Language Learning

    Institute of Scientific and Technical Information of China (English)

    邱达希

    2015-01-01

    The role and impact offirst language knowledge and how it affects Chinese learners' learning process are significant issues in second language learning.In discussing the role of first language transfer in second language learning,the theoretical understanding of first language transfer will be considered.The next section will go into further detail in the implications and suggestions for teaching and learning English writing and finally conclusions will be drawn from the reading and discussions within this paper.

  10. Theoretical Study of First Language Transfer in Second Language Learning

    Institute of Scientific and Technical Information of China (English)

    邱达希

    2015-01-01

    The role and impact of first language knowledge and how it affects Chinese learners’ learning process are significant issues in second language learning.In discussing the role of first language transfer in second language learning,the theoretical understanding of first language transfer will be considered.The next section will go into further detail in the implications and suggestions for teaching and learning English writing and finally conclusions will be drawn from the reading and discussions within this paper.

  11. Theoretical Studies of Structure, Spectroscopy, and Properties of a New Hydrazine Derivative

    Directory of Open Access Journals (Sweden)

    Hajar Sahebalzamani

    2013-01-01

    Full Text Available We will report a combined experimental and theoretical study on molecular structure, vibrational spectra, and energies of (E-1-(2,4-dinitrophenyl-2-[(4-methylphenylmethylidene]hydrazine (1. The molecular geometry and vibrational frequencies and energies in the ground state are calculated by using HF and DFT levels of theory with 6-311G basis sets. The calculated HOMO and LUMO energies also confirm that charge transfer occurs within the molecule. The harmonic vibrational frequencies were calculated, and the scaled values have been compared with experimental FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar-type spectrograms.

  12. Theoretical studies of 2-quinolinol: Geometries, vibrational frequencies, isomerization, tautomerism, and excited states

    Science.gov (United States)

    Pan, Yi; Lau, Kai-Chung; Al-Mogren, Muneerah Mogren; Mahjoub, Ahmed; Hochlaf, Majdi

    2014-10-01

    We treat theoretically 2-quinolinol(lactam), an analog of carbostyril and DNA bases. We characterized the ground state structure of 2-quinolinol and its isomer(lactim) using density functional theory(DFT). The reaction profile and energetics for lactam-lactim tautomerization and cis-lactim to trans-lactim isomerization predicted with explicitly correlated methods. We explored the pattern of the lowest singlet and triplet manifolds of states and electronic S1 ← S0 transitions using multiconfigurational methodologies. The theoretical results are compared with available experimental data and used to interpret the on-going photoelectron study of 2-quinolinol. Our analysis should help to understand the effect of tautomerism and aromaticity on the DNA bases.

  13. Theoretical and experimental studies of 3β-acetoxy-5α-cholestan-6-one oxime

    Science.gov (United States)

    Khan, Azhar U.; Avecillia, Fernando; Malik, Nazia; Khan, Md. Shahzad; Khan, Mohd Shahid; Mushtaque, Md.

    2016-10-01

    Steroidal oxime (3β-acetoxy-5α-cholestan- 6-one oxime) has been synthesized using microwave-induced reaction in 3.5 min using saturated steroidal ketone and aqueous hydroxylamine hydrochloride in ethanol. The structure of the compound was elucidated by UV, IR, 1H NMR and X-ray single crystal structure. The computational quantum chemical studies like, IR, UV analysis were performed by density functional theory (DFT) at Becke-3-Lee-Yang-Parr(B3LYP) exchange-correlation functional in combination with 6-31++G(d,p) basis sets. The harmonic vibrational frequencies, the optimized geometric parameters have been interpreted and compared with experimental values. Theoretical wavelength at 214.88 cm-1 correspond to the experimental value 214.0 cm-1. The nature of this transition is n → π*. The theoretical results are in good agreement with experiment results.

  14. Theoretical studies of permeability inversion from seismoelectric logs

    Science.gov (United States)

    Hu, H.; Guan, W.; Zhao, W.

    2012-04-01

    Permeability is one of the most important parameters for evaluating the level of difficulty in oil and gas exploitation. A quick, continuous and accurate in-situ estimate of reservoir permeability is highly significant. Stoneley wave logs have been used to determine formation permeability (Tang and Cheng, 1996). However, the inversion errors of this method are too big in low-permeability formations, especially in high-porosity and low-permeability formations resulting from the high clay content in pores. In this study, we propose to invert permeability by using the full waveforms of seismoelectric logs with low frequencies. This method is based on the relationship of permeability with the ratio of the electric excitation intensity to the pressure field's (REP) with respect to the Stoneley wave in seismoelectric logs. By solving the governing equations for electrokinetic coupled wavefields in homogeneous fluid-saturated porous media (Pride, 1994), we calculate the full waveforms of the borehole seismoelectric wavefields excited by a point pressure source and investigate frequency-dependent excitation intensities of the mode waves and excitation intensities of the real branch points in seismoelectric logs. It is found that the REP's phase, which reflects the phase discrepancy between the Stoneley-wave-induced electric field and the acoustic pressure, is sensitive to formation permeability. To check the relation between permeability and REP's phase qualitatively, an approximate expression of the tangent of the REP's argument is derived theoretically as tan(θEP) ≈-ωc/ω = -φη/ (2πfα ∞ρfκ0), where θEPdenotes the arguments of the REP and their principal value is the REP's phase,ω is the angular frequency,ωc is a critical angular frequency that separates the low-frequency viscous flow from the high-frequency inertial flow, φ is the porosity, α∞ is the tortuosity, κ0 is the Darcy permeability, ρf and η are the density and the viscosity of the pore

  15. Theoretical study of ferroelectric nanoparticles using phase reconstructed electron microscopy

    DEFF Research Database (Denmark)

    Phatak, C.; Petford-Long, A. K.; Beleggia, Marco

    2014-01-01

    Ferroelectric nanostructures are important for a variety of applications in electronic and electro-optical devices, including nonvolatile memories and thin-film capacitors. These applications involve stability and switching of polarization using external stimuli, such as electric fields. We present...... a theoretical model describing how the shape of a nanoparticle affects its polarization in the absence of screening charges, and quantify the electron-optical phase shift for detecting ferroelectric signals with phase-sensitive techniques in a transmission electron microscope. We provide an example phase shift...

  16. Theoretical study of the dipole moment of oxygen monofluoride (OF)

    Science.gov (United States)

    Langhoff, S. R.; Bauschlicher, C. W., Jr.; Partridge, H.

    1983-01-01

    The ground-state potential curve and dipole-moment function of OF are calculated theoretically using the complete active-space self-consistent-field levels, externally contracted configuration-interaction levels, or multireference (singles plus doubles) configuration-interaction levels. Both an extended Gaussian basis set and a double-zeta-plus-polarization basis set were applied. The results are presented in extensive tables and graphs. Best results are achieved using a large Gaussian basis set and taking the valence-correlation energy into account. It is suggested that OF may best be detected by its laser-magnetic-resonance spectrum in the IR.

  17. Theoretical study of the thermochemistry of chlorine oxyfluorides

    Science.gov (United States)

    Sánchez, Hernán R.; Del Pla, Julián

    2016-10-01

    There is a lack of experimental thermochemical values for most chlorine oxyfluorides. Previous high level theoretical, CCSD(T), results showed uncommonly large errors in the standard heats of formation calculated through the atomization method. We propose that the differences are due to unusually large contributions to energy from higher excitations within the coupled cluster framework, and we tackle the problem by using a calculation scheme based on isodesmic reactions. Our suspicions are supported by results of static correlation diagnostics. Our final recommended values are in better agreement with the experimental data available. Other thermodynamic properties are also calculated.

  18. Synthesis, characterization, investigation of biological activity and theoretical studies of hydrazone compounds containing choloroacetyl group

    Science.gov (United States)

    Cukurovali, Alaaddin; Yilmaz, Engin

    2014-10-01

    In this study, three new hydrazide-hydrazone derivative compounds which contain choloroacetyl group have been synthesized and characterized. In the characterization, spectral techniques such as IR, 1H NMR, 13C NMR and UV-Vis spectroscopy techniques were used. Antibacterial effects of the synthesized compounds were investigated against Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. In the theoretical calculations Gaussian 09 software was used with the DFT/6-311+(d,p) basis set. Experimental X-ray analysis of compounds has not been studied. Theoretical bond lengths of synthesized compounds were compared with experimental bond lengths of a similar compound. Theoretical and experimental bond lengths are in good agreement with R2: 0.896, 0.899 and 0.900 for compounds 1, 2, and 3, respectively. For antibacterial activity, the most effective one was found to be N‧-(4-bromobenzylidene)-2-chloro-N-(4-(3-methyl-3-phenylcyclobutyl)-thiazol-2-yl) acetohydrazide against P.aeroginaosa ATTC 27853, among the studied compounds.

  19. Theoretical study of magnetoelectric effects in noncentrosymmetric and cuprate superconductors

    Science.gov (United States)

    Kashyap, Manoj K.

    A century after the discovery of superconductivity at the lab of Kamerlingh Onnes in 1911, it is noticeable that the phenomenon is quite ubiquitous in nature. In addition to a long list of superconducting alloys and compounds, almost half the elements in the periodic table superconduct. By the late seventies, superconductivity was thought to be well understood. This turned out to be a myth, with the discovery of unconventional superconductors that defied Bardeen-Cooper-Schrieffer (BCS) theory. Cuprates have been the most prominent example among them ever since their discovery in 1986 by Bednorz and Muller. Another example of non-compliance with BCS theory lie among noncentrosymmetric superconductors. In this dissertation, magnetoelectric (ME) effects in these two classes of superconductors have been studied from different perspectives, utilizing Ginzburg-Landau (GL) theory. Even though GL theory was proposed before the BCS theory, it was not given much importance due to its phenomenological nature until Gor'kov proved that it is a limiting form of the microscopic BCS theory. However today, in the absence of any complete microscopic theory to explain superconductivity in unconventional superconductors, Ginzburg-Landau theory is an important tool to move ahead and qualitatively understand the behavior of varied superconducting systems. Noncentrosymmetric superconductors have generated much theoretical interest since 2004 despite been known for long. The absence of inversion symmetry in non- centrosymmetric superconductors allows for extra terms called Lifshitz invariants in the Ginzburg-Landau functional. This leads to magnetoelectric effects that do not exist in centrosymmetric superconductors. One manifestation of this is in the vortex structure in materials with a cubic point group O. In particular, a current is predicted to flow parallel to the applied magnetic field in such a vortex in addition to the usual vortex supercurrents. In this work, we present both

  20. Theoretical Study of Sodium-Water Surface Reaction Mechanism

    Science.gov (United States)

    Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro

    Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using the ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule on the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. It was found that the estimated rate constant of the former was much larger than the latter. The results are the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by Japan Atomic Energy Agency (JAEA) toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR).

  1. Experimental and theoretical studies on visible light attenuation in water

    CERN Document Server

    Simpson, A; Cho, H J; Liu, H

    2014-01-01

    In this study we describe lab experiments on determining the above water reflectance Rrs coefficient, and the water attenuation coefficient Kd for fresh water. Different types of screens (totally absorbent, gray, etc.) were submerged in water (0-0.6 m) and illuminated from outside. The spectral density of the water leaving radiance was measured for different depths. The results were ran by a code which took into account the geometry of the incident irradiation, the geometry of the screen under water, and boundary conditions at the water surface provided by the radiation transfer theory. From the experimental data and our model we obtain the spectral distribution of the attenuation coefficient for fresh water and compared it with other data in literature. These experiments, performed in the Nonlinear Wave Lab at ERAU# represent just a preliminary calibration of the experimental protocol. More tests with water of different degrees of turbidity, and possibly wave filed at the water surface are in progress and wi...

  2. Theoretical studies of the transport property of oligosilane

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The transport mechanisms of four-conjugated systems were comparatively studied by combining ATK and Gaussian 03 calculations.It was found that the charge-doped oligosilane behaved in a different way from the boron doped and phosphorus doped oligosilanes in terms of the transmission property.The charge-doped oligosilane showed almost no conductivity owing to the damage of the electron transfer path by charge-doping.By contrast,the boron doped and phosphorus doped oligosilanes were demonstrated to be good semiconductors and NDR behavior was observed for them.This is a reasonable result after the analysis of the transmission spectra,MPSH states,energy gap,conjugation effect,and scattering effect.

  3. Theoretical study of plasma confinement by magnetic multicusp field

    Science.gov (United States)

    Khalzov, Ivan; Forest, Cary

    2014-10-01

    Plasma confinement in a magnetic multicusp field is studied numerically using both collisional particle-in-cell and isothermal two-fluid MHD codes and tested against the empirical model. The simulation domain is two-dimensional, periodic in one direction and bounded by absorbing boundaries with multicups field in other direction. First, we study the dependence of plasma loss width on plasma parameters and field strength and compare the results with the well-known empirical formula w = 2√{ρeρi } (two hybrid gyro-radius). Our results show that the loss width has the same scaling with magnetic field w ~ 1 / B , but dependence on other plasma parameters does not agree with this formula. Second, we study the plasma flow drive in the cusp region due to electric field applied by discrete electrodes. The electrode positions are optimized for achieving the highest plasma flow. Comparison with available experimental data from Madison Plasma Dynamo Experiment (MPDX) is made. The work is supported by NSF and DoE.

  4. Theoretical Study on Inner Shell Electron Impact Excitation of Lithium

    Institute of Scientific and Technical Information of China (English)

    YANG Ning-Xuan; DONG Chen-Zhong; JIANG Jun

    2009-01-01

    Cross sections for electron impact excitation of lithium from the ground state ls22s to the excited states 1s2s2,1s2p2,1s2snp (n = 2-5),1s2sns (n = 3-5),1s2pns (n = 3-5),and 1s2pnp (n=3-5) are calculated by using a full relativistic distorted wave method.The latest experimental electron energy loss spectra for inner-shell electron excitations of lithium at a given incident electron energy of 2500 eV[Chin.Phys.Lett.25 (2008) 3649]have been reproduced by the present theoretical investigation excellently.At the same time,the structures of electron energy loss spectra of lithium at low incident electron energy are also predicted theoretically,it is found that the electron energy loss spectra in the energy region of 55-57eV show two-peak structures.

  5. Protonation of caffeine: A theoretical and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Bahrami, Hamed [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Tabrizchi, Mahmoud, E-mail: m-tabriz@cc.iut.ac.ir [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Farrokhpour, Hossein [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2013-03-29

    Highlights: ► Protonation of caffeine was examined by ion mobility spectrometry equipped with two ionization sources. ► Experimental and theoretical evidence was collected to assign the observed peaks to caffeine related ionic species. ► A new concept of “internal proton affinity”, the protonation tendency for each atom in a molecule, was defined. - Abstract: Protonation of caffeine was examined by ion mobility spectrometry equipped with two ionization sources, corona discharge (CD) and UV photoionization. Three peaks were observed in ion mobility spectrum by simultaneously running the two ionization sources. Experimental and theoretical evidence was collected to link the observed peaks to caffeine related ionic species. One peak was attributed to the M{sup +} ion while the other two were assigned to different protonated isomers of caffeine. In the case of CD ionization source, it was observed that different sites of caffeine compete for protonation and their relative intensities, depends on the sample concentration as well as the nature of the reactant ions. The new concept of “internal proton affinity” (IPA) was defined to express the tendency of holding the added proton for each atom in a molecule.

  6. Advertisement Analysis: A Comparative Critical Study

    Directory of Open Access Journals (Sweden)

    Noureldin Mohamed Abdelaal

    2014-12-01

    Full Text Available This study aimed at analyzing two advertisements, and investigating how advertisers use discourse and semiotics to make people and customers buy into their ideas, beliefs, or simply their products. The two advertisements analyzed are beauty products which have been selected from internet magazines. The methodology adopted in this study is qualitative method. The first advertisement is analyzed qualitatively in terms of content; there was no focus on a specific theoretical frame work, while the second advertisement analysis is based on Fairclough’s framework, the critical discourse analysis framework.

  7. Theoretical and experimental NMR studies on muscimol from fly agaric mushroom (Amanita muscaria)

    Science.gov (United States)

    Kupka, Teobald; Wieczorek, Piotr P.

    2016-01-01

    In this article we report results of combined theoretical and experimental NMR studies on muscimol, the bioactive alkaloid from fly agaric mushroom (Amanita muscaria). The assignment of 1H and 13C NMR spectra of muscimol in DMSO-d6 was supported by additional two-dimensional heteronuclear correlated spectra (2D NMR) and gauge independent atomic orbital (GIAO) NMR calculations using density functional theory (DFT). The effect of solvent in theoretical calculations was included via polarized continuum model (PCM) and the hybrid three-parameter B3LYP density functional in combination with 6-311++G(3df,2pd) basis set enabled calculation of reliable structures of non-ionized (neutral) molecule and its NH and zwitterionic forms in the gas phase, chloroform, DMSO and water. GIAO NMR calculations, using equilibrium and rovibrationally averaged geometry, at B3LYP/6-31G* and B3LYP/aug-cc-pVTZ-J levels of theory provided muscimol nuclear magnetic shieldings. The theoretical proton and carbon chemical shifts were critically compared with experimental NMR spectra measured in DMSO. Our results provide useful information on its structure in solution. We believe that such data could improve the understanding of basic features of muscimol at atomistic level and provide another tool in studies related to GABA analogs.

  8. Theoretical Studies of the Optoelectronic Properties of Semiconductor Quantum Wells.

    Science.gov (United States)

    Chao, Calvin Yi-Ping

    The valence-band structure of a semiconductor quantum well is calculated based on the multiband effective -mass theory. A unitary transformation is found to diagonalize the six-by-six Luttinger-Kohn Hamiltonian into two three -by-three blocks, making the computation more efficient. With this new formulation, the effect of strain on the band structure is studied systematically for both the compressional and tensile strain. The importance of the coupling between the heavy-hole, light-hole bands and the spin-orbit split -off bands is especially pointed out. The resonant tunneling of holes through a double -barrier structure is investigated using a transfer-matrix technique. It is shown that the strong mixing between the heavy holes and the light holes results in a totally different I-V characteristic from that predicted previously by the parabolic-band model. The exciton equation in momentum space is solved by using a modified Gaussian quadrature method. The exact solutions for a pure-two-dimensional exciton are derived by means of the Mehler-Fock transform, and the accuracy of the quadrature method is checked by comparing the numerical solutions against the exact solutions. A complete theory for quantum-well excitons is developed taking into account the effects of the valence -band mixing and the intersubband Coulomb interaction. Optical absorption spectra are calculated and compared to experimental data. The comparison demonstrates that the theory explains very well the quantum-confined Stark effect, the polarization selection rule, the coupling between the interwell and intrawell excitons in a multiwell structure, and the anticrossing between the ground state of a light-hole exciton and the excited state of a heavy-hole exciton observed experimentally.

  9. Physics studies in Europe; a comparative study

    NARCIS (Netherlands)

    Steenstrup, S; dalle Rose, LFD; Jones, WG; Tugulea, L; van Steenwijk, FJ

    What are the differences and similarities between physics studies at different universities across Europe (here the definition of Europe is broad)? How much does a student have to work to obtain a degree in physics? Questions like those prompted EUPEN (European Physics Education Network) to make a

  10. Protonation of caffeine: A theoretical and experimental study

    Science.gov (United States)

    Bahrami, Hamed; Tabrizchi, Mahmoud; Farrokhpour, Hossein

    2013-03-01

    Protonation of caffeine was examined by ion mobility spectrometry equipped with two ionization sources, corona discharge (CD) and UV photoionization. Three peaks were observed in ion mobility spectrum by simultaneously running the two ionization sources. Experimental and theoretical evidence was collected to link the observed peaks to caffeine related ionic species. One peak was attributed to the M+ ion while the other two were assigned to different protonated isomers of caffeine. In the case of CD ionization source, it was observed that different sites of caffeine compete for protonation and their relative intensities, depends on the sample concentration as well as the nature of the reactant ions. The new concept of "internal proton affinity" (IPA) was defined to express the tendency of holding the added proton for each atom in a molecule.

  11. Theoretical Advanced Study Institute in Elementary Particle Physics

    CERN Document Server

    2017-01-01

    The program will consist of a pedagogical series of lectures and seminars. Lectures will be given over a four-week period, three or four lectures per day, Monday through Friday. The audience will be composed primarily of advanced theoretical graduate students. Experimentalists with a strong background in theory are also encouraged to apply. Some post-doctoral fellows will be admitted, but preference will be given to applicants who will not have received their Ph.D. before 2017. The minimum background needed to get full benefit of TASI is a knowledge of quantum field theory (including RGEs) and familiarity with the Standard Model. Some familiarity with SUSY would be helpful. We hope to provide some subsidy, but students will need partial support from other sources. Rooms, meals, and access to all facilities will be provided at reasonable rates in beautifully located dormitories at the University of Colorado.

  12. A theoretical study of the spheroidal droplet evaporation in forced convection

    Science.gov (United States)

    Li, Jie; Zhang, Jian

    2014-11-01

    In many applications, the shape of a droplet may be assumed to be an oblate spheroid. A theoretical study is conducted on the evaporation of an oblate spheroidal droplet under forced convection conditions. Closed-form analytical expressions of the mass evaporation rate for an oblate spheroid are derived, in the regime of controlled mass-transfer and heat-transfer, respectively. The variation of droplet size during the evaporation process is presented in the regime of shrinking dynamic model. Comparing with the droplets having the same surface area, an increase in the aspect ratio enhances the mass evaporation rate and prolongs the burnout time.

  13. Theoretical Study on the Reaction Mechanism between Dichlorocarbene and Armchair Single-walled Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    LI Rui-Fang; SHANG Zhen-Feng; XU Xiu-Fang; WANG Gui-Chang

    2006-01-01

    The reaction mechanism between CCl2 and armchair single-walled carbon nanotubes (ASWCNTs) (3,3) and (4,4) has been studied by semiempirical AM1 and ab initio methods. The activation barriers of CCl2 adding to ASWCNT (3,3) and (4,4) are computed and compared. The lower barrier of CCl2 forms cycloaddition isomer on (3,3) maybe because the strain energy of (3,3) is larger than that of (4,4). Our theoretical results are consistent with the experimental results.

  14. Theoretical Study of the Opacity for Mixture Materials at High Temperatures

    Institute of Scientific and Technical Information of China (English)

    颜君; 吴泽清; 逄锦桥; 邱玉波

    2002-01-01

    Using a detailed configuration accounting model with term structures treated by the unresolved transition array model, we have extensively investigated the opacities of mixt ure materials. For plasmas at the temperat ure of 250eV and density of 1 g/cm3, our calculated Rosseland mean opacities are in good agreement with other theoretical results. A high increase in the Rosseland mean opacity to 2944 cm2/g is achieved for a multi-element mixture compared to the value of 1729 cm2/g for pure gold. Various mixtures at other plasma conditions are also studied.

  15. Theoretical Study on the Interaction of o-Tetrafluorophenylene Mercury with Ethylene and Acetylene

    Directory of Open Access Journals (Sweden)

    Eduardo A. Castro

    2003-05-01

    Full Text Available The results of a theoretical study on the interaction of o-tetrafluorophenylene mercury with ethylene and acetylene are reported. The AM1 molecular orbital semiempirical method is applied through a complete optimization procedure without any restrictions to find the optimal equilibrium geometries. The comparative capabilities of ethylene and acetylene molecules to form stable complexes with o-tetrafluorophenylene mercury are analyzed and their corresponding bonding features are discussed. Ethylene seems to be capable of forming a molecular complex while acetylene is predicted to be incapable of doing so.

  16. A theoretical study on vomitoxin and its tautomers

    Energy Technology Data Exchange (ETDEWEB)

    Tuerker, Lemi [Middle East Technical University, Department of Chemistry, 06531 Ankara (Turkey)], E-mail: lturker@metu.edu.tr; Guemues, Selcuk [Middle East Technical University, Department of Chemistry, 06531 Ankara (Turkey); Yuezuencue Yil Universitesi, Kimya Boeluemue, 65080 Kampues, Van (Turkey)

    2009-04-15

    In the present work, the structural and electronic properties of vomitoxin (deoxynivalenol, a mycotoxin) and all of its possible tautomers have been investigated by the application of B3LYP/6-31G(d,p) type quantum chemical calculations. According to the results of the calculations, tautomer V{sub 4} has been found to be the most stable one among all the structures both in the gas and aqueous phases. The calculations also indicated that, vomitoxin and V{sub 2} possess the deepest and the highest lying HOMO levels, respectively. Hence, V{sub 2} is to be more susceptible to oxidations than the others. On the other hand, V{sub 5}(S) and vomitoxin have the lowest and the next lowest LUMO energies, respectively. Whereas, V{sub 1} and V{sub 2} possess quite highly lying (within the group) LUMO energy levels which result in comparatively unfavorable reduction potentials. Some important geometrical and physicochemical properties and the calculated IR spectra of the systems have also been reported in the study.

  17. Theoretical study of selective methylation in the synthesis of azithromycin

    Science.gov (United States)

    Duran, Dilek; Aviyente, Viktorya; Baysal, Canan

    2004-01-01

    Azithromycin is a 15-membered macrolide antibiotic which is active in vitro against clinically important gram-negative bacteria. In this study, the selectivity of the methylation mechanism was analyzed computationally on the 2'- OCbz-3'- NMeCbz derivative of azithromycin in vacuum and in DMF. We have shown that the methylation of the hydroxy group on C-6 is energetically unfavorable compared to the other hydroxy groups in vacuum; the softness values further showed that the C-6 anion is not reactive towards CH3I in the methylation mechanism. To understand the effect of the solvent on the methylation process, detailed molecular dynamics simulations were performed in DMF using the anions at the C-4'', C-6, C-11 and C-12 positions. We find the conformations of the anions not to be affected by the presence of the solvent. The radial distribution functions of the solvent molecules around the O- of the anions demonstrate that DMF molecules cluster around the C-6 anion. The relative strength of the anion-solvent interactions reveal that the solvent molecules provide the largest stabilization to the C-6 anion and prevent the methylation at this position. The latter descriptor was found to be an important factor in explaining the experimentally observed selectivity towards the methylation of the C-4'', C-6, C-11 and C-12 anions.

  18. Theoretical design study of the MSFC wind-wheel turbine

    Science.gov (United States)

    Frost, W.; Kessel, P. A.

    1982-01-01

    A wind wheel turbine (WWT) is studied. Evaluation of the probable performance, possible practical applications, and economic viability as compared to other conventional wind energy systems is discussed. The WWT apparatus is essentially a bladed wheel which is directly exposed to the wind on the upper half and exposed to wind through multiple ducting on the lower half. The multiple ducts consist of a forward duct (front concentrator) and two side ducts (side concentrators). The forced rotation of the wheel is then converted to power through appropriate subsystems. Test results on two simple models, a paper model and a stainless steel model, are reported. Measured values of power coefficients over wind speeds ranging from 4 to 16 m/s are given. An analytical model of a four bladed wheel is also developed. Overall design features of the wind turbine are evaluated and discussed. Turbine sizing is specified for a 5 and 25 kW machine. Suggested improvements to the original design to increase performance and performance predictions for an improved WWT design are given.

  19. Shear Behavior of 3D Woven Hollow Integrated Sandwich Composites: Experimental, Theoretical and Numerical Study

    Science.gov (United States)

    Zhou, Guangming; Liu, Chang; Cai, Deng'an; Li, Wenlong; Wang, Xiaopei

    2016-11-01

    An experimental, theoretical and numerical investigation on the shear behavior of 3D woven hollow integrated sandwich composites was presented in this paper. The microstructure of the composites was studied, then the shear modulus and load-deflection curves were obtained by double lap shear tests on the specimens in two principal directions of the sandwich panels, called warp and weft. The experimental results showed that the shear modulus of the warp was higher than that of the weft and the failure occurred in the roots of piles. A finite element model was established to predict the shear behavior of the composites. The simulated results agreed well with the experimental data. Simultaneously, a theoretical method was developed to predict the shear modulus. By comparing with the experimental data, the accuracy of the theoretical method was verified. The influence of structural parameters on shear modulus was also discussed. The higher yarn number, yarn density and dip angle of the piles could all improve the shear modulus of 3D woven hollow integrated sandwich composites at different levels, while the increasing height would decrease the shear modulus.

  20. The Influence Studies in Comparative Literature

    Institute of Scientific and Technical Information of China (English)

    张宏莹

    2010-01-01

    Comparative literature arose in the 19th century,the approach adopted for its influence study has been developed and diversified in different eras,in this article,the influence study in comparative literature through a reading culture is discussed in order to reveal in what aspects the reading culture may cut across the regional border of influence study.

  1. We need theoretical physics approaches to study living systems

    Science.gov (United States)

    Blagoev, Krastan B.; Shukla, Kamal; affil="3" >Herbert Levine,

    2013-08-01

    Living systems, as created initially by the transition from assemblies of large molecules to self-reproducing information-rich cells, have for centuries been studied via the empirical toolkit of biology. This has been a highly successful enterprise, bringing us from the vague non-scientific notions of vitalism to the modern appreciation of the biophysical and biochemical bases of life. Yet, the truly mind-boggling complexity of even the simplest self-sufficient cells, let alone the emergence of multicellular organisms, of brain and consciousness, and to ecological communities and human civilizations, calls out for a complementary approach. In this editorial, we propose that theoretical physics can play an essential role in making sense of living matter. When faced with a highly complex system, a physicist builds simplified models. Quoting Philip W Anderson's Nobel prize address, 'the art of model-building is the exclusion of real but irrelevant parts of the problem and entails hazards for the builder and the reader. The builder may leave out something genuinely relevant and the reader, armed with too sophisticated an experimental probe, may take literally a schematized model. Very often such a simplified model throws more light on the real working of nature....' In his formulation, the job of a theorist is to get at the crux of the system by ignoring details and yet to find a testable consequence of the resulting simple picture. This is rather different than the predilection of the applied mathematician who wants to include all the known details in the hope of a quantitative simulacrum of reality. These efforts may be practically useful, but do not usually lead to increased understanding. To illustrate how this works, we can look at a non-living example of complex behavior that was afforded by spatiotemporal patterning in the Belousov-Zhabotinsky reaction [1]. Physicists who worked on this system did not attempt to determine all the relevant chemical intermediates

  2. Theoretical study on primary reaction of photosynthetic bacteria

    Institute of Scientific and Technical Information of China (English)

    张纯喜; 樊红军; 李良璧; 匡廷云

    1999-01-01

    Theoretical calculation was carried out on the primary electron donor P870 of photosynthetic bacteria. The results show that: (ⅰ) the bimolecular structure of the primary electron donor is more advantageous in energy than monomolecular structure; (ⅱ) the initial configuration of primary electron donor is no longer stable and changes to the configuration with lower energy and chemical reactivity after the charge separation. In the P870, such structural change is completed through the rotation of C3 acetyl, so the oxygen atom of acetyl interacts with the magnesium atom of another bacterio-chlorophyll molecule, and the total energy and chemical reactivity are reduced evidently. It is suggested that the structural change of the primary electron donor is important in preventing the occurrence of charge recombination during the primary reaction and maintaining the high efficiency of the conversion of sun-light to chemical energy. A new mechanism of primary reaction has been proposed, which can give r

  3. Solvothermal synthesis and theoretical study of a polypyridium trimesylate adduct

    Indian Academy of Sciences (India)

    Yulan Zhu; Feng Ma; Kuirong Ma; Li Cao; Lianhua Zhao

    2011-09-01

    The title compound (C9H3O6·C20H17N4)4·0.5H2O 1 was isolated from solvothermal synthesis of 4'-(4-pyridyl)-2,2':6',2'-terpyridine (pytpy) and trimesic acid (1,3,5-benzenetricarboxylic acid, H3BTC). It was characterized by element analysis, IR, TGA, XRD, X-ray single-crystal diffraction, and spectroscopy properties, together with quantum chemistry calculation of spectrum (UV-vis spectra) through the method b3lyp/6-31 t g (d,p) are also investigated. Single-crystal X-ray diffraction shows 1 possesses a 3-D supramolecular network with 1-D six-fold helical double chains built from protonated (H3pytpy)$^{3+}_{n}$ cations and deprotonated (BTC)$^{3−}_{n}$ anions. The maximum of the fluorescent emission bands of 1 is located at 427 nm (ex = 266 nm), with a shoulder at about 390 nm. The result of theoretic calculations confirms that 1 has small HOMO-LUMO energy gap (1.24 eV) and high chemical reactivity.

  4. Theoretical and Experimental Studies of Elementary Particle Physics

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Harold G [Indiana University; Kostelecky, V Alan [Indiana University; Musser, James A [Indiana University

    2013-07-29

    The elementary particle physics research program at Indiana University spans a broad range of the most interesting topics in this fundamental field, including important contributions to each of the frontiers identified in the recent report of HEPAP's Particle Physics Prioritization Panel: the Energy Frontier, the Intensity Frontier, and the Cosmic Frontier. Experimentally, we contribute to knowledge at the Energy Frontier through our work on the D0 and ATLAS collaborations. We work at the Intensity Frontier on the MINOS and NOvA experiments and participate in R&D for LBNE. We are also very active on the theoretical side of each of these areas with internationally recognized efforts in phenomenology both in and beyond the Standard Model and in lattice QCD. Finally, although not part of this grant, members of the Indiana University particle physics group have strong involvement in several astrophysics projects at the Cosmic Frontier. Our research efforts are divided into three task areas. The Task A group works on D0 and ATLAS; Task B is our theory group; and Task C contains our MINOS, NOvA, and LBNE (LArTPC) research. Each task includes contributions from faculty, senior scientists, postdocs, graduate and undergraduate students, engineers, technicians, and administrative personnel. This work was supported by DOE Grant DE-FG02-91ER40661. In the following, we describe progress made in the research of each task during the final period of the grant, from November 1, 2009 to April 30, 2013.

  5. SAR image autofocus by sharpness optimization: a theoretical study.

    Science.gov (United States)

    Morrison, Robert L; Do, Minh N; Munson, David C

    2007-09-01

    Synthetic aperture radar (SAR) autofocus techniques that optimize sharpness metrics can produce excellent restorations in comparison with conventional autofocus approaches. To help formalize the understanding of metric-based SAR autofocus methods, and to gain more insight into their performance, we present a theoretical analysis of these techniques using simple image models. Specifically, we consider the intensity-squared metric, and a dominant point-targets image model, and derive expressions for the resulting objective function. We examine the conditions under which the perfectly focused image models correspond to stationary points of the objective function. A key contribution is that we demonstrate formally, for the specific case of intensity-squared minimization autofocus, the mechanism by which metric-based methods utilize the multichannel defocusing model of SAR autofocus to enforce the stationary point property for multiple image columns. Furthermore, our analysis shows that the objective function has a special separble property through which it can be well approximated locally by a sum of 1-D functions of each phase error component. This allows fast performance through solving a sequence of 1-D optimization problems for each phase component simultaneously. Simulation results using the proposed models and actual SAR imagery confirm that the analysis extends well to realistic situations.

  6. Studies in theoretical particle physics. Progress report, 1990--1991

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, D.B.

    1991-07-01

    This proposal focuses on research on three distinct areas of particle physics: (1) Nonperturbative QCD. I tend to continue work on analytic modelling of nonperturbative effects in the strong interactions. I have been investigating the theoretical connection between the nonrelativistic quark model and QCD. The primary motivation has been to understand the experimental observation of nonzero matrix elements involving current strange quarks in ordinary matter -- which in the quark model has no strange quark component. This has led to my present work on understanding constituent (quark model) quarks as collective excitations of QCD degrees of freedom. (2) Weak Scale Baryogenesis. A continuation of work on baryogenesis in the early universe from weak interactions. In particular, an investigation of baryogenesis occurring during the weak phase transition through anomalous baryon violating processes in the standard model of weak interactions. (3) Flavor and Compositeness. Further investigation of a new mechanism that I recently discovered for dynamical mass generation for fermions, which naturally leads to a family hierarchy structure. A discussion of recent past work is found in the next section, followed by an outline of the proposed research. A recent publication from each of these three areas is attached to this proposal.

  7. Structural, vibrational and theoretical studies of L-histidine bromide

    Science.gov (United States)

    Ahmed, A. Ben; Feki, H.; Abid, Y.; Boughzala, H.; Mlayah, A.

    2008-10-01

    This paper presents the results of our calculations of the geometric parameters, vibrational spectra and hyperpolarizability of a non linear optical material, L-histidine bromide. Due to the lack of sufficiently precise information on the geometric structure available in literature, theoretical calculations were preceded by re-determination of the crystal X-ray structure. Single crystals of L-histidine bromide have been grown by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in the non-Centro symmetric space group P2 12 12 1 of the orthorhombic system. Raman spectra have been recorded in the range [200-3500 cm -1]. All observed vibrational bands have been discussed and assigned to normal mode or to combinations and overtones on the basis of our calculations. The optimized geometric bond lengths and bond angles obtained by using HF and DFT (B3LYP and BLYP) show good agreement with the experimental data. Comparison between the measured and the calculated vibrational frequencies indicate that B3LYP is superior to the scaled HF approach for molecular vibrational problems. To investigate microscopic second order non linear optical properties of L-histidine bromide, the electric dipole μ, the polarizability α and the hyperpolarizability β were computed using DFT//B3LYP/6-31G(d) method. According to our calculations, the title compound exhibits non-zero β value revealing microscopic second order NLO behaviour.

  8. A Theoretical Study on Reductive Debromination of Polybrominated Diphenyl Ethers

    Directory of Open Access Journals (Sweden)

    Xian-Fei Huang

    2012-07-01

    Full Text Available Recent progress has been made in the reductive debromination of polybrominated diphenyl ethers (PBDEs by nanoscale zero-valent iron (nZVI. To better understand the mechanism of this reaction, seven selected BDE congeners and their anions were investigated at the density functional theory (DFT level using four different methods, including B3LYP/6-31G(d, B3LYP/6-31+G(d, B3LYP/6-31G(d,p and B3LYP/6-311G(d,p. The cleaved C–Br bonds observed in the equilibrium structures of anionic PBDEs were adopted as the probe of the susceptible debromination position of PBDEs in the presence of nZVI, and the proposed major reaction pathways based on our calculations can satisfactorily conform to the reported experimental results. The debromination preference is theoretically evaluated as meta-Br > ortho-Br > para-Br. In addition, both the calculated frontier orbital energies and adiabatic electronic affinities were found to be highly related to their experimental reductive debromination rate constants. The highest linear regression coefficient was observed in the case using the energy of lowest unoccupied molecular orbital as the molecular descriptor obtained from B3LYP/6-31G(d (R2 = 0.961, n = 7 or B3LYP/6-31G(d,p (R2 = 0.961, n = 7. The results clearly showed the evidence of an electron transfer mechanism associated with this reductive debromination reaction.

