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Sample records for chromatography theoretical investigations

  1. Electrochemically modulated liquid chromatography: Theoretical investigations and applications from the perspectives of chromatography and interfacial electrochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Keller, David W.

    2005-05-01

    Electrochemically modulated liquid chromatography (EMLC) employs a conductive material as both a stationary phase for chromatographic separations and as a working electrode for performing electrochemistry experiments. This dual functionality gives EMLC the capacity to manipulate chromatographic separations by changing the potential applied (E{sub app}) to the stationary phase with respect to an external reference. The ability to monitor retention as a function of E{sub app} provides a means to chromatographically monitor electrosorption processes at solid-liquid interfaces. In this dissertation, the retention mechanism for EMLC is examined from the perspective of electrical double layer theory and interfacial thermodynamics. From the chromatographic data, it is possible to determine the interfacial excess ({Lambda}) of a solute and changes in interfacial tension (d{gamma}) as a function of both E{sub app} and the supporting electrolyte concentration. Taken together, these two experimentally manipulated parameters can be examined within the context of the Gibbs adsorption equation to delineate the contribution of a variety of interfacial properties, including the charge of solute on the stationary phase and the potential of zero charge (PZC), to the mechanism behind EMLC-based retention. The chromatographic probing of interfacial phenomena is complemented by electroanalytical experiments that exploit the ability to monitor the electronic current flowing through an EMLC column. Cyclic voltammetry and chronoamperometry of an EMLC column are used to determine the electronic performance characteristics of an EMLC column. An electrochemical flow injection analysis of a column is provided in which the current required to maintain a constant E{sub app} is monitored and provides a way to examine the influence that acetonitrile and supporting electrolyte composition, flow rate, column backpressure, and ionic strength have on the structure of electrified interfaces.

  2. UNIFIED THEORETICAL MOMENT EXPRESSIONS FOR ELUTION CHROMATOGRAPHY AND FRONTAL CHROMATOGRAPHY

    Institute of Scientific and Technical Information of China (English)

    YANGGengliang; TAOZuyi

    1992-01-01

    The unified theoretical moment expressions for elution chromatography and frontal chromatography when the sorption process is described by a linear model were derived. The moment expressions derived by previous authors can be obtained from these unified theoretical moment expressions. In this paper, a mathematical analysis has been carried out so as to set up a unified theoretical basis for elution and frontal chromatography.

  3. Theoretical Investigations Regarding Single Molecules

    DEFF Research Database (Denmark)

    Pedersen, Kim Georg Lind

    interfere destructively or constructively. Destructive interference effects in electron transport could potentially improve thermo-electrics, organic logic circuits and energy harvesting. We have investigated destructive interference in off-resonant transport through organic molecules, and have found a set...

  4. Theoretical Studies of PCl3/H2 Gas Chromatography Mechanism

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-Li; MA Lin; SUN Ren-An

    2007-01-01

    Density functional theory B3LYP method was firstly applied to fully optimize the geometrical configuration of each stable point on PCl3/H2 gas chromatography reaction potential energy surface on the 6-311G** basis set, and single point energy was computed at the QCISD(T)/ 6-311G** level, then the transition state was validated by analyzing the unique imaginary vibration modes of each transition state and calculating intrinsic reaction coordinate (IRC), and the major reaction and competing reaction paths of PCl3/H2 gas chromatography reaction were presented through comparing active energy barrier, and phosphor was finally gained from the reaction of PH and PCl.

  5. Theoretical Investigation of Guide Wave Flowmeter

    Science.gov (United States)

    Sato, Harumichi; Lebedev, Maxim; Akedo, Jun

    2007-07-01

    Cylindrical pipes are widely used in industries such as nuclear power plants and micro total analysis systems (μTAS). Measuring the flow rate of fluid in such pipes is critical. Ultrasonic flowmeters are noncontact, nondestructive, and easy-to-use devices, and are therefore widely used. However, typical bulk-wave-based ultrasonic flowmeters cannot be used for pipes narrower than the wavelength of bulk waves. For such pipes, we are currently developing a “guide wave flowmeter” that uses guide waves instead of bulk waves. Previously, we theoretically and experimentally investigated a pipe filled with quiescent fluid for all modes [Jpn. J. Appl. Phys. 45 (2006) 4573]. In this study, we expanded our theoretical investigation to a cylindrical pipe containing flowing fluid, and then compared the results with experimental results. Both the theoretical and experimental results revealed that the flow rate can be determined by measuring the sound velocity (propagation time) of guide waves. This is the operating principle of our guide wave flowmeter.

  6. Theoretical investigation of aspects of radioactive contamination

    International Nuclear Information System (INIS)

    The BNFL programme of work has investigated theoretical aspects of the mechanisms responsible for the deposition and adherence of contamination to metallic surfaces and the energetics of physical decontamination processes. The work has been conducted in two phases: The theoretical and laboratory study of deposition of species from aqueous media on to stainless steel; Theoretical assessment of the forces causing the attraction of PuO2 and UO2 particles to stainless steel in an air environment and comparison of these forces with the energies delivered by physical jetting processes. The first phase produced a model which was found to give good agreement with plant operational experience of the deposition of simple aqueous ions such as Cobalt. Due to the complexities, however, of surface / colloid and surface / particle interactions the model was found not to be successful at predicting deposition for more complex compounds, such as Ruthenium Nitrosyls. At this stage the model had fulfilled its original requirement of underpinning design work on pipework shielding systems and it was decided not to pursue the library of chemical speciation data that would be necessary to model the behaviour of a full spectrum of possible contaminants. The second phase predicts by theoretical analysis that the relation of the energy delivered by jetting techniques to the physical forces causing the adherence of PuO2 and UO2 particles will vary considerably with particle size. This is particularly notably for larger PuO2 particles which are firmly held as a result of high levels of electrostatic charge due to their intense alpha activity. Small particles tend to be difficult to remove due to the low profile that they present to the jetting medium. Large and small PuO2 particles and small UO2 particle are thus predicted to be difficult to remove and will present an energy threshold which may not be crossed by all decontamination techniques. (author)

  7. Theoretical investigations of grout seal longevity

    International Nuclear Information System (INIS)

    Theoretical investigations into the longevity of repository seals have dealt primarily with the development of a methodology to evaluate interactions between portland cement-based grout and groundwater. Groundwater travel times through a seal have been calculated based on Darcy's Law, with an assumed hydraulic gradient for the site and initial hydraulic conductivity for the grout. Chemical interactions between a model grout and actual groundwater compositions have been evaluated by means of geochemical modelling codes. Changes in grout porosity derived from the geochemical modelling have been extended to yield estimates of hydraulic conductivity, based on published experimental results. Also, a preliminary approach to the evaluation of the role of diffusion processes in grout alteration has begun. Results of these investigations suggest that cement grout seals will maintain an acceptable level of performance for tens of thousands to millions of years, provided the repository is sited where groundwater chemistry is compatible with the seals and hydrologic gradients are low. (au) (21 refs.)

  8. 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

  9. Theoretical study of rock mass investigation efficiency

    International Nuclear Information System (INIS)

    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

  10. Theoretical and experimental investigations of Chinese evacuated tubular solar collectors

    DEFF Research Database (Denmark)

    Qin, Lin; Furbo, Simon

    1999-01-01

    Four different marketed Chinese evacuated tubular solar collectors have been investigated both theoretically and experimentally. The advantages of the investigated solar collectors compared to normal flat plate collectors were elucidated.......Four different marketed Chinese evacuated tubular solar collectors have been investigated both theoretically and experimentally. The advantages of the investigated solar collectors compared to normal flat plate collectors were elucidated....

  11. Application of gas chromatography to the investigations on polypropylene radiolysis

    International Nuclear Information System (INIS)

    Refinement of the gas chromatography (GC) instrumental approach permitted not only improvement of investigation in basic research, but also development of a new kind of polypropylene blends, more suitable for the production of medical devices and radiation sterilization. It has been shown, that using the GC method not only methane and carbon dioxide can be measured, but also the consumption of oxygen which reacts with free radicals on the polypropylene chain

  12. Theoretical And Experimental Investigation Of Reditrons

    Science.gov (United States)

    Kwan, T. J.; Davis, H. A.; Fulton, R. D.; Sherwood, E. G.

    1988-05-01

    We have carried out theoretical and experimental study to optimize the efficiency of microwave production of the reditron. In the optimal configuration, we have achieved the production of 3.3 GW of microwave radiation at 10.0% efficiency with a very narrow spectrum centered at 2.15 GHz. This is roughly a factor of 3.5 increase in efficiency and about 3 in bandwidth narrowing over conventional vircators. In additon, we found that the use of cavities can achieved bandwidth narrowing, stability of frequency during repeated operation, improvement of mode selectivity.

  13. On the possibility of shear-driven chromatography: a theoretical performance analysis.

    Science.gov (United States)

    Desmet, G; Baron, G V

    1999-09-01

    The use of shear forces for the generation of the mobile phase flow in chromatographic separations is proposed. This novel chromatographic operating principle, referred to as shear-driven chromatography (SDC), completely circumvents the pressure-drop limitation of conventional pressure-driven GC and LC without affecting the operational flexibility (choice of mobile and stationary phases, possibility of solvent and/or temperature programming, etc.). In the present paper, the expression for the height equivalent to a theoretical plate in SDC in a channel with a flat rectangular cross-section is established and is used to demonstrate the large gain in analysis speed under LC, GC and supercritical fluid chromatography conditions. PMID:10514973

  14. Theoretical investigation electroopticalof nonlinear properties ofchromophores

    Institute of Scientific and Technical Information of China (English)

    ZhouYu-fang; ZhuangDe-xin

    2004-01-01

    Organic electrooptical (EO) chromophores are now gaining more attention because the property of organic photorefrative (PR) materials could be controlled by doped EO chromophores. In this paper, nonlinear optical (NLO) properties of a new group of organic electrcoptical chromophores, synthesized recently in our laboratory, were elucidated theoretically with the quantum chemical density functional theory (DFT) and the intermediate neglect of differential overlap Hamilton and the configuration interaction (INDO/CI), as well as semiemperical Austin Modlel 1 (AM1) methods. The electronic transition intensity, dipole moment and the second- order polarizability were obtained. The results show this group of chromophores possess appropriate optical absorption property and good electrooptical property and optical activity. The second-order polarizabilities β are as large as the order of 10-29 to 10-28 ESU, indicating the promising applications in the future. The physical mechanism of NLO is discussed by means of molecular orbital and electronic charge distribution.

  15. Theoretical investigations relevant to magnetic fusion research

    International Nuclear Information System (INIS)

    Substantial and significant progress on several fronts of our investigations has been achieved since our last renewal proposal. A brief discussion of these results and their relevance to on-going national experiments will precede the proposed work in each area

  16. Electrically Responsive Surfaces: Experimental and Theoretical Investigations

    Science.gov (United States)

    2016-01-01

    orientation of the surface-tethered molecules under electroinduced switching, but also provided an in-depth characterization of the system reversibility. Furthermore, the unique support from molecular dynamics (MD) simulations is highlighted. MD simulations with polarizable force fields (FFs), which could give proper description of the charge polarization caused by electrical stimulus, have helped not only back many of the experimental observations, but also to rationalize the mechanism of switching behavior. More importantly, this polarizable FF-based approach can efficiently be extended to light or pH stimulated surfaces when integrated with reactive FF methods. The interplay between experimental and theoretical studies has led to a higher level of understanding of the switchable surfaces, and to a more precise interpretation and rationalization of the observed data. The perspectives on the challenges and opportunities for future progress on stimuli-responsive surfaces are also presented. PMID:27268783

  17. Electrically Responsive Surfaces: Experimental and Theoretical Investigations.

    Science.gov (United States)

    Cantini, Eleonora; Wang, Xingyong; Koelsch, Patrick; Preece, Jon A; Ma, Jing; Mendes, Paula M

    2016-06-21

    the surface-tethered molecules under electroinduced switching, but also provided an in-depth characterization of the system reversibility. Furthermore, the unique support from molecular dynamics (MD) simulations is highlighted. MD simulations with polarizable force fields (FFs), which could give proper description of the charge polarization caused by electrical stimulus, have helped not only back many of the experimental observations, but also to rationalize the mechanism of switching behavior. More importantly, this polarizable FF-based approach can efficiently be extended to light or pH stimulated surfaces when integrated with reactive FF methods. The interplay between experimental and theoretical studies has led to a higher level of understanding of the switchable surfaces, and to a more precise interpretation and rationalization of the observed data. The perspectives on the challenges and opportunities for future progress on stimuli-responsive surfaces are also presented. PMID:27268783

  18. A theoretical investigation on multilayer silicon nanoribbons

    Science.gov (United States)

    Zhang, Xiaohan; Ge, Hongyu; Wang, Guo; Liao, Yi

    2016-05-01

    Multilayer silicon nanoribbons constructed with an armchair silicene nanoribbon are investigated based on density functional theory calculations. The bare nanoribbons are metallic except for the mono- or double-layer samples. The partially occupied frontier bands are contributed by near-degenerate surface and edge states. Edge-hydrogen atoms passivate the edge states and full hydrogenation causes a metal-semiconductor transition. These are all explained using frontier wavefunctions. A six-layer full hydrogen-passivated silicon nanoribbon has a band gap larger than that of bulk silicon, and its hole and electron mobilities are also on the order of 103 cm2 V-1 s-1, implying potential application in small-size logic devices.

  19. Experimental and theoretical investigation of high gradient acceleration

    International Nuclear Information System (INIS)

    This report contains a technical progress summary of the research conducted under the auspices of DOE Grant No. DE-FG0291ER-40648. ''Experimental and Theoretical Investigations of High Gradient Acceleration.'' This grant supports three research tasks: Task A consists of the design and fabrication of a 17GHz of photocathode gun, Task B supports the testing of high gradient acceleration using a 33GHz structure, and Task C comprises theoretical investigations, both in support of the experimental tasks and on critical physics issues for the development of high energy linear colliders. This report is organized as follows. The development of an rf gun design and research progress on the picosecond laser system is summarized in Sec. 2, the status of the studies of the LBL/Haimson high gradient structure, using a 50 MW free-electron laser is summarized in Sec. 3, and theoretical research progress is described in Sec. 4. Supporting material is contained in Appendices A-G

  20. THEORETICAL INVESTIGATION OF SELECTED TRACE ELEMENTS IN COAL GASIFICATION PLANTS

    Science.gov (United States)

    The report gives results of a theoretical investigation of the disposition of five volatile trace elements (arsenic, boron, lead, selenium, and mercury) in SNG-producing coal gasification plants. Three coal gasification processes (dry-bottom Lurgi, Koppers-Totzek, and HYGAS) were...

  1. Novel approach to theoretical investigation of heavy quasi-molecules

    International Nuclear Information System (INIS)

    The new approach to the theoretical investigation of heavy quasi-molecules is created. The approach is based on the application of finite basis set method in Cassini coordinates. The method allows the generation of accurate quasi-complete spectrum of two-center Dirac Hamiltonian eigen-states.

  2. Determination of theoretical retention times for peptides analyzed by reversed- -phase high-performance liquid chromatography

    Directory of Open Access Journals (Sweden)

    Jerzy Dziuba

    2011-06-01

    Full Text Available   Background. Peptides are important components of foods mainly due to their biological activity. The basic method of their identification is reversed phase high-performance liquid chromatography coupled with electrospray-ionization mass spectrometry (RP-HPLC-ESI-MS. Retention time (tR prediction in silico is very helpful in analysis of multicomponent peptide mixtures. One of problems associated with RP-HPLC-ESI-MS is deterioration of mass spectra quality by trifluoroacetic acid (TFA. This problem can be avoided through the use of chromatographic columns designed for work with low TFA concentrations in mobile phase. The objective of this study was to determine the correlations between peptide retention times predicted with the use of a program available on-line and experimental retention times obtained using the column working with low TFA concentrations. Material and methods. The set of synthetic peptides and bovine α-lactalbumin fragments (18 peptides was used in the experiment. Theoretical retention times were calculated using Sequence Specific Retention Calculator (SSRC program. The experimental retention times were measured via RP-HPLC-ESI-MS method using column working with low TFA content. The dependence between theoretical and experimental tR was expressed via empirical equations. Results. The best correlation between theoretical and experimental retention times of peptides containing at least four amino acid residues has been obtained when third order polynomial (R² = 0.9536. Prediction quality for di- and tripeptides was significantly lower. The method described can be applied for cysteine-containing peptides although our sample preparation procedure did not include modification of this amino acid, taken into attention by SSRC program. Conclusions. The results of this study validate the usefulness of a third degree polynomial as a simple function describing the correlation between peptide retention times predicted by an on

  3. Experimental and theoretical investigation of high gradient acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Wurtele, J.S.; Bekefi, G.; Chen, C.; Chen, S.C.; Temkin, R.J.

    1993-01-01

    This report contains a technical progress summary of the research conducted under the auspices of DOE Grant No. DE-AC02-91-ER40648, Experimental and Theoretical Investigations of High Gradient Acceleration''. This grant supports three research tasks: Task A consists of the design, fabrication and testing of a 17GHz RF photocathode gun, which can produce 2ps electron pulses with up to 1nC of charge at 2MeV energy and at a 1OHz repetition rate. Task B supports the testing of high gradient acceleration at 33GHz structure, and Task C comprises theoretical investigations, both in support of the experimental tasks and on critical physics issues for the development of high energy linear colliders.

  4. Experimental and theoretical investigation of high gradient acceleration

    International Nuclear Information System (INIS)

    This report contains a technical progress summary of the research conducted under the auspices of DOE Grant No. DE-AC02-91-ER40648, ''Experimental and Theoretical Investigations of High Gradient Acceleration''. This grant supports three research tasks: Task A consists of the design, fabrication and testing of a 17GHz RF photocathode gun, which can produce 2ps electron pulses with up to 1nC of charge at 2MeV energy and at a 1OHz repetition rate. Task B supports the testing of high gradient acceleration at 33GHz structure, and Task C comprises theoretical investigations, both in support of the experimental tasks and on critical physics issues for the development of high energy linear colliders

  5. Theoretical investigation of ordering and complexation in solutions of polyelectrolytes

    OpenAIRE

    Oskolkov, Nikolay

    2007-01-01

    The PhD thesis is dedicated to the theoretical investigation of two effects taking place in the ion-containing polymeric systems, namely, nematic ordering in solutions of rodlike polyelectrolytes and complexation in solutions of oppositely charged polyelectrolytes taking into account the effect of charge inversion (overcharging) of macroions. The correlation free energy of electrostatic interactions in solutions of rodlike polyelectrolytes was calculated within the framework of the Debye-H...

  6. Heuristics in Argumentation: A Game-Theoretical Investigation

    OpenAIRE

    Prakken, Henry; Riveret, Régis; Rotolo, Antonino; Sartor, Giovanni

    2008-01-01

    This paper provides a game-theoretical investigation on how to determine optimal strategies in dialogue games for argumentation. To make our ideas as widely applicable as possible, we adopt an abstract dialectical setting and model dialogues as extensive games with perfect information where optimal strategies are determined by preferences over outcomes of the disputes. In turn, preferences are specified in terms of expected utility combining the probability of success of arguments with the co...

  7. Experimental and Theoretical Investigations of Wet Flue Gas Desulphurisation

    DEFF Research Database (Denmark)

    Kiil, Søren

    temperature in the interval 313 - 333 K, pertinent for full-scale wet FGD packed towers. The possibility of co-firing straw and coal was investigated in a full-scale power plant. No ef-fects on the overall performance of the wet FGD plant were observed, though laboratory ex-periments with fine dust and fly......-scale experiments. In the theoretical part of the work, the laboratory and pilot plant observations are investigated using mathematical modelling.The mechanism underlying the rate of dissolution of finely grinded limestone particles was examined in a laboratory batch apparatus using acid titration. Three Danish...

  8. Theoretical investigation of the molecular structure of the isoquercitrin molecule

    Science.gov (United States)

    Cornard, J. P.; Boudet, A. C.; Merlin, J. C.

    1999-09-01

    Isoquercitrin is a glycosilated flavonoid that has received a great deal of attention because of its numerous biological effects. We present a theoretical study on isoquercitrin using both empirical (Molecular Mechanics (MM), with MMX force field) and quantum chemical (AM1 semiempirical method) techniques. The most stable structures of the molecule obtained by MM calculations have been used as input data for the semiempirical treatment. The position and orientation of the glucose moiety with regard to the remainder of the molecule have been investigated. The flexibility of isoquercitrin principally lies in rotations around the inter-ring bond and the sugar link. In order to know the structural modifications generated by the substitution by a sugar, geometrical parameters of quercetin (aglycon) and isoquercitrin have been compared. The good accordance between theoretical and experimental electronic spectra permits to confirm the reliability of the structural model.

  9. Theoretical investigations of intersubband relaxation in quantum wells

    CERN Document Server

    Khan-Ngern, S

    2002-01-01

    In this thesis intersubband relaxation of electrons in quantum wells is theoretically investigated. Firstly, the in-plane kinetic energy, and also well width dependences of electron intra- or intersubband scattering rates (or times), associated by longitudinal optical (LO) phonon emission in a semiconductor single quantum well (SQW) structure are presented. Semi-analytic calculations are carried out for a GaAs/Al sub 0 sub . sub 3 Ga sub 0 sub . sub 7 As SQW structure. The results show that the scattering rates (both for intra- and intersubband scattering) weakly depend on in-plane kinetic energy of the electron. Furthermore, the resulting calculations of well width dependence show that intrasubband scattering times gradually increase with well width contrasting with the intersubband scattering times which display a monotonic decrease. A theoretical study of the condition to achieve inverted population in a semiconductor double quantum well (DQW) structure is also presented. The LO-phonon assisted tunneling r...

  10. Multiple condensation induced water hammer events, experiments and theoretical investigations

    International Nuclear Information System (INIS)

    We investigate steam condensation induced water hammer (CIWH) phenomena and present experimental and theoretical results. Some of the experiments were performed in the PMK-2 facility, which is a full-pressure thermalhydraulic model of the nuclear power plant of VVER-440/312 type and located in the Atomic Energy Research Institute Budapest, Hungary. Other experiments were done in the ROSA facility in Japan. On the theoretical side CIWH is studied and analyzed with the WAHA3 model based on two-phase flow six first-order partial differential equations that present one dimensional, surface averaged mass, momentum and energy balances. A second order accurate high-resolution shockcapturing numerical scheme was applied with different kind of limiters in the numerical calculations. The applied two-fluid model shows some similarities to RELAP5 which is widely used in the nuclear industry to simulate nuclear power plant accidents. New features are the existence of multiple, independent CIWH pressure peaks both in experiments and in simulations. Experimentally measured and theoretically calculated CIWH pressure peaks are in qualitative agreement. However, the computational results are very sensitive against flow velocity. (orig.)

  11. Theoretical Investigations of Optical Origins of Fluorescent Graphene Quantum Dots

    Science.gov (United States)

    Wang, Jingang; Cao, Shuo; Ding, Yong; Ma, Fengcai; Lu, Wengang; Sun, Mengtao

    2016-04-01

    The optical properties of graphene quantum dots (GQDs) were investigated theoretically. We focused on the photoinduced charge transfer and electron-hole coherence of single-layer graphene in the electronic transitions in the visible regions. Surface functionalization with donor or acceptor groups produced a red shift in the absorption spectrum, and electrons and holes were highly delocalized. The recombination of excited, well-separated electron-hole (e–h) pairs can result in enhanced fluorescence. This fluorescence enhancement by surface functionalization occurs because of the decreased symmetry of the graphene resulting from the roughened structure of the surface-functionalized GQDs.

  12. Theoretical Investigations of Optical Origins of Fluorescent Graphene Quantum Dots

    Science.gov (United States)

    Wang, Jingang; Cao, Shuo; Ding, Yong; Ma, Fengcai; Lu, Wengang; Sun, Mengtao

    2016-01-01

    The optical properties of graphene quantum dots (GQDs) were investigated theoretically. We focused on the photoinduced charge transfer and electron-hole coherence of single-layer graphene in the electronic transitions in the visible regions. Surface functionalization with donor or acceptor groups produced a red shift in the absorption spectrum, and electrons and holes were highly delocalized. The recombination of excited, well-separated electron-hole (e–h) pairs can result in enhanced fluorescence. This fluorescence enhancement by surface functionalization occurs because of the decreased symmetry of the graphene resulting from the roughened structure of the surface-functionalized GQDs. PMID:27094439

  13. Theoretical Investigation of Trust in Small and Medium Sized Enterprises

    Directory of Open Access Journals (Sweden)

    Valentinas Navickas

    2014-06-01

    Full Text Available The hectic pace of competition pushes the sector of small and medium enterprise to adopt sophisticated marketing ideas. In this context, customers are becoming more and more selective. However, expansion possibilities are burdened by the great variety of limitations. The current study paper aims to investigate the academic perception of trust which is treated as competitive advantage for small and medium enterprises. The object of the article is trust in small and medium enterprises. It has three objectives: to analyse small and medium enterprise characteristics through the academic perspective; to consider trust from the theoretical point of view; and to present the models that centre their attention on the trust as a construct that enhances customer satisfaction. Regarding the novelty of the current study, it brings a novel approach on a great variety of collected understandings of trust and puts an important foundation for future theory and practice investigations.

  14. Investigations on Actuator Dynamics through Theoretical and Finite Element Approach

    Directory of Open Access Journals (Sweden)

    Somashekhar S. Hiremath

    2010-01-01

    Full Text Available This paper gives a new approach for modeling the fluid-structure interaction of servovalve component-actuator. The analyzed valve is a precision flow control valve-jet pipe electrohydraulic servovalve. The positioning of an actuator depends upon the flow rate from control ports, in turn depends on the spool position. Theoretical investigation is made for No-load condition and Load condition for an actuator. These are used in finite element modeling of an actuator. The fluid-structure-interaction (FSI is established between the piston and the fluid cavities at the piston end. The fluid cavities were modeled with special purpose hydrostatic fluid elements while the piston is modeled with brick elements. The finite element method is used to simulate the variation of cavity pressure, cavity volume, mass flow rate, and the actuator velocity. The finite element analysis is extended to study the system's linearized response to harmonic excitation using direct solution steady-state dynamics. It was observed from the analysis that the natural frequency of the actuator depends upon the position of the piston in the cylinder. This is a close match with theoretical and simulation results. The effect of bulk modulus is also presented in the paper.

  15. An Experimental and Theoretical Investigation of Electrostatically Coupled Cantilever Microbeams

    KAUST Repository

    Ilyas, Saad

    2016-06-16

    We present an experimental and theoretical investigation of the static and dynamic behavior of electrostatically coupled laterally actuated silicon microbeams. The coupled beam resonators are composed of two almost identical flexible cantilever beams forming the two sides of a capacitor. The experimental and theoretical analysis of the coupled system is carried out and compared against the results of beams actuated with fixed electrodes individually. The pull-in characteristics of the electrostatically coupled beams are studied, including the pull-in time. The dynamics of the coupled dual beams are explored via frequency sweeps around the neighborhood of the natural frequencies of the system for different input voltages. Good agreement is reported among the simulation results and the experimental data. The results show considerable drop in the pull-in values as compared to single microbeam resonators. The dynamics of the coupled beam resonators are demonstrated as a way to increase the bandwidth of the resonator near primary resonance as well as a way to introduce increased frequency shift, which can be promising for resonant sensing applications. Moreover the dynamic pull-in characteristics are also studied and proposed as a way to sense the shift in resonance frequency.

  16. A game theoretic investigation of deception in network security

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Thomas E.; Grosu, Daniel

    2010-12-03

    We perform a game theoretic investigation of the effects of deception on the interactions between an attacker and a defender of a computer network. The defender can employ camouflage by either disguising a normal system as a honeypot or by disguising a honeypot as a normal system. We model the interactions between defender and attacker using a signaling game, a non-cooperative two player dynamic game of incomplete information. For this model, we determine which strategies admit perfect Bayesian equilibria. These equilibria are refined Nash equilibria in which neither the defender nor the attacker will unilaterally choose to deviate from their strategies. Finally, we discuss the benefits of employing deceptive equilibrium strategies in the defense of a computer network.

  17. Applying Theoretical Approach for Predicting the Selective Calcium Channel Blockers Pharmacological Parameter by Biopartitioning Micellar Chromatography

    Institute of Scientific and Technical Information of China (English)

    WANG Su-Min; YANG Geng-Liang; LI Zhi-Wei; LIU Hai-Yan; GUO Hui-Juan

    2006-01-01

    The usefulness of biopartitioning micellar chromatography (BMC) for predicting oral drug acute toxicity and apparent bioavailability was demonstrated. A logarithmic model (an LD50 model) and the second order polynomial models (apparent bioavailability model) have been obtained using the retention data of the selective calcium channel blockers to predict pharmacological properties of compounds. The use of BMC is simple, reproducible and can provide key information about the acute toxicity and transport properties of new compounds during the drug discovery process.

  18. Theoretical investigations of grout seal longevity - Final report

    International Nuclear Information System (INIS)

    Theoretical investigations into the longevity of repository seals have dealt primarily with the development of a methodology to evaluate interactions between portland cement-based grout and groundwater. Evaluation of chemical thermodynamic equilibria between grout and groundwater, and among grout, groundwater, and granitic host rock phases using the geochemical codes EQ3NR/EQ6 suggests that a fracture filled with grout and saturated with groundwater will tend to fill and 'tighten' with time. Results of these investigations suggest that cement grout seals will maintain an acceptable level of performance for tens of thousands to millions of years, provided the repository is sited where groundwater chemistry is compatible with the seals and hydrologic gradients are low. The results of the grout: groundwater: rock calculations suggest that buffering of the fracture seals chemical systems by the granite rock may be important in determining the long-term fate of grout seals and the resulting phase assemblage in the fracture. The similarity of the modelled reaction products to those observed in naturally filled fractures suggests that with time equilibrium will be approached and grouted fractures subject to low hydrologic gradients will continue to seal. If grout injected into fractures materially reduces groundwater flux, the approach to chemical equilibrium will likely be accelerated. In light of this, even very thin or imperfectly grouted fractures would tighten in suitable hydrogeologic environments. (29 refs.) (au)

  19. Theoretical investigation of two-frequency generation mechanism in vircator

    International Nuclear Information System (INIS)

    At present, the virtual cathode systems (vircators) are used for generation of powerful emission. One of peculiarities of the magneto-insulated diode vircator is the generation possibility on the two frequencies. In particular, it can be used for plasma heating of fusion plasmas. In present paper the two-frequency generation mechanism for increasing of emission efficiency and realizing of the emission parameters operating is investigated. The problem has been investigated by means analytical and numerical methods. It has been shown that two-frequency generation regime is conditioned by two virtual cathodes forming. In result, the nonsymmetrical potential well is formed in which the flow electrons are captured. It has obtained that the depth of the potential well and emission power are considerably higher for the foil system in comparison with foilless system. The dependencies of frequency spectrum and efficiency on system geometry and external magnetic field have been determined. It has been shown that the frequency spectrum and emission power do not depend on drift tube length if it exceeds the Debye radius calculated with taking into account the reduction coefficient. The influence of transverse impulse and velocity spread on efficiency are studied. Comparison of theoretical results with experiments is carried out

  20. Theoretical and experimental investigation of multispectral photoacoustic osteoporosis detection method

    Science.gov (United States)

    Steinberg, Idan; Hershkovich, Hadas Sara; Gannot, Israel; Eyal, Avishay

    2014-03-01

    Osteoporosis is a widespread disorder, which has a catastrophic impact on patients lives and overwhelming related to healthcare costs. Recently, we proposed a multispectral photoacoustic technique for early detection of osteoporosis. Such technique has great advantages over pure ultrasonic or optical methods as it allows the deduction of both bone functionality from the bone absorption spectrum and bone resistance to fracture from the characteristics of the ultrasound propagation. We demonstrated the propagation of multiple acoustic modes in animal bones in-vitro. To further investigate the effects of multiple wavelength excitations and of induced osteoporosis on the PA signal a multispectral photoacoustic system is presented. The experimental investigation is based on measuring the interference of multiple acoustic modes. The performance of the system is evaluated and a simple two mode theoretical model is fitted to the measured phase signals. The results show that such PA technique is accurate and repeatable. Then a multiple wavelength excitation is tested. It is shown that the PA response due to different excitation wavelengths revels that absorption by the different bone constitutes has a profound effect on the mode generation. The PA response is measured in single wavelength before and after induced osteoporosis. Results show that induced osteoporosis alters the measured amplitude and phase in a consistent manner which allows the detection of the onset of osteoporosis. These results suggest that a complete characterization of the bone over a region of both acoustic and optical frequencies might be used as a powerful tool for in-vivo bone evaluation.

  1. A Theoretical Study of the Separation Principle in Size Exclusion Chromatography

    DEFF Research Database (Denmark)

    Wang, Yanwei; Teraoka, Iwao; Hansen, Flemming Yssing;

    2010-01-01

    The principle of polymer separation in size exclusion chromatography (SEC) is studied based on a classical equilibrium partitioning theory. The task is to examine the correlation between the mean span dimension of polymer chains and their equilibrium partition coefficients with confining pores....... Using an extended formulation of the recently developed confinement analysis from bulk structures (CABS) method, we calculate the partition coefficients for both linear and branched polymer chains with cylindrical pores—a model pore geometry that is considered to be more realistic for voids in SEC...

  2. Experimental Investigation and Theoretical Modeling of Nanosilica Activity in Concrete

    Directory of Open Access Journals (Sweden)

    Han-Seung Lee

    2014-01-01

    Full Text Available This paper presents experimental investigations and theoretical modeling of the hydration reaction of nanosilica blended concrete with different water-to-binder ratios and different nanosilica replacement ratios. The developments of chemically bound water contents, calcium hydroxide contents, and compressive strength of Portland cement control specimens and nanosilica blended specimens were measured at different ages: 1 day, 3 days, 7 days, 14 days, and 28 days. Due to the pozzolanic reaction of nanosilica, the contents of calcium hydroxide in nanosilica blended pastes are considerably lower than those in the control specimens. Compared with the control specimens, the extent of compressive strength enhancement in the nanosilica blended specimens is much higher at early ages. Additionally, a blended cement hydration model that considers both the hydration reaction of cement and the pozzolanic reaction of nanosilica is proposed. The properties of nanosilica blended concrete during hardening were evaluated using the degree of hydration of cement and the reaction degree of nanosilica. The calculated chemically bound water contents, calcium hydroxide contents, and compressive strength were generally consistent with the experimental results.

  3. Experimental and theoretical investigation of anaerobic fluidized bed biofilm reactors

    Directory of Open Access Journals (Sweden)

    M. Fuentes

    2009-09-01

    Full Text Available This work presents an experimental and theoretical investigation of anaerobic fluidized bed reactors (AFBRs. The bioreactors are modeled as dynamic three-phase systems. Biochemical transformations are assumed to occur only in the fluidized bed zone. The biofilm process model is coupled to the system hydrodynamic model through the biofilm detachment rate; which is assumed to be a first-order function of the energy dissipation parameter and a second order function of biofilm thickness. Non-active biomass is considered to be particulate material subject to hydrolysis. The model includes the anaerobic conversion for complex substrate degradation and kinetic parameters selected from the literature. The experimental set-up consisted of two mesophilic (36±1ºC lab-scale AFBRs (R1 and R2 loaded with sand as inert support for biofilm development. The reactor start-up policy was based on gradual increments in the organic loading rate (OLR, over a four month period. Step-type disturbances were applied on the inlet (glucose and acetic acid substrate concentration (chemical oxygen demand (COD from 0.85 to 2.66 g L-1 and on the feed flow rate (from 3.2 up to 6.0 L d-1 considering the maximum efficiency as the reactor loading rate switching. The predicted and measured responses of the total and soluble COD, volatile fatty acid (VFA concentrations, biogas production rate and pH were investigated. Regarding hydrodynamic and fluidization aspects, variations of the bed expansion due to disturbances in the inlet flow rate and the biofilm growth were measured. As rate coefficients for the biofilm detachment model, empirical values of 3.73⋅10(4 and 0.75⋅10(4 s² kg-1 m-1 for R1 and R2, respectively, were estimated.

  4. PRELIMINARY PHYTOCHEMICAL INVESTIGATION AND THIN LAYER CHROMATOGRAPHY OF RHEUM EMODI

    OpenAIRE

    Mir Ashfaq Ahmad; K. W. Shah; Showkat Ahmad Wani

    2012-01-01

    Preliminary phytochemical investigation of aqueous and methanolic rhizome extracts of Rheum emodi followed by their TLC profiling were carried out. Phytochemical analysis reveals the presence of diverse groups of phytoconstituents in two different extracts (aqueous and methanolic rhizome extracts). Chemical constituents also show different Rf values in two different solvent systems.

  5. Theoretical investigation on shocklets in compressible boundary layers

    Institute of Scientific and Technical Information of China (English)

    袁湘江; 刘智勇; 沈洁; 李国良

    2014-01-01

    By the shock relationships, the wavy characteristics and the forming condi-tions of a shock wave are analyzed. The wavy characteristics of an Euler system are stud-ied theoretically. The present research focuses on the wavy characteristics of Tollmien-Schlichting (T-S) waves, the excitation conditions of shocklets in compressible boundary layers, and the viscous effect on shock. The possibility of existence of shocklets in the compressible boundary layer and the physical mechanism of formation are theoretically interpreted.

  6. Theoretical repeatability assessment without repetitive measurements in gradient high-performance liquid chromatography.

    Science.gov (United States)

    Kotani, Akira; Tsutsumi, Risa; Shoji, Asaki; Hayashi, Yuzuru; Kusu, Fumiyo; Yamamoto, Kazuhiro; Hakamata, Hideki

    2016-07-01

    This paper puts forward a time and material-saving method for evaluating the repeatability of area measurements in gradient HPLC with UV detection (HPLC-UV), based on the function of mutual information (FUMI) theory which can theoretically provide the measurement standard deviation (SD) and detection limits through the stochastic properties of baseline noise with no recourse to repetitive measurements of real samples. The chromatographic determination of terbinafine hydrochloride and enalapril maleate is taken as an example. The best choice of the number of noise data points, inevitable for the theoretical evaluation, is shown to be 512 data points (10.24s at 50 point/s sampling rate of an A/D converter). Coupled with the relative SD (RSD) of sample injection variability in the instrument used, the theoretical evaluation is proved to give identical values of area measurement RSDs to those estimated by the usual repetitive method (n=6) over a wide concentration range of the analytes within the 95% confidence intervals of the latter RSD. The FUMI theory is not a statistical one, but the "statistical" reliability of its SD estimates (n=1) is observed to be as high as that attained by thirty-one measurements of the same samples (n=31). PMID:27266336

  7. Silicene: a review of recent experimental and theoretical investigations

    International Nuclear Information System (INIS)

    Silicene is the silicon counterpart of graphene, i.e. it consists in a single layer of Si atoms with a hexagonal arrangement. We present a review of recent theoretical and experimental works on this novel two dimensional material. We discuss first the structural, electronic and vibrational properties of free-standing silicene, as predicted from first-principles calculations. We next review theoretical studies on the interaction of silicene with different substrates. The growth and experimental characterization of silicene on Ag(1 1 1) is next discussed, providing insights into the different phases or atomic arrangements of silicene observed on this metallic surface, as well as on its electronic structure. Recent experimental findings about the likely formation of hexagonal Si nanosheets on MoS2 are also highlighted. (topical review)

  8. Theoretical and experimental investigations of stochastic boundaries in tokamaks

    International Nuclear Information System (INIS)

    The physics of stochastic boundaries are reviewed. The stochastic properties of magnetic field lines are recalled and related to the spectrum of the radial magnetic perturbation. The stochastic region, referred to as the divertor volume, is shown to be bounded to the edge plasma. Theoretical predictions for the transport of energy, current and particles in the divertor volume are analysed for both the laminar and ergodic regimes. (K.A.)

  9. Experimental and theoretical investigation of direct frequency comb spectroscopy

    OpenAIRE

    Peters, Elisabeth

    2011-01-01

    This thesis reports on theoretical and experimental examination of two-photon direct frequency comb spectroscopy (DFCS) using atomic two-level systems. This method is a very promising tool to extend optical spectroscopy into the short wavelength region where only few cw laser sources exist. The high peak intensities of pulsed lasers facilitate efficient nonlinear conversion into frequency regions which are so far unexplored, for example by high harmonic generation (HHG). DFCS is based on...

  10. Investigations in Experimental and Theoretical High Energy Physics

    Energy Technology Data Exchange (ETDEWEB)

    Krennrich, Frank [Iowa State University

    2013-07-29

    We report on the work done under DOE grant DE-FG02-01ER41155. The experimental tasks have ongoing efforts at CERN (ATLAS), the Whipple observatory (VERITAS) and R&D work on dual readout calorimetry and neutrino-less double beta decay. The theoretical task emphasizes the weak interaction and in particular CP violation and neutrino physics. The detailed descriptions of the final report on each project are given under the appropriate task section of this report.

  11. Experimental and theoretical investigation of shock waves in ventilation systems

    International Nuclear Information System (INIS)

    The passage of shock-waves through a model ventilation system which includes two rooms, a blower, a HEPA filter and a damper, all connected by 30cm diameter ducts was studied experimentally and theoretically. A computer code was utilized which treated the three-dimensional effects as the shock progressed through changes of area. Several different levels of shock overpressure were examined. Good correlation between experimental and computer results was obtained. (author)

  12. Theoretical evaluation of peak capacity improvements by use of liquid chromatography combined with drift tube ion mobility-mass spectrometry.

    Science.gov (United States)

    Causon, Tim J; Hann, Stephan

    2015-10-16

    In the domain of liquid phase separations, the quality of separation obtainable is most readily gauged by consideration of classical chromatographic peak capacity theory. Column-based multidimensional strategies for liquid chromatography remain the most attractive and practical route for increasing the number of spatially resolved components in order to reduce stress on necessary mass spectrometric detection. However, the stress placed on a chromatographic separation step as a second dimension in a comprehensive online methodology (i.e. online LC×LC) is rather high. As an alternative to online LC×LC combinations, coupling of HPLC with ion mobility spectrometry hyphenated to mass spectrometry (IMS-MS) has emerged as an attractive approach to permit comprehensive sampling of first dimension chromatographic peaks and subsequent introduction to an orthogonal IMS separation prior to measurement of ions by a mass spectrometer. In the present work, utilization of classical peak capacity and ion mobility theory allows theoretical assessment of the potential of two- (LC×IMS-MS) or even three-dimensional (LC×LC×IMS-MS) experimental setups to enhance peak capacity and, therefore, the number of correctly annotated features within the framework of complex, non-targeted analysis problems frequently addressed using HPLC-MS strategies. Theoretical calculations indicate that newly-available drift tube IMS-MS instrumentation can yield peak capacities of between 10 and 40 using nitrogen drift gas for typical non-targeted metabolomic, lipidomic and proteomic applications according to the expected reduced mobilities of components in the respective samples. Theoretically, this approach can significantly improve the overall peak capacity of conventional HPLC-(MS) methodologies to in excess of 10(4) depending upon the column length and gradient time employed. A more elaborate combination of LC×LC×IMS-MS would improve the ion suppression limitation and possibly allow access to

  13. Theoretical investigation on the Schelling's critical neighborhood demand

    CERN Document Server

    Shin, Jae Kyun

    2014-01-01

    We derived the critical neighborhood demand in the Schelling's segregation model by studying the conditions for which a chain reaction of migrations of unsatisfied agents occurs. The essence of Schelling dynamics was approximated in two simplified models: (1) a random walk model for the initial stage of the migrations to illustrate the power-law behavior of chain reaction lengths under critical conditions, and (2) a two-room model for the whole process to represent a non-spatial version of segregation dynamics in the Schelling model. Our theoretical results showed good agreements with numerical results obtained from agent-based simulations.

  14. Theoretical and experimental investigations of nano-Schottky contacts

    Science.gov (United States)

    Rezeq, Moh'd.; Eledlebi, Khouloud; Ismail, Mohammed; Dey, Ripon Kumar; Cui, Bo

    2016-07-01

    Formation of metal-semiconductor (M-S) contacts at sub-20 nanometer range is a key requirement for down-scaling of semiconductor devices. However, electrical measurements of M-S contacts at this scale have exhibited dramatic change in the current-voltage (I-V) characteristics compared to that of conventional (or planar) Schottky contacts. This change is actually attributed to the limited metal contact region where the transferred charge from the semiconductor into the metal is confined to a small surface area, which in turn results in an enhanced electric field at the nano-M-S interface. We here present detailed theoretical models to analyze the nano-M-S junctions at 10 nm contact range and then implement this analysis on the experimental data we conducted under these conditions. Both theoretical and experimental results demonstrate a significant effect of the contact size on the electronic structure of the M-S junctions and thus on the I-V characteristics. This effect is rather prominent when the size of the metal contact is substantially smaller than the width of conventional depletion region of the relevant planar M-S contacts.

  15. Combine experimental and theoretical investigation on an alkaloid-Dimethylisoborreverine

    Science.gov (United States)

    Singh, Swapnil; Singh, Harshita; Karthick, T.; Agarwal, Parag; Erande, Rohan D.; Dethe, Dattatraya H.; Tandon, Poonam

    2016-01-01

    A combined experimental (FT-IR, 1H and 13C NMR) and theoretical approach is used to study the structure and properties of antimalarial drug dimethylisoborreverine (DMIB). Conformational analysis, has been performed by plotting one dimensional potential energy curve that was computed using density functional theory (DFT) with B3LYP/6-31G method and predicted conformer A1 as the most stable conformer. After full geometry optimization, harmonic wavenumbers were computed for conformer A1 at the DFT/B3LYP/6-311++G(d,P) level. A complete vibrational assignment of all the vibrational modes have been performed on the bases of the potential energy distribution (PED) and theoretical results were found to be in good agreement with the observed data. To predict the solvent effect, the UV-Vis spectra were calculated in different solvents by polarizable continuum model using TD-DFT method. Molecular docking studies were performed to test the biological activity of the sample using SWISSDOCK web server and Hex 8.0.0 software. The molecular electrostatic potential (MESP) was plotted to identify the reactive sites of the molecule. Natural bond orbital (NBO) analysis was performed to get a deep insight of intramolecular charge transfer. Thermodynamical parameters were calculated to predict the direction of chemical reaction.

  16. Theoretical investigation of nonlinear properties of electrooptical chromophores

    Institute of Scientific and Technical Information of China (English)

    Zhou Yu-fang; Zhuang De-xin

    2004-01-01

    Organic electrooptical (EO) chromophores are now gaining more attention because the property of organic photorefrative (PR) materials could be controlled by doped EO chromophores. In this paper, nonlinear optical (NLO) properties of a new group of organic electrooptical chromophores, synthesized recently in our laboratory, were elucidated theoretically with the quantum chemical density functional theory (DFT) and the intermediate neglect of differential overlap Hamilton and the configuration interaction (INDO/CI), as well as semiemperical Austin Model 1 (AM1) methods. The electronic transition intensity, dipole moment and the second- order polarizability were obtained. The results show this group of chrormophores possess appropriate optical absorption property and good electrooptical property and optical activity. The second-order polarizabilities βare as large as the order of 10-29 to 10-28 ESU, indicating the promising applications in the future. The physical mechanism of NLO is discussed by means of molecular orbital and electronic charge distribution.

  17. Opacity Measurement and Theoretical Investigation of Hot Silicon Plasma

    Science.gov (United States)

    Xiong, Gang; Yang, Jiamin; Zhang, Jiyan; Hu, Zhimin; Zhao, Yang; Qing, Bo; Yang, Guohong; Wei, Minxi; Yi, Rongqing; Song, Tianming; Li, Hang; Yuan, Zheng; Lv, Min; Meng, Xujun; Xu, Yan; Wu, Zeqing; Yan, Jun

    2016-01-01

    We report on opacity measurements of a silicon (Si) plasma at a temperature of (72 ± 5) eV and a density of (6.0 ± 1.2) mg cm-3 in the photon energy range of 1790-1880 eV. A 23 μg cm-2 Si foil tamped by 50 μg cm-2 CH layers on each side was heated to a hot-dense plasma state by X-ray radiation emitted from a D-shaped gold cavity that was irradiated by intense lasers. Absorption lines of 1s - 2p transitions of Si xiii to Si ix ions have been measured using point-projection spectroscopy. The transmission spectrum of the silicon plasma was determined by comparing the light passing through the plasma to the light from the same shot passing by the plasma. The density of the Si plasma was determined experimentally by side-on radiography and the temperature was estimated from the radiation flux data. Radiative hydrodynamic simulations were performed to obtain the temporal evolutions of the density and temperature of the Si plasma. The experimentally obtained transmission spectra of the Si sample plasma have been reproduced using a detailed term account model with the local thermodynamic equilibrium approximation. The energy levels, oscillator strengths and photoionization cross-sections used in the calculation were generated by the flexible atomic code. The experimental transmission spectrum was compared with the theoretical calculation and good agreement was found. The present experimental spectrum and theoretical calculation were also compared with the new opacities available in the Los Alamos OPLIB database.

  18. Theoretical and experimental investigation of methanol combustion under constant volume

    Energy Technology Data Exchange (ETDEWEB)

    Tatem, P.A.F.

    1984-01-01

    This work advances the area of zone modeling through the development of a five-zone theoretical model with time-incrementing capabilities to predict the results of burning liquid pool methanol fires in a gastight enclosure. The model consists of a liquid fuel bed, a developed flame above the fuel bed, a plume sitting on top of the flame, the enclosure walls, and an ambient gaseous medium existing between the enclosure walls and flame-plume boundaries. The model assumes chemical equilibrium to determine the energy available from the combusting fuel, and temperature-dependent equilibrium concentrations of the combustion products. Once the available energy has been dictated by the chemical equilibrium, the energy feedback occurring within each defined zone makes possible the prediction of the temperatures (ambient gas, flame, and plume), the mass evaporation rate of the fuel, and the total pressure and oxygen concentration within the enclosure. The physical effects of the oxygen concentration on a confined methanol fire were well established in this work through a comparison of the results from the enclosed model with model results from the same fire in the open.

  19. Theoretical investigation of the thermodynamic properties of metallic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Vu Van [Vietnam Education Publishing House, 81 Tran Hung Dao, Hanoi (Viet Nam); Phuong, Duong Dai [Hanoi National University of Education, 136 Xuan Thuy, Hanoi (Viet Nam); Hoa, Nguyen Thi [University of Transport and Communications, Lang Thuong, Dong Da, Hanoi (Viet Nam); Hieu, Ho Khac, E-mail: hieuhk@duytan.edu.vn [Institute of Research and Development, Duy Tan University, K7/25 Quang Trung, Danang (Viet Nam)

    2015-05-29

    The thermodynamic properties of metallic thin films with face-centered cubic structure at ambient conditions were investigated using the statistical moment method including the anharmonicity effects of thermal lattice vibrations. The analytical expressions of Helmholtz free energy, lattice parameter, linear thermal expansion coefficient, specific heats at the constant volume and constant pressure were derived in terms of the power moments of the atomic displacements. Numerical calculations of thermodynamic properties have been performed for Au and Al thin films and compared with those of bulk metals. This research proposes that thermodynamic quantities of thin films approach the values of bulk when the thickness of thin film is about 70 nm. - Highlights: • Thermodynamic properties of thin films were investigated using the moment method. • Expressions of Helmholtz energy, expansion coefficient, specific heats were derived. • Calculations for Au, Al thin films were performed and compared with those of bulks.

  20. Theoretical investigation of the thermodynamic properties of metallic thin films

    International Nuclear Information System (INIS)

    The thermodynamic properties of metallic thin films with face-centered cubic structure at ambient conditions were investigated using the statistical moment method including the anharmonicity effects of thermal lattice vibrations. The analytical expressions of Helmholtz free energy, lattice parameter, linear thermal expansion coefficient, specific heats at the constant volume and constant pressure were derived in terms of the power moments of the atomic displacements. Numerical calculations of thermodynamic properties have been performed for Au and Al thin films and compared with those of bulk metals. This research proposes that thermodynamic quantities of thin films approach the values of bulk when the thickness of thin film is about 70 nm. - Highlights: • Thermodynamic properties of thin films were investigated using the moment method. • Expressions of Helmholtz energy, expansion coefficient, specific heats were derived. • Calculations for Au, Al thin films were performed and compared with those of bulks

  1. Experimental and Theoretical Status of Borromean Halo Nuclei Structure Investigation

    Science.gov (United States)

    Petrascu, Marius

    2006-08-01

    An introduction to the work performed in pre-emission of neutrons from 11Li halo nuclei will be presented. The standing present problems in the investigation of the structure of Borromean halo nuclei by means of the Cnn correlation function are outlined. An investigation of the target screening effect on the pre-emission of halo neutrons will be briefly described. It is shown that due to the diminishing of the screening effect the yield of neutron pair pre-emission is expected to be much larger in the case of 12C than in the case of Si target. It is shown that a new experiment on l2C target will allow to solve the standing problems of Cnn and also to test experimentally a recent new theory of Cnn [10 ].

  2. Theoretical investigation of OCN− adsorption onto boron nitride nanotubes

    International Nuclear Information System (INIS)

    Highlights: ► Adsorption behavior of OCN− on (6, 0) and (8, 0) BNNTs based on density functional theory. ► OCN− is strongly bound to BNNTs in corresponding configurations. ► The effect of the OCN− adsorption on the geometries and electronic properties of related BNNTs is investigated. ► BNNTs is suggested as superior sensor for OCN− comparing with CNTs. - Abstract: First-principles calculations based on density functional theory (DFT) method are used to investigate the adsorption properties of OCN− on H-capped zigzag and armchair single-walled BN nanotubes (BNNTs). The results indicate that OCN− is strongly bound to the outer surface of zigzag (6, 0) BNNTs in comparison with armchair (5, 5) BNNT. Binding energy and equilibrium distance corresponding to the most stable configuration are found to be −486.79 kJ mol−1 and 1.526 Å, respectively being typical for the chemisorptions. Energy gap, dipole moment, natural atomic orbital occupancies and global indices for most stable configuration are calculated. Furthermore, the effect of the OCN− adsorption on the geometries and electronic properties of related BNNT is also studied. The calculated density of states (DOS) reveals that there is a significant orbital hybridization between two species in adsorption process being an evidence of strong interaction. Therefore, one can conclude that BNNTs play an important role as suitable sensor.

  3. Perturbative series expansions theoretical aspects and numerical investigations

    CERN Document Server

    Biasco, L

    2004-01-01

    Perturbation theory is introduced by means of models borrowed from Celestial Mechanics, namely the two-body and three-body problems. Such models allow to introduce in a simple way the concepts of integrable and nearly-integrable systems, which can be conveniently investigated using Hamiltonian formalism. After discussing the problem of the convergence of the Lindstedt series, we introduce the basic notions of KAM theory, which allows (under quite general assumptions) to state the persistence of invariant tori. The value at which such surfaces break-down can be determined by means of numerical algorithms. Among the others, we review three methods to which we refer as Greene, Pade' and Lyapunov. We present some concrete applications to discrete models of the three different techniques, in order to provide complementary information about the break-down of invariant tori.

  4. Experimental and theoretical investigations of falling film evaporation

    Science.gov (United States)

    Pehlivan, Hüseyin; Özdemir, Mustafa

    2012-06-01

    In this study, a mathematical model was developed for falling film evaporation in vacuum using heat transfer relations. An experimental device was designed. experimental set-up which was used was equipped with a triangular weir distribution device and it had the ability to record data up to 3 m. Experiments were performed in a single-effect process with sucrose-water solution varying from 3 to 20% concentration rate of sucrose and we used a vertical tube evaporator with the dimensions of laboratory scale. The model that was developed considers convection, shear stress, viscosity and conjugate heat transfer while most of the previous works ignored these factors. The main factors influencing the heat transfer mechanism performance of the unit were investigated and analyzed. We concluded that the experimental studies are verified by the developed model. Furthermore, it was also concluded that, the heat transfer is affected by the mass flow rate, sucrose concentration rate in solution, film thickness and pressure.

  5. A theoretical investigation of the (0001) covellite surfaces

    International Nuclear Information System (INIS)

    We report on the properties of the (0001) covellites surfaces, which we investigate by periodic slab density functional theory calculations. The absolute surface energies have been computed for all bulk terminations, showing that surfaces terminated by the flat CuS layer are associated with the lowest surface energy. Cleavage is predicted to occur across the [0001] interlayer Cu–S bond. The surfaces obtained by lowest energy cleavage are analyzed in terms of the atomic vertical relaxation, workfunction, and surface band structure. Our study predicts the presence of a shallow pz-derived surface state located 0.26 eV below the Fermi level, which is set to play an important role in the surface reactivity of covellite

  6. A theoretical investigation of the (0001) covellite surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gaspari, Roberto, E-mail: roberto.gaspari@iit.it [D3-Computation, Istituto Italiano di Tecnologia, via Morego 30, Genova 16163 (Italy); Manna, Liberato [Department of Nanochemistry, Istituto Italiano di Tecnologia, via Morego 30, Genova 16163 (Italy); Cavalli, Andrea [D3-Computation, Istituto Italiano di Tecnologia, via Morego 30, Genova 16163 (Italy); Department of Pharmacy and Biotechnology, University of Bologna, via Belmeloro 6, I-40126 Bologna (Italy)

    2014-07-28

    We report on the properties of the (0001) covellites surfaces, which we investigate by periodic slab density functional theory calculations. The absolute surface energies have been computed for all bulk terminations, showing that surfaces terminated by the flat CuS layer are associated with the lowest surface energy. Cleavage is predicted to occur across the [0001] interlayer Cu–S bond. The surfaces obtained by lowest energy cleavage are analyzed in terms of the atomic vertical relaxation, workfunction, and surface band structure. Our study predicts the presence of a shallow p{sub z}-derived surface state located 0.26 eV below the Fermi level, which is set to play an important role in the surface reactivity of covellite.

  7. Theoretical investigations of two Si-based spintronic materials

    International Nuclear Information System (INIS)

    Two Si-based spintronic materials, a Mn-Si digital ferromagnetic heterostructure ((delta)-layer of Mn doped in Si) with defects and dilutely doped MnxSi1-x alloy are investigated using a density-functional based approach. We model the heterostructure and alloy with a supercell of 64 atoms and examine several configurations of the Mn atoms. We find that 25% substitutional defects without vacancies in the (delta) layer diminishes half metallicity of the DFH substantially. For the alloy, the magnetic moment M ranges from 1.0-9.0 μB/unit-cell depending on impurity configuration and concentration. Mn impurities introduce a narrow band of localized states near EF. These alloys are not half metals though their moments are integer. We explain the substantially different magnetic moments

  8. Theoretical investigation of spectroscopic properties of W25+

    International Nuclear Information System (INIS)

    Energy levels and emission spectra of W25+ ion have been studied by performing the large-scale relativistic configuration interaction calculations. Configuration interaction strength is used to determine the configurations exhibiting the largest influence on the 4f3, 4d94f4, 4f25s, 4f25p, 4f25d, 4f25f, 4f25g, and 4f26g configuration energies. It is shown that correlation effects are crucial for 4f25s→4f3 transition which in a single-configuration approach occurs due to the weak electric octupole transitions. As well, the correlation effects affect 4f25d→4f3 transitions by increasing transition probabilities by an order. The corona model has been used to estimate the contribution of various transitions to the emission in a low-density electron beam ion trap (EBIT) plasma. Modeling in 10–30 nm wavelength range produces lines which do not form emission bands and can be observed in EBIT plasma. - Highlights: • Energy levels and radiative transition probabilities are studied for the W25+ ion. • Correlation effects are investigated for main configurations of the ion. • The corona model is used to find lines in spectra

  9. Theoretical investigations on fluorene-pyridines as electroactive sensor molecules

    International Nuclear Information System (INIS)

    Full text: Organic semiconducting oligomers and polymers are promising candidates for chemical sensing applications. In this work, sensor molecules comprising a sequence of para- and meta-linked fluorene- and pyridine- units are studied. Spectroscopic investigations show that upon protonation of the pyridine rings (i.e., when adding acids to the solutions), one observes a distinct red-shift of the absorption and emission maxima by approximately 0.5 eV. The fact that the polymers are highly emissive in both, the non protonated as well as protonated state makes them particularly interesting candidates for ratio metric sensors based on organic semiconductors. To rationalize the observed behaviour, we calculate the geometric and electronic structures of the relevant molecules at various stages of protonation using both semiempirical as well as density functional theory based methods. In general, we obtain good agreement between theory and experiment and excited state localization is found to play a crucial role in the sensing process. In practice, one can expect the interaction between the proton and the nitrogen of the pyridine unit to be modulated by interaction with the counter-ion as well as by screening through solvent molecules. These effects are accounted for in calculations on smaller model systems. (author)

  10. Theoretical and experimental investigation of cappillary electrolysis system

    International Nuclear Information System (INIS)

    In a fusion reactor environment, it is expected that highly tritiated water will be formed when tritium is extracted from the blanket as well as during the plasma exhaust purification process. As a consequence, the recovery of elemental tritium from its oxides is an essentrial step before recycling the fuel to the reactor. Among different basic processes that can be used for this purpose, electrolysis appears to be very promising. Therefore, SCK/CEN has developed a small dedicated cell designed to decompose 100 ml/day of pure DTO or HTO. At the present project stage, a prototype cell is available and the device has been successfully tested with light water during several thousands of hours. In the orginal concept, the liquid inventory is limited to the vertical porous gas separator. Capillarity is used as a driving force to feed the cell to avoid the use of a pump. This fact turns out to have a considerable influence on the behaviour of the electrolytic system. This particular behaviour has been theorectically investigated with the aim to allow a better basic understanding of the capillary electrolysis. A deterministic model has been developed for its purpose. The mathematical equations show clearly that the electrolyte tends to accumulate at the top of the gas separator. An equilibrium state can be reached only if sufficiently large amounts of electrolyte can flow back towards the bottom of the gas separator. This counter-flow has been taken into account by introducing a single general diffusion coefficient into the model. In a second phase, systematic experimental runs have been carried out with mock-up cells. A statistical treatment based on the maximum likelihood estimation algorithm allowed to compute the best values for the diffusion coefficient and to validate the model. Finally, acceptabel ranges of the independent varialbles have been defined and all the subsequent experimental runs have been performed without stability problems. (author). 12 refs.; 5 figs

  11. Theoretical investigation of second hyperpolarizability of trans-polyacetylene: Comparison between experimental and theoretical results for small oligomers.

    Science.gov (United States)

    de Andrade, Ageo Meier; Inacio, Patrícia Loren; Camilo, Alexandre

    2015-12-28

    The development of new conductive polymers nowadays is one of the most important technological areas in materials design. Computational investigation of desired properties in conductive polymers could save financial resources and time, but it is important to choose the methodology that produces good results comparing to experimental results. To verify the prediction of second hyperpolarizability (γ) in oligomers of Trans-Polyacetylene (TPA) by theoretical calculations, a series of semi-empirical, Hartree-Fock (HF), and Density Functional Theory (DFT) calculations were performed and analysed through linear fitting statistical analysis to investigate the accuracy of such theoretical predictions in comparison to the experimental ones. The results showed that HF and DFT methodologies do not describe γ with good accuracy, but the use of diffuse and polarizability functions in HF methodology provided better results than 3-21G and 6-31G functions. It was concluded that RM1 methodology better agrees with γ experimental results for TPA oligomers, and linear fitting statistical analysis is a useful tool to compare experimental and theoretical results. PMID:26723710

  12. Theoretical investigation of second hyperpolarizability of trans-polyacetylene: Comparison between experimental and theoretical results for small oligomers

    Science.gov (United States)

    Andrade, Ageo Meier de; Inacio, Patrícia Loren; Camilo, Alexandre

    2015-12-01

    The development of new conductive polymers nowadays is one of the most important technological areas in materials design. Computational investigation of desired properties in conductive polymers could save financial resources and time, but it is important to choose the methodology that produces good results comparing to experimental results. To verify the prediction of second hyperpolarizability (γ) in oligomers of Trans-Polyacetylene (TPA) by theoretical calculations, a series of semi-empirical, Hartree-Fock (HF), and Density Functional Theory (DFT) calculations were performed and analysed through linear fitting statistical analysis to investigate the accuracy of such theoretical predictions in comparison to the experimental ones. The results showed that HF and DFT methodologies do not describe γ with good accuracy, but the use of diffuse and polarizability functions in HF methodology provided better results than 3-21G and 6-31G functions. It was concluded that RM1 methodology better agrees with γ experimental results for TPA oligomers, and linear fitting statistical analysis is a useful tool to compare experimental and theoretical results.

  13. Preliminary phytochemical investigation and thin layer chromatography profiling of sequential extracts of Moringa oleifera pods

    Directory of Open Access Journals (Sweden)

    Veena Sharma

    2013-01-01

    Full Text Available Context: Moringa oleifera Lam (Moringaceae is a highly valued plant, distributed in many countries of the tropics and subtropics. It has an impressive range of medicinal uses with high nutritional value. Aim: The present study, primarily aims to carry out a preliminary phytochemical screening so as to detect the major class of compounds present in M. oleifera and to perform thin layer chromatography (TLC profiling of all sequential extracts. Materials and Methods: Phytochemical analysis was performed by various qualitative methods and TLC profiling was carried out using various solvent system of varying polarity. Results and Conclusions: Qualitative phytochemical analysis reflects the presence of phenolics, triterpenoids, cardiac glycosides, steroid, alkaloids and saponin in the plant extract. TLC profiling of the M. oleifera pods was carried out using sequential extracts of petroleum ether, benzene, petroleum ether, benzene, chloroform, ethyl acetate, ethanol and water respectively. The results obtained in the present investigation indicated M. oleifera pods as a rich source of natural antioxidants.

  14. Theoretical model and experimental investigation of current density boundary condition for welding arc study

    OpenAIRE

    Boutaghane, A.; Bouhadef, K.; Valensi, F.; Pellerin, S.; Benkedda, Y.

    2011-01-01

    Abstract This paper presents results of theoretical and experimental investigation of the welding arc in Gas Tungsten Arc Welding (GTAW) and Gas Metal Arc Welding (GMAW) processes. A theoretical model consisting in simultaneous resolution of the set of conservation equations for mass, momentum, energy and current, Ohm's law and Maxwell equation is used to predict temperatures and current density distribution in argon welding arcs. A current density profile h...

  15. Male-to-Female and Female-to-Male Transsexualism - A Theoretical Investigation

    OpenAIRE

    Volkova, Anna

    2015-01-01

    This project contains a theoretical investigation of MtF and FtM transsexualism. The theoretical point of departure is Harry Benjamin’s book The Transsexual Phenomenon. The former provides a general overview of the struggles a male transsexual faces in his life. Subsequently, the projects proceeds by giving a detailed account of Blanchard’s Theory of Autogynephilia. Using Lawrence’s and Blanchard’s research, the term autogynephilia is described and discussed. In the investigati...

  16. Cromatografia unificada Unified chromatography

    Directory of Open Access Journals (Sweden)

    Carin von Mühlen

    2004-10-01

    Full Text Available The scope of this study encompasses an overview of the principles of unified chromatography as well as the principles of chromatographic techniques as applied to unified systems, which include gas chromatography, liquid chromatography, supercritical fluid chromatography, high temperature and high pressure liquid chromatography, micro-liquid chromatography, enhanced fluidity chromatography, and solvating gas chromatography. Theoretical considerations and individual instrumental parameters such as mobile phase, sample introduction system, columns, and detection system are also discussed. Future applications of this separation approach are discussed.

  17. Theoretical study of closed-loop recycling liquid-liquid chromatography and experimental verification of the theory.

    Science.gov (United States)

    Kostanyan, Artak E; Erastov, Andrey A

    2016-09-01

    The non-ideal recycling equilibrium-cell model including the effects of extra-column dispersion is used to simulate and analyze closed-loop recycling counter-current chromatography (CLR CCC). Previously, the operating scheme with the detector located before the column was considered. In this study, analysis of the process is carried out for a more realistic and practical scheme with the detector located immediately after the column. Peak equation for individual cycles and equations describing the transport of single peaks and complex chromatograms inside the recycling closed-loop, as well as equations for the resolution between single solute peaks of the neighboring cycles, for the resolution of peaks in the recycling chromatogram and for the resolution between the chromatograms of the neighboring cycles are presented. It is shown that, unlike conventional chromatography, increasing of the extra-column volume (the recycling line length) may allow a better separation of the components in CLR chromatography. For the experimental verification of the theory, aspirin, caffeine, coumarin and the solvent system hexane/ethyl acetate/ethanol/water (1:1:1:1) were used. Comparison of experimental and simulated processes of recycling and distribution of the solutes in the closed-loop demonstrated a good agreement between theory and experiment. PMID:27492599

  18. Investigating the Retention Mechanisms of Liquid Chromatography Using Solid-Phase Extraction Cartridges

    Science.gov (United States)

    O'Donnell, Mary E.; Musial, Beata A.; Bretz, Stacey Lowery; Danielson, Neil D.; Ca, Diep

    2009-01-01

    Liquid chromatography (LC) experiments for the undergraduate analytical laboratory course often illustrate the application of reversed-phase LC to solve a separation problem, but rarely compare LC retention mechanisms. In addition, a high-performance liquid chromatography instrument may be beyond what some small colleges can purchase. Solid-phase…

  19. Stability of an oscillating tip in Non-Contact Atomic Force Microscopy: theoretical and numerical investigations

    CERN Document Server

    Couturier, G; Boisgard, R; Aimé, J P; Nony, Laurent; Boisgard, Rodolphe; Aim\\'{e}, Jean-Pierre

    2002-01-01

    This paper is a theoretical and a numerical investigation of the stability of a tip-cantilever system used in Non-Contact Atomic Force Microscopy (NC-AFM) when it oscillates close to a surface. No additional dissipative force is considered. The theoretical approach is based on a variationnal method exploiting a coarse grained operation that gives the temporal dependence of the nonlinear coupled equations of motion in amplitude and phase of the oscillator. Stability criterions for the resonance peak are deduced and predict a stable behavior of the oscillator in the vicinity of the resonance. The numerical approach is based on results obtained with a virtual NC-AFM developped in our group. The effect of the size of the stable domain in phase is investigated. These results are in particularly good agreement with the theoretical predictions. Also they show the influence of the phase shifter in the feedback loop and the way it can affect the damping signal.