  9. Theoretical Studies of Dielectronic Recombination of Aluminum-Like Ions

    Science.gov (United States)

    Gorczyca, Tom; Abdel Naby, S. A.; Nikolic, D.; Badnell, N. R.; Savin, D. W.

    2008-05-01

    Dielectronic recombination (DR) is an important process occurring in astrophysical plasmas. DR is responsible for the charge state balance as well as the cooling of astrophysical plasmas, and it is the dominant electron-ion recombination process in both photoionized and collisionally-ionized plasmas. Accurate and reliable calculations for DR rate coefficients are needed to analyze the spectra obtained from astrophysical observations. Over the past few years, our group has computed reliable DR data for all isoelectronic sequences up through Mg-like ions using a state-of-the-art multiconfiguration Breit-Pauli (MCBP) distorted wave method. Recently, we have focused our work on the complex third-row M-shell isoelectronic sequences, especially Al-like. Although there exist some DR calculations for S IV, those were performed only within a non-relativistic LS-coupling approximation and for higher temperatures more suitable for collisionally-ionized plasmas but not for the lower temperatures appropriate for photoionized plasmas. Fe XIV DR calculations have been completed and tested against the Heidelberg heavy-ion Test Storage Ring facility measurements. MCBP cross sections and rate coefficients of a wide range of Al-like ions, computed using the AUTOSTRUCTURE suite of atomic structure and collision codes, will be presented. The effect of fine structure splitting in the ground state will be discussed, and comparisons against all available data, theoretical as well as experimental, will be shown. Our results are fitted into a simple formula for easier implementation into modeling codes used by the astrophysics community. This work was funded in part by NASA (APRA), NASA (SHP) SR&T, and UK PPARC grants.

  10. Theoretical and computational studies of small jammed systems

    Science.gov (United States)

    Gao, Guo-Jie Jason

    We focus on static and slowly driven granular materials modeled as frictionless, spherical grains that interact via soft, purely repulsive contact forces. This thesis will be organized into three related projects. First, we employ simulations to generate MS disk packings using an algorithm where we successively grow or shrink the particles isotropically and minimize the total energy at each step until particles are just at contact. We focus on small systems and are able to enumerate nearly all of the possible MS packings. We found several remarkable features of the frequency distribution. For example, the frequency grows exponentially with increasing packing fraction. In addition, distinct mechanically stable packings within do occur with frequencies that differ by orders of magnitude, which contradicts the equal-probability assumption of Edwards' and other statistical mechanical descriptions. In the second project, we enumerate and classify nearly all of the possible mechanically stable (MS) packings of bidipserse mixtures of frictionless disks in small sheared systems. We find that MS packings form continuous geometrical families, where each family is defined by its particular network of particle contacts. We also monitor the dynamics of MS packings along geometrical families by applying quasistatic simple shear strain at zero pressure. For small numbers of particles, we find that the dynamics is deterministic and highly contracting. In studies with N > 16, we observe an increase in the period and random splittings of the trajectories caused by bifurcations in configuration space. We argue that the ratio of the splitting and contraction rates in large systems will determine the distribution of MS-packing geometrical families visited in steady-state. Finally, we perform simulations of sedimenting frictionless disks to generate mechanically stable (MS) packings in small 2D systems and compare these results to similarly designed experiments. In both experiments and

  11. Model-theoretic Optimization Approach to Triathlon Performance Under Comparative Static Conditions – Results Based on The Olympic Games 2012

    Directory of Open Access Journals (Sweden)

    Michael Fröhlich

    2013-10-01

    Full Text Available In Olympic-distance triathlon, time minimization is the goal in all three disciplines and the two transitions. Running is the key to winning, whereas swimming and cycling performance are less significantly associated with overall competition time. A comparative static simulation calculation based on the individual times of each discipline was done. Furthermore, the share of the discipline in the total time proved that increasing the scope of running training results in an additional performance development. Looking at the current development in triathlon and taking the Olympic Games in London 2012 as an initial basis for model-theoretic simulations of performance development, the first fact that attracts attention is that running becomes more and more the crucial variable in terms of winning a triathlon. Run times below 29:00 minutes in Olympic-distance triathlon will be decisive for winning. Currently, cycle training time is definitely overrepresented. The share of swimming is considered optimal.

  12. Theoretical studies on the reaction pathways of electronically excited DAAF

    Energy Technology Data Exchange (ETDEWEB)

    Quenneville, Jason M [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory

    2009-01-01

    an explosive compound. Here we describe high level quantum chemistry calculations aimed at mapping the electronic states involved in excitation of 3,3{prime}-Diamino-4,4{prime}-azoxyfurazan (DAAF) with 400-nm light. DAAF is a high-nitrogen high explosive that is of interest for its relative insensitivity to shock compression. The goal of the theoretical work described here is to determine the competing pathways for radiative and non-radiative electronic state quenching in an effort to help guide spectroscopic experiments being conducted in tandem.

  13. Theoretical Studies of the Relaxation Matrix for Molecular Systems

    Science.gov (United States)

    Ma, Qiancheng; Boulet, C.

    2016-06-01

    The phenomenon of collisional transfer of intensity due to line mixing has an increasing importance for atmospheric monitoring. From a theoretical point of view, all relevant information about the collisional processes is contained in the relaxation matrix where the diagonal elements give half-widths and shifts, and the off-diagonal elements correspond to line interferences. For simple systems such as those consisting of diatom-atom or diatom-diatom, accurate fully quantum calculations based on interaction potentials are feasible. However, fully quantum calculations become unrealistic for more complex systems. On the other hand, the semi-classical Robert-Bonamy formalism, which has been widely used to calculate half-widths and shifts for decades, fails in calculating the off-diagonal matrix elements resulting from applying the isolated line approximation. As a result, in order to simulate atmospheric spectra where the effects from line mixing are important, semi-empirical fitting or scaling laws such as the energy corrected sudden (ECS) and the infinite order sudden (IOS) models are commonly used. Recently, we have found that in developing this semi-classical line shape theory, to rely on the isolated line approximation is not necessary. By eliminating this unjustified assumption, and accurately evaluating matrix elements of the exponential operators, we have developed a more capable formalism that enables one not only to reduce uncertainties for calculated half-widths and shifts, but also to calculate the whole relaxation matrix. This implies that we can address the line mixing with the semi-classical theory based on interaction potentials between molecular absorber and molecular perturber. We have applied this formalism for Raman and infrared spectra of linear and asymmetric-top molecules. Recently, the method has been extended into symmetric-tops with inverse symmetry such as the NH3 molecule. Our calculated half-widths of NH3 lines in the νb{1} and the pure

  14. Theoretical Studies of Spectroscopic Line Mixing in Remote Sensing Applications

    Science.gov (United States)

    Ma, Q.; Boulet, C.; Tipping, R. H.

    2015-01-01

    The phenomenon of collisional transfer of intensity due to line mixing has an increasing importance for atmospheric monitoring. From a theoretical point of view, all relevant information about the collisional processes is contained in the relaxation matrix where the diagonal elements give half-widths and shifts, and the off-diagonal elements correspond to line interferences. For simple systems such as those consisting of diatom-atom or diatom-diatom, accurate fully quantum calculations based on interaction potentials are feasible. However, fully quantum calculations become unrealistic for more complex systems. On the other hand, the semi-classical Robert-Bonamy (RB) formalism, which has been widely used to calculate half-widths and shifts for decades, fails in calculating the off-diagonal matrix elements. As a result, in order to simulate atmospheric spectra where the effects from line mixing are important, semi-empirical fitting or scaling laws such as the ECS (Energy-Corrected Sudden) and IOS (Infinite-Order Sudden) models are commonly used. Recently, while scrutinizing the development of the RB formalism, we have found that these authors applied the isolated line approximation in their evaluating matrix elements of the Liouville scattering operator given in exponential form. Since the criterion of this assumption is so stringent, it is not valid for many systems of interest in atmospheric applications. Furthermore, it is this assumption that blocks the possibility to calculate the whole relaxation matrix at all. By eliminating this unjustified application, and accurately evaluating matrix elements of the exponential operators, we have developed a more capable formalism. With this new formalism, we are now able not only to reduce uncertainties for calculated half-widths and shifts, but also to remove a once insurmountable obstacle to calculate the whole relaxation matrix. This implies that we can address the line mixing with the semi-classical theory based on

  15. Theoretical study of the porosity and temperature effects on the shock response of graphitic materials

    Science.gov (United States)

    Bourasseau, Emeric; Pineau, Nicolas; Hebert, David; Soulard, Laurent

    2015-06-01

    The response of graphite, and graphite-like materials, to shock compression have been the subject of numerous experimental studies over a few decades, showing a substantial dependence of the shock properties (Hugoniot curves, transition to diamond, ...) on the initial porosity and granularity of the polycrystalline samples. Theoretical studies of these processes have been enabled only recently, thanks to the development of computationally efficient empirical potentials such as LCBOPII which reproduce accurately the various phases of carbon (graphene, graphite, diamond, liquid carbon) and the few available ab initio data for shock compression of graphite. These studies are restricted to monocrystalline samples which, in the case of graphite, represent a serious approximation to the actual experimental set-ups and may explain the large over-estimation of the graphite/diamond transition pressure (~ 60 GPa vs. 15-25 GPa). In this paper we present a theoretical study on the shock compression of porous graphite by means of Molecular Dynamics and Monte Carlo simulations using the LCBOPII potential. The results are compared to the available experimental data and the role of porosity and temperature on the shock properties and graphite/diamond transition is discussed.

  16. Three dimensional elastoplastic response of compliant fault zones to nearby earthquakes: A theoretic study

    Science.gov (United States)

    Kang, J.; Duan, B.

    2012-12-01

    Response of compliant fault zone to the nearby dynamic rupture is detected by seismic and InSAR observations. Seismic observations of damage to the Landers fault zone by the Hector Mine earthquake suggest that response of fault zones can be inelastic. Recent two dimensional theoretical studies reveal that inelastic response of fault zones results in distinguished features in the surface residual displacement field that can be detected by InSAR images. In this study, we extend the recent theoretical studies to three dimensions, so that we may compare modeling results with InSAR observations in the future. We use a Drucker-Prager criterion to characterize elastoplastic response of rocks to nearby spontaneous dynamic rupture in an inhomogeneous medium that contains a compliant fault zone. A finite element method is used to simulate dynamic rupture and seismic wave propagations in the model. Preliminary results show that 1) depth dependence of plastic strain within the fault zone may have important effects on the surface deformation field, 2) plastic strain near the Earth's surface within the fault zone can occur in both extensional and compressive quadrants of the rupture, which is different from previous two dimensional studies, and 3) the vertical surface residual displacement is enhanced within the fault zone, while is reduced outside of the fault zone.

  17. A Comparative Analysis of Three English Translations of Li Qingzhao ’s Sheng Sheng Man in Two Different Theoretical Frameworks

    Institute of Scientific and Technical Information of China (English)

    SU Zhi-jun

    2016-01-01

    Demanding as it has always been, verse translation is a suitable subject to observe on what ground and how translators make their choices to deal with translation problems. By comparing three different English versions of Li Qingzhao’s Sheng Sheng Man within two dramatically different theoretical frameworks, namely the skopos theory and Walter Benjamin’s theory on pure language, the present study aims at deriving a reflection on the nature of translation as a practice, a closer look at its dy-namic complexity.

  18. Theoretical Study on the Mechanism Properties of a Novel Trans-platinum Antitumor Drug

    Institute of Scientific and Technical Information of China (English)

    HE Qin; ZHOU Li-Xin; ZHANG Zhi-Qiang

    2005-01-01

    The mechanism properties of a novel trans-platinum (with one or two of the normal ammine ligands replaced by the planar nitrogen ligand) antitumor drug were explored by using the B3LYP method in the present paper, and the interaction for the monofunctional adduct on DNA trans-[Pt(NH3)(QUIN)GCl] (QUIN = quinoline, G = guanine) with N-containing ligands has been theoretically studied and compared with that of S-containing ligands. The results show that the N-containing ligands are more preferred in the gas phase. Environment effect has been investigated systematically using the PCM model with a series of dielectric constants ε (4.9, 9.0 and 78.4) and compared to the gas phase result with a similar trend.

  19. THEORETICAL STUDY OF SOLAR COLLECTOR WITH MINI PARABOLIC CONCENTRATOR

    Directory of Open Access Journals (Sweden)

    I TABET

    2013-12-01

    Full Text Available In this paper, numerical modeling and simulation of the thermal behavior of a solar collector vacuum tube with a concentration has been done, the value of adding a system of concentration at the back of the collector and try to increase the amount of solar radiation incident on the collector  in order to obtain high temperatures compared to traditional flat plate collector  and improved their energy performance, this type of collector  being integrated into buildings for domestic hot water, air conditioning and for cooling.

  20. Theoretical studies of acrolein hydrogenation on Au20 nanoparticle

    Science.gov (United States)

    Li, Zhe; Chen, Zhao-Xu; He, Xiang; Kang, Guo-Jun

    2010-05-01

    Gold nanoparticles play a key role in catalytic processes. We investigated the kinetics of stepwise hydrogenation of acrolein on Au20 cluster model and compared with that on Au(110) surface. The rate-limiting step barrier of CC reduction is about 0.5 eV higher than that of CO hydrogenation on Au(110) surface. On Au20 nanoparticle, however, the energy barrier of the rate-determining step for CC hydrogenation turns out to be slightly lower than the value for the CO reduction. The selectivity difference on the two substrate models are attributed to different adsorption modes of acrolein: via the CC on Au20, compared to through both CC and CO on Au(110). The preference switch implies that the predicted selectivity of competitive hydrogenation depends on substrate model sensitively, and particles with more low-coordinated Au atoms than flat surfaces are favorable for CC hydrogenation, which is in agreement with experimental result.

  1. Bending of the calmodulin central helix : A theoretical study

    NARCIS (Netherlands)

    VanderSpoel, D; DeGroot, BL; Hayward, S; Berendsen, HJC; Vogel, HJ

    1996-01-01

    The crystal structure of calcium-calmodulin (CaM) reveals a protein with a typical dumbbell structure. Various spectroscopic studies have suggested that the central linker region of CaM, which is alpha-helical in the crystal structure, is flexible in solution. In particular, NMR studies have indicat

  2. Theoretical studies of non inductive current drive in compact toroids

    NARCIS (Netherlands)

    Farengo, R; Lifschitz, AF; Caputi, KI; Arista, NR; Clemente, RA

    2002-01-01

    Three non inductive current drive methods that can be applied to compact toroids axe studied. The use of neutral beams to drive current in field reversed configurations and spheromaks is studied using a Monte Carlo code that includes a complete ionization package and follows the exact particle orbit

  3. Freezing of bentonite. Experimental studies and theoretical considerations

    Energy Technology Data Exchange (ETDEWEB)

    Birgersson, Martin; Karnland, Ola; Nilsson, Ulf (Clay Technology AB, Lund (Sweden))

    2010-01-15

    During its lifetime, a KBS-3 repository will be subject to various ambient temperatures. Backfilled tunnels, shafts and investigation bore holes closest to ground level will experience periods of temperature below 0 deg C. From a safety assessment perspective, it is therefore essential to understand the behavior of compacted bentonite below 0 deg C. A theoretical framework for predicting the pressure response in compacted water saturated bentonite due to temperature changes has been developed based on thermodynamics and a single pore-type. This model predicts an approximately linear temperature dependence of swelling pressure P{sub s}(w,DELTAT) = P{sub s}(w,0 deg C) + DELTAs(w)DELTAT/nu{sub clay}(w) where DELTAT denotes a temperature difference from 0 deg C, DELTAs(w) is the difference in partial molar entropy between clay water and bulk water, nu{sub clay} (w) is the partial molar volume of the clay water and w denotes the water/solid mass ratio of the clay. As bulk water changes phase at 0 deg C, DELTAs(w) has a different value dependent on whether DELTAT is negative or positive. Above 0 deg C DELTAs(w) is a small value for all relevant densities which means that the pressure response due to temperature changes is small. A further consequence of this fact is that DELTAs(w) is a large positive number below 0 deg C when the external water phase is transformed to ice. Consequently, the model predicts a large drop of swelling pressure with temperature below 0 deg C, in the order of 1.2 MPa/deg C. Specifically, the swelling pressure is zero at a certain (negative) temperature T{sub C}. T{sub C} also quantifies the freezing point of the bentonite sample under consideration, as ice formation in the bentonite does not occur until swelling pressure is lost. A large set of laboratory tests have been performed where fully water saturated samples of bentonites have been exposed to temperatures in the range -10 deg C to +25 deg C. The swelling pressure response has been

  4. Freezing of bentonite. Experimental studies and theoretical considerations

    Energy Technology Data Exchange (ETDEWEB)

    Birgersson, Martin; Karnland, Ola; Nilsson, Ulf (Clay Technology AB, Lund (Sweden))

    2010-01-15

    During its lifetime, a KBS-3 repository will be subject to various ambient temperatures. Backfilled tunnels, shafts and investigation bore holes closest to ground level will experience periods of temperature below 0 deg C. From a safety assessment perspective, it is therefore essential to understand the behavior of compacted bentonite below 0 deg C. A theoretical framework for predicting the pressure response in compacted water saturated bentonite due to temperature changes has been developed based on thermodynamics and a single pore-type. This model predicts an approximately linear temperature dependence of swelling pressure P{sub s}(w,DELTAT) = P{sub s}(w,0 deg C) + DELTAs(w)DELTAT/nu{sub clay}(w) where DELTAT denotes a temperature difference from 0 deg C, DELTAs(w) is the difference in partial molar entropy between clay water and bulk water, nu{sub clay} (w) is the partial molar volume of the clay water and w denotes the water/solid mass ratio of the clay. As bulk water changes phase at 0 deg C, DELTAs(w) has a different value dependent on whether DELTAT is negative or positive. Above 0 deg C DELTAs(w) is a small value for all relevant densities which means that the pressure response due to temperature changes is small. A further consequence of this fact is that DELTAs(w) is a large positive number below 0 deg C when the external water phase is transformed to ice. Consequently, the model predicts a large drop of swelling pressure with temperature below 0 deg C, in the order of 1.2 MPa/deg C. Specifically, the swelling pressure is zero at a certain (negative) temperature T{sub C}. T{sub C} also quantifies the freezing point of the bentonite sample under consideration, as ice formation in the bentonite does not occur until swelling pressure is lost. A large set of laboratory tests have been performed where fully water saturated samples of bentonites have been exposed to temperatures in the range -10 deg C to +25 deg C. The swelling pressure response has been

  5. Theoretical study of adsorption of tabun on calcium oxide clusters

    Science.gov (United States)

    Michalkova, A.; Paukku, Y.; Majumdar, D.; Leszczynski, J.

    2007-04-01

    Interactions of tabun (GA) with non-hydroxylated and hydroxylated CaO clusters have been studied using density functional (DFT) and Møller-Plesset second order perturbation (MP2) levels of theory. The nature of interactions has been further investigated from the topology of charge distribution (using Atoms in Molecules formalism) and molecular electrostatic potential (MEP) surfaces. These adsorption studies indicate that GA adsorbs strongly on the non-hydroxylated CaO cluster through its P dbnd O bond, while interactions of GA on the hydroxylated cluster are weak. These model studies could thus be useful to characterize inorganic oxides for efficient detection and disposal of GA.

  6. Theoretical and Experimental Studies of Magneto-Rayleigh-Taylor Instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Yue Ying [University of Michigan, Ann Arbor, MI (United States); Gilgenbach, Ronald [University of Michigan, Ann Arbor, MI (United States)

    2013-07-07

    Magneto-Rayleigh-Taylor instability (MRT) is important to magnetized target fusion, wire-array z-pinches, and equation-of-state studies using flyer plates or isentropic compression. It is also important to the study of the crab nebula. The investigators performed MRT experiments on thin foils, driven by the mega-ampere linear transformer driver (LTD) facility completed in their laboratory. This is the first 1-MA LTD in the USA. Initial experiments on the seeding of MRT were performed. Also completed was an analytic study of MRT for a finite plasma slab with arbitrary magnetic fields tangential to the interfaces. The effects of magnetic shear and feedthrough were analyzed.

  7. Experimental and Theoretical Studies of Pressure Broadened Alkali-Metal Atom Resonance Lines

    Science.gov (United States)

    Shindo, F.; Zhu, C.; Kirby, K.; Babb, J. F.

    2006-01-01

    We are carrying out a joint theoretical and experimental research program to study the broadening of alkali atom resonance lines due to collisions with helium and molecular hydrogen for applications to spectroscopic studies of brown dwarfs and extrasolar giant planets.

  8. Quantum theoretical study of hydrogen under high pressure

    CERN Document Server

    Biermann, S

    2001-01-01

    In the first chapter we will review our knowledge of the phase diagram of hydrogen. Chapter 2 is a summary of the standard density functional and molecular dynamics methods and shows how these are combined in the Car-Parrinello method. Here the nuclei are still treated as classical particles obeying Newtonian mechanics. In chapter 3 we drop this approximation. The path integral description of quantum statistics is added on top of the classical Car-Parrinello method and yields a formalism that includes quantum effects due to the finite de Broglie wavelength of the nuclei. Some technical aspects, namely the parallel implementation of the Path Integral Car-Parrinello (PICP) method, are discussed in chapter 4. In chapter 5 we present the results of our PICP calculations and compare them with prior calculations using the classical Car-Parrinello method as described in chapter 2.

  9. Thermodynamic properties of cyclohexanamines: Experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Verevkin, Sergey P., E-mail: sergey.verevkin@uni-rostock.de [Department of Physical Chemistry and Department “Science and Technology of Life, Light and Matter”, University of Rostock, Dr-Lorenz-Weg 1, Rostock D-18059 (Germany); Department of Physical Chemistry, Kazan Federal University, Kremlevskaya str. 18, 420008 Kazan (Russian Federation); Emeĺyanenko, Vladimir N. [Department of Physical Chemistry, Kazan Federal University, Kremlevskaya str. 18, 420008 Kazan (Russian Federation)

    2015-05-20

    Highlights: • Vapor pressures of four cyclohexanamine derivatives were measured. • Vaporization enthalpies were derived and compared with the literature. • Thermochemical data tested for consistency using additivity rules and computations. • Contradiction between available liquid phase enthalpies of formation was resolved. • Strength of intra-molecular hydrogen bonding in cyclohexyl-1,2-diamines assessed. - Abstract: Vapor pressures of cyclohexanamine, N-methyl-cyclohexanamine, N,N-dimethyl-cyclohexanamine, and N-cyclohexyl-cyclohexanamine were measured using the transpiration method. Molar enthalpies of vaporization of cyclohexanamine derivatives were derived from vapor pressure temperature dependences. Thermodynamic data on cyclohexanamine derivatives available in the literature were collected and treated uniformly. Consistency of the experimental data was proved with a group- contribution method and quantum-chemical calculations. Evaluated vaporization and formation enthalpies of cyclohexanamine derivatives were recommended for practical thermochemical calculations.

  10. Theoretical Study of Some Nitrososulfamide Compounds with Antitumor Activity

    Directory of Open Access Journals (Sweden)

    Madi Fatiha

    2004-09-01

    Full Text Available The lowest-energy conformations of four 2-chloroethylnitrososulfamides were determined using the MM+ molecular mechanics method as implemented in Hyperchem 6.0. Some of the calculated structural parameters, angles and bonds lengths were compared with the crystal structure data of N-nitroso-N-(2-chloroethyl-N’-sulfamoyl- proline. Using MM+, AM1 and PM3 the anti conformation was predicted to be more stable than the syn conformation in each of these compounds. With these methods we found that the relative energy of the transition state (TS was considerably higher, but with the ab initio method using RHF with minimal basic function STO-3G we found that the syn conformation is predicted to be slightly more stable. The determination of some atomic charges of a selection of atoms on the syn, anti and TS structures of the various compounds provided some details about the nature of the transition state.

  11. Adhesion at WC/diamond interfaces - A theoretical study

    Science.gov (United States)

    Padmanabhan, Haricharan; Rao, M. S. Ramachandra; Nanda, B. R. K.

    2015-06-01

    We investigate the adhesion at the interface of face-centered tungsten-carbide (001) and diamond (001) from density-functional calculations. Four high-symmetry model interfaces, representing different lattice orientations for either side of the interface, are constructed to incorporate different degrees of strain arising due to lattice mismatch. The adhesion, estimated from the ideal work of separation, is found to be in the range of 4 - 7 J m-2 and is comparable to that of metal-carbide interfaces. Maximum adhesion occurs when WC and diamond slabs have the same orientation, even though such a growth induces large epitaxial strain at the interface. From electronic structure calculations, we attribute the adhesion to covalent interaction between carbon p-orbitals as well as partial ionic interaction between the tungsten d- and carbon p-orbitals across the interface.

  12. Adhesion at WC/diamond interfaces - A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Padmanabhan, Haricharan [Department of Engineering Design, Indian Institute of Technology Madras, Chennai – 600036 (India); Rao, M. S. Ramachandra [Department of Physics and Nano-Functional Materials Technology Centre, Indian Institute of Technology Madras, Chennai – 600036 (India); Nanda, B. R. K., E-mail: nandab@iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai – 600036 (India)

    2015-06-24

    We investigate the adhesion at the interface of face-centered tungsten-carbide (001) and diamond (001) from density-functional calculations. Four high-symmetry model interfaces, representing different lattice orientations for either side of the interface, are constructed to incorporate different degrees of strain arising due to lattice mismatch. The adhesion, estimated from the ideal work of separation, is found to be in the range of 4 - 7 J m{sup −2} and is comparable to that of metal-carbide interfaces. Maximum adhesion occurs when WC and diamond slabs have the same orientation, even though such a growth induces large epitaxial strain at the interface. From electronic structure calculations, we attribute the adhesion to covalent interaction between carbon p-orbitals as well as partial ionic interaction between the tungsten d- and carbon p-orbitals across the interface.

  13. theoretical study of physiochemical properties of insulin-like growth ...

    African Journals Online (AJOL)

    dell

    Monte Carlo, Molecular Dynamics and Langevin simulation methods by MM+, AMBER and. OPLS force fields of ... This study has demonstrated that the simple model, which includes an ...... solubility of perfluorobenzene in the supercritical ...

  14. A Comparative Study of Whitman and Frost

    Institute of Scientific and Technical Information of China (English)

    田寨耕

    2014-01-01

    Walt Whitman and Robert Frost are both famous poets in American literary history. They share a great deal in common. This paper attempts to make a study of the two poets by means of comparing their similarities and differences.

  15. Experimental and Theoretical Studies in Hydrogen-Bonding Organocatalysis

    Directory of Open Access Journals (Sweden)

    Matej Žabka

    2015-08-01

    Full Text Available Chiral thioureas and squaramides are among the most prominent hydrogen-bond bifunctional organocatalysts now extensively used for various transformations, including aldol, Michael, Mannich and Diels-Alder reactions. More importantly, the experimental and computational study of the mode of activation has begun to attract considerable attention. Various experimental, spectroscopic and calculation methods are now frequently used, often as an integrated approach, to establish the reaction mechanism, the mode of activation or explain the stereochemical outcome of the reaction. This article comprises several case studies, sorted according to the method used in their study. The aim of this review is to give the investigators an overview of the methods currently utilized for mechanistic investigations in hydrogen-bonding organocatalysis.

  16. Theoretical Studies on N2H+O Reaction

    Institute of Scientific and Technical Information of China (English)

    L(U) Ying-wen; L(U) Wen-cai; SU Zhong-min

    2008-01-01

    The N2H+O potential energy profile was studied at the CCSD(T)/6-311G++(dfp)//MP2/6-311G(d,p) level.Reactions associated with four intermediates(cis-HNNO, trans-HNNO, NNHO, and NNOH) were investigated. The results indicate that N2H+O reaction toward H+N2O is more favored than that toward N2+OH, consistent with previous experimental studies. The pathways for the two reactions are found to go through cis-HNNO, transition state, and finally to the products. The N2H+O→NH+NO reaction was studied in detail. Product NO in such a reaction is likely to occur via cis-HNNO, followed by trans-HNNO, and finally dissociates into NH+NO. These results suggest that N2H+O→NH+NO is an important channel in NO production.

  17. TEBPP: Theoretical and Experimental study of Beam-Plasma-Physics

    Science.gov (United States)

    Anderson, H. R.; Bernstein, W.; Linson, L. M.; Papadopoulos, K.; Kellogg, P. J.; Szuszczewicz, E. P.; Hallinan, T. J.; Leinbach, H.

    1980-01-01

    The interaction of an electron beam (0 to 10 keV, 0 to 1.5 Amp) with the plasma and neutral atmospheres at 200 to 400 km altitude is studied with emphasis on applications to near Earth and cosmical plasmas. The interaction occurs in four space time regions: (1) near electron gun, beam coming into equilibrium with medium; (2) equilibrium propagation in ionosphere; (3) ahead of beam pulse, temporal and spatial precursors; (4) behind a beam pulse. While region 2 is of the greatest interest, it is essential to study Region 1 because it determines the characteristics of the beam as it enters 2 through 4.

  18. Theoretical study of reaction mechanism for NCO + HCNO

    Science.gov (United States)

    Zhang, Weichao; Du, Benni; Feng, Changjun

    2007-07-01

    A detailed quantum chemical study is performed on the mechanism of the NCO + HCNO reaction, which has never been studied by theory. The potential energy surface for this reaction is characterized at the B3LYP/6-311++G(d,p) level of theory, combined with high-level CBS-QB3 single point energy calculation. Four possible product channels have been investigated. From the calculations it can be seen that the formation of HCN + NO + CO is the dominant product channel, while the pathway to products of HCNN + CO 2 is expected to be minor one, and these conclusions are in good agreement with the experimental results.

  19. Generation, structure and reactivity of arynes: A theoretical study

    Indian Academy of Sciences (India)

    Peter G S Dkhar; R H Duncan Lyngdoh

    2000-04-01

    The semiempirical AM1 SCF-MO method is used to study the benzyne mechanism for aromatic nucleophilic substitution of various -substituted chlorobenzenes and 3-chloropyridine. The calculations predict that most of the fixed substituents studied here would induce the formation of 2,3-arynes through their electron-withdrawing resonance or inductive effects. The geometry and electronic structure of the 2,3- and 3,4-arynes investigated here, confirm the generally accepted -benzyne structure postulated for arynes. The sites of nucleophilic addition to arynes as predicted here are in fair agreement with expectation and experimental findings.

  20. CURRICULAR OFFER INFLUENCING STUDENTS’ SATISFACTION: COMPARATIVE STUDY

    OpenAIRE

    Oana DUMITRASCU; Constantin Manuel HILA

    2014-01-01

    The main objective of the study is the determination of students’ satisfaction regarding curricular activities. The study has been accomplished using the qualitative and quantitative research, using the bibliographic study, various secondary sources and different primary sources. The study is developed with a marketing research and accomplished using the survey method. 699 students from four universities have been questioned. Due to a comparative study the University of Applied Sciences Worms...

  1. Theoretical study of cathode surfaces and high-temperature superconductors

    Science.gov (United States)

    Mueller, Wolfgang

    1995-01-01

    Calculations are presented for the work functions of BaO on W, Os, Pt, and alloys of Re-W, Os-W, and Ir-W that are in excellent agreement with experiment. The observed emission enhancement for alloy relative to tungsten dispenser cathodes is attributed to properties of the substrate crystal structure and explained by the smaller depolarization of the surface dipole on hexagonal as compared to cubic substrates. For Ba and BaO on W(100), the geometry of the adsorbates has been determined by a comparison of inverse photoemission spectra with calculated densities of unoccupied states based on the fully relativistic embedded cluster approach. Results are also discussed for models of scandate cathodes and the electronic structure of oxygen on W(100) at room and elevated temperatures. A detailed comparison is made for the surface electronic structure of the high-temperature superconductor YBa2Cu3O7 as obtained with non-, quasi-, and fully relativistic cluster calculations.

  2. Theoretical study of symmetry of flux onto a capsule

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Hao; Wu, Changshu; Zou, Shiyang, E-mail: duan-hao@iapcm.ac.cn [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Pei, Wenbing [Shanghai Institute of Laser Plasma, China Academy of Engineering Physics, Shanghai 201800 (China)

    2015-09-15

    An analytic model to describe the flux asymmetry onto a capsule based on the viewfactor approximation is developed and verified with numerical simulations. By using a nested spheres technique to represent the various sources of flux asymmetry, the model can treat spherically and cylindrically symmetric hohlraums, e.g., cylinder, elliptic, and rugby. This approach includes the more realistic case of frequency-dependent flux asymmetry compared with the more standard frequency-integrated or single-frequency approaches [D. W. Phillion and S. M. Pollaine, Phys. Plasmas 1, 2963 (1994)]. Correspondingly, the approach can be used to assess x-ray preheat asymmetry generated from localized laser absorption in the high-Z hohlraum wall. For spherical hohlraums with 4, 6, or 8 laser entrance holes (LEHs), an optimal configuration of LEHs, laser spot placement, and angle-of-incidence of the single-ringed laser beams is defined. An analogy between minimizing the flux asymmetry onto a capsule and the Thomson problem of point charge placement on a sphere for minimized energy is shown.

  3. Theoretical Study on the Antioxidant Activity of Curcumin

    Institute of Scientific and Technical Information of China (English)

    SUN,You-Min(孙友敏); WANG,Ruo-Xi(王若曦); YUAN,Shi-Ling(苑世领); LIN,Xian-Jie(林宪杰); LIU,Cheng-Bu(刘成卜)

    2004-01-01

    The computational results for curcumin at the B3LYP/6-31G(d,p) level show that the enol form of curcumin is more stable than the diketo form because of an intramolecular hydrogen bond, which extends the conjugation effect in the enol chain, formed in the enol structure. Cis-diketone form can not be obtained, presumably due to the strong repulsion between the carbonyl dipoles aligned in parallel. According to the phenolic O-H bond dissociation enthalpy, curcumin in its most stable form can be suggested to be a relatively good antioxidant. In order to avoid overcoming H-bond interaction and to improve the antioxidant activity of curcumin, a catechol moiety was incorporated into curcumin for designing a novel antioxidant. It is found that the designed molecule is much more efficient to scavenge radical than curcumin, comparable to vitamin E. Moreover, the ionization potential of the designed molecule is similar to that of curcumin, indicating that the designed molecule can not display the prooxidant effect.

  4. Understanding the equatorial ocean : theoretical and observational studies

    NARCIS (Netherlands)

    Rabitti, A.

    2016-01-01

    By means of a variety of approaches, the present study points out the challenges in understanding equatorial ocean dynamics (±2.5º). Standard theory, in fact, fails in accurately describing such a big portion of our ocean. This is mainly because at the equator rotation and density stratification com

  5. Theoretical studies of the dynamics of chemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, A.F. [Argonne National Laboratory, IL (United States)

    1993-12-01

    Recent research effort has focussed on several reactions pertinent to combustion. The formation of the formyl radical from atomic hydrogen and carbon monoxide, recombination of alkyl radicals and halo-alkyl radicals with halogen atoms, and the thermal dissociation of hydrogen cyanide and acetylene have been studied by modeling. In addition, the inelastic collisions of NCO with helium have been investigated.

  6. Theoretical Studies in Chemical Kinetics - Annual Report, 1970.

    Science.gov (United States)

    Karplus, Martin

    1970-10-01

    The research performed includes (a) Alkali-Halide, Alkali-Halide (MX, M’X’) Exchange Reactions; (b) Inversion Problem; (c) Quantum Mechanics of Scattering Processes, (d) Transition State Analysis of Classical Trajectories, (e) Differential Cross Sections from Classical Trajectories; and (f) Other Studies.

  7. Theoretical studies of gene substitution, geographic variation, and speciation

    Energy Technology Data Exchange (ETDEWEB)

    Felsenstein, J.

    1977-07-31

    Brief comments are given on the results of a research program dealing with population genetics of evolutionary processes. The various subjects studied included genetic variation in clines; speciation and disruptive selection; parapatric speciation in clines; macroevolutionary laws in a model ecosystem; migration matrices; lethal allelism; estimation of number of loci in quantitative inheritance; numerical taxonomy methods; and new mutants in Lesch-Nyhan disease.

  8. Theoretical Study of Spin Crossover in 30 Iron Complexes

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta

    2016-01-01

    Spin crossover was studied in 30 iron complexes using density functional theory to quantify the direction and magnitude of dispersion, relativistic effects, zero-point energies, and vibrational entropy. Remarkably consistent entropy−enthalpy compensation was identified. Zero-point energies favor ...

  9. Cognition in Orienteering: Theoretical Perspectives and Methods of Study.

    Science.gov (United States)

    Ottosson, Torgny

    1996-01-01

    Almost without exception, published studies on cognition in orienteering have adopted an information processing perspective involving dualism between objective and subjective worlds. An alternative, experiential framework focuses on the orienteer's conception of (or way of experiencing) the task to be accomplished, and on "affordances" (lines of…

  10. Theoretical study of bone sialoprotein in bone biomineralization

    CSIR Research Space (South Africa)

    Yang, Y

    2011-05-01

    Full Text Available , highly conserved across several vertebrates, are the proposed active sites. We selected one of these sites, i.e. (Sp) 2 E 8 , where Sp represents a phosphoserine as a model peptide to study the role of BSP. We used molecular dynamics simulations...

  11. Theoretical study of solar combisystems based on bikini tanks and tank-in-tank stores

    DEFF Research Database (Denmark)

    Yazdanshenas, Eshagh; Furbo, Simon

    2012-01-01

    Purpose - Low flow bikini solar combisystems and high flow tank-in-tank solar combisystems have been studied theoretically. The aim of the paper is to study which of these two solar combisystem designs is suitable for different houses. The thermal performance of solar combisystems based on the two...... different heat storage types is compared. Design/methodology/approach - The thermal performance of Low flow bikini solar combisystems and high flow tank-in-tank solar combisystems is calculated with the simulation program TRNSYS. Two different TRNSYS models based on measurements were developed and used....... Findings - Based on the calculations it is concluded that low flow solar combisystems based on bikini tanks are promising for low energy buildings, while solar combisystems based on tank-in-tank stores are attractive for the houses with medium heating demand and old houses with high heating demand...

  12. A study of brain networks associated with swallowing using graph-theoretical approaches.

    Directory of Open Access Journals (Sweden)

    Bo Luan

    Full Text Available Functional connectivity between brain regions during swallowing tasks is still not well understood. Understanding these complex interactions is of great interest from both a scientific and a clinical perspective. In this study, functional magnetic resonance imaging (fMRI was utilized to study brain functional networks during voluntary saliva swallowing in twenty-two adult healthy subjects (all females, [Formula: see text] years of age. To construct these functional connections, we computed mean partial correlation matrices over ninety brain regions for each participant. Two regions were determined to be functionally connected if their correlation was above a certain threshold. These correlation matrices were then analyzed using graph-theoretical approaches. In particular, we considered several network measures for the whole brain and for swallowing-related brain regions. The results have shown that significant pairwise functional connections were, mostly, either local and intra-hemispheric or symmetrically inter-hemispheric. Furthermore, we showed that all human brain functional network, although varying in some degree, had typical small-world properties as compared to regular networks and random networks. These properties allow information transfer within the network at a relatively high efficiency. Swallowing-related brain regions also had higher values for some of the network measures in comparison to when these measures were calculated for the whole brain. The current results warrant further investigation of graph-theoretical approaches as a potential tool for understanding the neural basis of dysphagia.

  13. Theoretical studies of GaInNAs for optoelectronic device applications

    CERN Document Server

    Alexandropoulos, D

    2003-01-01

    This thesis focuses on the theoretical analysis of GalnNAs alloys for use in optoelectronic devices. We develop reliable theoretical models that describe the properties of GaInNAs alloys and apply these to establish design rules. We develop a k centre dot p model for the band structure of GaInNAs-based Quantum Wells (QW) that accounts for valence band mixing effects, strain effects and the N induced coupling of the conduction band states of GaInNAs alloys. We implement the model to study the effect of N on the conduction and valence bands. The optical properties of GaInNAs structures are studied and design rules that ensure optimal performance are derived for 1.3 mu m emission. It is established that high N content decreases the differential gain and the Momentum Matrix Element (MME) for TE polarisation while it increases the transparency concentration and the MME for TM polarisation. The material gain and linewidth enhancement factor are found to have comparable values to InGaAsP structures. The effect of al...

  14. Comparative study on direct burning of oil shale and coal

    Science.gov (United States)

    Hammad, Ahmad; Al Asfar, Jamil

    2017-07-01

    A comparative study of the direct burning processes of oil shale and coal in a circulating fluidized bed (CFB) was done in this study using ANSYS Fluent software to solve numerically the governing equations of continuity, momentum, energy and mass diffusion using finite volume method. The model was built based on an existing experimental combustion burner unit. The model was validated by comparing the theoretical results of oil shale with proved experimental results from the combustion unit. It was found that the temperature contours of the combustion process showed that the adiabatic flame temperature was 1080 K for oil shale compared with 2260 K for coal, while the obtained experimental results of temperatures at various locations of burner during the direct burning of oil shale showed that the maximum temperature reached 962 K for oil shale. These results were used in economic and environmental analysis which show that oil shale may be used as alternative fuel for coal in cement industry in Jordan.

  15. Experimental and theoretical studies of nanoparticles of antiferromagnetic materials

    DEFF Research Database (Denmark)

    Mørup, Steen; Madsen, Daniel Esmarch; Frandsen, Cathrine

    2007-01-01

    The magnetic properties of nanoparticles of antiferromagnetic materials are reviewed. The magnetic structure is often similar to the bulk structure, but there are several examples of size-dependent magnetic structures. Owing to the small magnetic moments of antiferromagnetic nanoparticles......, the commonly used analysis of magnetization curves above the superparamagnetic blocking temperature may give erroneous results, because the distribution in magnetic moments and the magnetic anisotropy are not taken into account. We discuss how the magnetic dynamics can be studied by use of magnetization...... nanoparticles is usually negligible, and therefore such particles present a unique possibility to study exchange interactions between magnetic particles. The interactions can have a significant influence on both the magnetic dynamics and the magnetic structure. Nanoparticles can be attached with a common...

  16. Using Defects in Materials to Store Energy: a Theoretical Study

    Science.gov (United States)

    Lu, I.-Te; Bernardi, Marco

    We study the energy stored by defects in materials using density functional theory (DFT) calculations. Leveraging experimental data to estimate the energy density of defects, expressed as the defect formation energy per unit volume (units of MJ/L) or weight (units of MJ/kg), we identify candidates for high energy density storage, including tungsten, diamond, graphite, silicon, and graphene. DFT calculations are applied to these materials to study the formation energy of vacancies, interstitials, and Frenkel pairs. Our results indicate that the energy density stored by defects in these materials, with experimentally accessible non-equilibrium defect concentrations, can be higher than that of common energy storage technologies such as lithium batteries and supercapacitors. We discuss storage of solar energy and electrical energy (through ion bombardment) using defects.

  17. Theoretical study on a Miniature Joule-Thomson & Bernoulli Cryocooler

    Science.gov (United States)

    Xiong, L. Y.; Kaiser, G.; Binneberg, A.

    2004-11-01

    In this paper, a microchannel-based cryocooler consisting of a compressor, a recuperator and a cold heat exchanger has been developed to study the feasibility of cryogenic cooling by the use of Joule-Thomson effect and Bernoulli effect. A set of governing equations including Bernoulli equations and energy equations are introduced and the performance of the cooler is calculated. The influences of some working conditions and structure parameters on the performance of coolers are discussed in details.

  18. The Case Study Approach: Some Theoretical, Methodological and Applied Considerations

    Science.gov (United States)

    2013-06-01

    a large manufacturing organisation in Malaysia . An in- depth case study process (specifically a qualitative approach) was used to illustrate the...researcher closely examined four leaders from generally diverse organisations, who had embraced the learning-organisation concept in order to improve...The researchers focused on the context of learning in the workplace , and they investigated the nature of learning and development opportunities that

  19. Relativistic Multichannel Theory: Theoretical Study of C+ Autoionization States

    Institute of Scientific and Technical Information of China (English)

    XIA Dan; ZHANG Shi-Zhong; PENG Yong-Lun; LI Jia-Ming

    2003-01-01

    Based on relativistic multichannel theory, the autoionization states of C+ are studied. We calculate all the autoionization states in the energy region of 193900 ~ 231700cm"1, and the results are in good agreement with the experimental data. The energy structure we obtain will be important in the dielectronic recombination processes, which plays a key role in determining the abundance of carbon in a nebula.

  20. A theoretical study on ascorbic acid dissociation in water clusters.

    Science.gov (United States)

    Demianenko, Eugeniy; Ilchenko, Mykola; Grebenyuk, Anatoliy; Lobanov, Victor; Tsendra, Oksana

    2014-03-01

    Dissociation of ascorbic acid in water has been studied by using a cluster model. It was examined by density functional theory (DFT) with the В3LYP, M06, and wB97XD functionals and a 6-311++G(d,p) basis set. The thermodynamic and kinetic characteristics of proton transfer from ascorbic acid molecule to water clusters were calculated as well as the equilibrium constants (pK a ) for the related processes. The used functionals in the DFT method together with continuum solvent models provided results close to the experimental data for the dissociation constant of ascorbic acid in aqueous solution.

  1. Role of hot electron transport in scintillators: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Huihui [SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, Key Lab. of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen Univ. (China); Li, Qi [Physical Sciences Division, IBM TJ Watson Research Center, Yorktown Heights, NY (United States); Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL (United States); Lu, Xinfu; Williams, R.T. [Department of Physics, Wake Forest University, Winston Salem, NC (United States); Qian, Yiyang [College of Engineering and Applied Science, Nanjing University (China); Wu, Yuntao [Scintillation Materials Research Center, University of Tennessee, Knoxville, TN (United States)

    2016-10-15

    Despite recent intensive study on scintillators, several fundamental questions on scintillator properties are still unknown. In this work, we use ab-initio calculations to determine the energy dependent group velocity of the hot electrons from the electronic structures of several typical scintillators. Based on the calculated group velocities and optical phonon frequencies, a Monte-Carlo simulation of hot electron transport in scintillators is carried out to calculate the thermalization time and diffusion range in selected scintillators. Our simulations provide physical insights on a recent trend of improved proportionality and light yield from mixed halide scintillators. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Theoretical Study on Catalyst Activation of Palladacycles in Heck Reaction

    Institute of Scientific and Technical Information of China (English)

    WANG Chen; FU Yao; LI Zhe; GUO Qing-Xiang

    2008-01-01

    A computational study with the B3PW91 density functional theory was carried out on the activation process of palladacycles as catalysts in the Heck reaction.Two possible pathways (i.e.anion reductive cleavage of the Pd-C bond,and olefin insertion into the Pd-C bond followed by β-H elimination)were taken into consideration.Computational results indicate that the palladacycles are activated via olefin insertion into the Pd-C bond followed by β-H elimination in the reaction conditions.

  3. Theoretical studies of the reaction e+ e- --> K+ K- gamma

    CERN Document Server

    Lesniak, Leonard

    2016-01-01

    We present studies of the e+ e- --> K+ K- gamma reaction for the e+e- center-of-mass energies close to the phi(1020) meson mass. Different mechanisms leading to the final state are considered. The strong interaction amplitudes of the K+K- pairs in the S-wave are taken into account. In addition, the photon emission in the initial state, the final state radiation effects and all the possible interference terms are included in the transition matrix elements. The K+K- effective mass distributions and the angular dependence of the reaction cross-section are calculated.

  4. THEORETICAL STUDY OF PODOPHYLLOTOXIN AND QUINOLONE ANALOGUES AS ANTITUMOR DRUGS

    Institute of Scientific and Technical Information of China (English)

    何峰; 戴颖仪; 朱孝峰; 黄爱东; 张翎; 颜少平; 刘宗潮

    2002-01-01

    Objective: To study the active sites of podophyllotoxin derivatives. Methods: Some podophyllotoxin derivatives were analyzed by quantum and mechanics method. Results: Some information was given according to the calculation results about HOMO and LUMO electron density. The C-4 position is the position for effective modification. The B ring and E ring are important active centers. Conclusion: The hole of positive charge in B ring easily combines with an acceptor within the molecular. Some quinolones with similar electronic construction to podophyllotoxin may have antitumor activity.

  5. Keto-enol tautomerism in estrogen hormone. A theoretical study

    Science.gov (United States)

    Jameh-Bozorghi, Saeed; Shirani, Hossein; Ghaempanah, Aram; Ghapanvari, Hamed

    2015-01-01

    The HF/6-311+G** calculation was used to investigate Keto-Enol tautomerism of Estrogen Hormone. Molecular geometries of keto, enol and transition state of this reaction were optimized and NBO calculations were performed. These calculation results showed that activation energy (Ea) of Keto-Enol tautomerization of Estrogen is 118.65 Kcal mol-1. Energetic study at B3LYP/6-311+G** level of theory revealed that keto tautomer is more stable structure. NBO analysis results have a good agreements with optimized geometries and experimental data.

  6. A theoretical study on interaction of proline with gold cluster

    Indian Academy of Sciences (India)

    Sandhya Rai; N V Suresh Kumar; Harjinder Singh

    2012-06-01

    Interaction of proline with gold cluster was studied using density functional theory (DFT). Two types of mixed basis sets UB3LYP/6-311++G ∪ LANL2MB and UB3LYP/6-311++G ∪ LANL2DZ were used for optimization of complex structures. Proline interacts with gold cluster either through one anchor bond, N–Au or an anchor bond O–Au associated with a non-conventional O–H…Au hydrogen bond. Among these interactions, higher tendency for interaction is seen with Au cluster through amide terminal. Natural bond orbital analysis (NBO) is used to substantiate the results.

  7. Theoretical and methodological studies of continuous microbial bioreactors.

    Science.gov (United States)

    Toda, Kiyoshi

    2003-08-01

    This article reviews most of the author's studies on process development and reactor design for continuous microbial reactions. (1) Enzyme reactions of growing and non-growing microbial cells immobilized in agar gel beads were analyzed pertaining to the effects of external and internal diffusion of substrate on reaction kinetics. (2) Experimental correlations of production rates of beta-fructosidase and acid phosphatase with dilution rate of continuous culture were simulated based on an operon model for enzyme regulation. (3) Population dynamics of an amylase-producing bacteria and their mutant were discussed in relation to enzyme productivity in a continuous culture of spore-forming bacteria. (4) Plasmid mobilization in a mixed population of donor, recipient, and helper cells was investigated in a continuous culture as a model study of accidental release of a genetically modified plasmid into a natural environment. (5) A production rate increase of up to 100-fold was achieved by cell-recycle culturing of continuous acetic acid fermentation using a filter module with a hollow fiber membrane. (6) The feasibility of a continuous surface culture for the biooxidation of organic substances was ascribed to an enhanced oxygen absorption rate in the presence of a microbial film on a liquid surface. (7) Simultaneous separation of inhibitory products using an electrodialysis module during some organic acid fermentations was effective for increasing production in a continuous culture.

  8. Singlet oxygen reactions with flavonoids. A theoretical-experimental study.

    Directory of Open Access Journals (Sweden)

    Javier Morales

    Full Text Available Detection of singlet oxygen emission, λ(max = 1270 nm, following laser excitation and steady-state methods were employed to measure the total reaction rate constant, k(T, and the reactive reaction rate constant, k(r, for the reaction between singlet oxygen and several flavonoids. Values of k(T determined in deuterated water, ranging from 2.4×10(7 M(-1 s(-1 to 13.4×10(7 M(-1 s(-1, for rutin and morin, respectively, and the values measured for k(r, ranging from 2.8×10(5 M(-1 s(-1 to 65.7×10(5 M(-1 s(-1 for kaempferol and morin, respectively, being epicatechin and catechin chemically unreactive. These results indicate that all the studied flavonoids are good quenchers of singlet oxygen and could be valuable antioxidants in systems under oxidative stress, in particular if a flavonoid-rich diet was previously consumed. Analysis of the dependence of rate constant values with molecular structure in terms of global descriptors and condensed Fukui functions, resulting from electronic structure calculations, supports the formation of a charge transfer exciplex in all studied reactions. The fraction of exciplex giving reaction products evolves through a hydroperoxide and/or an endoperoxide intermediate produced by singlet oxygen attack on the double bond of the ring C of the flavonoid.

  9. Singlet Oxygen Reactions with Flavonoids. A Theoretical – Experimental Study

    Science.gov (United States)

    Morales, Javier; Günther, Germán; Zanocco, Antonio L.; Lemp, Else

    2012-01-01

    Detection of singlet oxygen emission, λmax = 1270 nm, following laser excitation and steady-state methods were employed to measure the total reaction rate constant, kT, and the reactive reaction rate constant, kr, for the reaction between singlet oxygen and several flavonoids. Values of kT determined in deuterated water, ranging from 2.4×107 M−1s−1 to 13.4×107 M−1s−1, for rutin and morin, respectively, and the values measured for kr, ranging from 2.8×105 M−1s−1 to 65.7×105 M−1s−1 for kaempferol and morin, respectively, being epicatechin and catechin chemically unreactive. These results indicate that all the studied flavonoids are good quenchers of singlet oxygen and could be valuable antioxidants in systems under oxidative stress, in particular if a flavonoid-rich diet was previously consumed. Analysis of the dependence of rate constant values with molecular structure in terms of global descriptors and condensed Fukui functions, resulting from electronic structure calculations, supports the formation of a charge transfer exciplex in all studied reactions. The fraction of exciplex giving reaction products evolves through a hydroperoxide and/or an endoperoxide intermediate produced by singlet oxygen attack on the double bond of the ring C of the flavonoid. PMID:22802966

  10. A theoretical study of mechanical stability of arteries.

    Science.gov (United States)

    Rachev, Alexander

    2009-05-01

    This study proposes a mathematical model for studying stability of arteries subjected to a longitudinal extension and a periodic pressure. An artery was considered as a straight composite beam comprised of an external thick-walled tube and a fluid core. The dynamic criterion for stability was used, based on analyzing the small transverse vibrations superposed on the finite deformation of the vessel under static load. In contrast to the case of a static pressurization, in which buckling is only possible if the load produces a critical axial compressive force, a loss of stability of arteries under periodic pressure occurs under many combinations of load parameters. Instability occurs as a parametric resonance characterized by an exponential increase in the amplitude of transverse vibrations over several bands of pressure frequencies. The effects of load parameters were analyzed on the basis of the results for a dynamic and static stability of a rabbit thoracic aorta. Under normal physiological loads the artery is in a stable configuration. Static instability occurs under high distending pressures and low longitudinal stretch ratios. When the artery is subjected to periodic pressure, an independent increase in the mean pressure, amplitude of the periodic pressure, or frequency, most often, but not always, increases the risk of stability loss. In contrary, an increase in longitudinal stretch ratio most likely, but not certain, stabilizes the vessel. It was shown that adaptive geometrical remodeling due to an increase in mean pressure and flow does not affect artery stability.

  11. Theoretical Study of Interplay Between Superconductivity and Itinerant Ferromagnetism

    Directory of Open Access Journals (Sweden)

    Subhra Kakani

    2014-08-01

    Full Text Available Following Green’s function technique and equation of motion method, the coexistence of superconductivity (SC and itinerant ferromagnetism (FM is investigated in a single band homogenous system. Self consistent equations for SC and FM order parameters, Δ and m or I respectively are derived. It is shown that there generally exists a coexistent (Δ ≠ 0, and m or I ≠ 0 solutions to the coupled equations of the order parameter in the, temperature range 0 < T < min(TC, TFM, where TC and TFM are respectively the superconducting and ferromagnetic transition temperatures. Expressions for specific heat, density of states, free energy and critical field are derived. The specific heat has linear temperature dependence as opposed to the exponential decrease in the BCS theory. The density of states for a finite m increases as opposed to that of a ferromagnetic metal. Free energy study reveals that FMSC state has lowest energy than the normal FM state and therefore realized at low enough temperature .Effect of small external field is also studied. The theory is applied to explain the observations in uranium based intermetallics systems UCoGe and UIr. The agreement between theory and experiments is quite encouraging.

  12. Theoretical study about L-arginine complexes formation with thiotriazolin

    Directory of Open Access Journals (Sweden)

    L. I. Kucherenko

    2017-02-01

    Full Text Available Brain vascular diseases are one of the leading causes of morbidity, mortality and disability of population in the industrialized countries of the world. An important element of this problem’s solution is the creation of new highly effective and safe drugs, which would lead to mortality reduction, to increase in life expectancy and quality of life. Therefore it is interesting to create a new combined drug based on L-arginine and thiotriazolin. Purpose of the study: to consider the possible structure and energy characteristics of complexes formed by L-arginine, 3-methyl-1,2,4-triazolyl-5-thioacetate (MTTA and morpholine. Calculation method. The initial approximation to the complex geometry was obtained using molecular docking with the help of AutoDock Vina program. The obtained ternary complexes were pre-optimized by semi-empirical PM7 method with modeling the impact of the environment by COSMO method. The calculations were carried out using MOPAC2012 program. Then they were optimized by B97-D3/SVP + COSMO (Water dispersion-corrected DFT-D with geometrical spreading correction on insufficiency of gCP basis set. A more accurate calculation of the solvation energy was conducted by SMD. The calculations by density functional method were carried out using the ORCA 3.0.3 software. Energy complex formation in solution was calculated as the difference of the Gibbs free energy of the solvated complex and its individual components. Results. Quantum chemical calculations show, that thiotriazolin and L-arginine are able to form ternary complexes, where molecules are linked by multiple hydrogen bonds. The calculation data suggest, that studied complexes are thermodynamically unstable in solution. The energies of them are positive, but rather low despite charge gain of a number of intermolecular hydrogen bonds. Finding. Based on the results of the conducted quantum-chemical study of a three components system (MTTA, morpholine, and L-arginine it is possible

  13. Theoretical Study of Ion Transport in the Gramicidin a Channel

    Science.gov (United States)

    Roux, Benoi T.

    Modern techniques are used to study the permeation process of ions through the gramicidin A channel. The conformation of the gramicidin molecule is investigated experimentally in dimethylsulfoxide/acetone using the techniques of two-dimensional NMR spectroscopy. An empirical energy function is developed from ab initio calculations to represent the interaction of Li^{+}, Na^{+} and K^ {+} ions with the backbone of polypeptides; the parameters are tested in dense systems with free energy simulations. The dynamics of the gramicidin A channel dimer in the absence of water and ions is studied in the harmonic approximation by a vibrational analysis of the atomic motions relative to their equilibrium positions. The behavior of the water molecules in the channel is studied with a molecular dynamics simulation of a fully solvated Gramicidin A dimer embedded in a model membrane. the potential of mean force and the mobility of Na^{+ }, K^{+} and water are calculated in the interior of a gramicidin-like periodic poly (L,D)-alanine beta -helix. The potential of mean force of Na^ {+} ion along the axis of the gramicidin A channel is calculated with a molecular dynamics simulation of a fully solvated Gramicidin A dimer embedded in a model membrane; the gramicidin channel is modeled as a right -handed head-to-head beta-helix dimer. Binding sites are found at the extremities of the channel; no large activation energy barrier is caused by the dehydration process at the entrance of the channel. In the appendices, Statistical Mechanical theories are used to investigate the equilibrium and dynamical properties of the liquid state. A theory of aqueous solutions is used to provide an interpretation for the Born model of ion hydration at the molecular level; the Born radius of hydration is interpreted in terms of the first peak in the solute-solvent radial distribution function. We show that some proposed closures for the RISM equation of Chandler and Andersen possess no solution because

  14. An in-depth analysis of theoretical frameworks for the study of care coordination1

    OpenAIRE

    Van Houdt, Sabine; Heyrman, Jan; Vanhaecht, Kris; Sermeus, Walter; De Lepeleire, Jan

    2013-01-01

    Introduction Complex chronic conditions often require long-term care from various healthcare professionals. Thus, maintaining quality care requires care coordination. Concepts for the study of care coordination require clarification to develop, study and evaluate coordination strategies. In 2007, the Agency for Healthcare Research and Quality defined care coordination and proposed five theoretical frameworks for exploring care coordination. This study aimed to update current theoretical frame...

  15. An in-depth analysis of theoretical frameworks for the study of care coordination

    OpenAIRE

    Sabine Van Houdt; Jan Heyrman; Kris Vanhaecht; Walter Sermeus; Jan De Lepeleire

    2013-01-01

    Introduction: Complex chronic conditions often require long-term care from various healthcare professionals. Thus, maintaining quality care requires care coordination. Concepts for the study of care coordination require clarification to develop, study and evaluate coordination strategies. In 2007, the Agency for Healthcare Research and Quality defined care coordination and proposed five theoretical frameworks for exploring care coordination. This study aimed to update current theoretical fram...

  16. Theoretical Studies on Defects of Kaolinite in Clays

    Institute of Scientific and Technical Information of China (English)

    HE Man-Chao; FANG Zhi-Jie; ZHANG Ping

    2009-01-01

    Using the first-principles methods, we study the formation energetics and charge doping properties of the extrinsic substitutional defects in kaolinite. Especially, we choose Be, Mg, Ca, Fe, Cr, Mn, Cu, Zn as extrinsic defects to substitute for AI atoms. By systematically calculating the impurity formation energies and transition energy levels, we find that all group-Ⅱ defects introduce the relative shallow transition energy levels in kaolinite. Among them, MgAI has the shallowest transition energy leve! at 0.08 eV above the valence band maximum. The transitionelemental defects ReAl, CrAl and MnAl are found to have relative low formation energies, suggesting their easy formation in kaolinite under natural surrounding conditions. Our calculations show that the defects CuAl and ZnAl have the high formation energies and deep transition energy levels, which exclude the possibility of their formation in natural kaolinite.

  17. Theoretical Study on Ion Escape in Martian Atmosphere

    Institute of Scientific and Technical Information of China (English)

    SHI Jian-Kui; LIU Zhen-Xing; Klaus TORKAR; Tielong ZHANG

    2007-01-01

    @@ Based on the observation that Martian magnetic moment is gradually reducing from the ancient to the present,we investigate the O+ ion flux distribution along magnetic field lines and the ion escaping flux in Martian tail with different assumed Martian magnetic moments. The results show that the O+ ion flux along magnetic field lines decreases with distance from Mars; the ion flux along the field line decreases more quickly if the magnetic moment is larger; the larger the magnetic moment, the smaller the ion escaping flux in the Martian tail. The ion escaping flux depends on Z-coordinate in the Martian tail. With decrease of the magnetic moment, the ion escaping flux in the Martian tail increases. The results are significant for studying the water loss from Mars surface.

  18. THEORETICAL STUDY OF THE ABSORPTION SPECTRA OF TRIAMTERENE

    Directory of Open Access Journals (Sweden)

    M. Ramegowda

    2013-03-01

    Full Text Available ABSTRACT: Time dependent density functional theory (TDDFT calculations have been carried out to study the electronic structure and the UV absorption spectra of Triamterene. The UV spectra have been investigated with inclusion of solvent effect. The B3LYP functional with a 6-31G(d, p basis sets have been used to compute absorption energies. The solvent effects have been described within the polarizable continuum model (PCM. The geometries are optimized using density functional theory (DFT with B3LYP functional combined with 6-31G(d, p basis sets. The vertical absorption energies both in gas phase and in polar solvents such as ethanol, methanol and water were computed. Red-shift of the absorption maximum in the polar solvents is discussed in terms of electrostatic interaction energy, oscillator strength and dipole moment.

  19. Study of nonplanarity of peptide bond using theoretical calculations.

    Science.gov (United States)

    Selvarengan, P; Kolandaivel, P

    2005-08-01

    The conformational dependence of nonplanarity of the peptide bond of formylglycinamide has been studied using ab initio and density functional theory methods. Hartree-Fock self-consistent field theory (HF), Møller-Plesset perturbation theory (MP2) of ab initio and B3LYP level of theory of dft method have been used employing 6-31++G** basis set. The MP2 method predicts better results than HF and B3LYP levels of theory for conformational stability dependence of nonplanarity. Systematic dependence of planarity deviation has been observed in MP2 theory. The chemical hardness values successfully predict the conformational region, but fail to obey maximum hardness principle. It is concluded that the most reliable dft method could not successfully predict the planarity of peptide bond in comparison with electron correlated method of ab initio method.

  20. Polymers' surface interactions with molten iron: A theoretical study

    Science.gov (United States)

    Assadi, M. Hussein N.; Sahajwalla, Veena

    2014-10-01

    Environmental concerns are the chief drive for more innovative recycling techniques for end-of-life polymeric products. One attractive option is taking advantage of C and H content of polymeric waste in steelmaking industry. In this work, we examined the interaction of two high production polymers i.e. polyurethane and polysulfide with molten iron using ab initio molecular dynamics simulation. We demonstrate that both polymers can be used as carburizers for molten iron. Additionally, we found that light weight H2 and CHx molecules were released as by-products of the polymer-molten iron interaction. The outcomes of this study will have applications in the carburization of molten iron during ladle metallurgy and waste plastic injection in electric arc furnace.

  1. Hydroxyl radical induced transformation of phenylurea herbicides: A theoretical study

    Science.gov (United States)

    Mile, Viktória; Harsányi, Ildikó; Kovács, Krisztina; Földes, Tamás; Takács, Erzsébet; Wojnárovits, László

    2017-03-01

    Aromatic ring hydroxylation reactions occurring during radiolysis of aqueous solutions are studied on the example of phenylurea herbicides by Density Functional Theory calculations. The effect of the aqueous media is taken into account by using the Solvation Model Based on Density model. Hydroxyl radical adds to the ring because the activation free energies (0.4-47.2 kJ mol-1) are low and also the Gibbs free energies have high negative values ((-27.4) to (-5.9) kJ mol-1). According to the calculations in most of cases the ortho- and para-addition is preferred in agreement with the experimental results. In these reactions hydroxycyclohexadienyl type radicals form. In a second type reaction, when loss of chlorine atom takes place, OH/Cl substitution occurs without cyclohexadienyl type intermediate.

  2. Theoretical Study of Elastic Properties of Tungsten Disilicide

    Institute of Scientific and Technical Information of China (English)

    XU Guo-Liang; ZHANG Dong-Ling; XIA Yao-Zheng; LIU Xue-Feng; LIU Yu-Fang; ZHANG Xian-Zhou

    2009-01-01

    @@ The plane-wave pseudopotential method using the generalized gradient approximation within the framework of density functional theory is applied to analyse the lattice parameters, elastic constants, bulk moduli, shear moduli and Young's moduli of WSi2. The quasi-harmonic Debye model, using a set of total energy versus cell volume obtained with the plane-wave pseudopotential method, is applied to the study of the elastic properties and vibrational effects. The athermal elastic constants of WSi2 are calculated as a function of pressure up to 35 GPa. The relationship between bulk modulus and temperature up to 1200K is also obtained. Moreover, the Debye temperature is determined from the non-equilibrium Gibbs function. The calculated results are in good agreement with the experimental data.

  3. Homogenisation of linear electromagnetic materials. Theoretical and numerical studies

    CERN Document Server

    MacKay, T G

    2001-01-01

    of the real and imaginary parts of the constitutive dyadics do not coincide, is demonstrated. Additionally, orthorhombic biaxial structures are presented which can arise even though the distinguished axes of the component phases are non-orthogonal. Secondly, the strong-property-fluctuation theory (SPFT) is developed for bianisotropic materials, under the bilocal approximation. The SPFT represents a major advance over traditional approaches to homogenisation, such as provided by the Maxwell Garnett and Bruggeman formalisms, by accommodating a more comprehensive description of the distributional statistics of the component phases. In particular, the SPFT takes account of scattering losses and in its zero-order implementation the SPFT reduces to the Bruggeman homogenisation formalism. Detailed numerical studies are presented which highlight the role of the correlation length, as well as the component phase topology and orientation diversity. Also, the choice of covariance function is demonstrated to exert only a...

  4. A theoretical study of radon measurement with activated charcoal

    Science.gov (United States)

    Nikezić, Dragoslav; Urošević, Vlade

    1998-02-01

    Diffusion of radon in a bed of activated charcoal is described by diffusion equations. An analytical solution of these equations is presented for the case of constant radon concentration in the atmosphere. The solutions are given separately for short term and long term exposure. An analytical form of the calibration constant f for long term exposure and constant radon concentration in air, was found to be f=kp {D}/{λ}S {sinh{λ}/{D}l }/{cosh{λ}/{D}l } A numerical method and computer code based on the method of finite elements is developed for the case of variable radon concentration in air. This program simulates radon adsorption by the activated charcoal bed, enabling determination of sensitivity. The dependence of sensitivity on different parameters, such as temperature, thickness of the charcoal, etc. was studied using this program.

  5. Experimental and theoretical studies of the structure and optical properties of nickel phthalocyanine nanowires

    Science.gov (United States)

    Wang, Xiaoyan; Wu, Wei; Ju, Haidong; Zou, Taoyu; Qiao, Zhenfang; Gong, Hao; Wang, Hai

    2016-12-01

    By using organic vapor phase deposition method, nickel phthalocyanines (NiPc) nanowires were successfully prepared, and the effects of heating temperature on the structural and optical properties of NiPc nanowires were investigated. Both the crystal structures of NiPc powders and nanowires are studied by x-ray diffraction patterns (XRD) and Fourier transform infrared spectra (FTIR). The lattice constants of NiPc nanowires from the fitting of XRD patterns are a = 13.04 Å, b = 3.75 Å, c = 24.32 Å, β = 94.10°, belonging to the space group of monoclinic (P21/c). X-ray photo-electron spectroscopy (XPS) suggests main peaks at 284.82 eV and 286.18 eV for C-C and C-N bonds and two peaks at 397.8 eV and 398.8 eV for N-C and the N-Ni bonds, respectively, in NiPc nanowires. FTIR spectra show a structural transition from powder to nanowire. The optical properties of NiPc nanowires have been investigated via a comparison between theoretical and experimental approaches. The most significant absorption peaks of NiPc nanowires in the visible region are located at 626 nm and 672 nm, showing a blue shift comparing with the β-NiPc. We have also theoretically revealed the excitation energies in NiPc single molecule and dimer in the form of α and β phases using time-dependent density-functional theory. These theoretical results are in qualitative agreement with the measurements of optical properties. Moreover, no noticeable change in crystalline form is shown when tuning the heating temperature from 420 °C to 450 °C, suggesting a wide synthesis temperature window. The reduced Ni-Ni distance indicated a clear advantage over powder in terms of potential applications in organic electronics.

  6. The theoretical studies of piezoresistive effect in diamond films

    Institute of Scientific and Technical Information of China (English)

    KONG; Chunyang

    2002-01-01

    [1]Jiang, X., Schiffmann, K., Klages, C. P., Nucleation and initial growth phase of diamond thin films on(100)silicon, Phys. Rev., 1994, B50(12): 8402-8410.[2]Jiang, X., Klages, C. P., Zachai, R. et al., Epitaxial diamond thin films on(100)silicon substrate, Appl. Phys. Lett., 1993, 62(26): 3438-3440.[3]Deguchi, M., Kitabatake, M., Hirao, T. et al., PR properties of chemical-vapor-deposited p-type diamond strain-gauges fabricared on diaphragm structure, Diamond Relat. Mater., 1996,5: 728-731.[4]Wang, W. L., Liao, K. J., Feng, B. et al., PR of p-type heteroepitaxial diamond films on Si(100), Diamond Relat. Matet., 1998, 7: 528-532.[5]Wang, W. L., Jiang, X., Taube, K. et al., PR of polycrystalline p-type diamond films of various doping levels at different temperatures, J. Appl. Phys., 1997, 82(2): 729-732.[6]Fang, L., Wang, W. L., Ding, P. D. et al., Study on the PR effect of crystalline and polycrystalline diamond under uniaxial strains, J. Appl. Phys., 1999, 86(9): 5185-5193.[7]Fang, L., Wang, W. L., Ding, P. D. et al., Study on the PR effect in p-type polycrystalline diamond, Science in China, 1999, 42(7): 769-778.[8]Aslam, M., Taher, I., Masood, A., Piezoresistivity invapor deposited diamond films, Appl. Phys. Lett., 1992, 60: 2923-2925.[9]Sondheimer, E. H., The mean free path of electrons in metals, Advan. Phys., 1952, 1: 1-42.[10]Fuchs, K., The conductivity of thin metallic films according to the electron theory of metals, Proc. Cambridge Phil. Soc., 1938, 34: 100-108.[11]Xue, Z. Q., Wu, Q. D., Li, J., Physics of Thin Films(in Chinese), 2nd ed., Beijing: Publishing House of Electronics Industry, 1991, 282-284.[12]Beer, A. C., Willardson, R. K., Hall and transverse magnetoresistance effects for warped bands and mixed scattering, Phys. Rev., 1958, 110: 1286-1294.[13]Kenneth, J. R., William, J. L., High-field magnetoresistance of semiconducting diamond, Phys. Rev., 1972, B6: 4588-4592.

  7. Theoretical studies of excited state 1,3 dipolar cycloadditions

    Science.gov (United States)

    Belluccci, Michael A.

    The 1,3 dipolar photocycloaddition reaction between 3-hydroxy-4',5,7-trimethoxyflavone (3-HTMF) and methyl cinnamate is investigated in this work. Since its inception in 2004 [JACS, 124, 13260 (2004)], this reaction remains at the forefront in the synthetic design of the rocaglamide natural products. The reaction is multi-faceted in that it involves multiple excited states and is contingent upon excited state intramolecular proton transfer (ESIPT) in 3-HTMF. Given the complexity of the reaction, there remain many questions regarding the underlying mechanism. Consequently, throughout this work we investigate the mechanism of the reaction along with a number of other properties that directly influence it. To investigate the photocycloaddition reaction, we began by studying the effects of different solvent environments on the ESIPT reaction in 3-hydroxyflavone since this underlying reaction is sensitive to the solvent environment and directly influences the cycloaddition. To study the ESIPT reaction, we developed a parallel multi-level genetic program to fit accurate empirical valence bond (EVB) potentials to ab initio data. We found that simulations with our EVB potentials accurately reproduced experimentally determined reaction rates, fluorescence spectra, and vibrational frequency spectra in all solvents. Furthermore, we found that the ultrafast ESIPT process results from a combination of ballistic transfer and intramolecular vibrational redistribution. To investigate the cycloaddition reaction mechanism, we utilized the string method to obtain minimum energy paths on the ab initio potential. These calculations demonstrated that the reaction can proceed through formation of an exciplex in the S1 state, followed by a non-adiabatic transition to the ground state. In addition, we investigated the enantioselective catalysis of the reaction using alpha,alpha,alpha',alpha'-tetraaryl-1,3-dioxolan-4,5-dimethanol alcohol (TADDOL). We found that TADDOL lowered the energy

  8. Theoretical study on the reactivity of sulfate species with hydrocarbons

    Science.gov (United States)

    Ma, Q.; Ellis, G.S.; Amrani, A.; Zhang, T.; Tang, Y.