  20. 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...

  1. Theoretical investigation of van der Waals forces between solid surfaces at nanoscales

    NARCIS (Netherlands)

    Kudryavtsev, Y.V.; Gelinck, E.R.M.; Fischer, H.R.

    2009-01-01

    A theoretical investigation of van der Waals forces acting between two solid silicon surfaces at separations from zero to approximately 20 nm is presented. We focused our efforts on the analysis of different factors that can cause deviations from the classical pressure-distance dependence p ∼ 1/D3.

  2. Experimental and Theoretical Investigation of Subnanosecond Pulse Propagation in Graded Index Fibers

    DEFF Research Database (Denmark)

    Nicolaisen, Ejner; Hansen, J. J. Ramskov

    1977-01-01

    The propagation in a fibre which does not exhibit any mode coupling is investigated by varying the launching conditions. It is shown that for this fibre there exists a trade-off between dispersion and power coupling efficiency. The measurements are compared to theoretical calculations taking leaky...

  3. Structural investigations of neuromelanin by pyrolysis-gas chromatography/mass spectrometry

    International Nuclear Information System (INIS)

    Pyrolysis combined with gas chromatography and mass spectrometry (Py-GC/MS) was applied for structural investigations of the human substantia nigra neuromelanin. Using synthetic neuromelanins, we have demonstrated that Py-GC/MS is suitable for identification and differentiation of both eumelanin (dopamine-derived) and pheomelanin (cysteinyldopamine-derived) component of the pigment. Structural information on melanin monomers was inferred from their pyrolytic markers. When the human neuromelanin was subjected to pyrolysis, none of the heterocyclic, sulfur-containing markers of pheomelanin component was detected among the thermal degradation products. We have concluded that nigral pigment isolated from normal brain tissue does not contain benzothiazine-type monomers, and that cysteinyldopamine-originated units may be incorporated into the polymer in uncyclized form. The most abundant pyrolysis product was identified as limonene, which indicates that nigral pigment is tightly associated with an isoprenoid-type compound. Pyrolysis in the presence of the methylating reagent allowed identification of high levels of saturated and monounsaturated straight-chain C14-C18 fatty acid species chemically bound to the pigment macromolecule. (author)

  4. Theoretical investigation of radical species formed from L-α-alanine under gamma-irradiation

    International Nuclear Information System (INIS)

    Gamma-irradiated L-α-alanine used in EPR-coupled dosimetry has a complex EPR spectrum at room temperature. Changing the temperature or other conditions of the irradiated samples leads to varied EPR spectrum, i.e., some components disappear and/or new ones are formed. We used both molecular mechanics (MM+) and semiempirical (AM1) methods to perform a theoretical investigation of the seven radical species that have been experimentally detected. We established their order of priority in the given simulation conditions (at 0 K, in vacuo). The formation stages advanced for these long-lived radical species were characterized by a theoretical determination of the reaction enthalpies. (author)

  5. Investigation into the quantitative aspects of supercritical fluids as mobile phases for chromatography and extraction

    OpenAIRE

    Frazier, James Owen

    1990-01-01

    Supercritical fluids were introduced as mobile phases for chromatography and extractions in the early sixties. Over the past decade the technique has received increased attention, largely owing to the introduction of several commercial instruments and to the ease of adapting available commercial equipment for use in sfe and sfc. This dissertation examines the use of supercritical C02 as a mobile phase for chromatography and extraction. The first chapter explores the problems and provides bac...

  6. Thin-Layer Chromatography/Desorption Electrospray Ionization Mass Spectrometry: Investigation of Goldenseal Alkaloids

    Energy Technology Data Exchange (ETDEWEB)

    Van Berkel, Gary J [ORNL; Tomkins, Bruce A [ORNL; Kertesz, Vilmos [ORNL

    2007-01-01

    Desorption electrospray ionization mass spectrometry was investigated as a means to qualitatively identify and to quantify analytes directly from developed normal-phase thin layer chromatography plates. The atmospheric sampling capillary of a commercial ion trap mass spectrometer was extended to permit sampling and ionization of analytes in bands separated on intact TLC plates (up to 10 cm x 10 cm). A surface positioning software package and the appropriate hardware enabled computer-controlled surface scanning along the length of development lanes or at fixed RF value across the plates versus the stationary desorption electrospray emitter. Goldenseal (Hydrastis canadensis) and related alkaloids and commercial dietary supplements were used as standards and samples. Alkaloid standards and samples were spotted and separated on aluminum- or glass-backed plates using established literature methods. The mass spectral signal levels as a function of desorption spray solvent were investigated with acetonitrile proving superior to methanol. The detection levels (ca. 5 ng each or 14 -28 pmol) in mass spectral full scan mode were determined statistically from the calibration curves (2.5 - 100 pmol) for the standards berberine, palmatine and hydrastinine spotted as a mixture and separated on the plates. Qualitative screening of the major alkaloids present in six different over-the-counter "goldenseal" dietary supplements was accomplished by obtaining full scan mass spectra during surface scans along the development lane in the direction of increasing RF value. In one sample, alkaloids were detected that strongly suggested the presence of at least one additional herb undeclared on the product label. These same data indicated the misidentification of one of the alkaloids in the TLC literature. Quantities of the alkaloids present in two of the samples determined using the mass spectral data were in reasonable agreement with the label values indicating the quantitative ability of

  7. Theoretical investigations of electron conditions and elementary processes in heavy ions

    International Nuclear Information System (INIS)

    This is a progress report of the investigations by the atom and molecule theoretical study group with the grant-in-aid for the special project research ''Heavy ion science''. Heavy ion beams are now handled for researches in many laboratories in the world, and it is becoming possible to confirm the theoretical calculations because of the availability of experiments for heavy atoms. The feature of this theoretical study group is to develop the study of atomic and molecular structures and elementary processes on the basis of the exact calculations performed in many years so far. It can be said that the results of the studies made by the group have obtained credit with investigators in the world. The contents of the studies performed by the group members are introduced simply. Then the results of the group meetings are reported, and finally, the list of papers and their authors is recorded. Heavy ion science, when it is viewed from the standpoint of atomic physics, has its most significance in controlling the velocity of specific ions, causing the special reaction and observing it in detail. The amount of data is recently very enormous and diverse owing to the measurements of cross sections in various elementary processes together with the findings on the exciting state of atoms, and the possibilities as a field of theoretical activities are almost unlimited. (Wakatsuki, Y.)

  8. Experimental and theoretical investigation of high gradient acceleration. Progress report, February 1, 1992--January 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Wurtele, J.S.; Bekefi, G.; Chen, C.; Chen, S.C.; Temkin, R.J.

    1993-01-01

    This report contains a technical progress summary of the research conducted under the auspices of DOE Grant No. DE-AC02-91-ER40648, ``Experimental and Theoretical Investigations of High Gradient Acceleration``. This grant supports three research tasks: Task A consists of the design, fabrication and testing of a 17GHz RF photocathode gun, which can produce 2ps electron pulses with up to 1nC of charge at 2MeV energy and at a 1OHz repetition rate. Task B supports the testing of high gradient acceleration at 33GHz structure, and Task C comprises theoretical investigations, both in support of the experimental tasks and on critical physics issues for the development of high energy linear colliders.

  9. Solid state structural and theoretical investigations of a biologically active chalcone

    Science.gov (United States)

    Abbas, Asghar; Gökce, Halil; Bahceli, Semiha; Bolte, Michael; Naseer, Muhammad Moazzam

    2016-05-01

    The computational methods are presently emerging as an efficient and reliable tool for predicting structural properties of biologically important compounds. In the present manuscript, the solid state structural and theoretical investigations of a biologically active chalcone i-e (E)-3-(4-(hexyloxy)phenyl)-1-phenylprop-2-en-1-one (6c) have been reported. The solid state structure of 6c was measured by X-ray crystallographic technique whereas the optimized molecular geometry, vibrational frequencies, the simulated UV-vis spectra (in gas and in methanol solvent), 1H and 13C NMR chemical shift (in gas and in chloroform solvent) values, HOMO-LUMO analysis, the molecular electrostatic potential (MEP) surface and thermodynamic parameters were calculated by using DFT/B3LYP method with 6-311++G(d,p) basis set in ground state. The results of the theoretical investigations were found to be in good agreement with experimental data.

  10. The physics and chemistry of dusty plasmas: A laboratory and theoretical investigation

    Science.gov (United States)

    Whipple, E. C.

    1986-01-01

    Theoretical work on dusty plasmas was conducted in three areas: collective effects in a dusty plasma, the role of dusty plasmas in cometary atmospheres, and the role of dusty plasmas in planetary atmospheres (particularly in the ring systems of the giant planets). Laboratory investigations consisted of studies of dust/plasma interactions and stimulated molecular excitation and infrared emission by charged dust grains. Also included is a list of current publications.

  11. Electron collisions with small esters: A joint experimental-theoretical investigation

    Science.gov (United States)

    de Souza, G. L. C.; da Silva, L. A.; de Sousa, W. J. C.; Sugohara, R. T.; Iga, I.; dos Santos, A. S.; Machado, L. E.; Homem, M. G. P.; Brescansin, L. M.; Lucchese, R. R.; Lee, M.-T.

    2016-03-01

    A theoretical and experimental investigation on elastic electron scattering by two small esters, namely, methyl formate and ethyl acetate, is reported. Experimental differential, integral, and momentum-transfer cross sections are given in the 30-1000 eV and 10∘-120∘ ranges. The relative-flow technique was used to determine such quantities. Particularly for methyl formate, a theoretical study was also carried out in the 1-500 eV range. A complex optical potential derived from a Hartree-Fock molecular wave function was used to represent the collision dynamics, whereas the Padé approximation was used to solve the scattering equations. In addition, calculations based on the framework of the independent-atom model (IAM) were also performed for both targets. In general, there is good agreement between our experimental data and the present theoretical results calculated using the Padé approximation. The theoretical results using the IAM also agree well with the experimental data at 200 eV and above. Moreover, for methyl formate, our calculations reveal a 2A'' (π*) resonance at about 3.0 eV and a σ*-type resonance centered at about 8.0 eV in the 2A' scattering channel. The π* resonance is also seen in other targets containing a carbonyl group.

  12. Theoretical and practical investigation of the electromagnetic radiation fields from the Sabborah radio broadcasting station

    International Nuclear Information System (INIS)

    This work has special importance as it aims at the investigation of the electromagnetic radiation from the Sabborah radio broadcasting station. The report includes general introduction to the physics of the electromagnetic fields and the biological effects of these fields and consequently its health effects. The bases of the recommended exposure limits according to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) have been discussed in addition to the theoretical and practical investigations. This report summarizes the results of this study and the final recommendations. (author)

  13. Theoretical and experimental investigation of biomass gasification process in a fixed bed gasifier

    International Nuclear Information System (INIS)

    This investigation concerns the process of air biomass gasification in a fixed bed gasifier. Theoretical equilibrium calculations and experimental investigation of the composition of syngas were carried out and compared with findings of other researchers. The influence of excess air ratio (λ) and parameters of biomass on the composition of syngas were investigated. A theoretical model is proposed, based on the equilibrium and thermodynamic balance of the gasification zone. The experimental investigation was carried out at a setup that consists of a gasifier connected by a pipe with a water boiler fired with coal (50 kWth). Syngas obtained in the gasifier is supplied into the coal firing zone of the boiler, and co-combusted with coal. The moisture content in biomass and excess air ratio of the gasification process are crucial parameters, determining the composition of syngas. Another important parameter is the kind of applied biomass. Despite similar compositions and dimensions of the two investigated feedstocks (wood pellets and oats husk pellets), compositions of syngas obtained in the case of these fuels were different. On the basis of tests it may be stated that oats husk pellets are not a suitable fuel for the purpose of gasification.

  14. A domain-theoretic investigation of posets of sub-sigma-algebras (extended abstract

    Directory of Open Access Journals (Sweden)

    Ingo Battenfeld

    2010-06-01

    Full Text Available Given a measurable space (X, M there is a (Galois connection between sub-sigma-algebras of M and equivalence relations on X. On the other hand equivalence relations on X are closely related to congruences on stochastic relations. In recent work, Doberkat has examined lattice properties of posets of congruences on a stochastic relation and motivated a domain-theoretic investigation of these ordered sets. Here we show that the posets of sub-sigma-algebras of a measurable space do not enjoy desired domain-theoretic properties and that our counterexamples can be applied to the set of smooth equivalence relations on an analytic space, thus giving a rather unsatisfactory answer to Doberkat's question.

  15. A domain-theoretic investigation of posets of sub-sigma-algebras (extended abstract)

    CERN Document Server

    Battenfeld, Ingo

    2010-01-01

    Given a measurable space (X, M) there is a (Galois) connection between sub-sigma-algebras of M and equivalence relations on X. On the other hand equivalence relations on X are closely related to congruences on stochastic relations. In recent work, Doberkat has examined lattice properties of posets of congruences on a stochastic relation and motivated a domain-theoretic investigation of these ordered sets. Here we show that the posets of sub-sigma-algebras of a measurable space do not enjoy desired domain-theoretic properties and that our counterexamples can be applied to the set of smooth equivalence relations on an analytic space, thus giving a rather unsatisfactory answer to Doberkat's question.

  16. Investigation of Practical and Theoretical Accuracy of Wireless Indoor Positioning System Ubisense

    Science.gov (United States)

    Woźniak, Marek; Odziemczyk, Waldemar; Nagórski, Kamil

    2013-12-01

    This paper presents the accuracy investigation results and functionality of Ubisense RTLS positioning system. Three kinds of studies were conducted: test of calibration accuracy, analysis of theoretical accuracy of the coordinates determination as well as accuracy measurements in field conditions. Test of calibration accuracy was made with several different geometric constellation of reference points (tag positions). We determined changes of orientation parameters of receivers and disturbance of positioning points coordinates against chosen reference points constellations. Analysis of theoretical accuracy was made for several receivers spatial positions and their orientations. It allowed to indicate favourable and unfavourable measurement area considering accuracy and reliability. Real positioning accuracy of the Ubisense system was determined by comparison with coordinates measured using precise tacheometer TCRP1201+. Results of conducted experiments and accuracy analysis of test measurement were presented in figures and diagrams.

  17. Theoretical investigation on peripheral ligands of oxygen-evolving center in photosystem II

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The interaction between the Mn-cluster and its peripheral ligands in oxygen-evolving center is still unclear. Theoretical investigation on the coordination of histidine, H2O, and Cl to Mn2O2 units in OEC is conducted. The following conclusions are obtained: (i) both histidine and H2O molecule, bound to the two Mn ions, respectively, are vertical to the Mn2O2 plane, and maintain a large distance; (ii) the two H2O molecules cannot bind to the same Mn2O2 unit. Based on Mn-cluster structure in OEC, we theoretically predict that two H2O molecules bind to the two Mn ions at the "C"-shaped open end in S0 state, while two His residues at the closed end. Cl ion can only terminally ligate at the open end. Individual valence for the four Mn ions in S0 state is assigned.

  18. Investigation of the concentration dependence of mass transfer coefficients in reversed-phase liquid chromatography.

    Science.gov (United States)

    Hao, Weiqiang; Wang, Junde; Zhang, Xiangmin

    2006-12-01

    In order to investigate the concentration dependence of mass transfer coefficients in RPLC, experimental breakthrough curves obtained by staircase frontal analysis (FA) were fitted to the simplified models such as multiplate (MP) model, equilibrium dispersive (ED) model, and transport model, and the sophisticated models such as lumped pore diffusion (POR) model and general rate (GR) model. The MP model was used to obtain the initial guesses of the parameters of the ED and the transport models. Then the best values were obtained by minimizing the differences between theoretical and experimental values with a nonlinear fitting procedure. The values of the parameters of the POR and the GR models can be calculated by using the expressions derived from the plate height equations, which was further validated by using the fitting method. It was found that the mass transfer coefficients would depend on the solute concentration. This can be ascribed to the surface diffusivity, which correlates with the concentration and is lumped into the mass transfer coefficients for both simplified and sophisticated models. PMID:17305235

  19. Investigating Solvent Purity Utilizing Comprehensive Gas Chromatography: A Study of Acetones

    Energy Technology Data Exchange (ETDEWEB)

    Wahl, Jon H.; Bolz, Cinnamon DH; Wahl, Karen L.

    2010-04-01

    Broad spectrum chemical analysis of trace level components is a continuing challenge for any analytical chemist. This challenge is further confounded when chemical impurities may be present in common organic solvents or when chemical artifacts may be formed, produced and introduced during an analytical procedure. Minimizing and understanding these chemical artifacts, is critical for trace level detection and is crucial for unambiguous analytical results. Comprehensive gas chromatography is an excellent analytical tool to help address these complex mixture challenges. This work examines the impurities present in various acetone sources utilizing comprehensive gas chromatography. This work highlights the extreme variability possible in solvent sources and hence the importance of understanding the impurities that may confound an analytical method or result.

  20. Purification of organic acids by chromatography with strong anionic resins: Investigation of uptake mechanisms.

    Science.gov (United States)

    Lemaire, Julien; Blanc, Claire-Line; Lutin, Florence; Théoleyre, Marc-André; Stambouli, Moncef; Pareau, Dominique

    2016-08-01

    Bio-based organic acids are promising renewable carbon sources for the chemical industry. However energy-consuming purification processes are used, like distillation or crystallization, to reach high purities required in some applications. That is why preparative chromatography was studied as an alternative separation technique. In a previous work dealing with the purification of lactic, succinic and citric acids, the Langmuir model was insufficient to explain the elution profiles obtained with a strong anionic resin. Consequently the Langmuir model was coupled with a usual ion-exchange model to take into account the retention of their conjugate bases (tailing and apparent delay observed with succinic and citric acids can be explained by the high affinity of succinate and citrate for resin cationic sites. The model was implemented in a preparative chromatography simulation program in order to optimize operating parameters of our pilot-scale ISMB unit (Improved Simulated Moving Bed). The comparison with experimental ISMB profiles was conclusive. PMID:27373374

  1. Investigation of Isotopic Abundance Ratio of Biofield Treated Phenol Derivatives Using Gas Chromatography-Mass Spectrometry

    OpenAIRE

    Trivedi, Mahendra Kumar

    2015-01-01

    Butylatedhydroxytoluene (BHT) and 4-methoxyphenol (4-MP) are phenol derivatives that are generally known for their antioxidant properties and depigmenting activities. The aim of this study was to evaluate the impact of biofield energy treatment on the isotopic abundance of BHT and 4-MP using gas chromatography-mass spectrometry (GC-MS). BHT and 4-MP samples were divided into two parts: control and treated. The control group remained untreated while the treated group was subjected to Mr. Trive...

  2. Theoretical model and experimental investigation of current density boundary condition for welding arc study

    Science.gov (United States)

    Boutaghane, A.; Bouhadef, K.; Valensi, F.; Pellerin, S.; Benkedda, Y.

    2011-04-01

    This paper presents results of theoretical and experimental investigation of the welding arc in Gas Tungsten Arc Welding (GTAW) and Gas Metal Arc Welding (GMAW) processes. A theoretical model consisting in simultaneous resolution of the set of conservation equations for mass, momentum, energy and current, Ohm's law and Maxwell equation is used to predict temperatures and current density distribution in argon welding arcs. A current density profile had to be assumed over the surface of the cathode as a boundary condition in order to make the theoretical calculations possible. In stationary GTAW process, this assumption leads to fair agreement with experimental results reported in literature with maximum arc temperatures of ~21 000 K. In contrast to the GTAW process, in GMAW process, the electrode is consumable and non-thermionic, and a realistic boundary condition of the current density is lacking. For establishing this crucial boundary condition which is the current density in the anode melting electrode, an original method is setup to enable the current density to be determined experimentally. High-speed camera (3000 images/s) is used to get geometrical dimensions of the welding wire used as anode. The total area of the melting anode covered by the arc plasma being determined, the current density at the anode surface can be calculated. For a 330 A arc, the current density at the melting anode surface is found to be of 5 × 107 A m-2 for a 1.2 mm diameter welding electrode.

  3. An Experimental and Theoretical Investigation of Micropiiting in Wind Turbine Gears and Bearings

    Energy Technology Data Exchange (ETDEWEB)

    Kahraman, Ahmet

    2012-03-28

    In this research study, the micro-pitting related contact failures of wind turbine gearbox components were investigated both experimentally and theoretically. On the experimental side, a twin-disk type test machine was used to simulate wind turbine transmission contacts in terms of their kinematic (rolling and sliding speeds), surface roughnesses, material parameters and lubricant conditions. A test matrix that represents the ranges of contact conditions of the wind turbine gear boxes was defined and executed to bring an empirical understanding to the micro-pitting problem in terms of key contact parameters and operating conditions. On the theoretical side, the first deterministic micro-pitting model based on a mixed elastohydrodynamic lubrication formulations and multi-axial near-surface crack initiation model was developed. This physics-based model includes actual instantaneous asperity contacts associated with real surface roughness profiles for predicting the onset of the micro-pit formation. The predictions from the theoretical model were compared to the experimental data for validation of the models. The close agreement between the model and measurements was demonstrated. With this, the proposed model can be deemed suitable for identifying the mechanisms leading to micro-pitting of gear and bearing surfaces of wind turbine gear boxes, including all key material, lubricant and surface engineering aspects of the problem, and providing solutions to these micro-pitting problems.

  4. Theoretical investigation of the forward phase-matched geometry for degenerate four-wave mixing spectroscopy

    International Nuclear Information System (INIS)

    We examine theoretically the degenerate four-wave mixing (DFWM) signal intensities and line shapes obtained with the forward phase-matched geometry in which all beams propagate in the same direction and compare the results to those of the phase-conjugate geometry with counterpropagating pump beams. To examine the forward phase-matched geometry, we modify a theoretical approach used previously to calculate phase-conjugate DFWM signal intensities. This theoretical approach, which involves numerical integration of the time-dependent density-matrix equations, is validated for the forward phase-matched geometry by comparison of our calculated line shapes to both a perturbative solution and to experimental data. This methodology is then used to compare the signal intensities and line shapes obtained with the forward phase-matched geometry and the phase-conjugate geometry in the perturbative (low laser power) and saturated (high laser power) regimes. In the perturbative regime the forward phase-matched signal exhibits less sensitivity to the Doppler linewidth. At pump laser intensities approximately equal to the saturation intensity the signal for the forward phase-matched geometry is stronger than that for the phase-conjugate geometry for primarily Doppler-broadened resonances, assuming the same probe volume for both geometries. These advantages warrant further investigations employing the forward phase-matched configuration for DFWM measurements of gas-phase species. copyright 1998 Optical Society of America

  5. Investigation of thermal properties of ZrCo: an experimental and theoretical study

    International Nuclear Information System (INIS)

    The thermodynamic properties of ZrCo intermetallic were investigated both experimentally and theoretically to determine its applicability for the storage of hydrogen isotopes. The enthalpy increments of ZrCo were measured using a high temperature inverse drop calorimeter in the temperature range 645-1500 K. A set of thermodynamic functions such as entropy, Gibbs energy function, heat capacity, Gibbs energy and enthalpy values for ZrCo were calculated using the data obtained in this study. The entropy (S) and specific heat capacities (Cv and Cp) of ZrCo were also computed using Debye-Grueneisen quasi-harmonic approximation to support the experimental study. (author)

  6. Experimental and theoretical investigation of timing jitter inside a stretcher-compressor setup.

    Science.gov (United States)

    Klingebiel, Sandro; Ahmad, Izhar; Wandt, Christoph; Skrobol, Christoph; Trushin, Sergei A; Major, Zsuzsanna; Krausz, Ferenc; Karsch, Stefan

    2012-02-13

    In an optically synchronized short-pulse optical-parametric chirped-pulse amplification (OPCPA) system, we observe a few-100 fs-scale timing jitter. With an active timing stabilization system slow fluctuations are removed and the timing jitter can be reduced to 100 fs standard deviation (Std). As the main source for the timing fluctuations we could identify air turbulence in the stretcher-compressor setup inside the chirped pulse amplification (CPA) pump chain. This observation is supported by theoretical investigation of group delay changes for angular deviations occurring between the parallel gratings of a compressor or stretcher, as they can be introduced by air turbulence. PMID:22418103

  7. The Investigation of Different Properties of Clonidine Drug Binding to Carbon Nanotube: A Theoretical Study

    OpenAIRE

    Z. Yousefian

    2014-01-01

    In this study, we investigated the binding of Clonidine Drug (C9H9Cl2N3) with zigzag single walled Carbon Nanotubes (SWCNTs) (5, 0) and a length of 5ᵒA by theoretical methods of theory (NMR,NBO, HOMO- LUMO Gap energy,…calculations) using Gaussian ­09 software package. Then, Simulation was done in MM+, AMBER and OPLS force fields by Monte Carlo method in HyperChem. Three important energy parameters – Potential Energy, Kinetic Energy and Total Energy-calculated in five different simulating temp...

  8. The Investigation of Different Properties of Clonidine Drug Binding to Carbon Nanotube: A Theoretical Study

    Directory of Open Access Journals (Sweden)

    Z. Yousefian

    2014-12-01

    Full Text Available In this study, we investigated the binding of Clonidine Drug (C9H9Cl2N3 with zigzag single walled Carbon Nanotubes (SWCNTs (5, 0 and a length of 5ᵒA by theoretical methods of theory (NMR,NBO, HOMO- LUMO Gap energy,…calculations using Gaussian ­09 software package. Then, Simulation was done in MM+, AMBER and OPLS force fields by Monte Carlo method in HyperChem. Three important energy parameters – Potential Energy, Kinetic Energy and Total Energy-calculated in five different simulating temperatures (308, 310, 312, 314 and 316 Kelvin were used for computation and good results were obtained.

  9. Theoretical investigation of TbNi_{5-x}Cu_x optical properties

    OpenAIRE

    Nekrasov, I. A.; Kokorina, E.E.; ~Galkin, V. A.; Kuz'min, Y. I.; ~Knyazev, Y. V.; Kuchin, A. G.

    2010-01-01

    In this paper we present theoretical investigation of optical conductivity for intermetallic TbNi_{5-x}Cu_x series. In the frame of LSDA+U calculations electronic structure for x=0,1,2 and on top of that optical conductivities were calculated. Disorder effects of Ni for Cu substitution on a level of LSDA+U densities of states (DOS) were taken into account via averaging over all possible Cu ion positions for given doping level x. Gradual suppression and loosing of structure of optical conducti...

  10. Experimental and Theoretical Investigation of Valence Orbitals in 1,4-Dioxane by Electron momentum Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    YANG Tie-Cheng; NING Chuan-Gang; SU Guo-Lin; DENG Jing-Kang; ZHANG Shu-Feng; REN Xue-Guang; HUANG Yan-Ru

    2006-01-01

    @@ The binding energy spectrum of all valence orbitals and the momentum distributions of highest occupied molecular orbital (HOMO: 8ag), 7bu + 7ag, 4bu, 2bg + 4ag and 2au in 1, 4-dioxane are investigated by electron momentum spectroscopy (EMS) with 600 e V impact energy. The experimental results are consistent with theoretical calculations of C2h chair conformation using the Hartree-Fock method and density functional theory with 6-311++G**and A UG-CC-PVTZ basis sets.

  11. A domain-theoretic investigation of posets of sub-sigma-algebras (extended abstract)

    OpenAIRE

    Ingo Battenfeld

    2010-01-01

    Given a measurable space (X, M) there is a (Galois) connection between sub-sigma-algebras of M and equivalence relations on X. On the other hand equivalence relations on X are closely related to congruences on stochastic relations. In recent work, Doberkat has examined lattice properties of posets of congruences on a stochastic relation and motivated a domain-theoretic investigation of these ordered sets. Here we show that the posets of sub-sigma-algebras of a measurable space do not enjoy de...

  12. Experimental and theoretical investigations on the antioxidant activity of isoorientin from Crotalaria globosa

    Science.gov (United States)

    Deepha, V.; Praveena, R.; Sivakumar, Raman; Sadasivam, K.

    2014-03-01

    The increasing interests in naturally occurring flavonoids are well known for their bioactivity as antioxidants. The present investigations with combined experimental and theoretical methods are employed to determine the radical scavenging activity and phytochemicals present in Crotalaria globosa, a novel plant source. Preliminary quantification of ethanolic extract of leaves shows high phenolic and flavonoid content than root extract; also it is validated through DPPHrad assay. Further analysis is carried out with successive extracts of leaves of varying polarity of solvents. In DPPHrad and FRAP assays, ethyl acetate fraction (EtOAc) exhibit higher scavenging activity followed by ethanol fraction (EtOH) whereas in NOS assay ethanol fraction is slightly predominant over the EtOAc fraction. The LC-MS analysis provides tentative information about the presence of flavonoid C-glycoside in EtOAc fraction (yellow solid). Presence of flavonoid isorientin has been confirmed through isolation (PTLC) and detected by spectroscopy methods (UV-visible and 1H NMR). Utilizing B3LYP/6-311G (d,p) level of theory the structure and reactivity of flavonoid isoorientin theoretically have been explored. The analysis of the theoretical Bond dissociation energy values, for all Osbnd H sites of isoorientin reveals that minimum energy is required to dissociate H-atom from B-ring than A and C-rings. In order to validate the antioxidant characteristics of isoorientin the relevant molecular descriptors IP, HOMO-LUMO, Mulliken spin density analysis and molecular electrostatic potential surfaces have been computed and interpreted. From experimental and theoretical results, it is proved that isoorientin can act as potent antiradical scavenger in oxidative system.

  13. Theoretical investigation of the MTC noise estimate in 1-D homogeneous systems

    International Nuclear Information System (INIS)

    In this paper, the accuracy of the noise-based determination of the moderator temperature coefficient (MTC) is investigated theoretically and quantitatively. It is known from earlier work that the noise method systematically underestimates the MTC. In this paper, it is found that the main reason for the underestimation lies with the radial incoherence of the temperature fluctuations. The deviation of the reactor response from point-kinetics is another possible reason, but it was found to play a quite insignificant role. The theory of neutron noise, induced by spatially random perturbations is elaborated and by its help the inaccuracy (bias) of the noise based MTC estimation was quantitatively investigated. It was found that a relatively short correlation length of the temperature fluctuations, which is in agreement with experimental evidence, can explain the observed underestimation of the MTC by the noise method

  14. Experimental and theoretical investigation on high-Tc superconducting intrinsic Josephson junctions

    Science.gov (United States)

    Grib, Alexander; Shukrinov, Yury; Schmidl, Frank; Seidel, Paul

    2010-11-01

    Within the last years many groups have realized and investigated different types of intrinsic Josephson junction (IJJ) arrays out of high-temperature superconducting single crystals or thin films. We tried to improve the synchronization between the junctions by external shunts. Mesa structures as well as microbridges on vicinal cut substrates showed multi-branch behaviour in their IV characteristics and random switching between branches. Theoretical modelling was done investigating phase dynamics and stability numerically as well as analytically. Branch structure in current voltage characteristics of IJJ is studied in the framework of different models, particularly, in capacitevely coupled Josephson junctions (CCJJ) model and CCJJ model with diffusion current. Results of modelling of return current in IV characteristics for stacks with different number of IJJ are presented. We discussed the possible mechanisms of synchronization and the ranges of stability. Conclusions with respect to application of such arrays such as radiation sources were given.

  15. Theoretical and Experimental Investigation of Force Estimation Errors Using Active Magnetic Bearings with Embedded Hall Sensors

    DEFF Research Database (Denmark)

    Voigt, Andreas Jauernik; Santos, Ilmar

    2012-01-01

    of AMBs by embedding Hall sensors instead of mounting these directly on the pole surfaces, force estimation errors are investigated both numerically and experimentally. A linearized version of the conventionally applied quadratic correspondence between measured Hall voltage and applied AMB force is......This paper gives an original theoretical and experimental contribution to the issue of reducing force estimation errors, which arise when applying Active Magnetic Bearings (AMBs) with pole embedded Hall sensors for force quantification purposes. Motivated by the prospect of increasing the usability...... for pole embedded and pole surface mounted Hall sensors. It is shown that in a given range of bias currents and rotor offsets, pole embedded and surface mounted Hall sensors perform equally well for the four pole heteropolar flux-split radial AMB under investigation. Furthermore, frequency dependence...

  16. Muramic Acid Measurements for Bacterial Investigations in Marine Environments by High-Pressure Liquid Chromatography

    OpenAIRE

    Mimura, Toru; Romano, Jean-Claude

    1985-01-01

    Muramic acid, a constituent of procaryotic cell walls, was assayed by high-pressure liquid chromatography in samples from several marine environments (water column, surface microlayer, and sediment) and a bacterial culture. It is used as a microbial biomass indicator. The method gave a good separation of muramic acid from interfering compounds with satisfactory reproducibility. A pseudomonad culture had a muramic acid content of 4.7 × 10−10 to 5.3 × 10−10 μg per cell during growth. In natural...

  17. Theoretical investigations on model ternary polypeptides using genetic algorithm-Some new results

    International Nuclear Information System (INIS)

    Graphical abstract: Model ternary polypeptide chains consisting of glycine, alanine and serine amino acids as repeat units in anti-parallel β-pleated sheet conformation have been theoretically investigated and designed using the genetic algorithm. The optimum solution or the polypeptide chain being searched for using the algorithm is the one having minimum band gap and maximum electronic delocalization in the polypeptide chain. The effects of (i) change of basis set from minimal to double zeta, (ii) change in secondary structure from β-pleated to α-helical, (iii) presence of solvation shell, and (iv) binding of ions such as H+ and Li+ to the peptide group on the resulting optimum solution as well as on electronic structure and conduction properties of polypeptides have been investigated taking the ab initio Hartree-Fock crystal orbital results as input. The band gap value was also found to decrease in presence of a solvation shell, in presence of cations in the vicinity of the polypeptide chain as well as with the use of an improved basis set. Highlights: → GA has been used for theoretical tailoring of aperiodic ternary polypeptides. → Band gap of polypeptide chain decreases in presence of solvation shell. → Band gap decreases in presence of cations in the vicinity of the chain. → H+ ion acts as a strong electron acceptor than Li+ ion due to smaller size. - Abstract: Using genetic algorithm (GA) model ternary polypeptides containing glycine, alanine and serine in β-pleated conformation have been theoretically investigated. In designing, the criterion to attain the optimum solution at the end of GA run is minimum band gap and maximum delocalization in the polypeptide chain. Ab initio results obtained using Clementi's minimal basis set are used as input. Effects of (i) change of basis set from minimal to double zeta, (ii) change in secondary structure from β-pleated to α-helical, (iii) presence of solvation shell and (iv) binding of H+ and Li+ ions to

  18. Arsenic speciation in seafood samples with emphasis on minor constituents. An investigation by high performance liquid chromatography with inductively coupled plasma mass spectrometric detection

    DEFF Research Database (Denmark)

    Larsen, Erik Huusfeldt; Pritzl, G.; Hansen, S. H.

    1993-01-01

    Extracts of 11 samples of shrimp, crab, fish, fish liver, shellfish and lobster digestive gland (hepatopancreas), including five certified reference materials, were investigated for their contents of arsenic compounds (arsenic speciation). The cation-exchange high performance liquid chromatography...

  19. Instrument modifications that produced reduced plate heights <2 with sub-2 μm particles and 95% of theoretical efficiency at k=2 in supercritical fluid chromatography.

    Science.gov (United States)

    Berger, Terry A

    2016-04-29

    The concept of peak fidelity was shown to be helpful in modeling tubing and detector cell dimensions. Connection tubing and flow cell variances were modeled to determine appropriate internal ID's, lengths, and volumes. A low dispersion plumbing configuration, based on these calculations, was assembled to replace the standard plumbing and produced the reported results. The modifications made were straightforward using commercially available parts. The full theoretical efficiency of a 3×100 mm column packed with 1.8 μm totally porous particles was achieved for the first time in supercritical fluid chromatography (SFC). Peak fidelity of >0.95 was maintained to below k=2. A reduced plate height as low as 1.87 was measured. Thus, true "ultra high performance" SFC was achieved, with the results a major improvement from all previous SFC reports. Since there were no efficiency losses, none could be attributed to thermal gradients caused by the expansion of the fluid over large pressure drops, under the conditions used. Similarly, changes in diffusion coefficients caused by significant decreases in density during expansion are apparently balanced by the increase in linear velocity, keeping the ratio between the diffusion coefficient and the linear velocity a constant. Changing modifier concentration to change retention was shown to not be a significant problem. All these issues have been a concern in the past. Diffusion coefficients, and viscosity data needs to be collected at high pressures before the actual limits of SFC can be discovered. PMID:27046003

  20. Nonlinear dynamics of an electrically actuated mems device: Experimental and theoretical investigation

    KAUST Repository

    Ruzziconi, Laura

    2013-11-15

    This study deals with an experimental and theoretical investigation of an electrically actuated micro-electromechanical system (MEMS). The experimental nonlinear dynamics are explored via frequency sweeps in a neighborhood of the first symmetric natural frequency, at increasing values of electrodynamic excitation. Both the non-resonant branch, the resonant one, the jump between them, and the presence of a range of inevitable escape (dynamic pull-in) are observed. To simulate the experimental behavior, a single degree-offreedom spring mass model is derived, which is based on the information coming from the experimentation. Despite the apparent simplicity, the model is able to catch all the most relevant aspects of the device response. This occurs not only at low values of electrodynamic excitation, but also at higher ones. Nevertheless, the theoretical predictions are not completely fulfilled in some aspects. In particular, the range of existence of each attractor is smaller in practice than in the simulations. This is because, under realistic conditions, disturbances are inevitably encountered (e.g. discontinuous steps when performing the sweeping, approximations in the modeling, etc.) and give uncertainties to the operating initial conditions. A reliable prediction of the actual (and not only theoretical) response is essential in applications. To take disturbances into account, we develop a dynamical integrity analysis. Integrity profiles and integrity charts are performed. They are able to detect the parameter range where each branch can be reliably observed in practice and where, instead, becomes vulnerable. Moreover, depending on the magnitude of the expected disturbances, the integrity charts can serve as a design guideline, in order to effectively operate the device in safe condition, according to the desired outcome. Copyright © 2013 by ASME.

  1. Theoretical investigation of solar humidification-dehumidification desalination system using parabolic trough concentrators

    International Nuclear Information System (INIS)

    Highlights: → We evaluated the performance of sea water HDD system powered by solar PTC. → The proposed design to the expected desalination plant performance was introduced. → The collector thermal efficiency was a function of solar radiation value. → The highest fresh water productivity is found to be in the summer season. → The production time reaches 42% of the day time in the summer season. - Abstract: This paper deals with the status of solar energy as a clean and renewable energy applications in desalination. The object of this research is to theoretically investigate the principal operating parameters of a proposed desalination system based on air humidification-dehumidification principles. A parabolic trough solar collector is adapted to drive and optimize the considered desalination system. A test set-up of the desalination system was designed and a theoretical simulation model was constructed to evaluate the performance and productivity of the proposed solar humidification-dehumidification desalination system. The theoretical simulation model was developed in which the thermodynamic models of each component of the considered were set up respectively. The study showed that, parabolic trough solar collector is the suitable to drive the proposed desalination system. A comparison study had been presented to show the effect of the different parameters on the performance and the productivity of the system. The productivity of the proposed system showed also an increase with the increase of the day time till an optimum value and then decreased. The highest fresh water productivity is found to be in the summer season, when high direct solar radiation and long solar time are always expected. The production time reaches a maximum value in the summer season, which is 42% of the day.

  2. Thermodynamic study of the electrochemical oxidation of some aminophenol derivatives: Experimental and theoretical investigation

    International Nuclear Information System (INIS)

    Electrochemical oxidation of some aminophenol derivatives (1–5) has been investigated both experimentally and theoretically. Experimental results were obtained using cyclic voltammetry and controlled potential coulometry. The theoretical results were calculated at DFT (B3LYP and BP86) levels of theory and 6-311 + G (p,d) basis sets. Using a general thermodynamic cycle, the calculated ΔGtot of the oxidation of the studied aminophenol derivatives indicates that thermodynamic is one of the important parameters on the potential oxidation. The obtained results show that electrochemical oxidation potential of 1–5 is directly dependent on the ΔGtot of electrochemical oxidation. In addition in this paper, mechanisms of the electrochemical oxidation of 4-(piperazin-1-yl) phenol (6) in the presence of various nucleophiles was studied in viewpoint of the thermodynamic. Mechanistic study of the electrochemical oxidation of 6 in the presence of different nucleophiles indicates that although the electrochemical oxidations of 6H+ in the presence of different nucleophiles have different mechanisms but proceed in the thermodynamically favored directions

  3. Theoretical and laboratory investigations of flow through fractures in crystalline rock

    International Nuclear Information System (INIS)

    A theoretical model developed for flow through a deformable fracture subject to stresses was successfully tested against laboratory experiments. The model contains no arbitrary parameters and can be used to predict flow rates through a single fracture if the fractional fracture contact area can be estimated and if stress-deformation data are available. These data can be obtained from laboratory or in situ tests. The model has considerable potential for practical application. The permeability of ultralarge samples of fractured crystalline rock as a function of stresses was measured. Results from tests on a pervasively fractured 1-m-diameter specimen of granitic rock showed that drastically simplifying assumptions must be used to apply theoretical models to this type of rock mass. Simple models successfully reproduce the trend of reduced permeability as stress is applied in a direction normal to the fracture plane. The tests also demonstrated how fracture conductivity increases as a result of dilatancy associated with shear displacements. The effect of specimen size on the hydraulic properties of fractured rock was also investigated. Permeability tests were performed on specimens of charcoal black granite containing a single fracture subjected to normal stress. Results are presented for tests performed on a 0.914-m-diameter specimen and on the same specimen after it had been reduced to 0.764 m in diameter. The data show that fracture conductivity is sensitive to stress history and sample disturbance

  4. An Experimental and Theoretical Investigation of a Micromirror Under Mixed-Frequency Excitation

    KAUST Repository

    Ilyas, Saad

    2015-01-12

    We present an experimental and theoretical investigation of a micromachined mirror under a mixed-frequency signal composed of two harmonic ac sources. The micromirror is made of polyimide as the main structural layer. The experimental and theoretical dynamics are explored via frequency sweeps in the desired neighborhoods. One frequency is fixed while the other frequency is swept through a wide range to study the dynamic responses. To simulate the behavior of the micromirror, it is modeled as a single degree of freedom system, where the parameters of the model are extracted experimentally. A good agreement is reported among the simulation results and the experimental data. These responses are studied under different frequencies and input voltages. The results show interesting dynamics, where the system exhibits primary resonance and combination resonances of additive and subtractive type. The mixed excitation is demonstrated as a way to increase the bandwidth of the resonator near primary resonance, which can be promising for resonant sensing applications in the effort to increase the signal-noise ratio over extended frequency range.

  5. THEORETICAL INVESTIGATION OF THE INNOVATIVE BRUSH-GRATER DEVICE FOR EXTRACTING FOREST SEEDS FROM PERICARP

    Directory of Open Access Journals (Sweden)

    Sviridov L. T.

    2015-04-01

    Full Text Available Protective forest plantations, shelter belts and plantings along the highways of Central - Black Earth region and southern Russia are badly damaged, and in some areas destroyed. Therefore, they can not perform their functions and require major reconstruction or restoration. The most resistant and applicable trees and shrubs to create protective forest plantings are: maple, ash, elm species and three-thorned acacia, honey-locust, white and yellow acacia, and other legumes breeds with high drought tolerance, disease resistance, technogenic pollution and pest damage. For the creation and restoration of protective forest plantations we require seeds of these species containing pericarp. In Voronezh State Forestry Academy we have carried out a scientific research for creation of a machine for extracting seeds from the legumes. Analysis of the results of scientific research of prototyping machines showed that they were made without considered technological and mechanical properties of the legumes theoretical researches workflow machines for extracting seeds from the legumes and scientific basis of design parameters and operating modes. In this article we have a presentation of the experimental sample of the machine for extracting seeds from the legumes and theoretical investigation of the workflow in the batch hopper. According to the results of the study, we have obtained a mathematical expression, which allows you to define the parameters and modes of operation of a brush-grater device

  6. Experimental and Theoretical Investigations of Phonation Threshold Pressure as a Function of Vocal Fold Elongation

    Science.gov (United States)

    Tao, Chao; Regner, Michael F.; Zhang, Yu; Jiang, Jack J.

    2014-01-01

    Summary The relationship between the vocal fold elongation and the phonation threshold pressure (PTP) was experimentally and theoretically investigated. The PTP values of seventeen excised canine larynges with 0% to 15% bilateral vocal fold elongations in 5% elongation steps were measured using an excised larynx phonation system. It was found that twelve larynges exhibited a monotonic relationship between PTP and elongation; in these larynges, the 0% elongation condition had the lowest PTP. Five larynges exhibited a PTP minimum at 5% elongation. To provide a theoretical explanation of these phenomena, a two-mass model was modified to simulate vibration of the elongated vocal folds. Two pairs of longitudinal springs were used to represent the longitudinal elastin in the vocal folds. This model showed that when the vocal folds were elongated, the increased longitudinal tension would increase the PTP value and the increased vocal fold length would decrease the PTP value. The antagonistic effects contributed by these two factors were found to be able to cause either a monotonic or a non-monotonic relationship between PTP and elongation, which were consistent with experimental observations. Because PTP describes the ease of phonation, this study suggests that there may exist a nonzero optimal vocal fold elongation for the greatest ease for phonation in some larynges. PMID:25530744

  7. Experimental and theoretical investigation of para-aminophenol ionization in corona discharge

    Science.gov (United States)

    Bahrami, H.; Salehabadi, H.

    2015-03-01

    Ionization of para-aminophenol was investigated using an ion mobility spectrometer equipped with a corona discharge as ionization source. The experimental results were confirmed with the use of theoretical method, based on density functional theory. Two peaks were observed in the ion mobility spectrum in the positive ion mode which was corresponded to the protonated isomers of para-aminophenol. It was observed that the relative intensities of the peaks depend on the sample concentration and the nature of the reactant ions. The relative energies of ions derived from protonation of para-aminophenol and its topical proton affinities were determined for different sites in the gas phase. The peak with the lower drift time was assigned to the oxygen protonated isomer and the other peak was ascribed to the nitrogen protonated isomer of para-aminophenol. The calculated dipole moment and localized charge of each isomer were used to verify the ion mobility peak separation. It was shown that combination of theoretical and experimental tools leads to reliable prediction of reactive protonation sites of chemicals in a corona discharge.

  8. Theoretical and experimental investigation on tandem Theoretical and experimental investigation on tandem modulator configurations for Frequency Coded Quantum Key Distribution systems

    CERN Document Server

    Mora, J; Amaya, W; Garcia-Munoz, V; Capmany, J

    2009-01-01

    We have theoretically and experimentally address the possible tandem electro-optical modulator configurations that can be employed to implement Frequency Coded Quantum Key Distribution systems (FC-QKD). A closed and general formulation of the end to end field propagation in a dispersion compensated FC-QKD optical fiber system under the low modulation index regime is presented which accounts for all the possible tandem combinations. The properties and the parameter selection of the modulators to achieve each one are summarized. We also address which protocol (B92, BB84 or either) is feasible to be implemented with each configuration. The results confirm those reported for the configurations previously reported in the literature and, at the same time, show the existence of four novel tandem modulator configurations that can also be employed. We have also provided experimental evidence of the successful operation of the novel configurations that confirm the behavior predicted by the theoretical results.

  9. Theoretical investigation on degradation behaviors of spectral properties of thermal control coatings induced by charged particles

    International Nuclear Information System (INIS)

    The degradation of spectral properties of thermal control coatings on spacecrafts is investigated in this paper. By studying their physical components and geometry structure, the factors which determine the spectral properties of the coatings are founded. A theoretical model for calculating the spectral absorptance of coatings is proposed based on the Mie's theory and Stratified Media theory. Mathematical expressions are introduced for accounting for the effect of the complicated environment. Based on these work, a predicting model for the degradation of spectral absorptance properties of the coatings is established. To validate this model, the predicted degradation performance of spectral properties of zinc oxide based coatings under electrons and protons exposure are compared with the experimental data. A good agreement is found at the wavelength between 250 nm and 2500 nm. Finally, a useful approach for predicting the degradation behaviors of thermal control coatings on spacecrafts in orbit is established.

  10. Theoretical and Computational Investigation of Periodically Focused Intense Charged-Particle Beams

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chiping [Massachusetts Institute of Technology

    2013-06-26

    The purpose of this report is to summarize results of theoretical and computational investigations of periodically focused intense charged-particle beams in parameter regimes relevant to the development of advanced high-brightness, high-power accelerators for high-energy physics research. The breakthroughs and highlights in our research in the period from April 1, 2010 to March 30, 2013 were: a) Theory and simulation of adiabatic thermal Child-Langmuir flow; b) Particle-in-cell simulations of adiabatic thermal beams in periodic solenoidal focusing field; c)Dynamics of charged particles in an adiabatic thermal beam equilibrium in a periodic solenoidal focusing field; d) Training of undergraduate researchers and graduate student in accelerator and beam physics. A brief introduction and summary is presented. Detailed descriptions of research results are provided in an appendix of publications at the end of the report.

  11. Theoretical Investigation of Nonlinear Optical Properties of Organic and Transition Metal Hybrid Azobenzene Dendrimers

    Institute of Scientific and Technical Information of China (English)

    LIU Cai-Ping; LIU Ping; WU Ke-Chen

    2008-01-01

    In this work, we report a theoretical exploration of the responses of organic azo-benzene dendrimers. The polarizabilities, the first and second hyperpolarizabilities of the azobenzene monomers (GO), and the first, second and third generation (G1, G2 and G3, respectively) are investigated by semi-empirical methods. The calculated results show that the nonlinear optical (NLO)properties of these organic dendrimers are mainly determined by the azobenzene chromospheres.Additionally, the values of β and γ increase almost in proportion to the number of chromophores. On the other hand, two types of transition metal hybrid azobenzene dendrimers (core-hybrid and branch-end hybrid according to the sites combined with transition metals) are simulated and discussed in detail in the framework of time-dependent density functional theory (TDDFT). The calculated results reveal that the NLO responses of these metal dendrimers distinctly varied as a result of altering the charge transfer transition scale and the excitation energies.

  12. Theoretical investigations of the experimentally observed selectivity of a cobalt imprinted polymer.

    Science.gov (United States)

    Bhaskarapillai, Anupkumar; Chandra, Sharat; Sevilimedu, Narasimhan V; Sellergren, Börje

    2009-11-15

    A cobalt imprinted polymer synthesised, for reducing the volume of radioactive waste generated during nuclear reactor decontaminations, using vinylbenzyl iminodiacetate (VbIDA) as the functional ligand, has been found to be selective for cobaltous ions over excess ferrous ions. The selectivity of the polymer has been investigated through theoretical calculation of the formation energies of complexes involved by using the ab-initio density functional theory (DFT) code SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms). The formation energies of complexes of Fe(2+), Co(2+), Cu(2+) and Ni(2+) with the free functional ligands as well as with ligands attached to the crosslinkers have been calculated. The calculations revealed that the ferrous forms an unstable complex with the ligands attached to the crosslinkers. The formation energy calculation results were found to corroborate the experimentally observed selectivity order. PMID:19414245

  13. Rheological investigations on the theoretical predicted “Poisoning” effect in bidisperse ferrofluids

    Science.gov (United States)

    Siebert, E.; Dupuis, V.; Neveu, S.; Odenbach, S.

    2015-01-01

    Interparticle interactions in ferrofluids especially the influence of small particles on the agglomeration behaviour of large particles were the topic of numerous theoretical predictions and simulations as well as of experimental investigations. In this context the "Poisoning" effect describes the decrease of the magnetoviscous effect in the presence of small particles in a bidisperse model fluid. In order to examine this effect rheological experiments have been carried out by means of a specially designed rheometer, which allows measurements under the influence of an applied magnetic field. We were able to synthesize ferrofluids with a narrow particle size distribution containing only small or large cobalt ferrite nanoparticles, which were mixed to receive various bidisperse fluid samples. With these fluids changes of the viscous behaviour in a magnetic field have been measured and compared according to their individual compositions.

  14. Theoretical and experimental investigation of fiber Bragg gratings with different lengths for ultrasonic detection

    Science.gov (United States)

    Yu, Zhouzhou; Jiang, Qi; Zhang, Hao; Wang, Junjie

    2016-06-01

    In this paper, the response of fiber Bragg gratings (FBGs) subjected to the ultrasonic wave has been theoretically and experimentally investigated. Although FBG sensors have been widely used in the ultrasonic detection for practical structural health monitoring, the relationship between the grating length and ultrasonic frequency is not yet to be obtained. To address this problem, an ultrasound detection system based on FBGs is designed and the response sensitivity of different lengths gratings are detected. Experimental results indicate that the grating with 3 mm length has a higher sensitivity when detecting high frequency ultrasonic wave, and the amplitude can be up to 0.6 mV. The 10 mm length grating has better detection sensitivity for low frequency ultrasonic wave and the amplitude is 0.8 mV. The results of this analysis provide useful tools for high sensitivity ultrasound detection in damage detection systems.

  15. Terahertz Generation in an Electrically Biased Optical Fiber: A Theoretical Investigation

    Directory of Open Access Journals (Sweden)

    Montasir Qasymeh

    2012-01-01

    Full Text Available We propose and theoretically investigate a novel approach for generating terahertz (THz radiation in a standard single-mode fiber. The optical fiber is mediated by an electrostatic field, which induces an effective second-order nonlinear susceptibility via the Kerr effect. The THz generation is based on difference frequency generation (DFG. A dispersive fiber Bragg grating (FBG is utilized to phase match the two interacting optical carriers. A ring resonator is utilized to boost the optical intensities in the biased optical fiber. A mathematical model is developed which is supported by a numerical analysis and simulations. It is shown that a wide spectrum of a tunable THz radiation can be generated, providing a proper design of the FBG and the optical carriers.

  16. Theoretical investigation of a blue hydroxyquinaldine-based aluminum(III) complex

    International Nuclear Information System (INIS)

    The absorption and light-emitting properties of a blue aluminum complex are investigated theoretically. The complex is bis(8-hydroxyquinolinolato) aluminum hydroxide [Al(Mq)2OH] and emits at about 485 nm. Very bright organic light-emitting diodes can be fabricated from Al(Mq)2OH with a maximum luminance of about 14 000 cd/m2. The geometry, bonding, and frontier orbitals are examined in details by self-consistent Hartree-Fock method and by density functional theory. Computational results indicate that the peak emission is mainly determined by the 2-methyl-8-quinolinol group and is independent of the hydroxide group. The computed absorption and emission gaps are in good agreement with experimentally determined values

  17. A Review of Experimental And Theoretical Investigations of Stable Isotope Separation by Plasma Methods

    International Nuclear Information System (INIS)

    Here is given a review of experimental and theoretical investigations of isotope separation processes in different plasma separation devices: plasma centrifuges, RF-systems with traveling magnetic field, DC arc discharges, nonequilibrium plasmachemical reactions (diffusion methods), and also in ICR-installations, performing isotopically selective ion-cyclotron resonance heating of the target component in magnetized collisionless plasma (selective collisionless method). Applied to separation installations, with the use of diffusion processes, various cardinal mechanisms are considered, leading to separation phenomena in plasma: centrifuging, thermodiffusion, ion wind, difference of isotope ionization degree, etc. Comparison is performed with the results of experiments. Problems of metal isotope separation by method of isotopically selective ion cyclotron resonance (ICR) are considered. Estimations of energetic consumption in all plasma methods of isotope separation and possibility of their industrial use are given. (author)

  18. Catecholase activity investigations using in situ copper complexes continuing Schiff base derivatives with a theoretical calculation

    Directory of Open Access Journals (Sweden)

    A. Djedouani

    2015-03-01

    Full Text Available The study of catecholase activity of a series of Schiff base compounds using in situ copper complexes of 4-hydroxy-6-methyl-3-(1-(phenyliminoethyl-2H-pyran-2-one derivatives has been reported. The reaction rate depends on four parameters: The nature of the substitution in para position to the benzene ring, the nature of counter anion, the concentration of ligand and the nature of solvent. The highest rate activity is given by complex resulting from one equivalent of ligand L2 and two equivalents of copper acetate in methanol, which equal to 62.25 µmol.min-1.L-1.In other part, a theoretical study of such ligands using the semi-empirical method AM1 were also investigated. A good relationship founded between the maximal reaction rate (Vmax and the HOMO energy (Pearson correlation: r=-0.794.

  19. A Theoretical Investigation of Composite Overwrapped Pressure Vessel (COPV) Mechanics Applied to NASA Full Scale Tests

    Science.gov (United States)

    Thesken, John C.; Murthy, Pappu L. N.; Phoenix, S. L.; Greene, N.; Palko, Joseph L.; Eldridge, Jeffrey; Sutter, James; Saulsberry, R.; Beeson, H.

    2009-01-01

    A theoretical investigation of the factors controlling the stress rupture life of the National Aeronautics and Space Administration's (NASA) composite overwrapped pressure vessels (COPVs) continues. Kevlar (DuPont) fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of a load sharing liner, the manufacturing induced residual stresses and the complex mechanical response, the state of actual fiber stress in flight hardware and test articles is not clearly known. This paper is a companion to a previously reported experimental investigation and develops a theoretical framework necessary to design full-scale pathfinder experiments and accurately interpret the experimentally observed deformation and failure mechanisms leading up to static burst in COPVs. The fundamental mechanical response of COPVs is described using linear elasticity and thin shell theory and discussed in comparison to existing experimental observations. These comparisons reveal discrepancies between physical data and the current analytical results and suggest that the vessel s residual stress state and the spatial stress distribution as a function of pressure may be completely different from predictions based upon existing linear elastic analyses. The 3D elasticity of transversely isotropic spherical shells demonstrates that an overly compliant transverse stiffness relative to membrane stiffness can account for some of this by shifting a thin shell problem well into the realm of thick shell response. The use of calibration procedures are demonstrated as calibrated thin shell model results and finite element results are shown to be in good agreement with the experimental results. The successes reported here have lead to continuing work with full scale testing of larger NASA COPV

  20. An experimental and theoretical investigation of the photophysics of 1-hydroxy-2-naphthoic acid.

    Science.gov (United States)

    Mishra, H; Maheshwary, S; Tripathi, H B; Sathyamurthy, N

    2005-03-31

    Photophysical and photochemical properties of 1-hydroxy-2-naphthoic acid (1,2-HNA) have been investigated experimentally by steady state and time domain fluorescence measurements and theoretically by Hartree-Fock (HF), configuration interaction at the single excitation (CIS) level, density functional theoretic (DFT), and semiempirical (AM1) methods. 1,2-HNA exhibits normal fluorescence that depends on its concentration, nature of the solvent, pH, temperature, and wavelength of excitation. It seems to form different emitting species in different media, akin to 3-hydroxy-2-naphthoic acid (3,2-HNA). The large Stokes shifted emission observed at pH 13 is attributed to species undergoing excited-state intramolecular proton transfer. Nonradiative transition seems to increase on protonation and decrease on deprotonation. AM1(PECI=8) calculations predict the absorption maximum (lambda(max) = 335.9 nm) in reasonable agreement with experiment (lambda(max) = 352 nm) for the neutral 1,2-HNA. They also predict a red shift in absorption on protonation and a blue shift on deprotonation as observed experimentally. CIS calculations tend to overestimate the energy gap and hence underestimate the absorption maxima between the ground and the excited electronic states of 1,2-HNA and its protonated and deprotonated forms. However, they do predict correctly that the excited state intramolecular proton transfer is likely to occur in the deprotonated form of 1,2-HNA and not in the neutral and the protonated forms. A single minimum is found in the potential energy profile for the ground state as well as the first excited state of 1,2-HNA and its protonated species. In contrast, a double minimum with a nominal barrier in between is predicted for the ground state and also the first three excited states of the deprotonated species. The keto form of the deprotonated species is found to be slightly less stable than the enol form in all the states investigated. PMID:16833586

  1. Corrosion product deposits on boiling-water reactor cladding: Experimental and theoretical investigation of magnetic properties

    Science.gov (United States)

    Orlov, A.; Degueldre, C.; Wiese, H.; Ledergerber, G.; Valizadeh, S.

    2011-09-01

    Recent Eddy current investigations on the cladding of nuclear fuel pins have shown that the apparent oxide layers are falsified due to unexpected magnetic properties of corrosion product deposits. Analyses by Scanning Electron Microscopy (SEM) or Electron Probe Micro Analysis (EPMA) demonstrated that the deposit layer consists of complex 3-d element oxides (Ni, Mn, Fe) along with Zn, since the reactor operates with a Zn addition procedure to reduce buildup of radiation fields on the recirculation system surfaces. The oxides crystallise in ferritic spinel structures. These spinels are well-known for their magnetic behaviour. Since non-magnetic zinc ferrite (ZnFe 2O 4) may become magnetic when doped with even small amounts of Ni and/or Mn, their occurrence in the deposit layer has been analyzed. The magnetic permeability of zinc ferrite, trevorite and jacobsite and their solid solutions are estimated by magnetic moment additivity. From the void history examination, the low elevation sample (810 mm) did not face significant boiling during the irradiation cycles suggesting growth of (Mn0.092+Zn0.752+Fe0.293+)[(Fe1.713+Mn0.032+Ni0.132+)O] crystals with theoretical value of the magnetic permeability for the averaged heterogeneous CRUD layer of 9.5 ± 3. Meanwhile, (Mn0.162+Zn0.552+Fe0.293+)[(Fe1.713+Mn0.042+Ni0.252+)O] crystallizes at the mid elevation (1810 mm) with theoretical magnetic permeability for the CRUD layer of 4.2 ± 1.5 at the investigated azimuthal location. These theoretical data are compared with the magnetic permeability of the corrosion product deposited layers gained from reactor pool side Eddy current (EC) analyses (9.0 ± 1.0 for low and 3.5 ± 1.0 for high elevation). The calculated thicknesses and magnetic permeability values of the deposition layers (estimated by MAGNACROX multifrequency EC method) match together with these estimated using an "ion magnetic moment additivity" model.

  2. Corrosion product deposits on boiling-water reactor cladding: Experimental and theoretical investigation of magnetic properties

    International Nuclear Information System (INIS)

    Recent Eddy current investigations on the cladding of nuclear fuel pins have shown that the apparent oxide layers are falsified due to unexpected magnetic properties of corrosion product deposits. Analyses by Scanning Electron Microscopy (SEM) or Electron Probe Micro Analysis (EPMA) demonstrated that the deposit layer consists of complex 3-d element oxides (Ni, Mn, Fe) along with Zn, since the reactor operates with a Zn addition procedure to reduce buildup of radiation fields on the recirculation system surfaces. The oxides crystallise in ferritic spinel structures. These spinels are well-known for their magnetic behaviour. Since non-magnetic zinc ferrite (ZnFe2O4) may become magnetic when doped with even small amounts of Ni and/or Mn, their occurrence in the deposit layer has been analyzed. The magnetic permeability of zinc ferrite, trevorite and jacobsite and their solid solutions are estimated by magnetic moment additivity. From the void history examination, the low elevation sample (810 mm) did not face significant boiling during the irradiation cycles suggesting growth of (Mn0.092+Zn0.752+Fe0.293+)[(Fe1.713+Mn0.032+Ni0.132+)O4] crystals with theoretical value of the magnetic permeability for the averaged heterogeneous CRUD layer of 9.5 ± 3. Meanwhile, (Mn0.162+Zn0.552+Fe0.293+)[(Fe1.713+Mn0.042+Ni0.252+)O4] crystallizes at the mid elevation (1810 mm) with theoretical magnetic permeability for the CRUD layer of 4.2 ± 1.5 at the investigated azimuthal location. These theoretical data are compared with the magnetic permeability of the corrosion product deposited layers gained from reactor pool side Eddy current (EC) analyses (9.0 ± 1.0 for low and 3.5 ± 1.0 for high elevation). The calculated thicknesses and magnetic permeability values of the deposition layers (estimated by MAGNACROX multifrequency EC method) match together with these estimated using an 'ion magnetic moment additivity' model.

  3. Experimental and theoretical investigation of nucleation and growth of atmospheric aerosols

    Science.gov (United States)

    Zhao, Jun

    Aerosol particles have profound impacts on human health, atmospheric radiation, and cloud microphysics and these impacts are strongly dependent on particle sizes. However, formation and growth of atmospheric particles are currently not well understood. In this work, laboratory and theoretical studies have been performed to investigate the formation and growth of atmospheric particles. The first two parts of the dissertation are a laboratory investigation of new particle formation and growth, and a theoretical study of atmospheric molecular complexes and clusters. The nucleation rate was considerably enhanced in the presence of cis-pinonic acid and ammonia. The composition of the critical cluster was estimated from the dependence of the nucleation rate on the precursor concentration and the time evolution of the clusters was then simulated using molecular dynamic simulations. Results from quantum chemical calculations and quantum theory of atoms in molecules (QTAIM) reveal that formation of strong hydrogen bonding between an organic acid and sulfuric acid is likely responsible for a reduction of the nucleation barrier by modifying the hydrophobic properties of the organic acid and allowing further addition of hydrophilic species (e.g., H2SO4, H2O, and possibly NH 3) to the hydrophilic side of the clusters. This promotes growth of the nascent cluster to overcome the nucleation barrier and thus enhances the nucleation in the atmosphere. The last part of this dissertation is the laboratory investigation of heterogeneous interactions of atmospheric carbonyls with sulfuric acid. Direct measurement has been performed to investigate the heterogeneous uptake of atmospheric carbonyls on sulfuric acid. Important parameters have been obtained from the time-dependent or time-independent uptake profiles. The results indicated that the acid-catalyzed reactions of larger aldehydes (e.g. octanal and 2, 4-hexadienal) in sulfuric acid solution were attributed to aldol condensation in

  4. Plasma Electronics. Theoretical and Experimental Investigations of Plasma Nonlinearity in the Powerful Microwave Oscillators

    International Nuclear Information System (INIS)

    During more than 50 years of Plasma Electronics development a great number of experimental and theoretical results have been achieved. These results allow understanding of physical processes which originate under charged particles beams interaction with a plasma. However, one essential aspect of such interaction remains insufficiently studied. The question is about a correlation between conditions of microwave excitation by a beam in plasma and plasma parameters. Each of these effects, namely the influence of plasma parameters on conditions of microwave excitation by a beam and plasma parameters variations under the influence of propagating microwave radiation are well known and investigated enough. However their common action under beam-plasma instability (BPI) development were not studied systematically, although the role of such reciprocal influence on character of these processes may be very large. The aim of this report is a review of recent theoretical and experimental investigations of such plasma nonlinearity in plasma-filled trawling-wave tubes. N.M.Zemlyansky and E.A.Kornilov have done experiments in Kharkov Institute of Physics and Technology (KhPhTI). Development of the theoretical model was started in KhPhTI (Yu.P.Bliokh, Ya.B.Fainberg, M.G.Lyubarsky, and V.O.Podobinsky) and continues by author in Technion. The developed theory takes into account two main reasons of the plasma density redistribution: high frequency pressure (HFP) force which ''push out'' plasma from the regions with increased microwave amplitude, or microwave discharge, which appears in the region where amplitude is large enough. Displaced (under HFP action) or additionally originating (under (BPD) development) plasma propagates from the disturbance source in the form of slow plasma waves (for example, ion-sound or magneto-sound waves), and the BPI develops in the nonhomogeneous plasma. It changes both magnitude and longitudinal distribution of excited microwave amplitude. As a result

  5. Experimental and theoretical investigations on the COMET concept for ex-vessel core melt retention

    International Nuclear Information System (INIS)

    In the very unlikely case of a core melt accident in a nuclear power plant, the reactor pressure vessel could fail and corium melt could be released into the reactor cavity. Subsequent processes could result in a threat of the containment integrity. As a counter-measure the implementation of a core-catcher device in nuclear power plants is envisaged. Such a core-catcher concept has been developed at the Forschungszentrum Karlsruhe (FZK, Germany) within the COMET project. It is based on water injection into the melt layer from the bottom, yielding rapid fragmentation of the corium, porosity formation and thus coolability. Detailed large scale experiments with sustained heating of melts have highlighted the sequences of flooding and cooling and have been used to optimise the COMET concept. The open porosities and large surfaces that are generated during melt solidification form a porous permeable structure that is permanently filled with the evaporating coolant water and thus allows efficient short-term and long-term removal of the decay heat. Two variants of the bottom flooding concept have been developed and seem technically mature for reactor application. Corium layers up to 0.5 m high are safely arrested and cooled by water supply with 0.2 bar overpressure. The conceptual and experimental work at FZK is accompanied by theoretical investigations at IKE, University of Stuttgart. These investigations address porosity formation as well as quenching and long-term coolability of layers with resulting porosities. The aim of the theoretical work is to get a better understanding of the underlying processes of porosity formation in order to generally support the applicability of the concept for real conditions and to allow checks and optimisation for various conditions. A model for porosity formation is presented, which assumes that this process is essentially determined by strong local pressure buildup from strong evaporation due to water injection from below and the

  6. Adsorption of Emerging Munitions Contaminants on Cellulose Surface: A Combined Theoretical and Experimental Investigation.