    2008-01-01

    The abiotic, thermochemically controlled reduction of sulfate to hydrogen sulfide coupled with the oxidation of hydrocarbons, is termed thermochemical sulfate reduction (TSR), and is an important alteration process that affects petroleum accumulations in nature. Although TSR is commonly observed in high-temperature carbonate reservoirs, it has proven difficult to simulate in the laboratory under conditions resembling nature. The present study was designed to evaluate the relative reactivities of various sulfate species in order to provide greater insight into the mechanism of TSR and potentially to fill the gap between laboratory experimental data and geological observations. Accordingly, quantum mechanics density functional theory (DFT) was used to determine the activation energy required to reach a potential transition state for various aqueous systems involving simple hydrocarbons and different sulfate species. The entire reaction process that results in the reduction of sulfate to sulfide is far too complex to be modeled entirely; therefore, we examined what is believed to be the rate limiting step, namely, the reduction of sulfate S(VI) to sulfite S(IV). The results of the study show that water-solvated sulfate anions SO42 - are very stable due to their symmetrical molecular structure and spherical electronic distributions. Consequently, in the absence of catalysis, the reactivity of SO42 - is expected to be extremely low. However, both the protonation of sulfate to form bisulfate anions (HSO4-) and the formation of metal-sulfate contact ion-pairs could effectively destabilize the sulfate molecular structure, thereby making it more reactive. Previous reports of experimental simulations of TSR generally have involved the use of acidic solutions that contain elevated concentrations of HSO4- relative to SO42 -. However, in formation waters typically encountered in petroleum reservoirs, the concentration of HSO4- is likely to be significantly lower than the levels

  9. Theoretical study of the relativistic molecular rotational g-tensor

    Energy Technology Data Exchange (ETDEWEB)

    Aucar, I. Agustín, E-mail: agustin.aucar@conicet.gov.ar; Gomez, Sergio S., E-mail: ssgomez@exa.unne.edu.ar [Institute for Modeling and Technological Innovation, IMIT (CONICET-UNNE) and Faculty of Exact and Natural Sciences, Northeastern University of Argentina, Avenida Libertad 5400, W3404AAS Corrientes (Argentina); Giribet, Claudia G.; Ruiz de Azúa, Martín C. [Physics Department, Faculty of Exact and Natural Sciences, University of Buenos Aires and IFIBA CONICET, Ciudad Universitaria, Pab. I, 1428 Buenos Aires (Argentina)

    2014-11-21

    An original formulation of the relativistic molecular rotational g-tensor valid for heavy atom containing compounds is presented. In such formulation, the relevant terms of a molecular Hamiltonian for non-relativistic nuclei and relativistic electrons in the laboratory system are considered. Terms linear and bilinear in the nuclear rotation angular momentum and an external uniform magnetic field are considered within first and second order (relativistic) perturbation theory to obtain the rotational g-tensor. Relativistic effects are further analyzed by carrying out the linear response within the elimination of the small component expansion. Quantitative results for model systems HX (X=F, Cl, Br, I), XF (X=Cl, Br, I), and YH{sup +} (Y=Ne, Ar, Kr, Xe, Rn) are obtained both at the RPA and density functional theory levels of approximation. Relativistic effects are shown to be small for this molecular property. The relation between the rotational g-tensor and susceptibility tensor which is valid in the non-relativistic theory does not hold within the relativistic framework, and differences between both molecular parameters are analyzed for the model systems under study. It is found that the non-relativistic relation remains valid within 2% even for the heavy HI, IF, and XeH{sup +} systems. Only for the sixth-row Rn atom a significant deviation of this relation is found.

  10. REGIONAL INNOVATION SYSTEM: THEORETICAL APPROACH AND EMPIRICAL STUDY OF CHINA

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-guang; CHEN Cai

    2003-01-01

    Regional innovation system (RIS) is the new research field of modern economic geography in the age of knowledge economy. Based on the researches of regional economic geography, the authors of the paper consider RIS as the integrated and interactive systems with innovation milieu, elements, units, structure and functions. Five aspects of evaluation indicators including innovation input scale and output scale, innovation milieu transition, innovation in-ner operation, as well as innovation outer impact are worked out for final indicators of RIS scale and quality. Accord-ing to different RIS situations, three patterns of independent, imitative and cooperative development are put forward for choosing. At the latter part of the paper, we select 12 provincial regions (including three municipalities and one au-tonomous region) of China for empirical study. The results show that there exists great difference among each region from the aspects of innovation scale and quality mainly owning to the diversification of RIS social and economic mi-lieu, the major innovative units of enterprises, universities and R&D institutes. Finally, the paper points out the innova-tion development decisions for each region.

  11. Study of microbial adhesion on some wood species: theoretical prediction.

    Science.gov (United States)

    Soumya, El abed; Mohamed, Mostakim; Fatimazahra, Berguadi; Hassan, Latrache; Abdellah, Houari; Fatima, Hamadi; Saad, Ibnsouda koraichi

    2011-01-01

    The initial interaction between microorganisms and substrata is mediated by physicochemical forces, which in turn originate from the physicochemical surface properties of both interacting phases. In this context, we have determined the physicochemical proprieties of all microorganisms isolated from cedar wood decay in an old monument at the Medina of Fez-Morocco. The cedar wood was also assayed in terms of hydrophobicity and electron dono-r-electron acceptor (acid-base) properties. Investigations of these two aspects were performed by contact angles measurements via sessile drop technique. Except Bacillus subtilis strain (deltaGiwi 0) and can therefore be considered as hydrophilic while cedar wood revealed a hydrophobic character (deltaGiwi = -58.81 mi m(-2)). All microbial strains were predominantly electron donor. The results show also that all strains were weak electron acceptors. Cedar wood exhibits a weak electron donor/acceptor character. Based on the thermodynamic approach, the Lifshitz-van der Waals interaction free energy, the acid-basic interactions free energy, the total interaction free energy between the microbial cells and six different wood species (cedar, oak, beech, ash, pine and teak) in aqueous media was calculated and used to predict which microbial strains have a higher ability to adhere to wooden surfaces. Except of weak wood, for all the situations studied, generalizations concerning the adhesion of the microbiata on wood species cannot be made and the microbial adhesion on wooden substrata was dependent on wood species and microorganismstested.

  12. Theoretical study for the interlamellar aminoalcohol functionalization of kaolinite

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Xin-Juan [Key Laboratory of Green Process and Engineering, National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Li, Huiquan, E-mail: hqli@home.ipe.ac.cn [Key Laboratory of Green Process and Engineering, National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Qinfu; Cheng, Hongfei [School of Geoscience and Surveying Engineering, China University of Mining and Technology, Beijing 100083 (China); He, Peng; Li, Shaopeng [Key Laboratory of Green Process and Engineering, National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-08-30

    Graphical abstract: - Highlights: • The results indicated that aminoalcohols exist with a mixing of intercalation and grafting. • Aminoalcohols can form strong hydrogen bonds with Al octahedral sheet. • The interaction between aminoalcohols and Si tetrahedral sheet are mainly attributed by vdW force. • Aminoalcohols grafting or intercalating on kaolinite have strong reactivity as electron donors. - Abstract: Fundamental problems related to aminoalcohols intercalating on kaolinite were investigated by using density functional theory method. This study examines the adsorption modes of diethanolamine and triethanolamine on kaolinite, the role of hydrogen bonds and van der Waals (vdW) forces between aminoalcohols and interlayer of kaolinite, and the change of molecular orbital occupancies of functionalized kaolinite. Results show that functionalized kaolinite is physically intercalated and covalently grafted by aminoalcohols. Non-covalent interaction analysis provides a visualized description that intercalated aminoalcohols form strong hydrogen bonds with Al octahedral sheet, and the interaction between aminoalcohols and Si tetrahedral sheet is mainly attributed to weak vdW force. The analysis of molecular orbital occupancies for kaolinite complex showed that the functionalized kaolinite has strong chemical reactivity as electron donors on the sites of grafted or intercalated aminoalcohols for further chemical reaction with other materials.

  13. Graphene to fluorographene and fluorographane: a theoretical study.

    Science.gov (United States)

    Paupitz, R; Autreto, P A S; Legoas, S B; Srinivasan, S Goverapet; van Duin, A C T; Galvão, D S

    2013-01-25

    We report here a fully reactive molecular dynamics study on the structural and dynamical aspects of the fluorination of graphene membranes (fluorographene). Our results show that fluorination tends to produce defective areas on the graphene membranes with significant distortions of carbon-carbon bonds. Depending on the amount of incorporated fluorine atoms, large membrane holes were observed due to carbon atom losses. These results may explain the broad distribution of the structural lattice parameter values experimentally observed. We have also investigated the effects of mixing hydrogen and fluorine atoms on the graphene functionalization. Our results show that, when in small amounts, the presence of hydrogen atoms produces a significant decrease in the rate of fluorine incorporation onto the membrane. On the other hand, when fluorine is the minority element, it produces a significant catalytic effect on the rate of hydrogen incorporation. We have also observed the spontaneous formation of new hybrid structures with different stable configurations (chair-like, zigzag-like and boat-like) which we named fluorographane.

  14. Theoretical studies on energetic materials bearing pentaflurosulphyl (SF5) groups

    Indian Academy of Sciences (India)

    Li Xiao-Hong; Cui Hong-Ling; Ju Wei-Wei; Li Tong-Wei; Zhang Rui-Zhou; Yong Yong-Liang

    2014-07-01

    Heats of formation (HOF) for a series of energetic materials containing SF5 group were studied by density functional theory. Results show that HOFs increase with the augmention of field effects of substituted groups. Addition of furazan or furoxan ring increases HOF of the energetic materials. All the SF5-containing compounds have densities which are ∼0.19 g/cm3 higher than those containing -NH2 group. S-F bond is the trigger bond for the thermolysis process in the title compounds and bond dissociation energies of the weakest bonds range from 351.1 to 388.3 kJ/mol. Detonation velocities (D) and pressures (P) are evaluated by Kamlet-Jacobs equations with the calculated densities and HOFs. Results show that increasing the amount of furazan rings results in a larger D and P. Considering the detonation performance and thermal stability, eight compounds may be considered as potential candidates for high-energy density materials.

  15. Theoretical study of nonlinear optical properties of some azoic dyes

    Directory of Open Access Journals (Sweden)

    Hadji Djebar

    2015-07-01

    Full Text Available In this paper we presented semi-empirical PM3, ab-initio (HF, MP2 and DFT (B3LYP, B3PW91 calculation of the dipole moment, polarizability, and first hyperpolarizability of some azoics dyes derivatives which have electron donor and electron acceptor groups on either sides. The first hyperpolarizability of these molecules was calculated with PM3 method, HF/6-31G**, HF/6-31+G**, HF/6-31++G**, DFT with B3LYP and B3PW91 functional, and MP2/6-31++G** based on finite field approach using GAUSSIAN03 program. The effects of the intramolecular charge transfer (ICT from the donor to the acceptor groups on the molecular geometry and atomic charge distribution of these NLO chromophores are derived from its HF, MP2 and DFT calculations. The variation of this property has also been correlated to E (HOMO-LUMO gap and to the nature of the highest occupied molecular orbital HOMO and the lowest unoccupied molecular orbital HOMO. The study reveals that the azoics dyes derivatives have large hyperpolarizability values; hence they may be used in the development of nonlinear optical materials.

  16. Theoretical kinetic study of the low temperature oxidation of ethanol

    CERN Document Server

    Fournet, René; Bounaceur, Roda; Molière, Michel

    2009-01-01

    In order to improve the understanding of the low temperature combustion of ethanol, high-level ab initio calculations were performed for elementary reactions involving hydroxyethylperoxy radicals. These radicals come from the addition of hydroxethyl radicals (?CH3CHOH and ?CH2CH2OH) on oxygen molecule. Unimolecular reactions involving hydroxyethylperoxy radicals and their radical products were studied at the CBS-QB3 level of theory. The results allowed to highlight the principal ways of decomposition of these radicals. Calculations of potential energy surfaces showed that the principal channels lead to the formation of HO2 radicals which can be considered, at low temperature, as slightly reactive. However, in the case of CH3CH(OOH)O? radicals, a route of decomposition yields H atom and formic peracid, which is a branching agent that can strongly enhance the reactivity of ethanol in low temperature oxidation. In addition to these analyses, high-pressure limit rate constants were derived in the temperature rang...

  17. Theoretical Study on the High Energy Density Compound Hexanitrohexaazatricyclotetradecanedifuroxan

    Institute of Scientific and Technical Information of China (English)

    QIU Ling; XIAO He-Ming; ZHU Wei-Hua; JU Xue-Hai; GONG Xue-Dong

    2006-01-01

    Density functional theory (DFT) has been employed to study the molecular geometries, electronic structures,infrared (IR) spectra, and thermodynamic properties of the high energy density compound hexanitrohexaazatricyclotetradecanedifuroxan (HHTTD) at the B3LYP/6-31G** level of theory. The calculated results showthattherearefourconformationalisomers (a, β, γ and δ) for HHTTD, and the relative stabilities of four conformers were assessed based on the calculated total energies and the energy-gaps between the frontier molecular orbitals. The computed harmonic vibrational frequencies are in reasonable agreement with the available experimental data. Thermodynamic properties derived from the IR spectra on the basis of statistical thermodynamic principles are linearly correlated with the temperature. Detonation performances were evaluated by using the Kamlet-Jacobsequationsbasedonthecalculated densities and heats of formation. It was found that four HHTTD isomers with the predicted densities of ca. 2 g·cm-3, detonation velocities near 10 km·s-1, and detonation pressures over 45 Gpa, may be novel potential candidates of high energy density materials (HEDM). These results may provide basic information for the molecular designof HEDM.

  18. Theoretical study on the constricted flow phenomena in arteries

    Science.gov (United States)

    Sen, S.; Chakravarty, S.

    2012-12-01

    The present study is dealt with the constricted flow characteristics of blood in arteries by making use of an appropriate mathematical model. The constricted artery experiences the generated wall shear stress due to flow disturbances in the presence of constriction. The disturbed flow in the stenosed arterial segment causes malfunction of the cardiovascular system leading to serious health problems in the form of heart attack and stroke. The flowing blood contained in the stenosed artery is considered to be non-Newtonian while the flow is treated to be two-dimensional. The present pursuit also accounts for the motion of the arterial wall and its effect on local fluid mechanics. The flow analysis applies the time-dependent, two-dimensional incompressible nonlinear Navier-Stokes equations for non-Newtonian fluid representing blood. An extensive quantitative analysis presented at the end of the paper based on large scale numerical computations of the quantities of major physiological significance enables one to estimate the constricted flow characteristics in the arterial system under consideration which deviates significantly from that of normal physiological flow conditions.

  19. Theoretical study of trans-cis photoisomerism in polymethine cyanines

    Science.gov (United States)

    Momicchioli, Fabio; Baraldi, Ivan; Berthier, Gaston

    1988-06-01

    The trans-cis photoisomerism of polymethine dyes has been interpreted so far using different and rather inconsistent models of the potential energy surfaces. In order to search for a unified electronic model, we tackled the problem again from an intramolecular point of view. Our study consisted in qualitative MO considerations followed by explicit (CS INDO) calculations of the S 0, T 1 and S 1 potential energy curves for a proper model system: pentamethine cyanine isomerizing around the 2-3 and 3-4 bonds. Torsional energy levels for the calculated potential curves were also obtained. The main conclusions are: (i) the photoreaction proceeds through a "non-spectroscopic" (perp) S 1 minimum which exists also in the isolated molecule, (ii) this twisted excited species has charge transfer character (TICT), as opposed to the biradicaloid character of the "non-spectroscopic" S 1 minimum involved in the trans→cis photoisomerization of olefines (e.g., stilbene). The possible consequences on the dynamics of the excited state relaxation in non-polar solvents are envisaged.

  20. Chemical functionalization of graphene via aryne cycloaddition: a theoretical study.

    Science.gov (United States)

    Zhao, Jing-xiang; Wang, Hong-xia; Gao, Bo; Wang, Xiao-guang; Cai, Qing-hai; Wang, Xuan-zhang

    2012-06-01

    Chemical functionalization of graphene provides a promising route to improve its solubility in water and organic solvents as well as modify its electronic properties, thus significantly expanding its potential applications. In this article, by using density functional theory (DFT) methods, we have studied the effects of the chemical functionalization of graphenes via aryne cycloaddition on its properties. We found that the adsorption of an isolated aryne group on the graphene sheet is very weak with the adsorption energy of -0.204 eV, even though two new single C-C interactions are formed between the aryne group and the graphene. However, the interaction of graphene with the aryne group can be greatly strengthened by (i) substituting the H-atoms in aryne group with F-, Cl-, -NO(2) (electron-withdrawing capability), or CH(3)-group (electron-donating capability), and (ii) increasing the coverage of the adsorbed aryne groups on the graphene sheet. As expected, the strongest bonding is found on the graphene edges, in which the adsorbed aryne groups prefer to be far away from each other. Interestingly, chemical functionalization with aryne groups leads to an opening of the band gap of graphene, which is dependent on the coverage of the adsorbed aryne groups. The present work provides an insight into the modifications of graphene with aryne groups in experiment.

  1. Theoretical and experimental studies of a magnetically actuated valveless micropump

    Science.gov (United States)

    Ashouri, Majid; Behshad Shafii, Mohammad; Moosavi, Ali

    2017-01-01

    This paper presents the prototype design, fabrication, and characterization of a magnetically actuated micropump. The pump body consists of three nozzle/diffuser elements and two pumping chambers connected to the ends of a flat-wall pumping cylinder. A cylindrical permanent magnet placed inside the pumping cylinder acts as a piston which reciprocates by using an external magnetic actuator driven by a motor. The magnetic piston is covered by a ferrofluid to provide self-sealing capability. A prototype composed of three bonded layers of polymethyl-methacrylate (PMMA) has been fabricated. Water has been successfully pumped at pressures of up to 750 Pa and flow rates of up to 700 µl min-1 while working at the piston actuation frequency of 4 and 5 Hz, respectively. 3D numerical simulations are also carried out to study the performance of the pump. The best experimental and numerical volumetric efficiency of the pump are about 7 and 8%, respectively, at the piston speed of 0.03 m s-1. The contactless external actuation feature of the design enables integration of the pump with other PMMA-based microfluidic systems with low cost and disposability.

  2. Mathematics education and comparative historical studies

    Directory of Open Access Journals (Sweden)

    Wagner RODRIGUES VALENTE

    2013-11-01

    Full Text Available This paper has as its aims: to characterize the area of research «history of mathematics education» and to defend the idea that mathematics education has constituted a privileged research theme within the field of comparative historical studies. To achieve these aims, the text includes references to a review of the literature concerning comparative studies, the analysis of two fundamental moments focused on attempts to internationalize the mathematics curriculum, both of which occurred during the 20th century, and, to end, a case study emanating from an international cooperation between researchers in Brazil and Portugal.

  3. Magnetotactic bacteria and microjets: A comparative study

    NARCIS (Netherlands)

    Khalil, I.S.M.; Magdanz, Veronika; Sanchez, Samuel; Schmidt, Oliver G.; Misra, Sarthak

    2013-01-01

    We provide a comparative study between two self-propelled microrobots, i.e., magnetotactic bacteria and microjets. This study includes characterization of their fluidic properties (linear and rotational drag coefficients) based on their morphologies and characterization of their magnetic properties

  4. Theoretical studies in nuclear reactions and nuclear structure. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    1992-05-01

    Research in the Maryland Nuclear Theory Group focusses on problems in four basic areas of current relevance. Hadrons in nuclear matter; the structure of hadrons; relativistic nuclear physics and heavy ion dynamics and related processes. The section on hadrons in nuclear matter groups together research items which are aimed at exploring ways in which the properties of nucleons and the mesons which play a role in the nuclear force are modified in the nuclear medium. A very interesting result has been the finding that QCD sum rules supply a new insight into the decrease of the nucleon`s mass in the nuclear medium. The quark condensate, which characterizes spontaneous chiral symmetry breaking of the late QCD vacuum, decreases in nuclear matter and this is responsible for the decrease of the nucleon`s mass. The section on the structure of hadrons contains progress reports on our research aimed at understanding the structure of the nucleon. Widely different approaches are being studied, e.g., lattice gauge calculations, QCD sum rules, quark-meson models with confinement and other hedgehog models. A major goal of this type of research is to develop appropriate links between nuclear physics and QCD. The section on relativistic nuclear physics represents our continuing interest in developing an appropriate relativistic framework for nuclear dynamics. A Lorentz-invariant description of the nuclear force suggests a similar decrease of the nucleon`s mass in the nuclear medium as has been found from QCD sum rules. Work in progress extends previous successes in elastic scattering to inelastic scattering of protons by nuclei. The section on heavy ion dynamics and related processes reports on research into the e{sup +}e{sup {minus}} problem and heavy ion dynamics.

  5. Theoretical studies in nuclear reactions and nuclear structure

    Energy Technology Data Exchange (ETDEWEB)

    1992-05-01

    Research in the Maryland Nuclear Theory Group focusses on problems in four basic areas of current relevance. Hadrons in nuclear matter; the structure of hadrons; relativistic nuclear physics and heavy ion dynamics and related processes. The section on hadrons in nuclear matter groups together research items which are aimed at exploring ways in which the properties of nucleons and the mesons which play a role in the nuclear force are modified in the nuclear medium. A very interesting result has been the finding that QCD sum rules supply a new insight into the decrease of the nucleon's mass in the nuclear medium. The quark condensate, which characterizes spontaneous chiral symmetry breaking of the late QCD vacuum, decreases in nuclear matter and this is responsible for the decrease of the nucleon's mass. The section on the structure of hadrons contains progress reports on our research aimed at understanding the structure of the nucleon. Widely different approaches are being studied, e.g., lattice gauge calculations, QCD sum rules, quark-meson models with confinement and other hedgehog models. A major goal of this type of research is to develop appropriate links between nuclear physics and QCD. The section on relativistic nuclear physics represents our continuing interest in developing an appropriate relativistic framework for nuclear dynamics. A Lorentz-invariant description of the nuclear force suggests a similar decrease of the nucleon's mass in the nuclear medium as has been found from QCD sum rules. Work in progress extends previous successes in elastic scattering to inelastic scattering of protons by nuclei. The section on heavy ion dynamics and related processes reports on research into the e{sup +}e{sup {minus}} problem and heavy ion dynamics.

  6. Theoretical and experimental studies on emissions from wood combustion

    Energy Technology Data Exchange (ETDEWEB)

    Skreiberg, Oeyvind

    1997-12-31

    This thesis discusses experiments on emissions from wood log combustion and single wood particle combustion, both caused by incomplete combustion and emissions of nitric and nitrous oxide, together with empirical and kinetic NO{sub x} modelling. Experiments were performed in three different wood stoves: a traditional stove, a staged air stove and a stove equipped with a catalytic afterburner. Ideally, biomass fuel does not give a net contribution to the greenhouse effect. However, incomplete combustion was found to result in significant greenhouse gas emissions. Empirical modelling showed the excess air ratio and the combustion chamber temperature to be the most important input variables controlling the total fuel-N to NO{sub x} conversion factor. As the result of an international round robin test of a wood stove equipped with a catalytic afterburner, particle emission measurements were found to be the best method to evaluate the environmental acceptability of the tested stove, since the particle emission level was least dependent of the national standards, test procedures and calculation procedures used. In batch single wood particle combustion experiments on an electrically heated small-scale fixed bed reactor the fuel-N to NO conversion factor varied between 0.11-0.86 depending on wood species and operating conditions. A parameter study and homogeneous kinetic modelling on a plug flow reactor showed that, depending on the combustion compliance in question, there is an optimum combination of primary excess air ratio, temperature and residence time that gives a maximum conversion of fuel-N to N{sub 2}. 70 refs., 100 figs., 26 tabs.

  7. Theoretical Study of Amplitude Modulation Application during Radio Frequency Electrocoagulation

    Directory of Open Access Journals (Sweden)

    V. A. Karpuhin

    2015-01-01

    Full Text Available This article concerns the investigation results of influence of the amplitude-modulated acting signal parameters on the thermoelectric characteristics of biological tissues for a specified geometry of the working electrode section during RF mono-polar electrocoagulation. The geometric model ‘electrode - a biological tissue’ was suggested to study the distribution of power and temperature fields in biological tissue during mono-polar coagulation. The model of biological tissue is represented as a cylinder and the needle electrode is an ellipsoid immersed in the biological tissue. The heat and quasi-electrostatics equations are used as a mathematical model. These equations are solved in Comsol Multiphysics environment.As a result, we have got the following findings: the technique of calculating parameters of the PAM acting signal which has a fixed carrier frequency for the needle electrode of a specified geometry and the immersion depth in biological tissues is suggested. Parameters of PAM signal are determined for this electrode geometry. These parameters provide a 60 ... 80°C heating range of biological tissues near the working part of the tool for different amplitudes of acting signal during RF coagulation. It has been found out that both the temperature and the relaxation frequency of biological tissue depend on exposure time for the needle electrode of a specified geometry and immersion depth of the working part of tool into biological tissue.It is shown that the relaxation frequency of the biological tissue, subjected to the radiofrequency pulses, linearly depends on its heating temperature and can be used as a numerical criterion for maintaining the specified temperature conditions. It is found that the relaxation frequency of the biological tissue depends on the contact area of the tool working part and biological tissues. To reduce this dependence it is necessary to provide automatic current control of the output action.

  8. Theoretical study of ultraviolet induced photodissociation dynamics of sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Tatsuhiro; Ohta, Ayumi; Suzuki, Tomoya; Ikeda, Kumiko [Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-Cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Danielache, Sebastian O. [Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-Cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Earth-Life Science Institute (ELSI), Tokyo Institute of Technology (Japan); Department of Environmental Science and Techonology, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yoohama 226-8502 (Japan); Nanbu, Shinkoh, E-mail: shinkoh.nanbu@sophia.ac.jp [Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-Cho, Chiyoda-ku, Tokyo 102-8554 (Japan)

    2015-05-01

    Highlights: • Photodissociation dynamics of H{sub 2}SO{sub 4} at low-lying electronically excited states were investigated. • Photochemical processes were simulated by on-the-fly ab initio MD. • Sulfuric acid after the excitation to the S{sub 1} state dissociated to HSO{sub 4}(1{sup 2}A″) + H({sup 2}S). • Sulfuric acid after the excitation to the S{sub 2} state dissociated to HSO{sub 4}(2{sup 2}A″) + H({sup 2}S). • The energy region of the UV spectra where NMD fractionation may occur is predicted. - Abstract: Photodissociation dynamics of sulfuric acid after excitation to the first and second excited states (S{sub 1} and S{sub 2}) were studied by an on-the-fly ab initio molecular dynamics simulations based on the Zhu–Nakamura version of the trajectory surface hopping (ZN-TSH). Forces acting on the nuclear motion were computed on-the-fly by CASSCF method with Dunning’s augmented cc-pVDZ basis set. It was newly found that the parent molecule dissociated into two reaction-channels (i) HSO{sub 4}(1{sup 2}A″) + H({sup 2}S) by S{sub 1}-excitation, and (ii) HSO{sub 4}(2{sup 2}A″) + H({sup 2}S) by S{sub 2}-excitation. The direct dissociation dynamics yield products different from the SO{sub 2} + 2OH fragments often presented in the literature. Both channels result in the same product and differs only in the electronic state of the HSO{sub 4} fragment{sub .} The trajectories running on S{sub 2} do not hop with S{sub 0} and a nonadiabatic transition happens at the S{sub 2}–S{sub 1} conical intersection located at a longer OH bond-length than the S{sub 1}–S{sub 0} intersection producing an electronic excited state (2{sup 2}A″) of HSO{sub 4} product.

  9. Hydrogen motion in proton sponge cations: a theoretical study.

    Science.gov (United States)

    Horbatenko, Yevhen; Vyboishchikov, Sergei F

    2011-04-18

    This work presents a study of intramolecular NHN hydrogen bonds in cations of the following proton sponges: 2,7-bis(trimethylsilyl)-1,8-bis(dimethylamino)naphthalene (1), 1,6-diazabicyclo[4.4.4.]tetradecane (2), 1,9-bis(dimethylamino)dibenzoselenophene (3), 1,9-bis(dimethylamino)dibenzothiophene (4), 4,5-bis(dimethylamino)fluorene (5), quino[7,8-h]quinoline (6) 1,2-bis(dimethylamino)benzene (7), and 1,12-bis(dimethylamino)benzo[c]phenantrene (8). Three different patterns were found for proton motion: systems with a single-well potential (cations 1-2), systems with a double-well potential and low proton transfer barrier, ΔEe (cations 3-5), and those with a double-well potential and a high barrier (cations 6-8). Tests of several density functionals indicate that the PBEPBE functional reproduces the potential-energy surface (PES) obtained at the MP2 level well, whereas the B3LYP, MPWB1K, and MPW1B95 functionals overestimate the barrier. Three-dimensional PESs were constructed and the vibrational Schrödinger equation was solved for selected cases of cation 1 (with a single-well potential), cation 4 (with a ΔEe value of 0.1 kcal mol(-1) at the MP2 level), and cations 6 (ΔEe = 2.4 kcal mol(-1)) and 7 (ΔEe=3.4 kcal mol(-1)). The PES is highly anharmonic in all of these cases. The analysis of the three-dimensional ground-state vibrational wave function shows that the proton is delocalized in cations 1 and 4, but is rather localized around the energy minima for cation 7. Cation 6 is an intermediate case, with two weakly pronounced maxima and substantial tunneling. This allows for classification of proton sponge cations into those with localized and those with delocalized proton behavior, with the borderline between them at ΔEe values of about 1.5 kcal mol(-1). The excited vibrational states of proton sponge cations with a low barrier can be described within the framework of a simple particle-in-a-box model. Each cation can be assigned an effective box width.

  10. Centrifugation. A theoretical study of oxygen enrichment by centrifugation

    Energy Technology Data Exchange (ETDEWEB)

    Kierkegaard, P.; Raetz, E.

    1998-12-01

    In the present paper we first investigate what happens if we fill a cylinder with air, close it and rotate it. The results show that no matter which peripheral speed is used, it is not possible by means of the radial separation effect alone, to enrich the oxygen concentration from the previous 21% to more then 23.3%, which is of no practical value. In case of a too low enrichment in one centrifuge, the wanted material from this centrifuge can be used as an input for a second centrifuge and so on, in this way forming a cascade of centrifuges. Oxygen will be enriched in each step, until the desired concentration is reached. Cascading was the technology in the very beginning by enrichment plants for uraniumhexaflouride, used for atomic weapons and nuclear power plants. In this study we try to avoid cascading by aiming for higher separation factors. Therefore, we next investigate the possibilities of using a countercurrent centrifuge where in principle the enriched gas is subjected to several centrifugation in the same centrifuge. The calculations show, that in this way it is possible to produce nearly a 100% pure oxygen (polluted with some heavier molecules like argon) in one machine. Our third step was to calculate the amount of oxygen produced per hour. Using a countercurrent centrifuge of the Zippe type, 100 cm high and 20 cm in diameter, it is or will be possible in the near future to produce 17 g enriched air per hour enriched to 50% oxygen. That corresponds to processing 1 m{sup 3} atmospherical air in the period of approximately 24 hours. This is not very impressive. Our fourth step was to estimate the amount of power used for producing this amount of oxygen. A rough, but complicated, estimate shows that the power consumption at the production level will be about the double of the consumption used today. The overall conclusion is, that centrifugation as a production method for oxygen (or nitrogen) will not be competitive with the currently used method in the

  11. A COMPARATIVE STUDY OF BYG SEARCH ENGINES

    Directory of Open Access Journals (Sweden)

    Kailash Kumar

    2013-01-01

    Full Text Available This paper compares the retrieval effectiveness of the Bing, Yahoo and Google (BYG Search Engines. The precision and relative recall of each search engine was considered for evaluating the effectiveness of the search engines. General Queries were tested. Results of the study showed that the precision of Google was high as compared to other two search engines and Yahoo has better precision than Bing

  12. A Theoretical and Experimental Study of DNA Self-assembly

    Science.gov (United States)

    Chandran, Harish

    The control of matter and phenomena at the nanoscale is fast becoming one of the most important challenges of the 21st century with wide-ranging applications from energy and health care to computing and material science. Conventional top-down approaches to nanotechnology, having served us well for long, are reaching their inherent limitations. Meanwhile, bottom-up methods such as self-assembly are emerging as viable alternatives for nanoscale fabrication and manipulation. A particularly successful bottom up technique is DNA self-assembly where a set of carefully designed DNA strands form a nanoscale object as a consequence of specific, local interactions among the different components, without external direction. The final product of the self-assembly process might be a static nanostructure or a dynamic nanodevice that performs a specific function. Over the past two decades, DNA self-assembly has produced stunning nanoscale objects such as 2D and 3D lattices, polyhedra and addressable arbitrary shaped substrates, and a myriad of nanoscale devices such as molecular tweezers, computational circuits, biosensors and molecular assembly lines. In this dissertation we study multiple problems in the theory, simulations and experiments of DNA self-assembly. We extend the Turing-universal mathematical framework of self-assembly known as the Tile Assembly Model by incorporating randomization during the assembly process. This allows us to reduce the tile complexity of linear assemblies. We develop multiple techniques to build linear assemblies of expected length N using far fewer tile types than previously possible. We abstract the fundamental properties of DNA and develop a biochemical system, which we call meta-DNA, based entirely on strands of DNA as the only component molecule. We further develop various enzyme-free protocols to manipulate meta-DNA systems and provide strand level details along with abstract notations for these mechanisms. We simulate DNA circuits by

  13. Experimental and theoretical studies on concrete structures with special-shaped shear walls

    Directory of Open Access Journals (Sweden)

    LIU Jianxin

    2014-06-01

    Full Text Available On the basis of concept design and staggered shear panels structure,this paper puts forward a new reinforced concrete high rise biuding structure with special-shaped shear walls and presents an experimental study of the seismic performance of the new special-shaped shear walls structure under low reversed cyclic loading using MTS electro hydraulic servo system.Compared with experimental results,a finite element analysis on this special-shaped shear wall structure,which considers the nonlinearity of concrete structure,is found suitable.It shows that the experimental results fairly confirms to the calculated values,which indicates that this new structure has advantages as good architecture function,big effective space,high overall lateral stiffness,fine ductility,advanced seismic behavior,etc..That is,the close r agreement between the theoretical and experimental results indicates the proposed shear wall structure has wide applications.

  14. Theoretical study of the porosity effects on the shock response of graphitic materials

    Directory of Open Access Journals (Sweden)

    Pineau Nicolas

    2015-01-01

    Full Text Available In this paper we present a theoretical study of the shock compression of porous graphite by means of combined Monte Carlo and molecular dynamics simulations using the LCBOPII potential. The results show that the Hugoniostat methods can be used with “pole” properties calculated from porous models to reproduce the experimental Hugoniot of pure graphite and diamond with good accuracy. The computed shock temperatures show a sharp increase for weak shocks which we analyze as the heating associated with the closure of the initial porosity. After this initial phase, the temperature increases with shock intensity at a rate comparable to monocrystalline graphite and diamond. These simulations data can be exploited in view to build a full equation of state for use in hydrodynamic simulations.

  15. Theoretical Chemistry Study of the Hydrogen-bonded Interaction between Acylamine and Chloromethane Compounds

    Institute of Scientific and Technical Information of China (English)

    GE Qing-Yu; WANG Hai-Jun; CHEN Jian-Hua

    2005-01-01

    The hydrogen-bonded interaction between acylamine and chloromethane was studied using theoretical calculation methods. Looking the interaction system as a hydrogen-bonded complex, the geometric optimization of the interaction system was performed with HF and B3LYP methods at 6-311++G** level. Stable structures of these complexes were obtained. Binding energies and some other physical chemistry parameters of them were computed and compared. According to the calculation results, it can be identified that DMA (DMF or DEF) can form stable complex with chloromethane by the hydrogen-bonded interaction between them. The stable orders of these hydrogen-bonded complexes were obtained and described as: DMF-CHCl3>DMF-CH2Cl2>DMF-CH3Cl, DEF-CHCl3>DEF-CH2Cl2>DEF-CH3Cl, DMA-CHCl3>DMA-CH2Cl2>DMA-CH3Cl, respectively.

  16. Theoretical structural and vibrational study of 5-trifluoromethyluracil. A comparison with uracil

    Energy Technology Data Exchange (ETDEWEB)

    Rudyk, Roxana; Ramos, María E.; Checa, María A.; Brandán, Silvia A. [Cátedra de Química General, Instituto de Química Inorgánica, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471,(4000), San Miguel de Tucumán, Tucum and #x00E1 (Argentina); Chamorro, Eduardo E. [Facultad de Ciencias Exactas, Universidad Andrés Bello, Avda. República 275, 8370146, Santiago (Chile)

    2014-10-06

    In the present work, a comparative study on the structural and vibrational properties of the 5-trifluoromethyluracil (TFMU) derivative with those corresponding to uracil in gas and aqueous solution phases was performed combining the available H{sup 1}-NMR, C{sup 13}-NMR, F{sup 19}-NMR and FTIR spectra with Density Functional Theory (DFT) calculations. Three stable conformers were theoretically determined in both media by using the hybrid B3LYP/6-31G* method. The solvent effects were simulated by means of the self-consistent reaction field (SCRF) method employing the integral equation formalism variant (IEFPCM). Complete assignments of the vibrational spectra in both phases were performed combining the internal coordinates analysis and the DFT calculations with the Scaled Quantum Mechanics Force Field (SQMFF) methodology. The atomic charges, bond orders, solvation energies, dipole moments, molecular electrostatic potentials and force constants parameters were calculated for the three conformers of TFMU in gas phase and aqueous solution.

  17. Theoretical description of mixed-field orientation of asymmetric top molecules: a time-dependent study

    CERN Document Server

    Omiste, Juan J

    2016-01-01

    We present a theoretical study of the mixed-field-orientation of asymmetric top molecules in tilted static electric field and non-resonant linearly polarized laser pulse by solving the time-dependent Schr\\"odinger equation. Within this framework, we compute the mixed-field orientation of a state selected molecular beam of benzonitrile (C$_7$H$_5$N) and compare with the experimental observations [J. L. Hansen et al., Phys. Rev. A 83, 023406 (2011)], and with our previous time-independent descriptions [J. J. Omiste et al., Phys. Chem. Chem. Phys. 13, 18815 (2011)]. For an excited rotational state, we investigate the field-dressed dynamics for several field configurations as those used in the mixed-field experiments. The non-adiabatic phenomena and their consequences on the rotational dynamics are analyzed in detail.

  18. Fatigue study on the actuation performance of macro fiber composite (MFC): theoretical and experimental approach

    Science.gov (United States)

    Pandey, Akash; Arockiarajan, A.

    2017-03-01

    Macro fiber composite (MFC) is extensively used in vibration control and actuation applications due to its high flexibility and enhanced coupling coefficients. During these applications, MFCs are subjected to the continuous cyclic electrical loading, which may lead to the degradation in its actuation performance. In order to predict the life cycle of MFCs, an experimental setup has been devised and experiments are performed under cyclic loading condition. Efforts involved in the experiments are huge in terms of time and cost. Hence, an attempt has been made to develop a theoretical model to predict the fatigue behavior of MFCs. A nonlinear finite element method has been formulated based on Kirchhoff plate theory wherein the fatigue failure criterion based on strain energy is embedded. Simulated results based on the proposed model is compared with experimental observation and are in good agreement with each other. Variation in the life cycle of MFCs are also studied for different operating temperatures as well as structural/geometric configurations.