    Science.gov (United States)

    Shukla, Manoj K; Poda, Aimee

    2016-06-01

    This manuscript reports results of an integrated theoretical and experimental investigation of adsorption of two emerging contaminants (DNAN and FOX-7) and legacy compound TNT on cellulose surface. Cellulose was modeled as trimeric form of the linear chain of 1 → 4 linked of β-D-glucopyranos in (4)C1 chair conformation. Geometries of modeled cellulose, munitions compounds and their complexes were optimized at the M06-2X functional level of Density Functional Theory using the 6-31G(d,p) basis set in gas phase and in water solution. The effect of water solution was modeled using the CPCM approach. Nature of potential energy surfaces was ascertained through harmonic vibrational frequency analysis. Interaction energies were corrected for basis set superposition error and the 6-311G(d,p) basis set was used. Molecular electrostatic potential mapping was performed to understand the reactivity of the investigated systems. It was predicted that adsorbates will be weakly adsorbed on the cellulose surface in water solution than in the gas phase. PMID:27084096

  7. Theoretical investigation of interaction between the set of ligands and α7 nicotinic acetylcholine receptor

    Science.gov (United States)

    Glukhova, O. E.; Prytkova, T. R.; Shmygin, D. S.

    2016-03-01

    Nicotinic acetylcholine receptors (nAChRs) are neuron receptor proteins that provide a transmission of nerve impulse through the synapses. They are composed of a pentametric assembly of five homologous subunits (5 α7 subunits for α7nAChR, for example), oriented around the central pore. These receptors might be found in the chemical synapses of central and peripheral nervous system, and also in the neuromuscular synapses. Transmembrane domain of the one of such receptors constitutes ion channel. The conductive properties of ion channel strongly depend on the receptor conformation changes in the response of binding with some molecule, f.e. acetylcholine. Investigation of interaction between ligands and acetylcholine receptor is important for drug design. In this work we investigate theoretically the interaction between the set of different ligands (such as vanillin, thymoquinone, etc.) and the nicotinic acetylcholine receptor (primarily with subunit of the α7nAChR) by different methods and packages (AutodockVina, GROMACS, KVAZAR, HARLEM, VMD). We calculate interaction energy between different ligands in the subunit using molecular dynamics. On the base of obtained calculation results and using molecular docking we found an optimal location of different ligands in the subunit.

  8. A numerical investigation into the solids phase chromatography using a combined continuous and discrete approach

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Solids phase chromatography for particle classification is based on different retention times of particles with different properties when they are elutriated through a confined geometry.This work aims at a fundamental understanding of such a technology by using the combined continuous and discrete method.A packed bed is employed as the model confined geometry.The numerical method is compared first with experimental observations,followed by a parametric analysis of the effects on the flow hydrodynamics and solids behaviour of various parameters including the number of injected particles,the superficial gas velocity,the contact stiffness and the diameter ratio of the packed column to the packed particles.The results show that the modelling captures some important features of the flow of an injected pulse of fine particles in a packed bed. An increase in the number of injected particles or the superficial gas velocity reduces the retention time,whereas the contact stiffness does not show much effect over the range of 5×102 to5×104 N/m.It is also found that the effect on the retention time of the diameter ratio of the packed column to the packed particles seems complex showing a non-monotonous dependence.

  9. DFT theoretical and FT-IR spectroscopic investigations of the plasticity of clay minerals dispersions

    Science.gov (United States)

    Kasprzhitskii, A.; Lazorenko, G.; Yavna, V.; Daniel, Ph.

    2016-04-01

    Plasticity is the most important property of dispersions of clay minerals that determine the character of participation of these systems in many natural and technological processes. We report on the results of studies of hydration mechanism in typical clay minerals making part of natural dispersions of sedimentation masses by means of IR spectroscopy and theoretical density functional theory (DFT) methods. X-ray diffraction analysis of clay minerals of Millerovo mineral deposit (Russian Federation) is carried out. Regularities and peculiarities of interaction of water molecules with kaolinite basal planes (001) and (00 1 bar) are analyzed. The role of water in the formation of plasticity of clay minerals dispersions is revealed. The modes of water molecules placement and their state and structure in the system "clay mineral-water" is defined. Phase transition processes of clay minerals dispersion into plastic and liquid state and their influence on spectral characteristics of the systems are investigated. The interpretation of clay minerals phase transitions into plastic and fluid state based on the results of DFT simulation is given. The relation is established between specific variation of spectral characteristics and phase transitions of clay minerals dispersions into plastic and liquid state.

  10. Theoretical investigation of van der Waals forces between solid surfaces at nanoscales

    Science.gov (United States)

    Kudryavtsev, Yaroslav V.; Gelinck, Edwin; Fischer, Hartmut R.

    2009-08-01

    A theoretical investigation of van der Waals forces acting between two solid silicon surfaces at separations from zero to approximately 20 nm is presented. We focused our efforts on the analysis of different factors that can cause deviations from the classical pressure-distance dependence p ˜ 1/ D3. It is demonstrated that a layer (oxide or water) at any of the surfaces influences the pressure up to distances, which are an order of magnitude larger than its own thickness. A jump on the p( D) curve is expected at contact of the adsorbed liquid layers. The retardation of van der Waals forces at 5 < D < 20 nm has the similar effect on the pressure as 1 nm oxide layers. At the far end of this range the pressure decreases by 30% due to the retardation. Nanoscale roughness plays a great role when the surfaces are close-to-contact, the crucial factor is the height distribution of asperities. However, their curvature and surface density are also important, as well as the amount of adsorbed water.

  11. Theoretical investigation of indium phosphide buried ring resonators for new angular velocity sensors

    Science.gov (United States)

    Dell'Olio, Francesco; Ciminelli, Caterina; Armenise, Mario Nicola

    2013-02-01

    Here, we report the guidelines to be followed to optimize the design of a new angular velocity sensor based on an indium phosphide (InP) ring resonator. Optical properties of InP ring resonators have been investigated together with some significant physical effects for improving the sensor sensitivity. Three-dimensional algorithms have been utilized for the theoretical estimation of the waveguide loss. An optimized waveguide with propagation loss <0.3 dB/cm and a ring resonator with a quality factor of 1.5×106 have been designed. Performance of angular velocity sensors based on InP low-loss ring resonators has been estimated and discussed. Resolution of 10 deg/h and bias drift in the range of 0.1 to 0.3 deg/h have been evaluated for a fully integrated optical gyro including an InGaAsP/InP optical cavity having a footprint less than 24 cm2.

  12. Molecular-orbital and structural descriptors in theoretical investigation of electroreduction of nitrodiazoles

    Directory of Open Access Journals (Sweden)

    BRANKO KOLARIC

    2005-07-01

    Full Text Available It is shown how a simple theoretical approach can be used for the investigation of electro-organic reactions.Mononitroimidazoles and mononitropyrazoles were studied by the semiempirical MNDO-PM3 molecular orbital method. The electrochemical reduction potentials of diazoles have been correlated with the energy of the lowest unoccupied molecular orbital (LUMO. It was found that an admirable correlation could be obtained by the introduction of simple structural descriptors as a correction to the energy of the LUMO. The interaction of a molecule with its surrounding depends on electrostatic potential and on steric hindrance. Most of these steric effects are taken into account using two parameters having a very limited set of integer values. The first (b is the position of a ring substituent regarding ring nitrogens, which accounts for the different orientations of dipole moments and for the different shape of the electrostatic potential. The second (structural parameter (t is the type of the ring, which accounts mostly for different modes of electrode approach, and for different charge polarization patterns in two diazole rings. The extended correlation with ELUMO, b and t, is very good, having a regression coefficient r = 0.991. The intrinsic importance of b and t is exemplified by their high statistical weight.

  13. Experimental and theoretical investigation of sorption kinetics of beryllium on Amberlite-IR-120 sorbent

    Energy Technology Data Exchange (ETDEWEB)

    Othman, Sameh H. [Nuclear Research Center, Atomic Energy Authority, Cairo (Egypt); Shabaan, M.; Demerdash, M. [Nuclear Materials Authority, Cairo (Egypt); Saleh, Mahmoud M., E-mail: mahmoudsaleh90@yahoo.co [Chemistry Dept., Faculty of science, Cairo University, Cairo (Egypt)

    2009-08-01

    Experimental and theoretical studies of the sorption kinetics of beryllium cation from its synthetic solution on amberlite IR-120 (Amb-IR-120) sorbent was achieved at different temperatures. The dependence of the sorption kinetic parameters on the temperature of the solution has been investigated. The pH of solution and agitation speed had dramatic effects on the uptake of Be by Amb-IR-120. It was found that pH in the range of 3-3.5 and agitation speed of 150 rpm are proper conditions of Be sorption at the present experimental set. The fit of experimental data with the homogeneous diffusion model (HDM) equations demonstrated the possibility of using this model for adequate description of the beryllium sorption kinetics on the Amb-IR-120 sorbent. Two stages of adsorption with different controlling processes were proposed. Liquid film diffusion controls the process at the early stage of the adsorption followed by matrix diffusion which controls the process in the final stage. Two different equations were used to express each stage.

  14. Theoretical and experimental investigation of acoustic streaming in a porous material.

    Science.gov (United States)

    Poesio, Pietro; Ooms, Gijs; Schraven, Arthur; van der Bas, Fred

    2002-07-01

    An experimental and theoretical investigation of the influence of high-frequency acoustic waves on the flow of a liquid through a porous material has been made. Particular attention was paid to the phenomenon of acoustic streaming of the liquid in the porous material due to the damping of the acoustic waves. The experiments were performed on Berea sandstone cores. Two acoustic horns were used with frequencies of 20 and 40 kHz, and with maximum power output of 2 and 0.7 kW, respectively. A high external pressure was applied in order to avoid cavitation. A microphone was used to measure the damping of the waves in the porous material and also temperature and pressure measurements in the flowing liquid inside the cores were carried out. To model the acoustic streaming effect Darcy's law was extended with a source term representing the momentum transfer from the acoustic waves to the liquid. The model predictions for the pressure distribution inside the core under acoustic streaming conditions are in reasonable agreement with the experimental data. PMID:12241483

  15. Structural, electronic and optical properties of Cu-doped ZnO: experimental and theoretical investigation

    Science.gov (United States)

    Horzum, S.; Torun, E.; Serin, T.; Peeters, F. M.

    2016-06-01

    Experiments are supplemented with ab initio density functional theory (DFT) calculations in order to investigate how the structural, electronic and optical properties of zinc oxide (ZnO) thin films are modified upon Cu doping. Changes in characteristic properties of doped thin films, that are deposited on a glass substrate by sol-gel dip coating technique, are monitored using X-ray diffraction (XRD) and UV measurements. Our ab initio calculations show that the electronic structure of ZnO can be well described by DFT+U/? method and we find that Cu atom substitutional doping in ZnO is the most favourable case. Our XRD measurements reveal that the crystallite size of the films decrease with increasing Cu doping. Moreover, we determine the optical constants such as refractive index, extinction coefficient, optical dielectric function and optical energy band gap values of the films by means of UV-Vis transmittance spectra. The optical band gap of ZnO the thin film linearly decreases from 3.25 to 3.20 eV at 5% doping. In addition, our calculations reveal that the electronic defect states that stem from Cu atoms are not optically active and the optical band gap is determined by the ZnO band edges. Experimentally observed structural and optical results are in good agreement with our theoretical results.

  16. Experimental and theoretical investigation of the lateral Casimir force between corrugated surfaces

    International Nuclear Information System (INIS)

    The lateral Casimir force acting between a sinusoidally corrugated gold plate and sphere was calculated and measured. The experimental setup was based on the atomic force microscope specially adapted for the measurement of the lateral Casimir force. The measured force oscillates sinusoidally as a function of the phase difference between the two corrugations. Both systematic and random errors are analyzed and a lateral force amplitude of 3.2x10-13 N was measured at a separation distance of 221 nm with a resulting relative error 24% at a 95% confidence probability. The dependence of the measured lateral force amplitude on separation was investigated and shown to be consistent with the inverse fourth power distance dependence. The complete theory of the lateral Casimir force is presented including finite conductivity and roughness corrections. The obtained theoretical dependence was analyzed as a function of surface separation, corrugation amplitudes, phase difference, and plasma wavelength of a metal. The theory was compared with the experimental data and shown to be in good agreement. The constraints on hypothetical Yukawa-type interactions following from the measurements of the lateral Casimir force are calculated. The possible applications of the lateral vacuum forces to nanotechnology are discussed

  17. A theoretical investigation of gas phase NO 3 initiated nitration of p-cresol

    Science.gov (United States)

    Jessen, Carina Ebbesen; Gross, Allan; Kongsted, Jacob; Jørgensen, Solvejg

    2011-11-01

    The reaction mechanisms for nitration of p-cresol (4-methylphenol) initiated by the NO 3 radical are investigated theoretically. We have considered two reaction mechanisms: addition-elimination and hydrogen abstraction. Density functional theory methods employing the B3LYP and BB1K exchange-correlation functionals combined with the basis set 6-311+G(d,p) were employed for the geometry optimization of the stationary points along the reaction path. The energies have been refined using the coupled cluster singles and doubles method including a perturbative correction due to triples excitations (CCSD(T)). The barrier heights for these reaction paths are calculated in order to identify the reaction channel. The reaction path where the NO 3 radical is added to the C1 position and the NO 2 radical to the C2 position has the lowest energy barrier for the elimination of the HNO 3 and the transition state is better stabilized than any of the other transition states describing elimination.

  18. Rheological investigations on the theoretical predicted “Poisoning” effect in bidisperse ferrofluids

    Energy Technology Data Exchange (ETDEWEB)

    Siebert, E. [Chair of Magnetofluiddynamics, Measuring and Automation Technology, Technische Universität Dresden (Germany); Dupuis, V.; Neveu, S. [Sorbonne Universités, UPMC Univ Paris 06, UMR 8234, PHENIX, F-75005 Paris (France); CNRS, UMR 8234, PHENIX, F-75005 Paris (France); Odenbach, S., E-mail: stefan.odenbach@tu-dresden.de [Chair of Magnetofluiddynamics, Measuring and Automation Technology, Technische Universität Dresden (Germany)

    2015-01-15

    Interparticle interactions in ferrofluids especially the influence of small particles on the agglomeration behaviour of large particles were the topic of numerous theoretical predictions and simulations as well as of experimental investigations. In this context the “Poisoning” effect describes the decrease of the magnetoviscous effect in the presence of small particles in a bidisperse model fluid. In order to examine this effect rheological experiments have been carried out by means of a specially designed rheometer, which allows measurements under the influence of an applied magnetic field. We were able to synthesize ferrofluids with a narrow particle size distribution containing only small or large cobalt ferrite nanoparticles, which were mixed to receive various bidisperse fluid samples. With these fluids changes of the viscous behaviour in a magnetic field have been measured and compared according to their individual compositions. - Highlights: • Two ferrofluids containing either large or small particles were synthesized. • The “Poisoning” effect is not present in the observed fluid compositions. • The magnetoviscous effect increases with rising amount of small particles. • The usual shear thinning behaviour is suppressed by the presence of small particles. • The small particle influence parameter (SPIP) is introduced.

  19. Theoretical investigation of polymer chain stability in the metal coordinated azorubine and cyclam complex

    International Nuclear Information System (INIS)

    Highlights: • Ni(II)- and Zn(II)-coordinated cyclam–azorubine complexes are described using DFT. • Ni(II) coordinated system shows a reasonably small singlet–triplet energy gap. • Intersystem crossing gives high barrier between singlet and triplet geometries. • For the Zn(II) case only the singlet state is energetically favorable. • The stability of a longer polymer (oligomer) chain was described using DFTB. - Abstract: Theoretical investigations have been performed for unit systems with Ni(II) and Zn(II) coordination between azorubine and 1,4,8,11-tetraazacyclotetradecane (cyclam) complexes using the conventional DFT and the DFT-based tight binding (DFTB) methods. Two different geometries (short and long) and spin states (singlet and triplet) of the model system built by two mesylate groups and the cyclam ring together with Ni(II) and Zn(II) ions were energetically characterized. For the Ni(II) coordination complex the triplet geometry is preferred, but one could not exclude also the presence of the singlet spin configuration due to the huge energy barrier defined by the intersystem crossing. The intersystem crossing geometry of the singlet–triplet transition was studied in details and the corresponding spin–orbit couplings were discussed. For the Zn(II) coordination complex only the singlet state was found. Polymer chain build up from four unit systems presents irregular forms with strong coordination bonds between units

  20. Theoretical and experimental investigation of acoustic streaming in a porous material

    Science.gov (United States)

    Poesio, Pietro; Ooms, Gijs; Schraven, Arthur; van der Bas, Fred

    2002-07-01

    An experimental and theoretical investigation of the influence of high-frequency acoustic waves on the flow of a liquid through a porous material has been made. Particular attention was paid to the phenomenon of acoustic streaming of the liquid in the porous material due to the damping of the acoustic waves. The experiments were performed on Berea sandstone cores. Two acoustic horns were used with frequencies of 20 and 40 kHz, and with maximum power output of 2 and 0.7 kW, respectively. A high external pressure was applied in order to avoid cavitation. A microphone was used to measure the damping of the waves in the porous material and also temperature and pressure measurements in the flowing liquid inside the cores were carried out. To model the acoustic streaming effect Darcy's law was extended with a source term representing the momentum transfer from the acoustic waves to the liquid. The model predictions for the pressure distribution inside the core under acoustic streaming conditions are in reasonable agreement with the experimental data.

  1. Experimental and theoretical investigation of the drilling of alumina ceramic using Nd:YAG pulsed laser

    Science.gov (United States)

    Hanon, M. M.; Akman, E.; Genc Oztoprak, B.; Gunes, M.; Taha, Z. A.; Hajim, K. I.; Kacar, E.; Gundogdu, O.; Demir, A.

    2012-06-01

    Alumina ceramics have found wide range of applications from semiconductors, communication technologies, medical devices, automotive to aerospace industries. Processing of alumina ceramics is rather difficult due to its high degree of brittleness, hardness, low thermal diffusivity and conductivity. Rapid improvements in laser technologies in recent years make the laser among the most convenient processing tools for difficult-to-machine materials such as hardened metals, ceramics and composites. This is particularly evident as lasers have become an inexpensive and controllable alternative to conventional hole drilling methods. This paper reports theoretical and experimental results of drilling the alumina ceramic with thicknesses of 5 mm and 10.5 mm using milisecond pulsed Nd:YAG laser. Effects of the laser peak power, pulse duration, repetition rate and focal plane position have been determined using optical and Scanning Electron Microscopy (SEM) images taken from cross-sections of the drilled alumina ceramic samples. In addition to dimensional analysis of the samples, microstructural investigations have also been examined. It has been observed that, the depth of the crater can be controlled as a function of the peak power and the pulse duration for a single laser pulse application without any defect. Crater depth can be increased by increasing the number of laser pulses with some defects. In addition to experimental work, conditions have been simulated using ANYS FLUENT package providing results, which are in good agreement with the experimental results.

  2. Theoretical investigation of isotope exchange reaction in tritium-contaminated mineral oil in vacuum pump

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Liang; Xie, Yun [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Du, Liang [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); School of Radiation Medicine and Protection (SRMP), School for Radiological and Interdisciplinary Sciences (RAD-X), Suzhou 215000 (China); Li, Weiyi [School of Physics and Chemistry, Xihua University, Chengdu 610065 (China); Tan, Zhaoyi, E-mail: zhyitan@126.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2015-04-28

    Highlights: • This is the first theoretical investigation about T–H exchange in vacuum oil. • T–H isotope exchange is accomplished through two different change mechanisms. • Isotope exchange is selective, molecules with −OH and −COOH exchange more easily. • The methyl and methylene radicals in waste oil were observed by {sup 1}HNMR. - Abstract: The mechanism of the isotope exchange reaction between molecular tritium and several typical organic molecules in vacuum pump mineral oil has been investigated by density functional theory (DFT), and the reaction rates are determined by conventional transition state theory (TST). The tritium–hydrogen isotope exchange reaction can proceed with two different mechanisms, the direct T–H exchange mechanism and the hyrogenation–dehydrogenation exchange mechanism. In the direct exchange mechanism, the titrated product is obtained through one-step via a four-membered ring hydrogen migration transition state. In the hyrogenation–dehydrogenation exchange mechanism, the T–H exchange could be accomplished by the hydrogenation of the unsaturated bond with tritium followed by the dehydrogenation of HT. Isotope exchange between hydrogen and tritium is selective, and oil containing molecules with −OH and −COOH groups can more easily exchange hydrogen for tritium. For aldehydes and ketones, the ability of T–H isotope exchange can be determined by the hydrogenation of T{sub 2} or the dehydrogenation of HT. The molecules containing one type of hydrogen provide a single product, while the molecules containing different types of hydrogens provide competitive products. The rate constants are presented to quantitatively estimate the selectivity of the products.

  3. Theoretical and experimental investigation of plate screen mesh heat pipe solar collector

    International Nuclear Information System (INIS)

    Highlights: • Experimental and computer simulation are performed for wicked heat pipe solar collectors. • Outdoor tests are conducted to compare its performance at different period of the year. • Modest improvement of the collector is achievement by adding fins to the condenser region. • Mesh number of heat pipe porous structure is an important factor in collector design. • Water slightly outperform methanol for such design and operating conditions. - Abstract: Heat pipes are efficient heat transfer devices for solar hot water heating systems. However, the effective downward transfer of solar energy in an integrated heat pipe system provides increased design and implementation options. There is a lack of literature about flat plate wicked assisted heat pipe solar collector, especially with the presence of finned water-cooled condenser wicked heat pipes for solar energy applications. In this paper the consequence of incorporating fins arrays into the condenser region of screen mesh heat pipe solar collector is investigated. An experimental and a transient theoretical model are conducted to compare the performances of solar heating system at different period of the year. A good agreement is shown between the model and the experiment. Two working fluids are investigated (water and methanol) and results reveal that water slightly outperforms methanol with a collector instantaneous efficiency of nearly 60%. That modest improvement is achieved by adding fins to the condenser region of the heat pipes. Results show that the collector efficiency increase as the number of fins increases (upon certain number) and reveal that the mesh number is an important factor which affect the overall collector efficiency. An optimal heat pipe mesh number of 100 meshes/in. with two layers appears to be favorable in such collectors for their design and operating conditions

  4. Theoretical investigation of isotope exchange reaction in tritium-contaminated mineral oil in vacuum pump

    International Nuclear Information System (INIS)

    Highlights: • This is the first theoretical investigation about T–H exchange in vacuum oil. • T–H isotope exchange is accomplished through two different change mechanisms. • Isotope exchange is selective, molecules with −OH and −COOH exchange more easily. • The methyl and methylene radicals in waste oil were observed by 1HNMR. - Abstract: The mechanism of the isotope exchange reaction between molecular tritium and several typical organic molecules in vacuum pump mineral oil has been investigated by density functional theory (DFT), and the reaction rates are determined by conventional transition state theory (TST). The tritium–hydrogen isotope exchange reaction can proceed with two different mechanisms, the direct T–H exchange mechanism and the hyrogenation–dehydrogenation exchange mechanism. In the direct exchange mechanism, the titrated product is obtained through one-step via a four-membered ring hydrogen migration transition state. In the hyrogenation–dehydrogenation exchange mechanism, the T–H exchange could be accomplished by the hydrogenation of the unsaturated bond with tritium followed by the dehydrogenation of HT. Isotope exchange between hydrogen and tritium is selective, and oil containing molecules with −OH and −COOH groups can more easily exchange hydrogen for tritium. For aldehydes and ketones, the ability of T–H isotope exchange can be determined by the hydrogenation of T2 or the dehydrogenation of HT. The molecules containing one type of hydrogen provide a single product, while the molecules containing different types of hydrogens provide competitive products. The rate constants are presented to quantitatively estimate the selectivity of the products

  5. Experimental investigation of liquid chromatography columns by means of computed tomography

    DEFF Research Database (Denmark)

    Astrath, D.U.; Lottes, F.; Vu, Duc Thuong;

    2007-01-01

    The efficiency of packed chromatographic columns was investigated experimentally by means of computed tomography (CT) techniques. The measurements were carried out by monitoring tracer fronts in situ inside the chromatographic columns. The experimental results were fitted using the equilibrium di...

  6. Surface charge and interfacial potential of titanium dioxide nanoparticles: experimental and theoretical investigations.

    Science.gov (United States)

    Holmberg, Jenny Perez; Ahlberg, Elisabet; Bergenholtz, Johan; Hassellöv, Martin; Abbas, Zareen

    2013-10-01

    Size dependent surface charging and interfacial potential of titanium dioxide (TiO2) nanoparticles are investigated by experimental and theoretical methods. Commercially available TiO2 (P25) nanoparticles were used for surface charge determinations by potentiometric titrations. Anatase particles, 10 and 22 nm in diameter, were synthesized by controlled hydrolysis of TiCl4, and electrophoretic mobilities were determined at a fixed pH but at increasing salt concentrations. Corrected Debye-Hückel theory of surface complexation (CDH-SC) was modified to model the size dependent surface charging behavior of TiO2 nanoparticles. Experimentally determined surface charge densities of rutile and P25 nanoparticles in different electrolytes were accurately modeled by the CDH-SC theory. Stern layer capacitances calculated by the CDH-SC theory were in good agreement with the values found by the classical surface complexation approach, and the interaction of protons with OH groups is found to be less exothermic than for iron oxide surfaces. Moreover, the CDH-SC theory predicts that the surface charge density of TiO2 nanoparticles of diameter point of zero charge (pHPZC) shifts to higher pH values as the particle size decreases. The importance of including the particle size in calculating the zeta potentials from mobilities is demonstrated. Smoluchowski theory showed that 10nm particles had lower zeta potential than 22 nm particles, whereas a reverse trend was seen when zeta potentials were calculated by Ohshima's theory in which particle size is included. Electrokinetic charge densities calculated from zeta potentials were found to be only one third of the true surface charge densities. PMID:23859811

  7. Experimental and theoretical investigations of the adhesion time of Penicillium spores to cedar wood surface

    Energy Technology Data Exchange (ETDEWEB)

    Soumya, Elabed [Laboratoire de Biotechnologie Microbienne, Faculté des Sciences et Techniques de Fès-Saïs (Morocco); Université Sidi Mohamed Ben Abdellah, Centre Universitaire Régional d' Interface-Fès (Morocco); Saad, Ibnsouda Koraichi, E-mail: ibnsouda@hotmail.com [Laboratoire de Biotechnologie Microbienne, Faculté des Sciences et Techniques de Fès-Saïs (Morocco); Université Sidi Mohamed Ben Abdellah, Centre Universitaire Régional d' Interface-Fès (Morocco); Abdellah, Houari [Laboratoire de Biotechnologie Microbienne, Faculté des Sciences et Techniques de Fès-Saïs (Morocco); Hassan, Latrache [Laboratoire de Valorisation et de Sécurité des Produits Agroalimentaires, Faculté des Sciences et Techniques de Beni Mellal (Morocco)

    2013-04-01

    In this study, the adhesion of 4 Penicillium strains (Penicillium granulatum, Penicillium crustosum, Penicillium commune and Penicillium chrysogenum) on cedar wood was examined qualitatively and quantitatively by using the extended DLVO (XDLVO) approach and the environmental scanning electronic microscopy (ESEM) technique. A comparison between the XDLVO theories and the ESEM technique was also investigated. The adhesion tests revealed that P. chrysogenum was not able to adhere on the cedar wood substrata, as predicted by the XDLVO approach. We have also found by ESEM that the three Penicillium strains (P. granulatum, P. crustosum, P. commune) adhered on wood, as not predicted theoretically. Moreover, the time of adhesion (3 h and 24 h) was used not only to compare the capacity of adhesion according to contact time but also to explain the discrepancies between the XDLVO approach prediction and the adhesion experiments. A positive relationship between the XDLVO approach and adhesion experiments has been observed after 3 h of adhesion. In contrast, a contradiction between the XDLVO predictions and the adhesion test results has been noted after 24 h of adhesion of Penicillium strains to the wood surface. Highlights: ► Calculation of free energy of adhesion to cedar wood of Penicillium by XDLVO approach ► Adhesion is not favorable for all Penicillium spores–cedar wood combinations. ► Adhesion tests demonstrated the ability of Penicillium spores to adhere to cedar wood. ► XDLVO approach correlated well with the results obtained after 3 h of adhesion. ► Discrepancy between XDLVO predictions and experimental observations at 24 h of adhesion.

  8. Experimental and Theoretical Investigations of Reaction-Coupled Flow and Transport in Porous Media

    Science.gov (United States)

    Kim, J.; Schwartz, F. W.

    2004-12-01

    In some systems, it is possible to observe complex patterns of coupling between fluid and flow and mass transport when reactions involving a solid phase are operative. For example, dissolution and precipitation reactions can change a porous medium's physical properties such as porosity and permeability. These changes influence fluid flow, which affect the concentration of dissolved solids, the composition of solid phases, and the rate and direction of advective transport. Both experimental and modeling studies were conducted to investigate the coupling between flow and transport due to effects of fluid density, dissolution/precipitation reactions, and heterogeneity in medium properties. The complex chemical system is created by pumping a dilute Fe(ClO4)3 solution through a medium created by mixing glass beads and crushed calcite. Fe3+ rapidly hydrolyzes to produce hydroxo complexes and H+. As pH increases through reaction with calcite, a poorly crystallized solid, ferric oxyhydroxide precipitates. Two-dimensional flow tank studies are use to verify a novel modeling approach. In the model, there is full coupling of flow and transport due to permeability changes from dissolution/precipitation reactions. Further, TOUGHREACT is used to study reaction-front dynamics, and how the aqueous phase concentrations depend upon this pattern of evolution. Both the experimental and theoretical results highlight the complexity of coupling in systems with heterogeneous reactions. The important implication of this study is that details of interactions between pore fluid and the porous medium need to be well characterized in order to predict the changing aqueous concentrations.

  9. Does Prop-2-ynylideneamine, HC≡CCH=NH, Exist in Space? A Theoretical and Computational Investigation

    Directory of Open Access Journals (Sweden)

    Osman I. Osman

    2014-06-01

    Full Text Available MP2, DFT and CCSD methods with 6-311++G** and aug-cc-pvdz basis sets have been used to probe the structural changes and relative energies of E-prop-2-ynylideneamine (I, Z-prop-2-ynylideneamine (II, prop-1,2-diene-1-imine (III and vinyl cyanide (IV. The energy near-equivalence and provenance of preference of isomers and tautomers were investigated by NBO calculations using HF and B3LYP methods with 6-311++G** and aug-cc-pvdz basis sets. All substrates have Cs symmetry. The optimized geometries were found to be mainly theoretical method dependent. All elected levels of theory have computed I/II total energy of isomerization (ΔE of 1.707 to 3.707 kJ/mol in favour of II at 298.15 K. MP2 and CCSD methods have indicated clearly the preference of II over III; while the B3LYP functional predicted nearly similar total energies. All tested levels of theory yielded a global II/IV tautomerization total energy (ΔE of 137.3–148.4 kJ/mol in support of IV at 298.15 K. The negative values of ΔS indicated that IV is favoured at low temperature. At high temperature, a reverse tautomerization becomes spontaneous and II is preferred. The existence of II in space was debated through the interpretation and analysis of the thermodynamic and kinetic studies of this tautomerization reaction and the presence of similar compounds in the Interstellar Medium (ISM.

  10. DNA quadruplexes: from monomers to nanoscale self-assemblies, theoretical and spectroscopic investigation

    Czech Academy of Sciences Publication Activity Database

    Andrushchenko, Valery; Tsankov, D.; Krasteva, M.; Wieser, H.; Bouř, Petr

    Kharkov, 2009. s. 35-35. [International Conference. Nanobiophysics: Fundamental and Applied Aspects. 05.10.2009-08.10.2009, Kharkov] Institutional research plan: CEZ:AV0Z40550506 Keywords : GMP * IR * VCD Subject RIV: CF - Physical ; Theoretical Chemistry

  11. Applying 'Sequential Windowed Acquisition of All Theoretical Fragment Ion Mass Spectra' (SWATH) for systematic toxicological analysis with liquid chromatography-high-resolution tandem mass spectrometry.

    Science.gov (United States)

    Arnhard, Kathrin; Gottschall, Anna; Pitterl, Florian; Oberacher, Herbert

    2015-01-01

    Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has become an indispensable analytical technique in clinical and forensic toxicology for detection and identification of potentially toxic or harmful compounds. Particularly, non-target LC-MS/MS assays enable extensive and universal screening requested in systematic toxicological analysis. An integral part of the identification process is the generation of information-rich product ion spectra which can be searched against libraries of reference mass spectra. Usually, 'data-dependent acquisition' (DDA) strategies are applied for automated data acquisition. In this study, the 'data-independent acquisition' (DIA) method 'Sequential Windowed Acquisition of All Theoretical Fragment Ion Mass Spectra' (SWATH) was combined with LC-MS/MS on a quadrupole-quadrupole-time-of-flight (QqTOF) instrument for acquiring informative high-resolution tandem mass spectra. SWATH performs data-independent fragmentation of all precursor ions entering the mass spectrometer in 21m/z isolation windows. The whole m/z range of interest is covered by continuous stepping of the isolation window. This allows numerous repeat analyses of each window during the elution of a single chromatographic peak and results in a complete fragment ion map of the sample. Compounds and samples typically encountered in forensic casework were used to assess performance characteristics of LC-MS/MS with SWATH. Our experiments clearly revealed that SWATH is a sensitive and specific identification technique. SWATH is capable of identifying more compounds at lower concentration levels than DDA does. The dynamic range of SWATH was estimated to be three orders of magnitude. Furthermore, the >600,000 SWATH spectra matched led to only 408 incorrect calls (false positive rate = 0.06 %). Deconvolution of generated ion maps was found to be essential for unravelling the full identification power of LC-MS/MS with SWATH. With the available software, however, only semi

  12. Investigation of use of another person’s and counterfeit payment cards: the theoretical and methodological aspects

    OpenAIRE

    Aleksandrs Berezins

    2014-01-01

    Abstract The central research subject of Doctoral Thesis "Investigation of use of another person’s and counterfeit payment cards: the theoretical and methodological aspects" is two-sided and formed of the mechanism of use of another person’s and counterfeit payment cards and the mechanism for investigating such type of crime. On the basis of the results of finding out the regularities of the mentioned subjects, the author proposes specific recommendations for investigating t...

  13. Investigation of the applicability of polyHIPE materials in liquid chromatography

    OpenAIRE

    Choudhury, Sidratul

    2016-01-01

    Polymer monoliths have gained significant interest as stationary phase materials over the last 25 years. More recently, enthusiasm for polymer high internal phase emulsions (polyHIPEs) in chromatographic separations has grown, primarily due to their large pore sizes (greater than 10 µm), which make polyHIPEs highly permeable and ideal for high flow rate separations. In this study, the applicability of polyHIPE materials as stationary phase materials was investigated and novel methods to incre...

  14. The impact on CT dose of the variability in tube current modulation technology: a theoretical investigation

    International Nuclear Information System (INIS)

    Body CT scans are routinely performed using tube-current-modulation (TCM) technology. There is notable variability across CT manufacturers in terms of how TCM technology is implemented. Some manufacturers aim to provide uniform image noise across body regions and patient sizes, whereas others aim to provide lower noise for smaller patients. The purpose of this study was to conduct a theoretical investigation to understand how manufacturer-dependent TCM scheme affects organ dose, and to develop a generic approach for assessing organ dose across TCM schemes. The adult reference female extended cardiac-torso (XCAT) phantom was used for this study. A ray-tracing method was developed to calculate the attenuation of the phantom for a given projection angle based on phantom anatomy, CT system geometry, x-ray energy spectrum, and bowtie filter filtration. The tube current (mA) for a given projection angle was then calculated as a log-linear function of the attenuation along that projection. The slope of this function, termed modulation control strength, α, was varied from 0 to 1 to emulate the variability in TCM technology. Using a validated Monte Carlo program, organ dose was simulated for five α values (α = 0, 0.25, 0.5, 0.75, and 1) in the absence and presence of a realistic system mA limit. Organ dose was further normalized by volume-weighted CT dose index (CTDIvol) to obtain conversion factors (h factors) that are relatively independent of system specifics and scan parameters. For both chest and abdomen-pelvis scans and for 24 radiosensitive organs, organ dose conversion factors varied with α, following second-order polynomial equations. This result suggested the need for α-specific organ dose conversion factors (i.e., conversion factors specific to the modulation scheme used). On the other hand, across the full range of α values, organ dose in a TCM scan could be derived from the conversion factors established for a fixed-mA scan (hFIXED). This was possible by

  15. Theoretical and experimental investigation of the drift velocity in AlGaAs/GaAs heterostructures

    Science.gov (United States)

    Zandler, G.; Kiener, C.; Boxleitner, W.; Vass, E.; Wirner, C.; Gornik, E.; Weimann, G.

    1991-12-01

    The drift velocity of hot electrons in AlGaAs/GaAs heterostructures is measured at different temperatures by a pulsed I-V technique up to electric fields of 1.2 kV/cm. The experimental results are compared with theoretical drift velocities deduced from the Boltzmann integral equation and a balance equation method. The calculations are carried out with selfconsistent and Stern-Howard wave functions taking into account polar optical phonon and ionized impurity scattering as well as electron-electron collisions. At low field strengths both theoretical methods lead to drift velocities which are in good agreement with the experimental data. It is shown that for higher lattice temperatures and higher electric field strengths intersubband scattering has to be taken into account in the theoretical models.

  16. Investigation of acoustic gravity waves created by anomalous heat sources: experiments and theoretical analysis

    Science.gov (United States)

    Pradipta, R.; Lee, M. C.

    2013-07-01

    We have been investigating high-power radio wave-induced acoustic gravity waves (AGWs) at Gakona, Alaska, using the High-frequency Active Aurora Research Program (HAARP) heating facility (i.e. HF heater) and extensive diagnostic instruments. This work was aimed at performing a controlled study of the space plasma turbulence triggered by the AGWs originating from anomalous heat sources, as observed in our earlier experiments at Arecibo, Puerto Rico (Pradipta 2007 MS Thesis MIT Press, Cambridge, MA). The HF heater operated in continuous wave (CW) O-mode can heat ionospheric plasmas effectively to yield a depleted magnetic flux tube as rising plasma bubbles (Lee et al 1998 Geophys. Res. Lett. 25 579). Two processes are responsible for the depletion of the magnetic flux tube: (i) thermal expansion and (ii) chemical reactions caused by heated ions. The depleted plasmas create large density gradients that can augment spread F processes via generalized Rayleigh-Taylor instabilities (Lee et al 1999 Geophys. Res. Lett. 26 37). It is thus expected that the temperature of neutral particles in the heated ionospheric region can be increased. Such a heat source in the neutral atmosphere may potentially generate AGWs in the form of traveling ionospheric plasma disturbances (TIPDs). We should point out that these TIPDs have features distinctively different from electric and magnetic field (ExB) drifts of HF wave-induced large-scale non-propagating plasma structures. Moreover, it was noted in our recent study of naturally occurring AGW-induced TIDs that only large-scale AGWs can propagate upward to reach higher altitudes. Thus, in our Gakona experiments we select optimum heating schemes for HF wave-induced AGWs that can be distinguished from the naturally occurring ones. The generation and propagation of AGWs are monitored by MUIR (Modular Ultra high-frequency Ionospheric Radar), Digisonde and GPS/low-earth-orbit satellites. Our theoretical and experimental studies have shown that

  17. EXPERIMENTAL AND THEORETICAL INVESTIGATIONS OF NEW POWER CYCLES AND ADVANCED FALLING FILM HEAT EXCHANGERS

    Energy Technology Data Exchange (ETDEWEB)

    Arsalan Razani; Kwang J. Kim

    2000-10-28

    The annual progress report for the period of October 1, 1999 to September 30, 2000 on DOE/UNM grant number DE-FG26-98FT40148 discusses the progress on both the theoretical analysis of advanced power cycles and the experimental investigation of advanced falling film heat exchangers. The previously developed computer program for the triple cycle, based on the air standard cycle assumption, was modified to include actual air composition (%77.48 N{sub 2}, %20.59 O{sub 2}, %1.9 H{sub 2}O, and %0.03 CO{sub 2}). The actual combustion products were used in exergy analysis of the triple cycle. The effect of steam injection into the combustion chamber on its irreversibility, and the irreversibility of the entire cycle, was evaluated. A more practical fuel inlet condition and a better position of the feedwater heater in the steam cycle were used in the modified cycle. The effect of pinch point and the temperature difference between the combustion products, as well as the steam in the heat recovery steam generator on irreversibility of the cycle were evaluated. Design, construction, and testing of the multitube horizontal falling film condenser facility were completed. Two effective heat transfer additives (2-ethyl-1-hexanol and alkyl amine) were identified and tested for steam condensation. The test results are included. The condenser was designed with twelve tubes in an array of three horizontals and four verticals, with a 2-inch horizontal and 1.5-inch vertical in-line pitch. By using effective additives, the condensation heat transfer rate can be augmented as much as 30%, as compared to a heat transfer that operated without additives under the same operating condition. When heat transfer additives function effectively, the condensate-droplets become more dispersed and have a smaller shape than those produced without additives. These droplets, unlike traditional turbulence, start at the top portion of the condenser tubes and cover most of the tubes. Such a flow behavior can

  18. Investigation of acoustic gravity waves created by anomalous heat sources: experiments and theoretical analysis

    International Nuclear Information System (INIS)

    We have been investigating high-power radio wave-induced acoustic gravity waves (AGWs) at Gakona, Alaska, using the High-frequency Active Aurora Research Program (HAARP) heating facility (i.e. HF heater) and extensive diagnostic instruments. This work was aimed at performing a controlled study of the space plasma turbulence triggered by the AGWs originating from anomalous heat sources, as observed in our earlier experiments at Arecibo, Puerto Rico (Pradipta 2007 MS Thesis MIT Press, Cambridge, MA). The HF heater operated in continuous wave (CW) O-mode can heat ionospheric plasmas effectively to yield a depleted magnetic flux tube as rising plasma bubbles (Lee et al 1998 Geophys. Res. Lett. 25 579). Two processes are responsible for the depletion of the magnetic flux tube: (i) thermal expansion and (ii) chemical reactions caused by heated ions. The depleted plasmas create large density gradients that can augment spread F processes via generalized Rayleigh–Taylor instabilities (Lee et al 1999 Geophys. Res. Lett. 26 37). It is thus expected that the temperature of neutral particles in the heated ionospheric region can be increased. Such a heat source in the neutral atmosphere may potentially generate AGWs in the form of traveling ionospheric plasma disturbances (TIPDs). We should point out that these TIPDs have features distinctively different from electric and magnetic field (ExB) drifts of HF wave-induced large-scale non-propagating plasma structures. Moreover, it was noted in our recent study of naturally occurring AGW-induced TIDs that only large-scale AGWs can propagate upward to reach higher altitudes. Thus, in our Gakona experiments we select optimum heating schemes for HF wave-induced AGWs that can be distinguished from the naturally occurring ones. The generation and propagation of AGWs are monitored by MUIR (Modular Ultra high-frequency Ionospheric Radar), Digisonde and GPS/low-earth-orbit satellites. Our theoretical and experimental studies have shown

  19. Theoretical investigations of the structures and electronic spectra of 8-hydroxylquinoline derivatives

    Science.gov (United States)

    Ning, Pan; Ren, Tiegang; Zhang, Yanxin; Zhang, Jinglai

    2013-11-01

    The spectroscopic properties of 8-hydroxyquinoline derivatives are theoretically investigated by means of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The target molecules are divided into two groups: group (I): (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)quinolin-8-ol (A), together with corresponding potential reaction products of A with acetic acid, i.e., (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)quinolin-8-yl acetate (AR1), and (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)-8-hydroxyquinolinium (AR2); group (II): (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)quinolin-8-ol (B), as well as potential reaction products of B with acetic acid, i.e., (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)quinolin-8-yl acetate (BR1), and (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)-8-hydroxyquinolinium (BR2). The geometries are optimized by B3LYP and M06 methods. The results indicate that product molecules tend to be effectively planar compared with reactants. Subsequently, UV absorption spectra are simulated through TD-DFT method with PCM model to further confirm the reasonable products of two reactions. AR2 and BR2 are identified as the target molecules through the experimental spectra for the real products. It is worth noting that the maximum absorption wavelengths of compounds AR2 and BR2 present prominent red shift compared the initial reactants A and B, respectively, which should be ascribed to the enhancive planarity of products that mentioned above and the decreased HOMO-LUMO energy gap. Geometric structures and optical properties for corresponding compounds are discussed in detail.

  20. Theoretical investigation of zero field splitting parameter of Cr3+ doped diammonium hexaaqua magnesium sulfate

    International Nuclear Information System (INIS)

    The zero field splitting parameter D of Cr3+ doped diammonium hexaaqua magnesium sulfate (DHMS) are calculated with perturbation formula using crystal field (CF) parameters from superposition model. The theoretically calculated ZFS parameters for Cr3+ in DHMS single crystal are compared with the experimental value obtained by electron paramagnetic resonance (EPR). The theoretical ZFS parameter D is similar to that from experiment. The energy band positions of optical absorption spectra of Cr3+ doped DHMS single crystal are calculated with CFA package, which are in good match with experimental values

  1. THEORETICAL AND EXPERIMENTAL INVESTIGATIONS OF ENTRAINED AND TRANSPORTED CHARACTERISTICS OF SUBMERGED JET

    Institute of Scientific and Technical Information of China (English)

    DONG Zhi-yong; WU Chi-gong; YANG YONG-quan

    2004-01-01

    This paper presents entrainment mechanism,and transported and diffusion characteristics at the point of entry of submerged jet. The profiles of both velocity and concentration within the air-water mixing layer were theoretically deduced. And the comparisons between theoretical values and measured data were made. Results show that the velocity profile within the air-water mixing layer exhibits a form of error function. The concentrations of air entrainment in the internal and external regions of air-water mixing layer correspond to Gaussian distribution.

  2. Theoretical investigation on the magnetic and electric properties in TbSb compound through an anisotropic microscopic model

    Science.gov (United States)

    von Ranke, P. J.; Ribeiro, P. O.; Carvalho, A. Magnus G.; Alho, B. P.; Alvarenga, T. S. T.; Nobrega, E. P.; Caldas, A.; de Sousa, V. S. R.; Lopes, P. H. O.; de Oliveira, N. A.

    2016-05-01

    We report the strong correlations between the magnetoresistivity and the magnetic entropy change in the cubic antiferromagnetic TbSb compound. The theoretical investigation was performed through a microscopic model which takes into account the crystalline electrical field anisotropy, exchange coupling interactions between the up and down magnetic sublattices, and the Zeeman interaction. The easy magnetization directions changes from ⟨001⟩ to ⟨110⟩ and then to ⟨111⟩ observed experimentally was successfully theoretically described. Also, the calculation of the temperature dependence of electric resistivity showed good agreement with the experimental data. Theoretical predictions were calculated for the temperature dependence of the magnetic entropy and resistivity changes upon magnetic field variation. Besides, the difference in the spin up and down sublattices resistivity was investigated.

  3. First-Year Biology Students' Understandings of Meiosis: An Investigation Using a Structural Theoretical Framework

    Science.gov (United States)

    Quinn, Frances; Pegg, John; Panizzon, Debra

    2009-01-01

    Meiosis is a biological concept that is both complex and important for students to learn. This study aims to explore first-year biology students' explanations of the process of meiosis, using an explicit theoretical framework provided by the Structure of the Observed Learning Outcome (SOLO) model. The research was based on responses of 334…

  4. Theoretical investigation of the phonon-polariton mode in Czochralski-grown piezoelectric superlattice

    Science.gov (United States)

    Bai, Wen-Chao; Lan, Zhong-Jian; Zhang, Han-Zhuang; Zhang, Han; Jiang, Li

    2016-09-01

    The properties of phonon-polaritons in Czochralski-grown piezoelectric superlattice (CPSL), are studied theoretically. We propose the phonon-polariton mode of CPSL. The mechanism for polariton coupling is analyzed. We discuss the factors that influence the properties of the phonon-polariton. Some potential applications are also discussed.

  5. Combined TPD and theoretical investigation of CO desorption from Cu-K-FER zeolite

    Czech Academy of Sciences Publication Activity Database

    Bulánek, R.; Nachtigall, Petr; Cicmanec, P.

    2008-01-01

    Roč. 174, č. 2 (2008), s. 895-898. ISSN 0167-2991 R&D Projects: GA MŠk LC512; GA ČR GA203/06/0324 Institutional research plan: CEZ:AV0Z40550506 Keywords : zeolite * adsorption * TPD Subject RIV: CF - Physical ; Theoretical Chemistry

  6. Theoretical investigation of layered zeolite frameworks: Interaction between IPC-1P layers derived from zeolite UTL

    Czech Academy of Sciences Publication Activity Database

    Grajciar, L.; Bludský, Ota; Roth, Wieslaw Jerzy; Nachtigall, P.

    2013-01-01

    Roč. 204, Apr 15 (2013), s. 15-21. ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388963 ; RVO:61388955 Keywords : layered zeolites * density functional theory * hydrogen bonding * structure Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.309, year: 2013

  7. Theoretical investigation of layered zeolite frameworks: Surface properties of 2D zeolites

    Czech Academy of Sciences Publication Activity Database

    Hermann, Jan; Trachta, Michal; Nachtigall, P.; Bludský, Ota

    2014-01-01

    Roč. 227, May 15 (2014), s. 2-8. ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388963 Keywords : layered zeolite frameworks * surface properties * 2D zeolite s Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.893, year: 2014

  8. Theoretical Investigation of the Vibrational Dynamics of Ag+CO Solvated in the Ne Matrix

    Czech Academy of Sciences Publication Activity Database

    Šilhan, Martin; Nachtigall, Petr; Bludský, Ota

    2003-01-01

    Roč. 375, 1/2 (2003), s. 54-58. ISSN 0009-2614 R&D Projects: GA MŠk LN00A032 Institutional research plan: CEZ:AV0Z4040901 Keywords : density-functional * calculations * metal-carbonyl cations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.438, year: 2003

  9. Theoretical investigation of dinitrosyl complexes in Cu-zeolites as intermediates in deNOx process

    Czech Academy of Sciences Publication Activity Database

    Pulido, Maria Angeles; Nachtigall, Petr

    2009-01-01

    Roč. 11, č. 9 (2009), s. 1447-1458. ISSN 1463-9076 R&D Projects: GA ČR GA203/06/0324; GA MŠk LC512 Institutional research plan: CEZ:AV0Z40550506 Keywords : zeolites * deNOx * DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.116, year: 2009

  10. Investigation of drugs of abuse and relevant metabolites in Dutch sewage water by liquid chromatography coupled to high resolution mass spectrometry

    NARCIS (Netherlands)

    L. Bijlsma; E. Emke; F. Hernández; P. de Voogt

    2012-01-01

    An extensive study on the presence of illicit drugs and pharmaceuticals with potential for abuse in sewage waters was made for the first time in the Netherlands. A total number of 24 target drugs were investigated in influent and effluent wastewater using liquid chromatography coupled to a high reso

  11. Theoretical and experimental investigations of CHF in round tubes and rod bundles

    International Nuclear Information System (INIS)

    A knowledge of the condition leading to critical heat flux (CHF) is of great importance in the design of nuclear reactors. Although many efforts have been devoted to the subject of CHF during the last few decades, information on the burnout phenomenon at low velocity condition is very limited. Furthermore, in most cases, the applicable range of a bundle CHF correlation is restricted to a narrow region mainly due to the limitation of the CHF data base used in the correlation development. In view of these points, theoretical and experimental investigations are performed in this study for round tubes and rod bundles. A CHF prediction model for low velocity conditions is proposed throughout the assessment of CHF data from various sources with mass velocities less than 500 kg/m2s. The CHF data base is classified into seven groups with respect to the flow pattern characteristics at CHF conditions. CHF data for each group is analyzed by several CHF prediction models including; the flooding correlations, the flow regime transition criteria, the complete evaporation model, and the empirical correlations. At zero inlet flow or extremely low mass velocity conditions, the flooding correlation can be used for predicting CHF employing appropriate constant. In the slug or churn-turbulent flow regime, CHF seems to occur at the annular flow transition conditions. When CHF occurs at the annular flow region, the empirical correlation such as AECL CHF lookup table gives accurate predictions except for the ranges where density-wave instability is expected. A phenomenological model for the prediction of dryout locations under flooding-limited CHF condition is developed based on the liquid film dryout model and the two-phase mixture level theory. The mass and energy conservation equations are applicable to the liquid film considering no entrainment of liquid droplets from the film region. The variation of the two-phase mixture level after the onset of flooding is calculated based on the

  12. Theoretical and experimental investigation of optical absorption anisotropy in β-Ga2O3.

    Science.gov (United States)

    Ricci, F; Boschi, F; Baraldi, A; Filippetti, A; Higashiwaki, M; Kuramata, A; Fiorentini, V; Fornari, R

    2016-06-01

    The question of optical bandgap anisotropy in the monoclinic semiconductor β-Ga2O3 was revisited by combining accurate optical absorption measurements with theoretical analysis, performed using different advanced computation methods. As expected, the bandgap edge of bulk β-Ga2O3 was found to be a function of light polarization and crystal orientation, with the lowest onset occurring at polarization in the ac crystal plane around 4.5-4.6 eV; polarization along b unambiguously shifts the onset up by 0.2 eV. The theoretical analysis clearly indicates that the shift in the b onset is due to a suppression of the transition matrix elements of the three top valence bands at Γ point. PMID:26952789

  13. Theoretical and experimental investigation of optical absorption anisotropy in β-Ga2O3

    Science.gov (United States)

    Ricci, F.; Boschi, F.; Baraldi, A.; Filippetti, A.; Higashiwaki, M.; Kuramata, A.; Fiorentini, V.; Fornari, R.

    2016-06-01

    The question of optical bandgap anisotropy in the monoclinic semiconductor β-Ga2O3 was revisited by combining accurate optical absorption measurements with theoretical analysis, performed using different advanced computation methods. As expected, the bandgap edge of bulk β-Ga2O3 was found to be a function of light polarization and crystal orientation, with the lowest onset occurring at polarization in the ac crystal plane around 4.5-4.6 eV polarization along b unambiguously shifts the onset up by 0.2 eV. The theoretical analysis clearly indicates that the shift in the b onset is due to a suppression of the transition matrix elements of the three top valence bands at Γ point.

  14. THEORETICAL AND EXPERIMENTAL INVESTIGATIONS PERTAINING TO DETERMINATION OF FLUID JET PRESSURE ON TREATED FLAT SURFACE

    Directory of Open Access Journals (Sweden)

    I. Kachanov

    2014-10-01

    Full Text Available A mathematical model for  calculation of a jet power impact on a barrier consisting of a corrosive deposit layer  has been proposed on the basis of an upper-bound method and accepted assumptions. A variational problem associated with determination of a minimum destruction pressure has been solved and a theoretical dependence for pressure calculation at the point of jet-barrier collision with due account of mechanical properties of the destroyed material and kinematic jet parameters has been obtained in the paper. Comparison of experimental data obtained by means of the EDP-30 sensor with the theoretical ones has shown a divergence of 15–19 % within velocity range of the jet impact from 150 to 300 m/s.

  15. Combined Experimental and Theoretical Investigations of Heterogeneous Dual Cation Sites in Cu,M-FER Zeolites

    Czech Academy of Sciences Publication Activity Database

    Bulánek, R.; Frolich, K.; Cicmanec, P.; Nachtigallová, Dana; Pulido, A.; Nachtigall, P.

    2011-01-01

    Roč. 115, č. 27 (2011), s. 13312-13321. ISSN 1932-7447 R&D Projects: GA ČR GA203/09/0143; GA MŠk LC512 Institutional research plan: CEZ:AV0Z40550506 Keywords : augmented-wave method * high-silica zeolites * co adsorption * infrared-spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.805, year: 2011

  16. Emotion felt by the listener and expressed by the music: a literature review and theoretical investigation

    OpenAIRE

    Emery eSchubert

    2013-01-01

    In his seminal paper, Gabrielsson (2002) distinguishes between emotion felt by the listener, here: ‘internal locus of emotion’ (IL), and the emotion the music is expressing, here: 'external locus emotion' (EL). This paper tabulates 16 such publications published in the decade 2003-2012 consisting of 19 studies/experiments and provides some theoretical perspectives. The key findings were that (1) IL ratings was frequently rated statistically the same or lower than the corresponding EL...

  17. An optical and theoretical investigation of the ultrafast dynamics of a bisthienylethene-based photochromic switch

    OpenAIRE

    Hania, P. R.; Telesca, R.; Lucas, L.N.; Pugzlys, A.; Esch, J.H. van; Feringa, B.L.; Snijders, J. G.; Duppen, K

    2002-01-01

    The switching behavior of 1,2-bis(5-phenyl-2-methylthien-3-yl)cyclopentene is studied by means of polarization selective nonlinear optical spectroscopy and time-dependent density functional theory. The combined information from the observed population and orientational dynamics together with the results of theoretical calculations show that on a subpicosecond time scale rapid mixing and relaxation of electronic states occur, before switching takes place. Such preswitching dynamics was not stu...

  18. Experimental and theoretical investigations on magnetic and related properties of ErRuSi

    OpenAIRE

    Gupta, Sachin; Das, A; Suresh, K. G.; Hoser, A.; Knyazev, Yu. V.; Kuz'min, Yu. I.; Lukoyanov, A. V.

    2014-01-01

    We report experimental and theoretical studies of magnetic and related properties of ErRuSi compound. Various experimental techniques such as neutron diffraction, magnetization, magneto-thermal, magneto-transport, optical have been used to study the compound. Neutron diffraction shows ferromagnetic ordering at low temperatures with moments aligned in ab plane. Neutron diffraction and magnetization data show reduction in magnetic moment, which may be due to crystalline electric field effects a...

  19. Effective public policy which can reduce gender discrimination in the agricultural labour market: A theoretical investigation

    OpenAIRE

    Kundu, AMIT

    2013-01-01

    Wage and employment differences between male and female agricultural labourers in the under developed countries including India is not new. With the help of a simple theoretical model it is here proved that public policy like implementation of National Rural Employment Guarantee Scheme (NREGS) in the rural areas can reduce wage discrimination but fails to reduce employment discrimination in the agricultural labour market. It is also proved that implementation of NREGS not only reduces profita...

  20. Does Government Sponsored Advertising Increase Social Welfare? A Theoretical and Empirical Investigation

    OpenAIRE

    Carpio, Carlos E.; Isengildina-Massa, Olga

    2013-01-01

    The main objective of this study was to analyze the effect of advertising on social welfare in a perfectly competitive market where the level of advertising is chosen by a social planner. The theoretical model revealed that social planner sponsored advertising that increases the equilibrium price of the advertised good can increase society’s welfare if the effect of advertising in consumers’ utility is higher than the consumer welfare reducing price effect (producer welfare is increased by th...

  1. Theoretical analysis and experimental investigation of valveless piezoelectric pump with unsymmetrical ridges

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jianhui; LU Jizhuang; XIA Qixiao; LI Hong

    2007-01-01

    A novel valveless piezoelectric pump with unsymmetrical ridges is presented at first. It ingeniously uti- lizes the inner space of its chamber by developing its chamber bottom into unsymmetrical ridges along the direction of the inlet and outlet of the pump. Hence, a series of cuneiform channels are asymmetrically and alternately formed between the unsymmetrical ridges and the piezoelectric vibrator, which enables the pump to form a one-way flow instead of the func- tion of the traditional diffuse or nozzle elements fitted outside the chamber. Then, by analyzing the vibration of the piezo- electric vibrator, the vibration deformation function and the equation of volume change are established. Meanwhile, the theoretical equation of the pump flow rate is established. Finally, a real valveless piezoelectric pump with unsymmetri- cal ridges is manufactured, and the flow rate of the pump is measured through experiments. It is proved that the theory is rational and correct by comparing the experimental flow rate and the theoretical flow rate. In addition, for calculating the theoretical flow rate, the positive and converse flow resis- tance coefficients of unsymmetrical ridges are measured through experiments, when one slope angle of the unsym- metrical ridges is 90° and another is changing from 20° to 60°, respectively.

  2. Experimental and Theoretical Investigation of Impact Dynamic Plasticity for CK45

    Directory of Open Access Journals (Sweden)

    Hani Aziz Ameen

    2015-03-01

    Full Text Available The low velocity axial impact of thin-walled circular ck45 tubes is taken. The wrinkles develop progressively and the phenomenon is known as dynamic progressive buckling. In the present paper, experimental and theoretical studies on dynamic plastic buckling of circular cylindrical shells under axial impact are carried out by designing and building a device to study the behavior of ck45 under low speed impact (3.8-6.25m/s. The work consists of experimental and theoretical (Abramowicz model for the energy absorbers and dynamic load under different velocities. The results show that when the velocity of impact increases, the value of the dynamic crushing stress for ck45 will increase, also for elastoplastic collapse deformation, a tube initially goes through elastic deformation, then plastic deformation occurs, after that the tube goes through plastic collapse. As the force decreases, the displacement still increases. Abramowicz model for dynamic impact shows well coincide with discrepancy 45%. It can be indicated that the increasing in the velocity or kinetic energy leads to increase in the load in the practical part while it seems to be horizontally linear in the theoretical part.

  3. Experimental and theoretical investigation of an evaporative fuel system for heat engines

    International Nuclear Information System (INIS)

    The evaporative gas turbine (EvGT) pilot plant has been in operation at Lund University in Sweden since 1997. This project has led to improved knowledge of evaporative techniques and the concept of introducing fuel into gas turbines by evaporation. This results in, amongst others, power augmentation, efficiency increase and lower emissions. This article presents the experimental and theoretical results of the evaporation of a mixture of ethanol and water into an air stream at elevated pressures and temperatures. A theoretical model has been established for the simultaneous heat and mass transfer occurring in the ethanol humidification tower. The theoretical model has been validated through experiments at several operating conditions. It has been shown that the air, water and ethanol can be calculated throughout the column in a satisfactory way. The height of the column can be estimated within an error of 15% compared with measurements. The results from the model are most sensitive to the properties of diffusion coefficient, viscosity, thermal conductivity and activity coefficient due to the complexity of the polar gas mixture of water and air

  4. Theoretical and experimental investigation of carnosine and its oxygenated adducts. The reaction with the nickel ion

    Science.gov (United States)

    Pavlos, Dimitrios; Petropouleas, Panayiotis; Hatzipanayioti, Despina

    2015-11-01

    DFT theoretical calculations at B3LYP/TZVP or LANL2DZ level of theory, for neutral, zwitterions, protonated and anionic carnosine, were performed. Energies, the structural and spectroscopic parameters were calculated in the gas phase and aqueous medium. Additional H-bonds stabilize the ionized forms of carnosine, creating "nests" into which metal ions or bio-molecules may be sheltered. Based on Fukui functions, the reactivity of the abovementioned forms of carnosine, with 1O2, may lead to oxygenated species. The theoretical spectroscopic parameters have been correlated to our experimental results. The effect of H2O2 and the electrochemistry of aqueous carnosine solutions were examined. Theoretical models containing Ni(II), carnosine and water were constructed. In the isolated mauve solid, formulated [Ni(carn)2(H2O)5], the COOsbnd , Nπ and/or NH2 were bonded. When H2O2 was added, the imidazole NMR signals disappeared. A redox couple clearly indicates one electron process, the electron coming from either the oxidation of imidazole ring or the nickel(II)/Ni(III) couple.

  5. Investigating the in vitro metabolism of fipexide: characterization of reactive metabolites using liquid chromatography/mass spectrometry.

    Science.gov (United States)

    Sleno, Lekha; Staack, Roland F; Varesio, Emmanuel; Hopfgartner, Gérard

    2007-01-01

    The in vitro metabolism of the nootropic drug fipexide was studied using different liquid chromatography/mass spectrometry (LC/MS) techniques. This drug has been withdrawn from the market due to toxic effects. No previous reports have investigated the possible involvement of reactive metabolites in the toxicity of fipexide. The hydrolysis of this drug leads to the formation of two potentially toxic species, 3,4-methylenedioxybenzylpiperazine (MDBP) and 4-chlorophenoxyacetic acid (4-CPA). Here, we investigate the in vitro metabolism of fipexide in human, rat, mouse and dog, as well as of MDBP and 4-CPA in human and rat, while focusing on the formation of reactive metabolites. A combination of LC/MS analyses on a hybrid quadrupole-linear ion trap instrument and accurate mass data from QqTOF measurements was employed for the characterization of these metabolites. Microsomal metabolites of fipexide were MDBP, 4-CPA, fipexide N-oxide or hydroxyl, demethylenated fipexide and other minor ones, all of which were investigated by tandem mass spectrometry. Reactive metabolites were detected using several trapping procedures with small molecules such as glutathione, its ethyl ester derivative and N-acetylcysteine. The demethylenated metabolite, a catechol, formed its corresponding ortho-quinone, which readily reacts with these nucleophiles. MDBP was studied in a similar manner, due to its ability to form an analogous catechol. Because of its acidic nature, 4-CPA was assessed for possible acylglucuronide and acyl-CoA thioester metabolites, which could also be involved in bioactivation pathways. Several important metabolites were identified as potential mediators of toxicity via protein binding. PMID:17577876

  6. Gas chromatography-mass spectrometry in the investigation of on-column dehydration of steroid hormones during gas-liquid chromatography.

    Science.gov (United States)

    Trafford, D J; Coldwell, R D; Makin, H L

    1991-01-01

    Some underivatized steroids when injected onto conventional packed columns for gas-liquid chromatography underwent varying degrees of dehydration. This problem was traced to the presence of small pieces of broken glass on the top of the column at the point of injection. This observation provoked an examination of the effect of pre-column dehydration on a number of different types of steroids. Powdered aluminium was placed in the injection liner of a Hewlett-Packard gas chromatograph fitted with an HP1 capillary column connected to a mass selective detector, and injections were made using a new high temperature septumless injection system at temperatures between 200 and 400 degrees C. 5 alpha-androstan-3 alpha-ol, a simple monofunctional C19 steroid chosen as a model to establish optimum conditions, underwent dehydration at injection temperatures greater than 250 degrees C and the product reached a maximum at 400 degrees C when no unchanged steroid was present. Monohydroxylated androgens and oestrogens underwent dehydration at 400 degrees C producing products whose mass spectra indicated they were monenes, although the position of the double bond could not be assigned. Polyfunctional androgens and oestrogens and corticosteroids underwent complex changes producing a number of products some of whose structures could not be determined. The dehydration products had the advantage that they had relatively intense high mass ions and for suitable steroids this might provide enhanced sensitivity of detection during mass fragmentography. In such cases dehydration was reproducible and straight line standard curves were obtained. C27 and C28 secosteroids (vitamins D2 and D3) and some of their metabolites (e.g. 25-hydroxyvitamin D) underwent efficient dehydration, again producing products with intense molecular ions. In the case of 24,25-dihydroxyvitamin D3 and 25,26-dihydroxyvitamin D3, dehydration produced different products which were easily resolved in the chromatographic

  7. Experimental and theoretical investigations of non-Newtonian electro-osmotic driven flow in rectangular microchannels.

    Science.gov (United States)

    Huang, Yi; Chen, Juzheng; Wong, TeckNeng; Liow, Jong-Leng

    2016-07-20

    With the development of microfluidics, electro-osmotic (EO) driven flow has gained intense research interest as a result of its unique flow profile and the corresponding benefits in its application in the transportation of sensitive samples. Sensitive samples, such as DNA, are incapable of enduring strong flow shear induced by conventional hydrodynamic driven methods. EO driven flow is thus a niche area. However, even though there are a few research studies focusing on bio-fluidic samples related to EO driven flow, the majority of them are merely theoretical modeling without solid evidence from experiments due to the inherent complex rheological behavior of the bio-fluids. Challenges occur when the EO driven mechanism meets with complex rheology; vital questions such as can the zeta potential still be assumed to be constant when dealing with fluids with complex rheology? and "Does the shear thinning effect enhance electro-osmotic driven flow?" need to be answered. We conducted experiments using current monitoring and microscopy fluorescence methods, and developed a theoretical model by coupling a generalized Smoluchowski approach with the power-law constitutive model. We calculated the zeta potential and compared the experimental results with modeling to answer the questions. The results show a reduction of zeta potential in the presence of PEO aqueous solutions. A constant zeta potential is also indicated by varying the PEO concentration and the electric field strength.The shear thinning effect is also addressed via experimental data and theoretical calculations. The results show a promising enhancement of the EO driven velocity due to the shear thinning effect. PMID:27381295

  8. Actinyl electronic structure investigation using a combined theoretical and experimental approach

    Energy Technology Data Exchange (ETDEWEB)

    Hilaire, S.; Guillaumont, D.; Gutierrez, F.; Wastin, F.; Colineau, E.; Gouder, T.; Berthet, JC.; Meyer, D.; Simoni, E

    2004-07-01

    Early actinides (U, Np, Pu, Am) show a particular linear bond actinyl type structure in higher oxidation state. The multiple bond nature of this chemical pattern contributes to a drastic diminution of the charge at the metallic core inducing a strong stabilisation of these high oxidation states. The potential participation of the early actinide 5f orbitals in the valence molecular shell is supposed to be one of the most important engines of this chemical specificity. In order to progress in the comprehension of this behaviour, a study of the electronic and the geometric structure of some actinyl complexes with different electronic configuration is undertaken using theoretical and experimental approaches. (authors)

  9. Actinyl electronic structure investigation using a combined theoretical and experimental approach

    International Nuclear Information System (INIS)

    Early actinides (U, Np, Pu, Am) show a particular linear bond actinyl type structure in higher oxidation state. The multiple bond nature of this chemical pattern contributes to a drastic diminution of the charge at the metallic core inducing a strong stabilisation of these high oxidation states. The potential participation of the early actinide 5f orbitals in the valence molecular shell is supposed to be one of the most important engines of this chemical specificity. In order to progress in the comprehension of this behaviour, a study of the electronic and the geometric structure of some actinyl complexes with different electronic configuration is undertaken using theoretical and experimental approaches. (authors)

  10. Inclusion process of tetracycline in β and γ-cyclodextrins: A theoretical investigation

    Science.gov (United States)

    Costa, Mércia A. S.; Anconi, Cleber P. A.; Dos Santos, Hélio F.; De Almeida, Wagner B.; Nascimento, Clebio S.