  19. A theoretical study of the spheroidal droplet evaporation in forced convection

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jie, E-mail: leejay1986@163.com; Zhang, Jian

    2014-11-07

    In many applications, the shape of a droplet may be assumed to be an oblate spheroid. A theoretical study is conducted on the evaporation of an oblate spheroidal droplet under forced convection conditions. Closed-form analytical expressions of the mass evaporation rate for an oblate spheroid are derived, in the regime of controlled mass-transfer and heat-transfer, respectively. The variation of droplet size during the evaporation process is presented in the regime of shrinking dynamic model. Comparing with the droplets having the same surface area, an increase in the aspect ratio enhances the mass evaporation rate and prolongs the burnout time. - Highlights: • Fully algebraic solutions for the spheroidal droplet evaporation rate is obtained. • We examine the effect of aspect ratio on the droplet evaporation. • We propose a calculation method of Nusselt number for spheroidal droplet.

  20. Spectroscopic and theoretical study of the o-vanillin hydrazone of the mycobactericidal drug isoniazid

    Science.gov (United States)

    González-Baró, Ana C.; Pis-Diez, Reinaldo; Parajón-Costa, Beatriz S.; Rey, Nicolás A.

    2012-01-01

    A complete and detailed study of the hydrazone obtained from condensation of antituberculous isoniazid (hydrazide of the isonicotinic acid, INH) and o-vanillin (2-hydroxy-3-methoxybenzaldehyde, o-HVa) is performed. It includes structural and spectroscopic analyses, comparing experimental and theoretical results. The compound was obtained as a chloride of the pyridinic salt (INHOVA +Cl -) but it will be referred as INHOVA for the sake of simplicity. The conformational space was searched and optimized geometries were determined both in gas phase and including solvent effects. Vibrational (IR and Raman), electronic and NMR spectra were registered and assigned with the help of computational methods based on the Density Functional Theory. Isoniazid hydrazones are good candidates for therapeutic agents against tuberculosis with conserved efficiency and lower toxicity and resistance than parent INH.

  1. Experimental and theoretical study of 3p photoionization and subsequent Auger decay in atomic chromium

    Science.gov (United States)

    Keskinen, J.; Huttula, S.-M.; Mäkinen, A.; Patanen, M.; Huttula, M.

    2015-12-01

    3p photoionization and subsequent low kinetic energy Coster-Kronig and super Coster-Kronig Auger decay have been studied in atomic chromium. The binding energies, line widths, and relative intensities for the transitions seen in the synchrotron radiation excited 3p photoelectron spectrum are determined. The high resolution M2,3 M4,5 M4,5 and M2,3 M4,5 N1 Auger electron spectra following the electron impact excited 3p ionization are presented and the kinetic energies, relative intensities, and identifications are given for the main lines. The experimental findings are compared with the theoretical predictions obtained from Hartree-Fock and multiconfiguration Dirac-Fock approaches.

  2. Theoretical study of charge transfer dynamics in collisions of C6+ carbon ions with pyrimidine nucleobases

    Science.gov (United States)

    Bacchus-Montabonel, M. C.

    2012-07-01

    A theoretical approach of the charge transfer dynamics induced by collision of C6+ ions with biological targets has been performed in a wide collision energy range by means of ab-initio quantum chemistry molecular methods. The process has been investigated for the target series thymine, uracil and 5-halouracil corresponding to similar molecules with different substituent on carbon C5. Such a study may be related to hadrontherapy treatments by C6+carbon ions and may provide, in particular, information on the radio-sensitivity of the different bases with regard to ion-induced radiation damage. The results have been compared to a previous analysis concerning the collision of C4+ carbon ions with the same biomolecular targets and significant charge effects have been pointed out.

  3. Theoretical Studies of Gas Phase Elementary and Carbon Nanostructure Growth Reactions

    Science.gov (United States)

    2013-09-19

    DOI: 10.1021/ct1000268. 26. A. J. Midey, T. M. Miller, A. A. Viggiano, N. C. Bera, S. Maeda, and K. Morokuma, Chemistry of VX Surrogates and Ion...THEORETICAL STUDIES OF GAS PHASE ELEMENTARY AND CARBON NANOSTRUCTURE GROWTH REACTIONS KEIJI MOROKUMA EMORY UNIVERSITY 09/19/2013 Final Report...Z39.18 30-09-2013 Final Performance Report 1 July 2010 - 30 June 2013 Theoretical Studies of Gas Phase Elementary and Carbon Nanostructure Growth

  4. Spaced education activates students in a theoretical radiological science course: a pilot study

    Directory of Open Access Journals (Sweden)

    Nkenke Emeka

    2012-05-01

    Full Text Available Abstract Background The present study aimed at determining if the addition of spaced education to traditional face-to-face lectures increased the time students kept busy with the learning content of a theoretical radiological science course. Methods The study comprised two groups of 21 third-year dental students. The students were randomly assigned to a “traditional group” and a “spaced education group”. Both groups followed a traditional face-to-face course. The intervention in the spaced education group was performed in way that these students received e-mails with a delay of 14 days to each face-to-face lecture. These e-mails contained multiple choice questions on the learning content of the lectures. The students returned their answers to the questions also by e-mail. On return they received an additional e-mail that included the correct answers and additional explanatory material. All students of both groups documented the time they worked on the learning content of the different lectures before a multiple choice exam was held after the completion of the course. All students of both groups completed the TRIL questionnaire (Trierer Inventar zur Lehrevaluation for the evaluation of courses at university after the completion of the course. The results for the time invested in the learning content and the results of the questionnaire for the two groups were compared using the Mann–Whitney-U test. Results The spaced education group spent significantly more time (216.2 ± 123.9 min on keeping busy with the learning content compared to the traditional group (58.4 ± 94.8 min, p  Conclusions Adding spaced education to a face-to-face theoretical radiological science course activates students in a way that they spend significantly more time on keeping busy with the learning content.

  5. An experimental and theoretical study of reaction steps relevant to the methanol-to-hydrocarbons reaction

    Energy Technology Data Exchange (ETDEWEB)

    Svelle, Stian

    2004-07-01

    The primary objective of the present work is to obtain new insight into the reaction mechanism of the zeolite catalyzed methanol-to-hydrocarbons (MTH) reaction. It was decided to use both experimental and computational techniques to reach this goal. An investigation of the n-butene + methanol system was therefore initiated. Over time, it became apparent that it was possible to determine the rate for the methylation of n-butene by methanol. The ethene and propene systems were therefore reexamined in order to collect kinetic information also for those cases. With the development of user-friendly quantum chemistry programs such as the Gaussian suite of programs, the possibility of applying quantum chemical methods to many types of problems has become readily available even for non-experts. When performing mechanistic studies, there is quite often a considerable synergy effect when combining experimental and computational approaches. The methylation reactions mentioned above turned out to be an issue well suited for quantum chemical investigations. The incentive for examining the halomethane reactivity was the clear analogy to the MTH reaction system. Alkene dimerization was also a reaction readily examined with quantum chemistry. As discussed in the introduction of this thesis, polymethylbenzenes, or their cationic counterparts, are suspected to be key intermediates in the MTH reaction. It was therefore decided to investigate the intrinsic reactivity of these species in the gas-phase by employing sophisticated mass spectrometric (MS) techniques in collaboration with the MS group at the Department of Chemistry, University of Oslo The data thus obtained will also be compared with results from an ongoing computational study on gas phase polymethylbenzenium reactivity. 6 papers presenting various studies are included. The titles are: 1) A Theoretical Investigation of the Methylation of Alkenes with Methanol over Acidic Zeolites. 2) A Theoretical Investigation of the

  6. An in-depth analysis of theoretical frameworks for the study of care coordination

    Directory of Open Access Journals (Sweden)

    Sabine Van Houdt

    2013-06-01

    Full Text Available Introduction: Complex chronic conditions often require long-term care from various healthcare professionals. Thus, maintaining quality care requires care coordination. Concepts for the study of care coordination require clarification to develop, study and evaluate coordination strategies. In 2007, the Agency for Healthcare Research and Quality defined care coordination and proposed five theoretical frameworks for exploring care coordination. This study aimed to update current theoretical frameworks and clarify key concepts related to care coordination. Methods: We performed a literature review to update existing theoretical frameworks. An in-depth analysis of these theoretical frameworks was conducted to formulate key concepts related to care coordination.Results: Our literature review found seven previously unidentified theoretical frameworks for studying care coordination. The in-depth analysis identified fourteen key concepts that the theoretical frameworks addressed. These were ‘external factors’, ‘structure’, ‘tasks characteristics’, ‘cultural factors’, ‘knowledge and technology’, ‘need for coordination’, ‘administrative operational processes’, ‘exchange of information’, ‘goals’, ‘roles’, ‘quality of relationship’, ‘patient outcome’, ‘team outcome’, and ‘(interorganizational outcome’.Conclusion: These 14 interrelated key concepts provide a base to develop or choose a framework for studying care coordination. The relational coordination theory and the multi-level framework are interesting as these are the most comprehensive.

  7. An in-depth analysis of theoretical frameworks for the study of care coordination

    Directory of Open Access Journals (Sweden)

    Sabine Van Houdt

    2013-06-01

    Full Text Available Introduction: Complex chronic conditions often require long-term care from various healthcare professionals. Thus, maintaining quality care requires care coordination. Concepts for the study of care coordination require clarification to develop, study and evaluate coordination strategies. In 2007, the Agency for Healthcare Research and Quality defined care coordination and proposed five theoretical frameworks for exploring care coordination. This study aimed to update current theoretical frameworks and clarify key concepts related to care coordination. Methods: We performed a literature review to update existing theoretical frameworks. An in-depth analysis of these theoretical frameworks was conducted to formulate key concepts related to care coordination. Results: Our literature review found seven previously unidentified theoretical frameworks for studying care coordination. The in-depth analysis identified fourteen key concepts that the theoretical frameworks addressed. These were ‘external factors’, ‘structure’, ‘tasks characteristics’, ‘cultural factors’, ‘knowledge and technology’, ‘need for coordination’, ‘administrative operational processes’, ‘exchange of information’, ‘goals’, ‘roles’, ‘quality of relationship’, ‘patient outcome’, ‘team outcome’, and ‘(interorganizational outcome’. Conclusion: These 14 interrelated key concepts provide a base to develop or choose a framework for studying care coordination. The relational coordination theory and the multi-level framework are interesting as these are the most comprehensive.

  8. Experimental and theoretical study of the efficiency of a three-electrode reactor for the removal of NO

    Science.gov (United States)

    Gallego, J. L.; Minotti, F.; Grondona, D.

    2014-05-01

    An experimental and theoretical study is presented on the efficiency of the removal of NO in a N2 atmosphere in a novel three-electrode reactor. This reactor combines a dielectric-barrier discharge with a corona discharge, designed to enhance streamer propagation in a relatively large region. Experimentally, the reactor has a good energy yield for the removal of NO, as compared with other discharge methods. A theoretical model is developed for the production of reactive species in the streamers by different reactions that allow to relate simple electrical measurements with the reactor efficiency. This theoretical efficiency resulted in good agreement with the experimental one, validating the model and allowing the evaluation of the contribution of different reactions involved in NO removal.

  9. Comparative study of quantum anharmonic potentials

    Energy Technology Data Exchange (ETDEWEB)

    Amore, Paolo [Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima (Mexico)]. E-mail: paolo@ucol.mx; Aranda, Alfredo [Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima (Mexico); De Pace, Arturo [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, via P. Giuria 1, I-10125 Torino (Italy); Lopez, Jorge A. [Physics Department, University of Texas at El Paso, El Paso, TX (United States)

    2004-09-06

    We perform a study of various anharmonic potentials using a recently developed method. We calculate both the wave functions and the energy eigenvalues for the ground and first excited states of the quartic, sextic and octic potentials with high precision, comparing the results with other techniques available in the literature.

  10. A Comparative Study of Sparse Associative Memories

    Science.gov (United States)

    Gripon, Vincent; Heusel, Judith; Löwe, Matthias; Vermet, Franck

    2016-07-01

    We study various models of associative memories with sparse information, i.e. a pattern to be stored is a random string of 0s and 1s with about log N 1s, only. We compare different synaptic weights, architectures and retrieval mechanisms to shed light on the influence of the various parameters on the storage capacity.

  11. A Comparative Study of Probabilistic Roadmap Planners

    NARCIS (Netherlands)

    Geraerts, R.J.; Overmars, M.H.

    2004-01-01

    The probabilistic roadmap approach is one of the leading motion planning techniques. Over the past eight years the technique has been studied by many different researchers. This has led to a large number of variants of the approach, each with its own merits. It is difficult to compare the different

  12. A comparative study of map use

    DEFF Research Database (Denmark)

    Bouvin, Niels Olof; Brodersen, Ann Christina; Bødker, Susanne

    2006-01-01

    We present a study comparing the handling of three kinds of maps, each on a physical device: a paper map, a tablet-PC based map, and a cellular phone based one. Six groups of users were asked to locate eight landmarks, looking out a window, and using a particular map. We have begun analyzing video...

  13. Theoretical study of the C-H bond dissociation energy of acetylene

    Science.gov (United States)

    Taylor, Peter R.; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

    1990-01-01

    The authors present a theoretical study of the convergence of the C-H bond dissociation energy (D sub o) of acetylene with respect to both the one- and n-particle spaces. Their best estimate for D sub o of 130.1 plus or minus 1.0 kcal/mole is slightly below previous theoretical estimates, but substantially above the value determined using Stark anticrossing spectroscopy that is asserted to be an upper bound.

  14. Experimental and theoretical study of molecular structure of beryllium, magnesium, calcium, strontium and barium 4-nitrobenzoates

    Science.gov (United States)

    Samsonowicz, M.; Regulska, E.; Świsłocka, R.; Lewandowski, W.

    2013-02-01

    The influence of alkaline earth metal ions on the electronic system of 4-nitrobenzoic acid was studied in this paper. The vibrational (FT-IR) and NMR (1H and 13C) spectra were recorded for 4-nitrobenzoic acid (4-nba) and its salts (4-nb). The assignment of vibrational spectra was done. Some shifts of band wavenumbers in alkaline earth metal 4-nitrobenzoates spectra were observed in the series from magnesium to barium salts. Good correlations between wavenumbers of the vibrational bands in the IR spectra of studied salts and ionic potential, electronegativity, inverse of atomic mass, ionic radius and ionization energy of studied metals were found. The regular changes in the chemical shifts of protons (1H NMR) and carbons (13C NMR) in the series of studied salts were also observed. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G** as well as LANL2DZ basis sets. Theoretical wavenumbers and intensities in IR and chemical shifts in NMR spectra were also obtained. The calculated parameters were compared with experimental data of studied compounds.

  15. Experimental and theoretical study of molecular structure of beryllium, magnesium, calcium, strontium and barium 4-nitrobenzoates.

    Science.gov (United States)

    Samsonowicz, M; Regulska, E; Świsłocka, R; Lewandowski, W

    2013-02-15

    The influence of alkaline earth metal ions on the electronic system of 4-nitrobenzoic acid was studied in this paper. The vibrational (FT-IR) and NMR ((1)H and (13)C) spectra were recorded for 4-nitrobenzoic acid (4-nba) and its salts (4-nb). The assignment of vibrational spectra was done. Some shifts of band wavenumbers in alkaline earth metal 4-nitrobenzoates spectra were observed in the series from magnesium to barium salts. Good correlations between wavenumbers of the vibrational bands in the IR spectra of studied salts and ionic potential, electronegativity, inverse of atomic mass, ionic radius and ionization energy of studied metals were found. The regular changes in the chemical shifts of protons ((1)H NMR) and carbons ((13)C NMR) in the series of studied salts were also observed. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G(**) as well as LANL2DZ basis sets. Theoretical wavenumbers and intensities in IR and chemical shifts in NMR spectra were also obtained. The calculated parameters were compared with experimental data of studied compounds.

  16. Sampling artifacts in active air sampling of semivolatile organic contaminants: Comparing theoretical and measured artifacts and evaluating implications for monitoring networks.

    Science.gov (United States)

    Melymuk, Lisa; Bohlin-Nizzetto, Pernilla; Prokeš, Roman; Kukučka, Petr; Klánová, Jana

    2016-10-01

    The effects of sampling artifacts are often not fully considered in the design of air monitoring with active air samplers. Semivolatile organic contaminants (SVOCs) are particularly vulnerable to a range of sampling artifacts because of their wide range of gas-particle partitioning and degradation rates, and these can lead to erroneous measurements of air concentrations and a lack of comparability between sites with different environmental and sampling conditions. This study used specially adapted filter-sorbent sampling trains in three types of active air samplers to investigate breakthrough of SVOCs, and the possibility of other sampling artifacts. Breakthrough volumes were experimentally determined for a range of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) in sampling volumes from 300 to 10,000 m(3), and sampling durations of 1-7 days. In parallel, breakthrough was estimated based on theoretical sorbent-vapor pressure relationships. The comparison of measured and theoretical determinations of breakthrough demonstrated good agreement between experimental and estimated breakthrough volumes, and showed that theoretical breakthrough estimates should be used when developing air monitoring protocols. Significant breakthrough in active air samplers occurred for compounds with vapor pressure >0.5 Pa at volumes Sample volumes between 700 and 10,000 m(3) may lead to breakthrough for compounds with vapor pressures between 0.005 and 0.5 Pa. Breakthrough is largely driven by sample volume and compound volatility (therefore indirectly by temperature) and is independent of sampler type. The presence of significant breakthrough at "typical" sampling conditions is relevant for air monitoring networks, and may lead to under-reporting of more volatile SVOCs.

  17. A Comparative Study on Author's Unreliability

    Institute of Scientific and Technical Information of China (English)

    林映凡

    2016-01-01

    Literature appreciation usually follows a"writer-text-reader" process. The author is an inseparable part in literary discussion. Most literary schools have debate on the author's status, which is mainly sorted into two kinds: reliable author or unreliable author. This paper makes a comparative study on the author's status, which is mainly from the perspectives of New Criticism and Deconstruction. Both of them go for unreliability of the author. They share similarities but also bear differences.

  18. Comparative Study on Richard Ⅲ and Macbeth

    Institute of Scientific and Technical Information of China (English)

    冯丽霞; 闫继苗; 徐婷婷

    2013-01-01

    Shakespeare is one of the most prominent drama writers all over the world. His masterpiece displays vivid, delicate and profound humanity. Richard Ⅲ and Macbeth as the main heroes in his two tragedies of the same theme, share quite a lot of simi⁃larities and differences, yet resulting in sharply different readers’response to their fates. The comparative study on these two char⁃acters is aimed at helping readers better understand the two tragedies.

  19. Theoretical and Experimental Study of Long-Period Grating Refractive Index Sensor

    Science.gov (United States)

    Nidhi; Kaler, R. S.; Kapur, Pawan

    2014-01-01

    This article presents the theoretical and experimental investigation of the response of long-period gratings as a refractive index sensor. Cladding modes are calculated, and results are compared with Optigrating 4.2.2 (Optiwave Systems Inc., Ottawa, Canada). The response has been checked for refractive indices ranging from 1 to 1.458. Theoretically simulated results are in accordance with the experimental results. It was found that the software package calculated values correctly up to the seventh decimal point. The ambient refractive index response of a long-period grating over a much wider index range has been modeled for values both less and more than the cladding refractive index.

  20. Vibronic structure in triatomic molecules : The hydrocarbon flame bands of the formyl radical (HCO). A theoretical study

    OpenAIRE

    Serrano Andrés, Luis; Forsberg, Niclas; Malmqvist, Per-Ake

    1998-01-01

    A theoretical study of the vibrational structure of the math 2A′ ground and math 2A′ excited states of the formyl radical, HCO, and its deuterated form, DCO, has been performed. The potential energy surfaces have been computed by means of a multiconfigurational perturbative method, CASPT2. The computed geometries and the harmonic and anharmonic frequencies are successfully compared to the available experimental information. The vibrational intensities of the transition math 2A′↔math 2A′ have ...

  1. Validation of a Theoretical Model of Diagnostic Classroom Assessment: A Mixed Methods Study

    Science.gov (United States)

    Koh, Nancy

    2012-01-01

    The purpose of the study was to validate a theoretical model of diagnostic, formative classroom assessment called, "Proximal Assessment for Learner Diagnosis" (PALD). To achieve its purpose, the study employed a two-stage, mixed-methods design. The study utilized multiple data sources from 11 elementary level mathematics teachers who…

  2. Theoretical and experimental IR, Raman and NMR spectra in studying the electronic structure of 2-nitrobenzoates

    Science.gov (United States)

    Świsłocka, R.; Samsonowicz, M.; Regulska, E.; Lewandowski, W.

    2007-05-01

    The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of the 2-nitrobenzoic acid (2-NBA) was studied. Optimized geometrical structures of studied compounds were calculated by HF, B3PW91, B3LYP methods using 6-311++G ∗∗ basis set. The theoretical IR and NMR spectra were obtained. The vibrational (FT-IR, FT-Raman) and NMR ( 1H and 13C) spectra for 2-nitrobenzoic acid salts of alkali metals were also recorded. The assignment of vibrational spectra was done. Characteristic shifts of band wavenumbers and changes in band intensities along the metal series were observed. Good correlation between the wavenumbers of the vibrational bands in the IR and Raman spectra for 2-nitrobenzoates (2-NB) and ionic potential, electronegativity, atomic mass and affinity of metals were found. The chemical shifts of protons and carbons ( 1H, 13C NMR) in the series of studied alkali metal 2-nitrobenzoates were observed too. The calculated parameters were compared to experimental characteristic of studied compounds.

  3. Spaced education activates students in a theoretical radiological science course: a pilot study.

    Science.gov (United States)

    Nkenke, Emeka; Vairaktaris, Elefterios; Bauersachs, Anne; Eitner, Stephan; Budach, Alexander; Knipfer, Christian; Stelzle, Florian

    2012-05-23

    The present study aimed at determining if the addition of spaced education to traditional face-to-face lectures increased the time students kept busy with the learning content of a theoretical radiological science course. The study comprised two groups of 21 third-year dental students. The students were randomly assigned to a "traditional group" and a "spaced education group". Both groups followed a traditional face-to-face course. The intervention in the spaced education group was performed in way that these students received e-mails with a delay of 14 days to each face-to-face lecture. These e-mails contained multiple choice questions on the learning content of the lectures. The students returned their answers to the questions also by e-mail. On return they received an additional e-mail that included the correct answers and additional explanatory material.All students of both groups documented the time they worked on the learning content of the different lectures before a multiple choice exam was held after the completion of the course. All students of both groups completed the TRIL questionnaire (Trierer Inventar zur Lehrevaluation) for the evaluation of courses at university after the completion of the course. The results for the time invested in the learning content and the results of the questionnaire for the two groups were compared using the Mann-Whitney-U test. The spaced education group spent significantly more time (216.2 ± 123.9 min) on keeping busy with the learning content compared to the traditional group (58.4 ± 94.8 min, p didactics of the course significantly better than the traditional group (p = .034). The students of the spaced education group also felt that their needs were fulfilled significantly better compared to the traditional group as far as communication with the teacher was concerned (p = .022). Adding spaced education to a face-to-face theoretical radiological science course activates students in a way that

  4. Experimental and Theoretical Study on the Surface Enhanced Raman Mechanism of Pristine and Chemically Doped Graphene

    Science.gov (United States)

    Feng, Simin; Dos Santos, Maria C.; Lu, Ruitao; Elias, Ana L.; Perea-Lopez, Nestor; Terrones, Mauricio

    2014-03-01

    It is demonstrated that graphene could be used as an efficient surface-enhanced Raman spectroscopy (SERS) substrate. Recently, our group has also shown that chemically doped graphene can improve the SERS signal of pristine graphene. Here we present an experimental and theoretical study on the SERS mechanism for both pristine (PG) and Nitrogen-doped graphene (NG). Large-area and highly-crystalline monolayer PG and NG sheets have been synthesized. Common molecules, such as Rhodamine B, Crystal Violet, Methylene Blue and Melamine were used as Raman probes using different laser excitation energies. It was observed that for each molecule, specific laser energy exhibits large intensity Raman signals when compared to others. More importantly, some signals can be detected even for concentrations as low as 10-8 M, which provides excellent molecular sensing properties. Then the system was modeled using DFT-B3LYP/6-31(d,p) and the Mulliken population analysis was used to calculate the net charge on the adsorbed molecules. By comparing the cases of PG and NG, our preliminary results suggest that stronger Raman enhancement of NG would likely be coming from the resonance of EF of graphene and the LUMO level of the adsorbed molecules.

  5. A THEORETICAL AND NUMERICAL STUDY OF THERMOSOLUTAL CONVECTION: STABILITY OF A SALINITY GRADIENT SOLAR POND

    Directory of Open Access Journals (Sweden)

    Djamel Kalache

    2011-01-01

    Full Text Available A theoretical and numerical study of the effect of thermodiffusion on the stability of a gradient layer is presented. It intends to clarify the mechanisms of fluid dynamics and the processes which occur in a salinity gradient solar pond. A mathematical modelling is developed to describe the thermodiffusion contribution on the solar pond where thermal, radiative, and massive fluxes are coupled in the double diffusion. More realistic boundary conditions for temperature and concentration profiles are used. Our results are compared with those obtained experimentally by authors without extracting the heat flux from the storage zone. We have considered the stability analysis of the equilibrium solution. We assumed that the perturbation of quantities such as velocity, temperature, and concentration are infinitesimal. Linearized equations satisfying appropriate prescribed boundary conditions are then obtained and expanded into polynomials form. The Galerkin method along with a symbolic algebra code (Maple are used to solve these equations. The effect of the separation coefficient y is analyzed in the positive and negative case. We have also numerically compared the critical Rayleigh numbers for the onset of convection with those obtained by the linear stability analysis for Le = 100, µa = 0.8, and f = 0.5.

  6. Comparative study of INPIStron and spark gap

    Science.gov (United States)

    Han, Kwang S.; Lee, Ja H.

    1993-01-01

    An inverse pinch plasma switch, INPIStron, was studied in comparison to a conventional spark gap. The INPIStron is under development for high power switching applications. The INPIStron has an inverse pinch dynamics, opposed to Z-pinch dynamics in the spark gap. The electrical, plasma dynamics and radiative properties of the closing plasmas have been studied. Recently the high-voltage pulse transfer capabilities or both the INPIStron and the spark gap were also compared. The INPIStron with a low impedance Z = 9 ohms transfers 87 percent of an input pulse with a halfwidth of 2 mu s. For the same input pulse the spark gap of Z = 100 ohms transfers 68 percent. Fast framing and streak photography, taken with an TRW image converter camera, was used to observe the discharge uniformity and closing plasma speed in both switches. In order to assess the effects of closing plasmas on erosion of electrode material, emission spectra of two switches were studied with a spectrometer-optical multi channel analyzer (OMA) system. The typical emission spectra of the closing plasmas in the INPIStron and the spark gap showed that there were comparatively weak carbon line emission in 658.7 nm and copper (electrode material) line emissions in the INPIStron, indicating low erosion of materials in the INPIStron.

  7. THEORETICAL STUDY OF CO2:N2 ADSORPTION IN FAUJASITE IMPREGNATED WITH MONOETHANOLAMINE

    Directory of Open Access Journals (Sweden)

    A. E. O. Lima

    2015-09-01

    Full Text Available AbstractMany efforts have been made to develop amine-based solid adsorbents for capture of CO2 by adsorption. Compared with the traditional process of absorption in aqueous solutions of amines, the adsorbents with amine immobilized in solids generally result in processes with lower capital and energy costs. The literature contains some experimental studies of CO2 adsorption in impregnated materials; however, few studies are devoted to the theoretical interpretation of this system in terms of CO2 capture for post-combustion (N2 mixture with a low partial pressure of CO2. Therefore, this study investigates the adsorption of a CO2:N2 mixture on zeolite NaX impregnated with monoethanolamine (MEA, using molecular simulation. A model of NaX impregnated with MEA was proposed and the adsorption of a 15:85 (CO2:N2 mixture was investigated based on the Monte Carlo method. The simulation of the MEA impregnated zeolite at 25 ˚C predicted higher CO2 selectivity and significant improvement in the heat of adsorption. Unfortunately, the adsorption heat improvement did not translate into corresponding increases in the amount of adsorbed CO2. Moreover, MEA concentrations higher than 12 wt% hindered the adsorption of CO2molecules. An explanation for the results in terms of occupied volumes and interaction energies is presented.

  8. RETAIL STORE IMAGE: A COMPARISON AMONG THEORETICAL AND EMPIRICAL DIMENSIONS IN A BRAZILIAN STUDY

    Directory of Open Access Journals (Sweden)

    Janaina de Moura Engracia Giraldi

    2008-01-01

    Full Text Available The retail store can be the key success factor, the competitive advantage of a retail company. An important element to the retail strategy is the store image; the total sum of customers’ perceptions about a store. The present paper compares the theoretical and empirical dimensions of retail store’s image in a Brazilian study. The type of research used was the quantitative study, and the data collected was analyzed by use of the factor analysis technique, in order to identify the underlying factors to retail store image. In conclusion, it was observed that the form by which the respondents evaluate the image of a specific supermarket in Brazil is simpler than what was foreseen by theory, with nine factors representing the following store image dimensions: quality,price, after sales service, advertising, clientele, assortment, convenience, atmosphere and services. An important practical contribution of the present study refers to the development of a simpler scale, that can be used by retailers in a viable form to obtain data on their perceived image.

  9. EFQPSK Versus CERN: A Comparative Study

    Science.gov (United States)

    Borah, Deva K.; Horan, Stephen

    2001-01-01

    This report presents a comparative study on Enhanced Feher's Quadrature Phase Shift Keying (EFQPSK) and Constrained Envelope Root Nyquist (CERN) techniques. These two techniques have been developed in recent times to provide high spectral and power efficiencies under nonlinear amplifier environment. The purpose of this study is to gain insights into these techniques and to help system planners and designers with an appropriate set of guidelines for using these techniques. The comparative study presented in this report relies on effective simulation models and procedures. Therefore, a significant part of this report is devoted to understanding the mathematical and simulation models of the techniques and their set-up procedures. In particular, mathematical models of EFQPSK and CERN, effects of the sampling rate in discrete time signal representation, and modeling of nonlinear amplifiers and predistorters have been considered in detail. The results of this study show that both EFQPSK and CERN signals provide spectrally efficient communications compared to filtered conventional linear modulation techniques when a nonlinear power amplifier is used. However, there are important differences. The spectral efficiency of CERN signals, with a small amount of input backoff, is significantly better than that of EFQPSK signals if the nonlinear amplifier is an ideal clipper. However, to achieve such spectral efficiencies with a practical nonlinear amplifier, CERN processing requires a predistorter which effectively translates the amplifier's characteristics close to those of an ideal clipper. Thus, the spectral performance of CERN signals strongly depends on the predistorter. EFQPSK signals, on the other hand, do not need such predistorters since their spectra are almost unaffected by the nonlinear amplifier, Ibis report discusses several receiver structures for EFQPSK signals. It is observed that optimal receiver structures can be realized for both coded and uncoded EFQPSK

  10. CURRICULAR OFFER INFLUENCING STUDENTS’ SATISFACTION: COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    Oana DUMITRASCU

    2014-11-01

    Full Text Available The main objective of the study is the determination of students’ satisfaction regarding curricular activities. The study has been accomplished using the qualitative and quantitative research, using the bibliographic study, various secondary sources and different primary sources. The study is developed with a marketing research and accomplished using the survey method. 699 students from four universities have been questioned. Due to a comparative study the University of Applied Sciences Worms, University of Applied Sciences Wiesbaden Rüsselsheim, University of Applied Sciences Frankfurt am Main and Nürtingen-Geislingen University have been analysed and their similarities and differences have been identified. The collected data, based on the established sample, is evaluated through univariate and bivariate analysis. In accordance with the evaluated sample, specific gaps from each region are identified regarding the curricular offer of the analysed universities. As a result to the conducted study, recommendations for the University of Applied Sciences Worms regarding the student’s satisfaction concerning the curricular offer are presented.

  11. CURRICULAR OFFER INFLUENCING STUDENTS’ SATISFACTION: COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    Oana DUMITRASCU

    2014-11-01

    Full Text Available The main objective of the study is the determination of students’ satisfaction regarding curricular activities. The study has been accomplished using the qualitative and quantitative research, using the bibliographic study, various secondary sources and different primary sources. The study is developed with a marketing research and accomplished using the survey method. 699 students from four universities have been questioned. Due to a comparative study the University of Applied Sciences Worms, University of Applied Sciences Wiesbaden Rüsselsheim, University of Applied Sciences Frankfurt am Main and Nürtingen-Geislingen University have been analysed and their similarities and differences have been identified. The collected data, based on the established sample, is evaluated through univariate and bivariate analysis. In accordance with the evaluated sample, specific gaps from each region are identified regarding the curricular offer of the analysed universities. As a result to the conducted study, recommendations for the University of Applied Sciences Worms regarding the student’s satisfaction concerning the curricular offer are presented.

  12. Medication competency of nurses according to theoretical and drug calculation online exams: A descriptive correlational study.

    Science.gov (United States)

    Sneck, Sami; Saarnio, Reetta; Isola, Arja; Boigu, Risto

    2016-01-01

    Medication administration is an important task of registered nurses. According to previous studies, nurses lack theoretical knowledge and drug calculation skills and knowledge-based mistakes do occur in clinical practice. Finnish health care organizations started to develop a systematic verification processes for medication competence at the end of the last decade. No studies have yet been made of nurses' theoretical knowledge and drug calculation skills according to these online exams. The aim of this study was to describe the medication competence of Finnish nurses according to theoretical and drug calculation exams. A descriptive correlation design was adopted. Participants and settings All nurses who participated in the online exam in three Finnish hospitals between 1.1.2009 and 31.05.2014 were selected to the study (n=2479). Quantitative methods like Pearson's chi-squared tests, analysis of variance (ANOVA) with post hoc Tukey tests and Pearson's correlation coefficient were used to test the existence of relationships between dependent and independent variables. The majority of nurses mastered the theoretical knowledge needed in medication administration, but 5% of the nurses struggled with passing the drug calculation exam. Theoretical knowledge and drug calculation skills were better in acute care units than in the other units and younger nurses achieved better results in both exams than their older colleagues. The differences found in this study were statistically significant, but not high. Nevertheless, even the tiniest deficiency in theoretical knowledge and drug calculation skills should be focused on. It is important to identify the nurses who struggle in the exams and to plan targeted educational interventions for supporting them. The next step is to study if verification of medication competence has an effect on patient safety. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Curriculum, Curriculum Development, Curriculum Studies? Problematising Theoretical Ambiguities in Doctoral Theses in the Education Field

    Science.gov (United States)

    du Preez, Petro; Simmonds, Shan

    2014-01-01

    Theoretical ambiguities in curriculum studies result in conceptual mayhem. Accordingly, they hinder the development of the complicated conversation on curriculum as a verb. This article aims to contribute to reconceptualizing curriculum studies as a dynamic social practice that aspires to thinking and acting with intelligences and sensitivity so…

  14. Deaf Studies: A Critique of the Predominant U.S. Theoretical Direction

    Science.gov (United States)

    Myers, Shirley Shultz; Fernandes, Jane K.

    2010-01-01

    The focus and concerns establishing Deaf Studies in the 1970s have rigidified into a reactive stance toward changing historical conditions and the variety of deaf lives today. This critique analyzes the theoretical foundation of this stance: a tendency to downplay established research in the field of Deaf Studies and linguistics, the employment of…

  15. Theoretical study of loss compensation in long-range dielectric loaded surface plasmon polariton waveguides

    NARCIS (Netherlands)

    García Blanco, Sonia Maria; Pollnau, Markus; Bozhevolnyi, Sergey I.

    In this paper, a theoretical study of loss compensation in long-range dielectric loaded surface plasmon waveguides (LR-DLSPPs) is presented. Although extendable to other gain materials, rare-earth doped double tungstates are used as gain material in this work. Two different structures are studied

  16. Experimental and theoretical study of rapid flows of cohesionless granular materials down inclined chutes

    NARCIS (Netherlands)

    Kruyt, N.P.; Verel, W.J.Th.

    1992-01-01

    A theoretical and experimental study is performed of rapid, fully developed flows of cohesionless granular materials down inclined chutes with a rough base. Two flow types are studied in detail: (1) immature sliding flow, where a stagnant zone forms on the base of the chute, and (2) fully developed

  17. Theoretical study of the dual harmonic system and its application on the CSNS/RCS

    CERN Document Server

    Yuan, Yao-Shuo; Xu, Shou-Yan; Yuan, Yue; Wang, Sheng

    2015-01-01

    The dual harmonic system has been widely used in high intensity proton synchrotrons to suppress the space charge effect, as well as reduce the beam loss. To investigate the longitudinal beam dynamics in the dual rf system, the potential well, the sub-buckets in the bunch and the multi-solutions of the phase equation have been studied theoretically. Based on these theoretical studis, the optimization of bunching factor and rf voltage waveform are made for the dual harmonic rf system in the upgrade phase of the CSNS/RCS. In the optimization process, the simulation with space charge effect is done by using a newly developed code C-SCSIM.

  18. Theoretical/Computational Studies of High-Temperature Superconductivity from Quantum Magnetism

    Science.gov (United States)

    2016-06-09

    AFRL-AFOSR-VA-TR-2016-0204 Theoretical/Computational Studies of High-Temperature Superconductivity from Quantum Magnetism Jose Rodriguez CALIFORNIA...TITLE AND SUBTITLE Theoretical/Computational Studies of High-Temperature Superconductivity from Quantum Magnetism 5a.  CONTRACT NUMBER 5b.  GRANT...SUBJECT TERMS quantum magnetism, HTS, superconductivity 16.  SECURITY CLASSIFICATION OF: 17.  LIMITATION OF       ABSTRACT UU 18.  NUMBER        OF

  19. Theoretical and experimental study of kinetics of photoexcited carriers in wide band gap semiconductors

    Science.gov (United States)

    Shishehchi, Sara; Rudin, Sergey; Garrett, Gregory; Wraback, Michael; Bellotti, Enrico

    2013-03-01

    We present a theoretical and experimental study of the subpicosecond kinetics of photo-excited carriers in the wide band gap semiconductors GaN and ZnO. In the theoretical model, interaction with a photo-excitation laser pulse is treated coherently and a generalized Monte Carlo simulation is used to account for scattering and dephasing. The scattering mechanisms included are carrier interactions with polar optical phonons and acoustic phonons, and carrier-carrier Coulomb interactions. For comparison, experimental time-resolved photoluminescence studies on GaN and ZnO samples are performed over a range of temperatures and excitation powers.