    2015-04-01

    The present Letter reports results from a comprehensive theoretical analysis of the inclusion process involving the tetracycline (TC) by β and γ-cyclodextrin (CD). Structure and stabilization energies were calculated, both in gas phase and aqueous solution, using a sequential methodology based on semiempirical and density functional theory (DFT) calculations. By the results, a qualitative structure-property relationship could be established with two main structural features being relevant for inclusion complex stabilization: (i) the depth of inclusion, which favors the hydrophobic contact inside the cavity of CDs and (ii) the hydrogen bonds established between guest and host molecules.

  11. Theoretical investigation of layered zeolites with MWW topology: MCM-22P vs. MCM-56

    Czech Academy of Sciences Publication Activity Database

    Položij, M.; Thang, H. V.; Rubeš, Miroslav; Eliášová, Pavla; Čejka, Jiří; Nachtigall, P.

    2014-01-01

    Roč. 43, č. 27 (2014), s. 10443-10450. ISSN 1477-9226 R&D Projects: GA ČR GBP106/12/G015; GA ČR(CZ) GP14-18521P EU Projects: European Commission(XE) 604307 - CASCATBEL Grant ostatní: GA MŠk(CZ) LM2010005; GA MŠk(CZ) ED3.2.00/08.0144 Institutional support: RVO:61388963 ; RVO:61388955 Keywords : initio molecular dynamics * total energy calculations * wave basis set Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.197, year: 2014

  12. Evolution of the electronic structures of NixSiy ordered systems: Experimental and theoretical investigations

    International Nuclear Information System (INIS)

    We study the change of the electronic structures of nickel silicides, Ni3Si and NiSi2, as well as nickel and silicon through the evolution of their valence band X-ray photoelectron spectra (v-XPS) both experimentally and theoretically. The experimental spectra are compared to the total and partial densities of states using the tight-binding linear muffin-tin orbital method (TB-LMTO) in the atomic sphere approximation (ASA). Good agreement is found between theory and experiment. (author)

  13. Ultrafast Gain Dynamics in Quantum Dot Amplifiers: Theoretical Analysis and Experimental Investigations

    DEFF Research Database (Denmark)

    Poel, Mike van der; Gehrig, Edeltraud; Hess, Ortwin;

    2005-01-01

    Ultrafast gain dynamics in an optical amplifier with an active layer of self-organized quantum dots (QDs) emitting near 1.3$muhbox m$is characterized experimentally in a pump-probe experiment and modeled theoretically on the basis of QD Maxwell–Bloch equations. Experiment and theory are in good...... agreement and show ultrafast subpicoseconds gain recovery followed by a slower 5 ps recovery. This behavior is found to be mainly caused by longitudinal optical phonon scattering and strongly dependents on electronic structure and confinement energy of the dots. A low amplitude-phase coupling ($alpha...

  14. Theoretical and Experimental Investigations of a Passively Mode-Locked Nd" Glass Laser

    OpenAIRE

    Kolmeder, Christian; Zinth, Wolfgang

    1981-01-01

    The presented theoretical model for a mode-locked Nd-glass laser simultaneously takes into account dynamics of the mode-locking dye, amplification saturation and radiation background. A systematic variation of laser parameters gives insight into the pulse formation process and allows to improve the laser design. The calculations show that it should be possible to decrease considerably the duration of light pulses of a mode-locked Nd-glass laser. Using a new mode-locking dye with a switching t...

  15. Experimental and theoretical investigation of an innovative evaporative condenser for residential refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Nasr, M.M.; Hassan, M. Salah [Department of Mechanical Power Engineering, Faculty of Engineering, Minia University (Egypt)

    2009-11-15

    In this study, an innovative, evaporative condenser for residential refrigerator was introduced. A vapor compression cycle incorporating the proposed evaporative condenser was tested to evaluate the cycle performance. To allow for evaporative cooling, sheets of cloth were wrapped around condenser to suck the water from a water basin by capillary effect. The thermal properties at the different points of the refrigeration cycle were measured for typical operating conditions. The experimental results showed that the condenser temperature increases 0.45 C for each degree increase in evaporator temperature when the air velocity is 2.5 m/s, and the ambient condition is 29 C and the relative humidity is 37.5%. Meanwhile, the condenser temperature increase is 0.88 C in the case of air velocity 1.1 m/s and ambient conditions of 31 C and relative humidity of 47.1%. A theoretical model for the evaporative condenser was developed, and validated by experimental results. The theoretical model showed that the evaporative condenser can operate at a condensing temperature of 20 C lower than that of the air-cooled condenser for heat flux of 150 W/m{sup 2}, and at air velocity 3 m/s. The effect of the different parameters on the condenser temperature was studied too. (author)

  16. Experimental and theoretical investigation of plasma oscillations of electrons in zinc and cadmium

    International Nuclear Information System (INIS)

    The spectra of the characteristic energy losses of fast (30 keV) electrons traversing thin metallic Zn and Cd films are measured. A narrow plasma loss peak at 9.07 eV is observed in Cd, which is characteristic of ordinary simple metals, in Zn the plasma resonance is first manifest as a singularity of the threshold type near 9.3 eV and this is followed by a bΩad peak at 14.3 eV. The dielectric functions of Zn and Cd are analyzed theoretically both within the framework of the pseudopotential theory as well as on the basis of the electron band structure of the metals calculated by taking into account the presence of narrow d-bands in the metals. It is shown that the pseudopotential approach describes correctly the width of the plasma resonance in Cd but cannot explain the plasmon energy shift. This approach is completely invalid for Zn. A calculation of the loss function by microscopic theory yields better agreement with the experimentat data for Cd and also describes correctly the threshold nature of the beginning of the plasma resonance in Zn. As a whole, the agreement between the calculated and experimental spectra for Zn is essentially qualitative. The causes of the insufficient accuracy of the theoretical calculations in the case of Zn are discussed briefly

  17. Theoretical Investigation of Dissolution Test Criteria for Waiver of Clinical Bioequivalence Study.

    Science.gov (United States)

    Sugano, Kiyohiko

    2016-06-01

    The purpose of the present study was to provide a theoretical basis for the dissolution test criteria of a biowaiver scheme. The critical dissolution number (Dncrit) was defined as a value to show bioequivalence of AUC and Cmax against infinitely rapid dissolution (Dn = ∞). The gastrointestinal tract was represented by the one-compartment model. The dissolution of a drug was expressed by the Noyes-Whitney equation. The permeation of a drug was expressed by the first-order equation. The approximate analytical solutions of Dncrit were derived from the analytical solution for the fraction of a dose absorbed [Fa = 1 - exp(-1/(1/Dn + Do/Pn)]; Do, the dose number; Pn, the permeation number). Numerical integration was also performed to calculate Dncrit more accurately. Dncrit was found to become smaller as Pn and Do became smaller. Dncrit for Cmax was found to be dependent on the elimination half-life of a drug as well as Pn and Do. The Fa equation can be an appropriate theoretical basis for a biowaiver scheme. PMID:27238491

  18. Theoretical investigation of new Heusler alloys Ru2VGa1−xAlx

    International Nuclear Information System (INIS)

    Highlights: • Electronic and thermodynamic properties of new Heusler alloys Ru2VGa1−xAlx (x = 0, 0.25, 0.50, 0.75, and 1.00) are studied. • Elastic parameters and stability of Ru2VGa1−xAlx alloys. • A linear behavior of the lattice parameter, bulk modulus, elastic constants and Debye temperature on x has been observed. - Abstract: Results of first-principles full-potential linearized augmented plane wave calculations of elastic and related electronic and thermodynamic properties of the quaternary Heusler alloys Ru2VAlxGa1−x (x = 0, 0.25, 0.5, 0.75, 1) are presented. These materials were found to have the L21 structure for all concentrations. The agreement between the theoretical and experimental lattice parameters for both Ru2VAl and Ru2VGa at various temperatures was found to be satisfactory. Our results provide predictions for the remaining mixed more» Heusler alloys Ru2VAlxGa1−x (0 < x < 1) for which no direct experimental or theoretical data are presently available. In their equilibrium L21 structure, all concentrations are non-magnetic metals. A linear variation of the lattice parameter, bulk modulus, elastic constants and Debye temperature has been observed with x

  19. Theoretical and experimental investigations on the dynamic and thermodynamic characteristics of the linear compressor for the pulse tube cryocooler

    Science.gov (United States)

    Zhang, L.; Dang, H. Z.; Tan, J.; Bao, D.; Zhao, Y. B.; Qian, G. Z.

    2015-12-01

    Theoretical and experimental investigations on the dynamic and thermodynamic characteristics of a linear compressor incorporating the thermodynamic characteristics of the inertance tube pulse tube cold finger have been made. Both the compressor and cold finger are assumed as a one-dimensional thermodynamic model. The governing equations of the thermodynamic characteristics of the working gas are summarized, and the effects of the cooling performance on the working gas in the compression space are discussed. Based on the analysis of the working gas, the governing equations of the dynamic and thermodynamic characteristics of the compressor are deduced, and then the principles of achieving the optimal performance of the compressor are discussed in detail. Systematic experimental investigations are conducted on a developed moving-coil linear compressor which drives a pulse tube cold finger, which indicate the general agreement with the simulated results, and thus verify the rationality of the theoretical model and analyses.

  20. Self-healing in segmented metallized film capacitors: Experimental and theoretical investigations for engineering design

    Science.gov (United States)

    Belko, V. O.; Emelyanov, O. A.

    2016-01-01

    A significant increase in the efficiency of modern metallized film capacitors has been achieved by the application of special segmented nanometer-thick electrodes. The proper design of the electrode segmentation guarantees the best efficiency of the capacitor's self-healing (SH) ability. Meanwhile, the reported theoretical and experimental results have not led to the commonly accepted model of the SH process, since the experimental SH dissipated energy value is several times higher than the calculated one. In this paper, we show that the difference is caused by the heat outflow into polymer film. Based on this, a mathematical model of the metallized electrode destruction is developed. These insights in turn are leading to a better understanding of the SH development. The adequacy of the model is confirmed by both the experiments and the numerical calculations. A procedure of optimal segmented electrode design is offered.

  1. An experimental and theoretical investigation into positron and electron scattering from formaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Zecca, A; Trainotti, E; Chiari, L [Department of Physics, University of Trento, Povo, I-38123 Trento (Italy); GarcIa, G [Instituto de Matematicas y Fisica Fundamental, CSIC, Serrano 121, 28006 Madrid (Spain); Blanco, F [Facultad de Ciencias Fisicas, Departamento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense, Avda. Complutense s/n, E-28040 Madrid (Spain); Bettega, M H F [Departamento de Fisica, Universidade Federal do Parana, Caixa Postal 19044, 81531-990 Curitiba, Parana (Brazil); Varella, M T do N [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970 Sao Paulo, SP (Brazil); Lima, M A P [Instituto de Fisica ' Gleb Wataghin' , Universidade Estadual de Campinas, Caixa Postal 6165, 13083-970 Campinas, Sao Paulo (Brazil); Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Caixa Postal 6170, 13083-970 Campinas, Sao Paulo (Brazil); Brunger, M J, E-mail: Michael.Brunger@flinders.edu.au [ARC Centre for Antimatter-Matter Studies, School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia)

    2011-10-14

    We report on measurements of total cross sections (TCSs) for positron scattering from the fundamental organic molecule formaldehyde (CH{sub 2}O). The energy range of these measurements was 0.26-50.3 eV, whereas the energy resolution was {approx}260 meV. To assist us in interpreting these data, Schwinger multichannel level calculations for positron elastic scattering from CH{sub 2}O were also undertaken (0.5-50 eV). These calculations, incorporating an accurate model for the target polarization, are found to be in good qualitative agreement with our measured data. In addition, in order to compare the behaviour of positron and electron scattering from this species, independent atom model-screened additivity rule theoretical electron TCSs, now for energies in the range 1-10 000 eV, are also reported.

  2. Experimental and theoretical investigation on the misalignment tolerance of a micron-sized solid immersion lens

    International Nuclear Information System (INIS)

    We report an experimental and theoretical study on the alignment error tolerance of a 2 μm-size solid immersion lens (SIL) illuminated by different types of focused spots. Tightly confined focal spots are of great interest for improving the performance of many optical systems, so that a study on the alignment tolerance is of interest. In particular, it was found that micro-SILs can be largely misaligned with respect to the optical axis of an objective lens focusing light onto it and yet allow for a reasonably good immersed spot. In fact, a displacement of approximately 400 nm, i.e. one fifth of the lens diameter, is tolerable. The measurements are compared with a rigorous finite element method model for a micro-SIL, showing an excellent agreement. (paper)

  3. Excited doublet and quartet states of SiP: a high level theoretical investigation

    International Nuclear Information System (INIS)

    Doublet and quartet states of the SiP molecule dissociating into the four lowest dissociation channels are characterized theoretically at a high-level of correlation treatment (multireference single and double excitation configuration interaction). Potential energy curves give a global view of the manifold of possible electronic states. For selected states, dipole and transition moment functions, and transition probabilities and radiative lifetimes are also reported as well as an extensive set of spectroscopic constants. A new 2Π state offers another likely route for exploring transitions to excited vibrational states of both X2Π and A2Σ+ states. A detailed set of data for the quartet states is expected to provide valuable information for the experimental identification of these states

  4. Role of magnesium in ZnS structure: Experimental and theoretical investigation

    Science.gov (United States)

    Shahid, M. Y.; Asghar, M.; Arbi, H. M.; Zafar, M.; Ilyas, S. Z.

    2016-02-01

    Wide band gap semiconductor materials are extending significant applications in electronics and optoelectronics industry. They are showing continued advancement in ultraviolet to infrared LEDs and laser diodes. Likewise the band gap tunability of ZnS with intentional impurities such as Mg and Mn are found useful for optoelectronic devices. Information from literature indicates slight blue shift in the band gap energy of ZnS by Mg doping but nevertheless, we report a reasonable red shift (3.48 eV/356 nm to 2.58 eV/480 nm) in ZnS band gap energy in Mg-ZnS structure. Theoretical model based on first principle theory using local density approximation revealed consistent results on Mg-ZnS structure. Similarly, structural, morphological, optical and electrical properties of the as grown Mg-ZnS were studied by XRD, SEM, FTIR, EDS, UV-Vis Spectrophotometer and Hall measurement techniques.

  5. Theoretical investigation on antioxidant activity of vitamins and phenolic acids for designing a novel antioxidant

    Science.gov (United States)

    Mohajeri, Afshan; Asemani, S. Somayeh

    2009-07-01

    Theoretical calculations have been performed to predict antioxidant property for two interesting classes of compounds including phenolic acids and vitamins. Important characteristics of antioxidants such as O-H bond dissociation enthalpy (BDE) and ionization potential (IP) were calculated in the gas-phase to analyze the effect of heterocyclic ring, intramolecular hydrogen bonding and presence of electron donating group near the O-H on the antioxidant activity. The results reveal that the presence of intramolecular hydrogen bonding through ortho-hydroxy group lowers BDE, IP and spin density. In general, phenolic acids were found to be more effective antioxidant than vitamins. The H-atom transfer (HAT) mechanism was selected to study the hydrogen abstraction from phenolic compounds by hydroperoxyl radical. It is found that the antioxidant with lower BDE undergoes hydrogen abstraction with low barrier and considerable exothermicity. On the basis of these results we were able to design a novel antioxidant with enhanced activity.

  6. Self-condensation of n-(N-propyl)butanimine: NMR and mass spectral analyses and investigation by theoretical calculation

    Energy Technology Data Exchange (ETDEWEB)

    Manfrini, Rozangela Magalhaes; Teixeira, Flavia Rodrigues; Pilo-Veloso, Dorila; Alcantara, Antonio Flavio de Carvalho, E-mail: aalcantara@zeus.qui.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Inst. de Ciencias Exatas. Dept. de Quimica; Nelson, David Lee [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Fac. de Farmacia. Dept. de Quimica; Siqueira, Ezequias Pessoa de [Centro de Pesquisas Rene Rachou (FIOCRUZ), Belo Horizonte, MG (Brazil)

    2012-07-01

    The stability of N-propylbutanimine (1) was investigated under different experimental conditions. The acid-catalyzed self-condensation that produced the E-enimine (4) and Z-inimine (5) was studied by experimental analyses and theoretical calculations. Since the calculations for the energy of 5 indicated that it had a lower energy than 4, yet 4 was the principal product, the self-condensation of 1 must be kinetically controlled. (author)

  7. A Theoretical investigation on HC Mixtures as Possible Alternatives to R134a in Vapor Compression Refrigeration

    OpenAIRE

    Feiza Memet

    2014-01-01

    This paper provides a theoretical comparison of the performance of refrigerants in use in a vapor comparison cycle. It is about the phase-out of R134a from actual refrigeration system, comparison being performed for this chemical and two more ecological mixtures: R290/R600a described as (30/70) and (40/60). Were investigated effects of condensation temperatures and evaporation temperatures on performance measures as COP (Coefficient of Performance) and VCC (volumetric coo...

  8. A Theoretical and Experimental Investigation on Free Vibration Vehavior of a Cantilever Beam with a Breathing Crack

    Directory of Open Access Journals (Sweden)

    M. Rezaee

    2012-01-01

    Full Text Available In this paper the free nonlinear vibration behavior of a cracked cantilever beam is investigated both theoretically and experimentally. For simplicity, the dynamic behavior of a cracked beam vibrating at its first mode is simulated using a simple single degree of freedom lumped parameter system. The time varying stiffness is modeled using a harmonic function. The governing equation of motion is solved by a perturbation method – the method of Multiple Scales.

  9. Theoretical and infrared investigation of 2-acetylpyridine isolated in solid nitrogen and in neat condensed phases

    Science.gov (United States)

    Kuş, Nihal

    2016-07-01

    The geometries of the two conformers of 2-acetylpyridine (2AP) were optimized at the DFT/B3LYP/6-311++G(d,p) level of approximation, and their relative energy and interconversion barrier evaluated. Both conformers were found to belong to the Cs symmetry point group, with conformer cis (with the methyl group and the ring nitrogen atom located in the same side of the molecule) being considerably stabilized over the trans form. The cis conformer exhibits stabilizing interactions between the ortho ring hydrogen atom and the carbonyl oxygen, as well as between the methyl out-of-the-plane hydrogen atoms and the ring nitrogen atom. In the less stable trans conformer (ΔE(trans-cis) = 26.3 kJ mol-1) these stabilizing interactions are replaced by repulsive interactions between the oxygen and nitrogen lone electron pairs and between the ring ortho and methyl out-of-the-plane hydrogen atoms. The energy barrier between the two conformers amounts to 30.7 kJ mol-1 in the cis → trans direction (4.4 kJ mol-1 in the reverse direction). In agreement with the theoretical data, in a cryogenic N2 matrix prepared from the room temperature 2AP gas phase, only the most stable cis conformer was observed. The IR spectra of 2AP isolated in solid N2, and those for the low temperature amorphous and crystalline neat solid states of the compound were recorded, and correlations between the spectroscopic data and the strength and nature of the dominant intermolecular interactions in 2AP neat condensed phases were evaluated. The analysis of the experimental vibrational data was supported by theoretical calculation of harmonic and anharmonic frequencies and IR intensities obtained at the DFT/B3LYP/6-311++G(d,p) level of theory.

  10. Density response to central electron heating: theoretical investigations and experimental observations in ASDEX Upgrade

    International Nuclear Information System (INIS)

    Theory of ion temperature gradient (ITG) and trapped electron modes (TEMs) is applied to the study of particle transport in experimental conditions with central electron heating. It is shown that in the unstable domain of TEMs, the electron thermo diffusive flux is directed outwards. By means of such a flux, a mechanism is identified likely to account for density flattening with central electron heating. Theoretical predictions are compared with experimental observations in ASDEX Upgrade. A parameter domain (including L- and H-mode plasmas) is identified, in which flattening with central electron heating is observed in the experiments. In general, this domain turns out to be the same domain in which the dominant plasma instability is a TEM. On the contrary, the dominant instability is an ITG in plasmas whose density profile is not affected significantly by central electron heating. The flattening predicted by quasi-linear theory for low density L-mode plasmas is too small compared to the experimental observations. At very high density, even when the dominant instability is an ITG, electron heating can provide density flattening, via the coupling with the ion heat channel. In these conditions the anomalous diffusivity increases in response to the increased ion heat flux, while the large collisionality makes the anomalous pinch small and the Ware pinch important. (author)

  11. Optical and theoretical investigations of V{sup 2+} ion in GaN

    Energy Technology Data Exchange (ETDEWEB)

    Souissi, Hajer; Dammak, Mohamed; Kammoun, Souha [Universite de Sfax, Laboratoire de Physique Appliquee, Groupe de Physique Theorique, Departement de Physique, Faculte des Sciences de Sfax, B. P. 802, 3018 Sfax (Tunisia); Souissi, Mnawer; Chine, Zied; El Jani, Belgacem [Unite de Recherche sur les Hetero-Epitaxies et Applications, Faculte des Sciences de Monastir, Mounastir 5000 (Tunisia)

    2011-05-15

    The infrared luminescence of vanadium-doped gallium nitride (GaN:V) grown by metalorganic vapour phase epitaxy technique (MOVPE) on SiN-treated sapphire substrate were examined. Two spin allowed transitions were observed at 6633 cm{sup -1} and 6959 cm{sup -1}, and are respectively assigned to the {sup 4}T{sub 1}({sup 4}P){yields}{sup 4}T{sub 1}({sup 4}F) and {sup 4}A{sub 2}({sup 4}F) {yields} {sup 4}T{sub 1}({sup 4}F) transition of V{sup 2+} (3d{sup 3}) in a tetrahedral symmetry with a {sup 4}T{sub 1} ground state. Crystal-field calculation of the detected transition energies based on the Tanabe-Sugano scheme is presented. Good agreements between theoretical and experimental energy levels are obtained. The presence of a series of vibronic state is also discussed in this work (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Theoretical and experimental investigation on magneto-hydrodynamics of plasma window

    Science.gov (United States)

    Wang, S. Z.; Zhu, K.; Huang, S.; Lu, Y. R.; Hershcovitch, A.; Yuan, Z. X.; Shi, B. L.; Gan, P. P.

    2016-01-01

    As a new device, plasma window has been designed to use plasma discharge to separate atmosphere from vacuum with high difference of pressure. It has many excellent properties, being able to be used as available passage for ion beam with negligible energy loss, also impervious to radiation damage and thermal damage. Normally beam focusing by accelerators is not that easy to achieve within channel of small cross section. 10 mm diameter plasma window's experimental realization could contribute to its further application in accelerator system. In this paper, 10 mm diameter 60 mm long plasma window has first been designed and managed to generate arc discharge with argon gas experimentally. The result proves that it has the ability to separate at least 28.8 kPa (not the upper limit) from 360 Pa with 50 A direct current and 2.5 kW power supplied. Current increase leads to linear inlet pressure increase obviously, while it has less impact on outlet pressure and voltage, coming to the conclusion that the higher current of plasma discharge, the larger pressure difference it creates. Theoretical analysis of 10 mm diameter plasma window in axis symmetrical configuration using argon also has been provided, in which a numerical 2D FLUENT-based magneto-hydrodynamic simulation model is settled. It has a good agreement with experimental result on voltage and mass flow rate when inlet pressure is increased.

  13. Theoretical and experimental investigation of crown/ammonium complexes in solution.

    Science.gov (United States)

    Achazi, Andreas J; von Krbek, Larissa K S; Schalley, Christoph A; Paulus, Beate

    2016-01-01

    The Gibbs energies of association ΔGsolT between primary alkyl ammonium ions and crown ethers in solution are measured and calculated. Measurements are performed by isothermal titration calorimetry and revealed a strong solvent-dependent ion pair effect. Calculations are performed with density functional theory including Grimme's dispersion correction D3(BJ). The translational, rotational, and vibrational contributions to the Gibbs energy of association ΔGsolT are taken into account by a rigid-rotor-harmonic-oscillator approximation with a free-rotor approximation for low lying vibrational modes. Solvation effects δGseT are taken into account by applying the continuum solvation model COSMO-RS. Our study aims at finding a suitable theoretical method for the evaluation of the host guest interaction in crown/ammonium complexes as well as the observed ion pair effects. A good agreement of theory and experiment is only achieved, when solvation and the effects of the counterions are explicitly taken into account. PMID:25868688

  14. Theoretical investigation of metastable Al2SiO5 polymorphs.

    Science.gov (United States)

    Oganov, A R; Price, G D; Brodholt, J P

    2001-09-01

    Using theoretical simulations based on density functional theory within the generalized gradient approximation, a series of metastable phase transitions occurring in low-pressure Al2SiO5 polymorphs (andalusite and sillimanite) are predicted; similar results were obtained using semiclassical interatomic potentials within the ionic shell model. Soft lattice modes as well as related structural changes are analysed. For sillimanite, an isosymmetric phase transition at ca 35 GPa is predicted; an incommensurately modulated form of sillimanite can also be obtained at low temperatures and high pressures. The high-pressure isosymmetric phase contains five-coordinate Si and Al atoms. The origin of the fivefold coordination is discussed in detail. Andalusite was found to transform directly into an amorphous phase at ca 50 GPa. This study provides an insight into the nature of metastable modifications of crystal structures and the ways in which they are formed. Present results indicate the existence of a critical bonding distance, above which interatomic interactions cannot be considered as bonding. The critical distance for the Si-O bond is 2.25 A. PMID:11526304

  15. Theoretical Investigation on the One- and Two-photon Absorption Properties of Porphyrin-thiophene Chromophores

    Institute of Scientific and Technical Information of China (English)

    LI, Wenchao; FENG, Jikang; REN, Aimin; ZHANG, Xiangbiao; SUN, Chiachung

    2009-01-01

    Two series of porphydn-thiophene chromophores were theoretically studied that exhibit large two-photon ab- sorption cross-section in the visible region. The density functional theory (DFT) associated with ZINDO/SDCI methods has been used to calculate the molecular geometries, electronic structures, one-photon and two-photon ab- sorption properties. The results show that the number of thiophene units affects the properties of one-photon ab- sorption (OPA) and two-photon absorption (TPA). Porphyrin-thiophene chromophores featuring two or three thio- phene units have wide TPA response ranges; they can be applied to many nonlinear optical areas, such as optical limiting. Intervening ethynyl unit is beneficial to extend the conjugated pathway, and increase the two-photon ab- sorption cross-section. At the same time, the OPA and TPA wavelengths are bathochromically shifted. From view- point of the high transparency and large nonlinear optical response, porphyrin-thiophene chromophores will be promising TPA materials.

  16. Theoretical models and simulation codes to investigate bystander effects and cellular communication at low doses

    Science.gov (United States)

    Ballarini, F.; Alloni, D.; Facoetti, A.; Mairani, A.; Nano, R.; Ottolenghi, A.

    Astronauts in space are continuously exposed to low doses of ionizing radiation from Galactic Cosmic Rays During the last ten years the effects of low radiation doses have been widely re-discussed following a large number of observations on the so-called non targeted effects in particular bystander effects The latter consist of induction of cytogenetic damage in cells not directly traversed by radiation most likely as a response to molecular messengers released by directly irradiated cells Bystander effects which are observed both for lethal endpoints e g clonogenic inactivation and apoptosis and for non-lethal ones e g mutations and neoplastic transformation tend to show non-linear dose responses This might have significant consequences in terms of low-dose risk which is generally calculated on the basis of the Linear No Threshold hypothesis Although the mechanisms underlying bystander effects are still largely unknown it is now clear that two types of cellular communication i e via gap junctions and or release of molecular messengers into the extracellular environment play a fundamental role Theoretical models and simulation codes can be of help in elucidating such mechanisms In the present paper we will review different available modelling approaches including one that is being developed at the University of Pavia The focus will be on the different assumptions adopted by the various authors and on the implications of such assumptions in terms of non-targeted radiobiological damage and more generally low-dose

  17. Correlative theoretical and experimental investigation of the formation of AlYB14 and competing phases

    Science.gov (United States)

    Hunold, Oliver; Chen, Yen-Ting; Music, Denis; Persson, Per O. Å.; Primetzhofer, Daniel; to Baben, Moritz; Achenbach, Jan-Ole; Keuter, Philipp; Schneider, Jochen M.

    2016-02-01

    The phase formation in the boron-rich section of the Al-Y-B system has been explored by a correlative theoretical and experimental research approach. The structure of coatings deposited via high power pulsed magnetron sputtering from a compound target was studied using elastic recoil detection analysis, electron energy loss spectroscopy spectrum imaging, as well as X-ray and electron diffraction data. The formation of AlYB14 together with the (Y,Al)B6 impurity phase, containing 1.8 at. % less B than AlYB14, was observed at a growth temperature of 800 °C and hence 600 °C below the bulk synthesis temperature. Based on quantum mechanical calculations, we infer that minute compositional variations within the film may be responsible for the formation of both icosahedrally bonded AlYB14 and cubic (Y,Al)B6 phases. These findings are relevant for synthesis attempts of all boron rich icosahedrally bonded compounds with the space group: Imma that form ternary phases at similar compositions.

  18. Theoretical investigation of alignment-dependent intense-field fragmentation of acetylene

    Science.gov (United States)

    Doblhoff-Dier, Katharina; Kitzler, Markus; Gräfe, Stefanie

    2016-07-01

    We analyze the alignment-dependent dissociative and nondissociative ionization of acetylene, C2H2 . Numerical models describing the yield of the singly and doubly charged ions (C2H2+,C2H22 +) and several fragmentation and isomerization channels (C2H++H+ ,CH++CH+ ,CH2++C+ ) as a function of the relative alignment angle between the laser polarization axis and the molecular axis are presented. We apply and compare two different approaches. The first is based on time-dependent density functional theory. The second is a quasi-single-particle approach using the Dyson orbitals. We find good agreement between the results of both methods. A comparison of our theoretical predictions with experimental data allows us to show that the alignment-dependent yield of most reaction channels is described to high accuracy assuming sequential ionization. However, for some of the fragmentation channels, namely, CH++CH+ and C2H++H+ , we find non-negligible influence of recollisional ionization.

  19. Experimental and theoretical investigation of the angular dependence of the Casimir force between sinusoidally corrugated surfaces

    Science.gov (United States)

    Banishev, A. A.; Wagner, J.; Emig, T.; Zandi, R.; Mohideen, U.

    2014-06-01

    In the current work we present the complete results for the measurement of normal Casimir force between a shallow and smooth sinusoidally corrugated gold coated sphere and a plate at various angles between the corrugations using an atomic force microscope. All measured data were compared with the theoretical approach using the proximity force approximation and theory based on derivative expansion. In both cases real material properties of the surfaces and nonzero temperature were taken into account. Special attention is paid to the description of electrostatic interactions between corrugated surfaces at different angles between corrugations and samples preparation and characterization. The measured forces are found to be in good agreement with the theory including correlation effects of geometry and material properties and deviate significantly from the predictions of the proximity force approximation approach. This provides the quantitative confirmation for the observation of diffraction-type effects that are disregarded within the PFA approach. The obtained results open new opportunities for control of the Casimir effect in micromechanical systems.

  20. Theoretical and experimental investigation on magneto-hydrodynamics of plasma window

    International Nuclear Information System (INIS)

    As a new device, plasma window has been designed to use plasma discharge to separate atmosphere from vacuum with high difference of pressure. It has many excellent properties, being able to be used as available passage for ion beam with negligible energy loss, also impervious to radiation damage and thermal damage. Normally beam focusing by accelerators is not that easy to achieve within channel of small cross section. 10 mm diameter plasma window's experimental realization could contribute to its further application in accelerator system. In this paper, 10 mm diameter 60 mm long plasma window has first been designed and managed to generate arc discharge with argon gas experimentally. The result proves that it has the ability to separate at least 28.8 kPa (not the upper limit) from 360 Pa with 50 A direct current and 2.5 kW power supplied. Current increase leads to linear inlet pressure increase obviously, while it has less impact on outlet pressure and voltage, coming to the conclusion that the higher current of plasma discharge, the larger pressure difference it creates. Theoretical analysis of 10 mm diameter plasma window in axis symmetrical configuration using argon also has been provided, in which a numerical 2D FLUENT-based magneto-hydrodynamic simulation model is settled. It has a good agreement with experimental result on voltage and mass flow rate when inlet pressure is increased

  1. Theoretical and experimental investigation on magneto-hydrodynamics of plasma window

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S. Z.; Zhu, K., E-mail: zhukun@pku.edu.cn; Huang, S.; Lu, Y. R.; Yuan, Z. X.; Shi, B. L.; Gan, P. P. [State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Hershcovitch, A. [Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)

    2016-01-15

    As a new device, plasma window has been designed to use plasma discharge to separate atmosphere from vacuum with high difference of pressure. It has many excellent properties, being able to be used as available passage for ion beam with negligible energy loss, also impervious to radiation damage and thermal damage. Normally beam focusing by accelerators is not that easy to achieve within channel of small cross section. 10 mm diameter plasma window's experimental realization could contribute to its further application in accelerator system. In this paper, 10 mm diameter 60 mm long plasma window has first been designed and managed to generate arc discharge with argon gas experimentally. The result proves that it has the ability to separate at least 28.8 kPa (not the upper limit) from 360 Pa with 50 A direct current and 2.5 kW power supplied. Current increase leads to linear inlet pressure increase obviously, while it has less impact on outlet pressure and voltage, coming to the conclusion that the higher current of plasma discharge, the larger pressure difference it creates. Theoretical analysis of 10 mm diameter plasma window in axis symmetrical configuration using argon also has been provided, in which a numerical 2D FLUENT-based magneto-hydrodynamic simulation model is settled. It has a good agreement with experimental result on voltage and mass flow rate when inlet pressure is increased.

  2. Theoretical Investigation of the Electronic Structure and Spectra of Mg(2+)He and Mg(+)He.

    Science.gov (United States)

    Bejaoui, M; Dhiflaoui, J; Mabrouk, N; El Ouelhazi, R; Berriche, H

    2016-02-11

    The ground and many excited states of the Mg(+)He van der Waals molecular system have been explored using a one-electron pseudopotential approach. In this approach, effective potentials are used to consider the Mg(2+) core and the electron-He effects. Furthermore, a core-core interaction is included. This has reduced the number of active electrons of the Mg(+)He, to be considered in the calculation, to a single valence electron. This has permitted to use extended Gaussian basis sets for Mg and He. Therefore, the potentianl energy and dipole moments calculations are carried out at the Hartree-Fock level of theory, and the spin-orbit effect is included using a semiclassical approach. The core-core interaction for the Mg(2+)He ground state is included using accurate CCSD(T) calculations. The spectroscopic constants of the Mg(+)He electronic states are extracted and compared with the existing theoretical works, where very good agreement is observed. Moreover, the transition dipole function has been determined for a large and dense grid of internuclear distances including the spin-orbit effect. PMID:26783874

  3. Theoretical and experimental investigation of evanescent-wave absorption sensors for extreme temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Buric, Michael P. [U.S. DOE; Ohodnicki, Paul R. [U.S. DOE; Chorpening, Benjamin T. [U.S. DOE

    2013-09-26

    Recently, significant developments in evanescent wave absorption sensors have been demonstrated for high temperature sensing applications based upon the optical responses of advanced thin film materials. We will demonstrate how such sensors can be utilized in a mode that allows for chemical or temperature sensing starting from basic theoretical considerations. We will also present experimental high temperature sensing results for fabricated sensors. Potential applications of the sensors to be discussed include a range of high temperature systems relevant for fossil energy and combustion monitoring such as industrial combustors or reaction vessels, solid oxide fuel cells, and gas turbines. In these applications, even a small increase in operating efficiency realized via careful observation of in-process parameters and implementation of real-time process controls can result in dramatic savings across the energy industry, illustrating the necessity of pursuing such techniques. It is hoped that sensors of the type described here will allow for unprecedented measurement-access to processes which present challenging high-temperature and chemically reactive environments.

  4. Theoretical and Experimental Investigations of the Potential of Osmotic Energy for Power Production

    Directory of Open Access Journals (Sweden)

    Adel O. Sharif

    2014-08-01

    Full Text Available This paper presents a study on the potential of osmotic energy for power production. The study includes both pilot plant testing and theoretical modelling as well as cost estimation. A projected cost of £30/MWh of clean electricity could be achieved by using a Hydro-Osmotic Power (HOP plant if a suitable membrane is used and the osmotic potential difference between the two solutions is greater than 25 bar; a condition that can be readily found in many sites around the world. Results have shown that the membrane system accounts for 50%–80% of the HOP plant cost depending on the salinity difference level. Thus, further development in membrane technology and identifying suitable membranes would have a significant impact on the feasibility of the process and the route to market. As the membrane permeability determines the HOP process feasibility, this paper also describes the effect of the interaction between the fluid and the membrane on the system permeability. It has been shown that both the fluid physical properties as well as the membrane micro-structural parameters need to be considered if further development of the HOP process is to be achieved.

  5. Experimental and theoretical investigations on spectroscopic properties of the imidazole-fused phenanthroline and its derivatives

    Science.gov (United States)

    Zhong, Rongfeng; Xu, Shengxian; Wang, Jinglan; Zhao, Feng; Xia, Hongying; Wang, Yibo

    2016-05-01

    Two phenanthroline derivatives, 1H-imidazo[4,5-f][1,10]phenanthroline (imPhen) and 2-(9H-fluoren-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (Flu-imPhen), have been synthesized and characterized and the corresponding absorption and emission spectroscopic properties have been studied in CH2Cl2 solution. The imPhen exhibits the main two absorption bands at 282 nm and 229 nm and these bands are assigned as the typical π → π*(Phen) state. In addition, the weak absorption bands at 313 nm associated with a shoulder near 302 nm were assigned to the π → π*(Phen) state with partial charge transfer (CT) character. A similar absorption spectra are observed in the case of the Flu-imPhen in the region of 200-300 nm, while the region of 300-400 nm of the spectra are dominated by the characteristic π → π* transition of the fluorene moiety. imPhen shows the typical ligand-centered 1π → π* emission, while Flu-imPhen emits from the mixed 1π → π*/CT states. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) were employed to rationalize the photophysical properties of these ligands studied. The theoretical data confirm the assignment of the experimental absorption spectra and the nature of the emitting states.

  6. Emotion felt by the listener and expressed by the music: a literature review and theoretical investigation

    Directory of Open Access Journals (Sweden)

    Emery eSchubert

    2013-12-01

    Full Text Available In his seminal paper, Gabrielsson (2002 distinguishes between emotion felt by the listener, here: ‘internal locus of emotion’ (IL, and the emotion the music is expressing, here: 'external locus emotion' (EL. This paper tabulates 16 such publications published in the decade 2003-2012 consisting of 19 studies/experiments and provides some theoretical perspectives. The key findings were that (1 IL ratings was frequently rated statistically the same or lower than the corresponding EL rating (e.g. lower felt happiness rating compared to the apparent happiness of the music, and that (2 self-select and preferred music had a smaller gap across the emotion loci than experimenter selected and disliked music. These key findings were explained by an ‘inhibited’ emotional contagion mechanism, where the otherwise matching felt emotion may have been attenuated by some other factor such as social context. Matching between EL and IL for loved and self-selected pieces was explained by the activation of ‘contagion’ circuits. Physiological arousal, personality and age, as well as musical features (tempo, mode, putative emotions were observed to influence perceived and felt emotion distinctions. A variety of data collection formats were identified, but mostly using continuous rating scales. In conclusion, a more systematic use of terminology appears desirable with respect to theory-building. Whether two broad categories, namely matched and unmatched, are sufficient to capture the relationships between EL and IL, instead of four categories as suggested by Gabrielsson, is subject to future research.

  7. An experimental and theoretical investigation of particle–wall impacts in a T-junction

    KAUST Repository

    Vigolo, D.

    2013-07-01

    Understanding the behaviour of particles entrained in a fluid flow upon changes in flow direction is crucial in problems where particle inertia is important, such as the erosion process in pipe bends. We present results on the impact of particles in a T-shaped channel in the laminar-turbulent transitional regime. The impacting event for a given system is described in terms of the Reynolds number and the particle Stokes number. Experimental results for the impact are compared with the trajectories predicted by theoretical particle-tracing models for a range of configurations to determine the role of the viscous boundary layer in retarding the particles and reducing the rate of collision with the substrate. In particular, a two-dimensional model based on a stagnation-point flow is used together with three-dimensional numerical simulations. We show how the simple two-dimensional model provides a tractable way of understanding the general collision behaviour, while more advanced three-dimensional simulations can be helpful in understanding the details of the flow. © 2013 Cambridge University Press.

  8. Theoretical investigations on structure, density, detonation properties, and sensitivity of the derivatives of PYX.

    Science.gov (United States)

    Liu, Hui; Wang, Fang; Wang, Gui-Xiang; Gong, Xue-Dong

    2012-08-15

    The -NH(2), -NO(2), -N(3), -NHNO(2), and -ONO(2) substitution derivatives of PYX (2,6-bis(picrylamino)-3,5-dinitropyridine) were studied at the B3LYP/6-31G** level of density functional theory. The sublimation enthalpies and heats of formation (HOFs) in gas phase and solid state of these compounds were calculated. The theoretical predicted density (ρ), detonation pressure (P), and detonation velocity (D) showed that these derivatives have better detonation performance than PYX. The effects of substituent groups on HOF, ρ, P, and D were discussed. The order of contribution of various groups to P and D was -ONO(2) > -NO(2) > -NHNO(2) > -N(3) > -NH(2). Sensitivity was evaluated using the frontier orbital energies, bond orders, bond dissociation enthalpies (BDEs), and characteristic heights (h(50)). The trigger bonds in the pyrolysis process for these PYX derivatives may be Ring-NO(2), NH-NO(2), or O-NO(2) varying with the substituents. The h(50) of most compounds are larger than that of CL-20, and those of -NH(2), -NO(2), and most -ONO(2) derivatives are larger than that of RDX. The BDEs of the trigger bonds of all but the -ONO(2) derivatives are sufficiently large. Taking both detonation performance and sensitivity into consideration, some derivatives of PYX may be good candidates of explosives. PMID:22618376

  9. Enhancement in dehydriding performance of magnesium hydride by iron incorporation: A combined experimental and theoretical investigation

    Science.gov (United States)

    Chen, Haipeng; Yu, Hao; Zhang, Qianqian; Liu, Bogu; Liu, Pei; Zhou, Xinpei; Han, Zongying; Zhou, Shixue

    2016-08-01

    Structural change and dehydriding mechanism of MgH2 with atomic Fe incorporation from reactive ball milling are characterized and simulated by first-principles calculation. Two kinds of hydrides β- and γ-MgH2 are formed from Mg powders under hydrogen atmosphere by 3.0 h of milling with pretreated anthracite as milling aid. Experimental studies suggest that the atomic Fe can be incorporated onto MgH2 surface by the shearing effect of Fe-based milling balls on Mg/MgH2 particles. The incorporated Fe has a high dispersity on MgH2 surface and can form atomic clusters FeH4/FeH2 by combining with H anions. The dehydriding reaction of the Fe-incorporated MgH2 begins at hydride surface and shows an enhanced performance with apparent activation energy of 110.3 kJ mol-1. Theoretical studies suggest that the incorporated Fe can act as a bridge that contributes to electron transfer from H anion to Mg cation before H2 molecule formation. The intrinsic reason of atomic Fe in catalyzing dehydriding reaction of MgH2 lies in its moderate strength of electron attraction.

  10. Theoretical and Experimental Investigations of the Potential of Osmotic Energy for Power Production †

    Science.gov (United States)

    Sharif, Adel O.; Merdaw, Ali A.; Aryafar, Maryam; Nicoll, Peter

    2014-01-01

    This paper presents a study on the potential of osmotic energy for power production. The study includes both pilot plant testing and theoretical modelling as well as cost estimation. A projected cost of £30/MWh of clean electricity could be achieved by using a Hydro-Osmotic Power (HOP) plant if a suitable membrane is used and the osmotic potential difference between the two solutions is greater than 25 bar; a condition that can be readily found in many sites around the world. Results have shown that the membrane system accounts for 50%–80% of the HOP plant cost depending on the salinity difference level. Thus, further development in membrane technology and identifying suitable membranes would have a significant impact on the feasibility of the process and the route to market. As the membrane permeability determines the HOP process feasibility, this paper also describes the effect of the interaction between the fluid and the membrane on the system permeability. It has been shown that both the fluid physical properties as well as the membrane micro-structural parameters need to be considered if further development of the HOP process is to be achieved. PMID:25110959

  11. Theoretical and experimental investigations of the potential of osmotic energy for power production.

    Science.gov (United States)

    Sharif, Adel O; Merdaw, Ali A; Aryafar, Maryam; Nicoll, Peter

    2014-01-01

    This paper presents a study on the potential of osmotic energy for power production. The study includes both pilot plant testing and theoretical modelling as well as cost estimation. A projected cost of £30/MWh of clean electricity could be achieved by using a Hydro-Osmotic Power (HOP) plant if a suitable membrane is used and the osmotic potential difference between the two solutions is greater than 25 bar; a condition that can be readily found in many sites around the world. Results have shown that the membrane system accounts for 50%-80% of the HOP plant cost depending on the salinity difference level. Thus, further development in membrane technology and identifying suitable membranes would have a significant impact on the feasibility of the process and the route to market. As the membrane permeability determines the HOP process feasibility, this paper also describes the effect of the interaction between the fluid and the membrane on the system permeability. It has been shown that both the fluid physical properties as well as the membrane micro-structural parameters need to be considered if further development of the HOP process is to be achieved. PMID:25110959

  12. Theoretical modelling and experimental investigations of the diode-pumped thin-disk Yb : YAG laser

    International Nuclear Information System (INIS)

    The fundamental principles of the operation of a solid-state laser are presented for the case when the active element is a thin disk. An analytical model of this laser is developed. The model is used to calculate the influence of the various parameters on the operational efficiency of the laser. A detailed model is also developed for calculations relating to a specific laser design and this model takes account of the geometry of the active medium, of the diode pump configuration, and of the operating conditions. Experiments yielded a cw output power up to 350 W and an optical pumping efficiency of ∼ 50% (the corresponding values obtained in this single-mode regime were approximately 100 W and 440%). These results were obtained below 0 0C for eight passes of the pump radiation through the active medium. At room temperature and for 16 passes the same parameters were several tens of watts and an efficiency up to 58%. These experimental results were in good agreement with the predictions of the theoretical model. (lasers)

  13. Theoretical Investigation Of Plate Fixation And Intramedullary Nailing Methods On Radius Fractures

    Directory of Open Access Journals (Sweden)

    Halim Kovacı

    2012-06-01

    Full Text Available While forearm fractures are often treated with plate-screw osteosynthesis, intramedullary nailing gained importance recently. For this aim, radius bone model was obtained using CT images, a fracture was introduced to the model and the callus, which is a structure forms during healing, was added to the model. Plate and intramedullary nail models were implemented to radius model. Structural behaviors of obtained models and callus on treatments with various implants were investigated under axial loading. In the light of these analyses, stresses on bone-implant structure and callus movement were investigated from the angle of application and treatment, depending on implant selection.

  14. Theoretical investigation of endohedral complexes of Si and Ge with C{sub 60} molecule

    Energy Technology Data Exchange (ETDEWEB)

    Umran, Nibras Mossa, E-mail: nibrasmossa@uokerbala.edu.iq [Department of Physics, Panjab University, Chandigarh 160014 (India); Department of Physics, Science College, Kerbala University, Kerbala (Iraq); Kumar, Ranjan [Department of Physics, Panjab University, Chandigarh 160014 (India)

    2014-03-15

    The electronic and magnetic properties of Si and Ge doped C{sub 60} fullerene are investigated with ab initio density functional theory calculations. In endohedral Si{sub n} (n=1–10) and Ge{sub n} (1–9) doped C{sub 60} complexes we have seen that Si and Ge doped complexes are stable up to 9 and 4 atoms, respectively. We have also investigated binding energy and ionization potential of the endohedral fullerene C{sub 60}. Endohedral fullerenes have been found to be more chemically reactive. Mullikan charge analysis shows the presence of the magnetic moment in these systems.

  15. Experimental, Theoretical and Numerical Investigation of the Flexural Behaviour of the Composite Sandwich Panels with PVC Foam Core

    Science.gov (United States)

    Mostafa, A.; Shankar, K.; Morozov, E. V.

    2014-08-01

    This study presents the main results of an experimental, theoretical and numerical investigation on the flexural behaviour and failure mode of composite sandwich panels primarily developed for marine applications. The face sheets of the sandwich panels are made up of glass fibre reinforced polymer (GFRP), while polyvinylchloride (PVC) foam was used as core material. Four-point bending test was carried out to investigate the flexural behaviour of the sandwich panel under quasi static load. The finite element (FE) analysis taking into account the cohesive nature of the skin-core interaction as well as the geometry and materials nonlinearity was performed, while a classical beam theory was used to estimate the flexural response. Although the FE results accurately represented the initial and post yield flexural response, the theoretical one restricted to the initial response of the sandwich panel due to the linearity assumptions. Core shear failure associate with skin-core debonding close to the loading points was the dominant failure mode observed experimentally and validated numerically and theoretically.

  16. The photophysics of pyranthione: a theoretical investigation focussing on spin-forbidden transitions

    Science.gov (United States)

    Tatchen, Jörg; Waletzke, Mirko; Marian, Christel M.; Grimme, Stefan

    2001-03-01

    In this paper we present the results of a theoretical study on the electronic structure and the photophysics of low-lying singlet and triplet states of 4H-pyran-4-thione. In a first step, Russel-Saunders coupled wavefunctions and spin-independent properties were determined by means of a recently proposed combination of density functional theory and multi-reference configuration interaction methods. Spin-orbit (SO) coupling was subsequently included at the level of quasi-degenerate perturbation theory. For the evaluation of spin-dependent properties a non-empirical effective one-electron SO mean-field Hamiltonian was employed. Calculated excitation energies, dipole moments, fine-structure splittings, and transition moments compare very well with experimental data. For the T 1 state we find that phosphorescence and non-radiative decay via intersystem crossing to the S 0 state are concurrent processes occurring at approximately equal rates of the order of 10 4 s-1. The T z→S 0 radiative transition gains its intensity from two sources: (1) Direct SO coupling of the S 0 and T 1 levels combined with the large dipole moment difference between these states and (2) the strong S 2→S 0 spin-allowed transition. The computed SO splitting in the T 1 state of D=-18 cm-1 is mainly due to interaction with the closeby T 2 state. A rapid depletion of the S 1 state via intersystem crossing to the T 1 state can be mediated by the T 2 state, if spin relaxation is fast within the triplet levels.

  17. Microwave ablation at 915 MHz vs 2.45 GHz: A theoretical and experimental investigation

    International Nuclear Information System (INIS)

    Purpose: The relationship between microwave ablation system operating frequency and ablation performance is not currently well understood. The objective of this study was to comparatively assess the differences in microwave ablation at 915 MHz and 2.45 GHz. Methods: Analytical expressions for electromagnetic radiation from point sources were used to compare power deposition at the two frequencies of interest. A 3D electromagnetic-thermal bioheat transfer solver was implemented with the finite element method to characterize power deposition and thermal ablation with asymmetrical insulated dipole antennas (single-antenna and dual-antenna synchronous arrays). Simulation results were validated against experiments in ex vivo tissue. Results: Theoretical, computational, and experimental results indicated greater power deposition and larger diameter ablation zones when using a single insulated microwave antenna at 2.45 GHz; experimentally, 32 ± 4.1 mm and 36.3 ± 1.0 mm for 5 and 10 min, respectively, at 2.45 GHz, compared to 24 ± 1.7 mm and 29.5 ± 0.6 mm at 915 MHz, with 30 W forward power at the antenna input port. In experiments, faster heating was observed at locations 5 mm (0.91 vs 0.49 °C/s) and 10 mm (0.28 vs 0.15 °C/s) from the antenna operating at 2.45 GHz. Larger ablation zones were observed with dual-antenna arrays at 2.45 GHz; however, the differences were less pronounced than for single antennas. Conclusions: Single- and dual-antenna arrays systems operating at 2.45 GHz yield larger ablation zone due to greater power deposition in proximity to the antenna, as well as greater role of thermal conduction

  18. Transient deformation of LMFBR cores due to local failure: experimental and theoretical investigation

    International Nuclear Information System (INIS)

    This paper describes an effort to predict the mechanical core deformation caused by local failure within an LMFBR core. These activities are intended to cover all the potential core damage possibilities currently under discussion and analysis. In particular it is shown that the reactor can be scrammed in time under pessimistic-realistic pressure transients and that the damage does not exceed tolerable limits. A special gas generator technique to simulate a fuel coolant explosion has been developed at AWRE Foulness. This has been used to perform the explosion tests needed to demonstrate the safety of the SNR 300 core. A molten fuel-coolant interaction (MFCI) experimental facility, and a drop tower to carry out sub-assembly crushing tests are described. Theoretical studies are presented which use mass-spring-dashpot, lumped parameter-hinge or micro-rigid-lumped-mass models. They simulate the crushing and bending of a single sub-assembly interacting with the coolant as well as the behaviour of a multirow 'spoke' model. For the core analysis only preliminary computational results are presently available which can be compared with the full scale tests in which the fluid pressure did not exceed a 'threshold' of about 100 bar. Parameter studies show the influence of pulse shape, material properties as well as the time integrator. Some of the unanswered questions concern the hydrodynamic feedback of the deformations on the pressure distribution in space and time. Also the behaviour of the highly irradiation-embrittled cores is poorly understood today. Finally, an enhanced energy release package to describe the MFCI must still be added to the reactivity calculation module of a future fast reactor dynamics code. (Auth.)

  19. Microwave ablation at 915 MHz vs 2.45 GHz: A theoretical and experimental investigation

    Energy Technology Data Exchange (ETDEWEB)

    Curto, Sergio; Taj-Eldin, Mohammed; Fairchild, Dillon; Prakash, Punit, E-mail: prakashp@ksu.edu [Department of Electrical and Computer Engineering, Kansas State University, Manhattan, Kansas 66506 (United States)

    2015-11-15

    Purpose: The relationship between microwave ablation system operating frequency and ablation performance is not currently well understood. The objective of this study was to comparatively assess the differences in microwave ablation at 915 MHz and 2.45 GHz. Methods: Analytical expressions for electromagnetic radiation from point sources were used to compare power deposition at the two frequencies of interest. A 3D electromagnetic-thermal bioheat transfer solver was implemented with the finite element method to characterize power deposition and thermal ablation with asymmetrical insulated dipole antennas (single-antenna and dual-antenna synchronous arrays). Simulation results were validated against experiments in ex vivo tissue. Results: Theoretical, computational, and experimental results indicated greater power deposition and larger diameter ablation zones when using a single insulated microwave antenna at 2.45 GHz; experimentally, 32 ± 4.1 mm and 36.3 ± 1.0 mm for 5 and 10 min, respectively, at 2.45 GHz, compared to 24 ± 1.7 mm and 29.5 ± 0.6 mm at 915 MHz, with 30 W forward power at the antenna input port. In experiments, faster heating was observed at locations 5 mm (0.91 vs 0.49 °C/s) and 10 mm (0.28 vs 0.15 °C/s) from the antenna operating at 2.45 GHz. Larger ablation zones were observed with dual-antenna arrays at 2.45 GHz; however, the differences were less pronounced than for single antennas. Conclusions: Single- and dual-antenna arrays systems operating at 2.45 GHz yield larger ablation zone due to greater power deposition in proximity to the antenna, as well as greater role of thermal conduction.

  20. Theoretical investigations of the transition from bubble boiling to film boiling at forced convection

    International Nuclear Information System (INIS)

    The model laws for the initial film boiling at forced convection are realized in vertical tubes. The local conditions in the investigated area were regarded to be most effective and sufficient for the description. The theory was confirmed by experimental data. (orig.)

  1. Theoretical investigation of the structure of κ-Al2O3

    DEFF Research Database (Denmark)

    Yourdshahyan, Y.; Engberg, U.; Bengtsson, L.; Lundqvist, B.I.; Hammer, Bjørk

    1997-01-01

    Using plane-wave pseudopotential calculations based on density-functional theory at the local-density-approximation level we investigate all the possible kappa-Al2O3 structures which are permitted by the known crystal symmetry. We find that structures with sixfold coordinated Al atoms are signifi...

  2. A theoretical and experimental investigation of an in-band pumped gain-switched thulium-doped fiber laser

    International Nuclear Information System (INIS)

    In this paper, the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber (TDF) laser is investigated. The analytical formulations of pump energy threshold, peak power extraction efficiency, and pulse extraction efficiency are derived through analyzing the interaction process between the pump pulse and the laser pulse. They are useful for understanding, designing, and optimizing the in-band pumped TDF lasers in a 1.9 μm–2.1 μm wavelength region. The experiment with an all-fiber gain-switched TDF laser pumped by a 1.558-μm pulse amplifier is conducted, and our experimental results show good agreement with theoretical analysis

  3. Theoretical and experimental investigation on the transient coupled heat and mass transfer in a radial flow desiccant packed bed

    International Nuclear Information System (INIS)

    Highlights: ► We present theoretical and experimental investigation of desiccant bed. ► Transient coupled heat and mass transfer in a radial flow desiccant packed bed has been reported. ► A real-time model is used. ► The prediction of air exit conditions from the bed is carried out. - Abstract: Theoretical and experimental investigation on the transient coupled heat and mass transfer in a radial flow desiccant packed bed has been reported in the present work. An experimental test rig has been designed and constructed to carry out the required experimental measurements. System parameters and flowing air conditions (bed weight, air velocity, air conditions – dry and wet bulb temperatures- at exit of test rig components) are measured and analyzed. A hollow cylindrical packed bed has been used as a desiccant dehumidifier. This configuration decreases the required power to blow air through the bed. In the theoretical study, prediction of air exit conditions from the bed is carried out based on the model of Barlow for the analysis of adsorption and regeneration processes in the desiccant bed. This model uses simple effectiveness equations for steady-state heat and mass exchangers within a finite difference procedure. Air at different conditions of temperature and humidity enters the regenerated bed and the exit temperature and humidity are plotted with time. Acceptable agreement is found between the theoretical and experimental results. The most effective parameters on the system performance are the initial water content of the bed and its initial temperature. Bed cooling during adsorption improves the system performance.

  4. Theoretical Investigation of Subwavelength Gratings and Vertical Cavity Lasers Employing Grating Structures

    DEFF Research Database (Denmark)

    Taghizadeh, Alireza

    . Though both sides of the grating layer are not surrounded by low refractive-index materials as in high-index-contrast gratings (HCGs), the HG can provide a near-unity reflectivity over a broader wavelength range than HCGs, or work as a resonator with a quality (Q) factor as high as 109. The physics......-factor is investigated, which shows that the uncertainty in the Q-factor can be several orders of magnitude larger than the uncertainty in the resonance frequency. Next, the HG is shown to possess a near-unity reflectivity in a broad wavelength range, which can be broader than the HCG, since the cap layer introduces...... more guided mode resonances (GMRs) in the reflectivity spectrum. The fabrication tolerance of the HG is investigated numerically, which shows that the broadband near-unity reflectivity characteristic is prone to common fabrication errors. An experimental demonstration of the HG reflector confirms its...

  5. Theoretical Investigation on Alcohol Sensing of Glycine-Coated Carbon Nanotubes

    Science.gov (United States)

    Jiang, Tao; Kussow, Gary; Kwon, Young-Kyun

    2007-03-01

    It has been observed that single walled carbon nanotube field effect transistors (SWNT-FET) coated with glycine can be used as alcohol sensors. The original semiconducting glycine-coated SWNT-FET have been changed to be metalic in the presence of alcohol. Using ab initio density functional theory, we compute the structural and electronic properties of carbon nanotubes coated with glycine in the absence or in the presence of alcohol (Isopropanol) to investigate alcohol sensing mechanism. To demonstrate specificity of such glycine-coated SWNT-FETs on alcohol, we also study those properties in the presence of other molecules, such as acetone and water. Furthermore, we investigate the effect of an external fields on glycine-coated SWNT with IPA, and indentify the gate-electric-field screening in SWNT-FET to be a major role for alcohol sensing.

  6. What are the characteristics of mathematical creativity? An empirical and theoretical investigation of mathematical creativity.

    OpenAIRE

    Haavold, Per Øystein

    2013-01-01

    The main research question in this research project was "what are the characteristics of mathematical creativity?" It was investigated both qualitatively and quantitatively and the findings are presented in four articles. In the first article, three high achieving students were given an unfamiliar trigonometric problem. The findings indicate strongly that the student’s way of thinking is strongly linked with imitative reasoning and only when received some form of guidance, were they able to d...

  7. Experimental and theoretical investigations of photocurrents in non-centrosymmetric semiconductor quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Duc, Huynh Thanh; Foerstner, Jens; Meier, Torsten [Department of Physics and CeOPP, University Paderborn (Germany); Priyadarshi, Shekar; Racu, Ana Maria; Pierz, Klaus; Siegner, Uwe; Bieler, Mark [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

    2010-07-01

    We compute photocurrents generated by femtosecond single-color laser pulses in non-centrosymmetric semiconductor quantum wells by combining a 14 x 14 k.p band structure theory with multi-band semiconductor Bloch equations. The transient photocurrents are investigated experimentally by measuring the associated Terahertz emission. The dependencies of the photocurrent and the Terahertz emission on the excitation conditions are discussed for (110)-oriented GaAs quantum wells. The comparison between theory and experiment shows a good agreement.

  8. Theoretical and experimental investigation of a Moving Bed Heat Exchanger for Solar Central Receiver Power Plants

    International Nuclear Information System (INIS)

    A Moving Bed Heat Exchanger for heat extraction from solar heated granular materials is investigated with respect to flow behaviour. To overcome limitations of existing empirical models, a numerical CFD model is established and parametrised with the help of experiments. Parametric studies are performed to quantify the effect of inlet velocities on the velocity field. A good agreement with an empirical model is found. Also, a comparison with PIV measurements confirms its validity, making it a solid basis for future design work.

  9. Investigating dynamical deformations of tumor cells in circulation: predictions from a theoretical model

    Directory of Open Access Journals (Sweden)

    KatarzynaAnnaRejniak

    2012-09-01

    The goal of this project is to use computational mechanical modeling to investigate fundamental biophysical parameters of tumor cells in circulation. As a first step to build a robust in silico model we consider a single cell exposed to the blood flow. We examine parameters related to structure of the actin network, cell nucleus and adhesion links between the tumor and endothelial cells that allow for successful transition between different transport modes of the adhesion cascade.

  10. The Electronic Structure of Organic Molecular Materials : Theoretical and Spectroscopic Investigations

    OpenAIRE

    Brumboiu, Iulia Emilia

    2014-01-01

    In the present thesis the electronic properties of two organic molecules were studied by means of density functional theory (DFT) in connection to their possible applications in organic photovoltaics and molecular spintronics respectively. The first analysed system is the C60 derivative PCBM extensively used in polymer solar cells for the charge separation process. Since fullerenes have been shown to undergo modifications as a result of light exposure, investigating their electronic structure...

  11. Theoretical and experimental investigations on fracture statistics carried out at the IDIEM (Chile

    Directory of Open Access Journals (Sweden)

    Kittl, P.

    1986-09-01

    Full Text Available The high exigencies required for some structures owing to their responsability or their high cost have originated a new discipline that can be called Reability Engineering, which main aim is to determine the probability afforded by a machine to comply a requirement. This work contains a not fully detailed description of the topics studied by IDEM during those last years, within this field. Within it there are Fracture Statistics, which studies the probability for some structure to undergo plastic deformations, and the probability of the causes to occur, taken into account materials fatigue. It also includes a theoretical development of the fracture statistics, describing the specific-risk-of-fracture functions by means of integral equations, and the determination of their parameters and their uncertainties, when the functions have a known analytical form. Experimental researches range from the most brittle bodies, such as glass, almost brittle ones such as cement paste and to others that can admit plastic deformation, such as certain weldings, enlarging the study to fibro-composites and natural materials such as granite.

    Las altas exigencias requeridas para algunas estructuras de especial responsabilidad o de muy alto coste han dado origen a una nueva disciplina que puede denominarse Ingeniería de la Fiabilidad, cuyo principal objetivo es determinar la probabilidad con que un ingenio puede verificar una exigencia. En este trabajo se presenta una descripción, no muy detallada, de los tópicos tratados por el IDIEM, en estos últimos años, dentro de esta disciplina. Dentro de ella está la Mecánica Estadística de Fractura, que estudia la probabilidad de que una estructura se deforme plásticamente, y la probabilidad de ocurrencia de las causas, teniendo en cuenta la fatiga de los materiales. Se incluye un desarrollo teórico de la mecánica estadística de fractura, describiendo las funciones de riesgo específico de

  12. THEORETICAL ASPECTS, EXPERIMENTAL INVESTIGATIONS AND EFFICIENCY IN USAGE OF HIGH-STRENGTH CONCRETE FOR BRIDGE STRUCTURES

    Directory of Open Access Journals (Sweden)

    G. D. Liakhevich

    2015-01-01

    Full Text Available In Belarus concrete with strength up to 60 MPA is used for construction. At the same time high strength concrete with compressive strength above 60 MPA is widely used in all industrially developed countries. High- strength concrete is included in regulatory documents of the European Union and that fact has laid a solid foundation for its application. High strength concrete is produced using highly dispersed silica additives, such as micro-silica and plasticizers (super-plasticizers with a water/cement (w/c ratio not greater than 0.4.Theoretical aspects of high-strength concrete for bridge structures have been studied in the paper. The paper shows a positive impact of highly dispersed additives on structure and physico-mechanical properties of cement compositions, namely: reduction of total porosity of a cement stone in concrete while increasing volumetric concentration and dispersion of a filler; binding of calcium hydroxide with the help of amorphised micro-silica; increased activity of mineral additives during their thin shredding; acceleration of the initial stage of chemical hardening of cement compositions with highly dispersed particle additives that serve as centers of crystallization; “binder-additive” cluster formation due to high surface energy of highly dispersed additive particles; hardening of surface area between a cement stone and aggregates in concrete; high-strength concretes are gaining strength much faster than conventional concretes.Technology of preparation and composition of high-strength concrete using highly dispersed mineral additives and super-plasticizer has been developed in the paper. This concrete will ensure a higher density, wa- ter-and gas tightness, increased resistance to aggressive environment, reduced consumption of concrete and reinforcement, reduced transport and installation weight, increased initial strength, early easing of shutters and preliminary compression, increased length of bridge spans

  13. Theoretical investigations of CO₂ and CH₄ sorption in an interpenetrated diamondoid metal-organic material.

    KAUST Repository

    Pham, Tony

    2014-05-29

    Grand canonical Monte Carlo (GCMC) simulations of CO2 and CH4 sorption and separation were performed in dia-7i-1-Co, a metal-organic material (MOM) consisting of a 7-fold interpenetrated net of Co(2+) ions coordinated to 4-(2-(4-pyridyl)ethenyl)benzoate linkers. This MOM shows high affinity toward CH4 at low loading due to the presence of narrow, close fitting, one-dimensional hydrophobic channels-this makes the MOM relevant for applications in low-pressure methane storage. The calculated CO2 and CH4 sorption isotherms and isosteric heat of adsorption, Qst, values in dia-7i-1-Co are in good agreement with the corresponding experimental results for all state points considered. The experimental initial Qst value for CH4 in dia-7i-1-Co is currently the highest of reported MOM materials, and this was further validated by the simulations performed herein. The simulations predict relatively constant Qst values for CO2 and CH4 sorption across all loadings in dia-7i-1-Co, consistent with the one type of binding site identified for the respective sorbate molecules in this MOM. Examination of the three-dimensional histogram showing the sites of CO2 and CH4 sorption in dia-7i-1-Co confirmed this finding. Inspection of the modeled structure revealed that the sorbate molecules form a strong interaction with the organic linkers within the constricted hydrophobic channels. Ideal adsorbed solution theory (IAST) calculations and GCMC binary mixture simulations predict that the selectivity of CO2 over CH4 in dia-7i-1-Co is quite low, which is a direct consequence of the MOM\\'s high affinity toward both CO2 and CH4 as well as the nonspecific mechanism shown here. This study provides theoretical insights into the effects of pore size on CO2 and CH4 sorption in porous MOMs and its effect upon selectivity, including postulating design strategies to distinguish between sorbates of similar size and hydrophobicity.

  14. Theoretical investigation of the mechanical and thermodynamics properties of Nb3Ga superconductor under pressure

    International Nuclear Information System (INIS)

    The mechanical and thermodynamics properties of Nb3Ga under pressure have been studied and analyzed using first-principles combined with quasi-harmonic Debye model. The calculated lattice parameter of the ground state is in well agreement with the experimental data. The pressure dependence of a/a0 and V/V0 are investigated, the bulk modulus B0 and its pressure derivative B′ are found to be 164.5 GPa and 3.936, respectively. The elastic constants under pressure are obtained and the polycrystalline elastic moduli of Nb3Ga are calculated derived from the single-crystal elastic constants. The results show that Nb3Ga is stable and behaves in a ductile manner up to 40 GPa. In addition, the elastic anisotropy, Vickers hardness as well as the melting temperature of Nb3Ga are investigated. Finally, the pressure and temperature dependence of the thermodynamic properties are also been obtained in the ranges of 0–40 GPa and 0–1000 K through the quasi-harmonic Debye model. - Highlights: • The physical properties of Nb3Ga were investigated. • The bulk modulus B0 and its pressure derivative B′ are found to be 164.5 GPa and 3.936. • The Nb3Ga is stable and behaves in a ductile manner up to 40 GPa. • The temperature dependence of the thermodynamic properties is obtained. • The 3D figures of the Young's modulus for Nb3Ga are obtained under pressure

  15. Combined experimental and theoretical mechanistic investigation of the Barbier allylation in aqueous media

    DEFF Research Database (Denmark)

    Dam, Johan Hygum; Fristrup, Peter; Madsen, Robert

    2008-01-01

    The Barbier allylation of a series of para-substituted benzaldehydes with allylbromide in the presence of Zn, In, Sn, Sb, Bi, and Mg was investigated using competition experiments. In all cases, the slope of the Hammett plots indicated a build-up of negative charge in the selectivity-determining ...... effect of solvent described by a polarized continuum model. The calculated secondary deuterium isotope effects based on this mechanism were found to be in good agreement with experimental values, thus adding further support to this mechanistic scenario....

  16. Theoretical investigation of Sn-doped Ge2Sb2Te5 alloy in crystalline phase

    International Nuclear Information System (INIS)

    Ge2Sb2Te5 (GST) is technologically important for phase-change random access memory applications. It has been shown that the 2.2 atomic % doping of Sn weakens the Ge–Te bond strength while maintaining the symmetry of stable phase of GST. The influence of Sn doping upon the phase change characteristics of the crystalline GST alloy has been investigated by ab initio calculations. The lattice parameter, average interface distances between two adjacent (111) layers, equilibrium volume, metallic character and electrical resistance has been calculated for the stable phase of GST and Sn-doped GST

  17. Theoretical investigation of anomalously high efficiency in a three cavity gyroklystron amplifier

    International Nuclear Information System (INIS)

    The University of Maryland's three cavity gyroklystron amplifier operating at a frequency of 10 GHz, voltage of 425 kV, current of 160 A, and pitch angle (v perpendicular/vz) near .82, has demonstrated an efficiency of 35%. The author's simulations using fixed field profiles predict a significantly lower efficiency, primarily because of the small pitch angle in the experiment. They will be investigating two methods of improving the efficiency in their simulations: Beam-wave interaction after the output cavity, and modification of the first two cavity Qs due to beam loading. Results of their nonlinear code will be given for both cases

  18. Theoretical and Numerical Investigation of a Four-cavity TE021-Mode Gyroklystron

    Science.gov (United States)

    Wang, Jianxun; Luo, Yong; Xu, Yong; Li, Hongfu

    2008-12-01

    Using self-consistent field theory and PIC simulation, the interaction of electron flow with HF fields in a four-cavity Gyroklystron with TE021-mode has been analyzed. Self-consistent field theory includes both linear theory and nonlinear theory. Optimized parameters and their corresponding efficiency, gain and bandwidth of the optimized Gyroklystron have been found. Numerical investigation using PIC simulation is also given. Parameters of the cavities which are operating in TE021 mode are optimized to minimize TE011 mode and to suppress parasitic self-oscillations. The results of theory are in good qualitative agreement with PIC simulation.

  19. Field emission properties of capped carbon nanotubes doped by alkali metals:a theoretical investigation

    Institute of Scientific and Technical Information of China (English)

    Jin Lei; Fu Hong-Gang; Xie Ying; Yu Hai-Tao

    2012-01-01

    The electronic structures and field emission properties of capped CNT55 systems with or without alkali metal atom adsorption were systematically investigated by density functional theory calculation.The results indicate that the adsorption of alkali metal on the center site of a CNT tip is energetically favorable.In addition,the adsorption energies increase with the introduction of the electric field.The excessive negative charges on CNT tips make electron emittance much easier and result in a decrease in work function.Furthermore,the inducing effect by positively charged alkali metal atoms can be reasonably considered as the dominant reason for the improvement in field emission properties.

  20. a Theoretical Investigation on 10-12 Potential of Hydrogen-Hydrogen Covalent Bond

    Science.gov (United States)

    Taneri, Sencer

    2013-05-01

    This is an analytical investigation of well-known 10-12 potential of hydrogen-hydrogen covalent bond. In this research, we will make an elaboration of the well-known 6-12 Lennard-Jones potential in case of this type of bond. Though the results are illustrated in many text books and literature, an analytical analysis for these potentials is missing almost everywhere. The power laws are valid for small radial distances, which are calculated to some extent. The internuclear separation as well as the binding energy of the hydrogen molecule are evaluated with success.

  1. Theoretical investigation of Sn-doped Ge2Sb2Te5 alloy in crystalline phase

    Science.gov (United States)

    Singh, Janpreet; Singh, Gurinder; Kaura, Aman; Tripathi, S. K.

    2015-06-01

    Ge2Sb2Te5 (GST) is technologically important for phase-change random access memory applications. It has been shown that the 2.2 atomic % doping of Sn weakens the Ge-Te bond strength while maintaining the symmetry of stable phase of GST. The influence of Sn doping upon the phase change characteristics of the crystalline GST alloy has been investigated by ab initio calculations. The lattice parameter, average interface distances between two adjacent (111) layers, equilibrium volume, metallic character and electrical resistance has been calculated for the stable phase of GST and Sn-doped GST.

  2. Theoretical investigations on the elastic and thermodynamic properties of rhenium phosphide

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Qun; Zhu, Xuanmin; Lin, Zhengzhe; Yao, Ronghui [Xidian Univ., Xi' an (China). School of Physics and Optoelectronic Engineering; Yan, Haiyan [Baoji Univ. of Arts and Sciences (China). Dept. of Chemistry and Chemical Engineering

    2016-04-01

    Structural, mechanical, and electronic properties of orthorhombic rhenium phosphide (Re{sub 2}P) are systematically investigated by using first principles calculations. The elastic constants and anisotropy of elastic properties are obtained. The metallic character of Re{sub 2}P is demonstrated by density of state calculations. The quasi-harmonic Debye model is applied to the study of the thermodynamic properties. The thermal expansion, heat capacities, and Grueneisen parameter on the temperature and pressure have been determined as a function of temperature and pressure in the pressure range from 0 to 100 GPa and the temperature range from 0 to 1600 K.

  3. Theoretical and experimental investigation into anti-idling A/C system for trucks

    International Nuclear Information System (INIS)

    Highlights: • A mathematical model is developed and verified using a built test-bed. • Thermal and performance characteristics of an anti-idling truck A/C system are investigated. • It is shown that variable speed fans have significant effects on the COP in different conditions. • A point of optimum COP can be found by changing the fans speed for any operating condition. • Anti-idling A/C systems equipped to variable speed control can significantly save environment. - Abstract: In this study, a recently developed truck anti-idling air conditioning (A/C) system is investigated. A mathematical model is developed to simulate the thermodynamic and heat transfer characteristics of the A/C system and calculate the coefficient of performance (COP). Utilizing environmental chambers and a number of measuring equipment, an experimental setup is built to verify the accuracy of the mathematical model and to perform a comprehensive study on the performance of the system for a wide range of operating conditions. A good agreement between the simulation and the experimental data, with a maximum discrepancy of 10.6%, is achieved. The results show a range of 0.5–1.7 for the system COP under a variety of operating condition. The parametric study shows that for any cooling demand, ambient and indoor air temperatures, there is a point of optimum COP that can be achieved by adjusting the condenser and evaporator fans speed

  4. Theoretical investigation of electronic and magnetic properties of HoRh layers

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, Sidi Bouzid, Safi (Morocco); LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France); Hamedoun, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Mounkachi, O. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Bahmad, L. [LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); El Moussaoui, H. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco)

    2013-10-15

    Self-consistent ab initio calculations, based on Density Functional Theory (DFT) approach and using Full potential Linear Augmented Plane Wave (FLAPW) method, are performed to investigate both electronic and magnetic properties of the HoRh layers. Polarized spin and spin–orbit coupling are included in calculations within the framework of the antiferromagnetic state between two sites of Ho. Magnetic moment considered to lie along (001) axes are computed. The data obtained from the ab initio calculations are then used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The exchange integrals between the magnetic atoms in the same sites are given by using mean field theory. The HTSEs of the magnetic susceptibility of HoRh layers spin-S through the Ising model for HoRh layers, are studied to tenth order series in β=1/k{sub B}T. The critical exponent γ associated with the magnetic susceptibility is deduced for two models. - Highlights: • Ab initio calculations is using to investigate both electronic and magnetic properties of the HoRh layers. • Obtained data from ab initio calculations are used as input for the HTSEs. • The Néel temperature is obtained for HoRh layers.

  5. Nonlinear optical switching behavior in the solid state: A theoretical investigation on anils

    KAUST Repository

    Ségerie, Audrey

    2011-09-13

    The linear (π(1)) and second-order nonlinear (π(2)) optical properties of two anil crystals, [N-(4-hydroxy)-salicylidene-amino-4-(methylbenzoate) and N-(3,5-di-tert- butylsalicylidene)-4-aminopyridine, denoted 4A and 4P, respectively], as well as the optical contrasts upon switching between their enol (E) and keto (K) forms, have been investigated by combining the molecular responses calculated using quantum chemistry methods and an electrostatic interaction scheme to account for the local field effects. It is found that intermolecular interactions impact differently the K/E optical contrasts in the two systems, which illustrates the importance of the supramolecular organization on the macroscopic responses. In 4A, the surrounding effects on the (hyper)polarizabilities are similar in the enol and keto forms, leading to optical contrasts very close to those of the isolated molecule. In contrast, an enhancement of the second-order susceptibility is observed in the keto form of 4P, leading to a large π(2)(K)/π(2)(E) contrast. Moreover, the π(2)(4A)/π(2)(4P) ratio for the most stable enol forms is obtained to be in good agreement with previous experimental investigations, which supports the reliability of the computational procedure. © 2011 American Chemical Society.

  6. Theoretical investigation of ionic effects in actuation and sensing of IPMCs of various geometries

    Science.gov (United States)

    Stalbaum, Tyler; Nelson, Shelby E.; Palmre, Viljar; Kim, Kwang J.

    2015-04-01

    Ionic polymer-metal composite (IPMC) electromechanical and mechanoelectrical phenomena for rectangular and tube-shaped IPMC devices have been examined through simulation and experimental investigation. There is a specific focus on investigating the anion and cation effects in actuation versus sensing. Simulations were performed using COMSOL Multiphysics 4.3b. Sample IPMCs were fabricated in lab in the desired geometries by techniques described herein. The sample sizes were roughly 1 mm thick and 20-25 mm in length. Actuation and sensor experiments were performed with the samples and compared to simulation results, which exhibit good agreement for voltage and tip displacement measurements. Fundamental differences in the electromechanical and mechanoelectrical transductions of IPMCs are highlighted in the simulation results. These results display the negligible effect of anion motion in actuation as compared to during sensing. In actuation, the cation motion is dominated by an electric potential flux, and the anions move only slightly in accordance with the deformed polymer membrane. In sensing, the electric potential is induced by the ionic migration in the polymer, and both cation and anion concentration variations are of similar magnitudes.

  7. Structural and Theoretical Investigation of Anhydrous 3,4,5-Triacetoxybenzoic Acid.

    Directory of Open Access Journals (Sweden)

    Paulo S Carvalho

    Full Text Available A comprehensive investigation of anhydrous form of 3,4,5-Triacetoxybenzoic acid (TABA is reported. Single crystal X-ray diffraction, Thermal analysis, Fourier Transform Infrared spectroscopy (FTIR and DFT calculations were applied for TABA characterization. This anhydrous phase crystallizes in the triclinic [Formula: see text] space group (Z' = 1 and its packing shows a supramolecular motif in a classical [Formula: see text] ring formed by acid-acid groups association. The phase stability is accounted in terms of supramolecular architecture and its thermal behaviour. Conformation search at B3LYP/6-311++G(2d,p level of theory shows the existence of three stable conformers and the most stable conformation was found experimentally. The reactivity of TABA was investigated using the molecular orbital theory and molecular electrostatic potential. The calculation results were used to simulate the infrared spectrum. There is a good agreement between calculated and experimental IR spectrum, which allowed the assignment of the normal vibrational modes.

  8. Conflicts of interest during contact investigations: a game-theoretic analysis.

    Science.gov (United States)

    Sippl-Swezey, Nicolas; Enanoria, Wayne T; Porco, Travis C

    2014-01-01

    The goal of contact tracing is to reduce the likelihood of transmission, particularly to individuals who are at greatest risk for developing complications of infection, as well as identifying individuals who are in need of medical treatment of other interventions. In this paper, we develop a simple mathematical model of contact investigations among a small group of individuals and apply game theory to explore conflicts of interest that may arise in the context of perceived costs of disclosure. Using analytic Kolmogorov equations, we determine whether or not it is possible for individual incentives to drive noncooperation, even though cooperation would yield a better group outcome. We found that if all individuals have a cost of disclosure, then the optimal individual decision is to simply not disclose each other. With further analysis of (1) completely offsetting the costs of disclosure and (2) partially offsetting the costs of disclosure, we found that all individuals disclose all contacts, resulting in a smaller basic reproductive number and an alignment of individual and group optimality. More data are needed to understand decision making during outbreak investigations and what the real and perceived costs are. PMID:24982688

  9. Structure and spectromagnetic properties of the superoxide radical adduct of DMPO in water: elucidation by theoretical investigations.

    Science.gov (United States)

    Houriez, Céline; Ferré, Nicolas; Siri, Didier; Tordo, Paul; Masella, Michel

    2010-09-16

    In the field of spin trapping chemistry, the design of more efficient radical traps can be assisted by the development of theoretical methods able to give a quantitative evaluation of the electron paramagnetic resonance (EPR) spectrum features of the spin-adduct radical, even before initiating the experimental work. The superoxide radical adduct of the 5,5-dimethyl-1-pyrroline-N-oxide nitrone (DMPO-OOH) has been reported in a huge number of papers devoted to the study of the oxidative stress. Here, we present for the first time the theoretical study of DMPO-OOH in an explicit water solution, based on the combined QM/MM//MD protocol we recently proposed, featuring a full coupling between the solute and all the explicit water molecules. Our results show that the DMPO-OOH EPR spectrum, whose interpretation is still debated, can be explained in the light of two sites in chemical exchange, in agreement with the most recent experimental data. Moreover, we demonstrate that each site consists of an equilibrium between the two main 5-membered ring conformations of DMPO-OOH. We provide also an analysis of the solvent contribution to the hyperfine coupling constants (hcc's) as well as an exhaustive study of the possible relationship between the hcc's and the main structural characteristics of DMPO-OOH. Our QM/MM//MD protocol appears thus to be an accurate theoretical tool allowing the investigation of the magnetic properties of large nitroxide spin adducts in complex environments. PMID:20722404

  10. Theoretical and Experimental Investigation of the Nonlinear Behavior of an Electrostatically Actuated In-Plane MEMS Arch

    KAUST Repository

    Ramini, Abdallah H.

    2016-05-02

    We present theoretical and experimental investigation of the nonlinear behavior of a clamped-clamped in-plane MEMS arch when excited by a DC electrostatic load superimposed to an AC harmonic load. Experimentally, a case study of in-plane silicon micromachined arch is examined and its mechanical behavior is measured using optical techniques. An algorithm is developed to extract the various parameters, such as the induced axial force and the initial rise, needed to model the behavior of the arch. A softening spring behavior is observed when the excitation is close to the first resonance frequency due to the quadratic nonlinearity coming from the arch geometry and the electrostatic force. Also, a hardening spring behavior is observed when the excitation is close to the third (second symmetric) resonance frequency due to the cubic nonlinearity coming from mid-plane stretching. Dynamic snap-through behavior is also reported for larger range of electric loads. Theoretically, a multi-mode Galerkin reduced order model is utilized to simulate the arch behavior. General agreement is reported among the theoretical and experimental data.

  11. Synthesis, single crystal structure, Hirshfeld surface and theoretical investigations on pyrimidine derivative

    Science.gov (United States)

    Dhandapani, A.; Manivarman, S.; Subashchandrabose, S.

    2016-07-01

    Nonlinear optical organic crystal of ethyl-6-(chloromethyl)-4-(4-hydroxy-3-methoxyphenyl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylatemonohydrate (CHMTM) were grown by the slow evaporation technique. Structural characterization was made by X-ray diffraction method, further characterized by FT-IR, FT-Raman, and NMR spectra. The equilibrium geometry and harmonic vibrational wavenumbers were computed using Density Functional Theory (DFT) method. The vibrational assignments were carried out with the help of potential energy distribution (PED) analysis. The intermolecular interactions of the crystal structure were analyzed using Hirshfeld surface and fingerprint analysis. Charge transfer analyzed with the help of NBO analysis. The nonlinear optical properties (NLO) and energy gap (Eg) analysis were also investigated.

  12. Theoretical and experimental investigations on fluid-structure-interaction in cylindrical structures

    International Nuclear Information System (INIS)

    The presented FSE (fluid-structure-element) is based on approximate analytical solutions of the continuity equation and the Navier-Stokes equation considering the structural motion. Due to the linearization with respect to the structural DOFs (degrees of freedom) a mass and a damping matrix can be obtained from the instationary 2D-solution, and a stiffness matrix is derived from the stationary 3D-solution. Experimental investigations have proved the FSE to be applicable for narrow annular gaps in the laminar as well as in the turbulent flow range. The FSE can be used to integrate the fluid-structure-interaction (FSIA) into large finite element (FE) models. It has already been used within a FE based vibration model of the VVER-440 type pressurized water reactor. (orig./HP)

  13. Theoretical investigation of a semiconductor ring laser driven by Chua's oscillator

    Science.gov (United States)

    Takougang Kingni, Sifeu; Woafo, Paul

    2013-06-01

    The modeling and numerical investigation of the dynamical behavior of a semiconductor ring laser (SRL) driven by Chua's oscillator are reported. By increasing the coupling strength between the SRL and Chua's oscillator at a fixed bias current, the SRL exhibits an intermittency route to anti-phase chaos. However, for a fixed value of the coupling strength, we report a period-doubling route to out-of-phase and anti-phase chaos when varying one of the parameters of the Chua's oscillator are reported. We also demonstrate that a SRL driven by the chaotic output of Chua's oscillator generates a more complex chaos compared to the one found in a SRL subject to a sinusoidally modulated current. This new way of modulation of semiconductor lasers would not only bring a general benefit in the physical equipment and reduce their cost but could have an impact for some relevant engineering applications.

  14. Theoretical investigation of reactions between ammonia and precursors from the ozonolysis of ethene

    Science.gov (United States)

    Jørgensen, Solvejg; Gross, Allan

    2009-07-01

    The reaction mechanisms between ammonia and two secondary organic aerosol (SOA) precursors from ozonolysis of alkenes - namely the secondary ozonide (SOZ) and hydroxyl substituted ester (HSE) have been investigated using quantum mechanics calculations. For the reaction between ammonia and SOZ, three reaction channels were found (i) an aldehyde, a hydrogen peroxide and an imine, (ii) two aldehydes and a hydroxylamine, (iii) a hydroxyalkyl hydroperoxide and an imine. For the reaction involving the HSE the reaction products are an aldehyde, carboxylic acid and ammonia. The B3LYP method with 6-311++G(2d,2p) basis set was employed for the geometry optimisation of the stationary points. Gaussian 2 and Gaussian 3 levels of theory have been used to optimise and refine the energy. From an energetic point of view, it is concluded that the reaction between ammonia and HSE is in favour compared to the one with the SOZ.

  15. Theoretical investigation of reactions between ammonia and precursors from the ozonolysis of ethene

    International Nuclear Information System (INIS)

    The reaction mechanisms between ammonia and two secondary organic aerosol (SOA) precursors from ozonolysis of alkenes - namely the secondary ozonide (SOZ) and hydroxyl substituted ester (HSE) have been investigated using quantum mechanics calculations. For the reaction between ammonia and SOZ, three reaction channels were found (i) an aldehyde, a hydrogen peroxide and an imine, (ii) two aldehydes and a hydroxylamine, (iii) a hydroxyalkyl hydroperoxide and an imine. For the reaction involving the HSE the reaction products are an aldehyde, carboxylic acid and ammonia. The B3LYP method with 6-311++G(2d,2p) basis set was employed for the geometry optimisation of the stationary points. Gaussian 2 and Gaussian 3 levels of theory have been used to optimise and refine the energy. From an energetic point of view, it is concluded that the reaction between ammonia and HSE is in favour compared to the one with the SOZ.

  16. Theoretical investigation of reactions between ammonia and precursors from the ozonolysis of ethene

    Energy Technology Data Exchange (ETDEWEB)

    Jorgensen, Solvejg, E-mail: solvejg@kemi.ku.dk [Copenhagen Center of Atmospheric Research, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen O (Denmark); Gross, Allan, E-mail: agr@dmi.dk [Research Department, Danish Meteorological Institute, Lyngbyvej 100, DK-2100 Copenhagen O (Denmark)

    2009-07-30

    The reaction mechanisms between ammonia and two secondary organic aerosol (SOA) precursors from ozonolysis of alkenes - namely the secondary ozonide (SOZ) and hydroxyl substituted ester (HSE) have been investigated using quantum mechanics calculations. For the reaction between ammonia and SOZ, three reaction channels were found (i) an aldehyde, a hydrogen peroxide and an imine, (ii) two aldehydes and a hydroxylamine, (iii) a hydroxyalkyl hydroperoxide and an imine. For the reaction involving the HSE the reaction products are an aldehyde, carboxylic acid and ammonia. The B3LYP method with 6-311++G(2d,2p) basis set was employed for the geometry optimisation of the stationary points. Gaussian 2 and Gaussian 3 levels of theory have been used to optimise and refine the energy. From an energetic point of view, it is concluded that the reaction between ammonia and HSE is in favour compared to the one with the SOZ.

  17. Theoretical Investigation of Supported Utra-Thin Cobalt/Nickel/Iron/Manganese Oxides

    Science.gov (United States)

    Bajdich, Michal; García Melchor, Max; Vojvodic, Alexandra

    In the last decade, a number of experiments have shown that ultra-thin layers of transition metal oxides (TMOs) can be stabilized when interfaced with precious metal supports such as Au(111) and Pt(111) or Ir(100). Moreover, gold supported Co/Ni/Mn-based catalysts have been experimentally proven to exhibit higher oxygen evolution reaction (OER) activities than other metal supported oxide catalysts. However, the synergistic effect of contact with gold support is yet to be fully understood. In this talk, I will report on our recent investigation of thermodynamic stability and and high water reactivity of ultra-thin cobalt oxide nanoislands supported on Au(111). Furthermore, the stability trends, scaling of the metal-support interaction and charge transfer of several Mn/Fe/Co/Ni supported oxides on all FCC(111) metals will be analyzed. The type and role of different edge sites for the OER activity of these nanoislands will be discussed.

  18. Energy shift of collective electron excitations in highly corrugated graphitic nanostructures: Experimental and theoretical investigation

    Energy Technology Data Exchange (ETDEWEB)

    Sedelnikova, O. V., E-mail: o.sedelnikova@gmail.com; Bulusheva, L. G.; Okotrub, A. V. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Science, 3 Acad. Lavrentiev Ave., Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2 Pirogov Str., Novosibirsk 630090 (Russian Federation); Tomsk State University, 36 Lenina Ave., Tomsk 634050 (Russian Federation); Asanov, I. P. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Science, 3 Acad. Lavrentiev Ave., Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2 Pirogov Str., Novosibirsk 630090 (Russian Federation); Yushina, I. V. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Science, 3 Acad. Lavrentiev Ave., Novosibirsk 630090 (Russian Federation)

    2014-04-21

    Effect of corrugation of hexagonal carbon network on the collective electron excitations has been studied using optical absorption and X-ray photoelectron spectroscopy in conjunction with density functional theory calculations. Onion-like carbon (OLC) was taken as a material, where graphitic mantle enveloping agglomerates of multi-shell fullerenes is strongly curved. Experiments showed that positions of π and π + σ plasmon modes as well as π → π* absorption peak are substantially redshifted for OLC as compared with those of highly ordered pyrolytic graphite and thermally exfoliated graphite consisted of planar sheets. This effect was reproduced in behavior of dielectric functions of rippled graphite models calculated within the random phase approximation. We conclude that the energy of electron excitations in graphitic materials could be precisely tuned by a simple bending of hexagonal network without change of topology. Moreover, our investigation suggests that in such materials optical exciton can transfer energy to plasmon non-radiatively.

  19. A theoretical and experimental investigation on the adsorption of pentacene on the Cu(322) surface

    Science.gov (United States)

    Matos, Jeronimo; Sauvage-Simkin, Michele; Coati, Alessandro; Garreau, Yves; Vlad, Alina; Muller, Kathrin; Bendounan, Azzedine; Kara, Abdelkader

    In this study, complementary techniques including density functional theory (DFT), grazing incidence x-ray diffraction (GIXD), and scanning tunneling microscopy (STM) are used to study the surface distortions induced by the adsorption of pentacene on the stepped Cu(322) surface. GIXD measurements are performed for the clean Cu(322) surface and at various coverages of pentacene, up to one monolayer. For the one monolayer case, reciprocal space maps from GIXD measurement suggest the reconstruction of the steps to double the step width and height, with two pentacene molecules present at each terrace. Complementary DFT calculations are carried out, with and without the self-consistent inclusion of vdW interactions, using the optB88-vdW and PBE functionals. Our investigation illustrates a prototype method for conducting future benchmarking studies to assess the accuracy of the current self-consistent vdW functionals when applied to organic molecule adsorption.

  20. A theoretical investigation of valence and Rydberg electronic states of acrolein

    International Nuclear Information System (INIS)

    The main features of the ultraviolet spectrum of acrolein have been studied by a multireference perturbative treatment and by a time dependent density functional approach. The valence and Rydberg transition energies have been calculated and the assignment of the experimental bands has been clarified. The different relaxation trends of the three lowest singlet and triplet excited states have been analyzed by unconstrained geometry optimizations. This has allowed, in particular, the characterization of a twisted 3(ππ*) state, which is crucial for the interesting photophysics and photochemistry of the acrolein molecule and, more generally, of the α,β-enones. Solvatochromic shifts in aqueous solution have been investigated using a combined discrete/continuum approach based on the so called polarizable continuum model. The experimental trends are well reproduced by this approach and a closer degeneracy in the triplet manifold has been detected in solution with respect to gas phase

  1. THEORETICAL INVESTIGATION ON BY-ONLY-CURRENT ELECTROMAGNETIC SEPARATION OF INCLUSION FROM MOLTEN METALS

    Institute of Scientific and Technical Information of China (English)

    B.W. Zhang; Z.M. Ren; Y.B. Zhong; K. Deng; K.D. Xu

    2002-01-01

    The electromagnetic field under applied AC and DC current in round and rectangularpipe was systematically investigated, then a concept of "equivalent current density"was proposed for evaluating the inhomogeneous electromagnetic pinch force, and themono-component removal efficiency and the overall removal efficiency of inclusionwere formulated. It is founded that flat pipe is superior to round pipe for the electro-magnetic removal of inclusion, and DC current can get a higher removal efficiencythan AC current due to absence of skin phenomenon. Under usual condition, a re-moval efficiency of 52% for 10μm inclusion or more than 92% for 20μm inclusioncan be achieved by imposing a current density of 3× 106A/m2 in a fiat pipe.

  2. Theoretical Investigation on the Adsorption of Ag+ and Hydrated Ag+ Cations on Clean Si(111)Surface

    Institute of Scientific and Technical Information of China (English)

    SHENG Yong-Li; LI Meng-Hua; WANG Zhi-Guo; LIU Yong-Jun

    2008-01-01

    In this paper,the adsorption of Ag+ and hydrated Ag+ cations on clean Si(111)surface were investigated by using cluster(Gaussian 03)and periodic(DMol3)ab initio calculations.Si(111)surface was described with cluster models(Si14H17 and Si22H21)and a four-silicon layer slab with periodic boundary conditions.The effect of basis set superposition error(BSSE)was taken into account by applying the counterpoise correction.The calculated results indicated that the binding energies between hydrated Ag+ cations and clean Si(111)surface are large,suggesting a strong interaction between hydrated Ag+ cations and the semiconductor surface.With the increase of number,water molecules form hydrogen bond network with one another and only one water molecule binds directly to the Ag+ cation.The Ag+ cation in aqueous solution will safely attach to the clean Si(111)surface.

  3. Structures of Aln, its anions and cations up to n=34: A theoretical investigation

    International Nuclear Information System (INIS)

    A systematic density functional study has been performed for neutral and singly charged clusters of aluminum with up to 34 atoms. A thorough search for global minimum structures has been carried out for Aln employing genetic algorithm and basin-hopping procedures. For Aln this confirms results of previous investigations up to n=22; new global minima have been located for n=23-31, 33. Structures for singly charged cations and anions have been obtained by reoptimization of the pool of 40 low-energy structures of the neutral clusters. The global minima of charged and neutral clusters are always low-spin states with the possible exception of a triplet state of Al28, which is isoenergetic with a singlet. The cluster structures are mostly quite irregular and do not resemble fractions of the fcc bulk phase. High symmetries are found only for the global minimum of Al23 and the triplet state of Al28.

  4. Theoretical Investigation of Uniform and Non-uniform Penetrable Sphere Fluid

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shi-Qi

    2006-01-01

    A bridge function approximation is proposed for a single-component fluid consisting of penetrable sphere interacting via a potential that remains finite and constant for center-center distance smaller than the particle diameter and is zero otherwise. The radial distribution function from the Ornstein-Zernike integral equation combined with the present bridge function approximation is in satisfactory agreement with the corresponding simulation data for all of the investigated state points. The presently calculated excess Helmholtz free energy respectively based on virial route and compressibility route is highly self-consistent, and is in very good agreement with simulational results for the case of low temperatures. The present bridge function approximation, combined with the bridge density functional approximation,can reproduce very accurately density profiles of the penetrable sphere fluid confined in a hard spherical cavity for all the cases where simulational results are available.

  5. An experimental and theoretical investigation on torrefaction of a large wet wood particle.

    Science.gov (United States)

    Basu, Prabir; Sadhukhan, Anup Kumar; Gupta, Parthapratim; Rao, Shailendra; Dhungana, Alok; Acharya, Bishnu

    2014-05-01

    A competitive kinetic scheme representing primary and secondary reactions is proposed for torrefaction of large wet wood particles. Drying and diffusive, convective and radiative mode of heat transfer is considered including particle shrinking during torrefaction. The model prediction compares well with the experimental results of both mass fraction residue and temperature profiles for biomass particles. The effect of temperature, residence time and particle size on torrefaction of cylindrical wood particles is investigated through model simulations. For large biomass particles heat transfer is identified as one of the controlling factor for torrefaction. The optimum torrefaction temperature, residence time and particle size are identified. The model may thus be integrated with CFD analysis to estimate the performance of an existing torrefier for a given feedstock. The performance analysis may also provide useful insight for design and development of an efficient torrefier. PMID:24657751

  6. X-band Dielectric Loaded Rf Driven Accelerator Structures Theoretical And Experimental Investigations

    CERN Document Server

    Zou, P

    2001-01-01

    An important area of application of high-power radio frequency (RF) and microwave sources is particle acceleration. A major challenge for the current worldwide research and development effort in linear accelerator is the search for a compact and affordable very-high-energy accelerator technology for the next generation supercolliders. It has been recognized for sometime that dielectric loaded accelerator structures are attractive candidates for the next generation very-high-energy linear accelerators, because they possess several distinct advantages over conventional metallic iris- loaded accelerator structures. However, some fundamental issues, such as RF breakdown in the dielectric, Joule heating, and vacuum properties of dielectric materials, are still the subjects of intense investigation, requiring the validation by experiments conducted at high power levels. An X-band traveling-wave accelerator based on dielectric-lined waveguide has been designed and constructed. Numerical calculation, bench measuremen...

  7. Theoretical investigation on the alkali-metal doped BN fullerene as a material for hydrogen storage

    International Nuclear Information System (INIS)

    Graphical abstract: First-principles calculations have been used to investigate hydrogen adsorption on alkali atom doped B36N36 clusters. Adsorption of alkali atoms involves a charge transfer process, creating positively-charged alkali atoms and this polarizes the H2 molecules and increases their binding energy. The maximum hydrogen storage capacity of Li doped BN fullerene is 8.9 wt.% in which 60 hydrogen atoms were chemisorbed and 12 H2 were adsorbed in molecular form. - Abstract: First-principles calculations have been used to investigate hydrogen adsorption on alkali atom doped B36N36 clusters. The alkali atom adsorption takes place near the six tetragonal bridge sites available on the cage, thereby avoiding the notorious clustering problem. Adsorption of alkali atoms involves a charge transfer process, creating positively charged alkali atoms and this polarizes the H2 molecules thereby, increasing their binding energy. Li atom has been found to adsorb up to three hydrogen molecules with an average binding energy of 0.189 eV. The fully doped Li6B36N36 cluster has been found to hold up to 18 hydrogen molecules with the average binding energy of 0.146 eV. This corresponds to a gravimetric density of hydrogen storage of 3.7 wt.%. Chemisorption on the Li6B36N36 has been found to be an exothermic reaction, in which 60 hydrogen atoms chemisorbed with an average chemisorption energy of -2.13 eV. Thus, the maximum hydrogen storage capacity of Li doped BN fullerene is 8.9 wt.% in which 60 hydrogen atoms were chemisorbed and 12 hydrogen molecules were adsorbed in molecular form.

  8. Theoretical investigation of electronic and magnetic properties of MnAu layers

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, BP 63, 46000, Sidi Bouzid, Safi (Morocco); LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Hlil, E.K. [Institut Neel, CNRS et Universite Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France); Hamedoun, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Mounkachi, O. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Bahmad, L. [LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco)

    2013-01-15

    Self-consistent ab initio calculations, based on the density functional theory (DFT) approach and using the full potential linear augmented plane wave (FLAPW) method, are performed to investigate both electronic and magnetic properties of the MnAu layers. Polarized spin and spin-orbit coupling are included in calculations within the framework of the antiferromagnetic state between two adjacent Mn layers. Magnetic moment considered to lie along a axes are computed. The data obtained from the ab initio calculations are then used as input for the high temperature series expansions (HTSEs) calculation to compute other magnetic parameters. The exchange integrals between the magnetic atoms in the same layer and between the magnetic atoms in the bilayers adjacent are given by using mean field theory. The HTSEs of the magnetic susceptibility of MnAu antiferromagnetic spin-S through two model: Ising and XY layers consisting of l=2, 3, 4, 5, 6 and bulk ({infinity}) interacting layers, are studied to sixth order series in {beta}=1/k{sub B}T obtained for free-surface boundary conditions. The effects of finite size on critical-point behavior are studied by extrapolation of the high-temperature series. The Neel temperature T{sub N}(l) as a function of the number of l spin layers is obtained by HTSEs of the magnetic susceptibility series by using the Pade approximant method and by MFT theory. The critical exponent {gamma} associated with the magnetic susceptibility is deduced. T{sub N}(l) for the l-layers are estimated from the divergence of the staggered susceptibility with an exponent for Ising model of {gamma}(1)=2.96, and for XY model of {gamma}(2)=2.82, which is consistent with the basic assumptions of scaling laws. Our estimates for the shift exponent of the Neel temperature for the two models are obtained. - Highlights: Black-Right-Pointing-Pointer ab initio calculations is using to investigate both electronic and magnetic properties of the MnAu layers. Black

  9. Theoretical and practical investigation into sustainable metal joining process for the automotive industry

    International Nuclear Information System (INIS)

    Currently there are about 4300 weld points on the average steel vehicle. Errors and problems due to tip damage and wear can cause great losses due to production line downtime. Current industrial monitoring systems check the quality of the nugget after processing 15 cars average once every two weeks. The nuggets are examined off line using a destructive process, which takes approximately 10 days to complete causing a long delay in the production process. In this paper a simulation results using software package, SORPAS, will be presented to determined the sustainability factors in spot welding process including Voltage, Current, Force, Water cooling rates, Material thicknesses and usage. The experimental results of various spot welding processes will be investigated and reported. The correlation of experimental results shows that SORPAS simulations can be used as an off line measurement to reduce factory energy usage. This paper also provides an overview of electrode current selection and its variance over the lifetime of the electrode tip, and describes the proposed analysis system for the selection of welding parameters for the spot welding process, as the electrode tip wears.

  10. Theoretical investigation on ESIPT mechanism of a new fluorescent sensor in different solvents.

    Science.gov (United States)

    Yang, Dapeng; Zheng, Rui; Wang, Yusheng; Lv, Jian

    2016-04-15

    In the present work, a new phenylbenzimidazole derivatized fluorescent sensor (L) (J. Lumin. 147 (2014) 179), has been investigated on the excited state proton transfer (ESPT) based on the time-dependent density functional theory (TDDFT) method. The calculated absorption and fluorescence spectra based on the TDDFT method are in agreement with the experimental results. Two kinds of structures of L chromophore are found in the first excited (S1) state, which may be due to the proton transfer reactive. Hydrogen bond strengthening has been testified in the S1 state based on comparing staple bond lengths and bond angles involved in hydrogen bonding between the S0 state and the S1 state. In addition, the calculated infrared spectra at the N-H stretching vibrational region and calculated hydrogen bond energy also declare the phenomenon of hydrogen bond strengthening. The frontier molecular orbitals (MOs) and Mulliken's charge distribution analysis method as well as natural bond orbital (NBO) demonstrate the charge distribution, which provides the tendency of ESIPT reaction. The potential energy surfaces of the S0 and S1 states are constructed to explain the mechanism of the proton transfer in the excited state in detail. In addition, the ESIPT process of sensor L is dependent on different solvents. PMID:26827174

  11. A synthetic, catalytic and theoretical investigation of an unsymmetrical SCN pincer palladacycle.

    Science.gov (United States)

    Roffe, Gavin W; Boonseng, Sarote; Baltus, Christine B; Coles, Simon J; Day, Iain J; Jones, Rhiannon N; Press, Neil J; Ruiz, Mario; Tizzard, Graham J; Cox, Hazel; Spencer, John

    2016-04-01

    The SCN ligand 2-{3-[(methylsulfanyl)methyl]phenyl}pyridine, 1, has been synthesized starting from an initial Suzuki-Miyaura (SM) coupling between 3-((hydroxymethyl)phenyl)boronic acid and 2-bromopyridine. The C-H activation of 1 with in situ formed Pd(MeCN)4(BF4)2 has been studied and leads to a mixture of palladacycles, which were characterized by X-ray crystallography. The monomeric palladacycle LPdCl 6, where L-H = 1, has been synthesized, and tested in SM couplings of aryl bromides, where it showed moderate activity. Density functional theory and the atoms in molecules (AIM) method have been used to investigate the formation and bonding of 6, revealing a difference in the nature of the Pd-S and Pd-N bonds. It was found that S-coordination to the metal in the rate determining C-H bond activation step leads to better stabilization of the Pd(II) centre (by 13-28 kJ mol(-1)) than with N-coordination. This is attributed to the electron donating ability of the donor atoms determined by Bader charges. The AIM analysis also revealed that the Pd-N bonds are stronger than the Pd-S bonds influencing the stability of key intermediates in the palladacycle formation reaction pathway. PMID:27152207

  12. Experimental and theoretical investigation of the iron core transformer for the EXTRAP T1 device

    International Nuclear Information System (INIS)

    The possibility of driving the discharge current of the toroidal EXTRAP T1 device, using the iron core transformer, is investigated. It is shown that the breakdown voltage 20 kV can be supplied, along the zero line of the vacuum magnetic field, at a time shorter than 1 μs. this is made possible by the transient build-up of the magnetic field in the iron core laminations. The plasma current rise time is determined by the evolution of the inductance and resistance of the discharge. This enables the plasma current to be built up to an amplitude I(sub)p=50 kA within 10-15 μs and sustained at this value during a steady-state period of 100 μs. The premagnetized iron core of the cross-sectional area 0.16 m2 is sufficient to provide the necessary flux swing, if the saturation induction is not lower than 1 T. It is further concluded that the SiFe lamination is adequate for the present application. However, to reduce the stray field interfering with the zero line of the octupole field, a lamination of thickness d < 0.1 mm with high resistivity should be employed. The interlamination voltage should be reduced by segmenting the core. The steady-state is supplied by an 0.4Ω, 20 kV artificial line consisting of 20 μF capacitive elements. (author)

  13. Intermolecular Sulfur···Oxygen Interactions: Theoretical and Statistical Investigations.

    Science.gov (United States)

    Zhang, Xuejin; Gong, Zhen; Li, Jian; Lu, Tao

    2015-10-26

    Intermolecular S···O interactions are very common and are important in biological systems, but until recently, the presence of these contacts in protein-ligand systems largely depended on serendipitous discovery instead of rational design. Here we provide insight into the phenomenon of intermolecular S···O contacts by focusing on three sulfur-containing aromatic rings. Quantum mechanics is employed to characterize the strength and directionality of the S···O interactions and to determine their energy dependence on their geometric parameters. Protein Data Bank mining is performed to systematically determine the occurrence and geometry of intermolecular S···O interactions, and several representative examples are discussed. Three typical cases are investigated using a combined quantum mechanics/molecular mechanics approach to demonstrate the potential of these interactions in improving binding affinities and physiochemical properties. Overall, our work elucidates the structures and energy features of intermolecular S···O interactions and addresses their use in molecular design. PMID:26393532

  14. Theoretical Investigation of Creeping Viscoelastic Flow Transition Around a Rotating Curved Pipe

    CERN Document Server

    Hamza, S E E

    2015-01-01

    The study of creeping motion of viscoelastic fluid around a rotating rigid torus is investigated. The analysis of the problem is performed using a second-order viscoelastic model. The study is carried out in terms of the bipolar toroidal system of coordinates where the toroid is rotating about its axis of symmetry (z-axis). The problem is solved within the frame of slow flow approximation. Therefore, all variables in the governing equations are expanded in a power series of angular velocity. A set of successive partial differential equations is obtained. The equations of motion governing the first and second-order are formulated and solved for the first-order only in this paper. However, the solution of the second-order equations will be the subject of a part two of this series of papers. Analytically, Laplace's equation is solved via the usual method of separation of variables. This method shows that, the solution is given in a form of infinite sums over Legendre functions of the first and second kinds. From...

  15. Experimental and theoretical investigation of droplet emission from tungsten melt layer

    International Nuclear Information System (INIS)

    Tungsten in form of macrobrush structure is foreseen as one of candidate materials for the ITER divertor and the dome. Melting of tungsten and the following melt motion and melt splashing are expected to be the main mechanisms of damage which determine the lifetime of plasma facing components. New experimental investigations of droplet emission from the W melt layer for the Edge Localised Mode (ELM)-like heat loads have been carried out at the plasma gun facility quasistationary plasma accelerators (QSPA-T). In these experiments the threshold for droplet emission and the distributions of velocity on emission angles and amplitude of the ejected droplets were determined. In the paper the main physical mechanism (the Kelvin-Helmholtz instability) of the melt splashing under the heat loads being applied at QSPA-T and those anticipated after the ITER transients is analyzed. These numerical simulations demonstrated a reasonable agreement with the experimental data on the droplet sizes and droplet velocities and allowed the projections upon the W melt splashing at ITER conditions.

  16. Experimental and Theoretical Investigation of Multispecies Oral Biofilm Resistance to Chlorhexidine Treatment

    Science.gov (United States)

    Shen, Ya; Zhao, Jia; de La Fuente-Núñez, César; Wang, Zhejun; Hancock, Robert E. W.; Roberts, Clive R.; Ma, Jingzhi; Li, Jun; Haapasalo, Markus; Wang, Qi

    2016-06-01

    We investigate recovery of multispecies oral biofilms following chlorhexidine gluconate (CHX) and CHX with surface modifiers (CHX-Plus) treatment. Specifically, we examine the percentage of viable bacteria in the biofilms following their exposure to CHX and CHX-Plus for 1, 3, and 10 minutes, respectively. Before antimicrobial treatment, the biofilms are allowed to grow for three weeks. We find that (a). CHX-Plus kills bacteria in biofilms more effectively than the regular 2% CHX does, (b). cell continues to be killed for up to one week after exposure to the CHX solutions, (c). the biofilms start to recover after two weeks, the percentage of the viable bacteria recovers in the 1 and 3 minutes treatment groups but not in the 10 minutes treatment group after five weeks, and the biofilms fully return to the pretreatment levels after eight weeks. To understand the mechanism, a mathematical model for multiple bacterial phenotypes is developed, adopting the notion that bacterial persisters exist in the biofilms together with regulatory quorum sensing molecules and growth factor proteins. The model reveals the crucial role played by the persisters, quorum sensing molecules, and growth factors in biofilm recovery, accurately predicting the viable bacterial population after CHX treatment.

  17. Theoretical And Experimental Investigations On The Plasma Of A CO2 High Power Laser

    Science.gov (United States)

    Abel, W.; Wallter, B.

    1984-03-01

    The CO2 high power laser is increasingly used in material processing. This application of the laser has to meet some requirements: at one hand the laser is a tool free of wastage, but at the other hand is to guarantee that the properties of that tool are constant in time. Therefore power, geometry and mode of the beam have to be stable over long intervalls, even if the laser is used in rough industrial environment. Otherwise laser material processing would not be competitive. The beam quality is affected by all components of the laser - by the CO2 plasma and its IR - amplification, by the resonator which at last generates the beam by optical feedback, and also by the electric power supply whose effects on the plasma may be measured at the laser beam. A transversal flow laser has been developed at the Technical University of Vienna in cooperation with VOest-Alpine AG, Linz (Austria). This laser produces 1 kW of beam power with unfolded resonator. It was subject to investigations presented in this paper.

  18. Theoretical and experimental investigation of thermohydrologic processes in a partially saturated, fractured porous medium

    Energy Technology Data Exchange (ETDEWEB)

    Green, R.T.; Manteufel, R.D. [Nuclear Regulatory Commission, Washington, DC (United States). Div. of Regulatory Applications; Dodge, F.T.; Svedeman, S.J. [Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses

    1993-07-01

    The performance of a geologic repository for high-level nuclear waste will be influenced to a large degree by thermohydrologic phenomena created by the emplacement of heat-generating radioactive waste. The importance of these phenomena is manifest in that they can greatly affect the movement of moisture and the resulting transport of radionuclides from the repository. Thus, these phenomena must be well understood prior to a definitive assessment of a potential repository site. An investigation has been undertaken along three separate avenues of analysis: (i) laboratory experiments, (ii) mathematical models, and (iii) similitude analysis. A summary of accomplishments to date is as follows. (1) A review of the literature on the theory of heat and mass transfer in partially saturated porous medium. (2) A development of the governing conservation and constitutive equations. (3) A development of a dimensionless form of the governing equations. (4) A numerical study of the importance and sensitivity of flow to a set of dimensionless groups. (5) A survey and evaluation of experimental measurement techniques. (6) Execution of laboratory experiments of nonisothermal flow in a porous medium with a simulated fracture.

  19. Theoretical Investigations of Nonlinear Optical Properties of Transition Metal Cluster Anions

    Institute of Scientific and Technical Information of China (English)

    LIU Cai-Ping; SA Rong-Jian; MANG Chao-Yong; LI Qiao-Hong; LI Fu-Jun; WU Ke-Chen

    2008-01-01

    In the framework of density functional theory (DFT), the electronic excitations and nonlinear optical (NLO) properties of six binuelear transition metal cluster anions with the formula of [Ch2M-(μ-Ch)2-M'CN]2-(M = Mo, W; Ch = S, Se; M' = Cu, Ag) have been systemically investigated at both cases of gas phase and DMF solution. The obtained electronic absorption spectra reveal that the element replacements of metals M and ligands Ch have significant influence on the absorptions, especially on the low-lying ones. In addition, the transitions of μ-Ch→M are dominant for the low-lying excitations, whereas the transitions of M'→M as well as Ch→M are mainly responsible for the higher excitations. The calculated molecular first and second hyper- polarizabilities present the remarkable element substitution and solvent effects. The analyses show that the transitions involving μ-Ch→M charge transfer make the critical contributions to the first hyperpolarizability β, and that the charge transfers from the moieties of MCh4 to M'CN as well as those of β-Ch→M and M'→M are responsible for the second hyperpolarizability γ. Moreover, the introduction of solvent leads to the results that the transitions within the moieties of MCh4 and M'CN make larger contributions to the hyperpolafizability, especially to γ.

  20. Theoretical Investigation on the Solubilization in Water of Functionalized Single-Wall Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Michael Mananghaya

    2012-01-01

    Full Text Available An important technique to increase the solubility and reactivity of carbon nanotube is through functionalization. In this study, the effects of functionalization of some single-walled carbon nanotubes (SWCNTs were investigated with the aid of density functional theory. The SWCNT model used in the study consists of a finite, (5, 0 zigzag nanotube segment containing 60 C atoms with hydrogen atoms added to the dangling bonds of the perimeter carbons. There are three water-dispersible SWCNTs used in this study that were functionalized with (a formic acid, as a model of carboxylic acid, (b isophthalic acid, as a model aromatic dicarboxylic acid, and (c benzenesulfonic acid, as a model aromatic sulfonic acid. Binding energies of the organic radicals to the nanotubes are calculated, as well as the HOMO-LUMO gaps and dipole moments of both nanotubes and functionalized nanotubes. Binding was found out to be thermodynamically favorable. The functionalization increases the electrical dipole moments and results in an enhancement in the solubility of the nanotubes in water manifested through favorable changes in the free energies of solvation. This should lower the toxicity of nanotubes and improve their biocompatibility.

  1. Theoretical investigation on H abstraction reaction mechanisms and rate constants of Isoflurane with the OH radical

    Science.gov (United States)

    Ren, Hongjiang; Li, Xiaojun

    2015-12-01

    The mechanism of H abstraction reactions for Isoflurane with the OH radical was investigated using density functional theory and G3(MP2) duel theory methods. The geometrical structures of all the species were fully optimised at B3LYP/6-311++G** level of theory. Thermochemistry data were obtained by utilising the high accurate model chemistry method G3(MP2) combined with the standard statistical thermodynamic calculations. Gibbs free energies were used for the reaction channels analysis. All the reaction channels were confirmed throughout the intrinsic reaction coordinate analysis. The results show that two channels were obtained, which correspond to P(1) and P(2) with the respective activation barriers of 63.03 and 54.82 kJ/mol. The rate constants for the two channels over a wide temperature range of 298.15-2000 K were predicted and the calculated data are in agreement with the experimental one. The results show that P(2) is the dominant reaction channel under 800 K and above 800 K, it can be found that P(1) will be more preferable reaction channel.

  2. Theoretical and experimental investigation of thermohydrologic processes in a partially saturated, fractured porous medium

    International Nuclear Information System (INIS)

    The performance of a geologic repository for high-level nuclear waste will be influenced to a large degree by thermohydrologic phenomena created by the emplacement of heat-generating radioactive waste. The importance of these phenomena is manifest in that they can greatly affect the movement of moisture and the resulting transport of radionuclides from the repository. Thus, these phenomena must be well understood prior to a definitive assessment of a potential repository site. An investigation has been undertaken along three separate avenues of analysis: (i) laboratory experiments, (ii) mathematical models, and (iii) similitude analysis. A summary of accomplishments to date is as follows. (1) A review of the literature on the theory of heat and mass transfer in partially saturated porous medium. (2) A development of the governing conservation and constitutive equations. (3) A development of a dimensionless form of the governing equations. (4) A numerical study of the importance and sensitivity of flow to a set of dimensionless groups. (5) A survey and evaluation of experimental measurement techniques. (6) Execution of laboratory experiments of nonisothermal flow in a porous medium with a simulated fracture

  3. A theoretical investigation on influences of slab tracks on vertical dynamic responses of railway viaducts

    Science.gov (United States)

    Shi, Li; Cai, Yuanqiang; Wang, Peng; Sun, Honglei

    2016-07-01

    A railway viaduct model consisting of infinite spans of elastically-supported girders carrying a slab track of infinite length is established to investigate the influence of the slabs on the vertical dynamic response of the viaduct, when a moving harmonic point load or a moving sprung wheel is applied. The infinite rail, the discontinuous slabs and girders of identical span lengths are idealized as Euler-Bernoulli beams. The rail fasteners, the cushion layer beneath the slab and the elastic bearings at the girder supports are represented by discretely distributed springs of hysteretic damping. Due to the repetitive nature of the girders, the model can be divided into periodic three-beam units by the span length of the girder, and then solved analytically in the frequency domain using the property of periodic structure. Besides the first natural frequency of the girder with elastic bearings, it is found that the resonance frequency of the slab on the cushion layer has a significant influence on the dynamic response of the track and the girder. Parametric excitations due to the moving wheel periodically passing the discontinuous slabs contribute significantly to the wheel/rail interactions.

  4. Do inverse dithienylethenes behave as normal ones? A joint spectroscopic and theoretical investigation.

    Science.gov (United States)

    Aloïse, Stéphane; Sliwa, Michel; Buntinx, Guy; Delbaere, Stéphanie; Perrier, Aurélie; Maurel, François; Jacquemin, Denis; Takeshita, Michinori

    2013-05-01

    We investigate an inverse (I) dithienylethene, the bis(3,5-dimethyl-2-thienyl) perfluorocyclopentene, using absorption, emission and NMR spectroscopies as well as state-of-art first-principles (TDDFT) calculations. First, we find in addition to the expected antiparallel and parallel conformers, a new stable antiparallel conformer , but its energy is too high to be significantly populated at working temperature. More importantly, we demonstrate that, instead of an equal proportion of an AP and a P conformer as in normal (N) diarylethenes, the AP conformer is present in large excess. This result is confirmed by both DFT thermodynamical analysis and temperature-dependent NMR experiments modelized with an ↔ fast interconversion model. With the latter, the relative populations are estimated to be ca. 3/1 for /. Furthermore, the 0-0 energies simulated with a model that accounts for both vibrational and state-specific media effects of the ground and the excited states indicate that and have very similar absorption signatures while only the conformer should give rise to emission. Eventually, within excited state manifold, important topological points along the ring-closure reaction coordinate, and more specifically the unprecedented S1(opt) of the closed isomer, have been identified. PMID:23515439

  5. Theoretical investigation of coherent synchrotron radiation induced microbunching instability in transport and recirculation arcs

    CERN Document Server

    Tsai, Cheng-Ying; Li, Rui; Tennant, Christopher

    2014-01-01

    The coherent synchrotron radiation (CSR) of a high brightness electron beam traversing a series of dipoles, such as recirculation or transport arcs, may lead to the microbunching instability. We extend and develop a semi-analytical approach of the CSR-induced microbunching instability for a general lattice, based on the previous formulation with 1-D CSR model [Phys. Rev. ST Accel. Beams 5, 064401 (2002)] and apply it to investigate the physical processes of microbunching amplification for two example transport arc lattices. We find that the microbunching instability in transport arcs has a distinguishing feature of multistage amplification (e.g, up to 6th stage for our example arcs in contrast to two stage amplification for a 3-dipole chicane). By further extending the concept of stage gain as proposed by Huang and Kim [Phys. Rev. ST Accel. Beams 5, 074401 (2002)], we developed a method to quantitatively characterize the microbunching amplification in terms of iterative or staged orders that allows the compar...

  6. Theoretical Investigation of the Exotic Structure of the Mirror Nuclei 17Ne and 17N

    Institute of Scientific and Technical Information of China (English)

    LIANG Yu-Jie; LI Xi-Han; DENG Fu-Guo; LIU Zu-Hua; ZHOU Hong-Yu

    2006-01-01

    @@ The exotic structures of the ground state of the mirror nuclei 17Ne and 17N are investigated by means of the asymptotic normalization coefficient (ANC) method to explore the role of the Coulomb interaction. The probabilities of a valence nucleon outside the binding-potential are P = 56.69±2.987.46%for 17Ne and P = 45.51 ±2.325.81% for 17N. The rms radii are 1/2 5.06±0.110.30 fm and 1/2 = 4.24±0.060.16 fm, respectively. The results obtained are nearly independent of the potential parameters. According to the halo occurrence conditions, it is suggested that 17 Ne is a two-proton halo and 17 N is a two-neutron skin. Moreover, two effects of the Coulomb interaction on the exotic structure are analysed. From the present results, the exotic structure of the nucleus in the proton-rich side is more obvious than that of its mirror nucleus because of the Coulomb interaction.

  7. A synthetic, catalytic and theoretical investigation of an unsymmetrical SCN pincer palladacycle

    Science.gov (United States)

    Roffe, Gavin W.; Boonseng, Sarote; Baltus, Christine B.; Coles, Simon J.; Day, Iain J.; Jones, Rhiannon N.; Press, Neil J.; Ruiz, Mario; Tizzard, Graham J.; Cox, Hazel

    2016-01-01

    The SCN ligand 2-{3-[(methylsulfanyl)methyl]phenyl}pyridine, 1, has been synthesized starting from an initial Suzuki–Miyaura (SM) coupling between 3-((hydroxymethyl)phenyl)boronic acid and 2-bromopyridine. The C–H activation of 1 with in situ formed Pd(MeCN)4(BF4)2 has been studied and leads to a mixture of palladacycles, which were characterized by X-ray crystallography. The monomeric palladacycle LPdCl 6, where L-H = 1, has been synthesized, and tested in SM couplings of aryl bromides, where it showed moderate activity. Density functional theory and the atoms in molecules (AIM) method have been used to investigate the formation and bonding of 6, revealing a difference in the nature of the Pd–S and Pd–N bonds. It was found that S-coordination to the metal in the rate determining C–H bond activation step leads to better stabilization of the Pd(II) centre (by 13–28 kJ mol−1) than with N-coordination. This is attributed to the electron donating ability of the donor atoms determined by Bader charges. The AIM analysis also revealed that the Pd–N bonds are stronger than the Pd–S bonds influencing the stability of key intermediates in the palladacycle formation reaction pathway.

  8. Theoretical investigations of the 12C(α,γ)16OE2 cross section

    International Nuclear Information System (INIS)

    The E2 component of the 12C(α,γ)16O cross section is investigated in three ways: by a microscopic cluster model, by R-matrix fits and by a combination of both. The microscopic calculation leads to an estimate of the S-factor at a typical energy of 300 keV of SE2(300 keV)≈ 50 keV-b for ground-state transitions. Cascade transitions to the 02+ and 21+ excited states of 16O are also studied. Then the S-factor is analyzed in the phenomenological R-matrix theory. We show that the background term plays a crucial role, and cannot be determined without ambiguity. Consequently only an upper limit on the extrapolated S-factor can be obtained [SE2(300 keV)< 190 keV-b]. Finally, we use the microscopic Asymptotic Normalization Constant (ANC) of the 21+ level, well known to be a cluster state to constrain the R-matrix analysis. This procedure strongly reduces the uncertainties on the R-matrix fits, and we end up with a recommended value of SE2(300 keV) = 42 ± 2 keV-b. (author)

  9. Theoretical Investigation of Detailed Thermodynamic Character of Possible Difunctional Adducts Model

    Institute of Scientific and Technical Information of China (English)

    CHANG Guan-Ru; ZHOU Li-Xin; CHEN Dong

    2006-01-01

    The B3LYP/6-31G* level of theory was used to optimize trans-[Pt(NH3)(Am)G-L], where Am = quinoline or thiazole and L is chosen as the model for functional groups of peptide side chains, and for adenine and guanine sites of DNA as the ultimate target of platinum anticancer drugs. Bond dissociating energy and stability energy of complexes are chosen to study detailedly ther- modynamic character of possible difunctional adducts model. In order to investigate the influence of a polarizable environment on the energy of the Pt-L bond formation, we adopt a new bonding energy formula brought forward by Lippard and his coworkers: ΔH(Sol) = ΔH(SCF) + ΔG(Solv), which is quite appropriate to compare with what is found in experimental studies. Our calculated results demonstrate that N-containing ligands are more favored in view of thermodynamics both in gas phrase and in solution. However, it is worthly to be noted that addition of solvation free energies result in moderate correction of bonding energy in relative ordering, and the largest ones both present in imidazole ligand, not in guanine ligand. Finally, the nature of bond is analyzed in terms of partial charges distribution based on NBO population.

  10. A Theoretical Investigation of Decay and Energy Transfer Rates and Efficiencies Near Gold Nanospheres

    CERN Document Server

    Marocico, Cristian A; Bradley, A Louise

    2015-01-01

    We consider the effect of Au nanospheres of subwavelength sizes on the decay and energy transfer rates of quantum systems placed in the proximity of these nanospheres. We find that, for the sphere sizes considered in this contribution, the radiative decay rate is barely affected by the presence of the nanosphere, whereas the non-radiative decay rate is greatly enhanced due to energy transfer from the quantum system to the nanosphere, leading to a strong quenching of the emission of the quantum system. The emission wavelength of the quantum emitter and its intrinsic quantum yield play an important role and the impact of both has to be considered together when investigating their effect on the non-radiative decay rate. The energy transfer process from the emitter to the nanosphere has a complicated distance dependence, with a 1/r^6 regime, characteristic of the F\\"orster energy transfer mechanism, but also exhibiting other distance dependence regimes. In the case of a donor-acceptor pair in the presence of a Au...

  11. Experimental and Theoretical Investigation of Multispecies Oral Biofilm Resistance to Chlorhexidine Treatment.

    Science.gov (United States)

    Shen, Ya; Zhao, Jia; de la Fuente-Núñez, César; Wang, Zhejun; Hancock, Robert E W; Roberts, Clive R; Ma, Jingzhi; Li, Jun; Haapasalo, Markus; Wang, Qi

    2016-01-01

    We investigate recovery of multispecies oral biofilms following chlorhexidine gluconate (CHX) and CHX with surface modifiers (CHX-Plus) treatment. Specifically, we examine the percentage of viable bacteria in the biofilms following their exposure to CHX and CHX-Plus for 1, 3, and 10 minutes, respectively. Before antimicrobial treatment, the biofilms are allowed to grow for three weeks. We find that (a). CHX-Plus kills bacteria in biofilms more effectively than the regular 2% CHX does, (b). cell continues to be killed for up to one week after exposure to the CHX solutions, (c). the biofilms start to recover after two weeks, the percentage of the viable bacteria recovers in the 1 and 3 minutes treatment groups but not in the 10 minutes treatment group after five weeks, and the biofilms fully return to the pretreatment levels after eight weeks. To understand the mechanism, a mathematical model for multiple bacterial phenotypes is developed, adopting the notion that bacterial persisters exist in the biofilms together with regulatory quorum sensing molecules and growth factor proteins. The model reveals the crucial role played by the persisters, quorum sensing molecules, and growth factors in biofilm recovery, accurately predicting the viable bacterial population after CHX treatment. PMID:27325010

  12. Theoretical and experimental investigations of flow pulsation effects in Coriolis mass flowmeters

    Science.gov (United States)

    Svete, A.; Kutin, J.; Bobovnik, G.; Bajsić, I.

    2015-09-01

    An understanding of the effects of flow pulsations on the dynamic behavior of Coriolis flowmeters is very important for their further development. In order to determine the phase difference between the vibrational signals, which represents the basic measurement effect of Coriolis flowmeters, there are many methods that include the proper filtering of all the signal components, except those with frequencies close to the drive frequency. Therefore, an understanding of the phenomenon of exciting the meter at its first natural frequency is very important. The results of a simple, linear, two-degree-of-freedom, lumped-parameter, dynamic model of a flowmeter show that the flow pulsations can degrade the accuracy of such a flowmeter as a result of indirect excitations of the measuring tube at the first natural frequency through the second-order perturbations by means of the Coriolis forces induced in pulsating flow conditions. In order to experimentally investigate these flow pulsation effects, a prototype of a straight-tube Coriolis mass flowmeter was developed to enable the processing of the response signals logged directly from the flow tube's sensors with the dual quadrature demodulation method, and therefore to provide the information available within the phase-difference data. The experimental results show that the flow pulsations upset the meter at its first natural frequency indirectly, as well as directly at the frequency of the pulsations due to the geometric imperfections of the measuring tube.

  13. An experimental and theoretical investigation of loperamide hydrochloride-glutaric acid cocrystals.

    Science.gov (United States)

    Bruni, Giovanna; Maietta, Mariarosa; Maggi, Lauretta; Mustarelli, Piercarlo; Ferrara, Chiara; Berbenni, Vittorio; Freccero, Mauro; Scotti, Federico; Milanese, Chiara; Girella, Alessandro; Marini, Amedeo

    2013-07-11

    Cocrystallization is a powerful method to improve the physicochemical properties of drugs. Loperamide hydrochloride is a topical analgesic for the gastrointestinal tract showing low and pH-dependent solubility; for this reason, an enhancement of its solubility or dissolution rate, particularly at the pH of the intestinal tract, could improve its local efficacy. Here we prepared cocrystals of this active principle with glutaric acid and so obtained a new crystalline solid representing a viable alternative to improve the physicochemical properties and thus the pharmaceutical behavior of the drug. Differential scanning calorimetry, X-ray powder diffraction, Fourier infrared spectroscopy, solid-state NMR, and scanning electron microscopy coupled to the energy-dispersive X-ray spectrometry were used to investigate the new solid-phase formation. DFT calculations at B3LYP/6-31G(d) level of theory, in the gas phase, including frequencies computation, provided a rationale for the interaction between loperamide hydrochloride and glutaric acid. The cocrystals showed improved water solubility in comparison with loperamide HCl, and the pharmaceutical formulation proposed was able to release the drug more rapidly in comparison with three reference commercial products when tested at neutral pH values. PMID:23763498

  14. THEORETICAL INVESTIGATION OF MICROSTRUCTURE EVOLUTION AND DEFORMATION OF ZIRCONIUM UNDER CASCADE DAMAGE CONDITIONS

    Energy Technology Data Exchange (ETDEWEB)

    Barashev, Alexander V [ORNL; Golubov, Stanislav I [ORNL; Stoller, Roger E [ORNL

    2012-06-01

    This work is based on our reaction-diffusion model of radiation growth of Zr-based materials proposed recently in [1]. In [1], the equations for the strain rates in unloaded pure crystal under cascade damage conditions of, e.g., neutron or heavy-ion irradiation were derived as functions of dislocation densities, which include contributions from dislocation loops, and spatial distribution of their Burgers vectors. The model takes into account the intra-cascade clustering of self-interstitial atoms and their one-dimensional diffusion; explains the growth stages, including the break-away growth of pre-annealed samples; and accounts for some striking observations, such as of negative strain in prismatic direction, and co-existence of vacancy- and interstitial-type prismatic loops. In this report, the change of dislocation densities due to accumulation of sessile dislocation loops is taken into account explicitly to investigate the dose dependence of radiation growth. The dose dependence of climb rates of dislocations is calculated, which is important for the climb-induced glide model of radiation creep. The results of fitting the model to available experimental data and some numerical calculations of the strain behavior of Zr for different initial dislocation structures are presented and discussed. The computer code RIMD-ZR.V1 (Radiation Induced Microstructure and Deformation of Zr) developed is described and attached to this report.

  15. Theoretical Investigation on the Solubilization in Water of Functionalized Single-Wall Carbon Nano tubes

    International Nuclear Information System (INIS)

    An important technique to increase the solubility and reactivity of carbon nano tube is through functionalization. In this study, the effects of functionalization of some single-walled carbon nano tubes (SWCNTs) were investigated with the aid of density functional theory. The SWCNT model used in the study consists of a finite, (5, 0) zigzag nano tube segment containing 60 C atoms with hydrogen atoms added to the dangling bonds of the perimeter carbons. There are three water-dispersible SWCNTs used in this study that were functionalized with (a) formic acid, as a model of carboxylic acid, (b) isophthalic acid, as a model aromatic dicarboxylic acid, and (c) benzenesulfonic acid, as a model aromatic sulfonic acid. Binding energies of the organic radicals to the nano tubes are calculated, as well as the HOMO-LUMO gaps and dipole moments of both nano tubes and functionalized nano tubes. Binding was found out to be thermodynamically favorable. The functionalization increases the electrical dipole moments and results in an enhancement in the solubility of the nano tubes in water manifested through favorable changes in the free energies of solvation. This should lower the toxicity of nano tubes and improve their biocompatibility.

  16. Theoretical investigation of the mechanism of tritiated methane dehydrogenation reaction using nickel-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Liang; Li, Jiamao; Deng, Bing; Yang, Yong; Wang, Heyi [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Li, Weiyi [School of Physics and Chemistry, Xihua University, Chengdu 610065 (China); Li, Shuo, E-mail: lishuo@cqut.edu.cn [School of Chemical Engineering, Chongqing University of Technology, Chongqing 400054 (China); Tan, Zhaoyi, E-mail: tanzhaoyi@caep.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2015-06-15

    Graphical abstract: - Highlights: • Four-step dehydrogenation of CT{sub 4} catalyzed by Ni to form Ni–C by releasing T{sub 2}. • The process of Ni + CT{sub 4} → NiCT{sub 2} + T{sub 2} is more achievable than that of NiCT{sub 2} → NiC + T{sub 2}. • TNiCT → T{sub 2}NiC step is the RDS with the rate constant of k = 2.8 × 10{sup 13} exp(−313,136/RT). • The hydrogen isotope effect value of k{sub H}/k{sub T} is 2.94, and k{sub D}/k{sub T} is 1.39. • CH{sub 4} and CD{sub 4} dehydrogenations are likely to occur, accompanied by the CT{sub 4} cracking. - Abstract: The mechanism of tritiated methane dehydrogenation reaction catalyzed by nickel-based catalyst was investigated in detail by density functional theory (DFT) at the B3LYP/[6-311++G(d, p), SDD] level. The computational results indicated that the dehydrogenation of tritiated methane is endothermic. The decomposition of tritiated methane catalyzed by Ni to form Ni-based carbon (Ni–C) after a four-step dehydrogenation companied with releasing tritium. After the first and second dehydrogenation steps, Ni + CT{sub 4} formed NiCT{sub 2}. After the third and fourth dehydrogenation steps, NiCT{sub 2} formed NiC. The first and second steps of dehydrogenation occurred on both the singlet and triplet states, and the lowest energy route is Ni + CT{sub 4} → {sup 1}COM → {sup 1}TS1 → {sup 3}IM1 → {sup 3}TS2 → {sup 3}IM2. The third and fourth steps of dehydrogenation occurred on both the singlet and quintet states, and the minimum energy reaction pathway appeared to be IM3 → {sup 1}TS4 → {sup 5}IM4 → {sup 5}TS5 → {sup 5}IM5 → {sup 5}pro + T{sub 2}. The fourth step of dehydrogenation TNiCT → T{sub 2}NiC was the rate-determining step of the entire reaction with the rate constant of k{sub 2} = 2.8 × 10{sup 13} exp(−313,136/RT) (in cm{sup 3} mol{sup −1} s{sup −1}), and its activation energy barrier was calculated to be 51.8 kcal/mol. The Ni-catalyzed CH{sub 4} and CD{sub 4} cracking

  17. Experimental and theoretical investigations of mercury adsorption on hematite (1-102) surfaces

    Science.gov (United States)

    Jung, J.; Wilcox, J.; Jew, A. D.; Rupp, E. C.; Brown, G. E.