  20. Comparative bioequivalence study of meloxicam drugs

    Directory of Open Access Journals (Sweden)

    Ekut Karieva

    2011-03-01

    Full Text Available The governments of many countries strongly support the production and clinical use of generic medicinal products which are “copies” of patented drugs and can be marked at lower cost. At present time bioequivalence testing is regarded as a useful methodology to perform comparisons among different products containing the same active ingredient. This report presents the results of comparative bioequivalence study of three meloxicam formulations: brand-drug “Melbek” with tablets and capsules of meloxicam developed at the Tashkent Pharmaceutical Institute. The results obtained confirm the bioequivalence of the studied drugs, which indicate about scientifically based approach to the selection of excipients and technological process in the development of the above generic drugs.

  1. EFFICIENCY OF ISO 9001 IN PORTUGAL: A QUALITATIVE STUDY FROM A HOLISTIC THEORETICAL PERSPECTIVE

    Directory of Open Access Journals (Sweden)

    Alcina Dias

    2013-03-01

    Full Text Available The purpose of this paper is to analy se the efficiency of ISO 9001 from a holistic theoretical approach where the Contingency theory, the Institutional theory and the Resources-Based View are integrated. The study was carried out in companies of different sectors of activity in Portugal, based on a qualitative methodology (interviews. The fact of the interviews having been undertaken under an ISO 9001 structure made it easier for companies to grasp the issues under investigation. An ISO 9001 characterisation was carried out on a theoretical framework approach and findings point out efficiency gains and revealed that the absence of ISO 9001 would work as a competitive disadvantage. The contribution of this research aims to reinforce the state of art as concerns the theoretical scope of analysis of these issues enriched by the case study achievement.

  2. The comparative analysis and improvement of theoretic-methodical approaches concerning the estimation of strategy of the large enterprises on the markets with the intensive competition

    Directory of Open Access Journals (Sweden)

    O.A. Bilovodska

    2010-12-01

    Full Text Available In this article the comparative analysis of existent approaches concerning to the estimation of strategies of enterprises is made. Besides, the theoretic-methodical approach concerning the estimation of strategy of the enterprises is improved on the basis of accounting of the strategic aim of the enterprise and also interests of the manufacturer and goods consumer.

  3. Theoretical Study of Wood Microwave Pretreatment in Rectangular Cavity for Fabricating Wood-Based Nanocomposites

    Directory of Open Access Journals (Sweden)

    Yongfeng Luo

    2014-01-01

    Full Text Available Modifying wood by high intensive microwave pretreatment method is widely researched for the fabrication of wood-based nanocomposites, but the temperature uniformity and energy efficiency of microwave pretreatment have not reached the ideal state. In this study, the pretreated wood in rectangular cavity by high intensive microwave is theoretically studied by the finite element method based on the Maxwell electromagnetic field equations and the heat and mass transfer theory. The results show that the temperature uniformity and energy efficiency are related to the microwave feeding modes. Compared with the single-port and the two-port feeding mode, the four-port feeding mode is the best case on temperature uniformity and energy efficiency. The optimized parameters of cavity to pretreatment wood are achieved, which are that the height of cavities is between 0.08 m and 0.11 m in the four-port feeding mode when the thickness of wood is 0.06 m.

  4. Theoretical study of the adsorption of histidine amino acid on graphene

    Science.gov (United States)

    Rodríguez, S. J.; Makinistian, L.; Albanesi, E.

    2016-04-01

    Previous studies have demonstrated how the interactions between biomolecules and graphene play a crucial role in the characterization and functionalization of biosensors. In this paper we present a theoretical study of the adsorption of histidine on graphene using density functional theory (DFT). In order to evaluate the relevance of including the carboxyl (-COOH) and amino (-NH2) groups in the calculations, we considered i) the histidine complete (i.e., with its carboxyl and its amino groups included), and ii) the histidine’s imidazole ring alone. We calculated the density of states for the two systems before and after adsorption. Furthermore, we compared the results of three approximations of the exchange and correlation interactions: local density (LDA), the generalized gradients by Perdew, Burke and Ernzerhof (GGA-PBE), and one including van der Waals forces (DFT-D2). We found that the adsorption energy calculated by DFT-D2 is higher than the other two: Eads-DFT-D2 >E ads-LDA >E ads-GGA . We report the existence of charge transfer from graphene to the molecule when the adsorption occurs; this charge transfer turns up to be greater for the complete histidine than for the imidazole ring alone. Our results revealed that including the carboxyl and amino groups generates a shift in the states of imidazole ring towards EF .

  5. Theoretical and experimental study of foaming process with chain extended recycled PET

    Directory of Open Access Journals (Sweden)

    2009-02-01

    Full Text Available The theoretical and experimental study of a thermoplastic polymer foaming process is presented. Industrial scraps of PET were used for the production of foamed sheets. The process was performed by making use of a chemical blowing agent (CBA in the extrusion process. Due to the low intrinsic viscosity of the recycled PET, a chain extender was also used in order to increase the molecular weight of the polymer matrix. Pyromellitic dianhydride (PMDA and Hydrocerol CT 534 were chosen as chain extender and CBA, respectively. The reactive extrusion and foaming were performed in a two step process. Rheological characterization was carried out on PET samples previously treated with PMDA, as well as the morphological study was performed to define the cellular structure of the foams produced. Moreover, in order to predict the morphology of the foam, a non isothermal model was developed by taking into account both mass transfer phenomenon and viscous forces effect. Model results were compared with experimental data obtained analyzing the foamed samples. The model was validated in relation to working conditions, chemical blowing agent percentage and initial rheological properties of recycled polymer. A pretty good agreement between experimental and calculated data was achieved.

  6. MIP models for connected facility location: A theoretical and computational study.

    Science.gov (United States)

    Gollowitzer, Stefan; Ljubić, Ivana

    2011-02-01

    This article comprises the first theoretical and computational study on mixed integer programming (MIP) models for the connected facility location problem (ConFL). ConFL combines facility location and Steiner trees: given a set of customers, a set of potential facility locations and some inter-connection nodes, ConFL searches for the minimum-cost way of assigning each customer to exactly one open facility, and connecting the open facilities via a Steiner tree. The costs needed for building the Steiner tree, facility opening costs and the assignment costs need to be minimized. We model ConFL using seven compact and three mixed integer programming formulations of exponential size. We also show how to transform ConFL into the Steiner arborescence problem. A full hierarchy between the models is provided. For two exponential size models we develop a branch-and-cut algorithm. An extensive computational study is based on two benchmark sets of randomly generated instances with up to 1300 nodes and 115,000 edges. We empirically compare the presented models with respect to the quality of obtained bounds and the corresponding running time. We report optimal values for all but 16 instances for which the obtained gaps are below 0.6%.

  7. On gel electrophoresis of dielectric charged particles with hydrophobic surface: A combined theoretical and numerical study.

    Science.gov (United States)

    Majee, Partha Sarathi; Bhattacharyya, Somnath; Gopmandal, Partha Pratim; Ohshima, Hiroyuki

    2017-09-21

    A theoretical study on the gel electrophoresis of a charged particle incorporating the effects of dielectric polarization and surface hydrophobicity at the particle-liquid interface is made. A simplified model based on the weak applied field and low charge density assumption is also presented and compared with the full numerical model for a nonpolarizable particle to elucidate the nonlinear effects such as double layer polarization and relaxation as well as surface conduction. The main motivation of this study is to analyze the electrophoresis of the surface functionalized nanoparticle with tunable hydrophobicity or charged fluid drop in gel medium by considering the electrokinetic effects and hydrodynamic interactions between the particle and the gel medium. An effective medium approach, in which the transport in the electrolyte saturated hydrogel medium is governed by the Brinkman equation, is adopted in the present analysis. The governing electrokinetic equations based on the conservation principles is solved numerically. The Navier-slip boundary condition along with the continuity condition of dielectric displacement are imposed on the surface of the hydrophobic polarizable particle. The impact of the slip length on the electrophoresis is profound for a thinner Debye layer, however, surface conduction effect also becomes significant for a hydrophobic particle. Impact of hydrophobicity and relaxation effects are higher for a larger particle. Dielectric polarization creates a reduction in its electrophoretic propulsion and has negligible impact at the thinner Debye length as well as lower gel screening length. This article is protected by copyright. All rights reserved.

  8. Theoretical study of protons damage in materials used in airspace equipment

    Energy Technology Data Exchange (ETDEWEB)

    Stenico, Gabriela V.; Buschini, Renata L.; Inocente, Guilherme F.; Mesa, Joe [Universidade Estadual Paulista (UNESP), Botucatu, SP (Brazil). Inst. de Biociencias de Botucatu. Dept. de Fisica e Biofisica; Pazianotto, Mauricio T. [Instituto Tecnologico de Aeronautica (ITA), Sao Jose dos Campos, SP (Brazil). Inst. de Estudos Avancados

    2011-07-01

    Full text: There is a great ongoing effort to understanding the effect of dose levels of ionizing radiation from cosmic rays (CR) received by pilots, aircraft crew and sensitive equipment (avionics). A large part of Brazil and South America are subject to the South Atlantic Magnetic Anomaly. Differently to other places in the world, few measurements exist in this region of the radiation distribution due to cosmic ray penetration as a function of altitude, which is an important ingredient in the study of protons interactions with the materials that constitute the aircraft as well as for other spacecraft and satellites components, mainly the electronic sensitive equipment. In this sense, it is relevant to know the processes of interaction of protons with Si (semiconductor material) and Ta (metal), which are widely used with this purpose. Also with the objective to decrease the damage from the interactions of protons with these materials, it is commonly used Al slice like shield. The aim of this work is to study by Monte Carlo simulation the behavior of these materials as targets with protons of energies between 300 and 400 MeV, mainly by calculating the energy deposition, the most likely path of the protons in the target, and also the ionizing process. In this sense we used two codes: the first code was the SRIM 2008 and the MCNPX v.2.5. The theoretical results will be compared with some preliminary experimental ones obtained by IEAv (Instituto de Estudos Avancados) - ITA (Instituto Tecnologico de Aeronautica). (author)

  9. Spectral investigation and theoretical study of zwitterionic and neutral forms of quinolinic acid

    Science.gov (United States)

    Karabacak, M.; Sinha, L.; Prasad, O.; Bilgili, S.; Sachan, Alok K.; Asiri, A. M.; Atac, A.

    2015-09-01

    In this study, molecular structure and vibrational analysis of quinolinic acid (2,3-pyridinedicarboxylic acid), in zwitterionic and neutral forms, were presented using FT-IR, FT-Raman, NMR, UV experimental techniques and quantum chemical calculations. FT-IR and FT-Raman spectra of 2,3-pyridinedicarboxylic acid (2,3-PDCA) in the solid phase were recorded in the region 4000-400 cm-1 and 3500-0 cm-1, respectively. The geometrical parameters and energies were obtained for zwitter and neutral forms by using density functional theory (DFT) at B3LYP/6-311++G(d,p) level of theory. 3D potential energy scan was performed by varying the selected dihedral angles using M06-2X and B3LYP functionals at 6-31G(d) level of theory and thus the most stable conformer of the title compound was determined. The most stable conformer was further optimized at higher level and vibrational wavenumbers were calculated. Theoretical vibrational assignment of 2,3-PDCA, using percentage potential energy distribution (PED) was done with MOLVIB program. 13C and 1H NMR spectra were recorded in DMSO. Chemical shifts were calculated at the same level of theory. The UV absorption spectra of the studied compound in ethanol and water were recorded in the range of 200-400 nm. The optimized geometric parameters were compared with experimental data.

  10. A comparative study of teenage pregnancy.

    Science.gov (United States)

    Mahavarkar, S H; Madhu, C K; Mule, V D

    2008-08-01

    Teenage pregnancy is a global problem and is considered a high-risk group, in spite of conflicting evidence. Our objective was to compare obstetric outcomes of pregnancy in teenagers and older women. This was a retrospective study of case records of pregnancies from August 2000 to July 2001. Girls aged pregnancy outcomes in older women (19-35 years) in the same hospital. The study took place in the Government General Hospital, Sangli, India, a teaching hospital in rural India, with an annual delivery rate of over 3,500. A total of 386 teenage pregnancies were compared with pregnancies in 3,326 older women. Socioeconomic data, age, number of pregnancies, antenatal care and complications, mode of delivery, and neonatal outcomes were considered. The incidence of teenage pregnancy in the study was 10%. A significant proportion of teenage pregnant mothers were in their first pregnancies. The teenage mothers were nearly three times more at risk of developing anaemia (OR = 2.83, 95% CI = 2.2-3.7, p Teenage mothers were twice as likely to develop hypertensive problems in pregnancy (OR = 2.2, 95% CI = 1.5-3.2, p teenage pregnancies are still a common occurrence in rural India in spite of various legislations and government programmes and teenage pregnancy is a risk factor for poor obstetric outcome in rural India. Cultural practices, poor socioeconomic conditions, low literacy rate and lack of awareness of the risks are some of the main contributory factors. Early booking, good care during pregnancy and delivery and proper utilisation of contraceptive services can prevent the incidence and complications in this high-risk group.

  11. Theoretical study of the transverse acoustic phonons of GaSb at high pressure

    Indian Academy of Sciences (India)

    S Shinde; M Talati; Prafulla K Jha; S P Sanyal

    2004-08-01

    We have investigated the phonon dispersion curves and one-phonon density of states up to the pressure of 8 GPa using a theoretical model, namely the rigid ion model. The transverse acoustic phonons as a function of pressure have been compared with the recently measured inelastic neutron scattering data which show a strong softening near the zone boundaries. The calculated one-phonon density of states show pronounced shift in the peak positions with the increase in pressure.

  12. Theoretical study of phenyl-substituted indacenodithiophene copolymers for high performance organic photovoltaics.

    Science.gov (United States)

    Chochos, Christos L; Avgeropoulos, Apostolos; Lidorikis, Elefterios

    2013-02-14

    The theoretical estimation of energy levels and energy gaps of conjugated polymers for organic photovoltaics (OPVs) represents in principle a useful tool for the prescreening of new donor systems as a suitable pair for the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM). In this study, ten tetraphenyl-substituted indacenodithiophene (IDT) copolymers (eight in the form of donor-acceptor), whose energy gaps vary in the range of 1.48-2.11 eV have been selected and their highest occupied molecular orbitals (HOMOs), lowest unoccupied molecular orbitals (LUMOs), and gap energies have been calculated by applying density functional theory (DFT) and/or time-dependent density functional theory (TD-DFT) methods. In spite of the examined molecular structure variety, nice correlations (theoretical models) between experimental and theoretical electronic parameters were found. It is shown that the theoretical band gap estimated by the TD-DFT using dimer model compounds and DFT using tetramer model compounds provide in good agreement the optical band gap of these polymers. Finally, the optimum theoretical limits of the LUMO offset between the fullerene and the IDT tetramer model compounds, for which high performance OPVs (efficiency > 6%) are obtained, is presented for the first time.

  13. Comparative microscopy study of Vibrio cholerae flagella

    Science.gov (United States)

    Konnov, Nikolai P.; Baiburin, Vil B.; Zadnova, Svetlana P.; Volkov, Uryi P.

    1999-06-01

    A fine structure of bacteria flagella is an important problem of molecular cell biology. Bacteria flagella are the self-assembled structures that allow to use the flagellum protein in a number of biotechnological applications. However, at present, there is a little information about high resolution scanning probe microscopy study of flagellum structure, in particular, about investigation of Vibrio cholerae flagella. In our lab have been carried out the high resolution comparative investigation of V. cholerae flagella by means of various microscopes: tunneling (STM), scanning force (SFM) and electron transmission. As a scanning probe microscope is used designed in our lab versatile SPM with replaceable measuring heads. Bacteria were grown, fixed and treated according to the conventional techniques. For STM investigations samples were covered with Pt/Ir thin films by rotated vacuum evaporation, in SFM investigations were used uncovered samples. Electron microscopy of the negatively stained bacteria was used as a test procedure.

  14. Comparative studies on ecotoxicology of synthetic detergents.

    Science.gov (United States)

    Lal, H; Misra, V; Viswanathan, P N; Krishna Murti, C R

    1983-12-01

    To predict the comparative toxicological response of synthetic detergents on aquatic ecosystems, the effects of various concentrations of neutralized alkyl benzene sulfonate were studied. The median tolerance limit at 48 hr, 95% confidence limit, slope function, presumable harmless concentration, and rate of survival of different species of aquatic fauna such as water fleas (Daphnia magna), mosquito larvae (Culex pipiens), slug worms (Tubifex rivulorum), snails (Lymnaea vulgaris), tadpoles (Rana cyanophlyctis), and fish fingerlings (Cirrhina mrigala) were followed at 0, 24, 48, 72, and 96 hr. Any effect on quality of the water was also tested after the addition of various concentrations of detergents. The results showed that water fleas are more susceptible to detergent toxicity than fish fingerlings, tadpoles, slug worms, snails, and mosquito larvae. Behavioral changes were also observed as an index for detergent toxicity. The relative toxicity of the detergents to various species is discussed in relation to selective ecotoxicological response.

  15. A COMPARATIVE STUDY IN WIRELESS SENSOR NETWORKS

    Directory of Open Access Journals (Sweden)

    Hasan Al-Refai

    2014-02-01

    Full Text Available Sensor networks consist of a large number of small, low-powered wireless nodes with limited computation, communication, and sensing abilities, in a battery-powered sensor network, energy and communication bandwidth are a precious resources. Thus, there is a need to adapt the networking process to match the application in order to minimize the resources consumed and extend the life of the network. In this paper, we introduce a comparative study in different routing algorithms that propose vital solutions to the most important issues that should be taken into account when designing wireless network which are reliability, lifetime, communication bandwidth, transmission rand, and finally the limited energy issue, so we will introduce their algorithms and discuss how did they propose to solve such of these challenges and finally we will do some evaluation to each approach.

  16. Initial teacher education in Japan and Spain. A comparative study

    Directory of Open Access Journals (Sweden)

    Eva Ramírez Carpeño

    2015-06-01

    Full Text Available The purpose of this article is to examine, from a comparative perspective, the initial teacher training systems in Spain and Japan. We will analyze the current design of teacher educational programs, from Infant level to Secondary level. The relevance of teacher performances has been endorsed by several studies, placing international attention on teachers’ training policies. The results show similar trends relating to programs’ structure and students’ selection. Nevertheless, there are many differences when analyzing duration, flexibility or accreditation, which could provided us with key elements to reflect upon our own educational context. Such reflections could contribute to the improvement of our teachers’ training systems, the promotion of theoretical and practical development on educational policies, and a higher quality of educational practices. 

  17. COSMOS - a study comparing peripheral intravenous systems.

    Science.gov (United States)

    López, Juan Luis González; Del Palacio, Encarnación Ferenández; Marti, Carmen Benedicto; Corral, Javier Olivares; Portal, Pilar Herrera; Vilela, Ana Arribi

    In many areas of the world, safety peripheral intravenous systems have come into widespread use. The Madrid region was the first in Spain to adopt such an approach. These systems, though initially introduced to protect users from sharps injuries, have now evolved to include patient protection features as well. Patient protection, simply stated, means closing the system to pathogen entry. The authors' purpose was to investigate, in a prospective and randomized study, the clinical performance of a closed safe intravenous system versus an open system (COSMOS - Compact Closed System versus Mounted Open System). COSMOS is designed to provide definitive answers, from a nursing perspective, to many topics related to peripheral venous catheterization, which have important implications in intravenous therapy and which have not been validated scientifically. Furthermore, it forms pioneering research in that it is the first clinical trial on medical devices in a legislated environment carried out entirely by nurses and whose promoter and principal investigator is a nurse. The objectives of COSMOS are to compare the effectiveness (as defined by time of survival without complications) and rates of catheter-related complications, such as phlebitis, pain, extravasation, blockage and catheter-related infections. It also looks at rates of catheter colonization, the ease of handling of both systems and overall costs. This article outlines the authors' approach, both in preparing hospital units for such an evaluation as well as in the choice of parameters and their method of study. Further articles will detail the results and findings of the study.

  18. Coarse grained molecular dynamics and theoretical studies of carbon nanotubes entering cell membrane

    Institute of Scientific and Technical Information of China (English)

    Xinghua Shi; Yong Kong; Huajian Gao

    2008-01-01

    Motivated by recent experimental observations that carbon nanotubes (CNT) can enter animal cells, here we conduct coarse grained molecular dynamics and theore-tical studies of the intrinsic interaction mechanisms between CNT's and lipid bilayer. The results indicate that CNT-cell interaction is dominated by van der Waals and hydropho-bic forces, and that CNT's with sufficiently small radii can directly pierce through cell membrane while larger tubes tend to enter cell via a wrapping mechanism. Theoretical models are proposed to explain the observed size effect in transition of entry mechanisms.

  19. Theoretical study on the ultra-narrow bandwidth tunable atomic filter with electromagnetically induced transparency

    Science.gov (United States)

    Liu, Yang; Li, Shu-qing; Feng, Zhong-ying; Liu, Xiao-fei; Gao, Jin-yue

    2016-12-01

    To obtain the weak signal light detection from the high background noise, we present a theoretical study on the ultra-narrow bandwidth tunable atomic filter with electromagnetically induced transparency. In a three-level Λ -type atomic system in the rubidium D1 line, the bandwidth of the EIT atomic filter is narrowed to ~6.5 \\text{MHz} . And the single peak transmission of the filter can be up to 86% . Moreover, the transmission wavelength can be tuned by changing the coupling light frequency. This theoretical scheme can also be applied to other alkali atomic systems.

  20. Red/blue shifting hydrogen bonds in acetonitrile-dimethyl sulphoxide solutions: FTIR and theoretical studies

    Science.gov (United States)

    Kannan, P. P.; Karthick, N. K.; Mahendraprabu, A.; Shanmugam, R.; Elangovan, A.; Arivazhagan, G.

    2017-07-01

    FTIR spectra of neat acetonitrile (AN), dimethyl sulphoxide (DMSO) and their binary solutions at various mole fractions have been recorded at room temperature. Theoretical calculations have also been carried out on acetonitrile (monomer, dimer), dimethyl sulphoxide (monomer, dimer) and AN - DMSO complex molecules. 1:2 (AN:DMSO) and 2:1 complexation through the red shifting (AN) C - H ⋯ O = S(DMSO) and blue shifting (DMSO) C - H ⋯ N ≡ C(AN) hydrogen bonds has been identified. The experimental and theoretical studies favour the presence of both the monomer and dimer in liquid AN, but only closed dimers in DMSO. The dipole-dipole interactions existed in AN and DMSO dimers disappear in the complex molecules. Partial π bond between S and O atoms, and three lone pair of electrons on oxygen atom of DMSO have been noticed theoretically.

  1. THEORETICAL STUDY OF HEAT TRANSFER ENHANCEMENT IN PIPE WITH POROUS BODY

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A theoretical investigation of the fluid flow and heat transferin a pipe with porous body of high porosity twis ted by metal wire was carried out. A theoretical model of a circular pipe with porous matrix attached at the channel wall and extended inward the centerline was set up. Through ana lyzing the flow in the porous matrix by the Brinkman-extend ed-Darcy equation and through including the effect of disper sion by adding the dispersion coefficient into the energy equa tion, the theoretical solutions of velocity distribution and temperature fields were obtained. Finally the effect of the properties of the porous matrix on the flow and heat transfer in the porous body was studied, which indicates that dispersion can really enhance the heat transfer in pipe.

  2. Theoretical studies of Q1D organic conductors:a personal view

    OpenAIRE

    Celebonovic, V.

    2004-01-01

    This is a review of some aspects of theoretical studies of the Bechgaard salts,which also retraces the evolution of the author's interest in the field.It discusses the calculation of the condutivity,attempts at gaining some knowledge on the EOS and thermal properties of these materials,as well as some ideas on the possible future developement of the field.

  3. Review of The Theoretical and Empirical Study on the Interest Conflict Between City Groups

    Institute of Scientific and Technical Information of China (English)

    Guo; Zeguang; Qian; Fang

    2016-01-01

    The Theoretical and Empirical Study on the Interest Conflict Between City Groups Author:Miao Jianjun Year:2014Publisher:Economy&Management Publishing House ISBN:9787509629482(240 pages,in Chinese)Since the application of the strategy"Rising of Central China,"provinces in China’s central region consecutively released their development

  4. Theoretical study of the electromechanical efficiency of a loaded tubular dielectric elastomer actuator

    DEFF Research Database (Denmark)

    Rechenbach, Björn; Willatzen, Morten; Lassen, Benny

    2016-01-01

    The electromechanical efficiency of a loaded tubular dielectric elastomer actuator (DEA) is investigated theoretically. In previous studies, the external system, on which the DEA performs mechanical work, is implemented implicitly by prescribing the stroke of the DEA in a closed operation cycle...

  5. Studying Activities That Take Place in Speech Interactions: A Theoretical and Methodological Framework

    Science.gov (United States)

    Saint-Dizier de Almeida, Valérie; Colletta, Jean-Marc; Auriac-Slusarczyk, Emmanuelle; Specogna, Antonietta; Simon, Jean-Pascal; Fiema, Gabriela; Luxembourger, Christophe

    2016-01-01

    The paper proposes a theoretical and methodological framework based on a pluralistic, concerted approach to the study of activities that take place in and through speech interactions. The framework has a general scope, applying to any collective activity taking form through language interactions. It contributes to a fuller understanding of the…

  6. Theoretical Studies of Laws Nanostructuring and Heterogeneous Hardening of Steel Samples by Wave Intensive Plastic Deformation

    Directory of Open Access Journals (Sweden)

    A.V. Kirichek

    2015-12-01

    Full Text Available Theoretical studies and calculations, allowing to define the required parameters of the wave deformation hardening, are performed in order to obtain heterogeneous hardened surface layer in steel samples. The conditions for the effective use of impact energy for elastic-plastic deformation of the processed material and the establishment of a deep hardened surface layer are revealed.

  7. Liquid phase demixing in ferroelectric/semiconducting polymer blends: an experimental and theoretical study

    NARCIS (Netherlands)

    Michels, J.J.; Breemen, A.J.J.M. van; Usman, K.; Gelinck, G.H.

    2011-01-01

    This article describes a combined experimental and theoretical study on nanophase structure development as a result of liquid phase demixing in solution-cast blends of the organic semiconductor poly(9,9'-dioctyl fluorene) (PFO) and the ferroelectric polymer poly(vinylidene fluoride-co-trifluoroethyl

  8. Mems Q-Factor Enhancement Using Parametric Amplification: Theoretical Study and Design of a Parametric Device

    CERN Document Server

    Grasser, L; Parrain, F; Roux, X Le; Gilles, J -P

    2008-01-01

    Parametric amplification is an interesting way of artificially increasing a MEMS Quality factor and could be helpful in many kinds of applications. This paper presents a theoretical study of this principle, based on Matlab/Simulink simulations, and proposes design guidelines for parametric structures. A new device designed with this approach is presented together with the corresponding FEM simulation results.

  9. A theoretical framework to study variations in workplace violence experienced by emergency responders

    NARCIS (Netherlands)

    L. van Reemst (Lisa)

    2016-01-01

    markdownabstractEmergency responders are often sent to the front line and are often confronted with aggression and violence in interaction with citizens. According to previous studies, some professionals experience more workplace violence than others. In this article, the theoretical framework to st

  10. A Theoretical Framework to Study Variations in Workplace Violence Experienced by Emergency Responders

    NARCIS (Netherlands)

    L. van Reemst (Lisa)

    2016-01-01

    textabstractEmergency responders are often sent to the front line and are often confronted with aggression and violence in inter- action with citizens. According to previous studies, some professionals experience more workplace violence than others. In this article, the theoretical framework to stud

  11. Theoretical and Experimental Study of Scattering of a Plane Wave by an Inhomogeneous Plasma Sphere

    Institute of Scientific and Technical Information of China (English)

    SONG Fa-Lun; CAO Jin-Xiang; WANG Ge; WANG Yan; ZHU Ying; ZHU Jian; WANG Liang; NIU Tian-Ye

    2006-01-01

    @@ Scattering of electromagnetic waves by an inhomogeneous plasma sphere has been studied theoretically and experimentally. The offset angles of electromagnetic waves caused by the plasma sphere have been observed experimentally. The effects of the electromagnetic wave frequency and plasma density on the offset angle are discussed. The plasma density is estimated with the offset angle.

  12. A theoretical framework to study variations in workplace violence experienced by emergency responders

    NARCIS (Netherlands)

    L. van Reemst (Lisa)

    2016-01-01

    markdownabstractEmergency responders are often sent to the front line and are often confronted with aggression and violence in interaction with citizens. According to previous studies, some professionals experience more workplace violence than others. In this article, the theoretical framework to

  13. A Theoretical Framework to Study Variations in Workplace Violence Experienced by Emergency Responders

    NARCIS (Netherlands)

    L. van Reemst (Lisa)

    2016-01-01

    textabstractEmergency responders are often sent to the front line and are often confronted with aggression and violence in inter- action with citizens. According to previous studies, some professionals experience more workplace violence than others. In this article, the theoretical framework to

  14. Theoretical study of the ground state of (EDO-TTF)(2)PF6

    NARCIS (Netherlands)

    Linker, Gerrit-Jan; van Duijnen, Piet Th.; van Loosdrecht, Paul H.M.; Broer, Ria

    2015-01-01

    In this paper we present a theoretical study of the nature of the ground state of the (EDO-TTF)(2)PF6 charge transfer salt by using ab initio quantum chemical theory for clusters in vacuum, for embedded clusters and for the periodic system. Exemplary for other organic charge transfer systems, we sho

  15. [Habermas and Paulo Freire: theoretical referrals for the study on communication in nursing].

    Science.gov (United States)

    Larocca, Liliana Muller; Mazza, Verônica de Azevedo

    2003-08-01

    The present work has the objective of introducing the ideas of Jürgen Habermas and Paulo Freire about the dialogue as a fundamental human phenomenon, data on their trajectories of life, ideological approaches when locating the human being through history and their relevance as theoretical referrals for the study on communication in the process of the nurse's work.

  16. Theoretical and experimental study of the vibrational excitations in ethane monolayers adsorbed on graphite (0001) surfaces

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Taub, H.

    1987-01-01

    The collective vibrational excitations of two different crystalline monolayer phases of ethane (C2H6) adsorbed on the graphite (0001) surface have been investigated theoretically and experimentally. The monolayer phases studied are the commensurate 7/8 ×4 structure in which the ethane molecules lie...

  17. Theoretical Study of Hydrated Cd~(2+) Interactions with Guanine

    Institute of Scientific and Technical Information of China (English)

    王敏; 洒荣建; 吴克琛; 李巧红; 韦永勤

    2012-01-01

    Theoretical study was performed to investigate how the hydration of cadmium ca-tion influences the structure and properties of guanine.The aqueous environment was simulated by both explicit solvent(1-5 water molecules) model and implicit solvent model.For complexes in which Cd2+ attached to the N(7) and O(6) sites of guanine,energy analysis together with the Natural Bonding Orbital(NBO) analysis were performed to elucidate the bonding characteristics in detail.The most stable structures are penta-coordinate complexes without aqua ligand located at the guanine site.Higher number of water ligands corresponds to higher stabilization energies.Average bonding energies of G-Cd increase with the number of water molecules.Bonding energies of water ligands depend on its position in the complexes.The charge distribution of guanine changed with increasing the number of water ligands,which may also influence the base-pairing pattern of guanine.There is positive charge transfer from guanine to aqua ligand as the number of the hydration waters increases.IEFPCM optimization has results comparable to the [CdG(H2O)5]2+ structure 5a.

  18. Theoretical Study of Intramolecular Interactions in Peri-Substituted Naphthalenes: Chalcogen and Hydrogen Bonds

    Directory of Open Access Journals (Sweden)

    Goar Sánchez–Sanz

    2017-02-01

    Full Text Available A theoretical study of the peri interactions, both intramolecular hydrogen (HB and chalcogen bonds (YB, in 1-hydroxy-8YH-naphthalene, 1,4-dihydroxy-5,8-di-YH-naphthalene, and 1,5-dihydroxy-4,8-di-YH-naphthalene, with Y = O, S, and Se was carried out. The systems with a OH:Y hydrogen bond are the most stable ones followed by those with a chalcogen O:Y interaction, those with a YH:O hydrogen bond (Y = S and Se being the least stable ones. The electron density values at the hydrogen bond critical points indicate that they have partial covalent character. Natural Bond Orbital (NBO analysis shows stabilization due to the charge transfer between lone pair orbitals towards empty Y-H that correlate with the interatomic distances. The electron density shift maps and non-covalent indexes in the different systems are consistent with the relative strength of the interactions. The structures found on the CSD were used to compare the experimental and calculated results.

  19. A theoretical study on C-COOH homolytic bond dissociation enthalpies.

    Science.gov (United States)

    Shi, Jing; Huang, Xiong-Yi; Wang, Jun-Peng; Li, Run

    2010-06-01

    The knowledge of C-COOH homolytic bond dissociation enthalpies (BDEs) is of great importance in understanding various chemical and biochemical processes involving the decarboxylation reaction. In the present study, the density functional theory (DFT method), B3P86/6-311++G(2df,2p)//B3LYP/6-31+G(d), is found to be reliable to predict the C-COOH BDE of various structurally unrelated carboxylic acids. The mean absolute deviation (MAD) and root-mean-square deviation (rmsd) of this optimal method are equal to 2.0 and 2.5 kcal/mol, respectively. With the authorized theoretical protocol in hand, an extensive C-COOH BDE scale containing over 100 carboxylic acids has been established. The availability of this body of data enabled a detailed investigation of remote substituent effect on four types of carboxylic acids, including para-substituted benzoic acid, beta-substituted cis-propenoic acid, beta-substituted trans-propenoic acid, and substituted propiolic acid. Also with the C-COOH BDE data obtained in this work, an excellent linear relationship has been found between the C-COOH BDE of carboxylic acids and the C-H BDE of their hydrocarbon analogues. After comparing the energy barrier of the Pd-catalyzed decarboxylation reaction (DeltaG(decarboxylation)++) with the related C-COOH BDE, a negative correlation between the DeltaG(decarboxylation)++ and the C-COOH BDE was found.

  20. Theoretical study of the oxidation mechanisms of thiophene initiated by hydroxyl radicals.

    Science.gov (United States)

    Shiroudi, Abolfazl; Deleuze, Michael S

    2015-11-01

    The mechanisms for the oxidation of thiophene by OH radicals under inert conditions (Ar) have been studied using density functional theory in conjunction with various exchange-correlation functionals. These results were compared with benchmark CBS-QB3 theoretical results. Kinetic rate constants were estimated by means of variational transition state theory (VTST) and the statistical Rice-Ramsperger-Kassel-Marcus (RRKM) theory. Effective rate constants were calculated via a steady-state analysis based upon a two-step model reaction mechanism. In line with experimental results, the computed branching ratios indicate that the most kinetically efficient process involves OH addition to a carbon atom adjacent to the sulfur atom. Due to the presence of negative activation energies, pressures larger than 10(4) bar are required to reach the high-pressure limit. Nucleus-independent chemical shift indices and natural bond orbital analysis show that the computed activation energies are dictated by changes in aromaticity and charge-transfer effects due to the delocalization of lone pairs from sulfur to empty π(*) orbitals. Graphical Abstract CBS-QB3 energy profiles for the reaction pathways 1-3 characterizing the oxidation of thiophene by hydroxyl radicals into the related products.

  1. Theoretical Study of Monolayer and Double-Layer Waveguide Love Wave Sensors for Achieving High Sensitivity.

    Science.gov (United States)

    Li, Shuangming; Wan, Ying; Fan, Chunhai; Su, Yan

    2017-03-22

    Love wave sensors have been widely used for sensing applications. In this work, we introduce the theoretical analysis of the monolayer and double-layer waveguide Love wave sensors. The velocity, particle displacement and energy distribution of Love waves were analyzed. Using the variations of the energy repartition, the sensitivity coefficients of Love wave sensors were calculated. To achieve a higher sensitivity coefficient, a thin gold layer was added as the second waveguide on top of the silicon dioxide (SiO₂) waveguide-based, 36 degree-rotated, Y-cut, X-propagating lithium tantalate (36° YX LiTaO₃) Love wave sensor. The Love wave velocity was significantly reduced by the added gold layer, and the flow of wave energy into the waveguide layer from the substrate was enhanced. By using the double-layer structure, almost a 72-fold enhancement in the sensitivity coefficient was achieved compared to the monolayer structure. Additionally, the thickness of the SiO₂ layer was also reduced with the application of the gold layer, resulting in easier device fabrication. This study allows for the possibility of designing and realizing robust Love wave sensors with high sensitivity and a low limit of detection.

  2. Modeling of air-gap membrane distillation process: A theoretical and experimental study

    KAUST Repository

    Alsaadi, Ahmad Salem

    2013-06-03

    A one dimensional (1-D) air gap membrane distillation (AGMD) model for flat sheet type modules has been developed. This model is based on mathematical equations that describe the heat and mass transfer mechanisms of a single-stage AGMD process. It can simulate AGMD modules in both co-current and counter-current flow regimes. The theoretical model was validated using AGMD experimental data obtained under different operating conditions and parameters. The predicted water vapor flux was compared to the flux measured at five different feed water temperatures, two different feed water salinities, three different air gap widths and two MD membranes with different average pore sizes. This comparison showed that the model flux predictions are strongly correlated with the experimental data, with model predictions being within +10% of the experimentally determined values. The model was then used to study and analyze the parameters that have significant effect on scaling-up the AGMD process such as the effect of increasing the membrane length, and feed and coolant flow rates. The model was also used to analyze the maximum thermal efficiency of the AGMD process by tracing changes in water production rate and the heat input to the process along the membrane length. This was used to understand the gain in both process production and thermal efficiency for different membrane surface areas and the resultant increases in process capital and water unit cost. © 2013 Elsevier B.V.

  3. Experimental and Theoretical Study of Sandwich Panels with Steel Facesheets and GFRP Core

    Directory of Open Access Journals (Sweden)

    Hai Fang

    2016-01-01

    Full Text Available This study presented a new form of composite sandwich panels, with steel plates as facesheets and bonded glass fiber-reinforced polymer (GFRP pultruded hollow square tubes as core. In this novel panel, GFRP and steel were optimally combined to obtain high bending stiffness, strength, and good ductility. Four-point bending test was implemented to analyze the distribution of the stress, strain, mid-span deflection, and the ultimate failure mode. A section transformation method was used to evaluate the stress and the mid-span deflection of the sandwich panels. The theoretical values, experimental results, and FEM simulation values are compared and appeared to be in good agreement. The influence of thickness of steel facesheet on mid-span deflection and stress was simulated. The results showed that the mid-span deflection and stress decreased and the decent speed was getting smaller as the thickness of steel facesheet increases. A most effective thickness of steel facesheet was advised.