    2013-12-01

    Fly ash is a primary byproduct of the coal combustion process. The release of fly ash into the environment and its use in consumer products are public health concerns because of the presence of toxic trace metals and metalloids, such as mercury (Hg), selenium (Se), and arsenic (As), which may exist as components of fly ash, partition onto fly ash as it cools, or is lost to the environment through smoke stacks in a vapor phase. Therefore, it is important to understand the components of fly ash and their interaction with trace metals. In this study, calculations using density functional theory (DFT) were carried out in conjunction with experimental studies to investigate the interaction between Hg and hematite, an important mineral component of fly ash. Our experimental study, designed to simulate Hg sorption in a coal-fired power plant exhaust system, involved exposure of the fine fraction of bituminous coal fly ash (≤ 0.1 μm) to methane combustion flue gas, supplemented with SO2, NOx, HCl, and Hg in a packed-bed reactor. Sorption reaction products were characterized by synchrotron-based x-ray fluorescence mapping (s-XRF), x-ray diffraction (XRD), and extended x-ray absorption fine structure (EXAFS) spectroscopy. Preliminary s-XRF results showed that Hg in the sample is correlated with Fe, S, Cl, Br, and to a lesser extent with Se and As. From the XRD analysis, the dominant mineral phases detected were quartz, iron oxide (hematite), and various sulfate-bearing cements. Based on the experimental results, DFT studies were carried out to investigate the adsorption of Hg on hematite (α-Fe2O3) (1-102) surfaces. The two α-Fe2O3 (1-102) surfaces modeled consisted of two different surface terminations: (1) M2-clean, which corresponds to the oxygen terminated r-cut surface with the first layer of cations removed and no hydroxyl group and (2) M2-OH2-OH which has bihydroxylated top oxygen atoms and a second layer of hydroxylated oxygen atoms. These surface terminations

  18. A theoretical and numerical investigation of travelling wave induction microfluidic pumping in a temperature gradient

    International Nuclear Information System (INIS)

    The phenomenon of induction electrohydrodynamics (EHD) has recently received great attention as a promising driving mechanism for microfluidic pumping due to its miniaturization capability. To obtain a high working efficiency of induction micropumps, a vertical temperature gradient can be imposed along the depth of a pump channel. A travelling wave (TW) potential signal propagating along an electrode array at the channel substrate interacts with this conductive heat flux, resulting in a local free charge distribution inside the bulk fluid. The induced charge wave lags behind the voltage wave in the spatial phase, and this out-of-phase polarization based pumping effect exhibits a single structural dispersion at charge relaxation frequency of the dielectric system. The classical model of electrothermal flow has always been used to numerically obtain the flow field of TW pumps, but the effect of its small temperature gradient approximation has rarely been investigated. In this study, an enhanced treatment for induction EHD modelling is developed, in which the deflection of potential contour lines caused by large temperature gradients is successfully characterized by an advection–diffusion equation, and a more accurate expression of electrothermal body force is derived and introduced to fluid dynamics as a source term of electrical origin. For the calculation of a repulsion-type induction micropump, although both models present similar results in a small thermal gradient, the enhanced one can provide more exact frequency-dependence of the pump performance and spatial distribution of electrostatic force as well as the resulting velocity profile in an excessive heat flux. Furthermore, a model extension for Joule heating induced TW pumping is also presented, and surprisingly matches the unexpected nonlinear fluid flow behaviour at higher conductivities as reported in a pioneering literature. These results can provide valuable insights into induction pumping of lab

  19. Theoretical Investigation on Structures and Nonlinear Optical Properties of the Alkalis and Low Coordination Acenes Salt

    International Nuclear Information System (INIS)

    The alkalis and low coordination acenes salts alpha-M at the rate of n-acenes (M = Li, Na and K) salts (n = 1, 2 and 3) were designed to investigate the effect of the increasing atomic number of alkali metals and the number n of conjugated benzenoid rings on the nonlinear optical responses. Alkalis Li, Na and K were selected herein, and both DFT (M05-2X, M06-2X and PBE0) and MP2 methods and 6-311+G(D) basis set are employed to optimize geometrical structures and to calculate the polarizability (alpha/sub 0/) and first hyperpolarizability (beta/sub vec/) of the alpha-M at the rate of n-acenes (M = Li, Na and K) salts (n = 1, 2 and 3). Results show that the alpha/sub 0/ values of alpha-M at the rate of n-acenes (M = Li, Na and K) salts (n = 1, 2 and 3) increase with increasing number of n conjugated benzenoid rings and the atomic number of alkali metals and beta/sub vec/ values of alpha-M at the rate of n-acenes (M = Li, Na and K) salts (n = 1, 2 and 3) are opposite. The beta/sub vec/ values of alpha-M at the rate of n-acenes (M = Li, Na and K) salts (n = 1, 2 and 3) are increasing remarkably (397.6 au. for alpha-Li at the rate of benzene < 1196.5 au. for alpha-Na at the rate of benzene < 1608.6 au. for alpha-K at the rate of benzene and tending to decease with increasing number of n by M06-2X method. Our present research may be favorable to the development of excellent nonlinear optical (NLO) materials. (author)

  20. Gas-Phase Thermal Tautomerization of Imidazole-Acetic Acid: Theoretical and Computational Investigations

    Directory of Open Access Journals (Sweden)

    Saadullah G. Aziz

    2015-11-01

    Full Text Available The gas-phase thermal tautomerization reaction between imidazole-4-acetic (I and imidazole-5-acetic (II acids was monitored using the traditional hybrid functional (B3LYP and the long-range corrected functionals (CAM-B3LYP and ωB97XD with 6-311++G** and aug-cc-pvdz basis sets. The roles of the long-range and dispersion corrections on their geometrical parameters, thermodynamic functions, kinetics, dipole moments, Highest Occupied Molecular Orbital–Lowest Unoccupied Molecular Orbital (HOMO–LUMO energy gaps and total hyperpolarizability were investigated. All tested levels of theory predicted the preference of I over II by 0.750–0.877 kcal/mol. The origin of predilection of I is assigned to the H-bonding interaction (nN8→σ*O14–H15. This interaction stabilized I by 15.07 kcal/mol. The gas-phase interconversion between the two tautomers assumed a 1,2-proton shift mechanism, with two transition states (TS, TS1 and TS2, having energy barriers of 47.67–49.92 and 49.55–52.69 kcal/mol, respectively, and an sp3-type intermediate. A water-assisted 1,3-proton shift route brought the barrier height down to less than 20 kcal/mol in gas-phase and less than 12 kcal/mol in solution. The relatively high values of total hyperpolarizability of I compared to II were interpreted and discussed.

  1. Experimental and theoretical investigation of anomalous behavior in rotational bands at high spin

    International Nuclear Information System (INIS)

    High spin states of the barium nuclei have been investigated via the 114Cd(16O,4n)126Ba, 120Sn(12C,4n)128Ba and 124Sn(12C,4n)132Ba reactions. The even spin positive parity yrast band in 126Ba has been excited up to the 16+, and possibly the 18+ state. In addition, another strongly excited band was excited with spins and parities: 7-, 9-, 11-, 13- and 15-. In 128Ba, the even spin positive parity band has been excited up to the 12+ state. Backbending seems to begin at the 12+ state. Two-quasiparticles-plus-rotor bandmixing calculations have been performed in order to explain the backbending and the anomalous negative parity bands observed in 126128Ba and several other nuclei. The test case of 68156Er88 was studied in detail. Good agreement with experimental excitation energies was obtained. The E2 transition rates between the negative parity yrast states were estimated for 156Er. Strongly enhanced rates are found within the states of odd spin, and within the state of even spin. The values of the g-factors were also estimated for the two-quasineutron yrast states in 156Er, showing considerable deviations from the rotational values. The calculation was applied, with very similar results to 56126Ba70. Reasonable fits to the excitation energies were obtained. The case of 46104Pd58 was considered, and very similar results were obtained. The nucleus 80192Hg112 was also studied. No reasonable fit was obtained for the negative parity states. The above evidence suggests that decoupling effects are responsible for the anomalous high spin behavior of the nuclei considered

  2. Theoretical investigation of lead vapor adsorption on kaolinite surfaces with DFT calculations

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xinye [Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096 (China); Huang, Yaji, E-mail: heyyj@seu.edu.cn [Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096 (China); Pan, Zhigang [College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009 (China); Wang, Yongxing; Liu, Changqi [Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096 (China)

    2015-09-15

    Highlights: • Al surface after dehydroxylation is active while Si surface is inert. • The active sites are the unsaturated Al atoms and O atoms losing H atom. • PbO is the most suitable species for adsorption. • Increasing the activities of Al atoms can enhance the performance of kaolinite. • Produce of amorphous silica is a potential path to enhance the performance of kaolinite. - Abstract: Kaolinite can be used as the in-furnace sorbent/additive to adsorb lead (Pb) vapor at high temperature. In this paper, the adsorptions of Pb atom, PbO molecule and PbCl{sub 2} molecule on kaolinie surfaces were investigated by density functional theory (DFT) calculation. Si surface is inert to Pb vapor adsorption while Al surfaces with dehydroxylation are active for the unsaturated Al atoms and the O atoms losing H atoms. The adsorption energy of PbO is much higher than that of Pb atom and PbCl{sub 2}. Considering the energy barriers, it is easy for PbO and PbCl{sub 2} to adsorb on Al surfaces but difficult to escape. The high energy barriers of de–HCl process cause the difficulties of PbCl{sub 2} to form PbO·Al{sub 2}O{sub 3}·2SiO{sub 2} with kaolinite. Considering the inertia of Si atoms and the activity of Al atoms after dehydroxylation, calcination, acid/alkali treatment and some other treatment aiming at amorphous silica producing and Al activity enhancement can be used as the modification measures to improve the performance of kaolinite as the in-furnace metal capture sorbent.

  3. Theoretical investigation of interaction between a rectangular plate and fractional viscoelastic foundation

    Directory of Open Access Journals (Sweden)

    Chengcheng Zhang

    2014-08-01

    Full Text Available The interaction between plates and foundations is a typical problem encountered in geotechnical engineering. The long-term plate performance is highly dependent on the rheological characteristics of ground soil. Compared with conventional linear rheology, the fractional calculus-based theory is a more powerful mathematical tool that can address this issue. This paper proposes a fractional Merchant model (FMM to investigate the time-dependent behavior of a simply supported rectangular plate on viscoelastic foundation. The correspondence principle involving Laplace transforms was employed to derive the closed-form solutions of plate response under uniformly distributed load. The plate deflection, bending moment, and foundation reaction calculated using the FMM were compared with the results obtained from the analogous elastic model (EM and the standard Merchant model (SMM. It is shown that the upper and lower bound solutions of the FMM can be determined using the EM. In addition, a parametric study was performed to examine the influences of the model parameters on the time-dependent behavior of the plate–foundation interaction problem. The results indicate that a small fractional differential order corresponds to a plate resting on a sandy soil foundation, while the fractional differential order value should be increased for a clayey soil foundation. The long-term performance of a foundation plate can be accurately simulated by varying the values of the fractional differential order and the viscosity coefficient. The observations from this study reveal that the proposed fractional model has the capability to capture the variation of plate deflection over many decades of time.

  4. Theoretical investigation of lead vapor adsorption on kaolinite surfaces with DFT calculations

    International Nuclear Information System (INIS)

    Highlights: • Al surface after dehydroxylation is active while Si surface is inert. • The active sites are the unsaturated Al atoms and O atoms losing H atom. • PbO is the most suitable species for adsorption. • Increasing the activities of Al atoms can enhance the performance of kaolinite. • Produce of amorphous silica is a potential path to enhance the performance of kaolinite. - Abstract: Kaolinite can be used as the in-furnace sorbent/additive to adsorb lead (Pb) vapor at high temperature. In this paper, the adsorptions of Pb atom, PbO molecule and PbCl2 molecule on kaolinie surfaces were investigated by density functional theory (DFT) calculation. Si surface is inert to Pb vapor adsorption while Al surfaces with dehydroxylation are active for the unsaturated Al atoms and the O atoms losing H atoms. The adsorption energy of PbO is much higher than that of Pb atom and PbCl2. Considering the energy barriers, it is easy for PbO and PbCl2 to adsorb on Al surfaces but difficult to escape. The high energy barriers of de–HCl process cause the difficulties of PbCl2 to form PbO·Al2O3·2SiO2 with kaolinite. Considering the inertia of Si atoms and the activity of Al atoms after dehydroxylation, calcination, acid/alkali treatment and some other treatment aiming at amorphous silica producing and Al activity enhancement can be used as the modification measures to improve the performance of kaolinite as the in-furnace metal capture sorbent

  5. Theoretical investigation of thermophysical properties in two-temperature argon-helium thermal plasma

    International Nuclear Information System (INIS)

    The thermophysical properties of argon-helium thermal plasma have been studied in the temperature range from 5000 to 40 000 K at atmospheric pressure in local thermodynamic equilibrium and non-local thermodynamic equilibrium conditions. Two cases of thermal plasma considered are (i) ground state plasma in which all the atoms and ions are assumed to be in the ground state and (ii) excited state plasma in which atoms and ions are distributed over various possible excited states. The influence of electronic excitation and non-equilibrium parameter θ = Te/Th on thermodynamic properties (composition, degree of ionization, Debye length, enthalpy, and total specific heat) and transport properties (electrical conductivity, electron thermal conductivity, and thermal diffusion ratio) have been studied. Within the framework of Chapman-Enskog method, the higher-order contributions to transport coefficient and their convergence are studied. The influence of different molar compositions of argon-helium plasma mixture on convergence of higher-orders is investigated. Furthermore, the effect of different definitions of Debye length has also been examined for electrical conductivity and it is observed that electrical conductivity with the definition of Debye length (in which only electrons participate in screening) is less than that of the another definition (in which both the electrons and ions participate in screening) and this deviation increases with electron temperature. Finally, the effect of lowering of ionization energy is examined on electron number density, Debye length, and higher-order contribution to electrical conductivity. It is observed that the lowering of the ionization energy affects the electron transport-properties and consequently their higher-order contributions depending upon the value of the non-equilibrium parameter θ.

  6. Theoretical investigation of interaction between a rectangular plate and fractional viscoelastic foundation

    Institute of Scientific and Technical Information of China (English)

    Chengcheng Zhang; Honghu Zhu; Bin Shi; Linchao Liu

    2014-01-01

    The interaction between plates and foundations is a typical problem encountered in geotechnical en-gineering. The long-term plate performance is highly dependent on the rheological characteristics of ground soil. Compared with conventional linear rheology, the fractional calculus-based theory is a more powerful mathematical tool that can address this issue. This paper proposes a fractional Merchant model (FMM) to investigate the time-dependent behavior of a simply supported rectangular plate on visco-elastic foundation. The correspondence principle involving Laplace transforms was employed to derive the closed-form solutions of plate response under uniformly distributed load. The plate deflection, bending moment, and foundation reaction calculated using the FMM were compared with the results obtained from the analogous elastic model (EM) and the standard Merchant model (SMM). It is shown that the upper and lower bound solutions of the FMM can be determined using the EM. In addition, a parametric study was performed to examine the influences of the model parameters on the time-dependent behavior of the plateefoundation interaction problem. The results indicate that a small fractional differential order corresponds to a plate resting on a sandy soil foundation, while the fractional differential order value should be increased for a clayey soil foundation. The long-term performance of a foundation plate can be accurately simulated by varying the values of the fractional differential order and the viscosity coefficient. The observations from this study reveal that the proposed fractional model has the capability to capture the variation of plate deflection over many decades of time.

  7. Theoretical investigations of the physical properties of zircon-type YVO4

    International Nuclear Information System (INIS)

    The crystal structure, electronic properties, elastic properties, hardness and thermodynamic properties of the laser host material zircon-type YVO4 are studied using the pseudopotential plane wave method within the local density approximation (LDA) and generalized gradient approximation (GGA). The calculated ground state values such as lattice parameter, bulk modulus and its pressure derivative, the band structure and densities of states were in favorable agreement with previous works and the existed experimental data. The elastic constants Cij, the aggregate elastic moduli (B, G, E), Poisson's ratio and elastic anisotropy have been investigated. In YVO4, V–O bonds with shorter bond length and larger Mulliken population make great contribution to hardness than Y–O bonds. Using quasi-harmonic Debye model considering the phonon effects, bulk modulus, heat capacity and thermal expansion coefficient of YVO4 are calculated within a range of 0–6 GPa and 0–1200 K. - Graphical Abstract: (a) Directional dependence of Young's modulus in zircon-type YVO4 and (b) projections of the directional dependent Young's modulus in different planes for zircon-type YVO4. The units are in GPa. Highlights: ► This paper systematically studied the physical properties of zircon-type YVO4 from first-principles calculations. ► Zircon-type YVO4 is mechanically stable and it is ductile for B/G>1.75 and v>0.26. ► Universal elastic anisotropy index AU for zircon-type YVO4 is 2.41, so YVO4 is anisotropic. ► V–O bonds with shorter bond length and larger Mulliken population make greater contribution to the hardness of YVO4.

  8. Combined experimental and theoretical investigation of interactions between kaolinite inner surface and intercalated dimethyl sulfoxide

    International Nuclear Information System (INIS)

    Graphical abstract: Snapshot of the kaolinite–DMSO system after equilibrium is reached. - Highlights: • Dimethyl sulfoxide arranges a monolayer structure between kaolinite layers. • Weak hydrogen bonds exist between methyl groups of dimethyl sulfoxide and kaolinite silica layer. • Intercalated dimethyl sulfoxide forms strong hydrogen bonds with kaolinite alumina layer. - Abstract: Kaolinite intercalation complex with dimethyl sulfoxide (DMSO) was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry–differential scanning calorimetry (TG–DSC) combined with molecular dynamics simulation. The bands assigned to the OH stretching of inner surface of kaolinite were significantly perturbed after intercalation of DMSO into kaolinite. Additionally, the bands attributed to the vibration of gibbsite-like layers of kaolinite shifted to the lower wave number, indicating that the intercalated DMSO were strongly hydrogen bonded to the alumina octahedral surface of kaolinite. The slightly decreased intensity of 1031 cm−1 and 1016 cm−1 band due to the in-plane vibration of Si−O of kaolinite revealed that some DMSO molecules formed weak hydrogen bonds with the silicon tetrahedral surface of kaolinite. Based on the TG result of kaolinite–DMSO intercalation complex, the formula of A12Si2O5(OH)4(DMSO)0.7 was obtained, with which the kaolinite–DMSO complex model was constructed. The molecular dynamics simulation of kaolinite–DMSO complex directly confirmed the monolayer structure of DMSO in interlayer space of kaolinite, where the DMSO arranged almost parallel with kaolinite basal surface with all methyl groups being distributed near the interlayer midplane and oxygen atoms orienting toward to the alumina octahedral surface. The radial distribution function between kaolinite and intercalated DMSO verified the strong hydrogen bonds forming between hydroxyl hydrogen atoms of alumina octahedral surface and

  9. Combined experimental and theoretical investigation of interactions between kaolinite inner surface and intercalated dimethyl sulfoxide

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuai [School of Geoscience and Surveying Engineering, China University of Mining & Technology, Beijing 100083 (China); Liu, Qinfu, E-mail: lqf@cumtb.edu.cn [School of Geoscience and Surveying Engineering, China University of Mining & Technology, Beijing 100083 (China); Cheng, Hongfei [School of Geoscience and Surveying Engineering, China University of Mining & Technology, Beijing 100083 (China); Zeng, Fangui [Department of Earth Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

    2015-03-15

    Graphical abstract: Snapshot of the kaolinite–DMSO system after equilibrium is reached. - Highlights: • Dimethyl sulfoxide arranges a monolayer structure between kaolinite layers. • Weak hydrogen bonds exist between methyl groups of dimethyl sulfoxide and kaolinite silica layer. • Intercalated dimethyl sulfoxide forms strong hydrogen bonds with kaolinite alumina layer. - Abstract: Kaolinite intercalation complex with dimethyl sulfoxide (DMSO) was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry–differential scanning calorimetry (TG–DSC) combined with molecular dynamics simulation. The bands assigned to the OH stretching of inner surface of kaolinite were significantly perturbed after intercalation of DMSO into kaolinite. Additionally, the bands attributed to the vibration of gibbsite-like layers of kaolinite shifted to the lower wave number, indicating that the intercalated DMSO were strongly hydrogen bonded to the alumina octahedral surface of kaolinite. The slightly decreased intensity of 1031 cm{sup −1} and 1016 cm{sup −1} band due to the in-plane vibration of Si−O of kaolinite revealed that some DMSO molecules formed weak hydrogen bonds with the silicon tetrahedral surface of kaolinite. Based on the TG result of kaolinite–DMSO intercalation complex, the formula of A1{sub 2}Si{sub 2}O{sub 5}(OH){sub 4}(DMSO){sub 0.7} was obtained, with which the kaolinite–DMSO complex model was constructed. The molecular dynamics simulation of kaolinite–DMSO complex directly confirmed the monolayer structure of DMSO in interlayer space of kaolinite, where the DMSO arranged almost parallel with kaolinite basal surface with all methyl groups being distributed near the interlayer midplane and oxygen atoms orienting toward to the alumina octahedral surface. The radial distribution function between kaolinite and intercalated DMSO verified the strong hydrogen bonds forming between hydroxyl hydrogen

  10. Polycrystalline Mg2Si thin films: A theoretical investigation of their electronic transport properties

    International Nuclear Information System (INIS)

    The electronic structures and thermoelectric properties of a polycrystalline Mg2Si thin film have been investigated by first-principle density-functional theory (DFT) and Boltzmann transport theory calculations within the constant-relaxation time approximation. The polycrystalline thin film has been simulated by assembling three types of slabs each having the orientation (001), (110) or (111) with a thickness of about 18 Å. The effect of applying the relaxation procedure to the thin film induces disorder in the structure that has been ascertained by calculating radial distribution functions. For the calculations of the thermoelectric properties, the energy gap has been fixed at the experimental value of 0.74 eV. The thermoelectric properties, namely the Seebeck coefficient, the electrical conductivity and the power factor, have been determined at three temperatures of 350 K, 600 K and 900 K with respect to both the energy levels and the p-type and n-type doping levels. The best Seebeck coefficient is obtained at 350 K: the Syy component of the tensor amounts to about ±1000 μV K−1, depending on the type of charge carriers. However, the electrical conductivity is much too small which results in low values of the figure of merit ZT. Structure–property relationship correlations based on directional radial distribution functions allow us to tentatively draw some explanations regarding the anisotropy of the electrical conductivity. Finally, the low ZT values obtained for the polycrystalline Mg2Si thin film are paralleled with those recently reported in the literature for bulk chalcogenide glasses. - Graphical abstract: Structure of the polycrystalline thin film of Mg2Si. - Author-Highlights: • Polycrystalline Mg2Si film has been modelled by DFT approach. • Thermoelectric properties have been evaluated by semi-classical Boltzmann theory. • The structure was found to be slightly disordered after relaxation. • The highest value of Seebeck coefficient reaches

  11. Polycrystalline Mg{sub 2}Si thin films: A theoretical investigation of their electronic transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Balout, H. [MADIREL, Aix-Marseille University and CNRS, Avenue Normandie-Niemen, 13397 Marseille (France); Boulet, P., E-mail: pascal.boulet@univ-amu.fr [MADIREL, Aix-Marseille University and CNRS, Avenue Normandie-Niemen, 13397 Marseille (France); Record, M.-C. [IM2NP, Aix-Marseille University and CNRS, Avenue Normandie-Niemen, 13397 Marseille (France)

    2015-05-15

    The electronic structures and thermoelectric properties of a polycrystalline Mg{sub 2}Si thin film have been investigated by first-principle density-functional theory (DFT) and Boltzmann transport theory calculations within the constant-relaxation time approximation. The polycrystalline thin film has been simulated by assembling three types of slabs each having the orientation (001), (110) or (111) with a thickness of about 18 Å. The effect of applying the relaxation procedure to the thin film induces disorder in the structure that has been ascertained by calculating radial distribution functions. For the calculations of the thermoelectric properties, the energy gap has been fixed at the experimental value of 0.74 eV. The thermoelectric properties, namely the Seebeck coefficient, the electrical conductivity and the power factor, have been determined at three temperatures of 350 K, 600 K and 900 K with respect to both the energy levels and the p-type and n-type doping levels. The best Seebeck coefficient is obtained at 350 K: the S{sub yy} component of the tensor amounts to about ±1000 μV K{sup −1}, depending on the type of charge carriers. However, the electrical conductivity is much too small which results in low values of the figure of merit ZT. Structure–property relationship correlations based on directional radial distribution functions allow us to tentatively draw some explanations regarding the anisotropy of the electrical conductivity. Finally, the low ZT values obtained for the polycrystalline Mg{sub 2}Si thin film are paralleled with those recently reported in the literature for bulk chalcogenide glasses. - Graphical abstract: Structure of the polycrystalline thin film of Mg{sub 2}Si. - Author-Highlights: • Polycrystalline Mg{sub 2}Si film has been modelled by DFT approach. • Thermoelectric properties have been evaluated by semi-classical Boltzmann theory. • The structure was found to be slightly disordered after relaxation. • The highest

  12. Experimental and theoretical investigation of semiconductor optical amplifier (SOA)-based all-optical wavelength converters

    Science.gov (United States)

    Dailey, James M.

    evident in the gain. We also discuss our work in optimizing SOA-based all-optical wavelength converters. We compare the use of passive Mach-Zehnder interferometer (AMZI) and Gaussian bandpass filters to optimize the wavelength-converted output eye quality. We conclude that the Gaussian filters provide superior signal quality, but with much lower output power. We also investigate the optimization of an active AMZI through the careful design of the power splitters. We numerically demonstrate significant and robust improvements in eye quality using our design rules, including increases of 21.5 and 4.6 dB in eye extinction and opening.

  13. Evaluation of conditions of comprehensive two-dimensional gas chromatography that yield a near-theoretical maximum in peak capacity gain.

    Science.gov (United States)

    Klee, Matthew S; Cochran, Jack; Merrick, Mark; Blumberg, Leonid M

    2015-02-27

    The peak capacity gain (Gn) of a GC×GC system is the ratio of the system peak capacity to that of an optimized one-dimensional GC analysis lasting the same time and providing the same detection limit. A near-theoretical maximum in Gn has been experimentally demonstrated in GC×GC-TOF based on a 60m×0.25mm primary column. It was found that Gn was close to 9 compared to the theoretical maximum of about 11 for this system. A six-sigma peak capacity of 4500 was obtained during an 80min heating ramp from 50°C to 320°C. Using peak deconvolution, 2242 individual peaks were determined in a Las Vegas runoff water sample. This is the first definitive experimental demonstration known to us of an order-of-magnitude Gn. The key factors enabling this gain were: relatively sharp (about 20ms at half height) reinjection pulses into the secondary column, relatively long (60m) primary column, the same diameters in primary and secondary columns, relatively low retention factor at the end of the secondary analysis (k≅5 instead of 15, optimal for ideal conditions), optimum flow rate in both columns, and helium (rather than hydrogen) used as the carrier gas. The latter, while making the analysis 65% longer than if using H2, was a better match to the reinjection bandwidth and cycle time. PMID:25627969

  14. Origin of electronic properties of PbGa{sub 2}Se{sub 4} crystal: Experimental and theoretical investigations

    Energy Technology Data Exchange (ETDEWEB)

    Babuka, T. [Institute of Physics, Jan Dlugosz University in Czestochowa, Al. Armii Krajowej 13/15, 42-200 Czestochowa (Poland); Kityk, I.V. [Faculty of Electrical Engineering, Czestochowa University Technology, Al. Armii Krajowej 17, 42-201 Czestochowa (Poland); Department of Solid State Physics, Eastern European National University, Voli 13 Ave., Lutsk 43205 (Ukraine); Parasyuk, O.V. [Department of Inorganic and Physical Chemistry, Eastern European National University, Voli 13 Ave., Lutsk 43205 (Ukraine); Myronchuk, G. [Department of Solid State Physics, Eastern European National University, Voli 13 Ave., Lutsk 43205 (Ukraine); Khyzhun, O.Y. [Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky Street, Kyiv 03142 (Ukraine); Fedorchuk, A.O. [Lviv National University of Veterinary Medicine and Biotechnologies, Department of Inorganic and Organic Chemistry, Pekarska St. 50, 79010 Lviv (Ukraine); Makowska-Janusik, M., E-mail: m.makowska@ajd.czest.pl [Institute of Physics, Jan Dlugosz University in Czestochowa, Al. Armii Krajowej 13/15, 42-200 Czestochowa (Poland)

    2015-06-05

    Graphical abstract: In the presented work the structural and electronic properties of the PbGa{sub 2}Se{sub 4} single crystal were investigated experimentally as well as theoretically. The XPS spectra, Urbach’s rule and steepness parameters of PbGa{sub 2}Se{sub 4} single crystal have been investigated for the first time. The quantum chemical calculations were also never performed before for the studied structure. The theoretically obtained data help to explain the properties of material. - Highlights: • Urbach’s rule and steepness parameters for PbGa{sub 2}Se{sub 4} crystals explored for the first time. • Non-reactivity of the PbGa{sub 2}Se{sub 4} surface was established by XPS. • DFT approach shows its efficiency to describe electronic properties of PbGa{sub 2}Se{sub 4}. • Electronic parameters are affected by existence of electron–phonon interaction. - Abstract: The PbGa{sub 2}Se{sub 4} crystal is a promising material for optoelectronic applications. It is caused by coexistence of the large polarized Pb cations and a huge contribution of anharmonic phonon subsystem caused by chalcogenide anions. In the present work the electronic and optical properties of the mentioned material were studied theoretically as well as experimentally by optical and X-ray photoelectron spectroscopy methods. The DFT approach has been used for the quantum chemical electronic properties calculations. Urbach rule and steepness parameters of the PbGa{sub 2}Se{sub 4} crystal have been evaluated for the first time. These parameters and Urbach energies increase with increasing temperature of the samples that is typical for the semiconducting materials. The XPS measurements of the investigated crystal reveal that all the spectral features are originated from core-level states of the constituent elements. Simultaneously these results also confirm non-reactivity of the PbGa{sub 2}Se{sub 4} surface. However, the titled single crystal possesses a number of intrinsic structural

  15. Theoretical investigation of the effect of hydrogen addition on the formation and properties of soliton in direct current argon plasma

    International Nuclear Information System (INIS)

    In this study the effect of hydrogen addition on the formation and properties of soliton in direct-current (DC) argon plasma is theoretically investigated. By coupling fluid equations with Poisons equation for such multi-component plasma, the Mach number and amplitude of the soliton are determined following pseudo potential method. Addition of hydrogen in argon discharge leads to the decrease of electron, Ar+ ion density while a reverse trend was observed for ArH+ and hydrogen like ions. It was found that presence of hydrogen like ions in argon plasma affects the formation of soliton with its amplitude significantly decreases as concentration of hydrogen increases. On the other hand, increase in ion to electron temperature ratios of the lighter ions in the discharge also has a significant influence on the amplitude and formation of soliton. The inverse relation between solitons width and amplitude is found to be consistent for the entire range of study

  16. Theoretical investigation on crystal structure, detonation performance and thermal stability of a high density cage hexanitrohexaazaisowurtzitane derivative

    Indian Academy of Sciences (India)

    Li Xiao-Hong; Cui Hong-Ling; Li Li-Ben; Zhang Xian-Zhou

    2013-07-01

    Density functional theory calculations were performed to study the new polynitro cage compound with the similar framework of HNIW. IR spectrum, heat of formation and thermodynamic properties were predicted. The bond dissociation energies and bond orders for the weakest bonds were analysed to investigate the thermal stability of the title compound. The detonation and pressure were evaluated by using the Kamlet-Jacobs equations based on the theoretical density and condensed HOFs. In addition, the results show that there exists an essentially linear relationship between the WBIs of N-NO2 bonds and the charges -QNO2 on the nitro groups. The crystal structure obtained by molecular mechanics belongs to P21/C space group, with lattice parameters Z = 4, a = 12.3421 Å, b = 24.6849 Å, c = 20.4912 Å, = 1.896 g cm-3. The designed compound has high thermal stability and good detonation properties and is a promising high energy density compound.

  17. A Theoretical investigation on HC Mixtures as Possible Alternatives to R134a in Vapor Compression Refrigeration

    Directory of Open Access Journals (Sweden)

    Feiza Memet

    2014-07-01

    Full Text Available This paper provides a theoretical comparison of the performance of refrigerants in use in a vapor comparison cycle. It is about the phase-out of R134a from actual refrigeration system, comparison being performed for this chemical and two more ecological mixtures: R290/R600a described as (30/70 and (40/60. Were investigated effects of condensation temperatures and evaporation temperatures on performance measures as COP (Coefficient of Performance and VCC (volumetric cooling capacity. COP is a measure of the performance of the refrigeration cycle, while VCC is an indicator of compressor size. Results of this study will reveal that R290/R600a (30/70 is a good option when it is about substitution of R134a, from energy efficiency point of view, in terms of COP. R290/R600a (40/60 has VCC values bellow the ones of R134a, but comparable.

  18. Theoretical investigation on the steady-state natural circulation characteristics of a new type of pressurized water reactor

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This article presents a theoretical investigation on the steady-state natural circulation characteristics of a new type of pressurized water reactor. Through numerically solving the one-dimensional steady-state single-phase conservative equations for the primary circuit and the steady-state two-phase drift-flux conservative equations for the secondary side of the steam generator, the natural circulation characteristics were studied. On the basis of the preliminary calculation analysis, it was found that natural circulation mass flow rate was proportional to the exponential function of the power and that the value of the exponent is related to the operating conditions of the secondary side of the steam generator. The higher the outlet pressure of the secondary side of the steam generator, the higher the primary natural circulation mass flow rate. The larger height difference between the core center and the steam generator center is favorable for the heat removal capacity of the natural circulation.

  19. Theoretical Investigation of Peak-Delay Force Reduction for Caissons Exposed to Non-breaking Short-Crested Waves

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Liu, Z.

    In nature coastal structures are exposed to oblique short-crested waves. The effect of wave incident angle on total wave force on a long caisson are twofold. The one is the force reduction due to the reduction of instantaneous point pressure on the caisson, named point-pressure force reduction. The...... other is the force reduction due to the fact that the peak pressures do not occur simultaneously along the caisson, named peak-delay force reduction. These two reduction effects can also be expected with short-crested waves, as the short-crestedness of waves means the spreading of wave energy over a...... on the peak-delay force reduction of caissons exposed to non-breaking short-crested waves. Battjes (1982) has investigated theoretically the peak-delay force reduction of shortcrested waves with only one frequency component. Such a force reduction factor cannot be applied because in nature waves are...

  20. Theoretical investigation of the decay of an SF6 gas-blast arc using a two-temperature hydrodynamic model

    Science.gov (United States)

    Wang, WeiZong; Yan, Joseph D.; Rong, MingZhe; Murphy, Anthony B.; Spencer, Joseph W.

    2013-02-01

    The behaviour of a decaying SF6 arc, which is representative of the approach to the final current-zero state of switching arcs in a high-voltage circuit breaker, is theoretically investigated by a two-temperature hydrodynamic model, taking into account the possible departure of the plasma state from local thermodynamic equilibrium (LTE). The model couples the plasma flow with electromagnetic fields in a self-consistent manner. The electrons and heavy species are assumed to have different temperatures. The species composition, thermodynamic properties and transport coefficients of the plasma under non-LTE conditions are calculated from fundamental theory. The model is then applied to a two-dimensional axisymmetric SF6 arc burning in a supersonic nozzle under well-controlled conditions; for this configuration, experimental results are available for comparison. The effect of turbulence is considered using the Prandtl mixing-length model. The edge absorption of the radiation emitted by the arc core is taken into account by a modified net emission coefficient approach. The complete set of conservation equations is discretized and solved using the finite volume method. The evolution of electron and heavy-particle temperatures and the total arc resistance, along with other physical quantities, is carefully analysed and compared with those of the LTE case. It is demonstrated that the electron and heavy-particle temperature diverge at all times in the plasma-cold-flow interaction region, in which strong gas flow exists, and further in the transient current-zero period, in which case the collision energy exchange is ineffective. This study quantitatively analyses the energy exchange mechanisms between electrons and heavy particles in the high-pressure supersonic SF6 arcs and provides the foundation for further theoretical investigation of transient SF6 arc behaviour as the current ramps down to zero in gas-blast circuit breakers.

  1. Theoretical investigation of the decay of an SF6 gas-blast arc using a two-temperature hydrodynamic model

    International Nuclear Information System (INIS)

    The behaviour of a decaying SF6 arc, which is representative of the approach to the final current-zero state of switching arcs in a high-voltage circuit breaker, is theoretically investigated by a two-temperature hydrodynamic model, taking into account the possible departure of the plasma state from local thermodynamic equilibrium (LTE). The model couples the plasma flow with electromagnetic fields in a self-consistent manner. The electrons and heavy species are assumed to have different temperatures. The species composition, thermodynamic properties and transport coefficients of the plasma under non-LTE conditions are calculated from fundamental theory. The model is then applied to a two-dimensional axisymmetric SF6 arc burning in a supersonic nozzle under well-controlled conditions; for this configuration, experimental results are available for comparison. The effect of turbulence is considered using the Prandtl mixing-length model. The edge absorption of the radiation emitted by the arc core is taken into account by a modified net emission coefficient approach. The complete set of conservation equations is discretized and solved using the finite volume method. The evolution of electron and heavy-particle temperatures and the total arc resistance, along with other physical quantities, is carefully analysed and compared with those of the LTE case. It is demonstrated that the electron and heavy-particle temperature diverge at all times in the plasma-cold-flow interaction region, in which strong gas flow exists, and further in the transient current-zero period, in which case the collision energy exchange is ineffective. This study quantitatively analyses the energy exchange mechanisms between electrons and heavy particles in the high-pressure supersonic SF6 arcs and provides the foundation for further theoretical investigation of transient SF6 arc behaviour as the current ramps down to zero in gas-blast circuit breakers.

  2. Martensitic transformation in Heusler alloys Mn{sub 2}YIn (Y=Ni, Pd and Pt): Theoretical and experimental investigation

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Hongzhi, E-mail: luo_hongzhi@163.com [School of Material Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Bohua; Xin, Yuepeng; Jia, Pengzhong; Meng, Fanbin [School of Material Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Liu, Enke; Wang, Wenhong; Wu, Guangheng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-12-01

    The martensitic transformation and electronic structure of Heusler alloys Mn{sub 2}YIn (Y=Ni, Pd, Pt) have been investigated by both first-principles calculation and experimental investigation. Theoretical calculation reveals that, the energy difference ΔE between the tetragonal martensitic phase and cubic austenitic phase increases with Y varying from Ni to Pt in Mn{sub 2}YIn. Thus a structural transition from cubic to tetragonal is most likely to happen in Heusler alloy Mn{sub 2}PtIn. A single Heusler phase can be obtained in both Mn{sub 2}PtIn and Mn{sub 2}PdIn. A martensitic transformation temperature of 615 K has been identified in Mn{sub 2}PtIn. And in Mn{sub 2}PdIn, the austenitic phase is stable and no martensitic transformation is observed till 5 K. This indicates there may exist a positive relation between ΔE and martensitic transformation temperature. Calculated results show that Mn{sub 2}YIn are all ferrimagnets in both austenitic and martensitic phases. The magnetic properties are mainly determined by the antiparallel aligned Mn spin moments. These findings can help to develop new FSMAs with novel properties. - Highlights: • Positive relation between ΔE and martensitic transformation temperature has been observed. • Heusler alloy Mn{sub 2}PdIn has been synthesized successfully and investigated. • Martensitic transformation in Heusler alloys can be predicted by first -principles calculations.

  3. Experimental and theoretical investigations on condensation heat transfer at very low pressure to improve power plant efficiency

    International Nuclear Information System (INIS)

    Highlights: • Theoretical model for condensation heat transfer at very low pressure is developed using only one iterative loop. • Experimental results on steam and air steam condensation heat transfer at very low pressure are presented. • The developed model gives the good predictions for local condensation heat transfer at low pressure. • A maximal deterioration of 50% in condensation heat transfer is obtained at low pressure for air fraction of 4%. • A new correlation including effect of a wavy film surface for steam condensation at low pressure is suggested. - Abstract: This paper presents experimental investigation on the influence of very low pressure on local and average condensation heat transfer in a vertical tube. Furthermore, this paper develops an analytical study for film condensation heat transfer coefficient in the presence of non-condensable gas inside a vertical tube. The condensate film thickness is calculated for each location in a tube using mass and heat transfer analogy. The effects of interfacial shear stress and waves on condensate film surface are included in the model. The comparative studies show that the present model well predicts the experimental data of Khun et al. [1]for local condensation of steam air mixture at high pressure. Different correlations defined for condensation heat transfer are evaluated. It is found that the correlations of Cavallini and Zecchin [2] and Shah [3] are the closest to the calculated steam condensation local heat transfer coefficient. The model gives a satisfactory accuracy with the experimental results for condensation heat transfer at very low pressure. The mean deviation between the predictions of the theoretical model with the measurements for pure saturated vapor is 12%. Experimental data show that the increase of air fraction to 4% deteriorates condensation heat transfer at low pressure up to 50%

  4. Theoretical investigation of heat balance in direct injection (DI) diesel engines for neat diesel fuel and gasoline fumigation

    International Nuclear Information System (INIS)

    The main purpose of the presented study is to evaluate energy balance theoretically in direct injection (DI) diesel engines at different conditions. To analyze energy balance, a zero-dimensional multi-zone thermodynamic model has been developed and used. In this thermodynamic model, zero-dimensional intake and exhaust approximations given by Durgun, zero-dimensional compression and expansion model given by Heywood and quasi-dimensional phenomenological combustion model developed by Shahed and then improved Ottikkutti have been used and developed with new approximations and assumptions. By using the developed model, complete diesel engine cycle, engine performance parameters and exhaust emissions can be determined easily. Also, by using this model energy balance can be analyzed for neat diesel fuel and for light fuel fumigation easily. In the presented study, heat balance has been investigated theoretically for three different engines and various numerical applications have been conducted. In the numerical applications two different turbocharged DI diesel engines and a naturally aspirated DI diesel engine have been used. From these numerical applications, it is determined that, what portion of available fuel energy is converted to useful work, what amount of fuel energy is lost by exhaust gases or lost by heat transfer. In addition, heat balance has been analyzed for gasoline fumigation and some numerical results have been given. Brake effective power and brake specific fuel consumption increase and brake effective efficiency decreases for gasoline fumigation for turbocharged diesel engines used in numerical applications. Combustion duration increases with increasing fumigation ratio and thus heat transfer to the walls increases. Because exhaust temperature increases, exhaust losses also increases for fumigation case

  5. Theoretical and experimental investigations on the partial scaling method for the Oxford-type moving-coil linear compressor

    Science.gov (United States)

    Zhang, Lei; Dang, Haizheng; Tan, Jun; Song, Yuyao; Zhou, Binglu; Zou, Ruiqi; Zhao, Yibo; Gao, Zhiqian; Bao, Dingli; Li, Ning

    2015-07-01

    This paper puts forward the partial scaling method of the Oxford-type moving-coil linear compressor for pulse tube cryocoolers and analyzes the related principles. The systematic experimental investigations are further made to verify the analyses. One of the typical compressors developed in the authors' laboratory is chosen to be scaled, and then coupled with the original pulse tube cold finger. At the typical operating temperature of 80 K for the pulse tube cold finger, the scaled compressor's maximum input electric power increases from 236.7 W to 370.0 W, and the cooling power is enhanced from 10.0 W to 15.0 W. The motor efficiency decreases from 78% to 73%, but the average cooling efficiency slightly increases from 11% to 12% of Carnot efficiency due to a better match between scaled compressor and original cold finger. The rationality and feasibility of the partial scaling method have been verified by the theoretical analyses and experimental investigations.

  6. Theoretical and experimental investigations of nanosecond 177.3 nm deep-ultraviolet light by second harmonic generation in KBBF

    Science.gov (United States)

    Yang, F.; Wang, Z.; Zhou, Y.; Li, F.; Xu, J.; Xu, Y.; Cheng, X.; Lu, Y.; Bo, Y.; Peng, Q.; Cui, D.; Zhang, X.; Wang, X.; Zhu, Y.; Xu, Z.

    2009-08-01

    We have presented theoretical and experimental investigations of nanosecond (ns) deep-ultraviolet (DUV) 177.3 nm radiation by means of second harmonic generation (SHG) from a frequency-tripled Nd:YAG laser (355 nm, 49 ns and 10 kHz) in KBe2BO3F2 (KBBF) nonlinear crystal for the first time. A DUV KBBF-SHG numerical model, accounting for linear absorption, pump depletion, beam spatial birefringent walk-off and diffraction, is performed in the Gaussian approximation of spatial and temporal profiles. In the experiment, a maximum average output power of 14.1 mW at 177.3 nm was obtained. The dependence of 177.3 nm output power on the 355 nm pump power was simulated. The calculated results are in good agreement with the measured data. We used the model further to investigate the optical conversion efficiency, pulse width, beam spatial intensity profile and beam quality factor of the generated 177.3 nm light, in particular the effect of beam birefringent walk-off.

  7. Gas Chromatography.

    Science.gov (United States)

    Karasek, Francis W.; And Others

    1984-01-01

    This review covers fundamental developments in gas chromatography during 1982 and 1983. Literature is considered under these headings: columns; liguid phases; solid supports; sorption processes and solvents; open tubular column gas chromatography; instrumentation; high-resolution columns and applications; other techniques; qualitative and…

  8. An in-situ gas chromatography investigation into the suppression of oxygen gas evolution by coated amorphous cobalt-phosphate nanoparticles on oxide electrode

    Science.gov (United States)

    Gim, Jihyeon; Song, Jinju; Kim, Sungjin; Jo, Jeonggeun; Kim, Seokhun; Yoon, Jaegu; Kim, Donghan; Hong, Suk-Gi; Park, Jin-Hwan; Mathew, Vinod; Han, Junhee; Song, Sun-Ju; Kim, Jaekook

    2016-03-01

    The real time detection of quantitative oxygen release from the cathode is performed by in-situ Gas Chromatography as a tool to not only determine the amount of oxygen release from a lithium-ion cell but also to address the safety concerns. This in-situ gas chromatography technique monitoring the gas evolution during electrochemical reaction presents opportunities to clearly understand the effect of surface modification and predict on the cathode stability. The oxide cathode, 0.5Li2MnO3•0.5LiNi0.4Co0.2Mn0.4O2, surface modified by amorphous cobalt-phosphate nanoparticles (a-CoPO4) is prepared by a simple co-precipitation reaction followed by a mild heat treatment. The presence of a 40 nm thick a-CoPO4 coating layer wrapping the oxide powders is confirmed by electron microscopy. The electrochemical measurements reveal that the a-CoPO4 coated overlithiated layered oxide cathode shows better performances than the pristine counterpart. The enhanced performance of the surface modified oxide is attributed to the uniformly coated Co-P-O layer facilitating the suppression of O2 evolution and offering potential lithium host sites. Further, the formation of a stable SEI layer protecting electrolyte decomposition also contributes to enhanced stabilities with lesser voltage decay. The in-situ gas chromatography technique to study electrode safety offers opportunities to investigate the safety issues of a variety of nanostructured electrodes.

  9. An in-situ gas chromatography investigation into the suppression of oxygen gas evolution by coated amorphous cobalt-phosphate nanoparticles on oxide electrode.

    Science.gov (United States)

    Gim, Jihyeon; Song, Jinju; Kim, Sungjin; Jo, Jeonggeun; Kim, Seokhun; Yoon, Jaegu; Kim, Donghan; Hong, Suk-Gi; Park, Jin-Hwan; Mathew, Vinod; Han, Junhee; Song, Sun-Ju; Kim, Jaekook

    2016-01-01

    The real time detection of quantitative oxygen release from the cathode is performed by in-situ Gas Chromatography as a tool to not only determine the amount of oxygen release from a lithium-ion cell but also to address the safety concerns. This in-situ gas chromatography technique monitoring the gas evolution during electrochemical reaction presents opportunities to clearly understand the effect of surface modification and predict on the cathode stability. The oxide cathode, 0.5Li2MnO3∙0.5LiNi0.4Co0.2Mn0.4O2, surface modified by amorphous cobalt-phosphate nanoparticles (a-CoPO4) is prepared by a simple co-precipitation reaction followed by a mild heat treatment. The presence of a 40 nm thick a-CoPO4 coating layer wrapping the oxide powders is confirmed by electron microscopy. The electrochemical measurements reveal that the a-CoPO4 coated overlithiated layered oxide cathode shows better performances than the pristine counterpart. The enhanced performance of the surface modified oxide is attributed to the uniformly coated Co-P-O layer facilitating the suppression of O2 evolution and offering potential lithium host sites. Further, the formation of a stable SEI layer protecting electrolyte decomposition also contributes to enhanced stabilities with lesser voltage decay. The in-situ gas chromatography technique to study electrode safety offers opportunities to investigate the safety issues of a variety of nanostructured electrodes. PMID:27001370

  10. Investigation of pharmaceuticals in processed animal by-products by liquid chromatography coupled to high-resolution mass spectrometry.

    Science.gov (United States)

    Nácher-Mestre, Jaime; Ibáñez, María; Serrano, Roque; Boix, Clara; Bijlsma, Lubertus; Lunestad, Bjørn Tore; Hannisdal, Rita; Alm, Martin; Hernández, Félix; Berntssen, Marc H G

    2016-07-01

    There is an on-going trend for developing more sustainable salmon feed in which traditionally applied marine feed ingredients are replaced with alternatives. Processed animal products (PAPs) have been re-authorized as novel high quality protein ingredients in 2013. These PAPs may harbor undesirable substances such as pharmaceuticals and metabolites which are not previously associated with salmon farming, but might cause a potential risk for feed and food safety. To control these contaminants, an analytical strategy based on a generic extraction followed by ultra-high performance liquid chromatography coupled to high resolution mass spectrometry (UHPLC-HRMS) using quadrupole time-of-flight mass analyzer (QTOF MS) was applied for wide scope screening. Quality control samples, consisting of PAP commodities spiked at 0.02, 0.1 and 0.2 mg/kg with 150 analytes, were injected in every sample batch to verify the overall method performance. The methodology was applied to 19 commercially available PAP samples from six different types of matrices from the EU animal rendering industry. This strategy allows assessing possible emergent risk exposition of the salmon farming industry to 1005 undesirables, including pharmaceuticals, several dyes and relevant metabolites. PMID:27058915

  11. Theoretical investigation of {1 1 0} generalized stacking faults and their relation to dislocation behavior in perovskite oxides

    International Nuclear Information System (INIS)

    Studies of generalized stacking fault energy surfaces, or γ-surfaces, provide a convenient and efficient source of information on possible dislocation dissociation mechanisms and favorable glide systems. We carried out an extensive theoretical investigation of the {1 1 0}γ-surface for three technologically important perovskite oxides SrTiO3, BaTiO3, and PbTiO3. The calculations were performed using both a highly accurate first-principles density functional theory approach and simple empirical interatomic potentials. The main characteristic features common to all {1 1 0}γ-surfaces are the low energy path along the direction and the existence of a single local energy minimum along this path. This minimum corresponds to an antiphase boundary that has been observed experimentally in dissociated dislocation cores in various perovskites. The energy profiles obtained using the empirical potentials agree qualitatively well with the first-principles results but there are significant quantitative discrepancies. This comparison provides a valuable insight into the quality and limitations of empirical potentials for atomistic simulations of dislocations and other extended defects in these materials.

  12. Investigating Brain Network Characteristics Interrupted by Covert White Matter Injury in Patients with Moyamoya Disease: Insights from Graph Theoretical Analysis.

    Science.gov (United States)

    Kazumata, Ken; Tha, Khin Khin; Narita, Hisashi; Shichinohe, Hideo; Ito, Masaki; Uchino, Haruto; Abumiya, Takeo

    2016-05-01

    Chronic ischemia in adult moyamoya disease (MMD) reduces the integrity of normal-appearing white matter (WM). We investigated whether covert WM impairment alters large-scale brain networks and specific neural circuits associated with neurocognitive dysfunction in MMD. Forty-six participants (control, n = 23; MMD, n = 23) were examined using diffusion tensor imaging and streamline tractography. Structural connectivity among 90 cortical and subcortical brain regions was evaluated using the mean fractional anisotropy along the fiber tracts. Graph theoretical analysis was used to measure network parameters and inter-regional connectivity. Global network parameters were reduced in patients with MMD, including cluster coefficient (controls vs. MMD: 3.62 ± 0.24 vs. 3.26 ± 0.36; P < 0.0001), characteristic path length (controls vs. MMD: 1.20 ± 0.02 vs. 1.17 ± 0.01; P < 0.001), and small-world property (controls vs. MMD: 3.07 ± 0.18 vs. 2.83 ± 0.27; P < 0.001). Reduced pairwise connectivity was found in prefrontal neural circuits within the middle/inferior frontal gyrus; supplementary motor area; and insular, inferior temporal, and dorsal cingulate cortices. Covert WM microstructural changes in patients with MMD alter large-scale brain networks, as well as lateral prefrontal neural circuits. Evaluation of structural connectivity may be useful to assess the severity of chronic ischemic injury from a network perspective. PMID:26724619

  13. Theoretical and experimental investigations on corrosion control of 65Cu–35Zn brass in nitric acid by two thiophenol derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahimzadeh, M.; Gholami, M.; Momeni, M. [Metallurgical and Materials Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111 (Iran, Islamic Republic of); Kosari, A., E-mail: Akosari.ali@gmail.com [Metallurgical and Materials Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111 (Iran, Islamic Republic of); Moayed, M.H. [Metallurgical and Materials Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111 (Iran, Islamic Republic of); Davoodi, A. [Materials Engineering Department, Hakim Sabzevari University, Sabzevar 391 (Iran, Islamic Republic of)

    2015-03-30

    Highlights: • Two organic compounds were studied as corrosion inhibitor for brass. • Three equivalent circuits were used to fit the impedance spectra. • Langmuir isotherm was used to determine the inhibitor adsorption type. • An increase in corrosion resistance of brass in the range of 20–35 was detected. • Correlation between quantum chemical and experimental efficiencies was acquired. - Abstract: Inhibitive performance of two thiophenol derivatives namely 4-aminothiophenol (4-ATP) and 4-amino phenol disulfide (4-APD) on corrosion behavior of 65Cu–35Zn brass in 0.5 M HNO{sub 3} was investigated. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) and also quantum chemical study were used. 4-APD showed higher efficiency at low temperatures while for higher temperatures the 4-ATP is more efficient. The inhibitors obey Langmuir isotherm and its adsorption is both chemical and physical type. Quantum chemical study reveals that the benzene ring, S and N atoms can be suitable sites for adsorption onto surface. Finally, an acceptable correlation between the theoretical and experimental inhibitor efficiency was acquired.

  14. Theoretical investigations on SiC2 siligraphene as promising metal-free catalyst for oxygen reduction reaction

    Science.gov (United States)

    Dong, Huilong; Lin, Bin; Gilmore, Keith; Hou, Tingjun; Lee, Shuit-Tong; Li, Youyong

    2015-12-01

    The design and discovery of high-performance metal-free catalytic materials for oxygen reduction reaction (ORR) electrocatalysis is vital for the development of fuel cells. By performing density functional theory (DFT) calculations, we investigate the potential applications of SiC2 siligraphene (g-SiC2) as metal-free ORR catalyst. The g-SiC2 exhibits higher adsorption affinity for the O2 molecule and other ORR intermediates than the traditional Pt (111), and shows good tolerance against CO poisoning. The detailed LH and ER mechanisms in catalyzing ORR by g-SiC2 are simulated and discussed, both in acidic and alkaline environment. We find that, in alkaline environment, the g-SiC2 presents a very low activation barrier (0.16 eV) for the rate determining step (RDS) and shows no overpotential at the equilibrium potential. Our theoretical simulations validate that the siligraphene with alternatively arranged Si and C atoms holds great potential as ORR catalyst in alkaline environment.

  15. Transition Metal Complexes of Calix[4]arene: Theoretical Investigations into Small Guest Binding within the Host Cavity.

    Science.gov (United States)

    Murphy, Paul; Dalgarno, Scott J; Paterson, Martin J

    2016-02-11

    The ability to selectively detect or store small molecules, such as gases, is of enormous commercial potential. Calixarenes have been studied extensively as host molecules; however, recent synthetic advances have seen the formation of new polymetallic calixarene clusters, which have not yet been explored for such purposes. We therefore present a theoretical study, using Density Functional Theory, to thoroughly investigate the binding preferences of calix[4]arene, with a variety of transition metal cations coordinated to the calixarene tetraphenolic pocket, toward a series of important small molecules, H2S, SO2, H2O, O2, H2, N2, N2O, CO2, NH3, and HCN. It was found that the inclusion of a metal atom at the lower-rim of the calixarene caused significant strengthening of binding energy with all of the small molecules in our study as compared to metal-free calixarene. The guests, SO2 and NH3, were found to bind strongest with H2 binding weakest. Our calculations predict that simply introducing metal coordination of any type to calix[4]arene will make the largest difference to the binding energies. Subsequently changing the type, oxidation state, or the spin state of the metal coordinated to the calixarene tetraphenolic pocket was found to have a lesser effect on these. PMID:26783648

  16. Theoretical investigation on the performance of DNA electrophoresis under programmed step electric field strength: Two-step condition.

    Science.gov (United States)

    Ni, Yi; Liu, Chenchen; Chen, Qinmiao; Zhu, Xifang; Dou, Xiaoming

    2015-10-01

    Programmed step electric field strength is a simple-to-use technique that has already been reported to be effective to enhance the efficiency or speed of DNA electrophoresis. However, a global understanding and the details of this technique are still vague. In this paper, we investigated the influence of programmed step electric field strength by theoretical calculation and concentrated on a basic format named as two-step electric field strength. Both subtypes of two-step electric field strength conditions were considered. The important parameters, such as peak spacing, peak width, resolution, and migration time, were calculated in theory to understand the performance of DNA electrophoresis under programmed step electric field strength. The influence of two-step electric field strength on DNA electrophoresis was clearly revealed on a diagram of resolution versus migration time. Both resolution and speed of DNA electrophoresis under two-step electric field strength conditions are simply expressed by the shape of curves in the diagram. The possible shapes of curve were explored by calculation and shown in this paper. The subtype II of two-step electric field strength brings drastic variation on the resolution. Its limitations of enhancement and deterioration of resolution were predicted in theory. PMID:26289302

  17. Theoretical and experimental investigation on the sudden unbalance and rub-impact in rotor system caused by blade off

    Science.gov (United States)

    Wang, Cun; Zhang, Dayi; Ma, Yanhong; Liang, Zhichao; Hong, Jie

    2016-08-01

    Blade loss from a running turbofan rotor will introduce sudden unbalance into the dynamical system, and as a consequence leads to the rub-impact, the asymmetry of rotor and a series of interesting dynamic characteristics. The paper focuses on the theoretical study on the sudden unbalance and rub-impact caused by blade loss, in particular investigates the response of the rotor on a rotor test rig with sudden unbalance and rub-impact device designed respectively. The results reveal that the sudden unbalance will induce impact effect on the rotor, and critical speed frequency is excited in frequency spectrum. Meantime, the impact effect is more obvious for the rotor operating above critical speed. The influence of rub-impact is considered as additional constraint to the rotor, analyzed by the theory of time-varying system for the first time, and the results are evaluated by experimental tests. The study shows that great attention should be paid to the dynamical design for the overhung rotor system, additional constraint and corresponding analysis method in rub-impact need to be intensively studied.

  18. Systematic theoretical investigations for contribution of lattice constraint to novel atomic arrangements in alloy semiconductor thin films

    International Nuclear Information System (INIS)

    The atomic arrangements in zinc blende structured GaNxAs1-x thin films coherently grown on V-grooved substrates are theoretically investigated using empirical interatomic potentials and Monte Carlo simulation. The resultant atomic arrangements in GaNxAs1-x strongly depend on concentration x and substrate lattice parameter asub. Surface segregation of As or N is mainly found in GaNxAs1-x with large lattice mismatch to the substrate. On the other hand, the novel atomic arrangements such as layered segregation or ordered structure are found in GaNxAs1-x at the specific region such as (x, asub) = (0.5, 5.3), (0.3, 5.3), and (0.3, 5.1). This specific region corresponds to that with negative excess energy and with sufficient N and As atoms remaining in thin film layers even after their surface segregation. The formation of the novel atomic arrangements is discussed in terms of bond lengths in the surface layers. These results suggest that various novel atomic arrangements in alloy semiconductor thin films appear depending on x and asub which control degree of lattice constraint.

  19. The impact of Dust Storms on both Solar Radiation and Sky temperature in Tabouk Saudi Arabia, theoretical Investigations

    Science.gov (United States)

    Maghrabi, Abdullrahman

    2016-04-01

    Dust particles affect both solar and terrestrial radiation by scattering and absorption and are therefore considered to be a significant climate-forcing factor. Dust storms are a very frequent phenomenon in Saudi Arabia. Several dust storm events occurred in Tabouk, northern region of Saudi Arabia, during the period between 2014-2015. In this study, simulations using the SMART model were conducted to investigate how the dusty conditions affected the solar irradiances during these events. Additionally, theoretical simulations were carried out using MODTRAN program to examine the changes in the infrared sky temperature during dusty conditions. The Atmospheric Optical Depth (AOD) measurements at (500 nm) were used as an input into both programs. The analysis showed that the dusty conditions significantly decrease the global and direct irradiances and increase the diffuse component compared with clear sky days. Also it was found that the dust storms increase the sky temperature in the atmospheric window (8-14 μm) such that the window emissions resembled those of a blackbody and the atmospheric window was almost closed.

  20. Experimental and Theoretical Investigation of Synergy between Ion Bernstein and Lower Hybrid Waves in PBX-M

    Energy Technology Data Exchange (ETDEWEB)

    A. Cardinali; A. Post-Zwicker; F. Paoletti; S. Bernabei; S. Von Goeler; W. Tighe

    1998-02-01

    The synergistic behavior of lower hybrid and ion Bernstein waves on the Princeton Beta Experiment-Modified tokamak [Phys. Fluids B 2, 1271 (1990)] is experimentally studied using a 2-D hard X-ray camera. The hard X-ray bremsstrahlung emission from suprathermal electrons, generated with lower hybrid current drive, is enhanced during ion Bernstein wave power injection. This enhancement is observed in limited regions of space suggesting the formation of localized current channels. The effects on plasma electrons during combined application of these two types of waves are theoretically investigated using a quasilinear model. The numerical code simultaneously solves the 3-D (R, Z, {Phi}) toroidal wave equation for the electric field (in the WKBJ approximation) and the Fokker-Planck equation for the distribution function in two dimensions (v{sub parallel}, v{sub perpendicular}) with an added quasilinear diffusion coefficient. The radial profile of the non-inductively generated current density, the transmitted power traces and the total power damping curve are calculated. The beneficial effects of a combined utilization of ion Bernstein and lower hybrid waves on the current drive are emphasized. The numerical results are compared with the experimental observations.

  1. The effect of moisture on the structures and properties of lead halide perovskites: a first-principles theoretical investigation.

    Science.gov (United States)

    Zhang, Lei; Ju, Ming-Gang; Liang, WanZhen

    2016-08-17

    With efficiencies exceeding 20% and low production costs, lead halide perovskite solar cells (PSCs) have become potential candidates for future commercial applications. However, there are serious concerns about their long-term stability and environmental friendliness, heavily related to their commercial viability. Herein, we present a theoretical investigation based on the ab initio molecular dynamics (AIMD) simulations and the first-principles density functional theory (DFT) calculations to investigate the effects of sunlight and moisture on the structures and properties of MAPbI3 perovskites. AIMD simulations have been performed to simulate the impact of a few water molecules on the structures of MAPbI3 surfaces terminated in three different ways. The evolution of geometric and electronic structures as well as the absorption spectra has been shown. It is found that the PbI2-terminated surface is the most stable while both the MAI-terminated and PbI2-defective surfaces undergo structural reconstruction, leading to the formation of hydrated compounds in a humid environment. The moisture-induced weakening of photoabsorption is closely related to the formation of hydrated species, and the hydrated crystals MAPbI3·H2O and MA4PbI6·2H2O scarcely absorb the visible light. The electronic excitation in the bare and water-absorbed MAPbI3 nanoparticles tends to weaken Pb-I bonds, especially those around water molecules, and the maximal decrease of photoexcitation-induced bond order can reach up to 20% in the excited state in which the water molecules are involved in the electronic excitation, indicating the accelerated decomposition of perovskites in the presence of sunlight and moisture. This work is valuable for understanding the mechanism of chemical or photochemical instability of MAPbI3 perovskites in the presence of moisture. PMID:27499005

  2. Investigation of mercury-containing proteins by enriched stable isotopic tracer and size-exclusion chromatography hyphenated to inductively coupled plasma-isotope dilution mass spectrometry

    International Nuclear Information System (INIS)

    In order to investigate trace mercury-containing proteins in maternal rat and their offspring, a method of enriched stable isotopic tracer (196Hg and 198Hg) combined with size-exclusion chromatography (SEC) coupled to inductively coupled plasma-isotope dilution mass spectrometry (ICP-IDMS) was developed. Prior to the analysis, 196Hg- and 198Hg-enriched methylmercury was administrated to the pregnant rats. Then the mercury-containing proteins in serum and brain cytosol of the dam and pup rats were separated by size-exclusion columns and the mercury was detected by ICP-MS. The ICP-MS spectrogram of the tracing samples showed significantly elevated 196Hg and 198Hg isotopic signals compared with the natural ones, indicating that the detection sensitivity could be increased by the tracer method. The contents of mercury in chromatographic fractions of the dam and pup rat brain cytosol were quantitatively estimated by post-column reverse ID-ICP-MS. The quantitative speciation differences of mercury in brain cytosol between the dam and pup rats were observed, indicating that such studies could be useful for toxicological estimation. Additionally, the isotopic ratio measurement of 198Hg/202Hg in the tracing samples could be used to identify the artifact mercury species caused in the analytical procedure. The study demonstrates that the tracer method combined with high-performance liquid chromatography (HPLC)-ICP-IDMS could provide reliably qualitative and quantitative information on mercury-containing proteins in organisms

  3. Origin of the Zero-Field Splitting in Mononuclear Octahedral Mn(IV) Complexes: A Combined Experimental and Theoretical Investigation.

    Science.gov (United States)

    Zlatar, Matija; Gruden, Maja; Vassilyeva, Olga Yu; Buvaylo, Elena A; Ponomarev, A N; Zvyagin, S A; Wosnitza, J; Krzystek, J; Garcia-Fernandez, Pablo; Duboc, Carole

    2016-02-01

    The aim of this work was to determine and understand the origin of the electronic properties of Mn(IV) complexes, especially the zero-field splitting (ZFS), through a combined experimental and theoretical investigation on five well-characterized mononuclear octahedral Mn(IV) compounds, with various coordination spheres (N6, N3O3, N2O4 in both trans (trans-N2O4) and cis configurations (cis-N2O4) and O4S2). High-frequency and -field EPR (HFEPR) spectroscopy has been applied to determine the ZFS parameters of two of these compounds, MnL(trans-N2O4) and MnL(O4S2). While at X-band EPR, the axial-component of the ZFS tensor, D, was estimated to be +0.47 cm(-1) for MnL(O4S2), and a D-value of +2.289(5) cm(-1) was determined by HFEPR, which is the largest D-magnitude ever measured for a Mn(IV) complex. A moderate D value of -0.997(6) cm(-1) has been found for MnL(trans-N2O4). Quantum chemical calculations based on two theoretical frameworks (the Density Functional Theory based on a coupled perturbed approach (CP-DFT) and the hybrid Ligand-Field DFT (LF-DFT)) have been performed to define appropriate methodologies to calculate the ZFS tensor for Mn(IV) centers, to predict the orientation of the magnetic axes with respect to the molecular ones, and to define and quantify the physical origin of the different contributions to the ZFS. Except in the case of MnL(trans-N2O4), the experimental and calculated D values are in good agreement, and the sign of D is well predicted, LF-DFT being more satisfactory than CP-DFT. The calculations performed on MnL(cis-N2O4) are consistent with the orientation of the principal anisotropic axis determined by single-crystal EPR, validating the calculated ZFS tensor orientation. The different contributions to D were analyzed demonstrating that the d-d transitions mainly govern D in Mn(IV) ion. However, a deep analysis evidences that many factors enter into the game, explaining why no obvious magnetostructural correlations can be drawn in this

  4. A theoretical investigation of radiative effects and microphysical processes involved in the interaction of aerosol particulates in the atmosphere and validation of the theoretical results with the INDOEX observations

    International Nuclear Information System (INIS)

    A theoretical approach, which is based on certain physical assumptions and quantum physical concepts, has been extended to investigate the radiative effects and the microphysical properties involved in the interaction of aerosol particulates in the atmosphere which may have important climatic effect. The theoretical findings are used to validate some of the observations of Indian Ocean Experiment (INDOEX) during its First Field Phase-98 (FFP-98) and Intense Field Phase-99 (IFP-99). The aerosol optical depth and the radiative forcing of the surface and the top of the atmosphere are computed and the results are found to have a good correspondence with the INDOEX results

  5. MULTISCALE ATOMISTIC SIMULATION OF METAL-OXYGEN SURFACE INTERACTIONS: METHODOLOGICAL DEVELOPMENT, THEORETICAL INVESTIGATION, AND CORRELATION WITH EXPERIMENT - FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    PI: Yang, Judith C., Mechanical Eng. & Materials Science, University of Pittsburgh; Co-PI: McGaughey, Alan, Mechanical Eng., Carnegie Mellon University; Sinnott, Susan and Phillpot, Simon, Materials Science & Eng., University of Florida

    2007-09-30

    input parameters were systematically altered to observe how various physical processes impact morphologies. It was noted that potential gradients, developed to simulate medium-range substrate mediated interactions such as strain, and the probability of an adatom attaching to an island, have the largest effect on island morphologies. Nanorods, and round, square and dendritic shapes have all been observed (see section 2E) which correlate well with experimental observations of the wide range of oxide morphologies produced during in situ oxidation of Cu thin films. The people involved in the development and utilization of TFOx included a post-doc, Dr. Rich McAfee, and a graduate student, Ms. Xuetian Han. Both joined this program in August 2002. Dr. McAfee has been at Brashear Co., in Pittsburgh, PA since June 2004. To allow TFOx to be accessible to the rest of the scientific community, a web-site describing TFOx has been developed: www.tfox.org. No unexpended funds are expected at the completion of the current funding cycle. For in-depth development of the theoretical effort, the Principle Investigator (PI) proposed in the initial grant to collaborate with Dr. Maria Bartelt at Lawrence Livermore National Lab (LLNL). A graduate student, Dr. Guangwen Zhou, was supported within this DOE program for several months, where he was to collaborate with Dr. Bartelt. Unfortunately, Dr. Bartelt became very ill during this time and passed away in 2003. The focus of Dr. Zhou's thesis work (completed in December, 2003) was the wide variety of oxide nanostructures (e.g., nano-rods, domes, and pyramids) that form during oxidation of Cu thin films in situ. His primary contribution while supported on this DOE grant was the demonstration that the elastic strain relief model, as developed by Tersoff and Tromp to explain nanorod formation in Ge/Si system, explains Cu2O nano-rod formation when Cu(100) is oxidized around 600C. Validation of this model requires surface and interface energies

  6. Using Affinity Chromatography to Investigate Novel Protein-Protein Interactions in an Undergraduate Cell and Molecular Biology Lab Course

    Science.gov (United States)

    Belanger, Kenneth D.

    2009-01-01

    Inquiry-driven lab exercises require students to think carefully about a question, carry out an investigation of that question, and critically analyze the results of their investigation. Here, we describe the implementation and assessment of an inquiry-based laboratory exercise in which students obtain and analyze novel data that contribute to our…

  7. Theoretical investigations on two-phase flow instability in parallel channels under axial non-uniform heating

    International Nuclear Information System (INIS)

    Highlights: • We developed a model based on homogeneous flow model to analyze two-phase flow instability in parallel channels. • The influence of axial non-uniform heating on the system stability has been investigated. • Influences of various factors on system instability under cosine heat flux have been studied. • The system under top-peaked heat flux is the most stable system. - Abstract: Two-phase flow instability in parallel channels heated by axial non-uniform heat flux has been theoretically studied in this paper. The system control equations of parallel channels were established based on the homogeneous flow model in two-phase region. Semi-implicit finite-difference scheme and staggered mesh method were used to discretize the equations, and the difference equations were solved by chasing method. Cosine, bottom-peaked and top-peaked heat fluxes were used to study the influence of non-uniform heating on two-phase flow instability of the parallel channels system. The marginal stability boundaries (MSB) of parallel channels and three-dimensional instability spaces (or instability reefs) under different heat flux conditions have been obtained. Compared with axial uniform heating, axial non-uniform heating will affect the system stability. Cosine and bottom-peaked heat fluxes can destabilize the system stability in high inlet subcooling region, while the opposite effect can be found in low inlet subcooling region. However, top-peaked heat flux can enhance the system stability in the whole region. In addition, for cosine heat flux, increasing the system pressure or inlet resistance coefficient can strengthen the system stability, and increasing the heating power will destabilize the system stability. The influence of inlet subcooling number on the system stability is multi-valued under cosine heat flux

  8. Ion chromatography electrospray ionization mass spectrometry method development and investigation of lithium hexafluorophosphate-based organic electrolytes and their thermal decomposition products.

    Science.gov (United States)

    Kraft, Vadim; Grützke, Martin; Weber, Waldemar; Winter, Martin; Nowak, Sascha

    2014-08-01

    A method based on the coupling of ion chromatography (IC) and electrospray ionization mass spectrometry (ESI-MS) for the separation and determination of thermal decomposition products of LiPF6-based organic electrolytes is presented. The utilized electrolytes, LP30 and LP50, are commercially available and consist of 1mol/l LiPF6 dissolved in ethylene carbonate/dimethyl carbonate and ethylene carbonate/ethyl methyl carbonate, respectively. For the separation method development three ion chromatographic columns with different capacity and stationary phase were used and compared. Besides the known hydrolysis products of lithium hexafluorophosphate, several new organophosphates were separated and identified with the developed IC-ESI-MS method during aging investigations of the electrolytes. The chemical structures were elucidated with IC-ESI-MS/MS. PMID:24939088

  9. A Radiative Performance Investigation of the PLIF Experimental and Theoretical Large Diameter Argon Gas Puff Nozzle Profiles on DQ

    Science.gov (United States)

    Chong, Y. K.; Thornhill, J. W.; Davis, J.; Qi, N.; Frese, M. H.; Frese, S. D.

    2004-11-01

    Theoretical and experimental results for the dynamics and the K-shell radiation emission characteristics of large diameter argon double-puff loads driven by the Decade Quad (DQ) pulsed power generator are compared. The theoretical results are generated using a version of the MACH2 two dimensional MHD code that incorporates a tabular collisional radiative equilibrium (TCRE) model. The TCRE model is needed to self-consistently treat the non-LTE radiation and ionization dynamics. The initial gas density profiles used in the calculations are taken from the measured PLIF (planar laser induced fluorescence) data. Based on the results of this experimental/theoretical comparison, it may be possible to create a theoretical tool for designing future nozzles. This can be done by combining the capabilities of our radiation MHD code with one that does a reasonable job of predicting the initial density profile for a given nozzle such as the Navier Stokes nozzle design code at AEDC.

  10. The metaphors in Song of Songs and adolescents : a reception-theoretical investigation and proposed translation / Charles Dussé

    OpenAIRE

    Dusse, Charles

    1995-01-01

    The purpose of this study was to translate the metaphors of Song of Songs for teenagers according to translation-theoretical and reception-theoretical principles. The two prerequisites proposed for a successful translation are the retention of the original image and a knowledge of the reader. Chapter 2 deals with the importance of translation society and three frameworks, namely the nature of translation, situational analysis and principles and criteria for translation. The first framework de...

  11. Probing the early stages of salt nucleation—Experimental and theoretical investigations of sodium/potassium thiocyanate cluster anions

    Science.gov (United States)

    Deng, S. H. M.; Kong, Xiang-Yu; Wang, Xue-Bin

    2015-01-01

    Due to the fast solvent evaporation in electrospray ionization (ESI), the concentration of initially dilute electrolyte solutions rapidly increases to afford the formation of supersaturated droplets and generation of various pristine anhydrous salt clusters in the gas phase. The size, composition, and charge distributions of these clusters, in principle, witness the nucleation evolution in solutions. Herein, we report a microscopic study on the initial stage of nucleation and crystallization of sodium/potassium thiocyanate salt solutions simulated in the ESI process. Singly charged M x (SCN)x + 1 - , doubly charged M y (SCN)y + 2 2 - (M = Na, K), and triply charged K z (SCN)z + 3 3 - anion clusters (x, y, and z stand for the number of alkali atoms in the singly, doubly, and triply charged clusters, respectively) were produced via electrospray of the corresponding salt solutions and were characterized by negative ion photoelectron spectroscopy (NIPES). The vertical detachment energies (VDEs) of these sodium/potassium thiocyanate cluster anions were obtained, and theoretical calculations were carried out for the sodium thiocyanate clusters in assisting spectral identification. The measured VDEs of singly charged anions M x (SCN)x + 1 - (M = Na and K) demonstrate that they are superhalogen anions. The existence of doubly charged anions M y (SCN)y + 2 2 - (y = 2x, x ≥ 4 and 3 for M = Na and K, respectively) and triply charged anions K z (SCN)z + 3 3 - (z = 3x, x ≥ 6) was initially discovered from the photoelectron spectra for those singly charged anions of M x (SCN)x + 1 - with the same mass-to-charge ratio (m/z), and later independently confirmed by the observation of their distinct mass spectral distributions and by taking their NIPE spectra for those pure multiply charged anions with their m/z different from the singly charged species. For large clusters, multiply charged clusters were found to become preferred, but at higher temperatures, those multiply charged

  12. Probing the early stages of salt nucleation—Experimental and theoretical investigations of sodium/potassium thiocyanate cluster anions

    International Nuclear Information System (INIS)

    Due to the fast solvent evaporation in electrospray ionization (ESI), the concentration of initially dilute electrolyte solutions rapidly increases to afford the formation of supersaturated droplets and generation of various pristine anhydrous salt clusters in the gas phase. The size, composition, and charge distributions of these clusters, in principle, witness the nucleation evolution in solutions. Herein, we report a microscopic study on the initial stage of nucleation and crystallization of sodium/potassium thiocyanate salt solutions simulated in the ESI process. Singly charged Mx(SCN)x+1−, doubly charged My(SCN)y+22− (M = Na, K), and triply charged Kz(SCN)z+33− anion clusters (x, y, and z stand for the number of alkali atoms in the singly, doubly, and triply charged clusters, respectively) were produced via electrospray of the corresponding salt solutions and were characterized by negative ion photoelectron spectroscopy (NIPES). The vertical detachment energies (VDEs) of these sodium/potassium thiocyanate cluster anions were obtained, and theoretical calculations were carried out for the sodium thiocyanate clusters in assisting spectral identification. The measured VDEs of singly charged anions Mx(SCN)x+1− (M = Na and K) demonstrate that they are superhalogen anions. The existence of doubly charged anions My(SCN)y+22− (y = 2x, x ≥ 4 and 3 for M = Na and K, respectively) and triply charged anions Kz(SCN)z+33− (z = 3x, x ≥ 6) was initially discovered from the photoelectron spectra for those singly charged anions of Mx(SCN)x+1− with the same mass-to-charge ratio (m/z), and later independently confirmed by the observation of their distinct mass spectral distributions and by taking their NIPE spectra for those pure multiply charged anions with their m/z different from the singly charged species. For large clusters, multiply charged clusters were found to become preferred, but at higher temperatures, those multiply charged clusters were suppressed

  13. Theoretical and experimental investigation of drug-polymer interaction and miscibility and its impact on drug supersaturation in aqueous medium.

    Science.gov (United States)

    Baghel, Shrawan; Cathcart, Helen; O'Reilly, Niall J

    2016-10-01

    Amorphous solid dispersions (ASDs) have the potential to offer higher apparent solubility and bioavailability of BCS class II drugs. Knowledge of the solid state drug-polymer solubility/miscibility and their mutual interaction are fundamental requirements for the effective design and development of such systems. To this end, we have carried out a comprehensive investigation of various ASD systems of dipyridamole and cinnarizine in polyvinylpyrrolidone (PVP) and polyacrylic acid (PAA) at different drug loadings. Theoretical and experimental examinations (by implementing binary and ternary Flory-Huggins (F-H) theory) related to drug-polymer interaction/miscibility including solubility parameter approach, melting point depression method, phase diagram, drug-polymer interaction in the presence of moisture and the effect of drug loading on interaction parameter were performed. The information obtained from this study was used to predict the stability of ASDs at different drug loadings and under different thermal and moisture conditions. Thermal and moisture sorption analysis not only provided the composition-dependent interaction parameter but also predicted the composition dependent miscibility. DPM-PVP, DPM-PAA and CNZ-PAA systems have shown molecular level mixing over the complete range of drug loading. For CNZ-PVP, the presence of a single Tg at lower drug loadings (10, 20 and 35%w/w) indicates the formation of solid solution. However, drug recrystallization was observed for samples with higher drug weight fractions (50 and 65%w/w). Finally, the role of polymer in maintaining drug supersaturation has also been explored. It has been found that drug-polymer combinations capable of hydrogen-bonding in the solution state (DPM-PVP, DPM-PAA and CNZ-PAA) are more effective in preventing drug crystallization compared to the drug-polymer systems without such interaction (CNZ-PVP). The DPM-PAA system outperformed all other ASDs in various stability conditions (dry-state, in

  14. Probing the early stages of salt nucleation—Experimental and theoretical investigations of sodium/potassium thiocyanate cluster anions

    Energy Technology Data Exchange (ETDEWEB)

    Deng, S. H. M.; Kong, Xiang-Yu; Wang, Xue-Bin, E-mail: xuebin.wang@pnnl.gov [Physical Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P. O. Box 999, MS K8-88, Richland, Washington 99352 (United States)

    2015-01-14

    Due to the fast solvent evaporation in electrospray ionization (ESI), the concentration of initially dilute electrolyte solutions rapidly increases to afford the formation of supersaturated droplets and generation of various pristine anhydrous salt clusters in the gas phase. The size, composition, and charge distributions of these clusters, in principle, witness the nucleation evolution in solutions. Herein, we report a microscopic study on the initial stage of nucleation and crystallization of sodium/potassium thiocyanate salt solutions simulated in the ESI process. Singly charged M{sub x}(SCN){sub x+1}{sup −}, doubly charged M{sub y}(SCN){sub y+2}{sup 2−} (M = Na, K), and triply charged K{sub z}(SCN){sub z+3}{sup 3−} anion clusters (x, y, and z stand for the number of alkali atoms in the singly, doubly, and triply charged clusters, respectively) were produced via electrospray of the corresponding salt solutions and were characterized by negative ion photoelectron spectroscopy (NIPES). The vertical detachment energies (VDEs) of these sodium/potassium thiocyanate cluster anions were obtained, and theoretical calculations were carried out for the sodium thiocyanate clusters in assisting spectral identification. The measured VDEs of singly charged anions M{sub x}(SCN){sub x+1}{sup −} (M = Na and K) demonstrate that they are superhalogen anions. The existence of doubly charged anions M{sub y}(SCN){sub y+2}{sup 2−} (y = 2x, x ≥ 4 and 3 for M = Na and K, respectively) and triply charged anions K{sub z}(SCN){sub z+3}{sup 3−} (z = 3x, x ≥ 6) was initially discovered from the photoelectron spectra for those singly charged anions of M{sub x}(SCN){sub x+1}{sup −} with the same mass-to-charge ratio (m/z), and later independently confirmed by the observation of their distinct mass spectral distributions and by taking their NIPE spectra for those pure multiply charged anions with their m/z different from the singly charged species. For large clusters, multiply

  15. Amino acid-type interactions of L-3,4-dihydroxyphenylalanine with transition metal ions: An experimental and theoretical investigation

    Science.gov (United States)

    Mandal, Shilpi; Das, Gunajyoti; Askari, Hassan

    2015-11-01

    This paper reports the synthesis of the Ni+2, Cu+2 and Zn+2 complexes of L-3,4-dihydroxyphenylalanine (L-dopa) using a solvent-free solid-state grinding procedure. The synthesized complexes are characterized by elemental, molar conductance, EDAX-SEM, TG/DTA, infrared, electronic absorption, fluorescence and XRD analyses; confirming a 1:2 metal-ligand stoichiometry of the complexes and involvement of the carboxyl and amino groups in complex formation. Phase-diagram and the kinetic parameters of the interactions between L-dopa and the metal ions are also explored. Molecular structures of the metal complexes are modeled within the framework of density functional theory in a vacuum and implicit aqueous environment using the most stable L-dopa conformers determined at the MP2/6-311++G(d,p) level. The gas and aqueous phase metal-binding affinities; theoretical IR and UV-vis spectral aspects; partial atomic charges; Wiberg bond indices; HOMO-LUMO energy gaps and dipole moments of the L-dopa conformers as well as their complexes are calculated and analyzed at B3LYP/6-311++G(d,p) level. The singlet state of the Ni(L-dopa)2 complex is found to be more favorable from thermodynamic perspectives as compared to the triplet state. Use of BHandHLYP and dispersion-corrected B3LYP (at DFT-D2 level) methods in conjugation with the 6-311++G(d,p) basis set affords us to accurately predict the binding affinity order of the three Lewis acids investigated, assess the influence of metal-aromatic π interactions on the thermodynamic stability of metalated L-dopa, and explore the effectiveness of the aforesaid methodologies in predicting a certain set of spectral and electronic properties of bioactive molecules. UV-vis titration and docking studies reveal that the metal complexes of L-dopa are able to bind to the surface of DNA.

  16. Theoretical investigation of the design and performance of a dual energy (kV and MV) radiotherapy imager

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Langechuan; Antonuk, Larry E., E-mail: antonuk@umich.edu; El-Mohri, Youcef; Zhao, Qihua; Jiang, Hao [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2015-04-15

    , incorporate a BGO converter with a 0.508 mm pitch and a 2 cm thickness, and operate at full resolution for kV imaging and 2 × 2 binning mode for MV imaging. Such a dual energy imager design should provide soft tissue visualization at low, clinically practical doses under MV conditions, while helping to preserve the high spatial resolution and high contrast offered by kV imaging. Conclusions: The authors’ theoretical investigation suggests that a dual energy imager capable of largely preserving the desirable characteristics of both kV and MV imaging is feasible. Such an imager, when coupled to a dual energy radiation source, could facilitate simplification of current treatment room imaging systems (as well as their associated quality assurance), and facilitate more precise integration of kV and MV imaging information by virtue of reduced geometric uncertainties.

  17. Theoretical investigation of site-specific characteristics of CO adsorption complexes in the Li+-FER zeolite

    Czech Academy of Sciences Publication Activity Database

    Nachtigall, Petr; Bulánek, R.

    2006-01-01

    Roč. 307, č. 1 (2006), s. 118-127. ISSN 0926-860X R&D Projects: GA MŠk(CZ) LC512 Institutional research plan: CEZ:AV0Z40550506 Keywords : adsorption * spectroscopy * DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.630, year: 2006

  18. The Potential of Isotope Ratio Mass Spectrometry (IRMS) and Gas Chromatography-IRMS Analysis of Triacetone Triperoxide in Forensic Explosives Investigations.

    Science.gov (United States)

    Bezemer, Karlijn D B; Koeberg, Mattijs; van der Heijden, Antoine E D M; van Driel, Chris A; Blaga, Cornelia; Bruinsma, Jildert; van Asten, Arian C

    2016-09-01

    Studying links between triacetone triperoxide (TATP) samples from crime scenes and suspects can assist in criminal investigations. Isotope ratio mass spectrometry (IRMS) and gas chromatography (GC)-IRMS were used to measure the isotopic compositions of TATP and its precursors acetone and hydrogen peroxide. In total, 31 TATP samples were synthesized with different raw material combinations and reaction conditions. For carbon, a good differentiation and a linear relationship were observed for acetone-TATP combinations. The extent of negative (δ(13) C) fractionation depended on the reaction yield. Limited enrichment was observed for the hydrogen isotope (δ(2) H) values of the TATP samples probably due to a constant exchange of hydrogen atoms in aqueous solution. For oxygen (δ(18) O), the small isotopic range and excess of water in hydrogen peroxide resulted in poor differentiation. GC-IRMS and IRMS data were comparable except for one TATP sample prepared with high acid concentration demonstrating the potential of compound-specific isotope analysis. Carbon IRMS has practical use in forensic TATP investigations. PMID:27356279

  19. Multiscale atomistic simulation of metal-oxygen surface interactions: methodological development, theoretical investigation, and correlation with experiment

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Judith C. [University of Pittsburgh

    2015-01-09

    The purpose of this grant is to develop the multi-scale theoretical methods to describe the nanoscale oxidation of metal thin films, as the PI (Yang) extensive previous experience in the experimental elucidation of the initial stages of Cu oxidation by primarily in situ transmission electron microscopy methods. Through the use and development of computational tools at varying length (and time) scales, from atomistic quantum mechanical calculation, force field mesoscale simulations, to large scale Kinetic Monte Carlo (KMC) modeling, the fundamental underpinings of the initial stages of Cu oxidation have been elucidated. The development of computational modeling tools allows for accelerated materials discovery. The theoretical tools developed from this program impact a wide range of technologies that depend on surface reactions, including corrosion, catalysis, and nanomaterials fabrication.

  20. Adsorption of Propane and Propylene on CuBTC Metal-Organic Framework: Combined Theoretical and Experimental Investigation

    Czech Academy of Sciences Publication Activity Database

    Rubeš, M.; Wiersum, A. D.; Llewellyn, P. L.; Grajciar, L.; Bludský, Ota; Nachtigall, P.

    2013-01-01

    Roč. 117, č. 21 (2013), s. 11159-11167. ISSN 1932-7447 R&D Projects: GA MŠk(CZ) ME10032; GA ČR GBP106/12/G015 Institutional support: RVO:61388963 Keywords : coordinatively unsaturated sites * ab-initio calculations * basis-set convergence * molecular simulation * CuBTC Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.835, year: 2013

  1. Combined Theoretical and Experimental Investigation of CO Adsorption on Coordinatively Unsaturated Sites in CuBTC MOF

    Czech Academy of Sciences Publication Activity Database

    Rubeš, M.; Grajciar, L.; Bludský, Ota; Wiersum, A. D.; Llewellyn, P. L.; Nachtigall, P.

    2012-01-01

    Roč. 13, č. 2 (2012), s. 488-495. ISSN 1439-4235 R&D Projects: GA MŠk LC512 Grant ostatní: GA MŠk(CZ) 7E09111; 7th framework programme(XE) 228862 Institutional research plan: CEZ:AV0Z40550506 Keywords : ab initio calculations * adsorption * density functional calculations * metal - organic frameworks * microcalorimetry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.349, year: 2012

  2. Theoretical investigation of the Friedlander reaction catalysed by CuBTC: Concerted effect of the adjacent Cu2+ sites

    Czech Academy of Sciences Publication Activity Database

    Položij, M.; Pérez-Mayoral, E.; Čejka, Jiří; Hermann, J.; Nachtigall, P.

    2013-01-01

    Roč. 204, APR 2013 (2013), s. 101-107. ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Grant ostatní: European Commission(XE) FP7/2007-2013, contract 228862 Institutional support: RVO:61388955 Keywords : Friedlander reaction * Metal Organic Framework ( MOF ) * CuBTC Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.309, year: 2013

  3. Investigating the Relationship Between Advertising and Pricing in a Channel with Private Label Offering: A Theoretic Model

    OpenAIRE

    Karray Salma; Martín-Herrán Guiomar

    2008-01-01

    We study the relationship between pricing and advertising decisions in a distribution channel where national brands are competing with a private label. We solve a three-stage game-theoretic model where the national brands compete on advertising and prices, and the retailer is investing in umbrella advertising for the store and is selling a private label. The obtained equilibrium strategies highlight the importance of determining the complementary or competitive roles of advertising to better ...

  4. Ion Chromatography.

    Science.gov (United States)

    Mulik, James D.; Sawicki, Eugene

    1979-01-01

    Accurate for the analysis of ions in solution, this form of analysis enables the analyst to directly assay many compounds that previously were difficult or impossible to analyze. The method is a combination of the methodologies of ion exchange, liquid chromatography, and conductimetric determination with eluant suppression. (Author/RE)

  5. Preliminary investigation by liquid chromatography tandem mass spectrometry of perfluorinated compounds presence in bass reared and fished in Italy

    Directory of Open Access Journals (Sweden)

    Federica Farabegoli

    2013-12-01

    Full Text Available The term perfluorinated compounds (PFCs defines synthetic fully-fluorinated compounds; since the 50s they have been largely employed in a wide range of industrial and consumer applications, due to their chemical and physical properties. Only recently, research on their potential adverse effects on both the environment and human health has been conducted, highlighting carcinogenic activity, toxic effects on reproduction, liver and kidney. Human exposure to PFCs is mainly through diet, and in particular fishery products are one of the most contaminated food. Perfluorooctane sulfonate (PFOS and perfluorooctanoic acid (PFOA are the two most important and investigated compounds of this group. The aim of this work was to carry out a preliminary monitoring on the presence of these two molecules in 50 bass muscle samples, of which 30 reared and 20 fished, collected from different Italian areas of the Mediterranean Sea. The method used was based on extraction with organic solvent followed by two purification steps: one with salts and one with dispersive solid phase. The extract was finally analysed by means of an ultra performance liquid chromatographytandem mass spectrometric system. Data showed a relevant contamination of this species and evidenced a significant difference of concentrations between fished (PFOS 112.4- >2000 ng/L and PFOA 3.3-487.0 ng/L and reared basses (PFOS 11.1-104.5 ng/L and PFOA <3-51.4 ng/L. Even if these levels of contamination are sensibly lower than those observed in several studies, fished basses could represent a more relevant source of PFCs exposure in human diet.

  6. An experimental and theoretical investigation of free Oxazole in conjunction with the DFT analysis of Oxazole⋯(H2O)n complexes.

    Science.gov (United States)

    Yurdakul, Şenay; Badoğlu, Serdar; Özkurt, Lütfiye

    2016-06-01

    The mid-IR spectrum of Oxazole (Oxa) is recorded. This spectrum is interpreted with the help of B3LYP/6-311++G(d,p) calculations and potential energy distribution (PED) analysis. The experimental spectrum is concordant with the theoretical data. Geometrical parameters and the atomic charges are also theoretically obtained and presented. Solvent effects on the geometrical parameters, vibrational frequencies, and electronic properties of Oxa are analyzed theoretically in chloroform, ethanol, and water. Besides, hydrogen bonded Oxa⋯(H2O)n (n=1, 2,…, 10) complexes are investigated within the PCM solvation model. It is found that the interaction energies in Oxa⋯(H2O)n complexes are influenced by the number of water molecules, and by the arrangement of water molecules. PMID:26978786

  7. Experimental and theoretical investigations on isotope selective excitation in multi-step laser photoionisation schemes: a spectral simulation approach

    International Nuclear Information System (INIS)

    Multi-step laser excitation of atoms in the vapor phase results in preferential excitation of one isotope in comparison to the other isotopes. When the laser power is just sufficient to saturate the transition, the degree of selectivity depends only on the spectroscopic parameters such as the isotope shift of the constituent isotopes, hyperfine structure (in case of odd isotopes), linewidth of the excitation laser, Doppler width of the atoms and the photoionisation scheme used. Isotope selectivity is an important parameter useful for estimating the efficacy of a photoionisation scheme to selectively excite (and ionise) to the desired degree. From the basic principles of laser spectroscopy, few generalised conclusions can be made about the effect of spectroscopic parameters on the isotopic selectivity. However, in several cases the isotopic selectivity is a result of complex interplay of these parameters. In order to use the multi-step photoionisation schemes for selective excitation of the isotopes, a simple qualitative understanding is not sufficient. Therefore, it is necessary to quantitatively estimate the effect of these parameters on the selective excitation of the isotope of interest. We have developed a new theoretical model 'spectral simulation method' for the calculation of isotopic selectivity. The model is based on the classical line shapes of the atomic transitions for the estimation of the wing overlap of unwanted isotopes at the resonance frequency of the isotope of interest. The model has been applied to several atomic systems and is found to be in good agreement with other theoretical and experimental results. In the present report we describe various details of this new theoretical model and some of the studies carried out for the calculation of isotopic selectivity using this model. (author)

  8. Theoretical investigation on the molecular inclusion process of prilocaine into p-sulfonic acid calix[6]arene

    Science.gov (United States)

    de Sousa, Sara M. R.; Fernandes, Sergio A.; De Almeida, Wagner B.; Guimarães, Luciana; Abranches, Paula A. S.; Varejão, Eduardo V. V.; Nascimento, Clebio S., Jr.

    2016-02-01

    The present letter reports, for the first time, results from a theoretical analysis of the inclusion process involving the prilocaine into the p-sulfonic acid calix[6]arene. Structure and stabilization energies were calculated, in both gas and aqueous phases, using a sequential methodology based on semiempirical and Density Functional Theory (DFT) calculations. From the results, a qualitative structure property relationship could be established with some main structural features being relevant for inclusion complex stabilization: (i) the hydrogen bonds established between guest and host molecules, (ii) the dispersion effect and (iii) the inclusion mode of guest molecule into the host cavity.

  9. Effect of Gap Size on Coating Extrusion of Pb-GF Composite Wire by Theoretical Calculation and Experimental Investigation

    Institute of Scientific and Technical Information of China (English)

    Wenbin FANG; Hongfei SUN; Erde WANG; Yaohong GENG

    2005-01-01

    A new method using lead coated glass fiber to produce continuous wire for battery grid of electric vehicles (EVs)and hybrid electric vehicles (HEVs) was introduced. Under equal flow, both the maximum and minimum theoretical value of gap size were studied and estimation equation was established. The experimental results show that the gap size is a key parameter for the continuous coating extrusion process. Its maximum value (Hmax) is 0.24 mm and the minimum one (Hmin) is 0.12 mm. At a gap size of 0.18 mm, the maximum of metal extrusion per unit of time and optimal coating speed could be obtained.

  10. Theoretical investigations on the determination of cavitation-free primary flow after compacting the reactor FRG-1

    International Nuclear Information System (INIS)

    Basing on an extensive analysis of the influence of compacting the FRG-1 reactor core upon the change in flow, heat exchange, as well as cavitation behavior of the primary circuit the underlying principles of the determination procedure for a cavitations-free primary flow have been developed theoretically. It was found that the problem has to be treated in a complex manner, i.e. considering the coupled flow, temperature, as well as cavitation fields, and that for a successful solution of the problem it is absolutely necessary to simultaneously induce an optimized fixation of the main primary coolant pump. (orig.)

  11. Theoretical investigation of structural properties of CuCl, CuBr and CuI compounds under hydrostatic pressure

    Energy Technology Data Exchange (ETDEWEB)

    Louhibi-Fasla, S.; Djabri, H. Rekab; Achour, H. [Laboratoire de Micro et de Nanophysique LaMiN - ENP d' ORAN, BP 1523, El M' Naouer, 31000 (Algeria); Kefif, K. [Laboratoire de Physique des Couches Minces et Matériaux pour l' Electronique, Université d' ORAN, Es-senia (Algeria)

    2013-12-16

    We have applied a recent version of the full potential linear muffin-tin orbitals method (FPLMTO) to study the structural properties of copper halides CuX (X=Cl, Br, I) under high pressure using the generalized gradient approximation (GGA) for the exchange and correlation potential by Perdew et al. Results are given for lattice parameters, bulk modulus and its first derivatives in the wurtzite(B4), zinc-blende (B3), CsCl (B2), rock-salt (B1), and PbO (B10) structures. The results of these calculations are compared with the available theoretical and experimental data.

  12. Of Chains and Rings: Synthetic Strategies and Theoretical Investigations for Tuning the Structure of Silver Coordination Compounds and Their Applications

    Directory of Open Access Journals (Sweden)

    Tünde Vig Slenters

    2010-05-01

    Full Text Available Varying the polyethyleneglycol spacer between two (iso-nicotinic groups of the ligand systems, a large structural variety of silver coordination compounds was obtained, starting with zero-dimensional ring systems, via one-dimensional chains, helices and double-helices to two-dimensional polycatenanes. Theoretical calculations help to understand their formation and allow predictions in some cases. These structures can be tuned by careful design of the ligand, the use of solvent and the counter ions, influencing also other important properties such as light stability and solubility. The latter is important in the context of biomedical applications, using silver compounds as antimicrobial agents.

  13. Robust Method Using Online Steric Exclusion Chromatography-Ultraviolet-Inductively Coupled Plasma Mass Spectrometry To Investigate Nanoparticle Fate and Behavior in Environmental Samples.

    Science.gov (United States)

    Al-Sid-Cheikh, Maya; Pédrot, Mathieu; Bouhnik-Le Coz, Martine; Dia, Aline; Davranche, Mélanie; Neaime, Chrystelle; Grasset, Fabien

    2015-10-20

    The foundation of nanoscience is that the properties of materials change as a function of their physical dimensions, and nanotechnology exploits this premise by applying selected property modifications for a specific benefit. However, to investigate the fate and effect of the engineered nanoparticles on toxic metal (TM) mobility, the analytical limitations in a natural environment remain a critical problem to overcome. Recently, a new generation of size exclusion chromatography (SEC) columns developed with spherical silica is available for pore sizes between 5 and 400 nm, allowing the analysis of nanoparticles. In this study, these columns were applied to the analysis of metal-based nanoparticles in environmental and artificial samples. The new method allows quantitative measurements of the interactions among nanoparticles, organic matter, and metals. Moreover, because of the new nanoscale SEC, our method allows the study of these interactions for different size ranges of nanoparticles and weights of organic molecules with a precision of 1.2 × 10(-2) kDa. The method was successfully applied to the study of nanomagnetite spiked in complex matrixes, such as sewage sludge, groundwater, tap water, and different artificial samples containing Leonardite humic acid and different toxic metals (i.e., As, Pb, Th). Finally, our results showed that different types of interactions, such as adsorption, stabilization, and/or destabilization of nanomagnetite could be observed using this new method. PMID:26383030

  14. Application of gas chromatography/mass spectroscopy to the investigation of metabolic pathways of trace elements using stable isotopes as tracers

    International Nuclear Information System (INIS)

    Zinc and copper metabolism became easier to study after science provided two research ways: Isotope tracer technique and atomic absorption spectroscopy. Using stable isotopes is advantageous in humans because exposure to radioactivity is avoided and therefore the method can be used safely in infants and pregnant women. We have investigated the bioavailability of zinc in a group of premature infants and one term infant weighing 1 850 to 5 630 g and the copper absorption in a man and an adolescent with M. Wilson (a copper storage disease) and discuss the accurate isotope analysis of human feces in relation to mineral bioavailability studies of premature infants. It is shown that for the determination of bioavailability of zinc and copper, the method of chelate-gas chromatography/mass spectrometry (GC/MS) is valuable for routine application to clinical experiments; the human fecal samples resulting from diet suitably enriched with isotopes 68Zn, 70Zn or 65Cu can be routinely analysed with a precision of about 1% for these stable isotopes. The total zinc in feces was determined by atomic absorption spectroscopy and the 70Zn/64Zn ratio by chelate-GC/MS (EI). We have found different absorption values between 3% to 70% for zinc in a group of different infants including twins, triplets and preterms. The copper uptake was determined to be 79.7% and 49.9%. (orig./RB)

  15. Further investigation of a peptide extraction method with mesoporous silica using high-performance liquid chromatography coupled with tandem mass spectrometry.

    Science.gov (United States)

    Du, Yan; Wu, Dapeng; Guan, Yafeng

    2016-06-01

    Mobil Composition of Matter No. 41 (MCM-41) was the most frequently used mesoporous silica material to extract peptides from complex biological samples. However, there were confusing extraction conditions and large extraction efficiency variance among related reports, which resulted from unclear understanding about the interaction between the material and peptides. In this study, the extraction mechanism was investigated with one set of tryptic peptides by using high-performance liquid chromatography coupled with triple quadrupole mass spectrometry. Generally, hydrophobic interaction and electrostatic attraction were two major driving forces for extraction of peptides, while electrostatic repulsion greatly weakened the interaction between the material and peptides with isoelectric points below the pH. With most peptides positively charged and MCM-41 slightly negatively charged, most efficient extraction was obtained at pH 3, and it was proved that electrostatic and hydrophobic interaction acted in synergy for extraction of all the peptides. A mixed solution of acetonitrile with buffers of high pH or ion strength was demonstrated to be favorable for elution, which performed much better than the commonly used eluate (mixture of acetonitrile with 0.1% trifluoroacetic acid). Finally, under optimum conditions, it was found that extraction efficiency of MCM-41 for protein digest and human serum was greatly improved. PMID:27059091

  16. Application of gas chromatography with atomic emission detection to the geochemical investigation of polycyclic aromatic sulfur heterocycles in Egyptian crude oils

    Energy Technology Data Exchange (ETDEWEB)

    Hegazi, A.H.; Andersson, J.T. [Institute of Inorganic and Analytical Chemistry, University of Munster, Wilhelm-Klemm Strasse 8, 48149 Munster (Germany); El-Gayar, M.Sh. [Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Alexandria 21321 (Egypt)

    2004-01-15

    Twelve crude oils from a number of producing wells in the Gulf of Suez and Western Desert, Egypt were characterized by a variety of saturate biomarker compositions. The biomarker distribution clearly grouped the Gulf of Suez oils into two source-related types but revealed significant differences among the Western Desert oils. The oils were fractionated into saturates, mono- and polyaromatics; and the distribution of polycyclic aromatic sulfur heterocycles (PASH) in the polyaromatics fraction was investigated by gas chromatography (GC) with atomic emission detector (AED) in the carbon- and sulfur-selective modes. This makes possible the evaluation of the distribution patterns of PASHs even in cases where their relative abundance is low. The thiophenic distribution fingerprints were utilized for oil/oil correlations. Significant differences in the relative abundance of benzothiophenes and dibenzothiophenes were obvious between the Gulf of Suez and Western Desert oils. Moreover, the PASH pattern distinguished between oils derived from carbonate and siliciclastic source rocks. Maturity parameters based upon methyldibenzothiophene isomers were found consistent with other maturity-dependent saturate biomarkers.

  17. Investigation of uranium and thorium activities and isotopic ratios in environmental water samples in Tokushima, Japan, using extraction chromatography and samarium coprecipitation

    International Nuclear Information System (INIS)

    Management and pollution-control of environmental water are not only a national and international priority, but also important issues in a local government. At local areas there are the characteristic climatic variations, the various landforms structures, the restricted places bordered by nuclear fuel facilities and nuclear power plants, the different industrial development and so on. They are responsible for the safety management of the natural surface and underground waters at each local government. So far, the presence and behavior of radioelements, including uranium and thorium isotopes, in environmental waters from different sources have been widely studied throughout the world, while those studies in Japan also have been carried out throughout the national distribution uptake by major research institutes. However, at a local area there is a great lack of more detailed data of uranium and thorium activities and isotopic ratios in environmental samples, and its fact is no exception in Tokushima, Japan, where is located in Shikoku Island. Therefore, we plan to investigate uranium and thorium activities and isotopic ratios in environmental samples and their behavior in Tokushima. We have applied an extraction chromatography using Eichrom UTEVATM resin column and samarium fluoride or hydroxide coprecipitation methods to separate uranium and thorium fractions in environmental waters and then to measure their activities by α-spectrometry. A chemical yield in this procedure was estimated by monitoring signal intensities of uranium and thorium concentrations on ICP-MS. A blank sample for back-ground measurement in the α-spectrometry was also prepared in the same procedure. We have examined the present separation Procedure qualitatively using a test solution in water taken as an environmental water sample, in which soluble fractions leaching from a monazite are contained as uranium, thorium and the others. Fig 1(a) and 1(b) show a spectra of uranium and thorium

  18. Theoretical investigation on the inclusion of TCDD with β-cyclodextrin by performing QM calculations and MD simulations

    International Nuclear Information System (INIS)

    Highlights: → We study the inclusion mechanism of TCDD with β-CD by theoretical methods. → Clearly, the formation of inclusion complex is an energetically driven process. → The inclusion complex can be detected by IR and Raman techniques. → The results imply that β-CD may be used as a host molecule to enrich TCDD molecules. - Abstract: The rapid enrichment and detection of trace polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are currently challenging issues in the field of environmental science. In this paper, by performing quantum chemistry (QM) calculations and molecular dynamics (MD) simulations, we studied the inclusion complexation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a representative PCDD molecule, with β-cyclodextrin (β-CD), one of the widely used compounds in supramolecular chemistry. The calculated results reveal that the stable inclusion complex can be formed in both the gas phase and solvent, which proposes that β-CD may serve as a potential substrate enriching TCDD. The calculated vibrational spectra indicate that the infrared (IR) and Raman spectroscopy may be suitable for the detection of β-CD-modified TCDD. The present theoretical results may be informative to environmental scientists who are devoting themselves to developing effective methods for detection and treatment of POPs.

  19. Optimal electron irradiation as a tool for functionalization of MoS2: Theoretical and experimental investigation

    International Nuclear Information System (INIS)

    We demonstrate the utility of electron irradiation as a tool to enhance device functionality of graphene-analogous MoS2. With the help of first-principles based calculations, vacancy-induced changes of various electronic properties are shown to be a combined result of crystal-field modification and spin-orbital coupling. A comparative theoretical study of various possible vacancy configurations both in bulk and monolayer MoS2 and related changes in their respective band-structures help us to explain plausible irradiation induced effects. Experimentally, various structural forms of MoS2 in bulk, few layered flakes, and nanocrystals are observed to exhibit important modification of their magnetic, transport, and vibrational properties, following low doses of electron irradiation. While irradiated single crystals and nanocrystals show an enhanced magnetization, transport properties of few-layered devices show a significant increase in their conductivity, which can be very useful for fabrication of electronic devices. Our theoretical calculations reveal that this increase in n-type conductivity and magnetization can be correlated with the presence of sulfur and molybdenum vacancies

  20. Theoretical investigation on the inclusion of TCDD with {beta}-cyclodextrin by performing QM calculations and MD simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Wenxiao [Key Lab of Colloid and Interface Chemistry, Ministry of Education, Institute of Theoretical Chemistry, Shandong University, Jinan 250100 (China); Zhang, Dongju, E-mail: zhangdj@sdu.edu.cn [Key Lab of Colloid and Interface Chemistry, Ministry of Education, Institute of Theoretical Chemistry, Shandong University, Jinan 250100 (China); Zhan, Jinhua [Key Lab of Colloid and Interface Chemistry, Ministry of Education, Institute of Theoretical Chemistry, Shandong University, Jinan 250100 (China)

    2011-09-15

    Highlights: {yields} We study the inclusion mechanism of TCDD with {beta}-CD by theoretical methods. {yields} Clearly, the formation of inclusion complex is an energetically driven process. {yields} The inclusion complex can be detected by IR and Raman techniques. {yields} The results imply that {beta}-CD may be used as a host molecule to enrich TCDD molecules. - Abstract: The rapid enrichment and detection of trace polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are currently challenging issues in the field of environmental science. In this paper, by performing quantum chemistry (QM) calculations and molecular dynamics (MD) simulations, we studied the inclusion complexation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a representative PCDD molecule, with {beta}-cyclodextrin ({beta}-CD), one of the widely used compounds in supramolecular chemistry. The calculated results reveal that the stable inclusion complex can be formed in both the gas phase and solvent, which proposes that {beta}-CD may serve as a potential substrate enriching TCDD. The calculated vibrational spectra indicate that the infrared (IR) and Raman spectroscopy may be suitable for the detection of {beta}-CD-modified TCDD. The present theoretical results may be informative to environmental scientists who are devoting themselves to developing effective methods for detection and treatment of POPs.

  1. Probing microhydration effect on the electronic structure of the GFP chromophore anion: Photoelectron spectroscopy and theoretical investigations

    Energy Technology Data Exchange (ETDEWEB)

    Bhaskaran-Nair, Kiran; Shelton, William A. [Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Valiev, Marat; Kowalski, Karol, E-mail: karol.kowalski@pnnl.gov [William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, K8-91, P.O. Box 999, Richland, Washington 99352 (United States); Deng, S. H. M.; Wang, Xue-Bin, E-mail: xuebin.wang@pnnl.gov [Physical Sciences Division, Pacific Northwest National Laboratory, K8-88, P.O. Box 999, Richland, Washington 99352 (United States)

    2015-12-14

    The photophysics of the Green Fluorescent Protein (GFP) chromophore is critically dependent on its local structure and on its environment. Despite extensive experimental and computational studies, there remain many open questions regarding the key fundamental variables that govern this process. One outstanding problem is the role of autoionization as a possible relaxation pathway of the excited state under different environmental conditions. This issue is considered in our work through combined experimental and theoretical studies of microsolvated clusters of the deprotonated p-hydroxybenzylidene-2,3-dimethylimidazolinone anion (HBDI{sup −}), an analog of the GFP chromophore. Through selective generation of microsolvated structures of predetermined size and subsequent analysis of experimental photoelectron spectra by high level ab initio methods, we are able to precisely identify the structure of the system, establish the accuracy of theoretical data, and provide reliable description of auto-ionization process as a function of hydrogen-bonding environment. Our study clearly illustrates the first few water molecules progressively stabilize the excited state of the chromophore anion against the autodetached neutral state, which should be an important trait for crystallographic water molecules in GFPs that has not been fully explored to date.

  2. Probing microhydration effect on the electronic structure of the GFP chromophore anion: Photoelectron spectroscopy and theoretical investigations

    Science.gov (United States)

    Bhaskaran-Nair, Kiran; Valiev, Marat; Deng, S. H. M.; Shelton, William A.; Kowalski, Karol; Wang, Xue-Bin

    2015-12-01

    The photophysics of the Green Fluorescent Protein (GFP) chromophore is critically dependent on its local structure and on its environment. Despite extensive experimental and computational studies, there remain many open questions regarding the key fundamental variables that govern this process. One outstanding problem is the role of autoionization as a possible relaxation pathway of the excited state under different environmental conditions. This issue is considered in our work through combined experimental and theoretical studies of microsolvated clusters of the deprotonated p-hydroxybenzylidene-2,3-dimethylimidazolinone anion (HBDI-), an analog of the GFP chromophore. Through selective generation of microsolvated structures of predetermined size and subsequent analysis of experimental photoelectron spectra by high level ab initio methods, we are able to precisely identify the structure of the system, establish the accuracy of theoretical data, and provide reliable description of auto-ionization process as a function of hydrogen-bonding environment. Our study clearly illustrates the first few water molecules progressively stabilize the excited state of the chromophore anion against the autodetached neutral state, which should be an important trait for crystallographic water molecules in GFPs that has not been fully explored to date.

  3. Probing microhydration effect on the electronic structure of the GFP chromophore anion. Photoelectron spectroscopy and theoretical investigations

    Energy Technology Data Exchange (ETDEWEB)

    Bhaskaran-Nair, Kiran [Louisiana State Univ., Baton Rouge, LA (United States); Valiev, Marat [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Atmospheric Science and Global Change Div. (ASGC); Deng, Shihu [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shelton, William A. [Louisiana State Univ., Baton Rouge, LA (United States); Kowalski, Karol [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Atmospheric Science and Global Change Div. (ASGC); Wang, Xue B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-12-14

    The photophysics of Green Fluorescent Protein (GFP) chromophore is critically dependent on its local structure and on its environment. Despite extensive experimental and computational studies, there remain many open questions regarding the key fundamental variables that govern this process. One outstanding problem is the role of autoionization as a possible relaxation pathway of the excited state under different environmental conditions. This issue is considered in our work through combined experimental and theoretical studies of microsolvated clusters of the deprotonated p-hydroxybenzylidene-2,3-dimethylimidazolinone anion (HBDI⁻), an analog of GFP chromophore. Through selective generation of microsolvated structures of predetermined size and subsequent analysis of experimental photoelectron spectra by high level ab-initio methods we are able to precisely identify the structure of the system, establish the accuracy of theoretical data, and provide reliable description of auto-ionization process as a function of hydrogen-bonding environment. Our study clearly illustrates the first few water molecules progressively stabilize the excited state of the chromophore anion against the autodetached neutral state, which should be an important trait for crystallographic water molecules in GFPs that has not been fully explored to date.

  4. Games and Diabetes: A Review Investigating Theoretical Frameworks, Evaluation Methodologies, and Opportunities for Design Grounded in Learning Theories.

    Science.gov (United States)

    Lazem, Shaimaa; Webster, Mary; Holmes, Wayne; Wolf, Motje

    2016-03-01

    Here we review 18 articles that describe the design and evaluation of 1 or more games for diabetes from technical, methodological, and theoretical perspectives. We undertook searches covering the period 2010 to May 2015 in the ACM, IEEE, Journal of Medical Internet Research, Studies in Health Technology and Informatics, and Google Scholar online databases using the keywords "children," "computer games," "diabetes," "games," "type 1," and "type 2" in various Boolean combinations. The review sets out to establish, for future research, an understanding of the current landscape of digital games designed for children with diabetes. We briefly explored the use and impact of well-established learning theories in such games. The most frequently mentioned theoretical frameworks were social cognitive theory and social constructivism. Due to the limitations of the reported evaluation methodologies, little evidence was found to support the strong promise of games for diabetes. Furthermore, we could not establish a relation between design features and the game outcomes. We argue that an in-depth discussion about the extent to which learning theories could and should be manifested in the design decisions is required. PMID:26337753

  5. Theoretical and experimental investigation of magnetoelectric effect for bending-tension coupled modes in magnetostrictive-piezoelectric layered composites

    Science.gov (United States)

    Hasanyan, D.; Gao, J.; Wang, Y.; Viswan, R.; Li, M.; Shen, Y.; Li, J.; Viehland, D.

    2012-07-01

    In this paper, we discuss a theoretical model with experimental verification for the resonance enhancement of magnetoelectric (ME) interactions at frequencies corresponding to bending-tension oscillations. A dynamic theory of arbitrary laminated magneto-elasto-electric bars was constructed. The model included bending and longitudinal vibration effects for predicting ME coefficients in laminate bar composite structures consisting of magnetostrictive, piezoelectric, and pure elastic layers. The thickness dependence of stress, strain, and magnetic and electric fields within a sample are taken into account, as such the bending deformations should be considered in an applied magnetic or electric field. The frequency dependence of the ME voltage coefficients has obtained by solving electrostatic, magnetostatic, and elastodynamic equations. We consider boundary conditions corresponding to free vibrations at both ends. As a demonstration, our theory for multilayer ME composites was then applied to ferromagnetic-ferroelectric bilayers, specifically Metglas-PZT ones. A theoretical model is presented for static (low-frequency) ME effects in such bilayers. We also performed experiments for these Metglas-PZT bilayers and analyzed the influence of Metglas geometry (length and thickness) and Metglas/PZT volume fraction on the ME coefficient. The frequency dependence of the ME coefficient is also presented for different geometries (length, thickness) of Metglas. The theory shows good agreement with experimental data, even near the resonance frequency.

  6. Experimental and theoretical investigations of the stress-induced twinning/detwinning in the martensite phase of a FSMA system

    International Nuclear Information System (INIS)

    Highlights: ► We present a model for stress-induced twinning/detwinning in the martensite phase of a FSMA. ► We then quantitatively compared the theoretical fit to the actual experimental data. ► It was found to be applicable even in the mixed region just above the austenite finish temperature. -- Abstract: Ferromagnetic shape memory alloys (FSMAs) have the largest magnetic field induced strain below austenite–martensite transformation temperatures. The martensitic phase has structural twins that reorient under applied magnetic field or stress. To understand this behavior, stress–strain measurements were made at different temperatures on a typical FSMA material, NiFeAl. A thermodynamic constitutive model based on Clausius–Duhem inequality, was used to theoretically determine the stress resulting from an applied stress at each temperature. In this paper, we studied twinning/detwinning in the martensite under applied stress only. Thus, the free energy of the system has a sole contribution from the mechanical energy, which, in turn, depends on the elastic moduli pertaining to the elastic and twinning strains. This volume fraction of martensite phase, both for the field-preferred and stress-preferred directions, and magneto-mechanical driving force, was determined and correlated with the experimental results. Finally, the model was found to fit well with data in the premartensitic region too

  7. Ion chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Tarter, J.G.

    1987-01-01

    Similar in many ways to other liquid chromatographic techniques, ion chromatography (IC) is an invaluable method that is used all too rarely in chemical analysis. Its application is particularly promising in the analysis of inorganic anions, an area where more information is needed. Ion Chromatogrphy identifies the merits of this technique. Serving as a review and reference for experienced ion chromatographers and as a teaching aid for individuals new to the field, it provides the information necessary for determining the potential usefulness of IC for a given situation. Among the areas treated, this volume focuses on eluant-suppressed IC, especially for anion and cation analysis, single-column IC, plus ancillary techniques and applications, electrochemical, spectroscopic, and other detecting methods, ion chromatography exclusion (ICE), including its limits and applications.

  8. Theoretical investigations on magnetic entropy change in amorphous and crystalline systems: Applications to RAg (R=Tb, Dy, Ho) and GdCuAl

    International Nuclear Information System (INIS)

    We report theoretical investigations on the magnetic entropy changes in amorphous systems through two different assumptions. In the first assumption, the HPZ-anisotropic model is considered to deal with the random direction of magnetic moments, where the amorphous RAg (R=Tb, Dy and Ho) were used as prototypes systems. In the second assumption, the amorphisation is parameterized through the exchange interaction distribution and GdCuAl, in amorphous and crystalline structures, were considered as prototypes systems. Comparisons between the magnetic entropy changes under amorphisation and under the usual magnetic field variation were performed. The model reveals the dependence of refrigerant capacity on the amorphisation parameter, and an optimum amorphisation parameter was calculated. - Highlights: • Theoretical investigation on RAg (R=Tb, Dy and Ho) and GdCuAl amorphous alloys. • Magnetic entropy changes in GdCuAl in both amorphous and crystalline structures. • The refrigerant capacity was compared in both amorphous and crystalline phases

  9. Theoretical investigations on magnetic entropy change in amorphous and crystalline systems: Applications to RAg (R=Tb, Dy, Ho) and GdCuAl

    Energy Technology Data Exchange (ETDEWEB)

    Ranke, P.J. von, E-mail: von.ranke@uol.com.br [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Nóbrega, E.P. [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Caldas, A. [Sociedade Unificada de Ensino Superior e Cultura, SUESC, 20211-351 Rio de Janeiro, RJ (Brazil); Alho, B.P. [Instituto de Aplicação Fernando Rodrigues da Silveira, Universidade do Estado do Rio de Janeiro, Rua Santa Alexandrina, 288, 20260-232 RJ (Brazil); Ribeiro, P.O.; Alvarenga, T.S.T.; Lopes, P.H.O.; Sousa, V.S.R. de [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Carvalho, A. Magnus G. [Laboratório Nacional de Luz Síncrotron, CNPEM, 13083-970 Campinas, SP (Brazil); Oliveira, N.A. de [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil)

    2014-11-15

    We report theoretical investigations on the magnetic entropy changes in amorphous systems through two different assumptions. In the first assumption, the HPZ-anisotropic model is considered to deal with the random direction of magnetic moments, where the amorphous RAg (R=Tb, Dy and Ho) were used as prototypes systems. In the second assumption, the amorphisation is parameterized through the exchange interaction distribution and GdCuAl, in amorphous and crystalline structures, were considered as prototypes systems. Comparisons between the magnetic entropy changes under amorphisation and under the usual magnetic field variation were performed. The model reveals the dependence of refrigerant capacity on the amorphisation parameter, and an optimum amorphisation parameter was calculated. - Highlights: • Theoretical investigation on RAg (R=Tb, Dy and Ho) and GdCuAl amorphous alloys. • Magnetic entropy changes in GdCuAl in both amorphous and crystalline structures. • The refrigerant capacity was compared in both amorphous and crystalline phases.

  10. Investigation on the Dynamic Performance of the Tripod-Ball Sliding Joint with Clearance in a CRANK-SLIDER Mechanism. Part 1. Theoretical and Experimental Results

    Science.gov (United States)

    JIA, X.; JIN, D.; JI, L.; ZHANG, J.

    2002-05-01

    Clearance is inevitable in the kinematic joints of mechanisms. In this paper, the dynamic behavior of a crank-slider mechanism with clearance in its tripod-ball sliding joint is investigated theoretically and experimentally. The mathematical model of this new-type of joint is established, and the new concepts of basal system and active system are put forward. Based on the mode-change criterion established in this paper, the consistent equations of motion in full-scale are derived by using Kane method. The experimental rig was set up to measure the effects of the clearance on the dynamic response. The dynamic responses including additional motion, input torque and acceleration have been obtained, and the effects of the clearance size and driving speed have also been investigated by both analytical and experimental means. Corresponding experimental studies verify the theoretical results satisfactorily.

  11. INVESTIGATION OF DEPENDENCE OF ANTIOXIDANT ACTIVITY OF ESSENTIAL OILS FROM CLOVE BUDS, LEMONGRASS, CARDAMOM AND BERRIES OF JUNIPER ON OIL CONCENTRATION BY CAPILLARY GAS-LIQUID CHROMATOGRAPHY

    Directory of Open Access Journals (Sweden)

    Алексей Леонидович Самусенко

    2014-10-01

    Full Text Available In recent time the biological activity of essential oils from spicy-aromatic herbs, including the antioxidant one, have been evaluated in numerous studies. Earlier we have demonstrated high antioxidant activity of the oils contained monoterpenes, such as γ-terpinene and α-terpinolene, sesquiterpenes (zingeberene and β-caryofillene and citral. However the concentration value of oils in the “aldehyde – essential oil” system was excessively high and the investigation of various concentrations was not carried out by us. The goal of this work was studying of the influence of oil concentration on antioxidant activity value for selected essential oils and correlation of the obtained data with a change of main antioxidants in the composition of the essential oils under study. The antioxidant properties of the essential oils from clove buds (Caryophyllus aromaticus L., lemongrass (Cymbopogon citratus, cardamom (Elettaria cardamomum and berries of juniper (Juniperus pinchoti on oil concentration has been studied by capillary gas-liquid chromatography using an aldehyde/carboxylic acid assay. Trans-2-hexenal was selected to serve as the test substance. The dependence of oil antioxidant activity on its concentration was found to be closely connected with a rate of content change of main antioxidants in the composition of the essential oils under study at prolonged exposure to light. It was noted that the presence of strong antioxidants in oil composition even in relatively low quantities can significantly affect the value of their AOA and its dependence on the concentration of oil in the solution. It was observed the strong dependence «antioxidant activity – oil concentration» for clove and lemongrass oils. Low concentrations of all investigated oils, except for oil from clove buds, didn’t have an inhibiting action on the oxidation of test-aldehyde.

  12. Theoretical and experimental investigations of HF oscillation excitation in an ion collective accelerator based on the Doppler effect

    International Nuclear Information System (INIS)

    The studies on the two-beam method for acceleration of the HF field ions, excited by an electron beam on the normal and Doppler effects, are presented. The dynamics of exciting the eigen waves of the periodic slowing down structure by relativistic ion beam on the Doppler anomalous effect is theoretically studied. The instability stabilization mechanisms are considered and the analytical expressions for the electron beam energy transfer efficiency to the excited wave are presented. The description of the experimental acceleration bench, created for verifying the possibility of accelerating the protons up to 3 A by the energy up to 8 MeV is set forth. The double resonance on the anomalous and normal Doppler effects by an electron beam interaction with a spiral slowing down structure is experimentally studied. Increase in the efficiency of the accelerating HF field excitation is identified

  13. Systematic theoretical investigation of the zero-field splitting in Gd(III) complexes: Wave function and density functional approaches

    Science.gov (United States)

    Khan, Shehryar; Kubica-Misztal, Aleksandra; Kruk, Danuta; Kowalewski, Jozef; Odelius, Michael

    2015-01-01

    The zero-field splitting (ZFS) of the electronic ground state in paramagnetic ions is a sensitive probe of the variations in the electronic and molecular structure with an impact on fields ranging from fundamental physical chemistry to medical applications. A detailed analysis of the ZFS in a series of symmetric Gd(III) complexes is presented in order to establish the applicability and accuracy of computational methods using multiconfigurational complete-active-space self-consistent field wave functions and of density functional theory calculations. The various computational schemes are then applied to larger complexes Gd(III)DOTA(H2O)-, Gd(III)DTPA(H2O)2-, and Gd(III)(H2O)83+ in order to analyze how the theoretical results compare to experimentally derived parameters. In contrast to approximations based on density functional theory, the multiconfigurational methods produce results for the ZFS of Gd(III) complexes on the correct order of magnitude.

  14. Theoretical and experimental investigation of the mode-spacing of fiber Bragg grating Fabry-Perot cavity

    Institute of Scientific and Technical Information of China (English)

    Wenhua Ren; Peilin Tao; Zhongwei Tan; Yan Liu; Shuisheng Jian

    2009-01-01

    The mode-spacing of the fiber Bragg grating Fabry-Perot(FBG F-P)cavity is calculated by using the effective cavity length which contains the effective length of the FBG.The expression of the effective length,defined by using the phase-time delay,is obtained and simplified as a function of the peak reflectivity at the Bragg wavelength,the band edges,and the first zero-reflectivity wavelength.The effective length is discussed from the energy penetration depth point of view.Three FBG F-P cavities are fabricated in order to validate the effective length approach.The experimental data fits well with the theoretical predictions.The limitation of this method is also pointed out and the improved approach is proposed.

  15. Investigation of 90Sr(II) sorption onto graphene oxides studied by macroscopic experiments and theoretical calculations

    International Nuclear Information System (INIS)

    The graphene oxides were applied as adsorbents to remove 90Sr(II) ions from aqueous solutions under different experimental conditions. The results showed that 90Sr(II) sorption was mainly dominated by ion exchange and outer-sphere surface complexation. The maximum sorption capacity (Csmas) was calculated to be 3.84 x 10-4 mol/g at pH 5.8 and 20 deg C, which was much higher than that of 90Sr(II) on other today's materials. The thermodynamic parameters suggested that the sorption was an endothermic and spontaneous process. The theoretical calculation results indicated that COH and COC groups contributed to the coordination of Sr(II) ions. (author)

  16. Systematic theoretical investigation of the zero-field splitting in Gd(III) complexes: Wave function and density functional approaches

    International Nuclear Information System (INIS)

    The zero-field splitting (ZFS) of the electronic ground state in paramagnetic ions is a sensitive probe of the variations in the electronic and molecular structure with an impact on fields ranging from fundamental physical chemistry to medical applications. A detailed analysis of the ZFS in a series of symmetric Gd(III) complexes is presented in order to establish the applicability and accuracy of computational methods using multiconfigurational complete-active-space self-consistent field wave functions and of density functional theory calculations. The various computational schemes are then applied to larger complexes Gd(III)DOTA(H2O)−, Gd(III)DTPA(H2O)2−, and Gd(III)(H2O)83+ in order to analyze how the theoretical results compare to experimentally derived parameters. In contrast to approximations based on density functional theory, the multiconfigurational methods produce results for the ZFS of Gd(III) complexes on the correct order of magnitude

  17. Theoretical investigation of the local and global components of the neutron-noise fields in a boiling water reactor

    International Nuclear Information System (INIS)

    In view of recent experimental work the neutron noise in a BWR is believed to be separable into a local and a global component. It is the existence of the local component which makes possible the measurement of steam-velocity by correlating the signals of axially placed incore neutron detectors. The authors use a one-dimensional (axial) model of the core and solve the two group diffusion equations satisfied by the neutron-noise. The solution is shown to be composed of two terms which can be identified as the theoretical counterparts of the components found in experiments. The properties of the two terms are discussed in the special case of an axially propagating disturbance of the moderator density (steam content). (Auth.)

  18. Theoretical investigation of force field and vibrational spectrum of BF3 molecule by MO LCAO SCF method

    International Nuclear Information System (INIS)

    Non-empirical calculations of equilibrium internuclear distances, force constants, frequencies of normal vibrations, isotope shifts and vibration intensities in IR spectrum of BF3 molecule have been made by MO LCAO SCF method using three bases of grouped gauss functions: DZ (9s5p/4s2p), TZ(10s6p/5s3p) and TZ+P (10s6p1d/5s3p1d). All the three bases lead to the results which are in good agreement with the experimental data. For instance, theoretical values of vibration frequencies differ from the experimental ones by average 3.2; 2.4 and 7.0% in the bases DZ, TZ and TZ+P respectively

  19. INVESTIGATION INTO THE REGIOCHEMISTRY OF SOME PYRAZOLES DERIVED FROM 1, 3-DIPOLAR CYCLOADDITION OF ACRYLONITRILE WITH SOME NITRILIMINES: THEORETICAL AND EXPERIMENTAL STUDIES

    OpenAIRE

    FARID MOEINPOUR; MEHDI BAKAVOLI; ABOLGHASEM DAVOODNIA; ALI MORSALI

    2011-01-01

    1,3-dipolar cycloaddition between acrylonitrile and two N-(4-substituted)phenyl-C-(4-chlorophenyl)nitrilimines which were generated in situ afforded the new pyrazoles. The regiochemistry and reactivity of these reactions has been investigated on the basis of density functional theory (DFT) -based reactivity indexes and activation energy calculations. The theoretical 13C NMR chemical shifts of the cycloadducts which were obtained by GIAO method were comparable with the observed values.

  20. A theoretical and (e,2e) experimental investigation into the complete valence electronic structure of (1.1.1) propellane

    International Nuclear Information System (INIS)

    The first comprehensive electronic structural study of the complete valence shell of [1.1.1] propellane is reported. Binding energy spectra were measured in the energy regime 3.5-46.5 eV over a range of different target electron momentum so that individual orbital momentum profiles could also be determined. These binding energy spectra were collected using an energy dispersive multichannel electron momentum spectrometer at a total energy of 1000 eV, with a coincidence energy resolution of 1.38 eV and a momentum resolution of about 0.1 a.u. The experimental orbital electron momentum profiles are compared with those calculated in the plane wave impulse approximation (PWIA) using both a triple zeta plus polarisation level SCF wavefunction and a further 13 basis sets as calculated using Density Functional Theory (DFT). A critical comparison between the experimental an theoretical momentum distributions (MDs) allows to determine the optimum wavefunction for [1.1.1]propellane. In general, the level of agreement between the experimental and theoretical MDs for the optimum wavefunction for all of the respective valence orbitals was very good. The determination of this wavefunction then allowed to derive the chemically interesting molecular properties of [1.1.1]propellane. These include infrared spectra, bond lengths, bond orders, electron densities and many others. A summary of these results and a comparison of them with the previous results of other workers is presented with the level of agreement typically being good. In particular, the existence of the C1-C3 bridging bond with a bond order of 0.70 was confirmed. 59 refs., 4 tabs., 11 figs

  1. Theoretical investigation of new Heusler alloys Ru{sub 2}VGa{sub 1−x}Al{sub x}

    Energy Technology Data Exchange (ETDEWEB)

    Abbassa, Hamza [Département de Physique, Université de Abdelhamid Ibn Badis de Mostaganem, Mostaganem (Algeria); Laboratoire de Physique des Couches Minces et Matériaux pour l’Electronique (LPC2ME), Université d’Oran, Es-Senia, Oran (Algeria); Hadjri-Mebarki, Soria [Laboratoire de Physique des Couches Minces et Matériaux pour l’Electronique (LPC2ME), Université d’Oran, Es-Senia, Oran (Algeria); Amrani, Bouhalouane, E-mail: amrani.bouhalouane@univ-oran.dz [Laboratoire de Physique des Couches Minces et Matériaux pour l’Electronique (LPC2ME), Université d’Oran, Es-Senia, Oran (Algeria); Belaroussi, Tayeb [Département de Physique, Université de Abdelhamid Ibn Badis de Mostaganem, Mostaganem (Algeria); Laboratoire de Physique de Plasmas des Matériaux Conducteur et leur Applications (LPPMCA), Université d’USTOMB, Oran (Algeria); Driss Khodja, Kouider [Laboratoire de Physique des Couches Minces et Matériaux pour l’Electronique (LPC2ME), Université d’Oran, Es-Senia, Oran (Algeria); Aubert, Pascal [Institut d’Electronique Fondamentale, Université Paris-Sud – CNRS, Orsay 91405 (France)

    2015-07-15

    Highlights: • Electronic and thermodynamic properties of new Heusler alloys Ru{sub 2}VGa{sub 1−x}Al{sub x} (x = 0, 0.25, 0.50, 0.75, and 1.00) are studied. • Elastic parameters and stability of Ru{sub 2}VGa{sub 1−x}Al{sub x} alloys. • A linear behavior of the lattice parameter, bulk modulus, elastic constants and Debye temperature on x has been observed. - Abstract: Results of first-principles full-potential linearized augmented plane wave calculations of elastic and related electronic and thermodynamic properties of the quaternary Heusler alloys Ru{sub 2}VAl{sub x}Ga{sub 1−x} (x = 0, 0.25, 0.5, 0.75, 1) are presented. These materials were found to have the L2{sub 1} structure for all concentrations. The agreement between the theoretical and experimental lattice parameters for both Ru{sub 2}VAl and Ru{sub 2}VGa at various temperatures was found to be satisfactory. Our results provide predictions for the remaining mixed more» Heusler alloys Ru{sub 2}VAl{sub x}Ga{sub 1−x} (0 < x < 1) for which no direct experimental or theoretical data are presently available. In their equilibrium L2{sub 1} structure, all concentrations are non-magnetic metals. A linear variation of the lattice parameter, bulk modulus, elastic constants and Debye temperature has been observed with x.