  4. Theoretical study on oligothiophene N-succinimidyl esters: size and push-pull effects.

    Science.gov (United States)

    Piacenza, M; Zambianchi, M; Barbarella, G; Gigli, G; Della Sala, F

    2008-09-21

    We report a theoretical study on the optical properties of bithiophene and terthiophene N-succinimidyl esters, which have been functionalized with a methylsulfanyl group in the alpha or the beta positions. Time-dependent density functional theory (TD-DFT) and approximate coupled-cluster singles and doubles with the resolution of identity technique (RI-CC2) calculations have been performed in the ground and excited states. The RI-CC2 results for absorption and fluorescence energies are in better qualitative agreement with experiments, whereas TD-DFT does not correctly describe the higher energy part of the absorption spectra of beta-substituted bithiophenes, due to the presence of charge-transfer states. Systems functionalized at the alpha position show a large red-shift of the main absorption and fluorescence band and a larger Stokes-shift compared to the unsubstituted species. These effects are in most cases less pronounced for the beta-substituted structures. In particular, we found that the Stokes-shift of the alpha-substituted structures is larger than the one of the beta-substituted species due to a more planar orientation of the methylsulfanyl group with respect to the neighbouring thiophene in the excited state.

  5. Theoretical and Experimental Study of the Solar Still Coupled To a Vertical Still with Water Film

    Directory of Open Access Journals (Sweden)

    Mohammed Mustapha Belhadj

    2014-03-01

    Full Text Available Solar distillation is one of the simplest processes and the most significant of separation. A solar distiller of new design was built by the coupling of two confused devices which are; a conventional solar distiller with only one slope directed towards the south, with what we name a Solar Still with Capillary Film (or SSCF; It consists of a parallelepipedic compartment formed by two plates opposite face to face and drawn aside from a distance from 0.03m, which devote an advantage of re-use of the condensation latent heat to evaporate another quantity of water. We developed a digital code which makes it possible to obtain the values of the temperatures and the rate of condensation of this devise. In this work we consider the comparative study between the theoretical results, and those measured in experiments. We numerically found a rate of condensation very important which reaches 8,43Kg.m -2 .d -1 , and which approaches to that obtained in experiments, in sunny day (correspondent at 06/8/2007, and a solar radiation of 20,7 MJ.m -2 .d -1 .

  6. Intentional burns in Nepal: a comparative study.

    Science.gov (United States)

    Lama, Bir Bahadur; Duke, Janine M; Sharma, Narayan Prasad; Thapa, Buland; Dahal, Peeyush; Bariya, Nara Devi; Marston, Wendy; Wallace, Hilary J

    2015-09-01

    Intentional burns injuries are associated with high mortality rates, and for survivors, high levels of physical and psychological morbidity. This study provides a comprehensive assessment of intentional burn admissions to the adult Burns Unit at Bir Hospital, Kathmandu, Nepal, during the period 2002-2013. A secondary data analysis of de-identified data of patients hospitalized at Bir Hospital, Kathmandu, with a burn during the period of 1 January 2002 to 31 August 2013. Socio-demographic, injury and psychosocial factors of patients with intentional and unintentional burns are described and compared. Chi-square tests, Fisher's exact test and Wilcoxon rank sum tests were used to determine statistical significance. There were a total of 1148 burn admissions of which 329 (29%) were for intentional burn, 293 (26%) were self-inflicted and 36 (3%) were due to assault. Mortality rates for intentional burns were approximately three times those for unintentional burns (60 vs. 22%). When compared to unintentional burns, patients with intentional burns were more likely to be female (79 vs. 48%), married (84 vs. 67%), younger (25 vs. 30 years), have more extensive burns (total body surface area, %: 55 vs. 25) and higher mortality (60 vs. 22%). Intentional burns were more likely to occur at home (95 vs. 67%), be caused by fire (96 vs. 77%), and kerosene was the most common accelerant (91 vs. 31%). A primary psychosocial risk factor was identified in the majority of intentional burn cases, with 60% experiencing adjustment problems/interpersonal conflict and 32% with evidence of a pre-existing psychological condition. A record of alcohol/substance abuse related to the patient or other was associated with a greater proportion of intentional burns when compared with unintentional burns (17 vs. 4%). The majority of intentional burn patients were female. Almost all intentional burns occurred in the home and were caused by fire, with kerosene the most common accelerant used. Underlying

  7. A theoretical and experimental study on geometric nonlinearity of initially curved cantilever beams

    Directory of Open Access Journals (Sweden)

    Sushanta Ghuku

    2016-03-01

    Full Text Available This paper presents a theoretical and experimental study on large deflection behavior of initially curved cantilever beams subjected to various types of loadings. The physical system as a straight cantilever beam subjected to a tip concentrated load is considered in this study. Nonlinear differential equations are obtained for large deflection analysis of such a straight cantilever beam, and this problem is known to involve geometrical nonlinearity. The equations are solved numerically with the help of MATLAB® computational platform to get deflection profiles of the concerned problem. These results are imposed subsequently on the center line of an initially curved beam to get theoretical load-deflection behavior of curved beam problems. To verify the theoretical model, experiment is carried out with the master leaf of a leaf spring bundle by modeling it as an initially curved cantilever beam. The effects of initial clamping and geometry variations in the eye-region are observed from experimental investigation which is commonly neglected in the mathematical formulation. Comparisons of the theoretical results with the experimental results are quite good, but the avenues for further improvement are also reported. The proposed approach is further extended to study large deflection behavior of an initially curved cantilever beam subjected to distributed and combined load. These results are successfully validated with existing results for straight beams and some new results are furnished for initially curved cantilever beams.

  8. Theoretical Studies on Structures, Properties and Dominant Debromination Pathways for Selected Polybrominated Diphenyl Ethers

    Directory of Open Access Journals (Sweden)

    Lingyun Li

    2016-06-01

    Full Text Available The B3LYP/6-311+G(d-SDD method, which considers the relativistic effect of bromine, was adopted for the calculations of the selected polybrominated diphenyl ethers (PBDEs in the present study, in which the B3LYP/6-311+G(d method was also applied. The calculated values and experimental data for structural parameters of the selected PBDEs were compared to find the suitable theoretical methods for their structural optimization. The results show that the B3LYP/6-311+G(d method can give the better results (with the root mean square errors (RMSEs of 0.0268 for the C–Br bond and 0.0161 for the C–O bond than the B3LYP/6-311+G(d-SDD method. Then, the B3LYP/6-311+G(d method was applied to predict the structures for the other selected PBDEs (both neutral and anionic species. The lowest unoccupied molecular orbital (LUMO and the electron affinity are of a close relationship. The electron affinities (vertical electron affinity and adiabatic electron affinity were discussed to study their electron capture abilities. To better estimate the conversion of configuration for PBDEs, the configuration transition states for BDE-5, BDE-22 and BDE-47 were calculated at the B3LYP/ 6-311+G(d level in both gas phase and solution. The possible debromination pathway for BDE-22 were also studied, which have bromine substituents on two phenyl rings and the bromine on meta-position prefers to depart from the phenyl ring. The reaction profile of the electron-induced reductive debromination for BDE-22 were also shown in order to study its degradation mechanism.

  9. The BEST study - a prospective study to compare business class ...

    African Journals Online (AJOL)

    ... a prospective study to compare business class versus economy class air travel as a cause of thrombosis. ... Patients/methods. ... Logistical regression analysis was used to determine the risk factors related to abnormally high D-dimer levels.

  10. Theoretical Study of the Radical Scavenging Activity of Shikonin and Its Derivatives%Theoretical Study of the Radical Scavenging Activity of Shikonin and Its Derivatives

    Institute of Scientific and Technical Information of China (English)

    靳瑞岌; 李杰

    2012-01-01

    A series of shikonin derivatives have been designed and their radical scavenging activity has been characterized by the B3LYP/6-31 +G(d) approach. The hydrogen bond properties of the studied structures were investigated using the atoms in molecules (AIM) theory. The calculated results reveal that the hydrogen bond is important for good scavenging activity. The introduction of electron-drawing (electron-donating) groups increases (decreases) the scavenging activities of radical and radical cations of shikonin derivatives. Shikonin derivatives appear to be good candidates for the single-electron-transfer mechanism, particularly for -N(CH3)2 derivative. Taking this system as an example, we present an efficient method for the investigation of radical scavenging activity from theoretical point of view. With the current work, we hope to highlight the radical scavenging activity of hydroxynaphtho- quinones derivatives and stimulate the interest for further studies and exploitation in pharmaceutical industry.

  11. COMPARATIVE STUDY ON ACCOUNTING AND FISCAL AMORTIZATION

    Directory of Open Access Journals (Sweden)

    MARIANA GURAU

    2012-05-01

    Full Text Available Placed in the international trend, Romanian accounting had experienced various changes, especially as regards of progress on disconnection between accounting and fiscality. In the present, fiscal rules should not have any role in accounting decisions, because accounting rules are applied to produce accounting information that is useful in making decisions and to provide a "true and fair view" upon financial reality of the entity. However, the barrier in the habit of accounting to thinking for fiscal point of view all economic transactions remains insurmountable, yet. Starting from this perspective on disconnection between accounting and fiscality would mean that amortization recorded in the accounting, as a result of management policy, to be different from fiscality amortization, to calculate income tax. Although formally accepted, disconnect between accounting and fiscality continues to meet many difficulties. In this sense, it is usual in practice to use the same method of amortization for accounting purposes and for fiscal purposes to prevent complications of double track amortization and prevent wandering in the rules in this field. Accounting rule is deliberately eluded in favor of the fiscal rules. This is the reason we proposed to make in this paper a comparative study between norms and rules on accounting and fiscal amortization, paper in which we intend to show the benefits of applying accounting and fiscal rules separately.

  12. Comparative study of selected parallel tempering methods

    Science.gov (United States)

    Malakis, A.; Papakonstantinou, T.

    2013-07-01

    We review several parallel tempering schemes and examine their main ingredients for accuracy and efficiency. The present study covers two selection methods of temperatures and several choices for the exchange of replicas, including a recent novel all-pair exchange method. We compare the resulting schemes and measure specific heat errors and efficiency using the two-dimensional (2D) Ising model. Our tests suggest that an earlier proposal for using numbers of local moves related to the canonical correlation times is one of the key ingredients for increasing efficiency, and protocols using cluster algorithms are found to be very effective. Some of the protocols are also tested for efficiency and ground state production in 3D spin-glass models where we find that a simple nearest-neighbor approach using a local n-fold-way algorithm is the most effective. Finally, we present evidence that the asymptotic limits of the ground state energy for the isotropic case and for an anisotropic case of the 3D spin-glass model are very close and may even coincide.

  13. Theoretical and experimental study of aparisthman: A natural product with anti-ulcer activity

    Science.gov (United States)

    Brasil, D. S. B.; Moreira, R. Y. O.; Müller, A. H.; Alves, C. N.

    Aparisthman is a furan diterpenoid with a clerodane skeleton isolated from Aparisthmium cordatum (Juss.) Bail. (Euphorbiaceae). This natural product presents significant anti-ulcer activity to the level of cimetidine (Tagamet®), a compound used for the treatment of ulcers provoked by stress. The structure of X-ray diffraction of the aparisthman was compared with theoretical calculations and the results showed that the theory is in accordance with the experimental data. The infrared (IR) and nuclear magnetic resonance (NMR) spectra also were obtained and compared with theoretical calculations. The B3LYP theory level, with the 6-31G(d,p) basis set, leads the value to the IR absorption close to the value experimentally observed. NMR theoretical obtained with HF/6-311+G(2d,p) shows little deviation of experimental results. Calculations of molecular electrostatic potential and stabilization energies suggest that the protonation of aparisthman will be able to occur on carbonyl oxygen atom (O4).

  14. Theoretical spectroscopic study of the conjugate microcystin-LR-europium cryptate

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Julio G.; Dutra, Jose Diogo L.; Costa Junior, Nivan B. da; Freire, Ricardo O., E-mail: rfreire@ufs.br [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Departamento de Quimica; Alves Junior, Severino; Sa, Gilberto F. de [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Departamento de Quimica Fundamental

    2013-02-15

    In this work, theoretical tools were used to study spectroscopic properties of the conjugate microcystin-LR-europium cryptate. The Sparkle/AM1 model was applied to predict the geometry of the system and the INDO/S-CIS model was used to calculate the excited state energies. Based on the Judd-Ofelt theory, the intensity parameters were predicted and a theoretical model based on the theory of the 4f-4f transitions was applied to calculate energy transfer and backtransfer rates, radiative and non-radiative decay rates, quantum efficiency and quantum yield. A detailed study of the luminescent properties of the conjugate Microcystin-LR-europium cryptate was carried out. The results show that the theoretical quantum yield of luminescence of 23% is in good agreement with the experimental value published. This fact suggests that this theoretical protocol can be used to design new systems in order to improve their luminescence properties. The results suggest that this luminescent system may be a good conjugate for using in assay ELISA for detection by luminescence of the Microcystin-LR in water. (author)

  15. Studying Scale-Up and Spread as Social Practice: Theoretical Introduction and Empirical Case Study.

    Science.gov (United States)

    Shaw, James; Shaw, Sara; Wherton, Joseph; Hughes, Gemma; Greenhalgh, Trisha

    2017-07-07

    Health and care technologies often succeed on a small scale but fail to achieve widespread use (scale-up) or become routine practice in other settings (spread). One reason for this is under-theorization of the process of scale-up and spread, for which a potentially fruitful theoretical approach is to consider the adoption and use of technologies as social practices. This study aimed to use an in-depth case study of assisted living to explore the feasibility and usefulness of a social practice approach to explaining the scale-up of an assisted-living technology across a local system of health and social care. This was an individual case study of the implementation of a Global Positioning System (GPS) "geo-fence" for a person living with dementia, nested in a much wider program of ethnographic research and organizational case study of technology implementation across health and social care (Studies in Co-creating Assisted Living Solutions [SCALS] in the United Kingdom). A layered sociological analysis included micro-level data on the index case, meso-level data on the organization, and macro-level data on the wider social, technological, economic, and political context. Data (interviews, ethnographic notes, and documents) were analyzed and synthesized using structuration theory. A social practice lens enabled the uptake of the GPS technology to be studied in the context of what human actors found salient, meaningful, ethical, legal, materially possible, and professionally or culturally appropriate in particular social situations. Data extracts were used to illustrate three exemplar findings. First, professional practice is (and probably always will be) oriented not to "implementing technologies" but to providing excellent, ethical care to sick and vulnerable individuals. Second, in order to "work," health and care technologies rely heavily on human relationships and situated knowledge. Third, such technologies do not just need to be adopted by individuals; they need

  16. Theoretical study of Kondo effect and related transport properties in topological insulator systems

    Science.gov (United States)

    Xin, Xianhao

    This thesis presents theoretical studies of the Kondo effect and related transport properties in topological insulator systems. The thesis mainly covers two topics: the Kondo effect on the surface of a bulk topological insulator material and the Kondo effect in a topological insulator quantum dot. Other relevant background knowledge and theoretical techniques for the transport calculations are also discussed in the thesis. For the first topic, we investigate the role of magnetic impurities in the transport properties of a three-dimensional topological insulator's surface states. First, we combine the second-order perturbation theory and the Boltzmann transport equation to calculate the magnetically induced resistivity in a topological insulator. Our result shows a non-perturbative behavior when conduction electrons and magnetic impurities' spins are antiferromagnetically coupled. The surface resistivity is found to display an oscillatory rather than isotropic behavior compared to the conventional Kondo effect. Both the variational method and renormalization group (RG) analysis are employed to compute the Kondo temperature, through which the non-perturbative behavior is confirmed. We further study the RG flows and demonstrate that the RG trajectories eventually flow into a strong coupling regime if the coupling is antiferromagnetic. This work is motivated by the recent transport experiments, in which surface currents were detected in topological insulators. The calculation is shown to be qualitatively consistent with the low temperature dip observed in the experimental R - T curve, and it might be one of the possible origins of the dip. For the second main topic, we investigate theoretically the nonequilibrium transport properties of a topological insulator quantum dot (TIQD) in the Coulomb blockade and Kondo regime. An Anderson impurity model is applied to a TIQD system coupled to two external leads, and we show that the model realizes the spin-orbital Kondo effect

  17. A Comparative Study of Three Vibration Based Damage Assessment Techniques

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Rytter, A.

    Three different vibration based damage assessment techniques have been compared. One of the techniques uses the ratios between changes in experimentally and theoretically estimated natural frequencies, respectively, to locate a damage. The second technique relies on updating of an FEM based...

  18. Theoretical Study of the Effects of Di-Muonic Molecules on Muon-Catalyzed Fusion

    Science.gov (United States)

    2012-03-01

    MOLECULES ON MUON -CATALYZED FUSION DISSERTATION Eugene V. Sheely, Lieutenant Colonel, USA DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY...THEORETICAL STUDY OF THE EFFECTS OF DI-MUONIC MOLECULES ON MUON -CATALYZED FUSION DISSERTATION Presented to the Faculty...potential of enhancing the muon -catalyzed fusion reaction rate. In order to study these di-muonic molecules a method of non-adiabatic quantum mechanics

  19. Theoretical and experimental studies of space-related plasma wave propagation and resonance phenomena

    Science.gov (United States)

    Crawford, F. W.

    1975-01-01

    A ten year summary was given of university research on the nature and characteristics of space related plasma resonance phenomena, whistler propagation in laboratory plasmas, and theoretical and experimental studies of plasma wave propagation. Data are also given on long delayed echoes, low frequency instabilities, ionospheric heating, and backscatter, and pulse propagation. A list is included of all conference papers, publications, and reports resulting from the study.

  20. Spectroscopy and Photochemistry of Europium atoms in low temperature solids - an experimental and theoretical study

    OpenAIRE

    Byrne, Owen

    2010-01-01

    This thesis presents an experimental and theoretical study of the luminescence, reactivity and ionisation of atomic europium isolated in cryogenic thin films of rare gases argon, krypton and xenon. Many studies are available concerning the spectroscopy of matrix-isolated main group metal atoms, however, the lanthanide series remains relatively undocumented. A thorough investigation of matrix-isolated europium is performed in this thesis in an effort to develop the spectroscopy ...

  1. A theoretical justification for the study of skin sensitivity in patients with bell's palsy

    OpenAIRE

    Cárdenas Palacios, Carlos Andrés; Universidad de la Sabana-Bogotá,Colombia

    2015-01-01

    The purpose of this review is to highlight the importance of conducting studies to estimate the level of association between measures of skin sensitivity, facial region, facial paralysis level, and time of evolution, in patients with Bells palsy; the above stems from the theoretical review of various studies that have found differences in measures of pressure threshold, two-point discrimination and appreciation of the vibration between different facial regions, both in patients with this kind...

  2. A Theoretical Study of the Two-Dimensional Point Focusing by Two Multilayer Laue Lenses.

    Energy Technology Data Exchange (ETDEWEB)

    Yan,H.; Maser, J.; Kang, H.C.; Macrader, A.; Stephenson, B.

    2008-08-10

    Hard x-ray point focusing by two crossed multilayer Laue lenses is studied using a full-wave modeling approach. This study shows that for a small numerical aperture, the two consecutive diffraction processes can be decoupled into two independent ones in respective directions. Using this theoretical tool, we investigated adverse effects of various misalignments on the 2D focus profile and discussed the tolerance to them. We also derived simple expressions that described the required alignment accuracy.

  3. A comparative study of Raman enhancement in capillaries

    Science.gov (United States)

    Eftekhari, Fatemeh; Irizar, Juan; Hulbert, Laila; Helmy, Amr S.

    2011-06-01

    This work reports on the comparative studies of Raman enhancement in liquid core waveguides (LCWs). The theoretical considerations that describe Raman enhancement in LCWs is adapted to analyze and compare the performance of hollow core photonic crystal fibers (HCPCFs) to conventional Teflon capillary tubes. The optical losses in both platforms are measured and used to predict their performance for different lengths. The results show that for an optimal waveguide length, two orders of magnitude enhancement in the Raman signal can be achieved for aqueous solutions using HCPCFs. This length, however, cannot be achieved using normal capillary effects. By integrating the interface of the fluidic pump and the HCPCF into a microfluidic chip, we are able to control fluid transport and fill longer lengths of HCPCFs regardless of the viscosity of the sample. The long-term stability and reproducibility of Raman spectra attained through this platform are demonstrated for naphthalenethiol, which is a well-studied organic compound. Using the HCPCF platform, the detection limit of normal Raman scattering in the range of micro-molars has been achieved. In addition to the higher signal-to-noise ratio of the Raman signal from the HCPCF-platform, more Raman modes of naphthalenethiol are revealed using this platform.

  4. A Comparative Study of Principals' Administrative Behaviour.

    Science.gov (United States)

    Chung, Kyung Ae

    1989-01-01

    Compared are the managerial behaviors and beliefs of Korean and American secondary school principals. Generalizations are proposed in the areas of work hours, work pace, communication skills, organizational style, instructional leadership, and other managerial behaviors. (16 references) (SI)

  5. Comparative study of environmental impact assessment methods ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-07-20

    Jul 20, 2009 ... Then both approaches required be comparing and contrasting. Among these methods .... should include political powers (factors related to the poli- cy test) and .... mental system and predict the component behavior. Using the ...

  6. THEORETICAL AND EXPERIMENTAL STUDIES ON FRACTURE PLANE CONTROL BLAST WITH NOTCHED BOREHOLES

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The results of theoretical studies and field tests on fracture plane control blast with notched boreholes have been introduced. In these studies, the single symmetrical notched borehole was simplified to a pressurized hole with two symmetrical cracks under the state of plane strain. In analyzing the growth and termination of the notch, only quasi-static pressure was considered. In the mean time, the rock to be blasted was considered to be isotropic. Based on the principles of fracture mechanics, the stress components near the tip of the notch were calculated, and the criteria for growth and termination of the notch were established. The growth direction of the notch was also predicted on the basis of strain energy density factor. An approach for estimating the amount of explosive for each hole and the spacing of holes was suggested. Furthermore, field tests were conducted to check the results from the theoretical studies.

  7. Dimerization of green sensitizing cyanines in solution. A spectroscopic and theoretical study of the bonding nature

    Science.gov (United States)

    Baraldi, I.; Caselli, M.; Momicchioli, F.; Ponterini, G.; Vanossi, D.

    2002-01-01

    The bonding nature in cyanine-dye aggregates has been investigated by studying dimerization in solution of 3,3 '-disulfopropyl-4,5,4 ',5 '-dibenzo-9-ethyloxacarbocyanine (D) and three other oxacarbocyanine analogues (E, F, G) used as photographic sensitizers in the green spectral region. Quantitative information on the monomer-dimer equilibrium of dye D in different solvents and of its analogues (E, F, G) in water was obtained by measurement of the absorption spectrum as a function of dye concentration and of temperature. Dimerization was found to be generally driven by enthalpic factors traceable to strong attractive van der Waals interactions between the two large and highly polarizable dye molecules. Entropic contributions to ΔG0 usually favour dissociation but are smaller than the enthalpic ones. The visible absorption spectrum of the dimer consists in a classic two-branched exciton band with a marked splitting ( 1600 cm-1 in water). The experimental observations were the subject of a theoretical study including classical molecular dynamics (MD) and Monte Carlo (MC) calculations of the dimer structure and comparative analysis of monomer and dimer spectra by the CS INDO CI method. Computer simulations led to three similar H-type structures, the most stable of which is characterized by a distance of 4.7 Å between the planes of the chromophores and an endo-endo configuration of the sulfopropyl substituents. The calculated dimer spectrum was clearly interpreted in terms of exciton model but a quantitative agreement with the two-maximum exciton band could be obtained only by assuming substantial deviation of the long molecular axes from parallelism. On the basis of normal coordinate calculations it is suggested that such configurations may occur with a high probability in virtue of twisting vibrational motions of extremely low frequency.

  8. Bits of Baggage and Wanderers' Tales: Towards the Construction of a New Theoretical Framework for Comparative Adult Education.

    Science.gov (United States)

    Arthur, Lore

    2001-01-01

    Reviews the history of comparative adult education and the multiple pathways afforded by postmodernism and poststructuralism. Concludes that comparative adult education should avoid bipolar constructs and include exploration of the following: analysis, forces, power, genre, communication, interculturality, knowledge construction, evaluation, and…

  9. SKIN STAPLED OR SUTURED: A COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    Veerendra Kumar

    2015-01-01

    Full Text Available BACKGROUND: The choice of wound closure after a surgical procedure has been a surgeon’s dilemma . The concerns have been as to how fast , uneventful , less painful , with minimal complications and comfortable will the patient’s recovery be. A well - known technology is surgical staples which are easier to use , less time consuming and a needle free method o f wound closure. OBJECTIVE: To compare skin staples with non - absorbable skin suture for skin closure in surgical laparotomy procedures for the following character : wound infection , dehiscence , cosmesis and postoperative pain . METHODS: This is a comparative study conducted on 100 patients divided in two groups randomly at Bapuji Hospital for cases undergoing surgical laparotomy procedures. Skin closure was done with 2 - 0 polyamide skin sutures in one group and skin closure was achieved with skin staples in th e other group. The outcome of wound was assessed on 3rd , 5th and 7th postoperative days using ASEPSIS score. Wound cosmesis was assessed on the 7th postoperative day and followed up at 1st month and 3rd month , using modified Hollander cosmesis scale. Postoperative pain was assessed using the visual analogue scale on the 1st , 3rd and 7th postoperative days. RESULTS : The mean wound ASPESIS scores on day 3 for skin staples and sutured group was 0.28 and 0.36 (p=0.7 respectively. The score on day 5 for staples and sutured group was 0.12 and 0.28 (p=0.4 respectively. The results in both the groups were the same , 0.08 on day 7(p=0. Wound cosmesis mean score assessment on day 7 for skin staples suturing group was 5.84 and 5.68 respectively (p=0.3. The mean score for cosmesis assessment at 1 month , and 3 rd month for skin staples and suturing group was 5.92 and 5.68 (p=0.1 and was 6.00 and 5.92 (p=0.36 respectively which was not satistically significant . The visual analogue scale score for postopera tive pain on 1st day , 3 rd and 7 th day for skin staples and suturing group 54

  10. Theoretical Study of Wave Breaking for Nonlinear Water Waves Propagating on a Sloping Bottom

    Science.gov (United States)

    Chen, Y. Y.; Hsu, H. C.; Li, M. S.

    2012-04-01

    In this paper, a third-order asymptotic solution in a Lagrangian framework describing nonlinear water wave propagation on the surface of a uniform sloping bottom is presented. A two-parameter perturbation method is used to develop a new mathematical derivation. The particle trajectories, wave pressure and Lagrangian velocity potential are obtained as a function of the nonlinear wave steepness and the bottom slope perturbed to third order. This theoretical solution in Lagrangian form satisfies state of the normal pressure at the free surface. The condition of the conservation of mass flux is examined in detail for the first time. The two important properties in Lagrangian coordinates, Lagrangian wave frequency and Lagrangian mean level, are included in the third-order solution. The solution can also be used to estimate the mean return current for waves progressing over the sloping bottom. The Lagrangian solution untangle the description of the features of wave shoaling in the direction of wave propagation from deep to shallow water, as well as the process of successive deformation of a wave profile and water particle trajectories leading to wave breaking. A series of experiment was conducted to validate the obtained theoretical solution. The proposed solution will be used to determine the wave shoaling and breaking process and the comparisons between the experimental and theoretical results are excellent. For example, the variations of phase velocity on sloping bottom are obtained by 7 set of two close wave gauges and the theoretical result could accurately predict the measured phase velocity. The theoretical wave breaking index can be derived by use of the kinematic stability parameter (K.P.S). The comparisons between the theory, experiment (present study, Iwagali et al.(1974), Deo et al.(2003) and Tsai et al.(2005)) and empirical formula of Goda (2004) for the breaking index(u/C) versus the relative water depth(d/L) under two different bottom slopes shows that the

  11. Institutions and national development in Latin America: a comparative study.

    Science.gov (United States)

    Portes, Alejandro; Smith, Lori D

    We review the theoretical and empirical literatures on the role of institutions on national development as a prelude to present a more rigorous and measurable definition of the concept and a methodology to study this relationship at the national and subnational levels. The existing research literature features conflicting definitions of the concept of "institutions" and empirical tests based mostly on reputational indices, with countries as units of analysis. The present study's methodology is based on a set of five strategic organizations studied comparatively in five Latin American countries. These include key federal agencies, public administrative organizations, and stock exchanges. Systematic analysis of results show a pattern of differences between economically-oriented institutions and those entrusted with providing basic services to the general population. Consistent differences in institutional quality also emerge across countries, despite similar levels of economic development. Using the algebraic methods developed by Ragin, we test six hypotheses about factors determining the developmental character of particular institutions. Implications of results for theory and for methodological practices of future studies in this field are discussed.

  12. Electronic properties of diphenyl-s-tetrazine and some related oligomers. An spectroscopic and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Moral, Monica; Garcia, Gregorio [Departamento de Quimica Fisica y Analitica, Facultad de Ciencias Experimentales, Universidad de Jaen, Campus las Lagunillas, E23071 Jaen (Spain); Penas, Antonio [Departamento de Quimica Inorganica y Organica, Facultad de Ciencias Experimentales, Universidad de Jaen, Campus las Lagunillas, E23071 Jaen (Spain); Garzon, Andres; Granadino-Roldan, Jose M. [Departamento de Quimica Fisica y Analitica, Facultad de Ciencias Experimentales, Universidad de Jaen, Campus las Lagunillas, E23071 Jaen (Spain); Melguizo, Manuel [Departamento de Quimica Inorganica y Organica, Facultad de Ciencias Experimentales, Universidad de Jaen, Campus las Lagunillas, E23071 Jaen (Spain); Fernandez-Gomez, Manuel, E-mail: mfg@ujaen.es [Departamento de Quimica Fisica y Analitica, Facultad de Ciencias Experimentales, Universidad de Jaen, Campus las Lagunillas, E23071 Jaen (Spain)

    2012-10-26

    Highlights: Black-Right-Pointing-Pointer We study properties of Ph{sub 2}Tz and (PhTz){sub n}Ph as candidates for organic electronics. Black-Right-Pointing-Pointer The synthesis of Ph{sub 2}Tz was performed through a modified Pinner-type reaction. Black-Right-Pointing-Pointer IR/Raman spectra allowed to conclude that Ph{sub 2}Tz is nearly planar in liquid phase. Black-Right-Pointing-Pointer Electronic structure was studied by UV-Vis/TD-DFT methods in different solvents. Black-Right-Pointing-Pointer Bandgap, E{sub LUMO}, electron mobility predict some n-type character for limit polymer. -- Abstract: This work presents a theoretical and spectroscopic study on the electronic and structural properties of the diphenyl-s-tetrazine molecule (Ph{sub 2}Tz) and some oligomeric derivatives. Ph{sub 2}Tz was synthesized through a variation of Pinner-type reaction which uses N-acetylcysteine as catalyst. Insight into the structure and electronic properties of the title compound was obtained through IR, Raman, UV-Vis spectra in different solvents, and theoretical calculations. Theoretical studies have been extended to different n-mers derivatives up to an ideal molecular wire through the oligomeric approximation, predicting this way electronic properties such as LUMO energy levels, electron affinity and reorganization energy in order to assess their possible applications in molecular electronics.

  13. Theoretical study and calculation of the response of a fast neutron dosemeter based on track detection

    Energy Technology Data Exchange (ETDEWEB)

    Decossas, J.L.; Vareille, J.C.; Moliton, J.P.; Teyssier, J.L. (Limoges Univ., 87 (France). Lab. d' Electronique des Polymeres sous Faisceaux Ioniques)

    1983-01-01

    A fast neutron dosemeter is generally composed of a radiator in which n-p elastic scattering occurs and a detector which registers protons. A theoretical study, and the calculation (FORTRAN program) of the response of such a dosemeter is presented involving two steps: 1) The proton flux emerging from a thick radiator on which monoenergetic neutrons are normally incident is studied. This is characterised by its energy spectrum depending on the neutron energy and on the radiator thickness. 2) Proton detection being achieved with a solid state nuclear track detector whose performance is known, the number of registered tracks are calculated. The dosemeter sensitivity (tracks cm/sup -2/. Sv/sup -1/) is deduced. Then, the calculations show that it is possible to optimise the radiator thickness to obtain the smallest variation in sensitivity with neutron energy. The theoretical results are in good agreement with the experimental ones found in the literature.

  14. Theoretical & Experimental Studies on Vibration & Damping of Fibre-Reinforced Cantilever Laminates.

    Directory of Open Access Journals (Sweden)

    M. Ganapathi

    2000-07-01

    Full Text Available In this paper, vibration and damping analyses  of glass fibre-reinforced laminated composite cantilever beams and plates are studied using C1 finite element using shear deformation theory and alsothrough experiments. The formulation in the theoretical model includes in-plane and rotary inertiaterms. The governing equations for the complex eigenvalue problem based on complex elastic moduliare formulated. The solutions are obtained using QR algorithm. Parametric study is carried out tohighlight; the effects of lay-up and ply-angle of the laminates. A limited number of experimentalinvestigafions on cantilever laminates are conducted for obtaining the natural frequenciqs, dampingfactor and frequency responses. The comparison between the theoretical and the experimfntal resultsshows good agreement.

  15. Theoretical study of a dual harmonic system and its application to the CSNS/RCS

    Science.gov (United States)

    Yuan, Yao-Shuo; Wang, Na; Xu, Shou-Yan; Yuan, Yue; Wang, Sheng

    2015-12-01

    Dual harmonic systems have been widely used in high intensity proton synchrotrons to suppress the space charge effect, as well as reduce the beam loss. To investigate the longitudinal beam dynamics in a dual rf system, the potential well, the sub-buckets in the bunch and the multi-solutions of the phase equation are studied theoretically in this paper. Based on these theoretical studies, optimization of bunching factor and rf voltage waveform are made for the dual harmonic rf system in the upgrade phase of the China Spallation Neutron Source Rapid Cycling Synchrotron (CSNS/RCS). In the optimization process, the simulation with space charge effect is done using a newly developed code, C-SCSIM. Supported by National Natural Science Foundation of China (11175193)

  16. Conformational equilibrium of phenylacetic acid and its halogenated analogues through theoretical studies, NMR and IR spectroscopy

    Science.gov (United States)

    Levandowski, Mariana N.; Rozada, Thiago C.; Melo, Ulisses Z.; Basso, Ernani A.; Fiorin, Barbara C.

    2017-03-01

    This paper presents a study on the conformational preferences of phenylacetic acid (PA) and its halogenated analogues (FPA, CPA, BPA). To clarify the effects that rule these molecules' behaviour, theoretical calculations were used, for both the isolated phase and solution, combined with nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. Most conformations of phenylacetic acid and its halogenated derivatives are stabilized through the hyperconjugative effect, which rules the conformational preference. NMR analyses showed that even with the variation in medium polarity, there was no significant change in the conformation population. Infrared spectroscopy showed similar results for all compounds under study. In most spectra, two bands were found through the carbonyl deconvolution, which is in accordance with the theoretical data. It was possible to prove that variation in the nature of the substituent in the ortho position had no significant influence on the conformational equilibrium.

  17. New theoretical methods for studies on electrons and positrons scattering involving multichannel processes

    CERN Document Server

    Lara, O

    1995-01-01

    continued fractions are now in progress. It is well known that multichannel effects strongly influence the low-energy electron scattering by atoms and molecules. Nevertheless, the inclusion of such effects on the calculations of scattering cross sections remains a considerable task for the area researches due to the complexity of the problem. In the present study we aim to develop a new theoretical method which can be efficiently applied to the multichannel scattering studies. Two new theoretical formalisms namely the Multichannel sup - C-Functional Method have been proposed. Both methods were developed on the base of well-known distorted-wave method combined with Schwinger variational principle. In addition, an integrative method proposed by Horacek and Sasakawa in 1983, the method of continued fractions is adapted by the first time to multichannel scatterings. Numerical test of these three methods were carried out through applications to solve the multichannel scattering problems involving the interaction o...

  18. The guanidine and maleic acid (1:1) complex. The additional theoretical and experimental studies

    Science.gov (United States)

    Drozd, Marek; Dudzic, Damian

    2012-04-01

    On the basis of experimental literature data the theoretical studies for guanidinium and maleic acid complex with using DFT method are performed. In these studies the experimental X-ray data for two different forms of investigated crystal were used. During the geometry optimization process one equilibrium structure was found, only. According to this result the infrared spectrum for one theoretical molecule was calculated. On the basis of potential energy distribution (PED) analysis the clear-cut assignments of observed bands were performed. For the calculated molecule with energy minimum the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were obtained and graphically illustrated. The energy difference (GAP) between HOMO and LUMO was analyzed. Additionally, the nonlinear properties of this molecule were calculated. The α and β (first and second order) hyperpolarizability values are obtained. On the basis of these results the title crystal was classified as new second order NLO generator.

  19. The Teaching of Anthropology: A Comparative Study.

    Science.gov (United States)

    Lombard, Jacques

    1984-01-01

    College-level anthropology teaching in various countries, including Belgium, France, Germany, the Netherlands, Portugal, South Africa, the United Kingdom, and Yugoslavia, is compared. Terminology is examined and historical background is provided. Also discussed are educational crises, the organization of teaching, and teaching methods. (RM)

  20. Theoretical and Computational Studies of Rare Earth Substitutes: A Test-bed for Accelerated Materials Development

    Energy Technology Data Exchange (ETDEWEB)

    Benedict, Lorin X. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-26

    Hard permanent magnets in wide use typically involve expensive Rare Earth elements. In this effort, we investigated candidate permanent magnet materials which contain no Rare Earths, while simultaneously exploring improvements in theoretical methodology which enable the better prediction of magnetic properties relevant for the future design and optimization of permanent magnets. This included a detailed study of magnetocrystalline anisotropy energies, and the use of advanced simulation tools to better describe magnetic properties at elevated temperatures.

  1. Theoretical and Experimental Study of Hopf Bifurcation and Limit Cycles of Railway Vehicle Hunting

    Institute of Scientific and Technical Information of China (English)

    Zeng Jing; Zhang Weihua; Shen Zhiyun

    1996-01-01

    The nonlinear hunting stability of railway vehicles is studied theoretically and experimentally in this paper. The Hopf bifurcation point is determined through calculating the eigenvalues of the system linearization equations incorporating with the golden cut method. The bifurcated limit cycles are computed by use of the shooting method to solve the boundary value problem of the system differential equations. Experimental validation to the numerical results is carricd out by utilizing the full scale roller test rig.

  2. Theoretical studies on electronic structure and x-ray spectroscopies of 2D materials

    OpenAIRE

    2016-01-01

    Extraordinary chemical and physical properties have been discovered from the studies of two-dimensional (2D) materials, ever since the successful exfoliation of graphene, the first 2D material. Theoretical investigations of electronic structure and spectroscopies of these materials play a fundamental role in deep understanding the various properties. In particular, the band structure and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy can provide critical information near the ...

  3. Design factors for “linear” ball valve: theoretical and experimental studies

    OpenAIRE

    Thananchai Leephakpreeda

    2005-01-01

    Generic non-linear flow characteristics of the conventional ball valve limit the applications of flow modulation in fluid processes. This work presents the flow characteristics of fluid flowing through the conventional and modified ball valves for feasibility of a “linear” ball valve. Theoretical studies are discussed for determining explicit and implicit factors on the valve coefficient, which modulates the flow rate of fluid when the ball valve is operated in flow control processes. In expe...

  4. Theoretical study of quasi-phase-matching fourth harmonic generation in periodically poled lithium tantalate

    Institute of Scientific and Technical Information of China (English)

    Wei Xie(谢威); Xianfeng Chen(陈险峰); Like He(何利科); Yuping Chen(陈玉萍); Yuxing Xia(夏宇兴)

    2004-01-01

    The direct fourth harmonic generation (FHG) is theoretically demonstrated based on quasi-phase-matching (QPM) configuration in periodically poled lithium tantalate (PPLT). The wavelength dependence of the period of FHG QPM gratings is calculated. Bandwidths of fundamental wavelength, temperature, and incident angle are also studied. A very wide bandwidth, as large as 119.5 nm, of fundamental wavelength near 3699 nm is found with the QPM period of 9.442 μm and the crystal length of 1 cm.

  5. Antennas for VHF/UHF personal radio: A theoretical and experimental study of characteristics and performance

    DEFF Research Database (Denmark)

    Andersen, Jørgen Bach; Hansen, Flemming

    1977-01-01

    , and it is shown how antenna impedance, gain, and radiation patterns can be calculated taking the presence of the body into account. For very short antennas the results indicate that radiation from the body may dominate over the radiation contributed by the antenna itself, and that the presence of the body can...... increase the antenna efficiency considerably, indicating that even very short antennas may provide acceptable radiation efficiencies. The results of the theoretical work are supported by measurements on practical antennas. Quarter-wave and short antennas of the helical type are compared with respect...

  6. A theoretical study of electronic excited states of photosynthetic reaction center in Rhodopseudomonas viridis

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The electronic singlet vertical excited states of photosynthetic reaction center (PSRC) in Rhodopseudomonas (Rps.) viridis were investigated by ZINDO and INDO/S methods. The effects of the interactions of pigment-pigment and pigment-protein on the electronic excitations were examined. The calculation results showed that the interactions of pigment-pigment and pigment-protein play an important role in reasonably assigning the experimental absorption and circular dichroism (CD) spectra of PSRC in Rps. virids. By comparing the theoretically computed excited states with the experimental absorption and CD spectra, satisfactory assignments of the experimental spectroscopic peaks were achieved.

  7. A structural and theoretical study of the alkylammonium nitrates forefather: Liquid methylammonium nitrate

    Science.gov (United States)

    Gontrani, Lorenzo; Caminiti, Ruggero; Salma, Umme; Campetella, Marco

    2017-09-01

    We present here a structural and vibrational analysis of melted methylammonium nitrate, the simplest compound of the family of alkylammonium nitrates. The static and dynamical features calculated were endorsed by comparing the experimental X-ray data with the theoretical ones. A reliable description cannot be obtained with classical molecular dynamics owing to polarization effects. Contrariwise, the structure factor and the vibrational frequencies obtained from ab initio molecular dynamics trajectories are in very good agreement with the experiment. A careful analysis has provided additional information on the complex hydrogen bonding network that exists in this liquid.

  8. Theoretical study of atoms by the electronic kinetic energy density and stress tensor density

    CERN Document Server

    Nozaki, Hiroo; Tachibana, Akitomo

    2016-01-01

    We analyze the electronic structure of atoms in the first, second and third periods using the electronic kinetic energy density and stress tensor density, which are local quantities motivated by quantum field theoretic consideration, specifically the rigged quantum electrodynamics. We compute the zero surfaces of the electronic kinetic energy density, which we call the electronic interfaces, of the atoms. We find that their sizes exhibit clear periodicity and are comparable to the conventional atomic and ionic radii. We also compute the electronic stress tensor density and its divergence, tension density, of the atoms, and discuss how their electronic structures are characterized by them.

  9. Heuristic Synthesis of Reversible Logic – A Comparative Study

    Directory of Open Access Journals (Sweden)

    Chua Shin Cheng

    2014-01-01

    Full Text Available Reversible logic circuits have been historically motivated by theoretical research in low-power, and recently attracted interest as components of the quantum algorithm, optical computing and nanotechnology. However due to the intrinsic property of reversible logic, traditional irreversible logic design and synthesis methods cannot be carried out. Thus a new set of algorithms are developed correctly to synthesize reversible logic circuit. This paper presents a comprehensive literature review with comparative study on heuristic based reversible logic synthesis. It reviews a range of heuristic based reversible logic synthesis techniques reported by researchers (BDD-based, cycle-based, search-based, non-search-based, rule-based, transformation-based, and ESOP-based. All techniques are described in detail and summarized in a table based on their features, limitation, library used and their consideration metric. Benchmark comparison of gate count and quantum cost are analysed for each synthesis technique. Comparing the synthesis algorithm outputs over the years, it can be observed that different approach has been used for the synthesis of reversible circuit. However, the improvements are not significant. Quantum cost and gate count has improved over the years, but arguments and debates are still on certain issues such as the issue of garbage outputs that remain the same. This paper provides the information of all heuristic based synthesis of reversible logic method proposed over the years. All techniques are explained in detail and thus informative for new reversible logic researchers and bridging the knowledge gap in this area.

  10. A Comparative Study of Default Reasoning and Epistemic Processes

    Institute of Scientific and Technical Information of China (English)

    李未

    1993-01-01

    A comparative study between the theories of default reasoning and open logic is given.Some concepts of open logic,such as new premises,rejections by facts,reconstructions ,epistemic processes,and its limit are introduced to describe th evolution of hypotheses.An improved version of the limit theorem is given and proved.A model-theoretic interpretation of the closed normal defaults is given using the above concepts and the corresponding completeness is proved.Any extension of a closed normal default theory is proved to be the linit of a δ-partial increasing epistemic process of that theory,and vice versa.It is proved that there exist two distinct extensions of a closed normal default theory iff there is an δ-non-monotonic epistemic process of that theory.The completeness of Reiter's proof is also given and proved,in terms of the epistemic processes.Finally,the work is compared with Gaerdenfors's theory of knowledge in flux.

  11. A theoretical study on the unsteady aerothermodynamics for attached flow models

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The principle of the unsteady aerothermodynamics was theoretically investigated for the attached flow. Firstly, two simplified models with analytic solutions to the N-S equations were selected for the research, namely the compressible unsteady flows on the infinite flat plate with both time-varying wall velocity and time-varying wall temperature boundary conditions. The unsteady temperature field and the unsteady wall heat flux (heat flow) were analytically solved for the second model. Then, the interaction characteristic of the unsteady temperature field and the unsteady velocity field in the simplified models and the effects of the interaction on the transient wall heat transfer were studied by these two analytic solutions. The unsteady heat flux, which is governed by the energy equation, is directly related to the unsteady compression work and viscous dissipation which originates from the velocity field governed by the momentum equation. The main parameters and their roles in how the unsteady velocity field affects the unsteady heat flux were discussed for the simplified models. Lastly, the similarity criteria of the unsteady aerothermodynamics were derived based on the compressible boundary layer equations. Along with the Strouhal number Stu, the unsteadiness criterion of the velocity field, StT number, the unsteadiness criterion of the temperature field was proposed for the first time. Different from the traditional method used in unsteady aerodynamics which measures the flow unsteadiness only by the Stu number, present results show that the flow unsteadiness in unsteady aerothermodynamics should be comprehensively estimated by comparing the relative magnitudes of the temperature field unsteadiness criterion StT number with the coefficients of other terms in the dimensionless energy equation.

  12. Theoretical study of the effect of stress-dependent remodeling on arterial geometry under hypertensive conditions.

    Science.gov (United States)

    Rachev, A

    1997-08-01

    Remodeling of arterial geometry was studied on the basis of a theoretical model. Sustained hypertension was simulated by a step increase in blood pressure. The artery was considered to be a thick-walled two-layer tube made of nonlinear elastic incompressible material. The basic hypothesis is that the artery remodels its zero-stress configuration in such a way that the strain and stress distributions in the arterial wall under hypertensive conditions are the same as under normotensive conditions. Using this hypothesis, a method for determining the geometrical dimensions of the zero-stress configuration of the hypertensive artery was proposed. To ensure uniqueness of the solution, two side conditions on the remodeling process are imposed: (a) the inner radius of the artery in the unloaded state remains unchanged; and (b) the ratio between the thickness of the inner and outer layer of the hypertensive artery in the zero-stress configuration is known. The model predicts that the arterial wall remodeling causes: (i) an increase of the wall thickness both in the unloaded and physiological states; (ii) an increase of the inner diameter of the hypertensive vessel under high pressure compared to the diameter of the normotensive artery under normal pressure; (iii) the opened-up configuration which arises when the unloaded arterial segment is cut radially still contains residual strains and stresses. These results are consistent with published experimental findings. It is speculated that the origin of residual stresses that exist in the unloaded and opened-up configurations is the stress-modulated growth.

  13. Growth, hyperpolarizability, characterization and theoretical studies of NLO active tris(allylthiourea)mercury(II) chloride

    Science.gov (United States)

    Rajasekar, M.; Muthu, K.; Aditya Prasad, A.; Meenakshisundaram, S. P.

    2015-04-01

    Single crystals of tris(allylthiourea)mercury(II) chloride (TATMC) have been grown by slow evaporation solution growth technique. It belongs to the trigonal system with noncentrosymmetric space group R3c and the cell parameters are, a = b = 11.4443(3) Å, c = 28.1142(6) Å, V = 3188.85(14) Å3, α = β = 90°, γ = 120° and Z = 6. Powder X-ray diffraction pattern reveals the crystallinity of the as-grown specimen and it closely resembles the simulated one from the single crystal XRD data. Good reflectance in the visible region is observed and the band gap energy is estimated using diffuse reflectance data by the application of Kubelka-Munk algorithm. The functional groups are identified by Fourier transform infrared spectral analysis and compared with theoretical spectrum. The crystal is stable up to the melting point and the mechanistic behavior is ascertained by microhardness studies. The second harmonic generation efficiency of TATMC is estimated by Kurtz and Perry powder technique. The first-order molecular hyperpolarizabilities of some tris(allylthiourea) complexes have been evaluated using density functional theory (DFT) employing B3LYP functional, LanL2DZ as basis set and results rationalized. The optimized geometry closely resembles the ORTEP. The Hirshfeld surface analysis is carried out using HF method with 3-21G as basis set. Investigation of the intermolecular interactions and crystal packing via Hirshfeld surface analysis, derived by single crystal XRD data, reveals the close contacts associated with strong interactions.

  14. Theoretical Study of Compact Objects: Pulsars, Thermally Emitting Neutron Stars and Magnetars

    Science.gov (United States)

    Lai, Dong

    This proposal focuses on understanding the various observational manifestations of magnetized neutron stars (NSs), including pulsars, radio-quiet thermally emitting NSs and magnetars. This is motivated by the recent and ongoing observational progress in the study of isolated NSs, made possible by space telescopes such as Chandra and XMM-Newton, and the prospect of near-future observations by NASA's Gravity and Extreme Magnetism SMEX (GEMS) mission (to be launched in 2014). Recent observations have raised a number of puzzles/questions that beg for theoretical understanding and modeling. The proposed research projects are grouped into two parts: (1) Theoretical modeling of surface (or near surface) X-ray emission from magnetized NSs, including the study of the physics of electron/ion cyclotron lines, radiative transfer during magnetar bursts, dense plasma refractive effect, partially ionized atmospheres, and calculations of X-ray polarization signatures of isolated and accreting magnetic NSs, in anticipation of their detections by GEMS. (2) Theoretical study and observational constraint on the internal structure and evolution of magnetic fields in young neutron stars in supernova remnants. The proposed research will improve our understanding of different populations of NSs and their underlying physical processes (including the extreme physics of strong-field quantum electrodynamics) and enhance the scientific return from the current and future NASA astrophysics missions. It is relevant to NASA's objective, ``Discover the origin, structure, evolution, and destiny of the universe''.

  15. Experimental FTIR and theoretical studies of gallic acid-acetonitrile clusters

    Science.gov (United States)

    Hirun, Namon; Dokmaisrijan, Supaporn; Tantishaiyakul, Vimon

    2012-02-01

    Gallic acid (3,4,5-trihydroxybenzoic acid, GA) has many possible conformers depending on the orientations of its three OH and COOH groups. The biological activity of polyphenolic compounds has been demonstrated to depend on their conformational characteristics. Therefore, experimental FTIR and theoretical studies of the GA-solvent clusters were performed to investigate the possible most favored conformation of GA. Acetonitrile (ACN) was selected as the solvent since its spectrum did not interfere with the OH stretching bands of GA. Also of importance was that these OH groups, in addition to the carboxyl group, of the GA are the most likely groups to interact with receptors. The solution of GA in the ACN solution was measured and the complex OH bands were deconvoluted to four component bands. These component bands corresponded to the three OH bands on the benzene ring and a broad band which is a combination band of mainly the OH of the COOH group and the inter- and intramolecular H-bonds from the OH groups on the ring. The conformations, relative stabilities and vibrational analysis of the GA monomers and the GA-ACN clusters were investigated using the B3LYP/6-311++G(2d,2p) method. Conformational analysis of the GA monomer yielded four most possible conformers, GA-I, GA-II, GA-III and GA-IV. These conformers were subsequently used for the study of the GA:ACN clusters at the 1:1, 1:2 and 1:4 mole ratios. The IR spectra of the most stable structures of these clusters were simulated and the vibrational wavenumbers of the OH and C dbnd O groups were compared with those from the experiment. The FTIR component bands were comparable to the computed OH bands of the GA-I-(ACN) 2, GA-IV-(ACN) 2 and GA-I-(ACN) 4 clusters. Furthermore, the C dbnd O stretching bands and the bands in the regions of 1800-1000 cm -1 obtained by computing and the experiment were similar for these clusters. Thus, GA-I and GA-IV are the most preferable conformations of GA in ACN and perhaps in the

  16. Catatonic schizophrenia: an international comparative study.

    Science.gov (United States)

    Chandrasena, R

    1986-04-01

    Thirty-five hospitalized catatonic schizophrenic patients from Sri Lanka were compared with 22 patients in the U.K. and 13 in Canada. The phenomenology was established using the Present State Examination. Results suggest that ethnicity, chronicity of illness and reception of neuroleptic treatment may influence the lower prevalence of catatonic symptoms among the U.K. and Canadian schizophrenics. Onset of illness appears to be among young adults and mutism, stupor, mannerisms, stereotypes and negativism were the common catatonic symptoms observed.

  17. New Thoughts about the Theoretical System of Current Comparative Literature%比较文学学科理论体系新思考

    Institute of Scientific and Technical Information of China (English)

    赵渭绒; 曹顺庆

    2012-01-01

    本文从三个方面对当前的比较文学学科理论体系进行新的思考。首先,指出学科发展第一、二阶段存在的理论缺陷及不足,指出影响研究既有实证性特点又有非实证性特点;平行研究认为不同文明之间不具备可比性,使其本身不具备"世界性胸怀"。其次,将差异性作为可比性提出来,学界不宜仅仅"求同"更应关注差异,笔者提出的比较文学变异学理论将进一步地完善比较文学学科理论体系。最后,指出比较文学的未来和发展趋势是进入世界文学发展阶段,在这一阶段中国学者将担任重要使命。%This article provides a new thought about the theoritical system of current comparative literature in three aspects. Firstly, it points out the drawbacks and weaknesses of the 1st and 2nd phases of the development of this discipline, namely the positivist and non-positivist characteristic of influence study, and the lack of a "world mind" in parallel study by claiming that there's no comparability between different cultures. Secondly, the cultural diversity should be highlighted as comparability since we should not only seek the common ground but also pay attention to the differences. The variation theory in eomparative literature raised by the present author can help complete the theoretical system of comparative literature. Thirdly, this artiele points out that eom- parative literature will enter the phase of world literature, in which Chinese scholars will play an important role.

  18. COMPARATIVE STUDY OF OWN FUNDS IN THE BANKING SYSTEM

    Directory of Open Access Journals (Sweden)

    Tesu Ramona

    2012-12-01

    Full Text Available The present article has as a reserch field theoretical, methodological and practical aspects of the own funds, taking into account the line-up attempts of the romanian banking system to the requirements of the European Union, materialised in the Basel Agreement. The objectives of the research theme, presented in this paper, are mainly oriented towards own funds. We also proposed the following secondary objectives: presenting the concept approaches concerning own funds, emphasysing the tipology of own funds and pointing out their purpose in the banking activity; presenting and analyse the evolution of the own funds in Romania, for a period of 8 years (2004-2011. Even though the actual stage of the research in this field is advanced, in the romanian and foreign literature which dedicate a lot of theoretical and empiric studies concerning own funds. In our study we will use a theoretical and a practical research. The theoretical research describes the laws, reglementations and rules of application in the banking field in our country. In the practical part we will use as a research method the quality-comparative analyse by presenting details regarding bank back-ups. Despite the global financial crisis, the Romanian banking system can be considered as stable as a whole, with levels of capitalization, solvency and liquidity in accordance with consistent with prudential requirements. Tier 1, defined as the core of their sources of credit institutions through the permanent criteria, payment flexibility and capacity to absorb losses continued to overwhelmingly support a total equity. Appropriate quality of own funds is on their structure. The most important component frame our capital plus capital frame attached. The second component in terms is still represented by legal reserves. An important challenge for banks was to maintain a level of own funds accordance, in the conditions witch they were eroded by the current period losses. Tier 2 support rate of

  19. Molecular orbital ab initio and density functional theoretical study on reaction between PH2 and NO

    Institute of Scientific and Technical Information of China (English)

    HU; Zhengfa(胡正发); WANG; Zhenya(王振亚); LI; Haiyang(李海洋); ZHOU; Shikang(周士康)

    2002-01-01

    The theoretical study of reaction between PH2 and NO on the ground state potential energy surface is reported by using molecular orbital ab initio calculation and density function theory (DFT). Equilibrium structural parameters, harmonic vibrational frequencies, total energies and zero point energies of all species during reaction are computed by HF, MP2 (full) and B3LYP theory levels with the medium basis set 6-31G*. Theoretical results indicate that intermediate IM1(H2PNO) is firstly formed by overcoming a small energy barrier TS1, and then two four-membered ring transient states TS2 and TS5, with energy barriers 103.3 and 102.6 kJ/mol respectively,then H-migration and isomerization are completed and the products PN and H2O are formed. The reaction is exothermic one with -189.6 k J/mol released.

  20. Experimental and theoretical study of an atmospheric air plasma-jet

    Science.gov (United States)

    Xaubet, M.; Giuliani, L.; Grondona, D.; Minotti, F.

    2017-01-01

    In this work, we present an experimental and theoretical study of a low frequency, atmospheric plasma-jet discharge in air. Voltage-current characteristics and spectroscopic data were experimentally obtained, and a theoretical model developed to gain information of different aspects of the discharge. The discharge is modeled as a cathode layer with different mechanisms of electron emission and a main discharge channel that includes the most important kinetic reactions and species. From the electric measurements, it is determined that high electric field magnitudes are attained in the main channel, depending on the gas flow rate. Using the voltage-current characteristics as an input, the model allows to determine the plasma state in the discharge, including electron, gas, and molecular nitrogen vibrational temperatures. The model also allows to infer the mechanisms of secondary electron emission that sustain the discharge.

  1. Theoretical and experimental study of solar water heater with internal exchanger using thermosiphon system

    Energy Technology Data Exchange (ETDEWEB)

    Koffi, P.M.E.; Andoh, H.Y.; Gbaha, P. [Laboratoire d' Energies Nouvelles et Renouvelables, Institut National Polytechnique Felix Houphoeuet-Boigny, B.P. 1526 Yamoussoukro (Ivory Coast); Toure, S. [Laboratoire d' Energie Solaire, Universite de Cocody, 22 B.P. 582, Abidjan 22 (Ivory Coast); Ado, G. [Laboratoire des Procedes, Industriels de Syntheses de l' Environnement et de l' Energie Nouvelle, INP-HB 22, B.P. 1093 Yamoussoukro (Ivory Coast)

    2008-08-15

    This study presents a theoretical and experimental analysis of the thermal performance of a solar water heater prototype with an internal exchanger using a thermosiphon system. The heat exchanger made of a rolled copper tube is placed diagonally in the storage tank so that the hot fluid crosses a significant mass of stored water. The results focus mainly on the levels of the heat fluxes, temperatures recorded, mass flow rate and efficiency of the collector. During the main insulation period, one obtains satisfactory qualitative and quantitative agreement between the experimental and theoretical results of mass flow rate and temperatures. Those indicate heat fluxes whose peak reaches 989 W/m{sup 2}, collector outlet water temperature levels of more than 85.5 C and a collector thermal effectiveness around 58%. (author)

  2. A theoretical study of improved front-illuminated avalanche drift detectors

    Science.gov (United States)

    Liang, K.; Yuan, J.; Li, H. R.; Yang, R.; Han, D. J.

    2013-06-01

    In this study, two avalanche drift detector (ADD) concepts were theoretically examined. One was an improved detector with an avalanche photodiode (APD) collecting and double pn-junction drift configuration, and the other was a combination of an APD collecting and metal oxide semiconductor (MOS) drift structure. The feasibility of the devices was theoretically investigated by the ISE-TCAD program. ADD can be operated in either Geiger mode or linear mode. In the former case, the detector was found to be appropriate for a single photon avalanche detector with a large collection area. In the latter case, the detector was observed to be well suited to be coupled to a scintillator for gamma-ray detection. The improved ADDs are considered to have good performances in the short wavelength optical detection and in matching common scintillation crystals with more flexibility.

  3. Theoretical and experimental study on shear lag effect of partially cable-stayed bridge

    Institute of Scientific and Technical Information of China (English)

    WU Gao-feng; XU Hong

    2005-01-01

    In order to resolve the traffic congestion problem, many cable-stayed bridges are designed with a large width to span ratio. This results in significant shear lag effect to cause nonuniform stress distribution along the flanges of the beam of bridge.This paper reports study on the shear lag effect of the Lanzhou Xiaoxihu Yellow River Bridge. A 3D finite element model of the bridge was developed and finite element analysis (FEA) was done to obtain the theoretical results. To evaluate the theoretical results, a scaled model was made to conduct static test in laboratory. The experiment results accorded with the results obtained by FEA. It is proved that FEA is an effective method to predict shear lag effect of bridges of this type.

  4. Theoretical study of the alkaline-earth (LiBe)+ ion: structure, spectroscopy and dipole moments

    Science.gov (United States)

    Ghanmi, C.; Farjallah, M.; Berriche, H.

    2017-03-01

    We study theoretically the structure and spectroscopic properties of the alkali alkaline-earth (LiBe)+ ion. The potential energy curves and their spectroscopic parameters, permanent and transition dipole moments are determined with a quantum chemistry approach. The (LiBe)+ ion is modelled as two valence electron system moving in the field of Be2+ and Li+ cores, which are described by pseudopotentials. In addition, effective core-polarization potentials are included to correct the energy. The molecular calculations are performed using a standard quantum chemistry approach based on the pseudopotential model, Gaussian basis sets, effective core polarization potentials, and full configuration interaction (CI) calculations. The precision of our spectroscopic parameters are discussed by comparison with currently available theoretical results. A rather good agreement is observed for the ground and first excited states. The permanent dipole moments reveal many abrupt changes, which are localized at particular distances corresponding to the positions of the avoided crossings.

  5. A review of recent theoretical studies in nonlinear crystals: towards the design of new materials

    Science.gov (United States)

    Luppi, Eleonora; Véniard, Valérie

    2016-12-01

    Nonlinear optics is an important and exciting field of fundamental and applied research, with applications in many different disciplines such as physics chemistry, material science and biology. In the recent years, nonlinear optical phenomena started to be also widely used in technological applications for optoelectronics and photovoltaics. This coincided with an important experimental and theoretical search for new materials with an efficient and exploitable nonlinear optical response. Here, starting from the discovery of nonlinear optics, we review the most important theoretical formalisms developed to understand, interpret and predict the nonlinear optical phenomena. We show the different level of approximation of the many-electrons interactions that these formalisms can describe which are fundamental in the interpretation of the experiments. The impact of the theory is then analyzed on different classes of new materials particularly studied in these years: silicon bulk to nano, compound semiconductors, graphene, transition metal dichalcogenide, hexagonal boron nitride and borate crystals.

  6. Application of matching liquid on the refractive index measurement of biotissue: A theoretical and experimental study

    Science.gov (United States)

    Wang, Jin; Ye, Qing; Deng, Zhichao; Zhou, Wenyuan; Mei, Jianchun; Zhang, Chunping; Tian, Jianguo

    2014-05-01

    The application of matching liquid on the measurement of the refractive index (RI) of biotissue using total internal reflection (TIR) method is investigated in detail. A theoretical model describing samples with different absorbing and scattering ability is given based on Fresnel formula. The theoretical calculation is verified by experimental results of three simulation samples (transparent plexiglass, white plexiglass and ZB3 glass) and cedar wood oil as the matching liquid. Reflectance curves of porcine tissue samples were recorded and systematically studied using two kinds of matching liquid (cedar wood oil and adipose oil) at the incident of TE and TM wave, respectively. Method for proper selection of matching liquid under different conditions is discussed.

  7. Comparative Transport Studies of '1212' Superconductors

    Directory of Open Access Journals (Sweden)

    Albert Gapud

    1999-12-01

    Full Text Available HgBa2CaCu2O6+δ (Hg -1212 thin films were fabricated by exchanging the T1 cations in TlBa2CaCu2O7-δ (Tl-1212 thin films with Hg cations, causing a 30-K increase in Tc. To determine how this exchange effects such a Tc increase, the irreversibility lines, temperature dependence of critical current density, and temperature dependence of Hall angle ofHg-1212 and TI-1212 thin films were measured and then compared. The results strongly suggest that the Tc shift is caused by a doubling of charge carrier density.

  8. Genetic network models: a comparative study

    Science.gov (United States)

    van Someren, Eugene P.; Wessels, Lodewyk F. A.; Reinders, Marcel J. T.

    2001-06-01

    Currently, the need arises for tools capable of unraveling the functionality of genes based on the analysis of microarray measurements. Modeling genetic interactions by means of genetic network models provides a methodology to infer functional relationships between genes. Although a wide variety of different models have been introduced so far, it remains, in general, unclear what the strengths and weaknesses of each of these approaches are and where these models overlap and differ. This paper compares different genetic modeling approaches that attempt to extract the gene regulation matrix from expression data. A taxonomy of continuous genetic network models is proposed and the following important characteristics are suggested and employed to compare the models: inferential power; predictive power; robustness; consistency; stability and computational cost. Where possible, synthetic time series data are employed to investigate some of these properties. The comparison shows that although genetic network modeling might provide valuable information regarding genetic interactions, current models show disappointing results on simple artificial problems. For now, the simplest models are favored because they generalize better, but more complex models will probably prevail once their bias is more thoroughly understood and their variance is better controlled.

  9. Advertisement Analysis: A Comparative Critical Study

    Science.gov (United States)

    Abdelaal, Noureldin Mohamed; Sase, Amal Saleh

    2014-01-01

    This study aimed at analyzing two advertisements, and investigating how advertisers use discourse and semiotics to make people and customers buy into their ideas, beliefs, or simply their products. The two advertisements analyzed are beauty products which have been selected from internet magazines. The methodology adopted in this study is…

  10. Internationalization, Globalization and Relationship Networks as an Epistemological Framework Based on Comparative Studies in Education

    Science.gov (United States)

    García, Amelia Molina; Lara, José Luis Horacio Andrade

    2016-01-01

    In this paper we present some thoughts on the epistemological framework of comparative studies in education. We present some concepts on the internationalization, globalization and inter-relation networks, based on Jürgen Schriewer, Immanuel Wallerstein, and Norbert Elias's theoretical concepts. These reflections were built within the framework of…

  11. Determinants of health policy impact: comparative results of a European policymaker study.

    NARCIS (Netherlands)

    Rütten, A.; Lüschen, G.; Lengerke, T. von; Abel, T.; Kannas, L.; Rodríguez Diaz, J.A.; Vinck, J.; Zee, J. van der

    2003-01-01

    OBJECTIVES: This article will use a new theoretical framework for the analysis of health policy impact introduced by Rutten et al. (2003). In particular, it will report on a comparative European study of policymakers' perception and evaluation of specific determinants of the policy impact, both in

  12. COMPARATIVE STUDY OF LIGHT SOURCES FOR HOUSEHOLD

    Directory of Open Access Journals (Sweden)

    Andrzej PAWLAK

    2017-01-01

    Full Text Available The article describes test results that provided the ground to define and evaluate basic photometric, colorimetric and electric parameters of selected, widely available light sources, which are equivalent to a traditional incandescent 60-Watt light bulb. Overall, one halogen light bulb, three compact fluorescent lamps and eleven LED light sources were tested. In general, it was concluded that in most cases (branded products, in particular the measured and calculated parameters differ from the values declared by manufacturers only to a small degree. LED sources prove to be the most beneficial substitute for traditional light bulbs, considering both their operational parameters and their price, which is comparable with the price of compact fluorescent lamps or, in some instances, even lower.

  13. Earthquake Correlations and Networks- A Comparative Study

    CERN Document Server

    G., T R Krishna Mohan P

    2010-01-01

    We quantify the correlation between earthquakes and use the same to distinguish between relevant causally connected earthquakes. Our correlation metric is a variation on the one introduced by Baiesi and Paczuski (2004). A network of earthquakes is constructed, which is time ordered and with links between the more correlated ones. Recurrences to earthquakes are identified employing correlation thresholds to demarcate the most meaningful ones in each cluster. Data pertaining to three different seismic regions, viz. California, Japan and Himalayas, are comparatively analyzed using such a network model. The distribution of recurrence lengths and recurrence times are two of the key features analyzed to draw conclusions about the universal aspects of such a network model. We find that the unimodal feature of recurrence length distribution, which helps to associate typical rupture lengths with different magnitude earthquakes, is robust across the different seismic regions. The out-degree of the networks shows a hub ...

  14. Nonlinear analysis of RED - a comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Kai; Wang Xiaofan E-mail: xfwang@sjtu.edu.cn; Xi Yugeng

    2004-09-01

    Random Early Detection (RED) is an active queue management (AQM) mechanism for routers on the Internet. In this paper, performance of RED and Adaptive RED are compared from the viewpoint of nonlinear dynamics. In particular, we reveal the relationship between the performance of the network and its nonlinear dynamical behavior. We measure the maximal Lyapunov exponent and Hurst parameter of the average queue length of RED and Adaptive RED, as well as the throughput and packet loss rate of the aggregate traffic on the bottleneck link. Our simulation scenarios include FTP flows and Web flows, one-way and two-way traffic. In most situations, Adaptive RED has smaller maximal Lyapunov exponents, lower Hurst parameters, higher throughput and lower packet loss rate than that of RED. This confirms that Adaptive RED has better performance than RED.

  15. A comparative study of microbiological and physicochemical ...

    African Journals Online (AJOL)

    Ethiopian Journal of Environmental Studies and Management ... Rwandan Water and Sanitation Corporation ltd (WASAC) water branches: Kimisagara WASAC water ... strategy for better water quality especially along the distribution network.

  16. Theoretical and Experimental Study on Electromechanical Coupling Properties of Multihammer Synchronous Vibration System

    Directory of Open Access Journals (Sweden)

    Xin Lai

    2016-01-01

    Full Text Available Industrial simulation of real external load using multiple exciting points or increasing exciting force by synchronizing multiple exciting forces requires multiple vibration hammers to be coordinated and work together. Multihammer vibration system which consists of several hammers is a complex electromechanical system with complex electromechanical coupling. In this paper, electromechanical coupling properties of such a multihammer vibration system were studied in detail using theoretical derivation, numerical simulation, and experiment. A kinetic model of multihammer synchronous vibration system was established, and approximate expressions for electromechanical coupling strength were solved using a small parameter periodic averaging method. Basic coupling rules and reasons were obtained. Self-synchronization and frequency hopping phenomenon were also analyzed. Subsequently, numerical simulations were carried out and electromechanical coupling process was obtained for different parameters. Simulation results verify correctness of the proposed model and results. Finally, experiments were carried out, self-synchronization and frequency hopping phenomenon were both observed, and results agree well with theoretical deduction and simulation results. These results provide theoretical foundations for multihammer synchronous vibration system and its synchronous control.

  17. Experiences of using the Theoretical Domains Framework across diverse clinical environments: a qualitative study.

    Science.gov (United States)

    Phillips, Cameron J; Marshall, Andrea P; Chaves, Nadia J; Jankelowitz, Stacey K; Lin, Ivan B; Loy, Clement T; Rees, Gwyneth; Sakzewski, Leanne; Thomas, Susie; To, The-Phung; Wilkinson, Shelley A; Michie, Susan

    2015-01-01

    The Theoretical Domains Framework (TDF) is an integrative framework developed from a synthesis of psychological theories as a vehicle to help apply theoretical approaches to interventions aimed at behavior change. This study explores experiences of TDF use by professionals from multiple disciplines across diverse clinical settings. Mixed methods were used to examine experiences, attitudes, and perspectives of health professionals in using the TDF in health care implementation projects. Individual interviews were conducted with ten health care professionals from six disciplines who used the TDF in implementation projects. Deductive content and thematic analysis were used. Three main themes and associated subthemes were identified including: 1) reasons for use of the TDF (increased confidence, broader perspective, and theoretical underpinnings); 2) challenges using the TDF (time and resources, operationalization of the TDF) and; 3) future use of the TDF. The TDF provided a useful, flexible framework for a diverse group of health professionals working across different clinical settings for the assessment of barriers and targeting resources to influence behavior change for implementation projects. The development of practical tools and training or support is likely to aid the utility of TDF.

  18. Theoretical and experimental study of spectral characteristics of the photoacoustic signal from stochastically distributed particles.

    Science.gov (United States)

    Wang, Shaohua; Tao, Chao; Yang, Yiqun; Wang, Xueding; Liu, Xiaojun

    2015-07-01

    Photoacoustic imaging is an emerging technique which inherits the merits of optical imaging and ultrasonic imaging. However, classical photoacoustic imaging mainly makes use of the time-domain parameters of signals. In contrast to previous studies, we theoretically investigate the spectral characteristics of the photoacoustic signal from stochastic distributed particles. The spectral slope is extracted and used for describing the spectral characteristics of the photoacoustic signal. Both Gaussian and spherical distributions of optical absorption in particles are considered. For both situations, the spectral slope is monotonically decreased with the increase of particle size. In addition, the quantitative relationship between the spectral slope and the imaging system factors, including the laser pulse envelope, directivity of ultrasound transducer, and signal bandwidth, are theoretically analyzed. Finally, an idealized phantom experiment is performed to validate the analyses and examine the instrument independent of the spectral slope. This work provides a theoretical framework and new experimental evidence for spectrum analysis of the photoacoustic signal. This could be helpful for quantitative tissue evaluation and imaging based on the spectral parameters of the photoacoustic signal.

  19. Theoretical study of the dipole moment function of OH(X2Pi)

    Science.gov (United States)

    Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Taylor, Peter R.

    1989-01-01

    A theoretical study of the sensitivity of the dipole moment function (DMF) of the X2Pi ground state of OH to basis-set saturation and to refinements in the correlation treatment is presented. Emphasis is placed on determining the slope of the DMF at r(e) and the r value at which the maximum occurs. Consideration is given to the effect of oxygen polarization functions up through h type, expansion of the active orbital space to include the O 3d-delta orbital, the effect of higher excitations using the averaged coupled-pair functional method, and the effect of evaluating the dipole moment as an energy derivative rather than as an expectation value. The theoretical DMFs obtained here, which should be the most accurate to date, differ markedly from an empirical DMF of Turnbull and Lowe that is based on experimentally derived intensity ratios. The theoretical DMFs agree better with a recently published DMF of Nelson et al., but suggest that this empirical DMF is also inaccurate for r greater than 2.3 a0.

  20. Theoretical and experimental studies on dynamics of double-helical gear system supported by journal bearings

    Directory of Open Access Journals (Sweden)

    Minghu Yin

    2016-05-01

    Full Text Available The dynamic behaviour of a double-helical gear system supported by journal bearings is theoretically and experimentally investigated in this study. A bending–torsional–axial coupling model for dynamic analysis of double-helical gear system is developed. Influence of the time-varying mesh stiffness and damping is considered. Oil film stiffness and damping of the supporting journal bearing are supposed to be time-varying, and the time-varying oil film stiffness and damping are predicted by a back propagation neural network, which is optimized by genetic algorithm. A double-helical gear–rotor–journal bearing system test rig is also established to carry out the experimental investigations, such as the dynamic transmission errors of gear pairs. The comparisons between theoretical and experimental results show that the time-varying oil film dynamic coefficients of journal bearings are an important internal excitation. The theoretical model with time-varying oil film stiffness and damping can predict the gear dynamics more accurate than the model with time-invariant oil film stiffness and damping, and the neural network optimized by genetic algorithm can obtain the time-varying oil film stiffness and damping efficiently and accurately for the dynamic analysis of double-helical gear system.