  2. Theoretical and experimental investigation of the f(D) max- (S/S 0) max anomaly in LiF:Mg,Ti

    International Nuclear Information System (INIS)

    Previous investigations in the framework of the Unified Interaction Model (UNIM) have demonstrated the difficulty in theoretically predicting both f(D)max and [S(Ds)/ S0]max with the same set of UNIM parameters. This anomaly is re-investigated and an alternative explanation, based on experimental measurements combined with UNIM analysis, is given. This explanation is based on the assumption that NLC, the total number of available luminescent centres is changed by the sensitisation dose or anneal or both. Allowing NLC to increase as the sensitisation dose is increased, a good fit to both f(D) and S(Ds)/S0 is obtained. (authors)

  3. Learning curves, taking instructions, and patient safety: using a theoretical domains framework in an interview study to investigate prescribing errors among trainee doctors

    Directory of Open Access Journals (Sweden)

    Duncan Eilidh M

    2012-09-01

    Full Text Available Abstract Background Prescribing errors are a major source of morbidity and mortality and represent a significant patient safety concern. Evidence suggests that trainee doctors are responsible for most prescribing errors. Understanding the factors that influence prescribing behavior may lead to effective interventions to reduce errors. Existing investigations of prescribing errors have been based on Human Error Theory but not on other relevant behavioral theories. The aim of this study was to apply a broad theory-based approach using the Theoretical Domains Framework (TDF to investigate prescribing in the hospital context among a sample of trainee doctors. Method Semistructured interviews, based on 12 theoretical domains, were conducted with 22 trainee doctors to explore views, opinions, and experiences of prescribing and prescribing errors. Content analysis was conducted, followed by applying relevance criteria and a novel stage of critical appraisal, to identify which theoretical domains could be targeted in interventions to improve prescribing. Results Seven theoretical domains met the criteria of relevance: “social professional role and identity,” “environmental context and resources,” “social influences,” “knowledge,” “skills,” “memory, attention, and decision making,” and “behavioral regulation.” From critical appraisal of the interview data, “beliefs about consequences” and “beliefs about capabilities” were also identified as potentially important domains. Interrelationships between domains were evident. Additionally, the data supported theoretical elaboration of the domain behavioral regulation. Conclusions In this investigation of hospital-based prescribing, participants’ attributions about causes of errors were used to identify domains that could be targeted in interventions to improve prescribing. In a departure from previous TDF practice, critical appraisal was used to identify additional domains

  4. Theoretical Investigation on Excitation, Ionization and Capture in H(1s, 2s) + H(1s, 2s) Collisions

    Institute of Scientific and Technical Information of China (English)

    CHEN Lan-Fang; ZHU Xiao-Long; MA Xin-Wen; LIU Ling; HE Bin; WANG Jian-Guo; Ratko JANEV

    2008-01-01

    @@ Cross sections of electron-loss in H(1s)+ H(1s) collisions and total collisional destruction of H(2s) in H(1s) + H(2s) collisions are calculated by four-body classical-trajectory Monte Carlo (CTMC) method and compared with previous theoretical and experimental data over the energy range of 4-100 keV. For the former a good agreement is obtained within different four-body CTMC calculations, and for the incident energy Ep > 10 keV, comparison with the experimental data shows a better agreement than the results calculated by the impact parameter approx-imation. For the latter, our theory predicts the correct experimental behaviour, and the discrepancies between our results and experimental ones are less than 30%. Based on the successive comparison with experiments, the cross sections for excitation to H(2p), single- and double-ionization and H- formation in H(2s)+H(2s) collisions are calculated in the energy range of 4-100 keV for the first time, and compared with those in H(1s)+H(1s) and H(1s)+H(2s) collisions.

  5. Systematic theoretical investigation of the zero-field splitting in Gd(III) complexes: Wave function and density functional approaches

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Shehryar, E-mail: sherkhan@fysik.su.se; Odelius, Michael, E-mail: odelius@fysik.su.se [Department of Physics, Stockholm University, AlbaNova University Center, S-106 91 Stockholm (Sweden); Kubica-Misztal, Aleksandra [Institute of Physics, Jagiellonian University, ul. Reymonta 4, PL-30-059 Krakow (Poland); Kruk, Danuta [Faculty of Mathematics and Computer Science, University of Warmia and Mazury in Olsztyn, Sloneczna 54, Olsztyn PL-10710 (Poland); Kowalewski, Jozef [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm (Sweden)

    2015-01-21

    The zero-field splitting (ZFS) of the electronic ground state in paramagnetic ions is a sensitive probe of the variations in the electronic and molecular structure with an impact on fields ranging from fundamental physical chemistry to medical applications. A detailed analysis of the ZFS in a series of symmetric Gd(III) complexes is presented in order to establish the applicability and accuracy of computational methods using multiconfigurational complete-active-space self-consistent field wave functions and of density functional theory calculations. The various computational schemes are then applied to larger complexes Gd(III)DOTA(H{sub 2}O){sup −}, Gd(III)DTPA(H{sub 2}O){sup 2−}, and Gd(III)(H{sub 2}O){sub 8}{sup 3+} in order to analyze how the theoretical results compare to experimentally derived parameters. In contrast to approximations based on density functional theory, the multiconfigurational methods produce results for the ZFS of Gd(III) complexes on the correct order of magnitude.

  6. Theoretical investigations on the geometric and electronic structures of polyacetylene molecule under the influence of external electric field

    Directory of Open Access Journals (Sweden)

    2009-11-01

    Full Text Available The geometric and electronic structures of all-trans polyacetylene (PA molecule in neutral, cationic, and anionic states have been studied theoretically by density functional theory method at the B3LYP/6-31+G* level. The results show that both the geometric and electronic structures of the PA molecule are sensitive to the external electric field (EF. For neutral PA molecule, with the increase of EF, the carbon-carbon single bonds are shortened while the carbon-carbon double bonds are elongated. The energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital (LUMO-HOMO gap decreases with the EF increasing. For cationic PA molecule, the carbon-carbon single bonds and carbon-carbon double bonds on the high potential side are elongated and shortened, respectively. While, the carboncarbon single bonds and carbon-carbon double bonds on the low potential side are shortened and elongated, respectively. Contrary to the neutral PA case, the LUMO-HOMO gap increases with the EF increasing. Contrast to the case of cationic PA, the evolution of carbon-carbon bond lengths for the anionic PA molecule under the external EF reverses. The LUMO-HOMO gap of the anionic PA molecule decreases with the increase of external EF. In addition, the spatial distributions of the HOMO and LUMO under the influence of external EF are also discussed for the PA molecule in neutral, cationic, and anionic states.

  7. Theoretical investigations on the structure and properties of p-n-alkoxy benzoic acid based liquid crystals

    Science.gov (United States)

    Subhapriya, P.; Dhanapal, V.; Sadasivam, K.; Vijayanand, P. S.

    2016-05-01

    The present study focused on the structural conformations, alkoxy chain lengths and mesogenic properties of two mole of alkoxy benzoic acid(nOBA) and one mole of suberic acid (SA) hydrogen bonded (nOBASA) complexes (n=8 to 10) by density functional theory (DFT) calculations and the Fourier Transform Infrared (FT-IR) spectrum. The intermolecular hydrogen bond formation was confirmed by the optimized geometric bond lengths and bond angles obtained by computation. Using the natural bond orbital (NBO) analysis, the stability of the molecule arising from hyper conjugative interactions and charge delocalization has been analyzed. Results obtained shows that the charge in electron density (ED) in σ*and π* antibonding orbital and second order delocalization energies E(2) authorizes the occurrence of intermolecular charge transfer. The molecular electrostatic potential (MEP) surface map is plotted over the optimized geometry of the molecule to obtain the chemical reactivity of the molecule. From the local charge distributions, the mesomorphic behavior and the nematic phase stabilities for each of the molecule have been predicted. Finally the calculated result is applied to simulated infrared spectra of 8OBASA mesogens which shows good agreement with the observed spectra. The comparison of the theoretical results obtained with the experimental ones shows the reliability of this DFT method.

  8. Systematic theoretical investigation of the zero-field splitting in Gd(III) complexes: wave function and density functional approaches.

    Science.gov (United States)

    Khan, Shehryar; Kubica-Misztal, Aleksandra; Kruk, Danuta; Kowalewski, Jozef; Odelius, Michael

    2015-01-21

    The zero-field splitting (ZFS) of the electronic ground state in paramagnetic ions is a sensitive probe of the variations in the electronic and molecular structure with an impact on fields ranging from fundamental physical chemistry to medical applications. A detailed analysis of the ZFS in a series of symmetric Gd(III) complexes is presented in order to establish the applicability and accuracy of computational methods using multiconfigurational complete-active-space self-consistent field wave functions and of density functional theory calculations. The various computational schemes are then applied to larger complexes Gd(III)DOTA(H2O)(-), Gd(III)DTPA(H2O)(2-), and Gd(III)(H2O)8(3+) in order to analyze how the theoretical results compare to experimentally derived parameters. In contrast to approximations based on density functional theory, the multiconfigurational methods produce results for the ZFS of Gd(III) complexes on the correct order of magnitude. PMID:25612706

  9. Release of cationic polymer-DNA complexes from the endosome: A theoretical investigation of the proton sponge hypothesis.

    Science.gov (United States)

    Yang, Shuang; May, Sylvio

    2008-11-14

    Polyplexes are complexes composed of DNA and cationic polymers; they are promising transport vehicles for nonviral gene delivery. Cationic polymers that contain protonatable groups, such as polyethylenimine, have been suggested to trigger endosomal escape of polyplexes according to the "proton sponge hypothesis." Here, osmotic swelling is induced by a decrease in the endosomal pH value, leading to an accumulation of polymer charge accompanied by the influx of Cl(-) ions to maintain overall electroneutrality. We study a theoretical model of the proton sponge mechanism. The model is based on the familiar Poisson-Boltzmann approach, modified so as to account for the presence of ionizable polyelectrolytes within self-consistent field theory with assumed ground state dominance. We consider polyplexes, composed of fixed amounts of DNA and cationic polymer, to coexist with uncomplexed cationic polymer in an enclosing vesicle of fixed volume. For such a system, we calculate the increase in osmotic pressure upon moderately decreasing the pH value and relate that pressure to the rupture tension of the enclosing membrane. Our model predicts membrane rupture upon pH decrease only within a certain range of free polymer content in the vesicle. That range narrows with increasing amount of DNA. Consequently, there exists a maximal amount of DNA that can be incorporated into a vesicle while maintaining the ability of content release through the proton sponge mechanism. PMID:19045433

  10. Thermodynamic properties and solidification kinetics of intermetallic Ni7Zr2 alloy investigated by electrostatic levitation technique and theoretical calculations

    Science.gov (United States)

    Li, L. H.; Hu, L.; Yang, S. J.; Wang, W. L.; Wei, B.

    2016-01-01

    The thermodynamic properties, including the density, volume expansion coefficient, ratio of specific heat to emissivity of intermetallic Ni7Zr2 alloy, have been measured using the non-contact electrostatic levitation technique. These properties vary linearly with temperature at solid and liquid states, even down to the obtained maximum undercooling of 317 K. The enthalpy, glass transition, diffusion coefficient, shear viscosity, and surface tension were obtained by using molecular dynamics simulations. Ni7Zr2 has a relatively poor glass forming ability, and the glass transition temperature is determined as 1026 K. The inter-diffusivity of Ni7Zr2 alloy fitted by Vogel-Fulcher-Tammann law yields a fragility parameter of 8.49, which indicates the fragile nature of this alloy. Due to the competition of increased thermodynamic driving force and decreased atomic diffusion, the dendrite growth velocity of Ni7Zr2 compound exhibits double-exponential relationship to the undercooling. The maximum growth velocity is predicted to be 0.45 m s-1 at the undercooling of 335 K. Theoretical analysis reveals that the dendrite growth is a diffusion-controlled process and the atomic diffusion speed is only 2.0 m s-1.

  11. A theoretical investigation on anomalous switching of single-stranded deoxyribonucleic acid (ssDNA) monolayers by water vapor

    Science.gov (United States)

    Zhao, Xin-Jun; Gao, Zhi-Fu; Jiang, Zhong-Ying

    2015-04-01

    In this paper, we use a molecular theory to study the anomalous switching of ssDNA monolayers. Here, both ssDNA-water and water-water hydrogen bonds and their explicit coupling to the ssDNA conformations are considered. We find that hydrogen bonding becomes a key element in inducing the anomalous switching of ssDNA monolayers. This finding accords well with the experimental observations. Based on our theoretical model, we predict that the anomalous switching induced by water vapor will be applicable to a wide range of hydrogen bonds polymers, and ssDNA-water hydrogen bonds and water-water hydrogen bonds hybridization will lead to the hydrogen-bond network formation of 3D ssDNA monolayers. Project supported by the National Natural Science Foundation of China (Grant Nos. 21264016, 11464047, and 21364016), the National Basic Research Program of China (Grant No. 2012CB821500), and the Natural Science Foundation of Xinjiang Uygur Autonomous Region, China (Grant No. 2013211A053).

  12. Thermodynamic properties and solidification kinetics of intermetallic Ni7Zr2 alloy investigated by electrostatic levitation technique and theoretical calculations

    International Nuclear Information System (INIS)

    The thermodynamic properties, including the density, volume expansion coefficient, ratio of specific heat to emissivity of intermetallic Ni7Zr2 alloy, have been measured using the non-contact electrostatic levitation technique. These properties vary linearly with temperature at solid and liquid states, even down to the obtained maximum undercooling of 317 K. The enthalpy, glass transition, diffusion coefficient, shear viscosity, and surface tension were obtained by using molecular dynamics simulations. Ni7Zr2 has a relatively poor glass forming ability, and the glass transition temperature is determined as 1026 K. The inter-diffusivity of Ni7Zr2 alloy fitted by Vogel–Fulcher–Tammann law yields a fragility parameter of 8.49, which indicates the fragile nature of this alloy. Due to the competition of increased thermodynamic driving force and decreased atomic diffusion, the dendrite growth velocity of Ni7Zr2 compound exhibits double-exponential relationship to the undercooling. The maximum growth velocity is predicted to be 0.45 m s−1 at the undercooling of 335 K. Theoretical analysis reveals that the dendrite growth is a diffusion-controlled process and the atomic diffusion speed is only 2.0 m s−1

  13. Theoretical and experimental investigation of a nonlinear compressive-mode energy harvester with high power output under weak excitations

    International Nuclear Information System (INIS)

    Harvesting ambient vibration energy is a promising method for realizing self-powered autonomous operation for low-power electronic devices. Most energy harvesters developed to date employ bending-beam configurations and work around the resonant points. There are two critical problems that have hindered the widespread adoption of energy harvesters: insufficient power output and narrow working bandwidth. To overcome these problems, we proposed a novel energy harvester, called a high-efficiency compressive-mode piezoelectric energy harvester (HC-PEH). The HC-PEH delicately synthesizes the merits of the force amplification effect of the flexural motion and the dynamic properties of elastic beams, and thus is capable of high power output with wide working bandwidth. In this paper, theoretical and experimental studies were performed on the HC-PEH. Taking nonlinear stiffness, nonlinear damping, and nonlinear piezoelectricity into account, we developed an analytical model that provides comprehensive insight into the nonlinear mechanical and electrical behaviors of the system. The analytical results closely render the experimental data and demonstrate great performance enhancement. In the experiment, a maximum power output of 54.7 mW is generated at 26 Hz under an acceleration of 4.9 m s−2, which is over one order of magnitude higher than other state-of-the-art systems. (paper)

  14. Theoretical investigations into spectral and non-linear optical properties of brucine and strychnine using density functional theory

    Science.gov (United States)

    Islam, Nasarul; Niaz, Saba; Manzoor, Taniya; Pandith, Altaf Hussain

    2014-10-01

    The density functional theoretical (DFT) computations were performed at the B3LYP/6-311G++(d, p) level to calculate the equilibrium geometry, vibrational wave numbers, intensities, and various other molecular properties of brucine and strychnine, which were found in satisfactory agreement with the experimental data. The out-of-phase stretching modes of aromatic rings and carbonyl stretching modes in combination with CH stretching modes at stereogenic centers generate VCD signals, which are remarkably efficient configuration markers for these chiral molecular systems. NBOs analysis reveals that the large values of second order perturbation energy (47.24 kcal/mol for brucine and 46.93 kcal/mol for strychnine) confirms strong hyperconjugative interaction between the orbital containing the lone pair of electron of nitrogen and the neighboring Cdbnd O antibonding orbital. The molecular electrostatic potential map of strychnine molecule, with no polar groups other than the lone keto group, shows less polarization, which accounts for its lower susceptibility towards electrophilic attack as compared to brucine.

  15. Influence of Nonpolar Substances on the Extraction Efficiency of Six Alkaloids in Zoagumhwan Investigated by Ultra Performance Liquid Chromatography and Photodiode Array Detection

    Directory of Open Access Journals (Sweden)

    Shijing Liu

    2012-11-01

    Full Text Available A reverse phase ultra performance liquid chromatography and photodiode array (UPLC-PDA detection method was established for the determination of six alkaloids in Zoagumhwan (ZGW, and further for investigating the influence of nonpolar substances on the extraction efficiency of these alkaloids. The method was based on a BEH C18 (50 mm × 2.1 mm, 1.7 μm column and mobile phase of aqueous phosphoric acid and acetonitrile including 0.05% buffer solution under gradient elution. ZGW samples of ZGW I, II, III and IV were obtained and prepared by pre-processing the crude materials of Coptidis rhizoma and Evodiae fructus using four technologies, namely direct water decoction, removal of nonpolar substances in Evodiae fructus by supercritical fluid extraction (SFE, removal of nonpolar substances in ZGW by SFE and removal of nonpolar substances in ZGW by steam distillation. The developed and validated UPLC-PDA method was precise, accurate and sensitive enough based on the facts that the six alkaloids showed good regression (r > 0.9998, the limit of detections and quantifications for six alkaloids were less than 28.8 and 94.5 ng/mL, respectively, and the recovery was in the range of 98.56%–103.24%. The sequence of the total contents of six alkaloids in these samples was ZGW II > ZGW IV > ZGW III > ZGW I. ZGW II, in which nonpolar substances, including essential oils, were firstly removed from Evodiae fructus by SFE, had the highest content of the total alkaloids, indicating that extraction efficiency of the total alkaloids could be remarkably increased after Evodiae fructus being extracted by SFE.

  16. Theoretical thermal-hydraulic investigations of the operational and safety features of the cold D2-moderator for SINQ

    International Nuclear Information System (INIS)

    In order to be able to investigate the behaviour of the gas-liquid mixture in the rather complex vessel and pipe system of the cold D2-moderator with heat exchanger and ballast volume, a computational model of the system has been set up. The model was first benchmarked against experimental data from the cold moderator mockup for the second cold source at the ILL Grenoble. It was then used to predict operational parameters such as pressure, velocity, moisture content and others of the system under normal conditions with the anticipated distribution of heat influx. Finally, the case of total loss of insulating vacuum was investigated. (author)

  17. Theoretical physics

    International Nuclear Information System (INIS)

    The 1988 progress report of the theoretical Physics Center (Ecole Polytechnique, France), is presented. The research activities are carried out in the fields of the supersymmetry theory, the dynamic systems theory, the statistical mechanics, the plasma physics and the random media. Substantial improvements are obtained on dynamical system investigations. In the field theory, the definition of the Gross-Neveu model is achieved. However the construction of the non-abelian gauge theories and the conformal theories are the main research activities. Concerning Astrophysics, a three-dimensional gravitational code is obtained. The activities of each team, and the list of the published papers, congress communications and thesis are given

  18. Theoretical investigation of active sites at the corners of Mgcl 2 crystallites in supported ziegler-natta catalysts

    KAUST Repository

    Correa, Andrea

    2012-05-08

    We present a theoretical study on possible models of catalytic active species corresponding to Ti-chloride species adsorbed at the corners of MgCl 2 crystallites. First we focused our efforts on the interaction between prototypes of three industrially relevant Lewis bases used as internal donors (1,3-diethers, alkoxysilanes and succinates) and MgCl 2 units at the corner of a MgCl 2 crystallite. Our calculations show that the energetic cost to extract MgCl 2 units at the corner of (104) edged MgCl 2 crystallites is not prohibitive, and that Lewis bases added during catalyst preparation make this process easier. After removal of one MgCl 2 unit, a short (110) stretch joining the (104) edges is formed. Adsorption of TiCl 4 on the generated vacancy originates a Ti-active species. In the second part of this manuscript, we report on the stereo- and regioselective behavior of this model of active species in the absence as well as in the presence of the three Lewis bases indicated above. Surface reconstruction due to the additional adsorption of an extra MgCl 2 layer is also considered. We show that, according to experimental data, Lewis bases coordinated in the proximity of the active Ti center confer a remarkable stereoselectivity. Moreover, surface reconstruction as well as donor coordination would improve regioselectivity by disfavoring secondary propene insertion. While still models of possible active species, our results indicate that defects, corners and surface reconstruction should be considered as possible anchoring sites for the catalytically active Ti-species. © 2012 American Chemical Society.

  19. Experimental investigation and theoretical analysis of pulse repetition rate adjustable deep ultraviolet picosecond radiation by second harmonic generation in KBe2BO3F2

    Science.gov (United States)

    Xu, Zhi; Zhang, Fengfeng; Zhang, Shenjin; Wang, Zhimin; Yang, Feng; Xu, Fengliang; Peng, Qinjun; Cui, Dafu; Zhang, Jingyuan; Wang, Xiaoyang; Chen, Chuangtian; Xu, Zuyan

    2014-06-01

    We reported on an experimental investigation and theoretical analysis of pulse repetition rate (PRR) adjustable deep ultraviolet (DUV) picosecond (ps) radiation by second harmonic generation (SHG) in KBe2BO3F2 (KBBF) crystal. Third harmonic radiation at 355 nm of a ps Nd:YVO4 laser output with PRR of 200 kHz-1 MHz was employed as the pump source. The dependence of the 177.3 nm output power on the 355 nm pump power was measured at different PRRs, and the maximum 177.3 nm average output power of 695 μW was obtained at the PRR of 200 kHz. The measured data agreed well with the results of the ps KBBF SHG theoretical simulations. Using simulations, the pulse width and the spectral bandwidth of the generated radiation at 177.3 nm were estimated to be 5.88 ps and 7.84 pm, respectively.

  20. Kinetics and thermodynamics of the reaction between the •OH radical and adenine – a theoretical investigation

    DEFF Research Database (Denmark)

    Milhøj, Birgitte Olai; Sauer, Stephan P. A.

    2015-01-01

    The accessibility of all possible reaction paths for the reaction between the nucleobase adenine and the •OH radical is investigated through quantum chemical calculations of barrier heights and rate constants at the wB97X-D/6-311++G(2df,2pd) level with Eckart tunneling corrections. First the...... Pople and Dunning basis sets, all of which have been employed in similar investigations in the literature. Improved energies are obtained through single point calculations with CCSD(T) and the same basis sets, and reaction rate constants are calculated for all methods both without tunneling corrections...... and with the Wigner, Bell and Eckart corrections. Compared to CCSD(T)//BHandHLYP/aug-cc-pVTZ reference results, the wB97XD/6-311++G(2df,2pd) method combined with Eckart tunneling corrections provides a sensible compromise between accuracy and time. Using this method all sub-reactions of the reaction...

  1. A Theoretical Investigation on the Reaction Mechanism of the C9H+ 12·Side-chain Decomposition

    Institute of Scientific and Technical Information of China (English)

    CHENG,Xueli; ZHAO,Yanyun; LI,Feng; ZHANG,Dongsheng

    2009-01-01

    n-Phenylpropane cation C9H+·12 serves as a prototype to investigate the reaction mechanisms of alkylbenzene cations.The decomposition reactions of C9H+·12 system have been studied extensively at the B3LYP/6-311 + + G**level with Gaussian 98 program package.All reaction channels were fully investigated with the vibrational mode analysis to confirm the transition states and with electron population analysis to discuss the electron redistribution,and to elucidate the reaction mechanism.The reaction mechanism shows that there is a non-barrier channel of C9H+·12→C7H+7+C2H·5,which is thermodynamically most favorable.

  2. Theoretical investigations of electronic structure and magnetism in Zr2CoSn full-Heusler compound

    International Nuclear Information System (INIS)

    The half-metallic properties of a new and promising full-Heusler compound, Zr2CoSn, are investigated by means of ab initio calculations within the Density Functional Theory framework. It was shown that the ferromagnetic ordered Hg2CuTi-type crystal structure is energetically the most favorable for this compound. The total magnetic moment is 3 μB/f.u. and follows a typical Slater–Pauling dependence. The half metallicity disappears if the unit cell volume is contracted by more than 5%. - Highlights: • Electronic structure and magnetic properties of Zr2CoSn were investigated. • The calculated equilibrium lattice parameter is a=6.76 Å • The total magnetic moment of Zr2CoSn is 3 μB/f.u. • Full spin polarization is at the ground state

  3. A Theoretical Investigation on the Reaction Mechanism of the C8H+·10 Side-Chain Decomposition Processes

    Institute of Scientific and Technical Information of China (English)

    CHENG Xue-Li; ZHAO Yan-Yun; LI Feng

    2008-01-01

    The dissociation of ethylbenzene cation C8H+·10 served as a prototype to investigate the decompasition mechanisms of alkylbenzene cations.The reactions of C8H+·10 decomposition reaction system have been studied extensively at the B3L YP/6-311++G** level with Gaussion 98 package.The chain reaction of C8H+·10 dissociation is initiated by C-H bond rupture.All reaction channels were fully investigated with the vibrational mode analysis to confirm the transition states and reveal the reaction mechanism.The energetically most favorable pathway is C8H+·10→TS4→·P2+H· and the channel ieading to C8H+·10 and C2H4 is also competitive.

  4. Theoretical investigations of electronic structure and magnetism in Zr{sub 2}CoSn full-Heusler compound

    Energy Technology Data Exchange (ETDEWEB)

    Birsan, A. [National Institute of Materials Physics, Atomistilor Str., No. 105 bis PO Box MG-7, 077125 Magurele (Romania); University of Bucharest, Faculty of Physics, Atomistilor Str., No. 105 PO Box MG-11, 077125 Magurele (Romania); Kuncser, V. [National Institute of Materials Physics, Atomistilor Str., No. 105 bis PO Box MG-7, 077125 Magurele (Romania)

    2015-08-15

    The half-metallic properties of a new and promising full-Heusler compound, Zr{sub 2}CoSn, are investigated by means of ab initio calculations within the Density Functional Theory framework. It was shown that the ferromagnetic ordered Hg{sub 2}CuTi-type crystal structure is energetically the most favorable for this compound. The total magnetic moment is 3 μ{sub B}/f.u. and follows a typical Slater–Pauling dependence. The half metallicity disappears if the unit cell volume is contracted by more than 5%. - Highlights: • Electronic structure and magnetic properties of Zr{sub 2}CoSn were investigated. • The calculated equilibrium lattice parameter is a=6.76 Å • The total magnetic moment of Zr{sub 2}CoSn is 3 μ{sub B}/f.u. • Full spin polarization is at the ground state.

  5. Theoretical investigation on ratiometric two-photon fluorescent probe for Zn2+ detection based on ICT mechanism

    Science.gov (United States)

    Huang, Shuang; Yang, Bao-Zhu; Ren, Ai-Min

    2016-06-01

    OPA (one-photon absorption), TPA (two-photon absorption) and fluorescence properties of a free ligand L upon coordination with Zn2+, and the regeneration with CN- were investigated in theory. According to our research, OPA spectra of ligand L show red-shift binding with Zn2+ while blue-shift with CN-. The fluorescence spectra and TPA wavelength are shifted in the same situation as those of OPA spectra. The value of TPA cross-section decreased at first, and then increased to 1813 GM for [L-Zn(CN)4]2-. Intramolecular charge transfer (ICT) mechanism was investigated by natural bond orbital (NBO) analysis. It demonstrates that L is hopeful to be a good ratiometric fluorescent probe for zinc ion detection in solution, and it can regenerate after CN- was introduced.

  6. Theoretical Investigation of the Performance of a Novel Loop Heat Pipe Solar Water Heating System for Use in Beijing, China

    OpenAIRE

    ZHAO, Xudong; Wang, Zhangyuan; Tang, Qi

    2010-01-01

    Abstract A novel loop heat pipe (LHP) solar water heating system for typical apartment buildings in Beijing was designed to enable effective collection of solar heat, distance transport, and efficient conversion of solar heat into hot water. Taking consideration of the heat balances occurring in various parts of the loop, such as the solar absorber, heat pipe loop, heat exchanger and storage tank, a computer model was developed to investigate the thermal performance of the system. ...

  7. Theoretical and experimental investigations of ferrofluids for guiding and detecting liquids in the subsurface. FY 1997 annual report

    International Nuclear Information System (INIS)

    Ferrofluids are stable colloidal suspensions of magnetic particles in various carrier liquids with high saturation magnetizations, which can be manipulated in virtually any fashion, defying gravitational or viscous forces in response to external magnetic fields. In this report, the authors review the results of their investigation of the potential of ferrofluids (1) to accurately and effectively guide reactants (for in-situ treatment) or barrier liquids (low-viscosity permeation grouts) to contaminated target zones in the subsurface using electromagnetic forces, and (2) to trace the movement and position of liquids injected in the subsurface using geophysical methods. They investigate the use of ferrofluids to enhance the efficiency of in-situ treatment and waste containment through (a) accurate guidance and delivery of reagent liquids to the desired subsurface contamination targets and/or (b) effective sweeping of the contaminated zone as ferrofluids move from the application point to an attracting magnet/collection point. They also investigate exploiting the strong magnetic signature of ferrofluids to develop a method for monitoring of liquid movement and position during injection using electromagnetic methods. The authors demonstrated the ability to induce ferrofluid movement in response to a magnetic field, and measured the corresponding magnetopressure. They demonstrated the feasibility of using conventional magnetometry for detecting subsurface zones of various shapes containing ferrofluids for tracing liquids injected for remediation or barrier formation. Experiments involving spherical, cylindrical and horizontal slabs showed a very good agreement between predictions and measurements

  8. Experimental and theoretical investigation of a pyridine containing Schiff base: Hirshfeld analysis of crystal structure, interaction with biomolecules and cytotoxicity

    Science.gov (United States)

    Chithiraikumar, S.; Neelakantan, M. A.

    2016-03-01

    A pyridine containing Schiff base (E)-2-methoxy-6-(((pyridin-2-ylmethyl)imino)methyl) phenol (L) was isolated in single crystals. The molecular structure of L was studied by FT-IR, NMR, UV-Vis techniques, single crystal XRD analysis and computationally by DFT method. L prefers enol form in the solid state. Electronic spectrum of L was recorded in different organic solvents to investigate the dependence of tautomerism on solvent types. The polar solvents facilitate the proton transfer by decreasing the activation energy needed for transition state. Potential energy curve for the intramolecular proton transfer in the ground state is generated in gas and solution phases. The 3D Hirshfeld surfaces and the associated 2D fingerprint plots were investigated. The percentages of various interactions were analyzed by fingerprint plots of Hirshfeld surface. The interaction of L with CT DNA was investigated under physiological conditions using UV-Vis spectroscopy, fluorescence quenching and molecular docking methods. Molecular docking studies reveal that binding of L to the groove of B-DNA is through hydrogen bonding and hydrophobic interactions. The in vitro cytotoxicity of L was carried out in two different human tumor cell lines, MCF 7 and MIA-Pa-Ca-2 exhibits moderate activity.

  9. Theoretical and experimental investigations of ferrofluids for guiding and detecting liquids in the subsurface. FY 1997 annual report

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, G.J.; Borglin, S.E.; Oldenburg, C.M.; Becker, A.

    1998-03-01

    Ferrofluids are stable colloidal suspensions of magnetic particles in various carrier liquids with high saturation magnetizations, which can be manipulated in virtually any fashion, defying gravitational or viscous forces in response to external magnetic fields. In this report, the authors review the results of their investigation of the potential of ferrofluids (1) to accurately and effectively guide reactants (for in-situ treatment) or barrier liquids (low-viscosity permeation grouts) to contaminated target zones in the subsurface using electromagnetic forces, and (2) to trace the movement and position of liquids injected in the subsurface using geophysical methods. They investigate the use of ferrofluids to enhance the efficiency of in-situ treatment and waste containment through (a) accurate guidance and delivery of reagent liquids to the desired subsurface contamination targets and/or (b) effective sweeping of the contaminated zone as ferrofluids move from the application point to an attracting magnet/collection point. They also investigate exploiting the strong magnetic signature of ferrofluids to develop a method for monitoring of liquid movement and position during injection using electromagnetic methods. The authors demonstrated the ability to induce ferrofluid movement in response to a magnetic field, and measured the corresponding magnetopressure. They demonstrated the feasibility of using conventional magnetometry for detecting subsurface zones of various shapes containing ferrofluids for tracing liquids injected for remediation or barrier formation. Experiments involving spherical, cylindrical and horizontal slabs showed a very good agreement between predictions and measurements.

  10. Experimental and theoretical investigation of water hammer induced by steam-water countercurrent flow a long horizontal pipe

    International Nuclear Information System (INIS)

    The condensation-induced water hammer in a horizontal pipe is the most damaging form of water hammer and its diagnosis is extremely difficult because of the complex nature of the underlying phenomena that occur at the steam-water interface. The current modeling concepts do not predict well the lower and upper boundaries of the water hammer accident occurred at San Onofre nuclear power station. In the present work, improved models that can predict the lower and upper boundaries of the initiation of water hammer induced by steam-water countercurrent flow in a long horizontal pipe is derived. In the analysis the interfacial friction factor, the criterion of onset of water hammer, and the interfacial heat transfer coefficient are the major constitutive relations, but there are several limited ranges in the application of current correlations being used. Several experiments have been conducted in adiabatic counter-current stratified flow with round pipe and rectangular duct test sections to develop the interfacial friction factor, the criterion of initiation of water hammer, and the correlation of water depth. First, an adiabatic semi-empirical correlation for interfacial friction factor has been developed based on the surface roughness concept. A comparison of the measured data including others with the predictions of the present correlation shows that the agreement is within ± 30% set of slug flow in a stratified wavy flow regime has been developed based on the total energy concept. This theoretical criterion agrees better with the measured data than the other criteria available in the literature, but predicts about 92∼107%. An empirical formulus for the criterion has been also developed and compared with others. Third, correlations which can predict the slope of liquid surface and the water depth at outlets of pipe and duct respectively, have been developed based on experimental data in countercurrent stratified tests. The correlations predict the measured data

  11. Experimental and Theoretical Investigations of Magnetic Exchange Pathways in Structurally Diverse Iron(III) Schiff-Base Complexes.

    Science.gov (United States)

    Herchel, Radovan; Nemec, Ivan; Machata, Marek; Trávníček, Zdeněk

    2015-09-01

    The synthesis, and the structural and magnetic properties, of the following new iron(III) Schiff base complexes with the {O',N,O″}-chelating ligand H2L (2-hydroxyphenylsalicylaldimine) are reported: K[FeL2]·H2O (1), (Pr3NH)[FeL2]·2CH3OH (2), [FeL(bpyO2) (CH3OH)][FeL2]·CH3OH (3), [Fe2L3(CH3OH)]·2CH3OH·H2O (4), and [{Fe2L2}(μ-OH)2{FeL(bpyO2)}2][BPh4]2·2H2O (5), where Pr3NH(+) represents the tripropylammonium cation and bpyO2 stands for 2,2'-bipyridine-N-dioxide. A thorough density functional theory (DFT) study of magnetic interactions (the isotropic exchange) at the B3LYP/def-TZVP level of theory was employed, and calculations have revealed superexchange pathways through intramolecular/intermolecular noncovalent contacts (π-π stacking, C-H···O and O-H···O hydrogen bonds, diamagnetic metal cations) and/or covalent bonds ((μ-O(Ph), μ-OH) or bis(μ-O(Ph)) bridging modes), which helped us to postulate trustworthy spin Hamiltonians for magnetic analysis of experimental data. Within the reported family of compounds 1-5, the mediators of the antiferromagnetic exchange can be sorted by their increasing strength as follows: π-π stacking (J(DFT) = -0.022 cm(-1)/J(mag) = -0.025(4) cm(-1) in 2) < C-H···O contacts and π-π stacking (J(DFT) = -0.19 cm(-1)/J(mag) = -0.347(9)cm(-1) in 1) < O-H···O hydrogen bonds (J(DFT) = -0.53 cm(-1)/J(mag) = -0.41(1) cm(-1) in 3) < bis(μ-O(Ph)) bridge (J(DFT) = -13.8 cm(-1)/J(mag) = -12.3(9) cm(-1) in 4) < (μ-O(Ph), μ-OH) bridge (J(DFT) = -18.0 cm(-1)/J(mag) = -17.1(2) cm(-1) in 5), where J(DFT) and J(mag) are the isotropic exchange parameters derived from DFT calculations, and analysis of the experimental magnetic data, respectively. The good agreement between theoretically calculated and experimentally derived isotropic exchange parameters suggests that this procedure is applicable also for other chemical and structural systems to interpret magnetic data properly. PMID:26262499

  12. Theoretical investigation of the broad one-photon absorption line-shape of a flexible symmetric carbazole derivative.

    Science.gov (United States)

    Liu, Yanli; Cerezo, Javier; Santoro, Fabrizio; Rizzo, Antonio; Lin, Na; Zhao, Xian

    2016-08-17

    The one-photon absorption spectrum of a carbazole derivative has been studied by employing density functional response theory combined with a mixed quantum/classical (QC) approach to simulate the spectral shape. In a first step of our analysis we employed the vertical gradient (VG) vibronic model to investigate the role of Franck-Condon (FC) profiles of the first ten electronic excited states of the system, underlying most of the range of the experimental spectrum. We then focussed on the first six excited states covering the low-energy region of the spectrum, and investigated the effect of inter-state electronic couplings on the spectral shapes within Herzberg-Teller (HT) theory. Furthermore, in order to introduce the broadening effects due to the two inter-ring torsions, we employed a QC approach, adopting VG vibronic models for high-frequency modes and computing the contribution of the torsions to the spectrum from the distribution of the excitation energies along a two-dimensional relaxed potential energy. Finally, we estimated the solvent inhomogeneous broadening by computing the solvent reorganization energy using a polarizable continuum model. Our calculations allow us to obtain a non-phenomenological description of the low-energy part of the spectrum in semi-quantitative agreement with experiment and to dissect the relative importance of solvent, torsional flexibility, FC vibronic progressions, and inter-state couplings in determining its broad spectral shapes and the modulation of its intensity. Our analysis also clearly highlights that the investigated carbazole represents a big challenge for available methodologies due to the existence of many close-lying excited electronic states coupled by internal low-frequency and high-frequency motions and by solvent fluctuations. The study of their impact on the spectra at the HT level is only approximate and more refined treatments would require a fully quantum-dynamical calculation on the manifold of the coupled

  13. Theoretical investigation of the mechanical and thermodynamics properties of Nb{sub 3}Ga superconductor under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Wenyan, E-mail: tianwy503@163.com [College of Electronics and Information Engineering, Taiyuan University of Science and Technology, Taiyuan 030024 (China); Chen, Haichuan [College of Electrical Engineering and Information Technology, Xihua University, Chengdu 610039 (China)

    2015-11-05

    The mechanical and thermodynamics properties of Nb{sub 3}Ga under pressure have been studied and analyzed using first-principles combined with quasi-harmonic Debye model. The calculated lattice parameter of the ground state is in well agreement with the experimental data. The pressure dependence of a/a{sub 0} and V/V{sub 0} are investigated, the bulk modulus B{sub 0} and its pressure derivative B{sup ′} are found to be 164.5 GPa and 3.936, respectively. The elastic constants under pressure are obtained and the polycrystalline elastic moduli of Nb{sub 3}Ga are calculated derived from the single-crystal elastic constants. The results show that Nb{sub 3}Ga is stable and behaves in a ductile manner up to 40 GPa. In addition, the elastic anisotropy, Vickers hardness as well as the melting temperature of Nb{sub 3}Ga are investigated. Finally, the pressure and temperature dependence of the thermodynamic properties are also been obtained in the ranges of 0–40 GPa and 0–1000 K through the quasi-harmonic Debye model. - Highlights: • The physical properties of Nb{sub 3}Ga were investigated. • The bulk modulus B{sub 0} and its pressure derivative B{sup ′} are found to be 164.5 GPa and 3.936. • The Nb{sub 3}Ga is stable and behaves in a ductile manner up to 40 GPa. • The temperature dependence of the thermodynamic properties is obtained. • The 3D figures of the Young's modulus for Nb{sub 3}Ga are obtained under pressure.

  14. Theoretical investigations of electronic structure and magnetism in Zr2CoSn full-Heusler compound

    OpenAIRE

    Birsan, A.; Kuncser, V.

    2014-01-01

    The half-metallic properties of a new and promising full-Heusler compound, Zr2CoSn, are investigated by means of ab initio calculations within the Density Functional Theory framework. The ferromagnetic ordered Hg2CuTi-type crystal structure is energetically favorable and the optimized lattice parameter is 6.76 A. The total magnetic moment calculated is 3 uB/f.u. and follows a typical Slater-Pauling dependence. The half metallicity disappears if the unit cell volume is contracted by 5 %.

  15. Theoretical investigation of the behavior of CuSe2O5 compound in high magnetic fields

    OpenAIRE

    Saghafi, Z.; Jahangiri, J.; Mahdavifar, S.; Hadipour, H.; Shayesteh, S. Farjami

    2015-01-01

    Based on analytical and numerical approaches, we investigate thermodynamic properties of CuSe2O5 at high magnetic fields which is a candidate for the strong intra-chain interaction in quasi one-dimensional (1D) quantum magnets. Magnetic behavior of the system can be described by the 1D spin-1/2 XXZ model in the presence of the Dzyaloshinskii-Moriya (DM) interaction. Un- der these circumstances, there is one quantum critical field in this compound. Below the quantum critical field the spin cha...

  16. Theoretical investigations of electronic structure and magnetism in Zr2CoSn full-Heusler compound

    Science.gov (United States)

    Birsan, A.; Kuncser, V.

    2015-08-01

    The half-metallic properties of a new and promising full-Heusler compound, Zr2CoSn, are investigated by means of ab initio calculations within the Density Functional Theory framework. It was shown that the ferromagnetic ordered Hg2CuTi-type crystal structure is energetically the most favorable for this compound. The total magnetic moment is 3 μB/f.u. and follows a typical Slater-Pauling dependence. The half metallicity disappears if the unit cell volume is contracted by more than 5%.

  17. Salen, reduced salen and N-alkylated salen type compounds: Spectral characterization, theoretical investigation and biological studies

    Science.gov (United States)

    Jeslin Kanaga Inba, P.; Annaraj, B.; Thalamuthu, S.; Neelakantan, M. A.

    2013-03-01

    Salen [2,2'-{propane-1,3-diylbis[nitrilo(E)methylylidene]}bis(6-methoxyphenol)], reduced salen [(2,2'-[propane-1,3-diylbis(iminomethylene))]bis(6-methoxyphenol)] and N-alkylated salen [diethyl-2,2'-(propane-1,3-diylbis((2-hydroxy-3-methoxybenzyl) azanediyl))diacetate] compounds have been synthesized and characterized by IR, 1H NMR, 13C NMR and UV-vis. spectroscopy. Molecular geometry of the title compounds in the ground state has been optimized by density functional method (B3LYP) with 6-31G basis set. Vibrational frequencies of the compounds were computed and compared with the experimental values. Tautomeric stability study of salen inferred that the enolimine form is more stable than its ketoenamine form in gas phase. The spectral behavior of salen in polar and nonpolar solvents was examined demonstrate the positive solvatochromism. The synthesized compounds have been studied with respect to their binding to calf thymus DNA showed that there were interactions between the compounds and DNA through a groove binding mode. Furthermore, the DNA cleavage activity of the compounds has been investigated by gel electrophoresis. The antioxidant properties of compounds were evaluated by DPPH method. The N-alkylated compound has a higher DPPH free radical scavenging activity. The antimicrobial activity was investigated on various gram positive and gram negative bacteria.

  18. Inhibition of carbon steel corrosion in CO2-saturated brine using some newly surfactants based on palm oil: Experimental and theoretical investigations

    International Nuclear Information System (INIS)

    New surfactants from the type of fatty acids derivatives were synthesized based on palm oil and their inhibitive action against the corrosion of carbon steel in CO2-saturated 1% NaCl solution were investigated at 50 °C. The detailed study of surfactants as corrosion inhibitors is given using polarization curves and electrochemical impedance spectroscopy methods. The inhibition efficiencies obtained from the two employed methods are nearly closed. Results show that, the investigated surfactants are good inhibitors and its inhibition efficiency reaches to 98.95% at 100 ppm for inhibitor V. The high inhibition efficiencies were attributed to the simple blocking effect by adsorption of inhibitor molecules on the steel surface. The surface activity of the synthesized surfactant solutions was determined using surface tension measurements at 25 °C. Adsorption of the inhibitors on the carbon steel surface was found to obey Langmuir's adsorption isotherm and chemisorption. The correlation between the inhibition efficiencies of the studied surfactants and their molecular structures has been investigated using quantum chemical calculations. The obtained theoretical results have been supported our experimental data. - Graphical abstract: To investigate the relationship between molecular structures of the studied surfactants and their inhibition effect; Quantum chemical molecular calculations were performed. The following quantum chemical indices such as highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), energy gap ΔE = EHOMO − ELUMO, and dipole moment (μ) were considered. The relation between these parameters and the inhibition efficiencies was explained. The obtained theoretical results have been supported our experimental data. - Highlights: • Effect of surfactants on carbon steel corrosion in CO2-saturted brine was investigated. • The high inhibition efficiency attributed to the adherent adsorption of the investigated

  19. Inhibition of carbon steel corrosion in CO{sub 2}-saturated brine using some newly surfactants based on palm oil: Experimental and theoretical investigations

    Energy Technology Data Exchange (ETDEWEB)

    Abd El-Lateef, Hany M., E-mail: Hany_shubra@yahoo.co.uk [Chemistry Department, Faculty of Science, Sohag University, Sohag (Egypt); Abbasov, V.M.; Aliyeva, L.I.; Qasimov, E.E.; Ismayilov, I.T. [Mamedaliev Institute of Petrochemical Processes, National Academy of Sciences of Azerbaijan, AZ1025 Baku (Azerbaijan)

    2013-11-01

    New surfactants from the type of fatty acids derivatives were synthesized based on palm oil and their inhibitive action against the corrosion of carbon steel in CO{sub 2}-saturated 1% NaCl solution were investigated at 50 °C. The detailed study of surfactants as corrosion inhibitors is given using polarization curves and electrochemical impedance spectroscopy methods. The inhibition efficiencies obtained from the two employed methods are nearly closed. Results show that, the investigated surfactants are good inhibitors and its inhibition efficiency reaches to 98.95% at 100 ppm for inhibitor V. The high inhibition efficiencies were attributed to the simple blocking effect by adsorption of inhibitor molecules on the steel surface. The surface activity of the synthesized surfactant solutions was determined using surface tension measurements at 25 °C. Adsorption of the inhibitors on the carbon steel surface was found to obey Langmuir's adsorption isotherm and chemisorption. The correlation between the inhibition efficiencies of the studied surfactants and their molecular structures has been investigated using quantum chemical calculations. The obtained theoretical results have been supported our experimental data. - Graphical abstract: To investigate the relationship between molecular structures of the studied surfactants and their inhibition effect; Quantum chemical molecular calculations were performed. The following quantum chemical indices such as highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), energy gap ΔE = E{sub HOMO} − E{sub LUMO}, and dipole moment (μ) were considered. The relation between these parameters and the inhibition efficiencies was explained. The obtained theoretical results have been supported our experimental data. - Highlights: • Effect of surfactants on carbon steel corrosion in CO{sub 2}-saturted brine was investigated. • The high inhibition efficiency attributed to the adherent adsorption

  20. Theoretical investigation of electronic structure of PbSxTe1-x and PbSexTe1-x alloys

    International Nuclear Information System (INIS)

    Using first-principles total-energy calculations within the hybrid full-potential augmented plane-wave plus local orbitals (APW+lo) method, we have investigated the structural and electronic properties of PbSxTe1-xand PbSexTe1-x alloys. In this study we employ two exchange and correlation approximations, the local-density (LDA) and generalized gradient (GGA) approximations. Equilibrium volumes, bulk moduli, charge densities, density of states and band structures of lead chalcogenide alloys, in the rocksalt structure are presented. The results show that both ternary alloys possess a direct and smaller energy gap comparing with binary compounds studied. A model structure of 32-atoms supercell is used

  1. Theoretical investigation of superconductivity in ternary silicide NaAlSi with layered diamond-like structure

    Science.gov (United States)

    Tütüncü, H. M.; Karaca, Ertuǧrul; Srivastava, G. P.

    2016-04-01

    We have investigated the electronic structure, phonon modes and electron-phonon coupling to understand superconductivity in the ternary silicide NaAlSi with a layered diamond-like structure. Our electronic results, using the density functional theory within a generalized gradient approximation, indicate that the density of states at the Fermi level is mainly governed by Si p states. The largest contributions to the electron-phonon coupling parameter involve Si-related vibrations both in the x-y plane as well as along the z-axis in the x-z plane. Our results indicate that this material is an s-p electron superconductor with a medium level electron-phonon coupling parameter of 0.68. Using the Allen-Dynes modification of the McMillan formula we obtain the superconducting critical temperature of 6.98 K, in excellent agreement with experimentally determined value of 7 K.

  2. Theoretical and experimental investigation on adaptability of charcoal beds to containment filter venting in Italian nuclear power plant

    International Nuclear Information System (INIS)

    The work has been divided into three parts. The first one gives a description of the facilities under investigation during some selected accidental conditions, also described. The second part, which consists of an experimental work, tries to identify the behavior of charcoal beds in terms of pressure drop vs the aerosol mass loading and of aerosol retention efficiency. On the basis of the experimental findings, the prediction of the behavior of the real beds is carried out in the third part, as regards the pressure drop through the beds, related to the selected accident scenarios. In addition in this last part the results of a preliminary evaluation of the maximum decay power picked up by the beds without reaching the carbon self-ignition temperature have been reported

  3. Theoretical Investigation on the Electron and Energy Transfer between Peripheral Carrier Transport Groups and Central Chromophores in Electroluminescent Materials

    Institute of Scientific and Technical Information of China (English)

    潘玉钰; 刘丹丹; 许海; 刘晓冬; 孙冠楠; 杨兵; 马於光

    2012-01-01

    The molecular materials with structures of luminescent core and peripheral carrier groups (e.g. carbazoles), have exhibited high-performance in organic light-emitting diodes (OLEDs). Present work is to understand the basic process of electronic and energy exchange between the peripheral functional groups and the central core through quantum chemical analysis. As an example, 4,7-bis(9,9-bis(6-(9H-carbazol-9-yl)hexyl)-9H-fluoren-2-yl)benzo[c]- [1,2,5]thiadiazole (TCBzC) is investigated in regards to optoelectronic properties using density functional theory (DFT). The results suggest that the forbidden transition from peripheral carbazole to the central chromophore core makes for separated electrical and optical properties, and high performance electroluminescence (EL) is mainly at- tributed to the energy-transfer from carbazoles to the fluorene derivative core.

  4. Benzene analogues of (quasi-)planar M@BnHn compounds (M = V−, Cr, Mn+): A theoretical investigation

    International Nuclear Information System (INIS)

    The stability of M@BnHn (M = V−, Cr, Mn+; n = 5–8) is investigated by density functional theory. For n = 6–8, the isomers possess (quasi-)planar local minima showed by geometry optimization at TPSSh/6-311+G** level. All the optimized structures are thermodynamics stable according to the large HOMO-LUMO gap, binding energy, vertical ionization potential, and vertical electron affinity analysis. The peripheral and central atomic radius fit each other best at n = 7 confirmed by the variation of the binding energy values. The availability of d atom orbitals in M for participation in the π-delocalized bonding with the peripheral ring leads to the aromaticity of the (quasi-)planar structures and makes them the benzene analogues. This work establishes firmly the metal-doped borane rings as a new type of aromatic molecule

  5. Theoretical Investigations on the Interaction Nature of Br2 with HF, H2O and NH3

    Institute of Scientific and Technical Information of China (English)

    WU Wen-Sheng; WANG Zhao-Xu; ZHENG Bai-Shu; SHU Hua; LI Xiang; WU Jun-Yong

    2007-01-01

    The interactions of HF, H2O and NH3 with Br2 are investigated at the MP2(full)/ aug-cc-pVDZ level. It is found that two kinds of stable complexes, halogen-bonded and hydrogen- bonded complexes, exist between Br2 and HF and between Br2 and H2O. The interaction energy analysis and natural population analysis (NPA) are conducted to these two kinds of complexes, indicating the halogen-bonded complexes are more stable than the corresponding hydrogen-bonded ones, and the binding energies of the former increase in the order HF<H2O<NH3, different from HF>H2O for the latter.

  6. Theoretical investigations of the optical and EPR spectra for trivalent cerium and ytterbium ions in orthorhombic YF3 crystal

    Science.gov (United States)

    Liu, Hong-Gang; Zheng, Wen-Chen

    2016-09-01

    The optical spectra and electron paramagnetic resonance (EPR) parameters (g factors and hyperfine structure constants A) for trivalent cerium and ytterbium ions in YF3 crystal with orthorhombic structure are investigated together by the complete diagonalization (of energy matrix) method (CDM). The obtained results are in reasonable agreement with the experimental ones. More importantly, two magnetically nonequivalent centers in YF3 crystal observed in EPR experiments are confirmed and ascribed to their specific positions in a unit cell by our calculations based on superposition model (SPM) analysis. Such identification of local sites with different magnetic properties would help us to understand not only the EPR spectra and magnetic susceptibility of other lanthanide ions doped in crystals with the same structure as YF3 but also the energy transfer scheme between two lanthanide ions occupying such two sites. All results are discussed carefully.

  7. A theoretical investigation of Ferromagnetic Resonance Linewidth and damping constants in coupled trilayer and spin valve systems

    International Nuclear Information System (INIS)

    The ferromagnetic resonance intrinsic field linewidth ΔH is investigated for a multilayer system such as a coupled trilayer and a spin valve structure. The magnetic coupling between two ferromagnetic layers separated by a nonmagnetic interlayer will be described by the bilinear J1 and biquadratic J2 coupling parameters. The interaction at the interface of the first ferromagnetic layer with the antiferromagnetic one is account for by the exchange anisotropy field, HE. A general formula is derived for the intrinsic linewidth ΔH. The explicit dependence of ΔH with HE, J1 and J2 will be highlighted. Analytical expressions for each mode field linewidth are found in special cases. Equivalent damping constants will be discussed

  8. The hyperbolic effect of density and strength of inter beta-cell coupling on islet bursting: a theoretical investigation

    Directory of Open Access Journals (Sweden)

    Wang Xujing

    2008-08-01

    Full Text Available Abstract Background Insulin, the principal regulating hormone of blood glucose, is released through the bursting of the pancreatic islets. Increasing evidence indicates the importance of islet morphostructure in its function, and the need of a quantitative investigation. Recently we have studied this problem from the perspective of islet bursting of insulin, utilizing a new 3D hexagonal closest packing (HCP model of islet structure that we have developed. Quantitative non-linear dependence of islet function on its structure was found. In this study, we further investigate two key structural measures: the number of neighboring cells that each β-cell is coupled to, nc, and the coupling strength, gc. Results β-cell clusters of different sizes with number of β-cells nβ ranging from 1–343, nc from 0–12, and gc from 0–1000 pS, were simulated. Three functional measures of islet bursting characteristics – fraction of bursting β-cells fb, synchronization index λ, and bursting period Tb, were quantified. The results revealed a hyperbolic dependence on the combined effect of nc and gc. From this we propose to define a dimensionless cluster coupling index or CCI, as a composite measure for islet morphostructural integrity. We show that the robustness of islet oscillatory bursting depends on CCI, with all three functional measures fb, λ and Tb increasing monotonically with CCI when it is small, and plateau around CCI = 1. Conclusion CCI is a good islet function predictor. It has the potential of linking islet structure and function, and providing insight to identify therapeutic targets for the preservation and restoration of islet β-cell mass and function.

  9. Theoretical investigations of structural, electronic and elastic properties of U2S3 type Nb2N3 under high pressure

    International Nuclear Information System (INIS)

    The structural, electronic and elastic properties of U2S3 type Nb2N3 under pressure ranging from 0 GPa to 100 GPa are investigated by plane-wave pseudopotential density functional theory with the generalized gradient approximation in this paper. The results at zero pressure are in good agreement with available theoretical results. The properties of U2S3 type Nb2N3 are compared to the new synthetic superhard material η-Ta2N3. The results show that U2S3 type Nb2N3 is hard to compress, and expected to have comparable hardness to η-Ta2N3

  10. Detailed theoretical investigation and comparison of the cascadability of conventional and gain-clamped SOA gates in multi wavelength optical networks

    DEFF Research Database (Denmark)

    Wolfson, David

    1999-01-01

    A detailed theoretical investigation of the cascadability of GC-SOAs and SOAs in WDM networks is presented. The analysis shows that the cascadability of SOAs is limited by degradation of both extinction ratio and ASE accumulation, whereas the cascadability for GC-SOAs mainly is limited by an...... accumulation af ASE. This result is superior cascadability of GC-SOAs at a channel bit rate of 2,5 Gbit/s in systems with up to at least 16 channels even when compared to short cavity SOA gates....

  11. Experimental and theoretical investigation of the effect of SiO2 content in gate dielectrics on work function shift induced by nanoscale capping layers

    KAUST Repository

    Caraveo-Frescas, J. A.

    2012-09-10

    The impact of SiO2 content in ultrathin gate dielectrics on the magnitude of the effective work function (EWF) shift induced by nanoscale capping layers has been investigated experimentally and theoretically. The magnitude of the effective work function shift for four different capping layers (AlN, Al2O3, La2O3, and Gd2O3) is measured as a function of SiO2 content in the gate dielectric. A nearly linear increase of this shift with SiO2 content is observed for all capping layers. The origin of this dependence is explained using density functional theory simulations.

  12. COMBINED THEORETICAL AND EXPERIMENTAL INVESTIGATION OF MECHANISMS AND KINETICS OF VAPOR-PHASE MERCURY UPTAKE BY CARBONACOUES SURFACES

    Energy Technology Data Exchange (ETDEWEB)

    Radisav D. Vidic

    2002-05-01

    The first part of this study evaluated the application of a versatile optical technique to study the adsorption and desorption of model adsorbates representative of volatile polar (acetone) and non-polar (propane) organic compounds on a model carbonaceous surface under ultra high vacuum (UHV) conditions. The results showed the strong correlation between optical differential reflectance (ODR) and adsorbate coverage determined by temperature programmed desorption (TPD). ODR technique was proved to be a powerful tool to investigate surface adsorption and desorption from UHV to high pressure conditions. The effects of chemical functionality and surface morphology on the adsorption/desorption behavior of acetone, propane and mercury were investigated for two model carbonaceous surfaces, namely air-cleaved highly oriented pyrolytic graphite (HOPG) and plasma-oxidized HOPG. They can be removed by thermal treatment (> 500 K). The presence of these groups almost completely suppresses propane adsorption at 90K and removal of these groups leads to dramatic increase in adsorption capacity. The amount of acetone adsorbed is independent of surface heat treatment and depends only on total exposure. The effects of morphological heterogeneity is evident for plasma-oxidized HOPG as this substrate provides greater surface area, as well as higher energy binding sites. Mercury adsorption at 100 K on HOPG surfaces with and without chemical functionalities and topological heterogeneity created by plasma oxidation occurs through physisorption. The removal of chemical functionalities from HOPG surface enhances mercury physisorption. Plasma oxidation of HOPG provides additional surface area for mercury adsorption. Mercury adsorption by activated carbon at atmospheric pressure occurs through two distinct mechanisms, physisorption below 348 K and chemisorption above 348 K. No significant impact of oxygen functionalities was observed in the chemisorption region. The key findings of this study

  13. Theoretical investigation of the vortex state in new superconductors: MgB2 and PrOs4Sb12

    International Nuclear Information System (INIS)

    As illustrated by the present thesis work, gap function anisotropy and crystal anisotropy are combined when influencing superconducting properties under a magnetic field. In order to study the mixed state of the recently discovered multiband superconductor MgB2, we first derive the Ginzburg-Landau functional for a two-gap superconductor from a weak coupling BCS model. The interaction between the two condensates is then described by a unique Josephson-type coupling. The two-gap theory then enables to explain the curvature and the anisotropy of the upper critical field, as well as the 30 degrees change of orientation for the vortex lattice which is observed when increasing the strength of the magnetic field applied along the c-tilde axis. Besides, we investigate the vortex lattice geometry in the superconducting heavy fermion PrOs4Sb12. When taking into account non local corrections for an s-wave Th-tetrahedral superconductor, we can explain the observed deformation of the lattice by the crystal symmetry of the compound. Ab initio results of the band structures confirm quantitatively our analysis. (author)

  14. Experimental and theoretical investigations of crack initiation and crack propagation in heavy section hollow cylinders under pressurized thermal shock loading

    International Nuclear Information System (INIS)

    The integrity of the reactor pressure vessel (RPV) must be guaranteed for all failure and loading conditions which may occur during operation and accidents. The impact of a pressurized thermal shock on postulated cracks is to be considered as one of the worst cases. In a loss-of-coolant accident with injection of cooling water such loads are to be expected. It was the essential aim of these investigations to qualify the knowledge of the temperature gradients, of the flow paths in the medium, of the stresses in the structure, of the crack loading and of the stable crack growth of the RPV-material. A result of that is high thermal stresses in wall areas adjacent to the inner surface and great thermal stress gradients in the wall. Critical areas for pressurized thermal shock transients are particularly cracked zones. Then the secondary thermal stresses can considerably increase the loading at the crack tip relative to the primary mechanical stresses resulting from the internal pressure, on the basis of the cooling process the toughness and the fracture toughness of the ferritic material will be reduced. In the Federal Republic of Germany extensive thermal shock examinations are being conducted at a decommissioned superheated steam reactor (HDR). Since at this real component the parameter variation in a wide spectrum is not possible, especially with regard to the material toughness, such parameter variations are being conducted at the MPA Stuttgart in connection with the research project emergency cooling simulation (NKS)

  15. Theoretical investigation of fluorination effect on the charge carrier transport properties of fused anthra-tetrathiophene and its derivatives.

    Science.gov (United States)

    Yin, Jun; Chaitanya, Kadali; Ju, Xue-Hai

    2016-03-01

    The crystal structures of known anthra-tetrathiophene (ATT) and its three fluorinated derivatives (ATT1, ATT2 and ATT3) were predicted by the Monte Carlo-simulated annealing method with the embedded electrostatic potential (ESP) charges. The most stable crystal structures were further optimized by the density functional theory with the dispersion energy (DFT-D) method. In addition, the effect of the electron-withdrawing fluorine atoms on the molecular geometry, molecular stacking, electronic and transport properties of title compounds were investigated by the density functional theory and the incoherent charge-hopping model. The calculated results show that the introduction of fluorine atoms does not affect the molecular planarity but decreases the HOMO-LUMO gap, which is beneficial to electron injection and provides more charge carrier stabilization. The improved electron mobility from ATT to ATT3 is attributed to the favorable molecular packing with strong π-π interaction and the short stacking distance. ATT2 and ATT3 exhibit remarkable angular dependence of mobilities and anisotropic behaviors. The band structures reveal that all the paths with larger transfer integrals are along the directions of large dispersions in the valence band (VB) and conduction band (CB). ATT3 has the largest electron mobility (0.48 cm(2)V(-1)s(-1)) among the four compounds, indicating that fluorination is an effective approach to improve electron transport. PMID:26774641

  16. Theoretical Investigation on Single-Wall Carbon Nanotubes Doped with Nitrogen, Pyridine-Like Nitrogen Defects, and Transition Metal Atoms

    Directory of Open Access Journals (Sweden)

    Michael Mananghaya

    2012-01-01

    Full Text Available This study addresses the inherent difficulty in synthesizing single-walled carbon nanotubes (SWCNTs with uniform chirality and well-defined electronic properties through the introduction of dopants, topological defects, and intercalation of metals. Depending on the desired application, one can modify the electronic and magnetic properties of SWCNTs through an appropriate introduction of imperfections. This scheme broadens the application areas of SWCNTs. Under this motivation, we present our ongoing investigations of the following models: (i (10, 0 and (5, 5 SWCNT doped with nitrogen (CNxNT, (ii (10, 0 and (5, 5 SWCNT with pyridine-like defects (3NV-CNxNT, (iii (10, 0 SWCNT with porphyrine-like defects (4ND-CNxNT. Models (ii and (iii were chemically functionalized with 14 transition metals (TMs: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Pt and Au. Using the spin-unrestricted density functional theory (DFT, stable configurations, deformations, formation and binding energies, the effects of the doping concentration of nitrogen, pyridine-like and porphyrine-like defects on the electronic properties were all examined. Results reveal that the electronic properties of SWCNTs show strong dependence on the concentration and configuration of nitrogen impurities, its defects, and the TMs adsorbed.

  17. Experimental and theoretical investigation of a novel mononuclear copper(II) azido compound with tridentate (NNO) Schiff base

    Science.gov (United States)

    Karahan, Ahmet; Karabulut, Sedat; Dal, Hakan; Kurtaran, Raif; Leszczynski, Jerzy

    2015-08-01

    The tridentate (NNO) Schiff base (HL), has been prepared by the condensation of 2-(aminomethyl)pyridine with 5-chloro-salicylaldehyde. The mononuclear [N-(2-pyridylmethyl)-3-chloro-salicylaldiminato] (azido) copper(II) complex of general formula [Cu(L)(N3)] (1) has been synthesized by the treatment of HL and CuCl2·2H2O with sodium azide. The ligand and complex have been investigated by various methods including IR, TG-DTA and X-ray diffraction techniques. The complex crystallizes in monoclinic space group P21/c, with unit cell dimensions a = 6.7369(4), b = 11.6058(8), c = 17.1379(11) Å, β = 93.823(2)°. The distorted square-planar Cu(II) ion in complex is chelated by one imino N, one phenolic O and one pyridine N atoms of Schiff base ligand and one N atom of azide ion. The electrochemical behavior of the mononuclear copper azido complex was studied with cyclic voltammetry. Tautomer stability of the ligand and the complex has been determined by molecular modeling techniques. It has been concluded that the HL is more stable than its tautomeric form (THL) both as ligand and complex structures.

  18. A theoretical investigation on the structures, densities, detonation properties and pyrolysis mechanism of the nitro derivatives of toluenes

    International Nuclear Information System (INIS)

    The nitro derivatives of toluenes are optimized to obtain their molecular geometries and electronic structures at the DFT-B3LYP/6-31G* level. Detonation properties are evaluated using the modified Kamlet-Jacobs equations based on the calculated densities and heats of formation. It is found that there are good linear relationships between density, detonation velocity, detonation pressure and the number of nitro and methyl groups. Thermal stability and the pyrolysis mechanism of the title compounds are investigated by calculating the bond dissociation energies at the unrestricted B3LYP/6-31G* level. The activation energies of H-transfer reaction are smaller than the BDEs of all bonds and this illustrates that the pyrolysis of the title compounds may be started from the isomerization reaction of H transfer. According to the quantitative standard of energetics and stability as an HEDC (high energy density compound), pentanitrotoluene essentially satisfies this requirement. In addition, we have discussed the effect of the nitro and methyl groups on the static electronic structural parameters and the kinetic parameter.

  19. Theoretical investigation of potential energy surface and bound states for the van der Waals complex Ar–BrCl dimer

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Rui [School of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou (China); Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan (China); Li, Song, E-mail: lsong@yangtzeu.edu.cn [School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou (China); Chen, Shan-Jun; Chen, Yan [School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou (China); Zheng, Li-Min [Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan (China)

    2015-09-08

    Highlights: • A two-dimensional potential for Ar–BrCl is constructed at the CCSD(T) level. • The PES is characterized by three minima and two saddle points between them. • Bound state calculations were carried out for the complex. - Abstract: The intermolecular potential energy surface (PES) of the ground electronic state for the Ar–BrCl dimer is constructed at the CCSD(T) level with the aug-cc-pVQZ basis set and mid-bond functions. The PES is characterized by three minima and two saddle points. The global minimum corresponding to a collinear Ar–BrCl configuration, which has been observed experimentally, is located at R = 4.10 Å and θ = 2.5° with a well depth of −285.207 cm{sup −1}. A nearly T-shaped structure and an anti-linear Ar–ClBr geometry is also predicted. The bound state calculations are preformed to study intermolecular vibrational modes, rotational levels and average structures for the complex. Our transition frequencies, spectroscopic constants and average structures for all isotopomers of the collinear isomer agree well with experimental data. We have also provided pure rotational transitional frequencies for both nearly T-shaped and anti-linear isomers. These results are significant for further experimental investigations of the Ar–BrCl dimer.

  20. Theoretical investigation of the behavior of CuSe2O5 compound in high magnetic fields

    Science.gov (United States)

    Saghafi, Z.; Jahangiri, J.; Mahdavifar, S.; Hadipour, H.; Farjami Shayesteh, S.

    2016-01-01

    Based on the analytical and numerical approaches, we investigate thermodynamic properties of CuSe2O5 compound at high magnetic fields which is a candidate for the strong intra-chain interaction in quasi one-dimensional (1D) quantum magnets. Magnetic behavior of the system can be described by the 1D spin-1/2 XXZ model in the presence of the Dzyaloshinskii-Moriya (DM) interaction. Under these circumstances, there is one quantum critical field in this compound. Below the quantum critical field the spin chain system is in the gapless Luttinger liquid (LL) regime, whereas above it one observes a crossover to the gapped saturation magnetic phase. Indications on the thermodynamic curves confirm the occurrence of such a phase transition. The main characteristics of the LL phase are gapless and spin-spin correlation functions decay algebraic. The effects of zero-temperature quantum phase transition are observed even at rather high temperatures in comparison with the counterpart compounds. In addition, we calculate the Wilson ratio in the model. The Wilson ratio at a fixed temperature remains almost independent of the field in the LL region. In the vicinity of the quantum critical field, the Wilson ratio increases and exhibits anomalous enhancement.